The Sendai Framework for Disaster Risk Reduction 2015-2030 finds that, despite progress in disaster risk reduction over the last decade “evidence indicates that exposure of persons and assets in all countries has increased faster than vulnerability has decreased, thus generating new risk and a steady rise in disaster losses” (p.4, UNISDR 2015). Fostering cooperation among relevant stakeholders and policy makers to “facilitate a science-policy interface for effective decisionmaking in disaster risk management” is required to achieve two priority areas for action, understanding disaster risk and enhancing disaster preparedness (p. 13, p. 23, UNISDR 2015). In other topic areas, the term science-policy interface is used interchangeably with the term boundary organisation. Both terms are usually used refer to systematic collaborative arrangements used to manage the intersection, or boundary, between science and policy domains, with the aim of facilitating the joint construction of knowledge to inform decision-making. Informed by complexity theory, and a constructivist focus on the functions and processes that minimize inevitable tensions between domains, this conceptual framework has become well established in fields where large complex issues have significant economic and political consequences, including environmental management, biodiversity, sustainable development, climate change and public health. To date, however, there has been little application of this framework in the disaster risk reduction field. In this doctoral project the boundary management framework informs an analysis of the research response to the 2010-2011 Canterbury Earthquake Sequence, focusing on the coordination role of New Zealand’s national Natural Hazards Research Platform. The project has two aims. It uses this framework to tell the nuanced story of the way this research coordination role evolved in response to both the complexity of the unfolding post-disaster environment, and to national policy and research developments. Lessons are drawn from this analysis for those planning and implementing arrangements across the science-policy boundary to manage research support for disaster risk reduction decision-making, particularly after disasters. The second aim is to use this case study to test the utility of the boundary management framework in the disaster risk reduction context. This requires that terminology and concepts are explained and translated in terms that make this analysis as accessible as possible across the disciplines, domains and sectors involved in disaster risk reduction. Key findings are that the focus on balance, both within organisations, and between organisations and domains, and the emphasis on systemic effects, patterns and trends, offer an effective and productive alternative to the more traditional focus on individual or organisational performance. Lessons are drawn concerning the application of this framework when planning and implementing boundary organisations in the hazard and disaster risk management context.
Following the Canterbury earthquake sequence of 2010-11, a large and contiguous tract of vacated ‘red zoned’ land lies alongside the lower Ōtākaro / Avon River and is known as the Avon-Ōtākaro Red Zone (AORZ). This is the second report in the Ecological Regeneration Options (ERO) project that addresses future land uses in the AORZ. The purpose of this report is to present results from an assessment of restoration opportunities conducted in April 2017. The objectives of the assessment were to identify potential benefits of ecological restoration activities across both land and water systems in the AORZ and characterise the key options for their implementation. The focus of this report is not to provide specific advice on the methods for achieving specific restoration endpoints per se. This will vary at different sites and scales with a large number of combinations possible. Rather, the emphasis is on providing an overview of the many restoration and regeneration options in their totality across the AORZ. An additional objective is to support their adequate assessment in the identification of optimum land uses and adaptive management practices for the AORZ. Participatory processes may play a useful role in assessment and stakeholder engagement by providing opportunities for social learning and the co-creation of new knowledge. We used a facilitated local knowledge based approach that generated a large quantity of reliable and site specific data in a short period of time. By inviting participation from a wide knowledge-holder network inclusivity is improved in comparison to small-group expert panel approaches. Similar approaches could be applied to other information gathering and assessment needs in the regeneration planning process. Findings from this study represent the most comprehensive set of concepts available to date to address the potential benefits of ecological regeneration in the AORZ. This is a core topic for planning to avoid missed opportunities and opportunity costs. The results identify a wide range of activities that may be applied to generate benefits for Christchurch and beyond, all involving aspects of a potential new ecology in the AORZ. These may be combined at a range of scales to create scenarios, quantify benefits, and explore the potential for synergies between different land use options. A particular challenge is acquiring the information needed within relatively short time frames. Early attention to gathering baseline data, addressing technical knowledge gaps, and developing conceptual frameworks to account for the many spatio-temporal aspects are all key activities that will assist in delivering the best outcomes. Methodologies by which these many facets can be pulled together in quantitative and comparative assessments are the focus of the final report in the ERO series.
Smart cities utilise new and innovative technology to improve the function of the city for governments, citizens and businesses. This thesis offers an in-depth discussion on the concept of the smart city and sets the context of smart cities internationally. It also examines how to improve a smart city through public engagement, as well as, how to implement participatory research in a smart city project to improve the level of engagement of citizens in the planning and implementation of smart projects. This thesis shows how to incentivise behaviour change with smart city technology and projects, through increasing participation in the planning and implementation of smart technology in a city. Meaningful data is created through this process of participation for citizens in the city, by engaging the citizens in the creation of the data, therefore the information created through a smart city project is created by and for the citizens themselves. To improve engagement, a city must understand its specific context and its residents. Using Christchurch, New Zealand, and the Christchurch City Council (CCC) Smart City Project as a case study, this research engages CCC stakeholders in the Smart City Project through a series of interviews, and citizens in Christchurch through a survey and focus groups. A thorough literature review has been conducted, to illuminate the different definitions of the smart city in academia, business and governments respectively, and how these definitions vary from one another. It provides details of a carefully selected set of relevant smart cities internationally and will discuss how the Christchurch Earthquake Sequence of 2010 and 2011 has affected the CCC Smart City Project. The research process, alongside the literature review, shows diverse groups of citizens in the city should be acknowledged in this process. The concept of the smart city is redefined to incorporate the context of Christchurch, its citizens and communities. Community perceptions of smart cities in Christchurch consider the post-disaster environment and this event and subsequent rebuild process should be a focus of the smart city project. The research identified that the CCC needs to focus on participatory approaches in the planning and implementation of smart projects, and community organisations in Christchurch offer an opportunity to understand community perspectives on new smart technology and that projects internationally should consider how the context of the city will affect the participation of its residents. This project offers ideas to influence the behaviour change of citizens through a smart city project. Further research should consider other stakeholders, for instance, innovation and technology-focused business in the city, and to fully engage citizens, future research must continue the process of participatory engagement, and target diverse groups in the city, including but not limited to minority groups, older and younger generations, and those with physical and mental disabilities.
The Canterbury Region is susceptible to a variety of natural hazards, including earthquakes, landslides and climate hazards. Increasing population and tourism within the region is driving development pressures and as more and more development occurs, the risk from natural hazards increases. In order to avoid development occurring in unacceptably vulnerable locations, natural hazard assessments are required. This study is a reconnaissance natural hazard assessment of Lakes Lyndon, Coleridge and Tekapo. There is restricted potential for development at Lake Lyndon, because the land surrounding the lake is owned by the Crown and has a number of development restrictions. However, there is the potential for conservation or recreation-linked development to occur. There is more potential for development at Lake Coleridge. Most of the land surrounding the lake is privately owned and has less development restrictions. The majority of land surrounding Lake Tekapo is divided into Crown-owned pastoral leases, which are protected from development, such as subdivision. However, there are substantial areas around the lake, which are privately owned and, therefore, have potential for development. Earthquake, landslide and climate hazards are the main natural hazards threatening Lakes Lyndon, Coleridge and Tekapo. The lakes are situated in a zone of active earth deformation in which large and relatively frequent earthquakes are produced. A large number of active faults lie within 15 km of each lake, which are capable of producing M7 or larger earthquakes. Ground shaking, liquefaction, landslides, tsunami and seiches are among the consequences of earthquakes, all of which have the potential to cause severe damage to lives, lifelines and infrastructure. Landslides are also common in the landscape surrounding the lakes. The majority of slopes surrounding the lakes are at significant risk from earthquake-induced failure under moderate to strong earthquake shaking. This level of shaking is expected to occur in any 50 year period around Lakes Lyndon and Coleridge, and in any 150 year period around Lake Tekapo. Injuries, fatalities and property damage can occur directly from landslide impact or from indirect effects such as flooding from landslide-generated tsunami or from landslide dam outbreaks. Lakes Lyndon, Coleridge and Tekapo are also susceptible to climate hazards, such as high winds, drought, heavy snowfall and heavy rainfall, which can lead to landslides and flooding. Future climate change due to global warming is most likely going to affect patterns of frequency and magnitudes of extreme weather events, leading to an increase in climate hazards. Before development is permitted around the lakes, it is essential that each of these hazards is considered so that unacceptably vulnerable areas can be avoided.
Natural hazard disasters often have large area-wide impacts, which can cause adverse stress-related mental health outcomes in exposed populations. As a result, increased treatment-seeking may be observed, which puts a strain on the limited public health care resources particularly in the aftermath of a disaster. It is therefore important for public health care planners to know whom to target, but also where and when to initiate intervention programs that promote emotional wellbeing and prevent the development of mental disorders after catastrophic events. A large body of literature assesses factors that predict and mitigate disaster-related mental disorders at various time periods, but the spatial component has rarely been investigated in disaster mental health research. This thesis uses spatial and spatio-temporal analysis techniques to examine when and where higher and lower than expected mood and anxiety symptom treatments occurred in the severely affected Christchurch urban area (New Zealand) after the 2010/11 Canterbury earthquakes. High-risk groups are identified and a possible relationship between exposure to the earthquakes and their physical impacts and mood and anxiety symptom treatments is assessed. The main research aim is to test the hypothesis that more severely affected Christchurch residents were more likely to show mood and anxiety symptoms when seeking treatment than less affected ones, in essence, testing for a dose-response relationship. The data consisted of mood and anxiety symptom treatment information from the New Zealand Ministry of Health’s administrative databases and demographic information from the National Health Index (NHI) register, when combined built a unique and rich source for identifying publically funded stress-related treatments for mood and anxiety symptoms in almost the whole population of the study area. The Christchurch urban area within the Christchurch City Council (CCC) boundary was the area of interest in which spatial variations in these treatments were assessed. Spatial and spatio-temporal analyses were done by applying retrospective space-time and spatial variation in temporal trends analysis using SaTScan™ software, and Bayesian hierarchical modelling techniques for disease mapping using WinBUGS software. The thesis identified an overall earthquake-exposure effect on mood and anxiety symptom treatments among Christchurch residents in the context of the earthquakes as they experienced stronger increases in the risk of being treated especially shortly after the catastrophic 2011 Christchurch earthquake compared to the rest of New Zealand. High-risk groups included females, elderly, children and those with a pre-existing mental illness with elderly and children especially at-risk in the context of the earthquakes. Looking at the spatio-temporal distribution of mood and anxiety symptom treatments in the Christchurch urban area, a high rates cluster ranging from the severely affected central city to the southeast was found post-disaster. Analysing residential exposure to various earthquake impacts found that living in closer proximity to more affected areas was identified as a risk factor for mood and anxiety symptom treatments, which largely confirms a dose-response relationship between level of affectedness and mood and anxiety symptom treatments. However, little changes in the spatial distribution of mood and anxiety symptom treatments occurred in the Christchurch urban area over time indicating that these results may have been biased by pre-existing spatial disparities. Additionally, the post-disaster mobility activity from severely affected eastern to the generally less affected western and northern parts of the city seemed to have played an important role as the strongest increases in treatment rates occurred in less affected northern areas of the city, whereas the severely affected eastern areas tended to show the lowest increases. An investigation into the different effects of mobility confirmed that within-city movers and temporary relocatees were generally more likely to receive care or treatment for mood or anxiety symptoms, but moving within the city was identified as a protective factor over time. In contrast, moving out of the city from minor, moderately or severely damaged plain areas of the city, which are generally less affluent than Port Hills areas, was identified as a risk factor in the second year post-disaster. Moreover, residents from less damaged plain areas of the city showed a decrease in the likelihood of receiving care or treatment for mood or anxiety symptoms compared to those from undamaged plain areas over time, which also contradicts a possible dose-response relationship. Finally, the effects of the social and physical environment, as well as community resilience on mood and anxiety symptom treatments among long-term stayers from Christchurch communities indicate an exacerbation of pre-existing mood and anxiety symptom treatment disparities in the city, whereas exposure to ‘felt’ earthquake intensities did not show a statistically significant effect. The findings of this thesis highlight the complex relationship between different levels of exposure to a severe natural disaster and adverse mental health outcomes in a severely affected region. It is one of the few studies that have access to area-wide health and impact information, are able to do a pre-disaster / post-disaster comparison and track their sample population to apply spatial and spatio-temporal analysis techniques for exposure assessment. Thus, this thesis enhances knowledge about the spatio-temporal distribution of adverse mental health outcomes in the context of a severe natural disaster and informs public health care planners, not only about high-risk groups, but also where and when to target health interventions. The results indicate that such programs should broadly target residents living in more affected areas as they are likely to face daily hardship by living in a disrupted environment and may have already been the most vulnerable ones before the disaster. Special attention should be focussed on women, elderly, children and people with pre-existing mental illnesses as they are most likely to receive care or treatment for stress-related mental health symptoms. Moreover, permanent relocatees from affected areas and temporarily relocatees shortly after the disaster may need special attention as they face additional stressors due to the relocation that may lead to the development of adverse mental health outcomes needing treatment.
In recent years, rocking isolation has become an effective approach to improve seismic performance of steel and reinforced concrete structures. These systems can mitigate structural damage through rigid body displacement and thus relatively low requirements for structural ductility, which can significantly improve seismic resilience of structures and reduce repairing costs after strong earthquakes. A number of base rocking structural systems with only a single rocking interface have been proposed. However, these systems can have significant high mode effect for high rise structures due to the single rocking interface. This RObust BUilding SysTem (ROBUST) project is a collaborative China-New Zealand project sponsored by the International Joint Research Laboratory of Earthquake Engineering (ILEE), Tongji University, and a number of agencies and universities within New Zealand including the BRANZ, Comflor, Earthquake Commission, HERA, QuakeCoRE, QuakeCentre, University of Auckland, and the University of Canterbury. A number of structural configurations will be tested [1, 2], and non-structural elements including ceilings, infilling walls, glazed curtain walls, precast concrete panels, piping system will also be tested in this project [3]. Within this study, a multiple rocking column steel structural system was proposed and investigated mainly by Tongji team with assistance of NZ members. The concept of rocking column system initiates from the structure of Chinese ancient wooden pagoda. In some of Chinese wooden pagodas, there are continuous core columns hanged only at the top of each pagoda, which is not connected to each stories. This core column can effectively avoid collapse of the whole structure under large storey drifts. Likewise, there are also central continuous columns in the newly proposed steel rocking column system, which can avoid weak story failure mechanism and make story drifts more uniform. In the proposed rocking column system, the structure can switch between an elastic rigidly connected moment resisting frame and a controlled rocking column system when subjected to strong ground motion excitations. The main seismic energy can be dissipated by asymmetric friction beam–column connections, thereby effectively reducing residual displacement of the structure under seismic loading without causing excessive damage to structural members. Re–centering of the structure is provided not only by gravity load carried by rocking columns, but also by mould coil springs. To investigate dynamic properties of the proposed system under different levels of ground excitations, a full-scale threestory steel rocking column structural system with central continuous columns is to be tested using the International joint research Laboratory of Earthquake Engineering (ILEE) facilities, Shanghai, China and an analytical model is established. A finite element model is also developed using ABAQUS to simulate the structural dynamic responses. The rocking column system proposed in this paper is shown to produce resilient design with quick repair or replacement.
Rising disaster losses, growth in global migration, migrant labour trends, and increasingly diverse populations have serious implications for disaster resilience around the world. These issues are of particular concern in New Zealand, which is highly exposed to disaster risk and has the highest proportion of migrant workers to national population in the OECD. Since there has been no research conducted into this issue in New Zealand to date, greater understanding of the social capital used by migrant workers in specific New Zealand contexts is needed to inform more targeted and inclusive disaster risk management approaches. A New Zealand case study is used to investigate the extent and types of social capital and levels of disaster risk awareness reported by members of three Filipino migrant workers organisations catering to dairy farm, construction and aged care workers in different urban and rural Canterbury districts. Findings from (3) semi-structured interviews and (3) focus groups include consistently high reliance on bonding capital and low levels of bridging capital across all three organisations and industry sectors, and in both urban and rural contexts. The transitory, precarious residential status conveyed by temporary work visas, and the difficulty of building bridging capital with host communities has contributed to this heavy reliance on bonding capital. Social media was essential to connect workers with family and friends in other countries, while Filipino migrant workers organisations provided members with valuable access to industry and district-specific networks of other Filipino migrant workers. Linking capital varied between the three organisations, with members of the organisation set up to advocate for dairy farm workers reporting the highest levels of linking capital. Factors influencing the capacity of workers organisations to develop linking capital appeared to include motivation (establishment objectives), length of time since establishment, support from government and industry groups, urban-rural context, income levels and gender. Although aware of publicity around earthquake and tsunami risk in the Canterbury region, participants were less aware of flood risk, and expressed fatalistic attitudes to disaster risk. Workers organisations offer a valuable potential interface between CDEM Group activities and migrant worker communities, since organisation leaders were interested in accessing government support to participate (with and on behalf of members) in disaster risk planning at district and regional level. With the potential to increase disaster resilience among these vulnerable, hard to reach communities, such participation could also help to build capacity across workers organisations (within Canterbury and across the country) to develop linking capital at national, as well as regional level. However, these links will also depend on greater government and industry commitment to providing more targeted and appropriate support for migrant workers, including consideration of the cultural qualifications of staff tasked with liaising with this community.
As the future of the world’s oil reserves becomes progressively more uncertain, it is becoming increasingly important that steps are taken to ensure that there are viable, attractive alternatives to travel by private motor vehicle. As with many of New Zealand’s major urban centres, Christchurch is still exceptionally reliant on private motor vehicles; although a significant proportion of the population indicate that they would like to cycle more, cycling is still an underutilised mode of transport. Following a series of fatal earthquakes that struck the city in 2010 and 2011, there has been the need to significantly redevelop much of the city’s horizontal infrastructure – subsequently providing the perfect platform for significant changes to be made to the road network. Many of the key planning frameworks governing the rebuild process have identified the need to improve Christchurch’s cycling facilities in order to boost cycling numbers and cyclist safety. The importance of considering future growth and travel patterns when planning for transport infrastructure has been highlighted extensively throughout literature. Accordingly, this study sought to identify areas where future cycle infrastructure development would be advantageous based on a number of population and employment projections, and likely future travel patterns throughout the city. Through the use of extensive GIS analysis, future population growth, employment and travel patterns for Christchurch city were examined in order to attain an understanding of where the current proposed major cycleways network could be improved, or extended. A range of data and network analysis were used to derive likely travel patterns throughout Christchurch in 2041. Trips were derived twice, once with a focus on simply finding the shortest route between each origin and destination, and then again with a focus on cyclist safety and areas where cyclists were unlikely to travel. It was found that although the proposed major cycleways network represents a significant step towards improving the cycling environment in Christchurch, there are areas of the city that will not be well serviced by the current proposed network in 2041. These include a number of key residential growth areas such as Halswell, Belfast and Prestons, along with a number of noteworthy key travel zones, particularly in areas close to the central city and key employment areas. Using network analysis, areas where improvements or extensions to the proposed network would be most beneficial were identified, and a number of potential extensions in a variety of areas throughout the city were added to the network of cycle ways. Although it has been found that filling small gaps in the network can have considerable positive outcomes, results from the prioritisation analysis suggested that initially in Christchurch demand is likely to be for more substantial extensions to the proposed major cycleways network.
<b>New Zealand has experienced several strong earthquakes in its history. While an earthquake cannot be prevented from occurring, planning can reduce its consequences when it does occur. This dissertation research examines various aspects of disaster risk management policy in Aotearoa New Zealand.</b>
Chapter 2 develops a method to rank and prioritise high-rise buildings for seismic retrofitting in Wellington, the earthquake-prone capital city of New Zealand. These buildings pose risks to Wellington’s long-term seismic resilience that are of clear concern to current and future policymakers. The prioritization strategy we propose, based on multi-criteria decision analysis (MCDA) methods, considers a variety of data on each building, including not only its structural characteristics, but also its location, its economic value to the city, and its social importance to the community around it. The study demonstrates how different measures, within four general criteria – life safety, geo-spatial location of the building, its economic role, and its socio-cultural role – can be operationalized into a viable framework for determining retrofitting/demolition policy priorities.
Chapter 3 and chapter 4 analyse the Residential Red Zone (RRR) program that was implemented in Christchurch after the 2011 earthquake. In the program, approximately 8,000 homeowners were told that their homes were no longer permittable, and they were bought by the government (through the Canterbury Earthquake Recovery Authority).
Chapter 3 examines the subjective wellbeing of the RRR residents (around 16000 people) after they were forced to move. We consider three indicators of subjective wellbeing: quality of life, stress, and emotional wellbeing. We found that demographic factors, health conditions, and the type of government compensation the residents accepted, were all significant determinants of the wellbeing of the Red Zone residents. More social relations, better financial circumstances, and the perception of better government communication were also all associated positively with a higher quality of life, less stress, and higher emotional wellbeing.
Chapter 4 concentrates on the impact of this managed retreat program on RRR residents’ income. We use individual-level comprehensive, administrative, panel data from Canterbury, and difference in difference evaluation method to explore the effects of displacement on Red Zone residential residents. We found that compared to non-relocated neighbours, the displaced people experience a significant initial decrease in their wages and salaries, and their total income. The impacts vary with time spent in the Red Zone and when they moved away. Wages and salaries of those who were red-zoned and moved in 2011 were reduced by 8%, and 5.4% for those who moved in 2012. Females faced greater decreases in wages and salaries, and total income, than males. There were no discernible impacts of the relocation on people’s self-employment income.
The nonlinear dynamic soil-foundation-structure interaction (SFSI) can signifi cantly affect the seismic response of buildings, causing additional deformation modes, damage and repair costs. Because of nonlinear foundation behaviour and interactions, the seismic demand on the superstructure may considerably change, and also permanent deformations at the foundation level may occur. Although SFSI effects may be benefi cial to the superstructure performance, any advantage would be of little structural value unless the phenomenon can be reliably controlled and exploited. Detrimental SFSI effects may also occur, including acceleration and displacement response ampli cation and differential settlements, which would be unconservative to neglect. The lack of proper understanding of the phenomenon and the limited available simpli ed tools accounting for SFSI have been major obstacles to the implementation of integrated design and assessment procedures into the everyday practice. In this study concepts, ideas and practical tools (inelastic spectra) for the seismic design and assessment of integrated foundation-superstructure systems are presented, with the aim to explicitly consider the impact of nonlinearities occurring at the soil-foundation interface on the building response within an integrated approach, where the foundation soil and superstructure are considered as part of an integrated system when evaluating the seismic response, working synergically for the achievement of a target global performance. A conceptual performance-based framework for the seismic design and assessment of integrated foundation-superstructure systems is developed. The framework is based on the use of peak and residual response parameters for both the superstructure and the foundation, which are then combined to produce the system performance matrix. Each performance matrix allows for worsening of the performance when different contributions are combined. An attempt is made to test the framework by using case histories from the 2011 Christchurch earthquake, which are previously shown to have been severely affected by nonlinear SFSI. The application highlights the framework sensitivity to the adopted performance limit states, which must be realistic for a reliable evaluation of the system performance. Constant ductility and constant strength inelastic spectra are generated for nonlinear SFSI systems (SDOF nonlinear superstructure and 3DOF foundation allowing for uplift and soil yielding), representing multistorey RC buildings with shallow rigid foundations supported by cohesive soils. Different ductilities/strengths, hysteretic rules (Bi-linear, Takeda and Flag-Shape), soil stiffness and strength and bearing capacity factors are considered. Footings and raft foundations are investigated, characterized respectively by constant (3 and 8) and typically large bearing capacity factors. It is confi rmed that when SFSI is considered, the superstructure yielding force needed to satisfy a target ductility for a new building changes, and that similarly, for an existing building, the ductility demand on a building of a given strength varies. The extent of change of seismic response with respect to xed-base (FB) conditions depends on the class of soils considered, and on the bearing capacity factor (SF). For SF equal to 3, the stiffer soils enhance the nonlinear rotational foundation behaviour and are associated with reduced settlement, while the softer ones are associated with increased settlement response but not signi ficant rotational behaviour. On average terms, for the simplifi ed models considered, SFSI is found to be bene cial to the superstructure performance in terms of acceleration and superstructure displacement demand, although exceptions are recorded due to ground motion variability. Conversely, in terms of total displacement, a signi cant response increase is observed. The larger the bearing capacity factor, the more the SFSI response approaches the FB system. For raft foundation buildings, characterized by large bearing capacity factors, the impact of foundation response is mostly elastic, and the system on average approaches FB conditions. Well de fined displacement participation factors to the peak total lateral displacement are observed for the different contributions (i.e. peak foundation rotation and translation and superstructure displacement). While the superstructure and foundation rotation show compensating trends, the foundation translation contribution varies as a function of the moment-to-shear ratio, becoming negligible in the medium-to-long periods. The longer the superstructure FB period, the less the foundation response is signifi cant. The larger the excitation level and the less ductile the superstructure, the larger the foundation contribution to the total lateral displacement, and the less the superstructure contribution. In terms of hysteretic behaviour, its impact is larger when the superstructure response is more signifi cant, i.e. for the softer/weaker soils and larger ductilities. Particularly, for the Flag Shape rule, larger superstructure displacement participation factors and smaller foundation contributions are recorded. In terms of residual displacements, the total residual-to-maximum ratios are similar in amplitudes and trends to the corresponding FB system responses, with the foundation and superstructure contributions showing complementary trends. The impact of nonlinear SFSI is especially important for the Flag Shape hysteresis rule, which would not otherwise suffer of any permanent deformations. By using the generated peak and residual inelastic spectra (i.e. inelastic acceleration/ displacement modifi cation factor spectra, and/or participation factor and residual spectra), conceptual simplifi ed procedures for the seismic design and assessment of integrated foundation-superstructure systems are presented. The residual displacements at both the superstructure and foundation levels are explicitly considered. Both the force- and displacement-based approaches are explored. The procedures are de fined to be complementary to the previously proposed integrated performance-based framework. The use of participation factor spectra allows the designer to easily visualize the response of the system components, and could assist the decision making process of both the design and assessment of SFSI systems. The presented numerical results have been obtained using simpli ed models, assuming rigid foundation behaviour and neglecting P-Delta effects. The consideration of more complex systems including asymmetry in stiffness, mass, axial load and ground conditions with a exible foundation layout would highlight detrimental SFSI effects as related to induced differential settlements, while accounting for PDelta effects would further amplify the displacement response. Also, the adopted acceleration records were selected and scaled to match conventional design spectra, thus not representing any response ampli cation in the medium-to-long period range which could as well cause detrimental SFSI effects. While these limitations should be the subject of further research, this study makes a step forward to the understanding of SFSI phenomenon and its incorporation into performance-based design/assessment considerations.
Background: Up to 6 years after the 2011 Christchurch earthquakes, approximately one-third of parents in the Christchurch region reported difficulties managing the continuously high levels of distress their children were experiencing. In response, an app named Kākano was co-designed with parents to help them better support their children’s mental health. Objective: The objective of this study was to evaluate the acceptability, feasibility, and effectiveness of Kākano, a mobile parenting app to increase parental confidence in supporting children struggling with their mental health. Methods: A cluster-randomized delayed access controlled trial was carried out in the Christchurch region between July 2019 and January 2020. Parents were recruited through schools and block randomized to receive immediate or delayed access to Kākano. Participants were given access to the Kākano app for 4 weeks and encouraged to use it weekly. Web-based pre- and postintervention measurements were undertaken. Results: A total of 231 participants enrolled in the Kākano trial, with 205 (88.7%) participants completing baseline measures and being randomized (101 in the intervention group and 104 in the delayed access control group). Of these, 41 (20%) provided full outcome data, of which 19 (18.2%) were for delayed access and 21 (20.8%) were for the immediate Kākano intervention. Among those retained in the trial, there was a significant difference in the mean change between groups favoring Kākano in the brief parenting assessment (F1,39=7, P=.012) but not in the Short Warwick-Edinburgh Mental Well-being Scale (F1,39=2.9, P=.099), parenting self-efficacy (F1,39=0.1, P=.805), family cohesion (F1,39=0.4, P=.538), or parenting sense of confidence (F1,40=0.6, P=.457). Waitlisted participants who completed the app after the waitlist period showed similar trends for the outcome measures with significant changes in the brief assessment of parenting and the Short Warwick-Edinburgh Mental Well-being Scale. No relationship between the level of app usage and outcome was found. Although the app was designed with parents, the low rate of completion of the trial was disappointing. Conclusions: Kākano is an app co-designed with parents to help manage their children’s mental health. There was a high rate of attrition, as is often seen in digital health interventions. However, for those who did complete the intervention, there was some indication of improved parental well-being and self-assessed parenting. Preliminary indications from this trial show that Kākano has promising acceptability, feasibility, and effectiveness, but further investigation is warranted. Trial Registration: Australia New Zealand Clinical Trials Registry ACTRN12619001040156; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377824&isReview=true
High demolition rates were observed in New Zealand after the 2010-2011 Canterbury Earthquake Sequence despite the success of modern seismic design standards to achieve required performance objectives such as life safety and collapse prevention. Approximately 60% of the multi-storey reinforced concrete (RC) buildings in the Christchurch Central Business District were demolished after these earthquakes, even when only minor structural damage was present. Several factors influenced the decision of demolition instead of repair, one of them being the uncertainty of the seismic capacity of a damaged structure. To provide more insight into this topic, the investigation conducted in this thesis evaluated the residual capacity of moderately damaged RC walls and the effectiveness of repair techniques to restore the seismic performance of heavily damaged RC walls. The research outcome provided insights for developing guidelines for post-earthquake assessment of earthquake-damaged RC structures. The methodology used to conduct the investigation was through an experimental program divided into two phases. During the first phase, two walls were subjected to different types of pre-cyclic loading to represent the damaged condition from a prior earthquake, and a third wall represented a repair scenario with the damaged wall being repaired using epoxy injection and repair mortar after the pre-cyclic loading. Comparisons of these test walls to a control undamaged wall identified significant reductions in the stiffness of the damaged walls and a partial recovery in the wall stiffness achieved following epoxy injection. Visual damage that included distributed horizontal and diagonal cracks and spalling of the cover concrete did not affect the residual strength or displacement capacity of the walls. However, evidence of buckling of the longitudinal reinforcement during the pre-cyclic loading resulted in a slight reduction in strength recovery and a significant reduction in the displacement capacity of the damaged walls. Additional experimental programs from the literature were used to provide recommendations for modelling the response of moderately damaged RC walls and to identify a threshold that represented a potential reduction in the residual strength and displacement capacity of damaged RC walls in future earthquakes. The second phase of the experimental program conducted in this thesis addressed the replacement of concrete and reinforcing steel as repair techniques for heavily damaged RC walls. Two walls were repaired by replacing the damaged concrete and using welded connections to connect new reinforcing bars with existing bars. Different locations of the welded connections were investigated in the repaired walls to study the impact of these discontinuities at the critical section. No significant changes were observed in the stiffness, strength, and displacement capacity of the repaired walls compared to the benchmark undamaged wall. Differences in the local behaviour at the critical section were observed in one of the walls but did not impact the global response. The results of these two repaired walls were combined with other experimental programs found in the literature to assemble a database of repaired RC walls. Qualitative and quantitative analyses identified trends across various parameters, including wall types, damage before repair, and repair techniques implemented. The primary outcome of the database analysis was recommendations for concrete and reinforcing steel replacement to restore the strength and displacement capacity of heavily damaged RC walls.
The November 2016 MW 7.8 Kaikōura Earthquake initiated beneath the North Culverden basin on The Humps fault and propagated north-eastwards, rupturing at least 17 faults along a cumulative length of ~180 km. The geomorphic expression of The Humps Fault across the Emu Plains, along the NW margin of Culverden basin, comprises a series of near-parallel strands separated by up to 3 km across strike. The various strands strike east to east-northeast and have been projected to mainly dip steeply to the south in seismic data (~80°). In this area, the fault predominantly accommodates right-lateral slip, with uplift and subsidence confined to releasing and restraining bends and step-overs at a range of scales. The Kaikōura event ruptured pre-existing fault scarps along the Emu Plains, which had been partly identified prior to the earthquake. Geomorphology and faulting expression of The Humps Fault on The Emu Plains was mapped, along with faulting related structures which did not rupture in the 2016 earthquake. Fault ruptures strands are combined into sections and the kinematic deformation of sections analysed to provide a moment tensor fault plane solution. This fault plane solution is consistent with the regional principal horizontal shortening direction (PHS) of ~115°, similar to seismic focal mechanism solutions of some of the nearby aftershocks of the Kaikōura earthquake, and similar to the adjacent Hope Fault. To constrain the timing of paleoseismic events, a trench was excavated across the fault where it crossed a late Quaternary alluvial fan. Mapping of stratigraphy exposed in the trench walls, and dating of variably deformed strata, constrains the pre-historic earthquake event history at the trench site. The available data provides evidence for at least three paleo-earthquakes within the last 15.1 ka, with a possible fourth (penultimate) event. These events are estimated to have occurred at 7.7-10.3 ka, 10.3-14.8 ka, and one or more events that are older than ~15.1 ka. Some evidence suggests an additional penultimate event between 1850 C.E and 7.7 ka. Time-integrated slip-rates at three locations on the fault are measured using paleo-channels as piercing points. These sites give horizontal slip rates of 0.57 ± 0.1 mm/year, 0.49 ± 0.1 mm/year and one site constrains a minimum of between 0.1 - 0.4 mm/year. Two vertical slip-rates are calculated to be constrained to a maximum of 0.2 ± 0.02 mm/year at one site and between 0.02 and 0.1 mm/year at another site. Prior to this study, The Humps fault had only been partially documented in reconnaissance level mapping in the district, and no previous paleoseismic or slip rate data had been reported. This project has provided a detailed fault zone tectonic geomorphic map and established new slip-rate and paleoseismic data. The results highlight that The Humps fault plays an important role in regional seismicity and in accommodating plate boundary deformation across the North Canterbury region.
This thesis documents the development and demonstration of an assessment method for analysing earthquake-related damage to concrete waste water gravity pipes in Christchurch, New Zealand, following the 2010-2011 Canterbury Earthquake Sequence (CES). The method is intended to be internationally adaptable to assist territorial local authorities with improving lifelines infrastructure disaster impact assessment and improvements in resilience. This is achieved through the provision of high-resolution, localised damage data, which demonstrate earthquake impacts along the pipe length. The insights gained will assist decision making and the prioritisation of resources following earthquake events to quickly and efficiently restore network function and reduce community impacts. The method involved obtaining a selection of 55 reinforced concrete gravity waste water pipes with available Closed-Circuit Television (CCTV) inspection footage filmed before and after the CES. The pipes were assessed by reviewing the recordings, and damage was mapped to the nearest metre along the pipe length using Geographic Information Systems. An established, systematic coding process was used for reporting the nature and severity of the observed damage, and to differentiate between pre-existing and new damage resulting from the CES. The damage items were overlaid with geospatial data such as Light Detection and Ranging (LiDAR)-derived ground deformation data, Liquefaction Resistance Index data and seismic ground motion data (Peak Ground acceleration and Peak Ground Velocity) to identify potential relationships between these parameters and pipe performance. Initial assessment outcomes for the pipe selection revealed that main pipe joints and lateral connections were more vulnerable than the pipe body during a seismic event. Smaller diameter pipes may also be more vulnerable than larger pipes during a seismic event. Obvious differential ground movement resulted in increased local damage observations in many cases, however this was not obvious for all pipes. Pipes with older installation ages exhibited more overall damage prior to a seismic event, which is likely attributable to increased chemical and biological deterioration. However, no evidence was found relating pipe age to performance during a seismic event. No evidence was found linking levels of pre-CES damage in a pipe with subsequent seismic performance, and seismic performance with liquefaction resistance or magnitude of seismic ground motion. The results reported are of limited application due to the small demonstration sample size, but reveal the additional level of detail and insight possible using the method presented in this thesis over existing assessment methods, especially in relation to high resolution variations along the length of the pipe such as localised ground deformations evidenced by LiDAR. The results may be improved by studying a larger and more diverse sample pool, automating data collection and input processes in order to improve efficiency and consider additional input such as pipe dip and cumulative damage over a large distance. The method is dependent on comprehensive and accurate pre-event CCTV assessments and LIDAR data so that post-event data could be compared. It is proposed that local territorial authorities should prioritise acquiring this information as a first important step towards improving the seismic resilience of a gravity waste water pipe network.
Recent global tsunami events have highlighted the importance of effective tsunami risk management strategies (including land-use planning, structural and natural defences, warning systems, education and evacuation measures). However, the rarity of tsunami means that empirical data concerning reactions to tsunami warnings and tsunami evacuation behaviour is rare when compared to findings about evacuations to avoid other sources of hazard. To date empirical research into tsunami evacuations has focused on evacuation rates, rather than other aspects of the evacuation process. More knowledge is required about responses to warnings, pre-evacuation actions, evacuation dynamics and the return home after evacuations. Tsunami evacuation modelling has the potential to inform evidence-based tsunami risk planning and response. However to date tsunami evacuation models have largely focused on timings of evacuations, rather than evacuation behaviours. This Masters research uses a New Zealand case study to reduce both of these knowledge gaps. Qualitative survey data was gathered from populations across coastal communities in Banks Peninsula and Christchurch, New Zealand, required to evacuate due to the tsunami generated by the November 14th 2016 Kaikōura Earthquake. Survey questions asked about reactions to tsunami warnings, actions taken prior to evacuating and movements during the 2016 tsunami evacuation. This data was analysed to characterise trends and identify factors that influenced evacuation actions and behaviour. Finally, it was used to develop an evacuation model for Banks Peninsula. Where appropriate, the modelling inputs were informed by the survey data. Three key findings were identified from the results of the evacuation behaviour survey. Although 38% of the total survey respondents identified the earthquake shaking as a natural cue for the tsunami, most relied on receiving official warnings, including sirens, to prompt evacuations. Respondents sought further official information to inform their evacuation decisions, with 39% of respondents delaying their evacuation in order to do so. Finally, 96% of total respondents evacuated by car. This led to congestion, particularly in more densely populated Christchurch city suburbs. Prior to this research, evacuation modelling had not been completed for Banks Peninsula. The results of the modelling showed that if evacuees know how to respond to tsunami warnings and where and how to evacuate, there are no issues. However, if there are poor conditions, including if people do not evacuate immediately, if there are issues with the roading network, or if people do not know where or how to evacuate, evacuation times increase with there being more bottlenecks leading out of the evacuation zones. The results of this thesis highlight the importance of effective tsunami education and evacuation planning. Reducing exposure to tsunami risk through prompt evacuation relies on knowledge of how to interpret tsunami warnings, and when, where and how to evacuate. Recommendations from this research outline the need for public education and engagement, and the incorporation of evacuation signage, information boards and evacuation drills. Overall these findings provide more comprehensive picture of tsunami evacuation behaviour and decision making based on empirical data from a recent evacuation, which can be used to improve tsunami risk management strategies. This empirical data can also be used to inform evacuation modelling to improve the accuracy and realism of the evacuation models.
Access to clean and safe drinking water is a fundamental human requirement. However, in many areas of the world natural water sources have been impacted by a variety of biological and chemical contaminants. The ingestion of these contaminants may cause acute or chronic health problems. To prevent such illnesses, many technologies have been developed to treat, disinfect and supply safe drinking water quality. However, despite these advancements, water supply distribution systems can adversely affect the drinking water quality before it is delivered to consumers. The primary aim of this research was to investigate the effect that water distribution systems may have on household drinking water quality in Christchurch, New Zealand and Addis Ababa, Ethiopia. Water samples were collected from the source water and household taps in both cities. The samples were then tested for various physical, chemical and biological water quality parameters. The data collected was also used to determine if water samples complied with national drinking water quality standards in both countries. Independent samples t-test statistical analyses were also performed to determine if water quality measured in the samples collected from the source and household taps was significantly different. Water quality did not vary considerably between the source and tap water samples collected in Christchurch City. No bacteria were detected in any sample. However, the pH and total iron concentrations measured in source and tap water samples were found to be significantly different. The lower pH values measured in tap water samples suggests that corrosion may be taking place in the distribution system. No water samples transgressed the Drinking Water Standards for New Zealand (DWSNZ) MAVs. Monitoring data collected by the Christchurch City Council (CCC) was also used for comparison. A number of pH, turbidity and total iron concentration measurements collected by the CCC in 2011 were found to exceed the guideline values. This is likely due to structural damage to the source wells and pump-stations that occurred during the 2011 earthquake events. Overall, it was concluded that the distribution system does not adversely affect the quality of Christchurch City’s household drinking water. The water quality measured in samples collected from the source (LTP) and household taps in Addis Ababa was found to vary considerably. The water collected from the source complied with the Ethiopian (WHO) drinking water quality standards. However, tap water samples were often found to have degraded water quality for the physical and chemical parameters tested. This was especially the case after supply interruption and reinstatement events. Bacteria were also often detected in household tap water samples. The results from this study indicate that water supply disruptions may result in degraded water quality. This may be due to a drop in pipeline pressure and the intrusion of contaminants through the leaky and cross-connected pipes in the distribution network. This adversely affects the drinking water quality in Addis Ababa.
This thesis documents the development and demonstration of an assessment method for analysing earthquake-related damage to concrete waste water gravity pipes in Christchurch, New Zealand, following the 2010-2011 Canterbury Earthquake Sequence (CES). The method is intended to be internationally adaptable to assist territorial local authorities with improving lifelines infrastructure disaster impact assessment and improvements in resilience. This is achieved through the provision of high-resolution, localised damage data, which demonstrate earthquake impacts along the pipe length. The insights gained will assist decision making and the prioritisation of resources following earthquake events to quickly and efficiently restore network function and reduce community impacts. The method involved obtaining a selection of 55 reinforced concrete gravity waste water pipes with available Closed-Circuit Television (CCTV) inspection footage filmed before and after the CES. The pipes were assessed by reviewing the recordings, and damage was mapped to the nearest metre along the pipe length using Geographic Information Systems. An established, systematic coding process was used for reporting the nature and severity of the observed damage, and to differentiate between pre-existing and new damage resulting from the CES. The damage items were overlaid with geospatial data such as Light Detection and Ranging (LiDAR)-derived ground deformation data, Liquefaction Resistance Index data and seismic ground motion data (Peak Ground acceleration and Peak Ground Velocity) to identify potential relationships between these parameters and pipe performance. Initial assessment outcomes for the pipe selection revealed that main pipe joints and lateral connections were more vulnerable than the pipe body during a seismic event. Smaller diameter pipes may also be more vulnerable than larger pipes during a seismic event. Obvious differential ground movement resulted in increased local damage observations in many cases, however this was not obvious for all pipes. Pipes with older installation ages exhibited more overall damage prior to a seismic event, which is likely attributable to increased chemical and biological deterioration. However, no evidence was found relating pipe age to performance during a seismic event. No evidence was found linking levels of pre-CES damage in a pipe with subsequent seismic performance, and seismic performance with liquefaction resistance or magnitude of seismic ground motion. The results reported are of limited application due to the small demonstration sample size, but reveal the additional level of detail and insight possible using the method presented in this thesis over existing assessment methods, especially in relation to high resolution variations along the length of the pipe such as localised ground deformations evidenced by LiDAR. The results may be improved by studying a larger and more diverse sample pool, automating data collection and input processes in order to improve efficiency and consider additional input such as pipe dip and cumulative damage over a large distance. The method is dependent on comprehensive and accurate pre-event CCTV assessments and LIDAR data so that post-event data could be compared. It is proposed that local territorial authorities should prioritise acquiring this information as a first important step towards improving the seismic resilience of a gravity waste water pipe network.
Structures of the Lowry Peaks Range - Waikari Valley district are complex. The majority comprise three members of a predominantly WSW -ENE striking major northwards-directed, leading edge imbricate thrust system, with associated angular, asymmetric fault-propagation folds. This system forms anomalously within a large NESW trending belt of structures characterising the entire east coast of north Canterbury, both onshore and offshore and terminates westwards against N-S striking, east facing fold-fault zone. The objectives of this study address the origin, geometry and kinematics of the interaction between these diversely trending systems. Stratigraphy and small-scale structures denote three periods of deformation, namely: i) Middle Cretaceous deformation of the basement rocks, ii) weak Middle Oligocene deformation associated with the inception of the plate boundary through the South Island, and iii) major Pliocene - Recent deformation that formed the majority of the above-mentioned structures. Stress tensor analyses within competent basement and limestone cover rocks suggest two sets of sub-horizontal compression, NE-SW and NW-SE, the former likely to relate to a localised earlier period of deformation, now overprinted by the latter. NW-SE oriented sub-horizontal compression correlates well with results from other parts of north Canterbury. The result of NW-SE compression on the W-E to WSW-ENE striking structures is a large component of oblique motion, which is manifest in four ways: i) movement on two, differently oriented splays rather than a single fault strand, ii) the development of a sinuous trace for a number of the major folds, whereby the ends are oriented normal to the compression direction, the centres parallel to the strike of the faults, iii) the development of a number of cross-folds, striking NNE-SSW and iv) the apparently recent development of a strike-slip component on at least one of the major thrust faults. The origin of the W-E, or WSW-ENE striking structures may be reactivation of Late Cretaceous faults, stratigraphic evidence for the existence of a "structural high" (the Hurunui High) over the majority of the area in the Late Cretaceous to Early Eocene times suggests the formation of a W-E trending horst structure, with a corresponding asymmetric graben to the south. The junction of WSW-ENE trending structures with N-S trending structures to the west centres on an alluvial-filled depression, Waikari Flat, into which the structures of the WSW-ENE trending imbricate thrust system plunge, locally curling to the SW at their ends to link with N-S trending structures to the south. Roof thrusting on two orientations, W-E and N-S, towards to SE is currently occurring above these structures. Currently the area is not highly seismically active, although a magnitude ~6.4 Ms earthquake in historic times has been recorded. The effects of tectonics on the drainage of the area does suggest that the majority of the systems, are still potentially active, albeit moving at a comparatively slow rate. The majority of the recent motion appears to be concentrated on the roof-thrusting occurring in Waikari Flat, and uplift along the Lowry Peaks Fault System. Increasing amounts of secondary movement on back-thrusts and cross fractures is also implied for western ends of the major imbricate thrust system. In contrast, the southern-most fault system appears to be largely sustaining dextral strike-slip motion, with some local folding in central portions.
Following the Mw 6.2 Christchurch Earthquake on 22 February 2011, extensive ground cracking in loessial soils was reported in some areas of the Port Hills, southeast of central Christchurch. This study was undertaken to investigate the mechanisms of earthquake-induced ground damage on the eastern side of the Hillsborough Valley. A zone of extensional cracking up to 40m wide and 600m long was identified along the eastern foot-slope, accompanied by compression features and spring formation at the toe of the slope. An engineering geological and geomorphological model was developed for the eastern Hillsborough Valley that incorporates geotechnical investigation data sourced from the Canterbury Geotechnical Database (CGD), the findings of trenching and seismic refraction surveying carried out for this research, and interpretation of historical aerial photographs. The thickness and extent of a buried peat swamp at the base of the slope was mapped, and found to coincide with significant compression features. Ground cracking was found to have occurred entirely within loess-colluvium and to follow the apices of pre-1920s tunnel-gully fan debris at the southern end of the valley. The ground-cracking on the eastern side of the Hillsborough Valley is interpreted to have formed through tensile failure of the loess-colluvium. Testing was carried out to determine the tensile strength of Port Hills loess colluvium as a function of water content and density, in order to better understand the occurrence and distribution of the observed ground cracking. A comprehensive review of the soil tensile strength testing literature was undertaken, from which a test methodology was developed. Results show remoulded loess-colluvium to possess tensile strength of 7 - 28 kPa across the range of tested moisture contents (10-15%) and dry densities (1650-1900kg/m3). A positive linear relationship was observed between tensile strength and dry density, and a negative linear relationship between moisture content and tensile strength. The observed ground damage and available geotechnical information (inclinometer and piezometer records provided by the Earthquake Commission) were together used to interpret the mechanism(s) of slope movement that occurred in the eastern Hillsborough Valley. The observed ground damage is characteristic of translational movement, but without the development of lateral release scarps, or a basal sliding surface - which was not located during drilling. It is hypothesised that shear displacement has been accommodated by multiple slip surfaces of limited extent within the upper 10m of the slope. Movement has likely occurred within near-saturated colluvial units that have lost strength during earthquake shaking. The eastern Hillsborough Valley is considered to be an ‘incipient translational slide’, as both the patterns of damage and shearing are consistent with the early stages of such slide development. Sliding block analysis was utilised to understand how the eastern Hillsborough Valley may perform in a future large magnitude earthquake. Known cumulative displacements of ~0.3m for eastern Hillsborough Valley during the 2010-2011 Canterbury Earthquake Sequence were compared with modelled slope displacements to back-analyse a lower-bound yield acceleration of 0.2 - 0.25g. Synthetic broadband modelling for future Alpine and Hope Fault earthquakes indicates PGAs of approximately 0.08g for soil sites in the Christchurch area, as such, slope movement is unlikely to be reactivated by an Alpine Fault or Hope Fault earthquake. This does not take into account the possible role of strength loss due to excess pore pressure that may occur during these future events.
<b>Aotearoa has undoubtedly some of the most beautiful landscapes in the world, a privilege for its inhabitants. However, as our cities have developed post-colonisation, the connection between the natural environment and its occupants has diminished. Designers play a vital role within an ever evolving world to progress the built environment in a way that reflects and restores vital values that have been deprioritised. Future practice should prioritise diversity, care for the land, enhancement of community space, and sustainable practices.</b>
This research sets out to demonstrate that new design methodologies can encourage kaitiakitanga, whilst meeting the needs of urban public space. Initially through critical analysis and literature based research, a study of Ōtautahi Christchurch, the South Island’s largest city, was undertaken. The principles of a ‘15 minute city’ were also explored and applied to the city, establishing issues within the built environment that drove the overall research direction.
Through the tools of critical reflection and a research through design methodology, a design toolkit was constructed. This toolkit sets out to provide designers with a simple streamlined method of developing urban interventions that are sustainable and beneficial for human well-being. The toolkit incorporates an abstraction of the ‘15 minute city’ ideology and introduces the concepts of evolving green transportation routes within cities. Ōtautahi Christchurch, a city with a significant history of earthquake-caused damage, was chosen as the primary site for the application of this research’s proposed toolkit. The city becomes a canvas for an urban rebuild that explores and aims to set a precedent for a progressive 21st-century city.
A key finding as the toolkit research developed was the idea of a ‘temporary’ phase or intervention, being added to traditional design methodologies prior to permanent building. The research explains how this temporary phase could more actively engage diverse user groups and create active conversations between communities and designers.
The refined toolkit sets outs proposed timeline phases, methods of site analysis and development of design drivers. Alongside this, a modular architectural system establishes a design proposal for the temporary phase of an individual site within an evolving green route. This outcome provides further opportunity for realistic testing, which would actively involve communities and aims to shift our priorities within urban development. The introduction of the ‘temporary’ phase is beneficial in mitigating psychological implications on people and limiting physical impacts on the landscape.
The final design stage of the thesis applied the toolkit process to three sites in Ōtautahi Christchurch. Through a holistic lens, the toolkit framework set out methods to collate information that provides guidance for development on the sites. While some layers are initiated simply by recognising site characteristics, others are informed through software such as GIS.
Connected by a proposed green transport route, the three initial sites are developed with temporary interventions that utilise the modular design set out previously in the research. Contextualising the interventions on real world sites tested the flexibility of the system and allowed for critical reflection on the applicability of the toolkit to Aotearoa.
The research concludes by identifying future research opportunities and speculates on possible applications of its findings within the real world. Temporary Permanence highlights the significant role that we, as designers, have in shifting urban priorities to create more holistic, sustainable, and inclusive cities for people and the planet.
A non-destructive hardness testing method has been developed to investigate the amount of plastic strain demand in steel elements subjected to cyclic loading. The focus of this research is on application to the active links of eccentrically braced frames (EBFs), which are a commonly used seismic-resisting system in modern steel framed buildings. The 2010/2011 Christchurch earthquake series, especially the very intense February 22 shaking, which was the first earthquake worldwide to push complete EBF systems fully into their inelastic state, generating a moderate to high level of plastic strain in EBF active links, for a range of buildings from 3 to 23 storeys in height. This raised two important questions: 1) what was the extent of plastic deformation in active links; and 2) what effect does that have to post-earthquake steel properties? This project comprised determining a robust relationship between hardness and plastic strain in order to be able to answer the first question and provide the necessary input into answering the second question. A non-destructive Leeb (portable) hardness tester (model TH170) has been used to measure the hardness, in order to determine the plastic strain, in hot rolled steel universal sections and steel plates. A bench top Rockwell B was used to compare and validated the hardness measured by the portable hardness tester. Hardness was measured from monotonically strained tensile test specimens to identify the relationship between hardness and plastic strain demand. Test results confirmed a good relationship between hardness and the amount of monotonically induced plastic strain. Surface roughness was identified as an important parameter in obtaining reliable hardness readings from a portable hardness reader. A proper surface preparation method was established by using three different cleaning methods, finished with hand sanding to achieve surface roughness coefficients sufficiently low not to distort the results. This work showed that a test surface roughness (Ra) is not more than 1.6 micron meter (μm) is required for accurate readings from the TH170 tester. A case study on an earthquake affected building was carried out to identify the relationship between hardness and amount of plastic strain demand in cyclically deformed active links. Hardness was carried out from active links shown visually to have been the most affected during one of the major earthquake events. Onsite hardness test results were then compared with laboratory hardness test results. A good relationship between hardness from onsite and laboratory was observed between the test methods; Rockwell B bench top and portable Leeb tester TH170. Manufacturing induced plastic strain in the top and bottom of the webs of hot rolled sections were discovered from this research, an important result which explains why visual effects of earthquake induced active link yielding (eg cracked or flaking paint) was typically more prevalent over the middle half depth of the active link. The extent of this was quantified. It was also evident that the hardness readings from the portable hardness tester are influenced by geometry, mass effects and rigidity of the links. The final experimental stage was application of the method to full scale cyclic inelastic tested nominally identical active links subjected to loading regimes comprising constant and variable plastic strain demands. The links were cyclically loaded to achieve different plastic strain level. A novel Digital Image Correlation (DIC) technique was incorporated during the tests of this scale, to confirm the level of plastic strain achieved. Tensile test specimens were water jet cut from cyclically deformed webs to analyse the level of plastic strain. Test results show clear evidence that cyclically deformed structural steel elements show good correlation between hardness and the amount of plastic strain demand. DIC method was found to be reliable and accurate to check the level of plastic strain within cyclically deformed structural steel elements.
Timber has experienced renewed interests as a sustainable building material in recent times. Although traditionally it has been the prime choice for residential construction in New Zealand and some other parts of the world, its use can be increased significantly in the future through a wider range of applications, particularly when adopting engineered wood material, Research has been started on the development of innovative solutions for multi-storey non-residential timber buildings in recent years and this study is part of that initiative. Application of timber in commercial and office spaces posed some challenges with requirements of large column-free spaces. The current construction practice with timber is not properly suited for structures with the aforementioned required characteristics and new type of structures has to be developed for this type of applications. Any new structural system has to have adequate capacity for carry the gravity and lateral loads due to occupancy and the environmental effects. Along with wind loading, one of the major sources of lateral loads is earthquakes. New Zealand, being located in a seismically active region, has significant risk of earthquake hazard specially in the central region of the country and any structure has be designed for the seismic loading appropriate for the locality. There have been some significant developments in precast concrete in terms of solutions for earthquake resistant structures in the last decade. The “Hybrid” concept combining post-tensioning and energy dissipating elements with structural members has been introduced in the late 1990s by the precast concrete industry to achieve moment-resistant connections based on dry jointed ductile connections. Recent research at the University of Canterbury has shown that the concept can be adopted for timber for similar applications. Hybrid timber frames using post-tensioned beams and dissipaters have the potential to allow longer spans and smaller cross sections than other forms of solid timber frames. Buildings with post-tensioned frames and walls can have larger column-free spaces which is a particular advantage for non-residential applications. While other researchers are focusing on whole structural systems, this research concentrated on the analysis and design of individual members and connections between members or between member and foundation. This thesis extends existing knowledge on the seismic behaviour and response of post-tensioned single walls, columns under uni-direction loads and small scale beam-column joint connections into the response and design of post-tensioned coupled walls, columns under bi-directional loading and full-scale beam-column joints, as well as to generate further insight into practical applications of the design concept for subassemblies. Extensive experimental investigation of walls, column and beam-column joints provided valuable confirmation of the satisfactory performance of these systems. In general, they all exhibited almost complete re-centering capacity and significant energy dissipation, without resulting into structural damage. The different configurations tested also demonstrated the flexibility in design and possibilities for applications in practical structures. Based on the experimental results, numerical models were developed and refined from previous literature in precast concrete jointed ductile connections to predict the behaviour of post-tensioned timber subassemblies. The calibrated models also suggest the values of relevant parameters for applications in further analysis and design. Section analyses involving those parameters are performed to develop procedures to calculate moment capacities of the subassemblies. The typical features and geometric configurations the different types of subassemblies are similar with the only major difference in the connection interfaces. With adoption of appropriate values representing the corresponding connection interface and incorporation of the details of geometry and configurations, moment capacities of all the subassemblies can be calculated with the same scheme. That is found to be true for both post-tensioned-only and hybrid specimens and also applied for both uni-directional and bi-directional loading. The common section analysis and moment capacity calculation procedure is applied in the general design approach for subassemblies.
Sewerage systems convey sewage, or wastewater, from residential or commercial buildings through complex reticulation networks to treatment plants. During seismic events both transient ground motion and permanent ground deformation can induce physical damage to sewerage system components, limiting or impeding the operability of the whole system. The malfunction of municipal sewerage systems can result in the pollution of nearby waterways through discharge of untreated sewage, pose a public health threat by preventing the use of appropriate sanitation facilities, and cause serious inconvenience for rescuers and residents. Christchurch, the second largest city in New Zealand, was seriously affected by the Canterbury Earthquake Sequence (CES) in 2010-2011. The CES imposed widespread damage to the Christchurch sewerage system (CSS), causing a significant loss of functionality and serviceability to the system. The Christchurch City Council (CCC) relied heavily on temporary sewerage services for several months following the CES. The temporary services were supported by use of chemical and portable toilets to supplement the damaged wastewater system. The rebuild delivery agency -Stronger Christchurch Infrastructure Rebuild Team (SCIRT) was created to be responsible for repair of 85 % of the damaged horizontal infrastructure (i.e., water, wastewater, stormwater systems, and roads) in Christchurch. Numerous initiatives to create platforms/tools aiming to, on the one hand, support the understanding, management and mitigation of seismic risk for infrastructure prior to disasters, and on the other hand, to support the decision-making for post-disaster reconstruction and recovery, have been promoted worldwide. Despite this, the CES in New Zealand highlighted that none of the existing platforms/tools are either accessible and/or readable or usable by emergency managers and decision makers for restoring the CSS. Furthermore, the majority of existing tools have a sole focus on the engineering perspective, while the holistic process of formulating recovery decisions is based on system-wide approach, where a variety of factors in addition to technical considerations are involved. Lastly, there is a paucity of studies focused on the tools and frameworks for supporting decision-making specifically on sewerage system restoration after earthquakes. This thesis develops a decision support framework for sewerage pipe and system restoration after earthquakes, building on the experience and learning of the organisations involved in recovering the CSS following the CES in 2010-2011. The proposed decision support framework includes three modules: 1) Physical Damage Module (PDM); 2) Functional Impact Module (FIM); 3) Pipeline Restoration Module (PRM). The PDM provides seismic fragility matrices and functions for sewer gravity and pressure pipelines for predicting earthquake-induced physical damage, categorised by pipe materials and liquefaction zones. The FIM demonstrates a set of performance indicators that are categorised in five domains: structural, hydraulic, environmental, social and economic domains. These performance indicators are used to assess loss of wastewater system service and the induced functional impacts in three different phases: emergency response, short-term recovery and long-term restoration. Based on the knowledge of the physical and functional status-quo of the sewerage systems post-earthquake captured through the PDM and FIM, the PRM estimates restoration time of sewer networks by use of restoration models developed using a Random Forest technique and graphically represented in terms of restoration curves. The development of a decision support framework for sewer recovery after earthquakes enables decision makers to assess physical damage, evaluate functional impacts relating to hydraulic, environmental, structural, economic and social contexts, and to predict restoration time of sewerage systems. Furthermore, the decision support framework can be potentially employed to underpin system maintenance and upgrade by guiding system rehabilitation and to monitor system behaviours during business-as-usual time. In conjunction with expert judgement and best practices, this framework can be moreover applied to assist asset managers in targeting the inclusion of system resilience as part of asset maintenance programmes.
The previously unknown Greendale Fault was buried beneath the Canterbury Plains and ruptured in the September 4th 2010 moment magnitude (Mw) 7.1 Darfield Earthquake. The Darfield Earthquake and subsequent Mw 6 or greater events that caused damage to Christchurch highlight the importance of unmapped faults near urban areas. This thesis examines the morphology, age and origin of the Canterbury Plains together with the paleoseismology and surface-rupture displacement distributions of the Greendale Fault. It offers new insights into the surface-rupture characteristics, paleoseismology and recurrence interval of the Greendale Fault and related structures involved in the 2010 Darfield Earthquake. To help constrain the timing of the penultimate event on the Greendale Fault the origin and age of the faulted glacial outwash deposits have been examined using sedimentological analysis of gravels and optically stimulated luminescence (OSL) dating combined with analysis of GPS and LiDAR survey data. OSL ages from this and other studies, and the analysis of surface paleochannel morphology and subsurface gravel deposits indicate distinct episodes of glacial outwash activity across the Canterbury Plains, at ~20 to 24 and ~28 to 33 kyr separated by a hiatus in sedimentation possibly indicating an interstadial period. These data suggest multiple glacial periods between ~18 and 35 kyr which may have occurred throughout the Canterbury region and wider New Zealand. A new model for the Waimakariri Fan is proposed where aggradation is mainly achieved during episodic sheet flooding with the primary river channel location remaining approximately fixed. The timing, recurrence interval and displacements of the penultimate surface-rupturing earthquake on the Greendale Fault have been constrained by trenching the scarp produced in 2010 at two locations. These excavations reveal a doubling of the magnitude of surface displacement at depths of 2-4 m. Aided by OSL ages of sand lenses in the gravel deposits, this factor-of-two increase is interpreted to indicate that in the central section of the Greendale Fault the penultimate surface-rupturing event occurred between ca. 20 and 30 kyr ago. The Greendale Fault remained undetected prior to the Darfield earthquake because the penultimate fault scarp was eroded and buried during Late Pleistocene alluvial activity. The Darfield earthquake rupture terminated against the Hororata Anticline Fault (HAF) in the west and resulted in up to 400 mm of uplift on the Hororata Anticline immediately above the HAF. Folding in 2010 is compared to Quaternary and younger deformation across the anticline recorded by a seismic reflection line, GPS-measured topographic profiles along fluvial surfaces, and river channel sinuosity and morphology. It is concluded that the HAF can rupture during earthquakes dissimilar to the 2010 event that may not be triggered by slip on the Greendale Fault. Like the Greendale Fault geomorphic analyses provide no evidence for rupture of the HAF in the last 18 kyr, with the average recurrence interval for the late Quaternary inferred to be at least ~10 kyr. Surface rupture of the Greendale Fault during the Darfield Earthquake produced one of the most accessible and best documented active fault displacement and geometry datasets in the world. Surface rupture fracture patterns and displacements along the fault were measured with high precision using real time kinematic (RTK) GPS, tape and compass, airborne light detection and ranging (LiDAR), and aerial photos. This allowed for detailed analysis of the cumulative strike-slip displacement across the fault zone, displacement gradient (ground shear strain) and the type of displacement (i.e. faulting or folding). These strain profiles confirm that the rupture zone is generally wide (~30 to ~300 metres) with >50% of displacement (often 70-80%) accommodated by ground flexure rather than discrete fault slip and ground cracking. The greatest fault-zone widths and highest proportions of folding are observed at fault stepovers.
In most design codes, infill walls are considered as non-structural elements and thus are typically neglected in the design process. The observations made after major earthquakes (Duzce 1999, L’Aquila 2009, Christchurch 2011) have shown that even though infill walls are considered to be non-structural elements, they interact with the structural system during seismic actions. In the case of heavy infill walls (i.e. clay brick infill walls), the whole behaviour of the structure may be affected by this interaction (i.e. local or global structural failures such as soft storey mechanism). In the case of light infill walls (i.e. non-structural drywalls), this may cause significant economical losses. To consider the interaction of the structural system with the ‘non-structural ’infill walls at design stage may not be a practical approach due to the complexity of the infill wall behaviour. Therefore, the purpose of the reported research is to develop innovative technological solutions and design recommendations for low damage non-structural wall systems for seismic actions by making use of alternative approaches. Light (steel/timber framed drywalls) and heavy (unreinforced clay brick) non-structural infill wall systems were studied by following an experimental/numerical research programme. Quasi-static reverse cyclic tests were carried out by utilizing a specially designed full scale reinforced concrete frame, which can be used as a re-usable bare frame. In this frame, two RC beams and two RC columns were connected by two un-bonded post tensioning bars, emulating a jointed ductile frame system (PRESSS technology). Due to the rocking behaviour at the beam-column joint interfaces, this frame was typically a low damage structural solution, with the post-tensioning guaranteeing a linear elastic behaviour. Therefore, this frame could be repeatedly used in all of the tests carried out by changing only the infill walls within this frame. Due to the linear elastic behaviour of this structural bare frame, it was possible to extract the exact behaviour of the infill walls from the global results. In other words, the only parameter that affected the global results was given by the infill walls. For the test specimens, the existing practice of construction (as built) for both light and heavy non-structural walls was implemented. In the light of the observations taken during these tests, modified low damage construction practices were proposed and tested. In total, seven tests were carried out: 1) Bare frame , in order to confirm its linear elastic behaviour. 2) As built steel framed drywall specimen FIF1-STFD (Light) 3) As built timber framed drywall specimen FIF2-TBFD (Light) 4) As built unreinforced clay brick infill wall specimen FIF3-UCBI (Heavy) 5) Low damage steel framed drywall specimen MIF1-STFD (Light) 6) Low damage timber framed drywall specimen MIF2-TBFD (Light) 7) Low damage unreinforced clay brick infill wall specimen MIF5-UCBI (Heavy) The tests of the as built practices showed that both drywalls and unreinforced clay brick infill walls have a low serviceability inter-storey drift limit (0.2-0.3%). Based on the observations, simple modifications and details were proposed for the low damage specimens. The details proved to be working effectively in lowering the damage and increasing the serviceability drift limits. For drywalls, the proposed low damage solutions do not introduce additional cost, material or labour and they are easily applicable in real buildings. For unreinforced clay brick infill walls, a light steel sub-frame system was suggested that divides the infill panel zone into smaller individual panels, which requires additional labour and some cost. However, both systems can be engineered for seismic actions and their behaviour can be controlled by implementing the proposed details. The performance of the developed details were also confirmed by the numerical case study analyses carried out using Ruaumoko 2D on a reinforced concrete building model designed according to the NZ codes/standards. The results have confirmed that the implementation of the proposed low damage solutions is expected to significantly reduce the non-structural infill wall damage throughout a building.
This thesis is concerned with the effects of lateral confining reinforcement on the ductile behaviour of reinforced concrete columns. The contents of the chapters are summarized as follows. In Chapter one, the general problems in seismic design are discussed and earthquake design methods based on the ductile design approach are described. Japanese, New Zealand and United States design codes are compared. Finally, the scope of this research project is outlined. In Chapter two, after reviewing previous research on confined concrete, the factors which affect the effectiveness of lateral confinement are discussed. Especially the effects of the yield strength of transverse reinforcement, the compressive strength of plain concrete and the strain gradient in the column section due to bending are discussed based on tests which were conducted by the author et al at Kyoto University and Akashi Technological College, Japan. In the axial compression tests on spirally reinforced concrete cylinders (150 mm in diameter by 300 mm in height), the yield strength of transverse reinforcement and the compressive strength of plain concrete were varied from 161 MPa to 1352 MPa and from 17 MPa to 60 MPa, respectively, as experimental parameters. It is found that, when high strength spirals are used as confining reinforcement, the strength and ductility of the confined core concrete are remarkably enhanced but need to be estimated assuming several failure modes which could occur. These are based on the observations that concrete cylinders with high strength spirals suddenly failed at a concrete compressive strain of 2 to 3.5 % due to explosive crushing of the core concrete between the spiral bars or due to bearing failure of the core concrete immediately beneath the spiral bars, while the concrete cylinders with ordinary strength spirals failed in a gentle manner normally observed. In addition, eccentric loading tests were conducted on concrete columns with 200 mm square section confined by square spirals. It is found that the effectiveness of confining reinforcement is reduced by the presence of the strain gradient along the transverse section of column. In Chapter three, the effectiveness of transverse reinforcement with various types of anchorage details which simplify the fabrication of reinforcing cages are investigated. Eight reinforced concrete columns, with either 400 mm or 550 mm square cross sections, were tested subjected to axial compression loading and cyclic lateral loading which simulated a severe earthquake. The transverse reinforcement consisted of arrangements of square perimeter hoops with 135° end hooks, cross ties with 90° and 135° or 180° end hooks, and 'U' and 'J' shaped cross ties and perimeter hoops with tension splices. Conclusions are reached with regard to the effectiveness of the tested anchorage details in the plastic hinge regions of columns designed for earthquake resistance. In Chapter four, the effectiveness of interlocking spirals as transverse reinforcement is studied. Firstly, the general aspects and the related problems of interlocking spirals to provide adequate ductility in the potential plastic hinge region of columns are discussed, referring to the provisions in the New Zealand code,the CALTRANS (California Transportation Authority) code and other related codes. Secondly, based on those discussions, a design method to securely interlock the spirals is proposed. Thirdly, the effectiveness of interlocking spirals is assessed based on column tests conducted as part of this study. Three columns with interlocking spirals and, for comparison, one rectangular column with rectangular hoopsandcross ties, were tested under cyclic horizontal loading which simulated a severe earthquake. The sections of those columns were 400 mm by 600 mm. In Chapter five, analytical models to investigate the buckling behaviour of longitudinal reinforcement restrained by cross ties with 90° and 135° end hooks and by peripheral hoops are proposed. The analyzed results using the proposed models compare well with the experimental observations described in Chapter three. Using those proposed models, a method to check the effectiveness of cross ties with 90° and 135° end hooks is proposed for practical design purposes. In Chapter six, a theory for the prediction of the ultimate longitudinal compressive concrete strain at the stage of first hoop fracture referred to as the "Energy Balance Theory", which has been developed by Mander, Priestley and Park at University of Canterbury, is introduced. After discussing the problems in the "Energy Balance Theory", a modified theory for the prediction of the ultimate longitudinal compressive concrete strain at the stage of first hoop fracture is proposed. The predictions from the modified theory are found to compare well with previous experimental results.
Fine grained sediment deposition in urban environments during natural hazard events can impact critical infrastructure and properties (urban terrain) leading to reduced social and economic function and potentially adverse public health effects. Therefore, clean-up of the sediments is required to minimise impacts and restore social and economic functionality as soon as possible. The strategies employed to manage and coordinate the clean-up significantly influence the speed, cost and quality of the clean-up operation. Additionally, the physical properties of the fine grained sediment affects the clean-up, transport, storage and future usage of the sediment. The goals of the research are to assess the resources, time and cost required for fine grained sediment clean-up in an urban environment following a disaster and to determine how the geotechnical properties of sediment will affect urban clean-up strategies. The thesis focuses on the impact of fine grained sediment (<1 mm) deposition from three liquefaction events during the Canterbury earthquake sequence (2010-2011) on residential suburbs and transport networks in Christchurch. It also presents how geotechnical properties of the material may affect clean-up strategies and methods by presenting geotechnical analysis of tephra material from the North Island of New Zealand. Finally, lessons for disaster response planning and decision making for clean-up of sediment in urban environments are presented. A series of semi-structured interviews of key stakeholders supported by relevant academic literature and media reports were used to record the clean-up operation coordination and management and to make a preliminary qualification of the Christchurch liquefaction ejecta clean-up (costs breakdown, time, volume, resources, coordination, planning and priorities). Further analysis of the costs and resources involved for better accuracy was required and so the analysis of Christchurch City Council road management database (RAMM) was done. In order to make a transition from general fine sediment clean-up to specific types of fine disaster sediment clean-up, adequate information about the material properties is required as they will define how the material will be handled, transported and stored. Laboratory analysis of young volcanic tephra from the New Zealand’s North Island was performed to identify their geotechnical properties (density, granulometry, plasticity, composition and angle of repose). The major findings of this research were that emergency planning and the use of the coordinated incident management system (CIMS) system during the emergency were important to facilitate rapid clean-up tasking, management of resources and ultimately recovery from widespread and voluminous liquefaction ejecta deposition in eastern Christchurch. A total estimated cost of approximately $NZ 40 million was calculated for the Christchurch City clean-up following the 2010-2011 Canterbury earthquake sequence with a partial cost of $NZ 12 million for the Southern part of the city, where up to 33% (418 km) of the road network was impacted by liquefaction ejecta and required clearing of the material following the 22 February 2011 earthquake. Over 500,000 tonnes of ejecta has been stockpiled at Burwood landfill for all three liquefaction inducing earthquake events. The average cost per kilometre for the event clean-up was $NZ 5,500/km (4 September 2010), $NZ 11,650/km (22 February 2011) and $NZ 11,185/km (13 June 2011). The duration of clean-up time of residential properties and the road network was approximately two to three months for each of the three liquefaction ejecta events; despite events volumes and spatial distribution of ejecta. Interviews and quantitative analysis of RAMM data revealed that the experience and knowledge gained from the Darfield earthquake (4 September 2010) clean-up increased the efficiency of the following Christchurch earthquake induced liquefaction ejecta clean-up events. Density, particle size, particle shape, clay content and moisture content, are the important geotechnical properties that need to be considered when planning for a clean-up method that incorporates collection, transport and disposal or storage. The geotechnical properties for the tephra samples were analysed to increase preparedness and reaction response of potentially affected North Island cities from possible product from the active volcanoes in their region. The geotechnical results from this study show that volcanic tephra could be used in road or construction material but the properties would have to be further investigated for a New Zealand context. Using fresh volcanic material in road, building or flood control construction requires good understanding of the material properties and precaution during design and construction to extra care, but if well planned, it can be economically beneficial.
This thesis is concerned with modelling rockfall parameters associated with cliff collapse debris and the resultant “ramp” that formed following the high peak ground acceleration (PGA) events of 22 February 2011 and 13 June 2011. The Christchurch suburb of Redcliffs, located at the base of the Port Hills on the northern side of Banks Peninsula, New Zealand, is comprised of Miocene-age volcanics with valley-floor infilling marine sediments. The area is dominated by basaltic lava flows of the Mt Pleasant Formation, which is a suite of rocks forming part of the Lyttelton Volcanic Group that were erupted 11.0-10.0Ma. Fresh exposure enabled the identification of a basaltic ignimbrite unit at the study site overlying an orange tuff unit that forms a marker horizon spanning the length of the field area. Prior to this thesis, basaltic ignimbrite on Banks Peninsula has not been recorded, so descriptions and interpretations of this unit are the first presented. Mapping of the cliff face by remote observation, and analysis of hand samples collected from the base of the debris slopes, has identified a very strong (>200MPa), columnar-jointed, welded unit, and a very weak (<5MPa), massive, so-called brecciated unit that together represent the end-member components of the basaltic ignimbrite. Geochemical analysis shows the welded unit is picrite basalt, and the brecciated unit is hawaiite, making both clearly distinguishable from the underlying trachyandesite tuff. RocFall™ 4.0 was used to model future rockfalls at Redcliffs. RocFall™ is a two-dimensional (2D), hybrid, probabilistic modelling programme for which topographical profile data is used to generate slope profiles. GNS Science collected the data used for slope profile input in March 2011. An initial sensitivity analysis proved the Terrestrial Laser Scan (TLS)-derived slope to be too detailed to show any results when the slope roughness parameter was tested. A simplified slope profile enabled slope roughness to be varied, however the resulting model did not correlate with field observations as well. By using slope profile data from March 2011, modelled rockfall behaviour has been calibrated with observed rockfall runout at Redcliffs in the 13 June 2011 event to create a more accurate rockfall model. The rockfall model was developed on a single slope profile (Section E), with the chosen model then applied to four other section lines (A-D) to test the accuracy of the model, and to assess future rockfall runout across a wider area. Results from Section Lines A, B, and E correlate very well with field observations, with <=5% runout exceeding the modelled slope, and maximum bounce height at the toe of the slope <=1m. This is considered to lie within observed limits given the expectation that talus slopes will act as a ramp on which modelled rocks travel further downslope. Section Lines C and D produced higher runout percentage values than the other three section lines (23% and 85% exceeding the base of the slope, respectively). Section D also has a much higher maximum bounce height at the toe of the slope (~8.0m above the slope compared to <=1.0m for the other four sections). Results from modelling of all sections shows the significance of the ratio between total cliff height (H) and horizontal slope distance (x), and of maximum drop height to the top of the talus (H*) and horizontal slope distance (x). H/x can be applied to the horizontal to vertical ratio (H:V) as used commonly to identify potential slope instability. Using the maximum value from modelling at Redcliffs, the future runout limit can be identified by applying a 1.4H:1V ratio to the remainder of the cliff face. Additionally, the H*/x parameter shows that when H*/x >=0.6, the percentage of rock runout passing the toe of the slope will exceed 5%. When H*/x >=0.75, the maximum bounce height at the toe of the slope can be far greater than when H*/x is below this threshold. Both of these parameters can be easily obtained, and can contribute valuable guideline data to inform future land-use planning decisions. This thesis project has demonstrated the applicability of a 2D probabilistic-based model (RocFall™ 4.0) to evaluate rockfall runout on the talus slope (or ramp) at the base of ~35-70m high cliff with a basaltic ignimbrite source. Limitations of the modelling programme have been identified, in particular difficulties with adjusting modelled roughness of the slope profile and the inability to consider fragmentation. The runout profile using RocFall™ has been successfully calibrated against actual profiles and some anomalous results have been identified.
<strong>Sea level rise is one consequence of Earth’s changing climate. Century-long tide gauge records show that global-mean sea-level rise reached 11-16 cm during the twentieth century at a mean rate of 1.2 mm/y. Today, the average rate of global-mean sea-level rise is higher at 3-4 mm/y and is expected to increase in the future. This represents a hazard to low elevation coastal zones worldwide. Yet, before global sea level projections can be used to characterise future coastal flood hazard at a local scale, the effects of tectonics (and other processes) that drive vertical land motion (VLM) must be considered. VLM is defined as the vertical velocity (uplift or subsidence) of the solid surface with respect to the centre of Earth. In this study, new VLM maps are generated over coastal strips in New Zealand, using Sentinel-1 InSAR and GNSS data.</strong>In New Zealand, measuring VLM using InSAR on naturally vegetated or agricultural land is difficult due to signal decorrelation. Along the rural Bay of Plenty coastal strip, I use a persistent-scatterer approach to generate a VLM map from both east-looking ascending and west-looking descending Sentinel-1 data between 2015-2021. Using time-series data over the same time period from a dense network of 20 GNSS sensors, I tie InSAR-derived line-of-sight velocity to the 2014 ITRF reference frame. I test two different methods for measuring VLM and compare the results against GNSS vertical velocity along the Bay of Plenty coast. Best results are achieved by first removing the interpolated horizontal GNSS velocity field from each of the InSAR datasets, before averaging the two VLM estimates. Measured VLM is between -3 and 3 mm/y, with negative values (subsidence) occurring within the low-lying Rangitāiki Plain and Ōpōtiki valley, and uplift across the elevated region west of Matatā.This thesis integrates geomorphological, geological, and historical levelling VLM records with modern satellite datasets to assess VLM across timescales ranging from 10 to 100,000 years at Matatā. Uplift rate has been variable through time, with average uplift over the last 300,000 years of 1 mm/y, 4.5 mm/y since 1720 years, 2 mm/y between 1950-1978, and 10 mm/y between 2004-2011. Previous modelling has shown that the best fit to the 2004-2011 rapid uplift rates is an inflating magmatic source at ~10 km depth beneath Matatā. To reconcile all data, I present a VLM model that consists of short-lived periods (7 years) of rapid uplift (10 mm/y), separated by longer periods (30 years) of lower background uplift (3 mm/y). The episodic nature of VLM at Matatā likely reflects short-lived periods of magmatic intrusion. Episodic VLM characterised by large rates of uplift (10 mm/y) has been seen at Taupō volcano, and other volcanic centers globally. It has been 12 years since the end of the last intrusion episode; this modelling suggest one may expect to observe increased uplift rates at Matatā in the coming decades. Densely populated urban coastal strips are most at risk from the effects of relative sea-level rise. At the same time, anthropogenic activities associated with urbanization, such as groundwater withdrawal, and land reclamation can lead to local land subsidence (LLS), further exacerbating the risk to urban infrastructure. LLS refers to subsidence relative to nearby land area assumed to be stable. In this thesis, I create the first high-resolution (10 m) maps of LLS at six urban coastal strips in New Zealand, with a combined length of 285 km, using Sentinel-1 InSAR data between 2018-2021. This analysis reveals 89% of urban coastal strips are subsiding at rates of -0.5 mm/y or greater, and 11% is subsiding at higher rates of -3.0 mm/y or greater. On average, subsidence is -0.6 to -2.9 mm/y higher at the coastal strip, compared to inland areas occupied by GNSS stations. This analysis also documents highly-localised hotspots of LLS, with subsidence rates of up to -15 mm/y. In Christchurch, rapid and localised subsidence (-8 mm/y) is observed within coastal suburbs New Brighton and Southshore. In most cities, the highest subsidence rates occur on land reclaimed in the early-late twentieth century, and in areas built on Holocene sediment. Time-series analysis of LLS at sites of reclaimed land shows both linear and non-linear rates of deformation over time periods of up to 6-8 years. This thesis highlights the variable exposure to relative sea-level rise of New Zealand coastal strips, and demonstrates that in many cases current rates of VLM should be expected to continue for the next few decades.
Following the 22nd February 2011, Mw 6.2 earthquake located along a previously unknown fault beneath the Port Hills of Christchurch, surface cracking was identified in contour parallel locations within fill material at Quarry Road on the lower slopes of Mount Pleasant. GNS Science, in the role of advisor to the Christchurch City Council, concluded that these cracks were a part of a potential rotational mass movement (named zone 11A) within the fill and airfall loess material present. However, a lack of field evidence for slope instability and an absence of laboratory geotechnical data on which slope stability analysis was based, suggested this conclusion is potentially incorrect. It was hypothesised that ground cracking was in fact due to earthquake shaking, and not mass movement within the slope, thus forming the basis of this study. Three soil units were identified during surface and subsurface investigations at Quarry Road: fill derived from quarry operations in the adjacent St. Andrews Quarry (between 1893 and 1913), a buried topsoil, and underlying in-situ airfall loess. The fill material was identified by the presence of organic-rich topsoil “clods” that were irregular in both size (∼10 – 200 mm) and shape, with variable thicknesses of 1 – 10 m. Maximum thickness, as indicated by drill holes and geophysical survey lines, was identified below 6 Quarry Road and 7 The Brae where it is thought to infill a pre-existing gully formed in the underlying airfall loess. Bearing strength of the fill consistently exceeded 300 kPa ultimate below ∼500 mm depth. The buried topsoil was 200 – 300 mm thick, and normally displayed a lower bearing strength when encountered, but not below 300 kPa ultimate (3 – 11 blows per 100mm or ≥100 kPa allowable). In-situ airfall loess stood vertically in outcrop due to its characteristic high dry strength and also showed Scala penetrometer values of 6 – 20+ blows per 100 mm (450 – ≥1000 kPa ultimate). All soils were described as being moist to dry during subsurface investigations, with no groundwater table identified during any investigation into volcanic bedrock. In-situ moisture contents were established using bulk disturbed samples from hand augers and test pitting. Average moisture contents were low at 9% within the fill, 11 % within the buried topsoil, and 8% within the airfall loess: all were below the associated average plastic limit of 17, 15, and 16, respectively, determined during Atterberg limit analysis. Particle size distributions, identified using the sieve and pipette method, were similar between the three soil units with 11 – 20 % clay, 62 – 78 % silt, and 11 – 20 % fine sand. Using these results and the NZGS soil classification, the loess derived fill and in-situ airfall loess are termed SILT with some clay and sand, and the buried topsoil is SILT with minor clay and sand. Dispersivity of the units was found using the Emerson crumb test, which established that the fill can be non- to completely dispersive (score 0 – 4). The buried topsoil was always non-dispersive (score 0), and airfall loess completely dispersive (score 4). Values for cohesion (c) and internal friction angle (φ) of the three soil units were established using the direct shear box at field moisture contents. Results showed all soil units had high shear strengths at the moisture contents tested (c = 18 – 24 kPa and φ = 42 – 50°), with samples behaving in a brittle fashion. Moisture content was artificially increased to 16% within the buried topsoil, which reduced the shear strength (c = 10 kPa, φ = 18°) and allowed it to behave plastically. Observational information indicating stability at Quarry Road included: shallow, discontinuous, cracks that do not display vertical offset; no scarp features or compressional zones typical of landsliding; no tilted or deformed structures; no movement in inclinometers; no basal shear zone identified in logged core to 20 m depth; low field moisture contents; no groundwater table; and high soil strength using Scala penetrometers. Limit equilibrium analysis of the slope was conducted using Rocscience software Slide 5.0 to verify the slope stability identified by observational methods. Friction, cohesion, and density values determined during laboratory were input into the two slope models investigated. Results gave minimum static factor of safety values for translational (along buried topsoil) and rotational (in the fill) slides of 2.4 – 4.2. Sensitivity of the slope to reduced shear strength parameters was analysed using c = 10 kPa and φ = 18° for the translational buried topsoil plane, and a cohesion of 0 kPa within the fill for the rotational plane. The only situation that gave a factor of safety <1.0 was in nonengineered fill at 0.5 m depth. Pseudostatic analysis based on previous peak ground acceleration (PGA) values for the Canterbury Earthquake Sequence, and predicted PGAs for future Alpine Fault and Hope Fault earthquakes established minimum factor of safety values between 1.2 and 3.3. Yield acceleration PGAs were computed to be between 0.8g and 1.6g. Based on all information gathered, the cracking at Quarry Road is considered to be shallow deformation in response to earthquake shaking, and not due to deep-seated landsliding. It is recommended that the currently bare site be managed by smoothing the land, installing contour drainage, and bioremediation of the surface soils to reduce surface water infiltration and runoff. Extensive earthworks, including removal of the fill, are considered unnecessary. Any future replacement of housing would be subject to site-specific investigations, and careful foundation design based on those results.
