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Research papers, The University of Auckland Library

This thesis presents an assessment of historic seismic performance of the New Zealand stopbank network from the 1968 Inangahua earthquake through to the 2016 Kaikōura earthquake. An overview of the types of stopbanks and the main aspects of the design and construction of earthen stopbanks was presented. Stopbanks are structures that are widely used on the banks of rivers and other water bodies to protect against the impact of flood events. Earthen stopbanks are found to be the most used for such protection measures. Different stopbank damage or failure modes that may occur due to flooding or earthquake excitation were assessed with a focus on past earthquakes internationally, and examples of these damage and failure modes were presented. Stopbank damage and assessment reports were collated from available reconnaissance literature to develop the first geospatial database of stopbank damage observed in past earthquakes in New Zealand. Damage was observed in four earthquakes over the past 50 years, with a number of earthquakes resulting in no stopbank damage. The damage database therefore focussed on the Edgecumbe, Darfield, Christchurch and Kaikōura earthquakes. Cracking of the crest and liquefaction-induced settlement were the most common forms of damage observed. To understand the seismic demand on the stopbank network in past earthquakes, geospatial analyses were undertaken to approximate the peak ground acceleration (PGA) across the stopbank network for ten large earthquakes that have occurred in New Zealand over the past 50 years. The relationship between the demand, represented by the peak ground acceleration (PGA) and damage is discussed and key trends identified. Comparison of the seismic demand and the distribution of damage suggested that the seismic performance of the New Zealand stopbank network has been generally good across all events considered. Although a significant length of the stopbank networks were exposed to high levels of shaking in past events, the overall damage length was a small percentage of this. The key aspect controlling performance was the performance of the underlying foundation soils and the effect of this on the stopbank structure and stability

Images, UC QuakeStudies

A truck stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

Damage to River Road in Richmond. The road surface is badly cracked and slumped, and liquefaction silt covers part of the road. Two people in gumboots walk towards a barrier erected across the road using road cones and warning tape, and in the background the badly twisted Medway Street bridge can be seen. The photographer comments, "Longitudinal cracks indicate lateral movement as the land sagged towards the river. Near 373 River Rd, looking south-east towards Medway St. The Medway St bridge is visible in the background".

Images, UC QuakeStudies

Damage to the garden of a house in Richmond. Liquefaction is visible among the plants and on the driveway, and the driveway is badly cracked. The photographer comments, "These photos show our old house in River Rd. Water and silt have flattened the long grass in the back garden. The growth right of centre is suckers growing from the stump of a prunus tree we had felled last year. The section of fence between us and our neighbour fell down in the Sep 4 quake".

Images, UC QuakeStudies

Damage to a residential property in Richmond. The brick wall of the garage has collapse inward, and the roof fallen in on top of it. The photographer comments, "These photos show our old house in River Rd and recovery work around Richmond and St Albans. The neighbours behind us used the kayak to get in to their house - it's flooded by Dudley Creek which runs behind the block, plus major liquefaction. Our old garage provides a good spot to park it".

Images, UC QuakeStudies

A truck stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, and a digger is attempting to dig the truck out. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A car stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, lifting the back wheels off the ground. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A truck stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, and a digger is attempting to dig the truck out. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A sewage pumping station on Avonside Drive has been lifted out of the ground by liquefaction. In the background, the damaged Snell Place footbridge over the Avon River is closed off with cordon fencing. The photographer comments, "A Sunday afternoon ride to New Brighton, then back via Aranui, Wainoni, Dallington, and Richmond. Not a cheerful experience. Dallington footbridge. The two pieces of this foot bridge have moved towards each other, so the bridge has developed quite a peak. The sewage pumping station has been heaved out of the ground by hydraulic pressure during quakes".

Images, UC QuakeStudies

A car stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, lifting the back wheels off the ground. A line of other vehicles drive around the partially-submerged car. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Images, UC QuakeStudies

A car stuck in liquefaction on Breezes Road. The front wheels have fallen into a submerged pothole, lifting the back wheels off the ground. A line of other vehicles drive around the partially-submerged car. The photographer comments, "The most common sight was extensive damage to the roads. Papanui, Breezes, Wainoni, Shortland Street and many more roads had large cracks and large sink holes. There were approximately 6 cars and 1 large Ready Mix cement truck that had fallen into holes within a few blocks of each other. All people appear to have escaped without serious injury as far as I could tell".

Research papers, Lincoln University

The September and February earthquakes were terrifying and devastating. In February, 185 people were killed (this number excludes post earthquake related deaths) and several thousand injured. Damage to infrastructure above and below ground in and around Christchurch was widespread and it will take many years and billions of dollars to rebuild. The ongoing effects of the big quakes and aftershocks are numerous, with the deepest impact being on those who lost family and friends, their livelihoods and homes. What did Cantabrians do during the days, weeks and months of uncertainty and how have we responded? Many grieved, some left, some stayed, some arrived, many shovelled (liquefaction left thousands of tons of silt to be removed from homes and streets), and some used their expertise or knowledge to help in the recovery. This book highlights just some of the projects staff and students from The Faculty of Environment, Society and Design have been involved in from September 2010 to October 2012. The work is ongoing and the plan is to publish another book to document progress and new projects.

Research papers, University of Canterbury Library

Asset management in power systems is exercised to improve network reliability to provide confidence and security for customers and asset owners. While there are well-established reliability metrics that are used to measure and manage business-as-usual disruptions, an increasing appreciation of the consequences of low-probability high-impact events means that resilience is increasingly being factored into asset management in order to provide robustness and redundancy to components and wider networks. This is particularly important for electricity systems, given that a range of other infrastructure lifelines depend upon their operation. The 2010-2011 Canterbury Earthquake Sequence provides valuable insights into electricity system criticality and resilience in the face of severe earthquake impacts. While above-ground assets are relatively easy to monitor and repair, underground assets such as cables emplaced across wide areas in the distribution network are difficult to monitor, identify faults on, and repair. This study has characterised in detail the impacts to buried electricity cables in Christchurch resulting from seismically-induced ground deformation caused primarily by liquefaction and lateral spread. Primary modes of failure include cable bending, stretching, insulation damage, joint braking and, being pulled off other equipment such as substation connections. Performance and repair data have been compiled into a detailed geospatial database, which in combination with spatial models of peak ground acceleration, peak ground velocity and ground deformation, will be used to establish rigorous relationships between seismicity and performance. These metrics will be used to inform asset owners of network performance in future earthquakes, further assess component criticality, and provide resilience metrics.

Research papers, Lincoln University

Study region: Christchurch, New Zealand. Study focus: Low-lying coastal cities worldwide are vulnerable to shallow groundwater salinization caused by saltwater intrusion and anthropogenic activities. Shallow groundwater salinization can have cascading negative impacts on municipal assets, but this is rarely considered compared to impacts of salinization on water supply. Here, shallow groundwater salinity was sampled at high spatial resolution (1.3 piezometer/km²), then mapped and spatially interpolated. This was possible due to a uniquely extensive set of shallow piezometers installed in response to the 2010–11 Canterbury Earthquake Sequence to assess liquefaction risk. The municipal assets located within the brackish groundwater areas were highlighted. New hydrological insights for the region: Brackish groundwater areas were centred on a spit of coastal sand dunes and inside the meander of a tidal river with poorly drained soils. The municipal assets located within these areas include: (i) wastewater and stormwater pipes constructed from steel-reinforced concrete, which, if damaged, are vulnerable to premature failure when exposed to chloride underwater, and (ii) 41 parks and reserves totalling 236 ha, within which salt-intolerant groundwater-dependent species are at risk. This research highlights the importance of determining areas of saline shallow groundwater in low-lying coastal urban settings and the co-located municipal assets to allow the prioritisation of sites for future monitoring and management.