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Articles, Christchurch uncovered

Today, through the wonders of archaeology and Papers Past, we bring you the story of Charles Henry Cox, a man whose crime has been buried – literally – for over 100 years. But let’s not get too carried away. As … Continue reading →

Audio, Radio New Zealand

METIRIA TUREI to the Minister of Education: In relation to the proposed school closures in Christchurch, does she agree with Manning Intermediate head Richard Chambers that "The Minister promised us that we would have two years no matter what. It was a guarantee she made to our community repeatedly, it was unequivocal"? MAGGIE BARRY to the Minister of Finance: What reports has he received on the New Zealand economy? DAVID SHEARER to the Prime Minister: Does he have confidence in all his Ministers? Dr CAM CALDER to the Minister of Education: In the context of the Government's Christchurch schools announcement, what is the process going forward? Hon CLAYTON COSGROVE to the Minister for Building and Construction: Does he believe that the contracting system currently used in the construction industry works appropriately and fairly in circumstances of insolvency; if so, why? NICKY WAGNER to the Minister for Canterbury Earthquake Recovery: What progress is being made on making the Christchurch city centre safe for rebuilding? IAIN LEES-GALLOWAY to the Prime Minister: Does he stand by all his statements on withdrawing troops from Afghanistan? TIM MACINDOE to the Minister of Science and Innovation: How is the Government focussing New Zealand's science funding investment, and encouraging Kiwis to get involved in science? DAVID SHEARER to the Prime Minister: Does he stand by all his statements? ALFRED NGARO to the Minister for the Community and Voluntary Sector: What recent announcements has she made regarding government support for volunteering? EUGENIE SAGE to the Minister of Local Government: Does he have any concerns about the Hawkes Bay Regional Council's forecast of 530 percent increase in its debt by 2021/22? Rt Hon WINSTON PETERS to the Prime Minister: Does he still have confidence in the Associate Minister of Health; if so, why?

Research papers, University of Canterbury Library

The Canterbury Earthquakes of 2010-2011, in particular the 4th September 2010 Darfield earthquake and the 22nd February 2011 Christchurch earthquake, produced severe and widespread liquefaction in Christchurch and surrounding areas. The scale of the liquefaction was unprecedented, and caused extensive damage to a variety of man-made structures, including residential houses. Around 20,000 residential houses suffered serious damage as a direct result of the effects of liquefaction, and this resulted in approximately 7000 houses in the worst-hit areas being abandoned. Despite the good performance of light timber-framed houses under the inertial loads of the earthquake, these structures could not withstand the large loads and deformations associated with liquefaction, resulting in significant damage. The key structural component of houses subjected to liquefaction effects was found to be their foundations, as these are in direct contact with the ground. The performance of house foundations directly influenced the performance of the structure as a whole. Because of this, and due to the lack of research in this area, it was decided to investigate the performance of houses and in particular their foundations when subjected to the effects of liquefaction. The data from the inspections of approximately 500 houses conducted by a University of Canterbury summer research team following the 4th September 2010 earthquake in the worst-hit areas of Christchurch were analysed to determine the general performance of residential houses when subjected to high liquefaction loads. This was followed by the detailed inspection of around 170 houses with four different foundation types common to Christchurch and New Zealand: Concrete perimeter with short piers constructed to NZS3604, concrete slab-on-grade also to NZS3604, RibRaft slabs designed by Firth Industries and driven pile foundations. With a focus on foundations, floor levels and slopes were measured, and the damage to all areas of the house and property were recorded. Seven invasive inspections were also conducted on houses being demolished, to examine in more detail the deformation modes and the causes of damage in severely affected houses. The simplified modelling of concrete perimeter sections subjected to a variety of liquefaction-related scenarios was also performed, to examine the comparative performance of foundations built in different periods, and the loads generated under various bearing loss and lateral spreading cases. It was found that the level of foundation damage is directly related to the level of liquefaction experienced, and that foundation damage and liquefaction severity in turn influence the performance of the superstructure. Concrete perimeter foundations were found to have performed most poorly, suffering high local floor slopes and being likely to require foundation repairs even when liquefaction was low enough that no surface ejecta was seen. This was due to their weak, flexible foundation structure, which cannot withstand liquefaction loads without deforming. The vulnerability of concrete perimeter foundations was confirmed through modelling. Slab-on-grade foundations performed better, and were unlikely to require repairs at low levels of liquefaction. Ribraft and piled foundations performed the best, with repairs unlikely up to moderate levels of liquefaction. However, all foundation types were susceptible to significant damage at higher levels of liquefaction, with maximum differential settlements of 474mm, 202mm, 182mm and 250mm found for concrete perimeter, slab-on-grade, ribraft and piled foundations respectively when subjected to significant lateral spreading, the most severe loading scenario caused by liquefaction. It was found through the analysis of the data that the type of exterior wall cladding, either heavy or light, and the number of storeys, did not affect the performance of foundations. This was also shown through modelling for concrete perimeter foundations, and is due to the increased foundation strengths provided for heavily cladded and two-storey houses. Heavy roof claddings were found to increase the demands on foundations, worsening their performance. Pre-1930 concrete perimeter foundations were also found to be very vulnerable to damage under liquefaction loads, due to their weak and brittle construction.