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Christchurch Press Image: Dean Kozanic 2010:10:21 (06)

Images, UC QuakeStudies

Photograph captioned by Fairfax, "Part of the Kaiapoi stop bank earmarked to have underground damming to alleviate liquefaction in earthquakes".

Christchurch Press Image: Dean Kozanic 2010:10:21 (02)

Images, UC QuakeStudies

Photograph captioned by Fairfax, "Part of the Kaiapoi stop bank earmarked to have underground damming to alleviate liquefaction in earthquakes".

Christchurch Press Image: Dean Kozanic 2010:10:21 (04)

Images, UC QuakeStudies

Photograph captioned by Fairfax, "Part of the Kaiapoi stop bank earmarked to have underground damming to alleviate liquefaction in earthquakes".

Geotechnical Aspects of the 22 February 2011 Christchurch earthquake

Research papers, University of Canterbury Library

The 22 February 2011, Mw6.2-6.3 Christchurch earthquake is the most costly earthquake to affect New Zealand, causing 181 fatalities and severely damaging thousands of residential and commercial buildings, and most of the city lifelines and infrastructure. This manuscript presents an overview of observed geotechnical aspects of this earthquake as well as some of the completed and on-going research investigations. A unique aspect, which is particularly emphasized, is the severity and spatial extent of liquefaction occurring in native soils. Overall, both the spatial extent and severity of liquefaction in the city was greater than in the preceding 4th September 2010 Darfield earthquake, including numerous areas that liquefied in both events. Liquefaction and lateral spreading, variable over both large and short spatial scales, affected commercial structures in the Central Business District (CBD) in a variety of ways including: total and differential settlements and tilting; punching settlements of structures with shallow foundations; differential movements of components of complex structures; and interaction of adjacent structures via common foundation soils. Liquefaction was most severe in residential areas located to the east of the CBD as a result of stronger ground shaking due to the proximity to the causative fault, a high water table approximately 1m from the surface, and soils with composition and states of high susceptibility and potential for liquefaction. Total and differential settlements, and lateral movements, due to liquefaction and lateral spreading is estimated to have severely compromised 15,000 residential structures, the majority of which otherwise sustained only minor to moderate damage directly due to inertial loading from ground shaking. Liquefaction also had a profound effect on lifelines and other infrastructure, particularly bridge structures, and underground services. Minor damage was also observed at flood stop banks to the north of the city, which were more severely impacted in the 4th September 2010 Darfield earthquake. Due to the large high-frequency ground motion in the Port hills numerous rock falls and landslides also occurred, resulting in several fatalities and rendering some residential areas uninhabitable.

Performance of horizontal infrastructure in Christchurch city through the …

Research papers, University of Canterbury Library

This is an interim report from the research study performed within the NHRP Research Project “Impacts of soil liquefaction on land, buildings and buried pipe networks: geotechnical evaluation and design, Project 3: Seismic assessment and design of pipe networks in liquefiable soils”. The work presented herein is a continuation of the comprehensive study on the impacts of Christchurch earthquakes on the buried pipe networks presented in Cubrinovski et al. (2011). This report summarises the performance of Christchurch City’s potable water, waste water and road networks through the 2010-2011 Canterbury Earthquake Sequence (CES), and particularly focuses on the potable water network. It combines evidence based on comprehensive and well-documented data on the damage to the water network, detailed observations and interpretation of liquefaction-induced land damage, records and interpretations of ground motion characteristics induced by the Canterbury earthquakes, for a network analysis and pipeline performance evaluation using a GIS platform. The study addresses a range of issues relevant in the assessment of buried networks in areas affected by strong earthquakes and soil liquefaction. It discusses performance of different pipe materials (modern flexible pipelines and older brittle pipelines) including effects of pipe diameters, fittings and pipeline components/details, trench backfill characteristics, and severity of liquefaction. Detailed breakdown of key factors contributing to the damage to buried pipes is given with reference to the above and other relevant parameters. Particular attention is given to the interpretation, analysis and modelling of liquefaction effects on the damage and performance of the buried pipe networks. Clear link between liquefaction severity and damage rate for the pipeline has been observed with an increasing damage rate seen with increasing liquefaction severity. The approach taken here was to correlate the pipeline damage to LRI (Liquefaction Resistance Index, newly developed parameter in Cubrinovski et al., 2011) which represents a direct measure for the soil resistance to liquefaction while accounting for the seismic demand through PGA. Key quality of the adopted approach is that it provides a general methodology that in conjunction with conventional methods for liquefaction evaluation can be applied elsewhere in New Zealand and internationally. Preliminary correlations between pipeline damage (breaks km-1), liquefaction resistance (LRI) and seismic demand (PGA) have been developed for AC pipes, as an example. Such correlations can be directly used in the design and assessment of pipes in seismic areas both in liquefiable and non-liquefiable areas. Preliminary findings on the key factors for the damage to the potable water pipe network and established empirical correlations are presented including an overview of the damage to the waste water and road networks but with substantially less detail. A comprehensive summary of the damage data on the buried pipelines is given in a series of appendices.

Northern Outlook Image: Laura Melville 2011:02:22 13:46:33

Images, UC QuakeStudies

Photograph captioned by Fairfax, "Doug Cowan points to a new hole on Charles Street, which suffered liquefaction damage after Tuesday's earthquake."

Relationship between observed liquefaction at Kaiapoi following the 2010 D…

Research papers, The University of Auckland Library

The Darfield earthquake caused widespread damage in the Canterbury region of New Zealand, with the majority of damage resulting from liquefaction and lateral spreading. One of the worst hit locations was the small town of Kaiapoi north of Christchurch, an area that has experienced liquefaction during past events and has been identified as highly susceptible to liquefaction. The low lying town sits on the banks of the Kaiapoi River, once a branch of the Waimakariri, a large braided river transporting gravelly sediment. The Waimakariri has been extensively modified both by natural and human processes, consequently many areas in and around the town were once former river channels.

Images for earthquake liquefaction; more images...

Images, UC QuakeStudies

Images, UC QuakeStudies

Images, UC QuakeStudies

Research papers, University of Canterbury Library

Research papers, University of Canterbury Library

Images, UC QuakeStudies

Research papers, The University of Auckland Library

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Research papers, University of Canterbury Library

Research papers, University of Canterbury Library

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

Images, eqnz.chch.2010

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