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Research papers, University of Canterbury Library

Advanced seismic effective-stress analysis is used to scrutinize the liquefaction performance of 55 well-documented case-history sites from Christchurch. The performance of these sites during the 2010-2011 Canterbury earthquake sequence varied significantly, from no liquefaction manifestation at the ground surface (in any of the major events) to severe liquefaction manifestation in multiple events. For the majority of the 55 sites, the simplified liquefaction evaluation procedures, which are conventionally used in engineering practice, could not explain these dramatic differences in the manifestation. Detailed geotechnical characterization and subsequent examination of the soil profile characteristics of the 55 sites identified some similarities but also important differences between sites that manifested liquefaction in the two major events of the sequence (YY-sites) and sites that did not manifest liquefaction in either event (NN-sites). In particular, while the YY-sites and NN-sites are shown to have practically identical critical layer characteristics, they have significant differences with regard to their deposit characteristics including the thickness and vertical continuity of their critical zones and liquefiable materials. A CPT-based effective stress analysis procedure is developed and implemented for the analyses of the 55 case history sites. Key features of this procedure are that, on the one hand, it can be fully automated in a programming environment and, on the other hand, it is directly equivalent (in the definition of cyclic resistance and required input data) to the CPT-based simplified liquefaction evaluation procedures. These features facilitate significantly the application of effective-stress analysis for simple 1D free-field soil-column problems and also provide a basis for rigorous comparisons of the outcomes of effective-stress analyses and simplified procedures. Input motions for the analyses are derived using selected (reference) recordings from the two major events of the 2010-2011 Canterbury earthquake sequence. A step-by-step procedure for the selection of representative reference motions for each site and their subsequent treatment (i.e. deconvolution and scaling) is presented. The focus of the proposed procedure is to address key aspects of spatial variability of ground motion in the near-source region of an earthquake including extended-source effects, path effects, and variation in the deeper regional geology.

Images, UC QuakeStudies

An aerial photograph of Cambridge Terrace with the cleared PGC site in the upper centre. The photograph was captioned by BeckerFraserPhotos, "The area inside the cordon that is north of the river which encompasses the PGC site and Kilmore Street. The expectation is that this area will soon be outside the cordon".

Articles, Christchurch uncovered

Today on the blog we are discussing my favourite site of 2019. We already talked about part of the site’s history last fortnight on the blog- that it contained the store and offices for Walton, Warner and Co. and their … Continue reading →

Research papers, University of Canterbury Library

This paper presents an examination of ground motion observations from 20 near-source strong motion stations during the most significant 10 events in the 2010-2011 Canterbury earthquake to examine region-specific systematic effects based on relaxing the conventional ergodic assumption. On the basis of similar site-to-site residuals, surfical geology, and geographical proximity, 15 of the 20 stations are grouped into four sub-regions: the Central Business District; and Western, Eastern, and Northern suburbs. Mean site-to-site residuals for these sub-regions then allows for the possibility of non-ergodic ground motion prediction over these sub-regions of Canterbury, rather than only at strong motion station locations. The ratio of the total non-ergodic vs. ergodic standard deviation is found to be, on average, consistent with previous studies, however it is emphasized that on a site-by-site basis the non-ergodic standard deviation can easily vary by ±20%.

Other, National Library of New Zealand

Site of Christchurch-based handmade denim clothing company. Includes details of available stock, fitting guides, and photo gallery. Archive section of the site shows production models available prior to the Christchurch Earthquake.

Articles, Christchurch uncovered

Last time on the blog we looked specifically at the beer bottle labels from our Akaroa site. Today’s blog post is essentially a part two, where we’re going to take a look at the other labels found on the site. … Continue reading →

Articles, Christchurch uncovered

At the start of an archaeological investigation we often consult historical documents to learn as much as we can about a site’s past. Such research can identify the buildings that were once present, the people associated with the site through … Continue reading →