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Research papers, University of Canterbury Library

Pumice materials, which are problematic from an engineering viewpoint, are widespread in the central part of the North Island. Considering the impacts of the 2010-2011 Christchurch earthquakes, a clear understanding of their properties under earthquake loading is necessary. For example, the 1987 Edgecumbe earthquake showed evidence of localised liquefaction of sands of volcanic origin. To elucidate on this, research was undertaken to investigate whether existing empirical field-based methods to evaluate the liquefaction potential of sands, which were originally developed for hard-grained soils, are applicable to crushable pumice-rich deposits. For this purpose, two sites, one in Whakatane and another in Edgecumbe, were selected where the occurrence of liquefaction was reported following the Edgecumbe earthquake. Manifestations of soil liquefaction, such as sand boils and ejected materials, have been reported at both sites. Field tests, including cone penetration tests (CPT), shear-wave velocity profiling, and screw driving sounding (SDS) tests were performed at the sites. Then, considering estimated peak ground accelerations (PGAs) at the sites based on recorded motions and possible range of ground water table locations, liquefaction analysis was conducted at the sites using available empirical approaches. To clarify the results of the analysis, undisturbed soil samples were obtained at both sites to investigate the laboratory-derived cyclic resistance ratios and to compare with the field-estimated values. Research results clearly showed that these pumice-rich soils do not fit existing liquefaction assessment frameworks and alternate methods are necessary to characterise them.

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, UC QuakeStudies

Members of the Student Volunteer Army digging up liquefaction in from a resident's property. The liquefaction is being placed in wheelbarrows where it will be transported to the street and left in piles for the City Council to pick up.

Images, UC QuakeStudies

A damaged house in Avonside. The front of the house has sunk due to subsidence in the ground caused by liquefaction. Codes have been spray painted on the front window by the North Shore City Council rescue team.

Images, UC QuakeStudies

A large crack on the side of a residential road in Avonside. Cones have been placed on the crack to warn road users. In the background, piles of liquefaction have been dug out of residential properties and placed on the road for collection.

Images, UC QuakeStudies

Wheelbarrows being piled into trailers by members of the Student Volunteer Army so that they can be returned to the Volunteer Army's base at the University of Canterbury. Students have been using the wheelbarrows to clear liquefaction from Christchurch properties.

Images, UC QuakeStudies

A photograph of the earthquake damage the brick fence of a house in Christchurch. Bricks from the broken fence have been stacked on the footpath in front. Liquefaction has been piled on the footpath and road cones placed in front.

Images, UC QuakeStudies

A photograph of the earthquake damage the brick fence of a house in Christchurch. Bricks from the broken fence have been stacked on the footpath in front. Liquefaction has been piled on the footpath and road cones placed in front.

Images, UC QuakeStudies

Members of the Student Volunteer Army digging up liquefaction from a resident's property in Avonside. The liquefaction is being placed in wheelbarrows where it will be transported to the street and left in piles for the City Council to pick up.