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Research papers, University of Canterbury Library

This paper presents a critical evaluation of vertical ground motions observed in the Canterbury earthquake sequence. The abundance of strong near-source ground-motion recordings provides an opportunity to comprehensively review the estimation of vertical ground motions via the New Zealand Standard for earthquake loading, NZS1170.5:2004, and empirical ground motion prediction equations (GMPEs). An in-depth review of current GMPEs is carried out to determine the existing trends and characteristics present in the empirical models. Results illustrate that vertical ground motion amplitudes estimated based on NZS1170.5:2004 are significantly unconservative at short periods and near-source distances. While conventional GMPEs provide an improved prediction, in many instances they too underpredict vertical ground motion accelerations at short periods and near-source distances.

Research papers, University of Canterbury Library

Current research in geotechnical engineering at the University of Canterbury includes a number of laboratory testing programmes focussed on understanding the behaviour of natural soil deposits in Christchurch during the 2010-2011 Canterbury Earthquake Sequence. Many soils found in Christchurch are sands or silty sands with little to no plasticity, making them very difficult to sample using established methods. The gel-push sampling methodology, developed by Kiso-Jiban Consultants in Japan, was developed to address some of the deficiencies of existing sampling techniques and has been deployed on two projects in Christchurch. Gel push sampling is carried out with a range of samplers which are modified versions of existing technology, and the University of Canterbury has acquired three versions of the tools (GP-S, GP-Tr, GP-D). Soil samples are extracted from the bottom of a freshly drilled borehole and are captured within a liner barrel, close to 1m in length. A lubricating polymer gel coats the outside of the soil sample as it enters the liner barrel. The frictional rubbing which normally occurs on the sides of the soil samples using existing techniques is eliminated by the presence of the polymer gel. The operation of the gel-push samplers is significantly more complicated than conventional push-tube samplers, and in the initial trials a number of operational difficulties were encountered, requiring changes to the sampling procedures. Despite these issues, a number of high quality soil samples were obtained on both projects using the GP-S sampler to capture silty soil. Attempts were made to obtain clean sands using a different gel-push sampler (GP-TR) in the Red Zone. The laboratory testing of these sands indicated that they were being significantly disturbed during the sampling and/or transportation procedures. While it remains too early to draw definitive conclusions regarding the performance of the gel-push samplers, the methodology has provided some promising results. Further trialling of the tools are required to refine operating procedures understand the full range of soil conditions which can be successfully sampled using the tools. In parallel with the gel-push trials, a Dames and Moore fixed-piston sampler has been used by our research partners from Berkeley to obtain soil samples at a number of sites within Christchurch. This sampler features relatively short (50cm), thin-walled liner barrels which is advanced into the ground under the action of hydraulic pressure. By reducing the overall length of the soil being captured, the disturbance to the soil as it enters the liner barrel is significantly reduced. The Dames and Moore sampler is significantly easier to operate than the gel-push sampler, and past experience has shown it to be successful in soft, plastic materials (i.e. clays and silty clays). The cyclic resistance of one silty clay obtained using both the gel-push and Dames & Moore samplers has been found to be very similar, and ongoing research aims to establish whether similar results are obtained for different soil types, including silty materials and clean sands.

Images, eqnz.chch.2010

The unforgettable beauty of lavender Occurs in both the earth As well as part of the many changing Shades of the daily heavens on high. Is quickly there, and then is gone. Light violet, lavender, How unique is its special glow, Colored in nature in light lilac, Amethyst, and airy, purple indigo. From a poem by Gil Saenz

Images, eqnz.chch.2010

This statue of the Virgin Mary stood in the south tower of The Cathedral of the Blessed Sacrament and had been facing inside from when she was placed there and through the September 2010 earthquake. That changed on February 22 2010 at 12.51pm when Christchurch was rocked by a 6.3 magnitude earthquake. During the violent shaking motion Mary was t...

Images, eqnz.chch.2010

Manchester Courts, a seven-storey building on the corner of Hereford and Manchester Streets, is a category one historic place built in 1905-1906 that up until the 7.1 earthquake, housed offices. News of the scheduled demolition provoked an emotional response from the people of Christchurch. UPDATE 14 October 2010: A group of residents is campaig...

Images, eqnz.chch.2010

20161112_9961_7D2-70 The future face of Christchurch? Cultivate Christchurch is operating this urban farm in the city, about 5-10 minutes walk to Cathedral Square. Many of the buildings in this area were demolished after the earhquakes, and in the background is a new building on Kilmore Street.

Images, eqnz.chch.2010

A local inspecting the damage to St Lukes Church after the 6.3 quake hit. For whom the bell tolls Time marches on For whom the bell tolls Take a look to the sky just before you die It's the last time you will Blackened roar, massive roar, fills the crumbling sky Shattered goal fills his soul with a ruthless cry Stranger now are his eyes to this...

Images, eqnz.chch.2010

The Christchurch Cathedral Square showing the Anglican Cathedral after loosing its tower and spire after the 6.3 quake hit Christchurch 22 February 2011. This image also shows the remains of the very heavy snow fall we had on Monday 25 July 2011. The centre of the city is still cordoned off. This image was taken from a helicopter flight over the...

Images, eqnz.chch.2010

This winter-eve is warm, Humid the air! leafless, yet soft as spring, The tender purple spray on copse and briers! And that sweet city with her dreaming spires, She needs not June for beauty's heightening, Lovely all times she lies, lovely to-night!— From "Thyrsis: A Monody" by Matthew Arnold 1822–1888

Images, eqnz.chch.2010

Sadly the Chapel has been badly damaged in the magnitude 6.3 earthquake that hit Christchurch 22 February 2011. See below. The Rose Historic Chapel formerly St Mary’s Convent Chapel is the sole survivor of a group of heritage buildings in Christchurch that once comprised the St Mary’s Convent complex for the Sisters of Mercy in North Colombo St...