TRex heading to New Zealand to test Christchurch’s soils

February 7, 2013

The world’s largest seismic vibration truck called TRex is on its way to New Zealand to test Christchurch’s ground.

In a collaborative research project between the University of Canterbury (UC) and University of Texas, Austin, the 29,000kg truck will arrive in Christchurch next month to carry out tests. It will be the first time that it has been operated outside of the USA.

TRex will be used to determine the properties of soils from the ground surface to depths of 250 metres by applying small vibrations and recording them with an array of instruments.

UC earthquake engineer Dr Brendon Bradley said an understanding of Christchurch’s soil properties at great depths was important because it impacted how seismic waves were amplified, reflected, and refracted as they travelled up to the earth’s surface.

``The ground motion recorded in the February 11 2011 earthquake illustrated significant basin-effects. These were caused by reverberations of the soft sedimentary soils that Christchurch is founded on.

``Using state of the art information on soil properties throughout Christchurch obtained by TRex and previous testing we can begin to link cause and effect and better understand where such effects will occur elsewhere during future earthquakes worldwide,’’ Dr Bradley said.

UC’s Professor Misko Cubrinovski said that TRex would provide invaluable data on the seismic properties of soils and their liquefaction resistance.

``This is one of the several major collaborative projects on the Canterbury earthquakes between New Zealand and US researchers, which are supported by the National Science Foundation in the US, EQC and the Natural Hazards Research Platform.

The testing will begin on March 11 at 15 sites around Christchurch under the auspices of the Canterbury Earthquake Recovery Authority and the Christchurch City Council. The public are invited to witness the testing during two days at QEII Park on March 14 and at Ilam Fields on March 21. TRex will also make an appearance at the opening of UC’s Quake Centre on March 21.

Dr Brady Cox, one of several University of Texas people who will travel to New Zealand, said the vibrations produced by the truck would be imperceptible beyond 15 metres.

ENDS

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