A series of full scale tests have been undertaken to assess the performance of ground strengthening methods to improve seismic performance of liquefiable soils in the Christchurch area. The tests used sequences of explosive charges to simulate seismic shaking at levels representative of SLS and ULS events and induced liquefaction and expulsion of sand. Monitoring included measurement of ground motion, pore pressure development and settlements.
The results have determined that the treatment of the upper crust by densification or cement stabilisation is an effective method of reducing settlements and preventing surface expulsion of liquefiable soil. Other options including deep soil mixing and a perimeter curtain wall were less effective but achieved the proposed design objectives and also have application.