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EVALUATION OF LIQUEFACTION POTENTIAL OF SOILS USING SDS DATA IN CHRISTCHURCH (2014)
During severe earthquake shaking, soil liquefaction is a major concern for structures constructed on saturated loose sandy soils. A large number of civil engineering structures were damaged due to liquefaction during huge recent earthquakes in Christchurch. Several in-situ tests have been used for evaluating liquefaction resistance of soils. Cone penetration testing (CPT) is one of the most common in-situ tests, which is used worldwide for assessing the liquefaction potential of sandy soils. CPT is simple, fast, and it supplies continuous records with respect to depth. However, this test needs skilled operator and is relatively expensive. The Screw Driving Sounding (SDS) test is a relatively new operating system developed in Japan consisting of a machine that drills a rod into the ground at different steps of loading while being rotated. This machine can continuously measure the required torque, load, speed of penetration and rod friction during the test, so can give a clear overview of the soil profile along the depth of penetration. In this paper based on a number of SDS tests conducted in Christchurch a graph is presented which relates the cyclic stress ratio to the SDS parameters. Using the available data points a boundary line is defined between liquefied and unliquefied soil layers. By means of the proposed graph, liquefaction potential of soil can be estimated directly using SDS data. As SDS is simpler, faster and more economical than CPT, it can be a good alternative in situ test for soil characterization.
2014 NZSEE Conference
University of Auckland, Auckland, New Zealand.