During past major earthquakes in Christchurch, enormous damage to engineered structures and lifelines has been caused by liquefaction-induced ground failures. Standard penetration test is the most commonly used in situ test for soil characterization of liquefaction resistance. However this test has some limitations. A major disadvantage of SPT is the lack of repeatability and variation of energy delivered to the drilled rod. Moreover, this test cannot provide continuous profile of the soil. Screw Driving Sounding test (SDS) is a new testing method developed in Japan which consists of a machine drilling a rod into the ground surface at different steps of loading while rotating. This machine can continuously measure the required torque, load, speed of penetration and rod friction during the test, so can give a brief overview of soil profile along the depth of penetration. Based on many SDS tests conducted in Japan, it was shown that by measuring penetration velocity, rod friction and applied torque and load, soil properties can be identified with acceptable accuracy. Based on a number of SDS tests conducted in Christchurch, a correlation is made in this study between the normalized SPT N value and SDS results and using the obtained correlation factor, it is shown that liquefaction potential of soil can be measured by using SDS data which is simpler and faster test compared to SPT.
Soil characterization using SDS data in Christchurch