Investigations on the behavior of liquefying soils

Improved physical evidence is needed of the processes and mechanisms involved in the occurrence of liquefaction as soil strength deteriorates to a residual state to allow the development of new, more refined analyses for dam safety and more cost-effective and safe seismic remediation. Reliable physical evidence can only come from field or equivalent-field data of behavior under well known and defined conditions. It has been concluded that the only practical route by which this can be achieved is through the use of the centrifuge. This paper describes the centrifuge experiments being undertaken to capture data of equivalent prototype behavior under dynamic loading and preliminary results. The research is part of the ongoing U.S. Army Engineer Earthquake Engineering Research Program (EQEN) at the U.S. Army Engineer Waterways Experiment Station (WES) and is using the dynamic base shaking capability of the unique WES research centrifuge. Our objectives are: (1) improve the simplified liquefaction methodology correction factors, K sigma and K alpha, because this method will always be used with in-situ measurements for initial field investigations and for verification of dam and foundation improvements, (2) define better the behavior of liquefying soil and effects on dam behavior, (3) expand our earthquake case history data base with better known conditions and responses, and (4) provide progressive results for immediate use in U.S. Army Corps of Enginers projects. The approach of this research to investigate the behavior of liquefying soils is to use laboratory testing, analytical procedures and centrifuge dynamic model testing.