Towards a novel method for liquefaction evaluation of silty sands

Abstract

Soil liquefaction is a subject of long-standing interest in earthquake geotechnical engineering. Although significant advances in liquefaction research have been achieved in the past decades, it remains an area of great difficulty and uncertainty, as evidenced by the extensive liquefaction-related damage in many recent earthquakes. Of particular concern is the widespread liquefaction observed in silty sand deposits, raising questions about the deficiencies of the current methods for liquefaction evaluation. This paper presents selected results of a long-term research aimed at developing a rational method for evaluating the liquefaction potential of both clean and silty sands. The method is based on a comprehensive experimental program comprising small-strain shear wave testing and large-strain undrained shear testing for a wide range of sand states and is built in the critical state framework. A remarkable feature of the method is the unified characterization of shear wave velocity for both clean and silty sands through a state parameter defined in a sound theoretical context. As shear wave velocity is a well-defined soil property and can be measured both in the field and in the laboratory, and since the state parameter has proven a useful state variable for characterizing soil behavior under both cyclic and monotonic loadings, the new method is attractive and promising in a wide range of geotechnical applications.