Evaluation of K-o in Centrifuge Model Using Shear Wave Velocity

Abstract

The coefficient of earth pressure at rest (K-o) is an important parameter in the analysis and design of geotechnical structures. Methods based on the shear wave velocity (V-s) can be utilized to estimate K-o using the directionality of a shear wave and its dependence on effective stresses. For centrifuge modeling, it is important to understand the in-flight stress states at various locations during loading-unloading-reloading cycles and to develop a direct method for measuring K-o in flight. In this study, previously proposed methods based on V-s (V-s-K-o relationships) were assessed to determine K-o in a centrifuge model using the results of bender element tests performed in a cross-hole configuration. The suitability of the V-s-K-o relationship for the centrifuge test and variation in K-o with respect to location in the centrifuge model were investigated. Through changes in centrifugal acceleration, the loading and unloading stress conditions were simulated, and the K-o value calculated based on the V-s-K-o relationship was compared to values obtained from an earth pressure transducer and via empirical equations. It was found that the method using a single horizontally propagating V-s and one pressure measurement was adequate to evaluate K-o in a centrifuge model. In addition, K-o in the centrifuge model was higher at the center than near the boundary for the unloading stage because of the arching effect.