Evaluation of K_o in centrifuge model using shear wave velocity

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 beutilized to estimate K _o using the directionality of a shear wave and its dependence one 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 Ko 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 Vs 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.