Soil stresses in sand subjected to reverse faulting: physical modeling and theoretical estimation

The stress condition in the soil is one of the major concerns in understanding the responses of structures subjected to faulting. Although the soil stress in fault zones was investigated in field observations, theoretical studies, and numerical modeling, few of them measured the soil stress during faulting in tests. This study conducts both centrifuge modeling and theoretical estimation for soil stress in dry sand subjected to reverse faulting. The centrifuge test models the free-field condition under 50g. Miniature pressure sensors are installed to measure the horizontal soil stress on the footwall. A theoretical method for earth pressures under lateral deformations proposed in a previous study is applied to estimate the horizontal soil stress in this study. The results show that the horizontal soil stress on the footwall increases as it receives continuous horizontal displacements and compression initially. When the rupture develops, the displacements are localized in the shear band. The horizontal soil stress gradually becomes stable from the bottom to the rupture along the depth. The outcropping of the rupture is a critical state for horizontal soil stress. When the rupture outcrops, no more increments of soil stress occur on the footwall, as the fault deformation is released through the rupture path. The horizontal soil stress on the footwall has a D-shaped distribution along depth during faulting. The lateral earth pressure coefficient decreases from the rupture to the bottom with depth. The theoretical estimations of horizontal soil stresses generally agree with the measured ones.