Boundary effects on ground surface rupture induced by normal faulting

Abstract

Although centrifuge modelling has been used for studying soil–bedrock interaction, the limited space available in a model container to simulate prototype situations imposes challenges. This article introduces and discusses boundary effects on surface fault ruptures induced by normal faulting in clay and nine-layered soil strata in a geotechnical centrifuge. Both a horizontal kinematically constrained boundary and an unconstrained boundary, representing two extreme cases in the field, were applied. Their effects on soil deformation and the location of surface fault rupture are thoroughly compared and discussed. For both the clay and the nine-layered soil strata, the unconstrained boundary shifted the induced settlement profile towards the footwall, extended the range of soil subjected to tension, increased the horizontal displacement of the soil at the hanging wall and extended the influence zone of the surface fault rupture when compared with the constrained boundary cases. Compared with the clay stratum, the influence zone of surface fault rupture in the nine-layered soil was significantly reduced under the constrained boundary. However, the main rupture in both the clay and nine-layered soil strata was located at the intersection of the bedrock fault plane and the ground surface, independent of the boundary condition.