Experimental investigation on a setback distance model for independent foundation overburden sites under normal-fault bedrock dislocation

Ground deformation resulting from strong earthquake fault ruptures can cause significant damage, including the collapse of building structures, garnering considerable research attention. (1) In this study, a large-scale physical model test device was implemented to simulate the loading mode of bedrock dislocation under constant gravity. Based on seismic damage analysis, tests were designed to explore key influencing parameters—bedrock fault dip angle, soil properties, and overburden thickness—on a system comprising strong earthquake normal fault rupture, overburden soil, and independent foundation.(2) The progressive failure of the overburden soil was found to be a dynamic evolution process of the internal rupture zone (IRZ) formed by the tension rupture zone (TRZ) and shear rupture zone (SRZ); this failure process could be divided qualitatively into three stages: the rupture incubation stage (Stage I), development stage (Stage II), and completion stage (Stage III). The failure severity of the independent foundation was reasonably assessed. (3) The setback distance was further refined. This research provides a scientific basis for understanding the failure mechanism and determining the setback distance for buildings in bedrock dislocation sites.