Micro-macro analysis of shear band formation due to reverse fault in various normalized fault throw

Abstract

A two-dimensional discrete element modeling is adopted to study engineering and fundamental aspects of shear band formation in reverse faulting through sandy soils with varying densities. The employed DEM modeling methodology is verified with the experimental centrifuge result. From an engineering perspective, results show that the shear bands formed due to reverse fault consist of multiple ruptures formed at the different fault raise. These ruptures may deviate toward the hanging or footing wall depending on the faulting angle. The distortion zone outcropping location is captured by the W/H ratio at the 1% normalized fault throw (h/H) step. Various micro and macro aspects of shear banding, such as porosity, coordination number, and strong contact forces within the localized areas along the shear bands, are studied. Moreover, a link is established between the micro and macro events occurring inside the shear bands. The results show that the wedge pressure formed between the shear band and back-thrust rupture in the fault with a dip angle smaller than 45° significantly affects the back-thrust formation and micro-macro parameters in the shearing region.