Micro–macro analysis of shear band formation in various normalised reverse fault throws

Abstract

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