Investigating Shear Bands Propagation in Sands by Using the Developed Elemental-like Direct Shear-Faulting Box

This study investigates faults propagation in granular soils using the developed elemental-like direct shear-faulting box by detecting shear bands formation within soil samples. For this sake, first, some modifications are applied to the direct shear box in the Earthquake Research Institute. In this regard, two blocks are built at an angle of 45 degrees that can be moved relative to each other. Transparent walls are employed to increase the static resistance. Moreover, four screws are installed on the floor of the device. The friction in the test is reduced by using several ball bearings. The required thickness for the box walls is determined using a numerical simulation in ABAQUS software. To investigate faulting in granular soils, Firoozkooh sand is utilized and placed in the developed shear box. The overhead load is modeled by applying air pressure to a rubber membrane containing water. By continuous imaging of soil profiles, alterations in the soil surface are recorded, and an image correlation method is employed to predict the amount of fault-induced displacements, strains, and dilations. Results verify that the dilation effect elevates with increasing moisture content and wanes with the addition of fine-grained percentage and by boosting vertical loads. Moreover, various behavior has been observed without softening for cementitious sands.