Evaluating the stiffness of the cyclic direct simple shear apparatus passive locking mechanism

The following thesis presents a study conducted on the Cyclic Direct Simple Shear Apparatus. The focus of the study encompasses the improvements that the apparatus has undergone to ensure that the effectiveness of the results obtained from the experiment are representative of the soil’s behavior. This study includes evaluating the effect of stiffness posed by the cyclic direct simple shear system on the specimen during testing. A passive locking mechanism has been adopted to address the issue using a set of four screw wedged using a torque wrench between the vertically moving patterns. The study focused on assessing different combinations of screw size and applied torque to further elaborate of the best option to ensure a stiff apparatus. The cyclic direct simple shear apparatus is exposed to several obstacles when testing such as rocking, rigidity between connection, and vertical displacement taking place upon shearing soil specimens. To avoid any volumetric change, this study assessed three screw size of different diameters subject to three different torque measurements. The data obtained has been compared to previously conducted studies to validate the respective reasoning. Applying a passive locking mechanism proved to improve the stiffness of the apparatus, especially when high torque measurements are applied to screws of larger diameters. However, a drawback remains when assessing the different screw size without coupling the applied torque.