An Apparatus for Determining Micromechanical Interface Shear Properties of Geomaterial Contacts

This paper presents a custom-built micromechanical testing apparatus to analyze the interface shear behavior of geomaterial contacts. This apparatus allows for the investigation of rolling and sliding friction of a wide range of geomaterial contacts under various testing parameters, including normal load, displacement rate, and dry and wet conditions. The device is instrumented with sensors (load, displacement, and camera) and a computerized data acquisition system to measure and record the force, displacement, and images of the contacts during the test for in-depth study. The images are captured from the bottom of the sliding platform while shearing for only the contacts made of particle and transparent continuum materials. The shear response accuracy for the geomaterial contacts tested in the custom-built micro mechanical apparatus is demonstrated by comparing the results of the same contacts obtained from a high-end tribometer apparatus. It was found that test findings from a custom-built apparatus are as accurate as those from a high-end tribometer and reliable for the micromechanical analysis of geomaterial interactions. Further, experiments were performed on different types of interface contacts and under different conditions to demonstrate the apparatus's sensitivity. These findings indicate that the apparatus stiffness is sufficient and facilitates the understanding of micromechanical behavior and estimates basic yet essential inputs required to comprehend the complex behavior of geomaterials.