Assessment of interfacial friction angles of sand-structural materials

Abstract This research evaluates the interfacial friction angles of sand-structural materials (i.e. concrete, steel, and wood) from direct shear and model pile tests data. Some variable parameters are considered for performing laboratory tests such as shearing rates (0.05, 0.5, 1.0, 2.0, and 2.5 mm/min.), pile diameters (38.1, 76.2, and 101.6 mm), and normal stresses (27, 55, and 81 kPa). The validated shearing rates are found to be 8.7% and 4.3% in cases of direct shear and model pile tests respectively, which may represent a good accuracy of experimental tests. According to the direct shear test results, the interfacial sand-concrete and internal friction angles are equal at shearing rate of 2 mm/min. The interfacial friction angles are increased with the increment of pile diameters because of slip dilation impact of small diameter pile. The interfacial friction angle of sand-wood pile shows the higher value because of lower self-weight and stiffness of wood compared to the other structural materials. There is a scope for further research by conducting numerical analysis and deriving analytical formulations for obtaining explicit solution.