Abstract: The mechanical anchor is a type of commonly used ground anchor in the rock and soil anchoring engineering. It can obtain the required anchoring force in a short time mainly through the mutual extrusion friction between the metal anchor head and the rock and soil mass. The surface morphology of the metal anchor head is one of the important factors that affecting the interaction between the mechanical anchor and the rock and soil mass. In the practical applications, a form is often set up according to experience, and the pull-out test is used to verify whether the anchoring force meets the requirements. There is no targeted research on the shear performance of the rock-soil interface. To solve this issue, the spatial problem of the anchor-rock interaction is transformed into a plane problem. The direct shear test method is used to study the relationship between the shear stress and the shear displacement at the interface between the anchor head metal block with different surface morphology and the simulated surrounding rock, as well as the maximum shear stress under different normal stress, so as to obtain the shear strength of the anchor-rock interface. The results show that the cohesion of the pointed tooth shape is significantly larger than that of the smooth surface and the flat tooth shear contact surface. The internal friction angle of the shear contact surface also increases gradually in the order of smooth surface, flat tooth shape and pointed tooth shape, but the amplitude is not obvious. The internal friction angle is between 30° and 40°. 

Key words: Geotechnical Anchorage, Mechanical Anchor, Anchor-Rock Interface, Shear Characteristics, Direct Shear Test