Experimental Study on Influential Factors for Shear Properties of Interfaces Between Anchor Bolts and Soil Under Different Confining Pressures

In order to study the mechanical properties of the interface between anchor bolts and soil, the pull-out tests on indoor anchor bolts were performed. The effects of confining pressure, water content and soil strength on the mechanical properties the interfaces between anchorage bodies and soil were studied taking precast and cast-in-situ anchor bolts as objects. Simultaneously, the shear properties of the two types of anchor bolts were compared, and the whole process model of shear stress-shear displacement between interfaces of anchorage bodies and soil was proposed. The results indicated that the higher the confining pressures were, the greater the shear stresses of the interfaces and the ultimate pullout forces of anchor bolts were. With the increase in the water content, the ultimate pullout forces of anchor bolts increased first and then decreased, and when the water content of soil closed its optimal water content, the anchorage properties of anchor bolts were relatively better. The higher the soil strength was the greater the ultimate pullout forces of anchor bolts were. The ultimate forces of cast-in-situ anchor bolts were greater than that of precast anchor bolts, and the differences of the ultimate pullout force between the two types of anchor bolts were greater with the increase in confining pressures. The failure modes of the two types of anchor bolts were consistent. The proposed fitting curves of stress-strain relations between interfaces of anchorage bodies and soil were fairly good agreement with the measured curves by tests.