Experimental study on anchoring force evolution characteristics of mortar anchor in joint rock mass

In order to investigate the evolution of anchoring force of mortar anchor in joint rock mass,indoor pull-out test of anchorage volume with pre-joints of diff erent sizes and locations was conducted, and the influence of joint aperture and the joint-surface distance on the anchoring force of the whole system was also studied. The results show that the joint-surface distance has itte effect on the ultimate failure mode of the anchoring system,while with the increasing joint aperture,the ultimate failure mode of the anchoring system changes gradually from the yield and tensile failure of the anchor to shear failure at the contact faces between the anchor,mortar and the anchorage volume, and in which 66.67% of the shear failure presents the interface failure between the anchor and the mortar,only 33.33% of the shear failure sh ows the interface failure between the mortar and the anchorage volume .Joint aperture has significant influence on the stress distribution of the anchorage section and t he bearing capacity of the whole system.The bearing capacity of the anchorage system decreases gradually with the increasing joint aperture,while increases gradually with the rise of the joint-surface distance.Axial stress of the anchorage section in intact anchorage volume decreases gradually with the increasing depth,while the axial stress of the anchor near the joints in flawed anchorage volume maintains basically stable , and the axial stress of anchor is greater than that of the intact anchorage vol ume in the same position when the depth is greater than the joint-surface distance.