Experimental study on the effect of anchored bolts on failure and strength behavior of nonpersistent jointed rock model

Anchored bolts are well known as an effective measure to support the rock masses, after all with stiff steel bolts being inserted into them. Although numerous researches have been carried out on anchored joints, the effects of anchored bolts on rock mass containing nonpersistent joints were rarely investigated. In the present study, in order to make up for the deficiency of research, we carried out experimental study on the effect of anchored bolts on failure and strength behavior of nonpersistent jointed rock model. Specifically, the unbolted and bolted rocklike samples with one set of nonpersistent joints were carefully prepared and subjected to the uniaxial compression tests. The strength and failure behavior of jointed rock mass with/without bolts were systematically compared and analyzed. The results demonstrated the effect of joint dip angle and joint spacing on the failure behavior of jointed rock model. The anchored bolts mainly increased the strength of jointed samples having joints of intermediate dip angles such as alpha = 30 degrees, 45 degrees, and 60 degrees, which fail in a mechanism of Shear Failure along the Joint Plane. The anchored bolts support the jointed rock models through providing lateral constraints and "pin" effect. Even though the anchored bolts work better for the intermediate dip angle situations to increase the bearing capability than for low dip angle (e.g., alpha = 0 degrees and 15 degrees) and high dip angle (e.g., alpha = 75 degrees and 90 degrees), they provide limit support strength such that cannot eliminate the influence of nonpersistent joints.