Deformation Characteristics of Bolted Rock Joints under Compression-Shear Load

Joints exist widely in tunnel engineering. Studying the deformation characteristics of the bolted joint is beneficial for preventing rock mass disasters. To reveal the deformation characteristics of bolted rock joints, the elastic solutions of the radial deformation characteristics of bolted rock joints under compression-shear load were derived, which were based on the Lame solution in elastic mechanics and the displacement coordination condition of the interface between the bolt and the joint (assuming that the displacement at the interface between the bolt and joint is equal). Then, the distance from any point of the compression-shear side of the joint to the center of the bolt was denoted as r. The minimum of the radial displacement of the joint at the compression-shear side u(rmin) was calculated. Numerical simulation verified the correctness of the elastic solutions by calculating the influence range and distance. In addition, the variation law of the value of the radial displacement (u(r)) was analyzed and discussed by changing the elastic modulus of the rock block (E-r), radius (R), and elastic modulus (E-b) of the bolt. The results indicate the following: (1) The radial displacement will decrease as r decreases; the influence range of the bolt on the joint is approximately an ellipse, whereas the long axis of the ellipse is equal to the influence distance of the bolt. (2) The influence distance of the bolt is roughly six times the bolt radius (6R). (3) The radial displacement shows an exponential relationship with the elastic modulus of the rock and a nonlinear negative correlation with the radius and elastic modulus of the bolt. The increase in the elastic modulus of the rock, the elastic modulus, and the radius of the bolt will make the radial displacement smaller.