Reinforcement Performance of the Bolted Rock Mass with a Weak Interlayer Under Constant Lateral Stiffness Boundary Condition

Abstract

The widespread existence of weak interlayer poses a serious threat to the stability of roadway surrounding rock under constant stiffness restraint boundary condition in lateral direction (axial direction of roadway) and the rock bolt is widely used to reinforce the surrounding rock of roadway. So, in this paper, the reinforcement performance of the bolted rock mass with a weak interlayer was investigated under constant lateral stiffness (CLS) boundary condition. The research results indicated that the peak strength and elasticity modulus of the samples exponentially increase with the increasing of bolt pretension force and density. Two parameters Rp and RE were put forward to quantitatively describe the reinforcement effect of bolt pretension force and density on the peak strength and elasticity modulus of the samples. Under CLS boundary condition, the lateral direction of the samples experienced loading-unloading and expansion - compaction deformation periods during the whole triaxial compression process. The mechanism for the transformation of expansion - to - compaction was explained. Two new failure modes of the samples were observed and analyzed in detail, and were found them different from those of the bolted jointed rock mass and bedded rock mass.