New Rock Bolt Model and Numerical Implementation in Numerical Manifold Method

Abstract

A beam-element-based rock bolt model is proposed in this paper. The proposed model can not only simulate the compression and tension deformations of bolts in the rock block but also capture the interaction between the bolt and the joint. The antitension, antishear, and antirotation of bolts near the joint and the hardening characteristics of bolts after the plastic yielding can be comprehensively reflected using the proposed model. The rock bolt model has been incorporated into the original numerical manifold method (NMM) procedure developed for realistic applications. In the improved NMM procedure, the bolt can be input as the physical mesh, the layout of which is not correlated with the mathematical cover. Hence, the preprocess is simplified, and numerical simulation of a large number of bolts can be easily carried out. The results of this improved procedure for bolt modeling were verified with a direct shear test of an anchored joint. Finally, the procedure was applied to evaluate the reinforcement effect of bolts in the underground powerhouse of the Shuibuya hydropower station. The results show that the deformation behavior of the anchored rock mass and the reinforcement effect of bolts can be well captured by the bolt model.