Influence of joint angle on the instability failure characteristics and AE evolution law of underground caverns
Xiao Wang, Na Wu, Hong Li, Yatao Yan
Abstract
The existence of joints is the key factor for the instability of underground caverns. In this paper, the instability failure behaviours, acoustic emission (AE) characteristics and damage evolution rules of green sandstone caverns with different joint angles were investigated. First, the influences of joint angles on the strength and failure behaviour of the caverns were analysed. Then, the AE characteristics and damage evolution rules of jointed caverns in the process of failure were discussed. The research results showed that the UCS and elastic modulus presented obvious anisotropy. Furthermore, the existence of joints with various angles had a strong influence on the failure pattern of caverns. However, the damage of the cavern is mainly concentrated on the side wall, the top and bottom and the maximum value of AE in jointed caverns are smaller than that in intact cavern, but the occurrence time of AE maximum value is generally earlier than that of intact cavern. The damage progress of jointed caverns is divided into four stages: damage stable stage, damage slow increase stage, damage rapid increase stage and damage termination stage. The joint angle mainly affected the second and third stages of damage variable of the caverns.