The role of burial depth on the structural plane-controlled rock burst failure characteristics of circular hard rock tunnels under true triaxial conditions

Abstract

Deep rock mass excavation, very easy to induce rockburst disaster, the structural plane has an important role in controlling rockbursts, with the development of underground engineering to the deep part of the earth, the depth of burial on the structural Plane-Controlled Rockbursts more and more prominent, in order to study the impact of the depth of burial on the structural Plane-Controlled Rockbursts, this paper adopts the use of red sandstone to make a cubic specimen of 100 mm * 100 mm * 100 mm containing 50 mm round holes, prefabricated fissure simulation structural plane surface, simulating 500 m, 800 m, 1000 m, 1200 m and 1500 m depth of burial pressure conditions to carry out a series of true triaxial compression test, comparative analysis of different burial depth conditions with or without structural plane specimens of rockburst evolution, damage mechanisms and fractal characteristics of debris, the results show that the structural plane of the rock mass of rockburst evolution stage has undergone significant changes, can be divided into a calm stage, violent damage and micro-cracking Expansion stage, plate fracture flexure stage, violent failure stage (secondary rockburst).AE evolution process can be divided into microcrack closure and linear elasticity stage, cracks non-stable development and rockburst stage, cracks sprouting and stable expansion stage and cracks non-stable development to rockburst stage. Structural plane specimens rockburst intensity is greater than that of the unstructured specimens, the high burial depth environment has a certain inhibition of the occurrence of rockburst, but the rockburst danger and rockburst intensity will be enhanced. No structural plane rock mass failure process is non-linear and progressive, structural plane rockburst has a “sudden” “transient” characteristics.