Deformation and Failure Characteristics of the Rock Masses around Deep Underground Caverns

Zhechao Wang,Qi Wang,Chong Zhang

doi:10.1155/2015/230126

Abstract

The deformation and failure characteristics of deep rock masses are the focus of this study on deep rock mass engineering. The study identifies the deformation and failure characteristics of a deep cavern under different ground stress conditions using model test and theoretical analysis methods. First, the similarity theory for model tests is introduced, and then the scale factors used in the present study are calculated according to the Froude criterion. Based on the study objectives, the details of the study methods (the similarity coefficient, the loading conditions, the test steps, etc.) are introduced. Finally, the failure characteristics of the deep cavern and the strain distribution characteristics surrounding the caverns under different ground stress conditions are identified using the model test. It was found that compared with shallow rock masses the rock masses of the deep cavern have a much greater tensile range, which reaches 1.5 times the diameter of the cavern under the conditions established in the present study. Under different ground stress conditions, there are differences in failure characteristics and the reasons of the differences were analyzed. The implication of the test results on the design of support system for deep caverns was presented.

Highlights

The construction of infrastructure such as hydropower stations and the deep exploitation of such energy resources as coal require us to understand the deformation and failure characteristics of deep underground caverns
Based on the analysis of the test data, we know that the rock masses of the deep cavern have a tensile εθ (×102 με)
When designing a support system for rock masses, the strengthening range of anchor rods and anchor cables should be greater than the tensile range of the cavern

Summary

Introduction

The construction of infrastructure such as hydropower stations and the deep exploitation of such energy resources as coal require us to understand the deformation and failure characteristics of deep underground caverns. After the excavation of a cavern is completed, readjustment of the high ground stress states in the rock masses will occur; stress redistribution often leads to stress concentration, resulting in the development of pressure on the rocks surrounding the lining or the support system of the deep underground engineering structure. The current study shows that when the rocks surrounding a cavern are in a plastic deformation state, the embedded depth of the cavern is greater, and the pressure of the rocks surrounding the cavern is higher. The rocks surrounding a deep cavern are often in a high plastic state; the pressure of the rocks surrounding the cavern increases with the increasing depth [1,2,3]. Rock masses with different properties will have different failure modes under high pressure from the surrounding rocks [4, 5]

Methods

Results

Conclusion