Roadway Engineering Mechanical Properties and Roadway Structural Instability Mechanisms in Deep Wells

We proposed a new classification method for stress-bearing structures in very-deep roadways. We conducted tests for roadwayengineering mechanical properties, including rock mechanical tests and ground stress measurement of two caverns in very-deep wells. We suggested a classification method for stress-bearing structures based on shear stress. Tests revealed that rock strength in the shear direction was the lowest; the stress distributions of acoustic emission and hollow inclusion were highly similar. Based on the roadway-engineering mechanical properties of two caverns and numerical simulation and in-situ tests, the key bearing structures were classified based on the concentrated shear stress. In deep caverns, shear stress was more concentrated on the softer surrounding rock, the key bearing structure areas, and the more seriously fractured surrounding rocks. Using the loose circle in-situ test, we compared the classification method of the key bearing structures with other classification methods. The results revealed agreement with the classification methods used for the key bearing structures. The deformation in-situ test showed that the strata convergence of concentrated shear stress areas developed quickly. Therefore, the phenomena of concentrated shear stress and the expanded range of key bearing structures are the structural instability mechanisms of deep roadways.