Experimental Study on Mechanical Properties and Stability Analysis of Structural Plane under Unloading Normal Stress

Feng Jiao, Jiang Xu, Shoujian Peng (), Meixin He and Xinrui Zhang
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Feng Jiao: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400040, China
Jiang Xu: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400040, China
Shoujian Peng: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400040, China
Meixin He: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400040, China
Xinrui Zhang: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400040, China

Sustainability, 2022, vol. 14, issue 23, 1-21

Abstract: Excavation in rock induces the unloading of stress in excavation-disturbed zones and can cause the structural plane to reach shear failure due to the unloading of normal stress. Unloading normal stress tests of a regular sawtooth structural plane were conducted in this study to investigate the influence of the unloading velocities ( v ) and asperity angles ( θ ) on mechanical properties and the stability of the structural plane. The average value of normal displacement ( D u 1 ) and the shear displacement of unloading ( D su ) gradually increases with an increase in θ and D u 1 accounts for 59.70%, 31.81%, and 18.60% of the height of a single asperity under different θ . However, D u 2 , D s , and the unloading capacity (Δ σ n ) gradually decreased. Moreover, D s account for 24.52%, 11.61%, and 7.4% of the length of a single asperity, respectively. With an increase in θ and v , three-dimensional (3D) morphology parameters and normal deformation energy ( U n ) decreased gradually, indicating that the damage degree of the structural plane increases. The analysis of the evolution of the gap width of the structural plane at the initial point, unloading point, and instability point indicates that the greater the θ or the smaller the v , the lower would be the likelihood for the structural plane to be damaged. Concurrently, its instability is more sudden and the impact tendency is stronger.

Keywords: unloading normal stress; asperity angles; unloading velocities; energy evolution; 3D morphology parameters; gap width (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
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