Abstract
To study the lateral deformation characteristics of coal under different confining pressures, coal compression experiments with confining pressures of 0 MPa, 3 MPa, 5 MPa, and 7 MPa were conducted under the same loading rate by using the TAW-2000 electrohydraulic servo rock mechanics experimental machine. The results of the study showed the following: at the initial stage of loading, the lateral strain of coal was about 12.22%–46.9% of the axial strain at the elastic deformation stage and 41.18%–64.96% of the axial strain at the inelastic deformation to peak stress stage. Compared with the experiment under 0 MPa confining pressure, the growth rate of the lateral strain of the coal under 3 MPa, 5 MPa, and 7 MPa confining pressures was much smaller than that of the corresponding axial strain. When the coal was damaged under different confining pressures, the lateral strain was maintained at about 0.6 × 10−2. Based on the field verification, we proposed that the lateral strain during the coal failure and the nonlinear region of the lateral axis ratio changing with time can be used as potential parameters for predicting the coal failure.
Highlights
Because of the impact of excavation, the coal wall of the coal roadway and the coal wall of the working face change from the initial three-way force to the one-way force so that the coal wall of the roadway and the coal near the coal wall of the working face bear the weight of rock strata above the excavation space. e weight causes an increase in the supporting pressure of the coal near the coal wall of the roadway and the working face, causing the coal near the coal wall to expand to the side of the goaf, resulting in the spalling of roadway coal wall and working face coal wall
It is of great significance to study the lateral deformation and lateral deformation characteristics of coal under different surrounding rock pressures to control the expansion deformation of coal rib, to guide roadway support, and to grout reinforcement of coal rib
Based on the triaxial test results of granite under different confining pressures, Jingxiang et al analyzed the lateral deformation characteristics of granite and proposed that the brittleness characteristics of rock samples can be comprehensively reflected from the change law and magnitude of brittleness [1]
Summary
Because of the impact of excavation, the coal wall of the coal roadway and the coal wall of the working face change from the initial three-way force to the one-way force so that the coal wall of the roadway and the coal near the coal wall of the working face bear the weight of rock strata above the excavation space. e weight causes an increase in the supporting pressure of the coal near the coal wall of the roadway and the working face, causing the coal near the coal wall to expand to the side of the goaf, resulting in the spalling of roadway coal wall and working face coal wall. Based on the triaxial unloading seepage test results under different initial confining pressures and unloading rates, Rubin et al obtained the lateral deformation characteristics. Zhenqian et al investigated the lateral deformation characteristics of coal under different loading rates by using the TAW-2000 electrohydraulic servo rock mechanics experimental system. The lateral deformation characteristics and laws of rock under triaxial compression [13,14,15] and the axial deformation characteristics of coal under different confining pressures and loading speeds [16, 17] have been investigated in depth in China and abroad, and some great results have been achieved. The TAW-2000 electrohydraulic servo rock mechanics testing machine was employed to examine the deformation characteristics of coal samples under the same loading rate and different confining pressures.
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