Abstract
Slip and instability of coal-rock parting-coal structure (CRCS) subjected to excavation disturbance can easily induce coal-rock dynamic phenomena in deep coal mines. In this paper, the failure characteristics and influencing factors of CRCS slip and instability were investigated by theoretical analysis, numerical simulations, and field observations. The following main results are addressed: (1) the slip and instability of CRCS induced by excavation are due to stress release, and the damage of the rock parting is partitioned into three parts: shear failure zone, slipping zone, and splitting failure zone from inside to outside with slip; (2) the slip and instability process of CRCS is accompanied by initiation, expansion, and intersection of shear and tensile cracks. The development of the cracks is dominated by shear behaviour, while the tensile crack is the main factor affecting fracture and instability of CRCS; and (3) slip and instability of CRCS are characterized by stick-slip first and then stable slip, accompanied with high P-wave velocity and rockburst danger coefficient based on microseismic tomography.
Highlights
Introduction of the7301 Working Face. e 7301 working face with buried depth of 962 to 1037 m is the first fully mechanized top-coal caving face in the #7 mining area of Zhaolou coal mine (ZCM), with strike and slope lengths of 1678 and 230 m, respectively. e working face is characterized by strong rockburst danger
Rock Parting Slip Triggered by Roadway Excavation
(1) Fracture and slip of rock parting: a line-monitoring horizontal displacement was set with the interval of 0.5 m, and a total of 30 points were set for each line. e horizontal displacement value of each point is shown in Figure 8. e black vertical line in middle part represents the rock parting sandwiched between top and bottom coal blocks. e difference of horizontal displacements of the monitoring points indicates the fracture level of rock parting, and the difference of the points on both sides of the interface indicates slip. e fluctuation of horizontal displacement indicates the fracture of blocks
Summary
E size of numerical simulation model is consistent with that of the samples tested in laboratory. Erefore, the stress value of initial shear cracks can be used as the threshold of crack damage, which was 95.33% and 92.92% of UCS, respectively.
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