Short-crossbeam backfill in gob-side entry retaining is prone to lateral instability due to the caving gangue compression from gob, and lateral force point and angle are key influence factors on the stability. The instability of short crossbeam manifested as normal-stress bending failure and shear-stress cutting failure. The optimal bearing zone was in the transition zone between shear and compression. As loading point moved to the end, normal-stress failure load increased with crack propagation from the middle to the end, and shear-stress cutting load appeared at the position near the end and crack propagated towards the support point. Failure load was positively correlated with AE information, the correlation coefficients of loading positions and angles were 0.9722 and 0.9006 respectively. The influence of loading angle was less on failure load than the one of loading position: failure load increased by 2.60 times and by 1.16 times with loading position from the middle to the end and with loading angle from 0° to 30° respectively. The higher failure load, the greater fracture energy, the simpler crack propagation, and the more vertical the crack. The theoretical failure load of the maximum loading angle was consistent with the test result with 0.84% difference.
Key Words
AE information; failure process; intensity characteristics; mechanical model; normal-shear stress; short crossbeam support
Address
Yajun Xin — School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan, China; Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization, Jiaozuo, Henan, China
Qi Liu — School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan, China
Hongying Ji — School of Resources and Environment, Henan Polytechnic University, Jiaozuo, Henan, China
Yinquan Liang — Yunnan Dongyuan Zhenxiong Coal Industry Co., Ltd., Zhaotong, Yunnan, China
Jichun Kang — School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan, China
Jinwu Ren — Yonghua Energy Co., Ltd., Henan Energy and Chemical Industry Group, Luoyang, Henan, China
Hongjuan Dong — Mining Institute, Inner Mongolia Science and Technology University, Baotou, Inner Mongolia, China
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