回采工作面多巷布置留巷围岩变形特征与支护技术

CHARACTERISTICS OF SURROUNDING ROCK DEFORMATION AND REINFORCEMENT TECHNOLOGY OF RETAINED ENTRY IN WORKING FACE WITH MULTI-ENTRY LAYOUT

以晋城矿区回采工作面多巷布置留巷为工程背景,基于大量实测数据,分析留巷围岩变形与破坏的特征及机制。采用数值模拟软件FLAC3D研究巷道布置方式、煤柱尺寸、回采工作面宽度等参数对留巷围岩变形与破坏的影响,分析留巷及采煤工作面周围的应力分布。在此基础上,提出适合留巷特点的巷道支护形式与参数。在井下进行支护试验,监测留巷从掘进到报废全过程的围岩位移与支护体受力,评价支护效果。研究结果表明:留巷在受到本工作面超前支承压力作用后,围岩位移虽有增加,但变化不大;在本工作面后方一定距离围岩位移急剧增加,并在50～200 m范围内位移速度达到最大值,之后逐步趋于稳定;当留巷受到下一个工作面超前支承压力作用后,围岩位移再次显著增加。留巷围岩变形与巷道布置方式、煤柱尺寸及回采工作面参数密切相关。高预应力强力锚杆与锚索支护、全锚索支护是比较适合留巷的支护方式,能够大幅度减少围岩位移,保持巷道长期稳定。最后分析存在的问题,并提出改进意见。

Based on the entries retained for next working face in the multi-entry system in Jincheng mining district, and a large quantity of monitoring data collected in these entries, the characteristics and mechanisms of deformation and damage associated with these entries are analyzed. Numerical simulation code FLAC3~ is utilized to analyze the effects of entry layout pattern, coal pillar size, and face width on the deformation and damage of the entries retained for next face~ and the stress distribution around the entries and faces are calculated. The reinforcement patterns and parameters suitable for entries retained for next face are proposed based on above researches. Underground tests are carried out the surrounding rock displacements, rock bolt and cable loads are monitored during the whole service period of the entries retained; and the reinforcement performance is evaluated.The research results show： when the entry retained is originally affected by the front abutment stress of the current face, the surrounding rock displacement increases moderately; when the current working face advances past the entry retained for a certain distance, the surrounding rock displacement increases sharply; the peak of displacement velocity appears when the working face is 50 - 200 m away; and then the displacement is tending towards stability; when the entry retained is affected by the front abutment stress of the next face, the surrounding rock displacement increases evidently again. The deformation of the entries retained is closely connected with entry layout patterns, coal pillar size and the parameters of working faces. The rock bolts and cables with high pretension and intensive strength, and the cable bolting set in full entry section are fit for the entries retained, which can reduce surrounding rock displacements greatly and keep the entries stable for a long time. Finally, the existing faults are also addressed and some improvement suggestions are provided.