沿空留巷柔模砼墙支护阻力核定及失稳判据研究
Research on Resistance Verification and Instability Criterion of Flexible Formwork Concrete Wall Support for Leaving Tunnels Along the Gob
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摘要: 柔模砼墙沿空留巷工作面覆岩垮落结构与砼墙的稳定性是留巷成功与否的关键。因此,以大柳塔煤矿52606柔模砼墙沿空留巷工作面为研究背景,运用物理模拟和理论分析相结合的方法,分析工作面开采过程中覆岩垮落结构,计算留巷围岩稳定与复用阶段砼墙的支护阻力,确定不同留巷阶段砼墙的安全系数。结果表明:在相似模拟实验中,两工作面回采结束后,砼墙上方覆岩垮落呈短悬臂梁结构,且砼墙侧垮落角均大于煤壁侧垮落角;沿空巷道顶板第一次断裂位置位于采空区上方砼墙一侧,第二次断裂位置位于已形成悬臂梁结构的上位覆岩中,并得到计算砼墙支护阻力所需的力学参数;不同采动影响阶段砼墙的稳定状态与砼墙的极限载荷和实际载荷之比N有关,工作面回采过程中保证N >1则砼墙不会发生失稳破坏。该研究结果可为我国柔模砼墙沿空留巷工作面砼墙失稳判定和顶板控制提供重要的理论依据。Abstract: The stability of the overburden rock caving structure and concrete wall in gob-side entry retaining using a flexible formwork concrete wall is crucial for its success. This study focuses on the 52606 flexible formwork concrete wall in the Daliuta Coal Mine. By combining physical simulation and theoretical analysis, we examined the caving structure of overburden rock during the mining process and calculated the stability of the surrounding rock in the retaining roadway. The support resistance of the concrete wall in different stages determines its safety factor. Results from the simulation experiment reveal that after mining the two working faces, the collapse of the overlying strata above the concrete wall forms a short cantilever beam structure, with a larger collapse angle on the concrete wall side compared to the coal wall side. The first fracture position of the roadway roof along the goaf is on the side of the concrete wall above the goaf, while the second fracture position is in the upper overburden rock forming the cantilever beam structure. The mechanical parameters needed to calculate the concrete wall's support resistance were obtained. The stability of the concrete wall during different mining stages is related to the ratio N of the ultimate load to the actual load. When N > 1, the concrete wall remains stable during the mining process. This study provides a significant theoretical basis for determining instability and controlling the roof in gob-side entry retaining with a flexible formwork concrete wall in China.
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Key words:
- soft concrete wall /
- similar simulation /
- support resistance /
- collapsed structure /
- safety factor
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