水平割缝和顶板压裂复合作用下煤柱卸压效果数值模拟分析

Numerical simulation analysis of pressure relief effect under the combined action of horizontal slotting and roof fracturing

针对多巷布置工作面回采过程中煤柱应力集中程度大、巷道变形量大的问题,采用水平割缝+顶板压裂的双重手段对煤柱和顶板进行弱化卸压,旨在降低煤柱承载的应力水平,改变应力分配比例,使应力集中区向实体煤深部转移。在对煤柱留巷侧向顶板破断结构与应力分布情况以及水平割缝和顶板压裂复合作用下的煤柱卸压机理分析基础上,以纳林河二号矿井为研究对象进行了数值模拟分析,分析结果表明:采取割缝间距2 m+临巷侧保留5 m煤柱不割方案,应力向实体煤侧转移,实体煤侧承压范围主要在1~15 m范围内,相较于未采取任何卸压措施应力降低约30%;采取超高压水力割缝+压裂断顶方案后,保护煤柱侧应力大幅降低,基本处于原岩应力状态,不存在应力集中,应力相较于未采取任何卸压措施降低47%。

For the large coal pillar stress concentration degree and the large roadway deformation in the process of mining in multi-lane layout face,to reduce the stress level of coal pillar,change the stress distribution ratio and transfer the stress concentration area to the deep part of solid coal,a dual method of horizontal slotting and roof fracturing is used to weaken the pressure relief of coal pillar and roof in the process of multi-roadway mining.Based on the analysis of the fracture structure and stress distribution of the side roof of the coal pillar retaining roadway and the pressure relief mechanism of the coal pillar under the combined action of horizontal cutting and roof fracturing,the numerical simulation analysis is carried out for the No.2 well of Nalinhe Coal Mine.The results of analysis indicate that when the slotting spacing is 2 m and the coal pillar near the roadway is reserved at 5 m,the pressure bearing range of coal side is mainly in the range of 1-15 m,which is about 30%lower than that without any pressure relief measures;after adopting the scheme of ultra-high pressure hydraulic cutting+fracturing and roof breaking,the stress on the side of protective coal pillar is greatly reduced,which is basically in the original rock stress state,without stress concentration,and the stress is 47%lower than that without any pressure relief measures.