In order to solve the problem that the stability of main roof and gob-side entry retaining(GER) was seriously affected by soft and broken immediate roof,UDEC Trigon model,based on No.3414 mining face of Xinyuan Coal Mine,was established to simulate the fracture characteristics of lower strata in GER under different support conditions and the effect on the stability of the surrounding rock of GER was analyzed.The results showed that the fracture in the surrounding rock of GER was mainly composed of shear cracks,and tensions cracks were more in the roof of filling area which was the weak link in the control of surrounding rock in GER.When the lower strata broke outside the backfilled body,the development of the shear cracks in coal rib was inhibited and the stability of the load-bearing structure make up of backfilled body and coal rib was increased.The engineering practice showed that the lower strata broke outside the backfilled body,the convergence between roof and floor was 900 mm,and the convergence between ribs was 800 mm,which was appropriate to ventilation and gas emissions,after the adoption of high prestressed and high rigidity anchor cable in the roof of filling area.%为解决沿空留巷直接顶松软破碎,严重影响基本顶和沿空留巷稳定性的问题,以新元煤矿3414工作面为研究对象,建立UDEC Trigon模型,通过模拟不同支护条件下沿空留巷下位岩层断裂特征,分析其对围岩稳定性的影响.数值模拟发现,沿空留巷围岩以剪切裂隙为主;充填区顶板张拉裂隙较为发育,是沿空留巷围岩控制的薄弱环节;沿空留巷下位岩层沿充填体外侧断裂,抑制了剪切裂隙在实体煤帮发展,增加了巷旁充填体和实体煤帮的承载结构的稳定性.工程实践表明:采用高预应力、高刚度锚索及时支护充填区直接顶的围岩综合控制技术,沿空留巷下位岩层沿充填体外侧断裂,巷道围岩顶底板最大变形量为900 mm,两帮最大变形量为800 mm,能够满足通风和瓦斯排放的要求.
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