膏体充填开采条带煤柱覆岩稳定效应研究

Study on effect of overlying strata stability during strip coal pillar excavation with paste backfilling

针对膏体充填开采回收矿井条带煤柱中的覆岩稳定性问题,以许厂煤矿建筑物下条带煤柱开采为工程背景,采用理论分析、数值模拟和现场实测的方法,研究了膏体充填回收煤柱时的覆岩"活化"机理、顶板运移规律及覆岩稳定性影响因素。研究结果表明:采空区在外力扰动下会产生空洞、裂隙,随着岩块结构的演变,其对采场覆岩支护体系造成破坏,可通过控制充填体强度、充填率、充填步距及支护强度来改善采场围岩支护体系,要求充填体早期强度应大于0.13 MPa,而后期强度可按照与充填体宽度变化规律进行适当调整;模拟试验结果发现:覆岩及地表下沉曲线峰值位于条带煤柱中部区域,顶板最大下沉量为1 200 mm,邻近采空区覆岩"活化"程度达到最大;采取膏体充填开采回收煤柱,巷道矿压显现不明显,工程应用中取得了良好效果。

According to stability problem of mining strip coal pillars with paste backfilling,based on engineering background of mining strip coal pillars under buildings in Xuchang Coal Mine,the overburden ＂ activation＂ mechanism,laws of roof movement and influence factors of stability were studied by the method of theory analysis,numerical simulation and field measurement. The results showed that the cavity,fracture and rock mass structure in the goaf would evolve under the external force disturbance,and the rock support system of stope would be destroyed. The support of surrounding rock can be improved by controlling the strength of filling body,the filling rate,the stowing interval and the supporting strength. In the meantime,it demanded that early strength of the filling body must be greater than 0.13 MPa,and the later strength should be adjusted according to the change law of the width of filling body.The simulation results revealed that the peak value of overlying strata and surface subsidence curve was located in the central coal pillar area and the overlying strata was affected significantly by adjacent goaf. The 1 200 mm subsidence value reached the maximum at the center of working face. The strata behaviors was not obvious in process of mining strip coal pillars with paste backfilling and good effect in engineering application was obtained.