司马矿薄基岩区顶板突水危险性数值模拟研究

A numerically simulated model on the waterinrush risk under the geo-condition of thin rock-mass with thick-loose bed in Sima coal mine

为了研究司马矿薄基岩厚松散层特殊地质条件下的采动覆岩破坏、渗流等特性,评价发生顶板突水的危险性,建立了薄基岩厚松散层开采条件下的数值计算模型。采用理论分析、数值模拟和现场工程相结合的方法,利用多物理场耦合数值模拟软件COMSOL Multiphysics,研究了随工作面推进采场的变形、破坏、渗流和应力变化规律。结果表明:在司马矿薄基岩厚松散层这一特定的地质条件下,工作面涌水量、顶板破坏高度均随工作面推进不断增加并最终趋于稳定,当工作面推进到200 m时,顶板破坏高度约为80 m,工作面涌水量约为33 m3/min,与实测数据基本吻合;随着开采的进行,在采空区后方煤层的支承压力峰值位置几乎不变,在工作面前方形成的支承压力峰值极值点位置不断前移,应力集中系数约为2.0;在司马矿薄基岩区,在煤层采厚为5 m、基岩厚度为40 m的条件下,若顶板黏土层厚度大于40 m,将不会发生顶板突水。

In this paper, we have proposed a numerically simulated model on the waterinrush risk under the geocondition of the thin rockmass with thickloose bed in Sima coal mine. In proceeding with our research, we have first of all done detailed investigations as to the roof fractures evolution and seepage characteristics under the special geoconditions of the thin rockmass with the loose bed in the mine. At the same time, we have evaluated the risk of the roof water inrush and in turn established a numerical model in close conformity with the geological features of the mine. To push our work further, we have been adopting method after method, including the theoretical analy sis, numerical simulation and practical examination of the actual geo situation, with the help of the numerical software COMSOL multi physics for tracing the regularities of the geological deformation, fail ure, seepage and overstress with the working headface under the thin rock mass conditions with loose bed. The numerical simulation results give us enlightenment that ： the roof deformation tends to increase with the advancement of working faces and with the great displacement of the rocks in the middle of stope and smaller deformation for the rocks that stand on the two sides, plus the displacement for the mining floor, which indicates there must have happened the floor heave, the roof failure height or the water rushin with the working face advanc ing at the beginning and then has come to get stabilized in the end. With the former and latter taking place in the underground surface of 80 m and 33 m3/min respectively, particularly, when the working face advanced to 200 m, both of which agree with the field＇ measure ment data ; With the advancing of the working face, a particular situ ation is likely to happen with the supporting pressure peak and the value position behind the minedout area keeping stable, while the supporting pressure position with peak value in front of goaf moved as the advancement of working face and the stress concentration coeffi cient being 2.0; the results of the numerical simulation prove that for the thin rock area in Sima coal mine, under the condition, when the mining height reaches 5 m and the rock thickness is 40 m, there would be no roof waterinrush if the thickness of clay bed in the roof is over 40 m.