煤矿地下水库储水空间构成分析及计算方法

Analysis and calculation method of underground reservoir water storage space composition

针对西部近水平煤层煤矿地下水库有效储水空间难以确定的问题,提出了利用地下水库上覆各分界岩层的垂直位移轨迹方程计算各分带岩层冒落前后的体积差,从而确定煤矿地下水库不同分带内岩层的有效储水空间,解决了现有煤矿地下水库储水系数难以确定,导致地下水库储水空间计算困难的问题。基于工作面上覆岩层断裂分带划分结果,确定煤矿地下水库的主要储水空间为垮落带与块体铰接带垮落岩层的空隙、裂隙与离层空间,得出了近水平煤层垮落带与块体铰接带有效储水空间的计算表达式。基于结构力学与断裂力学理论,分析了垮落带分界岩层可能形成的3种不同结构形式,推导了砌体梁结构、台阶岩梁结构及完全垮落情况下工作面上覆垮落带、块体铰接带分界岩层的垂直位移轨迹方程,得出了上覆不同岩层结构煤矿地下水库的有效储水空间理论计算表达式。以大柳塔煤矿近水平煤层煤矿地下水库工程实践为依托,采用UDEC数值模拟计算方法分析了工作面上覆岩层的断裂结构,研究得出了地下水库上覆各分界岩层的垂直位移轨迹曲线,发现地下水库四周边界位置较中间位置的垂直位移量小,即四周边界位置具有更大的储水空间。采用理论分析与数值模拟相结合的方法,对各分界岩层的垂直位移曲线进行了拟合分析,得出了煤矿地下水库的有效储水空间。基于不同计算时步上覆岩层垂直位移曲线的差异,分析了煤矿地下水库储水空间的时空演化规律。通过在大柳塔煤矿进行现场抽放水试验,验证了上述煤矿地下水库有效储水空间计算方法的可行性及计算结果的可靠性。

In terms of the problem in calculating underground reservoir water storage space in the nearly horizontal coal seam at the coal mines in Western China,the calculation method,which uses the vertical displacement trajectory equation of different boundary strata to calculate the difference in volume before and after caving,was put forward. The method could calculate the effective reservoir space of different rock zones and solve the problem of confirming the storage coefficient for calculating the underground reservoir water storage space.Based on the dividing results of fracture zoning of overlying strata,the main water storage space of underground reservoir was the gap,crack and separation space of caving strata and block hinged zone,and the calculation expression of effective water storage space in nearly horizontal coal seam was obtained.The three different structure forms,which might be formed in the boundary strata of caved zone,were analyzed based on structural mechanics and fracture mechanics theory.The vertical displacement trajectory equation of masonry beam structure,step beam structure and fully caving condition were studied.The theoretical calculation equations of effective water storage space of different rock structures were obtained.The fracture structure of overlying strata was analyzed using the UDEC numerical simulation calculation method based on the engineering practice of Daliuta coal mine.The path curves of vertical displacement boundary strata were obtained.The vertical displacement around the underground reservoir was smaller than the middle position,which means bigger storage space. The vertical displacement curves of each boundary rock strata were fitted and analyzed by using the method of theoretical analysis and numerical simulation,and the effective water storage space of underground reservoir was obtained.The spatio-temporal evolution law of water storage space was analyzed based on the difference of vertical displacement curves of overlying strata in different calculation times.The feasibility and reliability of the calculation method for the effective storage space were verified by the field drainage test in Daliuta Coal Mine.