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为了研究覆岩导水裂缝带内裂隙岩层导水性与覆岩岩层层向拉伸变形的关系,定义了岩层中间层的概念;在假定可以用两段圆弧拟合岩层下沉盆地内外边缘曲线的条件下,导出了岩层层向拉伸率ε的计算公式;统计了近年来的井下导高观测成果。研究得出:当岩层中间层层向拉伸率超过岩石拉伸变形极限时,岩层会产生法向拉伸裂隙;当岩层层向拉伸率大于其临界拉伸率时,该岩层就会成为导水裂缝岩层。岩层层向拉伸率ε主要受岩层层位高度h,煤层采厚m,岩层下沉系数q,边界角δ0和充分采动角ψ等因素的影响。回归分析得出:覆岩岩层越坚硬,则裂采比就越大,导水裂缝带顶部岩层层向临界拉伸率ε0值就越小。
In order to study the relationship between the conductivity of fractured rock strata and the tensile deformation of overburden rock strata, the concept of middle strata is defined. In the assumption that two sections of arc can fit the curve of the inner and outer edge of the subsidence basin , The formula for calculating the layer stretch rate ε is deduced. The observation results of downhole conductivity in recent years are calculated. The study shows that when the stretch rate in middle layer of rock strata exceeds the limit of tensile deformation of rock, the rock strata will produce normal tensile fracture; when rock strata stretching rate is higher than its critical tensile rate, rock strata will become Water-conducting fractures. The layer stretch rate ε is mainly affected by such factors as the height of the strata h, the mining thickness m, the subsidence coefficient q, the boundary angle δ0 and the full mining angle ψ. The regression analysis shows that the harder the overburden strata, the greater the ratio of fracturing to production, and the smaller the value of ε0 to the critical stretch ratio of the strata at the top of the aqueduct.