基于岩层移动计算的工作面覆岩体渗透率变化研究

Study on the permeability change of overlying strata based on strata movement calculations

为了揭示在采动影响下工作面上覆岩层在垮落、变形过程中导致的渗透率变化,对广泛应用于地表开采沉陷预测的影响函数法进行函数的修正与优化,设计了计算步骤并将其应用到地表下岩层内部的变形移动计算,建立了基于影响函数法的采动岩层移动预计模型,获得了岩层水平及垂直方向的应变描述。结合煤岩体渗透率的计算模型,建立了"面应变-孔隙率-渗透率"的描述煤岩体渗透率变化的表征模型。以某浅埋深工作面开采时期地表及覆岩层移动的现场观测数据为依据,对建立的岩层移动预测模型的可靠性进行了检验。结果表明:该模型的计算结果可靠性高,可以进一步应用其来计算展示该工作面在开采过后覆岩层的渗透率变化情况。

In order to calculate the permeability change of overlying strata caused by the strata caving and deformation during mining, the influence-function method, which is widely applied to the surface subsidence prediction, is revised and optimized in this study. Meanwhile, the detail steps are designed to calculate the strata deformation and movement, establishing the subsurface strata-movement-prediction model based on the influence-function method. Both the horizontal and vertical strain could be derived by above-mentioned model. Furthermore, according to the permeability model of coal and rock mass, a method of ＂strain-porosity-permeability＂ for characterizing permeability change is established. The re- liability of the subsurface strata-movement-prediction model is tested, based on the field data of surface and overlying strata movement during mining in a shallow coal seam. Results indicate that this model has high reliability, and could also be applied to calculate the permeability change of overlying strata after mining activities.