覆岩组合结构下导水裂隙带演化规律与发育高度分析

Evolution rule and development height of permeable fractured zone under combined-strata structure

根据导水裂隙带发育规律与岩层结构及其运动特征的相关性,提出了基于覆岩组合结构与岩层拉伸变形计算的导水裂隙带高度预计新方法。研究发现覆岩导水裂隙带应是以岩层组为单位呈阶梯状向上发育的,每个岩层组由下部强度因素高的坚硬岩层与上部软弱岩层组成;通过理论分析,提出以岩层层向拉伸率为判据来判断岩层组的下沉变形及裂隙发育程度,只要确定各岩层组中的下位坚硬岩层的拉伸率变化拐点就可以较为准确地分析该岩层组的裂隙发育度,从而准确预测导水裂隙带发育高度。在考虑覆岩垮落碎胀特性的基础上,推导得到了较为合理的岩层层向拉伸率计算公式。经过现场实测验证,该方法理论预计的导高值与现场实测结果非常吻合。

According to the correlation between the developing rule and strata structure of the perme- able fractured zone and its movement feature, this paper proposed a new method to predict the devel- opment height of the permeable fractured zone based on the overburden combined strata structure and tensile deformation calculation. The results have shown that the permeable fractured zone should de- velop upward ladder-likely with units of strata groups made up by lower hard rock stratum and upper soft strata; through theoretical analysis, the tensile ratio of middle layer of stratum was proposed to es- timate the subsidence, deformation and the development degree of cracks in each strata group. The height of permeable fractured zone can be predicted accurately after the accurate analysis of the devel- opment degree of the cracks in the strata group through spotting the inflection point of lower hard stra- tum＇s tensile ratio curve; based on the calculation of strata group subsidence and the factor of stratum bulking coefficient, the reasonable formula of tensile ratio of middle layer of stratum was formed. Theresult predicted by this method was consistent with the field observation.