支承压力区裂隙闭合度变化对渗透率的影响
Effect of Crack Closure on Permeability in Abutment Pressure Area
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摘要: 建立了裂隙闭合度力学模型,结合支承压力表达式,计算得出了裂隙闭合区域范围。分析了支承压力区裂隙闭合度的变化过程以及裂隙闭合度变化对渗透率的影响。结果表明:原岩应力大于某个值时,支承压力区裂隙经历了“完全闭合-部分张开-完全张开”的过程,渗透率经历了“缓慢增加-快速增加-突跳式增加”的过程;原岩应力小于某个值时,支承压力区裂隙经历了“完全张开-部分闭合-完全张开”的过程,渗透率经历了“缓慢增加-减小-突跳式增加”的过程。同时利用comsol数值模拟软件,模拟了支承压力区煤体渗透率的变化情况,数值模拟结果与理论计算结果一致。Abstract: The mechanical model of crack closure was established, and the zone of crack closure was calculated combining with the abutment pressure formula. The crack closure evolution in the abutment pressure area was analyzed, based on which the rule of permeability evolution in the abutment pressure zone was obtained. The results show that: in the abutment pressure area, when the original stress is bigger than a certain value, the cracks experience the process of “completely closed - partially open - fully open” and permeability undergoes a process of “slow increase-rapid increase-sudden increase”; when the original stress is smaller than a certain value, the cracks experience the process of “fully open-partially closed-completely open” and permeability undergoes a process of “slow increase-decrease-sudden increase”. In the end, the numerical software of comsol was used to simulate the permeability evolution in the abutment pressure area and the result was consistent with the theoretical analysis.