采动影响下损伤煤岩体峰后渗透率演化模型研究

Research on mining-induced permeability evolution model of damaged coal in post-peak stage

在对比分析煤岩体峰前和峰后阶段渗透率演化规律差异的基础上,通过考虑开挖损伤对煤岩体渗透率的影响,基于裂隙平板模型建立了考虑损伤效应的峰后煤岩体渗透率模型;将实验测试数据与渗透率模型计算结果进行对比分析,验证了渗透率模型的合理性.基于此模型,具体分析了3种典型开采方式下(保护层开采,放顶煤开采和无煤柱开采)工作面前方煤岩体渗透率分布特征.研究结果表明:峰前和峰后阶段煤岩体渗透率均随应力呈现指数增长趋势,但两者在增长量上存在明显不同;根据渗透率分布特征,可以将工作面前方煤岩体划分为4个区域:渗流开放区,渗流屏蔽区,渗流过渡区和原岩渗流区;3种开采方式对工作面前方煤岩体的瓦斯渗流影响规律相似,但是在影响区域范围上存在较大差异.

Based on the permeability difference between pre-peak stage and post-peak stage,this paper considered the influence of excavation damage on coal permeability and established a postpeak permeability model based on the parallel plate model.The rationality of post-peak permeability model was verified through the comparison with permeability experiment.Based on this model,the permeability distribution characteristics of coal in front of working face were analyzed under three kinds of typical mining methods（protected coal seam mining,top-coal caving and non-pillar mining）.The results show that the coal permeability increases in an exponential form both in pre-peak stage and in post-peak stage,but the increment degrees are different.According to the permeability characteristics of coal in front of working face,the coal seam can be divided into four zones,including full flow zone,flow-shielding zone,transitive flow zone and in-situ rock flow zone.The influences of three kinds of typical mining methods on the gas seepage property are similar,while the sizes of influence area are different.