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针对构造煤渗透率对轴向应力循环加卸载的响应特征,利用自行研制的含瓦斯煤热–流–固耦合三轴渗流试验装置,进行试验研究,并结合试验结果进行渗透率动态模型分析,结果表明:含瓦斯构造煤的渗透率与应变的关系呈斜“V”字型走势,峰值强度后,煤样渗透率增加趋势明显,且增速大于初始压缩阶段渗透率的降速;煤样渗透率与轴向应力在加卸载过程中符合负指数函数分布,渗透率在加载过程中减小,卸载过程中有所恢复,渗透率与有效应力未形成封闭曲线,循环加卸载使煤样中孔隙进一步压缩,渗透率损失量增大,同时渗透率对于有效应力的敏感度降低;通过引入加载过程渗透率敏感性损失因子及卸载过程中渗透率损耗因子,建立循环加卸载过程中渗透率与有效应力的动态演化模型,试验数据与理论计算数据对比验证了模型的适用性。
Aimed at the response characteristics of tectonic coal permeability to cyclic stress unloading and unloading, the self-developed gas-coal-thermal-fluid-solid coupling three-axis seepage test device was used to carry out experimental research. Combined with the experimental results, the dynamic model of permeability was analyzed. The results show that the relationship between permeability and strain of coal containing gas is inclined and the peak value of permeability increases obviously, and the growth rate is faster than that of the initial compression stage. The permeability and axial stress of coal samples conform to the negative exponential distribution during loading and unloading, and the permeability decreases during loading and recovery during unloading. The closed curve of permeability and effective stress is not formed. In the sample, the pores are further compressed, and the loss of permeability increases. At the same time, the sensitivity of permeability to effective stress decreases. By introducing the permeability sensitivity loss factor during the loading process and the permeability loss factor during unloading, the permeability during cyclic loading and unloading is established The dynamic evolution model of the rate and the effective stress, the test data and the theoretical calculation data verify the applicability of the model.