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基于自主研发的煤岩热流固耦合试验系统,在考虑实际开采方式的条件下,进行轴压升高和围压降低的加卸载试验,分析研究不同加卸载速率下原煤的力学特性和渗透演化规律.结果表明:加卸载过程中,轴向应力的加载速率越大,峰值应力附近的曲线平台越长,峰值应力、轴向应变和环向应变也越大,体应变则越小.不同加卸载速率比下含瓦斯煤变形模量均先迅速减小后缓慢减小,到破坏时再迅速降低,而后逐渐保持稳定趋势;在相同轴向应变时,加卸载速率比越小,煤样的变形模量越大.加卸载过程中,煤样的偏应力、渗透率与应变的关系可分为三个阶段:初始压密与弹性阶段、屈服破坏阶段和破坏后阶段.加卸载速率比越小,煤样达到峰值应力时,含瓦斯煤的渗透率和体积变形越大.
Based on the self-developed coal-rock thermal-fluid-solid coupling test system, under the conditions of actual mining method, the unloading test of axial pressure rise and confining pressure reduction is carried out, and the mechanical properties and infiltration evolution of raw coal under different loading and unloading rates are analyzed The results show that the greater the loading rate of axial stress during loading and unloading, the longer the curve platform near the peak stress, the greater the peak stress, axial strain and hoop strain, and the smaller the body strain. The deformation modulus of gas containing coal decreases rapidly and then decreases slowly, and then decreases rapidly when it destructs, and then gradually maintains a steady trend; at the same axial strain, the rate of loading and unloading is smaller, the deformation of coal sample The bigger the modulus is, the more the stress, permeability and strain of the coal sample during loading and unloading can be divided into three stages: initial compaction and elastic stage, yield failure stage and post-damage stage.The smaller the loading / unloading rate ratio is, When the coal sample reaches the peak stress, the permeability and volume deformation of gas containing coal will increase.