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通过煤岩热流固耦合试验系统(THM-2)对砂岩进行循环加、卸载试验,研究加、卸载速率对其变形和渗透特性的影响.结果表明:初始循环时,岩石的轴向变形量Δε1较大,随着循环试验的进行,Δε1趋于稳定,受卸载速率v2的影响较小.加载变形模量和卸载变形模量均逐渐上升,随着循环次数的增加,上升速度逐渐变缓;同一循环内,卸载变形模量大于加载变形模量,且随着加、卸载的进行,差值逐渐减小.加载阶段和卸载阶段渗透率变化量的差值随着循环次数的增加逐渐减小;从第5次循环开始,渗透率曲线呈“∞”形,渗透率演化规律可以用轴向应变的变化特点表征,轴向应变的变化量Δεi1受到卸载速率vi2和应力加载上限σimax的综合作用,二者对应变在卸载初期起到积极的促进作用,三者之间的相互关系可用幂函数表达.
The effects of loading and unloading rates on the deformation and infiltration properties of sandstone were investigated by cyclic loading and unloading tests of THM-2 coal rock.The results show that the axial deformation Δε1 Larger, with the cyclic test, Δε1 tends to be stable and less affected by the unloading rate v2.The loading deformation modulus and unloading deformation modulus both increase gradually, and the ascending speed gradually decreases with the increase of circulation times; In the same cycle, the unloading deformation modulus is larger than the loading deformation modulus, and the difference gradually decreases with the loading and unloading, and the difference between the permeability variation during the loading phase and the unloading phase decreases with the increase of the number of cycles From the fifth cycle, the permeability curve shows “∞ ” shape. The law of permeability evolution can be characterized by the change characteristics of axial strain. The variation of axial strain Δεi1 is affected by the unloading rate vi2 and the upper stress limit σimax Combined effect, the two of the strain relief play a positive role in the early uninstall, the relationship between the three power function can be expressed.