基于卸荷试验路径的泥岩变形特征及数值计算

The deformation properties of mudstone and numerical calculation based on unloading path

通过先固结后径向卸载的三轴剪切试验方法模拟煤矿泥岩巷道开挖过程中应力状态变化,在试验围压内,径向卸荷条件可以用Drucker-Prager强度准则较好地描述软岩破坏过程。蠕变试验结果表明:随偏应力水平的降低,蠕变速率明显减小,当偏应力水平较低时(1.0 MPa),轴向蠕变无变化,蠕变速率几乎为0;当轴应力较高时(3.5 MPa),泥岩蠕变过程经历减速、定常和加速蠕变3个阶段。根据试验提出了泥岩的弹黏塑流变本构模型,将泥岩的蠕变试验结果与计算值进行对比:两者变形规律完全一致且数值较吻合,从而验证了泥岩本构模型的正确性。

The stress state in coalmine mudstone roadway excavation process was simulated by the triaxial shear test through the method of first consolidation then radial unloading.The radial unloading conditions of the test in the confining pressure can use the Drucker-Prager strength criterion,it can well describe the soft-rock failure process.The creep test results show that the creep rate reduce obviously with the deviatoric stress level decrease,the axial creep unchanged when the deviatoric stress level is lower（1.0 MPa）,the creep rate is almost zero;the mudstone creep process goes through deceleration,steady and acceleration these three stages when the axial stress is higher（3.5 MPa）.The elasto-viscoplastic rheological constitutive model of mudstone was proposed based on the test.Compared the test results and the calculated value,it shows that their deformation laws are complete consistency and their values are more anastomosis,thus the correctness of the constitutive model of mudstone is verified.