高应力泥质粉砂岩非线性蠕变损伤模型研究

为了研究高应力作用下泥质粉砂岩蠕变损伤特性，针对深埋硐室围岩和高陡边坡长期受高应力作用产生的蠕变影响，采用三轴流变试验仪对泥质粉砂岩进行分级增量加载研究其蠕变损伤特性。通过蠕变试验结果分析高应力泥质粉砂岩在硬化和软化2个阶段的不同损伤演化规律，硬化阶段考虑弹性模量、应力水平和应力作用时间综合影响的蠕变损伤效应；软化阶段基于损伤力学原理分析泥质粉砂岩在高应力作用下的蠕变损伤演化特性。通过建立考虑不同因素影响下的高应力泥质粉砂岩损伤演化方程，最终构建符合其蠕变特性的非线性蠕变损伤本构模型，并对改进后的蠕变模型参数进行识别反演。研究结果表明：高应力泥质粉砂岩的蠕变呈现明显的非线性特征，且蠕变硬化和软化特征明显，硬化阶段蠕变损伤变量随着应力水平的增大而增大，且随着时间增加而趋于稳定值；软化阶段蠕变损伤因子随应力水平和时间的增加呈明显的增长趋势，由此可见，高应力泥质粉砂岩蠕变在不同阶段其损伤受应力水平和应力作用时间的影响呈现明显的正相关趋势，说明该模型能够较好地反映泥质粉砂岩在高应力作用下应力水平与时间效应对蠕变损伤特性的影响，试验曲线与理论模型较为符合，研究成果可对高应力泥质粉砂岩深埋硐室及巷道围岩支护提供理论指导意义。

Research on Nonlinear Creep Damage Model of High Stress Argillaceous Siltstone

In order to investigate creep damage characteristics of argillaceous siltstone under the high stress, aiming at the creep effect of the surrounding rock of the deep weak roadway and high-steep slope Long-term subjected to high tress, the argillaceous siltstone was graded and incrementally loaded by using the triaxial rheological tester.Based on the results of creep tests, the different damage evolution of high stress argillaceous siltstone in the stages of hardening and softening were analyzed.The hardening stage took the comprehensive creep damage effect influenced by elastic modulus, stress level and stress acting time into consideration.In the softening stage, the creep damage evolution characteristics of muddy siltstone under high stress were analyzed based on the principle of damage mechanics.The damage evolution equation of high stress and argillaceous siltstone under the influence of different factors was established, and finally the nonlinear creep damage constitutive model was established according to its creep characteristics.Then improved creep model parameters were identified and retrieved.The results show that the creep of high stress muddy siltstone reflects obviously nonlinear characteristics,and the creep hardening and softening characteristics are also obvious.The creep damage variable in the hardening stage increases with the increase of the stress level, and tends to be stable with the increase of time.The creep damage factor increases with the stress level and time in the softening stage.Thus, the creep of high stress and argillaceous siltstone at different stages shows a significant positive correlation with the impact of stress level and stress time.It is shown that the model can better reflect the influence of stress level and time effect on the creep damage characteristics of high stress argillaceous siltstone.The test curves are in good agreement with the theoretical model,and provide theoretical guidance for the support of deep stress chamber and roadway surrounding rock of high stress muddy siltstone.