干湿循环对炭质泥岩蠕变及损伤特性的影响

为揭示炭质泥岩库岸边坡的时效变形和损伤特性，对经历不同干湿循环次数的炭质泥岩试样进行低场核磁共振和三轴压缩流变试验，研究炭质泥岩孔隙演化特征和蠕变特性；在此基础上，基于损伤理论和Lemaitre应变等效原理，建立考虑干湿循环、轴压和时间因素耦合影响的蠕变损伤方程 . 结果表明：随干湿循环次数增加，炭质泥岩孔隙率增加，孔隙结构由小孔隙向大孔隙演变，瞬时应变和蠕变量增大 . 建立的损伤方程能较好地表征干湿循环次数、轴压和时间对炭质泥岩损伤演化的影响；随干湿循环次数增加，炭质泥岩损伤增大，损伤时间效应增强；轴压增大，损伤增长的速率加快，加速损伤的持续时间增长.

Study on Effect of Wetting and Drying Cycles on Creep and Damage Characteristics of Carbonaceous Mudstone

To reveal the time-dependent deformation and damage characteristics of the carbonaceous mudstone reservoir bank slope, using a low-field nuclear magnetic resonance test and triaxial compression rheological test, the pore evolution law and creep characteristics of carbonaceous mudstone under wetting and drying cycles are studied.On this basis, based on the damage theory and the Lemaitre strain equivalence principle, a creep damage equationconsidering the coupling effects of wetting and drying cycles, axial pressure, and time is established. The results show that as the number of wetting and drying cycles increases, the porosity of the carbonaceous mudstone increases, the pore structure changes from small pores to large pores, and the instantaneous strain and creep strain of the carbonaceous mudstone increase. The established damage equation can better characterize the influence of the number of wetting and drying cycles, axial pressure, and time on the damage evolution of carbonaceous mudstone. With the increase in the number of wetting and drying cycles, the damage of carbonaceous mudstone is greater, and the damage time effect is more significant. As the axial pressure increases, the rate of damage growth is fastened, and the duration of the accelerated damage is prolonged.