DataSheet1_Critical Damage and Microstructure Characteristics of Sandstone in the Three Gorges Reservoir Area by Single Specimen Method Under Different Stress Paths.PDF

The critical damage value of rock is an important parameter of stability analysis when engineering rock mass. Based on the previous single test method, this paper, combined with the deformation characteristics of rock residual phase under different stress paths, proposed a single specimen repeated loading method to measure the critical damage value of rock based on different damage variables. The paper also proposed to modify the critical damage value based on residual constitutive energy and to improve the definition of damage variables based on constitutive energy dissipation. According to the microstructure characteristics of the rock sample, the mechanism of the single specimen method to determine the critical value of rock sample damage is revealed. The results show that: 1) Comparing the results of triaxial failure test of rock under different stress paths and single specimen repeated loading test, the residual strength of rock sample is mainly controlled by the confining pressure of loading, which is not an obvious relationship with initial confining pressure and stress path; 2) The number of repeated compressions has little effect on the internal structure, particle flatness, and particle surface smoothness of their specimens, which is reflected at the macroscopic level that the residual strength of sandstone tends to achieve a stable value; and 3) The corrected critical damage value based on residual strain energy is closer to the theoretical value. Test methods in this paper can provide useful references for determination of critical damage value.

岩石临界损伤值是工程岩体稳定性分析的重要参数。基于以往的单试样试验方法，本文结合不同应力路径下岩石残余阶段的变形特性，提出了一种基于不同损伤变量的单试样重复加载法以测定岩石临界损伤值。本文还提出基于残余本构能量修正临界损伤值的方法，并改进了基于本构能量耗散的损伤变量定义。根据岩石试样的微观结构特征，本文揭示了单试样法测定岩石试样损伤临界值的作用机制。研究结果表明：1）对比不同应力路径下岩石三轴破坏试验与单试样重复加载试验的结果，岩石试样的残余强度主要受加载围压控制，与初始围压及应力路径无明显关联；2）重复压缩次数对试样内部结构、颗粒平整度及颗粒表面光洁度的影响极小，宏观上体现为砂岩残余强度趋于稳定值；3）基于残余应变能修正后的临界损伤值更接近理论值。本文提出的试验方法可为岩石临界损伤值的测定提供有益参考。