分级加载条件下红砂岩蠕变特性试验研究

岩石的蠕变性质是引起工程岩体破坏的主要原因之一。通过进行分级加载蠕变试验，分析了红砂岩在不同加载应力条件下的蠕变特征。试验结果表明:在不同加载应力条件下，试件等速蠕变阶段应变速率与加载应力呈指数函数关系，并且当加载应力大于损伤强度σcd时，径向等速蠕变阶段应变速率大于轴向;同时，试件在破坏过程中存在加速蠕变阶段不明显的现象。根据蠕变破坏过程中黏滞系数的变化特点，将理想黏塑性体中的黏滞系数定义为时间的负指数函数，建立了一个非定常西原蠕变模型，该模型能较好反映红砂岩在单轴压缩条件下的蠕变特性。

Experimental study on creep characteristics of red sandstone under step loading

The creep properties of rock is one of the main reasons that cause the failure of engineering rock mass. Through the step loading creep tests, the creep characteristics of red sandstone under different conditions of loading stress were analyzed. The results showed that the relationship between the strain rate and the loading stress during the steady creep stage of specimen can be described by exponential function, and the radial strain rate is larger than the axial strain rate when the loading stress is greater than the damage strength. At the same time, the accelerated creep stage may be not obvious during the failure process of specimen. According to the variation characteristics of viscosity coefficient during the creep failure process, the viscosity coefficient of the ideal viscoplastic body was defined as the negative exponential function of time, and a nonstationary Nishihara creep model was established, which can better reflect the creep characteristics of red sandstone under uniaxial compression.