关键词: 初始损伤, 砂岩蠕变, 扰动效应, 加速蠕变损伤, 瞬时弹性模量

Abstract: In order to study creep characteristics of sandstone with initial damage under disturbance action, four kinds of working conditions were designed, and uniaxial compression creep disturbance test was carried out by using self-made creep test device.Considering influence of initial damage and accelerated creep damage, a nonlinear creep model of rock was constructed by introducing plastic deformation body, accelerated damage element and Burgers model in series. Creep parameters were inversed by used Levenberg-Marquardt+general global optimization method. The results show that there is a stress threshold for disturbance effect, and after reaching threshold, there is an obvious strain mutation in the creep curve before and after disturbance. Instantaneous elastic modulus under different working conditions has a similar trend of first rising and then decreasing, but instantaneous elastic modulus of specimen with initial damage is significantly lower than that of intact group. Long-term strength of sandstone with initial damage under disturbance condition decreases significantly, which is far less than same value. Long-term strength of intact specimen under disturbance condition is only 60%-64% of corresponding uniaxial compressive strength, and experimental data are in good agreement with theoretical curve of model, which can better reflect creep disturbance characteristics of sandstone with initial damage.

Key words: initial damage, sandstone creep, disturbance effect, accelerated creep damage, instantaneous elastic modulus