循环荷载下双裂隙砂岩弹性模量及裂纹动态演化

Elastic Modulus and Dynamic Evolution of Fracture in Double-Fractured Sandstone Under Cyclic Loading

为研究不同岩桥倾角砂岩在循环荷载作用下的弹性模量变化和裂纹动态演化规律,对裂隙倾角固定为45°,岩桥倾角分别为15°,45°,75°,90°,105°的砂岩试件开展了单轴循环加、卸载试验和PFC^(2D)模拟.结果表明,不同裂隙砂岩的弹性模量随循环荷载作用得到了明显的强化;在循环荷载作用下,应力-应变曲线与离散元模拟得到的试件瞬时微裂纹演化曲线存在对应关系;岩桥倾角对砂岩的破坏模式有影响,PFC^(2D)模拟的裂纹动态演化可以合理地反映岩石中裂纹的萌生位置、扩展方向.基于微裂纹数目所定义的损伤与破坏模式很好地对应,岩桥倾角为45°时原始损伤是最大的.

In order to study the changes in elastic modulus and the dynamic evolution of cracks in sandstones with different inclination angles of rock bridges under cyclic loading,uniaxial cyclic loading and unloading tests,along with PFC^(2D)simulations were carried out on sandstone specimens with rock bridge inclination angles of 15°,45°,75°,90°and 105°when the fissure inclination angle was fixed at 45°.The results show that a significant strengthening of the elastic modulus of sandstone with different fissures due to cyclic loading.There is a correlation between the stress‐strain curve and the instantaneous microcrack evolution curve of specimens obtained from discrete element simulation under cyclic loading.The rock bridge inclination angle has an influence on the damage mode of sandstone,and the dynamic crack evolution in the PFC^(2D)simulation can reasonably reflect the initiation location and growth direction of cracks in the rock.The damage defined based on the number of microcracks,corresponds well to the damage pattern,with the maximum original damage at a rock bridge inclination angle of 45°.