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实际工程中,岩体在进入最终应力状态前会经历多级时效荷载的作用。为研究该荷载下裂隙岩体强度、裂纹扩展和变形特征等的变化规律,以通过对砂岩切割并充填水泥砂浆制备的裂隙试样为对象,开展多级时效荷载下的三轴压缩试验。试验结果表明:多级时效荷载下,3种不同裂隙组合试样的强度较常规压缩均有一定程度的降低,陡缓和陡陡裂隙岩体的强度均在起裂强度σci和扩容应力σcd之间。裂纹扩展特征方面,在相同应力路径下,随着围压的增大,裂隙岩体的破坏呈现更强的剪切性质;缓缓裂隙组合岩体的破坏形式主要受裂隙本身的分布形态所控制,受应力水平和加载路径的影响较小,在试验中均以裂隙岩桥直接贯通发生破坏;相同围压条件下,陡缓和陡陡裂隙组合岩体在时效荷载作用下的破坏较常规压缩下的破坏表现出更强的张拉性质。利用Burgers蠕变损伤模型分析各岩体间的关系,指出岩体间变形的差异主要由裂隙特征导致的初始损伤差别和岩体处于不同强度区间而导致的不同时效损伤引起,为建立岩体时效损伤模型的进一步研究提供了参考。
In practical engineering, the rock mass undergoes multilevel aging loading before entering the final stress state. In order to study the variation of strength, crack propagation and deformation characteristics of fractured rock mass under this load, the triaxial compression test under multi-stage aging load was carried out by using fractured sand samples prepared by cutting sandstone and filling cement mortar. The experimental results show that under the multi-stage aging load, the strength of the three kinds of specimens with different fractures decreases to a certain extent compared with the conventional compression. The strength of the steep and steep fractured rock mass is between the rupture strength σci and the expansion stress σcd . In the aspect of crack propagation, under the same stress path, with the increase of confining pressure, the failure of fractured rock mass shows a stronger shear property. The destruction form of slowly fractured rock mass is mainly controlled by the distribution of fracture itself , Which is less affected by the stress level and the loading path. In the experiment, the failure occurred directly through the fractured rock bridge. Under the same confining pressure, the failure of the combined rock mass with steep and steep fracture under the time-dependent loading The sabotage showed a stronger tensile nature. The Burgers creep damage model is used to analyze the relationship between rock masses. It is pointed out that the difference between rock mass deformation is mainly caused by the difference of initial damage caused by the fracture characteristics and the different age damage caused by the rock mass in different strength intervals. In order to establish the rock mass aging The further study of the injury model provides a reference.