落锤冲击下饱冰裂隙砂岩动态力学性能研究

Study on the Dynamic Mechanical Properties of Ice-Saturated Fractured Sandstone

为了研究饱冰裂隙砂岩的动态力学特性,通过落锤冲击试验与PFC数值模拟相结合的方法揭示了裂隙倾角对饱冰裂隙砂动态力学特性及裂纹扩展过程的影响规律。试验结果表明,不同倾角饱冰裂隙砂岩的应变时程曲线形式一致,裂隙倾角仅影响峰值应变的大小,其中裂隙水平时的峰值应变最小,且随裂隙倾角的增大峰值应变增幅超过40%。试样的宏观破坏模式均以张拉为主。数值结果表明,循环冲击会影响饱冰裂隙砂岩应力-应变曲线的形态和斜率。试样的起裂应力与起裂应变的大小以及微裂纹数量均随裂隙倾角的增加呈先增后减的变化过程,而峰值应力则随裂隙倾角的增加而线性增大。

In order to study the dynamic mechanical properties of ice-saturated fractured sandstone, the influence of fracture dip angle on the dynamic mechanical properties and crack propagation process of ice-saturated fractured sandstone was revealed by the combination of drop weight impact test and PFC numerical simulation. The results are concluded as follows. The strain time history curves of ice-saturated fractured sandstone with different dip angles are consistent. The fracture dip angle only affects the peak strain. The peak strain at fracture level is the smallest, and the peak strain increases by more than 40% with the increase of fracture dip angle. The macroscopic failure modes of the samples are mainly tensile. The numerical results show that the cyclic impact will affect the shape and slope of the stress-strain curve of the ice-saturated fractured sandstone. The crack initiation stress, crack initiation strain and the number of microcracks increase first and then decrease with the increase of fracture dip angle, while the peak stress increases linearly with the increase of fracture dip angle.