In an earthquake, the initiation, movement, and deposit characteristics of a rockslide are closely related to the dynamic responses of rock masses, which constitute slope materials. In this study, considering time-varying amplitudes of earthquake wave, dolomite samples collected from the source area of Donghekou rockslide, triggered by the 2008 Wenchuan earthquake, were tested under triaxial multilevel cyclic loading to investigate the dynamic fatigue properties. For three samples considered herein, cyclic loadings reduced the fatigue strength by 33.1%, 29.8%, and 39.9% in comparison with static compressive strength. Based on the hysteresis loops of the axial stress–strain curve, cumulative residual strain, dynamic elastic modulus, dynamic damping ratio, and damping coefficient were obtained, and their response to increasing number of cycles or stress amplitude revealed a significant three-phase evolution process for the fatigue behavior of dolomite subjected to multilevel cyclic loading. At each level of cyclic loading, the cracks and pores generated in the prior level of loading were closed, which resulted in the recovery of the stiffness of the rock sample in the initial period, thereby causing the dynamic damping to initially decrease and then increase. In the last phase before failure, a sharp increase was observed in the cumulative residual strain, whereas a significant decrease was observed in the dynamic elastic modulus, indicating severe unrecoverable damage in rock samples. Compared with the fatigue failure mode under static loading, cyclic loading resulted in an extremely rough shear surface, with shearing powders in the shear zone and local crushing at the two ends of the shearing surface. The generation of shear surfaces was significantly influenced by the development of pre-existing quartz veins in rock samples.

在地震中，岩石滑坡的发生，运动和沉积特征与构成边坡材料的岩体动力响应密切相关。在这项研究中，考虑到地震波的时变幅度，在三轴多级循环荷载作用下，测试了由2008年汶川地震引发的东河口滑坡震源区收集的白云岩样品，以研究其动态疲劳特性。对于本文考虑的三个样品，与静态抗压强度相比，循环载荷使疲劳强度降低了33.1％，29.8％和39.9％。根据轴向应力-应变曲线的磁滞回线，获得累积残余应变，动弹性模量，动阻尼比和阻尼系数，它们对增加的循环次数或应力振幅的响应揭示了白云岩在多级循环载荷下的疲劳行为的重要的三相演化过程。在每个循环载荷水平下，在先前载荷水平下产生的裂缝和孔隙均被封闭，这导致岩石样品在初始阶段恢复了刚度，从而导致动态阻尼先减小然后增大。在破坏前的最后一个阶段，观察到累积残余应变急剧增加，而动态弹性模量则显着下降，这表明岩石样品中存在严重的不可恢复的破坏。与静态载荷下的疲劳破坏模式相比，循环载荷导致剪切面非常粗糙，在剪切区添加剪切粉，并在剪切面的两端局部粉碎。岩石样品中预先存在的石英脉的发育对剪切面的产生有显着影响。