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在库水的长期浸泡-风干循环作用下,库岸边坡岩体的动力特性变化规律直接影响其长期稳定性能,其中,消落带是库岸边坡稳定的敏感地带。因此,特选取三峡库区库岸边坡消落带典型砂岩为研究对象,设计了考虑水压力反复升降变化和浸泡-风干循环耦合作用的试验方案,对不同浸泡-风干循环作用周期的岩样进行单轴循环加、卸载动力响应试验。研究结果表明:随着浸泡-风干循环作用次数的增加,相同次数加、卸载循环作用时对应岩样的轴向应变、动应力-应变曲线的滞回圈面积逐渐增大,计算得到砂岩的阻尼系数、阻尼比逐渐变大,动弹性模量逐渐减小,说明浸泡-风干循环作用对砂岩动力特性的损伤是一种累积性发展的过程。最后,基于岩样的微观结构变化,对浸泡-风干水岩循环作用下砂岩动力特性劣化机制进行探讨。研究成果对库区大量存在的库岸边坡在考虑地震作用下的长期稳定性评价具有较高的参考价值。
Under the action of long-term soaking-air-drying cycle of reservoir water, the dynamic change of rock mass in bank slope directly affects its long-term stability, of which, the hydro-fluctuation belt is a sensitive stable zone of bank slope. Therefore, we selected the typical sandstone in the declining zone of the bank slope of the Three Gorges Reservoir Area as the research object, and designed a test program considering the coupled effect of repeated lifting and lowering of water pressure and soaking-air-dry cycle. Uniaxial cycle plus, unloading dynamic response test. The results show that with the increase of the number of soaking-air-drying cycles, the axial strain of the corresponding rock specimen increases with the same number of times and the unloading cycle increases. The hysteresis area of the dynamic stress-strain curve gradually increases. The damping of the sandstone Coefficient and damping ratio gradually increase, and dynamic elastic modulus decreases gradually, which indicates that the damage of sand-rock dynamic characteristics by soaking-air-dry cycle is a cumulative process of development. Finally, based on the change of microstructure of rock samples, the mechanism of dynamic deterioration of sandstone under soaking-air-drying water rock circulation was discussed. The research results have a high reference value for the long-term stability evaluation of the bank slope existing in the reservoir area considering the earthquake.