浸泡-风干循环作用下砂岩动力特性劣化规律研究  

Dynamic characteristics deterioration laws of sandstone under cyclic saturation-air drying

作　　者：邓华锋[1,2] 罗骞[1,2] 李建林[1,2] 何明[1,2] 原先凡[1,2] 朱敏[1,2] 

机构地区：[1]三峡大学三峡地区地质灾害与生态环境湖北省协同创新中心,湖北宜昌443002 [2]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《岩土力学》2013年第9期2468-2474,共7页Rock and Soil Mechanics

基　　金：国家重点基础研究发展计划(973)前期研究专项课题(No.2012CB426502);湖北省自然科学基金资助项目(No.2012FFB03805);宜昌市科学技术研究与开发项目(No.A2011–302–6);三峡大学科学基金(No.KJ2011B008)

摘　　要：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 condition of long-term cyclic saturation-air drying, long-term stability of reservoir bank slopes are affected by their dynamic characteristics change rules, and the hydro-fluctuation belt is the sensitive area. Thereafter, taking typical sandstone in the hydro-fluctuation belt of reservoir bank in Three Gorges reservoir area, a test scheme is designed with the consideration of coupling interaction of water pressure changes and saturation-air dry cyclic function, and uniaxial cyclic loading and unloading dynamic response tests of sandstone with different saturation-air dry cycle periods are carried out. The experimental results show that the hysteresis loop area of dynamic stress-strain curve and axial strain of the sandstone samples increase gradually when they experience the same times cyclic loading and unloading, and the dynamic elastic modulus of sandstone samples decrease gradually and damping coefficient, damping ratio increases gradually during the saturation-air dry cyclic process, which indicates that the saturation-air dry cyclic function has a cumulative damage of dynamic characteristics on the samples. Finally, degradation mechanisms of dynamic characteristics under the saturation-air dry cyclic function are discussed in detail based on the microscopic structure change of sandstones. Research results have an important reference for the long-term stability analysis of reservoir bank slopes considering the earthquake action.

关 键 词：浸泡-风干循环作用 循环加卸载 阻尼比 阻尼系数 动弹性模量 

分 类 号：TU452[建筑科学—岩土工程]