频发微震下含水率对堆积体斜坡动力响应规律及失稳模式的影响
Effect of moisture content on dynamic response law and failure mode of accumulation slopes under frequent micro-seismic actions
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摘要: 近年来,三峡库区微小地震频繁,同时库区堆积体斜坡广泛分布,频发微震作用下堆积体斜坡的稳定性值得关注。堆积体的含水率是影响斜坡稳定性的重要因素之一。通过振动台物理模型试验,揭示频发微震作用下三峡库区巨厚堆积体斜坡土体含水率对斜坡动力响应及失稳模式的影响。结果表明:模型斜坡在频发微震作用下发生“阶梯状”滑出破坏,变形演化过程:裂缝产生并发育→裂缝扩展→上部裂缝贯通(上部滑体发生滑动)→底部滑动面贯通(斜坡失稳破坏);裂缝贯通导致斜坡堆积体滑出的过程中,高含水率模型发生“局部整体式”破坏,低含水率模型发生“溃散式”破坏;坡体加速度响应表现出明显的趋高趋表效应,导致斜坡坡肩位置率先出现裂缝,含水率增大对这些效应具有促进作用。Abstract: Micro-seismic actions are frequent in the Three Gorges Reservoir area in recent years. Meanwhile, the accumulation slope is widely distributed in the reservoir area. Therefore, the stability of the accumulation slope under the frequent micro-seismic actions is noteworthy. The moisture content of accumulation body is one of the key factors affecting slope stability. The influences of the moisture content on the dynamic response and failure mode of the massive accumulation slope in Three Gorges Reservoir area are revealed by adopting the shaking table model tests. The results are as follows: under the frequent micro-seismic actions, the failure of the model slope is damaged by "ladder" sliding. The deformation evolution can be summarized as follows: generation of cracks → extension of cracks → connection of the upper cracks (sliding of the upper sliding body) → formation of the bottom slip plane (failure of the slope). During the process of accumulation sliding due to the connection of cracks, the failure of the high moisture content model is "locally integrated", while the failure of the low moisture content model is "collapsed and scattered". The acceleration response of the slope shows obvious altitude effect and skin effect, leading to the first crack in the shoulder of slope. The enhancement of moisture content promotes these effects.