基于振动台试验的不同含石率土-石混合体边坡地震动响应差异性研究

Difference of dynamic responses of soil-rock mixture slopes with different rock contents based on shaking table test

针对土-石混合体边坡动力响应特性尚不明确的问题,基于相似原理设计开展了3组不同含石率土-石混合体边坡大型振动台试验,系统地对比分析了不同含石率土-石混合体边坡动力响应的差异。研究结果表明:土-石混合体边坡在地震作用下的加速度响应符合自由面效应,即边坡在近坡顶端处的加速度放大效应要明显强于坡体内,而不同含石率土-石混合体边坡在不同频率正弦波激振作用下的动力响应差异明显,这是因为不同含石率土-石混合体边坡结构的动力特性存在差异;地震作用下,模型边坡动土压力由边坡浅表层至坡体内部呈不断增大趋势,但由于坡体变形与损伤程度不同,不同含石率边坡整体的动土压力响应程度不同;且在地震波分级加载过程中,边坡不同部位处动土压力的突变可作为边坡产生动力破坏的依据;随着含石率的上升,地震作用下边坡整体的变形程度逐渐降低:20%含石率边坡表现为由浅层至深层的连续滑动,而40%与60%含石率的边坡变形则相对较小,40%含石率边坡仅表层岩土体发生滑移,60%含石率边坡仅浅表层土体发生剥落,含石率的提升对土-石混合体边坡起到了加固作用。

To address the limited comprehension of the dynamic response characteristics of soil-rock mixture(SRM)slopes,three sets of large-scale shaking table model tests of SRM slope with different rock contents were designed and conducted based on the similarity principle.The differences in dynamic response of SRM slope with different rock contents were systematically compared and analyzed.The research results indicate that the acceleration response of SRM slopes under earthquake action conforms to the free surface effect,that is,the acceleration amplification effect of the slope is significantly stronger near the top of the slope than within the slope.However,the dynamic response of SRM slopes with different rock contents under sine wave excitation of different frequencies is significantly different,this is due to the differences in the dynamic properties of slope structures with different rock contents.Under seismic action,the dynamic earth pressure of SRM slopes with different rock contents increases continuously from the shallow surface to the interior of the slope,but due to the different degrees of deformation and damage of the slope body,the overall dynamic soil pressure response of slopes with different rock contents is different.Moreover,during the entire seismic wave grading loading process,the sudden changes in dynamic soil pressure at different parts of the slope can serve as the basis for dynamic failure of the slope.As the rock content rises,the overall deformation of the slope under seismic action decreases gradually.For instance,a slope with 20%rock content exhibits continuous sliding from shallow to deep layers,while slopes with 40%and 60%rock content have relatively small deformation.A slope with 40%rock content only experience sliding of surface rock and soil,and a slope with 60%rock content only experience peeling of shallow surface soil.This indicates that higher rock content reinforces the stability of the SRM slopes.