强震作用下陡倾顺层岩质边坡动力响应与破坏模式研究

STUDY ON DYNAMIC RESPONSE AND FAILURE MODE OF STEEP BEDDING ROCK SLOPE UNDER STRONG EARTHQUAKE

以陡倾顺层岩质边坡为研究对象,采用振动台模型试验与FLAC3D数值模拟方法,对强震作用下陡倾顺层岩质边坡的动力响应规律和变形破坏模式进行了研究。研究结果表明:陡倾顺层岩质边坡在坡表及坡内竖直方向的加速度响应均表现出高程放大效应,而水平方向上的加速度响应则表现为趋表效应;输入波类型对边坡模型加速度响应有显著影响,正弦波作用下的加速度响应明显强于天然地震波;加速度放大系数随地震波振幅的增大,呈现先增大后减小的变化规律;地震波加载持续时间对陡倾顺层岩质边坡加速度响应的影响较小。对模型试验和数值模拟中边坡变形破坏特征的分析,得到陡倾顺层岩质边坡在强震作用下的破坏模式为:地震诱发-坡表岩层出露处岩块松弛张裂-坡肩岩层处拉裂张开-坡面中部出现剪切裂缝-裂缝逐渐贯通-发生多级高位滑坡。

This paper takes the steep bedding rock slope as the research object,uses shaking table model test and FLAC3Dnumerical simulation method and studies the dynamic response law and deformation failure mode of steep bedding rock slope under strong earthquake.Results show that the acceleration response of steep bedding rock slope on the surface and in the vertical direction shows elevation amplification effect,while the acceleration response in horizontal direction turns into surface effect.The type of input wave has significant influence on the acceleration response of slope model,and the acceleration response under sine wave is obviously stronger than that of natural seismic wave.The acceleration response of steep bedding rock slope under the action of sine wave is obviously stronger than that of natural seismic wave.The acceleration amplification coefficients increases first and then decreases with seismic wave amplitudes increasing.The influence of seismic wave duration on the acceleration response of steep bedding rock slope is small.Based on the analysis of the deformation and failure characteristics of the slope in the model test and numerical simulation,the failure mode of the steep bedding rock slope under strong earthquake action is described as(1)earthquake induction,(2)rock mass relaxation and tension fracture at the exposed part of the slope,then(3)tensile crack of the shoulder rock layer,then(4)appearance of shear cracks in the middle part of the slope-gradual coalescence of cracks,subsequently(5)the occurrence of high locality landslide.