顺层岩质边坡加速度响应规律和滑动堵江机制大型振动台试验研究

LARGE-SCALE SHAKING TABLE TEST RESEARCH ON ACCELERATION RESPONSE RULES OF BEDDING LAYERED ROCK SLOPE AND ITS BLOCKING MECHANISM OF RIVER

根据动力模型试验的相似关系,制作1个尺寸为3.0 m×0.8 m×1.6 m(长×宽×高)坡角为40°的顺层模型边坡,设计传感器的布置和试验输入方案,并完成大型振动台试验。试验发现,在坡面上水平加速度随着坡高增加有明显的放大作用,并且该放大作用呈现出非线性和在不同高程的分段性特征,在坡高的1/3以下,加速度放大效应明显,在坡高2/3到坡顶处放大系数急剧增大,中间段水平加速度放大系数增长较为缓慢;在坡体内部竖直方向上,随着高程增加,加速度放大系也表现出非线性放大效应;在坡体水平方向上,在坡面一定深度内坡面处的加速度放大系数大于坡体内部,表现出趋表效应。根据破坏后的特征及试验过程中的视频回放和分析,得出模型边坡的滑动堵江机制为地震诱发→后缘松动拉裂→前缘剪切→高速下滑→对岸阻挡隆起→堆积坡脚→形成堰塞体。研究成果对地震灾区滑坡以及堰塞湖形成机制的认识和减灾防灾有一定的价值。

According to dynamic model test similarity relation this paper constructed a bedding layered slope model with the physical dimension of 3.0 m(L)×0.8 m(W)×1.6 m(H) is carried out a large-scale shaking table test. And the testing results show that at the slope surface amplification effect is nonlinear and sectional,while below the 1/3 and over the 2/3 of slope height the amplifications are obvious. At the vertical direction in the slope, acceleration amplified with the slope height nonlinearly,and acceleration amplification coefficient reached to peak value at slope shoulder. At the horizontal direction,acceleration amplification coefficient at slope surface is larger than that in the slope,and it shows tend-surface effect. The mechanism of blocking the river is that arthquake inducing→tensile crack and loosen appeared of rear top→shear extrusion damage of foot of slope→high speed sliding→blocking of the opposite bank-accumulation at base of slope→formation of barrier dam.