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地震中已经观测到斜坡的地震响应会受地形的影响。因此,在划分堆积层斜坡坡面类型的基础上,开展不同坡形振动台模型试验。试验结果表明:输入强度较强的地震波时,斜坡表面加速度响应峰值放大系数大于斜坡内部,且斜坡中上部及表面曲率变化较大处(AC2)加速度放大效应更为显著。坡形的变化影响着斜坡自振频率,表现为上凸下凹型斜坡的自振频率接近于5 Hz,其他坡形斜坡接近于10 Hz。模型破坏的临界加速度阈值为500~700 Gal与斜坡稳定性计算结果基本一致。坡形影响斜坡的滑动面位置及厚度,曲率半径越大(凸型为正、凹型为负)的坡形滑动面厚度越大。滑动距离(与坡脚的距离)量测显示:直线型和上凹下凸型斜坡滑动距离最远危害范围大,凸型和上凸下凹型斜坡运动距离较远危害范围较大,凹型坡运动距离较近危害范围较小。因此,直线型和上凹下凸型斜坡的危险性(危害性)最高,凸型和上凸下凹型斜坡危险性较高,凹坡危险性最低。本研究的意义在于加强地震力作用下地形效应对斜坡稳定性研究的认识,为防灾减灾和灾害风险评价提供科学依据。
The seismic response of slopes that have been observed in an earthquake may be affected by the terrain. Therefore, on the basis of dividing the slope types of the accumulation layer, different shale shaker model tests are carried out. The experimental results show that when the input intensity is strong, the peak amplification factor of the acceleration of the slope surface is larger than that of the slope, and the acceleration amplification effect of the AC2 acceleration in the upper part of the slope and the surface is more significant. The change of the slope shape affects the natural frequency of the slope. The natural frequency of the convex slope is close to 5 Hz and the slope of other slopes is close to 10 Hz. The critical acceleration threshold for failure of the model is 500-700 Ga, which is consistent with the calculation results of slope stability. The slope shape affects the position and thickness of the sliding surface of the slope, and the greater the thickness of the slope surface is, the larger the radius of curvature is (the convex shape is positive and the concave shape is negative). Slippage distance (distance from the foot of the slope) measurements show that the straight line type and the upper concave convex slope have the greatest sliding range, and the convex type and the convex convex concave type are far away from each other. The damage range is larger. The concave slope motion A closer range of hazards smaller. As a result, the straight-line and upper-concave-convex slopes have the highest risk (hazard), the convex-type and upper-convex-concave slopes are more dangerous and the slopes are the least dangerous. The significance of this study lies in strengthening understanding of slope stability study under the action of seismic forces and providing scientific evidences for disaster prevention and reduction and disaster risk assessment.