坡地地形对地震动特性的影响分析

采用有限元有限差分方法，结合人工透射边界理论，研究局部坡地地形对地震动特性的影响，分析坡高、坡角对地形放大效应的影响。研究结果表明:坡地地形斜坡段各点反应谱谱比最大值沿坡高逐渐增大，坡脚点对地震动反应谱谱比呈缩小效应；坡底段各点反应谱谱比接近1；坡起平台段空间点受地形效应的影响较大；坡高和坡角对地形效应的影响较明显，当坡角不变时，不同坡高反应谱谱比曲线形状基本相同，峰值点对应的特征周期随着坡高的增加呈增长趋势，峰值点对应的反应谱谱比随着坡高的增加呈增大趋势，斜坡顶点阿里亚斯烈度比值在地形坡高超过一定数值后随着坡高的增加呈增大趋势；当坡高不变时，大部分频段内反应谱谱比最大值随着坡角的增加逐渐增大，斜坡顶点阿里亚斯烈度比值在坡角达到一定数值后随着坡角的增加呈增大趋势。

Analysis of Slope Terrain Effect on the Properties of Ground Motion

Based on the finite element finite difference method and the theory of artificial transmission boundary, the influence of local slope terrain on ground motion characteristics (including response spectrum, peak acceleration, peak velocity, peak displacement and arias intensity) is studied, and the influence of slope height and slope angle on ground shape amplification effect is analyzed. The results show that: the maximum response spectrum ratio of each point on the slope section of slope terrain gradually increases along the slope height, and the maximum value is not more than 1.3; the slope toe point has a narrowing effect on the response spectrum ratio of ground motion; the spectrum ratio of each point on the bottom section of slope is close to 1; the spatial point on the platform section is greatly affected by the terrain effect, and gradually decreases with the distance from the top of slope. The height and slope angle of slope terrain have obvious influence on terrain effect. When the slope angle is constant, the shape of the spectral ratio curve of different slope heights is basically the same, the characteristic period corresponding to the peak point increases with the increase of height, and the spectral ratio corresponding to the peak point also increases with the increase of height. When the terrain height exceeds a certain value, the ratio of arias intensity at the top of slope increases with the increase of height; when the slope height is constant, the maximum value of response spectrum ratio in most frequency bands also increases with the increase of slope angle. And the ratio of arias intensity at the top of the slope increases with the increase of the slope after reaching a certain slope angle.