SV波入射下斜坡地形对上覆土层地震动放大的影响研究  

Study on the Effect of Ground Motion Amplification of Slope Topography to Overlying Soil Layer under Incident SV Waves

作　　者：刘启方 李家祥 温瑞智[2] LIU Qifang;LI Jiaxiang;WEN Ruizhi(Suzhou University of Science and Technology,Key Laboratory of Structure Engineering of Jiangsu Province,Suzhou 215009,China;Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China)

机构地区：[1]苏州科技大学,江苏省结构工程重点实验室,江苏苏州215009 [2]中国地震局工程力学研究所,黑龙江哈尔滨150080

出　　处：《防灾减灾工程学报》2022年第1期92-99,共8页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(51978434)资助。

摘　　要：针对上覆土层斜坡场,利用显式有限元方法,定量分析SV波入射下地震动的放大与斜坡角度、覆盖层的厚度以及覆盖层与下卧基岩阻抗比的关系。研究表明,当斜坡角度大于60°、覆盖土层厚度大于1/4斜坡高度时,在离坡顶点两倍斜坡高度以内,存在一个较一维土层明显的放大区域。在这一区域内,放大倍数最大值位于坡顶点,放大倍数随斜坡角度和土层厚度的增加而增大,随到坡顶点距离的增大和土层与基岩阻抗比的增大而减少。当土层与基岩阻抗比较低时,最大放大倍数可达一维土层的2.3倍。在这一区域内,斜坡地形土层基本频率约为一维土层的0.8~0.95倍。当斜坡角度<45°或覆盖层厚度小于斜坡高度的1/4时,斜坡对一维土层放大的影响显著下降。还利用最小二乘法和数值模拟结果拟合了显著放大区域的放大倍数与斜坡角度、覆盖层的厚度以及阻抗比的简单估计关系式。结果可为上覆土层的斜坡场地地震动参数的选择提供一定的参考。The relationships between the amplification of ground motion and the slope angle,the thickness of soil layer and the impedance ratio between soil and bedrock under inclined SV waves for a slope topography site are analyzed in this paper by the explicit finite element method.The study show that when the slope angle was larger than 60°,and the soil depth larger than one-quarter of the slope height,within twice the height of the slope from the slope crest,there exists an obvious amplification area compared with the one-dimensional soil layer.In this region,the amplification factor increases with the increase in slope angle and soil layer thickness,but decreases with the increase in distance to the crest of the slope and the increase in impedance ratio between soil layer and bedrock.In this region,the basic frequency of topographical slope soil is between 0.8 and 0.95 times that of one-dimensional soil.When the slope angle was smaller than 45°,or the soil depth was smaller than one-quarter of the slope height,the effect of the slope topography on soil amplification decreased significantly.At the same time,an estimated relation between amplification factor and slope angle,thickness of soil layer and impedance ratio in this area is fitted by the least square method using the numerical simulation results.The results of this paper can provide some references for the selection of ground motion parameters of the slope topography with the overlying soil layer.

关 键 词：土层 斜坡地形 基本频率 放大倍数 放大区域 

分 类 号：P315.9[天文地球—地震学]