土层对地震的随机反应分析  

ANALYSIS OF RANDOM RESPONSE OF SOIL LAYER TO EARTHQUAKE

作　　者：曾心传[1] 秦小军[1] 

机构地区：[1]中国地震局地震研究所

出　　处：《地震工程与工程振动》1998年第3期27-39,共13页Earthquake Engineering and Engineering Dynamics

基　　金：地震科学联合基金

摘　　要：利用随机振动理论，本文研究了非均匀土层对地震的动力反应问题。假定土层的剪切模量随深度呈指数函数形式分布。关于基岩输入地震动加速度的功率谱密度函数，考虑了两种形式：白噪声谱和有色谱。为了比较起见，文中考虑了均匀土层的情形。数值计算表明：（１）在基岩输入地震动加速度的功率谱密度为白谱的情况下，土层的最大期望反应（相对位移、绝对加速度、剪应变）大于基岩输入地震动的功率谱为有色谱的情形；（２）在土层的上部，对于相对位移和绝对加速度，非均质土层的最大期望反应值大于均质土层的最大期望反应值，在土层下部，情形正好相反；对于剪应变，在整个土层深度内，非均质土层的最大期望值大于均质土层的最大期望值；（３）无论对于均质或非均质土层，基岩输入地震动和土层反应均为平稳过程时，土层的最大期望反应最大；而基岩输入地震动和土层反应均为非平稳过程时，土层的最大期望反应最小。Using the theory of random vibration,the problem of dynamic response of the non homogeneous soil layer to earthquake is studied in the present paper.The shear modulus of the soil layer is assumed to be exponential function varying with the depth.Two cases of power spectral intensity function for the earthquake acceleration input at the base rock is considered:the white noise spectrum and the coloured spectrum.For comparison,the case of homogeneous soil layer is considered also.The numerical calculation results show that:(1)under the case that the power spectral density of the earthquake acceleration input at the base rock is the white noise spectrum,the maximum expected response(including the displacement,the acceleration,and the shear strain)of the soil layer is greater than that for the case of coloured spectrum.(2)In the upper part of the soil layer,the maximum expected values of the displacement and the acceleration for the case of non homogeneous medium are greater than that for the case of homogeneous soil layer,but in the lower part of the soil layer,the case is opposite.The maximum value of the shear for the non homo geneous soil layer is always greater than that for the homogeneous soil layer in the whole depth.(3)When both the earthquake acceleration input at the base rock and the response of the soil layer are stationary random process,the maximum expected responses are greater than that for the case of the response of the soil layer being non stationary random process,and among them,when both the earthquake acceleration input at the base rock and the response of the soil layer are non stationary random process,the maximum expected responses are the smallest.

关 键 词：非均匀土层 随机振动 地震反应 土层 

分 类 号：TU435[建筑科学—岩土工程] P315.9[建筑科学—土工工程]