多地貌单元复合场地非线性地震效应特征二维分析  

2D analysis of nonlinear seismic effect characteristics of multi-geomorphic composite site

作　　者：金丹丹[1,2] 陈国兴[1,2] 董菲蕃[1,2] 

机构地区：[1]南京工业大学岩土工程研究所,南京210009 [2]江苏省土木工程防震技术研究中心,南京210009

出　　处：《岩土力学》2014年第6期1818-1824,共7页Rock and Soil Mechanics

基　　金：国家科技支撑计划"地震预警与烈度速报系统的研究与示范应用"项目(No.2009BAK55B00)

摘　　要：针对由河漫滩、阶地、波状起伏的丘陵地带和残丘等组成的典型复合地形场地，基于ABAQUS软件的显式有限元并行计算集群平台，考虑土体的非线性特征，采用黏弹性人工边界模拟切除的无限域对地震波动的影响，建立了大尺度复合地形真实场地的二维有限元模型，并将基岩地震动视为SH波，分析了不同地貌单元复合场地地震效应特征。结果表明：地形差异引起地表各测点峰值加速度（PGA）及峰值位移（PGD）不同；在相同地震波入射下，河漫滩区地表PGA大于I级阶地区域，但其PGD明显小于I级阶地区域，且河漫滩区的峰值位移差动较小；场地地表水平加速度反应谱呈双峰及多峰现象，加速度在0．4～1．2 Hz频段放大较多，且加速度反应谱特性与输入地震动相关；特定频段（0．5～1．75 Hz）地震动放大效应与聚集效应比较明显，频率小于0．2 Hz及大于2 Hz时，场地地震动放大特征不显著。低丘区的敏感频率段宽于河漫滩区；观测点的位置影响相应的水平加速度持时大小，局部地形变化将引起地震动持时差异，且持时和输入地震动特性相关。Based on the explicit finite element method and 32 CPU parallel computing cluster platform of ABAQUS, considering theheterogeneity of ground soils, a large-scale refined two-dimensional finite element nonlinear analytical model for a multi-geomorphiccomposite site that consists of alluvial fiat, terraces, undulating hilly terrain and monadnock is established in the time domain. The SHwave is taken as the bedrock earthquake motion and nonlinear seismic effect characteristics of the composite site are analyzed. Theresults show that： （1） the peak ground acceleration（PGA） and peak ground displacement（PGD） of different observation points on theground surface vary with each other, which is caused by the terrain differences. When it＇s under the same input ground motion, theground surface PGA of alluvial fiat area shows obviously larger than that of the first terrace area, however, the PGD of alluvial flat issmaller than that of the first terrace, and the PGD difference is relatively smaller in the alluvial flat area. （2） The horizontalacceleration response spectrum of ground surface appears a double-peak or multi-peak phenomenon, the amplification of groundmotion seems outstanding in the frequency band from 0.4 Hz to 1.2 Hz. Moreover, the acceleration response spectrum is related withthe input ground motion. （3） The amplification effect and focusing effect of seismic motion are more obvious in specific frequencyband（0.5 Hz to 1.75 Hz）, when the frequency is lower than 0.2 Hz or higher than 2 Hz, the seismic amplification characteristics arenot apparent. （4） The location of observation point has influence on the acceleration duration, the changing terrain may causedifference of seismic motion duration, besides, the motion duration, in some way, is dependent on the input ground motioncharacteristics.

关 键 词：复合地形场地 不同地貌单元 土体非线性 地震效应特征 

分 类 号：TU475.1[建筑科学—结构工程]