【摘要】 以滁州市地震小区划场地为原型,针对由河漫滩、阶地、波状起伏的低丘等组成的典型复合场地,基于ABAQUS软件显式有限元并行计算平台,建立了大尺度场地二维模型,考虑土体的非线性特征,以SH波作为输入地震动,分析了河漫滩-阶地复合场地地震动力响应特征.结果表明,(1)与基岩地震动峰值加速度相比,土层近地表范围内(15m以浅)峰值加速度均表现出明显的放大现象,15m以深土层地震动放大效应随深度增加而逐渐减弱,且随深度增大,PGA放大系数值逐渐小于1.0;(2)土层峰值加速度随着深度增加非单一递减,局部土层深度地震动出现聚集效应,这一现象在河漫滩区表现比较明显;(3)场地不同区域地震动放大效应差异较大,河漫滩区地震动放大效应要明显比阶地低丘区更大;且输入地震动峰值相同时,河漫滩区反应谱特征周期要大于阶地区域,两者差距达0.05—0.15s;(4)随着输入地震动增加,反应谱谱峰向长周期方向移动明显.更多还原

【Abstract】 Take the seismic mic-rozonation site of Chuzhou City as background,a multi-geomorphic composite site consisting of alluvial flat,terraces,undulating hilly terrain was selected as prototype,considering the inhomogeneity of ground soils,based on the explicit FE method and parallel computing cluster platform of ABAQUS,a large-scale refined two-dimensional( 2D) FE nonlinear analytical model was established. The SH wave was taken as the bedrock earthquake motion and nonlinear seismic effect characteristics of the composite site were analyzed. The results show that:( 1) Compared with the input ground motion,the PGA of soils near the ground surface show an obvious amplification phenomenon,to soils deeper than 15 m,the seismic amplification effect seem weakened with the growth of depth,and gradually the amplification factor of PGA become smaller than 1. 0.( 2) The PGA display a non-monotonic decreasing characteristics with depth and a greater focusing effect of some particular soil layers,and this is more common in alluvial flat area.( 3) There are significant seismic effect difference among different locations of the site,when under the same input ground motion,the seismic amplification effect of alluvial flat area seems larger than that of terraces and low hill area,and with the increasing of input motion,the characteristic period values of acceleration response spectra of alluvial flat area are larger than that of terraces area,the difference between them comes to be 0. 05—0. 15s;( 4) With the increasing of input ground motion,the spectra peak moves to a larger period.更多还原