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基于ABAQUS软件自行研制的并行计算显式算法集群平台,针对苏州城区典型地层剖面,建立了大尺度深软场地的二维精细化非线性有限元分析模型,对人工地震波和大地震远场地震动作用下深软场地的非线性地震效应进行了比较研究。研究结果表明:(1)与人工地震波作用时深软场地的地表峰值加速度放大效应相比,大地震远场地震波作用时的放大效应尤为显著,由于土介质的横向不均匀性及其非线性,使不同地表的峰值加速度放大效应存在明显的变异性。(2)深软场地对周期小于0.3 s的高频地震波均具有显著的滤波效应;大地震远场地震波作用时,深软场地对周期0.85~1.65 s的长周期地震波的放大效应非常显著,但对2.5~7.0 s的长周期地震波呈现出明显的滤波效应。(3)地震动峰值加速度PGA值沿土层深度和横向的分布形态呈现出明显的高低起伏现象,在不同成因的土层更迭面附近及土介质横向不均匀性显著的区域,地震波的局部聚焦放大和过滤减小现象尤为明显,且大地震远场地震动作用时,20 m以浅土层的PGA值呈现出非常显著的放大效应。(4)地震波的频谱特性、土层的横向不均匀性对深软场地地表加速度反应谱谱的谱形有显著影响;给出了描述加速度反应谱沿土层深度变化特征的三维谱形曲线,可以直观地展示出深软场地中细长地下结构地震反应可能存在类共振现象的土层深度。
Based on ABAQUS software parallel computing explicit algorithm clustering platform, a two-dimensional finite element nonlinear finite element analysis model of large-scale deep soft ground is established for the typical stratigraphic section of Suzhou urban area. The model is applied to far-field ground motion of artificial earthquake and large earthquakes The nonlinear seismic effects of deep soft ground are compared. The results show that: (1) Compared with the amplification effect of surface acceleration at deep soft ground when artificial seismic waves are applied, the amplification effect of far-field seismic waves in large earthquakes is particularly significant. Due to the lateral heterogeneity of soil and its nonlinearity, So that there are obvious variability of amplification effect of peak acceleration on different ground surface. (2) Deep soft ground has significant filtering effect on high-frequency seismic waves with period of less than 0.3 s. In the case of far-field seismic waves, the amplification effect of long-period seismic waves with period of 0.85-1.65 s in deep soft ground is significant, The 2.5 ~ 7.0 s long-period seismic wave shows a significant filtering effect. (3) PGA value of ground motion shows obvious ups and downs along depth and lateral distribution of soil depth. In the regions of different genetic causes and near laterals, the local focus of seismic waves The phenomenon of amplification and filtration reduction is especially obvious. When the earthquakes are affected by far-field earthquakes, the PGA value of 20 m shallow soil shows a very significant amplification effect. (4) The spectrum characteristics of seismic wave and the horizontal heterogeneity of soil layer have a significant influence on the spectral shape of the surface acceleration response spectrum in deep soft ground. The three-dimensional spectral curve describing the variation characteristics of acceleration response spectrum along the soil depth is given, The depth of the soil layer that may have the resonance phenomenon in the seismic response of the slender underground structure in the soft ground can be visually displayed.