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采用等效线性动粘弹性模型描述土的动力非线性特性,基于一维等效线性波传法,对泉州盆地地震效应进行了分析;同时,采用修正Martin-Seed-Davidenkov动粘弹塑性模型描述土的动力非线性特性,对泉州盆地非线性地震效应进行了大尺度二维精细化有限元分析,研究了地形地貌和土层横向不均匀性对地震效应的影响。将两种分析结果进行对比,结果表明:①随着基岩输入地震动强度增大,地表峰值加速度PGA放大效应总体呈现减小趋势,中震与小震、大震与小震的地表PGA放大系数之比依次为0.83~0.99、0.72~0.97;②该盆地Ⅲ类场地处,基岩、地表起伏不大,且土层横向分布较均匀,两种方法计算得到的地震效应特征类似;基岩或地表起伏剧烈、土层横向分布明显不均匀的Ⅱ类场地上,二维非线性分析给出的地表PGA放大系数明显大于一维等效线性结果,两种方法得到的地表加速度反应谱及PGA随土层深度的变化特征存在显著差异,二维非线性分析给出的地表加速度反应谱大多呈现双峰甚至多峰现象,且PGA在土层特定深度处存在聚集效应,使PGA随土层深度的变化呈现非单调性。
The dynamic linear dynamic viscoelastic model is used to describe the dynamic nonlinear characteristics of soil. Based on the one-dimensional equivalent linear wave propagation method, the seismic effect in Quanzhou Basin is analyzed. At the same time, the modified Martin-Seed-Davidenkov dynamic viscoelastic-plastic model The dynamic nonlinear characteristics of soil are studied. The large-scale two-dimensional finite element analysis of the non-linear seismic effect in Quanzhou basin is carried out. The influence of topography and horizontal heterogeneity of soil on the seismic effect is studied. Comparing the results of the two analyzes, the results show that: (1) With the increase of ground motions, the PGA amplification effect of the peak acceleration of the ground surface shows an overall decreasing trend. The surface PGA amplitudes of the moderate and small earthquakes, large earthquakes and small earthquakes increase The ratios of the coefficients are 0.83 ~ 0.99 and 0.72 ~ 0.97, respectively. ② In the Ⅲ type of site in the basin, the bedrock has little fluctuation and the horizontal distribution of the soil layer is uniform. The seismic effect characteristics calculated by the two methods are similar. Or ground surface undulation drastic, horizontal distribution of soil is obviously uneven on the Ⅱ site, two-dimensional nonlinear analysis of surface PGA amplification coefficient was significantly greater than the one-dimensional equivalent linear results obtained by the two methods of surface acceleration response spectrum and PGA There are significant differences with the soil depth variation characteristics. The two-dimensional non-linear analysis shows that the surface acceleration response spectrum mostly shows bimodal or even multi-peak phenomenon, and the PGA has the aggregating effect at a certain depth of the soil layer, The change is non-monotonic.