以苏通大桥沉井基础方案为例,通过数值分析,分析土层侧向人工边界设置位置对沉井基础地震反应计算的影响。探讨了土层和结构地震反应随土层计算范围不同而变化的规律。为在计算大型沉井基础的地震反应有限元分析中,合理确定有限土域范围提供依据。当土层单侧外延为土层厚度的4倍时,土层中人工侧向边界对沉井地震反应(如单元的弯矩、剪力和轴力等)的影响可以控制在1%的相对误差之内。
Taking the open caisson foundation in Sutong Bridge as the engineering background, the influence of the location of the vertical artificial boundary set in soil layer on the seismic response analysis of the foundation has been analyzed by numerical analysis. The variation tendency of the seismic responses of the soil layer and the foundation with different soil region considered in calculation is studied. The result can be used as reference for the analysis of the large-scale open caisson foundation by the finite element method. When the model is in L/H=4 with the vertical artificial boundary, the effect of vertical artificial boundary in soil layer on the seismic responses of the open caisson, such as the moment, shear and axial force of the elements, can be controlled below 1% of relative errors.