不同边界条件对路基结构动力学响应的影响

Effects of Different Boundary Conditions on the Dynamical Response of Subgrade Structure

分别采用静力人工边界、无限元边界、粘弹性动力人工边界和远置静力人工边界对承受交通载荷的典型路基结构进行有限元分析。以远置静力人工边界计算获得的路面竖向位移和面层底部拉应力时程曲线为参考解,揭示边界条件对路基结构动力学响应的影响。分析结果表明:边界条件对拉应力的影响很小,它们与参考解的最大误差为0.82%;静力人工边界下的位移时程曲线一直在参考解附近震荡,无限元边界下的位移解高于参考解,粘弹性动力人工边界下的路面位移与参考解最为接近。综合考虑位移和应力的精确度与CPU的计算时间,粘弹性动力人工边界为最佳的路基结构动力学分析边界条件。

4 kinds of boundary conditions(BCs), including the static artificial BC, the infinite element BC, the visco-elastic dynamical artificial BC and the remote static artificial BC, were used to perform finite element analysis of typical subgrade structure under traffic loading. Time-history curves of the pavement vertical displacement and the tensile stress at the bottom of the surface course obtained from the remote static artificial BC were selected as reference solution to indicate the effects of different BCs on the dynamical responses of subgrade structure. Results show that change of BC has little effect on the tensile stress and the maximum error is only 0.82%. Time-history curve of the displacement obtained from the static artificial BC oscillates near the reference solution; solution from the infinite element BC is higher than the reference one; however, displacement obtained from the visco-elastic dynamical artificial BC is most close to the reference solution. The predicting accuracies of displacement and stress, with the CPU time, are considered comprehensively. It is found that the visco-elastic dynamical artificial BC is most suitable for the dynamical analysis of subgrade structure.