为了研究硬壳层对低路堤软土地基动力响应的影响，将软土地基上的道路系统模拟成路面-路基-硬壳层-软土地基4层结构。假设路面、路基、硬壳层都为单相弹性土体，而软土地基采用饱和多孔介质模拟，通过积分变换法对模型进行推导求解，分别建立了路面、路基、硬壳层和软土地基的动力刚度矩阵，并考虑路表车辆荷载条件、层间连续条件和饱和软基表面透水条件，最终集成了道路结构的整体动力刚度矩阵，获得了车辆荷载作用下低路堤软土地基的动力响应解答。在该基础上，利用快速傅里叶逆变换方法对动力响应进行数值求解，详细分析了硬壳层厚度、模量和泊松比对动应力扩散作用的影响。研究结果表明，软土地基表面的动力响应对硬壳层厚度和模量的变化十分敏感，硬壳层的存在大大地减弱了软基顶面的竖向动应力，并且增大了竖向动应力的分布范围，可见硬壳层对交通荷载引起的动力响应有明显的扩散作用。

In order to investigate the dynamic response of hard crust under the low embankment of soft subsoil, the road system on soft subsoil is simulated into pavement – subgrade – hard crust – soft subsoil layers of structure. The pavement, subgrade and hard crust are regarded as three elastic layers resting on a poroelastic porous medium simulation. Solution is derived by using the integral transform model, the dynamic stiffness matrix for the pavement; subgrade, hard crust and soft subsoil are set up respectively. The dynamic response equations for the layer which considered the effect of vehicle load are obtained by integrating the overall dynamic stiffness matrix of structure. On this basis, numerical results are derived through the inverse fast Fourier transform (FFT) method and used to analyze the influences of thickness, modulus and Poisson ratio of hard crust on stress dispersion. It is shown that the existence of the hard crust weakened the vertical dynamic stress of soft foundation greatly and increased the range of diffusion. And the responses of soft subsoil are very sensitive to the change of thickness and modulus. Therefore, it can be concluded that the dynamic response of traffic load is significantly diffused by hard crust.