交通荷载作用下非饱和风积沙路基动力响应研究

Dynamic responses of unsaturated aeolian sand subgrade to traffic loads

为了给风积沙路基的设计提供理论基础,建立了包含风积沙路基的多层道路动力学模型,模型中风积沙路基土使用非饱和多孔介质模拟,其它道路层采用弹性介质。首先通过双重Fourier变换求得了不同层在变换域内的解析解,并由道路的层间连续假设得到了多层道路动力学模型整体的刚度矩阵。然后结合应力边界条件求得了非饱和风积沙路基内动力响应的解。计算中考虑了风积沙路基土体模量随饱和度变化规律以及其土水特征曲线,研究了路基厚度、饱和度以及车辆载重对路基内动力响应的影响。研究发现:风积沙路基饱和度对路基动力响应的影响显著,路基土饱和度从0.45增加到0.75时,路基顶部竖向位移幅值增加49.5%;随着路基厚度增加,路基内的竖向加速度幅值逐渐降低,但路基厚度超过3 m后效果逐渐减弱。基于计算结果,得到了不同饱和度与车辆载重下的非饱和风积沙路基工作区深度预测公式,研究结果可为风积沙路基设计提供参考。

This paper investigates the dynamic responses of an unsaturated aeolian sand subgrade to traffic loads,through numerical simulations of a multilayered road over the aeolian sand subgrade.The aeolian sand subgrade is simulated by an unsaturated poroelastic medium,while other road layers are assumed to be elastic media.Analytical solutions to different layers are derived using the double Fourier transform,based on which the stiffness matrix of the whole system is obtained with the continuity assumption between different interlayers.Solutions to the unsaturated aeolian sand subgrade can then be calculated considering the stress boundary conditions.The variation of modulus with soil saturation and SWCC of aeolian sand subgrade are also considered when studying the effects of subgrade thickness,soil saturation,and vehicle loads on dynamic responses of the subgrade.It is found that the effects of soil saturation on dynamic responses of aeolian sand subgrade are significant,and the amplitude of vertical displacement in the subgrade surface increases 49.5%when subgrade soil saturation increases from 0.45 to 0.75.The amplitudes of vertical acceleration inside the subgrade decrease with the increase of subgrade thickness,and the effects gradually weaken after the subgrade thickness exceeds 3 m.Based on the calculation results,a prediction formula for the influence depth of aeolian sand subgrade under different soil saturations and vehicle loads is proposed,which can provide references for the design of aeolian sand subgrade.