高速制动荷载下饱和地基-路基结构的动力响应

DYNAMIC RESPONSE OF SATURATED GROUND- SUBGRADE UNDER HIGH-SPEED BRAKING LOADS

  • 摘要: 为研究变速移动荷载下层状道路结构的动应力响应,通过Dirac函数给出了变速移动荷载的表达式;基于Biot固结理论,结合Fourier变换、势函数分解及透射矩阵法给出了移动荷载下层状饱和地基的Green函数;通过对Green函数和变速移动荷载在时空域的卷积,得到了变速移动荷载下层状饱和地基的动力响应。研究结果表明:变速移动荷载对层状道路结构的动应力响应有显著影响;轮-路摩擦(制动力)主要影响上层路面结构的动力响应,而变速效应(加速度)对下层饱和地基的动力响应有显著影响,特别是对于高速制动荷载下的动剪应力;随荷载移动初速度和制动力/加速度的增大,变速制动荷载对饱和地基动力响应的影响也随之增大;上层路面结构刚度越小、饱和地基深度越大、渗透性越差时,变速制动荷载所诱发的动应力放大效应越明显。

     

    Abstract: The dynamic stress responses of the layered pavement structures subjected to a variable-speed moving load are analyzed. The Dirac function is used to obtain the expression for a variable-speed moving load. Based on Biot's consolidation theory, Green's function of a layered saturated ground under moving loads is developed by combining the Fourier transform, potential function decomposition as well as the transmission matrix method. The dynamic response of the layered saturated ground subjected to a variable-speed moving load can be obtained by convolving Green's function and variable-speed moving load one in the spatiotemporal domain. The results show that the variable-speed moving load has a significant effect on the dynamic stress response of the layered pavement structures. The wheel-pavement friction (braking force) mainly affects the dynamic response of the upper-layer pavement structure. In contrast, the variable-speed effect (acceleration) has a significant effect on the dynamic response of the lower-layer saturated ground, especially for the dynamic shear stress at the high-speed braking load. The effect of variable-speed braking loads on the dynamic response of saturated ground increases with growing initial speed and braking force/acceleration. The lower the stiffness of the upper-layer pavement structure, the deeper the saturated ground, and the poorer the permeability, the more pronounced the dynamic stress amplification effect induced by variable-speed braking loads.

     

/

返回文章
返回