循环动载作用下层状介质长期沉降计算方法

针对循环动载作用下交通基础设施长期沉降,研究解决在移动条形荷载作用下层状介质动应力和循环加卸载条件下层状介质残余应力、永久应变与残余沉降计算2个基本问题.采用Fourier积分变换与递推矩阵方法,依据平面问题动力微分方程、边界条件与层间连续条件,推导得到移动条形荷载作用下的层状介质动应力解析解.考虑应力水平和应力路径的影响,提出新的永久应变经验公式,通过卸载条件下附加永久应变的弹性边值问题求解,获得循环动载作用下层状介质残余应力与长期沉降的表达式.针对3种不同路基半刚性基层沥青路面环道试验,研究路表残余长期沉降变化规律;通过实测值和预测值对比分析验证了本文方法的合理性和可靠性.

Computational procedure for long term settlement of layered medium under cyclic dynamic loads

The formulations of some variables were presented for two essential problems of long term settlement of traffic infrastructures, which were dynamic stresses under the moving strip load, residual stresses, permanent strain and residual settlement induced by traffic loads. The analytical solutions of the dynamic stresses were given for the plane problem of layered medium under the moving strip load by using Fourier integral transform and transfer matrix method, and these solutions were derived from the dynamic differential equation, boundary conditions and continuous conditions between each two layers. A new empirical formulation of permanent strain was proposed by incorporating the influences of stress level and stress path. Then the expressions were offered for the residual stress and long term settlement of layered medium under cyclic dynamic loads, which was derived from solving an elastic boundary value problem without any dynamic load but with the permanent strain. The variations of long term settlement on the surface of layered medium were investigated for some cases of circular track tests for semi rigid base asphalt pavement. The reasonability and the reliability of the method were verified by the comparison between the test results and the predicted results under three types of subgrade soils.