交通动载下路基长期运营沉降等效有限元分析
Equivalent finite element method for long-term settlement of subgrade induced by traffic load
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摘要: 饱和软土地基上交通动载会引起显著的沉降,在考虑循环荷载作用的经验显式本构模型的基础上发展了等效有限元方法,实现了对交通移动荷载下路基长期沉降的计算。采用拟静力方法计算动应力比,基于试验量测的累积轴向应变及累计孔压建立显式的应力-应变模型,得到交通循环动载下地基单元的塑性应变,结合初应变有限元的原理,对通用有限元软件进行二次开发实现路基运营沉降计算。作为算例分析了一个典型的路基断面在交通荷载作用下塑性应变和长期沉降的发展分布规律。分析表明,最大塑性应变发生在路面侧边界位置,而最大沉降分布于路面中心一定宽度范围内。Abstract: Traffic load may produce a significant settlement of subgrade on saturated soft soils. This work aims to develop an equivalent finite element method to calculate the long-term settlement of subgrade. The pseudo-static method is used to calculate the dynamic stress ratio. An explicit stress-strain model is developed from the experimental data of axial plastic strain and accumulated pore pressure and then integrated into the initial-strain-based equivalent FEM. The equivalent FEM is established using the user-defined subroutine offered by the commercial FEM software. As an illustration, the equivalent FEM is used to compute the settlement of a typical cross-section of a road. It is found that the maximum strains are distributed near the side of road surface, and the maximum settlement is located in the central area of road surface.