加筋对桩承式路堤荷载传递影响的三维有限元模拟

建立了土拱效应分析的三维弹塑性有限元模型,采用数值模拟方法研究了桩承式加筋路堤的荷载传递机理。计算结果表明,路堤底部加筋增强了路堤荷载向桩帽上转移的能力。影响路堤荷载向桩帽上转移主要是土拱效应,其次是加筋的拉膜效应。土拱效应与路堤加筋与否关系不大。加筋拉膜效应在土拱效应发挥后开始发挥,桩帽边缘处底部加筋的拉应力最大。加筋拉膜效应随着加筋刚度和桩间距的增加而增大,随着加筋位置的升高而减小。与底部加筋的桩承式路堤相比,对于给定的桩帽-土差异沉降,双层加筋桩承式路堤中加筋的拉膜效应增大,第一层加筋的拉应力减小。第二层加筋铺设位置越高,其拉应力越小,最大拉应力点向桩帽中心方向移动。

3D finite element simulation of the influence of reinforcements on load transfer behaviors of a piled embankment

A 3D elastic-plastic finite element model for simulating the soil arching effect in a piled embankment with reinforcements was developed. The load transfer mechanism of the piled embankment with reinforcements was investigated numerically in detail by finite element method. The results show that the embedding of reinforcements in the piled embankment enhances the ability to transfer embankment loads to pile caps. Comparing the magnitude of transferred embankment load, much more embankment loads are transferred to pile caps by the soil arching effect than by the membrane effect. The installation of reinforcements has little influence on the soil arching effect. The membrane effect of the reinforcements appears after the full mobilization of the soil arching effect. The maximum tensile stress in the basal reinforcements occurs at the edge of the pile cap. The membrane effect increases with increasing the reinforcement stiffness and pile spacing, but reduces with increasing the installation height of reinforcements. For a given differential settlement between the pile cap and surrounding soil, the total membrane effect of a piled embankment with two layers of reinforcements is greater than that of a basal reinforced piled embankment. The tensile stress in the first layer of reinforcements is smaller than that in the basal reinforcement in the basal reinforced piled embankment. The higher the location of the second layer of reinforcements, the smaller the tensile stress, and the maximum tensile stress point will move towards to the center of the pile cap.