桩承式路堤土拱效应分析

Soil arch analysis of pile-supported embankments

基于单桩等效处理范围内堤身土体受力平衡,改进了传统的HEWLETT极限状态空间土拱效应分析方法,求得了桩体荷载分担比计算的解析表达式。研究了桩间距、桩帽大小和填料内摩擦角对桩体荷载分担比的影响。研究表明:土拱处于弹性状态时,改进方法计算出的桩体荷载分担比小于HEWLETT极限状态计算结果;土拱处于塑性状态时,改进方法计算结果与HEWLETT计算结果相同。设计桩承式路堤时,若填料内摩擦角较大,则应优先考虑增大桩帽宽度来提高桩体荷载分担比;若内摩擦角较小,则可适当减小桩距来提高桩体荷载分担比。大内摩擦角填料有助于提高桩体荷载分担比。给出了桩体荷载分担比计算图,便于工程应用。最后对一个工程实例作了分析。

Based on gravity balance of embankment filling above equivalent area for one pile, conventional HEWLETT's three-dimensional soil-arch analysis method is improved. An analytical solution for pile efficacy is obtained. Influence of pile spacing, pile cap dimension and angle of internal friction of embankment filling on the pile efficacy is analyzed. Pile efficacy calculated by the improved method is less than that obtained by HEWLETT's method.When the soil arch is in plastic state, both methods have the same value. Increasing pile cap dimension is more economy for embankments with large friction angle. Decreasing the pile space is more effective for embankments with small friction angle. Choosing embankment filling with large friction angle is helpful to increasing pile efficacy. Pile efficacy charts are given for engineering application. Finally, these formulas are used to analyze a practical case.