Model test on vertical bearing capacity of X-section concrete pile raft foundation in silica sand

石英砂地基中X截面混凝土桩筏基础的竖向承载力模型试验

To reveal the bearing capacity of the X-section concrete piles pile raft foundation in silica sand,a series of vertical load tests are carried out.The X-section concrete piles are compared with circular section pile with the same section area.The load−settlement curves,axial force and skin friction,strain on concave and convex edge of the pile,pile-sand stress ratio,distributions of side and tip resistance are presented.The results show that bearing capacity of the X section concrete pile raft foundation is much larger than that of the circular pile raft foundation.Besides,compared with the circular pile,the peak axial force of X-section piles under raft is deeper and smaller while the neutral point of X-section concrete pile is deeper.Moreover,the strain on the concave edge is much larger than that on the convex edge of the pile,and the convex edge has more potential in bearing capacity as the vertical load increases.The X-section pile has higher pile-sand stress ratios and load-sharing between side resistance and tip resistance.Above all,the X-section concrete pile can significantly increase the bearing capacity of pile-raft foundations in silica sand.

为了揭示X截面桩筏基础在石英砂中的承载能力,将X截面桩与同截面积的圆形桩进行对比研究,开展了一系列模型试验。研究内容包括X截面桩筏基础的荷载-沉降曲线、轴力和摩阻力、X截面桩凹凸边缘的应变分析、桩-土应力比、桩侧阻力和端部承载力的分布。结果表明:X截面桩筏基础的承载力远远大于圆形桩筏基础的承载力。筏板下的X截面桩轴力峰值比圆形桩的轴力峰值小且位置更深;因而,中性点位置也比圆形桩更深。此外,X截面桩的凹缘处应变远大于凸缘处,且随着荷载的增大,凸缘处具有更大的承载力潜能。与圆截面桩相比,X截面桩具有更高的桩-土应力比,更大的侧阻力与端阻力荷载分担比。因此,X截面桩可以显著提高砂土中桩筏基础的承载力。