刘建宇 王春艳 刘冒佚 丁选明 刘欢

摘 要：通过室内模型试验研究钙质砂地基中桩基的水平承载特性，分析桩长对桩顶位移、桩顶转角、桩身弯矩以及桩侧土体压力分布的影响，并与福建标准砂地基中的模型桩进行了比较。试验结果表明：桩长对水平承载特性具有显著影响;增加桩长能明显提高单桩水平极限承载力，桩身变形逐渐由刚性转动转变为弯曲变形;弯矩沿桩身的分布范围由全段分布转变为集中在桩身上半部分;桩侧土压力主要分布在迎土侧的上部土层中，土体压力随着水平荷载的增加而发生明显变化;在低应力水平下，钙质砂中单桩水平承载力要大于标准砂中桩基承载力，钙质砂在较高应力水平下的模型试验有待进一步探究。

关键词：钙质砂;桩基础;单桩;模型试验;承载特性

中图分类号：TU473.1 文献标志码：A 文章编号：2096-6717（2021）06-0074-08

Abstract： Through a series of model tests in laboratory， the horizontal bearing characteristics of the pile in the calcareous sand foundation were investigated. The influence of the pile length on the pile top displacement， the rotation of the pile head， bending moment of the pile body and the distribution of the pile side soil pressure were analyzed. In addition， it is compared with model piles in silica sand （Fujian standard sand）. The test results show that the horizontal displacement-load curve of the model pile in the calcareous sand is abrupt， and the pile length has a significant influence on the horizontal bearing characteristics. Increasing the pile length can significantly increase the ultimate horizontal bearing capacity of model pile， and the pile deformation gradually changes from rigid rotation to bending deformation. The distribution range of the bending moment along the pile body is changed from the whole pile length to half. The soil pressure on the side of the pile is mainly distributed in the upper soil layer on the soil-facing side， and the soil pressure changes significantly with the increase of the horizontal load. Under low stress levels， the horizontal bearing capacity of a single pile in calcareous sand is greater than that in silica sand. The model test of calcareous sand under higher stress levels needs to be further explored.

Keywords： calcareous sand; pile foundation; single pile; model test; bearing characteristics

钙质砂广泛分布在中国南海海域，因具有极高的碳酸钙含量而得名。与石英砂相比，钙质砂具有内部孔隙多、颗粒易破碎、重度较低、棱角和内摩擦角较大等特点[1-4]。由于其独特的物理特性，钙质砂与石英砂在工程力学性质上有较大的差异，导致在钙质砂地基上进行工程建设时，现有的设计理论和设计方法不再适用[5]，需要对其进行专门研究。

学者们对钙质砂中桩基承载特性展开了大量的研究。秦月等[5]采用室内模型试验，模拟了单桩在不同受力方向下的承载特性，分析了钙质砂地基中桩-土相互作用机制。……