静钻根植竹节桩荷载传递机理模型试验

Model test on load transfer mechanism of a static drill rooted nodular pile

针对静钻根植竹节桩这种新型组合桩基的荷载传递机理的问题,在模型槽中进行竹节桩的模型试验.通过埋设在竹节桩表面与水泥土中的应变片及桩底的土压力传感器对加载过程中桩身、桩端以及水泥土中的应力进行测量.模型试验结果表明:桩侧水泥土与桩端水泥土在荷载传递过程中所起作用不同,靠近桩端水泥土处桩侧水泥土中应力较大,在实际工程中需要提高该区域水泥土强度;模型试验测得的水泥土与桩周土极限侧摩阻力比现场试桩水泥土与桩周土的极限侧摩阻力大,在实际工程中搅拌水泥土时应提高搅拌均匀性以增加桩侧摩阻力;可以用传统桩基沉降计算公式计算静钻根植竹节桩的桩端沉降.

For investigating the load transfer mechanism of the nodular pile,a model test of the pile was conducted in the model box.The axial force of the nodular pile and the mobilized base load were measured by the strain gauges attached on the pile shaft and the soil pressure sensors underneath the pile base respectively,while the stress in the cemented soil was measured with the help of the Polyvinylchlorid（PVC）pipe on which the strain gauges were attached.The experimental results show that：the function of the cemented soil along the shaft is different from that of the cemented soil at the enlarged pile base;the stress in the cemented soil along the shaft is enlarged suddenly when approaching the pile base,thus the cemented soil at this area should be strengthened in actual projects;the ultimate skin friction of the model pile is larger than the skin friction in the field test,thus the skin friction should be improved by increasing the homogeneity of the cemented soil in actual projects;the theoretical tip displacement-tip load curves of traditional pile foundation can be applied for the nodular pile.