楔形劲性水泥土复合桩工作性状试验研究

Experimental Study of Axial Behavior of Cement-Soil Mixed Columns with Tapered Rigid Inclusions

楔形劲性水泥土复合桩是一种新型组合桩,为深入研究该桩型的工作性状,对4根不同楔角、芯长比和平均截面含芯率的楔形劲性水泥土复合桩进行了模型试验,研究了其荷载位移曲线、桩身轴力分布、桩端阻力以及侧摩阻力。试验结果表明:楔形劲性水泥土复合桩的极限承载力约为等截面劲性复合桩的1.2~1.4倍;水泥土外桩轴力在芯桩底端截面处发生突变,设计时应对该处强度进行验算;在荷载传递过程中芯桩-水泥土桩界面阻力发挥程度仅5.3%~21.4%;芯桩分担了90%以上的荷载,增大楔角会提高芯桩荷载分担占比,而平均截面含芯率和芯长比对荷载分担影响不大。

The cement-soil mixed column with tapered rigid inclusion is a new type of composite column applied in the soil improvement projects.To study the axial behaviors of this type of composite column,axial pile loading tests on four composite columns with different tapering angles,inclusion length ratios and average area core ratios were performed.The load-displacement curve,axial force distribution along the rigid inclusions,end resistance and shaft resistance of the piles were studied and evaluated.The test results show that the ultimate axial capacity of the cement-soil mixed column with a tapered rigid inclusion is about 1.2 to 1.4 times of that of the cement-soil mixed column with a uniform section rigid inclusion;The axial force within the cement-soil mixed column changes abruptly at the bottom section of the rigid inclusion,so the strength at the bottom of the rigid inclusion should be checked in the design;In the process of load transfer,only 5.3%to 21.4%of the interface resistance between rigid inclusion and the cement-soil mixed column is mobilized;The rigid inclusion shares more than 90%of the applied axial load,and increasing the taper angle will increase the load sharing ratio of the rigid inclusion,but the average area core ratio and rigid inclusion length ratio have limited effect on the load sharing.