成层地基中静压单桩挤土效应试验

采用室内模型试验研究了成层地基中静压桩沉桩过程，对模型桩整个沉桩过程中的挤土效应进行了分析研究。通过模型试验对在均质不同软硬地基中静力压入单桩过程产生的位移场进行了比较分析，获得了浅层土体、桩身周围、桩端处土体不同的位移变化模式，并揭示了桩周不同位置特别是软硬土层交界处土体位移随水平和深度方向的变化规律。试验结果表明，均质地基挤土位移的最大值与压桩深度存在滞后效应；对于成层地基，最大径向、竖向位移均出现在软硬土层交界面处，由于软硬土层力学性质的差异，土体位移主要表现为，软层处位移变大，硬层处位移变小。试验获得的结果便于进一步明确静压桩沉桩过程中挤土效应的内在机理，对预估沉桩的施工影响和指导沉桩设计都具有现实意义。

Experimental Analysis of Compaction Effect of Single Pile Jacked in Layered Ground

The experimental analysis of single pile jacked in layered ground is conducted to study the behavior of compaction effect during the pile pressing process. Through comparison and analysis of displacement field of different uniform soft and hard ground during pile penetration, the different displacement modes of soil located at different positions are obtained. Moreover, the tests reveal the soil displacement behavior produced by different positioning and the depth of the pile, especially at layered soil interfaces. The experimental results show that a lag effect existed between the maximum displacement and the pressed pile depth in the uniform ground. And, the maximum radial and vertical displacements appear at the soil interface, due to the difference of soft and hard soil mechanical properties, the changing laws of displacement show mainly that the soft soil become larger, the hand soil become smaller. The experimental results allow for a better understanding of the inherent mechanism of compaction of the jacked pile during the penetration process. These results are important for estimating the influence of pile installation and guiding pile design during construction projects.