(湖南大学岩土工程研究所， 长沙 410082)

［摘要］为分析PHC管桩沉桩过程中土塞效应对挤土径向位移的影响，首先从土塞的形成过程和作用机理出发，建立了土塞单元体的受力平衡方程，得出了垂直向总荷载的表达式；其次，将土塞视为“桩中桩”，基于Gibson提出的不排水条件下黏性土桩端极限承载力模型，得出“桩中桩”桩端极限承载力的表达式，从而导得PHC管桩在沉桩过程中土塞高度的表达式；再次，应用圆柱孔扩张理论对PHC管桩桩周土体进行弹塑性分析，获得塑性区半径、土体径向位移等解析表达式；最后，将理论计算结果与工程实例进行对比分析，并进一步分析了径厚比、刚度比对静压PHC管桩桩周土体径向位移的影响，验证了所提出的解析表达式的合理性。所提出的解析表达式对PHC管桩沉桩过程中挤土径向位移的计算具有一定的参考价值。

［关键词］PHC管桩； 土塞效应； 土塞高度； 圆柱孔扩张理论； 土体径向位移

中图分类号：TU473.1文献标识码：A文章编号：1002-848X(2019)16-0133-07

Study on calculation method of radial displacement caused by squeezing effect of PHC pipe pile considering plugging effect

Zhao Minghua, Xiao Rong, Yang Chaowei, Xiao Yao

(Institute of Geotechnical Engineering, Hunan University, Changsha 410082, China)

Abstract:In order to analyze the influence of plugging effect on the radial displacement due to soil squeezing effect in the process of driving PHC pipe piles, the force balance equation of plug element was established based on the formation process and mechanism of plugging, and the expression of vertical total load was obtained firstly. Secondly, the soil plug was regarded as a “pile in pile” and the ultimate bearing capacity model of clay pile tip under undrained condition proposed by Gibson was derived to obtain the formula of ultimate bearing capacity at the end of “pile in pile”. Then the formula for soil plug height of PHC pipe pile was obtained during pile driving. Thirdly, the elastic-plastic analysis of soil around PHC pipe pile was carried out by using cylindrical cavity expansion theory, and the analytical formulas of radius of plastic zone and radial displacement of soil were obtained. Finally, the theoretical calculation results were compared with engineering examples. The influence of diameter-thickness ratio and stiffness ratio on the radial displacement of soil around static pressure PHC pipe pile was  further analyzed, and the rationality of the analytical expression was verified. The analytical expression presented  has certain reference value for calculating the radial displacement of soil compaction during pile driving of PHC pipe piles.

Keywords:PHC pipe pile; plugging effect; height of soil plug; cylindrical cavity expansion theory; radial displacement of soil

*国家自然科学基金项目(51478178)。

作者简介：赵明华，博士，教授，博士生导师，Email:mhzhaohd@21cn.com。