静压沉桩过程模拟与挤土效应分析  

Jacked piles processes simulation and soil extrusion effect analysis

作　　者：于贝 何良德[1] 黄雄 YU Bei;HE Liangde;HUANG Xiong(College of Harbor,Coastal and Offshore Engineering,Hohai University,Nanjing 210098,China;Fujian Port Aviation Survey and Design Institute Co,Ltd.,Fuzhou 350002,China)

机构地区：[1]河海大学港口海岸与近海工程学院,江苏南京210098 [2]福建省港航勘察设计院有限公司,福建福州350002

出　　处：《人民长江》2020年第6期172-178,共7页Yangtze River

基　　金：国家重点研发计划项目(2016YFC0402007);山东省交通运输科技项目(2017B79)。

摘　　要：为了研究静压沉桩的挤土效应,利用ANSYS有限元软件建立了二维轴对称模型,采用位移贯入法对沉桩全过程进行了模拟。通过获取沉桩过程中桩周土体的位移轨迹,揭示了沉桩挤土的内在机理,发现沉桩对土体的作用可归纳为“密实-挤压-拖带”3个阶段。扣除初始地应力,深入分析了土体中应力增量场的分布规律,认为扩张压力由无重力地基的扩张压力、地应力围压及其引起的扩张压力增量三部分组成。将有限元计算结果与理论解进行对比,发现不考虑竖平面偏应力影响会使得理论解的扩张压力偏大,基于柱孔扩张理论的空间轴对称解仅适用于内摩擦角较大的情况。A two-dimensional axisymmetric model was established based on the finite element simulation software ANSYS to study the compaction effect of jacked pile when it was driven into soil,and the displacement penetrating method was used to simulate the whole process of jacked piles.By obtaining the displacement trajectory of the soil around the pile during the punching processes,the internal mechanism of the compaction effect was revealed,and it was found that the effect of the punching processes on the soil can be summarized into three stages:compact-extrusion-towing.After deducting the initial geostress,the distribution law of stress increment field in the soil was analyzed in depth.It was considered that the expansion pressure was composed of three parts:expansion pressure of the gravityless foundation,the ground stress confining pressure and the expansion pressure increment caused by confining pressure.The finite element calculation results were compared with the theoretical solution,and it was found that the expansion stress of the theoretical solution was too large as not considering the influence of the vertical plane deviator stress,and the axisymmetric solution based on the expansion theory of cylindrical holes can only be applied to the case in which the internal friction angle is large.

关 键 词：沉桩过程 挤土效应 位移贯入法 位移轨迹 桩周应力 

分 类 号：TU473[建筑科学—结构工程]