软土地区桩基施工群孔效应对周边环境的影响机理及控制策略研究

项目名称： 软土地区桩基施工群孔效应对周边环境的影响机理及控制策略研究

项目编号： No.51508382

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 建筑科学

项目作者： 程雪松

作者单位： 天津大学

项目金额： 23万元

中文摘要： 目前城市中施工场地周边密集的建筑物及隧道管线等对地层的变形限制非常严格，软土地区土质条件差，桩成孔引起的周边地层变形不容忽视。桩基施工过程中，自地表或桩顶标高以上开始成孔时会在地层中留下空桩孔，若回填不及时或未回填，便会在土体中形成大量空桩孔。这些空桩孔的水平卸荷作用相互叠加，可以引发周边土体较大的变形及沉降，进而造成周边建筑物、隧道、管线发生开裂、沉降，甚至垮塌等灾害，此问题在本研究中称为群孔效应。.本项目拟通过对软土地区群孔效应进行工程实测、离心机试验及数值模拟等多种手段的系统研究，探索大量空孔的相互作用及叠加机理，研究空孔对土体抗侧移刚度的影响，以及不同条件下群孔效应的影响大小及范围，提出预估群孔效应引发周边土体变形的简化计算方法，最终提出减小和避免群孔效应对周边环境影响的控制措施，从而为设计施工人员准确预估桩基施工对周边环境的影响、正确采取相关控制措施提供参考。

中文关键词： 桩基；相互作用；软土；桩孔；环境影响

英文摘要： The deformation of the ground must be strictly controlled when there are many buildings, tunnels and municipal pipes around the construction site in the city. The construction of boreholes of pile foundation can cause large ground deformation in soft soil area because of the bad soil condition. During the construction process of the pile foundation, if the boreholes are started from the ground surface or the elevation above the pile top, a large amount of hollow boreholes will be left in the soil strata when they are not refilled or not refilled in time. The superposition of the lateral unloading effects of the hollow boreholes can lead to significant deformation and settlement of the adjoining soil, and cause cracking, subsidence, or even collapse of the adjacent buildings, tunnels and pipes. This problem is named borehole group effect in this research..This project aims to investigate the borehole group effect systematically through field monitoring, centrifuge test and numerical simulation. The interaction and superposition mechanism of large amount of hollow boreholes, the influence of the boreholes on the lateral stiffness of the soil, and the magnitude and range of the influence of borehole group effect on the environment under different conditions will be researched. Finally, the simplified calculating method to evaluate the soil deformation caused by borehole group effect and the control methods to minimize the influence of the borehole group effect on the environment will be proposed to provide reference about predicting and controlling the influence of the borehole group effect for the designers and constructors.

英文关键词： pile foundation;interaction;soft soil;borehole;environmental influence