地下连续墙施工引起的土体变形实测与数值分析研究

发布时间：2018-04-11 14:26

本文选题：地连墙 + 现场实测　；参考：《天津大学》2014年硕士论文

【摘要】：随着人口密度加大,城市不断兴建和发展,大规模的高层建筑、地下空间建设正在进行。基坑深度、规模、难度的快速发展给设计、施工都带来了严峻的挑战。加之近些年来,基坑工程事故频发,需要对基坑施工的全过程给予更加细致、全面的研究。当基坑施工引起的变形需要严格控制时,常常采用刚度大、整体性较好的地下连续墙作为围护结构。过去在工程设计时一般不考虑基坑围护结构施工引起的土体位移,认为在地连墙施工期间,土体没有较明显的变化。然而很多工程实例表明围护结构施工可引起可观的土体变形。本文以地连墙施工为例,分析了围护结构施工引起的土体变化。以天津地区嘉海一期基坑工程的地连墙施工过程为监测对象,监测历时近10个月。在嘉海一期基坑南侧布置了4个监测断面,每个断面设置有测斜管、孔隙水压力测管等不同功能的孔位。实测结果表明地连墙施工对土体测斜值、孔隙水压力都有明显影响。地连墙施工完成后,坑外土体位移均远离地连墙方向,这主要是由于天津地区土体侧压力系数值较小(小于1)。对于地下连续墙施工过程中孔隙水压力,开挖成槽阶段,表现为卸荷效应占主导,槽段周围土体孔隙水压力有所下降。而灌注混凝土阶段,加载效应显著,土体孔隙水压力有所上升。采用三维有限元数值模拟地连墙施工,结果与现场实测数据拟合良好。并进一步分析搅拌桩隔离墙(是否存在、不同嵌固深度)、地表建筑物(不同荷载、不同距离)以及两种情况综合作用工况下,地连墙施工引起的土体变形。根据明德林(Mindlin)解推导地连墙施工引起土体水平位移的弹性数值解,土体的变量为泊松比和弹性模量,地连墙则主要考虑不同墙深。给出工程常见土层和地连墙工况下的数值解表格,便于实际工程应用。
[Abstract]:With the increase of population density and the continuous construction and development of cities, large-scale high-rise buildings and underground space are being constructed.The rapid development of foundation pit depth, scale and difficulty brings severe challenges to design and construction.In addition, in recent years, the foundation pit engineering accidents occur frequently, need to give a more detailed and comprehensive study on the whole process of foundation pit construction.When the deformation caused by foundation pit construction needs to be strictly controlled, the underground continuous wall with high stiffness and good integrity is often used as the retaining structure.In the past, the displacement of soil caused by the construction of retaining structure of foundation pit was generally not considered in the engineering design, and it was considered that there was no obvious change of soil mass during the construction of the ground connecting wall.However, many engineering examples show that the construction of retaining structure can cause considerable deformation of soil.In this paper, the soil mass change caused by the construction of the retaining structure is analyzed by taking the construction of the ground-connected wall as an example.Taking the construction process of the ground connection wall of the first stage foundation pit project in Tianjin area as the monitoring object, the monitoring lasted nearly 10 months.Four monitoring sections are arranged on the south side of Jiahai first stage foundation pit, each section is equipped with hole positions with different functions, such as inclined pipe and pore water pressure measuring pipe.The measured results show that the construction of the ground connecting wall has a significant effect on the slope value and pore water pressure of the soil.After the construction of the connecting wall, the displacement of the soil outside the pit is far away from the direction of the wall, which is mainly due to the fact that the coefficient of lateral pressure of the soil in Tianjin area is smaller (less than 1%).For the pore water pressure of underground continuous wall during the construction process, in the stage of trench excavation, the unloading effect dominates, and the pore water pressure of soil around the slot section decreases.However, in the stage of pouring concrete, the loading effect is obvious, and the pore water pressure of soil is increased.The three dimensional finite element method is used to simulate the construction of the ground connecting wall, and the results fit well with the field measured data.Furthermore, the soil deformation caused by the wall of mixing piles (existence or not, different embedded depth, surface buildings (different loads, different distances) and the combined action of two conditions are analyzed.According to Mindlin's solution, the elastic numerical solution of horizontal displacement caused by the construction of the ground connecting wall is derived. The variables of the soil are Poisson's ratio and elastic modulus, while the connecting wall's depth is mainly considered.The numerical solution table of the common soil layer and the ground-connected wall is given, which is convenient for practical engineering application.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU753

【参考文献】