【作者】 刘洪斌；

【导师】 张宏胜；

【作者基本信息】 重庆大学 ， 土木工程， 2011， 硕士

【摘要】 随着城市的不断发展,城市建设不断的朝着深、高的方向发展,这都要求建筑要有很好的基础结构,从而产生了大量的深基坑工程。由于深基坑工程难度大,周期长,造价高,如何对其支护结构进行有效的设计分析,以及对其安全的控制保证就成为焦点。传统的深基坑边坡稳定性分析客观上存在着大量的不确定性,充分考虑由各种因素引起的不确定性是边坡稳定性研究的发展趋势。本文利用MIDAS有限元软件,采用单位建模,对成都金阳项目建立了基坑开挖、支护模拟的有限元模型,模拟分析了在不同的工况作用下,其基坑的水平以及垂直位移变形情况,并反馈与设计,从而可以更好的优化设计,优化造价。通过模拟得到如下结论:①基坑开挖后,应用数值模拟技术对开挖过程中的各种复杂应力状况进行动态模拟分析,分析在开挖过程中基坑的变形位移,我们得到其在不同施工进程(直接开挖和分部开挖)、不同锚杆倾角(15度与18度)、有无附加荷载(有施工附加荷载与无施工荷载)的情况下,基坑位移变形的大小对比情况,为工程开挖做前期方案做定性分析。②有限元法模拟基坑开挖过程中的不同锚杆间距(1.5米与2.0米)状况下的基坑位移变形大小分析,为工程决策做出参考,在满足工程安全的情况下,进行造价优化。同时基于土体的不确定性,实际工程的影响因素较大,数值模拟很难对基坑工程定量分析的特点,引入灰色理论的基本概念,将深基坑边坡系统视为一个灰色系统,对深基坑支护结构的水平、垂直位移建立GM(1,1)模型,对其基坑变形做出有效的模拟和预测。同时,本文还尝试引入在隧道工程中常用的Verhulst模型,对基坑变形做出警戒性预测,对基坑变形可能出现的最大值做出定量分析。为基坑预警做出探索。研究结果表明:灰色系统理论在深基坑变形预测分析中是比较有效的,具有良好的前景。改进型GM(1,1)模型预测变形较之其他的模型有明显的优势,而Verhulst模型则是对破坏曲线的一个具体模拟,可以得到较好的包络线,提供警戒值。更多还原

【Abstract】 Accompany with the development of the city construction ,the buildings were builded higher and higher . As a result ,the building must have a durable basis, the foundation must be deep. But becanse of the foundation construction is very difficult and costs a lot of money with long period, the deep foundation construction is be paid more and more attention by the government and the engineers. How to make the deep foundation to be safety and how to optimizate the design are becomed focus. Many scholars have spended energy on it. Traditional slopal foundation thoery have many uncertain factors. Nowady, scholars consider the uncertains as indispensable factors in designs. The theroy as this becomes more and more popular.L use the finite element sofeware like MIDAS in the aricle below . it uses the modeling unite to set up an excavation project and the foundation support simulation established the jingyang projection in chengdu. It have simulated the horizonal displacement and the vertical dispalcement in different conditons. After that, we result back, and optimizate the design and decease the cost .we have get some conclutions from the simulations:①After the excavation of numerical simulation technology, application of various excavation process complex stress status, analyzes the dynamic simulation in excavation pit deformation displacement in the process ,We get different construction process in the excavation and division, different anchor excavation Angle (15 degrees and 18 degrees), whether additional load (construction with no additional load under the condition of construction load), the size of the displacement deformation of foundation pit excavation projects for comparison, the qualitative analysis is done do scheme.②Finite element method to simulate the excavation process different anchor spacing (1.5 meters and 2 meters) of excavation displacement situations for engineering deformation amplitude analysis, reference, satisfying the decisions under the condition of construction safety, cost optimization.Meanwhile, based on the uncertainty of soil influence factors of actual engineering larger, numerical simulation is hard to the characteristics of foundation pit engineering quantitative analysis, and introduce the basic concept of grey theory, deep foundation pit slope system as a gray system of deep foundation pit bracing structure, the horizontal and vertical displacement establish GM (1, 1) model, the deformation of the simulation and forecast an effective. At the same time, this paper also attempt to introduce in the tunnel engineering used in Verhulst model, the deformation forecast to make of vigilance deformation, the maximum possible to quantitative analysis. For foundation pit warning to explore.The result show that : The grey theroy is very useful in the forcasting of foundation deformation . The development of the GM (1,1) have much more advantages than other medals, and the Verhust medal have a good performace in providing the warning values.更多还原