基坑土体参数及超挖变形的数值模拟研究

发布时间：2018-05-14 04:32

本文选题：土质基坑 + 桩锚支护　；参考：《重庆大学》2014年硕士论文

【摘要】：随着重庆市直辖以来工程建设的加速发展，基坑工程数量愈来愈多。其中一些开挖深度内全是土体的土质基坑，其变形相比于岩质基坑较大，但又不同于软土地区的基坑，使得桩锚支护结构体系在这类基坑中的应用较为广泛。由于目前基坑工程的设计理论尚不够完善，，其支护体系的变形研究仍处于发展阶段，因此利用数值分析方法对基坑变形进行研究是十分必要的。但由于计算参数常常不易获得，且对数值分析中的参数取值研究不够重视，导致一些数值分析模型的可靠性较低，不能满足工程要求；并且在实际施工中由于与设计脱节，未遵循时空效应的分层开挖原则而超挖的现象时有发生，超挖引起的过大变形带来了诸多工程问题。因此，本文针对重庆地区桩锚支护结构的土质基坑工程做了如下研究探讨： ①对基坑工程设计分析的三种常用方法进行了简单介绍，并重点说明FLAC3D软件的原理和适用性；探讨数值模拟分析方法中的两个关键问题，即本构模型的选用及土体弹性模量的取值。 ②基于地勘报告中的土体参数，利用FLAC3D软件对重庆地区桩锚支护结构的土质基坑工程实例进行数值模拟。然后结合实测数据进行土体参数的位移反演分析，得到了满足工程要求的可靠数值分析模型；同时探讨重庆地区适用于数值分析的土体弹性模量E的取值关系。 ③在上述可靠数值模型的基础上，分析部分工程实例的原设计开挖工况的支护桩水平变形；然后重点进行不同位置不同厚度的单一超挖工况的数值模拟分析，探讨单一超挖对支护桩水平变形的影响规律。 ④结合支护桩水平变形的预警值，探讨最大允许分层开挖厚度的理论值；并对其建议值的可行性进行分析。
[Abstract]:With the rapid development of engineering construction in Chongqing, the number of foundation pit engineering is increasing. Some of them are soil foundation pit in the depth of excavation, its deformation is larger than that of rock foundation pit, but it is different from the foundation pit in soft soil area, so the pile-anchor support structure system is widely used in this kind of foundation pit. Because the design theory of foundation pit engineering is not perfect at present, the research on deformation of supporting system is still in the developing stage, so it is very necessary to study the deformation of foundation pit by using numerical analysis method. However, the calculation parameters are often difficult to obtain, and the research on the parameter values in the numerical analysis is not paid enough attention to, which leads to the low reliability of some numerical analysis models, which can not meet the engineering requirements, and is out of touch with the design in the actual construction. The phenomenon of overdigging occurs from time to time, which does not follow the principle of stratified excavation with space-time effect. The excessive deformation caused by over-excavation has brought a lot of engineering problems. Therefore, this paper has done the following research on the soil foundation pit engineering of pile and anchor support structure in Chongqing area: The main contents are as follows: 1. Three common methods of foundation pit engineering design and analysis are briefly introduced, and the principle and applicability of FLAC3D software are emphatically explained, and two key problems in numerical simulation analysis method are discussed. That is, the selection of constitutive model and the value of elastic modulus of soil. 2 based on the soil parameters in the geological prospecting report, the numerical simulation of soil foundation pit engineering example of pile and anchor supporting structure in Chongqing area is carried out by using FLAC3D software. Then, based on the measured data, a reliable numerical analysis model is obtained, which meets the requirements of engineering, and the relationship of soil elastic modulus E suitable for numerical analysis in Chongqing area is also discussed. 3 on the basis of the above reliable numerical model, the horizontal deformation of the supporting pile under the original design excavation condition of some engineering examples is analyzed, and then the numerical simulation analysis of the single overworking condition with different positions and different thickness is carried out. The influence of single overbreak on horizontal deformation of supporting pile is discussed. (4) based on the early warning value of horizontal deformation of supporting pile, the theoretical value of maximum allowable thickness of layered excavation is discussed, and the feasibility of the suggested value is analyzed.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU470

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