地铁盾构施工引起的地层沉降对周边建筑的影响研究

发布时间：2018-07-10 15:09

本文选题：地铁施工 + 盾构　；参考：《武汉理工大学》2015年硕士论文

【摘要】：城市人口密度的增加对公共交通的发展提出了更高要求,地铁由于安全、高效和环保而被广泛应用。我国正处于城市化建设高速发展阶段,许多城市都积极进行地铁修建。然而地铁线路规划需综合考虑地上、地下各方面因素,故地铁线路在铺设时无可避免地会下穿现有建筑,而地铁施工引起的地层沉降必将对地表建筑产生一定的影响。故在施工前期需对这些结构的安全性能进行预评估,判断地铁施工引起的地层沉降是否会影响临近结构的正常使用和结构安全。基于大量工程经验,目前我国普遍规定地铁施工引起的地层沉降不超过3cm。但由于各地地质条件、结构形式、隧道半径和埋深等方面的差异,该规定值的实用性面临很大的争议:对施工环境地质条件较好,且周边建筑基础埋深较深的施工工况而言,该值可能过于严格,从而增大施工难度;但对于施工环境地质条件较差,且周边建筑为历史建筑的施工工况而言,该值可能并不能保证结构的安全。由此可见,要确定地铁施工引起的地层沉降对周边结构的影响限值,应当针对不同的地质条件、建筑结构形式及基础形式等进行具体研究。本文以某九层框架结构为研究对象,分别采用整体有限元方法和基于Peck公式的简化方法,研究地铁施工引起的地层沉降对结构受力和变形的影响。具体研究工作包括:1)总结归纳目前地铁施工引起地层沉降的预测方法,并采用Peck经验公式给出了北京、上海、广州三地的地层沉降预测模型。研究了隧道埋深、地质条件及沉降槽宽度等关键参数变化对沉降曲线的影响。2)建立隧道-土层-框架结构整体有限元模型,采用单元生死的方法模拟盾构施工过程,分析结构的受力和变形特征。3)基于上述Peck公式确定的不同关键参数下的沉降曲线,将其作为外荷载在某九层框架结构基础底部输入,分析结构的受力和变形特征。4)基于受力分析的结构安全性评价,选取结构柱的开裂荷载为结构安全性评判指标,讨论不同基础形式、隧道与结构相对位置、隧道埋深等不同沉降曲线下结构的安全性。5)在基于变形的结构安全性评价,系统总结目前国内外对地铁施工引起沉降的评估指标和评价方法,并在归纳总结的基础上选用我国规范的相关指标作为评价指标,对该九层框架在不同沉降值下的安全性能进行了评估。研究结果表明:采用整体有限元法和简化的Peck公式法均可分析地铁施工引起的地层变形对结构的影响,但显然简化公式法更为简单、实用;基于结构受力和变形两方面的评价指标得到的评价结果是相同的,即表明二者的统一性。
[Abstract]:The increase of urban population density puts forward higher requirements for the development of public transport. Subway is widely used because of its safety, efficiency and environmental protection. Our country is in the urbanization construction high-speed development stage, many cities are carrying on the subway construction positively. However, it is necessary to take all factors above ground and underground into consideration in subway line planning, so it is inevitable that subway line will go through the existing building when laying, and the ground settlement caused by subway construction will have certain influence on the surface building. Therefore, it is necessary to pre-evaluate the safety performance of these structures in the early stage of construction to determine whether the ground settlement caused by subway construction will affect the normal use of adjacent structures and structural safety. Based on a large amount of engineering experience, it is generally stipulated that the ground settlement caused by subway construction in China is not more than 3 cm at present. However, due to the differences in geological conditions, structural forms, tunnel radius and burial depth in various places, the practicability of the specified values faces great controversy: for the construction conditions where the geological conditions of the construction environment are good, and the foundation of the surrounding buildings is buried deeper, This value may be too strict to make the construction more difficult, but it may not guarantee the safety of the structure when the construction environment and geological conditions are poor, and the surrounding building is the construction condition of the historical building. It can be seen that in order to determine the limit value of the influence of ground subsidence caused by subway construction on the surrounding structure, it is necessary to study the different geological conditions, the form of building structure and the form of foundation, etc. In this paper, a nine-story frame structure is taken as the research object, and the global finite element method and the simplified method based on Peck formula are used to study the influence of ground settlement caused by subway construction on the stress and deformation of the structure. The concrete research work includes: 1) summing up and summing up the prediction methods of ground subsidence caused by subway construction at present, and using Peck empirical formula to give the prediction models of ground subsidence in Beijing, Shanghai and Guangzhou. The influence of the key parameters such as depth of tunnel, geological condition and width of settlement trough on settlement curve is studied. 2) the integral finite element model of tunnel-soil-frame structure is established, and the method of element birth and death is used to simulate the construction process of shield tunneling. Based on the settlement curves of different key parameters determined by the Peck formula above, the settlement curves are input as external loads at the base of a nine-story frame structure. Based on the structural safety evaluation of the stress analysis, the cracking load of the structural column is selected as the structural safety evaluation index, and the different foundation forms, the relative position of the tunnel and the structure are discussed. Safety evaluation of structures under different settlement curves, such as tunnel depth, is based on deformation-based structural safety evaluation. The evaluation indexes and methods of settlement caused by subway construction at home and abroad are systematically summarized. On the basis of summing up and summarizing, the safety performance of the nine-story frame under different settlement values is evaluated by selecting the relevant indexes of the code of our country as the evaluation index. The results show that the whole finite element method and the simplified Peck formula method can be used to analyze the influence of formation deformation caused by subway construction on the structure, but it is obvious that the simplified formula method is simpler and more practical. The evaluation results based on the structural stress and deformation are the same, that is to say, the unity of the two.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U231.3;U455.43;TU433

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