盾构下穿既有建筑物桩基托换的风险管理研究

发布时间：2018-08-04 09:00

【摘要】：近年来,随着城市化进程的加快,城市地铁建设密度越来越大。城市既有建筑物密集,导致在地铁建设过程中穿越既有建筑物和构筑物的情况时有发生,这无疑给地铁建设增加了难度,也给地铁的安全施工提出了新的严峻课题。地铁在下穿既有建筑物过程中通常采用盾构隧道施工的方法,其中,在盾构下穿既有建筑物中需要采用桩基托换技术实现对建筑物的保护,因此,针对地铁盾构隧道下穿既有建筑物桩基托换的安全问题,建立科学合理的风险评价方法显得十分重要。本文在分析盾构隧道对地层、桩基、建筑物影响规律的基础上,构建了盾构下穿既有建筑物桩基托换的风险管理体系,并结合广州地铁盾构下穿鱼珠煤场宿舍A7楼工程,分析了盾构下穿既有建筑物桩基托换过程中主要风险因素,并针对主要风险要素制定相应的风险动态控制体系。为盾构下穿既有建筑物桩基托换施工提供了科学依据。主要工作如下:(1)分析了地铁—地层—桩基—上部建筑物四者之间的相互作用关系。论文首先分析地铁—地层—桩基—上部建筑物四者之间的关系,发现控制地层变形是保证盾构下穿既有建筑物的核心因素。接着在介绍盾构施工特点的基础上分别介绍了盾构施工对地层的影响、地层变形对既有桩基的影响和地层变形对既有建筑物的影响。(2)构建了盾构下穿既有建筑物桩基托换风险管理体系。在分析了盾构隧道对地层、桩基、建筑物影响规律的基础上,构建了盾构下穿既有建筑物桩基托换风险管理体系,识别出包括盾构隧道施工风险和建筑物自身风险在内的7大类36个风险因素。在对数据进行处理后利用专家知识建立贝叶斯网络拓扑结构,并借助GeNIe2.0软件参数学习的功能得到更为合理的盾构下穿既有建筑物桩基托换安全风险贝叶斯网络。(3)以广州地铁盾构下穿鱼珠煤场宿舍A7楼工程为例对风险管理体系进行应用。参照建立的盾构下穿既有建筑物桩基托换风险管理体系,结合广州地铁盾构下穿鱼珠煤场宿舍A7楼工程,在识别出风险因素后,制作调查问卷获取风险评价的基础数据,并利用SPSS22.0软件对基础数据进行信度分析和效度分析。然后运用贝叶斯网络自带的算法,对得到的盾构下穿既有建筑物桩基托换安全风险贝叶斯网络进行逆向推理、敏感性分析和最大致因链分析,找到对盾构下穿既有建筑物桩基托换安全影响较大的风险因素。针对较大的风险因素,制定相应的监控体系和动态风险控制体系。监控体系包括对主托梁受力的监测、楼体倾斜和楼体结构变形的监测、柱子沉降和千斤顶顶力的监测。通过监测数据实时对各风险因素进行反映,保证整个盾构隧道下穿既有建筑施工的安全。
[Abstract]:In recent years, with the acceleration of urbanization, urban subway construction density is increasing. The density of the existing buildings in the city leads to the situation of passing through the existing buildings and structures in the process of subway construction, which undoubtedly increases the difficulty of the subway construction and puts forward a new severe subject for the safe construction of the subway. The construction method of shield tunnel is usually used in the process of subway passing through the existing building, in which the pile foundation underpinning technique is needed to protect the building. It is very important to establish a scientific and reasonable risk assessment method to solve the safety problem of pile foundation underpinning under shield tunnel. On the basis of analyzing the influence of shield tunneling on stratum, pile foundation and building, this paper constructs the risk management system of pile foundation underpinning under shield tunneling, and combines with the A7 floor project of the dormitory of Yuzhu Coal Yard under shield tunneling in Guangzhou Metro. The main risk factors in the process of pile foundation replacement under shield machine are analyzed and the corresponding risk dynamic control system is established for the main risk factors. It provides scientific basis for pile foundation replacement construction under shield tunneling. The main works are as follows: (1) the interaction between the four subways, the stratum, the pile foundation and the upper building is analyzed. Firstly, the paper analyzes the relationship between the four persons of subway, stratum, pile foundation and upper building, and finds that controlling the deformation of stratum is the key factor to guarantee the penetration of existing building under shield. Then, on the basis of introducing the characteristics of shield construction, the influence of shield construction on stratum is introduced respectively. The influence of formation deformation on existing pile foundation and the influence of stratum deformation on existing building. (2) the risk management system of pile foundation underpinning under shield is constructed. On the basis of analyzing the influence of shield tunneling on stratum, pile foundation and building, the risk management system of pile foundation underpinning under shield tunneling is constructed. 36 risk factors including shield tunnel construction risk and building risk are identified. After processing the data, the topological structure of Bayesian network is established by using expert knowledge. With the help of the function of parameter learning of GeNIe2.0 software, a more reasonable Bayesian network for safety risk of pile foundation underpinning under shield tunneling is obtained. (3) the risk management system is applied to the A7 floor project of Yuzhu coal yard dormitory under shield tunneling in Guangzhou Metro. With reference to the established risk management system for pile foundation underpinning of existing buildings under shield tunneling, combined with the A7 floor project of the dormitory of Yuzhu Coal Yard under shield tunneling in Guangzhou Metro, after identifying the risk factors, a questionnaire was made to obtain the basic data of risk evaluation. The reliability and validity of basic data were analyzed by SPSS22.0 software. Then the Bayesian network with its own algorithm is used to carry out reverse reasoning, sensitivity analysis and maximum factor chain analysis to the security risk Bayesian network under shield tunneling pile foundation replacement of existing buildings. The risk factors affecting the safety of pile foundation underpinning under shield tunneling are found. According to the larger risk factors, the corresponding monitoring system and dynamic risk control system are established. The monitoring system includes the monitoring of the stress of the main bracket, the monitoring of the slope of the building and the deformation of the building structure, the monitoring of the settlement of the columns and the force of the Jack. The risk factors are reflected by monitoring data in real time to ensure the safety of the whole shield tunnel under the existing building construction.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U455.43;TU753

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