21世纪以来，中国地下工程建设突飞猛进，导致由地铁盾构施工引起的多种安全事故频发。地铁盾构施工安全灾变机理相当复杂，是一个动态的不确定性问题。因此，准确把握地铁盾构施工全过程安全风险变化规律，分析地铁盾构施工事故演化机理，具有重大理论和现实意义。本文在借鉴国内外相关研究的基础上，首先，分析了地铁盾构施工全过程的工艺流程及作业要点，基于地铁盾构施工安全风险发生机理，建立了安全风险评价指标体系：其次，基于探索因素分析(EFA)与结构方程模型(SEM)相结合的方法，从主观角度探究了地铁盾构施工全过程安全风险变化规律；然后，利用迭代自组织数据(ISODATA)聚类算法，分析了客观发生的地铁盾构施工安全事件，从客观角度验证了安全风险“浴盆”曲线规律的有效性，确定事故的主要类型为突涌及地表沉降超限。最后，针对主要的突涌及地表沉降超限事故，通过ABAQUS有限元数值分析技术，构建了精细化仿真模型，分析地铁盾构施工突涌事故的风险演化过程；采用蝴蝶结分析(BTA)与模糊贝叶斯网络(FBN)相结合的方法，评估了地铁盾构施工地表沉降超限的安全风险演化过程；根据ABAQUS仿真计算结果及BTA-FBN概率分析结论，制定了相应的安全风险控制措施，有效提高了地铁盾构施工现场安全管理绩效。本文主要研究内容如下： (1)为减少因知识缺乏而产生的地铁盾构施工全过程安全风险认知的不确定性，在分析梳理地铁盾构施工全过程的工艺流程及作业要点的基础上，构建了安全风险评价指标体系；依据安全风险评价指标体系，形成了地铁盾构施工全过程安全风险调查问卷；根据现场施工人员主观经验的问卷调查结果，利用探索性因素分析(EFA)和结构方程模型(SEM)方法，拟合得出了地铁盾构施工全过程安全风险“浴盆”曲线规律，实现对地铁盾构施工全过程安全风险分布重点阶段及主导风险因素的可知和预估，为基于ISODATA的地铁盾构施工安全事件聚类研究提供了基本框架。 (2)在地铁盾构施工全过程安全风险变化规律分析的基础上，利用ISODATA聚类算法研究了客观发生的地铁盾构施工安全事件(未遂事件及事故)，拟合得出了地铁盾构施工全过程安全风险“浴盆”曲线规律，从客观角度验证了基于EFA-SEM的地铁盾构施工全过程安全风险变化规律的有效性。此外，通过聚类分析地铁盾构施工未遂事件及事故，确定了地铁盾构施工事故的主要类型，为后续事故演化机理解析确定主要研究对象。首先，将发生频率高、严重程度低的未遂事件纳入研究范围，扩展数据库的信息来源；其次，根据EFA-SEM模型提取的施工阶段及风险因素基本框架，分析收集的243安全事件，定义数据库结构所包含类别及变量，形成结构化数据库；最后，通过ISODATA聚类算法建立聚类集群，分析整体数据库变量分布情况，拟合得出地铁盾构施工全过程安全风险“浴盆”曲线；对比分析集群与集群、集群与数据库之间，发生的各种后果严重程度水平，获取集群风险程度的量化结果，确定地铁盾构施工事故的主要类型为突涌及地表沉降超限。 (3)根据地铁盾构施工事故主要类型为突涌的结论，探究地铁盾构施工突涌事故演化机理。以XW盾构区间为研究背景，考虑水土流固耦合作用，管片衬砌不连续性，以及管片、注浆层和围岩之间的相互作用，结合3D非线性接触理论，建立了地铁盾构施工突涌事故精细化仿真模型；以不同水头差的变化反映涌水量的动态演化，探究了其对盾构施工中管片接缝的机械和变形性能影响；通过对比分析盾构区间不同阶段突涌事故模型结果，验证了始发.到达为施工安全风险控制重点阶段；依据突涌事故模型计算结果，提出了土体加固深度以及涌水排放量的安全控制措施。 (4)根据地铁盾构施工事故主要类型为地表沉降超限的结论，探究地铁盾构施工地表沉降超限事故演化机理。以XW区间盾构隧道工程为例，利用模糊统计试验理论定义“正常地铁盾构施工状态”，从“正常地铁盾构施工状态”样本数据库提取设备故障发生概率：利用专家加权聚集模糊数三角形和梯形数方法，获取环境失效、操作失误及多重故障发生概率；结合蝴蝶结分析(BTA)及模糊贝叶斯网络(FBN)方法，将蝴蝶结分析映射到模糊贝叶斯网络，建立了“正常地铁盾构施工状态”因果网络BTA-FBN评价模型；引入伯恩鲍姆测度(BM)、风险增加当量(RAW)及故障树下行法(FV)三个相应的重要措施，确定了“正常地铁盾构施工状态”地表沉降模型的关键节点；通过对比分析盾构区间不同阶段地表沉降超限BTA-FBN模型结果，验证了始发-到达为施工安全风险控制重点阶段；根据BTA-FBN模型确定的事故动态演化场景关键节点，制定了地铁盾构施工地表沉降超限的安全控制措施。 关键词：地铁盾构；施工全过程；安全风险；探索因素分析；结构方程模型；蝴蝶结分析；模糊贝叶斯网络

 Since the 21st century, the construction of underground projects in China has developed rapidly, accidents caused by metro construction frequently occur. The intrinsic dynamic nature and uncertainty along with the shield tunneling, make the evolution of the accidents complicated with multi-source risk factors. Therefore, it is of great theoretical and practical significance to explore the law of evolution mechanism from safety risk factors to the final accidents during the shield tunneling process. Firstly, we analyzed the working process and key points of operation during the shield tunnel construction, and established a risk evaluation index system based on the risk mechanism of metro construction. A method of integrating exploratory factor analysis (EFA) with structural equation model (SEM) was proposed to investigate the safety risk change law of the whole process of metro shield construction from the subjective point of view. Subsequently, the iterative self-organizing data (ISODATA) clustering algorithm was employed to analyze the incident report of the metro shield construction, which indicated the effectiveness of safety risk “bathtub” curve law from the objective point of view, and revealed that inrushing and excessive ground settlement were the main accident types. Finally, we constructed a fine simulation model by ABAQUS, and analyzed the safety risk evolution process of the inrush accidents in the metro shield construction. We integrated the Bow-tie analysis (BTA) and the Fuzzy-Bayesian Network (FBN) to analyze and evaluate safety risk of the excessive surface settlement in the metro shield construction dynamically. Combining the results of ABAQUS simulation and the BTA-FBN probability analysis, the corresponding safety management measures were formulated, which can effectively assist the control of safety risk in metro construction. The main contents of this thesis are as follows: (1) To reduce the cognition uncertainty about tunneling induced safety risk due to the lack of kowledge, the working flow and key points of operation during the whole metro shield construction process were analyzed, and a safety risk evaluation index system was established. In the light of the safety risk assessment index system, a safety risk survey questionnaire for the whole process of metro shield construction was formed. According to the questionnaire survey results of the subjective experience of the site workers, by integrating the exploratory factor analysis (EFA) with the structural equation model (SEM), we established the safety risk "bathtub" curve indicating the key stages with high safety risk and the leading risk factors in the whole process of metro shield construction, which provide a basic framework for the clustering research of safety shields based on ISODATA. (2 ) On the basis of the analysis of the change of the safety risk in the whole process of the metro construction, the ISODATA clustering algorithm was used to study the metro shield construction safety events (i.e. near-miss and accidents). The law of the "bathtub" curve of the safety risk in the whole process of the metro construction was fitted, which verified the safety risk change rule in the whole process of metro construction based on EFA-SEM from an objective point of view. In addition, through cluster analysis of metro construction accidents, the main types of accidents were determined, which is the research object of the subsequent accident evolution mechanism analysis. Firstly, to cover as much information as possible, the near-misses with high frequency and low severity were also included in database. Secondly, according to the basic framework of the construction phase and risk factors extracted by the EFA-SEM model, 243 collected safety events were analyzed, to establish a structured database with the incidents categories and variables contained. Finally, the cluster was established by ISODATA clustering algorithm, and the distribution of the overall database variables were analyzed. The safety risk “bathtub” curve of the whole process of metro shield construction was obtained. Through the comparison of clusters and database, as well as the severity level of various consequences, the result of the risk degree of the clusters was obtained, thus confirming the main types of the metro construction accident are inrushing and excessive surface settlement. (3) According to the conclusion that the main type of metro construction is the inrushing, the evolution mechanism of the inrush accidents in metro construction was explored. The shield tunneling of the XW section was selected as a study object in this thesis. A fine hybrid model of the inrush accident in the construction of metro shield was established based on the 3D nonlinear contact theory, with in consideration of the interaction between soil and water, the lining discontinuity of shield tunnel and the interactions between tunnel segments, grouting layer and surrounding rock. The variation of water head difference that reflects the dynamic evolution of water grushing flow, was simulated to investigate their effects on the mechanical and deformation properties of the segments and joints in the shield construction. By comparing and analyzing the results of the inrush accident model in different construction stages, it was verified that the launching-arrival was the key stage of construction safety risk control. Moreover, the safety measures of controlling the depth of the end reinforcement and the discharge of gushing water were put forward based on the calculation results of the inrush accident model. (4) According to the conclusion that the main types of metro construction accidents is the excessive surface settlement, the evolution mechanism of the excessive surface settlement accidents in metro shield construction was discussed. Based on the fuzzy statistic test theory, the "normal metro shield construction status" during the shield tunneling of the XW section was defined, which was used to extract the equipment failure probability from the noise reduction sample database. The probabilities of environment failure, operation error and multiple faults were evaluated by adopting improved expert weighted aggregation of fuzzy number triangles and trapezoidal numbers. A hybrid method combining bow analysis (BTA) and Fuzzy-Bayesian Network (FBN) was proposed, which map the Bow-tie analysis into the Fuzzy Bayesian network to establish the causal network BTA-FBN evaluation model for the "normal metro shield construction state". By introducing three corresponding important measures, Bimbaum measure (BM), risk achievement worth (RAW), and Fussell-Vesely (FV), the key nodes of normal surface settlement model in "normal metro shield construction state" were identified. By comparing and analyzing the BTA-FBN model results of surface settlement at different stages of shield tunneling, it was verified that launching-arrival was the key stage of construction safety risk control. In addition, the relevant safety measures for excessive surface settlement were developed according to the identified key nodes of the accident dynamic evolution circumstance determined by BTA-FBN model. Key words: Metro shield; Whole construction process; Safety risk; Exploration factor analysis; Structural equation model; Bow-tie analysis; Fuzzy Bayesian network