基于大样本的强透水砂层盾构施工风险与控制研究

Risk Analysis and Handling of Shield Construction in Watered Sandy Stratum from Large Volume Data

基于大量强透水砂层盾构施工工程事故现场调研及资料分析,建立大样本数据库并构建强透水砂层盾构施工风险事故树,以分析风险源及各自权重;基于模糊综合评价法探究强透水砂层盾构施工风险评估方法,推导出各风险因素对风险发生概率和损失的评价矩阵,从机理控制层面提出风险控制措施,并以广州某强透水砂层盾构工程实施验证。研究表明,施工风险主要为管片破裂、隧道上浮、渣土喷涌及地表塌陷等,风险发生概率与相应损失程度均可划分为5个等级。可通过加强管片拼装质量、改善上覆土层工程特性、渣土改良及装置改进等风险规避策略,有效控制施工风险,并结合风险规避、保留及转移等3种策略对地表塌陷风险进行有效控制。

Based on large volume data of site investigation and engineering data analysis of shield construction in Strengthened permeable grit stratum,a fault tree is built to obtain the risk sources and their weight.Then the method of risk evaluating is studied on the basis of fuzzy comprehensive evaluation in two steps：The factor sets of both probability and loss are given according to risk source;and by using trapezoidal membership functions,the probability and loss of each factor are calculated as a matrix of risk evaluation.After that,the level of risk is confirmed through the matrix of risk evaluation.Finally,on the basis of risk handling principle,the risk handling measures are proposed from the mechanism of level,which is proved in practical engineering in Guangzhou.The study shows that,risk of shield construction is consisted of segment crushing,tunnel floating,spewing and ground collapsing etc.And the probability of risk as well as the loss of risk can both be divided into five degrees.Moreover,the main risk of shield construction,such as segment crushing,tunnel floating and spewing,can be well controlled by using risk aversion strategy such as the improvement of segment installing quality and the stratum properties,and risks of ground collapsing can be controlled by using risk aversion strategy,retention strategy and risk transfer strategy and so on.