盾构隧道穿越沼气地层风险识别与控制

Research on Identification and Control Technology for Shield Tunnel crossing Biogas Layer

为解决盾构隧道穿越沼气地层时由于沼气处理不当而发生安全事故,本文提出了盾构隧道穿越沼气地层的"事前、事中和事后"三层风险识别与控制体系。探讨了地质勘探中沼气来源与风险识别流程,进而通过分析盾构机的掘进速度、出土量与地层中赋存沼气的相互关系,确立了判定沼气等级的计算公式。建立了沼气监测系统,系统地论述了沼气隧道施工中对于施工技术等方面的要求与实现路径。制订了详细的应急预案响应机制以保证盾构施工的安全。以武汉地铁2号线汉—范区间为例,验证了该技术体系的应用效果。结果表明,该技术体系能够对盾构沼气地层进行有效的风险识别与控制,并帮助改进施工技术方案,保证了该盾构隧道零安全事故的顺利贯通,为后续类似沼气地层的盾构施工提供了重要借鉴。

In order to prevent safety accidents in shield tunnel crossing biogas layer according to improper handling of biogas,the risk identification and control technology for shield tunnel crossing biogas layer is established,which consists of three layers： pre-control,in-control and ex-control.Firstly,it discussed the risk identification process and criteria of geological exploration in shield tunnel.Then,the formulas for determining biogas level is established for providing a quantitative criterion of risk control level of biogas,which is due to analyze the interrelation of the speed of shield tunneling machine,the amount of unearthed and the concentration of biogas in formation. Secondly,a gas monitoring system in line with the actual needs is established,and systematically discussed the requirements and implementation path of ventilation,construction technology,et al. in biogas-tunnel construction. At the same time,a detailed contingency plan is developed to ensure the safety of shield construction. Finally,it illustrated the effect of the technology in Han-Fan interval of Wuhan Metro Line 2. The results show that the technology can effectively / identify,monitor and improve the construction program,ensured the shield tunnel passed through without any security incidents. It provides an important reference for the subsequent shield construction projects crossing biogas layer.