浅埋大跨下穿高速公路隧道施工风险评估及控制措施研究

Study on risk assessment and control measures in the construction process of shallow and large-span tunnel beneath expressway

为评估浅埋大跨下穿高速公路隧道施工风险和优化施工措施,结合深圳市红棉路隧道工程现场监测数据,建立基于功效系数法的隧道施工风险评估模型。计算分析表明,现有的施工措施无法满足下穿高速公路段施工安全要求,施工风险等级极高,需要及时对其调整。经综合分析,采取合理的施工步序、台阶长度、开挖进尺、掌子面封闭加固措施、隧道施工工序优化、及时封闭初支、加快二衬施工等一系列优化控制措施,并采用FLAC3D数值计算软件验证其可行性。同时,通过现场实施效果与监测数据的反馈,并应用提出的风险评估模型计算发现隧道下穿高速公路段施工风险等级已降为低度,证明采取的风险控制措施合理可行,能够保障隧道成功穿越机荷高速公路。

For evaluating construction risk and optimizing construction measures of shallow and large-span tunnelbeneath expressway, the field monitoring data of Hongmian road tunnel in Shenzhen was employed in this study.The risk assessment model of tunnel construction was established based on efficacy coefficient method. Throughthe calculation and analysis, the results show that the existing construction measures cannot meet safety requirementin the construction process of tunnel beneath expressway, and that the level of risk is extremely high andhence needs to be timely adjusted. Through comprehensive analysis, a series of optimization measures, for example,reasonable construction step, the suitable length of bench and excavation, soil reinforcement measures ontunnel face, optimizing construction process, closing primary support in time and speeding up the construction ofsecond lining, were used in construction, and the feasibility were verified by the numerical calculation softwareFLAC3D. Meanwhile, from the feedback of field implement and monitoring result, and in the application of riskassessment model put forward, the calculation results indicate that the level of risk has been reduced to be lowgrade in the construction process of tunnel beneath expressway. The risk control measures have been proved to bereasonable and feasibility, which can guarantee that the tunnel crosses Jihe expressway successfully.