大型海底隧道钻爆法修建关键技术

Key technology of large cross-section subsea tunnel construction using drill and blast method

针对海底隧道建设和运营中的突出问题,以工程安全和排水量控制为核心,对其关键技术进行了系统的研究和实践.限于通道两岸接线的条件,提出了"极限顶板厚度"的概念,使隧道纵断面位置的选择更加自如;基于精细化的地质勘察,提出了物探与钻探相结合,以钻探为主的超前探测方法;针对海底隧道施工对围岩稳定和堵水的双重要求,提出了"复合注浆"的新理念,并形成了相应的周边帷幕注浆技术;通过对地层变形及动态演化过程的研究,建立了施工扰动下海床安全状态与隧道围岩变形的量化关系,制定了保证隧道安全性的围岩变形控制标准;提出了隧道原始渗水量的分级方法,建立了基于排水量控制的围岩加固圈和支护结构设计方法,明确了初期支护的主承载作用,二次衬砌结构通常仅作为安全储备;针对海底隧道的高风险特点,建立了工程安全控制体系,形成了相应的管理基准和我国海底隧道钻爆法修建的技术模式.

The prominent problems emerged in the construction and operation periods of subsea tunnels are engineering safety and water discharge control.This paper conducted a systematic research and extensive practice on the related key techniques.Due to the limited conditions of both adjacent shores,the paper put forward the concept of ＂ultimate roof thickness＂,which made the selection of tunnel alignment much more convenient.For the advanced detection,based on the elaborate geological investigation,a combination method was proposed that drilling exploration worked together with geophysical prospecting and extra emphasis was paid on drilling exploration.This method successfully guaranteed the construction safety.For the requirements of surrounding rock stability and water sealing,the paper brought up the new concept of ＂composite grouting＂ and established the related techniques of curtain grouting,which improved the grouting efficiency and reliability.According to the study of the evolution process of ground deformation,the paper established the quantity relationship between the surrounding rock deformation and seabed safety during ttnnel construction.The paper proposed the classification method due to water inflow and established the design method of the support structure and grouting zone of the surrounding rock,based on the water inflow control theory.The design philosophy clarified that the primary support bore the majority parts of the load and the secondary lining services as safety reserve.Against the high-risk characteristic of subsea tunneling projects,the paper established the engineering safety control system and a set of management criteria,and constituted the technical mode of subsea tunneling with drill and blast method in our country.