The Super Large Section Of Shallow Tunnel Construction Of The Underground Nest Of Tubes Protection Research

In the construction of urban underground structure, using mining tunneling method can minimize the impact on the surrounding environment, while ensuring the smooth flow of urban ground transportation and the normal use of underground pipelines. For underground structures with wide span, apart from ensuring their safety, quality, progress and controlling the cost, we must also take necessary measures to ensure the safety and normal use of underground pipe group.The structure of Shenzhen CITIC Underground Plaza Part B is constructed with flat-roof and upright-wall tunneling method, with a wide span of27.3m. One of the characteristics of this project is super-large cross-section and shallow-buried. Since underground pipeline is densely distributed under the site, the main difficulty of this project is how to protect the tube base and ensure the normal use of underground pipe group. In this paper, based on referring to large amounts of materials, combined with existing theory, the use of numerical analysis and combined with construction to test and practice, a comprehensive construction program, that is, large-pipe-shed advance support, small pipe grouting, eight pilot heading, all pilot holes staggered to each other, short step excavation, drainage in tunnel, is adopted finally to ensure the safety of road ground environment and road traffic as well as the normal usage of underground pipes.In this paper, the use of numerical analysis and finite element analysis theory, combined with field tests, the method of adopting overall construction program, as well as the successful construction case of flat-roof and upright-wall tunneling with super-large cross-section, provides referential experience for other underground engineering project with similar construction environment.