The first component of the first two-way eight-lane prefabricated open-cut arched tunnel in China was successfully implemented

Recently, with the completion of the last concrete pouring of the prefabricated components of the first prefabricated tunnel of the Xinsen Avenue Project of the Southwest Company of China Construction Seventh Bureau. It marks the phased progress of the first two-way eight-lane prefabricated open-cut arched tunnel in China, laying a solid foundation for ensuring the on-schedule construction of the next on-site assembly of the project.

On the afternoon of August 6, in the prefabricated yard of the Xinsen Avenue project, with the start of the hopper, the gray-black concrete was slowly poured into the already assembled high-precision hydraulic system arch formwork with a length of 16m and a height of 5.6m. The workers carefully and meticulously operated it. They used a combination of mechanical automatic vibrating and manual vibrating to overcome the difficulties of dense steel bars and many embedded parts. This piece of component weighs more than 70 tons. After the strength meets the requirements, it can be dismantled and transported to the storage area for orderly storage, waiting for on-site assembly.

According to Yuan Shunli, the executive manager of the project, the project is a key project in Chongqing High-tech Zone, with strict requirements on environmental protection, construction period and quality. In the face of high pressure on environmental protection, many factors affecting the construction period, difficult quality control of mass concrete, large investment in construction manpower and material resources, and high safety risks. After many investigations and investigations, the Southwest Company of China Construction Seventh Bureau innovatively proposed the adoption of a new technology of prefabricated tunnel structure, which won the support of the owner and all participating units. The China Construction Seventh Bureau led the "Research on Prefabrication Technology of Super-Span Open-cut Tunnel Structure", and carefully built a prefabricated component factory, using BIM+ prefabricated, 3D scanning, overall machine tool automatic control milling template and other new technologies and new processes. It solved the production problem of high-precision prefabricated components; through a large number of concrete mix ratio tests, it solves the technical problems of high-performance concrete such as poor workability of concrete and slow growth of strength in the later stage, and only saw the pouring of the first component.

The implementation of prefabricated tunnels realizes the standardized production of cut-and-cover tunnel linings, greatly improves the quality of tunnel projects, and greatly reduces the construction period. More importantly, it meets the requirements of green environmental protection and responds to the guidance and goals of the national "dual carbon" strategy. It is expected to formulate corresponding technical standards and construction guidelines for the industry, and provide reference value and normative guidance for the implementation of subsequent similar projects.