[**Ningxia Internet Radio and Television Station].
The deep and lengthy flute of the giant ship woke up the sleeping Dalian Bay, and a red sun gradually surfaced on the sea, opening a new and enthusiastic day for the builders.
Under Dalian Bay, the undersea tunnel lies in it like a giant python. You Jin, manager of the main structure project department of the sea tunnel of the third company of CCCC First Harbor Bureau, also felt a great responsibility when he was pleased with the breakthrough of the tunnel.
The Dalian Bay Undersea Tunnel is a key project of the national strategy of "revitalizing the Northeast" and "building a strong transportation country", with a total length of 51 km, consisting of 18 immersed tubes and 1 final joint, with a design life of 100 years. After it is completed and opened to traffic, it will add a new north-south fast passage for Dalian City and promote the integration of both sides of Dalian Bay.
As the first cross-sea immersed tunnel in northern China, affected by high latitude and cold climate, especially in the severe cold construction environment in winter, the asphalt mixture is very prone to temperature segregation, which leads to the decline of the rutting resistance and cracking of the pavement, which seriously affects the quality of the pavement and brings pressure to the later maintenance. "This is a high-quality project with a 'warranty' of 100 years, and there must be no quality problems. Chief engineer Zhang Jun made improving asphalt concrete a top priority for the technical team.
To this end, starting from the material composition and mechanism, based on the durability research of asphalt mixture and the mechanism of pavement disease, through a wide range of raw material comparison and existing pavement disease research, the technical team proposed a long-life asphalt mixture mix design method, determined the raw materials suitable for the climatic characteristics and use conditions in Dalian, and finally designed high-performance asphalt surface courses such as warm mix flame retardant asphalt mixture, high modulus asphalt concrete structural layer and self-melting ice asphalt pavement. After testing, the new high-modulus concrete not only has strong ductility and fatigue resistance, but also can be used to solve the problems of insufficient rutting resistance of the surface layer and insufficient stiffness of the base layer under complex climatic conditions, which guarantees the pavement quality of the Dalian Bay submarine tunnel project from the design of raw materials and structural layer mix ratio, and provides an important theoretical basis for the construction of the project.
To cast the "permanent pavement" of the seabed, it is not enough to solve the asphalt concrete material, and the temperature of the asphalt concrete is also imperative. The average temperature in Dalian in winter is minus 3 degrees to 4 degrees, and the conventional asphalt concrete construction must ensure that the temperature is above 10 degrees, and the paving temperature must be above 160 degrees. To this end, the technical team controls the whole process from material storage, material transportation to unloading and material use, including the use of tarpaulin shed to close the material yard, the installation of foam board isolation in the carriage, the use of double-layer quilt on the roof, the preheating of the pavement temperature in advance, and the control of asphalt paving temperature, etc., which ultimately ensure the high-quality construction of asphalt pavement under low temperature conditions.
Thanks to the use of high-modulus asphalt concrete and new paving techniques, the construction quality of the Dalian Bay Submarine Tunnel pavement has been greatly improved. At present, the technical team is working to promote the new technology to similar projects, and strive to cast more "permanent pavement" in the immersed tunnel.
Statement: The copyright of this article belongs to the original author, if there is a mistake or infringement of your legitimate rights and interests, you can contact us by email, and we will deal with it in a timely manner. E-mail address: [email protected]