China's first long-distance pipe jacking water supply tunnel across the Han River has been completed

Recently, with the "Hanjiang" pipe jacking machine slowly through the door of the receiving well, the crossing pipe jacking section of the Danjiangkou urban water supply capacity Improvement Project constructed by the second Aviation Bureau of China Communications was successfully received, marking the successful completion of the first long-distance pipe jacking water supply tunnel across the Han River in China.

The project is located in the urban area of Danjiangkou City, Hubei Province. It is a livelihood project to meet the water demand of Danjiangkou City's long-term planning population and improve the quality of water for residents' living and production. The construction of the project involves the left and right sides of Danjiangkou City, starting from the second water plant and finally the first water plant, the total length of the new pipeline is about 10 kilometers. Among them, the total length of the pipe-jacking water supply tunnel in the crossing section is about 718 meters, and the outer diameter of the tunnel is 2.4 meters, which is the most difficult and risky section in the project.

This section of pipe jacking passes through the whole section of rock layer, and crosses the interface of strongly weathered and moderately weathered rock layers for many times. The geological conditions are complicated, and the construction is difficult. In order to ensure the applicability and reliability of the pipe jacking equipment, the project department adopts a new modified mud-water balanced rock pipe jacking machine with a length of 5.2 meters and an excavation diameter of 2.46 meters for construction. The cutter head of the pipe jacking machine is designed for wear-resistant reinforcement, equipped with 16 hobs embedded with high-strength alloy teeth and 24 scrapers to ensure that the rock and soil mass can be effectively broken. Improve the wear resistance of cutter head.

In the process of pipe jacking construction, due to the development of rock cracks, high water yield and high pressure, it has a great impact on the grouting resistance reduction and mud water treatment. The technical team of the project department has put forward the tunnel door sealing reinforcement measures to solve the difficulties, and developed the pipe jacking thixatic mud suitable for the fractured rock formation, which effectively reduces the water yield and jacking force. In order to prevent the pipe joint structure damage during the long-distance rock pipe jacking construction, the project site carried out structural safety monitoring, based on the test data, timely adjustment of jacking parameters to ensure the safety of the structure. In addition, the technical team of the project department has also overcome difficulties such as tool wear assessment and underwater reception of pipe jacking in high water pressure formation to ensure smooth reception of pipe jacking.

After the completion of the project, it will significantly improve the urban water supply capacity, water supply safety and water supply quality of Danjiangkou City, ensure residents' living and production water, and further promote the high-quality economic and social development of Danjiangkou City.