Media Focus | A Bridge was Launched at a height of 58 meters! The Detuo Special Bridge on the Luzhou-Shijiazhuang Expressway has achieved double-span connection

On March 31st, the Detuo Special Bridge of the Luzhou-Shijiazhuang Expressway, constructed by the Jiaojian Group, achieved double-span connection, marking the successful completion of the main structure of the bridge and laying a solid foundation for the full connection of the Luzhou-Shijiazhuang Expressway.

The Detuo Special Bridge is located in Detuo Town, Luding County, Ganzi Prefecture, spanning the Dadu River with a total length of approximately 1,518.5 meters. The area where it is situated has an extremely high seismic intensity, and various geological disasters such as mountain floods, mudslides, landslides, and collapses occur frequently. The maximum wind force monitored in the high-altitude operation construction area reaches above level 8, making the construction extremely difficult. The main bridge adopts a domestic first form of "concrete-filled steel tube truss piers + double-sided steel box composite beams" with a combination of 5 spans of 70 meters and 4 spans of 72 meters. The unidirectional continuous jacking length reaches 678 meters, which is the longest single-span jacking length for similar Bridges in mountainous areas.

As the Dadu River does not have the conditions for water transportation, the construction team adopted the step-by-step synchronous jacking technology. With the help of 24 sets of fully automatic CNC three-dimensional jacks and sensors, they monitored the stress and displacement changes during the jacking process in real time. At a height of about 20 floors, they pushed the 638-meter-long and 7,600-ton steel box girder into position with millimeter-level precision. Overcoming the installation difficulties of large-span and large-tonnage steel box girders in high-intensity areas and limited working Spaces, it achieved "zero error" in positioning and set a new record for the length of Bridges under jacking construction in high-intensity earthquake-stricken areas.

Up to now, the project has completed one scientific research project, obtained three utility model patents, and innovated multiple construction methods such as "A Double Casing Structure for Deep-water Pile Foundations in Complex Geological Environments". The application of various techniques in similar mountainous bridge construction has reached leading standards.

The Detuo Special Bridge is a key "two tunnels and one bridge" demonstration project of the Luzhou-Shijiazhuang Expressway, shouldering the responsibility of promoting the development of ethnic minority areas. After the completion and opening to traffic of the Luzhou-Shixian Expressway, the driving time from Luding to Shixian will be shortened from 3 hours to 1 hour. This "Red Road" will significantly improve the travel conditions in ethnic minority areas, accelerate the development of tourism resources such as Hailuogou Scenic Area, and promote rural revitalization and the rise of characteristic industries. Meanwhile, the high-standard seismic design of the bridge will significantly enhance the regional disaster resistance capacity, provide a solid guarantee for economic development, and help Ganzi Tibetan Autonomous Prefecture build a strategic support point for the "second passage to Tibet".

Extended reading

The Luding to Shimian Expressway is an important part of the "Sichuan Province Expressway Network Plan (2019-2035)". It is 96.51 kilometers long and is built to the standard of a two-way four-lane expressway with a designed speed of 80 kilometers per hour. The Detuo Special Bridge is one of the key structures of the "two tunnels and one bridge" demonstration project of the Luzhou-Shijiazhuang Expressway. The project is located in the severely affected area of the "9·5" Luding earthquake. The bridge is close to the ancient landslide body, with an earthquake intensity of 8 degrees, and the geological conditions are extremely complex.

The Jiaojian Group has innovatively adopted the first complete set of "Concrete-filled steel tube truss piers + prestressed steel box composite beams" system in China, which features extremely strong load-bearing capacity, seismic performance and economic efficiency.

The Jiaojian Group has carried out technological innovation based on the actual construction situation. It has invited technical teams from universities to the site for investigation and research many times, and monitored the stress, deformation and displacement throughout the jacking process. As a result, the installation accuracy has been significantly improved, effectively ensuring the safety of construction operations.

In response to the difficulties of deep water pile foundation hole formation, such as high difficulty, poor precision and limited working space, the Transportation Construction Group innovatively adopted the double casing hole formation technology. During the construction process, high support platforms were set up on the piers of the approach bridge, effectively solving problems such as mud leakage and the lack of a jacking platform.

The Jiaojian Group, adhering to the concepts of modular manufacturing and prefabricated construction, combined with BIM technology to optimize the design of segment connections, completed the installation of a single span in just 20 days, shortening the construction period of the entire bridge by six months. Through intelligent manufacturing in the factory and precise control of on-site welding sequence, the entire process of pre-assembly, installation and welding is controlled within the millimeter level in an environmentally friendly prefabricated construction, significantly reducing costs and on-site construction pollution, improving the efficiency of green construction of Bridges in complex terrain, and accelerating the green construction of Bridges in mountainous areas in China.

By the time of the double-span breakthrough of the Detuo Special Bridge, the completion rate of the roadbed, Bridges, culverts and tunnels of the Luzhou-Shijiazhuang Expressway has reached over 90%. As a "Tibetan-Yi corridor" connecting the Ya 'an-Kangding and Ya 'an-Xichang expressways, the completion of the Detuo Special Bridge will reduce the driving time from Luding to Shimian from three hours to one hour.