Tongzi Tunnel (now renamed “Daluoshan Tunnel”) Project

Project Overview:

The Tongzi Tunnel (now renamed the “Daluoshan Tunnel”) is a key control project for the expansion of the Chongqing-Zunyi section of the Lanhai National Expressway within Guizhou Province. It is a separated, extra-long tunnel: the left tube measures 10,497 meters in length, while the right tube is 10,485 meters long, with a maximum burial depth of approximately 640 meters. The project broke ground in April 2018 and achieved full贯通 of both tubes on November 28, 2022. Situated in a complex geological environment, the tunnel features a combination of challenging engineering characteristics and difficulties, including “four longs” (extra-long tunnel, long-distance single-heading excavation, long-distance fault crossing, and long-distance reverse-gradient construction), “three highs” (high geostress, stringent environmental requirements, and high gas concentration), “two larges” (large water inflow and large cross-section), and “one tight” (tight construction schedule). As a result, the tunnel poses significant safety risks and presents extremely high construction challenges, making it a landmark, emblematic project in tunnel construction in China’s southwestern region.

Project Highlights:

Overcoming World-Class Geological Challenges: Successfully tackled the combined risks posed by high gas content (maximum pressure of 1.5 MPa), high geostress, highly pressurized and water-rich conditions (with maximum daily inflow reaching 192,000 cubic meters) and four major fault zones. Innovatively applied advanced equipment—including energy-concentrating hydraulic blasting, three-arm rock-drilling rigs, fully hydraulic self-propelled arch support bridges, and secondary lining trolleys—to achieve safe and efficient tunneling under extreme conditions, with a monthly advance rate exceeding 90 meters.
Fine-grained supervision throughout the entire process and innovation-driven technological advancement: The project supervision work is guided by the objectives of “stability, speed, and quality,” and has established a seamless, fine-grained management chain covering the entire project lifecycle. We have comprehensively implemented standardized construction practices, the first-prototype engineering system, real-name management for work teams, and blacklist management. We have extensively applied BIM technology for site planning, construction simulation, and visualized briefing sessions, and have built an information-based management platform that integrates systems such as personnel positioning, smart access control, gas monitoring, and video surveillance, thereby achieving dynamic and intelligent control over the construction process.
A Model of Green Construction and Ecological Protection: In response to the stringent environmental requirements for tunnel construction through water source protection zones, we have innovatively developed a comprehensive tunnel drainage purification system featuring “primary sedimentation within the tunnel + multi-stage sedimentation at the tunnel portal + polyaluminum chloride treatment + three-stage sedimentation in the river channel.” This system ensures that discharged water meets regulatory standards, effectively safeguards the regional ecological environment, and embodies the concept of green construction.
Quality Engineering and Micro-Innovation Practices: With the goal of building “quality engineering,” we have carried out numerous micro-innovations in construction processes. For example, we’ve adopted cross-shaped positioning for hot-melt gaskets, magnetic welding guns for welding waterproof boards, steel-mold end-caps for securing waterstop strips, and self-propelled hydraulic formwork for cable trenches. These innovations have significantly improved the qualification rate of the secondary lining’s rebar protective layer (reaching over 85%), enhanced waterproofing quality, and optimized the appearance of concrete structures, systematically eliminating common quality defects.

Honored Achievements:

2024 Guizhou Province High-Quality Project (Huangguoshu Cup).
The project has developed a comprehensive technical system for the integrated treatment of complex geological conditions in long tunnels, a standardized management system for safe production, and green construction methods. The numerous minor innovative processes, summarized applications of four new technologies, and management experiences generated throughout the project possess high potential for wider adoption and application.

Project Showcase: