Lanzhou-Haikou National Expressway, Chongqing-Zunyi Section (Guizhou Province) Expansion Project—Dalou Mountain Tunnel (formerly known as Tongzi Tunnel)

Project Overview:

The Daloushan Tunnel (formerly known as the Tongzi Tunnel) is a key control project for the expansion of the Chongqing-Zunyi section (in Guizhou Province) of the Lanzhou-Haikou National Expressway. The tunnel’s single-bore length exceeds 10,000 meters (10,497 m for the left bore and 10,485 m for the right bore). It is not only Guizhou Province’s first highway tunnel exceeding 10,000 meters in length, but also the country’s first bidirectional six-lane mountainous expressway tunnel designed for a maximum speed of 100 km/h and with a single-bore length surpassing 10,000 meters. The project’s total estimated investment was approximately 1.81 billion yuan, and it was completed and opened to traffic in September 2023. In response to the world-class challenges encountered during tunnel construction—such as “two high and two large” (high geostress, high gas content, large water inflow, large cross-section), “three sudden events” (sudden water bursts, sudden mudflows, gas outbursts), and “four longs” (long tunnel mileage, long single-heading excavation distance, long ventilation distance, and long reverse-slope drainage distance)—the participating construction units jointly undertook major specialized technological research and successfully overcame these difficulties. The Daloushan Tunnel has now become a model project for the construction of ultra-long, large-span highway tunnels under complex geological conditions. Its technological innovations and engineering practices have attracted widespread attention within the industry. CCTV2 even dedicated a special report to this tunnel, and the 2024 Academic Annual Conference of the Tunnel Engineering Branch of the China Highway Society was held in Zunyi precisely with this tunnel as its focal point, marking its status as a national demonstration project and industry benchmark for long-tunnel technology.

Project Highlights:

We have developed a sealing support technology using basalt fiber sprayed concrete, which employs a spraying process to rapidly construct a support system that combines both sealing performance and toughness. This technology effectively addresses the challenge of gas sealing in large-section, extra-long tunnels. The related research results have been incorporated into the group standard titled "Construction Code for Basalt Fiber Sprayed Concrete in Highway Tunnels."
Integrating a multidimensional, synergistic technological system encompassing “high-precision surface deep-hole exploration—acoustic-vibration-enhanced gas drainage—advanced drainage via small pilot tunnels—CO2 fracturing for enhanced permeability,” we have overcome key technical bottlenecks in the geologic precision exploration of deeply buried, ultra-long, and large-span tunnels crossing high-gas coal-bearing strata, including challenges such as difficult geological detection, low coal seam permeability, and prolonged gas drainage cycles.
The innovative inclined shaft-horizontal tunnel intelligent ventilation system adopts a combined ventilation mode featuring relay pressurization and roadway-based ventilation, enabling safe and simultaneous construction across multiple working faces in ultra-long gas tunnels spanning tens of kilometers. Moreover, by employing a combined ventilation design—featuring long, unidirectional slopes with “multiple inclined shafts plus a single tunnel”—the system reduces operational ventilation energy consumption by 12%, delivering remarkable energy-saving results.
Addressing the challenging issue of disaster-causing interactions among “anticlinal structures—complex geostress fields—free gas pockets” in non-coal strata, we have developed a localized, directional pressure-relief technology for gas drainage and outburst prevention, achieving highly effective control and filling a gap in engineering practice for treating gas outbursts in tunnels excavated through carbonaceous mudstone formations.
Develop design methods and structural systems for tunnel maintenance-oriented drainage, significantly enhancing the long-term effectiveness of tunnel waterproofing and drainage. Research and develop a water supply system that utilizes underground groundwater in tunnels as an in-tunnel fire-fighting water source, thereby addressing the challenges of fire-fighting water supply in ultra-long tunnels and achieving green, circular utilization of underground water resources.

Honored Achievements:

First Prize, 2025 China Highway Survey and Design Association Highway Transportation Outstanding Design Award
First Prize of the 2025 Guizhou Province Civil and Architectural Engineering Technology Innovation Award;
2024 Guizhou Province High-Quality Engineering Award;
In 2018, ranked second in the BIM application category for large bridges and tunnels in the 9th “Innovation Cup” Building Information Modeling (BIM) Application Competition.
Holds 22 patents and has published 15 papers;

Project Showcase: