Recently, as the cutterhead of the "Taishan" shield machine broke through and successfully reached the receiving shaft, the east-line tunnel of the Jinan Yellow River Jiluo Road North Extension Project—invested in and constructed by Jinan Urban Construction Group and built by China Railway 14th Bureau—was successfully holed through. This marks another important milestone following the breakthrough of the west-line tunnel on January 6, signifying that China's largest-diameter combined road-rail shield tunnel has safely and smoothly crossed a large urban reservoir. The Jinan Start-up Zone for the Conversion of Old and New Growth Drivers has gained a new major transportation artery, laying a solid foundation for the completion and opening of the entire line.

Known as the "First Tunnel of the Ten-Thousand-Li Yellow River," the Jinan Yellow River Jiluo Road Tunnel is a landmark project for Jinan's development strategy of "carrying the river northward." To meet development needs, construction of the Jiluo Road Yellow River North Extension Project began simultaneously upon the tunnel's completion and opening. The project starts at the open-cut section of the Jiluo Road Tunnel and ends at National Highway 308, with a total route length of 4,383 meters, of which the shield-driven section is 2,045 meters. The segment outer diameter is 15.2 meters, and the shield machine cutterhead excavation diameter is 15.76 meters. It is designed as a double-tube, dual-direction, six-lane structure: the upper level carries a three-lane highway, while the lower level accommodates rail transit lines. It is currently the largest-diameter combined road-rail tunnel under construction in China.

According to Du Changyan, project manager of the China Railway 14th Bureau's Yellow River North Extension Project, the tunnel passes beneath the Hanji Railway and the Queshan Reservoir. The project is characterized by deep foundation pits, shallow cover, large diameter, long distance, high risk, and stringent environmental protection requirements. The project team repeatedly invited academicians including Qian Qihu and Li Shucai to conduct reviews and optimize the construction plan. Building on the experience gained from the Jiluo Road Yellow River Tunnel, the team carried out targeted upgrades and optimizations to the cutterheads and flushing systems of the two shield machines "Yellow River" and "Taishan," enabling them to more effectively adapt to the silty clay strata unique to the Yellow River basin. Efficiency improved by 20%, and the completed tunnel is watertight with no seepage, solid within and beautiful without. While protecting the reservoir and its surrounding environment, the team achieved steady progress in construction, with a maximum daily advance of 18 meters and a maximum monthly advance of 332 meters.

This is the first time a super-large-diameter shield tunnel has crossed a medium-to-large above-ground reservoir over a long distance, involving numerous controlling factors and high environmental protection requirements. To overcome the challenge of crossing the Queshan Reservoir over a long distance, Jinan Urban Construction Group organized expert review meetings on the construction plan. The project department established the "Wang Chao Innovation Studio" and, together with Shandong University and Beijing Jiaotong University, conducted research on the topic of "Long-Distance Crossing of a Large Reservoir by a Super-Large-Diameter Slurry Shield." They pioneered a "waterproof curtain" to place a "protective cover" over the reservoir bottom, effectively ensuring soil stability. Meanwhile, water quality monitoring frequency was increased to ensure zero pollution, zero discharge, and zero leakage during the tunneling process. Relying on the project, the team has summarized and mastered a complete set of technologies for super-large-diameter shield tunneling through medium-to-large reservoirs, producing six papers and eight invention patents.

As a landmark project of Jinan's new round of planning and development and the conversion of old and new growth drivers, the Jinan Yellow River Jiluo Road North Extension Project is an important link connecting Jinan's main urban area with the Start-up Zone for the Conversion of Old and New Growth Drivers. It is also a concrete manifestation of implementing three major strategic deployments: the national strategy for Yellow River ecological protection and high-quality development, and the provincial Party Committee and provincial government's "Strong Provincial Capital Strategy." Upon completion, the project will further optimize the transportation layout on both banks of the Yellow River and is of great significance for advancing Jinan's "river-carrying development" strategy, expanding urban space, guiding urban development, and improving the urban road and public transportation systems.