On the morning of July 29, good news came from the hinterland of the Qinling Mountains: the Shangshan TBM Tunnel, a key control project on the middle section of the Third West-East Gas Pipeline designed by the Pipeline Bureau Design Institute, was successfully holed through, marking a major breakthrough in China's capability to lay large-diameter pipelines under complex terrain conditions.

The Shangshan TBM Tunnel project is located in Shangluo City, Shaanxi Province. With a total length of 6,032.5 meters, it is the "throat" project for the middle section of the Third West-East Gas Pipeline crossing the Qinling Mountains, and is also China's first tunnel project to adopt single-shield TBM (tunnel boring machine) technology in the tunnel construction of 1,219 mm large-diameter long-distance transmission pipelines.

Construction of the project began on May 20, 2023. In the face of complex geological and hydrological conditions such as fault fracture zones and sudden water inrush, the Pipeline Design Institute established a dedicated design team and expert team to carry out research on the topic "Research on Key Technologies for Design and Construction of Oil and Gas Pipeline TBM Tunnels." Through calculation and research and development, a series of innovative technologies were developed, including the design of TBM tunnels crossing fault zones, seismic analysis of TBM segment rings, and tunnel waterproofing analysis.

In response to the project's characteristics of "small cross-section and long distance," the design team innovatively proposed a combined technology of "single-shield TBM + minimized main machine dimensions + hexagonal segment rings" in aspects such as preventing the cutterhead and shield body from getting stuck and the lifting and installation of small-diameter ultra-thick segments, ensuring precise and rapid advancement of tunnel construction in fault fracture zones.