On the 25th, with the successful completion of the last auxiliary gallery, No. 3 inclined shaft of the Dangshun Tunnel, the Dangshun Tunnel on the Xining-Chengdu Railway in Qinghai Province entered main tunnel construction across the entire line.

The picture shows No. 3 inclined shaft of the Dangshun Tunnel. Photo by Zhang Tianfu

The Xining-Chengdu Railway, an important component of the Lanzhou (Xining)-Guangzhou corridor of the national "Eight Vertical and Eight Horizontal" high-speed rail network, is located in the border area of Qinghai, Gansu and Sichuan provinces.

It is reported that the Dangshun Tunnel has a total length of 13.492 kilometers and is situated in the transitional zone between the Qinghai-Tibet Plateau and the Loess Plateau. The tunnel portal is located on the right bank of the Longwu River in Qinghai, a first-level tributary of the Yellow River. The area features deep valleys, well-developed vertical joints, protruding rock faces on cliffs with dangerous rocks on the verge of falling, and well-developed adverse geological phenomena such as collapses and landslides.

No. 3 inclined shaft of the Dangshun Tunnel has a total length of 1,545 meters, including 1,445 meters of Grade IV surrounding rock and 100 meters of Grade V surrounding rock. It was completed by the builders over 309 days, with an average monthly advance of 150 meters and a maximum monthly advance of 204 meters, completing 82 days ahead of the planned schedule.

On that day, with the successful completion of the last auxiliary gallery, No. 3 inclined shaft of the Dangshun Tunnel, it also meant that all five auxiliary galleries (totaling 4,397 meters) within Section 10 of the Xining-Chengdu Railway, constructed by CCCC ** Harbor Engineering Co., Ltd. and built under the supervision of Lanxin Railway Ganqing Co., Ltd., had successfully completed their construction tasks.

CCCC ** Harbor Engineering Co., Ltd. undertakes the construction task of Section 10 of the Xining-Chengdu Railway. The section is located in Tongren City and Jianzha County of Huangnan Tibetan Autonomous Prefecture, Qinghai Province, with a main line length of approximately 19.6 kilometers. The main works include 1.5 tunnels, 3 bridges and 2 subgrade sections, with tunnel construction accounting for 96.3%.

In addition to the Dangshun Tunnel, CCCC ** Harbor Engineering Co., Ltd. also undertakes the 5,343-meter exit section of the Longwu Tunnel on the Xining-Chengdu Railway. The Longwu Tunnel is located in Tongren City and Jianzha County of Huangnan Tibetan Autonomous Prefecture, Qinghai Province. The entrance is located on a mountain slope northeast of Kajia Village, Bao'an Town, Tongren City, and the exit is located southeast of Gulangdi Village, Dangshun Township, Jianzha County, on the right bank of the Longwu River. The maximum buried depth of the tunnel is approximately 720 meters.

Zhang Yiming, project manager of Section 10 of the Xining-Chengdu Railway, introduced that the tunnels within the section have complex geology, great construction difficulty and a tight schedule. The completion of the auxiliary galleries 82 days ahead of schedule greatly alleviated the construction pressure on the main tunnel. At the same time, technologies such as 3D visualization, simulation and information integration were actively introduced, and a BIM engineering digital platform was built on this basis. Meanwhile, the technological methods of "advance pipe roofing, strict grouting, short excavation, strong support, rapid sealing and frequent measurement" were strictly followed, and processes and tooling were vigorously improved to accelerate construction progress with all efforts.