On March 25th, it was reported on the official Weibo account of "China Railway Construction" that the Yawan High-Gas Tunnel, constructed by the China Railway 17th Bureau Group, has achieved a cumulative breakthrough of over 3000 meters. This significant milestone lays a solid foundation for the early completion of the tunnel.
The Yawan Tunnel, with a total length of 8488 meters, is often referred to as the "Mount Everest lying flat in the engineering world," indicating its immense construction difficulty. The high-gas section of the tunnel spans 2650 meters, while the low-gas section stretches over 5310 meters, with rock formations mainly composed of shale, mudstone, and sandstone.
During the construction process, multiple challenges such as gas outbursts, rock fracturing, shallow burial, and crossing reservoirs were encountered. Consequently, the tunnel was identified as a critical and difficult project along the entire Chongqing-Wanzhou high-speed railway.
In order to enhance excavation efficiency and shorten the construction period, the tunnel construction team innovatively adopted the "two main tunnels + two inclined shafts" auxiliary tunneling method. With this approach, two inclined shafts (with the first one measuring 720 meters and the second one measuring 1052 meters) were utilized to open up four auxiliary working faces for the left and right main tunnels, dividing them into multiple sections. This formation enabled the simultaneous excavation of six working faces within the main tunnels, presenting a spectacular scene of comprehensive excavation.
The "short tunneling and long support" strategy effectively alleviates the ventilation and material transportation pressure during the construction of service tunnels and main tunnels, greatly improving tunnel construction efficiency. Since tunnel excavation began, the monthly advance rate has remained stable at over 90 meters, smoothly completing various milestone tasks and achieving significant phased results.
As a vital part of the national "Eight Vertical and Eight Horizontal" high-speed railway main channel, the Chongqing-Wanzhou high-speed railway will further improve the rapid railway network in southwest China, providing great convenience for people along the route.
