China News Service, Maoxian County, Sichuan, April 26 (Reporter Liu Zhongjun) On the morning of the 26th, as the surrounding rock of the last half-meter arch was successfully drilled, thousands of builders after 8 years of hard work, became the (capital) Lanzhou ) Railway (hereinafter referred to as: Chenglan Railway) Liutongzhai Tunnel was successfully completed, which laid a solid foundation for the entire line of the railway.
The Chengdu-Lanzhou railway is an important part of the “Languang” corridor of the national “eight vertical and eight horizontal” high-speed railway planning network. It is designed to have a speed of 200 kilometers per hour. It is another railway built on a plateau with an altitude of 3000 meters after the Qinghai-Tibet Railway. "Heavenly Road".
Overlooking the Cheng-Lan railway bridge that crosses the mountains.
(Aerial image) Photo by Liu Zhongjun
The Liutongzhai Tunnel is located in Weimen Town and Goukou Town, Mao County, Sichuan. It was designed by China Railway Second Institute and constructed by China Railway 12th Bureau Group Co., Ltd. The total length of the tunnel is 16.312 kilometers, the maximum buried depth of the tunnel is 1410 meters, and the buried depth is more than 500 sections. Nearly 11 kilometers.
"The Liutongzhai Tunnel is one of the most severely deformed soft rock tunnels on the Chenglan Railway. In order to reduce construction and operation risks, the design adopts a dual-hole sub-repair plan." said Zhou Yuefeng, the project manager of the Chenglan Railway of China Railway Second Institute.
“The lithology of the surrounding rock of the whole tunnel is extremely weak and broken phyllite and carbonaceous phyllite, of which the surrounding rocks of grade IV and V account for more than 85%. The requirements for construction technology are high and the construction is extremely difficult.” China Railway According to Yang Wei, Chief Engineer of Chenglan Railway Project of the 12th Bureau, Liutongzhai Tunnel's geological and landforms are very complex, with the remarkable characteristics of "four poles and three heights".
Four extremes: extremely strong terrain cutting, extremely complex and active structural conditions, extremely weak and broken lithological conditions, and extremely significant effects of the Wenchuan earthquake. The three highs are: high crustal stress, high seismic intensity, and high risk of geological disasters.
The Liutongzhai Tunnel is located at the composite site of the north-eastern section of the "S"-shaped structural belt from Xuecheng to Wolong and the eastern section of the Shidaguan arc-shaped structural belt, and the southern section of the Minjiang fault zone.
Affected by regional structure, faults and folds develop.
The tunnel generally traverses a compound fold structure composed of the Yongding inverted turning oblique, the Huoshaopo syncline and the Huoshaopo inverted anticline, and the middle is cut off by the Daqishan Fault.
The Liutongzhai Tunnel on the Chenglan Railway was penetrated at the site.
Photo by Liu Zhongjun
Xiao Xialin, deputy commander of the Chenglan headquarters of Chenglan Railway Co., Ltd., said that since the start of construction of the Liutongzhai Tunnel in 2013, it has overcome the frequent earthquakes and weak lithology of the Minjiang fault zone. The in-situ stress is as high as 37Mpa and serious large deformations have occurred in the tunnel. , And the group hole effect is obvious and other geological difficulties
Through scientific research, the construction adopts high pier foundation and triple span super large open tunnel to protect the bridge, platform, and station carriage room together, and adopts innovative solutions such as dam-shaped hollow foundation and external hanging form trolley to solve the weak foundation and existing The problem of constructing large open tunnels under bridges and other conditions. In terms of controlling large deformations, active control technology was adopted, and a series of large deformation treatment technologies such as the combination of long and short bolts and the construction method of large section excavation and fast closing were proposed, which solved nearly 5 kilometers. Large deformation of soft rock.
It is understood that the completion of the Chengdu-Lanzhou Railway will end the history of no railways in northwestern Sichuan. It will jointly build a trunk railway channel connecting the northwest, southwest and south China coasts with the existing Baoji-Chengdu Railway, Lanzhou-Chongqing Railway, Sichuan-Tibet Railway, and Chengdu-Xi’an Railway. .
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