China News Service, Diqing, November 28 (Chen Qian, Gong Jianqiang) On the 27th, after 2,469 days and nights of fierce battles, a major breakthrough was made in the construction of the Lijiang-Shangri-La section of the Yunnan-Tibet Railway. The Haba Snow Mountain Tunnel constructed by China Railway 16th Bureau overcomes multiple technologies The problem is to achieve a flat conduction of 5774 meters.
At present, the remaining engineering of the main tunnel of the Haba Snow Mountain Tunnel, a major and difficult control project on the entire line, has entered the sprint stage.
The picture shows the construction site of the Haba Snow Mountain Tunnel from Lijiang to Shangri-La on the Yunnan-Tibet Railway.
Photo by Gong Jianqiang
The Haba Snow Mountain Tunnel is located in Diqing Tibetan Autonomous Prefecture, Yunnan Province, with a total length of 9,523 meters and a maximum buried depth of 1,155 meters. It is located in the northwestern Yunnan rift zone in the middle section of the Hengduan Mountains on the southeastern edge of the Qinghai-Tibet Plateau. The impact of activities is extremely prominent such as debris flow, landslide, large deformation of soft rock, collapse of fault fracture zone, water inrush and mud inrush, and karst. In particular, the maximum horizontal tectonic stress of fragmented basalt in this tunnel reached 29.4MPa, and the tunnel steel frame support The protection pressure (also known as the “second liner contact pressure”) exceeds 2MPa, which is the maximum value of Chinese railway tunnels. The deformation of the side wall of the tunnel during excavation is extremely serious, which is rare in the construction of Chinese tunnels.
The picture shows the construction site of the Haba Snow Mountain Tunnel from Lijiang to Shangri-La on the Yunnan-Tibet Railway.
Photo by Gong Jianqiang
“Generally, the steel frame support pressure of domestic tunnels is 0.5 MPa, and the steel frame support pressure of large deformation tunnels in other domestic projects is almost within 1 MPa. The Haba Snow Mountain Tunnel reached 2.4 MPa, which caused the entire tunnel to be like a spring. After the tunnel was excavated The surrounding rock is squeezed and deformed very strongly under the action of high ground stress. At most, a flat guide with a width of 8 meters is excavated, and it shrinks to only 1 meter.” said Li Guimin, deputy chief engineer of the Kunming Company of China Railway Second Institute.
As China's geological structure, neotectonic movement and in-situ stress environment cause the most special, complex and frequent large deformation of soft rock in tunnels, China Railway Group organized the China Railway Kunming Bureau Group Company and the participating parties to overcome the complex geological and landforms and the extreme harshness of the plateau. Climate conditions, on-site inspections, seminars and discussions on important and difficult projects of the Lixiang Railway, and 6 expert meetings have been organized to study countermeasures to overcome the problems, and the whole world will work together to tackle the global problem of high ground stress and large deformation.
Wang Xuebing, the head of the Lixiang Railway Section of the West Yunnan Railway Headquarters of China Railway Kunming Bureau Group Co., Ltd., said that the smooth opening of the Haba Snow Mountain Tunnel's horizontal guide has helped the rapid advancement of the remaining works in the main tunnel, relieved stress, ventilated smoke and drained water, and relieved the interior of the tunnel. Traffic pressure has played an extremely important role. At the same time, the lead leveling guide can release the ground stress in the surrounding rock in advance, which ensures the safe and rapid construction of the main tunnel in the later period, and also releases resources for the concentration of forces to overcome the remaining works of the main tunnel, and lays the foundation for the early opening to traffic. Solid foundation.
It is understood that the Lijiang-Shangri-La section of the Yunnan-Tibet Railway is about 140 kilometers long, and is an important part of China's mid- and long-term railway network planning.
After the completion and opening to traffic, the Diqing Tibetan Autonomous Prefecture in Yunnan Province will end the history of no railways. It is expected that it will arrive in 4 hours from Kunming to Shangri-La, which will greatly complement the shortcomings of the railway network and transportation services in the northwestern Yunnan region. And to promote the development of tourism economy in ethnic areas such as Tibetan, Yi, Naxi, Lisu, and Bai in northwestern Yunnan.
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