The Xinhua tunnel of Yunnan Dali Lincang railway was successfully opened on the 15th, marking a major breakthrough in the construction of key and difficult control projects along the line. This is also the first 10000 meter long railway tunnel built in high earthquake intensity areas and longitudinal valley areas of Hengduan Mountains in China. Its accumulated rich construction experience will provide technical reference for the construction of Sichuan Tibet and Yunnan Tibet railways.
Xinhua tunnel, with a total length of 12.3km, is a key and difficult control project of Dalin railway of China Myanmar International Corridor. It is located in Nanjian County, Dali Prefecture, Yunnan Province and belongs to the hinterland of Hengduan Mountains.
Due to the compression of the Eurasian plate and the Indian Ocean plate, huge folded Hengduan Mountains are formed. The reporter saw at the periphery of the tunnel that the mountains are vertical and horizontal, the terrain is steep, the river valley is deep, and the geological structure is extremely complex. Therefore, Xinhua tunnel belongs to national class I high-risk tunnel.
During the construction, the West Yunnan Railway Construction Headquarters of China Railway Kunming bureau group organized participants to overcome many problems, such as high water pressure, high heat, high earthquake intensity, high stress and so on. According to Zhao fan, manager of the third work area of Dalin Railway Project Department of China Railway 12th Bureau, there is a large reservoir with a water storage of 15 billion cubic meters above the tunnel. The whole construction operation is basically carried out more than 100 meters below the water level of the reservoir, which is equivalent to withstanding the huge pressure of 15 billion cubic meters of water. The surrounding rock of the tunnel is crushed, with developed fissures and serious water permeability. The maximum daily water inflow is 70000 m3.
At the same time, the tunnel is located in the high seismic intensity area, the intensity level reaches 8 degrees, and the earthquake damage is great. The maximum buried depth of the tunnel is 1100 meters, and the surrounding rock bears huge stress. The steel frame, concrete and other materials used in the tunnel have high requirements for compression resistance, corrosion resistance and strength.
Luo Yunfei, manager of the large temporary cooperation project Department of creec, said: "the tunnel passes through three faults in total. During the construction, in combination with the advanced geological prediction and monitoring measurement data, the surrounding rock level is adjusted in time and the support parameters are optimized. The measures of prevention, drainage and blocking are taken to solve the problems of large deformation, groundwater development and harmful gas according to local conditions."
Dalin railway, with a total length of 202 km, is an important part of the China Myanmar International Corridor. Its design speed is 160 km / h. After completion and opening to traffic, it is of great significance to boost the interconnection between Southwest China and surrounding countries.