Dalin railway barley ground tunnel overcomes the rare problem of "egg soup" and "water curtain hole"

Dali, CCTV, Jan. 7 (reporter Li Jianfei, correspondent Niu Rongjian) at 6:36 a.m. on Jan. 7, after four years of hard construction by railway builders, the number one problem in the construction of key projects of West China railway network and the important infrastructure of interconnection with neighboring countries - the first problem in the construction of new Dali Lincang railway, the control project of the whole line and the construction of the fifth company of China Railway First Bureau The 11.65 km long tunnel, barley land tunnel, has been safely and smoothly connected. The

barley land tunnel is located in Dali Prefecture, Yunnan Province, which belongs to the special red bed geological area in western Yunnan. Since the commencement of construction on December 28, 2015, the construction personnel of No. 5 company of China Railway First Bureau have been entangled in the same construction environment as "water curtain hole" and "egg soup". Xu Haijian, executive deputy manager of Dalin Railway Project Department of

first railway bureau, said: "the surrounding rock of the tunnel is seriously broken and has no cementation capacity, so it is easy to slide one after another and lose stability. The surrounding rock has strong water permeability and no isolation ability to groundwater. There is no water during excavation, but after a period of time, the fissure water seeps out, softens the surrounding rock and forms a weak sliding surface. During the construction process, the surrounding rock of the tunnel is broken and changed rapidly, with poor self stability, water absorption softening and water loss shrinkage, which can screw the steel structure with a thick bowl mouth into a twist shape. There is a large amount of water inflow in the tunnel, sometimes it needs 24 hours of continuous drainage. It is very difficult to advance the construction. "

in view of the construction difficulties, under the organization of the construction headquarters of the West Yunnan Railway, the participating units such as China Railway First Bureau and China Railway Eryuan have constantly adopted new measures and optimized new construction methods. Li Guangjun, deputy chief engineer of Dalin railway project of China Railway No.1 Engineering Group Co., Ltd., said: "the project adopts the measures of" early prediction, water control first, short footage, weak blasting, strong support, tight sealing and frequent measurement ", and 4 inclined shafts have been opened up, which have been increased to 10 tunnel openings to be excavated in sections. Especially for the train running 1000 meters, it is necessary to raise the limit slope of 8 floors - 24 / 1000, the maximum excavation section is 18 meters and the difficulty of facing 2200 cubic meters of water every day, which exceeds two standard swimming pools. The workers adopt the method of centralized drainage of accumulated water on the reverse slope of the four-stage pump station, steadily implement the fast construction method, optimize the construction process on the premise of ensuring the quality, and work in shifts for 24 hours, so as to realize the safe and smooth connection of the tunnel. " A 6031 a 6031 newly built Dali Lincang railway starts from Dali station of Dali Railway in the north, passes Weishan County of Dali Prefecture, crosses Lancang River and enters Lincang City, passes Yunxian County and reaches Linxiang District of Lincang City, with a total length of 202.095 kilometers. It is a class I national passenger and freight railway. Bridges and tunnels account for 87.25% of the total length of the railway, which is one of the most difficult projects in Yunnan Province. After the completion and opening to traffic, it will play a positive role in improving the Western Railway Network, improving the regional comprehensive transportation system in central and Western Yunnan, developing the local economy along the line, and highlighting the infrastructure and connectivity between Yunnan and surrounding countries. Up to now, 83% of the railway bridges have been completed, 84.2% of the tunnels have been completed, and the "four electricity" system and station building construction of the whole line have also entered the substantial and comprehensive construction stage.