China-Laos Railway domestic tunnel finally opened. How many days did it last?

On the morning of September 13, after 1200 days' hard work 1543 days, the domestic tunnels in China-Laos Railway were finally completed.

So far, 97.5% of the domestic tunnel projects in China-Laos Railway have been completed, laying the foundation for the opening of the whole line. Friendship Tunnel is located on the border between China and Laos, and it is a cross-border tunnel connecting China and Laos. A tunnel is the only cross-border tunnel connecting the two countries. The total length of the tunnel is 9.59 kilometers, including 7. 17 kilometers in China and 2.42 kilometers in Laos. The design speed is 160. In order to reflect the traditional friendship between China and Laos, the tunnel was named Friendship Tunnel. The China section of Friendship Tunnel is located in Honing Economic Development Zone, Xishuangbanna, Yunnan Province, and the foreign section is located in the northernmost virgin forest zone of Laos, where the local salt content exceeds 80%. The geology of the tunnel is complex, and the grade I surrounding rock accounts for 75% and 25% respectively. The surrounding rock is mainly mudstone and sandstone, with rock salt and gypsum. The rock mass is broken, softens when it meets water, and has poor self-stabilization ability. It is a Class I high-risk tunnel.

Mudstone plus sandstone is called weak surrounding rock in engineering, which is easy to slide when looking at water like soil for planting crops, and it is easy to slide and deform during construction, which has high safety risk. Luo Hengfu, director of Yumeo Railway Project of China Railway Second Bureau, adopted soft rock construction project. Short footage, fast construction and fast sealing? Based on the short-segment construction method, it reduces the exposure time of surrounding rock, avoids collapse and deformation, ensures the immediate closure of surrounding rock, and ensures the rapid construction and deformation of tunnel soft rock.

Tunnels are all in salt rock erosion environment, which is very corrosive to tunnel structure and rare at home and abroad. Salt rock is a stone formed by salt crystallization. Its strength is low, and when it meets water, it will become salt water, which is extremely corrosive to steel bars when it invades concrete structures. In order to ensure the engineering quality, from June 20 16, Yunnan Railway Construction Command of Kunming Bureau Group of China Railway organized China Railway Second Bureau, Academy of Iron Sciences and other institutions to carry out technical research. After 16 months' efforts, the requirements of concrete solid strength index were met in September 20 17. After expert review, this technology has reached the advanced level in the world. Luo Hengfu said that all tunnels are made of C50 and C45 high-strength and high-corrosion resistant concrete to resist the erosion of concrete by salt rock and gypsum. The steel bar is made of epoxy resin, which is different from the usual steel bar, just like wearing it to protect the steel bar from salt water? Protective clothing? .

During the construction, some areas encountered high salt road sections. In order to overcome this rare geology, the construction party invited experts in tunnel, geology and materials to the site for investigation and discussion to determine? Water injection and water plugging, all-inclusive waterproofing, circular multi-layer structure, strengthening material corrosion protection? Design scheme? According to the design scheme, we adopted a variety of special equipment for salt rock tunnel, such as 65-meter-long trestle and fully enclosed anti-floating formwork, which ensured the quality, safety and progress of the project to the maximum extent from the aspects of tooling and technology. ? Wang Hui, chief engineer of the project department, said.

Pan Fuping, 50, has been engaged in railway tunnel engineering for 27 years. He is the vice president of Yumo Railway Project Department of China Railway Second Bureau and the organizer of the domestic section of Friendship Tunnel. His apprentice Bai Xiao is the production organization of the overseas section of Friendship Tunnel. The distance between the two construction sites is less than 10 km, but due to the tight construction period and heavy tasks, it is difficult for them to meet the international standards. The surrounding rocks of the domestic and overseas sections of Friendship Tunnel are similar, but different. Two teachers and students talk on the phone every day. Greet each other and exchange work experience and construction technology. Both teachers and students are working hard. Compare progress with quality, you chase after me! ? I have an appointment with Xiaoyou. When the tunnel runs through, we hug once in the tunnel and take a group of shadows. As a result, we spent 1543 days and nights together in a tunnel. Pan Fuping said, I am very happy that the tunnel was opened today, but due to the epidemic, our agreement can only be cancelled temporarily. There are good friends in the sea, no matter far or near, our hearts are beating together.

Subgrade and bridge in China-Laos Railway domestic section have been basically completed, and other projects such as pavement and station building are being comprehensively promoted according to the construction plan. ? I want to take a train to China to see the Great Wall? I want to go to China by train to see the Great Wall. "The dream of Lao employees at the construction site of the overseas section of Friendship Tunnel. Tong orange is responsible for steel binding at the construction site. He has only seen trains on TV and online since he was a child, but he has never really experienced them. Fortunately, he participated in the construction of China-Laos Railway. He said he was excited. Like oranges, many Laos locals from the Friendship Tunnel Project have also become famous. They want to see how the railway was built and look forward to going far away by train one day.

The completion of the Friendship Tunnel marks another solid step in the construction of China-Laos Railway. Liu Juncheng, deputy commander of Yunnan Railway Construction Command of Kunming Bureau Group, said that at present, there are 93 tunnels running through 80 tunnels in Yumeo section of China-Laos Railway, and the remaining 13 tunnels are full length 10 km. The tunnel project has completed 97.5% of the design quantity, and the subgrade and bridge have been basically completed, paving and station building have been completed.

Liu Juncheng told reporters that during the construction process, they will conscientiously implement the new development concept, first innovate the construction management concept, and increase the service and leadership to the construction site according to the management orientation of service guidance and supervision. The second is the innovation of construction management mode, which effectively activates the endogenous power of construction production through typical guidance and dynamic design; The third is the innovation of construction technology, which provides a strong support for the construction of China-Laos Railway by innovating the construction technology of weak surrounding rock. China-Laos Railway is an international railway, mainly invested and built by China. The whole line adopts China technical standards, uses China equipment and is directly connected with China railway network. The total length exceeds 1000 km. It's only 3 after opening.