Fuxing tunnel of Yunnan Darui railway marks a new breakthrough in tunnel construction in China

After ten years of hard work by thousands of builders, the Fuxing tunnel of Dali Ruili railway was successfully completed on December 6. As the tunnel under construction in China with large deformation and the first use of prestressed anchor cable, Fuxing tunnel through marks a new breakthrough and a new level of tunnel construction in China.

Fuxing tunnel is located near Dali City, Dali Prefecture, with a total length of 5085 meters. It is the first tunnel of Dali Ruili railway from Dali station. The tunnel is located in the soft rock area of the red bed in western Yunnan. The geological condition is complex. The grade IV and V surrounding rocks of the tunnel intersect. The sandstone and mudstone contained in the tunnel are relatively broken. The maximum deformation of the surrounding rock during the construction is about 2 meters. It is very rare in the railway tunnels under construction in China at present, which puts forward high requirements for the construction quality of the tunnel and brings great difficulties to the tunnel construction.

in view of the rare large deformation of Fuxing tunnel, DARUI Project Department of China Railway No.8 Engineering Group Co., Ltd. organized domestic experts in tunnel design and construction for four times. After more than two years of repeated tests, the original horseshoe section was changed into a circular section and prestressed anchor cable was added to solve the problem of large deformation. The reporter learned that this method is still the first time to use in the domestic tunnel construction, which has a high reference value for similar tunnel deformation treatment. In the construction process of

, in addition to the influence of large deformation, Fuxing tunnel is also faced with the construction problems of passing through a 76 meter long Expressway and a residential area. For this reason, the constructors innovatively adopt such methods as one-time preset 133 meter long pipe shed, advance small pipe grouting, densification and enlargement of steel arch frame to make the tunnel pass under the expressway safely. In the construction process, more than 500 monitoring points are set up around the underpass section to realize the real-time monitoring of the ground buildings and ensure the construction period and safety. The smooth connection of Fuxing tunnel also laid a solid foundation for the smooth progress of the whole line construction.

Dali Ruili railway starts from Dali station of Kunchu Dali Railway in the East and ends in Ruili, a border city between China and Myanmar in the west, with a total length of about 330 km. After the completion of the Dali Ruili railway, the history that Baoshan City and Dehong Dai Jingpo Autonomous Prefecture are not connected to the railway will be ended, which has far-reaching significance for promoting the regional economic and social development along the railway.