Closure of steel tube concrete arch bridge with the highest span and the largest railway in the world

At 7:00 on June 20, with the smooth pouring of the last concrete, the cast-in-place main girder of the double track super major bridge of the Yarlung Zangbo River in the lain section of Sichuan Tibet railway, the world's highest elevation and largest span of railway steel tube concrete arch bridge, was successfully closed, marking the completion of the main works of 120 bridges along the whole line of the railway.

Located in Jiacha County, Shannan City, Tibet Autonomous Region, the double track bridge of the Brahmaputra River stands in the upper reservoir area of the zanmaputra hydropower station in Sangda gorge, crossing the Brahmaputra River with a depth of 66 meters, with a total length of 525.1 meters. The cast-in-place main beam of the closure is a full prestressed reinforced concrete box structure, which is symmetrically suspended on both sides of the section by using the spatial long sling hanger method. The beam is 18 meters wide and 35 meters away from the water surface. The construction period lasts for more than 5 years. It is the longest construction period, the most difficult construction and the most technological control project in the whole line of the Lalin railway.

Located in the canyon and windy area, the double track bridge on the Brahmaputra River has a maximum wind speed of grade 12, which is not only high-altitude construction, but also near water operation. In the process of construction, the construction personnel inherited the spirit of Qinghai Tibet railway, overcame the impact of high cold and anoxia, poor natural environment, difficult construction and epidemic situation, carefully organized, overcome difficulties, optimized the scheme, and ensured that the project construction was completed on schedule.

The timely closure of the main girder of the bridge not only lays a solid foundation for the smooth realization of the goal of opening to traffic of the Larin section of Sichuan Tibet Railway in 2021, but also creates the highest elevation, the largest steel tube arch span (430m main arch span), the largest steel tube diameter of the main arch (1.8m steel tube diameter), and the largest concrete jacking volume in a single pipe (concrete jacking in a single pipe) of the steel tube arch in the world 1022 square meters) 4 "world first".