Completion of concrete pouring for the second lining of the first plate of the longest tunnel in the Kangyu section of the West Chongqing high-speed rail.

On August 19, with the last concrete injection, Tiefengshan Tunnel, the longest tunnel in the first 15 tenders of Kangyu Section of Xiyu high-speed rail, was completed, marking the progress of the tunnel construction and laying a solid foundation for the follow-up construction.

Tiefengshan Tunnel, with a total length of 14,781 meters and a maximum buried depth of 870 meters, spans Wanzhou District, Yunyang County and Kaizhou District of Chongqing City. It is a single-hole double-track tunnel, which is the control project of the whole line. Grade IV and V surrounding rocks account for 93% of the tunnel. The unfavorable geology mainly includes coal seam and gas, harmful gas, karst, high ground stress, bedding, weak surrounding rock and other unfavorable geology, as well as soft plastic silty clay, salt-soluble breccia, gypsum, expansive mudstone and other special rock and soil.

In order to ensure the smooth pouring of the secondary lining, the project was planned and carefully deployed in advance, the first special construction scheme for the lining construction at the entrance of Tiefengshan Tunnel was formulated, and various departments and cooperative teams were actively organized to hold preparatory meetings for lining pouring, and safety and technical disclosure were carried out in detail to ensure the smooth progress of the construction.

The West Chongqing high-speed rail is an important part of China's "eight vertical and eight horizontal" high-speed rail network, including the Beijing-Kunming corridor from Beijing to Kunming and the Baotou (Yinchuan) sea corridor from Baotou, Yinchuan to Haikou. After the completion of the project, it will be connected with the Chengdu-Chongqing high-speed rail, Zhengzhou-Chongqing high-speed rail, Chongqing-Kunming high-speed rail, Xi'an-Yan'an high-speed rail, Xi'an-Shiyan high-speed rail and other lines that have been built and operated, so as to further improve the road network structure in the central and Western regions, which will greatly facilitate the travel of the people along the line. It is of great significance to promote the integration of urban and rural areas and the coordinated development of regions, and to form a new pattern of the development of the western region.