Abstract:

The statistical data on tunnels respectively on conventional railways, highspeed railways, and extralong railways in China by the end of 2023 are presented. According to the data, China′s operating railways have reached a total length of 159 000 km by the end of 2023. Among these operating railways, there were 18 573 tunnels with a total length of 23 508 km. The highspeed railways put into service in China have surpassed 45 000 km in total length, incorporating 4 561 tunnels built with a cumulative length of 7 735 km. Notably, 115 of them were classified as extralong, measuring over 10 km each, and their total length amounted to approximately 1 471 km. Furthermore, China has opened 286 extralong railway tunnels, spanning approximately 3 869 km in length. Out of these tunnels, 13 tunnels were longer than 20 km each, accounting for a total length of approximately 312 km. The authors also provide an overview of tunnels located on the new key projects opened in 2023, including GuiyangNanning railway and ChengduChuanzhusi section of ChengduLanzhou railway. The characteristics of these tunnels are highlighted, along with a summary of the technical experience gained from them. Moreover, the authors summarize the application of technologies in an array of tunnels, including those on GuangzhouShanwei highspeed railway and NingboJinhua railway, as well as the Liucun largediameter TBM tunnel on NanningChongzuo railway and tunnels on HeshunXingtai railway. Specifically, GuiyangNanning railway offers a paradigm that effectively mitigates safety risks associated with operating highspeed railways in karstdeveloped areas. This approach involves 3D spatial route selection, implementing innovative methods for karst treatment, and enhancing drainage measures during operation. The design of ChengduLanzhou railway fully reflects the concept of "priority to disaster reduction in route selection". This concept has resulted in a notable reduction of safety hazards during operation. In addition, innovative treatment techniques have been applied in tunnels that traverse active fault zones. As railway development in China continues to expand towards the western regions, tunnel construction faces a range of significant challenges. These include increasing burial depth, higher ground stress, complex geological tectonism, and oxygendeficient environments in highaltitude areas. It is imperative for industry peers to collaboratively address these challenges and make continuous innovations to advance tunnel construction technologies.

Key words: railway tunnel, highspeed railway tunnel, extralong railway tunnel, statistics