Abstract: According to the statistics of underwater tunnels in China as of the end of 2023, a total of 333 underwater tunnels (with underwater section length 〖WT〗L〖WT５《TNR》〗≥100 m each) have been built (including those initiated but not yet completed) in China by the end of 2023. A comprehensive analysis is conducted on these underwater tunnels from multiple aspects, 〖HJ3.2mm〗including the years of commencement, provincial administrative regions, water bodies crossed, construction methods, purposes, crosssectional sizes, lengths of underwater sections, design institutes, construction contractors, waterhead heights, maximum water depths, minimum cover depths, structural types, and numbers of tracks/lanes. The analysis reveals the following results: (1) There was 12 under water tunnels before 2000, showing a slow development speed. The past decade (20002023) witnessed the highest number of underwater tunnels being initiated, and there were 321 underwater tunnels (34 and 32 in 2019 and 2022, respectively). Guangdong province stands out for having constructed the highest number of underwater tunnels during this period, reaching 74, among which there are 31, 28, and 25 underwater tunnels crossing the Yangtze river, the Huangpu river, and the Pearl river, respectively. (2) The primary construction methods employed include the shield method, cut and cover method, and immersed tube method, accounting for 93.1% in all methods, and shield method is the most favorable one, reaching 76.6%. (3) The purposes of the underwater tunnels are metros and municipal roads/highways, the number of these tunnels account for 40% and 38%, respectively. (4) Among the underwater tunnels constructed by shield method, most of the shield diameter(〖WT〗d〖WT５《TNR》〗) is ＜7 m, accounting for 44% in all diameters, 7 m≤〖WT〗d〖WT５《TNR》〗＜10 m accounts for 11%, 10 m≤〖WT〗d〖WT５《TNR》〗＜14 m accounts for 24%, and 〖WT〗d〖WT５《TNR》〗≥14 m accounts for 21%. The crosssectional area(〖WT〗A〖WT５《TNR》〗) of the ShenzhenZhongshan Link immersed tunnel construed by immersed tube method is the largest, reaching 587. 88 m2. The   underwater tunnels constructed by nonshield method with a crosssectional area of 200 m2≤〖WT〗A〖WT５《TNR》〗＜300 m2 are the most, accounting for 35%. (5) The underwater tunnels with an underwater section length(〖WT〗L〖WT５《TNR》〗) of 100 m≤〖WT〗L〖WT５《TNR》〗< 500 m and 1 000 m≤〖WT〗L〖WT５《TNR》〗< 3 000 m account for 35% respectively. (6) The underwater tunnels with a water head height(〖WT〗h1〖WT５《TNR》〗) of 10 m≤〖WT〗h1〖WT５《TNR》〗＜30 m, a maximum water depth(〖WT〗h2〖WT５《TNR》〗) of 10 m ≤〖WT〗h2〖WT５《TNR》〗＜20 m, and a minimum cover depth(〖WT〗h3〖WT５《TNR》〗) of 10 m≤〖WT〗h3〖WT５《TNR》〗＜ 20 m accounts for a large proportion. (7) 67% of the metro tunnels adopt single line, 60% of the municipal road/highway tunnels adopt twoway 6lane, and 82% railway tunnels adopt double line. The underwater tunnels were predominantly designed for metro and highway purposes. The underwater tunnels develop from shallow and narrow water bodies to deep and wide bodies, they gradually become a primary option for sea and river crossings.

Key words: underwater tunnel, data statistics