All eight cross passages have been excavated on China’s major Pudong-Changxing Island tunnel project below the Yangtze river in Shanghai.
Last month, excavation of the eighth cross passage was completed between the 7.5km long main tunnels that run below the Yangtze. The 15m long link tunnels are spaced are intervals of approximately 800m, had excavated widths of almost 4m using ground freezing and the finished openings are 2.74m wide.
The tunnelling works are being done by Shanghai Tunnel Engineering Corp (STEC) in JV with Bouygues, and breakthrough of the second 15.43m diameter Herrenknecht Mixshield (S-318) brought the landmark main bores to completion in September last year.
The TBM drives employed the biggest shields ever used in tunnel excavations.
Geology along the 7.17km long bores comprised sand, clay and rubble up to 65m below the river. Lining is segmental rings (9+1), each 2m long (T&TI, October 2008, p7). The main tunnels will be fitted with double-decking, roads on top and the lower level will take service and safety installations, and maybe a metro link.
The client is Shanghai Changjiang Tunnel & Bridge Construction Development, and design was by Shanghai Tunnel Engineering Design Institute (STEDI).
