Excavating the Lot 1 of the Chengdu-Zigong high-speed railway, the EPBM Jinxiu has achieved a monthly advancement record of 406.8m, as the China Railway Construction Heavy Industry Co Ltd (CRCHI) reports.
Considering an average daily advance of 13.12m in July, the intended machine, which has been named after the tunnel it is boring, has exceeded the monthly progress of 394.2m in May, while the geology is mainly mudstone.
Being developed jointly by CRCHI and China Railway 14th Bureau Group Corporation Ltd, Jinxiu has a 12.79m diameter, 135m length as well as 7500kW installed power.
Although the total length of the Jinxiu Tunnel is 3.65km, 2.62km of that was dug by EPBM. The minimum curve radius of the shield machine excavation section is 650m, the line spacing is 4.2m and the location of this single bore tunnel, which will feature two rail lines, is at depths of 7-51m.
Due to the passing of the intended tunnel beneath several sensitive buildings and existing railway lines, in order to solve some of the challenges the design was optimized so only two cutting tools needed to be changed over 1937km.