Abstract: The reinforced ribs of sprayed concrete(RRS) in the Norwegian Method of Tunneling has been proved to be an economical and efficient supporting structure for the weak surrounding rock engineering in China and abroad. The weak zone in the Finnfast subsea tunnel in Norway was taken as a case study to demonstrate the supporting effects of RRS on weak surrounding rock. In view of the Q system for the classification of surrounding rock quality, finite difference method was employed to compare the deformation, the stress distribution, and the yield volume of surrounding rock in the presence and in the absence of RRS. The results show that RRS has good supporting effects on weak surrounding rock.

Key words: weak surronding rock, reinforced ribs of sprayed concrete, supporting effects, numerical simulation