Abstract:

Some technical difficulties, i.e. serious wear of cutterhead structure, inconvenient adjustment of opening rate of cutterhead, serious wear of cutting tools, blockage of circulation system and serious wear of slurry pipe, are often encountered when slurry shield boring in sandy cobble strata. Hence, countermeasures for the difficulties mentioned above are put forward by taking Yellow Rivercrossing Tunnel of Lanzhou Metro in waterrich sandy cobble strata for example. The study results show that: (1) The wear of cutterhead structure and adjustment of opening rate of cutterhead can be improved by adaptive improvement on cutterhead. (2) The abrasive resistance of the cutting tools and the shield boring efficiency can be improved by replacing the singleedge disc cutter by doubleedge disc cutter and diversion cutter by tearing cutter. (3) The blockage of circulation system can be solved by improving rock breaking system and largesize boulders treatment. (4) The serious local wear of slurry pipe can be solved by sectioning slurry pipe into 3 and connecting each section by flanges.

Key words: sandy cobble strata, slurry shield, tunnel, metro, opening rate of cutterhead, wear of cutting tools, blockage of circulation system