Abstract: During the construction of large crosssection horseshoeshaped EPB shield, many problems such as attitude control difficulty, mud cake and tunneling difficulty, would be encountered. Hence, the key technologies for the construction of large crosssection horseshoeshaped EPB shield used in Baicheng Tunnel of Menghua Railway are studied. The study mainly focuses on follow aspects: (1) In order to guarantee smooth and safe launching of shield, measures such as launching base, portal sealing device, launching parameters control and counterforce provided by strengthened opencut tunnel are adopted. (2) The shield attitude is controlled by partition cylinder thrust or slurry injection; the soil conditioning effect is improved by high polymer; and the safe shield crossing underneath BaotouMaoming Experssway is guarantee by adopting rational tunneling parameters and measuring method. (3) The problem of blind area at the bottom of the cutterhead is solved by adding a cone slag separator and expanding the spokes of the cutterhead at the bottom of cutterhead. (4) The shield is safely recieived by correctly install the receiving based and endwall.

Key words: tunnel, horseshoeshaped shield, shield launching, attitude control, muck conditioning, blind area excavation, shield arriving