Abstract:

The lakecrossing section of Slender West Lake Tunnel in Yangzhou is constructed by a 14.93 m slurry shield. The shield has bored through 1 275 mlong stiff plastic expansive clay strata successfully and has overcome a series of technological difficulties such as cutterhead blocking, slurry chamber and slurry pipe blocking, huge cutter head torque, low shield boring speed and difficulty in slurry separation. So far the tunnel is the largest tunnel in China bored by slurry shield in expansive clay strata. In the paper, the effective slurry circulating and muckingout technology when boring through the fullface clay strata, the technology to modify the shield to adapt to the expansive soil strata, the shield boring technology and the excavation face stability keeping technology in the stiff plastic clay strata, dynamic welding technology under 0.42 MPa pressure, accurate shield arriving technology on smallradius curve and rapid construction technology for the internal structures of the twostorey shieldbored tunnel are summarized. The paper can provide reference for the development of the slurry shield boring technology in expansive clay strata in China.

Key words: Slender West Lake Tunnel in Yangzhou, stiff plastic expansive clay strata, shield adaptability improving, maintenance under hyperbaric condition