Abstract:

Cutting tool replacement is inevitable in longdistance shield boring under complicated geological conditions. Due to the complexity, variability and limitation of geological conditions, cutting tool replacement under atmospheric pressure under the condition of reinforcement of the ground surrounding the shield usually cannot be achieved. However, hyperbaric intervention (replacing the cutting tools under hyperbaric condition) has good geological adaptability and can be applied without reinforcement of the ground to solve the problems that come with the traditional way of cutting tool replacement in shield boring. Tests are made on the filter membrane under hyperbaric conditions, so as to obtain a stabilized tunnel face in highlypermeable formations under high pressure. Results show that filter membrane that can provide good support for the tunnel face is made up of two parts, i.e., a compact airtight filter membrane on the tunnel face and a highlypermeable filter membrane zone in the ground. Based on the research results, hyperbaric intervention and saturated diving have been successfully conducted in N line project of Nanjing Weisan Road Rivercrossing Tunnel and the cutting tools of the superlarge diameter slurry shield have been replaced successfully.

Key words: superlarge diameter slurry shield, hyperbaric intervention, cutting tool replacement