超大直径泥水盾构带压进舱换刀技术研究与应用

摘要

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.%对于复杂地质条件下的盾构掘进，刀具更换往往不可避免。由于地质的复杂性、多变性和周边条件的局限性，常常无法实施盾构周边土体加固常压进舱换刀。带压进舱换刀技术以无需地层加固、地质适应性强、对周边环境要求低和影响小等特点，解决了苛刻条件下的换刀难题。为了能实现强渗透地层气压状态下开挖面稳定，采用室内试验对进舱泥膜的气密性进行了研究，研究结果表明：进舱泥膜不仅要在开挖面形成一层致密的不透气泥皮型泥膜，还需在地层中形成均匀的透渗带泥膜，方能达到最佳的闭气效果。基于研究成果，南京纬三路过江通道N线工程实现了泥水盾构开挖面大面积气压支护进舱作业，并采用压缩空气作业与饱合潜水作业完成了盾构刀盘的维修和刀具的检查与更换。