砂卵石地层双模盾构针对性设计与应用

为解决泥水盾构在砂卵石地层施工遇见的卡刀盘、堵管、滞排、异常磨损等诸多难题，分析导致泥水盾构在砂卵石地层施工困难的因素，依托成都西环线紫瑞隧道工程展开分析，预判工程重难点，并对盾构进行针对性设计；基于高标准压力及地表沉降隆起控制要求，在砂卵石地层施工中，提出气垫泥水盾构搭载螺机技术方案，且在隧道工程中应用“螺机出渣+闭式管道输渣” 技术；刀盘开挖的卵石被螺机及时输送至仓外，并通过泥浆泵及闭式管道输送至洞外，推进平稳，出渣顺畅，避免了卵石堆积引发的施工风险。工程应用证明，双模盾构相对常规气垫泥水盾构具有更强的适应砂卵石地层的能力。

Specific Design and Application of Double Mode Shield in Sandy Cobble Strata

When slurry shield tunneling in sandy cobble strata, many problems will be encountered, such as cutterhead jamming, pipe blocking, stagnation, and abnormal cutter wear. Hence, the factors induce the above problems in Zirui tunnel of Xihuan road in Chengdu, China, are analyzed. The project difficulties are predicted to conduct specific design. Based on the high standard pressure and surface subsidence requirements, the techniques of air cushion slurry shield equipped with screw conveyor and screw conveyer mucking + closed pipeline mucking are proposed and adopted. The cobble excavated by the cutterhead are timely transported to the outside of the excavation chamber by the screw conveyor, and further transported to the outside of the tunnel through slurry pump and closed pipe, so as to avoid the pebble accumulation and guarantee smooth shield tunneling. The engineering application validates that the double mode shield is superior to conventional air cushion slurry shield in aspect of adaptability to sandy cobble strata.