佛莞城际铁路狮子洋隧道的几个关键技术问题

Several Key Technical Problems of Foshan-Dongguan Intercity Railway Shiziyang Tunnel

研究目的:佛莞城际铁路狮子洋隧道结构外径13.1 m,是国内目前最大直径的铁路盾构隧道。工程具有大直径(13.1 m)、高水压(最大水压7.8 bar)、地质条件复杂(土岩复合地层,穿越三处破碎带和两处水下断层)、行车速度高(时速200 km)、盾构机类型新(土压-泥水双模式盾构)等特点。为保证施工与运营安全,必须妥善解决总体设计、施工组织设计、结构抗灾与防灾疏散设计等关键技术问题。研究结论:(1)复合地层水下隧道宜埋置于基岩中,岩石覆盖厚度可按"满足施工进舱作业安全,且围岩松弛压力与形变压力之和相对较小"的原则确定;(2)隧道长度不大时可采用单孔双线结构,并在隧道底部设置疏散廊道,同时采用中间箱涵预制的方式实现同步施工;(3)为减少局部岩层破碎带对施工的影响,可采用土压-泥水双模式盾构掘进;(4)为提高结构的抗灾性能,在钢筋混凝土管片内双掺钢纤维和聚丙烯纤维是一种可行的方案;(5)该研究成果可应用于复合地层盾构法水下隧道的设计。

Research purposes： Foshan - Dongguan Intercity Railway Shiziyang Tunnel whose structure external diameter is 13. 1 m is the largest railway shield tunnel in China. This project has multiple ＇characteristics of large exradius （ 13.1 m） , high water pressure （ 7.8 bar） , complex geological conditions （ soil and rock mix ground, cross - over 3 fracture zone and 2 underwater faults）, high speed （ 200 km/h）, a new type of shield machine （ dual - mode）. To ensure the safety of construction and operation in this project, the key technical issues of overall design, construction organization planning, disaster - resistance of structure and evacuation design must be solved appropriately. Research conclusions： （ 1 ） The underwater tunnel in the mix ground should be buried in the bedrock suitablely, The rock cover thickness of underwater tunnel can be determined, with the principle of ＂Working chamber should satisfy the security criteria, and the sum of relaxation of surrounding rock and deformation pressure is relatively small＂. （2） The tunnel with double tracks can be adopted if the tunnel is not very long, and evacuation corridor can be set up over the tunnel floor, to implement simultaneous construction, the intermediate box culvert can be preeast. （3） In order to reduce the local rock fracture zone effect upon construction, Dual -mode can be used in shield tunneling. （4）To enhance the capability of disaster - resistance of structure, adding steel fiber and polypropylene fiber to reinforced concrete lining segment is a kind of feasible scheme. （5） The research results can be used in the design of underwater shield tunnel in mix ground.