在建的佛莞城际铁路狮子洋隧道是第2条下穿珠江口狮子洋海域的盾构隧道,具有大直径(13.1 m)、高水压(最大水压0.78 MPa)、地质条件复杂(全断面土岩复合地层、穿越3处破碎带和2处水下断层)、独头掘进距离长(长4.9 km)、行车速度高(时速200 km/h)等显著特点.本文以该隧道工程为背景,采用工程类比、资料调研、经验总结等方法,通过对工程总体设计及关键技术的阐述,解决了基岩地层水下盾构隧道合理埋深选择、管片环向错台控制、高水压管片接缝防水、循环荷载下基底软弱地层沉降控制、内部结构同步施工等技术问题,提出了铁路盾构隧道管片双掺钢纤维及聚丙烯纤维以提高耐火性的方法,同时对复合地层(尤其是破碎地层)盾构选型、高水压条件下开舱技术进行了探讨.%Shiziyang Tunnel under construction on Foshan-Dongguan Intercity Railway, which has the significant characteristics of large diameter (13.1 m), high hydraulic pressure (0.78 MPa max.), complex geological conditions (full cross-section of composite strata, three fracture zones and two underwater faults), long distance of blind heading of shield (4.9 km) and high running speed of train (200 km/h), etc, is the 2nd shield tunnel crosses underneath Pearl River Estuary Shiziyang Sea.In this paper, the engineering comparison, data research and experience summary are carried out, and the overall design and key technologies for Sizhiyang Tunnel are introduced.And then, a series of problems, i.e.selection of depth of underwater shield tunnel in bedrock strata, segment circular dislocation control, segment joint waterproof under high hydraulic pressure, settlement control of weak base soil under cyclic load and synchronous construction of internal structure, are proposed and solved.Finally, the double-doping steel fiber and polypropylene fiber which can improve fire resistance capacity of shield tunnel segment are proposed;and the shield type selection in composite strata (especially in fracture formation) and shied chamber opening technology under high hydraulic pressure are discussed.
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