预切槽法在浅埋暗挖下穿公路段隧道中的设计

摘要

研究目的:机械预切槽法因其结合盾构的盾壳保护开挖理念和新奥法处理复杂地层的自由灵活理念,在土砂等极软弱围岩地质条件、城市特殊复杂环境近接施工或以上因素复合形成的复杂困难工程条件下具有显著的优势,可以较好地保障隧道施工的安全,同时也是机械化施工的一种很有发展潜力的隧道施工方法.本文结合福平铁路新鼓山隧道下穿福州机场高速公路的浅埋暗挖段,对隧道预切槽法施工在软弱地质下浅埋暗挖下穿通过道路的城市环境应用进行设计与分析,提出该方法的可行性.研究结论:(1)预切槽法可以应用于浅埋暗挖、下穿道路等特殊隧道段落的施工;(2)在浅埋、软弱、近接等特殊条件下,预切槽法形成的预筑拱作为超前措施,较常用的管棚等技术手段,对控制地表沉降、保证施工安全有更显著和可靠的作用,具有更大的安全性;(3)本研究结论可为类似工程条件的隧道设计提供借鉴.%Research purposes:Combined with the idea of shield tunneling and NATM,the pre-cutting method is more flexible with complex geology.It is a promising method for mechanization construction,and can ensure the safety of tunnel construction to a large extent especially when facing with small strength sand or clay,and with cases of tunneling near other structure in city.In this paper,with the problem of designing construction plan of Xingushan tunnel,a shallow-buried section of the tunnel under the Fuzhou Airport Expressway,the feasibility of pre-cutting method used in shallow tunneling underpass road in small strength sand or clay is discussed.Research conclusions:(1) The pre-cutting method can be designed for shallow tunneling,tunneling underpass road and other special sections of tunnel construction.(2) Compared to common technique means such as pipe roof,precut arch formed by pre-cutting method is more advanced and reliable to control surface subsidence and ensures construction safety under the special conditions of shallow,weak and close construction.(3) The research results can give references for deign of the same surroundings tunnel engineering.