水下隧道立交段设计与施工方案研究

水下隧道已逐步成为我国跨江越海的主要交通方式之一,水下隧道立体交叉的情况也越来越常见。针对目前国内缺乏完善的水下立体交叉隧道设计及施工体系,以我国某座水下隧道立交段为研究对象,对立体交叉段做了总体设计,确定了主线与匝道的内轮廓;同时,基于ANSYS有限元软件对主线隧道及匝道开挖过程进行模拟分析,提出隧道主线及匝道的开挖方案。得出如下结论:(1)通过采取CRD法等进行开挖,将大断面化为小断面,分部开挖,双层支护,成功解决了水下隧道立交段施工安全稳定的难题,可有效确保水下立交段隧道开挖的安全;(2)开挖过程中应严格遵守"先下后上、错开施工、超前支护、减少振动、分部施工、及时二衬"的施工原则,能够保证隧道的施工安全;(3)应紧密结合现场实际量测数据对围岩及支护结构的稳定性进行判别,二次衬砌尽量紧跟初期支护施作。

Research on the Design and Construction Plan of Underwater Tunnel Grade Separation

With underwater tunnel as one of the main traffic means for crossing river or sea,grade separation of underwater tunnel becomes more common. Due to the lack of perfect system for design and construction of underwater tunnel grade separation,this paper conducts in-depth study with reference to a domestic underwater tunnel grade separation,completes an overall design of the grade separation and defines the internal profiles of the mainline and the ramp. Excavation processes of main line tunnel and ramp are simulated based on ANSYS finite element software and the excavation plan is drawn out. The conclusions are as the followings:( 1) security and stability problems can be resolved through CRD method by means of reducing large cross-section to small one,excavation by segments,double-layer support;( 2) such construction principles are adopted as"cross construction,advance support,vibration reduction,segment construction and timely second lining";( 3) second lining should be kept in progress with initial support and stability discrimination of surrounding rock and support structure is conducted based on site measurement data.