【作者】 王翠；

【导师】 闫澍旺；

【作者基本信息】 天津大学 ， 岩土工程， 2009， 博士

【摘要】 沉管法作为一种较先进的水下隧道修建方法,越来越受到各国工程界的重视。该项技术涉及了岩土工程的许多重要课题,土壤的性质在隧道建设中处于不断变化的状态,稳定计算模式需要考虑的因素复杂。虽然欧美及日本已经有不少成功应用该工法的实例,我国上海、广州和宁波等地区也有少量类似工程,但目前世界各国均无相关规范指导设计施工,国内外工程界对该工法的研究仍处于经验总结阶段,沉管法中仍然存在一些岩土工程问题需要进一步的研究。本文密切结合实际工程,主要在以下几个方面进行了研究探索:(1)沉管隧道的干坞工程作为管段浇筑的场所具有占地面积大、暴露时间长等特点,并且在整个沉管工程的过程中需经历开挖、充水、再排水的复杂过程,其中涉及到土体的卸荷、扰动、浸润、水压力变化、渗流力作用、孔隙水升降等一系列的复杂作用,其力学特性变化很大,使边坡稳定性分析非常复杂。本文对干坞工程边坡各个工况下的稳定性进行了祥细的分析,总结出边坡在不同工况下的稳定性分析方法。(2)沉管法中干坞和水下基槽的开挖会使基底土体处于卸荷状态,其力学参数与正常加荷试验结果有所不同。本文通过室内试验对土体的卸荷强度参数进行了测试分析,得出了卸荷比和影响深度,并将试验结果应用于有限元分析,计算了地基土体在卸荷状态下的承载力和变形情况。(3)岸壁保护结构在施工的过程中将处于多种复杂工况,其受力条件变化很大,并且格构式地下连续墙的结构形式复杂,空间尺寸差异较大,无法采用常规的方法进行分析。本文采用规范法与有限元法,分析了格构式地下连续墙在不同工况下的稳定性及受力变形情况。(4)本文对ABAQUS软件进行二次开发,采用Duncan-Chang模型模拟地基土体,对干坞、基槽、岸壁保护结构体系施工对周围环境的影响进行了分析,分析结果与实测吻合较好,能够较真实的反映工程实际。(5)研究成果已作为天津海河隧道工程的设计和施工的依据,也可为北方地区的类似工程参考。更多还原

【Abstract】 Immersed tube method is one of the most advanced construction methods for building underwater tunnels. A number of geotechnical engineering problems are involved in such kind of projects. The soil properties are changeable during different periods of construction, and many complicated factors must be considered in analyzing the stability of the foundation system. Although several Caisson Tunnels have been built, no code for guiding design and construction was developed. Several geotechnical problems in Caisson Tunnel engineering still need to be further studied.The main achievements of this thesis are as follows:(1) The dry-dock is the field of constructing the tunnel pieces. It usually has large dimensions and will be exposed for several years. During construction, the dry-dock will be excavated, refilled with water and redried. In such periods, the soil will be unloaded and disturbed, the ground water level and the pore water pressure will change, and seepage will occur. All of these may have great influence on the behavior of soil. The slope stability of dry-dock under different conditions was analyzed considering the environment influence and soil properties at every different construction state.(2) The soil mass in foundation of dry-dock and underwater trench will be unloaded after the excavation works. The strength parameters of soil unloaded will change seriously from the initial condition. Based on laboratory tests, the proper parameters of unloaded soil were determined and the unloading ratio and the depth affected were derived with the FE analysis. Using these results, the bearing capacity and the deformation of the foundation were calculated.(3) The lattice style soil retaining system is a kind of complicated structure. Different segments have distinct thickness and length. And the environmental forces acting on it are changeable. Analyzing the stability and security of the diaphragm wall becomes very challenging. Code method related to soil retaining wall and FEM were both used in such kind of analysis。(4) In order to simulate the behavior of soil more precisely, the Duncan-Chang model was introduced and linked to the famous FEM software ABAQUS by developing a section of program. The influence of Caisson Tunnel engineering on the surrounding circumstance was predicted by the developed software. The simulation results agree well with measured data.(5)The results achieved in the thesis has been applied for the design and construction of the Haihe Caisson Tunnel project in Tianjin, and also can be referred by the similar tunnel project in Northern areas of China.更多还原