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跨海大桥深水桩基础防船撞能力及安全评估研究
Research on the Ability of Deep Water Pile Foudation of Cross Sea Bridge against Ship Collision and Its Safety Assessment
【作者】 李维洲；
【导师】 冯忠居；
【作者基本信息】 长安大学 ， 岩土工程， 2014， 博士
【摘要】 近二十年来我国修建了近百座的跨江、跨海大桥，许多都是举世瞩目的超级工程，但船撞桥而引发重大人员伤亡、财产损失的事件时常发生，说明在通航水域桥梁的防撞设计和防撞措施上还存在不足。我国桥梁防撞研究起步晚，早期重视程度不够，防撞设计理论及计算多依赖国外的研究成果，这和我国桥梁总体建设水平极不相称。本文结合平潭海峡大桥工程，基于现场模拟试验、数值分析及理论分析的方法，研究跨海大桥深水桩基础的防船撞能力，在此基础上进行船撞桥风险概率的安全评估，提出跨海大桥深水桩基础选用的防撞类型，及其防撞设施设计与施工关键技术。本文主要成果体现在：1.结合平潭大桥开展船舶撞击桥梁基础现场模拟试验，验证船撞桥梁数值仿真分析所采用的计算参数准确性和数值仿真计算方法的合理性。现场模拟碰撞试验结果表明：桥墩在环境激励下的自振频率与有限元模拟计算得到的自振频率比较接近，振动现场测试的加速度或速度的数据曲线与数值模拟计算得到的数据曲线呈现出强烈的非线性，但二者曲线总体趋势一致。试验验证了防撞钢套箱以及船用钢材采用各向同性应变率相关的塑性模型中相关本构关系及相关的计算参数的合理性，为船桥碰撞有限元模拟提供了试验依据。2.对船舶撞击桥梁桩基础进行数值模拟计算，结果表明：船桥碰撞最不利计算工况是最低通航水位下正撞时的工况，此时桩基础的桩基弯矩最大。与无防撞设施的桩基础相比，有防撞设施的桩基础受船撞后最大撞击力、承台水平位移及桩基最大弯矩、最大拉应力明显减小，且船舶撞击深度亦明显减小。3.建立了船撞作用下的群桩基础力学模型，提出承台受扭转作用时的单桩桩基内力计算方法。4.采用经验公式法、有限元法及动力模拟法对船撞力进行了计算，运用AASHTO模型对船撞桩基础的概率进行了计算，并以此为基础得出防撞力标准。结果表明：动力模拟计算的船撞力最大，其中主通航孔各墩为34.66MN，非通航孔为22.14MN；船撞桩基础的概率主通航孔各墩为2.187×10-4，非通航孔为0.492×10-4；经检验假定的主通航孔墩设计防撞力标准34.5MN，非通航孔过渡墩21.5MN满足规范要求。5.提出跨海大桥深水基础的承台采用钢套箱作为防撞设计，承台处在合适的水面标高能有效降低桥梁基桩受船撞的风险，并结合工程实际建议防撞钢套箱安装应和承台同步施工。介绍了防撞钢套箱和防撞墩的设计与施工关键技术。论文的研究成果对大型跨海深水桩基础桥梁的防撞理论体系的完善及设计与施工技术有借鉴价值。
【Abstract】 Our country had built nearly a hundred River-Crossing Bridges and Sea-CrossingBridges in recent twenty years. Many of them were world-renowned super engineering, butthe ship-bridge collisions took place usually in personnel dead, property lose and injured etc.Which meaned the anti-collision design and measures of bridge had obvious shortcomings innavigable waters. Our country started latly and also not notice the importance of research ofbridge collision avoidance, so the research of anti-collision design theory and calculationmuch dependended on foreign, which form a disproportion with china’s general level ofbridge construction. Combining with the engineering of Pingtan Strait Bridge, the simulatedtest, numerical analysis and theoretical analysis methods to research on the ship collisionprevention ability of bridge piles foundation in deep water was stuied in this paper. Based onthe analysis, the safety assessment of ship bridge collision risk was carry out, the typeselection of anti-collision and the key technology of anti-collision facilities design andconstruction of piles foundation in deep water was put forward. The main results were shownas the following:1. The bridge simulation test of ship collision of Pingtan bridge was carried out to verifythe the accuracy and reasonableness of calculation parameters of the numerical simulationmethods. The results of ship collision test showed that: the natural frequency of pier on theenvironment excitation was close to finite element simulation, the data curves of accelerationand velocity of the numerical simulation and vibration field testing had been showing a strongnonlinear, but the overall trend is consistent between the two curves. The experiment verifiedthe rationality of isotropic strain plasticity model relevant constitutive relations and relatedcalculation parameters of anti collision steel box and marine steel, which provided anexperimental basis.to the crash finite element simulation.2. The results obtained from numerical simulation computation of ship impacting bridgepile foundation showed that：the head-on collision under the lowest navigable water level isthe most adverse conditions of ship bridge collision computing, and At this time the bendingmoment of pile foundation pile foundation is largest. Compared with no anti-collisionfacilities of pile foundation, the maximum impact force, horizontal displacement of pilecaps, maximum bending moment and maximum tension stress of pile foundation reducesignificantly, at the same time depth of ship collision reduce significantly as well withanti-collision facilities of pile foundation.3. The mechanical model of a group pile foundation under of the role of ship collision was established. When the cap was acted by twisting, the calculated of pile internal forces wasproposed.4. The ship collision force was calculated by using the empirical formula method, finiteelement method and dynamic simulation, the AASHTO model was used to calculate the shipcollision probability, and the collision force standard was deduced. The results show that: theresult of dynamic simulation wa the maximum force, and the force value of each pier of themain navigation was34.66MN, while non-navigable was22.14MN; ship collision probabilityof each pier of the main navigation was2.187×10-4, while non-navigable was0.492×10-4; it wasverified that the assumed collision force design standards value of main navigation pier34.5MN and non-navigable transition pier21.5MN t meet the requirements.of specification.5. It was proposed that the anti-collision of deepwater pile foundation of cross-sea bridewas designed with steel sleeve box. Pile caps with Sutable surface elevation could effectivelyreduce the risk of bridge hit by ship and it was recommend that the installation ofanti-collision steel crash box and the pile caps should be constructed synchronously. Thedesign and construction technolygy of anti-collision steel boxed cofferdam and anti-collisionpier was introduced.The research results not only can improve theoretical system of large-scale cross-seacollision deepwater foundation of the bridge, but also have reference value to the design andconstruction techniques.