跨海大桥深水桩基础防船撞能力及安全评估研究

发布时间：2018-11-03 09:21

【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]:In the past two decades, nearly 100 bridges across rivers and seas have been built in China. Many of them are superprojects that attract worldwide attention. However, the collision of ships with bridges has caused heavy casualties and property losses. It shows that there are still shortcomings in collision prevention design and anti-collision measures of bridges in navigable waters. The research on anti-collision of bridges in our country started late and paid less attention in the early stage. The theory and calculation of anti-collision design mostly depend on the research results of foreign countries, which is out of proportion with the overall level of bridge construction in China. Based on the field simulation test, numerical analysis and theoretical analysis, this paper studies the ship collision prevention ability of deep-water pile foundation of cross-sea bridge based on the Pingtan Strait Bridge project, and then carries out the safety assessment of risk probability of ship collision bridge. The anti-collision type of deep-water pile foundation of cross-sea bridge and the key technology of design and construction of anti-collision facilities are put forward. The main achievements of this paper are as follows: 1. Combined with Pingtan Bridge, the field simulation test of ship impact bridge foundation is carried out to verify the accuracy of the calculation parameters and the rationality of the numerical simulation method used in the numerical simulation analysis of the ship impact bridge. The field simulation results show that the natural vibration frequency of piers under ambient excitation is close to that obtained by finite element simulation. The data curves of acceleration or velocity measured in vibration field show strong nonlinearity with those obtained by numerical simulation, but the general trend of the two curves is the same. The experiment verifies the rationality of the correlation constitutive relation and the relevant calculation parameters in the plastic model with isotropic strain rate and provides the experimental basis for the finite element simulation of ship bridge collision. 2. The numerical simulation results show that the most unfavorable calculation condition of ship and bridge collision is the positive impact condition under the lowest navigable water level, and the pile foundation bending moment is the largest at this time. Compared with the pile foundation without collision protection, the maximum impact force, the horizontal displacement of the cap and the maximum bending moment of the pile foundation, the maximum tensile stress and the impact depth of the pile foundation are obviously reduced. 3. The mechanical model of pile group foundation under the action of ship collision is established, and the calculation method of internal force of single pile foundation is put forward when the pile cap is subjected to torsion. 4. The empirical formula method, finite element method and dynamic simulation method are used to calculate the ship collision force. The probability of ship collision pile foundation is calculated by using AASHTO model, and the criterion of collision resistance is obtained. The results show that the ship collision force calculated by dynamic simulation is the largest, in which the main navigation holes are 34.66MN for each pier and 22.14MN for the non-navigable holes, and the probabilistic main navigation holes for the pile foundation are 2.187 脳 10 ~ (-4) and 0.492 脳 10 ~ (-4) respectively. The test assumes that the design of the main navigable hole pier is 34.5 MN, and the 21.5MN of the non-navigable hole transition pier meets the requirements of the code. 5. It is put forward that the cap of deep water foundation of sea crossing bridge is designed with steel casing box as collision prevention design, and the cap can effectively reduce the risk of the bridge foundation pile being hit by ship when the cap is on the right surface. Combined with the engineering practice, it is suggested that the installation of the collision proof steel jacket box should be synchronized with the cap. This paper introduces the key technology of design and construction of anti-collision steel sleeve box and anti-collision pier. The research results of this paper can be used for reference in the improvement of the theoretical system of anti-collision and the design and construction technology of the large bridge with deep-water pile foundation across the sea.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U443.26

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