【作者】 耿晔晗；

【导师】 郄志红；

【作者基本信息】 河北农业大学 ， 水工结构工程， 2012， 硕士

【摘要】 桥梁、渡槽等跨河流、沟谷的重要建筑物,是生命线工程中的喉结,它的安全和不间断工作是线路畅通的重要环节。由于洪水灾害发生十分频繁,从而导致的交通断路现象时有发生。为了保证道路的安全畅通,消除洪水灾害威胁,对跨河桥梁进行防洪风险分析则显得尤为重要,这不仅可以合理的控制建筑物在生命周期内的风险,也有助于优化设计和制定科学的维护管理计划,降低损失成本。本论文主要针对桥梁的冲刷风险、撞击风险和桩基承载力风险进行研究,依托邢衡高速公路老漳河特大桥。主要对以下几方面进行的研究:(1)洪水作用下桥梁风险分析方法的分析与综述;(2)应用模糊随机可靠度理论,确定桥梁基础冲刷的破坏分级,构建三级破坏隶属度函数,建立了桥梁基础防冲刷的极限状态方程,通过MATLAB实现JC法求解桥梁的冲刷可靠度。通过老漳河特大桥计算数据得出:随着洪水流量的增大,洪水频率则越小,冲刷深度则越大,且老漳河特大桥桩基长度存在优化空间。(3)对于在洪水作用下桥墩受漂浮物撞击,主要考虑了浮木等物体,进行了不同角度的撞击力计算。(4)针对桥梁失效概率较小,采用蒙特卡罗模拟需要庞大计算的问题,提出了应用基于序列子集(Subset)的马尔可夫链蒙特卡罗(MCMC)方法,这种方法不仅可以模拟任意分布的随机变量,也可以在保证模拟精度的同时,大大减少随机变量的抽样次数。将该种方法应用于桥梁桩基承载力风险的计算,建立在正常运行和在洪水状态下的桩基承载力极限状态方程,通过MATLB编程,得到单桩承载力的风险概率。以老漳河特大桥为例,在两种情况下的桩基承载力均满足安全要求。(5)对本论文的研究工作进行了总结,今后的研究重点进行了展望。更多还原

【Abstract】 The bridge and aqueduct are not only the important building for crossing the rivers and valleys,but also the key of the lifeline engineering.The safety and uninterrupted work of them is the important link in the smooth traffic.Due to the frequent flood disaster,often occur traffic breaking.It is important to carry out flood risk analysis in order to ensure for the safety and smooth of road and eliminate flood threat.The risk analysis of flood control not only can reasonably control the risk of bridge during the life cycle,but also is helpful for design optimization,making scientific maintenance management plan and reducing the loss cost.In this paper,scouring risk,impact risk and bearing capacity risk of pile foundation are researched.Basing on Laozhang River long-span bridge of Xingheng expressway.The content studied includes the following several respect mainly:(1) Analyses and review of risk analysis of flood control under the action of flood.(2) Scour damage classification of bridge foundation is determined and membership function of the three levels damage is constructed.Furthermore,limit state equation of bridge scour is established by applying the theory of fuzzy-random reliability.By programming with MATLAB,JC method is introduced to calculate the scour reliability of the bridge.Take Laozhang River long-span bridge as an exemple, from the data we can see that flood frequency and scouring depth increase with flow rate and the pile long can optimize.(3) For the impact force of floating objects under the action of the flood,this research mainly calculate impact force of different angles by considering the objects such as floating wood and oil drums and so on.(4) Considering the small failure probability of bridge and the problem of the monte carlo simulation needing a great lot of calculations,Marko Chain Monte Carlo method basing on the subset theory is put forward.This method not only can simulate random variables with any distribution,but also can greatly decrease the number of times of simulation on the premise of the same simulation precision.Through establishing the limit state equation on bridge foundation,this method is applied to calculate bearing capacity risk of pile foundation in normal operation and flood state,then calculating risk probability of bearing capacity of single pile through the programming in MATLAB. Take Laozhang River long-span bridge as an exemple,bearing capacity of pile foundation meet the safety requirements in normal and flood conditions.(5) Summarizing the research work in this paper and the research emphasis in the future is expected.更多还原