落石冲击下拱形明洞结构概率可靠性研究

发布时间：2018-01-10 07:06

本文关键词：落石冲击下拱形明洞结构概率可靠性研究　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着高速铁路向西部艰险山区的延伸,铁路隧道工程的修建难度和建设规模越来越大,但受地质条件和施工扰动等因素的影响,使得隧道洞口段成为最易遭受落石侵袭的地段,而拱形明洞结构由于受力合理,抗冲击性能强,且与暗洞过渡自然等优点,日渐成为落石多发区普遍采用的防护措施。本文以客运专线双线隧道拱形明洞为研究对象,通过文献调研,理论分析和三维颗粒流离散元(pFC3D)模拟的方法,对落石冲击下拱形明洞结构的概率可靠性进行了系统研究,主要研究成果如下:1、通过对实际落石灾害和室内模型试验的调研分析,结合离散元颗粒流模拟结果,可以确定落石冲击下拱形明洞结构表现为局部的失效破坏。根据落石冲击下拱形明洞结构的力学响应特征和荷载分布形态,可将明洞失效部分简化为四边固支钢筋混凝土方形板,按刚塑性板静态失效荷载的计算方法,得出结构在落石冲击下的极限承载力表达式。2、利用三维颗粒流离散元模拟方法,对不同落石高度、不同落石重量及不同回填土厚度条件下,落石冲击方形平板结构试验进行模拟,确定了平板不同尺寸范围内所受的落石冲击荷载,结合对应的工况组合条件,建立了关于落石冲击中心集中力和均布压力的回归分析表达式,以此来反映落石冲击荷载的变化规律。3、根据已确定的结构极限承载力和落石冲击荷载联立得到极限状态方程,结合随机变量的分布类型和概率统计特征,采用适用于包含非正态随机变量可靠性分析的当量正态化法,通过编写MATLAB程序对结构可靠指标进行计算,求得落石冲击下拱形明洞结构的可靠指标最小值为2.85,对应的失效破坏概率为0.219%。
[Abstract]:With the extension of high-speed railway to the western mountainous area, the construction difficulty and construction scale of railway tunnel project is becoming larger and larger, but it is affected by geological conditions and construction disturbance and other factors. The tunnel entrance section is the most vulnerable to rock fall, and the arch tunnel structure has the advantages of reasonable force, strong impact resistance and natural transition with the dark hole. This paper takes the double-line tunnel of passenger dedicated line as the research object, through the literature investigation. In this paper, the probabilistic reliability of the arch tunnel structure under the impact of rock drop is systematically studied by theoretical analysis and the method of three-dimensional particle flow discrete element pFC3D simulation. The main research results are as follows: 1. Through the investigation and analysis of the actual rock fall disaster and the indoor model test, combined with the simulation results of discrete element particle flow. According to the mechanical response characteristics and load distribution pattern of the open arch tunnel structure under rock fall impact, the local failure failure of the arch tunnel structure can be determined. The failure part of the open hole can be simplified as a quadrilateral fixed reinforced concrete square slab. According to the calculation method of static failure load of rigid-plastic plate, the expression .2 of ultimate bearing capacity of the structure under the impact of rock fall can be obtained. Three dimensional particle flow discrete element simulation method is used to simulate the slab structure test under the conditions of different falling height, different falling weight and different backfill thickness. The rock falling impact load in different size range of flat plate is determined. Combined with the corresponding working condition, the regression analysis expression about the concentrated force and uniform distribution pressure of rock falling impact center is established. According to the determined ultimate bearing capacity and rockfall impact load, the limit state equation is obtained, combined with the distribution type of random variables and probability and statistical characteristics. The equivalent normalization method, which is suitable for reliability analysis of non-normal random variables, is used to calculate the structural reliability index by writing MATLAB program. The minimum reliability index of the arch structure under rock fall impact is 2.85 and the corresponding failure probability is 0.21919.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451

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