天然气管道冲击外载荷作用下的极限状态设计方法研究

发布时间：2018-01-21 23:11

本文关键词： X80 埋地管道落石冲击可靠性极限状态　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着天然气管道的大量敷设,第三方载荷(落石冲击、夯击、交通载荷)对埋地管道的干扰日益严重,尤其崩塌引起的落石灾害。落石具有较大的冲击能量,冲击产生的损坏极易超过管道的极限承载能力,大口径高钢级管道多属于薄壳结构,损坏更为严重。但是,目前缺少大口径高钢级管道在落石冲击力作用下极限状态设计方法的研究。本文结合冲击理论、有限元数值模拟和概率分析方法等手段,对落石从边坡运动开始到冲击管道结束整个过程进行了研究,确定了不同壁厚的X80钢级埋地管道在落石冲击力作用下的应力分布规律与设计方法,主要取得如下成果:(1)对落石边坡运动过程和落石冲击过程进行理论分析,确定边坡高度、坡度和落石重量是影响落石冲击力大小的主要因素,并针对主要影响因素建立了用于描述落石冲击力分布规律的100个边坡模型。基于应力的失效判据进行管道极限状态设计方法研究,确定管道极限状态为极端极限状态(ULS)。(2)基于RocFall软件建立的落石运动边坡模型,得到落石边坡运动结束后首次冲击地面过程中冲击速度、冲击角度和冲击位置等变量的正态分布规律。基于改进的叶四桥经验公式计算落石冲击力,并利用SPSS软件检验得到落石冲击力服从Gamma分布,形状参数α为5.050,速率参数β为0.002。对影响落石冲击力计算的主要因素进行敏感性分析,得到影响因素敏感程度从大到小顺序为落石高度边坡坡度落石重量。(3)基于ABAQUS有限元软件建立的落石冲击埋地管道模型进行不同冲击方案的模拟与分析,冲击力作用下管道最大应力出现在管道顶端。利用SPSS统计软件对Φ1219×18.4mn、Φ1219×22mm和Φ1219×26.4mm三种规格在不同埋深情况下管道顶端最大应力进行统计分析,管道顶端最大应力均服从Gamma分布。通过Matlab编程对管道应力分布拟合,总共确定了 12组Gamma分布概率密度函数参数。(4)通过Matlab编程,采用直接抽样Monte Carlo方法计算管道失效概率和可靠指标。对Φ1219×18.4mm、Φ1219×22mm 和Φ1219×26.4mn 三种规格 X80 钢级管道的临界埋深进行研究,管道临界埋深分别为1.33m、1.26m、1.15m。在目标安全水平下管道应力极限均没有超过API SPEC 5L《管线管规范》规定的最小强度值。基于极限状态方程Z = 0.9σs-σvon mises进行管道极限状态设计,给出了崩塌区X80级埋地管道在不同目标安全水平下的极限状态设计表达式,提出了 X80级埋地管道极限状态设计方法,并编制了相应的极限状态设计流程。基于概率分析方法确定的管道极限状态设计方法与设计参数不仅提高了埋地输气管道可靠性分析的可信度,而且对X80钢级埋地管道在崩塌区的风险评估、管道设计及施工具有重要意义。
[Abstract]:With the large number of natural gas pipeline laying, the third party load (falling stone impact, tamping, traffic load) to the buried pipeline increasingly serious interference, especially the collapse caused by the rock fall disaster, falling stone has a large impact energy. The damage caused by impact is easy to exceed the ultimate bearing capacity of pipeline. The large diameter and high steel grade pipeline belongs to thin shell structure, and the damage is more serious. At present, there is a lack of research on the design method of limit state of large-caliber and high-steel pipeline under the action of rock drop impact. This paper combines impact theory, finite element numerical simulation and probabilistic analysis method and so on. The whole process from the start of slope movement to the end of impingement pipeline is studied, and the stress distribution and design method of X80 steel buried pipeline with different wall thickness under the action of falling rock impact force are determined. The main achievements are as follows: 1) the movement process and impact process of rock fall slope are analyzed theoretically, and the slope height, slope degree and falling stone weight are the main factors that affect the impact force. According to the main influencing factors, 100 slope models are established to describe the distribution law of rock fall impact force. The limit state design method of pipeline is studied based on the failure criterion of stress. Determining the limit state of pipeline as extreme limit state A slope model based on RocFall software is established. The normal distribution law of the impact velocity, impact angle and impact position during the first impact on the ground after the end of the rock fall slope movement is obtained. The impact force is calculated based on the improved Ye Si Bridge empirical formula. The distribution of impact force clothing from Gamma was obtained by SPSS software, and the shape parameter 伪 was 5.050. The rate parameter 尾 is 0.002.The sensitivity analysis of the main factors affecting the calculation of the impact force of rock drop is carried out. The order of sensitivity of influencing factors from big to small is slope drop weight of rock fall height slope. Simulation and analysis of different impact schemes are carried out based on the model of rockfall impingement buried pipeline established by ABAQUS finite element software. The maximum stress appears at the top of the pipe under the action of impact force. 桅 1219 脳 18.4mn is calculated by SPSS software. The maximum stress at the top of the pipe with 桅 1219 脳 22mm and 桅 1219 脳 26.4mm under different buried depths is analyzed statistically. The maximum stress at the top of the pipe is distributed from Gamma. The stress distribution of the pipeline is fitted by Matlab programming. A total of 12 groups of Gamma distribution probability density function parameters. The failure probability and reliability index of pipeline are calculated by direct sampling Monte Carlo method. The critical burying depth of 桅 1219 脳 22mm and 桅 1219 脳 26.4mn X80 steel grade pipeline is studied. 1.15m. at the target safety level, the stress limit of the pipeline does not exceed the minimum strength specified in API SPEC 5L < Pipe Specification >. Based on the limit state equation Z =. 0. 9 蟽 s-蟽 von mises is used to design the limit state of pipeline. The limit state design expression of X80 buried pipeline in collapse area under different target safety level is given, and the limit state design method of X80 buried pipeline is put forward. The design method and design parameters of pipeline limit state based on probabilistic analysis method not only improve the reliability analysis of buried gas pipeline. Moreover, it is of great significance for risk assessment, pipeline design and construction of X80 steel-grade buried pipeline in collapse area.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE973.1

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