典型地质灾害下高强钢埋地管线安全性研究

发布时间：2018-02-02 09:14

本文关键词： 高强钢滑坡地震冻胀安全性　出处：《北京交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着我国天然气使用量的逐年提高,天然气埋地管线尤其是高强钢埋地管线正在长距离大跨度的敷设。管线的穿越地带,地质地貌复杂多变,地下结构及潜在灾害难以全面估计,因此天然气管线在地质灾害下破坏事故频发,造成了巨大的经济损失和能源浪费,甚至还威胁到了人们的生命安全。在众多地质灾害中,以滑坡、地震及多年冻土区的冻胀灾害最为典型。上述三种典型地质灾害均是发生较为频繁,发生过程比较剧烈,危害程度严重,极易造成管道的屈曲变形、应力集中,甚至断裂和爆炸。因此,对典型地质灾害下高强钢埋地管线的安全性进行研究,对于分析管线安全性因素的影响规律,管线敷设及后期维护都具有较大的意义。 1.根据滑坡多发地区的实际工况条件,建立了管沟开挖前和开挖后的边坡二维分析模型,研究了边坡的稳定性：建立了三维边坡加入抗滑桩前后稳定性分析模型,提出了提高边坡稳定性的方案。应用解析法对滑坡作用下管道的力学行为进行了研究；应用有限元法对滑坡作用下管道的位移变化及应力进行了计算,整理了计算结果,结果表明：滑坡灾害发生后,管线将直接受到滑坡体的冲击,伴随着滑坡体的下滑,管线将发生屈曲变形,并且随着下滑位移的增大,管线变形增大,接近屈服极限后,变形量逐渐减小。超过屈服极限,管线进入塑性变形阶段。在此基础上,研究了滑坡规模、边坡角度、场地土类型及管道埋深等因素对管线安全性的影响规律。 2.建立了三维地震作用下管道分析模型,对模型施加粘弹性人工边界及地震波谱进行计算,将计算结果进行了分析。管道的轴向应力随着地震波加速度峰值、管道的径厚比和管土摩擦角的增大而增大,随着管径的增大而减小,管道埋深的轴向应力影响不大。 3.通过对土壤冻胀机理的分析及冻胀特性试验的研究,建立了多年冻土区土壤温度场和冻胀作用下管道分析有限元模型,结合格拉线相关实际工况,对多年冻土区管道在冻胀作用下的安全性进行了研究。分析了不同温度及不同管道埋深下管线的安全性。随着温度的降低,管道的上浮位移和最大应力均增大,虽然并未达到管道的屈服极限,但是常年的温度变化和低温影响造成的应力作用却有可能使管道产生较大变形；随着埋深的增加,管道上浮位移减小,但是最大应力增大。本文对三种典型地质灾害下高强钢埋地管线的安全性进行了研究,对于上述灾害多发地区的管线敷设和后期维护均具有实际意义。
[Abstract]:With the increasing use of natural gas in China, natural gas buried pipeline, especially high-strength steel buried pipeline, is being laid over a long distance and long span. It is difficult to estimate underground structure and potential disasters, so natural gas pipeline damage accidents occur frequently under geological disasters, resulting in huge economic losses and energy waste. Among the many geological disasters, landslide, earthquake and frost heave in permafrost region are the most typical. The above three typical geological disasters occur frequently. The process of occurrence is severe and the degree of harm is serious. It is easy to cause buckling deformation, stress concentration, even fracture and explosion of pipeline. Therefore, the safety of high-strength steel buried pipeline under typical geological disasters is studied. For analyzing the influence of pipeline safety factors, pipeline laying and later maintenance are of great significance. 1. According to the actual working conditions in the landslide prone area, the two-dimensional analysis model of the slope before and after the excavation of the pipe trench is established. The stability of the slope is studied: the stability analysis model of the three-dimensional slope before and after adding anti-slide pile is established, and the scheme to improve the slope stability is put forward. The mechanical behavior of the pipeline under the action of the landslide is studied by using the analytical method. The finite element method is used to calculate the displacement and stress of the pipeline under the action of landslide. The results show that the pipeline will be directly impacted by the landslide body after the landslide disaster occurs. Along with the slide of the landslide, the pipeline will be buckling deformation, and with the increase of the sliding displacement, the pipeline deformation will increase, close to the yield limit, the amount of deformation will gradually decrease and exceed the yield limit. On the basis of this, the influence of landslide scale, slope angle, site soil type and pipeline depth on pipeline safety is studied. 2. The pipeline analysis model under the action of 3D earthquake is established, and the viscoelastic artificial boundary and seismic spectrum are calculated. The calculated results are analyzed. The axial stress of the pipeline increases with the peak of seismic acceleration, the ratio of diameter to thickness and the friction angle of pipe and soil, and decreases with the increase of pipe diameter. The axial stress of pipeline buried depth has little effect. 3. Through the analysis of soil frost heaving mechanism and the research of frost heave characteristic test, the soil temperature field in permafrost region and the finite element model of pipeline analysis under frost heave action are established. The safety of pipeline in permafrost region under frost heaving is studied. The safety of pipeline under different temperature and buried depth is analyzed. With the decrease of temperature, the floating displacement and maximum stress of pipeline increase. Although the yield limit of the pipeline is not reached, the stress caused by the annual temperature change and the influence of low temperature may cause the pipeline to produce large deformation. With the increase of buried depth, the floating displacement of pipeline decreases, but the maximum stress increases. In this paper, the safety of high strength steel buried pipelines under three typical geological disasters is studied, which is of practical significance for the laying and later maintenance of pipelines in the disaster-prone areas mentioned above.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE88

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