金属管线对探地雷达探测道路地下病害的干扰

探地雷达作为一种电磁波反射类的方法,在城市道路地下病害探测中受金属管线干扰较大。为分析地下病害位于金属管线的不同部位的干扰问题,从探地雷达的分辨能力出发,推导出金属管线侧方探测干扰区的基本计算公式,结合正演数值模拟和实际同等规模建设的物理模型,对金属管线周边干扰区进行了验证试验。结果表明:金属管线两侧一定跨度范围内,存在一垂直高度为一个电磁波波长的干扰区,当地下病害位于该区域时,其反射波组受干扰,不利于病害属性和规模的解释,而当地下病害位于金属管线的正下方时,其不能被目前常用的单体式天线探测到。     

Recovery Behavior of the Propagating Buckle on Elastic Structures

Based on the beam system model used by Chater, Hutchinson and Neale (1982), the recovery behavior of propagating buckle on elastic structures is first found out from the computational results. As the representative of some elastic structures, the Chater-Hutchinson-Neale model indicates that once the buckle meets arresters, unlike the case in submarine pipelines, it will be reflected back to continue its propagation in a negative phase or a negative direction. The pressure which maintains the negative propagation, however, is as same as that required for the positive propagation. This fact has been examined in the experiment of the bulge propagation on a long elastic latex tube. The present discovery greatly supports the hypothesis that the buckle propagation coresponds to the coexisting phase of structures.     

A seismic design method for subsea pipelines against earthquake fault movement

As there are no specific guidelines on design of subsea pipelines crossing active seismic faults, methods for land buried pipelines have been applied to. Taking the large seismic fault movement into account, this paper proposes improved methods for seismic designs of subsea pipelines by comprehensively investigating the real constraining of soil on the pipelines, the interaction processes of soil with the pipeline, the plastic slippage of the soil, and the elastic-plastic properties of the pipeline materials. New formulas are given to calculate the length of transition section and its total elongation. These formulas are more reasonable in mechanism, and more practical for seismic design of subsea pipelines crossing active faults.     

Model test based soil spring model and application in pipeline thermal buckling analysis

The buckling of submarine pipelines may occur due to the action of axial soil frictional force caused by relative movement of soil and pipeline, which is induced by the thermal and internal pressure. The likelihood of occurrence of this buckling phenomenon is largely determined by soil resistance. A series of large-scale model tests were carried out to facilitate the establishment of substantial data base for a variety of burial pipeline relationships. Based on the test data, nonlinear soil spring can be adopted to simulate the soil behavior during the pipeline movement. For uplift resistance, an ideal elasticity plasticity model is recommended in the case of H/D (depth-to-diameter ratio)>5 and an elasticity softened model is recommended in the case of H/D≤5. The soil resistance along the pipeline axial direction can be simulated by an ideal elasticity plasticity model. The numerical analyzing results show that the capacity of pipeline against thermal buckling decreases with its initial imperfection enlargement and increases with the burial depth enhancement.     

Behavior of marine pipelines under seismic faults

A new study investigates an unburied offshore “snaked” pipeline behavior under various types of seismic faults. The snaking of the pipeline is caused by the thermal/pressure expansion and soil friction. The snaking takes place at a certain distance from the pipeline's unrestrained end and gradually increases towards the restraint. It is shown that longitudinal seismic faults have less effect on a straight pipeline than a snaked pipeline. The new seismic analysis demonstrates that an increase of ground displacement causes a very small change in bending and longitudinal stresses. The new approach results in a safe, subsea pipeline construction and operation with a significant cost reduction.     

大直戏薄壁管线浅海铺设的空间形态和应力分布数值计算与分析

利用非线性大直径薄壁铺设变形和应力计算模型，对水中铺设的典型工况进行了空间形态和应力分布的模拟计算，分析了实际工程中的两种铺设方案－采用刚性托架和托架船辅助铺设及仍采用刚性托铺设，并计算了水中铺设时的纵向水流对铺设时的管线空间形态和应力分布的影响，对计算结果作了定性的分析，提出了相应工况时该管道铺设工程中应该注意的考虑的问题。     

埕岛油田海底管道安装应力计算方法的研究及应用

海底管道的施工质量直接关系到海底管道能否长久地安全运行。对施工期间各种环境荷载、施工荷载作用下的海底管道在力和变形进行计算,分析和监控、是确保底管道施工质量的不可缺少的重要手段。本文通过计算实例对浮拖法敷设海底管道安装计算分析的方法作了研究,并对胜利海洋石油开发公司与天津大学合作研究开发的涨底管道安装分析软件在胜利岛油田海底管道工程建设中的应用作了介绍。     

Experimental Study of Hydrodynamic Loading on Submarine Composite Pipelines under the Action of Waves and Current

- This article is aimed at the experimental study of the hydrodynamic loading induced by waves and current acting on the JZ 20-2 submarine composite pipelines. The corresponding hydrodynamic coefficients obtained in this experimental study can be applied to engineering projects.     

管道中天然气水合物的形成对"西气东输"的影响

"西气东输"是我国距离最长、口径最大的输气管线,将成为贯穿我国腹地的大动脉.管线位处北纬的寒冷环境,温度低、压力大,形成的天然气水合物对管线的堵塞及其分解引起的危害是不容忽视的问题.本文从天然气水合物的结构出发,对它产生条件和分解方法进行了研究,给出了管线中天然气水合物的抑制方法,并提出了实施过程中可能出现的环境问题.     

带损伤海底石油管线的安全评估

综述了国际上在管线损伤方面的研究工作，供我国开展在役管线的安全评估时参考。