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81.
A study on quantifying offshore pipeline resistance during vertical penetration and axial walking is presented, based on coupled pore pressure and displacement finite element analysis with the Modified Cam Clay model. Following the validation of the numerical method against published centrifuge test results and limit analysis solutions, we present the findings of a detailed parametric study on the response of partially-embedded pipelines under vertical and axial movements, employing 2-D plain strain and full 3-D soil–pipeline models. Emphasis is put on practical findings, and on proposing simplified expressions for the estimation of the contact enhancement factor and of the equivalent friction factor, that can be used at least for preliminary design purposes. 相似文献
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地下管线综合管理系统设计与实现 总被引:1,自引:0,他引:1
地下综合管线是保障城市运行的重要基础设施,是城市各功能区有机连接和运转的“生命线”.本文针对地下管线存在的诸多问题与需求,设计了系统总体架构与开发流程,完成了地下管线空间数据模型、管点/管线数据结构及层内拓扑关系等数据库设计,建立了城市地下管线综合管理系统. 相似文献
85.
Submarine pipelines are the primary component of an offshore oil transportation system. Under operating conditions, a pipeline is subjected to high temperatures and pressures to improve oil mobility. As a result, additional stress accumulates in pipeline sections, which causes global buckling. For an exposed deep-water pipeline, lateral buckling is the major form of this global buckling. Large lateral displacement causes a very high bending moment which may lead to a local buckling failure in the pipe cross-section. This paper proposes a lateral global buckling failure envelope for deep-water HT/HP pipelines using a numerical simulation analysis. It analyzes the factors influencing the envelope, including the thickness t, diameter D, soil resistance coefficient μ, calculating length Lf, imperfection length L and imperfection amplitude V. Equations to calculate the failure envelope are established to make future post-buckling pipeline failure assessment more convenient. The results show that (1) the limit pressure difference pmax (the failure pressure difference for a post-buckling pipeline when it suffers no difference in temperature) is usually below the burst pressure difference pb (which is the largest pressure difference a pipeline can bear and is determined from the strength and sectional dimensions of the pipeline) and is approximately 0.62–0.75 times the value of pb and (2) thickness t has little influence on the normalized envelopes, but affects pmax. The diameter D, soil resistance coefficient μ, and calculating length Lf influence the maximum failure temperature difference Tmax (the failure temperature difference for a pipeline suffering no pressure difference). The diameter D also significantly affects the form of the normalized envelope. 相似文献
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AbstractThe mechanism of local scour under two vibrating pipelines is investigated numerically in this research. A sediment scour model is adopted to estimate the motion of sediment. The general moving objects model, which is dynamically coupled with fluid flow, is set up to simulate the vortex-induced vibration (VIV) of the pipeline. The sediment scour model and pipeline vibration model are verified with the previous experimental results and show good agreement. Then, the coupling effects between the pipeline vibration and the local scour are investigated numerically. The effects of G/D (the ratio of the distance between the two pipelines to the diameter of the pipelines) on the local scour and the VIV of the pipeline are examined. The results indicate that the maximum scour depth under the vibrating pipelines is much larger than the scour depth under the fixed pipelines. Due to the shadowing effect of the upstream pipeline, the maximum scour depth under the upstream pipeline is deeper than that under the downstream pipeline. The pipeline vibration magnitude is closely related to the strength of the vortex that sheds behind the pipeline. The effect of G/D on the shape and strength of the vortices that shed behind the pipelines is significant. 相似文献
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Dimitrios K. Karamitros George D. Bouckovalas George P. Kouretzis 《Soil Dynamics and Earthquake Engineering》2007,27(3):200-211
Existing analytical methods for the stress analysis of buried steel pipelines at crossings with active strike-slip faults depend on a number of simplifications, which limit their applicability and may even lead to non-conservative results. The analytical methodology presented herein maintains the well-established assumptions of existing methodologies, but also introduces a number of refinements in order to achieve a more wide range of application without any major simplicity sacrifice. More specifically, it employs equations of equilibrium and compatibility of displacements to derive the axial force applied on the pipeline and adopts a combination of beam-on-elastic-foundation and elastic-beam theory to calculate the developing bending moment. Although indirectly, material and large-displacement non-linearities are also taken into account, while the actual distribution of stresses on the pipeline cross-section is considered for the calculation of the maximum design strain. The proposed methodology is evaluated against the results of a series of benchmark 3D non-linear analyses with the finite element method. It is shown that fairly accurate predictions of pipeline strains may be obtained for a wide range of crossing angles and fault movement magnitudes encountered in practice. 相似文献
90.
探地雷达探测地下管线的能力 总被引:21,自引:0,他引:21
这是作者摘编的有关探地雷达探测管线的一些资料。通过细致的实验,从中分析管线的粗细、材质、充填物、缺损情况及天线频率、噪音等对雷达图像的影响,对今后开展城市管线探地雷达调查工作会有所帮助。 相似文献