Dynamic Response Of Pipeline Research Articles

Dynamic response and safety assessment of inner‐wall corroded concrete pipeline in service subjected to blasting vibration

AbstractBuried pipelines in urban area are prone to corrosion defects for many years. Ensure the safety of buried corrosion pipelines is a key concern during tunnel blasting excavation. Based on the blasting engineering along Shenzhen Metro Line 12, the field test of full‐scale concrete pipeline adjacent blasting was implemented. The dynamic response of concrete pipeline induced by blasting vibration was analyzed by using the dynamic finite element numerical simulation method, and the reliability of numerical simulation was verified by the field monitoring data. On this basis, considering the corrosion defect morphology of pipeline, the distribution characteristics of peak particle velocity and peak effective stress of concrete pipeline with different corrosion depths, corrosion widths, and corrosion lengths induced by blasting vibration were discussed. The parameter analysis method was used to research the influence of corrosion morphology parameters on the dynamic response of the pipeline, and the corrosion depth of the inner‐wall of the pipeline was defined as the main control parameter of the dynamic response. According to the failure criteria of concrete materials, the safety criterion of corroded concrete pipelines with different service years subjected to blasting vibration was established.

An innovative solution for the dynamic response of buried pipelines in layered transversely isotropic soil under pavement structures

The interaction between a buried pipeline and the surrounding soil under dynamic loads has attracted the attention of researchers. In this paper, a modified scaled boundary finite element method (SBFEM) based on the mechanical derivation method is proposed to determine the dynamic response of the buried pipeline in layered transversely isotropic soil under the pavement structure. A similarity line that replaces the similarity centre of the conventional method was introduced in the modified SBFEM. As a result, a new stiffness matrix equation was established for layered soil. The accuracy of the proposed algorithm was confirmed through numerical examples. Therefore, the effects of the thin layer elastic modulus, pipeline cushion thickness, pipeline radius, pipeline buried depth, and location of the cavity under the pipeline on the dynamic response of pipelines were studied under dynamic pavement loads. The parametric analysis gives a reliable numerical solution for engineering problems.

Dynamic response of pipelines under impact and harmonic loading

This study deals with the dynamic response of pipelines under flexural loads. The flexural loads can be harmonic (transmitted by pumps, compressors, etc.) or transient (seismic loads, foundation movement and impact for pipeline inspection). Existing works provide solutions in the frequency domain or in the time domain. However, the methods in the frequency domain cannot simulate the pipeline response under transient loading and the methods in the time domain are mostly based on approximate techniques. An exact solution for pipeline response under transient and harmonic loads is proposed. The modelling of fluid−pipe interaction under transient loading conditions yields coupled equilibrium and motion partial differential equations. Decoupling of the above equations is possible; however, it increases the order of the differential equations from 1 to 4. A system of eight first-order coupled partial differential equations is decoupled, yielding eight fourth-order ones. Integral transforms are used to achieve an analytical solution. The methodology is based on double integral transforms. The implementation of a finite sine Fourier transform for the spatial variable and the analytic inversion of the Laplace transform in the time domain are new. Results are provided for pipelines subjected to impact and harmonic loads.

Parametric study for underwater blast-induced pipeline response embedded in marine sediments

Blast response of submerged pipelines has been a research focus in recent years. In this article, a three-dimensional numerical model is established to investigate dynamic response of pipelines due to underwater explosion. The u–p approximation is integrated into finite element method (FEM) to simulate pore water effect in the seabed. Numerical continuity between hydraulic pressure in the flow field and pore pressure in the marine sediment is guaranteed to realize the blast response of submerged pipelines in ocean environment. Both fluid–structure interaction (FSI) and pipeline–seabed interaction (PSI) have been considered in the proposed model simultaneously. A comprehensive parametric study is carried out after validation of the present model with test data from underground explosion and underwater explosion, respectively. The effect of embedment depth, TNT equivalent, stand-off distance, pipeline diameter, and pipeline thickness to blast response of the submerged pipelines is investigated based on numerical results. Variation of deformation patterns and stress distribution of the pipeline with various installation and structure parameters has been illustrated and discussed to facilitate engineering practice.

Damping Effect on the Wave Propagation in Carbon Steel Pipelines Under Fluid Hammer Conditions

A sudden reduction of the fluid flow yields a pressure shock, which travels along the pipeline with a high-speed. Due to this transient loading, dynamic hoop stresses are developed that may cause catastrophic damages in pipeline integrity. The vibration of the pipe wall is affected by the flow parameters as well as by the elastic and damping characteristics of the material. Most of the studies on dynamic response of pipelines: (a) neglect the effect of the material damping and (b) are usually limited to harmonic pressure oscillations. The present work is an attempt to fill the above research gap. To achieve this target, an analytic solution of the governing motion equation of pipelines under moving pressure shock is derived. The proposed methodology takes into account both elastic and damping characteristics of the steel. With the aid of Laplace and Fourier integral transforms and generalized function properties, the solution is based on the transformation of the dynamic partial differential equation into an algebraic form. Analytical inversion of the transformed dynamic radial deflection variable is achieved, yielding the final solution. The proposed methodology is implemented in an engineering example; and the results are shown and discussed.

Dynamic Response of Pipelines Buried in Back-Filled Trenches

Dynamic response of pipelines buried in a back-filled rectangular trench in a semi-infinite medium has been investigated. The pipelines are modeled as long cylindrical shells of small thickness. By using the boundary integral representation and finite element method, we have studied the three-dimensional response to account for either plane P or SV wave incident at an arbitrary angle to the pipe-axis. Numerical results are presented for the normal displacements, displacements along pipe-axis, and the hoop stresses in the pipe wall. It is shown that the response depends critically on the back-filled material as well as on the directions of propagation of the incident waves.