Deformation Of Pipeline Research Articles

Scaling of dynamic bending response of metal tube under impact loading considering strain rate effects

Based on the engineering background of the heavy drop impacting metal tube, the scaling law without considering the strain rate effects was deduced according to the π theorem. Then, the scaling law considering the strain rate effects by modifying the initial velocity was derived. Finally, two scaling laws are compared by experiments and numerical simulation. The following conclusions are drawn: the scaling law without considering the strain rate effects is completely self-contained. However, if the strain rate effects are taken into account, the scaling law will be distorted. The scaling law for modifying the initial velocity can make the model test more accurately reflect the prototype test. The model test guided by the modified scaling law fits better with the prototype in terms of pipeline deformation, effective strain, effective stress, and particle vibration velocity, and the error is reduced by more than 50%.

Interaction Analyses between Existing Pipeline and Quasi-Rectangular Tunneling in Clays

Previous researches about geoenvironmental disturbance caused by tunneling have mainly concentrated on the influences of circular tunnel construction, but minimal interesting is given to the quasi-rectangular shield tunneling. Considering the convergence deformation model for quasi-rectangular shield tunneling at excavation face, the simplified closed-form solution is put forward to evaluate the deformation behavior for underground pipeline caused by quasi-rectangular shield tunneling. Firstly, the free-field displacements induced by the quasi-rectangular shield excavation are estimated by the point source technique. Secondly, characterized by the Winkler foundation, the free-field displacements are applied to the pipeline structures and a simplified analytical solution is obtained for analyzing the deformation of adjacent pipeline induced by quasi-rectangular tunneling. Through the analyses of engineering cases, the comparison between analytical solution for the free-field deformation and measured data is conducted. Meanwhile, the numerical simulation technique and the physical modelling tests for the pipeline deformation are utilized to compare the simplified analytical results. In addition, the primary parameters are conducted for the interaction mechanics between quasi-rectangular tunneling and existing pipeline, such as the pipeline diameter, the geometry size and centerline depth of pipeline and tunnel, the structural physics modulus of pipeline, the compressive modulus of ground, and the ground loss parameter. The results of this study are of great significance for exploring the geomechanical effects induced by quasi-rectangular shield tunneling in clays.

Mechanical Damage and Response of a Buried Steel Pipeline Under Subsurface Explosion Load

Abstract Subsurface explosions seriously threaten the safety and reliability of buried oil and gas pipeline. In order to investigate the mechanical responses of buried steel pipeline under subsurface explosion load, a numerical model of pipeline–soil coupling under explosion load was developed. Stress, displacement, plastic deformation, and local buckling of the buried pipeline were investigated. The effects of trinitrotoluene (TNT) magnitude, pipeline diameter-thickness ratio, pipeline's buried depth, explosive depth, and explosive offset on the mechanical response of pipeline were studied. The results show that the response time of buried pipeline is very short under the explosion load. There is a dent appearing on the pipeline section toward the exploding location. Cross-sectional area of the pipeline decreases along the time during the explosion, but it gradually increases for the elastic recovery. Pipeline's deformation and total energy increase gradually with the increasing of trinitrotoluene magnitude or diameter-thickness ratio, but they decrease with the increasing of the buried depth or explosive offset. With the explosive depth increases, the pipeline's plastic deformation first increases and then decreases. The pipeline's energy curve can be used to determine the buckling state under explosion load. The empirical formulas of the maximum strain and dent rate for buried pipelines have been obtained and can be used for the pipeline safety assessment.

Structural characteristics of twin-screw compressor rotor based on thermal-solid coupling method

High-temperature gas will cause stress and deformation of the rotor during the operation of the twin-screw compressor, which will affect the structural performance of the screw rotor. Based on the CFD/CSD coupling solution technology, the method of thermal solid numerical analysis is developed. The fluid control equations are time-averaged differential equations, and the turbulence model is a two-equation Realizable K-ε model. The thermal deformation and thermal stress of the rotor are obtained by solving the structural static equilibrium equation. The reliability of the proposed method is verified by solving the thermal deformation of the L-shaped large-diameter buried pipeline. Finally, the thermal deformation and thermal stress of the rotor under different exhaust pressures and different speeds are mainly studied. Through simulation analysis, the variation law of rotor deformation, stress and modal under different temperature fields of the compressor is obtained, which can provide a certain theoretical reference for the compressor structural design and optimization.

Dynamic torsion of underground pipeline due to sudden rotation of foundation fragment

In the paper, we study the strength of underground pipelines, which are laid through tectonic faults, and, as a consequence, are operated in difficult mining and geological conditions. In such dangerous areas, in addition to the standard pressure load of the transported product, the pipe is subjected to additional effects from the movements of the inhomogeneous, often damaged, foundation. Predictably, the most dangerous situation is when such movements are transient. The paper aims at developing a model to describe the non-stationary process of pipeline deformation on a damaged foundation caused by sudden mutual rotations of rock blocks around the pipe axis. The dynamics of the pipeline was studied in a linear formulation, modeling it with a rod with a tubular cross-section. The momentless theory of cylindrical shells and the energy concept of strength were used while considering the issues of ultimate equilibrium. The soil backfill was considered as Winkler's elastic layer. Local continuity disturbances of the foundation are described by a sudden rupture of the angle of rotation of its fragment. This approach, developed on the problems of statics, makes it possible to dynamically assess the strength of the underground pipeline not by external load from the soil, which is usually unknown, but by the observed or predicted parameters of the fault edges. We formulated an initial-boundary value problem for a hyperbolic differential equation of torsion with a discontinuous right-hand side. Based on the analytical solution of the problem, constructed in the form of squares from Bessel functions, the influence of the sudden rotation of the foundation fragment around the pipe axis on the stress-strain state of the pipeline is studied. Plots of the space-time distribution of the angle of rotation, angular velocity, torsion deformation and equivalent stresses of von Mises in the prefrontal and postfrontal areas are constructed. It is established that considering dynamic effects leads to an increase in the torsion deformation maxima and the equivalent stress in the pipe wall in comparison with the case of static perturbation.

Hydrostatic Test and Simulation Verification of Pipeline with Carbon Fiber Repair

We specially designed a hydraulic blasting test for the repair capability of carbon fiber composite materials on pipelines containing defects. In the water pressure test, the location of the pipeline pressure rupture did not appear in the repair area, and the amount of pipeline deformation in the repair area was small. A finite element simulation of the compression process was carried out. After simulation verification, it was found that the ultimate pressures of the two were basically the same, and in the limit state, the stress value of the carbon fiber composite material in the repair area did not exceed its tensile failure strength. It is concluded that carbon fiber composite materials can effectively repair pipeline defects and restore the pressure bearing capacity of the defects.

Deformation of Pipelines Induced by the Construction of Underlying Twin-Tunnel

Deformation of Pipelines Induced by the Construction of Underlying Twin-Tunnel

Thermomechanical Modeling of a Sleeve Rehabilitation System for Pressure Pipes

Abstract The thermomechanical modeling of a sleeve rehabilitation system for pressure pipes is studied including temperature effect on system behavior. The rehabilitation system consists of a multicylinder axisymmetric layer system, with an intermediate layer of epoxy resins and two outer steel covers that are longitudinally welded forming a sleeve. The analysis is conducted over several stages; initially, the incidence of temperature on the rigidity of three types of resins currently available on the market is experimentally evaluated. Then, nonlinear relationships between rigidity and temperature are established from the evaluation of the resins, which are typical of an inhomogeneous material. The resins exhibit a significant loss of rigidity with temperature, generating a risk of delamination that could drastically reduce the effectiveness of the rehabilitation system in the event of possible temperature rises. An analytical model was developed to calculate contact pressures between the resin layer and the external sleeve, internal pipeline displacements, stresses, and deformations. Finally, contour plots were developed for different temperature, pressure levels, and pipe thickness as a graphics tool to predict pipeline failure due to plastic deformation or rupture.

Using distributed fiber optic sensors to monitor underground infrastructure

Abstract The development of monitoring system technology enables more accurate measurement at regular intervals of many parameters affecting the safety and proper functioning of underground infrastructure. Means of monitoring underground infrastructure using distributed fiber optic sensors (DFOS) are presented in this paper. DFOS use is developing rapidly and investment is increasingly visible internationally – examples are given. The preliminary results are also presented of research on the application of DFOS for monitoring pipeline deformation and thin-walled GRP (FRP) panels used in the renovation of existing sewage networks.

The influence of erosion voids on the longitudinal behaviour of a jointed large-diameter reinforced concrete pipeline

Centrifuge tests were performed to investigate the influence of erosion voids on the longitudinal behaviour of a buried 1400 mm diameter reinforced concrete pipeline with gasketed bell-and-spigot joints. A novel technique was developed to simulate the formation of an erosion void straddling a pipe joint. After void formation, repeated loading was applied to the ground surface above the joint. Voids at different positions were investigated, including the haunch and invert straddling the joint, and the results are compared with the test without voids. The test results highlight the dominant influence of erosion voids on the longitudinal deformation of the jointed pipeline. The invert void straddling the joint imposes the most unfavourable condition, with significant joint rotation developing under repeated surface loading, which would eventually cause joint failure. The influence of erosion voids on the circumferential and longitudinal bending moments of the pipe barrel at different cross-sections was also investigated.

Assessment of internal pressure effect, causing additional bending of the pipeline

Article justifies accounting for internal pressure effect in the pipeline, causing additional bending of the pipeline. According to some scientists, there is an erroneously used concept of the equivalent longitudinal axial force (ELAF) Sx, which depends on working pressure, temperature stresses, and joint deformations of pipelines with various types of soils. However, authors of the article use ELAF Sx concept at construction of mathematical model of stress-strain state (SSS) for complex section of the trunk pipeline, and also reveal it when analyzing the results of calculating the durability and stability of the pipeline. Analysis of SSS for calculated section of the pipeline was carried out for two statements of the problem for different values of operation parameters. In the first statement, effect of internal pressure causing bending of the pipeline is taken into account, and in the second it is neglected. It is shown that due to effect of ELAF Sx at p0 = 9.0 MPa, Dt = 29 °C extreme value of bend increases by 54 %, extreme values of bending stresses from span bending moment increase by 74 %, and extreme value of bending stresses from support bending moment double with regard to corresponding SSS characteristics of the pipeline. In case of neglecting the internal pressure effect causing additional bending of the pipeline (second statement of the problem), error in calculating the extreme value of bend is 35 %, extreme value of bending stresses from span bending moments is 44 %, and extreme value of bending stresses from support bending moments is 95 %.

Safety analysis of gas pipeline under vehicle load

With the rapid development of the economy, construction has been carried out throughout the country. Natural gas pipe network is widely distributed, so construction vehicles driving on the ground with buried gas pipelines often exert pressure on the pipelines. If the pipelines are not buried deep enough, the pipeline material strength is poor or the construction quality is not qualified, the pipelines may be deformed or even broken when they are under high pressure. In this paper, the influence of excavator and heavy truck load on gas pipeline is analyzed by using finite element software. The results show that the construction vehicle propagates pressure load through the soil, which causes the local concentrated pressure above the pipeline and causes the pipeline deformation. In view of the safety hidden danger caused by the third party construction vehicles, this paper also gives some Suggestions and measures.

Method for determining technological parameters to repair pipeline with out-of-spec curvature

When performing in-line inspection of trunk pipelines, line pipe sections are detected with curvature exceeding the values required by specifications. To prepare a repair work project that entails bringing the pipeline into the standard conditions, it is necessary to determine the technological parameters of the repair. The corresponding technique is known for cases of moving an initially straight pipeline. The authors of the paper have developed the method for determining the technological parameters to repair pipeline with out-of-spec curvature of the axis. The method is based on simulation of pipeline deformation with the initial curvature of the axis, taking into account the actual operating conditions of the pipeline and in-line inspection data. Examples of calculations of repair technological parameters and stress-strain state of pipeline sections with out-of-spec curvature are given. The simulation results confirm the possibility for applying this method to assess the technological parameters of repair, the length of trench excavation, the size and limits of the pipeline additional burying or lifting, and to determine the stress-strain state of the pipeline section under repair during and after repair work.

Numerical analysis of offshore pipe-lay subjected to environment-induced non-uniformly distributed follower loads

The global pipeline configuration in installation is mainly governed by static lay effects, which, besides pipeline material properties and geometry, primarily depend on its submerged gravity and horizontal tension provided by the laying vessel. These loads are insensitive to the pipeline deformation and preserve both their values and their directions as the pipeline deforms throughout the whole course of the installation. However, these static lay effects may be significantly amplified by the environmental factors, primarily caused by astronomical ocean tides, such as water level variations and hydrodynamic currents. These factors may substantially affect pipeline configuration and significantly increase the internal forces. Moreover, the loads caused by the ocean currents are of a fundamentally different nature comparing to the gravity and the lay tension. They are nonuniformly distributed along the pipeline axis and change both their values and their directions following the nonlinear deformation of the pipeline throughout the course of the laying process. This paper presents a feasible numerical method for a structural analysis of a pipeline static configuration in installation, subjected to non-uniformly distributed, position- and orientation-dependent loading and water level variations. The method considers the whole pipeline, which is partially suspended and partially laid-on a seabed, as a single continuous segment, and is valid for both S-lay and J-lay techniques. The numerical solution adopts finite difference discretization of the pipeline, and proceeds sequentially in an incremental way, following the actual pipe-lay process. At each length increment a new consequent equilibrium configuration is being assessed by consistent minimization of the updated total potential energy, which allows for considering follower loads, which change both their values and their directions following the nonlinear deformation of the pipeline. Representative parametric study is conducted to demonstrate the feasibility of the method. Considered the effects of a power-law current velocity depth-varying profile and water level variations. The method compared to Abaqus/AQUA and its convergence is validated through finite difference grid refinement. The proposed technique presents a less time-consuming alternative to the available special-purpose commercial software that imposes the use of cumbersome Graphical User Interface for a model definition and a result processing.

Analysis on Mechanical Properties of the Buried Pipeline Considering Pipe-soil Interaction

Mechanical deformation of buried pipeline under vertical load is the result of pipe-soil interaction. In order to reveal the necessity of pipe-soil interaction while investigating mechanical properties of buried pipeline, the ANSYS commercial software is employed to construct pipe-soil interface and simulate pipe-soil coupling effect. With the newly developed model, mechanical properties of pipe under vertical static load are analyzed. Numerical solution is subsequently compared with analytical solution. The results reveal that (1) There is maximum Von Mises stress at internal surface of pipe side under overlying load, and minimum Von Mises stress appears in the pipe shoulder at angle of about 45°to x-axis; (2) The pipe-soil interaction has significant effect on analyzing the deformation and distribution of stress of buried pipeline; (3) Vertical displacement obtained from Marston model is larger than that obtained from newly constructed numerical model; (4) The deformation of pipe is obviously constrained by backfilled earth around the pipe. For a buried pipe, especially the elastic pipe, it is necessary to consider pipe-soil interaction while analyzing its mechanical properties.

Simulation of Dynamic Effects on Trunk Pipelines Laid in Difficult Engineering and Geological Conditions

In this paper, we conduct an experimental study of pipeline deformation together with soil to analyze the stress-strain state of the pipeline and compare it with the results of computer simulation. The experimental setup is a box of OSB panels, which is filled with soil. A polypropylene pipe is laid in the ground, onto which strain gauges are attached, which transmit strain measurements to the computer. At the bottom of the box is a board that drives the ground with a jack. The dependence of stresses in the pipe on soil displacements is constructed first for a polypropylene pipe, then the stresses are converted to a steel pipe and compared with the results of computer simulation in Ansys. The discrepancy between the results is small, due to inaccuracy in the selection of models of soil behavior. Further refinement of mathematical models is planned.

An Energy Solution for Predicting Buried Pipeline Response Induced by Tunneling Based on a Uniform Ground Movement Model

The construction of shield tunnels inevitably causes displacement of the surrounding soil and additional stress and deformation of the buried pipeline. An energy solution for predicting the deformation of buried pipelines caused by tunneling is proposed in this study. First, based on the uniform ground movement model, the interval of the free displacement field of soil around the pipeline induced by tunneling is calculated. Then, we use the Pasternak model to establish the total potential energy equation of the tunnel-soil-pipeline interaction. The final settlement interval of the pipeline is obtained by solving the numerical calculation program with MATLAB. The calculation results of the energy solution are compared with the results of the centrifugal test and the reported theoretical solutions of Winkler and Pasternak, and then the applicability of the solution for predicting the pipeline response under different geotechnical conditions is verified. Combined with an engineering case, the energy method calculation results, numerical simulation results, and measured results are compared to obtain the most unfavorable position of the pipeline caused by tunneling. At the end of this study, the application steps of the proposed method in actual construction are summarized. These steps are used to predict pipeline response in order to take protective measures.

Mechanics of contact interaction and deformation of main pipelines in the conditions of extreme external actions

Formulation and solution of a task for the composite engineering-geological interaction of a pipeline and a soil are considered. Finite element method is used for numerical analysis of the task, accounting for large displacements and corresponding strains under changing boundary conditions. The capability of the limit state reaching in the pipeline with loss of form stability is shown depending on pad layer and the pipe properties. It is demonstrated also that safety maintenance could be provided by usage of ribs, formed on a pipe by a cyclic thermomechanical actions.

Safety Analysis of Pipe–Soil Coordination Deformation Affected by Mining Subsidence

In view of the deformation and failure of buried gas pipelines in coal mining process, this paper analyzes the surface subsidence characteristics of pipelines along the pipeline during the mining process based on probability integral method, establishes the critical conditions of pipeline-soil synergy deformation, and derives the influence of mining subsidence. The analytical formulas of the deformation stress of the pipeline and the axial stress generated by the friction of the pipe soil were analyzed, and the formula for determining the pipeline failure under the composite stress was summarized. The deformation and stress distribution characteristics of the pipeline were analyzed with the engineering example. The results show that the axial stress increases rapidly in the early stage of subsidence, and the growth rate decreases in the later stage. The maximum tensile and compressive stress of the pipeline was distributed in the middle of the subsidence area, and the safety evaluation of the pipeline is carried out. It indicates that the Mises equivalent stress along the pipeline is less than the yield stress of the pipeline, and the buried pipeline is in a safe state.

Mechanics of contact interaction and deformation of main pipelines in the conditions of extreme external actions

Formulation and solution of a task for the composite engineering-geological interaction of a pipeline and a soil are considered. Finite element method is used for numerical analysis of the task, accounting for large displacements and corresponding strains under changing boundary conditions. The capability of the limit state reaching in the pipeline with loss of form stability is shown depending on pad layer and the pipe properties. It is demonstrated also that safety maintenance could be provided by usage of ribs, formed on a pipe by a cyclic thermomechanical actions.