Dynamic Response Of Buried Pipelines Research Articles

Dynamic Behavior and Parameter Characteristics of Buried Pipeline in Airports

Buried pipeline, as one of the crucial facilities of airport ground engineering, has been extensively utilized for the transportation of petroleum, natural gas, industrial wastewater, and more. However, there are significant gaps in the research on the dynamic response of buried pipelines in airports under the action of dynamic traffic loads, which severely hampers the design and engineering quality of oil transmission pipelines. This study builds a three-dimensional finite element model to simulate the action of vehicles on the pipe–soil structure with actual loads. Moreover, the current research establishes a dynamic analysis model of pipe–soil interaction to analyze the material damping and load parameters. Using the structural dynamic response equation and Rayleigh damping calculation theory, this study investigates the change law of pipe dynamic stress and influencing factors and presents the recommended values of the parameters related to the pipe–soil interaction. Results are as follows. A damping ratio of 0.05 can enhance the time lag of the dynamic response of the structure and weaken the response peak. For the Rayleigh damping parameters, the viscous damping coefficient [Formula: see text] has almost no effect on the dynamic response of the pipe–soil structure, so it can be disregarded in the calculation. With the increase of the axial weight of the traffic load above the pavement structure, the peak value of each dynamic response quantity of the pipe–soil structure and load magnitude. The suggested value of the dynamic load coefficient of the pipe–soil structure is 1.5. Lastly, the earth pressure and dynamic load coefficients are suggested to take values for different load and axle type cases.

Designing, analyzing, and experimentally verifying a uniaxial shear box for investigating the length effect of buried pipelines during soil liquefaction

During an earthquake, buried pipelines can be threatened by various factors such as fault movement, ground motion, and soil liquefaction. Among these, fault movement and ground displacement have been identified as the most direct causes of pipeline fracture and rupture, as evidenced by previous earthquake disasters. While numerous studies have focused on the failure modes and mechanisms of pipelines crossing faults, little attention has been given to the dynamic uplift behavior of buried pipelines during soil liquefaction. To address such an issue, this study designed a uniaxial shear box to investigate the dynamic characteristics of buried pipelines during soil liquefaction. The box dimensions are 3600 mm × 1000 mm × 1100 mm and can embed a pipeline specimen of 3000 mm in length for testing. The seismic input motion direction is designed to be consistent with the axial direction of the pipeline to avoid lateral input motion influence. This study used DEEPSOIL analysis software to investigate whether the response of a uniaxial shear box under conditions of dry sand and saturated sand is consistent with theoretical analysis results. In addition, a preliminary test was conducted to ensure compliance with the requirements of subsequent pipeline tests, specifically on the uplift behavior of buried pipelines. The results showed that the soil dynamic responses under both dry sand and saturated sand conditions were consistent with the DEEPSOIL analysis software results. Furthermore, the pipeline test results verified that the input motion did not generate additional forces on the buried pipeline, but did indeed trigger soil liquefaction and cause the pipeline to uplift. These findings demonstrate that the uniaxial shear box designed in this study meets the design requirements and can be used to investigate the dynamic response of buried pipelines subjected to soil liquefaction under the influence of length effects in future studies.

Dynamic Behavior and Safety Criteria of Buried Concrete Pipeline System under Blasting

In urban blasting engineering, researching the dynamic response of buried pipeline is a method for evaluating the stability of the pipeline. The dynamic response of buried pipeline under blasting includes peak particle velocity (PPV) and peak effective stress (PES) on the pipeline. This paper aims to analyze the dynamic response of the concrete pipeline with bell-and-spigot joints under a metro-connected aisle blasting, and provide a PPV safety criterion for evaluating the stability of the field concrete pipeline. This includes an analysis of the dynamic response of the concrete pipeline in the field monitoring and numerical simulation. The monitoring results reveal that the PPV is affected by the field factor, such as the explosion source distance, and it is noteworthy that the Sadovsky’s formula considering the influence of explosion source distance (data correlation coefficient—0.708) has higher accuracy in predicting the PPV compared to the original Sadovsky’s formula (data correlation coefficient—0.632). The dynamic response distribution characteristics of the concrete pipeline are analyzed based on the numerical simulation, and the results show that the PES of the joint is three times stronger than that of the barrel. A PPV safety criterion (1.43 cm/s) is provided for the site to evaluate the stability of the concrete pipeline according to the dynamic response of the pipeline joint.

Study on the calculation method and structural dynamic response of buried pipeline subjected to external explosion load based on multiphase coupling

When the buried pipeline is subjected to the external explosion load, stress and deformation will occur. When the stress and deformation value exceed a specific range, it will affect the normal use of the buried pipeline. In this paper, a multiphase coupled model of pipeline, soil and fluid within the pipeline is established. The penalty function coupling method is used to describe the load between soil and pipeline and the fluid within the pipeline. By specifying the boundary conditions of the coupled system, the multiphase coupled global solution variational principle function of the soil-pipe-fluid is derived. According to the established multiphase coupled calculation method, the numerical simulation analysis of the response of pipeline to external explosion is carried out. The maximum error of the experimental and numerical simulation results is about 5%, which verifies the accuracy of the multiphase coupled calculation method. The soil-pipeline-fluid multiphase coupled numerical calculation model is established to analyze the response of the buried pipeline under the external explosion load. The results show that during the explosion shock wave propagating in the soil, the peak value of the explosion pressure in different positions in the soil of the gas pipeline is greater than that of the oil pipeline. As for the structural response, the maximum radial displacement value of the oil pipeline is reduced by 3.83 mm compared with the gas pipeline, the maximum stress value is reduced by 3.75%. The maximum radial displacement value of the pipeline with a fluid velocity of 1.5 m/s is 2.65 mm larger than that of the pipeline with a fluid velocity of 1 m/s, and the maximum stress value is increased by 5.72%. The deformation resistance and explosion resistance of the oil pipeline are both stronger than that of the gas pipeline. The higher the fluid velocity, the weaker the pipeline's resistance to deformation and explosion will be.

Dynamic Response Analysis of Buried HDPE Pipes under Vibration Compaction Considering the Influence of Buried Depth and Filling Modulus

During pavement construction, the gravity load and vibration excitation from vibratory rollers can seriously affect the safety of underground pipelines. However, research on the dynamic response of buried pipelines under the action of large vibration rollers is rarely reported. Therefore, the dynamic response of a high-density polyethylene (HDPE) double-wall corrugated pipe under a vibratory roller was studied via field testing and a three-dimensional nonlinear finite-element model was established. This model was used to analyze the influence of filling property and vibration frequency on the dynamic response of an HDPE pipe under a vibration load from a vibratory roller. The results reveal that with the increase of compaction times, the backfill soil keeps changing between over-compaction (loose) and compaction states, and the pipe top pressure also keeps changing. Moreover, at a shallow burial, the pipe top pressure is more obvious when the compaction degree changes. The elastic modulus of filling soil within a certain range can effectively reduce the stress deformation of the pipeline under vibration compaction. However, when the elastic modulus of filling soil exceeds 10 times the initial elastic modulus, the deformation of the pipeline becomes greater than the initial value.

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 buried pipelines in randomly structured soil

Buried pipelines in soil undergoing ground vibrations respond by simple kinematic interaction and essentially follow the motion of the surrounding ground. More specifically, the strains that develop in the soil are imparted to the outer surface of the pipeline, which is the celebrated Newmark assumption dating from the 1960's that appears in design codes for pipelines. Of course, this assumption is invalid if the pipeline has bends and other geometric discontinuities. Furthermore, there remains the basic question of modeling the surrounding soil, which is a complex, two-phase medium with an inhomogeneous and anisotropic composition. In this work, we examine the dynamic response of a continuous pipeline by employing the waveguide model from classical elastodynamics. This implies that the pipeline is a continuously supported, beam-type structural element with distributed mass undergoing both axial and flexural vibrations. In here, we retain the influence of the axial vibrations on the flexural vibrations and work with a coupled system of two partial differential equations. The end boundaries of the pipeline are assumed to be fixed at a large distance from its center. We first examine the eigenvalue problem and then focus on the transient vibrations of the pipeline to support motion. In order to account for the complex composition of the ground, the soil impedance is converted into a random variable. Assuming uniform, Gaussian and log-normal distributions, we use Monte Carlo simulations to generate sample values for the soil impedance and compute the statistics (mean, variance and skewness) for the eigenvalue problem. Once the statistics of the eigenproperties of the buried pipeline example are recovered, the validity of the assumption that the soil is a deterministic medium is discussed.

Comparative study of analytical and numerical evaluation of the dynamic response of buried pipelines to road-cut excavation blasting

ABSTRACTThis study develops a mathematical model of buried pipelines subjected to surface blast loading based on the theory of beam on elastic foundation. The Fourier transform, a mathematical formula that converts the time domain of the problem to the frequency domain, was used in order to solve a fourth-order non-homogeneous partial differential equation. Transforming the solution back to the time domain, the blast-induced Peak Particle Velocity (PPV) of the pipeline can be calculated. In addition to the mathematical model, a three-dimensional finite element model has been established, thereby drawing a comparison between analytical and numerical results. It can be concluded that the analytically calculated PPV values are found to be higher than the corresponding numerical values. Lastly, the safe distance from the pipeline to blast source and the maximum allowable ANFO explosive weight for two types of rock have been presented in the form of graphs by imposing a limit of 50 mm/s for PPV. This comparative study has investigated the effect of road-cut excavation blasting on pipelines buried under only two types of rock mass. However, it can be used for different types of rock and explosives, mainly thanks to the comprehensiveness of the analytical solution.

Monitoring the Dynamic Response of a Buried Polyethylene Pipe to a Blast Wave: An Experimental Study

Although the use of polyethylene (PE) pipelines has become increasingly widespread in recent years, few studies have addressed their seismic design and ability to withstand blast waves. In order to establish their seismic capacity, the dynamic response of buried pipelines subjected to blast waves must be explored in depth. Here, we studied the dynamic response of PE pipes situated near an explosive source. Time histories of dynamic strains were measured by conventional strain gauges after simple waterproof treatment, and pipe and ground vibration velocity curves were obtained. Based on the experimental data, the attenuation law of the peak strains under the conditions of different charge masses and blast center distances was analyzed, and the spectrum characteristics of strain, velocity of the pipe, and ground velocity were studied. The results revealed that a large hoop strain on the PE pipes was produced due to the local impact near the explosive source. We found that peak hoop strain (PHS) or peak axial strain (PAS) had a power attenuation relationship with the scaled distance, and this relationship could also be derived by dimensional analysis. The average frequency of strains had the same attenuation form as the charge mass, which was between 10 Hz and 50 Hz. Additionally, the vibration of the pipe showed a low frequency. We also determined that the attenuation of the average frequency of pipe and ground vibration velocity was closely related to the charge mass and the scaled distance. Pipe peak vibration velocity (PPVV), ground peak particle velocity (GPPV), and the peak dynamic strain of pipe were highly positively correlated, which verifies the feasibility of using GPPV to characterize pipeline vibration and strain level. Thus, a blasting criterion of 10% minimum request strength (MRS) for PE pipe was proposed, which means that the additional PHS or PAS of the dangerous point must be less than 10% MRS, and we also propose limiting the safety distance–charge mass for blasts near buried PE pipelines by the criterion. Some results in this paper can serve as the basis for future in-depth theoretical research.

Study on Dynamic Strain Regularity and Influencing Factors of Shallow Buried Metal Pipe under Collapse Impact Load

With the combination of model experiment and numerical simulation, we explore the effect of collapse height, weight, and pipe-soil stiffness ratio on dynamic strain of shallow buried metal pipe under the collapse impact load. By analyzing the strain at different measuring points of the buried pipeline, the strain law of the buried pipeline under the collapse impact load is obtained. Based on the range analysis and variance significance analysis, it was found that the pipe-soil stiffness ratio has a more significant impact on the dynamic strain of the buried pipeline under impact compared to the collapse height and the weight. Then, the numerical simulation method was used to further analyze the effect of pipe-soil stiffness ratio on the dynamic response of buried pipelines; the following conclusions are drawn: As the stiffness ratio of pipe-soil increases, the plastic stress and strain of the buried pipeline will decrease, and influence of the pipeline by the collapse impact is slighter.

Analytical solution of the dynamic response of buried pipelines under blast wave

Several studies have addressed the effect of blasting on buried pipelines, but none of them has used an analytical method to find the beam deflection under the effect of the blast wave. In this study, the pipeline is modeled as beam, and its displacements are calculated under a blast wave equivalent dynamic load. Mathematical modeling of the problem results in a fourth-order inhomogeneous partial differential equation, which has to be solved so that the pipe displacements and the peak particle velocity could be found. Since it is not possible to solve the problem in the time domain, the problem is converted to the frequency domain by a Fourier transform, and then the differential equation is solved. Finally, the solution is transformed back to the time domain, and the maximum particle velocity is calculated using a computer code.

Gurtin-Type Quasi-Variational Principle of Buried Pipelines Dynamics

Because earthquakes may cause severe damage to buried pipelines, it is important to study dynamic response of buried pipelines. For dynamic response problem of buried pipelines, variational method is the suitable method. In the paper, Gurtin-type quasi-variational principle of buried pipelines dynamics is established by convolutional variational integral method, which is theoretical foundation of finite element method for solving buried pipelines dynamics problems.

Non-axisymmetric dynamic response of buried orthotropic cylindrical shells under moving load

The dynamic response of buried pipelines has gained considerable importance because these pipelines perform vital role in conducting energy, water, communication and transportation. After realizing the magnitude of damage, and hence, the human uncomfort and the economical losses, researchers have paid sincere attention to this problem. A number of papers have appeared in the past which discuss the different aspects of the problem. This paper presents a theoretical analysis of non-axisymmetric dynamic response of buried orthotropic cylindrical shell subjected to a moving load along the axis of the shell. The orthotropic shell has been buried in a homogeneous, isotropic and elastic medium of infinite extent. A thick shell theory including the effects of rotary inertia and shear deformation has been used. A perfect bond between the shell and the surrounding medium has been assumed. Results have been obtained for very hard (rocky), medium hard and soft soil surrounding the shell. The effects of shell orthotropy have been brought out by varying the non-dimensional orthotropic parameters over a long range. Under these conditions the shell response is studied in axisymmetric mode as well as in the flexural mode. It is observed that the shell response is significantly affected by change in orthotropic parameters and also due to change of response mode. It is observed that axial deformation is large in axisymmetric mode as compared to that in flexural mode.

Transverse Vibration of Buried Pipelines Due to Internal Excitation at a Point

This paper is concerned with the dynamic response of buried pipelines due to excitation located inside the pipe. This work is important for application to techniques that employ vibration to investigate pipeline support conditions using a vibrating pipe inspection device. It also has application to the detection of spanning in off-shore pipelines.Three different theoretical models are developed and investigated. The first model employs the theory of elasticity, the second is a finite element model and the third is a beam-on-elastic Pasternak foundation. Good agreement between these models is demonstrated. The beam-on-elastic Pasternak foundation model is successfully used to predict ‘signatures’ of the pipe-soil response that characterize soil support features, such as hard and soft supports.

Dynamic Response of Buried Pipelines—An Elasticity Solution

Abstract This paper presents a theory of elasticity solution of the axisymmetric steady-state dynamic response of a buried pipeline excited by a plane longitudinal wave (P-wave) traveling in the surrounding soil. Both the pipeline and the ground have been assumed to be linearly elastic, homogeneous and isotropic. Linear elasticity equations of motion have been solved simultaneously for the pipeline and the surrounding soil. A perfect bond between the pipeline and the ground has been assumed. The midplane deformations of the pipeline have been plotted against the nondimensional wave number of the incident wave, for different soil condition and angle of incidence of the wave. The results of the present work have been compared with those found by using a shell theory which includes the effect of shear deformation and rotary inertia. It has been found that excellent agreement exists between the results obtained by the two approaches. The present work concludes that the use of shell model, including effects of shear deformation and rotary inertia, is justified for the analysis of dynamic response of buried pipelines excited by seismic waves traveling in the ground.

Response of an elastically embedded rod subjected to periodically spaced longitudinal forces

The dynamic response of buried pipelines to earthquakes is best expressed in terms of dynamic amplification factors, i.e. as the ratio of dynamic to static response. In the present paper, the system is represented by a model consisting of a cylindrical rod of radius a embedded in an elastic medium. The required interacting static response of rods subjected to periodic longitudinal forces at intervals L and acting in alternate directions, is obtained. Such a load pattern corresponds to the incoherent motion occuring in earthquakes.The static displacements and interacting stresses of the system are established and are found to be dependent, for a given medium, on the ratio of stiffness of the medium and rod as well as on the aspect ratio a/L. Numerical results are presented for a series of rods governed by the above non-dimensional parameters.