Uplift of model steel pipelines embedded in polycrystalline ice

The experimental behaviour of model pipelines embedded in polycrystalline ice is studied to improve the understanding of the behaviour of a chilled buried pipeline subjected to frost heave. Two model pipelines with slightly different radius to thickness ratios were subjected to prescribed displacement rates. Their behaviour was monitored until peak strains corresponding to current acceptable strain limits, often referred to as the wrinkling strains, were exceeded. The sizing of the model pipelines and experimental setup are described and detailed procedures on polycrystalline ice sample preparation are given. Representative core samples of polycrystallineice were tested to determine its elastic and creep properties. The observed and predicted responses of strain histories in the pipeline are compared and acceptable agreement between the responses is obtained. Key words : experimental behaviour, embedded model pipelines, polycrystalline ice, frost heave, uplift resistance, critical strain limits.

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Permafrost Hazard of MoHe-DaQing Crude Oil Pipeline

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.734-737.2659 ◽

2013 ◽

Vol 734-737 ◽

pp. 2659-2663

Author(s):

Yun Bin Ma ◽

Dong Jie Tan ◽

Hong Yuan Jing ◽

Quan Xue ◽

Cheng Zhi Zhang

Keyword(s):

Crude Oil ◽

The Other ◽

Frost Heave ◽

Permafrost Soil ◽

Buried Pipeline ◽

Soil Frost ◽

Plastic Deformations ◽

Oil Pipeline ◽

Thaw Settlement ◽

Slope Instabilities

The crude oil pipeline from MoHe to DaQing (hereafter called Mo-Da pipeline) is part of China-Russia oil pipeline. Mo-Da pipeline is the first pipeline that through high latitude cold regions of China. The pipeline is in so complicated geography environment that many kinds of permafrost hazard are easily to happen including frost heave, thaw settlement, slope instabilities, and collapse and so on. The pipeline and the permafrost act and react upon one another. On one hand, soil frost heave and thaw settlement can produce extra stresses on pipe walls, which may result in centralized stresses and plastic deformations under certain conditions, even causes pipeline faults. On the other hand, buried pipeline will disturb ambient environment and then degrade the permafrost soil and finally impact safety of the pipeline. This paper mainly introduces the permafrost hazards of Mo-Da pipeline and demonstrates some methods for monitoring the influence of permafrost.

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MECHANICAL SIMULATION AND ELECTROCHEMICAL CORROSION IN A BURIED PIPELINE WITH CORROSION DEFECTS SITUATED IN PERMAFROST REGIONS

Surface Review and Letters ◽

10.1142/s0218625x21500025 ◽

2020 ◽

pp. 2150002

Author(s):

XIAOLI LI ◽

LI CHEN ◽

XIAOYAN LIU ◽

YU ZHANG ◽

LIFU CUI

Keyword(s):

Numerical Simulation ◽

Finite Element ◽

Simulation Analysis ◽

Electrochemical Corrosion ◽

Frost Heave ◽

Buried Pipeline ◽

Mechanical Coupling ◽

Finite Element Software ◽

Corrosion Defects ◽

Permafrost Regions

The geological environment along a buried pipeline in permafrost regions is complex, where differential frost heave often occurs. To understand the changes in the stress behavior of pipeline structures caused by corrosion while laying them in permafrost regions, we established a thermo-mechanical coupling model of buried pipeline with corrosion defects by using finite element software. Numerical simulation analysis of buried pipeline was conducted. The effects of the frost heave length, the length of the transition section, the corrosion depth, and the corrosion length on the stress displacement were obtained. These analyses showed that the stresses and displacements of the pipeline with corrosion defects in permafrost regions can be simulated by using the finite element software numerical simulation method. Afterward, the corrosion resistances of pipelines with different corrosion lengths and depths were investigated via an electrochemical testing method. These results can provide some useful insights into the possible mechanical state of buried pipeline with regard to their design and construction, as well as some useful theoretical references for simulating real-time monitoring and safety analysis for their operation in permafrost regions.

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Pipeline Upheaval Buckling in Clayey Backfill and Shore Approach

Volume 3: Offshore Geotechnics ◽

10.1115/omae2014-24521 ◽

2014 ◽

Cited By ~ 1

Author(s):

Alahyar Koochekali ◽

Behrouz Gatmiri ◽

Amirabbas Koochekali

Keyword(s):

Water Level ◽

Failure Mechanism ◽

Water Levels ◽

Burial Depth ◽

Buried Pipeline ◽

Soil Response ◽

Upheaval Buckling ◽

Soil Failure ◽

Mean Water Level ◽

Uplift Resistance

True estimation of soil response during pipeline upheaval buckling is a key parameter in the safe design of subsea buried pipeline. In this paper the effects of sea mean water level over the buried pipeline and the effects of pipe burial depth on the soil response during vertical buckling are investigated. For that purpose a numerical modeling of pipeline upheaval buckling in clayey backfill has been conducted. Different sea mean water levels are considered to simulate the pipeline shore approach. In addition, various pipeline burial depths are considered to predict the soil uplift resistance and the soil failure mechanism. In order to model the large penetration of pipeline into the soft clay, Arbitrary Eulerian Lagrangian (ALE) method is employed. The results reveal that in the shallow water the sea mean water level may have considerable effects on the soil failure mechanism and soil uplift resistance. In addition, as the sea mean water level and pipe burial depth increases, a new transitional failure mechanism can be observed. The mechanism is a combination of vertical sliding block mechanism and the flow-around mechanism.

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Beam-Mode Buckling of Buried Pipeline Subjected to Seismic Ground Motion

Volume 8: Seismic Engineering ◽

10.1115/pvp2012-78559 ◽

2012 ◽

Author(s):

Masaki Mitsuya ◽

Takashi Sakanoue ◽

Hiroyuki Motohashi

Keyword(s):

Finite Element ◽

Ground Motion ◽

Critical Strain ◽

Peak Load ◽

Earthquake Resistance ◽

Past Study ◽

Buried Pipeline ◽

Buried Pipelines ◽

Seismic Ground Motion ◽

Beam Mode

During seismic events, buried pipelines are subjected to deformation by seismic ground motion. In such cases, it is important to ensure the integrity of the pipeline. Both beam-mode and shell-mode buckling may occur in the event of compressive loading induced by seismic ground motion. In this study, the beam-mode buckling of a buried pipeline that occurred after the 2007 Niigataken Chuetsu-oki earthquake in Japan is investigated. A simple formula for estimating the critical strain, which is the strain at the peak load, is derived, and the formula is validated by finite-element analysis. In the formula, the critical strain increases with the pipeline diameter and hardness of the surrounding soil. By comparing the critical strain derived in this study for beam-mode buckling with the critical strain derived in a past study for shell-mode buckling, the formula facilitates the selection of the mode to be considered for evaluating the earthquake resistance of a pipeline. In addition to the critical strain, a method to estimate the deformation caused by seismic ground motion is proposed; the method can be used to evaluate the earthquake resistance of buried pipelines. This method uses finite-element analyses, and the soil–pipe interaction is considered. This method is used to reproduce the actual beam-mode buckling observed after the Niigataken Chuetsu-oki earthquake, and the earthquake resistance of a buried pipeline with general properties is evaluated as an example.

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Discrete ice lens theory for frost heave beneath pipelines

Canadian Geotechnical Journal ◽

10.1139/t92-053 ◽

1992 ◽

Vol 29 (3) ◽

pp. 487-497 ◽

Cited By ~ 12

Author(s):

J. F. (Derick) Nixon

Keyword(s):

Mass Flow ◽

Two Dimensions ◽

Frozen Soil ◽

Temperature Fields ◽

Frost Heave ◽

Temperature Profiles ◽

Two Dimensional ◽

Buried Pipeline ◽

Soil Columns ◽

One Dimensional

The discrete ice lens theory of frost heave in one-dimensional soil columns was developed to provide a better physical basis for engineering predictions of frost heave in soils. The theory has now been extended to the two-dimensional heat- and mass-flow situation beneath a buried chilled pipeline. Although the frozen and unfrozen soil regions beneath a buried cold pipeline are two dimensional, and the temperature and water-flow fields are potentially complex, considerable simplifications can be made by invoking the so-called quasi-static approach for estimating temperature fields around the buried pipeline. It is proposed that the curved, quasi-static temperature profiles available from published relationships are appropriate for frost-heave predictions in the two-dimensional region beneath a pipeline. Using these curved temperature profiles in the same program and solution procedure developed previously for one-dimensional soil columns allows frost-heave predictions for a buried pipeline to be carried out with a minimum of computational effort. Therefore, the lengthy and tedious numerical procedures that have been a feature of previous attempts to model heat and mass flow and the resulting frost heave in two dimensions can be avoided. The procedure has been used to predict the frost depth and heave beneath two well-documented pipeline test sections at Calgary, Alta., and Caen, France, with very good agreement between prediction and observation. Some predictions for a practical field situation indicate the initial ground temperature plays an important role in frost heave, frost penetration, and the time at which the final ice lens forms in the freezing soil. Key words : frost heave, discrete ice lens, pipeline, segregation potential, hydraulic conductivity of frozen soil.

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Comparison of predicted and observed responses of pipeline to differential frost heave

Canadian Geotechnical Journal ◽

10.1139/t94-098 ◽

1994 ◽

Vol 31 (6) ◽

pp. 803-816 ◽

Cited By ~ 3

Author(s):

B. Rajani ◽

N. Morgenstern

Keyword(s):

Large Diameter ◽

Time Dependent ◽

Frost Heave ◽

Scale Model ◽

Small Scale ◽

Frozen Soils ◽

Winkler Model ◽

Polycrystalline Ice ◽

Differential Frost Heave ◽

Small Scale Model

This paper describes the application of a simplified Winkler model to simulate the observed time-dependent responses of a pipeline at Caen, France, subjected to differential frost heave. The numerical Winkler model developed for a semi-infinite beam embedded in a creeping medium was used to evaluate the response of the Caen pipeline. Despite its simplicity, the Winkler model is able to predict the overall response of deflections and stresses which compares satisfactorily with observed data. In a previous study, the same Winkler analysis was applied to small-scale model steel pipelines embedded in polycrystalline ice, and satisfactory comparisons between the predicted and observed responses were obtained. Consequently, the analyses presented in this paper serve to reconfirm that the Winkler model can also be applied to analyze large-diameter pipelines subjected to differential frost heave. Key words : chilled pipelines, creeping foundation, frozen soils, frost heave.

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Beam-Mode Buckling of Buried Pipeline Subjected to Seismic Ground Motion

Journal of Pressure Vessel Technology ◽

10.1115/1.4007646 ◽

2013 ◽

Vol 135 (2) ◽

Cited By ~ 6

Author(s):

Masaki Mitsuya ◽

Takashi Sakanoue ◽

Hiroyuki Motohashi

Keyword(s):

Finite Element ◽

Ground Motion ◽

Critical Strain ◽

Earthquake Resistance ◽

Past Study ◽

Buried Pipeline ◽

Buried Pipelines ◽

Seismic Ground Motion ◽

Critical Buckling Strain ◽

Beam Mode

During seismic events, buried pipelines are subjected to deformation by seismic ground motion. In such cases, it is important to ensure the integrity of the pipeline. Both beam-mode and shell-mode buckling may occur in the event of compressive loading induced by seismic ground motion. In this study, the beam-mode buckling of a buried pipeline that occurred after the 2007 Niigataken Chuetsu-oki earthquake in Japan is investigated. A simple formula for estimating the critical buckling strain, which is the strain at the peak load, is derived, and the formula is validated by finite-element analysis. In the formula, the critical buckling strain increases with the pipeline diameter and hardness of the surrounding soil. By comparing the critical strain derived in this study for beam-mode buckling with the critical strain derived in a past study for shell-mode buckling, the formula facilitates the selection of the mode to be considered for evaluating the earthquake resistance of a pipeline. In addition to the critical buckling strain, a method to estimate the deformation caused by seismic ground motion is proposed; the method can be used to evaluate the earthquake resistance of buried pipelines. This method uses finite-element analyses, and the soil–pipe interaction is considered. This method is used to reproduce the actual beam-mode buckling observed after the Niigataken Chuetsu-oki earthquake, and the earthquake resistance of a buried pipeline with general properties is evaluated as an example.

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Experimental Studies of Pipeline Uplift Resistance in Frozen Ground

2004 International Pipeline Conference, Volumes 1, 2, and 3 ◽

10.1115/ipc2004-0133 ◽

2004 ◽

Author(s):

Bill Liu ◽

Jack Crooks ◽

J. F. (Derick) Nixon ◽

Joe Zhou

Keyword(s):

Experimental Studies ◽

Soil Surface ◽

Mechanical Tests ◽

Frozen Soil ◽

Frost Heave ◽

Frozen Ground ◽

Frozen Soils ◽

Uplift Resistance ◽

Load Displacement ◽

The Impact

A buried pipeline is subject to a variety of internal and external loads, one of which is the load induced by relative movements between the pipeline and the surrounding soils. Frost heave is one of the potential mechanisms that induce the relative movement for buried pipelines of chilled gas. The magnitude of the loads due to frost heave depends upon the amount of heaving and the load-displacement characteristics of the surrounding frozen soils, i.e., the uplift resistance of the frozen soils. Under the sponsorship of Pipeline Research Council International (PRCI), laboratory uplift tests have been carried out to study the load-displacement characteristics of a frozen soil and to assess the impact of loading rate, ice content and freezing direction. In addition to the measurements of the load and displacement of the pipe, deformations of the soil surface were also monitored at various locations. Parallel to the uplift tests, a series of laboratory geo-mechanical tests were conducted to define stiffness, tensile strain limits and time-dependent behavior of the frozen soil. Examples of the uplift test results are presented in the paper, together with detailed descriptions of soil material and test conditions. It is noted that quantitative data on uplift resistance are considered proprietary and will not be presented in this paper; however, detailed data may be obtained from technical publications of PRCI. Observations during the test with respect to the development of cracks in the frozen soil will be discussed. The load-displacement relationships measured in the uplift tests, together with the geo-mechanical properties of the frozen soil, will be used to the development and calibration of a numerical model, which will be presented in a separate technical paper to IPC2004.

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