Physical Scale Modelling of Electrothermic Thawing of Permafrost For Alleviation of Frost Heave Problems In Chilled Gas Pipelines

1981 ◽  
Vol 20 (03) ◽  
Author(s):  
F.E. Vermeulen ◽  
F.S. Chute ◽  
M.R. Cervenan
Keyword(s):  
Frost Heave ◽  
Gas Pipelines ◽  
Physical Scale ◽  
Scale Modelling

Prediction of Long-Term Frost Heave of Chilled Gas Pipelines by Centrifuge Modeling

2004 ◽  
Author(s):  
Vincent Morgan ◽  
Jack Clark ◽  
Bipul Hawlader ◽  
Joe Zhou
Keyword(s):  
Climatic Conditions ◽  
Full Scale ◽  
Centrifuge Modeling ◽  
Frost Heave ◽  
Soil Types ◽  
Small Scale ◽  
Gravitational Acceleration ◽  
Gas Pipelines ◽  
Centrifuge Testing ◽  
Pipe Geometry

The use of chilled gas transmission for northern pipelines has been considered an effective solution to reduce potential problems relating to permafrost preservation, as well as to provide other benefits such as increased throughput. However, the potential for frost heave as the pipe crosses areas of unfrozen ground may have implications on induced strains and therefore pipeline integrity. C-CORE, under the sponsorship of Pipeline Research Council International (PRCI), has been investigating the effects of frost heave for different soil types and varying pipe geometry and temperature. Previous studies of the effects of frost heave of chilled gas pipelines involved the construction of full-scale test sites, operated over a number of years and small scale laboratory tests. Recent advances in centrifuge testing techniques have allowed small-scale models to be constructed and tested under increased gravitational acceleration to replicate full-scale conditions. The major advantages are the reduced scale and time effects used in the modeling of the frost heave. This allows a number of sequential tests to be performed to study a range of soil types, pipe temperatures, groundwater and climatic conditions in a relatively short time period and at significantly reduced cost. Centrifuge modelling also incorporates other forms of soil deformations with development of ice lenses which includes the consolidation of unfrozen soil and deformation of both frozen and unfrozen soil. The tests performed to date have focused on the determination of frost heave behaviour for a number of soil types covering the range of frost susceptibility. This paper discusses the interpretation of the test results, and provides a comparison with common methods of analysis for prediction of frost heave. A design methodology is also proposed, which makes use of centrifuge test and analytical methods.

Innovative Mooring in the Port of the Future: Scale Model Testing of the ShoreTension System

2020 ◽  
Author(s):  
S. P. Reijmerink ◽  
N. Bruinsma ◽  
A. J. van der Hout ◽  
M. P. C. de Jong ◽  
C. Clement
Keyword(s):  
Numerical Models ◽  
Low Frequency ◽  
Scale Model ◽  
Performance Limits ◽  
Coastal System ◽  
Physical Scale ◽  
Scale Modelling ◽  
And Performance ◽  
Port Infrastructure ◽  
The Impact

Abstract Moored vessels often experience low-frequency vessel motions when moored in a port due to wave excitation. Under such conditions the loading and offloading of vessels may be hampered when these movements become too large [1,2,3]. Innovative mooring techniques can be used for reducing issues with excessive motions of moored vessels in waves [4,5,6]. Considering applying such techniques as part of the design of mooring facilities and ports is expected to make different approaches to port or mooring facility designs possible. Such techniques, like the ShoreTension (ST) system, are already applied successfully worldwide in ports [7,8,9], however the application and performance limits of such systems under extreme conditions are not well known. This paper describes the results of a research project using physical scale modelling to systematically verify and extend the applicability and performance limits of innovative mooring systems. It resulted in a solid validation database for validating numerical models. The knowledge developed in this research will benefit developers of mooring facilities (including ports) to significantly reduce costs by limiting the need for structures providing shelter from waves. Furthermore, this may also help lowering the impact of port infrastructure on the coastal system when using less invasive infrastructure.

Centrifuge modelling of gas pipelines undergoing freeze–thaw cycles

2021 ◽  
Author(s):  
Rajith Sudilan Dayarathne ◽  
Bipul C. Hawlader ◽  
Ryan Phillips
Keyword(s):  
Vertical Displacement ◽  
Operating Conditions ◽  
Frost Heave ◽  
Seasonal Temperature ◽  
Test Results ◽  
Gas Pipelines ◽  
Freezing And Thawing ◽  
Geotechnical Centrifuge ◽  
Freeze Thaw ◽  
Cyclic Temperature

Frost heave and thaw settlement are two critical factors that need to be considered in the design of chilled gas pipelines in cold regions. Due to the variation in seasonal temperature and operating conditions (e.g., pressure and temperature at the compressor stations), the pipeline temperature in some segments might vary from subzero to above-zero during winter and summer. This study examines the freezing and thawing for cyclic and constant temperatures at the pipeline and ground surfaces based on the response of fourteen model pipes tested in a geotechnical centrifuge. The cyclic (temperature) operation reduces the frost heave rate per year and causes net settlement in some cases. When the thaw bulb resulting from an above-zero operating temperature is less than the previously developed frost bulb, upward water flow occurs through the thawed soil, which could alter the pipeline–soil interaction behaviour. Five types of freeze-thaw-induced vertical displacement of the pipe have been identified from the centrifuge test results.

scholarly journals Physical scale modelling of adhered spill plume entrainment

2010 ◽  
Vol 45 (3) ◽  
pp. 149-158 ◽  
Author(s):  
Roger Harrison ◽  
Michael Spearpoint
Keyword(s):  
Physical Scale ◽  
Scale Modelling

Study on a Method Monitoring Oil and Gas Pipelines in Permafrost Regions

2012 ◽  
Author(s):  
Yunbin Ma ◽  
Dongjie Tan ◽  
Ning Song ◽  
Pengchao Chen ◽  
Tao Ma
Keyword(s):  
Temperature Field ◽  
Oil And Gas ◽  
Frost Heave ◽  
Fiber Grating ◽  
Test Results ◽  
Gas Pipelines ◽  
Monitoring Method ◽  
Oil And Gas Pipelines ◽  
The Impact ◽  
Permafrost Regions

Based on conditions of oil and gas pipelines in permafrost regions, this paper demonstrates a method for monitoring pipeline stress and displacement as well as permafrost temperature field. To measure pipeline displacement, Total Station measuring technique which calculates displacement by measuring the change of pipeline sign post was adopted; and to monitor pipeline stress and temperature field of permafrost, Fiber Grating Sensing technique was used. This method has been applied to Pipeline No. A for a year, according to the test results, during the year, displacements of different degrees have been occurred to the pipeline; this pipeline was not influenced by frost heave in winter but was influenced by thaw collapse in summer. Due to this monitoring method for oil and gas pipelines in permafrost regions, the condition of permafrost and the change of pipeline under the impact of permafrost were successfully monitored; therefore, this method is effective and feasible.

scholarly journals Remarks On The Sources Of Error In The Modelling Of Lunar Geotechnical Structures

2018 ◽  
Vol 40 (2) ◽  
pp. 133-139 ◽  
Author(s):  
Francesco Cafaro ◽  
Emanuele Miticocchio ◽  
Valentina Marzulli
Keyword(s):  
Scale Effects ◽  
Lunar Regolith ◽  
Three Dimensional ◽  
Structure Design ◽  
3D Analysis ◽  
Element Analysis ◽  
Change Of Scale ◽  
Physical Scale ◽  
Scale Modelling ◽  
New Research

AbstractScale modelling should be a very useful strategy for the design of lunar structures. Preventing structural damages in the lunar environment is crucial and scale models are helpful to achieve this aim. The size of these models must be scaled to take into account the different gravitational levels. Since the lunar gravity acceleration is about one-sixth of the terrestrial one, it follows that the models on Earth will be very smaller than the prototype to be realized on the Moon. This strategy will represent an opportunity for engineers working on lunar structure design, provided that the errors, both computational and experimental, related to the change of scale are quantified, allowing reliable extension of the physical scale modelling results to the prototype. In this work, a three-dimensional finite element analysis of walls retaining lunar regolith backfill is described and discussed, in order to provide preliminary results, which can guide a future experimental investigation based on physical scale-modelling. In particular, computational errors related to the scale effects are assessed, with respect to a virtual prototype of the lunar geotechnical structure, and compared with errors from other sources of discrepancy, like the adopted constitutive model, the variability of the geotechnical parameters and the calculation section used in the 3D analysis. The results seem to suggest the soundness of this strategy of modelling and are likely to encourage new research, both numerical and experimental, supporting the structure serviceability assessment.

Sign in / Sign up

Export Citation Format

Share Document