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experimental and analytical investigation of viscoelastic pipe-soil interaction
Title
An experimental and analytical investigation of viscoelastic pipe-soil interaction.
Creator
Ahn, Woo-Suk., Florida Atlantic University, Reddy, Dronnadula V., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
An overview of the current issues of HDPE pipe-soil systems is followed by a comprehensive literature review addressing current specifications, design methods, and relevant research projects. The following experimental tasks are described: (i) environmental stress cracking resistance (modified AASHTO M294), (ii) creep (10,000 hour parallel plate loading at super ambient temperatures), (iii) performance of buried pipes, subjected to live loading in a soil chamber, and (iv) field monitoring....
Show moreAn overview of the current issues of HDPE pipe-soil systems is followed by a comprehensive literature review addressing current specifications, design methods, and relevant research projects. The following experimental tasks are described: (i) environmental stress cracking resistance (modified AASHTO M294), (ii) creep (10,000 hour parallel plate loading at super ambient temperatures), (iii) performance of buried pipes, subjected to live loading in a soil chamber, and (iv) field monitoring. The findings include (i) satisfactory short-term environmental stress cracking resistance, (ii) temperature-dependency of the flexural modulus, (iii) the evidence of transition between slow crack growth and rapid crack propagation due to imperfect installation, and (iv) high load carrying capacity for the properly installed pipe in uniform backfill, showing an over-deflection failure mode with top flattening. The analytical investigations are as follows: (i) Bidirectional shift-constructed master curve, based on accelerated creep test values for long-term modulus prediction that showed good agreement with the Arrhenius equation-based analysis, (ii) Development of a seven-degree Voigt-Kelvin viscoelastic model based on the bidirectional shift-constructed master curve for analytical prediction of the long-term modulus, (iii) Comparison of two-dimensional and three-dimensional harmonic FEM analyses with the measured response of pipe-soil interaction, that demonstrated the analytical predictability of the pattern of deformation and stress distribution, and (iv) Determination of axial stress distribution along the pipe in non-uniform backfill condition, evaluated by approximate analysis based on finite differencing the deflection profile obtained from the assembly of individual finite segments/sections. This overcomes the limitation of the harmonic FEM analysis for pipe-soil interaction involving non-uniform soil conditions longitudinally and/or varying soil thickness circumferentially. The findings include (i) importance of axial stress contribution at failure, (ii) top flattening failure mode due to over-deflection preceding buckling or yielding, and (iii) critical adverse effect of the non-uniform backfill condition that can lead to joint opening, localized buckling, liner tearing/debonding, or cracking. The work has "spin off" applications to the coastal and offshore environments for sewage outfalls, marine pipelines etc.
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Date Issued
1998
PURL
http://purl.flvc.org/fcla/dt/12550
Subject Headings
Soil-structure interaction, Pipe, Plastic--Testing, Underground pipelines
Format
Document (PDF)
Long-term performance of buried high-density polyethylene plastic piping
Title
Long-term performance of buried high-density polyethylene plastic piping.
Creator
Gazagnaire, Cyril., Florida Atlantic University, Reddy, Dronnadula V.
Abstract/Description
The primary goal of this study was to evaluate the service life of HDPE (High Density PolyEthylene) pipes. The following experimental tasks were carried out: (i) procurement of materials, and fabrication of test setups; (ii) creep evaluation: the performance of buried pipes (notched/unnotched), subjected to live loading, was studied in soil chambers for three levels of loading (service, 2/3 and 1/3 of service). The long-term behavior was accelerated with super-ambient temperatures; (iii)...
Show moreThe primary goal of this study was to evaluate the service life of HDPE (High Density PolyEthylene) pipes. The following experimental tasks were carried out: (i) procurement of materials, and fabrication of test setups; (ii) creep evaluation: the performance of buried pipes (notched/unnotched), subjected to live loading, was studied in soil chambers for three levels of loading (service, 2/3 and 1/3 of service). The long-term behavior was accelerated with super-ambient temperatures; (iii) field monitoring: strains and diametral changes were measured for 10,000 hours. The analytical investigations were as follows: (i) extrapolation of the long-term performance at ambient temperature, based on the Bi-directional and the Arrhenius methods and (ii) 2-D Finite Element Analysis, using the software CANDE. The findings include: (i) the deflection threshold (7.5% vertical change of diameter) as the governing failure condition, (ii) similar life predictions, for Bi-directional and Arrhenius methods, with service lives of about 80 and 30 years at ambient temperature, for unnotched and notched specimens, respectively, subjected to maximum loading, and (iii) a reasonable agreement between analytical and experimental values.
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Date Issued
2000
PURL
http://purl.flvc.org/fcla/dt/15757
Subject Headings
Pipe, Plastic--Testing, Underground pipelines--Design and construction, Underground plastic pipe
Format
Document (PDF)
role of polyethylene duct cracking in the failure of post-tensioned cables in Florida segmental bridges
Title
The role of polyethylene duct cracking in the failure of post-tensioned cables in Florida segmental bridges.
Creator
David, Florent Martin., Florida Atlantic University, Hartt, William H.
Abstract/Description
During the past several decades, segmental construction using precast sections has evolved as a preferred design and construction method for bridges. The tendons used to hold the precast sections together are comprised of cables surrounded by a plastic duct filled with grout. Cracking of the tendon's protective plastic duct has been observed in several Florida bridges. An experimental investigation was performed to characterize the material properties of the high density polyethylene ducts...
Show moreDuring the past several decades, segmental construction using precast sections has evolved as a preferred design and construction method for bridges. The tendons used to hold the precast sections together are comprised of cables surrounded by a plastic duct filled with grout. Cracking of the tendon's protective plastic duct has been observed in several Florida bridges. An experimental investigation was performed to characterize the material properties of the high density polyethylene ducts used in the past and those being specified nowadays. The degree of cure of the resin, the results of three-point bending tests for unnotched and notched specimens, the coefficient of thermal expansion, and the deformation of a tendon as a function of temperature changes were studied. The effects of the grouting pressure and the void presence in the grout were quantified and the pressurization period was shown to affect significantly the pipe strain.
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Date Issued
2003
PURL
http://purl.flvc.org/fcla/dt/12999
Subject Headings
Pipe, Plastic--Testing, Bridges--Florida, Post-tensioned prestressed concrete construction
Format
Document (PDF)