Physical and Numerical Modelling of Pipelines in Elastic Visco-Plastic Soils Under Long-Term Ground Movements

Wong, Chee Ken

Physical and Numerical Modelling of Pipelines in Elastic Visco-Plastic Soils Under Long-Term Ground Movements

dc.contributor.advisor	Wan, Richard
dc.contributor.author	Wong, Chee Ken
dc.contributor.committeemember	Guo, Peijun
dc.contributor.committeemember	Priest, Jeffrey A.
dc.contributor.committeemember	Sudak, Leszek Jozef
dc.date	2018-11
dc.date.accessioned	2018-05-22T14:50:32Z
dc.date.available	2018-05-22T14:50:32Z
dc.date.issued	2018-05-15
dc.description.abstract	Pipelines have been constructed and designed to transport essential natural resources such as water, oil, and natural gas for the last 160 years. Many pipeline sections built are buried at shallow depths below the ground surface and through different geologic terrains. This includes complex terrains where permanent ground deformations can occur such as moving slopes/landslides, surface faulting, and ground subsidence. Pipeline sections subjected to such permanent ground deformations can yield because of large strain accumulation over time leading to large pipe stresses. The mode of pipe yielding promoted by permanent ground deformations is dependent on the pipeline axis orientation with respect to the ground movement direction. Longitudinal ground movements promote pipe buckling, transverse ground movements promote pipe bending, and complex ground movements promote a mix of pipe bending and buckling. This study introduces a set of numerical tools aimed at predicting the soil movement before a buried pipeline section reaches the onset of yielding. Various numerical tools are developed for pipelines buried in compacted clay soils such as Regina clay. Compacted clay soils are of specific interest as they exhibit significant time-dependent behavior such as creep, constant strain rate effect, and stress relaxation. The main benefit of the numerical tools developed in this thesis is for the pipeline industry to be able to continually assess pipeline performance in areas with unstable soil movements and to perform necessary remediation procedures such as pipe stress relief to prolong pipeline operation at the right time. The three phases of numerical tool development include: 1) Determination of constitutive models for compacted Regina clay and soil-pipe interface, 2) Validation of the longitudinal, transverse and vertical uplift soil resistances in existing buried pipeline guidelines through a series of physical soil-pipe prototype tests, and 3) Validation of the physical prototype test results through the creation of an Extended Finite Element Method (XFEM) numerical model. The physical prototype test results illustrate consistency with existing guidelines for transverse horizontal soil resistances, but a discrepancy for vertical uplift soil resistances. There also exists behavior discrepancy in the longitudinal soil resistances. The discrepancy in vertical pipe uplift results arises from neglecting the tensile failure mode of the soil in the guidelines. The behavior discrepancy in longitudinal loading is due to differences in adhesion factor estimation, also neglected in the guidelines. The final XFEM numerical model with cap (modified Drucker-Prager) plasticity coupled with Singh-Mitchell creep law for Regina clay demonstrate good predictions of soil-pipe interactions from physical prototype tests.	en_US
dc.identifier.citation	Wong, C. K. (2018). Physical and Numerical Modelling of Pipelines in Elastic Visco-Plastic Soils Under Long-Term Ground Movements (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31925	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/31925
dc.identifier.uri	http://hdl.handle.net/1880/106644
dc.language.iso	eng
dc.publisher.faculty	Graduate Studies
dc.publisher.faculty	Schulich School of Engineering
dc.publisher.institution	University of Calgary	en
dc.publisher.place	Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Pipelines
dc.subject	Clay Soil
dc.subject	Pipe-Soil Interaction
dc.subject	Elastic Visco-plastic Soil
dc.subject.classification	Engineering--Civil	en_US
dc.title	Physical and Numerical Modelling of Pipelines in Elastic Visco-Plastic Soils Under Long-Term Ground Movements
dc.type	doctoral thesis
thesis.degree.discipline	Civil Engineering
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.item.requestcopy	true