Risk to buried gas pipelines in landslide areas

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dc.contributor.authorFerreira, Nelson John
dc.contributor.examiningcommitteeAlfaro, M. (Civil Engineering) Dick, K (Biosystems Engineering) Wijewickerme, D. (University of British Columbia)en_US
dc.contributor.supervisorBlatz, James (Civil Engineering)en_US
dc.date.accessioned2016-09-09T16:57:04Z
dc.date.available2016-09-09T16:57:04Z
dc.date.issued2016
dc.degree.disciplineCivil Engineeringen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractNatural Hazards are a risk to buried gas pipeline infrastructure, but these risks are difficult to assess and quantify. This can often lead to the risks not being properly identified by pipeline owners. The risk to pipelines within landslide areas are particularly difficult to assess given the complex nature of landslide movements and the soil-pipeline interaction mechanisms imposing loads on a pipeline. This thesis research examines the relationship between ground movements and strains/stresses in buried pipelines through field measured ground movements and in-situ measured pipe strains/stresses. The pipe stresses and strains are then used to estimate probability of pipeline failure and risk based on RBDA limit states approaches. Within Manitoba Hydro’s pipeline network, three at-risk landslide areas (riverbank and deep river valleys) were selected for detailed studies. A field investigation and monitoring program was undertaken to assess possible sources of load and stresses on pipelines. Soil, ground, and pipe instrumentation were installed at the sites and monitored over a four year period. Monitoring results identified soil near the pipeline does not freeze, and ground movements at valley sites are slow moving (<50 mm/year) landslides. The monitoring results also showed pipe stresses and behaviour were affected by backfilling, changes in river levels, thermal affects, soil-pipe relaxation, and ground movements. Pipe push tests were conducted in conjunction with FEM modelling to examine pipe adhesion and to possible explain the pipe behaviour observed. Several ultimate and serviceability limit states pipe failure modes were assessed using the measured pipe stresses. Statistical analysis was undertaken to calculate the probability of pipeline failure for the various limit states failure modes and compared against limit states targets for several scenarios (backfill loads, initial stress-state of the pipeline, other pipelines within Manitoba Hydro network). Overall, the probability of failure estimates were generally insignificant or low due to a postulated soil-pipe relaxation mechanism which is causing a repeated release in longitudinal pipe stresses as the landslide continues to accumulate ongoing ground movements. Three mechanisms are presented and discussed. The statistical analysis indicate pipelines within Manitoba Hydro’s network may exceed limit states targets for yielding and local buckling depending on the loading scenario and the class of the pipeline within the landslide area. The outcome of the research was used to develop a risk managements system to examine geotechnical hazards within Manitoba Hydro’s pipeline network. Specifically, risks associated with ground movements along natural slopes and at river crossings are examined within the system.en_US
dc.description.noteOctober 2016en_US
dc.identifier.urihttp://hdl.handle.net/1993/31661
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectLandslidesen_US
dc.subjectBuried Pipelinesen_US
dc.subjectProbability Theoryen_US
dc.subjectSoil-Pipe Adhesionen_US
dc.subjectRisk Management Systemen_US
dc.subjectLimit Statesen_US
dc.subjectPipe push testsen_US
dc.subjectStrain monitoringen_US
dc.subjectground movementsen_US
dc.subjectPipeline Reliabilityen_US
dc.subjectsoil-pipe relaxationen_US
dc.titleRisk to buried gas pipelines in landslide areasen_US
dc.typedoctoral thesisen_US
local.subject.manitobayesen_US
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