Search

Landslides are a risk to buried gas pipeline infrastructure, but these risks are particularly difficult to assess given the complex nature of landslide movements. This paper presents of portion of research conducted at the University of Manitoba where gas pipelines within active landslide areas were monitored over a 4 year period. Two locations were examined in western Manitoba within the Assiniboine River Valley where a shallow natural gas pipeline runs parallel to the valley slope. A field investigation and monitoring program was undertaken where surficial ground movements and soil and pipe temperatures and pipe strains through strain gauges were measured. Monitoring results identified soil near the pipeline does not freeze, and ground movements are <50 mm/year. The monitoring results also showed pipe stresses and behaviour were affected by backfilling, thermal changes, soil−pipe relaxation, and ground movements. An unexpected outcome of the research was the response of the pipeline to slight ground movements was easily captured by the strain gauges and these movements, slow or surges, tended to occur at the same time between the two sites suggesting movements occur due to regional environmental effects. [ABSTRACT FROM AUTHOR]

The major rivers within the City of Winnipeg are founded in glacial Lake Agassiz clay and silt sediments that have low shear strength. As such, riverbank instabilities are a common issue along many stretches of the rivers. The use of rockfill columns has become an increasingly utilized approach for stabilizing failing banks. Recent cases in Winnipeg have shown that movements can occur following installation of rockfill columns. Uncertainty regarding the magnitude of these movements that is required to mobilize shearing resistance in the rockfill columns has resulted in situations where the stability of riverbanks following remediation has been questioned. This has provided a need to improve our understanding about how much movement a stabilized slope must undergo before sufficient shear resistance of the rockfill column will be mobilized. The results of experimental testing conducted to assess the shear mobilization of rockfill column materials using a large-scale direct shear test apparatus are presented in this paper. The testing methodology is described along with the test results. The results show that the development of material specifications, construction, and placement methods and appropriate methods of analysis requires understanding of the stress–strain properties of the in situ soil and the rockfill material. [ABSTRACT FROM AUTHOR]

Groundwater from the Carbonate Rock Aquifer is extensively used for cooling purposes in Winnipeg, Manitoba. This paper examines the factors affecting the magnitude and timing of temperature increases at production wells in groundwater-source cooling applications through numerical modeling and observations at a case study site. Generic simulations carried out using typical hydrogeologic parameters for the Carbonate Rock Aquifer suggested that temperature increases of a few degrees occur at a typical production well only a few years after the start of operation in a given system. Spacing of the wells and pumping rates were found to have a greater affect than material properties in a homogeneous aquifer. A case study of a thermal doublet in the Winnipeg area indicated, however, that heterogeneities are capable of causing a departure from the predicted temperatures of the generic models. The case study showed that it is possible to make reasonable predictions of the behaviour of the subsurface temperature field during thermal development of the Carbonate Rock Aquifer. Temperature records of the length used in this study will not be available in new developments, however, and efforts must be made to conduct more extensive field investigations to ensure that designs can properly account for geologic conditions. [ABSTRACT FROM AUTHOR]