Photo courtesy of H. Gillen
Phase IV of the RGHRP builds on the knowledge and experience gained in the previous Phases and focuses on developing strategies for the railway industry’s operational adaptation to climate change, specifically with regard to the increasing prevalence of extreme climate events, advancing research on identified subgrade issues for the industry partners, and filling knowledge gaps in hazard monitoring and assessment identified in Phase III.
The key objectives in Phase IV include: (1) developing and evaluating monitoring technologies for the investigation of ground hazard mechanisms and warning systems; (2) investigating the impact of extreme weather events and adaptation to climate change; (3) assessing multi-scale hazards; and (4) investigating train-induced pore pressure generation and remediation with geotextiles. The discoveries and technical developments will be shared with members of the RGHRP, regulatory agencies, and invited guests through publications and annual workshops.
Large slow-moving landslides: The University of Alberta, Geological Survey of Canada, CN and CP have begun the development of test sites in the Assiniboine River valley, where CN and CP have identified many landslides that impact their railway infrastructure. In collaboration with Transport Canada and the Geological Survey of Canada, these locations will be developed into test beds for site investigation and monitoring, providing a deeper understanding of the nature of the landslides within this valley to better guide the remediation methods implemented by the railways as they address these landslides.
Rock slope instability: The RGHRP team are developing a world-class database of rock slope deformation and failure records for several sites where the rail lines are situated adjacent to the Thompson River valley. This research includes field trials of doppler radar (potential collaboration with IDS Italy), continuous photography and other sensors, including hyperspectral and thermal sensors deployed using unmanned aerial systems. These instruments provide more continuous data streams to improve understanding of failure modes and precursor activities and to enhance the accuracy and timeliness of early detection and warning capabilities.
Rockfall triggering conditions and sensitivity: The RGHRP has quantified rockfall-weather relationships for rockfall hazard management along selected railway corridors. In Phase IV, the research will expand the corridor-scale analyses to a regional scale to quantify the effect of larger climatic signatures on rockfall occurrences using the extensive rockfall databases maintained by CN and CP that extend back to the 1970s and 80s. These databases will be analyzed with statistical techniques to correlate annual and seasonal rock-fall frequencies with interdecadal weather trends and against macro-scale weather phenomena such as the El Niño Southern Oscillation.
Scenario modelling and stress testing for extreme events: Extreme climatic events resulting in widespread flooding, fires or triggering of other ground hazards (e.g. debris flows, landslides, washouts) threaten Canada’s transportation corridors. The 2013 Alberta floods illustrated the damage potential of low-frequency high-magnitude events in transportation infrastructure. Though the magnitude and frequency of these events are expected to increase as a consequence of climate change, climate models are characterized by high levels of uncertainty for longer-term and local forecasts. A review of large-scale flooding and fire events will be conducted as examples of stress tests on infrastructure and the susceptibility of the surrounding terrain to ground hazard events. A framework for modelling extreme weather event scenarios at local and regional scales will be developed and applied to other regions to identify critical locations and systems that require an increase in resilience.
The development of tools to implement geometrical data begun in Phase III and resulted in proof of the utility of physics engine-based models for hazard modelling. Calibration datasets can be derived from local events, such as rockfalls or from events distributed over larger scales, such as debris flows and larger landslide instabilities. It is anticipated that the calibrated physics engine models will simulate potential failure patterns and distribution of down slope materials, supporting engineering decision making about the mitigation of hazards.
Through the extensive investigation of pore water pressure and deflection response of soft subgrades under cyclic loading from heavy train axles in the previous RGHRP phases, the research team has identified issues related to the development of depressions beneath track beds that retain water and result in the saturation of the underlying clayey soils. This study focuses on research related to the effectiveness of geotextiles to promote drainage from subgrade material and to address the impact of the increasing rates of fine grained materials being brought to the track surface and pore pressure generation in saturated clayey soils by cyclic loading by heavy axles loads.