Performance Evaluation of Critical Geosystems Using Multiscale Methods

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Countries around the world rely on various geotechnical infrastructure for flood control, water storage and hydroelectric power generation. These critical geosystems typically involve a porous media interacting with structural elements such as spillway walls, conduits associated with outlet works or adjoining gravity structures supporting the embankment. The failure of levees, or embankment dams by internal erosion may occur under high water levels during flood events or under normal operating conditions without an apparent triggering event. The latter can be attributed to various factors including decay of existing tree roots or invasive wildlife activities that result in local voids within levees or embankment dams that remain concealed until the safety of the earth structure is jeopardized. The worldwide average cost of failed or damaged earthen structures due to these factors exceeds billions of dollars per year. The negative impact of soil deterioration and erosion-related failure in geosystems is not limited to earth structures. Leaking pipes under or near existing structures are also known to cause sudden and unnoticed failure. ***In Canada, several regions are prone to flooding due, in large part, to the abundance of water resources and the extremes in seasonal temperatures. Extensive research has been done on intact earth structures to study the mechanisms of piping, erosion, and overtopping. However, studies related to the synthesis of failure mechanisms of earth structures with either (a) local soil deterioration, or (b) embedded structural elements are very scarce in the literature.***Current engineering tools and procedures are very limited in modeling the dynamics of the interaction between the flowing water, the soil media and embedded structures. To address this issue, the present work will develop a rigorous multiscale approach to provide as much information as reasonably feasible about this complex soil-water-structure interaction problem. The theme of this Discovery Grant relates to developing new engineering tools to assess the performance of critical geotechnical structures under extreme conditions using centrifuge experiments and multiscale modeling approaches. The outcome of this research program will help engineers and researchers to evaluate the safety of existing earth dams and levees. It will also explain the soil instability and failure associated with leaking pipes buried near surface and subsurface structures. ***The above research program will involve training of four Master and five Doctoral students in addition to five summer undergraduate students over the five year funding period. The graduating geotechnical engineers will have a balanced outlook on the importance (and limitations) of experimental research and sophisticated modelling, and will be a real asset to the scientific communities in Canada and internationally.