Stability of large embankments founded on glaciated soils

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The province of Saskatchewan is the world's largest potash producer. There are currently 10 potash mines in operation in Saskatchewan. The Saskatchewan potash industry has been regulated to minimize land use requirements and the environmental footprint of the tailings piles. This means that any future tailings deposition must be done at steeper side slopes and by increasing pile heights in excess of 50 m. It is, therefore, becoming increasingly critical to ensure the stability of these tailings piles. Already, the potash industry is experiencing an increase in the number of incidences of excessive deformations and instability in these piles. The response of the potash industry has been to place greater emphasis on the design and installation of field monitoring systems to guide the placement of tailings and to provide early warning of excessive deformations and potential failures. This, unfortunately, has not resulted in a significant drop in incidences of pile instability. Many of the potash tailings piles in Saskatchewan are founded on glaciated soils, which are quite stiff and have fairly high strength. As such, these soils do not approach failure condition under 'normal' loading conditions such as those imposed by buildings and other similar structures. The loading imposed by a tailings pile, however, is anything but 'normal'. A tailings pile, which is essentially a very large embankment, has the potential to cause failure of the glaciated soil over which it is placed. These tailings piles provide a unique opportunity to study the response of glaciated soils subjected to 'near failure' loading conditions and can be regarded as field-scale testing facilities. The proposed research aims to use the monitoring data from the tailings piles as field-scale tests in conjunction with advanced laboratory tests and sophisticated numerical modelling to provide a better understanding of the pre-failure deformation behaviour of glaciated soils. The outcome of the proposed research will lead to safer design of tailings piles and other large structures (such as dams, bridges, tunnels, etc.) founded on glaciated soils and result in significant savings in construction and operations costs.