Variations in river level and their impact on slope stability at the Borden Bridge landslide

ABSTRACT: Slope failures along the deeply incised river valleys are common throughout the prairies. These failures typically take the form of deep-seated, translational landslides that move predominately on either weak bentonite layers or pre-sheared Cretaceous shale bedrock layers. One of these landslides is at Borden Bridge, which is located on Highway No. 16 approximately 50 km west of Saskatoon. This paper presents a numerical evaluation of the potential role of the river level and the corresponding pore-water pressures within the clay shale on the rate of movement of the east bank of the Borden Bridge. Pore-water pressures and rates of movement modeled in the parametric analyses will be compared to those measured in the field. Though this work is preliminary, it will provide information regarding the role of river level fluctuations, the corresponding pore-water pressure response on the pre-sheared slide plane and the observed rate of movement of the Borden Bridge landslide.