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CASE STUDY OF A LANDSLIDE ON HIGHWAY 20 NORTH OF CRAVEN, SK
Session: Landslides and Slope Stability I / Mouvements de terrain et stabilité des pentes I
Harpreet Panesar, Saskatchewan Ministry of Highways and Infrastructure (Canada)
Hung Vu, Golder Associates Ltd (Canada)
Laurie Stang, Golder Associates Ltd (Canada)
Jody Schafer, Saskatchewan Ministry of Highways and Infrastructure (Canada)
Hamid Soleymani, Saskatchewan Ministry of Highways and Infrastructure (Canada)
Saskatchewan’s climate is classified as semi-arid; however, the occurrence of rainfall events and the intensity of rainfall have increased significantly in recent years. An increased frequency and intensity of rainfall events results in more water infiltration and a subsequent increase in groundwater table elevations and reduced soil suctions on the side slopes of highways. Higher groundwater tables and reduced soil suctions are contributing to the destabilization of marginally stable natural slopes and manmade fills across many valleys throughout Southern Saskatchewan.
Two such failures were observed on Highway 20 north of Craven, SK. Highway 20 has a number of high fills across ravines that feed into the valley of Last Mountain Lake just a few kilometers north of Craven where the highway starts to climb out of the valley. The fill at the location of the failure is more than 20 m high. Severe cracking along the shoulder was observed in August 2014.
This paper documents the results of a geohazard risk assessment, terrain analysis, site investigation, instrumentation monitoring, slope stability analysis and an evaluation of remediation options.
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