Characterization and Analysis of the Mitchell Creek Landslide: A Large-scale Rock Slope Instability in northwestern British Columbia

摘要

The Mitchell Creek Landslide (MCL) is a large, 74 Mm3, complex, active landslide located in the Coast Mountains of B.C. The slope is composed of foliated and hydrothermally altered volcanic-sedimentary rocks. The Mitchell Thrust and Brucejack faults constrain landslide geometry. Visible deformation initiated mid-20th century, coincident with rapid glacial retreat. This thesis presents results of a detailed characterization study which combines the results of geomorphological analysis, deformation feature mapping, and photogrammetric analysis of historic aerial photography from 1956, 1972, 1992, and 2010; geological and geomechanical borehole data; and geotechnical monitoring of landslide motion and groundwater conditions. Rates of movement vary spatially by geomorphological zone between 0.80 m/yr in the toe to 0.19 m/yr at the backscarp. Numerical modelling simulations were undertaken using continuum and discontinuum methods to evaluate failure mechanisms and landslide evolution. Glacier retreat, regional geology and rupture surface configuration were identified as the primary controls on landslide behaviour.