Using pre-failure and post-failure remote sensing data to constrain the three-dimensional numerical model of a large rock slope failure

Abstract

Factors governing rock slope stability include lithology, geological structures, hydrogeological conditions, and landform evolution. When certain conditions are met, rock slopes may become unstable, inducing deformation and failure. In the present study, an integrated remote sensing-numerical modeling approach investigates the deformation mechanisms leading to the 1965 Hope Slide, BC, Canada and the effect of slope kinematics on the long-term evolution of the slope. Pre- and post-failure datasets were used to perform a large-scale geomorphic and structural characterization, including kinematic and block-theory analyses. Extensive data collection was also undertaken using state-of-the-art remote sensing techniques, including digital photogrammetry (Structure-from-Motion), laser scanning (aerial and terrestrial), and infrared thermography. New evidence is provided that one or more prehistoric failures caused the removal of a key-block, and the initiation of long-term slope deformation and cumulative slope damage ultimately resulting in the catastrophic 1965 event. Detailed characterization of the rock slope has allowed the first three-dimensional, distinct element numerical model of the Hope Slide to be conducted. The results of the numerical simulations involving gradual reduction of the rupture surface shear strength indicate that 1965 slope failure may represent the outcome of a long-term, progressive failure mechanism that initiated after a prehistoric landslide. This combined field mapping–remote sensing–numerical modeling study clearly highlights the role of 3D slope kinematics on the geomorphic evolution of the slope, along with the associated failure mechanisms.