Development and application of a pseudo-3D pit slope displacement map derived from ground-based radar

• Unique 3-D experiment, monitoring of large rock slope using two synthetic aperture radar systems.
• Displacement vectors combined to create a 3-D displacement map of the rock slope.
• Over 25,000 displacement vectors created to resolve complex slope kinematics.

Slope monitoring plays an important role in the risk management of large open pit slopes. Historically, displacement data derived from measuring geodetic prisms have been relied upon to delineate the boundaries of potential slope hazards; however that data can be limited by its point-measurement nature. Localized displacements at each prism may be misinterpreted when extended to the behavior of the entire slope, and important displacements between prisms may be overlooked. New technologies like ground-based radar can provide high resolution, full area coverage of a slope in combination with near real-time acquisition and millimeter precision. As a line-of-sight instrument, these tools provide data on displacement magnitudes and rates, but not true direction hence limiting their use in gaining understanding of the kinematics and behavior of the moving slope. This paper describes a novel experiment in which two ground-based synthetic aperture radar systems were simultaneously deployed to record continuous, line-of-sight displacements of an open pit slope in “stereo”. The displacement vectors were combined to create a pseudo 3-D displacement map for the slope, which was subsequently used to interpret the influence of a major fault and the rock mass fabric in promoting different kinematic responses. The data collected demonstrates that an improved understanding of the 3-D kinematics of a large rock slope can be achieved using advanced state-of-the-art monitoring techniques to aid mine design.