Monitoring toppling failures using wireless inertial measurement unit sensors

A topple is a common rock slope failure – and usually the cause of a rockfall – that depends on the slope and rock geometries. This paper presents a laboratory simulation and field generation of a single-column rock topple failure. Innovative inertial measurement unit (IMU) sensors were used to collect three-dimensional acceleration and angular velocity data during four laboratory experiments to understand and characterise general toppling behaviours. A topple is identified by the gradual change in at least two gravity accelerations, the continuous increase in at least one of the angular velocities and a significant change in the linear acceleration in the direction of toppling. A field experiment showed similar sensor data patterns to those observed from the laboratory experiments. An isolated-block stability analysis of a single-column topple provides the basis for incorporating the IMU sensors into the development of future monitoring and early warning systems.