Combining InSAR and infrared thermography with numerical simulation to identify the unstable slope of open-pit: Qidashan case study, China

Slope failures frequently occur in open-pit mines, resulting in significant losses. Identifying the precursory displacements and triggering factors for detecting unstable slopes is critical for reducing and preventing their impact. This study proposes combining satellite radar interferometry and infrared thermography with numerical simulation to determine unstable slopes in an open-pit mine. First, interferometric synthetic aperture radar (InSAR) is utilized to capture deformation information in a line-of-sight direction in terms of velocity to locate the long-time movement on a large scale. The application of infrared thermography enables the detection of peculiar features based on the different thermal patterns occurring along the slope and the interpretation of critical sectors matching with the instability zones highlighted by the InSAR. In particular, areas with various surface temperatures were associated with vegetated spots, new benches, bare sectors, and contact between different lithologies. By means of three-dimensional stability analyses, the associated interferometry movement confirmed the slope instability, and a critical failure surface was found using two-dimensional numerical simulation. The efficacy of the proposed approach is verified through a massive slope failure in the Qidashan open-pit mine in Liaoning, China. It predicts the slope failures caused by intense rainfall and reveals the progressive failure mechanism. The practical application has demonstrated the feasibility and accuracy of the proposed approach for detecting failure precursors, providing a novel procedure for remotely identifying critical slopes in an open-pit with frequent mining activity. Graphical Abstract