Strong surface or subsurface vibrations (e.g., aftershocks and blasting) may affect the stability of open-pit mining slopes. Slope stability evaluation is one of the important research topics in open-pit mining safety production. Ground-based InSAR has become a conventional method for monitoring micro-deformation. Similar to spaceborne InSAR, GB-InSAR calculates phase change along the line of sight (LOS) to inverse the deformation of an observation object and then transforms into deformation in a specific direction according to the projection between the LOS and the observation direction. The GB-InSAR system can be used to monitor the activity characteristics of an open-pit slope in near real-time and provide reliable data for safety production.
We use a continuous observation mode and apply direct integration method to integrate the 25 interferograms formed by processing each SLC image with the subsequent one. The uniform atmospheric time-series correction factor is estimated based on the displacement variations over time for 12 ground control points selected on stable iron ores located away from the blasting areas.
Results show that the observation accuracy is within -0.3 mm to 0.3 mm. Only one remarkable displacement sector is located in the lower part of the quarry rock face with a maximum cumulated displacement of ~4 mm. Time-series displacement analysis of pixels shows a slight sliding of not more than 0.3 mm in LOS after blasting and gradually becomes stable over time.
The ground-based InSAR system has high observation stability. The blasting operation has no significant destructive effect on the entire mining face except for a slight decrease in the ore accumulation layer. The GB-SAR system can observe and recognize the deformation zone in a short time and plays an important role in investigating and evaluating slope stability and artificial landslide. The combined application of spaceborne and ground-based InSAR technologies will be further developed to realize the complementary advantages of both observation types based on the current research. At the same time, we will further develop the multi-baseline InSAR technique under repeated observations and introduce mature spaceborne InSAR processing methods to ground-based InSAR to expand its scope of application and enhance the stability of information extraction.