Enhancing stability analysis of open-pit slopes via integrated 3D numerical modeling and data monitoring

Abstract

The slope at Zhahanur open-pit mine (China) has experienced significant and prolonged deformation, posing a considerable risk to life and property within the mining area. To analyse the deformation and failure mechanism of the rock slope, geotechnical investigations, numerical simulations, and long-term movement monitoring were undertaken. In order to improve the efficiency of slope pretreatment, a point elimination method was proposed for the slope surface, and a 3D geological model of mining area was established. A systematic analysis was performed on monitoring data from surface slope radar and underground inclinometers, enabling the identification of the potential sliding surface and deformation pattern of northern slope in a rational manner. Additionally, through three-dimensional numerical simulation, the feasibility of the mining scheme that incorporates waste dump inside the pit was explored. These simulations accurately captured the varying deformation patterns at different levels and exhibited good agreement with available field monitoring data. The findings revealed a composite multi-stage slope failure pattern primarily controlled by weak layers. The safety factors associated to two competing slip surfaces were determined to be 1.20 and 1.15, respectively. To ensure the safe extraction of coal resources from the deformed slope, a combined mining scheme of in-pit dumping and mining is proposed in the study. The proposed scheme was shown to meet the production needs, with a minimum safety factor of 1.08 for rock slope under the mining scheme. By integrating various field monitoring techniques with numerical simulations, a collaborative monitoring scheme was devised to effectively and promptly identify potential sliding surface and implement necessary mining and control measures to ensure slope stability. This comprehensive approach provides valuable insights into the deformation behavior of the rock slope and facilitates the implementation of proactive measures to mitigate risks associated with slope instability.