Predictive Block Stability Analysis by Integrating UAV-Based Photogrammetry and Back Analysis

Summary

Abstract

Determining in-situ joint shear strength properties through the back analysis of previously failed blocks is substantial in rock slope stability analysis since such back-calculated strength parameters not only reflect site-specific geological conditions but also enhance the reliability of forward stability predictions. The integration of UAV-based photogrammetry within this analytical workflow strengthens the process by providing high-resolution 3D models for detailed, contact-free structural mapping and geometrical analysis of discontinuity networks. This study presents an extensive rock slope stability analysis on south facing wall of an open pit mine integrated with UAV-based photogrammetry. The study includes back analysis of an earlier wedge failure and forward block stability analysis for slope hazard assessment. Detailed structural geologic mapping is performed on the 3D model identify discontinuities along the slope face. Kinematic analysis performed using the mapped structural data confirmed that several wedges are kinematically admissible. Two previously failed wedges are also identified, one of which generated rock fragments that extended to the lower benches and near the access tunnel. The geometry, size and failure characteristics of this wedge are quantified on the 3D model. These inputs are used in back analysis to estimate joint shear strength parameters contributing to the failure. These parameters are then applied in forward block stability analyses to assess the potential for future block failures that could threaten the safety and mining operations. This workflow enables fast and rigorous mapping of structures, reliable calibration of joint shear parameters, supports predictive rock slope stability evaluation, and provides a foundation for designing targeted mitigation strategies to improve mine safety and operational reliability.