Risk classification and characterization of open-pit slope rock mass based on SPA-entropy weight-TOPSIS model

The stability of open-pit mine slopes is governed by a multifaceted interplay of rock mass properties, slope height, and slope angle, exhibiting significant uncertainty and complexity. Traditional single-stability evaluation methods, such as Limit Equilibrium Method and numerical simulation, struggle to provide high-precision analytical results in complex scenarios. To address this, an integrated evaluation approach fusing numerical simulation with Multi-Criteria Decision-Making theory is proposed to better characterize the stability state of slopes. The research findings indicate that:(1) The Geological Strength Index (GSI) exerts the most significant impact on slope stability, followed by slope height, while the bench slope angle has the least influence relatively.(2) Maximum horizontal stress, maximum displacement, and the plastic zone volume ratio are identified as the core components of the evaluation index system.(3) Discrepancies exist among the indices of stress, displacement, and the plastic zone in forming a unified evaluation criterion, demonstrating that a single indicator is insufficient to fully reflect the holistic stability of the slope.(4) The proposed integrated evaluation method based on Set Pair Analysis (SPA), Entropy Weight Method, and TOPSIS (SPA-Entropy-TOPSIS) exhibits excellent applicability and accuracy, providing a scientific basis for decision-making in mine design optimization and safety management.