Abstract: Obtaining the useful rock material from a waste rock storage yard that has been operated for an extended period is a crucial method for the utilizing waste resources. The stability of excavated waste rock storage yards is a significant factor to consider. This study focuses on the excavation and the transportation project of a waste rock storage yard in Ningbo City. The stability of conditions of slopes under three different excavation schemes: slope rate 1H:3.0V, slope rate 1H:2.0V, and stepped slope are evaluated. The strength reduction method in Phase2 software is utilized for this assessment. A comparison is conducted between the stability evaluation results of slopes with and without excavation unloading effects. The study demonstrates that the Phase2 software can effectively capture the rebound deformation and the stress redistribution behavior of slopes post-excavation of the waste rock storage yards. The stability factors increase by 10% when disregarding the excavation unloading effect, compared to when accounting for it. Hence, when evaluating the stability of excavation slopes in the waste rock storage yards, failing to consider the excavation unloading effect may result in an overestimation of the safety margins or reserves, potentially posing a risk hazard.

Key words: Waste Rock Storage Yard, Slope Stability, Excavation Unloading Effect, Strength Reduction Method