## 1 Introduction
[16] performed a statistical analysis of displacement data from numerous landslide cases exhibiting different failure modes. They summarized the correlations between various influencing factors and deformation data at different stages, and subsequently proposed early warning criteria based on the duration of deformation stages, crack characteristics, and displacement rates. [PERSON] et al. [17] proposed a landslide early warning system framework based on Earth observation technologies. Through case studies, they utilized satellite radar monitoring to detect precursory deformation of landslides, achieving early warning capabilities. [PERSON] et al. [18] studied the large-scale El Arrecife landslide at the Rules Reservoir in Spain and proposed a multi-sensor integrated monitoring approach based on DGPS, inclinometers, and InSAR technologies. Combined with structural kinematic analysis, this method effectively identifies landslide types, potential sliding surfaces, and estimates landslide volume. Previous studies on the relationship between water level fluctuations and slope stability have primarily focused on reservoir shore slopes, with limited attention given to open-pit mine slopes. In fact, open-pit mine slopes differ significantly from reservoir shore slopes in terms of morphology and engineering geological conditions. The main distinctions are as follows:1. Reservoir dams are generally constructed atop canyon landforms, which typically develop due to tectonic uplift and consist of valley slopes made of hard rocks. Due to long-term fluvial incision and tectonic uplift, steep cliffs are often composed of igneous or metamorphic rocks, while softer rocks are mostly sedimentary. Hydrodynamic landslides frequently occur on slopes composed of soft rocks or rock masses containing interbedded soft layers. 2. The morphology of high and steep open-pit mine slopes differs from that of reservoir shore slopes. After impoundment, lateral water pressure on reservoir slopes generally enhances slope stability, whereas the vertical downward water pressure acting on the flat bench faces of open-pit mines adversely affects slope stability. It is evident that there is currently no targeted research addressing the hydrodynamic landslide mechanisms of slopes with the aforementioned hydrogeological and engineering geological characteristics. However, it is important to note that a large number of open-pit mines in China are expected to enter the phases of production cessation, closure, and comprehensive rehabilitation in the foreseeable future [19]. Given the lack of mature technical guidelines or standards for this issue, there is an urgent need to develop an efficient and feasible dynamic evaluation method for the overall slope stability at different stages of the water impoundment process after mine closure. Such a method would provide critical technical support and reference for geological hazard prevention, ecological restoration, and post-mining utilization of large open-pit mines. This study aims to explore evaluation methods for slope stability following water impoundment in closed open-pit coal mines, with the goal of providing scientific guidance and support for mine reclamation. Based on large-scale parallel mechanical computations and the strength reduction method, the stability coefficient is defined, and its spatial distribution is simulated to visually identify potential landslide zones and quantify landslide risks. This approach enables three-dimensional dynamic stability analysis of the overall slope during the water impoundment process after mine closure, as well as effective assessment of backfilling remediation schemes.