Study on stability assessment of buckling failure and rainfall-induced instability mechanism for steeply inclined rock slope

To address challenges associated with the stability assessment and engineering control of buckling failure in steeply inclined rock slopes, this study takes the southern slope of the Longyu Open-Pit Mine as a case study and adopts an integrated approach combining theoretical modeling, field monitoring, and numerical simulation. First, under the assumptions of coordinated deformation and small strain, a differential equation governing the behavior of the surface rock layer is derived. This leads to the formulation of a safety factor defined as the ratio of the critical to the actual slope length. The analysis indicates that the slope remains stable when the thickness of the rock layer exceeds 10 m and the elastic modulus is greater than 32 GPa, thereby establishing a robust mechanical model for buckling failure. Second, based on field monitoring data of displacement and strain, orthogonal testing and factor sensitivity analyses are conducted. The results reveal the following ranking of influential factors: rock layer thickness ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>R</mml:mi> <mml:mo>=</mml:mo> </mml:math> 0.38+39.8 %) is an exceptionally sensitive positive factor; cohesion ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>R</mml:mi> <mml:mo>=</mml:mo> </mml:math> 0.25) is a highly sensitive positive factor; unit weight and groundwater level are significantly sensitive negative factors; whereas the influence of elastic modulus is negligible ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>R</mml:mi> <mml:mo>=</mml:mo> </mml:math> 0.03). These insights provide a clear priority hierarchy for monitoring and stability control measures. Finally, by incorporating real-time rainfall intensity data, FLAC3D simulations demonstrate a strong negative correlation between rainfall intensity and slope stability. Heavy rainfall is identified as a critical threshold triggering stability failure. Under such conditions, the maximum slope displacement increases by 175 %, reaching 5.5 m, and the shear strain increment develops into an arc-shaped sliding surface. The slope interval between 1360-1390 m is identified as the core risk zone, while the interval from 1290-1310 m acts as a key shear outlet. This clarifies the evolutionary pathway and key focus areas for preventing rainfall-induced instability. The findings of this study offer a solid theoretical foundation and practical technical support for the monitoring, risk warning, and engineering management of similar steeply inclined slopes.