Progressive failure mechanism of sandy loess slopes under mining disturbance-rainfall infiltration effects

Abstract

To investigate the instability process of sandy loess slopes under mining disturbance-rainfall infiltration effects, a two-dimensional physical model test was conducted on the sandy loess slope in Dabaibao Village, Shenmu City, Shaanxi Province. Displacement monitoring, crack statistical analysis, and pore structure characterization were employed to focus on the deformation response and failure mechanism of sandy loess slopes under the influence of mining disturbances-rainfall infiltration. The results indicate that slope failure exhibits a progressive evolution characterized by “tension-shear-sliding”, which can be divided into four stages: mining-induced pre-damage, tensile crack propagation, slope toe localized slip, and overall sliding instability. During the test, the maximum settlement displacement was 2.1 cm, equivalent to 2.1 m at the prototype scale (1:100), demonstrating significant localized deformation characteristics. The development of cracks intensified notably during the rainfall phase, with the rate of change in the slope’s fractal dimension being higher than that during the mining phase. These observations support the interpretation that mining disturbance predisposed the slope to subsequent instability through initial structural damage, whereas the subsequent rainfall phase was associated with accelerated crack propagation, deformation, and eventual sliding. Furthermore, pore structure coarsening and connectivity enhancement were most pronounced in the slope surface area, followed by the toe, and were relatively weaker at the top, indicating a strong correlation between microstructural degradation and the progression of macroscopic sliding. These research findings provide experimental evidence for the stability assessment and disaster prevention of sandy loess slopes in mining areas.