Instability prevention and control of waste dump slopes with different consolidation degrees under the influence of rainfall

Abstract

The stability and management of waste dump slopes are pivotal research topics in geotechnical engineering and have long posed central challenges in coal mine ecological restoration. Controlling the stability of waste dump slopes is challenging due to the influence of time, rainfall, stacking height, and angle on the consolidation degrees of coal gangue. On the basis of those mentioned above, the study focuses on the waste dump slope of Dongpo Coal Mine as the primary research subject. A consolidation model is developed to dynamically adjust key parameters of coal gangue based on varying degrees of consolidation, burial depth, and stress. The results of coal gangue solidification experiments was used to further develop the constitutive model of FLAC3D software. The characteristic of coal gangue with varying consolidation degrees in response to burial depth and stress variations can be realized. The stability of the waste dump slope under different slope angles, continuous rainfall, and various support measures were simulated. The threshold values for slope angle and rainfall duration that precipitate slope failure were determined. The relationship of slope angle (θ), rainfall duration (t), and slope safety factor (Fs) was elucidated and a comprehensive comparative analysis of four prevalent slope support measures was performed. The research findings indicate that with an increase in slope angle, the slope safety factor demonstrates an inversely proportional trend of decline, suggesting that the slope angle of Dongpo Coal Mine waste dump should be reduced from the original 42°–33°. At a slope angle of 33°, the slope reaches the instability threshold after five days of continuous rainfall, with the slope safety factor steadily decreasing and stabilizing as the rainfall duration prolongs. Finally, a combined support measure of three-dimensional grid planting and slope protection piles for waste dump slopes were proposed, which has yielded excellent results in field applications. This research offers valuable insights for the evaluation and management of waste dump slope stability across different consolidation degrees.