Stability evolution of upstream tailings dams under extreme rainfall conditions

Zhang Xiaobo; Wang Guodong; Ma Yongli; Cheng Jun; Yin Cheng; Li Haigang

doi:10.16186/j.cnki.1673-9787.2025030011

Abstract：Objectives This study investigates the stability of upstream tailings dams in the Poyang Lake re-gion under frequent heavy rainfall and prolonged rainfall conditions,focusing on the evolution of seepage fields and dam stability under different rainfall scenarios.Methods An upstream tailings dam in the Poyang Lake region was selected as a case study.Fluid-solid coupling simulations were conducted using the Seep/W and Slope/W modules of the finite element software GeoStudio.Results Under extreme rainfall condi-tions,rainfall infiltration reduced dam stability,and the rate of decrease in the safety factor was positively correlated with rainfall intensity.At rainfall intensities of 500 mm/d and 700 mm/d,the tailings dam rap-idly reached saturation,with safety factors falling below the minimum allowable value at 36 h and 24 h,re-spectively,indicating instability.Under prolonged rainfall conditions,the safety factor gradually de-creased;However,under moderate(25 mm/d)and heavy rainfall(50 mm/d),the dam remained stable af-ter 70 days of continuous rainfall.Conclusions Under heavy rainfall conditions,increased water content and saturation of surface tailings in certain areas readily induced shallow sliding instability,the main cause of localized stability reduction.Under prolonged rainfall conditions,differences in permeability across tail-ings layers caused localized increases in pore water pressure and unit weight within the dam,potentially triggering deep sliding instability and thereby contributing to overall stability reduction.To quantitatively characterize the rise of the seepage field,an infiltration coefficient was proposed to represent the magnitude and rate of the rise.The findings provide a reference for stability analysis of upstream tailings dams in the Poyang Lake region under complex rainfall conditions.