STABILITY ANALYSIS OF OPEN-PIT SLOPES IN COLD REGIONS BASED ON REDUCTION OF ROCK MASS MECHANICAL PARAMETERS

Abstract

Open-pit slopes in alpine mining areas of western China are significantly affected by freeze-thaw cycles, snowmelt infiltration and weathering, leading to severe deterioration of rock mechanical properties and difficulties in stability evaluation. Taking the rock slopes of Jingxi-Barak open-pit mining area of Xinjiang Jinchuan Mining Co., Ltd. as the research object, laboratory rock mechanical tests, rock mass strength parameter reduction and numerical stability analysis of slopes were carried out. Field sampling, standard specimen preparation and indoor mechanical tests were performed to systematically obtain physical and mechanical parameters including compressive strength, tensile strength and shear strength of four types of rock masses (tuff, limestone, tuffaceous sandstone and crystal tuff) under natural and saturated conditions. Combined with the structural characteristics of rock mass and excavation disturbance in the mining area, reasonable reduction of mechanical parameters of in-situ rock mass was realized. Numerical models of typical slope profiles were constructed, and seepage field analysis was conducted via the Seep/W module. The Sarma method and Spencer method were adopted to implement limit equilibrium stability calculations. The results show that the safety factors of slopes in the study area range from 2.077 to 2.247, which are higher than the allowable safety factor of 1.25 specified in relevant codes, indicating the overall good stability of slopes in the mining area. The research results can provide experimental basis and technical reference for slope safety evaluation, excavation design and geological disaster prevention and control of open-pit mines in cold alpine regions.