| The waste dump is one of the necessary facilities of open-pit mines,where the large amount of bulk material accumulated is an important source of disasters in dumping sites.Once the mine waste dump encounter heavy rainfall,it is easy to result in serious geological disasters such as landslides or mudslidess,which will bring serious loss of life and property to the mining areas,farmland and residential areas in the downstream or surrounding areas.In this paper,with the bailingwan waste dump in yinshan mine as an engineering example,the slope stability under different rainfall conditions was investigated through laboratory test,field test,and numerical simulation.The main achievments are summed up as follows:(1)According to the particle-size distribution results in the filed,the distribution law of the particle-size at different heights of the waste dump was achieved using the modified Rosin-Ramuler model.And the shear and triaxial compression tests were conducted for the bulk material collected in the field respectively.The results show that the cohesive force and the angle of internal friction of the bulk material in the waste dump decreased to some extent after they are saturated.(2)The seepage and stability analysis of two typical dangerous slope profiles of the waste dump under three rainfall conditions of heavy rain,torrential rain and heavy downpour were carried out.The results show that at the beginning of rainfall,the pore water pressure on the slope increases rapidly and the slope safety coefficient decreases immediately due to the infiltration of rainwater into the slope of the waste dump.However,under different rainfall conditions,the good stability of the waste dump occured with a minimum safety coefficient of 1.42.When the rainfall intensity is constant,the slope safety coefficient decreases steadily with the continuous rainfall.But for section of slope II,the safety coefficient rises slightly after the decrease.For a constant rainfall time,the larger the rainfall intensity is,the larger the rate and extent of the increase of the volume water content of the slope will be.So it has a great infuence on the slope,leading to a increase in the decrease rate and extent of safety coefficient.(3)Taking the final slope under the final design height of the waste dump as the research object,the influences of the reserved platform width of 30 m,35 m,40 m,45 m,50 m,55 m and 60 m on the slope stability under the natural condition and the above three rainfall conditions were analyzed.The results show that the reserved platform width is positively proportional to the slope safety coefficient.Under a natural condition,the slope has a good stability,with the minimum safety coefficient of 1.533.And under the heavy downpour condition,the platform width meeting the requirement of the slope safety coefficient of 1.15 should be greater than or equal to 45 m.As a result,the reserved platform should has a width of 55 m to ensure a certain margin of the safety coefficient. |
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