Landslide Mechanism And Back Pressure Slope Protection Treatment Technology Of Sunken Open-pit Mine

Influenced by the complex rock and soil structure,as well as the external conditions such as blasting,rainfall and mechanical disturbance,the local landslide in the production process of the open pit is common.Internal dumping is a form of dumping formed in the production process of open-pit mine in order to reduce the occupation of land resources and the transportation cost of waste soil.It is an effective way to improve the overall stability of the slope to use the internal dumping technology to back pressure landslide,combined with the supporting effect of the retaining dam on the internal dumping soil,which can reduce the exposed area and time of the slope,and reduce the effect of external force disturbance.Therefore,it is of great engineering significance to carry out the research on the landslide treatment technology of back pressure slope protection in open-pit mine for improving the safety and economy of mining.On the basis of field investigation,using indoor test,theoretical calculation,numerical simulation,engineering practice and other methods,the landslide disaster mechanism and back pressure slope protection treatment technology of sunken open-pit mine are studied,and the landslide treatment which considering economy and safety is put forward,and its reliability is explored.The main work is as follows:(1)The landslide in an open-pit mine of a depression was investigated on the spot to obtain the relevant engineering geological conditions and basic landslide information.The factors affecting the formation of landslide,such as topography,lithology,water and human engineering activities are systematically analyzed,and the disaster mechanism of hanging wall landslide and footwall landslide in open-pit mine is revealed.(2)Soil mechanics foundation test is carried out to obtain physical and mechanical parameters of rock and soil.Combined with the actual terrain and geological conditions of the mine,the landslide treatment technology based on the innovative idea of back pressure slope protection is put forward,the retaining dam and internal dumping process scheme is designed,the optimal design scheme by using the fuzzy comprehensive evaluation method is selected,and the back pressure slope protection treatment technology combining the reserved retaining dam and the covered dumping method is obtained.(3)The mechanical model of retaining dam under the action of groundwater seepage is constructed,and the expressions of sliding stability safety factor of artificial dam and reserved dam are derived.The influence of slope angle,dam height,dam crest width and groundwater level height on safety factor of artificial dam and reserved dam are discussed.(4)Considering the structural characteristics of the internal dumping,the expression of the safety factor of the internal dumping is deduced,and the numerical model of the back pressure slope protection of the internal dumping is established.The influence law of the bench height,platform width and slope angle of the internal dumping on the safety factor of the internal dumping is analyzed,and the structural parameter effect of the internal dumping in landslide treatment is revealed.(5)According to the feasibility study conclusion of the back pressure slope protection landslide treatment technology,the interception and drainage ditch are set to reduce the influence of rainwater infiltration on the stability of the internal dump slope and reserved retaining dam.The GNSS online monitoring system of slope displacement is set up,the stability trend of the slope in the area is predicted and treated,and the back pressure slope protection treatment technology is optimized.The results of this paper will play an effective guiding role in landslide control of sunken open-pit mine.