Study On Landslide Risk Assessment In The First Mining Area Of Open-pit Mine In Block Ⅰ Of Thar Coalfield

The artificial slope formed by open-pit mining changes the original stress balance in rock mass,which is easy to cause landslide disaster.With the continuous deepening of the first mining area of the open-pit mine in Block Ⅰ of Taer Coalfield,the weak layers are gradually exposed,and the weakening effect of groundwater on the mechanical properties of rock and soil.These unfavorable factors will lead to an increase in the probability of landslides.Therefore,in order to improve the level of disaster prevention and control of open-pit mines,to clarify the impact of landslides on open-pit mines and the economic losses caused by landslides,and to reduce the harm of landslides to human life safety and property,it is necessary to carry out landslide disaster risk assessment in the first mining area of the open-pit mine in Block Ⅰ of the Tar coalfield.This paper takes the open-pit mine of Ⅰ block in Pakistan Thar Coalfield as the research background.We analyzed the previous geological survey data of Block Ⅰ in Tar coalfield,Pakistan,obtained the geological structure,stratigraphic lithology and hydrogeological conditions of the mining area,and determined the physical and mechanical parameters of rock and soil in each rock layer.This paper determines the method and process of open-pit mine landslide risk assessment.Through numerical simulation and theoretical analysis and calculation,we delineated the scope of landslide hazards,analyzed the slope stability of the stope and the probability of landslide instability,established a comprehensive fuzzy evaluation model,calculated the total risk value of the landslide,and determined the slope risk decision.The results show that : The landslide hazard range of Block Ⅰ in the Tar coalfield of Pakistan is mainly in the east side.The potential landslide volume is 8754 m³,and the sliding distance is about 680 m.Comprehensive vulnerability of hazard bearing body is medium vulnerability.The annual instability probability of landslide under natural conditions is 0.003,and the landslide hazard is moderate.The annual instability probability of landslide under rainstorm is 0.0245,and the landslide hazard is highly dangerous.The annual instability probability of landslide under seismic conditions is 0.018,and the landslide hazard is highly dangerous.Under natural conditions,the total risk value of landslide is 114700 yuan,and the estimated annual mortality rate is 0.0255 people/year.The total risk value of landslide under rainstorm condition is 11707600 yuan,and the annual mortality rate of population is expected to be 0.18375 people/year.The total risk value of landslide under seismic conditions is 43007400 yuan,and the estimated annual mortality rate is0.135 people/year.The population mortality rate is greater than the acceptable mortality rate of 10^-3 people/year,which is an unacceptable risk.The danger level under natural conditions is small geological disaster,the danger level under rainstorm conditions is medium geological disaster,and the danger level under earthquake conditions is medium geological disaster.Therefore,in view of the main influencing factors of the slope stability of the open-pit mine and the landslide mechanism,it is recommended to take landslide prevention and management measures such as internal dumping presser foot and drainage by desiccation to ensure the safety of personnel and property in the open-pit mine.The paper has 36 figures,20 tables and 89 references.