Study On The Stability Of Working Slide Of Weijiamao Open Pit Coal Mine

The southwest working group of Weijiamao open pit coal mine suffered from landslide at the end of 2018.Due to the impact of land acquisition,it was unable to move forward,which affected the safety production of the open pit coal mine and the completion of the annual production task.Based on this background,the paper comprehensively uses the methods of field investigation,engineering exploration,geotechnical test,The mechanical properties of concrete are studied by theoretical analysis,rigid limit equilibrium method and numerical simulation,the landslide mechanism of the southwest working side of Weijiamao open pit coal mine,and formulates the landslide control plan of the southwest working side,which ensures the safe production of Weijiamao open pit coal mine and successfully completes the annual production task.The research methods and conclusions adopted in this paper have a strong theoretical guidance and practical application value for the case of open pit coal mine with similar engineering conditions.Based on the comprehensive analysis of the geological conditions and the current situation of the working side slope of Weijiamao open pit coal mine,combined with the numerical simulation calculation,the displacement characteristics,shear strain and plastic zone expansion of the slope are mainly revealed,the mechanism of slope instability and failure mode are analyzed,and the sliding horizon and scale of the slope are found out.The main sliding direction of the potential sliding body is 31°~48°and the potential sliding volume is about 1.25 million m~3.The southwest working slope is along the bottom of the weak layer and the back edge presents arc sliding,which causes the damage of the overlying soil and sand.The main mechanism of landslide is excavation unloading and shear failure,while on the macro level,it is creep sliding and tension crack traction landslide,showing the floor bedding and the back edge of slope body showing the arc shear failure mode of location and push.The influence of blasting vibration on slope stability is studied creatively,and LS-DYNA model is used to simulate.The results show that with the increase of blasting center distance,the impact of blasting vibration on slope body is gradually weakened;with the increase of charge,the dynamic response of slope is enhanced.Because the sandstone at the bottom of slope is still blasting and peeling off,it is suggested to reduce the charge of blasting once as much as possible,and pay attention to the deformation of slope after blasting.The sliding influence distance is calculated creatively,the stability coefficients of the whole slope and the local slope calculated by the limit equilibrium method are less than 1.1,which does not meet the requirements of the code.The particle element PFC3D is used to analyze the subsequent sliding range of the working slope soil layer landslide.The conclusion shows that the particles begin to slide down under the action of gravity,but the falling speed is not fast.With the decrease of the height of the particles from the ground,the sliding speed of the particles tends to decrease gradually.Due to the decrease of the height from the ground,a certain presser foot area is generated at the foot of the slope.When the model reaches equilibrium,the sliding distance about 54m.Combined with the current production situation of open-pit coal mine,a reasonable landslide control scheme is put forward,which successfully prevents the landslide accident.