Stability Analysis Of Boundary Pillars In The Transition From Open Pit To Underground In Yingping Mine Of Wengfu Phosphate Min

In this paper Taking Yingping ore of Wengfu Phosphate Mine as the research background,aiming at the problem of reserved parameters and stability of boundary pillars from open-pit to underground in Yingping ore,systematically studies the reserved parameters and stability of boundary pillars by means of theoretical analysis,calculation and numerical simulation.The state mode of boundary pillar is discussed,the evaluation and decision-making system of boundary pillar stability factors is established,the retention scheme of boundary pillar is analyzed,and constructed the boundary pillar stability analysis numerical simulation model,the results are as follows.(1)The four state modes of the boundary pillar are stable state,slight deformation state,severe deformation state and instability failure state.The state of these four kinds of boundary pillars is also the process of instability and failure of boundary pillars.(2)There are five factors affecting the stability of boundary pillar in the study area.According to the analytic hierarchy process,the order of weight influence from large to small is safe thickness,self strength,load,structural plane,blasting vibration.(3)According to the results of four theoretical calculation methods: engineering calculation method,fixed beam,Proctor arch and K.B.Rubienyita.The thickness of the boundary pillar should be at least more than 20 m.(4)The numerical simulation results show that when the thickness of the boundary pillar is20 m,the maximum displacement of the vertical displacement nephogram is 4.70 cm and 4.95 cm respectively,which is less than the allowable limit displacement of 5cm.At this time,the pillar will not be unstable and damaged,which verifies the rationality of the theoretical analysis results.The research results of this paper can provide theoretical support and reference for the boundary pillar reservation parameters of Yingping mine from open-pit to underground mining in Wengfu Phosphate Mine,and provide reference for the boundary pillar reservation of other metal and nonmetal mines from open-pit to underground mining.