Stability Analysis And Influencing Factors Of Boundary Pillar In A Copper Mine In Yunnan

Based on a copper mine in Yunnan as the research background,this paper selects the boundary pillars converted from open pit to underground as the research object,and uses the traditional theoretical calculation methods and numerical simulation methods of the boundary pillars to study the stability of the boundary pillars.The copper mine has completed the conversion of open-pit mining to underground mining.At this stage,its boundary pillars are basically in a stable state.However,the mine needs to carry out land reclamation disaster recovery treatment for the open-pit pit according to the national policy,which requires the boundary pillars to be removed.In addition to bearing its own weight,it also needs to bear the additional load caused by land reclamation,so it is necessary to study and analyze the stability of the boundary pillar.This article first studies the stability of the boundary pillar at this stage,and analyzes the factors that affect the boundary pillar.Through the analysis of the influencing factors,determine the importance of each influencing factor to the stability of the boundary pillar.The research content of this paper mainly includes the following parts:⑴ For the researched mines,conduct geological data access and related geological surveys to determine the engineering geological conditions and geological strata of the mines.⑵ Select relevant rock samples,do indoor rock mechanics parameter tests to determine rock mechanics parameters;and use Hoek-Brown criterion to calculate rock mechanics parameters.⑶ Calculate the thickness of the boundary pillars by traditional theoretical calculation methods,that is,calculate the minimum safe thickness of the boundary pillars using the KB Rubienyita formula and the structural mechanics calculation method.The calculation results are 21.65 m and21.61 m,both of which are less than The actual thickness of the ore pillar in the realm ultimately determines that the pillar in the mine is stable.⑷ According to the actual conditions of the mine and the occurrence of the ore body,use FLAC3 D three-dimensional modeling software to establish a model that meets the actual situation of the mine,assign the mechanical parameters of the ore to the model,and analyze the simulation results under the condition of the overlying rubber end sand The maximum vertical displacement,the maximum principal stress,and the penetration of the plastic zone in,then determine the stability of the boundary pillar.⑸ Selecting the thickness of the intermediate pillar,the thickness of the boundary pillar and the thickness of the isolation floor as the influencing factors of the boundary pillar,3 factors and 3levels are set up according to the orthogonal test design,and a total of 9 schemes are formulated.Numerical simulation of each plan is carried out to determine the maximum displacement,maximum principal stress and minimum principal stress of the boundary pillar,and the orthogonal range analysis of the simulation results is carried out to determine the importance of each influencing factor to the stability of the boundary pillar.Formulate a land reclamation plan to provide a basis for decision-making and delineate the scope of mining protection.