Rockburst Prediction Of A Deep Underground Gold Mine And Stability Analysis Of The Shallow Goaf

Deep mining are foreseeable becoming increasingly popular among mines because of the depletion of open-pit mineral resources and growing demand of raw materials to support construction and manufacture.Mining at great depth are often facing with the shallow goaf instability and the deep rockburst.These issues have become the bottleneck of the deep underground mineral exploitation,and pose some safety threats that needed to be addressed at the first place.Having investigated on an underground gold mine in Shanxi,this thesis particularly aims to analyse the stability of the shallow goafs and predict the rockburst possibilities during the process of deep mining.The main tasks of the project are including:based on the on-site survey results,utilizing MIDAS/GTS,a powerful geotechnical analyzing computing package,to analyse the stability of the existing shallow goafs and the impact of proposed deep mining on those goafs;based on the analysis results of typical rock's rockburst proneness,combined with the geological data and the reasonable deep mining approaches,respectively using Phase~2 and MIDAS/GTS for the simulation of roadway tunneling and ore exploitation to obtain the rockburst grade during and after the process of deep mining.The main contents of the paper are as follows:(1)Based on the indoor rock mechanics testing,rock mechanics parameter determination and detection of shallow goafs,combined with the geological data and the design of deep mining,a three-dimensional numerical model of the mine was established.(2)Based on the three-dimensional numerical model of the mine,using MIDAS/GTS to analyse the stability of shallow goafs and the impact of deep mining on shallow goafs.The results indicate that shallow goafs as a whole is stable,but 12#and 13#goafs which are located near the auxiliary shaft in 827m,18#and 19#goafs which are lacated above the interior shaft in 525m,and 24#goaf are metastable.If deep mining can be strictly carried out according to the design,the impact of deep mining on shallow goafs stability is less.(3)Combined with the indoor testing results,using three rockburst proneness indexes to analyse the typical rock's rockburst proneness.The results indicate that all the five kinds of rocks have rockburst proneness,and the rockburst proneness of gneiss which is in 425m is strong,others'rockburst proneness are modetate.(4)Based on the three-dimensional numerical model of the mine and the design of deep mining,combined with Russenes rockburst criterion,respectively using Phase~2 and MIDAS/GTS investigate the process of the roadway tunneling and the ore exploitation to predict the rockburst grade in the process of deep mining.The predicting results are as follows:In the process of the deep roadway tunneling:(1)roof:moderate-strong;(2)two sides:moderate;(3)footwall:slight.In the process of the deep ore exploitation:(1)roof:moderate;(2)footwall:moderate in 425m and363m,strong in 300m.This paper investigate the shallow goafs stability and the rockburst grade in the process of deep mining which are the security issues of deep mining.This study provides technical support for a gold mine in Shanxi Province to safely exploit the deep minerals,and it has theoretical and practical significance to exploit other deep mines.