Research On Monitoring，Forecast And Controlling Technology Of The Goaf In Dong Shengmiao

In underground metal mines, once the mineral deposits are recovered or mined, themined-out area also called as gob area, will form. Most of gob areas are usually emptybecause of the high cost of backfill in these areas. However, the formation of big gob areasdoes result in roof falls and other mining hazards, which threaten the safety of mining.Therefore, it need to take some measures to ensure the stability of gob area,the surroundingrock masses of the gob must be strengthened to minimize hazards caused by the gob. Thisthesis studies the gob stability, gob monitoring system, and management of gob area inDongshengmiao lead zinc ore mine. First, the stability of gob area was evaluated by thefinite difference FLAC3D code during mining stage. Then the monitoring system for gobarea was built to monitor the real-time gob activities. Finally, the upper surrounding rockcaving technology was implemented to backfill the gob area, which also improves themining safety. Concrete research content is as follows:Firstly, the gob area in the No.2and No.11were modeled by FLAC3D code and themodel was run to reach the initial equilibrium state. Then the mining process in blockNo.900was implemented and the stability of the gob area was analyzed. Next, the miningprocess in the adjacent block between No.850and No.900was modeled. By comparing thedisplacement, stress and shear strain rate in the model, it can be concluded that the uppersurrounding rock of the gob area remains stable during the mining process. The miningwork can be developed in this area but the real-time monitor during mining process isessential for mining safety.Secondly, the IMS microseismic monitoring system made in Austrilia were used inthis mine after comparing several different monitoring plans. An integrated monitoringsystem is established in conjunction with the results of FLAC model, laboratory virtualanalysis and the unique nature of current mining status. First, the positioning accuracy ofthe system was checked and confirmed. Then the3D mine model was imported in the3D visualized data analysis software JDI package. Through this way, the time and location ofmicroseismic events can be fixed and visualized. Finally, the obtained microseismic eventsfor a choosing area can be extracted and analyzed. Using these data the accumulatedapparent volume and average energy index curve can be drawn to evaluate the stability ofsurrounding rock for a span of time. Through the average displacement and apparent stresscontour figures, the stress state and deformation of the surrounding rock can be obtainedwhich is used to estimate whether the surrounding rock is failure or not. By predicting thepotential unstable area during mining process, this integrated monitoring system doesensure the mining safety of this mine.Finally, in order to fill the empty gob area, transfer and mitigate the stressconcentration in the surrounding mining area, two techniques, tailing-cemented filling andupper surrounding rock caving, were provided to manage the gob area according to themineral deposit status in this area. After analyzing the technical and economic evaluation,the upper surrounding rock caving technology was implemented. By employing thistechnique, the safety for both mining equipment and personnel was improved.Now Dong mine have been continuing excavating, excavation process of upper plateof the surrounding rock is stable,which is similar to the numerical simulation results. Themicro seismic monitoring and caving on the positive plate surrounding rock ensures thestability of mined-out area,which has significance of promotion.