Disaster Mechanism And Prevention Technology Of Caving In Mined-out Area Of Pangjiahe Gold Mine

As a precious metal mineral resource,gold mine is widely distributed in China,and the gold mined has important industrial value.In the condition of steeply inclined medium-thick orebody,the instability problem of the remaining goaf is more prominent when the shallow hole retaining method is used.The existence of mined-out area is easy to lead to caving impact disaster,which poses a serious threat to underground personnel and equipment,and increases the difficulty for safe and efficient mining.Taking the mining status of shallow hole retention method in Pangjiahe gold mine as the research object,this paper adopts the method of field investigation,theoretical analysis,physical experiment and numerical simulation to make a systematic study on the problem of goaf caving and disaster in the application of this mining method.According to the results of on-site structural plane investigation and point load strength test,the basic quality indexes of the orebody and surrounding rock mass of the Pangjiahe gold mine are 438.66,353.25 and 442.37,respectively,which belong to the medium stable level.Based on Hoek-Brown strength criterion,the mechanical parameters of ore body and surrounding rock mass are calculated.For mining goaf caving in to problems,using the numerical simulation analysis of the caving process,get PangJiaHe development,gold mine goaf roof caving is mainly due to the crack along the joint through the intact rock bridge,caving zone is given priority to with tensile failure,stability region with shear failure is given priority to,formation and dissipation of periodic stress balance arch,It is the main reason that the caving is slow and fast alternately.The caving mechanics model of the goaf roof was constructed,and the critical caving span value of the goaf was calculated to be about 10m.The characteristics of falling in goaf and the mechanism of disaster are expounded.The estimation value of the velocity of the impact gas wave and the determination method of the safety distance are given.The safety distance is determined to be 5m.Through numerical simulation analysis,the reasonable tailings filling height of the stope is determined to be 30m.Combined with the fuzzy mathematics optimization model,the scheme of caving partial top pillar+full tailings filling is selected to treat the goaf,and the method of caving top pillar treatment is given.Through field industrial test and economic benefit analysis,it is confirmed that the selected goaf treatment scheme has a good filling effect.After backfilling in single middle section,the expected profit and benefit can reach 10,025,800 yuan,and the economic benefit is relatively significant.In this paper,the mechanism of disaster caused by caving in the goaf is analyzed,and the treatment scheme of the goaf combined with collapse and filling is given,and the field industrial test is carried out in Pangjiahe gold mine.The practical application shows that this technology can effectively solve the problem of disaster caused by caving in goaf encountered in the mining of steeply inclined medium-thick ore body,and can realize the safe and efficient mining of this kind of mine.