Study On Fracture Instability Mechanism And Monitoring And Early Warning Model Of Filling Body-pillar System

The combined system of filling body and pillar is the common engineering structure in underground mine.The bearing effect of the whole system directly determines the quality of filling engineering in mining area.The mechanism of interaction between the systems was studied,and the mechanical response in the process of failure and deformation was used to identify the precursor fracture characteristics of the system.It was of great practical significance to establish a comprehensive evaluation and early warning system.Combined with theoretical analysis,indoor mechanical experiments and numerical simulation,the interaction mechanism and fracture deformation of the backfill pillar system were studied.The results were as follows:1)The mechanical experiments of single filling body and backfill pillar system were carried out,and the characteristics of Acoustic Emission activity,stress-strain and other mechanical responses and failure forms of them were analyzed.The results showed that the filling system with pillar support has better bearing capacity.With the enhancement of the lithology of the pillar,the bearing capacity of the system presented a positive correlation.2)Through the method of time difference location,the three-dimensional location of Acoustic Emission source was carried out,which showed the distribution state and accumulation evolution process of the fracture source in the filling body and the backfill pillar system directly and effectively.Comparing the localization results of single filling with filling pillar system,it was found that the internal seismic source is disordered in the process of single filling failure and deformation from the nucleus initiation to the most part of the internal area while the seismic source of the backfill-pillar system with filling body is characterized by the orderly development of the pillar as the main axis and scattered filling area.3)Five kinds of filling and pillar systems with increasing lithology were simulated.Three layers of fracture evolution zones were concluded.The first stage was the pillar fracture extension zone,the second stage was the whole system fracture through zone.4)Based on the mechanical experiments,Acoustic Emission source location and mesoscopic simulation results of precursor fracture characteristics,revealed the backfillpillar system instability evolution law,build a comprehensive evaluation system of backfill-pillar system monitoring and early warning model.Figure54;Table5;Reference 57...