Coupling Effect Of Coal Pillar-Roof And Stability Evaluation Of Pillar Goaf

As a common coal mining method in our country,room-type coal mining has caused a large number of pillar goafs and coal pillars underneath while mining coal resources.Therefore,it has become an important factor in the prevention and control of mine goaf disasters and the recovery of remaining coal resources research focus.In order to reveal the key to the long-term stability control of the pillar goaf,this paper uses numerical simulation methods to study the creep failure of the pillar goaf under the long-term overburden load based on the existing research.The uniaxial compression test was carried out on the coal pillar-roof assembly specimens of different sizes and shapes,and the failure characteristics of the specimens of different sizes and different shapes were initially obtained,and the influence of the roof during the failure process was verified.The critical instability state during the dynamic instability of the coal pillar group was determined,and the pillar-type goaf stability evaluation model under various influencing factors was established.The main work and results are as follows.(1)The process of coal pillar creep instability and failure is studied,and the elastic core area distribution and stress state inside the coal pillar in different time periods are obtained.The different stages of coal pillar creep and the main failure forms are analyzed,and the coal pillar's failure is given.Stable time criterion.(2)The load-bearing compression failure characteristic test of coal pillar-roof assembly of different sizes and shapes was designed,and the failure characteristics and acoustic emission phenomenon of different specimens were analyzed,the influence of size and shape on the failure process of composite specimens is studied.and the corresponding relationship between the surface failure of different specimens and the development of internal cracks was obtained.(3)The dynamic instability stress transfer and the development of plastic zone in the coal pillar group are analyzed,and it is determined that when the coal pillar instability area ratio is 22.80%,it is the critical instability state of the remaining coal pillar group,and the coal pillar instability area ratio is 56.51%.When the coal pillars are left behind,the coal pillars are in a state of complete instability.(4)AHP analysis of the key factors affecting the stability of the pillar goaf was carried out,combined with the fuzzy comprehensive evaluation method,a multi-index pillar goaf stability evaluation model was established,and the stability evaluation of the specific mining area was carried out on this basis.The paper has 43 figures,18 tables and 108 references.