Research On Stability Of The Coal Pillar In The Slot Of Full-Mechanized Top-coal Caving Long-wall Mining Face

With China’s growing coal mining depth, the original rock stress increases, the pillar width leave more and more, in this way, not only causes coal waste, but also interval pillar will appear stress concentration after workface stopping, and lead to serious threat of the lower coal safety production. Further more, the interval pillar experience gateway excavating, mining influence of before and after workface three stages. Along with the increase of mining degree, the degree about deformation and damage of the pillar become more and more big, the damage law is extremely complex, therefore interval pillar’s stable or not to be crucial to coal mining. It is great significance to achieve high recovery rate through the pillar of the reinforcement method to improve strength and stability of pillar.This paper is based on the4302working face of Chang Ping coal seam no.3of background, with the long wall fully-mechanized sublevel caving coal interval pillar as the research object, utilize the mechanical theory analysis and numerical simulation, the field measured to study the basic conditions of pillar stability, reasonable left width of pillar, control method of pillar stability and so on, this paper puts forward a "low pre-tightening force high strength anchor nets combined support+special circumstances grouting strengthening" strengthening technology of pillar, applied in engineering practice, and has achieved some research results:(1) With the help of key layer theory, establish long-wall fully-mechanized sublevel caving interval pillar, before working face will mine, after working face mining three different stages of the mining mechanics model, the master of the overlaying strata break rule; Through the analysis of key blocks influence pillar stability, this paper reveals the basic condition of pillar stability is existing certain width elastic nuclear in interior pillar.(2) Adopt the theory analysis and numerical simulation, the research on the interval pillar bearing pressure distribution law and the dynamic evolution process, it is concluded that side of the interval pillar gob area contain edge fracturing area, the plastic zone, the elastic zone, the original rock stress area; And the conclusion that reasonable pillar width formulas for the:(3) Using theoretical analysis method to study the interval pillar strength and failure form, stability influence factors, relationship between stability and supporting, it is concluded that the long wall fully-mechanized sublevel caving interval pillar reasonable consolidation method, anchor supporting combination with grouting strengthening, effectively improve the stability of pillar.(4) Based on the control concept of whole strengthening pillar stability, this paper puts forward the "low pre-tightening force high strength bolt support+special circumstances grouting strengthening" strengthening technology of pillar.Applying research results to interval pillar reinforcement of the4302long-wall fully-mechanized sublevel caving face in the coal seam no.3of Chang Ping mine coal, at the same time verify the rationality by field measurement methods.