Study on overburden strata movement law at face end of high cutting fully-mechanized top coal caving face in ultra thick seam

in order to study the gateway drving technocgy along the goaf whether could apply to or not to the high cutting rul-mechanized top coal caving miningface in uitra thick seam,.based on No.8204 high uting rul mechanized top coal caving mining face in ulrathick seam of Tashan Mine as an engineeing background.a surface ground subsidence observation,micro seismic observation and theoretcal nalysis method were appied to the studly on the overburden strata movement range,the cracks feldistribution,the movement features and structure features. The resuts showed that height ofthe rof fa赳ling zone in igh cutting rll- mechanized topcoal caving mining face in ulra thick seam wth a thickness of 15 m was 43 m,the height of cracks zone was 43 ~ 20 m and rock strata over 200 m above coal mining ace was in a bending and subsidence zone. with the of aling angle and moving angle as boundary:three crack development zones including the stlding breaking zone.ension and compression crack zone and compression crack zone formed at the end of high cutingfall - mechanized op coal caving mining face. Before the goaf stablized.a " ow cantilev er beam-upper bricks lined beam" struture was formed at the end of coal mining fac . Wih the cal mining face pushed fowar,the overburdenstrata would be further moved and subsided. Aferthe goaf stabilized,the low cantlever beam would be broken and a delta sliding zone was forme . The upper key layer would be still existed with mode of bricks lined beam structure and could control the distribution of the lateral stress field.