The Movement Law Of Roof In Longwall And Pitching Oblique Mining Area Of Steeply Dipping Seam

Steeply dipping seam is recognized as a difficult coal seam in domestic and foreign mining circles.In recent years,steeply dipping seam mining has made great progress in theoretical research,technical application and equipment development,but mining practice shows that there is still uneven support loading in this type of coal seam mining and is prone to tip and slide,coal wall flank and Because of the frequent occurrence of fly gangue,the pseudo-tilt fully mechanized mining method can effectively solve the above problems,Therefore,in-depth study of the surrounding rock deformation and destruction of the law of movement in longwall and pitching oblique mining area of steeply dipping seam,Provide theoretical support for the state control.Based on the engineering background of longwall and pitching oblique mining area of steeply dipping seam in Lvshuidong Coal Mine,a large-scale three-dimensional physical similarity simulation experiment,numerical simulation and on-site mining pressure observation comprehensive research methods are used to analyze the features of space roof deformation,breakage,movement and filling,The mechanicalresponse of main roof under the action of unbalanced filling.The research results show that the breaking of the immediately roof has obvious zoning and timing characteristics in pitching oblique working face of steeply dipping seam.The movement space of the falled roof is reduced in the pitching oblique working face,and the gangue filling range is increased.An effective support area of filling gangue(about 2/5 of the working face length)is formed in the lower part of the goaf.The main roof is first broken and cycled Sexual broken mainly occurs in the middle and upper areas along the inclined,and it's fractures are distributed along the inclined;under the support of the gangue filling,the lower part of main roof failures lag behind the middle and the upper part,and it's fractures extend along the strike,and the damage scope and extent are less than the middle and upper part;the stability of the roof in the Head T-junction area of the working face is less than Tail T-junction area.The main roof has obvious regional differences between stress distribution and deformation under the influence of unbalanced filling of the falling roof in the pitching oblique mining area.The stress release and deformation degree on middle part and upper part of main roof and stress concentration on its lower part in pitching oblique mining area are less than the basic top of the true oblique mining area,resulting in the damage range of the main roof of the pitching oblique mining area is less than the main roof of the true oblique mining area.Obviously,the stability of the main roof in the longwall and pitching oblique mining area of steeply dipping seam is higher than that of the true oblique mining area.With the increase of the pseudo-bevel angle and the range of effective support area in the lower part of the goaf,the main roof stability is gradually increased.The characteristics of strata behaviors in pitching oblique working face of steeply dipping seam are similar to that of the true oblique working face.However,the"support-surrounding rock" effect relationship is more complex,especially the impact effect of the caving roof in the goaf is an important reason to affect the stability of the "R(roof)-S(support)-F(floor)" system.Therefore,the support-surrounding rock "action relationship is divided into "R-S-F" action,"gangue-support and support" action,"gangue-support-coal wall"along the vertical rock formation direction,inclined direction,and strike direction.Compared with the true oblique working face,the stability control of the latter two systems has higher requirements for the control of rock formation in pitching oblique working face.The above research conclusions can provide theoretical support for the in-depth study of the interaction mechanism between the support and surrounding rock and the mechanism of surrounding rock instability and disaster in longwall and pitching oblique mining area of steeply dipping seam.Engineering practice shows that under the guidance of the research conclusions of the thesis,measures such as regional roof control of the working face,improved support strength,and strict control of Pitching oblique angle are adopted to effectively solve the series of difficulties in rock control of the pseudo-pitched working face,which guarantees The working face is safe and has achieved remarkable economic and social benefits.