Static And Dynimic Load Characteristics And Rockburst Rules Of Working Face Gob-side Roadway In Gently Inclined Coal Seam

Rockburst is a destructive coal mine dynamic disaster.According to investigation,about 95% of the rockburst accidents happen in the roadway,of which about 65% rock burst occurs in gob-side roadway.In gently inclined coal seam,the problem of rock burst is particularly obvious in gob-side roadway of working face.Therefore,it is of great significance to study static and dynamic load as well as rockburst rules of surrounding rock in gob-side roadway.This thesis has been studied by means of engineering research,case statistics,mechanical analysis,numerical simulation and engineering practice.The main conclusions are as follows:The investigation and analysis of rockburst manifestation characteristics in gob-side roadway shows that: the rock burst proportion of mining face is high,the rockburst times of outer side(coal pillar side)are higher than inner side(solid coal side),rockburst tendency of the roof and coal seam for strong-strong structure working face has highest proportion rockburst,and frequency of rockburst in 10~30m pillar is high.Coal seam dip angle,coal pillar and goaf width and overburden structure are main controlling factors of roadway static and dynamic load in gently inclined coal seam.The difference between the static load stress characteristics of the surrounding rock of the side roadway in the gently inclined coal seam and the horizontal coal seam is analyzed theoretically.The study shows that rockburst risk of the lower side is higher than the upper side,the roof peak stress position of the roof is shifted to the goaf,and the peak stress position of the u floor is shifted to the deep coal seam in the lower side of goaf.After excavating the roadway in gently inclined coal seam,the top part of the coal solid coal side is compressed and the bottom is pulled,the coal pillar side is the opposite.The "8" type elastic core is formed in the pillar,which becomes the main static load source of gob-side roadway rockburst.The theory and the field are combined to study the evolution rules and dynamic characteristics of the overlying rock structure in gently inclined coal seam.The study shows that the instability conditions of two structures of "cantilever beam" and "masonry beam" in gently inclined coal seam are more harsh than that of horizontal coal seams.The stability of coal pillar is worse when the overlying strata in the "F" type-"T" type-"V" structure evolvement.When the mine earth released from the gravel old roof and the third inferior key strataquake broken spread to the gob-side roadway of Yutian coal mine,the higher energy is transported,which is the dynamic load source of gob-side roadway rockburst.The influence of the width of coal pillar,the width of the goaf and the dip angle of the coal seam on the static load stress field of the roadside roadway in the gently inclined coal seam is simulated study,and the rockburst process of gob-side roadway under the action of the far field seisemic and the strong mine earthquake is reproduced.The results show that the vertical stress concentration degree of 15 m pillar is the highest,and the difference of peak position between roof and floor of 20~25m coal pillar is the most obvious.With the increase of the coal seam dip angle,the peak position of roof is shifted to the goaf,the peak value of floor is shifted to gob-side rib.The vertical stress of ribs decreased,the horizontal stress increased,and the variation amplitude of the toward-wave side was larger than the back-wave side.After the action of far field seismic,the vertical distance of the "8" type load in the middle of pillar from gob-side rib decreased.In the process of strong mine earthquake,the horizontal stress of toward-wave side rib increases rapidly.After the strong mine earthquake,toward-wave side rib is mainly tensile failure,and the roof subsidence is subsidiary,the top of back-wave side is mainly shear failure,and the bottom is tensile failure.According to the mechanical model,the combined method of pre-evaluation,monitoring,prevention measure,reduce static load and control dynamic load is adopted to control pressure,which can effectively predict and control rock burst of W1102 air-return roadway in Yutian coal mine.