In view of the serious situation of the gateway floor heave on island face of gently inclined coal seam

the mineral composition and microstructure of the roof and floor slabs were tested on the background of the 107 th working face in Pangpangta Mine.The deformation mechanism of gateway floor was studied by physical simulation.The results show that:1)The lithology of the headentry floor at the 107 th working face is mainly kaolinite

which has less expansive composition.The rock mass has fewer internal voids

dense structure and high strength;2)The headentry floor heave of the 107 th working face

which occurs during the excavation and belongs to extrusion and fluidity type

is the overall bending of the shallow rock strata.At the stage when the advance bearing pressure is used for mining

the upper hard rock layer of the floor exceeds its flexural strength and breaks.Thus

the restraint on the lower soft floor is removed and deformation increases sharply.Cracks appear at the corner and severe deformation zone

limited deforma tion zone and deformation transition zone appear sequentially in the floor;3)the mechanism of the headentry floor heave at 107 working face is as follows:extrusion flow of the hard floor under high stress is the main reason for the floor heave

while the existence of a small amount of expansive rock in the floor of the gently inclined coal seam has little effect on the formation of floor heave.Aiming at the specificity

the excavation pressure relief tank was adopted to release the pressure and mitigate the floor heave.On-site measurement shows that the proposed measures can effectively reduce the degree of headentry floor heave.