Investigation on displacement field characteristics of tunnel's surrounding rock and coal seam at FMTC face

The change rules of displacement field characteristics of coal seam and tun-nel’s surrounding rock were obtained by means of numerical simulation-FLAC3D and siteobservation,and according to engineering geology and exploitation technology of 1151(3)fully mechanized top coal caving(FMTC)face in Xieqiao colliery.The research’s resultsshow that the top coal displacement on the top of FMTC face is apparently larger thanthose of the middle and the bottom,the top coal begins to move in the front of the face’swall,and the sub-level top coal-rock moves ahead of the low-level top coal-rock,the verti-cal displacement of top coal-rock increases gradually as the decreasing of distance to face.Top coal and overlying strata in vertical direction are always in compressed state in thefront of face,then the top coal begins to separate from the overlying strata at the upside offace.The support loading at face is mainly the deformation pressure due to top coal andmain roof’s movement,and it is not suitable for the FMTC face with traditional support de-sign.Surrounding rock movement of the face is of near-field effect,the surrounding rockdeformation is acute greatly near to the face,the ideas of supporting design for the tailen-try and headentry should be changed from loading control to deformation control.