Abstract: The integrated research methods are adopted to analyze the coal wall stability for the issue of the hard gangue effect in full height mining face by the means of the theoretical analysis, indoor experiments and field measurement. The coal wall spalling model and the stable conditions are proposed, and the rib spalling mechanism in stratum of gangue is studied. The results show that: the compressive strength of the coal block in gangue or superimposed coal sample can be increased compared with the pure coal block; the axial deformation of the pure coal block or superimposed coal sample is larger than the coal block in gangue; the overall stability of the coal wall can be effectively improved in the coal seam with a stratum of gangue; the coal height has greater impact on the coal wall stability——the higher of the coal face, the easier for the coal wall instability under the same external load conditions; the coal face stability condition is given considering the differences of the continuous degree between the field coal body and indoor coal sample. The field measurement indicates that the rib spalling is more stable of the No.28202 coal face in context of the actual production in Dong-qu coal mine, and the rib spalling occurs mainly in the upper position of the No.8 coal seam. The coal face production conditions have been improved base on the low degree of rib spalling.

Key words: rib spalling mechanism, coal seam with a stratum of gangue, larger height coal face, column stability, critical instability