Abstract: Based on the condition of fully-mechanized working face in one mine, by using the field strain measurement and numerical simulation as a mutual authentication method, a comprehensive comparative study of the thick seam floor’s failure depth under the mining was carried out in this paper. Field measurement studies show that the failure depth of the coal seam floor is about 13~16m. The influence of the mining pressure on the floor presents the feature of“advance”appearance and “lag” continuity, while the advance and lag distances are manifested as the feature of decreaing gradually from shallow to deep. The numerical simulations indicate that floor failure zone affected by mining is between 0~16 m under the coal seam, which means the greatest failure depth of floor is 16 m, the zone of 16~36 m under the coal seam is slightly affected by coal mining, and the mining pressure tends to in situ pressure along with the increase of depth. By the comprehensive analysis, the failure depth of coal seam floor is 16 m, and the research results can make reference for safety mining of coal resources and mine water disaster control under the similar conditions.

Key words: strain test, numerical simulation, damage depth, mining pressure