Abstract: Based on the condition of the fully-mechanized working face in the mine, the rock deformations that changes with workface advance under different depth of coal seam floor are measured through the strain method. The results show that the violent influent range of mine pressure on the coal seam floor was “advance” appearance and “lag” continuity. The distance of the “advance” appearance was 37 m and the “lag” continuity was 32 m, and the violent influent range of mine pressure on the coal seam floor corresponding is decreasing from the shallow to deep. Combining with the analysis of the drilling sighting glass on mining floor, it is confirmed that the damage depth of working face floor mining-induced was 12 m. Based on the field in-situ measurement, using FLAC3D numerical simulation as a method of making a comprehensive comparative study about the failure characteristics of the coal floor, it reveals the three-dimensional failure characteristics of the floor in the mining process better. Using the field strain measurement, in-situ drilling sighting glass observations and numerical simulations as a mutual authentication method of making a comprehensive comparative study of the failure characteristics of the coal floor, it makes up the disadvantage of single research means in the past.

Key words: strain method, mine pressure, drilling sighting glass imaging, failure depth, failure characteristics