Abstract:
The uniaxial compressive strength, elastic modulus and tensile strength of coal seam were measured by the CMT5305 electronic universal testing machine, the static indentation hardness was also measured by different displacement rate with packaged cylindrical indenter. The results showed that the value of the static indentation hardness of the coal was independent of the displacement rate, but the local broken manners were time-dependent, the greater the displacement rate was, the shorter the broken time was, and there were two destructive modes of vortex and splitting when the coal was pressed by the indenter; the result of the drillability classification of the coal by the indentation hardness method did not agree with that by Polodyakonov hardness method, the former was the forth grade of medium soft and the latter wasⅤa toⅥ grade of medium hard to relatively soft, the classification was also affected by the indoor experimental conditions; the prediction model between the indentation hardness and the compressive strength, elastic modulus and tensile strength can be established by the logarithmic function, and the model can provide theoretical guidance for the accurate understanding of the mechanical properties of coal.