Study on the effect of moisture on mechanical properties and impact energy index of coal

Abstract

Coal destruction is an energy-driven destabilization phenomenon. In order to investigate the effect of moisture on energy accumulation and dissipation during coal destruction, uniaxial compression tests on coal samples with different water content states were carried out, and the mechanical properties and impact energy index of coal were analyzed based on this. The results showed that the uniaxial compressive strength and elastic modulus of coal samples decreased significantly with the increase of water content; the proportion of the initial compression-density stage, plastic deformation damage stage and post-peak damage stage in the full stress-strain process of coal samples increased, and the proportion of linear elastic stage decreased; the accumulation deformation energy before the peak of coal samples decreased, the loss deformation energy after the peak increased, and the impact energy index decreased. The increase of water content changed the coal sample from splitting damage to shear damage, and the particle size of crumbling pieces became larger, the number of pieces decreased, and the damage sound weakened during the damage. The uniaxial compressive strength, impact energy index and impact energy velocity index of coal samples in water-saturated condition decreased by 35.32%, 86.07% and 99.63%, respectively, compared with those in dry condition, and the coal seam water injection process can effectively reduce the impact propensity of coal seam.

Keywords

• moisture
• impact tendency
• uniaxial compressive strength
• impact energy index
• damage form