Damage Characteristics of Outburst Coal Sample Containing Gas Under Different Loading Rates

Abstract

To study the influence of loading rate on the damage characteristics of outburst coal containing gas, the uniaxial compression experiments were carried out for coal body with five loading rates, including 0.001 mm/s, 0.005 mm/s, 0.01 mm/s, 0.05 mm/s and 0.1 mm/s. The damage characteristics of coal body were analyzed from two aspects: cumulative acoustic emission damage and fractal characteristics of coal surface cracks. The result show that with the increase of loading rate, the uniaxial compressive strength of outburst coal with gas decreases gradually and presents a logarithmic function relationship. The cumulative acoustic emission damage curve shows that the maximum damage value of coal body first increases and then decreases with the increase of loading rate, and the loading rate of 0.05 mm/s is the inflection point of the curve. Fractal analysis on the surface crack morphology of coal body was carried out after being damaged by loading and the fractal dimension increases first and then decreases with the increase of loading rate, and the inflection point also appears at 0.05 mm/s. The conclusions obtained by the two methods are consistent.

Keywords

• gas containing coal
• loading rate
• cumulative damage
• surface crack morphology
• fractal dimension