Effect of hydrate crystal type on mechanical properties of gas hydrate-bearing coal

The mechanical properties of coal body containing gas hydrates is the basis for preventing coal and gas outburst utilizing hydration mechanism.The gas hydrate-bearing coal with different crystal types were performed,using self-developed equipment integrating gas hydrate formation and triaxial compression.Each stress-strain relations,strength and other characteristics were obtained by the triaxial compression tests on coal containing gas and containing different types of gas hydrate crystals.By fitting based on the Mohr-Kulun strength criterion,the cohesion,the angle of internal friction of coal bearing hydrate and coal bearing gas were got.The results show that,hydrate can enhance the stiffness and cohesion of coal body,and the coal containing II type gas hydrate is stronger to resistance destruction ability,and the types of hydrate in coal body have different affect for the mechanical properties of coal body.