Analysis the characteristic of energy and damage of coal-rock composite structure under cycle loading

The stability of coal-rock composite structures is of great significance to coal mine safety production. The uniaxial cyclic loading tests of the coal-rock composite structures with different coal-rock height ratios were carried out to study the stability and deformation failure characteristics of the coal-rock composite structure. The coal-rock height ratio play a vital role in the energy dissipation of coal-rock composite structures. The higher the coal-rock height ratio, the greater the average elastic energy and dissipated energy produced per cycle of coal-rock composite structures, the smaller the total elastic energy and dissipated energy produced in the process of cyclic loading. A more sensitive joint calculation method for calculating damage variables was proposed based on the difference of damage variables calculated by dissipated energy method and acoustic emission method. The joint damage variable calculation method can more accurately and sensitively reflect the damage of coal-rock composite structure under cyclic loading. The macroscopic crack first appears in the coal specimen in the coal-rock composite structure. The degree of broken coal specimens in the composite structure is inversely proportional to the coal-rock height ratio. The strength and deformation characteristics of the coal-rock composite structure are mainly affected by the coal sample in the composite structure.