Abstract
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.
Highlights
The stability of coal-rock composite structures is of great significance to coal mine safety production
Lithology and coal-rock height ratio play an important 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
Summary
[Fig. here] The average elastic energy and total elastic energy of composite structure with different coal-rock height ratios during cyclic loading are calculated. It can be seen that the higher the coal-rock height ratio is, the greater the average elastic energy per cycle of the coal-rock composite structure is, but the lower the total elastic energy is. Fig. shows the relationship between the dissipated energy of the coal-rock composite structure with different coalrock height ratios and the cycles. According to the dissipated energy method, the damage variables of the coal-rock composite structure under the cyclic loading are calculated, the calculation results are shown in Fig.. [Fig. here] Fig. shows the relationship between cumulative damage variables and cycles of composite structures with different coal-rock height ratios. When the coal-rock height ratio is 1:3, 1:2, 1:1, 2:1, 3:1, the average cumulative damage variable growth per cycle is 0.0522, 0.0615, 0.0753, 0.0968, and 0.1188, respectively
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