Bedding Effect on the Deformation: Damage Differentiation of Coal Mass

Abstract

In order to reveal the mechanical properties and damage mechanism of coal with parallel multibedding under stress disturbance, the raw coal samples with parallel multibedding were selected. The uniaxial compression and acoustic emission damage measurement were carried out using the coal-rock mechanics damage coupling test system, revealing the bedding effect of coal deformation-damage failure differentiation under different loading methods; based on the test results, a coupling characterization model of mechanical damage of coal and rock with parallel multibedding is established. The results show that (a) the acoustic emission of raw coal samples under different loading modes has obvious differentiation characteristics of bedding effect. When the vertical bedding is loaded, the peak stress of raw coal samples is relatively high and the acoustic emission activity period is relatively long; when the parallel bedding is loaded, the active degree of acoustic emission is relatively strong, and there is an obvious mutation period after the acoustic emission enters the acute period. (b) Under different loading modes, the difference in the influence of bedding on the fracture evolution of raw coal specimens is mainly concentrated before the stress turning point. In stage I, the acoustic emission b value of raw coal specimens decreases first, then becomes stable under vertical bedding loading, and decreases under parallel bedding loading; in stages II and III, the acoustic emission b value of raw coal samples showed the same change trend under different loading modes. (c) Combined with the basic principle of continuous damage mechanics and based on the difference of bedding effect, the relationship between cumulative acoustic emission ringing count and stress and damage variable of the raw coal samples was established. The rationality and effectiveness of the model are verified by experiments.