Influence of fracture dip angle on coal brittleness and energy evolution

Abstract

By prefabricating raw coal samples with cracks of different dip angles, uniaxial mechanical tests are carried out. Based on these, the energy evolution characteristics of the bearing failure process are analyzed. It is found that the uniaxial compressive limit of the coal decreases gradually with the decrease of the crack inclination, and the modulus of elasticity decreases linearly. And the brittleness of coal containing pre-fabricated crack gradually decreases as the angle of inclination of the fracture decreases, with the reduction of 36.41% at an angle of inclination of 0°. The “N” curve of the dissipation energy ratio Rd of the coal can reflect the precursor information of coal instability. The smaller the crack inclination of the prefabricated crack of coal, the earlier the Rd fluctuates and reaches the minimum value, the more drastic the Rd changes.

Keywords

• coal
• pre-fabricated crack
• crack inclination
• proportion of dissipated energy
• coal brittleness