An Experimental Study Into the Effects of Cumulative Energy Damage on the Mechanical Properties of Coal

The accumulated damage of the surrounding rocks induced by existing coal mining activities (such as excavation and extraction) is initial mechanical background rock for further operations. An energy-based Cumulative Initial Damage (CID) variable was proposed to account such damage. With MTS815 electro-hydraulic servo-controlled system, samples with different CID value were prepared cyclic pre-loading unloading process, a novel experimental framework presented investigate effect on properties samples. deformation characteristics, peak strength, strain, dilatancy brittle-ductile transformation behavior, microscopic structure investigated in detail. triaxial compression tests showed that increased value, compaction part shorter strain softening stage became longer. When from 0 0.521, deviation stress decreased 31.4 37.7%, respectively main characteristic fracture morphology changed cleavage steps dimpling.