Energy evolution and constitutive model of flawed coal failure based on acoustic emission and electric potential characterisation

Abstract

The stability of underground construction is seriously compromised by the joints, faults, and other defects existing in the natural coal mass. Understanding the energy evolution and damage characteristics of its fracture process is of great significance for the prediction and early warning of deep coal-rock dynamic disasters. In this paper, the uniaxial compression experiments are conducted on defective coals with simultaneous testing of acoustic emission (AE) and electric potential (EP) from specimen rupture. The energy evolution characteristics of the defective coals’ damage destruction process were investigated. The evolution laws of AE and EP were analyzed. The fracture characteristics and damage evolution characteristics of the specimens were revealed. The damage constitutive model based on the coupled AE and EP characterization was established. The findings indicate that: (1) prefabricated flaws have a significant weakening effect on the specimens. As the flaw inclination increases, the lesser the weakening effect on the energy storage capacity of the specimens. Both EP and AE responses effectively reflect the energy dissipation of the specimen. (2) Both the β_te of EP and the β_ta of AE exhibit significant precursor anomalies before severe damage occurs to the specimen. Employing a monitoring method combined with β_te and β_ta enables precise early warnings of coal instability processes. (3) According to the Lemaitre strain equivalence principle, a damage constitutive model of defective coal based on AE and EP coupling characterization is established. The model can effectively calculate the stress state of the specimen. These research findings offer crucial theoretical guidance for enhancing the stability of underground engineering and ensuring safe coal mine operations.