Coupling Mechanism of Dissipated Energy-Electromagnetic Radiation Energy during Deformation and Fracture of Loaded Composite Coal and Rock

Abstract

The nature of composite coal and rock fracture under load is the process of energy conversion inside it, and to explore the coupling mechanism of dissipated energy (DE) and electromagnetic radiation energy (ERE) during the deformation and fracture process of loaded composite coal and rock, based on theoretical mechanics, electromagnetics, and other subject theories, the stress-charge induction signal coupling relationship is deduced and established. On this basis, a coupled mathematical model of dissipated energy-electromagnetic radiation energy (DE-ERE) is established, and uniaxial loading experiments under different loading rates are carried out. The research results show that the energy of the composite coal and rock increases, and the internal free charge transitions from the high-concentration area to the low-concentration area, accumulating charges on the fractured surface, forming a regional electric field, and generating electromagnetic radiation. The change of the charge-induced signal on the surface of the loaded composite coal and rock is phased and has a corresponding relationship with each mechanical phase. Its peak appears earlier than the stress peak. There is a linear relationship between the charge induction signal and stress, and they have a strong correlation, which is consistent with the established mathematical model. The energy conversion characteristics of the composite coal and rock under load have stage characteristics. The elastoplastic period is mostly converted to dissipative energy release, and the increase of plastic deformation leads to rupture. ERE is one of the components of DE. In the early stage of elastoplasticity, the dissipated energy mainly exists in the form of electromagnetic radiation energy, and the change trends of the two are the same. After the peak value, it drops rapidly, and the DE is mainly composed of other destructive energy that causes deformation. The changes in ERE can be used to determine the DE and stress state, providing a new method for preventing coal and rock dynamic disasters.