The cataclysmic characteristics for bituminous-coal oxidation under uniaxial stress based on catastrophe theory

Abstract

Coal occupies a large proportion in the application of fossil energy and dominates the lifeblood of China's national economy. Coal spontaneous combustion (CSC), as one of the disasters in goaf of coal mines underground, could result in the coal fires, gas explosions or dust explosions, which threatens the workers and apparatus underground. Aiming to accurately explore the CSC characteristics of residual coal in goaf underground to prewarn the stages of CSC, a novel uniaxial compression equipped with a temperature-programmed(UCTP) device was built to carry out the fluid-solid-thermal-mechanical coupling tests. Based on the catastrophe theory, a new method for predicting the development stage of CSC is put forward. The following results were obtained: (i) The gas concentration, oxygen consumption rate and porosity are overall decreased as the stress increases. (ii) The kinetic parameters of coal oxidation loaded at 6.3 MPa recorded the highest results. (iii) The catastrophic temperature TCO is the optimal method to predict the development stage of CSC. (iv) Catastrophic temperature could characterize the CSC tendency, which appears under uniaxial stresses as follows: 2 MPa < 8 MPa <4 MPa < 0 MPa <6 MPa. The findings could provide the important theoretical guidance and technical support for the prediction of the process of CSC.