Research on mechanical characteristics and infrared radiation response law of loading failure process of type I pre-cracked coal sample under different loading rates

Abstract

Given the problem that coal and rock dynamic disasters such as pressure bumping often occur in mines with complex coal body defects such as rich fractures and joints, this paper carried out uniaxial compression tests of type I (single crack with the crack angle of 45°) pre-cracked coal samples under different loading rates and analyzed the influence of loading rate on the mechanical properties, failure modes, and variation laws of acoustic emission (AE) and infrared radiation (IR) of type I pre-cracked coal samples under loading. The results show that with the increase of loading rate, the failure rate of type I pre-cracked coal sample increases, and the collapsing strength also shows a downward trend. The failure types of type I pre-cracked coal samples are mainly wing failure along the pre-crack tip or the coexistence of wing failure and anti-foil failure. The fluctuation degree of infrared radiation temperature (IRT) during coal failure decreases with the increase of loading rate; under different loading rates, there was a positive correlation between the maximum infrared radiation temperature (MIRT) and AE counts of coal samples with type I prefabricated cracks. The density of AE counts is related to the loading rate and the development and damage of coal fractures. The research results provide a theoretical basis for monitoring and early warning of coal and rock dynamic disasters in mines with complex coal defects such as cracks and joints by the infrared method.