Quantitative characterization of constitutive model of mudstone under uniaxial loading after immersion in acid solution by infrared radiation

Abstract

The fracturing of coal and rock is a fundamental cause of mine disasters, such as coal pillar instability,water inrush and rock failure. To prevent the occurrences of these failures, it is important to accurately monitor and detect stress fractures in coal and rock. Furthermore, it is also essential to develop stress–strain constitutive models for an accurate and effective monitoring, early warning of coal and rock stress fracture process. The development of stress–strain constitutive model is the important basis for effectively realizing water conservation mining and rock strata control in mines. In this research, mudstone samples were collected from coal mining sites and mining faces. The mudstone samples were subjected to chemical corrosion using both strong acid and neutral solutions, followed by conducting infrared radiation observation experiments during uniaxial loading. The research findings revealed that 1) strong acid can promote the infrared radiation of the mudstone surface. The Average Infrared Radiation Temperature (AIRT) value of the mudstone corroded by the solution with pH 1.3 during uniaxial loading fracture is changed and noted 6.71 times to the solution with pH 7.3. 2) strong acid has an significant impact on the failure of mudstone samples. The mudstone corroded by the solution with pH 1.3 is mainly damaged by tension and shear composite cracks, while the mudstone corroded by the solution with pH 7.3 is primarily damaged by tension cracks. 3) A nearly linear relationship between the strain of mudstone during uniaxial loading and AIRT was found. This relationship defines a new index of deformation infrared radiation coefficient, allowing for the quantitative characterization between strain and infrared radiation. 4) A one-dimensional statistical damage constitutive model based on AIRT is established using Weibull distribution, while considering the stress–strain compaction stage. This model effectively predicts the stress of mudstone during uniaxial loading. The research results lay a theoretical and practical foundation for the monitoring and evaluation of rock stability in underground engineering such as coal mines, subways and tunnels.