Physical and Mechanical Properties Evolution of Coal Subjected to Salty Solution and a Damage Constitutive Model under Uniaxial Compression

Min Wang, Qifeng Guo, Yakun Tian and Bing Dai
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Min Wang: School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
Qifeng Guo: School of Civil and Resource Engineering, University of Science and Technology Beijing, Beijing 100083, China
Yakun Tian: School of Resource Environment and Safety Engineering, University of South China, Hengyang 421001, China
Bing Dai: School of Resource Environment and Safety Engineering, University of South China, Hengyang 421001, China

Mathematics, 2021, vol. 9, issue 24, 1-19

Abstract: Many underground reservoirs for storing water have been constructed in China’s western coal mines to protect water resources. Coal pillars which work as dams are subjected to a long-term soaking environment of concentrated salty water. Deterioration of the coal dam under the attack of the salty solution poses challenges for the long-term stability and serviceability of underground reservoirs. The evolution of the physical and mechanical properties of coal subjected to salty solutions are investigated in this paper. Coal from a western China mine is made to standard cylinder samples. The salty solution is prepared according to chemical tests of water in the mine. The coal samples soaked in the salty solution for different periods are tested by scanning electron microscope, nuclear magnetic resonance, and ultrasonic detector techniques. Further, uniaxial compression tests are carried out on the coal specimens. The evolutions of porosity, mass, microstructures of coal, solution pH values, and stress–strain curves are obtained for different soaking times. Moreover, a damage constitutive model for the coal samples is developed by introducing a chemical-stress coupling damage variable. The result shows that the corrosion effect of salty solution on coal samples becomes stronger with increasing immersion time. The degree of deterioration of the longitudinal wave velocity ( v p ) is positively correlated with the immersion time. With the increase in soaking times, the porosity of coal gradually increases. The relative mass firstly displays an increasing trend and then decreases with time. The peak strength and elastic modulus of coal decreases exponentially with soaking times. The developed damage constitutive model can well describe the stress–strain behavior of coal subjected to salty solution under the uniaxial compression.

Keywords: coal; deterioration characteristics; chemical-stress coupling factor; damage constitutive model (search for similar items in EconPapers)
JEL-codes: C (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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