Numerical Simulation of Physical Properties of Coal Sample Under Step Loading Conditions

Loading experiments were conducted to study the physical properties of coal samples under step loading conditions, and the physical properties of coal samples under different conditions were numerically simulated by FLAC3D software. The numerical simulation results under step loading showed that FLAC3D software can effectively simulate the strain value and overall change trend of coal samples, obtaining good simulation results. The accuracy and applicability of the numerical simulation model were verified. Based on this, the physical properties of coal samples under different conditions were further investigated. The simulation showed that the transverse strain at the top of the coal sample is more obvious than that at the bottom, which shows the process of stress transfer from top to bottom. The effect of the bulk modulus on the axial strain of the coal sample was small, and the axial strain decreased with the increase in the bulk modulus under the same conditions. The shape of the coal sample was found to have a great influence on the axial strain, and the axial strain of a cylindrical coal sample was much larger than that of a rectangular coal sample under the same conditions. An increase in the height of the coal sample resulted not only in an increase in the axial strain value, but also a gradual increase in the degree of strain. This has significant implications for future use in guiding the analysis of the physical properties of coal.