Numerical Simulation of Mechanical Properties of Deep Gray Sandstone with Holes and Radial Cracks

Abstract

In order to study the effects of prefabricated pore-fracture on the mechanical properties, crack extension and energy evolution of rocks under uniaxial compression, the effects of rock samples containing pore-fracture deep grey sandstone on the mechanical properties, crack extension and energy evolution of rocks were analysed in detail through the indoor experimental inverse performance of the fine-scale mechanical parameters of the PFC3D model. The results show that the mechanical parameters of deep grey sandstone samples with pore fissures are significantly lower than those of intact samples, and the decrease is closely related to the diameter of the pore as well as the length and width of the fissure, with the increase of the diameter of the pore, the peak strength and the peak strain of deep grey sandstone with single pore are in the trend of attenuation, and the mechanical parameters of deep grey sandstone samples with pore fissures of different lengths and widths are in the trend of attenuation with the increase of fissure widths and lengths of different layers. The mechanical parameters of deep grey sandstone samples with different lengths and widths of fissures show a trend of attenuation with the increase of fissure width and length; based on the analysis of microscopic crack characteristics during loading of deep grey sandstone with pore fissures, it is concluded that the cracks produced by deep grey sandstone samples with pore fissures are mainly distributed at the two ends of the samples, and the middle area has fewer cracks and the number of the cracks produced shows a trend of attenuation with the increase in the diameter of the pore as well as the length and width of the fissure; Based on the energy evolution mechanism, it is concluded that as the pore size of the rock sample increases, the strain node at which the dissipated energy begins to appear becomes progressively earlier, the energy storage capacity of the rock appears to be drastically reduced, and the internal damage becomes more and more severe.