Three-dimensional numerical simulation of sandstone failure characteristics based on mineral particles and pore structure
摘要
The meso-structure of the internal mineral particles and primary defects in the pores and cracks of the rock can affect its failure characteristics. In order to study the relationship between the internal meso-structure of the rock and the failure characteristics, uniaxial compression real-time CT scanning tests of φ15 × 30 mm sandstone were carried out, and several numerical models were constructed by RFPA3D-CT to analyze the effects of porosity, pore diameter, mineral particle content and particle size on the failure characteristics of sandstone. The results show that: (1) the initial porosity inside the sandstone specimen is 10.2%, and the porosity shows a trend of slow decrease to slow increase and finally drastic increase during the loading process. (2) When the porosity and mineral particle content are small, The failure is characterized by shear failure with oblique ' 1'distribution. When the porosity and mineral particle content increases, the failure location is shifted to the lower part, showing the up and down undulating tensile-shear composite failure characteristics. The stress concentration is more likely to form around the pores, and the micro-failure regions are extended along the more porous locations, while the mineral particles hinder the extension of the fissures. (3) Sandstone porosity, pore size and particle size showed strong negative correlation with peak strength, while sandstone mineral particle content showed strong positive correlation with peak strength. The size of the influence on the peak strength of sandstone is: porosity > pore diameter > mineral particle content > particle size, and the influence of pore structure on the peak strength of sandstone is greater than that of mineral particles.