Abstract: Due to the heterogeneity, opacity and porosity of rock, it is difficult to truly represent three-dimensional internal meso-structure of rock through physical experiments and numerical simulations. In this study, a 3D non-uniform numerical method was proposed to simulate the porous rock failure based on the parallel finite element method. The CT technology was used to scan the rock specimens and obtain the picture layers. The edge detection algorithm, filtering algorithm and 3D matrix mapping method were applied to process the scanned pictures and reconstruct the Brazilian disk finite element model of the rock. Thus, 3D numerical Brazilian disk models were constructed, and the influence of the porosity and pore distribution were analyzed numerically. The results indicated that the pore distribution and porosity had significant effects on the crack propagation and tensile strength. The number of the secondary cracks decreased when the porosity was smaller and pores were sparse, while the number of the secondary cracks increased when the porosity increased. The different porosities of numerical specimens were calculated by using the digital image processing method, and the relationship between the tensile strength and porosity followed an exponential function. The porosity of the specimen was obtained by the digital image processing technology, and the law of porosity and tensile strength was exponentially distributed. The median filtering algorithm improved the accuracy of the digital model in the image processing, and the 3D numerical simulation model reflected the 3D meso-structure of rock-like porous materials, which provided an effective method for studying the mechanical behavior of rock.

Key words: CT, digital image processing, basalt, numerical simulation, pore