Accurately simulating the compressive and tensile mechanical behavior of rock is one of the challenges faced by numerical simulation. In this paper, the rock's triaxial compression experiment and the Brazilian disk simulation were simulated, and the propagation process of the rock crack was simulated in Brazilian disk test in the finite element method. According to the experimental data, the KCC model was completely modified and the triaxial compression experiment was carried out with the modified model. The modified model was applied to the Brazilian disk test simulation, and the crack propagation in Brazilian disk test was simulated by inducing the erosion algorithm, which verifies the applicability of the erosion algorithm in the finite element method of material continuity loss.
Sandstone is ubiquitous in underground engineering, so studying the behavior of sandstone in underground engineering is of great significance to its application in mining and civil engineering[1]. Sandstone is a brittle material, and its characteristic is that its tensile strength is much lower than its compressive strength. Therefore, both compressive strength and tensile strength need to be considered when studying the mechanical properties of sandstone.
It is difficult to perform the direct tensile experiment of brittle materials. Because the Brazilian disk test is economy and simplicity, it has become a common method for measuring the indirect strength of brittle materials. A large number of numerical simulations have been applied to the study of Brazilian disk test, and many of these studies have focused on the location and propagation process of cracks in the Brazilian disk test. Many researchers use discrete element method (DEM) [2]or the finite element method (FEM) coupled with the DEM [3] to study the crack propagation in the model. These studies generally focus on tension behavior of rock, without considering the compression of the rock at the same model. To be able to consider the compression and tension of the rock at the same time, it is necessary to select an appropriate constitutive model. Mohr-Coulomb[4] and Hoek-Brown[5] is commonly used in the constitutive model of brittle materials. Although these constitutive models have good performance when applied to the compression of materials, they usually overestimate tensile strength of the brittle material. The advanced material models, namely Karagozian and Case concrete (KCC) models, is implemented in conjunction with the finite element code LS-DYNA. The KCC model is developed by Malvar et al[6-8]. After multiple versions upgrades, it can effectively simulate the key behaviors of concrete post-peak softening, shear dilation and strain rate effect. It can also automatically generate a set of parameters based on uniaxial compression strength, or be calibrated according to the laboratory data.
