Numerical Analysis of Tensile Crack Initiation and Propagation in Granites

Fracture analyses based on finite cover method (FCM) are conducted to investigate a fracture mechanism of granites. The analysis by the FCM, which is a cover-based generalized finite element method, has been extended for analyses of fracture process involving cracking within and/or between mineral grains in inhomogeneous rocks. A fracture process of numerical specimens which are prepared using X-ray CT image of African granites is studied. The analysis of material parameters, such as Young's modulus and tensile strength of minerals contained in the granites, is conducted to examine its influence on the fracture process and strength. Additionally, distribution of the mineral grains provides anisotropy for mechanical properties of granites. Comparison between numerical and experimental results presents that the important factors causing the anisotropy of macroscopic strength are the Young's modulus as well as the tensile strength of minerals distributed in the granites.