Sensitivity of the damage response and fracture path to material heterogeneity present in a sandstone specimen containing a pre-existing 3-D surface flaw under uniaxial loading

The heterogeneity of natural rock affects its fracture behaviour resulting in a variation of rock strength. To investigate the sensitivity of damage response and failure strength across rock samples numerical simulations are performed with random realizations of the Young's modulus. As a test case, we consider a rock specimen with a pre-existing 3-D surface flaw under uniaxial compression. To test the sensitivity of the damage response due to material heterogeneity for specific geometrical configurations Young's modulus is varied at the mesoscale using different randomized distributions while keeping the bulk material properties constant at the macroscale. The study shows that in general, the standard deviation is independent from geometrical parameters of initial fracture, but deviation increases when the orientations of the initial flaw and of the external loading are more aligned. In all cases, the exact fracture path displays some variability and in particular for cases with a high degree of heterogeneity some caution must be used when interpreting fracture patterns from a limited number of samples. As a consequence deviation of damage patterns generated from numerical models when compared to experimental results can confidently be attributed to the particular realizations of the heterogeneity present in the real and numerical sample.