Evaluating rock physics–fracture mechanics relationship by quantifying fracture process zone

In this thesis, the length of Fracture Process Zone (FPZ) of four rock types including a red sandstone, a white coarse-grained marble, a fine-grained granite and a coarse-grained granite are quantified. The length of FPZ of a moving crack or the cohesive length 𝓁𝑐 is quantified by post mortem roughness analysis of the fracture surfaces of the studied rocks using statistical physics and multifractal framework. Then, this critical length, 𝓁𝑐, is imported into non-linear fracture mechanics models to connect rock physics and fracture mechanics, which leads to determination of the cohesive stress 𝜎c or intrinsic tensile strength of rock materials.