Physical uniaxial compressive tests were conducted on high porosity vesicular basalt specimens in the lab. The main experimental mechanical parameters (i.e., peak strength and elastic constants) were used to calibrate numerical models in the 2-D PFC. Two different contact bond models were applied during the numerical analysis, namely, the linear parallel bond model and the flat-joint model. Also, different seed values were tested to generate distinct two-dimensional pore structures. Further, two grain size distributions were tested: a coarser sized one and a finer sized one. The effects of these bond models and parameters on the fracturing response of the rock were studied. Two simple mathematical criteria were also proposed for the accurate determination of the cracking thresholds from the numerically derived crack count curve. The numerical results were compared with the laboratory derived ones, and the differences were acceptable. Ultimately, via the coupled experimental and numerical approach, we were able to physically interpret the micro- and macrocracking response of the rocks.