Numerical study of rock fracturing during blasting excavation

During the process of excavations, blasting can induce damage inside surrounding rock, which may change the mechanical properties of rock mass and influence the stability of structure. Considering the effects of material properties and loading conditions, two numerical models, a rock blasting excavation model with two excavation steps and a planar rock model with four boreholes, are developed through the use of AUTODYN code. By using these numerical models, rock fracturing process is simulated in order to investigate some of the key aspects of the dynamic fracturing in surrounding rock. It is shown that in the process of blasting excavation, the tensile stresses occur and produce cracks in the surrounding rock. The cracks will extend, branch and some even coalesce under subsequent blasting operations. Stress waves superposition may result in more complex fracture mechanism with multi-boreholes.