Model Of Stages of Determination of Strength of Dynamic Fracture of Rocks and Digital Technological Verification

Abstract

Rapid development of engineering activities expands through a variety of rock engineering processes such as drilling, blasting, mining and mineral processing. Rock dynamic fracture mechanics methods are required to characterize the rock behavior in these activities. Dynamic fracture toughness is an important parameter for analysis of engineering structures under dynamic loading. Several experimental methods are used to determine the dynamic fracture properties of materials. Among them, the Hopkinson pressure bar and the drop weight have been frequently used to analyze the rocks properties. On the other hand, numerical simulations have been proved to be useful in dynamic fracture studies. Among various numerical techniques, the powerful extended finite element method (XFEM) enriches the finite element approximation with appropriate functions extracted from the fracture mechanics solution around a crack-tip. The main advantage of XFEM is its capability in modeling different states on a fixed mesh, which can be generated without considering the existence of discontinuities. In

this paper, first, the design of a drop weight test setup was presented, and afterwards, the experimental tests on igneous (basalt) and calcareous (limestone) rocks of single-edge-cracked bend specimen were discussed. Then, each experimental test is modeled with the XFEM code. Finally, the obtained experimental and numerical results were compared. The results indicate that the experimentally predicted dynamic fracture toughness has less than 8 percent difference with the dynamic fracture toughness calculated from extended finite element method.