A Study on Shock Wave Propagation Process in the Smooth Blasting Technique

Explosives can easily generate high energy and ultra-high pressure. In recent years, research on the advanced technological use of explosives is studied in various places. Here we focus on the Smooth Blasting Technique that is applied for tunnel blasting. This technique is performed to fracture concrete and to reduce the quantity of fragments, while avoiding stress concentration of ground pressure during tunnel blasting. When this technique is used, it is important to know what influence it will have. In our calculation code, the analysis of compressible substances, which cells transform greatly like air, was very difficult. In this study, we use LS-DYNA, an analysis code using a finite-element method. By analyzing the stress state of the air hole circumference, multilayer models such as air, Vinyl Chloride and water are analyzed and it aims to get the propagation process of the shock wave. The Arbitrary Lagrangian Eulerian (ALE) method is based on the arbitrary movement of a reference domain, which additionally to the common material domain and spatial domain, is introduced as a third domain. Three equations of state (EOS) are used in this study. The JWL equation of state is applied for the reaction of the explosive, and has form of a perfect gas equation of state. When the density becomes large, exponential terms modify the perfect gas equation of state. The Mie-Gruneisen equation of state is applied for water and poly vinyl chloride, and the linear polynomial equation of state is applied for air.