In the present study, heat of combustion (ΔHc) values are calculated for energetic materials (EM's) pellets based on ammonium perchlorate (AP), ammonium dinitramide (ADN) and potassium dinitramide (KDN) using a bomb calorimeter unit. ADN, KDN, and AP were mixed with carbon black (CB) in various ratios for preparing EM's pellets. Two set of experiments were performed for evaluating ΔHc for prepared pellets. In the first set of experimentation, pellets made from the mixtures of ADN, AP, and CB in different ratios were used, while in the second set of experimentation, pellets made from the mixtures of KDN, AP, and CB in different ratios were used. In all the formulations, CB acts as an organic fuel and as a catalyst, while the AP, ADN, and KDN act as oxidizer entities. The pellets were prepared using a pellet maker provided with the bomb calorimeter unit. It was observed that pure ADN/CB pellet did not burn, while pure KDN/CB pellet did not burn. Further, pure AP/CB pellet produces the highest ΔHc as compared to other prepared EM pellets.
Penetration and perforation performance of the rock targets by hard projectiles is suitable for understanding the ballistic behavior of the strategic and important structures such as protective structures, bunkers, ammunition stores, and nuclear power plants that are sensitive to missile impacts. In this study, ballistic penetration tests and numerical simulations were performed to examine the behavior of geo-material targets against hard projectile impacts. The granitic rock plates were used as target materials, and the projectiles were made of hardened 4340 steel. A loading-rate dependent shear failure model was suggested based on experimental data and implemented into LS-DYNA using a usermaterial subroutine. The ballistic test results were used to validate the suggested model. The numerical ballistic data simulated experimental behaviors relatively well.
Hard rock tunnel blasting becomes more efficient with the state-of-the-art technology advancients of the computeraided drilling machine which minimises the drilling error. However, overbreak is still considered as the primary challenge of any tunnelling project using drilling and blasting methods. This study evaluates a standard tunnel blasting design for 1 m advance used in a tunnel construction site in Japan. Blast damage zone (BDZ) of a single buffer hole blast design of the tunnel is estimated using Ash's modified energy and pressure-based approaches which calculated as 0.81, and 0.95 m respectively. In succession, five numerical models with different tunnel perimeter spacing-to-burden (S⁄B) ratio were simulated using ANSYS AUTODYN to evaluate S⁄B ratio effects to damages beyond the tunnel contour. The average practical BDZ of the AUTODYN analyses was estimated at 0.83 m which is reasonably corresponding with the Ash's BDZ approaches. The results show that more damages caused when S⁄B ratio increases. When the perimeter space is fixed to 0.83 m, the most appropriate S⁄B ratio is 1.0 for the tunnel construction site. The presented process of the BDZ evaluation can be applied in tunnel blasting designs in practice to minimise possible overbreak
Blasting to crush rocks or concrete using thermite reaction mixtures is a promising technique to reduce ground vibrations and noise. In this study, the deflagration propagation speed of a commercial thermite with different charge conditions was investigated using a modified velocity of detonation (VOD) measurement system. As a result, the continuous deflagration of thermite was intimately connected with charging and confining conditions. Therefore, it is important to consider the types of charge and confinement to utilize thermites for applications involving rock and civil engineering.