Analysis of efficiency and impact by deck charging patterns on rock blasting at Aruwakkalu Limestone Quarry, Sri Lanka

Abstract

There is a potential to enhance both the efficiency and the quantity of explosives in limestone excavation utilising deck charge patterns in the Aruwakkalu limestone quarry in Sri Lanka. To achieve this a series of combinations with ANFO and deck charge patterns were simulated using a numerical analysis software named JKSimblast – 2D bench. This study entails simulating and validating the existing blasting geometry in the rock blasting practice. The fragmentation curves of the real world blast events were analysed and plotted using an AI platform called “Streyos”. Subsequently, the blasting geometry was optimised by adjusting the spacing and burden with different charge amounts. A comparison was made between the explosive energy distribution figures of the simulated blast with optimised blasting geometry and the deck charging blast series. To simulate the limestone condition for the rock mass, throughout different simulations, the rock specific gravity (SG) was defined as 2.6. Optimised spacing and burden for a 10.3 m deep and 72 mm diameter blast hole pattern were found as 2.9 m and 2.4 m respectively, ensuring favourable conditions with controlled ground vibration (5 mms-1) and air blast overpressure (120 dB). The optimal configuration for minimising boulder formation in the upper section of the hole was 23.17 kg of ANFO quantity per hole with a two-charge deck pattern.