International Journal of Science, Technology and Society 2014; 2(3): 53-58 Published online May 30, 2014 (http://www.sciencepublishinggroup.com/j/ijsts) doi: 10.11648/j.ijsts.20140203.14 Importance of blast-design in reduction of blast-induced vibrations AJAKA, Ebenezer Oyedele 1 , ADESIDA, Patrick Adeniyi 2 1 Department of Mining Engineering, the Federal University of Technology, Akure, Nigeria 2 Fountain Construction Company, Km 3, Akure-Owo Expressway, Akure, Nigeria Email address: akdenezer@gmail.com (Ajaka E. O.), adepatade@gmail.com (Adesida P. A.) To cite this article: AJAKA, Ebenezer Oyedele, ADESIDA, Patrick Adeniyi. Importance of Blast-Design in Reduction of Blast-Induced Vibrations. International Journal of Science, Technology and Society. Vol. 2, No. 3, 2014, pp. 53-58. doi: 10.11648/j.ijsts.20140203.14 Abstract: The dissipated energy generated during blasting creates environmental problems in the form of ground vibration, air overpressure and flyrock. With increasing mining and construction activities in areas close to human settlements, ground vibration has become a critical environmental issue as it can cause human annoyance and structural damage. The magnitude of ground movement was measured in term of Peak Particle Velocity (PPV) with the aid of USS 2000-DK Seismograph. Site constant K, and site geological factor m were determined for both quarries by plotting the log-log graph of the maximum PPV against scaled distance. The data collected for the twenty blasting activities in each of the quarry sites have shown that the peak particle velocities (PPV) recorded varied directly with the charge weight per delay but inversely with scaled distance (SD) and shot to monitored distance for both selected sedimentary and igneous rock. A comparative analysis between the results obtained for constant charge per delay of 1000 kg, and monitoring distance of 500 m, 750 m and 1000 m were carried out. The magnitude of vibration for limestone is about twice that of granite at 300 m from the shot point and increase to about five times at 2200 m. This is evident when considering the main mechanisms which contribute to ground motion dissipation such as; damping of ground vibrations which cause lower ground vibration frequencies with increasing distance, discontinuities causing reflection, refraction and diffraction, internal friction causing frequency dependent attenuation, which is greater for coarser grained rocks and geometrical spreading of rock. Keywords: Blast-Induced Vibrations, Scaled Distance, Peak Particle Velocity, Seismograph, USBM Predictor Equation 1. Introduction Blasting is the principal method of rock breakage in mining and construction projects throughout the world. This may probably be due to its distinct advantages like economy, efficiency, convenience and ability to break the hardest of rocks. However, only a portion of the total energy of the explosives used in blasting is consumed in breaking rocks while the rest is dissipated. The dissipated energy creates environmental problems in the form of ground vibration, air overpressure and flyrock. With increasing mining and construction activities in areas close to human settlements, ground vibration has become a critical environmental issue as it can cause human annoyance and structural damage [1]. During blasting, explosive charges produce a great amount of energy, some of which is transmitted in the form of stress waves beyond the area of the fragmented rock. The propagating stress waves travel in the rock and soil and produce ground vibrations that have the potential to cause damage to structures in the vicinity of the blast. Much of the damage that has occurred near blasting sites in the past has been to residential structures that have experienced cracks in walls and ceilings. However, there is the potential for more serious structural damage if the vibration levels are too high [2]. In the past forty years, many investigations have looked at the damage that ground vibrations from blasting may cause. The United States Bureau of Mines has done many of the studies, primarily concentrating on the damage to residential structures. Previous studies have found that peak particle velocity is the best index for predicting damage to residential buildings. On the basis of damage studies to residential type structures, the U.S. Bureau of Mines in 1962 recommended that the ground motion should not exceed a 50.0 mm/sec peak particle velocity at a point of concern [3]. One of the most controversial issues facing the mining, quarrying and construction industries is ground vibration