Abstract
Adverse effects of the blasting vibration on surrounding structures intensify importance of investigation on the blast frequency content while it has not been fully considered in blasting design. In this study, blast-induced frequency content and dominant frequency attenuation are investigated. The results of this study and its comparison with the previous studies demonstrate that investigation of different parameters influencing blast-induced frequency content including peak blast load pressure, rise time, and falling time by the experimental pressure-time history with its Fast Fourier Transform (FFT) analysis leads to the similar results of study by the velocity-time recorded data of an infield blasting. The outcomes of this study on dominant frequency attenuation for different types of explosives but in the same material show approximately the same dominant vibration frequency in far-field for different explosives, whereas a rapid drop of dominant frequency to half of the initial value in near distance to the blasthole can be observed. Investigation on dominant frequency attenuation versus distance for the materials with different natural ground frequencies demonstrates that the geomaterial tends to pass the vibration frequency closer to its natural frequency. If the earth has a lower natural frequency, it will pass the waves with lower dominant frequencies, but it will attenuate the waves with higher dominant frequency.
Highlights
According to Kutter and Fairhurst suggestion, three distinct zones are formed surrounding a blasthole named (1) a crushed zone due to strong hydrodynamic shock, (2) a transitional, nonlinear zone, and (3) an elastic zone (Vibration Zone). e parameters of blast-induced vibration, i.e., peak particle velocity (PPV), vibration frequency, and duration, can adversely affect the nearby structures such as buildings, tunnels, bridges, and dams which are the major concerns for designers and constructors in mining industry and construction operations [3, 4]. e vibration may be amplified and causes damage to the structures because the resonance occurs due to approximate equivalence between the natural frequency of the structures and dominant frequency of the vibration
A Fast Fourier Transform (FFT) algorithm in MATLAB software is used to investigate the influence of different parameters on the frequency content, including peak blast load pressure, rise time, and falling time. e pressure-time
Due to the importance of the adverse effects of the explosion, especially on surrounding structures near the explosion site, the study of the blast-induced frequency content is of particular importance, so in this study, the parameters affecting the frequency content and dominant frequencydependent attenuation versus distance have been studied
Summary
Drilling and blasting is an affordable and flexible method for rock mass excavation in different geological conditions [1]. To minimize blast-induced structural damage, much research has been performed to study the frequency content of blasting and its effects on surrounding structures [3, 7–10]. Erefore, Shock and Vibration numerical modeling can be an opportunity to study the mechanisms of explosion and its side effects and raise our knowledge of the blasting process considering the response of rock materials to dynamic loads [16, 17]. Is paper is divided into two sections: firstly, the analysis of different parameters influencing blast-induced frequency content, including peak blast load pressure, rise time, and falling time, based upon the Fourier transform of the blasting pressure-time history functions using MATLAB software; secondly, the study of dominant frequency attenuation for the materials with different natural frequencies and different types of explosives in Sangan iron ore mine (Iran) using numerical simulation in FLAC environment Ere are several restrictions in experimental studies and their results interpretation because of high costs and difficulties in providing controlled conditions. erefore, Shock and Vibration numerical modeling can be an opportunity to study the mechanisms of explosion and its side effects and raise our knowledge of the blasting process considering the response of rock materials to dynamic loads [16, 17]. is paper is divided into two sections: firstly, the analysis of different parameters influencing blast-induced frequency content, including peak blast load pressure, rise time, and falling time, based upon the Fourier transform of the blasting pressure-time history functions using MATLAB software; secondly, the study of dominant frequency attenuation for the materials with different natural frequencies and different types of explosives in Sangan iron ore mine (Iran) using numerical simulation in FLAC environment
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