Vibroacoustic measurements and analysis of blasting works

Abstract

Blasting works cause short-term high-energy shock waves-acoustic, air (airblast) and paraseismic. The duration of the event can be up to 2-3 seconds, while the rise time to the peak value is directly related to the delay between the individual explosive material (EM) and the firing sequence and ranges from a few to several milliseconds. Their propagation in the environment can affect people, animals and construction structures located not only in the close but also further distance from their source. If EM is placed on the surface of the earth during the detonation, the shock wave spreads evenly in all directions in the half-space, and when the detonation follows in rock, the wave usually travels in one direction and is accompanied by a paraseismic wave. However, the sound heard when detonating is part of the wave spectrum in the band from 20 to 20000 Hz, while the airblast itself has a frequency of less than 20 Hz. Since at some distance from the detonated EM, the parameters of the airblast are close to the parameters of the acoustic wave, the method of spreading the acoustic wave depends to a great extent on atmospheric conditions, i.e. density, temperature and humidity of the air, and from wind speed and its direction. To get to know the essence of the phenomenon of the impact of blasting works, measurements are carried out considering the propagation conditions, i.e. meteorological conditions as well as vibration analysis in the ground itself and on the building substructure. This paper presents the results of research carried out by the Authors in terms of the correct assessment of the impact range (acoustic, airblast, paraseismic waves) during EM detonation placed on the surface.

Issues of Data Acquisition and Interpretation of Paraseismic Measuring Signals Triggered by the Detonation of Explosive Charges

“…Based on the conducted research and preliminary analysis, it can be concluded that the problem of measuring the impact of vibrations and air shock waves resulting from the detonation of explosive charges is a difficult issue and requires extensive experience, both when performing tests and analysing their results. Due to the more and more frequent execution of blasting works in the vicinity of buildings, it is necessary to apply new methods of vibration forecasting [ 36 ] or their analysis [ 12 , 35 , 37 ]. Thanks to this, it is possible to increase the credibility of the forecast and at the same time to a greater degree control the negative impact to environment of the blasting works performed.…”

“…The interaction of these effects may lead to a change in the intensity of one effect or to a limitation in accuracy of the measurements while mitigating another effect. Thus, effects that interact with each other may also be called “combined effects” [ 12 , 13 ]. This issue is very important, notably when the measurements of an effect are made in close proximity to the location of the detonated explosive charge.…”

The Influence of Vibrations Induced by Blasting Works in an Open-Pit Mine and Seismic Events in an Underground Mine on Building Structures—A Case Study

“…The dominant frequency of blast vibrations plays a crucial role in vibration persistence and its amplification or reduction characteristics in structures [22][23][24]. Several methods and models have been developed to predict and optimize blast-induced ground vibrations [25][26][27][28]. Guo and Li proposed a hybrid intelligent model using a least-squares support vector machine (LSSVM) optimized with a particle swarm algorithm (PSO) for vibration prediction [10,29].…”

Multidimensional Data Interpretation of Vibration Signals Registered in Different Locations for System Condition Monitoring of a Three-Stage Gear Transmission Operating under Difficult Conditions

“…The most fundamental goal of operational diagnostics is to detect defects at early stages of the related changes, before a transmission becomes actually damaged. An assessment of the dynamic state of a transmission based on an analysis of vibroacoustic signals is a problem discussed in numerous papers [ 1 , 2 , 3 , 4 ]. It should be noted that there are applicable standards and recommendations that primarily consider the aspects of fatigue strength, while disregarding the nature of the transmission damage at the same time.…”