New Approach for Identification of Suitable Vibration Attenuation Relationship for Underground Blasts

Abstract

For construction and mining activities, excavation is often performed with the help of blasting in hard or weathered rock or even hard soil. As a safety practice, the blasting operation is designed so that the nearby structures are not adversely affected. For this, blast vibration attenuation relationship for the ground media becomes necessary. In India, the relevant IS code specifies an attenuation relationship (Power expression) between the peak particle velocity, the charge weight and the distance of the monitoring point from the blast. However, the empirical coefficients are provided in IS code for only two categories-hard rock and weathered rock / soil. Hence they result in uneconomical and sometimes unviable blasting design. In lieu of above, site specific attenuation relationship may be used for design of blasting operation. Industrial practice is to find the empirical constants for the same Power expression (as IS code) using trial blast data from the site. For this purpose, the same dataset is used for parameter estimation as well as evaluation of the suitability of the estimated parameters. In this study it is demonstrated that evaluation of performance with a different dataset alters the conclusions. Further, expressions other than the commonly adopted Power expression might be more suitable for the relationship. In this article, two other expressions, namely, Reciprocal expression and Weibull model were identified which could be equally good. Exponents for scaled distance calculation, other than the popularly adopted 0.5, were found to be applicable in the case study. Trail blast data from a site was used to demonstrate the same. It was concluded that while developing site specific attenuation relationship, various expressions with different exponents should be examined for their suitability. The available dataset should be split into parameter estimation set and performance evaluation set. The best expression identified for the site from the performance evaluation set should be finally adopted for further activities.

Comparison of Presplit and Smooth Blasting Methods for Excavation of Rock Wells

“…rough the above analysis, it can be found that those comparison factors like crack, flatness, and damage are all related to excavation quality, whose influences are limited to the vicinity of the explosive source. Nevertheless, in practice, residents in the neighborhood are more concerned about the adverse impacts of blast-induced vibrations because they can propagate over long distances [24][25][26][27]. Hence, it is vital to investigate the vibration characteristics induced by blasting operations with two control techniques.…”

Quantifying and addressing uncertainties in empirical vibration attenuation relationship for underground blast by re-sampling

“…• It did not cover the uncertainties in model structure, which would include the expression form for the PPV. Methods to arrive at the best suited expression form for any site have been discussed in literature [7]. • The expression form for scaled distance (SD) was fixed, and uncertainty therein was not examined.…”

“…The trial blasting should be designed such that the area under consideration is represented well, with around 40 numbers of data sets, for development of the vibration attenuation relationship. First, the suitable equation form applicable for the site should be identified as elucidated in literature [7] from the trial blast data. Thereafter, employing the proposed methodology of re-sampling (each sample having, say, 30 data sets or more), the probability density functions should be established for the parameters of the chosen expression form.…”

“…Empirical vibration attenuation relationship for underground blasts are developed from trial blast data and subsequently used for design of controlled blasting operation for various applications such as deep excavations, tunnelling, and mining. There have been several studies in recent past [3,7,23,30,31,38,39] enumerating the various applications and improvements thereof for fitting empirical equations to the blast variables, namely, charge weight, monitoring distance and peak particle velocity (PPV). Furthermore, artificial intelligence (AI) tools such as artificial neural network [14,21,22,28,29,33], random forest algorithm [17], support vector machines [17], fuzzy logic, gene expression programming [8], analytical hierarchy process [13], and other tools [20,24] have been employed to develop better models for the underground blasts.…”

“…In the present case of estimate of blast variables for underground blasts, the various uncertainties involved may be the inherent variability of the ground response to underground blast, the variability of the soil properties in the area, the measurement errors from the trial blasting, the choice of location of the blast and measurements, the selected model and the estimated parameters. In the past, investigators have suggested methods for choice of best fitting empirical model for underground blast [7]. Whatever may be the best suited expression (generally the power form of expression is preferred for modelling vibration induced by underground blasts in industry), the estimated parameters would depend on the trial blast data.…”