Selection of site specific vibration equation by using analytic hierarchy process in a quarry
Introduction
Apart from its economical and production benefits in mines and quarries, blasting techniques create many adverse effects, such as environmental problems. First and foremost, the seismic waves produced by blasting causes damage on nearby structures and buildings. Frequency and particle velocity components are the most effective parameters on blast induced damage. Hence, determining the seismic energy distribution is important. This aspect has to be taken into consideration in the course of blast design, particularly with respect to minimizing the environmental issues (Kalayci, 2011).
Over the years and for different aims, many research studies have been carried out on blast induced vibration propagation. Although their main purpose was to isolate environmental issues, additional reasons included scaling the blasting performance and predicting and controlling the structure response (Dowding, 1985, Ambraseys and Hendron, 1968, Siskind et al., 1980, Ghosh and Daemen, 1983). Researchers considered, scaled distance, charge per delay and peak particle velocity data as decisive parameters and used statistical approximations as the analysis technique (Dowding, 1985, Siskind et al., 1980, Ghosh and Daemen, 1983, Gupta et al., 1988, Nicholls et al., 1971).
It is widely known that blast induced ground vibrations cause damage in ratio to their carried energy level. The energy level of vibrations counted with Particle displacement (mm), Particle velocity (mm/s), Particle acceleration (mm/s2) and wave frequency (Hz) (Dowding, 1985, Ambraseys and Hendron, 1968, Jimeno et al., 1995, Karadoğan, 2008, Faramarzi et al., 2014). A decisive approximation method or a formula has not yet been established because of the complexity of the subject. However, the well accepted empirical PPV attenuation equation is expressed in the form of a power law, as follows in Eq. (1) (Dowding, 1985);
where PPV is peak particle velocity, W is the maximum charge per delay, R is the distance between the monitoring and shot point.
Because of the complexity of the topic, some researchers used different analyses and intelligent systems for evaluating the vibration components and attenuations (Kahndelwal and Shing, 2006, Dehghani and Ataeepour, 2011, Mohamed, 2009).
Moreover, different researchers use different methods on reaching conclusions on geological data. Tutmez et al. (2012) used clustering based areal model in evaluating geo-environmental data whereas Başçetin (2007a, 2007b) used the selection of an optimal reclamation method; using an AHP-based model was evaluated for coal production in an open-pit coalmine. Also, Yavuz et al. (2008) applied AHP method using geological parameters for optimum support choice in a coalmine.
In this study, vibration analysis, formed using the commonly accepted PPV forecast equation, were studied for 12 years in a quarry located in Istanbul, Turkey. In each part of this study, it was notified that each output equation creates a different estimation. As the Analytic Hierarchy Process (AHP) was used, it was decided to use same field, where there are buildings, to carry out the excavation activity, and that the charge magnitude should be amplified in order to choose the best equation, verifying the most accurate output data in a 300 m distant field.
Since it would be necessary to amplify the charge magnitude for the excavation activity in a new practice in the same field, it was decided to use the Analytic Hierarchy Process (AHP) to choose the forecast equation that verifies the most accurate data by taking into consideration the buildings located in 300 m vicinity.
While using AHP, 102 vibration records were used as test data and classified according to distance and charge magnitude. For each group, estimations were made according to the previous years' equations. The error rate, number of data set, determination coefficient (r2) and the year of equation obtained, were used as estimation criteria and their weighted percentage was set. The decision matrix and priority vector was obtained and the consistency analysis was made. Ranking values were finalized according to common evaluation by researchers who have been working on the field for the past 12 years.
Section snippets
Analytic hierarchy process (AHP)
Myers and Alpert first introduced the Analytical Hierarchy Process in 1968. In 1977 it was developed as model by Saaty, in order for it to be applied in problem solving and decision-making processes. This is a method of decision-making and estimation used in defining decision hierarchy and which involves a percentage breakdown of decision edges on factors effecting the decision-making process. AHP depends on individual comparisons based on level of importance in factors affecting decisions or
Test site
This study was carried out at the Akyol quarry, located in the Catalca district of Istanbul province, in Turkey. The location of the district, and the satellite image of the quarry, can be identified using the Google Earth program, as shown in Fig. 1. The distance from the quarry to the closest building in the village is around 300 m.
Test procedure
Ground vibration components, induced by blasting in the quarry, were monitored to estimate site-specific attenuation for the quarry, by using vibration monitors. The parameters of charge quantity per delay, and the distances between the sources and the stations, were carefully recorded. The distances between shot points and monitor stations were determined using GPS. Blasting patterns and explosive charges at the shots were observed, and no changes were made in these patterns and charge amount.
AHP analysis
The goal is to choose the best estimation equation from among the 11 pre-set equations (Table 2) constituted according to the criteria.
A simplified flow chart of the AHP process is presented in Fig. 4 as follows:
Criteria for goal: To find out the most convenient equation in order to estimate damage on high level of amplitude in charge at distance of 300 m.
Criteria: For verification of the estimation, in values accumulated from test data within a fixed area and charge period (Table 7), the year
Discussion
While building up process structures, if a structure on a distant range and at risk of damage is taken into account, the highest point was assigned to equation group in distant range, which made the most acceptable estimation (having lowest rate of fault in estimation). The proceeding applicant may set his own level of importance following this sample as guide.
The equations presented in Fig. 2 are a form of curves generated from various years, showing a change according to the years elapsed.
Conclusions
The goal of this study was to estimate the vibrations formed following a blast in a quarry located in the city of Istanbul, in Turkey. In order to do so, through the use of Analytic Hierarchy Process, it was necessary to analyze and identify the most appropriate equation from among 11 estimation equations. In the analysis, 102 vibration recordings were used as tests data and the test data was estimated using 11 equations. The Analytic Hierarchy Process was conducted using error percentages, the
Acknowledgments
This study was supported by Istanbul University Scientific Research Projects (Project Number: T10296) and The Scientific and Technological Research Council of Turkey (Project Number: 110M555).
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