Structural safety criteria for blasting vibration based on wavelet packet energy spectra
Zhong Guosheng a ,b ,*,Li Jiang a ,Zhao Kui a
a School of Resources &Environmental Engineering,Jiangxi University of Science &Technology,Ganzhou 341000,China b
School of Civil &Transportation,South China University of Technology,Guangzhou 510641,China
a r t i c l e i n f o
Article history:
Received 24May 2010Accepted 2July 2010Keywords:
Blasting vibration
Wavelet packet transform Response energy Safety criteria
a b s t r a c t
Given multi-resolution decomposition of wavelet packet transforms,wavelet packet frequency band energy has been deduced from different bands of blasting vibration signals.Our deduction re flects the total effect of all three key elements (intensity,frequency and duration of vibration)of blasting vibration.We considered and discuss the dynamic response of structures and the effect of inherent characteristics of controlled structures to blasting vibration.Frequency band response coef ficients for controlled structures by blasting vibration have been obtained.We established multi-factor blasting vibration safety criteria,referred to as response energy criteria.These criteria re flect the total effect of intensity,frequency and duration of vibration and the inherent characteristics (natural frequency and damping ratio)of dynamic responses from controlled structures themselves.Feasibility and reliability of the criteria are validated by an example.
Copyright Ó2011,China University of Mining &Technology.All rights reserved.
1.Introduction
When we assess safety in blasting,we should first of all establish safety criteria,which re flect factors impacting on seismic blasting.Practice shows that in many cases,a single particle velocity as the only indicator to measure seismic intensity of blasting does not re flect accurately the actual breakage that occurs in structures,because the frequency of seismic waves,duration of vibration and other factors were not considered [1e 3].Research shows that,damage to structures caused by blasting vibration is the result from a variety of factors,such as intensity,frequency and duration of vibration as well as the characteristics of a dynamic response of the controlled structures themselves [4,5].However,current safety standards have neither considered the duration of blasting vibra-tion nor the inherent properties of the controlled structures (i.e.,natural frequency and damping ratio).It is inevitable that there are some defects and shortcomings in carrying out safety measures.In order to advance new safety criteria to re flect all the factors involved in blasting vibration,should be put on the agenda as soon as possible [6,7].
Wavelet packet techniques have been used to analyze blasting vibration signals.Based on wavelet packet energy spectra and the structure of dynamic responses,new safety criteria have been
established,which re flect the total effect of the intensity,frequency and duration of vibration and the characteristics of dynamic responses of the controlled structures themselves.It is of theoret-ical and practical importance to assess accurately and rationally the seismic effect of blasting by these criteria.The feasibility and reliability of these criteria are validated by live data of blasting vibration.
2.Wavelet packet energy spectrum analysis of blasting vibration
2.1.Characteristics of wavelet packet analysis
Wavelet analysis decomposes signals into two parts:low-frequency and rmation lost in the low-frequency part could be obtained from the high-frequency part.In turn,the low-frequency part is decomposed into two parts and this decomposition can be continued to a number of deeper levels.From the structure of wavelet decomposition it can be seen that the frequency resolution of the wavelet transform reduces with increased frequency.Wavelet packet analysis (WPD)is different.It decomposes signals not only into low-frequency signals,but also into a high-frequency part.WPD can adaptively select the appropriate frequency spectrum to match the signal spectrum from the analysis of the signal characteristics and requirements,it is relatively re fined method.Many publications dwell on its
*Corresponding author.Tel.:þ867978312259.E-mail address:zgs1001@ (Z.
Guosheng).
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Mining Science and Technology (China)
journal ho mep age:
/locate/mstc
1674-5264/$e see front matter Copyright Ó2011,China University of Mining &Technology.All rights reserved.doi:10.1016/j.mstc.2010.12.016
Mining Science and Technology (China)21(2011)35e 40
