Evaluation of blast load time series

During blasting, high temperature and pressure gas is instantaneously emitted, which results in fracture of rock mass. Outside the fractured zone, energy is transmitted in radial direction in the form of elastic waves. In this study, the fracturing process is not modeled. Instead, to simulate the propagation of blast induced vibration, the pressure load derived from empirical equations is applied to the fracture boundary. In the numerical modeling, accurate prediction of the blast load time series, including the detonation pressure, is most important. However, comprehensive study which evalutes the blast load from measured attenuation relationship is limited. In this study, the propagation of vibration due to explosion is simulated using numerical analysis and blast time series was back-calculated through comparison withthe measured record. To allow propagation of the vibration in radial direction, the fracture zone was modeled as a circle and pressure was applied normal to the boundary. The results show that the characteristics of blast vibration are highly dependent on the frequency of the load and the damping ratio of rock mass. In addition, it was found that the most widely used empirical function in Korea is not appropriate for modeling the blast inside the tunnel. In addition, it is shown that the detonatio pressure should be reduced by a significant amount from the empirical equation. When the adjusted load is applied, the results are in good agreement with the attenuation relationship derived from the measurements, regardless of the charge

keywords: 발파진동, 폭발하중, 파쇄영역, 진동감쇠, 수치해석, Blast vibration, Detonation pressure, Fracture zone, Attenuation, Numerical analysis

Reference

1. Choi, S.O., Park, E.S., Sun, W.C., Chung, S.K. (2004), “A Study on the blasting dynamic analysis using the measurement vibration waveform”, Journal of Korean Society for Rock Mechanics, Vol. 14, No. 2, pp. 108-120.

2. Choi, J.S., Lee, J.M., Jo, M.S. (2006), “A calculation of blasting load using input identification method & evaluation of structure's vibration in numerical analysis”, Journal of Korean Society for Rock Mechanics, Vol. 16, No. 3, pp. 232-240.

3. Itasca Consulting Group (2008), “FLAC (Fast Lagrangian Analyses of Continua) v.6.0”.

4. Jeon, S.S., Jang, Y.W., Jung, D.H. (2007), “Estimation of blasting distance satisfying allowable peak particle velocity - Analytical & Numerical analysis approach”, journal of KOSHAM, Vol. 7, No. 1, pp. 39-46.

5. Konya, C.J., Walter, E.J. (1991), Rock blasting and overbreak control, National Highway Institute, pp. 5.

6. Kramer, S.L. (1996), Geotechnical earthquake engineering, Prentice Hall, Upper Saddle River, N.J.,

7. Kuhlemeyer, R.L., Lysmer, J. (1973), “Finite element method accuracy for wave propagation problems”, Journal of Soil Mechanics & Foundations Div, Vol. 99, No. Tech Rpt.

8. Liu, Q., Tidman, P. (1995), “Estimation of the dynamic pressure around a fully loaded blast hole”:Retrieved from Canmet Mrl Experimental Mine.

9. Lysmer, J., Kuhlemeyer, R. (1969), “Finite element model for infinite media”, Journal of Engineering Mechanics Division. ASCE, Vol. 95, pp. 859-877.

10.

10. Park, D.H., Cho, Y.G., Jeon, S.W. (2006), “A case study on the blasting analysis of slope using monitored vibration waveform”, Korean Society of Explosives & Blasting Engineering, Vol. 24, No. 2, pp. 41-50.

11.

11. Park, D., Jeon, B., Jeon, S. (2009), “A numerical study on the screening of Blast-induced waves for reducing ground vibration”, Rock mechanics and rock engineering, Vol. 42, No. 3, pp. 449-473.

12.

12. Park, D., Kim, T.G., Ahn, J.K., Park, I.J. (2013), “Amplification characteristics of mountain slope”, journal of KOSHAM, Vol. 13, No. 2, pp. 117-123.

13.

13. Shin, J.H., Moon, H.G., Chae, S.E. (2011), “Effect of blast-induced vibration on existing tunnels in soft rocks”, Tunnelling and Underground Space Technology, Vol. 26, No. 1, pp. 51-61.

14.

14. Starfield, A.M., Pugliese, J.M. (1968), “Compression waves generated in rock by cylindrical explosive charges: a comparison between a computer model and field measurements”, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts: Elsevier, 5, pp. 65-77.

15.

15. Yang, H.S., Lim, S.S., Kim, W.B. (2003), “Tunnel blasting design with equations obtained from borehole and crater blasting”, Journal of Korean Geotechnical Society, Vol. 19, No. 5, pp. 327-333.

바로가기메뉴

Article Contents

Vol.16 No.1

Evaluation of blast load time series

Abstract

Reference

(사)한국터널지하공간학회