ABSTRACT

Conventional numerical methods used to predict blast-induced vibration mostly adopt pressure curves estimated by theoretical or semi-empirical equations as an input parameter for detonation source, These equations however, have shortcomings in determination of the detonation pressure which is one of the most important input parameters for numerical analysis, because they assume ideal explosion conditions to estimate explosion energy and the calculated pressure curve has little or no information about the propagating medium. In this study, therefore, we suggested a numerical technique which uses velocity waveform obtained from a test the as an input parameter instead of pressure curve. A series of correction procedure was performed to estimate the particle velocity waveform at the source of explosion. The results from the developed method showed a good agreement with the measured vibration data from the test blast. By comparing the results from the simulation technique developed in this study with those from the conventional ones using pressure curves, it is concluded that the developed method is more adequate for predicting blast-induced vibration, This is because the estimated velocity waveform of the blast source reflects characteristics of the propagating ground more accurately and the simulation result using such input well fit the measured data.

INTRODUCTION

When blasting activities occur in urban area, which affect human beings and nearby structures, measurement of blast-induced vibrations and evaluation of their effect must be preceded. Blast-induced vibration is usually observed by direct measurement from the test blast, but in cases where a test blast can not be conducted due to specific site conditions or economic reasons, it can be estimated by numerical simulation. blast ground vibration equation derived from the test blast can then be compared and verified with the numerical simulation.

However, conventional numerical methods used to predict blast-induced vibration mostly adopt pressures estimated by theoretical or semi-empirical equations as an input for the detonation load. These equations assume ideal explosion conditions to estimate explosion energy, thus the calculated blast pressure is usually overestimated. In addition, the pressure curve has little or no information about the propagating ground because it assumes a simple function such as a sinusoidal function. Consequently, dynamic numerical simulations using a pressure curve have several shortcomings in determinating the waveform of the blast source, one of the most important input parameters.

In this study, therefore, we suggested a numerical method which uses particle velocity waveform obtained from a test blast as input load instead of a pressure curve. A series of correction procedures was performed to estimate the particle velocity waveform at the blast source. We evaluated the feasibility of this

(Figure in full paper)

with the test blast results. Numerical simulation was accomplished by using FLAC, the two dimensional finite difference program.

ESTIMATION OF PARTICLE VELOCITY WAVEFORM AT DETONATION

Dynamic analysis using particle velocity waveform as an input source better reflects ground conditions and the actual phenomena of blasting than the conventional analysis using a pressure curve.

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