Martin F Stott, BSc. This paper was first published in GE’s September 1979 edition.
The prediction of damage caused by explosion-induced ground vibration has been studied for many years. Early work by the US Bureau of Mines (Thoenen 81 Windes, 1942) revealed that the use of Mercalli Scales for determining the effects of earthquake vibrations cannot be applied to vibrations originating from quarry blasts. Later work by Duvall 8t Fogleson in 1962, and Langefors & Kihlstrom in 1967 showed that the crit rion of peak particle velocity could be used to predict structural damage. A velocity of 50mm/sec is now generally recognised as the threshold value below which the damage to structures from ground vibrations is minimal.
However, vibration analyses based on this ‘structural damage’ criterion are not appropriate for an assessment of the stability response of slopes to ground shaking. A suitable dynamic approach was advocated in 1973 by Sarma, to determine the sensitivity of soil slope stability to peak horizontal acceleration.
This work was undertaken to show that practical design chart to give the safe proximity for quarry blasting adjacent to slopes for various explosion intensities. This work was undertaken to show that limestone quarrying could be carried out by blasting, whilst maintaining an acceptable factor of safety for the slopes of an adjoining spoil heap. The object was to maintain the security of the tip without being ‘over cautious’, thus maximising limestone extraction.