Delineating rockmass damage zones in blasting from in-field seismic velocity and peak particle velocity measurement

Abstract

Damage to the surrounding rock during blasting either in underground or surface excavation, is a growing concern today. It
has been found that the integrity of rockmass is reduced significantly from pre to post blast condition due to disregard paid to
the surrounding rockmass. For exercising suitable engineering controls accurate measurement of the same is a prerequisite. To
delineate the blast-induced rock damage zone seismic imaging technique can be used. Seismic imaging is a non-destructive
method to determine the field seismic velocity of the rockmass for its characterisation. Further, it is considered that the blastinduced ground vibration is the root cause of rock damage due to structural dilation and should be controlled to localize its
effect. Different researchers have related ground vibration to damage to arrive at the thresholds levels of damage. However,
the accuracy in measurement/estimation of extent of damage is always a concern. This paper presents a case in which the
seismic imaging technique was successfully used to delineate the extent of rock damage extent. The damage zone was also
correlated with the vibration model developed to establish the same for its direct use in damage assessment.