Allowed quantity of explosive charge depending on relative seismic sensitivity of rock mass.

The use is discussed of the oscillation speed of soil particles or rock caused by explosive detonations in a blast hole as a criterion for evaluating the potential of seismic activity to cause structural damage. An analysis is presented of research into blasting in sedimentary rock deposits, mainly limestone and dolomite. The results were used to develop a geological strength index (GSI), ranging from about 30 to 55, which, by applying the RMR or Q classification, can be used to assess rock masses as poor to acceptable. The Vukov Dol limestone open pit near Zagreb was used as a model. Test blasts and seismic measurements were used to determine the dependence of oscillation speed on the quantity of explosives and, based on the results, the allowed quantity of explosives per level of ignition was determined in compliance with DIN standard 4150. The correlations were used as a basis for verifying results from other localities, with the relative seismic sensitivity (RSO) of each rock mass being defined first. RSO values for each location and the three categories of structure covered in DIN 4150 were determined. Nomograms and graphs are presented which enable simple preliminary determination of the allowed quantity of explosives per ignition level.
The use is discussed of the oscillation speed of soil particles or rock caused by explosive detonations in a blast hole as a criterion for evaluating the potential of seismic activity to cause structural damage. An analysis is presented of research into blasting in sedimentary rock deposits, mainly limestone and dolomite. The results were used to develop a geological strength index (GSI), ranging from about 30 to 55, which, by applying the RMR or Q classification, can be used to assess rock masses as poor to acceptable. The Vukov Dol limestone open pit near Zagreb was used as a model. Test blasts and seismic measurements were used to determine the dependence of oscillation speed on the quantity of explosives and, based on the results, the allowed quantity of explosives per level of ignition was determined in compliance with DIN standard 4150. The correlations were used as a basis for verifying results from other localities, with the relative seismic sensitivity (RSO) of each rock mass being defined first. RSO values for each location and the three categories of structure covered in DIN 4150 were determined. Nomograms and graphs are presented which enable simple preliminary determination of the allowed quantity of explosives per ignition level.