## 3 Results
### Analysis and Evaluation of Measured Data
From the plot (Figure 8) it is visible that the highest attenuation of the seismic wave initiated by blasting works in Trebejov Quarry and the lowest values of particle velocity on building No. 91 were achieved at millisecond timing delays of 15 and 20 ms. The highest values of the particle velocity were measured at a millisecond timing delay of 5 ms. During a timing delay of 20 ms (blast No. 698), a lower particle velocity was achieved than for blast No. 693, close to which the only borehole was detonated. At standpoint S2, the vibrograph Svantek 958A was set at the reference point (Decree MZ SR No. 549/2007 and nr. 237/2009)--in the middle of the building. It monitored the effects of vibrations on the inhabitants of the building. Figure 8: Dependence of measured values of peak particle velocity in research blasts (source: author). Figure 9: Dependence of measured values of peak acceleration in blasts (source: author). Figure 9 shows that the maximum attenuation of the seismic wave initiated by the blasts in Trebejov Quarry, and the lowest values of the acceleration at building No. 91 were achieved during a millisecond timing delay of 20 ms. The highest values of vibration acceleration, \(\mathrm{a_{wmax}}\) = 0.078 m.s\({}^{-2}\),were measured at a millisecond timing delay of 1 ms. The timing of blasts No. 694 and No. 695 with a 1 ms delay was chosen in order to obtain a double seismic effect compared to individual blast No. 693. Although the measured values were the highest, they did not reach the expected double values. The measured maximum values of the acceleration for all blasts did not exceed the limit value \(\mathrm{a_{wmax}}\) = 0.11 m.s\({}^{-2}\), which is defined by the hygienic standard for the inhabitants of the building. The inhabitants of the building who were present at the research blasting operations did not perceive these vibrations as dangerous. At blasting No. 695, the seismic effects of two boreholes with doubled charge capacity and a millisecond delay of the blast in the second borehole of 5 ms were measured. The maximum value of vibration acceleration was approximately equal to that of blasting No. 693, meaning that a partial attenuation of the amplitude of the seismic wave generated by the first and second blasts occurred. At blasting No. 696, the seismic effects of two boreholes with doubled charge capacity and a millisecond delay of the blast in the second borehole of 10 ms were measured. The maximum value of the vibration acceleration was lower than that at blasting No. 695, the seismic effects of two boreholes with doubled charge capacity and a millisecond delay of the blast in the second borehole of 15 ms were measured. The maximum values of the vibration acceleration were equal to those of blasting No. 696, meaning that a partial attenuation of the amplitude of the seismic wave generated by the first and second blasts occurred. At blasting No. 698, the seismic effects of two boreholes with doubled charge capacity and a millisecond delay of the blast in the second borehole of 20 ms were measured. The maximum value of the vibration acceleration was lower than that at blasting No. 695, 696 and 697, meaning that the highest attenuation of the amplitude of the seismic wave generated by the first and second blasts occurred. The maximum vibration velocity was lower than that at blasting No. 693, when the charge capacity was half compared with blasting No. 698. The inhabitants of the building who were present at the research blast No. 698 also perceived these vibrations as safe. At the timing delay of 20 ms, when boreholes V10 and V11 were detonated with a delay of 20 ms (No. 698), a lower value of vibration acceleration was achieved than during No. 693, during which only one borehole V1 was detonated. In this way, it was experimentally shown that the suitable delay of the individual borehole detonation during blast works can decrease the seismic effect of the blast works and their impact not only on the buildings but also on their inhabitants.