Engineering Rock Mechanics

Vibrations due to excavation 265

0.3

Surface

• coal and mine blasting

0. I
   f= principal frequency

* 0 Quarry blasting

III-III

7 Construction blasting

eZa Localized excitation

0.2

0.1

0

E

2

50 5 IO 15 20

Natural frequency (Hz)

3

2

0.2

0.1

5 10 15 20

Damping (% of critical)

0

Principal frequency (Hz)

Figure 15.25 (a) Examples of principal frequencies induced by blasting (from
Siskind et al., 1980). (b) Examples of fundamental frequencies for low-rise residential
structures (from Dowding, 1985).

Frequency (Hz)

Figure 15.26 Example ground motion and structure response spectra (from
Dowding, 1985).