ABSTRACT
V i b r a t i o n v e l o c i t y drops o f f r a p i d l y w i t h d i s t a n c e . The v i b r a t i o n s do not normally damage concrete s t r u c t u r e s near the e x p l o s i o n . B l a s t i n g i n the v i c i n i t y of elements of s t r u c t u r e and i n s t a l l a t i o n s which are s e n s i t i v e t o v i b r a t i o n s , such as computers i n operation, should, however, be avoided. I n b l a s t i n g t e s t s near normal windows, no damage was caused to the g l a s s . The minimum d i s t a n c e was about 1 m. Danish t e s t s ( L a u r i t z e n ) a l s o show t h a t v i b r a t i o n damage i s of very l i m i t e d extent provided t h a t b l a s t i n g i s not c a r r i e d out i n u n s u i t a b l e p o s i t i o n s . The v i b r a t i o n t h a t can be permitted i n conjunction with l o c a l i z e d c u t t i n g and p a r t i a l demolition i s c o n s i d e r a b l y g r e a t e r than the ground v i b r a t i o n s due to b l a s t i n g , p i l i n g or heavy v e h i c u l a r t r a f f i c . Ground v i b r a t i o n s are, i n most c a s e s , i n the form of s u r f a c e waves or R a y l e i g h waves. These have a low v e l o c i t y of propagation, s m a l l wavelengths and l a r g e amplitudes. There i s a r i s k of
F i g . 11. The v i b r a t i o n v e l o c i t y decreases r a p i d l y with d i s t a n c e .
