ABSTRACT
Urban tunneling induces not only changes in rock massif (e.g. Rozsypal 2001), but buildings and inhabitants in the nearest surroundings above the tunnel or a mine working can be affected too. Vibrations are one of the most significant effects, especially when blasting operations are used as part of technological process. Seismic load on buildings and constructions can be evaluated with use of maximum velocity amplitude V and prevailing frequencies f in records. There is an effort to compile a universal relation for prediction of the maximum amplitude V . So-called Langerfor’s relation (Bongiovani 1991) is often used:
There, Q is the total charge or charge fired in one stage, R is distance, K is a coefficient representing physical properties of medium where the waves spread, m and a are empirical constants. Properties of medium (local geological pattern) influence attenuation, refraction and reflection of seismic waves and their modification into different types on boundary; therefore they have significant influence on resulting wave field, e.g. Isaac (1991). Similar empirical relations, which optimally satisfy local geological conditions and conditions for blasts performing, are presented in many other publications.All relations are based on empirical constants that represent studied locality and that can be obtained by parametric measurements. Analyses of
wave patterns can be performed for either a whole record or parts of a records representing blast of charge in individual stages (e.g. Pandula & Leššo 2005).
