Minimizing Negative Effects of Blasting on underground Structures

The present paper mainly deals with the prediction of blast-induced ground vibration level in Bakhtiary formation at intake of waterway system in Gotvand dam, Iran. For this research the ground vibration components were recorded carefully by means of 3 sets of vibration monitors for 32 blasts during bench blasting in front of tunnels. Then, the data pairs of scaled distance and particle velocity were analyzed by using the USBM equation. At the end of the statistical evaluations, a relationship between peak particle velocity and scaled distance for this site was established with good correlation. Again, other data measurements during tunnel excavation near concrete structures were used to validate the predicted PPV and optimize the blasting patterns to omit the effects of resonance and vibration in USBM (RI-8507) standard. Based on the vibration tests done in Bakhtiary conglomerate, ground vibration induced by underground blasting is at least 3times greater than vibration induced by bench blasting in the same rock, so constant dynamic factors of the rock mass (Bakhtiary conglomerate) which are related to vibration velocity are changed between 350-420 and 1.63-0.955.

کلیدواژه ها:

Tunnel excavation ، vibration effects ، PPV ، scaled distance ، USBM