EXPERIMENTAL STUDY ON THE STABILITY OF SURROUNDING ROCK IN TUNNEL BLASTING CONSTRUCTION

In this study,criteria and blast ing technologies are introduced in order to control the stability ofsurrounding rock of tunnel built using drill and blast safety . The paper is composed of three parts,namely, a blast vibration propagation law in roof surrounding rock in close proximity to tunnel face,two formulae to calculate particle critical vibration velocity of shotcrete and key structural element atthe roof of tunnel, and innovative technologies of tunnel blasting . The blast vibration propagationlaw is the base to control the sta bility of surrounding rock during tunnel blast ing Based onMorhr Coulomb criterion and the dynamic analys is, two formulae to calculate the critical particlevibration velocity are proposed Based on a series of trial blasts using electronic detonators, tw oinnovative blasting technologies are derived. One is the blast holes detonated one by one by usingelectronic detonator , and another is the blast holes detonated by combining initiation system ofelectronic detonators and nonel detonators T he use of ele ctronic detonators in tunnel blasting notonly leads to a smaller blast vibration but also to a smaller extent of the EDZ (excavation damagedzone