ABSTRACT
Limited knowledge on safe vibration levels near newly sprayed concrete (shotcrete) often leads to over-conservative limits in underground construction and tunnelling, with additional costs and planning uncertainties as a consequence. Work on compiling a database of practical vibration levels for shotcrete work close to blasting in hard rock have been initiated and will provide guidelines for safe distances and waiting times for newly sprayed wet-mix shotcrete. A large number of calculations are carried out with a previously developed and relatively computationally effective numerical elastic stress wave propagation model, which will result in a systematically compiled database. These guidelines, giving relationships between the amount of explosives, distance, rock type, shotcrete type, age and thickness, will be of great value as reference for design work and facilitate comparisons with in situ data. It will be possible to adopt the design to ensure undamaged and safer shotcrete constructions with longer service life.
