2017 Volume 133 Issue 6 Pages 123-131
Although blasting is a quite efficient and economical excavation method, it is rarely applied to tunnel projects close to residential areas due to its environmental impacts, especially with regard to vibration and noise. Two key controls used to mitigate the occurrence of noise and vibration due to blasting are the use of small instantaneous explosives charges and the use of precise delay times to initiate the blast design sequence. An advanced electronic detonator, which has its precision of 0.01% of designed delay time and has made it possible to achieve precise initiation control in blasting, was introduced and used in a tunnel construction site in Japan. Testing of the delay times during blasting was carried out, the test results revealed the specific features and performance of the detonator to control the blasting vibration especially within a short distance of the tunnel face. In previous studies, several ways of simulating blasting waveforms were used. One of these, the Monte Carlo method, in which the production wave was reproduced by superposing a single wave had the potential to give good predictions of the production waves that might occur. Therefore, in this study, a similar way of simulating production waves was carried out. Section peaks in the production waveforms correspond with the detonation of each blasthole. These section peaks were found to follow the Weibull distribution, even though the section peaks might be influenced by amount of explosives, drill alignment, and geological inhomogeneity etc. More detailed simulation with consideration of difference in travel time and the change of the Weibull parameters with distance gives further precise results compared with the real production waves. This study leads more precise method of predicting production waves and of optimum blasting design.