This study was conducted to find out the effect of th controlled-blast in tunnel on the ground above the tunnel. To do this, existing documents related to the blast were reviewed and the measured data of blast loading and particle velocity on the ground were analyzed and compared with the results of numerical analysis. In addition, the blast-induced ground settlement were estimated through a numerical analysis.
The soil profile in the target site consist of fill, colluvium, residual soil, weathered rock, and soft rock starting from the surface. Sandy soil is the main material in the colluvium layer and the ground water level is located low at residual soil, weathered rock, and soft rock layers.
The particle velocities measured at the closest ground from the blast location was below the permissible velocity of 0.3 cm/sec set by the Ministry of Environment. Thus, we concluded that the blast vibration has very little effect on the ground. The particle velocity predicted from the numerical analysis also showed the similar pattern with the measurement which is below the permissible velocity of 0.3 cm/sec.
The effect of the controlled-blast on the ground settlement was also examined through the numerical analysis and we found that its effect is little to ignore. Thus, we also concluded that the blast vibration has very little effect on the ground settlement. It indicates that the blast conducted in tunnel was properly controlled. Also it may be related to the ground condition in the target site. The damping effect of the blast vibration in soil is much bigger than that in rocks, and the blast-induced vibration in soft rock is damped during the propagation of the soil layer.