Prediction of the airblast wave effects near a tunnel advanced by drilling and blasting

Abstract

In this paper, a semi-empirical model for the prediction of the air wave pressure outside a tunnel due to blasting inside is developed. The model reproduces properly the complex phenomenon of the airblast wave propagation, both inside the tunnel and outside, and allows estimating the air pressure level (this is, generally, higher along the axis tunnel direction than in other directions). After the assessment of a theoretical basis, the model is calibrated from measurements made during a tunnel advancing by drilling and blasting in two phases: normal advance of the crown part and advancing by benching of the lower part. After this, the utility of the model is shown through a real case with a double negative air wave effect: existence of buildings and existence of protected natural habitat. Finally, the method is tested with measurements done in other tunnels and a practical way for using the model in two phases is proposed: one is the quantitative estimation of the air pressure or noise level, and the other is the qualitative estimation of the negative effects.