## 3 Results and Discussion  
### Results of the First Tests and Attenuation Law for the Air Overpressure Due to Common Blasts  
The detonation of the 90 charges of Riodin-type gelatinous dynamite located at different distances, detailed in Table 4, was carried out on different days. For each detonation, the value of the air overpressure of the detonation was measured in a straight line and was recorded without obstacles using the high-pressure microphone. In order to analyze the air blast wave values measured in the full-scale tests, the variable scaled distance Z (m/kg\({}^{1/3}\)) defined by Equation (1) was used. This variable includes the influence of the two independent variables that clearly affect the value of the detonation overpressure. The calculated scaled distance and the value of the air blast wave or air overpressure for each detonation are shown in Table 6.  
Figure 2: Charge locations in front of the different structures. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**N**} & \multirow{2}{*}{**Distance (ns)**} & \multirow{2}{*}{**Change (kg)**} & \multirow{2}{*}{**Observinger (ms)**} & \multirow{2}{*}{**N**} & \multirow{2}{*}{**Distance (ns)**} & \multirow{2}{*  
All the cases are characterized by short overpressure pulses. To illustrate it, the overpressure records obtained in tests no. 17 (\(S_{b}\) = 7.85 kPa) and no. 37 (\(S_{b}\) = 14.3 kPa) are shown in Figure 3 (left and right, respectively). The duration of the positive phase is only a few milliseconds, 5-10 ms. They are in accordance with the results of recently published research [16], keeping in mind that in our case, the explosive charge is on the floor, and consequently the overpressure is approximately twice the overpressure measured by them. The graph in Figure 4 was obtained by representing the overpressure measured at each detonation against the scaled distance in logarithmic scales. It is clear that there is a linear relationship between the \(\log(S_{b})\) and the \(\log(Z)\), which means that there is a potential relationship between the variables \(S_{b}\) (kPa) and \(Z\) (m/kg\({}^{1/3}\)). By applying logarithms and a least squares adjustment, the following relationship was found:  
\[S_{b}=309.33\cdot Z^{-1.216} \tag{3}\]  
with a high correlation coefficient \(r^{2}\) = 0.96. This is in accordance with the first experiences in this field [10]. On the other hand, the formula is quite similar to the prediction model proposed by the manufacturer of the explosive:  
Figure 4: Air overpressure measured as a function of scaled distance with Riodin charges (dots are actual values while lower and upper lines correspond to Equation (3) and Equation (5) respectively). Figure 3: Air overpressure measured in tests no. 17 (**left**) and no. 37 (**right**). \[S_{b}=322\cdot W^{0.56}\cdot R^{-1.3} \tag{4}\]  
although the latter gives results lower than the ones obtained from the experiences described here and it is useful only for \(Z>\)100. In the last years, different relationship between air peak overpressure Sb and scaled distance \(Z\), mainly polynomial, have been proposed by several authors [3; 4; 5]. We propose the exponential function for coherence with the analysis of air blast wave due to blasting in civil engineering with which this study is most related. On the other hand, it is a simple formula that only needs two empirical parameters. The relationship between the logarithm of the air overpressure log(\(S_{b}\)) and the logarithm of the scaled distance log(Z) is linear, and these two parameters can be deduced easily from field data by means of a linear regression. In the present study, the correlation coefficient found is high, \(r^{2}=96\%\), demonstrating that it is a sufficiently accurate approach for different analysis. The point cloud and the regression line are represented in Figure 4. As can be deduced from the same figure, some actual values are higher than the predicted ones.