Issue 55

A. Ata et alii, Frattura ed Integrità Strutturale, 55 (2021) 159-173; DOI: 10.3221/IGF-ESIS.55.12

As shown in Fig. 13.a-b and 14, the displacement is reduced by about 87%. The main reason for this reduction is the high stiffness of soil (B) regarding to soil (A). Effect of Weight of TNT In the second study, for cases 3, 4, 5 and 6, four different TNT charges(100, 200, 300 and 400 kg) were applied at constant scaled distance from ground surface, 1.0 m. Soil (A) is used in these cases. Fig. 15a and Fig. 15-b show the kinetic energy and plastic dissipation energy for the tunnel respectively. Fig. 15a-f show the pressure displacement along Paths 1 and 2 at the four charges at different time histories. Fig. 17a-b show the displacement along Paths 1 and 2 for the four cases.

Figure 15: a. Kinetic energy with time. b. plastic dissipation energy with time.

Figure 16: a. Pressure along Path 1 at 0.015 sec. b. Pressure along Path 2 at 0.015 sec. c. Pressure along Path 1 at 0.03 sec. d. Pressure along Path 2 at 0.03 sec. e. Pressure along Path 1 at 0.05 sec. f. Pressure along Path 2 at 0.05 sec. The kinetic energy difference due to the TNT change is significant; the kinetic energy is increased by 64% when the charge weight increased from 100kg to 400 kg of TNT, (Fig. 15a). The same as the kinetic energy, the plastic dissipation energy increased as the charge weight increased to reach a difference of 65.81%between TNT= 100 and TNT= 400, (Fig. 15b). As shown in Fig. 16a-f, as the weight of TNT increases the pressure reaches the tunnel increases. The maximum pressure that reached the crown of the tunnel due to the four cases is 17.6 MPa, 21.96 MPa, 24.4 MPa, and 26.9 MPa. The pressure of the last case of 400 TNT is still bigger despite of running time, at 0.05 sec is still 13.43 MPa, despite of case 3, TNT=100, it is decreased to 4.80MPa and this is because of the enormous energy released from the weight of 400 TNT kg. From Fig.

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