Issue 64

H. K. Tabar et alii, Frattura ed Integrità Strutturale, 64 (2023) 121-136; DOI: 10.3221/IGF-ESIS.64.08

(a) (b) Figure 3: (a) The comparison of numerical modeling results and experimental results and (b) The location of measuring points. Validation: Rock mass The numerical simulation of the effects of the explosion vibration on the tunnel was performed based on the study of Nanjiang et al. (2012). Then, vibration velocity generated in the surrounding rock was analyzed at different positions based on field experiments and the site of the explosion[23]. Tab. 6 presents the comparison of the results of modeling and measurements. According to Tab. 6, the difference between the numerical modeling and the velocities measured by the device is 13% on average indicating a lower modeling error.

Percentage Difference (%)

Velocity from Modeling (cm/s)

Measured Velocity (cm/s)

Distance (m)

Explosive (kg)

10.88

1.5

1.683

69.7

45

10.7

1.81

1.634

61.2

33

5.05 14.4 25.8

1.62 2.19 1.27

1.542 1.919 1.009

63.9 50.9

32 32

62

25.8

Table 6: The comparison of experimental relationship and numerical modeling of rocks.

Parametric studies This section reviews the results of the numerical analysis of LS-DYNA software on the cross-sectional support structure equivalent to Lattice girder and shotcrete. The simulated velocity and acceleration results were investigated at the desired points, as it is shown in Fig.4 . Five groups of measurement points from A to E of the tunnel structure are presented in Fig. 4 in order to study the dynamic parameters. Each group includes five measurement points with a distance of 0.50m between them, with the first point closest to the site of the explosion (e.g.A1) and the farthest point (e.g. A5) 2m away from the working face. The same procedure was applied to points B, C, D, and E. Points A to E are from the tunnel crown to the lowest point of the tunnel sidewall.

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