Analysis of Cumulative Damage for Shared Rock in a Neighborhood Tunnel under Cyclic Blasting Loading Using the Ultrasonic Test

Figure 14

Nephograms of absolute changes of ultrasonic wave velocity. (a) First blasting, (b) second blasting, (c) third blasting, and (d) fourth blasting (unit: m/s).

(a)

(b)

(c)

(d)