Assessment of the Excavation Damaged Zones in the Surrounding Rock of an Underground Powerhouse under High In Situ Stress Using an Acoustic Velocity Detecting Method

<div>The high stress phenomena in the underground powerhouse: (a) the irregular lamps cake core, (b) rock mass splitting and spalling occurring at the 2nd-layer drainage gallery, and (c) roof collapse induced by rock burst in No. 2 tailrace tunnel in the underground powerhouse.</div>

Advances in Civil Engineering

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Figure 7

Figure 7: Assessment of the Excavation Damaged Zones in the Surrounding Rock of an Underground Powerhouse under High In Situ Stress Using an Acoustic Velocity Detecting Method 

Figure 7 | Assessment of the Excavation Damaged Zones in the Surrounding Rock of an Underground Powerhouse under High In Situ Stress Using an Acoustic Velocity Detecting Method 