Research Article
Experimental Investigation of the Anomalously Low Friction Phenomena in Blocky Rock Systems
Figure 7
Spectral density of vertical displacement with different disturbance energies: (a) 50 mJ; (b) 150 mJ; (c) 250 mJ; (d) 300 mJ.
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| (b) | 
| (c) | 
| (d) |