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GD TEST prove, indagini e monitoraggi per la geoingegneria

NCB Cone Indenter Test

(National Coal Board - England)


The instrument is designed to determine the hardness of rock by measuring its resistance to indentation by a hardened tungsten carbide cone.

Is-m-w = D/P (average of 9 indentations)

UCS = xK (MPa)

Where:
D = nominal deflection of steel trip (in mm) representing a force of
· 40N for medimum rock (Is)
· 110N for hard rock (Im)
· 12N for weak rock (Iw)

P = penetration of specimen by cone

K = experimental constant
· 24.8 for medimum rock
· 35.8 for hard rock
· 16.5 for weak rock

 NCB Cone Indenter Apparatus
Indenter numbers and machine performance
Trend of the TBM tool wear vs. Cone indenter index


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