Page 59 - Engineering Rock Mass Classification_ Tunnelling, Foundations and Landslides

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TABLE 5.5 Recommendations of Singh et al. (1995) on Support Pre

Terzaghi’s classification Cla

Category Rock condition Rock load Cate- Rock con
(1) factor (H)p gory
I (2) (3) (5)
II (4)
III Hard and intact 0 Hard and
IV I
Hard stratified 0 to 0.5 B Hard strat
V or schistose II schistose

VI Massive, moderately 0 to 0.25 B III Massive, m
jointed jointed
0.25 B to 0.35 IV
Moderately blocky, (B þ Ht) Moderate
seamy, and seamy, ve
jointed 0.35 to 1.1 V
(B þ Ht) Very bloc
Very blocky and shattered
seamy, shattered 1.1 (B þ Ht) VI thin shear
arched fault

Completely crushed Complete
but chemically intact but chem
unaltered
thick shea
fault zone