Civil Engineering Reference
In-Depth Information
Classes of
rock strength
Sliding
surface
along
discontinuity?
Ye s
N o
Joints parallel to face
Closely fractured rock
Pair of intersecting joints
Weak, massive rock
Use discontinuity
shear strength
(Sections 4.2, 4.3)
Use rock mass
shear strength
(Sections 4.4, 4.5)
Figure 4.6
Relationship between geology
and classes of rock strength.
Intact,
weak rock
Rock
masses
Fractured,
strong rock
i
Rough, clean
fracture
Smooth, clean
fracture
Discontinuities
Figure 4.7
Relationships
between shear and
normal stresses on sliding
surface for five different
geological conditions
(Transportation Research
Board, 1996).
Infilled
fracture
Cohesion
Effective normal stress,
