Environmental Engineering Reference
In-Depth Information
PLATE 5.28 (
Color Plate 5.28
follows page 396.)
MIGMATITE (Rio-Santos Highway, Rio de Janeiro, Brazil).
Blocks
will have the characteristics of intact rock. As the degree of decomposition
increases, the significance of the discontinuities decreases, but even in highly decomposed
rock and residual soils, relict fractures can represent potential failure surfaces.
In general, experience shows that the response of a rock mass during tunneling opera-
tions will be governed by intact properties, and the rock may be considered as competent
if its joints are tight, their spacing is about 1 m or more, and the rock is fresh (Hartmann,
1966). In slopes and excavations, however, any size block of fresh rock within an exposed
wall can fail if the bounding planes of the block incline downward and out of the slope.
Engineering Properties Given in
Chapter 3
Hardness
The range in ”total hardness” for common rock types is given in
Figure 3.1.
Rock rippa-
bility as related to seismic velocities is given in
Table 3.7.
Permeability
Typical permeability coefficients for rock and soil formations are given in
Table 3.12.
Rupture Strength
The relationship between ”consistency” and uniaxial compressive strength is given in
Figure
3.39.
Correlation among unconfined compressive strength, density, and Schmidt hardness is
given in
Figure 3.40.
Common strength properties of fresh intact rock are given in
Table 5.19.
Shear-strength parameters of residual soil and weathered rock are given in
Table 3.35.
Deformation
Typical values for the elastic constants are listed in
Table 3.25.
Deformation characteristics
of intact rock in uniaxial compression to failure are listed in
Table 3.24;
relationships
