Environmental Engineering Reference
In-Depth Information
TABLE 5.16
General Engineering Properties of Common Rocks
a
Rock Type
Characteristics
Permeability
Deformability
Strength
Igneous
Phanerites
Welded interlocking
Essentially imper-
Very low
Very high
grains, very little pore
meable
spacer
Aphanites
Similar to above, or can
With voids can be
Very low to low
Very high to high
contain voids
highly permeable
Porous
Very high void ratio
Very high
Relatively low
Relatively low
Sedimentary
Sandstones
Voids cement filled.
Low
Low
High
Partial filling of voids by
Very high
Moderate to high
Moderate to low
cement coatings
Shales
a
Depend on degree of
Impermeable
High to low
Low to high
lithification
Can be highly
expansive
Limestone
Pure varieties normally
High through
Low except for
High except for
develop caverns
caverns
cavern arch
cavern arch
Impure varieties
Impermeable
Generally low
Generally high
Dolomite
Seldom develops cavities
Impermeable
Lower than
Higher than
limestone
limestone
Metamorphic
Gneiss
b
Weakly foliated
Essentially
Low
High
impermeable
Strongly foliated
Very low
Moderate normal to
High normal to
foliations. Low
foliations. Low
parallel to foliations
parallel to
foliations
Schist
b
Strongly foliated
Low
As for gneiss
As for gneiss
Phyllite
b
Highly foliated
Low
Weaker than gneiss
Weaker than gneiss
Quartzite
Strongly welded grains
Impermeable
Very low
Very high
Marble
Strongly welded
Impermeable
Very low
Very high
a
Fresh intact condition.
b
Anisotropic fabric.
Rock-Quality Indices (see
Section 2.4.5)
Indices of rock quality are determined from a number of relationships as follows:
1. Bulk density of intact specimens
2. Percent recovery from core borings
3. Rock-quality designation (RQD) from core borings
4. Point-load index (
I
s
) from testing core specimens in the field
5. Field shear-wave velocity (
V
Fs
) for dynamic Young's modulus
6.
Field compression-wave velocity (
V
F
) for rock type and quality
7.
Laboratory compression-wave velocity (
V
L
) on intact specimens to combine
with
V
F
to obtain the velocity index
8.
Laboratory shear-wave velocity (
V
Ls
) to compare with
V
Fs
for rock quality
