Environmental Engineering Reference
In-Depth Information
Rock Quality Indices
Sonic wave velocities
from seismic direct surveys (see
Section 2.3.2)
are used in evaluating
rock mass quality and dynamic properties.
Rock quality designation
may be considered as an index property (see
Section 2.4.5).
Rippability
Rippability refers to the ease of excavation by construction equipment. Since it is related
to rock quality in terms of hardness and fracture density, which may be measured
by seismic refraction surveys (see Section 2.3.2), correlations have been made between
rippability and seismic P wave velocities as given in Table 3.7. If the material is not rip-
pable by a particular piece of equipment, then jack-hammering and blasting are
required.
3.2.3
Soils
General
The basic and index properties of soils are generally considered to include volume-weight
and moisture-density relationships, relative density, gradation, plasticity, and organic
content.
TABLE 3.7
Rock Rippability as Related to Seismic p-Wave Velocities (Courtesy of Caterpillar Tractor Co.)
0
1
2
3
4
Velocity (m/s
×
1000)
Velocity (ft/s
×
1000)
012 34 5678 9 0 1 2 3 4 5
Topsoil
Clay
Glacial till
Igneous rocks
Granite
Basalt
Trap rock
Sedimentary rocks
Shale
Sandstone
Siltstone
Claystone
Conglomerate
Breccia
Caliche
Limestone
Metamorphic rocks
Schist
Slate
Minerals and ores
Coal
Iron ore
Rippable
Marginal
Non rippable
Rippability based on caterpillar D9 with mounted hydraulic No.9 ripper
