Environmental Engineering Reference
In-Depth Information
TABLE 2.9
Typical Compression-Wave Velocities in Soils and Rocks
Velocity (m/s) 1000
1
2
3
4
5
6
7
(ft/s
×
1000)
5
10
15
20
25
Material
Soils (above GWL)
Topsoil, leached, porous
Loess
Alluvium: soft or loose
Colluvium: soft or loose
Alluvium: firm to medium coarse
Colluvium: firm to medium coarse
Clays
Glacial till (compact)
Residual
Residual (saprolite)
Water
Sedimentary Rocks
Sandstone (soft to hard)
Shale (soft to hard)
Limestone
Soft
Hard
Crystalline
Anhydrite, gypsum, salt
Metamorphic Rocks
Slate
Schist
Gneiss
Marble
Quartzite
Igneous Rocks
Weathered
Fractured
Granite
Granodiorite
Quartz monzonite
Gabbro
Diabase
Basalt
}
Also gneiss
Notes:
(1) Velocities given are for dry soil conditions. As the percent saturation increases so do velocities: there-
fore, a velocity change may indicate the water table rather than a material change. (2) The wide range
of velocities given for rocks reflect the degree of weathering and fracturing: sound, massive rock yields
the highest velocities.
of the hydrophone is amplified and passed to a recorder, which transcribes each spark
event to sensitized paper, directly resulting in a pictorial section beneath the water surface.
Equipment in use is generally of two types:
“Subbottom Profilers,” “Boomers,” and “Bubble Pulsers” provide penetration
depths below the water-body floor in the range of 50 to 100 m. In general,
Subbottom Profilers and Boomers provide higher resolution and Bubble Pulsers
provide deeper penetration. They are often used together.
●
