GLOSSARIES - Geotechnical Earthquake Engineering - page 515

Key A designed compacted fill placed in a trench excavated in earth material beneath the toe of a
proposed fill slope.
Keyway An excavated trench into competent earth material beneath the toe of a proposed fill slope.
Lift During compaction operations, a layer of soil that is dumped by the construction equipment and
then subsequently compacted as structural fill.
Necking A reduction in cross-sectional area of a drilled shaft as a result of the inward movement of
the adjacent soils.
Owner Any person, agency, firm, or corporation having a legal or equitable interest in a given real

property.
Permanent Erosion Control Devices Improvements which remain throughout the life of the
development. They include terrace drains, down-drains, slope landscaping, channels, and storm drains.
Permit An official document or certificate issued by the building official authorizing performance
of a specified activity.
Pier A deep foundation system, similar to a cast-in-place pile, that consists of columnlike reinforced
concrete members. Piers are often of large enough diameter to enable down-hole inspection. Piers are
also commonly referred to as drilled shafts, bored piles, or drilled caissons.
Pile A deep foundation system, consisting of relatively long, slender, columnlike members that are
often driven into the ground.

Batter Pile A pile driven in at an angle inclined to the vertical to provide higher resistance to lat-

eral loads.
Combination End-Bearing and Friction Pile A pile that derives its capacity from combined
end-bearing resistance developed at the pile tip and frictional and/or adhesion resistance on the pile
perimeter.
End-Bearing Pile A pile whose support capacity is derived principally from the resistance of the
foundation material on which the pile tip rests.
Friction Pile A pile whose support capacity is derived principally from the resistance of the soil
friction and/or adhesion mobilized along the side of the embedded pile.
Pozzolan For concrete mix design, a siliceous or siliceous and aluminous material which will
chemically react with calcium hydroxide within the cement paste to form compounds having cemen-
titious properties.
Precise Grading Permit A permit that is issued on the basis of approved plans which show the
precise structure location, finish elevations, and all on-site improvements.
Relative Compaction The degree of compaction (expressed as a percentage) defined as the field
dry density divided by the laboratory maximum dry density.
Ripping or Rippability The characteristic of rock or dense and rocky soils that can be excavated
without blasting. Ripping is accomplished by using equipment such as a Caterpillar ripper, ripper-scar-
ifiers, tractor-ripper, or impact ripper. Ripper performance has been correlated with the seismic wave
velocity of the soil or rock (see Caterpillar Performance Handbook 1997).
Riprap Rocks that are generally less than 1800 kg (2 tons) in mass that are placed on the ground sur-
face, on slopes or at the toe of slopes, or on top of structures to prevent erosion by wave action or strong
currents.
Running Soil or Running Ground In tunneling or trench excavations, a granular material that
tends to flow or “run” into the excavation.
Sand Boil Also known as sand blow, sand volcano, or silt volcano. The ejection of sand at
ground surface, usually forming a cone shape, caused by underground piping. Sand boils can also
form at ground surface when there has been liquefaction of underlying soil during an earthquake.
Shear Key Similar to a buttress; however, generally constructed by excavating a slot within a natural
slope in order to stabilize the upper portion of the slope without grading encroachment into the lower por-
tion of the slope. A shear key is also often used to increase the factor of safety of an ancient landslide.