GLOSSARIES - Geotechnical Earthquake Engineering - page 513

Buttress Fill A fill mass, the configuration of which is designed by engineering calculations to stabi-
lize a slope exhibiting adverse geologic features. A buttress is generally specified by minimum key width
and depth and by maximum backcut angle. A buttress normally contains a back drainage system.
Caisson Sometimes a large-diameter pier. Another definition is a large structural chamber utilized to
keep soil and water from entering into a deep excavation or construction area. Caissons may be installed
by being sunk in place or by excavating the bottom of the unit as it slowly sinks to the desired depth.
Cat Slang for Caterpillar grading or construction equipment.
Clearing, Brushing, and Grubbing The removal of vegetation (grass, brush, trees, and similar

plant types) by mechanical means.
Clogging For a geotextile, a decrease in permeability due to soil particles that either have lodged in
the geotextile openings or have built up a restrictive layer on the surface of the geotextile.
Compaction The densification of a fill by mechanical means. Also see Compaction in Glossary 2.
Compaction Equipment Equipment grouped generally into five different types or classifica-
tions: sheepsfoot, vibratory, pneumatic, high-speed tamping foot, and chopper wheels (for municipal
landfill). Combinations of these types are also available.
Compaction Production Production expressed in compacted cubic meters (m 3 ) or compacted
cubic yards (yd 3 ) per hour.
Concrete A mixture of aggregates (sand and gravel) and paste (Portland cement and water). The
paste binds the aggregates together into a rocklike mass as the paste hardens because of the chemical
reactions between the cement and the water.
Contractor A person or company under contract or otherwise retained by the client to perform
demolition, grading, and other site improvements.
Cut-Fill Transition The location in a building pad where on one side the pad has been cut down,
exposing natural or rock material, while on the other side, fill has been placed.
Dam A structure built to impound water or other fluid products such as tailing waste and wastewater
effluent.
Homogeneous Earth Dam An earth dam whose embankment is formed of one soil type with-
out a systematic zoning of fill materials.
Zoned Earth Dam An earth dam embankment zoned by the systematic distribution of soil types
according to their strength and permeability characteristics, usually with a central impervious core and
shells of coarser materials.
Debris All products of clearing, grubbing, demolition, or contaminated soil material that are unsuitable
for reuse as compacted fill and/or any other material so designated by the geotechnical engineer or build-
ing official.
Dewatering The process used to remove water from a construction site, such as pumping from
wells to lower the groundwater table during a foundation excavation.
Dozer Slang for bulldozer construction equipment.
Drainage The removal of surface water from the site. See App. C, Standard Detail No. 9 (Day 1999)
for typical lot drainage specifications.
Drawdown The lowering of the groundwater table that occurs in the vicinity of a well that is in the
process of being pumped.
Earth Material Any rock, natural soil, or fill, or any combination thereof.
Electroosmosis A method of dewatering, applicable for silts and clays, in which an electric field is
established in the soil mass to cause the movement by electroosmotic forces of pore water to well point
cathodes.
Erosion Control Devices (Temporary) Devices which are removable and can rarely be sal-
vaged for subsequent reuse. In most cases they will last no longer than one rainy season. They include
sandbags, gravel bags, plastic sheeting (visqueen), silt fencing, straw bales, and similar items.