Geotextiles in Embankment Dams - Association of State Dam Safety ...

GlossaryFilter (Protective Filter) (ASTM D 653, 2005): A layer or combination of layersof pervious materials designed and installed in such a manner as to provide drainage,yet prevent the movement of soil particles due to flowing water.Filter Cake (Frobel, 1987): Soil stratification developed upstream of a geotextileby separating the suspended soil from water as the mixture attempts to pass througha soil fabric system.Filter cake: A thin layer of soil particles that accumulate at the face of a filterwhen flowing water carries eroding particles to the face. The filter cake forms wheneroded particles embed themselves into the voids of the filter.Filtration (Frobel, 1987): The process of retaining soils while allowing the passageof water (fluids).Fines (ASTM D 653, 2005): Portion of a soil finer than a No. 200 (75μm) U.S.standard sieve.First filling: Usually refers to the initial filling of a reservoir or conduit.Fish Mouth (Frobel, 1987): A half-cylindrical or half-conical opening formed byan edge wrinkle in a geomembrane seam. A seam defect due to the unequal lengthsof the mating surfaces.Flood (FEMA, 2004): A temporary rise in water surface elevation resulting ininundation of acres not normally covered by water. Hypothetical floods may beexpressed in terms of average probability of exceedance per year, such as 1-percentchanceflood, or expressed as a fraction of the probable maximum flood or otherreference flood.Force-elongation curve (ASTM D-4439, 2004): n – in a tensile test, a graphicalrepresentation of the relationship between the magnitude of the externally appliedforce and the change in length of the specimen in the direction of the applied force –synonym for “stress-strain curve”.Foundation (FEMA, 2004): The portion of a valley floor that underlies andsupports an embankment dam.Friction Angle (Frobel, 1987): An angle, the tangent of which is equal to the ratioof the friction force per unit area to the normal stress between two materials.Frost heave (ASTM D 653, 2002): The raising of a structure due to theaccumulation of ice in the underlying soil or rock.163