Geotextiles in Embankment Dams - Association of State Dam Safety ...
Geotextiles in Embankment Dams - Association of State Dam Safety ...
Geotextiles in Embankment Dams - Association of State Dam Safety ...
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GlossaryCritical Hydraulic Gradient - Hydraulic gradient at which the <strong>in</strong>tergranular pressure<strong>in</strong> a mass <strong>of</strong> cohesionless soil is reduced to zero by the upward flow <strong>of</strong> water.Hydraulic transmissivity (ASTM D-4439, 2004): (L 2 T -1 ), n – for a geotextile orrelated product, the volumetric flow rate <strong>of</strong> water per unit width <strong>of</strong> specimen perunit gradient <strong>in</strong> a direction parallel to the plane <strong>of</strong> the specimen.Hydrostatic Pressure, u 0 (FL -2 ) (ASTM D 653, 2005): A state <strong>of</strong> stress <strong>in</strong> whichall the pr<strong>in</strong>cipal stresses are equal (and there is no shear stress), as <strong>in</strong> a liquid at rest;the product <strong>of</strong> the unit weight <strong>of</strong> the liquid and the difference <strong>in</strong> elevation betweenthe given po<strong>in</strong>t and the free water elevation.Excess hydrostatic pressure (hydrostatic excess pressure), ū, u (FL -2 ): The pressurethat exists <strong>in</strong> pore water <strong>in</strong> excess <strong>of</strong> the hydrostatic pressure.Hydrostatic pressure: The pressure exerted by water at rest.Ice lens: A mass <strong>of</strong> ice formed dur<strong>in</strong>g the construction <strong>of</strong> an embankment dam,when a moist soil is exposed to free<strong>in</strong>g temperatures. In certa<strong>in</strong> types <strong>of</strong> soils (siltsand silty soils) the size <strong>of</strong> the ice mass will <strong>in</strong>crease as it draws unfrozen capillarywater from the adjacent soil. A void <strong>in</strong> the soil may rema<strong>in</strong> after the ice lens melts.Impervious: Not permeable; not allow<strong>in</strong>g liquid to pass through.Index test (ASTM D-4439, 2004): n – a test procedure which may conta<strong>in</strong> a knownbias but which may be used to establish on order for a set <strong>of</strong> specimens with respectto the property <strong>of</strong> <strong>in</strong>terest.Inspection: The review and assessment <strong>of</strong> the operation, ma<strong>in</strong>tenance, andcondition <strong>of</strong> a structure.Inspector: The designated on-site representative responsible for <strong>in</strong>spection andacceptance, approval, or rejection <strong>of</strong> work performed as set forth <strong>in</strong> the contractspecifications. The authorized person charged with the task <strong>of</strong> perform<strong>in</strong>g a physicalexam<strong>in</strong>ation and prepar<strong>in</strong>g documentation for <strong>in</strong>spection <strong>of</strong> the embankment damand appurtenant structures.In-plane flow (ASTM D-4439, 2004): n – fluid flow conf<strong>in</strong>ed to a direction parallelto the plane <strong>of</strong> a geotextile or related product.Internal erosion: A general term used to describe all <strong>of</strong> the various erosionalprocesses where water moves <strong>in</strong>ternally through or adjacent to the soil zones <strong>of</strong>167
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