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Hydraulic conductivity (K) is a property of soil that describes the ease with which water can move through pore spaces. It depends on the permeability of the material (pores, compaction) and on the degree of saturation. Saturated hydraulic conductivity, K sat, describes water movement through saturated media. Where hydraulic conductivity has ...
Table of saturated hydraulic conductivity (K) values found in nature. a table showing ranges of values of hydraulic conductivity and permeability for various geological materials. Values are for typical fresh groundwater conditions — using standard values of viscosity and specific gravity for water at 20 °C and 1 atm.
Unconsolidated sand and gravel Well sorted gravel: Well sorted sand or sand and gravel Very fine sand, silt, loess, loam: Unconsolidated clay and organic Peat: Layered clay: Unweathered clay Consolidated rocks Highly fractured rocks Oil reservoir rocks Fresh sandstone: Fresh limestone, dolomite: Fresh granite: k (cm 2) 0.001 0.0001 10 −5: 10 ...
The particle size distribution of a soil, its texture, determines many of the properties of that soil, in particular hydraulic conductivity and water potential, [1] but the mineralogy of those particles can strongly modify those properties. The mineralogy of the finest soil particles, clay, is especially important. [2]
According to the Unified Soil Classification System, a #4 sieve (4 openings per inch) having 4.75 mm opening size separates sand from gravel and a #200 sieve with an 0.075 mm opening separates sand from silt and clay. According to the British standard, 0.063 mm is the boundary between sand and silt, and 2 mm is the boundary between sand and gravel.
Silt is mineralogically like sand but with its higher specific surface area it is more chemically and physically active than sand. But it is the clay content of soil, with its very high specific surface area and generally large number of negative charges, that gives a soil its high retention capacity for water and nutrients. [11]
Soil gradation is an important aspect of soil mechanics and geotechnical engineering because it is an indicator of other engineering properties such as compressibility, shear strength, and hydraulic conductivity. In a design, the gradation of the in situ (on site) soil often controls the design and ground water drainage of the site.
This adsorbed layer is not free to move under gravity. It causes an obstruction to the flow of water in the pores and hence reduces the permeability of soils. According to Casagrande , it may be taken as the void ratio occupied by absorbed water and the permeability may be roughly assumed to be proportional to the square of the net voids ratio ...