Analytical Chem Soil HW Solutions 36

Analytical Chem Soil HW Solutions 36 - Q3.6 A well pumping...

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36 We can calculate the unit weight of the soil at a height of 180 mm from the data given for fluidization in upward flow, using the equation derived in the main text Section 3.11 for the critical upward hydraulic gradient, i crit = ( γ w )/ w (main text Equation 3.33) with i crit = 109.9 mm ÷ 120 mm = 0.916 Hence at fluidization, = 1.916 × w For a saturated soil, = w .(G s + v – 1)/(v) (main text Equation 1.11) where v is the specific volume, i.e. the ratio total volume V t volume of solids V s At fluidization, g/gw = 1.916 = (v + 1.65)/v hence 0.916v = 1.65 or v max = 1.8 We can calculate the specific volume of the soil in the densest state, at a sample height of 160 mm, by noting that the total volume V t is given by V t = A.z = V s .(V s /V t ) = V s .v so that v/z = A/V s = constant = v o /z o = 1.8/180 mm = 0.01 mm -1 Hence in the densest state with z = 160 mm, v = v min = 0.01 mm -1 160 mm v min = 1.6 Well pumping test (field measurement of permeability)
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Unformatted text preview: Q3.6 A well pumping test was carried out to determine the bulk permeability of a confined aquifer. The aquifer was overlain by a clay layer 4 m thick, the depth of the aquifer was 20 m, and the initial piezometric level in the aquifer was 2m below ground level. After a period of pumping when steady-state conditions had been reached, the following observations were made. pumped flowrate q = 1.637 litres/second well radius = 0.1 m drawdown just outside well = 2 m drawdown in piezometer at 100m distance from well = 0.2 m Deriving from first principles any equations you need to use, determine the bulk permeability of the aquifer. Would your analysis still apply for a drawdown in the well of 4 m? [University of London 2nd year BEng (Civil Engineering) examination, Queen Mary and Westfield College]...
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This note was uploaded on 12/28/2011 for the course CHM 4302 taught by Professor Stuartchalk during the Fall '11 term at UNF.

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