Analytical Chem Soil HW Solutions 60

Analytical Chem Soil HW Solutions 60 - Reading Beds, ' v...

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60 Q4.7 Solution Calculate the initial and final stresses at the top and bottom of each layer: Level, m above SD σ v , kPa u initial, kPa ' v initial, kPa u final, kPa ' v final, kPa Δσ ' v , kPa 105 0 0 0 0 0 0 98 126 0 126 0 126 0 94 210 40 170 40 170 0 84 420 95 325 0 420 +95 70 714 235 479 200 514 +35 i) Initial settlement is due to compression of the Thanet Sands, which will occur very quickly owing to their relatively high permeability and stiffness. E' 0 = ' v / ε v v = ρ /x Therefore settlement = ' v .x/E' 0 For the Thanet Sands, ' v (average) = (95 kPa + 35 kPa)/2 = 65 kPa = 65 kPa × 14 m ÷ 200 MPa = 4.6 mm ii) Ultimate settlement is due to compression of the Thanet Sands plus consolidation of the Woolwich & Reading Beds (now known as the Lambeth Group). For the Woolwich &
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Unformatted text preview: Reading Beds, ' v (average) = (95 kPa)/2 = 47.5 kPa = 47.5 kPa 10 m 40 MPa = 11.875 mm Total ultimate settlement = 4.6 mm + 11.9 mm = 16.5 mm (iii) Calculate the time factor T = c v .t/d 2 after t = 18 months: The Woolwich & Reading Beds have two-way drainage, so drainage path length d = 10 m 2 = 5 m. Hence T = 4 m 2 /year 1.5 year 52 m 2 = 0.24 4.18, = / ult = 0.58 Hence the settlement after 18 months = 4.55 mm (Thanet Sands) + (0.58 11.875 mm) (Woolwich & Reading Beds) = 11.4 mm...
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