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Name: ____________________ Date: ____________
1.Easy
A 10 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.15, e₀ = 0.65) lies below 6 m of sand (γ = 18.5 kN/m³). The water table is at the top of the clay; use γw = 9.81 kN/m³. A wide fill raises the vertical stress throughout the clay by 135 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
sand: Hs = 6 m, γ = 18.5 kN/m³clay: H = 10 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.15e0 = 0.65Δσ = 135 kPa
S = mm
2.Easy
A 6.5 m thick layer of normally consolidated clay (Cc = 0.4, e₀ = 0.9) has an effective vertical stress of 140 kPa at its mid-depth. A wide fill raises the vertical stress in the clay by 50 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
H = 6.5 mCc = 0.4e0 = 0.9σ′0 = 140 kPaΔσ = 50 kPa
S = mm
3.Medium
A 3 m thick overconsolidated clay layer has Cc = 0.4, Cr = 0.03 and e₀ = 0.9. At its mid-depth the effective vertical stress is 100 kPa and the preconsolidation pressure is 220 kPa. A new building adds 270 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 4.5 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.05 and e₀ = 0.6. At its mid-depth the effective vertical stress is 105 kPa and the preconsolidation pressure is 195 kPa. A new building adds 240 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
In a laboratory oedometer test, a clay specimen 20 mm thick, drained at the top and bottom, reaches 50% consolidation in 10 min. In the field the same clay forms a layer 9 m thick. It lies on impervious rock, with sand above it, so water drains out only at the top. How many days t does the field layer take to reach 50% consolidation?
In a laboratory oedometer test, a clay specimen 25 mm thick, drained at the top and bottom, reaches 50% consolidation in 12 min. In the field the same clay forms a layer 8 m thick. It lies between two sand layers, so water drains out at the top and the bottom. How many days t does the field layer take to reach 50% consolidation?