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Name: ____________________ Date: ____________
1.Easy
A 5 m thick normally consolidated clay layer (γsat = 19.5 kN/m³, Cc = 0.2, e₀ = 0.7) lies below 4.5 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 100 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
sand: Hs = 4.5 m, γ = 18.5 kN/m³clay: H = 5 m, γsat = 19.5 kN/m³γw = 9.81 kN/m³Cc = 0.2e0 = 0.7Δσ = 100 kPa
S = mm
2.Easy
A 7 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.6, e₀ = 1.1) lies below 5.5 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 35 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
sand: Hs = 5.5 m, γ = 18.5 kN/m³clay: H = 7 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.6e0 = 1.1Δσ = 35 kPa
S = mm
3.Medium
A 2 m thick overconsolidated clay layer has Cc = 0.45, Cr = 0.04 and e₀ = 0.95. At its mid-depth the effective vertical stress is 70 kPa and the preconsolidation pressure is 120 kPa. A new building adds 190 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 6 m thick overconsolidated clay layer has Cc = 0.2, Cr = 0.05 and e₀ = 0.6. At its mid-depth the effective vertical stress is 70 kPa and the overconsolidation ratio is OCR = 2.5. A new building adds 140 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
In a laboratory oedometer test, a clay specimen 19 mm thick, drained at the top and bottom, reaches 50% consolidation in 12 min. In the field the same clay forms a layer 3.5 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?
In a laboratory oedometer test, a clay specimen 19 mm thick, drained at the top and bottom, reaches 50% consolidation in 8 min. In the field the same clay forms a layer 10 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?