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Name: ____________________ Date: ____________
1.Easy
A 4 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.4, e₀ = 0.8) lies below 5.5 m of sand (γ = 17 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 105 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 = 17 kN/m³clay: H = 4 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.4e0 = 0.8Δσ = 105 kPa
S = mm
2.Easy
A 4 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.3, e₀ = 1.25) lies below 3.5 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 50 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
sand: Hs = 3.5 m, γ = 18.5 kN/m³clay: H = 4 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.3e0 = 1.25Δσ = 50 kPa
S = mm
3.Medium
A 4 m thick overconsolidated clay layer has Cc = 0.5, Cr = 0.03 and e₀ = 1.1. At its mid-depth the effective vertical stress is 45 kPa and the preconsolidation pressure is 125 kPa. A new building adds 150 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 6 m thick overconsolidated clay layer has Cc = 0.4, Cr = 0.05 and e₀ = 1. At its mid-depth the effective vertical stress is 110 kPa and the preconsolidation pressure is 180 kPa. A new building adds 25 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 6 min. In the field the same clay forms a layer 5.5 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?
A clay layer 2.5 m thick has a coefficient of consolidation cv = 3 m²/year. It lies on impervious rock, with sand above it, so water drains out only at the top. For 70% average consolidation the time factor is Tv = 0.403. How many years t does the layer take to reach 70% consolidation?