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Name: ____________________ Date: ____________
1.Easy
An 8 m thick normally consolidated clay layer (γsat = 19 kN/m³, Cc = 0.25, e₀ = 0.75) lies below 2.5 m of sand (γ = 17.5 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 = 2.5 m, γ = 17.5 kN/m³clay: H = 8 m, γsat = 19 kN/m³γw = 9.81 kN/m³Cc = 0.25e0 = 0.75Δσ = 35 kPa
S = mm
2.Easy
A 3 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.15, e₀ = 1.1) lies below 5 m of sand (γ = 17.5 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 110 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 m, γ = 17.5 kN/m³clay: H = 3 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.15e0 = 1.1Δσ = 110 kPa
S = mm
3.Medium
A 2 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.02 and e₀ = 0.95. At its mid-depth the effective vertical stress is 110 kPa and the preconsolidation pressure is 190 kPa. A new building adds 220 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
An 8 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.02 and e₀ = 1.2. At its mid-depth the effective vertical stress is 95 kPa and the overconsolidation ratio is OCR = 3. A new building adds 150 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 7 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 19 mm thick, drained at the top and bottom, reaches 50% consolidation in 4 min. In the field the same clay forms a layer 4.5 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?