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Name: ____________________ Date: ____________
1.Easy
An 8 m thick normally consolidated clay layer (γsat = 19.5 kN/m³, Cc = 0.3, e₀ = 1.1) lies below 3.5 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 80 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 = 17.5 kN/m³clay: H = 8 m, γsat = 19.5 kN/m³γw = 9.81 kN/m³Cc = 0.3e0 = 1.1Δσ = 80 kPa
S = mm
2.Easy
An 8 m thick normally consolidated clay layer (γsat = 18 kN/m³, Cc = 0.3, e₀ = 1.05) lies below 5.5 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 80 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 = 17.5 kN/m³clay: H = 8 m, γsat = 18 kN/m³γw = 9.81 kN/m³Cc = 0.3e0 = 1.05Δσ = 80 kPa
S = mm
3.Medium
A 3 m thick overconsolidated clay layer has Cc = 0.25, Cr = 0.03 and e₀ = 0.95. At its mid-depth the effective vertical stress is 80 kPa and the overconsolidation ratio is OCR = 2. A new building adds 130 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
An 8 m thick overconsolidated clay layer has Cc = 0.2, Cr = 0.02 and e₀ = 1.2. At its mid-depth the effective vertical stress is 70 kPa and the preconsolidation pressure is 190 kPa. A new building adds 90 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A clay layer 10 m thick has a coefficient of consolidation cv = 0.5 m²/year. It lies between two sand layers, so water drains out at the top and the bottom. For 80% average consolidation the time factor is Tv = 0.567. How many years t does the layer take to reach 80% consolidation?
In a laboratory oedometer test, a clay specimen 25 mm thick, drained at the top and bottom, reaches 50% consolidation in 4 min. In the field the same clay forms a layer 4 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?