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Name: ____________________ Date: ____________
1.Easy
An 8 m thick normally consolidated clay layer (γsat = 18.5 kN/m³, Cc = 0.45, e₀ = 1.3) lies below 2.5 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 90 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 = 18.5 kN/m³clay: H = 8 m, γsat = 18.5 kN/m³γw = 9.81 kN/m³Cc = 0.45e0 = 1.3Δσ = 90 kPa
S = mm
2.Easy
A 4 m thick normally consolidated clay layer (γsat = 19.5 kN/m³, Cc = 0.35, e₀ = 1.3) lies below 3 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 25 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 m, γ = 17.5 kN/m³clay: H = 4 m, γsat = 19.5 kN/m³γw = 9.81 kN/m³Cc = 0.35e0 = 1.3Δσ = 25 kPa
S = mm
3.Medium
A 5 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.04 and e₀ = 1.2. At its mid-depth the effective vertical stress is 80 kPa and the preconsolidation pressure is 110 kPa. A new building adds 110 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 6 m thick overconsolidated clay layer has Cc = 0.25, Cr = 0.05 and e₀ = 0.95. At its mid-depth the effective vertical stress is 70 kPa and the preconsolidation pressure is 160 kPa. A new building adds 30 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A clay layer 2.5 m thick has a coefficient of consolidation cv = 0.8 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?
A clay layer 9.5 m thick has a coefficient of consolidation cv = 2.5 m²/year. It lies between two sand layers, so water drains out at the top and the bottom. For 60% average consolidation the time factor is Tv = 0.287. How many years t does the layer take to reach 60% consolidation?