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Name: ____________________ Date: ____________
1.Easy
A 10 m thick normally consolidated clay layer (γsat = 18.5 kN/m³, Cc = 0.4, e₀ = 1.25) lies below 2.5 m of sand (γ = 19 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 65 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 = 19 kN/m³clay: H = 10 m, γsat = 18.5 kN/m³γw = 9.81 kN/m³Cc = 0.4e0 = 1.25Δσ = 65 kPa
S = mm
2.Easy
A 2.5 m thick layer of normally consolidated clay (Cc = 0.5, e₀ = 0.85) has an effective vertical stress of 130 kPa at its mid-depth. A wide fill raises the vertical stress in 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.
A 2 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.02 and e₀ = 0.65. At its mid-depth the effective vertical stress is 45 kPa and the preconsolidation pressure is 85 kPa. A new building adds 25 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 6.5 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.05 and e₀ = 1.05. At its mid-depth the effective vertical stress is 45 kPa and the preconsolidation pressure is 75 kPa. A new building adds 20 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
In a laboratory oedometer test, a clay specimen 25 mm thick, drained at the top and bottom, reaches 50% consolidation in 10 min. In the field the same clay forms a layer 6.5 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?
A clay layer 2 m thick has a coefficient of consolidation cv = 1.2 m²/year. It lies between two sand layers, so water drains out at the top and the bottom. For 50% average consolidation the time factor is Tv = 0.197. How many years t does the layer take to reach 50% consolidation?