A 10 m thick normally consolidated clay layer (γsat = 19.5 kN/m³, Cc = 0.2, e₀ = 0.95) lies below 3 m of sand (γ = 18 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 95 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
Consolidation settlement worksheet with answers
An 8 m thick layer of normally consolidated clay (Cc = 0.3, e₀ = 1.1) has an effective vertical stress of 110 kPa at its mid-depth. A wide fill raises the vertical stress in the clay by 45 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
A 2.5 m thick overconsolidated clay layer has Cc = 0.4, Cr = 0.06 and e₀ = 1.15. At its mid-depth the effective vertical stress is 85 kPa and the preconsolidation pressure is 145 kPa. A new building adds 180 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 7.5 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.06 and e₀ = 1.15. At its mid-depth the effective vertical stress is 85 kPa and the overconsolidation ratio is OCR = 2. A new building adds 200 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A clay layer 5 m thick has a coefficient of consolidation cv = 0.8 m²/year. It lies on impervious rock, with sand above it, so water drains out only at the top. For 50% average consolidation the time factor is Tv = 0.197. How many years t does the 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 6 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?
Answer key
- 1. S = 292.3 mm
- 2. S = 170.2 mm
- 3. S = 138 mm
- 4. S = 297.8 mm
- 5. t = 6.156 years
- 6. t = 184.7 days
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