A 5.5 m thick layer of normally consolidated clay (Cc = 0.25, e₀ = 1.4) has an effective vertical stress of 90 kPa at its mid-depth. A wide fill raises the vertical stress in the clay by 100 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
A 6 m thick normally consolidated clay layer (γsat = 19.5 kN/m³, Cc = 0.3, e₀ = 1.05) lies below 5.5 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.
A 4 m thick overconsolidated clay layer has Cc = 0.35, Cr = 0.04 and e₀ = 1.1. At its mid-depth the effective vertical stress is 85 kPa and the overconsolidation ratio is OCR = 2. A new building adds 120 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 2 m thick overconsolidated clay layer has Cc = 0.2, Cr = 0.03 and e₀ = 1.1. At its mid-depth the effective vertical stress is 45 kPa and the overconsolidation ratio is OCR = 3. A new building adds 120 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A clay layer 8.5 m thick has a coefficient of consolidation cv = 2 m²/year. It lies between two sand layers, so water drains out at the top and the bottom. For 90% average consolidation the time factor is Tv = 0.848. How many years t does the layer take to reach 90% consolidation?
A clay layer 9.5 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 70% average consolidation the time factor is Tv = 0.403. How many years t does the layer take to reach 70% consolidation?
Answer key
- 1. S = 185.9 mm
- 2. S = 199.6 mm
- 3. S = 77.14 mm
- 4. S = 30.23 mm
- 5. t = 7.659 years
- 6. t = 7.577 years
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