A 3.5 m thick layer of normally consolidated clay (Cc = 0.35, e₀ = 0.9) has an effective vertical stress of 95 kPa at its mid-depth. A wide fill raises the vertical stress in the clay by 125 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 normally consolidated clay layer (γsat = 19 kN/m³, Cc = 0.15, e₀ = 1) 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 75 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
A 7 m thick overconsolidated clay layer has Cc = 0.45, Cr = 0.03 and e₀ = 0.6. At its mid-depth the effective vertical stress is 95 kPa and the overconsolidation ratio is OCR = 1.5. A new building adds 50 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 3.5 m thick overconsolidated clay layer has Cc = 0.4, Cr = 0.05 and e₀ = 0.8. At its mid-depth the effective vertical stress is 115 kPa and the overconsolidation ratio is OCR = 2. A new building adds 150 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 = 3 m²/year. It lies on impervious rock, with sand above it, so water drains out only at the top. For 90% average consolidation the time factor is Tv = 0.848. How many years t does the layer take to reach 90% consolidation?
In a laboratory oedometer test, a clay specimen 19 mm thick, drained at the top and bottom, reaches 50% consolidation in 5 min. In the field the same clay forms a layer 7.5 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 = 235.1 mm
- 2. S = 116.5 mm
- 3. S = 37.98 mm
- 4. S = 77.11 mm
- 5. t = 1.767 years
- 6. t = 541 days
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