A 6 m thick normally consolidated clay layer (γsat = 19 kN/m³, Cc = 0.35, e₀ = 1.05) lies below 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 25 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 4 m thick layer of normally consolidated clay (Cc = 0.25, e₀ = 0.75) has an effective vertical stress of 130 kPa at its mid-depth. A wide fill raises the vertical stress in 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.
A 7.5 m thick overconsolidated clay layer has Cc = 0.45, Cr = 0.02 and e₀ = 1.1. At its mid-depth the effective vertical stress is 100 kPa and the preconsolidation pressure is 180 kPa. A new building adds 40 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A 5 m thick overconsolidated clay layer has Cc = 0.25, Cr = 0.03 and e₀ = 0.95. At its mid-depth the effective vertical stress is 60 kPa and the preconsolidation pressure is 110 kPa. A new building adds 130 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A clay layer 9.5 m thick has a coefficient of consolidation cv = 1 m²/year. It lies on impervious rock, with sand above it, so water drains out only at the top. 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 3 m thick has a coefficient of consolidation cv = 1.2 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?
Answer key
- 1. S = 82.58 mm
- 2. S = 100.6 mm
- 3. S = 10.44 mm
- 4. S = 172.4 mm
- 5. t = 51.17 years
- 6. t = 6.36 years
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