Consolidation settlement worksheet with answers

Free printable Consolidation settlement worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
Δσ = 30 kPasandclayCc​ = 0.25e0​ = 0.8σ′0​ = 80 kPa6.5 mwater table

A 6.5 m thick layer of normally consolidated clay (Cc = 0.25, e₀ = 0.8) has an effective vertical stress of 80 kPa at its mid-depth. A wide fill raises the vertical stress in the clay by 30 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.

H = 6.5 mCc = 0.25e0 = 0.8σ′0 = 80 kPaΔσ = 30 kPa
S = mm
2.Easy
Δσ = 75 kPasandclayCc​ = 0.3e0​ = 1.25σ′0​ = 45 kPa5.5 mwater table

A 5.5 m thick layer of normally consolidated clay (Cc = 0.3, e₀ = 1.25) has an effective vertical stress of 45 kPa at its mid-depth. A wide fill raises the vertical stress in 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.

H = 5.5 mCc = 0.3e0 = 1.25σ′0 = 45 kPaΔσ = 75 kPa
S = mm
3.Medium
Δσ = 110 kPasandclayCc​ = 0.5, Cr​ = 0.05e0​ = 1.1σ′0​ = 55 kPaσ′p​ = 95 kPa4 mwater table

A 4 m thick overconsolidated clay layer has Cc = 0.5, Cr = 0.05 and e₀ = 1.1. At its mid-depth the effective vertical stress is 55 kPa and the preconsolidation pressure is 95 kPa. A new building adds 110 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.

H = 4 mCc = 0.5Cr = 0.05e0 = 1.1σ′0 = 55 kPaσ′p = 95 kPaΔσ = 110 kPa
S = mm
4.Medium
Δσ = 90 kPasandclayCc​ = 0.5, Cr​ = 0.03e0​ = 0.85σ′0​ = 110 kPaOCR = 24.5 mwater table

A 4.5 m thick overconsolidated clay layer has Cc = 0.5, Cr = 0.03 and e₀ = 0.85. At its mid-depth the effective vertical stress is 110 kPa and the overconsolidation ratio is OCR = 2. A new building adds 90 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.

H = 4.5 mCc = 0.5Cr = 0.03e0 = 0.85σ′0 = 110 kPaOCR = 2Δσ = 90 kPa
S = mm
5.Hard
sandclayH = 5 m5 mimpervious rockwater table

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 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?

hlab = 25 mmtlab = 10 minH = 5 mfield: single drainage
t = days
6.Hard
sandclayH = 10 mcv​ = 1 m²/year10 msandwater table

A clay layer 10 m thick has a coefficient of consolidation cv = 1 m²/year. It lies between two sand layers, so water drains out at the top and the bottom. For 60% average consolidation the time factor is Tv = 0.287. How many years t does the layer take to reach 60% consolidation?

H = 10 mcv = 1 m²/yearU = 60%Tv = 0.287double drainage
t = years

Answer key

  1. 1. S = 124.9 mm
  2. 2. S = 312.4 mm
  3. 3. S = 250.9 mm
  4. 4. S = 18.95 mm
  5. 5. t = 1111 days
  6. 6. t = 7.175 years

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