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 = 90 kPasandγ = 19 kN/m³6 mclayγsat​ = 19 kN/m³Cc​ = 0.15, e0​ = 17 mwater tableX

A 7 m thick normally consolidated clay layer (γsat = 19 kN/m³, Cc = 0.15, e₀ = 1) lies below 6 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 90 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.

sand: Hs = 6 m, γ = 19 kN/m³clay: H = 7 m, γsat = 19 kN/m³γw = 9.81 kN/m³Cc = 0.15e0 = 1Δσ = 90 kPa
S = mm
2.Easy
Δσ = 110 kPasandγ = 17.5 kN/m³4.5 mclayγsat​ = 17.5 kN/m³Cc​ = 0.15, e0​ = 0.859 mwater tableX

A 9 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.15, e₀ = 0.85) lies below 4.5 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 110 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.

sand: Hs = 4.5 m, γ = 17.5 kN/m³clay: H = 9 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.15e0 = 0.85Δσ = 110 kPa
S = mm
3.Medium
Δσ = 160 kPasandclayCc​ = 0.35, Cr​ = 0.03e0​ = 0.8σ′0​ = 120 kPaσ′p​ = 210 kPa3.5 mwater table

A 3.5 m thick overconsolidated clay layer has Cc = 0.35, Cr = 0.03 and e₀ = 0.8. At its mid-depth the effective vertical stress is 120 kPa and the preconsolidation pressure is 210 kPa. A new building adds 160 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.

H = 3.5 mCc = 0.35Cr = 0.03e0 = 0.8σ′0 = 120 kPaσ′p = 210 kPaΔσ = 160 kPa
S = mm
4.Medium
Δσ = 160 kPasandclayCc​ = 0.3, Cr​ = 0.02e0​ = 1.1σ′0​ = 105 kPaOCR = 24.5 mwater table

A 4.5 m thick overconsolidated clay layer has Cc = 0.3, Cr = 0.02 and e₀ = 1.1. At its mid-depth the effective vertical stress is 105 kPa and the overconsolidation ratio is OCR = 2. A new building adds 160 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.

H = 4.5 mCc = 0.3Cr = 0.02e0 = 1.1σ′0 = 105 kPaOCR = 2Δσ = 160 kPa
S = mm
5.Hard
sandclayH = 4 m4 mimpervious rockwater table

In a laboratory oedometer test, a clay specimen 20 mm thick, drained at the top and bottom, reaches 50% consolidation in 12 min. In the field the same clay forms a layer 4 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 = 20 mmtlab = 12 minH = 4 mfield: single drainage
t = days
6.Hard
sandclayH = 9.5 m9.5 msandwater table

In a laboratory oedometer test, a clay specimen 19 mm thick, drained at the top and bottom, reaches 50% consolidation in 8 min. In the field the same clay forms a layer 9.5 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?

hlab = 19 mmtlab = 8 minH = 9.5 mfield: double drainage
t = days

Answer key

  1. 1. S = 109.4 mm
  2. 2. S = 214.9 mm
  3. 3. S = 99.2 mm
  4. 4. S = 77.85 mm
  5. 5. t = 1333 days
  6. 6. t = 1389 days

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