For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.
Name: ____________________ Date: ____________
1.Easy
An 8 m thick normally consolidated clay layer (γsat = 17.5 kN/m³, Cc = 0.35, e₀ = 1.05) lies below 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 145 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
sand: Hs = 5 m, γ = 17.5 kN/m³clay: H = 8 m, γsat = 17.5 kN/m³γw = 9.81 kN/m³Cc = 0.35e0 = 1.05Δσ = 145 kPa
S = mm
2.Easy
A 6 m thick layer of normally consolidated clay (Cc = 0.25, e₀ = 0.65) has an effective vertical stress of 115 kPa at its mid-depth. A wide fill raises the vertical stress in the clay by 70 kPa. Treat the layer as one sublayer with the stresses at its mid-depth. Find the primary consolidation settlement S in mm.
H = 6 mCc = 0.25e0 = 0.65σ′0 = 115 kPaΔσ = 70 kPa
S = mm
3.Medium
An 8 m thick overconsolidated clay layer has Cc = 0.35, Cr = 0.04 and e₀ = 1.15. At its mid-depth the effective vertical stress is 60 kPa and the preconsolidation pressure is 160 kPa. A new building adds 150 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 = 0.45, Cr = 0.04 and e₀ = 0.7. At its mid-depth the effective vertical stress is 55 kPa and the overconsolidation ratio is OCR = 2.5. A new building adds 110 kPa of vertical stress at mid-depth. Find the primary consolidation settlement S in mm.
A clay layer 3 m thick has a coefficient of consolidation cv = 2.5 m²/year. It lies between two sand layers, so water drains out at the top and the bottom. For 50% average consolidation the time factor is Tv = 0.197. How many years t does the layer take to reach 50% consolidation?
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 10 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?