Soil Consolidation

What is the primary purpose of a one-dimensional consolidation test (oedometer test)?

• To measure the shear strength of soil

• To estimate the amount of settlement and time of consolidation

• To determine the permeability of granular soils

• To assess the compaction characteristics of soil

Which of the following parameters CANNOT be determined from a consolidation test?

• Coefficient of consolidation

• Compression index

• Angle of internal friction

• Preconsolidation pressure

In the consolidation test, why is the load doubled with each increment?

• To accelerate the test process

• To simulate real-world stress conditions

• To maintain a logarithmic stress scale for analysis

• To prevent excessive deformation of the specimen

What does the coefficient of consolidation (Cv) represent?

• The rate at which water flows through soil

• The rate at which soil undergoes compression under load

• The ratio of volume change to effective stress

• The maximum stress a soil has experienced in the past

In the Casagrande method, which point on the time-settlement curve is used to determine the coefficient of consolidation (Cv)?

• 30% consolidation

• 50% consolidation

• 70% consolidation

• 90% consolidation

Given the following data from a consolidation test: 

   - t₉₀ = 25 min 

   - H = 10 mm (drainage path length) 

   - Time factor (Tv) for 90% consolidation = 0.848 

 

   Calculate the coefficient of consolidation (Cv) in m²/year.

• 0.12 m²/year

• 0.14 m²/year

• 0.16 m²/year

• 0.18 m²/year

A consolidation test gives the following data: 

   - Initial void ratio (e₀) = 1.20 

   - Final void ratio (e) = 0.95 

   - Applied stress increase (Δσ) = 100 kPa 

 

   What is the coefficient of volume compressibility (mᵥ)?

• 0.0012 kPa⁻¹

• 0.0025 kPa⁻¹

• 0.0035 kPa⁻¹

• 0.0050 kPa⁻¹

In a consolidation test, if the time for 50% consolidation (t₅₀) is 9 min and the specimen’s drainage path length (H) is 12 mm, what is the coefficient of consolidation (Cv) using the Casagrande method? (Tv for 50% consolidation = 0.197)

• 0.052 m²/year

• 0.105 m²/year

• 0.170 m²/year

• 0.420 m²/year

A clay layer has a thickness of 4 m and is subjected to a load increase. If Cv = 0.5 m²/year, how long will it take for 90% consolidation to occur? (Tv for 90% consolidation = 0.848)

• 1.5 years

• 2.7 years

• 4.3 years

• 6.8years

If the preconsolidation pressure (σ’c) of a soil is 150 kPa and the current effective stress is 100 kPa, the soil is:

• Normally consolidated

• Over consolidated

• Under consolidated

• Heavily compacted