1.2. Consolidated-drained test (CD test)

Try these first

1. 1.

   What does σ3 represent in triaxial tests?

   Hint

   Think about the pressure exerted on the soil.

2. 2.

   What is the main purpose of a Consolidated-Drained test?

   Hint

   Consider how soil behaves when water can escape.

3. 3.

   What is the primary purpose of the Consolidated-Drained test?

   • To determine shear strength parameters
   • To measure soil moisture
   • To assess soil color

   Hint

   Think about the properties engineers need for design.

4. 4.

   True or False: The Mohr-Coulomb failure envelope only applies to saturated soils.

   • True
   • False

   Hint

   Consider other soil conditions outside saturation.

5. 5.

   A soil sample yields a cohesion of 5 kPa and an angle of internal friction of 30 degrees during a CD test. Calculate the shear strength of the soil when the normal stress is 20 kPa.

   Hint

   Remember to convert the angle from degrees to use in the tangent function.

6. 6.

   An engineer needs to design a wall in clay known to have a failure envelope of c = 8 kPa and φ = 25 degrees. What factors should the engineer consider if the wall is to be built below groundwater level?

   Hint

   Think about what happens to pressures when water is present.