1.4. Uniform excess pore water pressure with depth

Try these first

1. 1.

   What is pore water pressure?

   Hint

   Think about what happens in soil when it's saturated.

2. 2.

   What does one-dimensional consolidation theory assume about soil layers?

   Hint

   What do these terms mean in relation to soil characteristics?

3. 3.

   What assumption is made about the coefficient of permeability in one-dimensional consolidation?

   • Varies with depth
   • Constant
   • Varies with time

   Hint

   Recall the assumptions about soil behavior.

4. 4.

   True or False: All soil layers are assumed to be compressible in the one-dimensional consolidation theory.

   • True
   • False

   Hint

   Consider what 'compressible' means.

5. 5.

   A soil layer 10 m deep has a permeability of 1x10^-4 m/s. Calculate how long it would take for the excess pore water pressure to decrease by 50% if drainage occurs from both ends.

   Hint

   Consider the factors influencing discharge rate and use appropriate equations.

6. 6.

   Given a soil element experiences an increase in vertical stress from 100 kPa to 200 kPa, with a coefficient of volume compressibility of 0.005 m²/kN, calculate the volume change of a 1 m³ soil element.

   Hint

   Remember to convert stresses to compatible units.