1.2. Pore Water Pressure

Try these first

1. 1.

   What is pore water pressure?

   Hint

   Think about how water fills spaces in soil.

2. 2.

   What happens to pore water pressure at the water table?

   Hint

   Remember how pressures equalize at that point.

3. 3.

   What is the formula for pore water pressure under hydrostatic conditions?

   Hint

   Think about how pressure varies with water depth.

4. 4.

   Is pore water pressure negative above the water table?

   • True
   • False

   Hint

   Consider how water is held in soil pores.

5. 5.

   A soil layer is saturated and has a unit weight of water of 9.81 kN/m³. If the groundwater level is at 5m, calculate the pore water pressure at a depth of 12m.

   Hint

   Remember to subtract the depth from the groundwater level.

6. 6.

   Describe what happens to pore water pressure when a heavy load is applied to saturated soil and predict how effective stress will change.

   Hint

   Think about how water adjusts to stress changes and how this affects strength.