1.3.1. First Part of Effective Stress Principle

Try these first

1. 1.

   What is the formula for total stress at a depth?

   Hint

   Think about the factors influencing stress at a given depth.

2. 2.

   What happens to pore water pressure below the water table?

   Hint

   Remember the hydrostatic condition of water.

3. 3.

   What equation represents total stress in soil at a certain depth?

   • σ = γZ
   • σ' = σ - u
   • u = γ_w h

   Hint

   Remember the basic equation for total stress!

4. 4.

   True or False: The effective stress is directly measurable.

   • True
   • False

   Hint

   Consider how we measure stress in soils.

5. 5.

   Calculate the total stress at a depth of 15 feet with a soil unit weight of 120 lbs/ft³. What would happen if water were to saturate this soil to 10 feet?

   Hint

   Make sure to account for both the weight of the soil and the contribution of the water above.

6. 6.

   Explain how excavation to a depth of 20 feet might impact pore water pressure and total stress in a nearby area.

   Hint

   Consider how soil reacts to sudden removal of load and its effects on water movement.