9.4.4. Distinguishing stresses

Try these first

1. 1.

   What is the formula for effective stress?

   Hint

   Remember what each term represents.

2. 2.

   What happens to effective stress when pore water pressure increases?

   Hint

   Consider the definition of effective stress.

3. 3.

   What is effective stress defined as?

   • Total Stress + Pore Water Pressure
   • Total Stress - Pore Water Pressure
   • Pore Water Pressure - Total Stress

   Hint

   There’s a formula for this!

4. 4.

   True or False: A decrease in pore water pressure will always result in increased effective stress.

   • True
   • False

   Hint

   Think about how water impacts soil weight.

5. 5.

   A soil layer has a density of 2 T/m³ and a thickness of 5m. Calculate the total stress and effective stress if the pore water pressure at the bottom is 6 T/m².

   Hint

   Use the formulas for total stress and then effective stress.

6. 6.

   Analyze a scenario where the groundwater table in a site rises suddenly. Describe its potential impacts on soil stability and effective stress.

   Hint

   Think about how even small fluctuations in water table can affect soil structure.