9.4.2. Impacts of water table changes

Try these first

1. 1.

   What is effective stress?

   Hint

   Think about how water impacts weight.

2. 2.

   What happens to effective stress when the water table falls?

   Hint

   Consider the effects of decreased water pressure.

3. 3.

   What happens to effective stress when the water table rises?

   • It increases
   • It decreases
   • It remains constant

   Hint

   Think about how water pressure impacts the load.

4. 4.

   True or False: Effective stress is the difference between total stress and pore water pressure.

   • True
   • False

   Hint

   Revisit the basic definition from the session.

5. 5.

   A soil layer has a total stress of 100kPa and a pore water pressure of 40kPa. Calculate the effective stress and discuss what happens if the water table rises 5m, increasing pore pressure by 10kPa.

   Hint

   Use σ' = σ - u and factor in the changes.

6. 6.

   Consider a construction site near a river in monsoon seasons. Outline potential risks due to changes in the water table and devise strategies to mitigate these hazards.

   Hint

   Think about practical ways to ensure stability and safety.