1.6. Unloading and Expansion Curves

Try these first

1. 1.

   Define void ratio.

   Hint

   What does it tell us about the soil?

2. 2.

   What happens to a soil sample when effective stress increases?

   Hint

   Think about the effects of pressure.

3. 3.

   What does the virgin compression curve indicate?

   • Low compression behavior
   • High compression behavior
   • No compression

   Hint

   Think of how soils behave when subjected to considerable stress.

4. 4.

   True or False: When soil is unloaded, it always returns to its original state.

   • True
   • False

   Hint

   Consider what happens during unloading processes.

5. 5.

   A soil sample is subjected to a series of load increments for 24 hours each, eventually showing a permanent strain of 5%. If unloaded, estimate how much it would recover based on the expansion curve.

   Hint

   Analyze the changes post-unloading to trace back to recovery.

6. 6.

   Propose a scenario where rapid unloading would affect the soil structure and discuss potential design implications.

   Hint

   Using the properties of permanent strain and effective stress, what could this lead to?