1.7. Effective Stress Mohr’s Circles

Try these first

1. 1.

   What is the main purpose of a triaxial test?

   Hint

   Think about the type of test and how it's conducted.

2. 2.

   Define effective stress.

   Hint

   Consider the impact of water on soil strength.

3. 3.

   What does the Mohr-Coulomb failure envelope represent?

   • Soil color
   • Shear strength of soils
   • Soil density

   Hint

   Look at how soil strength is typically analyzed.

4. 4.

   True or False: The effective stress increases as pore water pressure increases in saturated soils.

   • True
   • False

   Hint

   Consider how water pressure interacts with soil stress.

5. 5.

   Given a pore water pressure of 30 kPa and a total stress of 80 kPa, calculate the effective stress. Discuss what this means for the soil's behavior.

   Hint

   Remember the effective stress formula!

6. 6.

   Consider a saturated clay with varying pore water pressures under one-dimensional loading. Illustrate using Mohr’s Circle how increased pore pressure could alter the failure envelope.

   Hint

   Visual aid of Mohr's Circle will help understand the interactions!