1.5. Shear Strength Parameters

Try these first

1. 1.

   What does a triaxial test help determine?

   Hint

   Think about the contribution of the test to soil mechanics.

2. 2.

   Name the three types of triaxial tests.

   Hint

   Recall the drainage conditions for each test.

3. 3.

   What are the three categories of triaxial tests?

   • 1. Unconsolidated-Drained
   • Consolidated-Drained
   • Consolidated-Undrained
   • 2. Consolidated-Drained
   • Consolidated-Undrained
   • Unconsolidated-Undrained
   • 3. Consolidated-Undrained
   • Unconsolidated
   • Eroded-Drained

   Hint

   Recall the tests and conditions discussed.

4. 4.

   The effective stress is defined as which of the following: σ' = σ - u?

   • True
   • False

   Hint

   Think about how we calculate effective stress.

5. 5.

   A saturated clay sample is subjected to a consolidated-undrained test, yielding a total stress of 200 kPa with a pore water pressure of 75 kPa. Compute the effective stress and discuss its implications for soil stability.

   Hint

   Remember the effective stress equation.

6. 6.

   If a horizontal Mohr’s circle in an unconsolidated-undrained test demonstrates a horizontal tangent line, explain what this implies about the shear strength under varying confining pressures.

   Hint

   Consider what happens to pore water pressure in saturation.