5.2 - Shear strength in soils and rocks

Question 1

Define shear strength in soils (where do they derive their strength?)

Answer 1

Shear strength is the maximum shear stress that can be sustained by a soil mass before failure.

Question 2

Explain the Mohr Coulomb failure envelope and criterion.

Answer 2

• Under the line (Possible or stable)
• On the line (Impossible)
• Above the line (failure)

Question 3

Explain the impact of pore pressure on the maximum shear stress.

Question 4

Sources of shear strength (soil)

Answer 4

• Cohesion: a measure of the forces that cement particles of soils.
• Frictional resistance: a measure of the shear strength of soils due to friction.