Slope stability

Question 1

Limit equilibrium assumptions (4)

Answer 1

• Soil mass moves as a rigid block with movement only taking place on the failure surface itself.
• Assume a failure mechanism: shape & location of failure surface
• Asume plane strain conditions
• Assume uniform localisation of shear stresses

Question 2

Shear strength parameters used for short term stability?

Answer 2

Low permeability —> no flow of water —> undrained conditions —> use total stress analysis —> Cu (undrained shear strength

Question 3

Shear strength parameters for long term stability?

Answer 3

pwp in equilibrium —> drained conditions —> effective stress analysis —> c’, phi’

Question 4

What is phi’ governed by?

Answer 4

Density
Confining pressure
Grain size dist
Boundary conds

Question 5

What is residual state?

Answer 5

When a shear plane is formed in a clay, the adjacent particles tend to align parallel to the plane

Question 6

Slope stability measures?

Answer 6

Modify slope geometry
Drainage
Retaining structures