Soil Strength (CH13)

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Soil Strength(CH13)
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Strength
Greatest stress a material can sustain
Concrete strength?
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Soil Strength
SHEAR
Soil fails in shear
Earth slopes
Foundations
Retaining Walls
Tunnels
Pavements
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Shear Strength
Failure definition
Loose (or NC) vs. Dense (or OC)

• g curves depend on the soil and the testing
  conditions.
• We must simulate field loading in the lab.

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Shear Strength
Mohr Coulomb Failure Criterion
Concrete strength?
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Hydrostatic Pore Pressure, uh
Soil , g
z
hydrostatic pore water pressure at A
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Excess Pore Pressure, ue
Pore pressure generated in excess of hydrostatic
due to an applied load.
ue is temporary
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Loading Conditions
shear
DENSE
LOOSE
Soil densifies due to the change in structure (e
) (water squeezes out of the voids)
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Loading Conditions
LR Loading rate?
shear
DR Drainage rate? fn (k)
Water drains out, volume change, e
DRAINED
Water carries load, no volume change, e ct.
UNDRAINED