Consolidation I CH11

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Consolidation I(CH11)
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Consolidation
How can s increase?
1. Water level decreases
2. A load is induced (we will consider fills)
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Consolidation Physics
From Coduto 1998 (text)
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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
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Loading Conditions
LR Loading rate?
DR Drainage rate? fn (k)
Water drains out, volume change, e
DRAINED
Water carries load, no volume change, e ct.
UNDRAINED
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Loading Conditions
Drainage rate fn (k)
Units?
Consolidation time - dependent
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Consolidation Physics
From Coduto 1998 (text)
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Consolidation Physics
From Coduto 1998 (text)
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Important Conclusion
Consolidation involves a gradual transfer of
stress from the pore water (ue) to the soil
particles (s).
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Important Conclusion
Deformation occurs only if particles experience a
change in effective stress.
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Lab Testing
Consolidation test
to assess the compressibility characteristics
of clays.
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Lab Testing
Board
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Field vs. Lab
From Coduto 1998 (text)
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Consolidation Curve - LAB
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Example
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Example