Consolidation I (CH11)
Consolidation Process by which an in ’ causes a deformation of a soil mass by reducing its e (water seeps out of the voids). How can ’ increase? 1. Water level decreases 2. A load is induced (we will consider fills)
Consolidation Physics From Coduto 1998 (text)
Hydrostatic Pore Pressure, u h z Ground surface Soil, “hydrostatic pore water pressure at A” hphp
Excess Pore Pressure, u e Pore pressure generated in excess of hydrostatic due to an applied load. u e is temporary
Loading Conditions DENSE Soil densifies due to the change in structure (e ) (water squeezes out of the voids) LOOSE shear
LR: Loading rate? DR: Drainage rate? = fn (k) Water drains out, volume change, e Water carries load, no volume change, e = ct. DRAINED UNDRAINED Loading Conditions u e is generated!
Drainage rate = fn (k) Consolidation = time - dependent Loading Conditions Units?
Consolidation Physics From Coduto 1998 (text)
Consolidation Physics From Coduto 1998 (text)
Important Conclusion Consolidation involves a gradual transfer of stress from the pore water (u e ) to the soil particles ( ’).
Important Conclusion Deformation occurs only if particles experience a change in effective stress.
Lab Testing Consolidation test to assess the compressibility characteristics of clays.
Lab Testing Board…
Field vs. Lab From Coduto 1998 (text)
Consolidation Curve - LAB e ’ (log scale) p’p’ eoeo crcr c yield
Example