1. Consolidation I (CH11)

2. 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)

3. Consolidation Physics From Coduto 1998 (text)

4. Hydrostatic Pore Pressure, u h z Ground surface Soil,  “hydrostatic pore water pressure at A” hphp

5. Excess Pore Pressure, u e Pore pressure generated in excess of hydrostatic due to an applied load. u e is temporary

6. Loading Conditions DENSE Soil densifies due to the change in structure (e ) (water squeezes out of the voids) LOOSE shear

7. 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!

8. Drainage rate = fn (k) Consolidation = time - dependent Loading Conditions Units?

9. Consolidation Physics From Coduto 1998 (text)

10. Consolidation Physics From Coduto 1998 (text)

11. Important Conclusion Consolidation involves a gradual transfer of stress from the pore water (u e ) to the soil particles (  ’).

12. Important Conclusion Deformation occurs only if particles experience a change in effective stress.

13. Lab Testing Consolidation test to assess the compressibility characteristics of clays.

14. Lab Testing Board…

15. Field vs. Lab From Coduto 1998 (text)

16. Consolidation Curve - LAB e  ’ (log scale) p’p’ eoeo crcr c yield

17. Example