All of the equations I have come across for settlement calculations differentiate between cohesive and cohesionless materials.

How do you calculate the settlement of organic silts?  (ML/ OLs)?  It is all weight of hammer blow count material (lake bottom), and has low cohesive values.

Do you just assume cohesive material, and calculcate primary and secondary settlement?

THanks

Step 1: Is it really an OL (i.e., did you follow ASTM D-2487 with the wet- and oven-dry-prep liquid limits and return a classification of "organic silt")?
Step 2:  Do an odometer test with time readings that extend beyond the "end of primary" (i.e., so you actually have values of C-alpha).
Step 3:  Interpret the e log p for Pp, Cc and Cr
Step 4:  Do a settlement calculation for total consolidation settlement and a compression calculation for secondary settlement (this depends on a time-frame assessment for the project (i.e., how much compression will occur during the 20 years after construction).

In the absence of consolidation data, values for C-alpha are available from natural moisture content data, but first make sure that you actually have an OL or OH!

f-d

¡papá gordo ain't no madre flaca!