Good morning to all,
I have a question about the coefficient OCM(Overburden Compaction Multiplier).
The Ceasar describes it “Common practice has been to reduce it (from its default of 8) to values from 5 to 7,
depending on the degree of compaction of the backfill.
Backfill efficiency can be approximated by the Proctor Number, defined in most soils testbooks. (The Proctor Number is a ratio of unit weights) The standard practice when the Proctor Number is known is to multiply the default value 8 by the Proctor Number. This result should then be used as the compaction multiplier.”

For example, if the OCM = 8, the Proctor Number is 8/8 = 1 (compaction to 100%) while if the OCM = 4, the Proctor Number is 4/8 = 0.5 (compaction to 50%).
But during my stress analysis of buried pipeline by Caesar I've observed that more the OCM approaches 8 more the displacements increase(therefore soil less compact!), instead I expected smaller displacements (therefore soil more compacted)
Which link exists between OCM and the level of soil compaction (Proctor Number)?

How can I consider my soil model compacted during the analysis?
Thanks and Regards.

Anyone can Help me??

There is no answer without seeing all of your data. Can you file a Support Request on Smart Support and send in your job files.

The OCM in CAESAR II only adjusts the transverse stiffness, not the axial stiffness. It is a direct multiplier. You should see the change in the stiffnesses and ultimate loads listed in the buried pipe generator.
Does that explain your observations?

Hello Aleps,

A successful buried pipe installation depends on obtaining the proper soil support for the pipe. The amount of support depends on the level of compaction of the soil. A Target Value is used to evaluate the level of compaction of the soil. Typically, the Target Value is the percent compaction of the soil. To obtain the percent compaction, an in-place density test is compared to a laboratory test that determines the maximum dry density of the soil (e.g. percent standard Proctor). However, the density of gravel-size cohesionless materials used for pipe bedding, embedment, and backfill is difficult to measure in the field and in the laboratory. Materials such as pea gravel, crushed rock, and recycled concrete present unique measurement problems, particularly in pipeline trenches.

Also read this post I've replied recently.

http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=66286&#Post66286