Increment in Soil Bearing Capacity???

[TekEngr]

Any one can tell me any thumb rule to find the aproximate increment value in bearing capacity of soil (for inetial design) after proper compaction and adding the slected granular material??? 
 For example existing soil bearing capacity is 50 KN/m2 if we do compaction in proper way  and add 30 cm layer of slected granular material what incremental soil bearing capacity could be taken for my inetial design of raft footing??

 

[Guastavino]

Since you're asking that question, I would recommend the owner get a Geotechnical engineer on board. I think all that is going to vary based on site conditions, etc. I don't think it's as simple as a rule of thumb. I'm no geotechnical engineer, but I know I wouldn't feel comfortable without talking with one first.

 

[GeoPaveTraffic]

Please don't double post unless you are not getting a response in one thread or another.

There is no rule of thumb. Every case needs to be analyzed based on the specific conditions.

Mike Lambert

 

[MotorCity]

Agree with others above. Rule of thumb is to hire a geotechnical engineer. You may be able to use the presumptive bearing capacities in IBC, however it does not address multiple layers nor compaction. You also have to have some idea of the soil type you are dealing with. Might be a good place to start.