Increment of Soil Bearing Capacity???

[TekEngr]

Any one can tell me any thumb rule to find the approximate increment value in bearing capacity of soil (for initial design) after proper compaction and adding the selected 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 selected granular material what incremental soil bearing capacity could be taken for my initial design of raft footing and if soil type is clay??

 

[GeoPaveTraffic]

There is no rule of thumb. Each case needs to be calculated based on the specific factors that are involved.

Mike Lambert

 

[Okiryu]

The effect of bearing capacity improvement will depend on the size of the loaded area. For example, for your case, if you have a footing of 30 cm wide, it may be some increament in the bearing capacity, otherwise I would not consider any improvements. Your raft is definitively bigger than that, so I would be more concern on settlements rather than bearing capacity.