CBR Value.
CBR Value.
(OP)
I am working on a particular job that has poor ground conditions mainly consisting of aluvial deposits and silty clay. The specification for the access road states that a CBR Value at formation level is to be atleast 3%.
Using a Penetrologger, I have calculated that the bearing capacity of the clay at formation level is on average 1500kN/m^2. Unfortunately I could not find a direct conversion from MPa or kN/m^2 to CBR. Could anyone point me in the right direction if there is one?
Road is to take 300 Tonnes.
I am new this game, still studying at University. But could somebody also explain why when we CFA piled a particular area, 1 of the piles could not obtain any friction and the clay turned liquid?
Regards
Using a Penetrologger, I have calculated that the bearing capacity of the clay at formation level is on average 1500kN/m^2. Unfortunately I could not find a direct conversion from MPa or kN/m^2 to CBR. Could anyone point me in the right direction if there is one?
Road is to take 300 Tonnes.
I am new this game, still studying at University. But could somebody also explain why when we CFA piled a particular area, 1 of the piles could not obtain any friction and the clay turned liquid?
Regards





RE: CBR Value.
f-d
¡papá gordo ain't no madre flaca!
RE: CBR Value.
Also, a CBR of 3 is very low...I would expect that of relatively soft clay or silt.
To give you perspective, a clean sand will have a CBR of 10 to 20. A clayey sand will typically have a CBR in the range of 20 to 30. A graded aggregate base will typically have a CBR in the range of 70+
RE: CBR Value.
We used to design for CBR 3 soils too, depending on the project. Now that I'm working for the Department of Transportation, we'd just undercut it 2 ft and bring in something for better long-term performance.
People just don't like maintenance of their freeways.
f-d
¡papá gordo ain't no madre flaca!
RE: CBR Value.
Currently with the tests I have done I am getting a reading of 0.6MPa in one particular area of 100x7m according to my conversion, 0.6MPa is the same as 600kN/m^2? does this not seen extremely high?
RE: CBR Value.
If you want a shallow foundation system, you determine the bearing capacity of the soil and design the foundation accordingly. If the bearing capacity of the soil is too low to get a reasonable foundation size, then you must either lower the foundation to a stronger stratum, use a mat foundation, or go to a deep foundation system.