Cone Penetration test-method for calculating Soil bearing capacity

[angle30]

Greetings,
I have received results of Cone penetration test, and observing the notes, I saw a formula that was unclear to me (see link).
Reading through geotechincal literature, I was not able to find this formula shown on the photo(geotechnical engineering is not my area).
On the paper, soil parameters are not listed, only:
1.Depth of penetration,
2.Number of blows
3.Soil bearing capacity (apparently calculated via this formula?)



where:
A=0.001cm2
M=8kg
Depth measurment interval= 0.1m
P= dead weight of instrument, 13.8/15.4/17kg for penetration depth of 1/2/3m respectively.

I am wondering how can Soil bearing capacity be obtained from the parameters in the equation, and what is E here, since its not written in the legend?
Thank you in advance.

 

[oldestguy]

Sounds like magic to me.

From what I have heard some manufacturers claim their penetrometer, when run be their method, gives results comparable to the standard penetration test.

Now converting cone results to bearing capacity is something like converting SPT to bearing capacity. Most any engineer that has been around test boring rigs and sees the many variables there knows the STP is only an indicator of soil conditions maybe, to some extent, but to blindly take those results to a number for a structural engineer to design by is obviously an indication of inexperience.

There even was a drilling firm that would go so far as to show on their boring logs a number for bearing capacity, tied to the blow count only. Boy that was stretching it and placing their neck in the noose.

I hope you get the hint. That hangmans gallows is out there.

 

[oldestguy]

Hey, old guys don't type well. STP is for the car engine. SPT is the standard penetration test.

 

[angle30]

Thanks boys for the answers!

Oldestguy, youre right that everything sounds like a hokus-pokus thing. I am not in the position to point out probable errors, I just have to figure out these variables, which seems to be mission impossible (I have asked for additional information on their methods).
"E" in the equation is probably Energy, since a colleague mentioned the same sheet was sent to the firm that does electrical work for their calculations. Any opinions?
How is energy calculated in CPT?

 

[oldestguy]

Energy calcs for SPT? Well, when one wants to come up with some other weight or relate to a different impact method. Generally no calcs. It might be some want to see the difference in end pressure, if there is such a thing.

 

[moe333]

There are some pretty common bearing capacity equations using CPT data, I have not seen the one you show and would not use it. You can find the common ones through google. try Peter Robertsons web site (Greg Drilling). He has a lot of downloadable resources for CPT.