CU Triaxial and CD Triaxial - Effective Parameters

[nbr1]

I am trying to determine effective stress parameters for a foundation soil and have been
provided the following information (which is the only information available at present): The material is a slightly silty clay (CL); having a PI ~20 and moisture content of 20%.

Lab Test Phi (degrees) Cohesion (psf)
R (CU) 15.8 860
S (CD) 30.7 0

Do these values appear reasonable? What would one select for effective strength parameters if
this were the only information available?

 

[GeoPaveTraffic]

Results appear reasonable. Though I would never design without seeing the actual test results and studying the p-q plots to know that the results are in fact reasonable.

As for what you use for design, it depends on what you are designing. You may need Q (UU) test results, you may need to use a combination of R & S results or just the S results may be suffient. All depends on what you are designing and the type of loading(s) it will see.

Mike Lambert