Soil Properties from RQD?

[4n6]

I am designing a short (6' and less) Reinforced Earth wall in a cut situation. The reinforced fill will be crushed stone to minimize the reinforceing embedment length.

The retained material is a poor quality limestone, with an RQD (Rock Quality Designation) of 8 to 25. A Texas Cone Penetrometer advanced 0" at 100 blows.

Does anyone have any reccomendations as to what phi angle I should apply to the retained material? Would a value of 36 to 38 be appropriate?

Thanks in advance.

 

[Focht3]

[Focht3 shouts from atop his soap box]

Since you used the Texas cone, this project must have TexDOT money! No self-respecting geotechnical engineer uses it - but we must do the @#%&?! test on TexDOT jobs!! [calmer] You have my condolences. [aggravated again] Why do "they" insist on using this damn tool in rock?! It's stupid!

[Focht3 descends from his soap box]

Where is your site? (I'm in San Antonio.) How does the aggregate classify (per TexDOT)? How angular? What is the clay fraction and/or PI?

My initial reaction is to use only 32 or 33 degrees - the wall is short. Do you have an encroachment problem?

 

[BigH]

Focht3: I love your comments!!! I am narrowing you down!! My sister is in San Antonio - working for A&M extension program services. Just got her Ph.D. Proud of her for that. See my question, please, on minimum unit weights for fills in "earthworks". Best to you.

 

[kmerl]

You indicate that you are in poor quality limestone, I would agree with Focht3, a lower value is more conservative. If it is rock then the materials are retaining themselves, did you do any coring, this could give much better qualties to the internal phi angle of the rock.

ITS LIMESTONE, be more worried ABOUT sinkholes!!!! USe a more conservative phi angle.