×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Side Friction Resistance of Auger Cast Piles in Bedrock

Side Friction Resistance of Auger Cast Piles in Bedrock

Side Friction Resistance of Auger Cast Piles in Bedrock

(OP)
Does anyone have typical values that may be used.  The bedrock I am dealing with is medium hard sandstone and limestone.   

RE: Side Friction Resistance of Auger Cast Piles in Bedrock

The disrupted rock should have DCR around 10 or so, with integral parts only half foot in a column of test cylinder extracted of 5 ft. Then I would look it mainly as gross gravel of the same material.

http://www.finesoftware.eu/geotechnical-software/help/sheeting-design/table-of-ultimate-friction-factors-for-dissimilar-materials/

Concrete in soft disgregated middle strength rock maybe 0.55 to 0.60.  

RE: Side Friction Resistance of Auger Cast Piles in Bedrock

(OP)
I was actually looking more for the strength of the bond between the rock and concrete.  I am assuming that the rock can resist lateral forces and that lateral pressure is not develped against the pile.  Therefore, the method of using lateral pressure x tan (external frictions angle) would not be valid.   

RE: Side Friction Resistance of Auger Cast Piles in Bedrock

Then you have two limits: the shear strength near the altered surface within the rock, and the bond strength from concrete.

Tensile strength in the rock uses to be 10 to 15% percent of compressive atrength, and shear strength is not thought to be very dissimilar. DCR=10 woulg give allowable pressure of contact of around 2 MPa, 12.5% of which is 0.25 MPa, allowable, for shear strength.

For a DCR=10 you can  estimate from correlations c=0.255 MPa coexisting with an angle of inner friction of only 15 deg sexagesimal.

Bond within the concrete in uncheckable area better not to be taken over 1 MPa ultimate, 0.66 MPa allowable.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources