×
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

Pile loading test

Pile loading test

Pile loading test

(OP)
Hello,

 I am tring to calculate loading test of small scale pile in ABAQUS CAE. Results which I get are rediculus. I am afraid it can be connected with invalid definition of geostatic state of stress (gravity g=10 m/s). I checked the units but there is ok with them.

Axisymmetric model dimensions:

Part-1 : 0.5m x 1m (horizontal x vertical) with 'hole ' for pile 0.035m x 0.45m (horizontal x vertical)

Part-2 : 0.035m x 0.45m (horizontal x vertical)

My dry sand is modelled with Mohr-Coulomn

density 1450kg/m^3

Young modulus E=40e6 Pa

Poisson ratio ni=0.3

friction angle fi=33deg

dilatancy angle psi=10deg

cohesion c=100 Pa

Pile properties (Elastic):

density 2400kg/m^3

Young modulus E=20e9 Pa

Poisson ratio ni=0.3

 

I define initial state of stress( EALL - set which is whole model soil+pile) by

*initial conditions type=stress, geostatic
EALL, -14500, -1, 0, 0, 0.5

When I check Frame-1vertical  stress is like I defined and no vertical dispalcement occures

Frame-2 vertical stress changed (caused by the weight of pile) and significant values of displacement occured (also S12 and CSHEAR1 are not equal to 0)

Interaction between soil-pile (created in Initial step and propagated to all): tangential - penalty - friction coefficient 0.35

Two steps:

Step-1: Static, gravity load (whole model)

Step-2: Static, gravity load(propagated tron previous step) + displacement on the pile top (d=0,05m)

 

Problem is that the concentration of vertical stress is in soil under pile tip not as I expected in the pile head.

Does anybody  know what can caused this kind of behaviour? and what is more important how to fix it?

Thank You in advance

Regards,

Anna  

RE: Pile loading test

Hi,
Check your Boundary conditions.  

RE: Pile loading test

(OP)
XSymmetry - left side (axis)
Blocked Y - on the bottom
Blocked X - right side
 

RE: Pile loading test

Hi Anna,
has your problem been solved?  

RE: Pile loading test

(OP)
Unfortunately not :l

RE: Pile loading test

I read your problem which you explain above, but I couldn't understand well that, what's your aim of this model. If it's possible, please let me know your purpose of this simulation. I'd like to help you and solve your problem.
I have some experience in penetration pile .... in soil with Abaqus.  

RE: Pile loading test

Hi Anna,
Find the Attached(Inp file) which is analysis of pile driving. Hope, solve your problem.  

RE: Pile loading test

(OP)
Hello,
I hope it will solve my problem. Where can I find this Inp file?
Thank You

RE: Pile loading test

(OP)
Thank You one more time I am tring to analyze your file. Hope will find my mistake.

RE: Pile loading test

(OP)
I analyze Your input file but unfortunately, I didn't find solution for my problem :(

Would You be that kind and send me a cae file with simulation of loading test for any soil and pile parameters. I think My mistake is hidden in contact definition but I am not sure.

Thank You in advance
Anna

RE: Pile loading test

Hi,
I'm sorry about that, but I haven't any other cae file which be close to your problem. By the way, what's your definition of soil/pile interaction?
I think you should define contact interaction based on slide line formulation. Define surface to surface interaction and choose tangential behavior and then select penalty or Lagrange multiplier for friction formulation.  

RE: Pile loading test

Hi again,

I read your explanation of your simulation once again, and I think you should change the type of your analysis step from static to soils. It might be solve your problem to get more acceptable results. Try it. Good luck :)

RE: Pile loading test

(OP)
I checked for soil step but it doesn't change anything :/

RE: Pile loading test

You need to remove the pile from the geostatic stress. Just apply geostatic stress to the soil block.

Also, how have you modelled your interaction. Are you using effective stress analysis?

RE: Pile loading test

(OP)
You mean initial geostatic condition just to soil (nothing define for pile), right?

Step-1: Static, gravity load (whole model or also just soil?)

Step-2: Static, gravity load(propagated tron previous step) + displacement on the pile top (d=0,05m)

I'm trying to model dry case so there is no difference between effective and total.

Interaction: soil-pile
- surfaces: Master: pile shaft and tip, Slave: soil which is directly in contact with shaft and tip of pile

- created in Initial step and propagated to all: tangential -> penalty -> friction coefficient 0.35
 

RE: Pile loading test

Yes, geostatic stress is for the soil only. Do not include the pile.

Gravity is for whole model so that's correct.

Do you not have normal contact behaviour (hard contact and penalty constraint enforcement method)?

What value of poisson's ratio are you using?

 

RE: Pile loading test

Sorry read your earlier post about poisson's ratio.   

RE: Pile loading test

Hi Anna,

I have a problem which is close to your problem roughly. would you please let me know has your problem (stress concentration) been solved or not. If yes,I was wondering if you could help me.

Thanks,
Geotech2011

RE: Pile loading test

Hi Geotech 2011, I went through your input file as I would like to simulate pile driving. Is it possible for you to please explain the steps that you have used so I can understand them and apply to my model?

Regards,

Aliasger

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