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
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
Check your Boundary conditions.
RE: Pile loading test
Blocked Y - on the bottom
Blocked X - right side
RE: Pile loading test
has your problem been solved?
RE: Pile loading test
RE: Pile loading test
I have some experience in penetration pile .... in soil with Abaqus.
RE: Pile loading test
I want to model loading test of pile. So loaded it till failure (in this case I guess in soil).
Thank you in advance
RE: Pile loading test
Find the Attached(Inp file) which is analysis of pile driving. Hope, solve your problem.
RE: Pile loading test
I hope it will solve my problem. Where can I find this Inp file?
Thank You
RE: Pile loading test
Please find the attached.
RE: Pile loading test
RE: Pile loading test
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
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
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
RE: Pile loading test
Also, how have you modelled your interaction. Are you using effective stress analysis?
RE: Pile loading test
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
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
RE: Pile loading test
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
Regards,
Aliasger