×
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

Modelling sediment deposition history with Abaqus

Modelling sediment deposition history with Abaqus

Modelling sediment deposition history with Abaqus

(OP)
I am trying to simulate a large-scale sediment deposition in Abaqus Standard to evaluate excess pore pressure evolution.
My starting model is composed by 3 layers, which have to deposit within 3 separate time steps. The model is composed by 4 different iterations: the history begins with de-activating all of the layers, followed by three steps that activate one layer each. The deposition is supposed to be gradual through the duration of the timestep.
The layers are composed by 2 different sediment types.

This is what I did:
- Define the model's geometry (I made a partition of a shell into three rectangles);
- Define the materials properties of the two soil types (Plasticity, Elasticity, Permeability and Density);
- Define the mesh element type within the family "Pore Fluid/Stress";
- Define Steps and Iterations (time periods, ramping the load linearly over the step and activating Nlgeom);
- Define the load (gravity, -9.81);
- Define boundary conditions (fixed lower boundary, X-fixed lateral boundaries, 0 pore pressure at the top of each timesteps to allow vertical deformation);
- Define Predefined Fields (Saturation, Void Ratio, an Initial hydrostatic pore pressure gradient and minimum initial effective stress);

Abaqus is able to simulate the deposition of the first layer, where I can see a vertical displacement and the reduction in void ratio looks reasonable; as soon as the second layer’s deposition starts, it cannot find convergence.
.msg files tell me just that convergence is judged unlikely.

Does anyone have experience with this type of problems and see what am I doing wrong? My feeling is that as the original depositional surface is shifted down by the first stage of consolidation, creating excessive cells distortion at the beginning of the second time step: do you know how can I bypass the problem?
Thanks!

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! Already a Member? Login


Resources

White Paper – Choosing the Right Spring Loaded Connector
In today’s cost-sensitive world, designers are often driven to specify the lowest cost solution for every aspect of their designs to ensure that their solution is competitively priced and their company remains profitable. However, specifying a low-cost, low-quality connector solution can result in premature failure, considerable re-work costs and damage to reputations. Download Now
eBook – Own the Lifecycle: Sustainable Business Transformation
Increasingly, product and services companies are seeking more information and control in the operational lifecycle of their products, including service and use. Better information about the operational lifecycle, and the ability to use that information, requires more than just unstructured data flowing back from products in the field. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close