PLAXIS 2D - ANALYSE SPEED

Dear Arun,

Great to hear that you are starting to work with PLAXIS.

A calculation requires time and that time can be related to different parameters.

First of all, the type of analyses determines how complex the computation will be. For instance a dynamic analysis is more demanding to a plastic as more degrees of freedom are included in the analysis.

Then, the number of elements included in the finite element model can increase significantly the calculation time. That is why it is important to have an efficient mesh generated, meaning have fine elements where needed and large element far away on model boundaries.

Another aspect is the amount of plasticity generated. The mode plasticity generated the longer it takes the model to converge.

The latter depends on the constitutive model used and how well it can "describe" the soil response.

Note that we cannot give advise on material parameters as this is the job of the geotechnical engineer that has all the data at hand (field and/or laboratory) as well as experience.

A general recommendation, I would not try to "force" or "trick" a model to calculate with a green checkmark, as there might a real failure that occurs which is the reason why you run this analysis. In this case, in order to find out what the mechanism for failure is, and so possibly determining the cause, these Output plots should be inspected:

• deformed mesh
• total displacements (shaded plot)
• incremental displacement (shaded plot and/or arrows)
• total deviatoric strain (shaded plot)
• incremental deviatoric strains (shaded plot)
• plastic points
• when applicable: excess pore pressures (pexcess)

A combination of these plots will usually give insight into what is happening.

Dear Arun,

Great to hear that you are starting to work with PLAXIS.

A calculation requires time and that time can be related to different parameters.

First of all, the type of analyses determines how complex the computation will be. For instance a dynamic analysis is more demanding to a plastic as more degrees of freedom are included in the analysis.

Then, the number of elements included in the finite element model can increase significantly the calculation time. That is why it is important to have an efficient mesh generated, meaning have fine elements where needed and large element far away on model boundaries.

Another aspect is the amount of plasticity generated. The mode plasticity generated the longer it takes the model to converge.

The latter depends on the constitutive model used and how well it can "describe" the soil response.

Note that we cannot give advise on material parameters as this is the job of the geotechnical engineer that has all the data at hand (field and/or laboratory) as well as experience.

A general recommendation, I would not try to "force" or "trick" a model to calculate with a green checkmark, as there might a real failure that occurs which is the reason why you run this analysis. In this case, in order to find out what the mechanism for failure is, and so possibly determining the cause, these Output plots should be inspected:

• deformed mesh
• total displacements (shaded plot)
• incremental displacement (shaded plot and/or arrows)
• total deviatoric strain (shaded plot)
• incremental deviatoric strains (shaded plot)
• plastic points
• when applicable: excess pore pressures (pexcess)

A combination of these plots will usually give insight into what is happening.