Learning Forum

[VinayN]

Hi all !

I want to model an retaining wall with backfill but I can't seem to model it properly. Errors and warnings include

1)Solver pivot warnings or errors have been encountered during the solution.  This is usually a result of an ill conditioned matrix possibly due to unreasonable material properties, an under constrained model, or contact related issues.  Check results carefully.

2)Not enough constraints appear to be applied to prevent rigid body motion.  This may lead to solution warnings or errors.  Check results carefully.

Soil properties entered are random. Is this the mistake ?

Elastic mat support on base and to ends at toe and heel of wall as highlighted with stiffness of 2.6 N/mm3.

I've tried different contact conditions between soil and wall but nothing seems to work.

Thank you.

[VinayN]

with the same values I added fixed line supports at lower edge of heel and toe. Analysis was done but soil was collapsing on it self i.e. friction contact between soil and wall produced no stress in wall. Also I changed the type of mesh and size of soil body.

[peteroznewman]

You modeled a vertical column of soil with no support on the right side. Of course it is going to collapse. 

You need to model a lot larger body of soil and have a soil boundary on the right side far from the retaining wall foot and a soil boundary on the bottom, a long way below the retaining wall foot, and a soil boundary a long way to the left side way past the foot. These boundaries can be fixed because they are so far removed from the wall that they will have no effect on what happens near the wall.

Yes, it is wrong to insert random numbers into material properties. Get some valid inputs.

[VinayN]

Thank you for the suggestion. Hope I can get things right.