Dear Prof David / SOil model community,
I am performing coupled consolidation analysis for deep excavation in clay using HP clay model in Plaxis 3D. Performing the undrained analysis, the model works well. When I used consolidation or fully coupled analysis it gives convergence error while it works successfully for other plaxis models ( e.g. HSS). I am using interface element with the plate element which is being used as a wall. If I remove the interface element or make the interface element as permeable then the model with HP clay subroutinel runs successfully (plate is permeable). How can I overcome this convergence problem although i further refined the mesh near the wall?
Hi Muhammad, please check this: https://web.natur.cuni.cz/uhigug/masin/plaxumat/node11.html. Maybe the following will help: “When used with interface elements, proper interface parameters must be input in the “Interface” Tab sheet under “Material models” window. Particularly, as some tensile stress is allowed for in the soil through the parameter $ p_t$, the tensile stress should be allowed for also in the interface by increasing the cohesion value (e.g., 10 kPa). Convergence problems may also be caused by high interface stiffness. In the case PLAXIS keeps on iterating although the global error is below the tolerated value, or does not increase the step size although the number of iterations is below the “desired minimum”, problem is the most likely in interfaces.”