Problem in “Hoek Brown Softening” Model

Dear,

I have defined a model for the bedrock layer using the User Defined option “Hoek Brown Softening”. For the bedrock layer I have some laboratory data set as I attached in “Pic 01”. In this case I want to use the “Hoek Brown Softening” model, but some parameters are needed to define this model. I performed some Sensitivity Analysis for them to achieve information from them. In this case, as I attached in “Pic 02”, by these definitions I started to perform the PLT on a bedrock layer. During the analysis I encountered many errors and stopped stages before the “Ultimate Resistance” reached which showed Instability problems as the solver of Plaxis were not converged during calculations.

One specific point I encountered was that for definitions of the Fluidity Y parameter for the HBS model, as I defined positive values from even 0.00001 to 1000000 to create the Visco-Plastic regularization condition for my model to avoid these instability conditions, I noticed the calculation were moving very fast and strange for me which showed there was something wrong in this definition. The only way that showed the better performance of my model was to define zero for the Fluidity Y parameter, but by this value I encountered in every phase of my “Predefined Displacement” stages of PLT stopped stages which showed instability problems.

I think there should be some problem maybe in my phase setting definitions or in my material model parameters that even from the beginning stage of PLT, the stopped stages started

Could you please guide me how should I solve the model to converge my results?
Thanks for all your guidance and support,