Dear Friends,

I working in area of evaluation of collapse load for axisymmetric problems in geomechanics. 

I am evaluating N gamma (Weight component) for Conical footing having cone angle of 45 degree using finite element method (PLAXIS 2D).

The load deformation plot for cone diameter of 2 m is not having a saturation value i.e. the load keeps on increasing with increase in the displacement. The input parameters are:  cohesion less soil (c = 0.1 kPa), no surcharge (q = 0), weight of 20 kN/m3, Phi = 10 degree. I am using Plaxis-2D axisymetric formulation.  

Corresponding to weightless cohesive soil (unit weight is zero, cohesion = 20 kPa, surcharge = 0), the load disp plot has a saturation value whereas if unit weight is assigned, the load disp increases with increase in the displacements.

I am not able to obtain the collapse load corresponding to which the Nc Nq and Ny are determined.  

I am not getting a load disp curve with saturation or limiting value if a finite value of unit weight is assigned in the FE model

Can you please give me your inputs in this regards and what could be the possible error!!

Please see the attached pdf file of the problem statement, FE model, input parameters, etc.

Kind Regards

Jitesh