I suggest you to use PLAXIS or FLAC3D software for better predicting the soil pile interaction response. If at all you are interested in using ANSYS then try to simulate the pile and soil by using 8 or 20 noded solid elements. Then, the response pile you try to model using linear elastic and the soil using Drucker - Prager or Mohr - Coulomb model. The spring element model have limitation in predicting the response of pile - soil interaction.

Thanks a lot for your answer.

As you mentioned I have modeled pile and soil using 8 node solid elements. I'll try using the mentioned models for soil.

Thanks again for your comment.