Spring constants application-Staad

Dear all, 

Currently i am modelling tunnel lining for a project in Staad Pro. This requires the application of compression springs both on sides as well as invert. i have doubts regarding direction of radial and tangential stiffness to be applied in the model. 

1.As far as i understand, the KFX, KFY and KFZ values are to be specified along the current global axis of the model or is it a convention that radial stiffness always has to be specified as KFX irrespective of the global axis? 

2. Directions of radial stiffness shall be different for the invert (Global vertical) and side walls (Global horizontal). Do we have to consider different directions( KFX(radial for side walls) and KFY(radial for invert)) while specifying stiffness or they shall remain same (e.g. as KFX(radial for sidewalls as well as invert)) throughout the model? 



Regards