Material parameters for the embedded beam row in PLAXIS 2D are defined per structure (e.g. pile or ground anchor). In a plane strain analysis, these values are automatically calculated per unit length in the out-of-plane direction. So, the calculation kernel takes the spacing of these embedded beam row elements into account.
However, in the case of a layer dependent axial skin resistance distribution, the calculation kernel does not take this spacing into account.
As a consequence, when the pile spacing Ls > 1 m, the maximum axial skin resistance Tskin,max will be overestimated.
To check what exact value per unit length in the out-of-plane direction is used, you can see this value for the actually used Tmax in the Output program:
This is now solved since PLAXIS 2D 2017.01
In PLAXIS 2D 2017.00 and earlier versions (see the versions mentioned above) in which this spacing value [Ls] is not taken into account to determine the maximum axial skin resistance, you should divide the axial skin resistance by the spacing and use this value as an input value.