Pandu:

First of all the rocscience's programs have some tutorials in order for the user to get familiar with the programs

Slide tutorial: https://www.rocscience.com/help/slide/webhelp/tutorials/Slide_Tutorials.htm

If you are looking for a slope stability FS value incluiding pore pressure defined by water table then you should have groundwater method define as water sufaces in the project settings. In that kind of analyse you only have to define the points where your water table passes. Remember that when you are defining your material properties, in the water parameter option you have to choose the water table that you defined. 

Because Slide is an equilibrium limit method there"s no need to define boundary conditions as necessary for FEM analysis.

This specific tutorial will help you out

https://www.rocscience.com/help/slide/webhelp/pdf_files/tutorials/Tutorial_02_Materials_and_Loading.pdf

Also i would like to notice an error in your model image in the right side, your water table once it goes out of the ground must have a constant level, can't have the slope you design. I'm attaching an image to show my commentary.

Slide also has the option to run some FEM analyse but just to analyse groundwater seepage not slope stability.

https://www.rocscience.com/help/slide/webhelp/pdf_files/tutorials/Tutorial_07_Finite_Element_Groundwater_Seepage.pdf

Actually you need to specify two (simple phreatic surface) or more (complex phreatic surface) reference points with respect to global co-ordinate system. Then these points will give you a line of equal piezometric heads. Provided that you require to adjust piezometric pressure for local area either due to excavation or construction dewatering, specifying nodal values of the piezometric heads is necessary.

Get the basics first by getting familiar with the Rocscience manual as mentioned by Bernardo. Relate each sample tutorial with your problem and go on to understand the concept of FEM seepage analysis in slide.

 Bernardo Jimenez is correct about his observation regarding your water table.  In the real world, there is nothing that would keep a pond from forming in the low-point of your surface elevation profile, unless you had some really spectacular pumps operating.  Even then it would be impossible in a real-world situation to get a water table exactly coincident with a sloping ground surface as you have depicted in your model.  All this leads me to conclude that you might actually be trying to model the pore-water pressures in a confined aquifer at depth.  If this is the case, then the advice to carefully master all the nuances of whatever program you choose to use are even more important.  I have not used the Rocscience program "Slide," but one always needs to start from an accurate, realistic model of both the subsurface geology and groundwater conditions.  It appears from your model that you might want to consider starting by modeling the groundwater with a Rocscience program, or some other groundwater program, and then move the results into a slope stability program.

Dear Bernando Jimenez,

I know the mistake was i'm not getting familiar with the program before i used with, so my apologize for it ^^. Yes, i'm looking for slope stability FS using limit equilibrium analysis including pore pressure defined by water surface with several simulation, ex: water with depth 10 mbgl, 20 mbgl, with the result that i could get how to manage water pressure with certain slope angle for my learning.

At the point i made this question, i just confused with the boundary of water surface i have to applied. in example slope stability with overall slope angle 40 degree, and water level 10 mbgl. I'm attaching images for the explanation. what is the most ideal boundary for 10 mbgl? and the reason :)

Thank you in advanced for your priceless help

Yours faithfully

Pandu