The answer to Q.1 has to do with boundary limits...

Hi Sumit,

See responses in the attached word file.

Thanks.

Steven

@Niel-sir:

Thanks a lot sir Neil, I understood your valuable comments & incorporate in my further analysis accordingly.

@Halcomb-sir:

My sincere appreciation for your comments in the word file . I am going thru the word file & trying to correct my errors. I shall get back to you immediately once I get thru it.

Highly appreciated the support in lending me the time to go thru my word file to assist me. Once again, thank you so much to you both.

Sumit

Dear Halcomb-sir,

I have uploaded my latest result herewith.

Hi Sumit,

Glad to see you're making progress. In looking at the summary table of the offset distances vs. factors of safety. You'll note that the methods that show varying factors of safety are those that satisfy force equilibrium. The example from SLIDE shows that the Spencer's and GLE/M-P methods have a similar trend (a portion where the factor of safety drops below previous values and then comes back up - interesting to see the difference in the two methods too). I'd have to dig into the forces on the slices in your model to really review but I'd say it's likely due to how much external force from your 10 meter wide load is acting on the failure plane. That is, look at each analysis and see how much of the failure plane is below the external load. I'd suspect the number of slices (and hence the amount of force) on each failure plane below the external load is slightly different hence you're getting different factors of safety.

Dear Halcomb - sir,

I highly appreciate your valuable comments and your time for guiding me

Specifically, I've watched the slip surfaces for Spencer method at 10m & 15m offset distances.

SUMIT.