resrtaint due to sheet piles

[shreev10]

I am designing a water retaining structure which is cast within the sheetpiles.
The wall are pretty thick and the external formwork for the walls is provided by the sheetpiles. the internal formal to the walls is plywood.

I would like to know what kind of restraint wil the sheetpiles offer?
would i need to consider an end restraint case ?
or can i go with the end retaint case and a high restraint factor, say 0.8?

Regards

 

[EngDM]

How is the sheet pile restrained? Are you planning to tie it back with anchors or embed it below the excavation to create a cantilever?