Back analysis of stable un-failed slope

[geotechguy1]

I'm looking for a reference, the title of which eludes me on back-analysis of stable, un-failed slope. The reference presents a table of presumed factors of safety to use in the back analysis based on observed slope performance eg.

1.1 - if evidence of recurrent movement (i.e. there isn't a current failure but the geology / geomorphology suggests a history of failures)
1.3 - if no evidence of failures, no evidence of slope creep or deformation
1.4 -

I forget all the criteria now but it was used to justify using 1.3 or 1.4 in back analysis of an apparently stable slope to get parameters for use in forward analysis of a wall

 

[EireChch]

GG1 did you ever find this reference, funnily enough I am in need of it now !! I have a stable slope and trying to do a back analysis to justify parameters!

 

[geotechguy1]

I haven't been able to find it unfortunately. A previous employer in NZ adopted this approach ( I think there was a table where you'd use 1.0, 1.1, 1.2, or 1.3 in your back analysis depending on a field inspection of the slope - whether there was evidence of movement, distorted trees stuff like that). It was given to me by word of mouth / old reports but I'm certain at some point I found a reference paper that had it spelled out we could refer to. I wonder if it was an old Ministry of Works thing.