Horizontal displacement of earth dams during construction

[geotechguy1]

I'm trying to find a reference (preferably with case histories) for expected horizontal displacement ranges of an earth dam during construction as a percentage of height, eg. 0.5% to 1.0% of the height. I have that range (up to ~1.0%) in my head as a rule of thumb some grey haired guy in a corner office told me as a grad but I don't have a good reference for it.

 

[Milliontown]

I'm not really aware of any rules of thumb for horizontal displacement. the "1%" rule is generally used for vertical settlement of embankment dams under 200-feet (USBR DS13-9 section 9.3.2).

Horizontal displacement is a bit more complicated. Are you wanting to know the displacement at the crest, midslope, toe? The linked USBR design standard includes some information on the general pattern of horizontal deformation, but not much in the way of estimates or examples (pg. 5-6). If you really need to know, numerical modeling can give an estimate. Hand calcs could be possible but may be tedious.

We're generally most worried about vertical settlement and the implications of a lowered crest elevation and associated overtopping risk. The DS13-9 similarly states that horizontal displacement is a fraction of vertical displacement and if vertical displacement is acceptable, horizontal displacement is as well.