Boulder Retaining Walls

[tkvail]

Is the standard practice for designing Boulder Retaining walls to model it as a gravity retaining wall? Even though the boulders are segmental and not interlocked? If not are there references out there that provide adequate design methods? Any help on this subject would be great.

I have been told that boulder wall design is more by "rule of thumb" and that there is not a way to calculate a Factor of Safety for sliding and overturning. If this is the case how does one satisfy the typical adopted Building Code of a community that typically states all walls over 4' must be engineered and have a FS of greater than 1.5 for overturning and sliding?

Thanks

 

[tkvail]

It seems that this is a somewhat common question regarding the design of Rock Gravity retaining walls, aka Rockery. I have read thru all the threads pertaining to this answer and sounds like the jury is still out on this one.

Any comments regarding the problem with showing that a rock gravity wall can have a factor of safety greater than 1.5? How do other jurisdictions deal with this?

 

[oldestguy]

It is doubful that "boulder walls" built as gravity walls exceed 4 feet by much. If they are done by the "rule of thumb" with width being at least one third the height, there appears to be sufficient interlocking to do the job.

Any of these should be "designable" using earth pressurea and similar data to come up with a SF.

Those that I have seen that go much higher are built with mortar between the rocks, giving some degree of strength, fitting a design method.

Some very high ones (20 to 30 feet) do not seem to fit with any design, but are more or less "facing" of an earth slope that otherwise would stand by itself, except for face erosion. These generally are laid back at that "stable earth" slope angle. There is no design, other than the stability design of an earth slope.