Landscaping walls and soil borings

[rceconsulting]

Recently I've run across a few situations where so-called "landscape" retaining walls are required to be designed. Typically these walls are to be comprised of segmental block. My question pertains to the need for soil borings. I always request that a boring program be carried out for these walls (usually 4 ft or higher),however I often meet resistance due to the cost/time/etc. from both the client and sometimes my supervisor as well. I'm just curious about other's experience with this issue. Thanks.

 

[hokie66]

My opinion...overkill. All you need is a bit of a hole to see what is there near the surface. These type walls are flexible, so tolerate a variety of founding conditions.

 

[cvg]

ask your geotec for a cheaper alternative such as just a field visit with no samples or lab work. They may be able to give you enough information to design your wall without actually digging or testing - or they may not. It's worth a try.

 

[AussieGeoEng]

Depends on what you are referring to with segmental block - if you are referring to a proprietary product then maybe not so much of a problem.

I know of documented problems with boulder retaining walls constructed as "landscaping" feature so it doesn't need engineering design.

Search for "Boulder Wall Design and Construction Considerations" in the 10th Australia New Zealand Conference on Geomechanics

 

[msucog]

overkill?! NNOOOOO. mse walls are very complicated geotechnical structures and carry substantial liability. plus the material criteria on these walls is very particular. the wall designers must account for many geotechnical aspects so they must know what's going on deep below, in, behind and on top of the walls. the specifications typically have set criteria for all the many soil properties and the wall designer usually has to stamp/signoff on the wall and wall construction at the end. the permits and building code here typically require engineering, exploration and testing for anything over 6' tall.

FHWA-NHI-00-043

http://www.fhwa.dot.gov/engineering/geotech/library_listing.cfm