Question
Could you shed some light upon building a wall on sand. We are aiming for a contract in Kuwait to try and build a wall about 340m long. I have the guys to execute the work but do not know the depth and specs to erect a wall 2.7 m high. Any help would be appreciated. I am an engineer and will use this information to supervise the work.

Thanks a lot.

Hansen

Answer
Well, my advice would be to consult a Structural Engineer or geotechnical CE experienced in coastal engineering, but that is what your question is, isn抰 it!  

Sand is notorious for being a poor structural substrate, and there are not that many beaches & dunes here in the desert where I live (mostly metamorphic and alluvium).  You could do steel, precast concrete, or cast-in place pilings.  Then, tie the wall footing to it, but you抮e still dealing with an inherently unstable and erosive medium.  So the base of the wall may be 揻loating in space?in a few short years, just from erosion.

You should consult a geotechnical engineer and have him/her do some CPT (Cone penetrometer technology) tests and determine the depth to a good end-bearing strata, or the depth and number of piles for sufficient piling/skin friction.   

The footing solution is very site-specific.  Sand can liquefy and become unstable, especially if your sand in an environment subject to substantial groundwater or tidal influences.   Second, is the area subject to earthquakes? Sand becomes unstable as a foundation upon shaking, especially if wet!   

Remedies are available to overcome these stability limitations. One of the most common is compaction. To prove that you can build on sand just look at Japan. Most of their island is built on sand. They have had problems with earthquakes and have learned a lot because of it.

You can also modify soils with injection, densification, replacement, or a combination.

As far as information regarding building on sand look at any geotechnical/foundations engineering texts, the better part of half of most engineering books address building on sand.  For a quick review online at Amazon.com or Books.Google.com, try looking up 揇esign of foundation systems: principles and practices? By Nainan P. Kurian  - He shows how to calculate typical sand footings (He calls them 搑afts? also called 搒pread-footings?here in the US) for various load-bearing scenarios. It is only a $100 book, if this is what you are looking for.

Here are some on-line technical resources for sand/structural footings:
1.)from Japan:
www.fellenius.net/papers/162%20Footings%20in%20sand.pdf
2.)Another paper regarding spread footings on sand(from Texas A&M)
http://74.125.113.132/search?q=cache:4h9_1vIwmMkJ:www.roctest.com/modules/AxialR...

(Hopefully the long link works - If not just clip and past into your browser, or google "sand footings A&M")

Is the wall freestanding, or does it retain soil load/surcharge?  It will affect all sorts of design parameters (moments, footing spread, use of geogrid, etc.) ?See Kurian抯 book, or similar, if you don抰 know what these terms refer to...

Sorry to dump a bunch of technical stuff on you, but what you are trying to do is fraught with potential hazard, and you said you are an engineer.  Best of luck.

~Marc

PS Forgot to mention another good source of info: the ASCE website (http://www.asce.org/).  Scan their publications or search for a qualified geotech that can help you.