Hi Claudio,

As a practicing engineer, I am concerned about bearing capacity, sliding and overturning failure. Variables that are important could be weight, friction factor and durability of the wall to name a few.

Hopefully it helps.

Please see this report  from Professor Andrew Drescher and Professor David Newcomb with the University of Minnesota regarding the use of shredded tires for as fill for retaining walls and subgrade material for roadways.,

http://www.dot.state.mn.us/research/pdf/1994-04.pdf

Stacking the tyres, somewhat akin to a "crib" wall has been done for quite some time but as for a study? I have never heard of one. They are generally just low height walls with virtually only landscape value.

The biggest issues I would perceive for a "genuinely" loaded retaining one would be;

a. the infill material - free-flowing and "self-compacting" along the lines of fine to medium fine sands hydraulically placed would appear first glance a possible solution or even stabilised sand;

b. the voids created by the tyres shape/profile when filled;

c. the durability of the tyres - given that they would almost certainly be used and possibly quite old; and

d. the erection methodology and the interlock it generates.

Of course there are myriad others, like climate, traffic, sub-soils, foundations...and so on.

Tyres chained together and used for sand/beach reclamation/rectification/regeneration have been around for years.

So aside from the issues that Mr. Chuah raised, quite correctly, I would suggest you have a quite large research testing program awaiting you.

All the best. Be interesting to know the results because I have seen them used by farmers to create bunds in flood prone areas.

Depending on the height of the wall and the back infill material you are going to use, one or another of the variables raised by Mr. Chuah is going to be the critical. For example, by using granular material to fill the voids between/inside the tires (when using more than one line of vertically piled tires), then you practically will have only vertical load acting, and the bearing capacity of your soil, will be the most important varible to test.

Thanks to everyone for your time and knowledge. Finally i've decided study the interaction inside the retaining wall. In this kind of walls is important the external and internal design. The interaction between the sucesive's mats of tires tied togheter play's an important rol. Also the join beetwen the mat, the weight to name a few.

Some authors who have studied the use of tires in reinforced earth are: N.T. Long (France), O'shaughessy (Canada), Gerscovich (Brazil)...

I will share my studies in a few months.Thanks again!.