Materials for retaining wall?

[namtrak]

Wes,


Eastie has given some good advice on the rule of thumb for 1:1 for depth of footings.

Im not so sure about the 1:1 footings, I think the depth of the footing relates more to the load behind the wall. Also suspect that when you start getting footings over probably 600mm then they aren't achieving much. You dont have to go far to see retaining walls at 2m high and Im pretty sure that the footings for those aren't 2m deep. However I have been proven wrong before

[IanA]

Namtrak, there are many factors that influence the design of retaining walls and the design solution will reflect these. These will include the engineering properties of the soil at the base of the wall as well as the fill material behind the wall, and the behaviour of both soils when wet.
They can be designed as gravity structures, in which the mass of the wall and the breadth of it's base resists soil pressure behind the wall, in this case the footings may be relatively shallow.
Other methods include universal sections used as piles, soil anchors, or a combination of both.
For low walls, like the one that Wes is proposing, it would be costly have the soil tested at a lab and then to go through the full structural design, hence the 1:1 rule of thumb.

[Wes2008]

Hey guys,

I would like to thanks for all the help/advices you guys have given me. I ended up getting the Universal Column from Smorgon Steel. And they were very helpful. I will be getting the treated pine sleeper from Import Tile. I am glad that I found what I was looking for.

Once again thankyou very much.

Cheers,
Wes

[Eastie]

What is above is very much a 'rule of thumb' - applied to walls upto 1m (with a normal bearing load above the wall = 5kPa, e.g. your not parking cars on it).

For example a 600mm high wall has a common engineering spec of 500mm concrete footing in clay or 800mm concrete footing in sandy soil.

For walls higher than 1.2m engineering specs start to vary more (i.e. 1500 high wall = 1300mm footing in clay or 1700mm footing in sand / 1800 high wall = 1800mm in clay or 2000mm in sand).

1:1 is a rule of thumb, and if you've got free draining sandy soil it generally pays to go deeper to increase the bearing capacity. In any instance for walls above 1m you should check with your engineer

[Gingermick]

For walls higher than 1.2m engineering specs start to vary more (i.e. 1500 high wall = 1300mm footing in clay or 1700mm footing in sand / 1800 high wall = 1800mm in clay or 2000mm in sand).

We allow a 300mm footing for the bigger walls we design. (keystone type) Just to stop the bricks from sinking not to add stability to the wall. This is achieved through a geogrid that is locked to the blocks and goes back on approximately a 1:1 ratio. (Dependant on soil type and load and height)
mick

[Eastie]

Yep - forgot to mention that is for steel/timber soldier sets - not blocks.