Retaining wall

[Mobo_14]

Planning on building a retaining wall to hold up a drive way.

It’s approx 17 courses of block on flat just over 1800mm and I planned on building it 900mm at the base and gradually stepping it up to 215mm at the top.

Could anyone advise on how often I should reduce the thickness of the wall and if my plan is structurally sound? No drawings or engineers involved so just asking what yous think

Cheers

 

[mikeey84]

If I was going to be walking under it, I'd want a wall that high to be designed by an engineer, not people in an internet forum, but then I'm maybe just being overly nervous

 

[freddiemercurystwin]

Rule of thumb for mass retaining walls is the width is 1/3 the height so that should give you a guide. So 1/3 of 1800 at the base would be 600.

 

[Mobo_14]

Rule of thumb for mass retaining walls is the width is 1/3 the height so that should give you a guide. So 1/3 of 1800 at the base would be 600.

That’s what I usually go with just thought to beef it up at the base for at least a couple of courses.

 

[Mobo_14]

If I was going to be walking under it, I'd want a wall that high to be designed by an engineer, not people in an internet forum, but then I'm maybe just being overly nervous

You could do. Chances are they would over spec it anyway to cover their bum.

 

[^woody^]

A block flat is actually a very weak bond.

The typical maximum force from typical soils on a retaining wall will be at 1/3 the height. So the wall can be reduced at this point, so 320 then reduce to 215.

The foundations would need to be given equal design consideration to the wall

 

[Dereekoo]

Not quite right -The typical maximum force from typical soils( whatever they are) would be at the bottom of a wall. The resultant total force of this retained triangular wedge of soil is taken to act at 1/3 height for structural design purposes when calculating the overturning forces

 

[^woody^]

The wall can be reduced after 1/3 h is correct, as is the loading at the bottom third of the wall . The top 2/3 is only holding a relatively small section of ground

Typical soils are typical loose granular soils typically found in everyone's typical gardens, and not clays or rock.

 

[jks7492]

Have a look at BRE good building guide 16 - gives some useful rule of thumb guides for retaining wall dimensions for brickwork/clockwork walls.

 

[Dereekoo]

The wall can be reduced after 1/3 h is correct, as is the loading at the bottom third of the wall . The top 2/3 is only holding a relatively small section of ground

Typical soils are typical loose granular soils typically found in everyone's typical gardens, and not clays or rock.

Cant disagree about wall being reduced at ¹/3 h, in fact it can be reduced from the bottom all way to the top in a linear fashion if so desired and the blocks used facilitated such a construction.
I would be stuffed as typically in my area the ground is clay, I think London may be the same, possibly granite or slate in Wales and sandstone in Notts