Al Reynolds wrote:

"Sam" wrote:

Sorry, dg, but you are wrong on this one. A 330mm blockwork wall will
never be strong enough to retain 3m of soil, even with no surcharge on
the retained side, no water etc.


There's an awful lot of assertions in this thread.

Outside my back door is an earth bank, sloping
backwards at about 10 degrees to the vertical.
There is an un-reinforced concrete footing which
is 1.5ft high and about the same deep, followed
by 3.5ft of dry stone walling, maybe 8" deep. The
remaining 6ft of bank is not retained by any structure.

In total, I am guessing that this is considerably less
support than a 330mm blockwork wall, and it has
all been in place for about 80 years.

For a start thats only 5 ft, not ten foot high as a structure, and
secondly, I bet the remaining 6 ft slopes well back from the lip.


My point is that no-one can make absolute assertions
about what is or isn't sufficient to retain an earth bank
unless they investigate further.#

True. I have a 2'6" wall that I built very very conservatively, and so
far its fine. Block inside, with brick decorative facing. Convex but I
tied every block together and about every other brick, and tied the two
together.

No signs of movement BUT its a terrace behind it, that is flat. Its not
holding back a whole hillside, and it isn't in Boscastle either :-)

To make the point that any structure can go if enough unusual conditions
are imposed on it. Boscastle has been there a couple of hundred years,
not a mere 80....:-)



The best advice is to
consult someone who knows what they are talking
about, and is prepared to guarantee their conclusions.
It doesn't help slagging off other people on here.


True.

Biggest danger from a wall like this is water, If the hillside is
treeless, and there is not much vegetation and not much drainage, you
can get a landslip starting that nothing will stop. Deforestation is a
Bad Thing on slopes.

Even a structural engineer can only guess at 'worst cae' conditions.

Traditionally such things got rebuilt until they stopped falling down
for long enough to be regarded as 'permanent' 80 years is not 'permanent'


Just my two cents,
Al