Are there any rules of thumb or rough guides for how much static load a
pile say 100mm dia and 1m (or varying) depths will support in clay soil?

I'm mentally planning the workshop and I would like to timber frame the
floor, raised off the ground and supported on 4-6 piles (hence the
question).


The main reason is I will be *very* close to drains (shared sewer) and
hand dug piles will present the (albeit small) load below the depth of
the drain - and more importantly - when the water co want to dig it all
up and fix them, my workshop will not fall over.

Also, piles are not going to be much more work than a concrete or brick
foundation wall.


Cheers

Tim

On Sun, 23 Feb 2014 13:14:38 +0000, Tim Watts
wrote:

Are there any rules of thumb or rough guides for how much static load a
pile say 100mm dia and 1m (or varying) depths will support in clay soil?


Don't know. But saw sonotubes mentioned the other day on a beekeep
forum (Alternative use) - am sure I saw some figures on one of the
sites about them that gave dimensions vs load.


I'm mentally planning the workshop and I would like to timber frame the
floor, raised off the ground and supported on 4-6 piles (hence the
question).


The main reason is I will be *very* close to drains (shared sewer) and
hand dug piles will present the (albeit small) load below the depth of
the drain - and more importantly - when the water co want to dig it all
up and fix them, my workshop will not fall over.

Also, piles are not going to be much more work than a concrete or brick
foundation wall.


Cheers

Tim
--
http://www.voucherfreebies.co.uk

Tim Watts wrote:
Are there any rules of thumb or rough guides for how much static load
a pile say 100mm dia and 1m (or varying) depths will support in clay
soil?
I'm mentally planning the workshop and I would like to timber frame
the floor, raised off the ground and supported on 4-6 piles (hence the
question).


The main reason is I will be *very* close to drains (shared sewer) and
hand dug piles will present the (albeit small) load below the depth of
the drain - and more importantly - when the water co want to dig it
all up and fix them, my workshop will not fall over.

Also, piles are not going to be much more work than a concrete or
brick foundation wall.

Hand digging piles isn't as easy as it sounds.
They will end up conical in shape, with the narrow end being at the bottom -
proper piles are driven in, these are steel tubes 150mm across, rammed into
the ground pneumatically until they won't go any further, then filled with
concrete, this creates 'stilts' that hold up a ring beam that is poured on
top.

For a workshop, you might be better digging four holes, (one for each
corner) putting about 150mm of concrete in the bottom and building concrete
block pillars to get to the desired level - blocks laid on their side would
be best.
Then lay pre-stressed concrete lintels from one to the other to create a
raised frame ready for your timberwork to be built

On 23/02/14 15:42, Phil L wrote:
Tim Watts wrote:
Are there any rules of thumb or rough guides for how much static load
a pile say 100mm dia and 1m (or varying) depths will support in clay
soil?
I'm mentally planning the workshop and I would like to timber frame
the floor, raised off the ground and supported on 4-6 piles (hence the
question).


The main reason is I will be *very* close to drains (shared sewer) and
hand dug piles will present the (albeit small) load below the depth of
the drain - and more importantly - when the water co want to dig it
all up and fix them, my workshop will not fall over.

Also, piles are not going to be much more work than a concrete or
brick foundation wall.

Hand digging piles isn't as easy as it sounds.

Appreciated - I was thinking hand-auger, but that may or may not be easy
in my soil.

They will end up conical in shape, with the narrow end being at the bottom -
proper piles are driven in, these are steel tubes 150mm across, rammed into
the ground pneumatically until they won't go any further, then filled with
concrete, this creates 'stilts' that hold up a ring beam that is poured on
top.

For a workshop, you might be better digging four holes, (one for each
corner) putting about 150mm of concrete in the bottom and building concrete
block pillars to get to the desired level - blocks laid on their side would
be best.

That would be OK too - on the drains side I will just go 1m or so down,
less on the other side.

Then lay pre-stressed concrete lintels from one to the other to create a
raised frame ready for your timberwork to be built

Cheers

Tim

On Sun, 23 Feb 2014 15:42:52 -0000 Phil L wrote :
proper piles are driven in, these are steel tubes 150mm across, rammed
into the ground pneumatically until they won't go any further, then
filled with concrete, this creates 'stilts' that hold up a ring beam
that is poured on top.

Piles can be driven or bored: on larger projects the ground will
determine which is used - if it's a loose sandy soil overlaying gravel
then boring won't work as the sides will fall in, so driving to a set is
the norm. In clay IME boring is the norm.

Re the original OP's question, in my BCO days the rule of thumb
(literally!) for firm clay (defined as thumb press will leave an
impression but not sink in) was 1 ton/ft2, which for a 100mm bore would
allow 86kg - make the bore a more practical (in terms of being able to
get concrete down the bore) 150mm, and this increases to 193kg.

--
Tony Bryer, Greentram: 'Software to build on',
Melbourne, Australia www.greentram.com

On 23/02/14 22:08, Tony Bryer wrote:


Re the original OP's question, in my BCO days the rule of thumb
(literally!) for firm clay (defined as thumb press will leave an
impression but not sink in) was 1 ton/ft2, which for a 100mm bore would
allow 86kg - make the bore a more practical (in terms of being able to
get concrete down the bore) 150mm, and this increases to 193kg.


Wow - that's a nice easy figure. Thanks Tony.

Sounds like I would need wider piles (as Phil L suggested for practical
purposes) and maybe more.



I presume that what really matters here is the surface area at the load
face - ie the bottom of the hole? Concrete is far far stronger in
compression than the bearing load of a pile.

Would it make any difference to put 6" of concrete in the bottom of the
hole with a small pile formed into that (using 100mm drain pipe) to save
on quite a lot of concrete? Backfilling with earth.

eg

SSSSSSSSSSSSSSSSSSSSSS
D D
D D
D D
D D
D D
D D
D D
D D
D D
FFFFF FFFFF


D=100mm drain pipe pile
F = wider footing, eg 1sq ft.

Assume a few bits of rebar are dropped in.

More practical for hole digging, practical in terms of concrete.

On 23/02/14 22:18, Tim Watts wrote:
On 23/02/14 22:08, Tony Bryer wrote:


Re the original OP's question, in my BCO days the rule of thumb
(literally!) for firm clay (defined as thumb press will leave an
impression but not sink in) was 1 ton/ft2, which for a 100mm bore would
allow 86kg - make the bore a more practical (in terms of being able to
get concrete down the bore) 150mm, and this increases to 193kg.


Wow - that's a nice easy figure. Thanks Tony.

Sounds like I would need wider piles (as Phil L suggested for practical
purposes) and maybe more.



I presume that what really matters here is the surface area at the load
face - ie the bottom of the hole? Concrete is far far stronger in
compression than the bearing load of a pile.

Would it make any difference to put 6" of concrete in the bottom of the

Meant 12", about 1 sq ft ^^^

hole with a small pile formed into that (using 100mm drain pipe) to save
on quite a lot of concrete? Backfilling with earth.

eg

SSSSSSSSSSSSSSSSSSSSSS
D D
D D
D D
D D
D D
D D
D D
D D
D D
FFFFF FFFFF


D=100mm drain pipe pile
F = wider footing, eg 1sq ft.

Assume a few bits of rebar are dropped in.

More practical for hole digging, practical in terms of concrete.

On Sun, 23 Feb 2014 22:18:57 +0000 Tim Watts wrote :
I presume that what really matters here is the surface area at the load
face - ie the bottom of the hole? Concrete is far far stronger in
compression than the bearing load of a pile.

Yes, for short piles like this it is end bearing only [for the mega deep
piles that hold up tower blocks, under-reaming - tapering out the bottom
to give a large area - is common, and friction on the pile sides also
increases the capacity].

Would it make any difference to put 6" of concrete in the bottom of the
hole with a small pile formed into that (using 100mm drain pipe) to save
on quite a lot of concrete? Backfilling with earth.

You're not going to use that much concrete, but you're right: even weak
concrete will be way stronger than the ground. In my old UK home I built a
deck on mini-piles like this and lost quite a bit of clean rubble in them.

--
Tony Bryer, Greentram: 'Software to build on',
Melbourne, Australia www.greentram.com

On 23/02/14 22:54, Tony Bryer wrote:
On Sun, 23 Feb 2014 22:18:57 +0000 Tim Watts wrote :
I presume that what really matters here is the surface area at the load
face - ie the bottom of the hole? Concrete is far far stronger in
compression than the bearing load of a pile.

Yes, for short piles like this it is end bearing only [for the mega deep
piles that hold up tower blocks, under-reaming - tapering out the bottom
to give a large area - is common, and friction on the pile sides also
increases the capacity].

Would it make any difference to put 6" of concrete in the bottom of the
hole with a small pile formed into that (using 100mm drain pipe) to save
on quite a lot of concrete? Backfilling with earth.

You're not going to use that much concrete, but you're right: even weak
concrete will be way stronger than the ground. In my old UK home I built a
deck on mini-piles like this and lost quite a bit of clean rubble in them.


Thank you Tony - I have a plan

On 23/02/2014 22:18, Tim Watts wrote:
On 23/02/14 22:08, Tony Bryer wrote:


Re the original OP's question, in my BCO days the rule of thumb
(literally!) for firm clay (defined as thumb press will leave an
impression but not sink in) was 1 ton/ft2, which for a 100mm bore would
allow 86kg - make the bore a more practical (in terms of being able to
get concrete down the bore) 150mm, and this increases to 193kg.


Wow - that's a nice easy figure. Thanks Tony.

Sounds like I would need wider piles (as Phil L suggested for practical
purposes) and maybe more.



I presume that what really matters here is the surface area at the load
face - ie the bottom of the hole? Concrete is far far stronger in
compression than the bearing load of a pile.

Would it make any difference to put 6" of concrete in the bottom of the
hole with a small pile formed into that (using 100mm drain pipe) to save
on quite a lot of concrete? Backfilling with earth.

It might not.. quite a lot of the resistance is from friction at the
sides of the pile. (Well it is on the ones that don't reach rock.)
Some large buildings are built on sand by doing this and there wouldn't
be any difference in the weight bearing capacity at the bottom than at
the top if it weren't for the friction on the sides.

Tony Bryer wrote:

Piles can be driven or bored: on larger projects the ground will
determine which is used - if it's a loose sandy soil overlaying gravel
then boring won't work as the sides will fall in, so driving to a set is
the norm. In clay IME boring is the norm.

For anyone who has the time to read it, this is the report into
the pile boring machine which drilled into a Network Rail tunnel,
leaving auger sections across the track.

http://www.raib.gov.uk/cms_resources...Old_Street.pdf

"Summary
During the morning of Friday 8 March 2013, a train driver
reported that flood water was flowing from the roof of a railway
tunnel north of Old Street station near central London. The
driver of an out-of-service passenger train was asked to examine
the tunnel at low speed and check for damage. The driver stopped
short of the water flow and reported that two large drills
(augers) had come through the tunnel wall and were fouling the
line ahead of his train.

The augers were being used for boring piles from a construction
site about 13 metres above the top of the tunnel. The operators
of the piling rig involved were unaware that they were working
above an operational railway tunnel. Its position was not shown
on the site plan, or on any map available to either the developer
or the local planning authority. As a consequence, Network Rail
was not consulted during the planning application stage and was
unaware of the construction activity.

The RAIB has determined that approximately half of the piles
required for the new development would have intersected with the
tunnel had they had been constructed. It has identified two
learning points from this incident which are relevant to the
construction industry: clients and design teams should be aware
of the importance of information shown on land ownership records;
and those carrying out investigations for proposed developments
should be aware that not all railway tunnels are shown on
Ordnance Survey mapping.

The RAIB has also made five recommendations: three are addressed
to railway infrastructure managers, and relate to: the provision
of information to organisations undertaking property-related
searches; the provision of information on the location of railway
tunnels and associated subterranean structures; and the
identification of development work by third parties. One
recommendation is made to the British Standards Institution
relating to the enhancement of a British Standard, and one
recommendation is addressed to the Department for Communities and
Local Government relating to a recommendation made by the RAIB in
2007 which has not been implemented."

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

On 23/02/2014 16:36, Tim Watts wrote:
On 23/02/14 15:42, Phil L wrote:
Tim Watts wrote:
Are there any rules of thumb or rough guides for how much static load
a pile say 100mm dia and 1m (or varying) depths will support in clay
soil?
I'm mentally planning the workshop and I would like to timber frame
the floor, raised off the ground and supported on 4-6 piles (hence the
question).


The main reason is I will be *very* close to drains (shared sewer) and
hand dug piles will present the (albeit small) load below the depth of
the drain - and more importantly - when the water co want to dig it
all up and fix them, my workshop will not fall over.

Also, piles are not going to be much more work than a concrete or
brick foundation wall.

Hand digging piles isn't as easy as it sounds.

Appreciated - I was thinking hand-auger, but that may or may not be easy
in my soil...

This would be much more fun:

http://mtsplant.co.uk/products/attac...ar-drive-unit/

Colin Bignell