Filling 2 out of 5 rai. Any problems?

[pipoz]

why piles?
sand is excellent for building on

I do NOT want to start an argument, but sand is not excellent to build on for two major reasons: liquefaction and erosion, the former and latter being major problems in not only Thailand.
If oldmajor says he needs piles, after digging down 3 metres because of the sandy soil, then he should know!

Sorry but tend to disagree, depending on what the nature/make up fo the sand is.

If it is a type of packing sand, i.e. sand and clay mixture, undistrurbed with good compaction ability, then you build a four storey building on it with a pad footing & raft foundation and no need to pile.

If it is loose sand quality as in similar to beach sand types, then I would agree.

It sound like olmajor is digging down into an original or undistrurbed base! and it doesn't look like he is near a beach, nor does the colour look like a beach sand or overly sandy consitancy. It is of a redish colour which suggest it has may have a good mix of clay in it.

[Roger Ramjet]

Sorry but tend to disagree, depending on what the nature/make up fo the sand is.

That's a contradictory statement. Oldmajor said he needed piles, are you saying he doesn't or are you saying it depends, based on your "analysis" of his soil or based on your interpretation of his photo?
No matter how much sand is mixed with clay in Thailand, you will still have a major problem with liquefaction/expansion/compaction when the rains arrive. Have a look at half the houses in Bangkok and surrounds that have just used pad footings and you'll see cracks in walls, doors that won't close, steps that break away from the house structure and a plethora of other problems. Expansive clay soils shrink and swell significantly throughout the year in response to moisture levels and are common in Thailand. This shrink / swell cycle puts large pressures on in-ground foundations and is responsible for foundation cracking and movement which can cause damage brick facades and internal plaster board walls. The same applies to sandy soil which "shifts" or moves and compacts/expands, and therefore needs piles to stabalise either the raft slab or footings....if that's what oldmajor is going to build.... a house and workshop.... either on a raft slab or above ground.
As yet oldmajor has not told us what the Or Bor Tor or Tesaban engineering departments would recommend for his area, all he has said is the ground is sandy and requires piles.

[splitlid]

oi oi oi, i thought ya said you didnt want to start an arguement

bedrock bestest
sandy soil excellent
clay bad
in that order

[pipoz]

It’s not a contradiction Roger

Your statement was general: "...sand is not excellent to build on for two major reasons: liquefaction and erosion, the former and latter being major problems in not only Thailand". Sorry but this is not correct and some sand based soils are suitable if not excellent to construct low level commercial buildings on without piles and this is certain for a single storey dwelling. I don’t see a contradiction in my response, but more an explanation/clarification.

Having constructed a number of low level (up to six storey in height) commercial buildings all founded on sandy based soils, without need to piles, in Melbourne, on the Gold Coast and in Asia, buildings can be and are constructed on sandy type soils every day in the world, without the need to pile. Yes, sandy soils do vary in their consistency, strength and overall suitability for pad/raft foundations, but they can be and are built on, without the need to pile. PS, those building are still standing after 15 years.

I also seriously doubt that liquefaction will be an issue/factor to consider, in the Thailand region, where oldmajor is building

Keep in mind we are only talking about a simple house structure of a relatively light weight.

[Roger Ramjet]

http://www.myfoundationsolutions.com/wh ... andy-soil/

[pipoz]

http://www.myfoundationsolutions.com/why-foundations-fail/sandy-soil/

Roger, it's just a web link written by an Unknown.

Next we will be believing what we read in the daily newspapers or tabloids!

[Roger Ramjet]

http://homerenovations.about.com/od/leg ... otings.htm

[Roger Ramjet]

Pipoz,
That last one was the IBC recommendations: please note that sandy soil of any description is at the bottom as far as suitability is concerned. You must go deeper to where the rocky soil starts, especially in low lying areas in Thailand.
The science is friction. When do the foundations have enough friction to support the mass above? Sand is not a good supporter, therefore oldmajor is going to sink piles to where friction is greater.

[sirineou]

My House in Florida, like every other home there, is constructed on sandy soil, on a raft foundation, It is now 12 years old and not a single problem

[oldmajor]

Sorry but tend to disagree, depending on what the nature/make up fo the sand is.

As yet oldmajor has not told us what the Or Bor Tor or Tesaban engineering departments would recommend for his area, all he has said is the ground is sandy and requires piles.

I haven't yet met with the Or Bor Tor or Tesaban engineering departments yet. I hope to do so in March.
I beleive that Piles will be required as we did not hit any type of compacted soil or bedrock when we dug out a 3 metre hole. That coupled with digging back through the 1.5 - 2 metre fill that I have put down would make for some pretty deep foundations.

[Mike Judd]

It is really up to the builder what way he goes, but plenty of houses ,factories etc; have been built on properly designed Raft slabs all over the world, on sand ,soft ground and even mud, but it has to be properly designed with integrated beams and slab where all the steel is in the correct position to resist movement in any direction, then the whole structure simply floats . Obviously it would want to be on level ground, but it's just that as long as it's strong enough the wider the base the more weight it will take before any sinking will occure. Whether piles would be a cheaper or safer option depends on the building I suppose.

[pipoz]

It is really up to the builder what way he goes, but plenty of houses ,factories etc; have been built on properly designed Raft slabs all over the world, on sand ,soft ground and even mud, but it has to be properly designed with integrated beams and slab where all the steel is in the correct position to resist movement in any direction, then the whole structure simply floats .

That’s why the were called RAFT, as part of their design principal is one of floating across/over the ground soil surface and a designed based on a uniform bearing capacity from that ground, giving them an ability to absorbs some differential movement of the ground below, without wall cracking.

"The science is friction", as Roger put it, is not relevant with Raft slab designs.

pipoz

[Galee]

I don't know about sand, but I can tell you beach and chalk don't mix.
A while back in the UK, I bought a property that was built on the beach. It was built on a concrete slab. The back of the property had a full width conservatory with brick walls either end. These were keyed into the rear walls of the bungalow. The conservatory was built on a concrete slab above chalk infill. To cut a long story short, the chalk went soft and shrank and in doing so pulled the rear bungalow wall out. The builder had gone bust and the insurance company didn't want to know.
Apologies for going off topic.

[maximus]

sandy soil excellent

slam dunk

[Thai Shtick]

oldmajor,
You don't need a retaining wall for the raised land if you grass it properly now. There are a number of grasses available that would do the trick,

Hi oldmajor, Plant a couple rows of vetiver grass (หญ้าแฝด) to stop any erosion. I planted it last June along a Klong with great success. It's very hardy, doesn't need a lot of water and it's vertical root system can reach depths of 4 meters making it an outstanding grass for use in soil retention. There are many great websites regarding it's use in Thailand.