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BANGKOK 19 June 2019 16:29
JestSetter

Piling cost and experience using piles

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The land we have is near a stream (about 30 m.) and rice paddies are about 20 m. away. I went to visit a Thai owner of a restaurant/inn that is 2 level high (and whose property also is flanked by a canal) and that is about 500 m away. He decided to use piles and recommended we did too. He suggested not to do a soil sample as he figured it would most likely reveal that we would need piles as our house has 2 levels too. We would save 15000 B. He recommended to use 12 of them for a 80 m2 area, which seems to coincide with the number of footings. We do not know where the rock is in our land, but he remembered his being about 8 m. long. Looks like the cost for piling 12 piles would be around 100 K. 

 

If you had to use piles, can you please share your story and tell us the price to put them in.

 

I never had to do this, but I have a few question related to the operation when the solid ground below happens to be uneven. Do they fill the hole to to even it out? With what? gravel? Concrete/cement? There are different shapes of piles too. Not sure why? How are the piles tied in to the foundation slab? We are told that they come in set lengths. Do they cut the lengths of those? Do those prefab piles have rebars in then? What type of concrete grade?

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Addendum: A conversation with the man that does the piling (and the soil testing) seems to indicate that a soil sample is needed even if the piles hit the bottom rock. Assuming that the piles are connected at the foundation level and that unevenness of the rock is dealt with, I am surprised that they still need to test the soil. I hypothesize that perhaps the lateral motion of the pile needs to be controlled. By knowing the "tension"  that the soil will impart on the piles (laterally) they will know the shape and diameter size of the piles to be used. Is that what it is?

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Most driven piles in Thailand are "friction piles" which means they are not driven to rock but driven to sufficient depth that the relies on the friction between pile and below ground material being able to support the down force of the structure. Usually the local "pile driving" contractor has the experience in the area to give advice on depth, as for the number of piles that really depends on the size of the building - if in doubt on the number, you should consult an engineer. 

Usually the piles will end up at various heights above ground, these are then cut off to the same level and steel reinforced pile caps poured to a common height to suit. 

Edited by Artisi
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11 minutes ago, JAS21 said:

Here is an option ... https://www.youtube.com/watch?v=ecZp53Evj1k   used them for our carport.

 

Across the road I saw them use 20M piles (Bangkok) ... they used the drill, tube and pour concrete method.

 

Thank you. That is exactly what I was looking for. These are called helical piles. That seems like a smart technology. But I am told they are expensive. I will email them and find out.

 

The company you find that uses helical piles is in BKK. Now, the BIG issue is that I don't live in BKK, but Chiang Mai. Is there someone who has the machine to put this into the soil here? I will email them. Thank you.

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1 hour ago, Artisi said:

Most driven piles in Thailand are "friction piles" which means they are not driven to rock but driven to sufficient depth that the relies on the friction between pile and below ground material being able to support the down force of the structure. Usually the local "pile driving" contractor has the experience in the area to give advice on depth, as for the number of piles that really depends on the size of the building - if in doubt on the number, you should consult an engineer. 

Usually the piles will end up at various heights above ground, these are then cut off to the same level and steel reinforced pile caps poured to a common height to suit. 

That's interesting! They rely on friction. I wonder how much friction they can "create".

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I wonder what is most effective beside pile end-bearing piles and helical piles. Is increasing the surface area out of concrete (increasing the surface tension) of the foundation area outside the area of the house also effective in preventing settling, cracks,...?

Edited by JestSetter

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24 minutes ago, JestSetter said:

That's interesting! They rely on friction. I wonder how much friction they can "create".

At the correct surface area driven to the right depth sufficient to support your house. 

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1 hour ago, JestSetter said:

I wonder what is most effective beside pile end-bearing piles and helical piles. Is increasing the surface area out of concrete (increasing the surface tension) of the foundation area outside the area of the house also effective in preventing settling, cracks,...?

For a house, I would think there is virtually no difference between driven and screwed piles as far as load bearing is concerned. 

In reactive soil, you are not relying of foundation surface are  to support the structure - you are relying of the piles. 

As you seem to have a number of concerns, I would suggest hiring a competent architect or engineer to put your worries at rest.  

Edited by Artisi
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1 hour ago, Artisi said:

At the correct surface area driven to the right depth sufficient to support your house. 

I was looking for a formula. 

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This is my last question. I am trying to understand the physics behind those concrete piles. I am just curious. 

 

So, If my eyes are not failing me, even though those concrete piles do not seem to be shaped like nails, but more like elongated rectangular prisms, the soil around them would still exert enough friction to hug the surface of the pile after the hole has been made. Is this correct?

Edited by JestSetter

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1 hour ago, Artisi said:

For a house, I would think there is virtually no difference between driven and screwed piles as far as load bearing is concerned. 

In reactive soil, you are not relying of foundation surface are  to support the structure - you are relying of the piles. 

As you seem to have a number of concerns, I would suggest hiring a competent architect or engineer to put your worries at rest.  

Thanks for the explanation. Fascinating.

 

I will. Thanks.

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12 minutes ago, JestSetter said:

This is my last question. I am trying to understand the physics behind those concrete piles. I am just curious. 

 

So, If my eyes are not failing me, even though those concrete piles do not seem to be shaped like nails, but more like elongated rectangular prisms, the soil around them would still exert enough friction to hug the surface of the pile after the hole has been made. Is this correct?

in theory - yes.

One of many articles - please enjoy ?

https://bestengineeringprojects.com/pile-driving-formula-engineering-news-formula/

Edited by Artisi
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 if I remember my physics a long time ago at Uni, there is a coefficient of friction consideration,  where the ratio of force necessary to move  one surface  against the other and the pressure between then is considered in making calculations. I suspect the soil test required to determine the length of the piles necessary 

I dont remember the price because it was included in the whole build price.

We hit berrock after a few meters and you could feel the ground shaking  as the piles were hitting the rock and were not being driven anymore so we stopped driving as not to damage them, then a hole was dug a meter deep if i remember correctly, cut the piles at the bottom of the hole , a 1x1 m pad was poured and a footing column was poured to the desired height at ground level. 

image.png.f928ef9e1c8fe5b116fb6e7c516fd4ec.png

23131182_525538434461165_1601604057_o.jpg?oh=0529388fd6c41288a4d0a638845ffa39&oe=59F8F5A0

and then beams to support the ground slab.

22882205_524866844528324_350450374_o.jpg?oh=ca16e42b81dd2c3cf29da7991b6ce900&oe=59F8FBF8

Good luck with your build. Look forward to seeing a thread of it in TVF

Edited by sirineou
missing portion
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There is an equation, like I had seen when the piles were driven for a wharf

 

It went something like this 

 

After 5 belts with the Pile Driver, if they didn't go down a centimeter or 2 they were fine

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