Two Storied House on 20 inch Peaty Clay

[KalanaD]

Hello Engineers,

I have done a Bore Hole Test, for my proposed house site, summary of the same is as follows,
Layers = Position ====Layer Description============SPT #
1=====0.0-1.5 m ==Uncontrolled Filling including Debris ==n/a
2=====1.5-2.0 m ==Soft organic Peat clay ===========2
3=====2.0-7.5 m ==Soft lateritic soils ==============3
4=====7.5-10 m ==Completely weathered rock ========5-18
5=== more than 10.0 m ==Basement rock ============n/a

Ground water level is at .6 meters.
Due to the the flooding during rainy season, we are planning to fill the ground for a further 1.5 m from the current ground level, to lift the floor level of the house. House will be a two storied building of roughly 5000 sq feet (460 m²) floor area.
Considering the above factors and information,

My Questions to the specialists are:
1) What would be the most appropriate/recommended & cost effective method to improve the land for the foundation?
2) And any specific methods to use for the foundation?

Thank you very much in advance for your contribution to clear up my doubts.

 

[Ron]

Get a local geotechnical engineer involved to make these recommendations. You have some difficult soil conditions that can give some serious problems with long term performance of your foundation/structure. Not something you want to risk to an internet forum answer.

 

[FixedEarth]

It all comes down to the cost of avoiding foundation failure. Let us say your house costs 500,000 units of money to build. Would you be willing to spend, 1% or 5,000 units on a foundation engineering services? If so call the firm that did the soil boring and ask them to provide you a complete geotechnical engineering report. It seems all you have is just a boring log.

The alternative is to learn soil mechanics the hard way- about 15% of your house cost. This will be used to hire the foundation engineer, structural engineer and a contractor to underpin the foundation. Ron and I should be getting a cut of that 14% right now!

 

[Ron]

FE...I like the way you think!

 

[msquared48]

14% or not, i'd be seriously be considering a pile and grade beam foundation here. As previously entioned, you need a FULL geotech report for that.

What's my cut?

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dik]

Goetekkie is good idea... does the home have a basement? aka, indoor pool? <G>

If using a shallow foundation for poor soils of similar type, I've excavated the poor stuff and replaced with large rock/aggregate... placed using two types of equipment at the same time... one excavating and a front loader dumping the coarse material... and packin' the begeezus out of it... stiffened slab foundation or possibly a raft... talk to a geotekkie and a contractor...

Dik

 

[fattdad]

There is no way to help based on the OP. The soil descriptions do not relate to any standardized soil classification method, we have no classification data (i.e., LL, PI, Percent sand) and there's a liklihood that the soils are better or worse then the OP would suggest (i.e., folks overstate organic content all the time).

When doing construction on peat or true organic soils, it's usually piles, 'cause folks don't want to take the time to deal with surcharges and the engineering analyses required to determine the duration of the surcharge required to mitigate secondary compression. There's also a lot of risk in using spread footings even on surcharged soil.

You could also consider a soil raft, which is like saying, I don't care whether it settles or not, it'll all settle together and I can deal with the utilities and walkways as I need to. Not how I'd spend my money, but folks do. . .

From sketchy information alone, I'd agree it's piles and grade beams. Likely have to consider ventilation of the crawl space too. No idea whether changing water table drives up methane or other swamp gas.

f-d

¡papá gordo ain’t no madre flaca!