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House on stilts

House on stilts

House on stilts

(OP)
Hi,

I am a graduate Civil Engineer working in Christchurch, New Zealand.

I am working on a report presenting suitable foundation options for a proposed house.
The floor level has a minimum height of 2.8 m above sea level to meet flood plane regulations thus resulting in a height approximately 1.5 m above existing ground level.

These foundation options have to be in line with Department of building and housing guidelines.

I have done a liquefaction analysis of two dynamic probe results and came up with 127 - 129 mm settlement in ULS design case (0.35g/7.5 magnitude).

Most of the settlement is in the upper 6 m of material.

My two possible options are
Deep piles extending to 9 m depth. Assuming pile embedmant of 1 m and the 1.5 above existing ground level the pile will be approx 11.5 m long. The piles will support a concrete slab

Deep soil mixing to approx 6 m. with 1.5 m of imported fill on top to bring the house to the required level. Resulting in a 7.5 m capping layer of non liquefiable material. Then proceed with a concrete slab on top

I just wanted to see what peoples opinions where on these options and what other considerations i should be thinking of

Cheers
Eirechch

RE: House on stilts

(OP)
Sorry should have changed the name of the thread maybe not the most appropriate name but its just what some people were calling it in the office as i was leaning more to the piles as my first option

RE: House on stilts

What about geofoam encased in a concrete box? Google "geofoam" or styrofoam road beds or something & you will find lots of info; I have done some minor things with it & 2 house foundations that did not get built because of the cost (for the whole projects, not the foundations).

RE: House on stilts

Driven piles sound best, but check on possible failures from lateral loadings of big waves hitting the house. I'd design for much more than vertical loadings or liquifaction.

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