What are the disadvantages of a columnar foundation with a channel/angle brace embedded in concrete?

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In this case, the question is about the installation of a house of 2.4 x 6.0 m. However, in the long run, I expect that if not a hut, something else will stand on the same. The situation is complicated by the presence of the slope with a difference of height 40cm.

In the ground poles – at 1m with a sand cushion and the expansion of the bottom. Pillars with fittings D = 8mm. In the ground – a round hole with a drill 200mm. On top – the formwork (boxes) of boards 200x200, with a height of 700mm.

I think it would be a good idea to tie the posts together for rigidity. There is an 80 channel and somewhere the same level of angle. Question: How do I put the channel (angle tube)? Feet or wide (narrow) shelf up? Do I have to attach the embedding bars and weld the channel to them? After all, the design is not heavy, and the channel was treated solely as a strapping, without the function of support for the house.

Nevertheless, it turns out that the channel performs the role of the beam. Maybe install it below rather than on top of it?

I was thinking of just inserting the channel into the boxes. To make sure there are no voids, to sink the metal into the mix just poured...

What is wrong with my plan? Or how best to complete the strapping of the posts already ready for concreting, with or without the use of the channel bars, with minimal cost? That said, there are difficulties with welding.

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Answer

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The figure shows not a pile foundation, but a pile foundation with a camouflaged extension. The depth is not enough, because the regulatory depth of seasonal freezing in the middle belt varies from 1.2 to 1.8 m, and the calculation also depends on the soil. If the soil is even moderately friable, the piles will pull out. Before you design, let alone build, you need to conduct engineering and geological surveys, even if minimal. For a house to suffice two wells on 2-3 m, it is quite possible to do, even with a garden drill. You should at least have an idea of the types of soil (clay, loam, sandy loam, sand, peat), particle size distribution (for sand) and consistency (for clay soils). If at least 1.5 m of sand (of any coarseness), loam or clay of tight consistency (hard and semi-hard is even better) it will be enough to slightly deepen the foundation blocks (about 30 cm). For clay soils you will need a sand cushion, possibly tamping crushed stone into the holes. Before laying the pillow be sure to lay a geotextile with a conclusion to the surface. The number of blocks and the depth of embedding is quite realistic to achieve an even support for the cabin. Enough 8 supports. In the same way put a hut friend on highly permafrost loams, the fifth year stands perfectly straight.

  • What do you mean, two wells are enough if you need eight or nine? Are the others at a shallower depth? And with a 2 or 3-meter garden drill? I have not met such drills. Geotextile in this option will serve as a jacket for the entire post – throughout the depth. What, will the roofing feel bad? 
  • You misunderstand me. There are enough 2 wells to study the geological structure, 8-9 drills for large industrial buildings. There are drills with extensions, there are 2 m for sure. Geotextile is not for the post, but for the foundation block, so that the sand from the pillow does not mix with the clay soil (if it is clayey there). You can't design a foundation without having an idea of what it will stand on
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