To choose and calculate the base, it is necessary to know several important soil characteristics on construction site. To take samples and to draw conclusions on type of soil and its humidity it is possible independently.
The first that the builder has to learn about the site, is type of soil and its bearing capacity. Soil density directly depends on that, underground waters how close approach surface. These indicators are decisive for the choice of type of the building which will be built on this construction site.
How independently to define, the level of soil dampness and its type?
At first it is required to take samples of soil at depth of 20-25 cm and 90-100 cm. For this purpose dig out holes and take soil sample. Then in turn each of them is pounded between palms so as if wishing to receive round and long "sausage". Further draw conclusion, being guided by the following regularities:
- If the soil "rolls down" well, flexible and elastic, and palms become damp, so at this level of bedding on the site the clay layer with high content of water.· is located if "strip" quite fragile turns out, with cracks at the edges are semi-damp loams.· when the soil in the course of rolling down is scattered on small lumps – sandy loam.· from dry sample with the high content of sand it is impossible to receive "sausage". And than grains of sand are larger, especially soil bearing capacity is high. • To define, underground waters how highly approach, dig out pole of 2-meter depth and observe whether water accumulates at the bottom. If this is so, then UGV (level of underground water) on the site high.
Rules of calculation of the base depending on level of underground water
Houses with lightweight (karkasnik, from foam concrete blocks and gas concrete, from sendvich-panels, panel board, adobe) can be put on MZL (melkozaglublenny continuous footing) if UGV in this area is below its sole on 20-40 cm. If UGV above these marks, suit ring drainage. At the UGV low level (water is lower than 5-6 m from the surface of the soil) it is possible to build heavier buildings (brick, from glued bar, concrete blocks or plates), for which the buried continuous footing can form basis (its sole has to be lower than point of freezing of soil on 20-30 cm). The basis from monolithic plate at high UGV needs to be built on "floating" pillow as the soil on the site saturated with moisture and strongly puchinisty, irrespective of its type. The pillow of the base will act as the shock-absorber and destruction of the base will not happen. Pier foundation can be established at any UGV, but if it high, is required to make drainage. Screw piles – the optimum choice for the mobile and saturated with moisture soils. Not to be mistaken with the choice of type of foundation of the house and calculation of depth of its underlay, it is necessary to know about what SFP (soil freezing point) in this region. After the analysis of the revealed characteristics of construction site make the decision on what base for these conditions will be the most reliable.