Fundamenty na palach
The foundations on piles are then used, when the load-bearing soil is at this depth, where the construction of the described foundations together with earthworks and pumping of groundwater would turn out to be too expensive.
Foundations on piles are a type of deep foundations. The loads from the structure are transferred through the piles to the deeper layers of the soil, more durable than the surface layers. These foundations in the upper part are similar to shallow foundations and therefore are sometimes referred to as shallow foundations on piles.
The benches, plates, the feet and grates do not rest directly on the ground, but at the tops of piles sunk into the ground.
Posadowienie na palach: a) pole piles, b) suspended piles.
The piles are made of wood, concrete, reinforced concrete or steel with a length of several to several dozen meters and are sunk vertically or diagonally in the ground, usually in groups or rows. In practice, there are two cases of using piles:
a) "standing" pole piles,
b) suspended "hanging" piles.
Pole piles (rys.a) are used in cases, when upper, the subsurface layers of the subsoil are completely non-bearing soils, and below them there are load-bearing layers, e.g.. rocks, gravel, coarse sand or solid clay. These piles are led to the load-bearing layers, sinking into compact soils or resting their lower ends on the scales. The total load of the structure is transferred through the piles to the lower, durable soil layer by means of pressure at the lower ends. The upper layers of the soil are not involved in carrying the weight of the structure.
Suspended piles (rys.b) then apply, when the soil is homogeneous or shows slight differences in the bearing capacity of individual layers, and their load capacity is relatively small and increases with depth. These layers take part in the load transmission along the entire length of the piles. Part of the load is transferred to the lower layer by pressure at the lower ends of the piles, however, it is small and can be omitted.
The use of suspended piles is justified in these cases, when their length exceeds the width of the foundation.
Piles can be classified both in terms of material, from which they are made, as well as the method of making or recessing into the ground. Due to the method of making or recessing into the ground, there are several types of piles used in construction.