Filtration on piles is the best solution for structures erected on weak or unstable soils. The main purpose of this design is to combine load-bearing elements into a monolithic structure, which gives the building an additional margin of safety and reliability. This technology provides for the presence of reinforced bored piles, the diameter of which varies within 25–40 cm, driven into the ground to a depth of 1.6–3 m.
Arrangement of the foundation using this technology gives the structure greater reliability and stability. This is due to the fact that the grillage on piles holds and fastens vertical load-bearing structures together. Thus, it gives additional strength to the structure and counteracts the forces of frost heaving of the soil. The pile field for grillage on piles consists of vertical supporting structures installed at intervals of one to one and a half meters, depending on the type of soil and on the depth of the frozen layers.
To lay this structure, a shallow trench of approximately 30–40 cm is dug around the entire perimeter of future walls. Then, using a special drill, wells are created in it for laying pile structures. An asbestos-cement pipe with a pre-bonded reinforcing cage is lowered inside the holes. Also, the trench is laid out with geotextiles and covered with sand. Formwork is mounted on the resulting pillow. The entire structure is then poured with concrete, which is a very demanding operation.
Here it is necessary to use a special vibrator to compact the mixture and remove air bubbles, which contribute to the formation of cavities of various fractions. This can further lead to cracking of the structure and the collapse of the entire building. A monolithic grillage on piles must be reinforced to make it resistant to bending loads. Otherwise, at the slightest deformation, there will be a threat of concrete cracking.
The grillage is reinforced with two stiffening belts - upper and lower, consisting of several longitudinal steel bars, the number of which depends on the mass, height of the structure and the type of soil on which it is being built. This design is also reinforced with transverse reinforcement, which does not take on the load, but is necessary to bind the entire frame into a single monolith.
Modern large-scale construction uses grillage materials such as steel and prefabricatedreinforced concrete structures of the M350 grade on a granite basis. When constructing wooden buildings from a bar, the grillage is often the lower ledge of the bars, placed directly on the piles. Also, I-beams can be used in this capacity. True, this option is more expensive.
According to the current technological standards, the grillage can be used in the construction of capital brick buildings, as well as in structures made of aerated concrete blocks or wood concrete, erected on clay and combined soil, on soils of medium density and high water saturation.
