Construction land is all geological formations within the range of the influence of the loads of the erected structures or used for the construction of earth structures (e.g.. dams).
Building grounds are divided into groups and classes depending on their physical and technical characteristics. For each of them, the value of the allowable pressure transmitted through the foundation of the building is defined by building standards. Significant influence on the technical characteristics g.b. has groundwater level and its fluctuations throughout the year.
Construction land belongs to: rocks (geological formations formed during the formation of the earth's crust, usually characterized by low porosity, high strength and low deformability), natural mineral land (containing less than 2% organic parts), natural organic land (vegetable lands, containing more than 2% organic parts) and embankment land (from excavations or workings).
Building land, except for rocks, have a granular structure, they consist of particles made of primary rocks by weathering and crushing them. The grain size distribution of construction soils is determined according to the percentage content of individual fractions of mineral parts (the clay fraction has grains with a diameter smaller than 0,002 mm, dust - 0.002…0,05, sand - 0.05…2, pebble - 2…25, rocky - with a diameter greater than 25 mm).
Mineral construction soil is divided into non-cohesive soil (loose) - containing less than 2% clay fraction and less than 30% dust fraction (gravel, shambles, sands) and cohesive - containing more than 2% clay fraction (clay sands, cops, clay). The cohesiveness is all the greater, the higher the content of clay fraction in construction soils.
The condition of non-cohesive construction soils is characterized by the degree of their compaction, cohesive construction soils - the degree of plasticity. Building land, which under the influence of frost increase their volume by more than 9% the volume of water contained in the pores of the ground - these are heaping soils (such susceptibility to frost is shown mainly by cohesive soils). The size of the plantings depends on the type of soil, its dampness, groundwater level and depth of freezing. The increase in the volume of construction land may cause the lifting of shallow foundations and road surfaces. Non-cohesive construction soil is usually non-sagging. There are also small-planted construction land (uncertain, doubtful) - most often gravel and sand mixed with clay.
The suitability of soil for construction purposes is decisive: the ability of the soil to bear the loads on the structure (compressive strength, shear strength) and the associated resistance to subsidence and ease of earthworks (ease of breakout, the ability to persist, without additional security, walls of excavations and embankments, volumetric weight of the soil).