# Insulated foundation

(57) Abstract:

The invention relates to the construction and erection of buildings and structures on freezing swelling soils. The technical result consists in the possibility of laying the Foundation higher than the expected depth of frost heaving of soils and transfer the load across the surface of the Foundation, which ensures the reduction of the volumes of earthwork and material capacity of the Foundation. Insulated foundations on frozen ground includes a rigid body with tabs and indents on the side facing the ground, and inserts in the indents, the Foundation of material having a modulus that is different from the modulus of deformation of the material of the protrusions, and the liners in the indents made of insulating material, for example polystyrene. The ratio of the areas of the protrusions and indents take so that the pressure transmitted to the ground on the bottom surface of the protrusions is not less than the normal pressure of frost heaving of the soil. At the same time should be provided strength insulating material, and Foundation settlement should be determined taking into account the increased compressibility of insulating material. In customshape equals the total area of the Foundation. 1 C.p. f-crystals, 2 ill., table 1. The invention relates to the field of construction and is used in the construction of buildings and structures on freezing swelling soils.Known to the Foundation, including placed on the ground plate to the liner on the unsupported section of its area facing the ground, and the insert is made of insulating material and is also outside the square Foundation, and the load of the Foundation ground is transmitted through the bearing elements, such as piles (Steel piles TT, TT, TT and TT". Avenue RTG (16)-32615 Company "Suomen Trespalacios", 1991)Lack of Foundation is that the liner performs only the function of thermal insulation of ground and is not used to transfer the load to the soil, which increases the intensity of the Foundation.Closest to the claimed object, the technical solution is the Foundation on frozen ground, comprising a rigid body with tabs and indents on the side facing the ground, and inserts in the indents, the Foundation of material having a modulus that is different from the modulus of deformation of the material of the projections (SU 1539211, MKI 4 E 02 D 27/01 "the Foundation on the natural basis").Nedo estimated depth of freezing.The purpose of the claimed invention consists in providing the possibility of laying the Foundation higher than the expected depth of frost heaving of soils and transfer the load across the surface of the Foundation, which ensures the reduction of the volumes of earthwork and material Foundation.This objective is achieved in that in the base on the frozen ground, comprising a rigid body with tabs and indents on the side facing the ground, and inserts in the indents, the Foundation of material having a modulus that is different from the modulus of deformation of the material of the protrusions according to the invention, the inserts in the indents made of insulating material such as expanded polystyrene, and the area ratio of the protrusions and indents accepted terms and conditions:

- ground pressure on the lower surface of the projections P

_{sun}should not be less than the normal pressure of frost heaving of soil P

_{standards}< / BR>

P

_{sun}P

_{standards}(1)

- ground pressure on the lower surface of the liners P

_{VK}should be no more than the values calculated resistance of the material of the liners in compression R

_{SG}.P

_{VK}R

_{SG}(2)

- sludge Foundation calculated with the and S

_{before}.S S

_{before}(3)

In addition, according to the invention, the size of the indents with inserts A

_{VK}may be taken equal to the total area of the Foundation of A

A

_{VK}= A (4)

The thickness of the liner in the indents H

_{VK}installed by thermotechnical calculation of the conditions to prevent freezing of the ground through the body of the Foundation within the liners. The initial liner thickness H

_{VK}must be increased by the amount of compression of the liner during subsequent application of the load.In the proposed Foundation of the freezing becomes possible only through the body of the projections. The stability of the Foundation under the action of normal forces of frost heave in freezing soils provided that passed for soil pressure within the projections P

_{sun}is such that it is not less than the value of normal pressure frost heaving of the soil P

_{standards}. This requirement reflects the condition (1). It is known that when the pressure on the sole Foundation in excess of P

_{standards}the strain of heaving is not manifest.At the same time the pressure on the ground within the liners in the indents P

_{VK}should not exceed the design resistance of the material of the liner is x2">The presence of inserts in the indents of the Foundation that are performed, usually more compressible than the Foundation of the material, determines the education Foundation settlement in excess of the average draught of a solid Foundation without taking into account the compressibility of liners, which are calculated on the assumption bearing directly on soil S

_{cf}. Therefore, condition (3) defines the S

_{cf}. Therefore, condition (3) specifies checking the possible settling of the Foundation, taking into account the compressibility of the material of the liners.In the extreme case it is possible that under the conditions (2) and (3) the total size of the indents with inserts A

_{VK}can be according to condition (4) is estimated to be equal to the total area of the Foundation A. the Foundation turns into a hard body with a flat sole and a solid insulating spacer between the ground and the sole Foundation, through which the load acting on the Foundation, transmitted to the ground.A set of proposals provides an implementation of goal - reducing the amount of excavation work and material capacity of the Foundation by providing the possibility of laying the Foundation higher than the expected depth of frost heaving of soils and re>When analyzing the level of technology is not revealed similar, characterized by signs, identical to all the essential features of the proposed solution, i.e., it meets the requirements of novelty.Not detected signs that are distinctive in the inventive solution, i.e., it meets the requirement of inventive step.The invention is illustrated by drawings: Fig. 1 shows an insulated basement, loaded with load N and sunk into the soil to a depth D of Fig. 2 depicts a plot of pressure distribution on the ground on his soles.The Foundation (Fig. 1) includes a rigid body 1, made of reinforced concrete, with 2 tabs and indents 3 from the side adjacent to the ground, and inserts 4 EPS posted in indents 3 and at some distance outside of the Foundation 5. The inserts 4 are the modulus of deformation E

_{VK}other than the modulus of deformation of the material of the protrusions 2 - reinforced concrete, and are protected from exposure to groundwater, for example, by coating of hot bitumen.For example, illustrating the invention, taken with the following initial data:

- the load on the Foundation (including its weight) N = 1100 kN;

- size of the soles of the Foundation (linoleum P

_{cf}= 0,22 MPa;

the depth of laying the Foundation D = 0,50 m;

- modulus of the material of the inserts 3 in indents 2 (expanded polystyrene) E

_{VK}= 1 MPa;

is the calculated thickness of the liners 3 H

_{VK}= 0.1 m;

- current resistance of EPS R

_{SG}= 0.2 MPa;

- estimated depth of soil freezing D

_{f}= 1.9 m;

- normal frost heaving pressure P

_{standards}= 0.3 MPa;

- the calculated soil resistance R

_{g}= 0.32 MPa;

- the average precipitate a solid Foundation without taking into account the compressibility of the liners S

_{cf}= 2,89 cm;

the coefficient for the soil Foundation (P

_{cf}/S

_{cf}) K

_{about}= to 7.61 MPa/m

To select efficient ratio = A

_{sun}/A the squares of the projections 2-A

_{sun}the total area of the Foundation made A calculation pressure of the soil on the lower surface of the protrusions 2-P

_{sun}and inserts 4-P

_{VK}, as well as the resulting precipitate of the Foundation, taking into account the compressibility of the liners 4 S. Calculations made according to the formula:

< / BR>

< / BR>

< / BR>

The results of calculations for different values of the relative area of the protrusions () presented in the table.The table shows that the optimal ratio is = A

_{sun}/A, Rasnov>sun= 316 kPa does not exceed the calculated ground resistance R

_{g}= 320 kPa, and the conditions defined by the formula:

(1): P

_{sun}= 316 > P

_{standards}= 300 kPa;

(2): P

_{VK}= 179 < P

_{SG}= 200 kPa;

(3): S = 4,14 < S

_{before}= 10 cm

The dimensions of the Foundation shown in Fig. 1, provide the specified ratio = A

_{sun}/A = 0,3..The pressure distribution on the sole basis for the adopted value = 0,3 shown in Fig. 2 in the form of plots, 6 - pressure on the surface of the liners P

_{VK}7 - pressure on the surface of the projections P

_{sun}, 8 - average pressure on the surface of the basement in General, P

_{cf}.Thus, the requirements imposed on the design of foundations in the above example are satisfied.The advantages of the proposed solution Foundation on freezing heaving soils consist of:

compared with base - analogue of (1) providing the possibility of transferring the load to the soil not only through bearing elements, but also directly through the liners, the intensity of the basement in the above example is reduced, in particular, due to the refusal from the use of load-bearing elements (e.g., piles);

in comparison with the deposits heaving soils; in the above example, the decrease in depth from 1.9 m to 0.5 m leads to a reduction in the amount of excavation work 7 times (from 50 to 7 m

^{3}and volume of concrete 1.8 times (3,96 m

^{3}to 2.16 m

^{3}). In addition, in this example, the ratio of the total width of the indents to the full width of the Foundation amounted to 1,6/2,0 = 0,8 (see Fig. 2) that is outside the range 0,5...0,7 specified in the base-prototype (2). In accordance with the invention this ratio may be increased to 1. 1. The foundations on frozen ground, comprising a rigid body with tabs and indents on the side facing the ground, and inserts in the indents, the Foundation of material having a modulus that is different from the modulus of deformation of the material of the protrusions, wherein the liners in the indents made of insulating material, for example polystyrene, and the area ratio of the protrusions and indents accepted terms and conditions: ground pressure on the lower surface of the projections P

_{sun}should not be less than the normal pressure of frost heaving of soil P

_{standards}< / BR>

P

_{sun}P

_{standards};

the ground pressure on the lower surface of the liners P

_{VK}should be no more velocipedist, calculated taking into account the compressibility of the liners in the indents S should not exceed the regulated maximum allowable Foundation for precipitation S

_{before},

SS

_{before}.2. The Foundation under item 1, characterized in that the size of the indents with inserts A

_{VK}equals the total area of the Foundation AND,

A

_{VK}= A.

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FIELD: construction, particularly new building erection and existent building reconstruction under any engineering-geological circumstances.

SUBSTANCE: foundation structure comprises shallow foundation and reinforcement members. Reinforcement members are made as vertical bars of precast or cast-in-place piles having diameters less than 200 mm and arranged along foundation perimeter. The piles are spaced a distance from outer foundation faces. The distance is equal to 0.1-0.5 of reinforcement member diameter. Distance between neighboring piles is equal to 2-4 reinforcement member diameters and reinforcement member length is 15-20 diameters thereof.

EFFECT: increased load-bearing capacity due to creating compressive operational conditions under different engineering-geological circumstances, increased dynamic rigidity of foundation base and reduced foundation deformation and vibrational amplitude.

9 dwg