The blind area is a horizontal protective covering about 1-2 meters wide, located along the perimeter of the building. The design must be waterproof, and in some cases insulated. The protective layer must fit snugly against the vertical outer walls of the plinth or foundation. SNiP 2.02.01–83 states that a blind area is installed near any object. Various materials are used to construct the protective layer; the finished structure is subject to the same requirements - waterproofing, strength, insulation.

Basic requirements of regulatory documentation

The width of the protective layer is determined depending on the subsidence of the soil. Loess or clay soils have different indicators; they are determined in laboratory conditions. According to SNiP standards, there are two main types:

• Type I
• This includes soils in which subsidence under the influence of its own weight is absent or is no more than 5 cm. The structure will experience the main loads from external influences;

II type.

In this case, in addition to subsidence from external loads, subsidence under its own weight is possible to a height of more than 5 cm. The documentation also determines the width of the blind area. If the structure is installed on soils of the first type, then the parameter is at least 1.5 meters, and for soils of the second type - at least 2 meters. When constructing on subsidence soils, all measures are used to lay below the moving layer and additionally special technologies are used. On normally bearing soils, the minimum width of the structure is 0.8-1.0 meters. The eave overhang of the roof must be taken into account; the blind area should be 20-30 cm wider than its size. SNiP has special requirements for thickness

protective structure

In accordance with SNiP, it is necessary to arrange the structure with a slope of at least 10 ppm away from the wall of the building. This means that per 1 meter of the protective layer the slope is more than 1 cm. The maximum value of the slope should not be more than 10 cm per meter of width. If you arrange a covering with a higher slope, the flow of water flows from high speed, which will lead to destruction of the outer edge of the structure. Often on outside The blind area includes water intake gutters with a longitudinal slope.

Control the tilt parameters using a level or level. After installing the heat and waterproofing layers, the indicator should correspond to the original value. To achieve this, slope control is carried out at all stages of work.

SYSTEM OF REGULATIVE DOCUMENTS

IN THE AGRICULTURAL COMPLEX OF THE MINISTRY OF AGRICULTURE OF THE RUSSIAN FEDERATION

INDUSTRY BUILDING STANDARDS

DESIGN OF SHALLOW FOUNDATIONS FOR LOW-RISE RURAL BUILDINGS ON HEAVY SOILS

Ministry of Agriculture of the Russian Federation

PREFACE

1. DEVELOPED: FSUE "TsNIIEPselstroy" of the Ministry of Agriculture of the Russian Federation, with the participation of the State Unitary Enterprise "Mosgiproniselstroy"; Research Institute of Foundations and underground structures Gosstroy of the Russian Federation.

INTRODUCED: FSUE "TsNIIEPselstroy"

3. APPROVED AND ENTERED INTO EFFECT: By the Deputy Minister Agriculture Russian Federation. (11/10/2004)

4. AGREED BY: Department of Social Development and Labor Safety of the Ministry of Agriculture of Russia (05.11.2004)

5. CONSIDERED BY: Department of Economics and Finance of the Ministry of Agriculture of Russia (letter dated February 19, 2004 No. 237-08/354).

1 AREA OF USE

1.1. These standards are intended for the design and construction of shallow foundations of buildings (residential, cultural, household, industrial warehouses, garages and other low-rise buildings) up to 3 floors inclusive.

1.2. The standards do not apply to the foundations of buildings with spacer structures and foundations for equipment with dynamic loads.

1.3. The standards do not apply to foundations composed of permafrost, subsidence, swelling and saline soils, and to the foundations of buildings erected in seismic areas, in mined and karst areas.

2. REGULATORY REFERENCES

3.8. In terms of strength and crack resistance, shallow foundations must meet the requirements of SNiP 2.03.01-84*.

3.9. Measures for anti-corrosion protection of foundations should be carried out in accordance with SNiP 2.03.11-85.

3.10. Work on preparing the construction site and laying foundations must be carried out in accordance with the requirements of SNiP 3.02.01-87.

4. ASSESSMENT OF FROZE HEAVYING OF BASE SOILS

4.1. Heaving soils include clayey soils (in accordance with GOST 28622-90 they are divided into clays, loams and sandy loams), silty and fine sands, as well as large block soils with a clay aggregate content of more than 15% of the total mass, having a moisture content above a certain level at the beginning of freezing .

Coarse soils with sandy filling, gravelly, coarse and medium-sized sands that do not contain clay fractions are considered non-heaving at any level of free-flow groundwater.

4.2. A quantitative indicator of soil heaving is the relative frost heave deformation ε fh equal to the ratio of the rise of the unloaded soil surface to the thickness of the freezing layer.

If groundwater is detected in the surveyed area, the depth of the excavations should be increased in accordance with the data in Table. 2, characterizing the minimum distance Z between standard freezing depth d fh and depth of groundwater d w.

table 2

Excavations should be laid in the most characteristic places of the site (in high and low areas) within the contour of the designed building.

4.6. To determine the relative deformation of frost heaving based on the physical characteristics of the soil, it is necessary to establish:

The granulometric composition of the soil, classifying its type;

Dry soil density ρ d;

Density of solid soil particles ρs;

Soil plasticity: moisture content at the rolling boundary ( Wp) and fluidity ( W L, plasticity number Jp = W L - W P;

Estimated pre-winter humidity W in the layer of seasonal soil freezing;

Depth of seasonal soil freezing d fh.

4.7. The relative deformation of frost heaving of the soil is determined from graphs () using the parameter R f, calculated by the formula

Here Wcr- critical humidity, fractions of units, below the value of which in freezing heaving soil the redistribution of moisture causing frost heaving stops; determined by graphs ();

ρ w- density of water, t/m3;

M 0

W sat- total moisture capacity of the soil, fractions of units, is determined by the formula

(2)

The remaining designations are the same as in paragraph 4.6.

4.8. The estimated pre-winter soil moisture is determined in accordance with. It is assumed that the surface runoff of precipitation that fell on the construction site before the survey in the summer-autumn period is the same as the runoff in the pre-winter period.

5.1.3. On medium heaving (with h fl> 5 cm), highly heaving and excessively heaving soils, the strip foundations of all walls of the building must be rigidly connected to each other into a single structure - a system of cross beams.

5.1.4. Shallow columnar foundations on medium heaving soils (with h fl> 5 cm), highly heaving and excessively heaving soils should be rigidly connected to each other by foundation beams combined into a single system.

5.1.5. When installing columnar foundations it is necessary to provide a gap between the lower edges of the foundation beams and the planning surface that is not less than the calculated deformation (lift) of the unloaded foundation.

5.1.6. If the walls of buildings built on highly heaving and excessively heaving soils are insufficiently rigid, they should be strengthened by installing reinforced or reinforced concrete belts at the floor level.

5.1.7. Sections of buildings having different heights, should be arranged on separate foundations.

5.1.8. Verandas adjacent to buildings on highly heaving and excessively heaving soils should be erected on foundations that are not connected to the foundations of the buildings.

5.1.9. Extended buildings must be cut along their entire height into separate compartments, the length of which is taken as follows: for medium heaving soils (with hfl> 5 cm) up to 30 m, highly heaving - up to 24 m, excessively heaving - up to 18 m.

5.2. Calculation of shallow foundations.

5.2.1. Calculation of shallow foundations is carried out in the following sequence:

a) based on survey materials, the degree of heaving of the foundation soil is determined and, depending on it, the foundation design is selected in accordance with;

b) the preliminary dimensions of the base of the foundation, its depth, and the thickness of the sand (sand-gravel) cushion are specified;

c) in accordance with the requirements of SNiP 2.02.01-83*, the base is calculated based on deformations; in the case where under the sole of the cushion there is soil of less strength than the strength of the cushion material, it is necessary to check this soil in accordance with SNiP 2.02.01-83 *;

d) the foundation is calculated based on soil heaving deformations.

Table 3.

6. FEATURES OF DESIGNING SHALLOW FOUNDATIONS ON A LOCALLY COMPACTED BASE.

6.1. Requirements for soils and foundation design on locally compacted foundations.

6.1.1. Foundations on a locally compacted base include foundations in rammed (stamped) pits or trenches, foundations made of driven blocks.

6.1.2. A characteristic feature of these types of foundations is the presence of a compacted soil zone surrounding them, which is formed by ramming or stamping cavities in the base, immersing blocks by driving.

6.1.3. The depth of foundations should be taken equal to 0.5 - 1 m.

6.1.4. The foundations should have the shape of a truncated pyramid with an angle of inclination of the faces to the vertical of 5 - 10° and the dimensions of the upper section larger than the dimensions of the lower section.

6.1.5. The use of shallow foundations in compacted (stamped) pits or trenches is limited to the following soil conditions: clayey soils with a fluidity index of 0.2 - 0.7 and sandy soils (silty and fine, loose and medium density) when groundwater occurs from the base of the foundations at a distance of at least 1m.

6.1.6. The use of driving blocks is limited to the following soil conditions: clayey soils with a fluidity index of 0.2 - 0.8 and sandy soils (silty and fine, loose and medium density; with groundwater levels at least 0.5 m from the planning mark .

6.1.7. At hfi> 10 cm (where hfi- calculated rise of an unloaded foundation at the level of the base of the foundation during heaving of soil of a natural structure) foundations in rammed (stamped) pits and driven blocks should be rigidly connected to each other by foundation beams.

6.1.8. At hfi> 10 cm foundations in rammed (stamped) trenches should be reinforced.

6.2. Calculation of foundations on locally compacted foundations.

6.2.1. Foundations should be calculated according to the bearing capacity of the foundation soil based on the conditions

Where N- design load transferred to a columnar foundation or 1 m strip foundation;

F d- the calculated bearing capacity of the soil at the base of a columnar or 1m strip foundation, determined in accordance with;

Y k- reliability coefficient taken equal to 1.25.

6.2.2. The foundations of foundations laid on heaving soils are subject to calculation based on the deformation of frost heaving of soils. Moreover, along with the requirements.

Where condition must be met S OT

- settlement of the foundation after thawing of the soil; h fp

- raising the foundation by heaving forces.

Calculation of heaving deformation is carried out in accordance with.

7. 7. INSTRUCTIONS FOR CONSTRUCTING SHALLOW FOUNDATIONS ON A NATURAL BASIS 1. The development of trenches and pits when constructing shallow foundations should be started only after the materials have been delivered to the construction site foundation blocks and that's all necessary materials

and equipment so that the process of constructing foundations is carried out continuously, starting from the construction of pits and trenches and ending with backfilling of sinuses, soil compaction and construction of blind areas. The purpose of this requirement is to comprehensively carry out all work without allowing the foundation soils to become moist.

7.2. All work on site preparation, as well as on laying foundations on heaving soils, as a rule, should be carried out in the summer. IN winter time

the construction of foundations (especially on heaving soils) requires increased production standards, manufacturability and continuity of the entire work process and leads to an increase in their cost.

7.3. If it is necessary to carry out work in winter, the soil in the places where trenches and pits are constructed should be insulated in advance to protect against freezing or artificial thawing should be carried out.

7.4. Preparation of the foundation for a shallow foundation consists of excavating trenches (pits), installing an anti-heaving cushion (on heaving soils) or leveling bedding (on non-heaving soils). ρ When constructing a cushion, non-heaving material is poured in layers no more than 20 cm thick and compacted with rollers, platform vibrators or other mechanisms to a density d

> 1.6 t/m3. For small volumes of work, it is permissible to compact the cushion material using hand tampers.

7.5. Trenches for strip foundations should be cut narrow (0.8 - 1.5 m) so that the openings on the outside of the building can be covered with a blind area and waterproofing material.

7.7. If the groundwater level is high and there is high water on the construction site, it is necessary to take measures to protect the cushion material from silting. For this purpose, the gravel or crushed stone material is usually treated along the contour of the cushion with binders or the cushions are isolated from the effects of water with polymer films.

7.8. A sand cushion, as a rule, should be installed in the warm season. In winter conditions, it is necessary to avoid mixing the cushion material with snow and frozen soil inclusions.

7.9. For the blind area, expanded clay concrete with a dry density of 800 to 1000 kg/m 3 should be used. Laying the blind area can only be done after careful planning and compaction of the soil near the foundation near the external walls. The width of the blind area should ensure that the trench is covered to prevent storm and flood waters from entering it. It is advisable to lay the expanded clay concrete blind area on the ground surface in order to reduce the water saturation of the material. Laying expanded clay concrete in a trench opened in the ground should be avoided. If, for design reasons, this cannot be avoided, then it is necessary to provide drainage under the blind area.

7.10. In order to reduce the depth of soil freezing, it is necessary to provide for turfing the area and planting shrubs that accumulate snow deposition. Reducing the freezing depth can be achieved by using insulation materials placed under the blind area. To prevent soaking, insulation materials can be used, for example, in plastic bags in the form of mats.

7.11. It is prohibited to install shallow foundations on frozen foundations. In winter, it is allowed to build shallow foundations only if the groundwater is deep, with preliminary thawing of the frozen soil and the obligatory filling of the sinuses with non-heaving material.

7.12. When using shallow foundations in buildings with basements, the walls of the latter must be designed to withstand the loads from the foundations.

8. INSTRUCTIONS FOR CONSTRUCTING SHALLOW FOUNDATIONS ON A LOCALLY COMPACTED BASE

8.1. Tamping the cavity in the base is done using attachments, consisting of a tamper, a guide rod or frame, ensuring that the tamper falls exactly in the same place; a carriage with which the tamper moves along a guide rod or frame.

8.2. The carrying capacity of the mechanisms used for compacting pits must be at least 2.5 times the weight of the compactor.

8.3. When constructing foundations in rammed pits, the following requirements must be observed:

Concreting of foundations (installation of prefabricated elements) must be completed no later than 1 day after completion of compaction;

When the clear distance between the pits is up to 0.8 of the width of the foundation, compaction is carried out through one foundation, and missed foundations - no less than 3 days after concreting the previous ones.

8.4. After compacting the pits (trenches), the spreader is placed in them monolithic concrete class not lower than B15 or prefabricated elements are installed with finishing, having dimensions slightly larger than the dimensions of the pits.

8.5. The laying of the concrete mixture and its compaction are carried out in accordance with the work project, standard technological maps and the requirements of the chapter of SNiP 3.03.01-87. The concrete mixture is fed into the pit in uniform layers with a thickness equal to 1.25 working parts of the deep vibrator. Cone draft concrete mixture should be 3 - 5 cm.

Installation and construction of the superstructure begins after the concrete reaches 70% of its design strength.

8.6. Stamping of pits or trenches is carried out using pile-driving units, by immersing in the ground and then removing from it metal stamps having the same dimensions as the foundations being built.

When constructing foundations, it is necessary to comply with the requirements of paragraphs. 8.3.- 8.5.

8.7. When compacting (stamping) pits or trenches in winter, soil freezing from the surface to a depth of no more than 30 cm is allowed.

8.8. When the soil freezes to a depth of more than 30 cm, before starting work on ramming (stamping) pits or trenches, the soil should be thawed to the full thickness of freezing over an area with a diameter equal to 3 dimensions of the rammer (stamp) in the middle section. For strip foundations, the width of the thawed soil patch should be equal to 3 dimensions of the cross-section of the foundation in the middle section, the length - the sum of the length of the foundation and twice the width of the thawed patch.

8.9. After compacting (stamping) pits or trenches to the design level, they must be closed with insulated covers. The thawed state of the soil on the walls and bottom of the cavities must be maintained until the foundations are concreted.

8.10. When the soil freezing depth is more than 30 cm, the driving blocks are immersed in the following sequence:

Drilling leader wells to a depth equal to the thickness of the frozen soil layer;

The diameters of the wells are taken to be 10 - 20 cm larger than the width of the upper edge of the block.

The further sequence of immersion of blocks is established taking into account the properties of the foundation soil:

a) for weak clayey soils with a fluidity index of 0.6 or more and loose water-saturated silty sands:

driving the block to the design mark;

b) for medium-density sands and clayey soils of hard, semi-solid and refractory consistency:

installing the block on the immersion point;

driving the block to 0.5 - 0.7 design depth;

pouring medium-sized or coarse sand into the space between the walls of the well and the submersible block;

finishing the block to the design mark.

Note In case (b), the initial driving of blocks is carried out to a greater depth in stronger soils, and to a shallower depth in weaker soils.

Annex 1
Recommended
DETERMINATION OF ESTIMATED PRE-WINTER SOIL HUMIDITY

The value of the calculated pre-winter humidity is determined by the formula

Where Wn– weighted average value of soil moisture in the layer dfn, obtained during surveys in the summer-autumn period;

Ω s– estimated amount of precipitation, mm, fallen during the summer period t e(months) preceding the time of survey;

Ω os- estimated amount of precipitation, mm, that fell during the pre-winter period (before the establishment of the average monthly negative air temperature) t oc(months), equal in duration to the period t e; values Ω s And Ω oc are determined from the average long-term data of the “Climate Handbook” (L., Gidrometeoizdat, 1968).

Length of period t e, day, is determined by the ratio

at t e< 90°(2)

Where TO- filtration coefficient, m/day.

Approximate values t e for certain types of silty clay soils are: for sandy loam - 0.5 - 1 month, for loam - 2 months, for clay - 3 months.

Appendix 2
Recommended
DESIGN SOLUTIONS FOR CONNECTIONS OF FOUNDATION ELEMENTS

To ensure the joint operation of the elements of shallow strip foundations, the design solutions shown in Fig. 1.

Fig.1Constructive solutions for connecting elements of shallow strip foundations:

a) prefabricated monolithic foundation made of reinforced concrete blocks with reinforcement outlets;

b) foundation made of concrete blocks with armored belts;

c) a foundation made of concrete blocks with a reinforced concrete belt;

d) monolithic reinforced concrete foundation. 1 - monolithic concrete; 2 - prefabricated reinforced concrete blocks with reinforcement outlets; 3 - reinforced belts; 4 - reinforced concrete belt; 5 - monolithic reinforced concrete.

Note . If necessary (determined by calculation according to SNiP 2.03.01-84*), reinforcement of monolithic foundations is carried out with frames.

Appendix 3
Recommended
CALCULATION OF HEAVENING DEFORMATIONS OF THE BASE AND INTERNAL FORCES IN FOUNDATIONS

1. Calculation of heaving deformations of the base and forces in foundations is carried out in the following sequence:

a) the foundation is calculated for stability under the influence of tangential forces of frost heaving;

b) with previously accepted values ​​of the foundation depth and the thickness of the cushion made of non-heaving material, the calculated value of the rise of the unloaded foundation is determined hfi;

c) calculate the average rate of heaving of soil freezing under the base of the foundation V fi:

d) the specific normal heaving force is determined R g,

e) the rise and relative deformation of the base under the foundation are calculated - settlement of the foundation after thawing of the soil; And lfp taking into account the pressure under its sole;

f) internal forces in the foundation caused by heaving deformation of the foundation soil are calculated.

2. The stability of the foundation against the action of tangential forces of frost heaving of soils is carried out in accordance with SNiP 2.02.04-88.

In this case, the coefficient of operating conditions of the base along the lateral surface of the foundation γ τ determined by the empirical relationship:

Where t- width, m, of the sinuses of trenches (pits) filled with backfill made of non-heaving material.

3. If condition (1) is not met, it is necessary to apply anti-heaving measures, including increasing the width of the sinuses, filled with non-heaving material; treating the side surfaces of the foundation with plastic lubricants that reduce tangential heaving forces, etc. A significant reduction in the influence of tangential heaving forces on the foundation is achieved if its side faces are made inclined, i.e. when the width of the upper edge of the foundation is less than the width of its base.

Where ε fh- relative deformation of frost heaving of soil, fractions of units, is determined from the results of soil tests or from graphs (see Fig. 1);

d f- calculated depth of soil freezing, cm, determined according to SNiP 2.02.01-83*.

5. The average rate of heaving of soil freezing below the base of the foundation is determined by the formula

Where hfi- the same meaning as in paragraph 4;

t d- duration of the period, months, of soil freezing under the foundation, equal to

(5)

Where t o- the duration of the winter period, months, is determined according to SNiP 01/23/99.

Values d f And h n the same as in paragraph 4 ().

Table 3

Note . For intermediate valuesh P / b And l/ bcoefficient β determined by interpolation.

η And η 1- coefficients, values which are determined from the graphs (Fig. 4 and Fig. 5).

Fig.3. Addiction ω from TOat different meanings .

Based on the found internal forces in accordance with the requirements of SNiP 2.03.01-84* and SNiP II-22-81, the strength of a shallow strip foundation or foundation beam of columnar foundations is calculated, as well as structural elements building walls.

Rice. 5. Addiction η 1 , from TO at different meanings .

Note: It is allowed not to calculate the strength of wall elements if the conditions are met

13. Taking into account the alternating nature of deformations of foundations made of heaving soils (rise during freezing and settlement during thawing), reinforced concrete elements should be reinforced equally in the upper and lower parts of the sections.

Appendix 4.
Recommended
METHOD FOR DETERMINING THE FLEXIBILITY INDICATOR OF STRUCTURES

1. The flexibility index of building structures is determined by the formula

(1)

Where [ EJ] - reduced bending rigidity, kN.m, of the cross-section of building structures in the foundation - plinth - reinforcement belt - wall system;

reinforcement belt - wall;

L- length of the wall of the building (compartment), m;

WITH- base stiffness coefficient during soil heaving, kN/m

For strip foundations

for columnar foundation bases

Where Ai- sole area i th foundation, m 2 ;

P- the number of columnar foundations within the length of the building wall (compartment).

Values P r, hfi, b- the same as in .

Where Ej, Aj- respectively elastic modulus, kPa, and cross-sectional area, m, j-th connection;

m- number of connections between panels;

dj- distance from j th connection to the main central axis of the cross-section of the foundation, m;

y o- the distance from the main central axis of the cross section of the foundation to the conditional neutral axis of the foundation - wall of the building system, determined by the formula

(14)

wherein P- the number of structural elements in the foundation-wall system.

Appendix 5
Recommended
CALCULATION OF LOAD CAPACITY AND HEAVENING DEFORMATIONS OF FOUNDATIONS ON A LOCALLY COMPACTED BASE

1. The bearing capacity of the base of the driving block, the foundation in a stamped and rammed pit is determined by the formula

()

Where γ y- coefficient of working conditions, taken equal to: 1 - for the driving block; 0.95 - for a foundation in a stamped pit; 0.9 - for a foundation in a compacted pit;

F dσ- calculated bearing capacity of the base on the side surface of the foundation, kN, during settlement s about= 8 cm (determined in accordance with paragraph 2).

K o- coefficient equal to the ratio of the load perceived by the base of the foundation to the total load during settlement S o= 8 cm, conventionally accepted as the limit (determined from Table 1);

ξ - coefficient taking into account the increase in settlement over time, taken equal to: 0.4 - when J L≤ 0.25; 0.3 - at 0.25 ≤ J L≤ 0.6; 0.2 - for J L > 0.6;

S u- maximum average foundation settlement, cm, accepted in accordance with SNiP 2.02.01-83*.

Table 1

Notes: 1. The calculated indicator of soil fluidity is taken equal to its weighted average value within a depth of 1.7d(Where d- foundation depth).

At intermediate values J L and coefficient K o determined by interpolation.

2. The bearing capacity of the base on the side surface of the foundation, kN, is determined by the formula

Where V- resultant of soil resistance forces along the edge of the foundation, kN (determined in accordance with clause 3);

α - angle of inclination of the side faces of the foundation to the vertical, degrees;

A- area of ​​the lateral surface of the foundation face, m 2;

φ y And C y- respectively, the angle of internal friction, degrees, and specific adhesion, kPa, of compacted soil (determined from Table 2).

table 2

3. The resultant force of soil resistance, kPa, is determined by the formula

,(3)

Where λ - empirical coefficient, kN/m (determined in accordance with clause 4);

d

b- foundation width, m, at the level of the planning surface.

4. Coefficient value λ , tf/m 3, determined by the formula

()

Where γa- coefficient of working conditions, taken equal to 1 - at α = 10° and 0.6 - at α = 5°;

λ o- constant value equal to 4.10 4 kN/m 4 ;

d 1- foundation depth equal to 1 m;

J L And d- the same values ​​as in paragraphs 1 and 3.

Note. At intermediate values α coefficient y α determined by interpolation.

5. The bearing capacity of the bases of driven blocks, foundations in stamped and rammed pits, located in fine and dusty sands, may be determined in accordance with paragraphs. 1 - 4, taking J L equal to 0.3 and 0.4, respectively.

6. All other things being equal, the design load on the foundation in compacted trenches can be taken equal to . Meaning F d determined in accordance with paragraph 1 of .

7. The rise of the foundation heaving forces in a rammed (stamped) pit, the driving block is determined by the formula

()

Where V- relative buckling of an unloaded foundation, determined by empirical dependence

wherein

α - angle of inclination of the side faces of the foundation to the vertical, degrees;

d f And d- respectively, the depth of soil freezing and the depth of foundation;

h f- heaving deformation (rise) of the unloaded soil surface of natural structure, determined in accordance with.

N- design load on the foundation (for the second group of limit states), kN;

in which d y- depth of the compaction zone, determined from the expression

(9)

ε fh- the ratio of the average relative heaving deformation of compacted soil to the average relative heaving deformation of soil of natural structure, equal to

Where W And Wp- respectively, the natural moisture of the soil and the moisture at the rolling boundary.

9. The rise of the foundation in a compacted trench is determined by the heaving force acting on it, equal to

Where d- foundation depth, m;

P- the number of side faces of the foundation in contact with freezing soil, equal to 1 and 2, respectively, for heated and unheated buildings;

When calculating the flexibility index TO the base stiffness coefficient should be taken: for strip foundation

(14)

for columnar foundation

(15)

Where h f- rise of unloaded soil surface, m;

l 1= 1m,

P- number of columnar foundations within the length of the building L, m.

When determining ω values ​​are accepted: for strip foundation for columnar foundation

Where q- load transmitted to the foundation of 1 m of wall, kN/m.

12. Internal forces in the foundation (foundation beam) - building wall system and in individual structural elements are calculated in accordance with,.

When determining η And η 1 values ​​are accepted in accordance with clause 11 of this Appendix.

Appendix 6.
Information
Basic letter values

Efh- relative deformation of frost heaving;

d fh- standard soil freezing depth;

d w-depth of groundwater;

Z- the minimum distance between the standard freezing depth and the depth of groundwater;

Wp-humidity at the rolling boundary;

W L- humidity at the fluidity limit;

Jp- plasticity number;

W- estimated pre-winter humidity;

R f- parameter for calculating the relative deformation of frost heaving of the soil;

Wcr- critical humidity;

ρ w- density of water;

m 0- absolute value of the average long-term air temperature for the winter period; W sat- total moisture capacity of the soil;

Sr- degree of sand moisture;

hfi- calculated rise of the loaded base at the level of the base of the foundation during heaving of the soil under the foundation;

- settlement of the foundation after thawing of the soil;- the calculated value of the rise of the base due to heaving of the soil under the foundation;

e fp- calculated relative heaving deformation of the soil under the foundation;

S u- limit value of base lift.

Limit value of relative deformation of the base,

F d- calculated bearing capacity of the foundation soil;

U k- reliability coefficient;

condition must be met- foundation settlement after thawing;

ρ d- soil density in dry condition;

W p- weighted average value of soil moisture in the layer d f p;

Ωe- the estimated amount of precipitation that fell during the summer period preceding the time of the survey;

Ω K- estimated amount of precipitation during the pre-winter period;

t os- pre-winter period;

t c- duration of the period;

TO- filtration coefficient;

V fi- estimated average speed of soil heaving;

Pz- specific normal heaving force;

Lfp- relative deformation of the base under the foundation;

γ τ - coefficient of operating conditions of the base along the side surface of the foundation;

t- width of the sinuses of the trenches (pits);

h f- the magnitude of the rise of the unloaded soil surface;

d f- estimated depth of soil freezing;

t d- duration of the period of soil freezing under the foundation;

t 0- duration of the winter period;

α - empirical coefficient;

1 - width of the foundation base;

T- coefficient of working conditions of the foundations under the base of the foundation;

A- area of ​​the foundation base;

D l, Dci, Ψ - empirical coefficients;

R- pressure under the base of the foundation;

ρ - coefficient taking into account the influence of the thickness of the cushion on the immersed state of the underlying heaving soil;

TO- indicator of flexibility;

L- length of the foundation;

E j J j- bending rigidity;

G i A i- shear rigidity;

Ei- elastic modulus;

G i- material shear modulus;

A i- cross-sectional area of ​​the structural element;

M i- bending moment;

F i- shear force;

d i- distance from j th connection to the main central axis of the cross section of the foundation;

y o- distance from the main central axis of the cross-section of the foundation;

WITH- coefficient of foundation rigidity during soil heaving;

P- number of columnar foundations;

γ - coefficient of foundation operating conditions;

m- number of connections between panels;

γ at - working conditions coefficient;

F d b- calculated bearing capacity of the base along the lateral surface of the foundation;

α - angle of inclination of the side face of the foundation;

φ - angle of internal friction;

WITH- specific adhesion;

d- foundation depth;

V- relative buckling of an unloaded foundation;

Nn- heaving force acting on the foundation;

d y- depth of the compaction zone.

The blind area is a simple, but at the same time extremely important element for every home. Therefore, in the process of its arrangement it is necessary to follow some rules. To help in this matter, next we will look at how to make a blind area from different materials in compliance with all norms and requirements.

Blind area - what is the secret to the durability of the house?

First of all, let's figure out what function the blind area actually performs, and whether it is possible to do without it. So, this element of the building, in fact, is a cornice laid on the ground and adjacent to the base. Visually, it resembles an ordinary path, which is made with a slight slope from the house. Thanks to this slope, the blind area drains water from the foundation.

As you know, “a drop wears away a stone.” Therefore, a blind area laid around the house significantly increases the service life of the foundation, and therefore the entire house. Actually, this is its main task. In addition, it is capable of performing additional functions:

• thermal insulation - this allows you to neutralize negative impact soil heaving on the foundation;
• decorative - with a blind area the house has a complete and attractive appearance;
• stabilizing - stabilizes the gas regime of the soil around the house, in other words, prevents the access of oxygen to the soil near the foundation. Thanks to this, plants do not germinate.

In addition, the blind area can serve as a path, as most often happens. From all of the above, it is easy to conclude that theoretically the house can be operated without a blind area, but this will greatly affect its durability, and not for the better.

What do you need to know about the device - soft or hard version?

In order for the blind area to effectively solve the tasks assigned to it, it is necessary to follow the basic rules of its arrangement. First of all, you need to properly deepen the structure. The fact is that most of it is in the ground, and not on the surface, as many beginners think. The depth of the blind area should not exceed ½ of the design level of soil freezing. This allows the blind area to “play” with the ground, but at the same time not lose contact with the foundation.

Another important point– this is an additional waterproofing of the blind area. For these purposes, a waterproofing material is placed at the bottom of the trench and placed on the foundation. A cushion consisting of several layers of sand and crushed stone is laid on top of the waterproofing. To avoid migration of bulk materials, the cushion layers are reinforced with geotextiles. It must be said that a multilayer base structure is a relatively new solution that significantly reduces the cost and simplifies the construction of the structure.

A covering is laid on top of the pillow. Depending on the type of the latter, blind areas are divided into three types:

• hard – means monolithic concrete, asphalt or cement-filled coating;
• semi-rigid - these include blind areas paved paving slabs or other piece materials;
• soft (loose) - made from crushed stone, gravel, pebbles or other bulk material that is poured on top of the pillow.

It must be said that the choice of type of coating depends not only on the landscape design and your preferences, but also on some other factors. For example, a self-leveling cement coating is not suitable for heaving soils, since after the first winter it will crack and become unusable. If you need to insulate the blind area, it is advisable to use a hard covering.

Preparing the pillow - digging trenches and filling the “pie”

Regardless of what kind of coating you use, the installation of a blind area begins with the preparation of the cushion, and it is always performed in the same way. First of all, you need to decide on its width. According to SNiP 2.02.01-83, the blind area, and, consequently, the cushion, must extend beyond the roof overhang by at least 200 mm, while at the same time its width must be at least 700 mm.

Then, having decided on the width, you need to mark the perimeter of the house. A trench is dug according to the markings, i.e. it must correspond to the width of the blind area. As we said above, the depth of the trench is half the freezing level of the soil. A layer of clay 15–20 centimeters thick is placed at the bottom of the resulting ditch - this is an additional water seal. The clay must be carefully compacted and leveled, while ensuring a slope of about 8-12 cm per meter. Then the trench is covered with waterproofing material, for example, you can use polypropylene film or even several layers of roofing material. The main thing is that the waterproofing is wrapped 10 centimeters on the foundation, as well as on the wall of the trench to the level of crushed stone.

To fix the edge, you can attach a strip or corner over it.

Then the waterproofing is covered with a layer of sand at least 3 cm thick. The sand must also be leveled. Geotextiles are laid on the sand and wrapped on the wall of the trench. Then a layer of crushed stone about 9-10 cm thick is poured in and carefully compacted. In this case, a slope of 5-7 cm per meter is formed. At this point, the pillow can be said to be complete. Further actions depend on the material that will be used to cover the blind area. The only thing is that if you do not plan to carry out stormwater drainage around the perimeter of the blind area, you need to make drainage around it.

To arrange drainage, you need to dig a ditch 30 centimeters below the level of the cushion. The bottom of the ditch should be covered with geotextile, the edges of the canvas should be left with a margin of 35 cm. Then a layer of crushed stone is filled in and drainage pipes are laid. The pipes are also covered with a layer of crushed stone on top and wrapped with the free ends of geotextile. The finished drainage system should be drained into a fixed well or connected to storm sewer, if, of course, it exists.

Laying FEMka - a simple and beautiful option

First, let's look at how to make a blind area with paving slabs with your own hands, since this is one of the most common options. Work should begin by laying geotextiles on top of crushed stone with a fold over the trench wall. Next, install a border along the edge of the blind area. To do this, dig a groove along the width of the curb and fill it with cement mortar. The curb can be placed directly on the fresh mortar so that it is set in concrete a little.

To ensure that the border is level, stretch a cord along the edge of the blind area and align the sections of the border along it.

Then the geotextile is covered with a layer of sand at least 6 mm thick. The sand must be compacted, and it is advisable to spill it with water, which will allow it to be compacted more efficiently. It must be said that in the case of using paving slabs, the function of water drainage falls entirely on the waterproofing film. Therefore, there is no need to slope the top layer of sand. The process of laying FEM tiles is standard - you simply lay the tiles on the sand and align them relative to each other, as well as in the horizontal plane.

Here, in fact, are all the nuances of performing such a blind area. It must be said that according to this scheme it is made not only from paving slabs, but also from paving stones. The only thing is that the latter, unlike tiles, needs to be buried a little in the sand.

We make a blind area from bulk materials - one or two and you're done

It’s even easier to make a blind area from crushed stone. Essentially, it follows the same pattern as a pillow. But the crushed stone layer should be thicker, i.e. its thickness should be equal to the thickness of the crushed stone layer of the pillow, plus the thickness of the sand layer, plus the thickness of the coating layer. The result is about 20 centimeters. The surface of the crushed stone is leveled in a horizontal plane. As for the slope, there is also no point in doing it for a crushed stone blind area.

As you can see, the process of arranging a soft blind area is quite quick and simple. However, it has several disadvantages - it is fragility and not very presentable appearance. True, if landscape design decorated in the appropriate style, then pebbles or even ordinary crushed stone around the building can look quite good.

The blind area with a top cement-filling layer is approximately the same. The difference is that the layer of crushed stone should be several centimeters smaller, since the screed will take up this thickness. To fill the solution, formwork must be installed along the edge of the blind area. As a rule, it is made of boards, plywood or OSB. The most important thing is to fix it well so that the formwork does not move during the process of pouring the solution. To do this, you can use spacers and racks.

On the foundation side, before pouring, a sealant must be laid, which is responsible for the construction of the thermal seam and its sealing. Most often, a conventional damper tape made of foamed polyethylene is used for these purposes. A cement-sand mortar of grade M200, about 3 cm thick, is poured on top of the crushed stone. When the mortar begins to set, it is ironed, i.e. a thin layer of cement is poured on top and rubbed in with a small brush. Thanks to this operation, the blind area will become smoother and stronger.

After rubbing in dry cement, it is advisable to cover the surface of the blind area with a dark film, since the iron ripens better without light. To prevent the blind area from cracking during the drying process, you need to sprinkle it with water every day for the first few days.

Concrete blind area - we create it for a long time

The most durable and durable is the concrete blind area. The process of its manufacture begins with the preparation of a sand cushion, as before laying paving slabs. Then formwork is installed around the perimeter in the same way as in the previous case. Before laying the reinforcement, it is advisable to install expansion joints made of wooden planks about 15 mm thick. Compensators should be located perpendicular to the blind area, i.e. between the foundation and the formwork. The distance between compensators should not exceed 2.5–3 meters.

Since the planks will remain in the thickness of the concrete, they must first be treated with a protective antiseptic agent and bitumen mastic. Thanks to this, they will last for decades. When installing compensators, try to align their ends in the same plane with a slope of 10 cm per meter. As a result, the planks will additionally serve as guides.

After installing the formwork, a damper tape is laid along the wall and reinforced with reinforcing mesh. Its optimal dimensions are 100x100x4 mm. Keep in mind that the mesh should not lie on the pillow, so you need to place special stands or small stones under it. Otherwise, the grid will not perform its functions. After this, concrete work begins. First of all, you need to prepare a solution from the following ingredients:

• cement grade not lower than M400 – 280 kg;
• crushed stone – 1400 kg;
• sand – 840 kg;
• water 180–200 l.

Let me remind you that cement and sand are first mixed, then water and filler are added. The solution will turn out very dry, but don’t let this bother you. This consistency is necessary so that the concrete can maintain the required slope angle. Filling is carried out section by section. During this procedure, do not forget to compact the concrete. It is best to use special equipment for these purposes, but if you don’t have it, you can use a piece of reinforcement. During the compaction process, try not to displace the reinforcement mesh, as this will reduce the strength of the concrete.

After filling the blind area, expansion joints can be coated with construction sealant to eliminate the possibility of moisture penetrating into them. After the solution has set, it is advisable to carry out ironing according to the scheme described above. Do not forget that the surface of the concrete blind area must be moistened with water for the first few days.

A few words about thermal insulation - why does the soil need heat?

Insulation of the blind area may be necessary in the following cases:

• the house has a heated underground room (ground floor or basement) - in this case, insulation will reduce heat loss;
• the house is built on heaving soil - insulation will prevent the soil from freezing;
• several times during the season, the freezing depth may exceed the design value according to SNiP, i.e. the soil freezes to the very base of the foundation.

As mentioned above, it is better to carry out insulation under a concrete blind area - this will achieve the greatest effect. As for the choice of insulation, the optimal solution is extruded polystyrene foam. This material is not afraid of moisture, can withstand heavy mechanical loads and is very durable. Its only drawback is its high cost.

You can, of course, use regular high-density polystyrene foam (foam). However, it is advisable to waterproof it. As for the insulation process itself, everything is quite simple - the slabs are laid on a sand cushion, and then a concrete blind area is made along standard scheme. The main thing is to install the insulation correctly to prevent the appearance of cold bridges. Therefore, it is advisable to use conventional polyurethane foam for thermal insulation of seams.

Here, perhaps, are all the main points of arranging the blind area. Taking into account all these nuances and subtleties, you can reliably protect the foundation from moisture.

A properly insulated blind area is a structure consisting of several layers: waterproofing material, insulation, drainage. Insulating the blind area prevents the destruction of the foundation and walls of the house, washing out the soil, and also when constructing a building on heaving soils, it helps to avoid the destructive effects of soil freezing.

Insulation scheme for the blind area

To properly insulate a blind area with your own hands, you need to know the device and follow the order of the layers of the “pie”.

1. The lowest layer is geotextile. This is the layer that forms the entire structure.
2. The next layer of 10-15 cm is sand.
3. A layer of insulation is placed on top of the sand mound.
4. The next layer is again sand 15 cm.
5. Geotextiles again.
6. A layer of fine crushed stone.
7. Decorative tiles (or other material).

Why is the blind area around the house insulated?

Insulation of the blind area is necessary in order to protect it from premature destruction due to soil heaving in winter.

This event has other important functions:

• Reducing home heating costs;
• Reducing shifts of the blind area in relation to the base of the building.
• Improving the waterproofness of the blind area;
• Possibility to reduce foundation depth.

On heaving soils, to determine the depth of the foundation, the depth of freezing is of decisive importance, even if technical requirements allow less penetration.

And, vice versa: on low-heaving soils, the depth of laying the foundation does not depend on the amount of soil freezing in depth. The depth of its occurrence is dictated design features Houses.

Features of insulating a blind area with your own hands

When insulating the blind area of ​​a shallow house foundation, you can ignore soil freezing. Thus, even if you spend money on installing an insulated blind area, the savings will be very significant.

Insulation is a costly undertaking, but unreasonable savings can render all efforts futile. The work will only make sense if you simultaneously insulate the blind area, basement and foundation with your own hands.

The width of the insulation of the blind area must be no less than the freezing value of the soil.

Insulation of the base and blind area with polystyrene foam (penoplex slabs)

The best option would be to insulate the blind area with extruded polystyrene foam. Penoplex insulation is carried out in places where it is impossible to use other insulation materials. For example, in excessively humid conditions.

In addition, it has other advantages:

• high compressive strength;
• zero water absorption and vapor permeability;
• durability;
• ease;
• frost resistance;
• low flammability;
• environmental friendliness.

To insulate with penoplex with your own hands, you need to use 50 mm sheets in two layers or 100 mm sheets in one layer. The joints of polystyrene foam sheets will be protected by high-density polyethylene. To do this, it is laid on top of a layer of polystyrene foam boards.

PPU insulation

Polyurethane foam can be applied to any complex surface and therefore is used almost everywhere in house construction.

Positive properties of polyurethane foam:

• Has low thermal conductivity;
• Biologically resistant;
• Resistant to decomposition;
• Used at both low and high temperatures;
• Requires 2-3 hours to complete all work;
• Resistant to fire;
• Has low water absorption;
• The application layer has integrity, without gaps.

The disadvantage is the toxicity of one of the components of the material, which requires protective measures when spraying the product.

Insulation with expanded clay

This is one of the most common materials for do-it-yourself insulation of different parts of the house. It is effective and fireproof. It differs in the size of the granules (from 2 to 40 mm): gravel, crushed stone and sand. Expanded clay sand is used as a filler for concrete solutions. Expanded clay gravel is more frost-resistant and water-resistant than sand and crushed stone. It is used mainly for do-it-yourself insulation of basements, garages, as well as basements and blind areas.

Insulating a blind area with expanded clay does not require high costs or special knowledge. A layer of clay and waterproofing is laid in the excavated recess for the blind area, with sand and sand on top as protection against subsidence. Then expanded clay and again a layer of dronite and sand. On top there is crushed stone for the design of the territory.

Expanded clay is absolutely harmless and protects the foundation well from moisture penetration. Plus, it's very cheap.

An important stage of insulation is the installation of drainage. The groundwater level in wet areas is about 1 meter. When wet, expanded clay loses most of its thermal insulation properties; because of this, water should be drained away from the house.
A trench is dug at a distance from the base of the house, geotextiles, a layer of crushed stone and pipes are placed in it. Drainage pipes are covered with a layer of crushed stone, the edges of geotextiles and covered with sand.

Do-it-yourself blind area

An insulated blind area is important for arranging houses on damp, heaving soils. With the onset of severe frosts, soil saturated with moisture can begin to shift, rise and destroy the foundation. With warming, the reverse process begins - the soil settles, which also negatively affects the foundation of the building.

The main purpose of insulation is to prevent these processes. If you know the layout of layers and the main stages of work, then even a beginner can do insulation. Penoplex insulation is easy to use and effectively protects the lower elements of the building from the cold.

The work process includes the following stages:

1. Arrangement of space for subsequent manipulations. The area is cleared, the roots are removed, the top ball of earth with vegetation is removed to the depth of the insulation layers. It is necessary to correctly calculate this value, it depends on the heat technical characteristics.All vegetation is carefully removed, since in the future it will destroy the blind area and the structure itself with its root system.
2. Crushed stone is laid on the cleared area as a drainage layer. It is necessary to calculate its layer by subtracting the thickness of the facing tiles and sand cushion from the height of the turf layer.
3. The dug recess is surrounded around the perimeter with formwork. Protection against moisture penetration should be made of clay, which is distributed over the ditch and compacted with a layer of 25 cm.
4. The next layer of sand is poured and watered to ensure shrinkage.
5. Extruded polystyrene foam is laid on a layer of sand.
6. Paving slabs or other material are placed on top of the polystyrene.

For work on arranging the insulation of a blind area with your own hands, you need to carefully prepare and decide on the choice of thermal insulation material. The possibility of using any specific material is decided individually in each particular case. If everything is done efficiently and correctly from a technological point of view, the result of the work will delight you for many years.

From the point of view of material investments, a shallow foundation is the optimal solution for the construction low-rise buildings. But in this case, an insulated blind area and base will be required, especially if construction is carried out on heaving soils. This technology will help protect the soil from freezing near the building, protect the foundation from subsidence and deformation, and protect the walls from cracks and destruction.

When insulation is required

Even a schoolchild knows why a blind area is needed. But not every adult will be able to answer the question - why insulate it. The fact is that this needs to be done only in two cases:

• with a shallow foundation;
• if there is a heated basement floor.

The functions of the blind area located around the perimeter of the box include protecting the foundation and basement from direct penetration of rain or flood water directly under the building. Insulating the blind area with a shallow strip foundation, moreover, prevents freezing of the soil outside the underground structure and prevents frost from penetrating into the underground. This is especially important when building a house on a site with heaving soils. The fact is that as they freeze and increase in volume, they will begin to push the foundation upward, and in the spring they will thaw unevenly. And this is fraught with shrinkage, deformation and other troubles.

When the foundation is laid deeply, the blind area does not need insulation.

How to insulate the blind area

The technology allows the use of several materials to insulate the base and blind area after the construction of a shallow strip foundation. This:

• polyurethane foam;
• extruded polystyrene foam boards;
• Styrofoam;
• expanded clay;
• mineral wool, etc.

The laying depth and thickness of the insulation directly depends on its technical characteristics and the climatic conditions of the construction region. Modern foam materials, even with a relatively small thickness of the “warm” layer, are considered more effective than mineral wool and expanded clay, which is why they have been steadily in demand recently. But it is necessary to remember that, regardless of the choice of thermal insulation material, waterproofing of the structural elements of the structure and layers of the blind area must be carried out. The technology defines this stage as important due to the fact that the lack of waterproofing makes insulation absolutely useless.

Foam materials have virtually no disadvantages and have numerous advantages:

• light weight;
• low thermal conductivity;
• high frost resistance;
• almost zero water absorption;
• absence of rotting and decay processes;
• durability;
• environmental friendliness.

The technology for laying slabs outside the house is quite simple and does not require special knowledge.

It should be noted that polystyrene foam does not have the advantages of extruded polystyrene foam, popularly known as “penoplex” (which is, in fact, a trademark). Polystyrene foam absorbs moisture, after which it loses heat resistance, but this drawback can be solved by installing reliable waterproofing. Other negative properties of the material relate to its fragility and weak strength, which leads to a violation of the integrity of the blind area.

Foam plastic slabs can be damaged not only from mechanical impact from the outside, but also from ground movements. In the first case, you can protect the insulated blind area from destruction by strengthening the top layer with paving slabs, stone, or a layer of asphalt or concrete, and in the second case, by depriving the slabs of any contact with heaving soils. The only advantage of polystyrene foam is its low cost compared to similar insulation materials, but correcting the result of such savings can be costly.

More suitable option For insulation of the outside of a shallow foundation and blind area, extruded polystyrene foam is used. Its operation can be carried out in a wide temperature range, so the material is used both in the southern and northern regions of the country.

Polyurethane foam is sprayed over the surface in an even layer. The coating has no seams, does not deform when the ground moves, and is applied fairly quickly. But the technology requires special equipment and the presence of qualified workers. In this regard, private homeowners rarely choose the option of insulating the blind area with polyurethane foam.

The process of insulation with polystyrene foam boards

It is recommended to carry out work on insulating a shallow foundation at the stage of building a house, even before completing backfill sinuses, but after installing waterproofing. But often problems arise during the operation of the house, when there is no open access to the underground part. In this case, a trench is dug along the perimeter of the box to the level of the base of the strip foundation, after which the condition and integrity of the waterproofing is checked. It is updated if necessary.

First, polystyrene foam boards are glued onto the prepared vertical surface. At the corners of the house, the thickness of the insulation is laid, increased by 1.5-2 times compared to ordinary sheets. From the outside, the insulation is protected with a special profiled film. Next, the sinuses are filled with layer-by-layer compaction to the level of the base of the blind area.

Work should be performed carefully to avoid damage to the protective film or sheets, otherwise the defective areas will have to be redone.

Taking into account the width of the blind area (60-100cm), which should protrude beyond the house by at least 20cm more than the roof overhang, a trench is prepared along the entire perimeter of the house. Its depth for southern and middle latitudes is, as a rule, 20 cm, and for northern latitudes – 40 cm. The bottom of the trench is compacted, after which a layer of waterproofing and a 10-20 cm sand cushion. Expanded polystyrene sheets are placed on top, then sand or a sand-gravel mixture, then a masonry mesh.

If it is necessary to lay insulation slabs in two rows, you should pay attention to the location of the joining seams. They should not be combined in the vertical direction. For ease of concreting, removable formwork is installed above the edge of the trench.

At the last stage, the blind area is filled with concrete in compliance with the design slope. To prevent the concrete surface from cracking during operation, transverse expansion joints should be installed at a distance of 2.5-3 m along the length. They are carried out using bitumen-coated wooden slats installed “on edge”.

The top covering of the blind area must be waterproof. This could be, for example, paving, painting, paving or reinforced concrete.