Benefit on retaining walls to snip. Calculation of retaining walls. Do-it-yourself concrete retaining wall

"Design of retaining walls and basement walls".

Developed for SNiP 2.09.03-85 "Construction of industrial enterprises". Contains the main provisions for the calculation and design of retaining walls and basement walls of industrial enterprises from monolithic and prefabricated concrete and reinforced concrete. Calculation examples are given.
For engineering and technical workers of design and construction organizations.

FOREWORD

The manual was compiled for SNiP 2.09.03-85 "Constructions of industrial enterprises" and contains the main provisions for the calculation and design of retaining walls and basement walls of industrial enterprises from monolithic, prefabricated concrete and reinforced concrete with calculation examples and the necessary tabular values of the coefficients that facilitate the calculation.

In the process of preparing the Handbook, certain calculation prerequisites of SNiP 2.09.03-85 were clarified, including taking into account soil cohesion forces, determining the slope of the sliding plane of the collapse prism, which are supposed to be reflected in addition to the specified SNiP.

The manual was developed by the Central Research Institute of Industrial Buildings of the Gosstroy of the USSR (candidates of technical sciences A. M. Tugolukov, B. G. Kormer, engineers I. D. Zaleschansky, Yu. V. Frolov, S. V. Tretyakova, O. JI. Kuzina) with the participation of NIIOSP them. N. M. Gersevanova of the State Construction Committee of the USSR (Doctor of Technical Sciences E. A. Sorochan, Candidates of Technical Sciences A. V. Vronsky, A. S. Snarsky), Fundamental Project (engineers V. K. Demidov, M. L. Morgulis, I. S. Rabinovich), Kiev Promstroyproekt (engineers V. A. Kozlov, A. N. Sytnik, N. I. Solovieva).

1. GENERAL INSTRUCTIONS

1.1. This Manual was compiled to SNiP 2.09.03-85 "Constructions of industrial enterprises" and applies to the design of:
retaining walls erected on a natural basis and located on the territories of industrial enterprises, cities, towns, access and on-site railways and roads;
industrial basements, both detached and built-in.

1.2. The manual does not apply to the design of retaining walls of main roads, hydraulic structures, retaining walls for special purposes (anti-landslide, anti-landslide, etc.), as well as to the design of retaining walls intended for construction in special conditions (on permafrost, swelling, subsidence soils, on undermined territories, etc.).

1.3. The design of retaining walls and basement walls should be carried out on the basis of:
master plan drawings (horizontal and vertical layout);
report on engineering and geological surveys;
technological task containing data on loads and, if necessary, special requirements for the designed structure, for example, requirements for limiting deformations, etc.

1.4. The design of retaining walls and basements should be established on the basis of a comparison of options, based on the technical and economic feasibility of their use in specific construction conditions, taking into account the maximum reduction in material consumption, labor intensity and construction costs, as well as taking into account the operating conditions of structures.

1.5. Retaining walls built in settlements should be designed taking into account the architectural features of these settlements.

1.6. When designing retaining walls and basements, structural schemes should be adopted that provide the necessary strength, stability and spatial invariability of the structure as a whole, as well as its individual elements at all stages of construction and operation.

1.7. Elements of prefabricated structures must meet the conditions of their industrial production at specialized enterprises.
It is advisable to enlarge the elements of prefabricated structures, as far as the carrying capacity of the assembly mechanisms, as well as the conditions of manufacture and transportation, allow.

1.8. For monolithic reinforced concrete structures should provide for unified formwork and dimensions, allowing the use of standard reinforcing products and inventory formwork.

1.9. In prefabricated structures of retaining walls and basements, the structures of the nodes and the connection of the elements must ensure reliable transmission of forces, the strength of the elements themselves in the joint zone, as well as the connection of the additionally laid concrete in the joint with the concrete of the structure.

1.10. The design of structures of retaining walls and basements in the presence of an aggressive environment should be carried out taking into account the additional requirements of SNiP 3.04.03-85 "Protection of building structures and structures against corrosion".

1.11. The design of measures to protect reinforced concrete structures from electrocorrosion should be carried out taking into account the requirements of the relevant regulatory documents.

1.12. When designing retaining walls and basements, as a rule, unified standard structures should be used.
The design of individual structures of retaining walls and basements is allowed in cases where the values of the parameters and loads for their design do not correspond to the values accepted for standard structures, or when the use of standard structures is impossible, based on local construction conditions.

1.13. This Handbook deals with retaining walls and basement walls filled with homogeneous soil.

2. STRUCTURAL MATERIALS

2.1. Depending on the accepted constructive solution retaining walls can be built from reinforced concrete, concrete, rubble concrete and masonry.

2.2. Choice constructive material is determined by technical and economic considerations, durability requirements, conditions for the production of work, the presence of local building materials and means of mechanization.

2.3. For concrete and reinforced concrete structures, it is recommended to use concrete with a compressive strength of at least class B 15.

2.4. For structures subjected to alternate freezing and thawing, the design must specify the grade of concrete for frost resistance and water resistance. The design grade of concrete is set depending on temperature regime arising during the operation of the structure, and the values of the calculated winter temperatures of the outdoor air in the construction area and is taken in accordance with Table. 1...

Project documentation - documentation containing textual and graphic materials and defining architectural, functional, technological, constructive and engineering solutions to ensure the construction and reconstruction of capital construction projects.

Types of preparation work project documentation that affect the safety of capital construction facilities should only be carried out individual entrepreneurs or legal entities that have certificates of admission to such types of work issued by a self-regulatory organization. Other types of work on the preparation of project documentation can be performed by any individuals or legal entities.

The person who prepares the project documentation may be the developer or an individual or entity. The person who prepares the project documentation organizes and coordinates the work on the preparation of the project documentation, is responsible for the quality of the project documentation and its compliance with the requirements of technical regulations. The person preparing project documentation is entitled to perform certain types of work on the preparation of project documentation independently, provided that such person complies with the requirements for the types of work, and (or) with the involvement of other persons meeting the specified requirements.

Some norms for the design of retaining walls: Code of Rules SP 43.13330.2012 “Constructions of industrial enterprises”. Code of rules SP 20.13330.2011 “Loads and impacts”. Code of Rules SP 22.13330.2011 “Foundations of buildings and structures”.

Material requirements

The choice of material for a retaining wall and its foundation should be made taking into account many factors and requirements, among which the main ones are: the height of the wall, the required durability, water tightness, seismic resistance and resistance to chemical aggression, the quality of the base, the availability of local building materials, the conditions for the production of works, the means mechanization and conditions of interfacing with other structures.

Reinforced concrete thin-element retaining walls are the most economical; compared to massive concrete ones, they require approximately two times less cement with little reinforcement consumption. A significant advantage of reinforced concrete retaining walls is the possibility of using prefabricated structures and erecting them with direct pressure transfer to weak soils without an artificial foundation.

With a height of up to 6 m, cantilever reinforced concrete walls have a smaller volume than ribbed (buttress); for walls with a height of 6 to 8 m, the volumes are approximately the same, and for walls with a height of more than 8 m, a ribbed structure has a smaller volume of reinforced concrete than a cantilever structure. Thus, for walls of medium height and high, a reinforced concrete ribbed structure is most appropriate.

Concrete for reinforced concrete retaining walls must be dense, grades from 150 to 600. Steel rods with a diameter of up to 40 mm of a periodic profile of classes A-II and A-III serve as reinforcement, and for prestressed structures - high-strength wire.

For mounting fittings, as well as for off-design secondary parts of structures, steel can be used class A-I.

For welding of reinforcement bars, electrodes with high-quality coatings of the E42, E42A, E50A and E55 types are used in accordance with GOST 9467 - 60.

The use of concrete retaining walls is advisable only when high cost and lack of reinforcement, since the strength of concrete in massive retaining walls is far from being fully used. For this reason, the use of high grades of concrete for them is impractical, however, according to the condition of density, concrete grades below 150 should not be used. To reduce the volume of masonry, concrete retaining walls can be made with buttresses. For concrete retaining walls of a constant profile, the most economical at a height of more than 150 m will be a profile with an unloading platform at a level of about ¼ of the height of the wall from the edge of the foundation. However, profiles with an inclined front edge, inclined towards the backfill, with a protruding front edge, with an inclined sole, and even rectangular at a height of 1.5 m, can also be used. The use of profiles with an inclined rear face, rectangular and stepped may be due to the requirement for the verticality of the front face, for example, for mooring walls. However, it must be borne in mind that the strictly vertical front face of the retaining wall gives the impression of leaning, so it is usually made with a slight slope to the vertical (1/20 1/50). The inclined front face is made with a slope of about 1/3.

Retaining walls made of rubble masonry require less cement consumption compared to concrete ones, and can be erected in a shorter time with a simpler organization of work. The use of rubble masonry walls is advisable if there is a stone in place.

Rubble masonry must be made of stone grade not lower than 150 - 200 per portland cement mortar grades not lower than 25 - 50, and preferably 100 - 200. Solutions, in addition to strength, must have plasticity and water-holding capacity. Why is it recommended to introduce plasticizing additives into their composition. For hydraulic walls, a rubble stone of a grade of at least 200 is used, a solution of Portland cement of a grade of at least 50.

When choosing a retaining wall profile from rubble, the same considerations should be followed as for concrete walls, but without complicating it. Retaining with a vertical or inclined front face and with unloading platforms are used. The back face is made vertical or very low in height, or with support at the top of the wall.

If there is a torn or small rubble stone in place, then rubble concrete masonry can be used instead of rubble masonry.

Brick walls are allowed up to 3-4 m high. In this case, it is recommended to use buttresses. Most often, brick walls of a rectangular or stepped profile are used for small underground structures (walls of channels, wells, etc.). For external retaining walls. exposed to the weather, brickwork undesirable, and unsuitable for hydraulic walls. For brick retaining walls, well-burnt brick of a grade of at least 200 is used, on a solution of at least 25. The use of silicate brick is not allowed.

Hard rock, high-grade concrete and durable cladding are used if necessary to protect the wall from weathering, from the effects of high water velocities.

For concrete, cladding or the outer layer of masonry, it is allowed to use a material that can withstand freezing a hundred times.

If the structure is located in an area where the average monthly temperature of the coldest month is above 5 degrees Celsius. then the material must withstand only fifty-fold freezing.

When exposed to an aggressive environment, stone resistant to aggression, special cement for concrete and mortar, protective coatings or linings should be used.

For walls exposed to water, hydraulic concrete (GOST 26633-91 dated 1992.01.01 “Hydraulic engineering concrete”), as well as cement mortar masonry or waterproofing (cement grout, iron plating, shotcrete, asphalt paving, etc.) should be used.

Ribbed structures can be used for low retaining walls in the absence of stone and aggregates for concrete in place, as well as for temporary structures.

In seismic regions of high and medium height, retaining walls at the bottom with rocky and dense soils average 1/3 of the height, with soils of medium density - ½, with soft soils - 2/3, and with water pressure - up to the full height of the wall. The width of the foundation slab of a thin-element retaining wall of an angle profile is usually S2/3 of the height of the wall. However, these ratios also depend on other factors - on the profile of the retaining wall, its material, etc. Therefore, the figures given should be considered as rough estimates.

The top thickness must be at least:

for reinforced concrete walls 0.15 m,

for concrete walls 0.14 m,

for rubble and rubble concrete walls 0.75 m,

For brick walls 0.51 m

For concrete and reinforced concrete walls, the foundation, as a rule, is integral with the wall itself. At brick walls, the foundation is made in the form of an independent structure of rubble or concrete masonry, protruding beyond the edges of the wall and forming cuts with a width of at least 15 cm and no more than the height of the foundation. Foundation protrusions can be made stepped.

Calculation methods

Retaining walls should be calculated according to two groups of limit states:

the first group (by bearing capacity) provides for the performance of calculations;

on the stability of the position of the wall against shear and the strength of the soil base;

on the strength of structural elements and joints

the second group (according to serviceability) provides for checking:

grounds for allowable deformations;

structural elements to allowable values of crack opening.

Ground pressure for massive retaining walls (Fig. 2, a). Soil pressure for corner retaining walls should be determined based on the formation of a wedge-shaped symmetrical (and for a short rear console - asymmetric) collapse prism behind the wall (Fig. 2, b). Soil pressure is assumed to act on an inclined (calculated) plane drawn at an angle e at d = j ў.

The angle of inclination of the calculated plane to the vertical e is determined from condition (1), but is taken no more than (45° - j /2)

tg e \u003d (b - t) / h. (1)

The greatest value of the active soil pressure in the presence of a uniformly distributed load q on the horizontal surface of the backfill is determined when this load is located within the entire collapse prism, if the load does not have a fixed position.

Calculation of the stability of the position of the wall against shear

The calculation of the stability of the position of the wall against shear is made from the condition

Fsa J g c Fsr/ g n , (2)

where Fsa is the shear force, equal to the sum projections of all shear forces on a horizontal plane; Fsr - holding force equal to the sum of the projections of all holding forces on a horizontal plane; us - coefficient of working conditions of the foundation soil: for sands, except for dusty ones - 1; for silty sands, as well as silty-clay soils in a stabilized state - 0.9; for silt-clay soils in an unstabilized state - 0.85; for rocky, non-weathered and slightly weathered soils - 1; weathered - 0.9; heavily weathered - 0.8; g n - reliability coefficient for the purpose of the structure, taken equal to 1.2, 1.15 and 1.1, respectively, for buildings and structures of class I, II and III, assigned in accordance with the appendix. 4.

The shear force Fsa is determined by the formula

Fsa = Fsa, g + jsa ,q , (3)

where Fsa , g - shear force from the own weight of the soil is equal to:

Fsa, g = Pg h/2 ; (4)

Fsa , q - shear force from the load located on the surface of the collapse prism is equal to:

Fsa,q = Pqyb. (5)

Rice. 2 - Design schemes retaining walls: a - massive; b - corner profile

The holding force Fsr for a non-rock base is determined by the formula

Fsr = Fv tg(j I - b) + b c I + E r , (6)

where Fv is the sum of the projections of all forces on the vertical plane

a) for massive retaining walls

Fv = Fsa tg(e + d) + G c t + g I tgb b 2 /2, (7)

G st - dead weight of the wall and soil on its ledges.

b) for corner retaining walls (for e Ј q 0)

Fv = Fsa tg(e + j ў) + g ў g f + g I tg b b 2 /2 (8)

where g f - load safety factor is assumed to be 1.2; E r - passive soil resistance:

Er = g I l r /2 + cIhr(l r - 1)/tg j I , (9)

where l r - coefficient of passive soil resistance:

l r =tg2(45° + j I /2), (10)

hr - height of uplift prism

hr =d + btg b (11)

The calculation of the stability of retaining walls against shear should be carried out according to the formula (15) for three values of the angle b (b = 0, b = j I /2 and b = j I).

With an inclined wall base, in addition to the indicated values of the angle b, it is necessary to calculate against the shear also for negative values of the angle b.

When shearing along the sole (b = 0), the following restrictions should be taken into account: with I Ј 5 kPa, j I Ј 30°, l r = 1.

The holding force Fsr for a rock base is determined by the formula

Fsr=Fvf+Er, (12)

where f is the coefficient of friction of the sole on the rocky ground, is taken according to the results of direct tests, but not more than 0.65.

CENTRAL RESEARCH

AND DESIGN AND EXPERIMENTAL INSTITUTE OF INDUSTRIAL BUILDINGS AND CONSTRUCTIONS (TsNIIpromzdaniy) of the State Construction Committee of the USSR

REFERENCE AID

Retaining wall design

and basement walls

Developed for "Construction of industrial enterprises". Contains the main provisions for the calculation and design of retaining walls and basement walls of industrial enterprises from monolithic and prefabricated concrete and reinforced concrete. Calculation examples are given.

For engineering and technical workers of design and construction organizations.

FOREWORD

The manual was compiled for “Constructions of industrial enterprises” and contains the main provisions for the calculation and design of retaining walls and basement walls of industrial enterprises from monolithic, prefabricated concrete and reinforced concrete with calculation examples and the necessary tabular values of the coefficients that facilitate the calculation.

In the process of preparing the Handbook, certain calculation prerequisites were clarified, including taking into account the cohesive forces of the soil, determining the slope of the slip plane of the collapse prism, which are supposed to be reflected in addition to the specified SNiP.

1. GENERAL INSTRUCTIONS

1.1. This Manual has been drawn up for “Constructions of industrial enterprises” and applies to the design of:

retaining walls erected on a natural basis and located on the territories of industrial enterprises, cities, towns, access and on-site railways and roads;

industrial basements, both detached and built-in.

1.3. The design of retaining walls and basement walls should be carried out on the basis of:

master plan drawings (horizontal and vertical layout);

report on engineering and geological surveys;

technological task containing data on loads and, if necessary, special requirements for the designed structure, for example, requirements for limiting deformations, etc.

1.5. Retaining walls built in settlements should be designed taking into account the architectural features of these settlements.

1.7. Elements of prefabricated structures must meet the conditions of their industrial production at specialized enterprises.

It is advisable to enlarge the elements of prefabricated structures, as far as the carrying capacity of the assembly mechanisms, as well as the conditions of manufacture and transportation, allow.

1.8. For monolithic reinforced concrete structures, unified formwork and overall dimensions should be provided, allowing the use of standard reinforcing products and inventory formwork.

1.10. The design of structures of retaining walls and basements in the presence of an aggressive environment should be carried out taking into account the additional requirements of SNiP 3.04.03-85 “Protection of building structures and structures from corrosion”.

1.11. The design of measures to protect reinforced concrete structures from electrocorrosion should be carried out taking into account the requirements of the relevant regulatory documents.

1.12. When designing retaining walls and basements, as a rule, unified standard structures should be used.

The design of individual structures of retaining walls and basements is allowed in cases where the values of the parameters and loads for their design do not correspond to the values accepted for standard structures, or when the use of standard structures is impossible, based on local construction conditions.

1.13. This Handbook deals with retaining walls and basement walls filled with homogeneous soil.

2. STRUCTURAL MATERIALS

2.1. Depending on the adopted design solution, retaining walls can be built from reinforced concrete, concrete, rubble concrete and masonry.

2.2. The choice of structural material is determined by technical and economic considerations, durability requirements, work conditions, the availability of local building materials and mechanization.

2.3. For concrete and reinforced concrete structures, it is recommended to use concrete with a compressive strength of at least class B 15.

2.4. For structures subjected to alternate freezing and thawing, the design must specify the grade of concrete for frost resistance and water resistance. The design grade of concrete is set depending on the temperature regime that occurs during the operation of the structure, and the values of the calculated winter temperatures of the outdoor air in the construction area and is taken in accordance with Table. 1.

Table 1

	Estimated	Concrete grade, not lower
structures	temperature	frost resistance	in terms of water resistance
freezing at	air, ??C	Building class
variable freeze and thaw
In water-saturated
state (for example, structures located in a seasonally thawing layer						He is normalized
soil in permafrost areas)	Below -5 to -20 inclusive				Not standardized
				Not standardized
In conditions of episodic water saturation (for example, above-ground structures that are constantly exposed to						He is normalized
atmospheric influences)	Below -20 to -40 inclusive				W2 He is normalized
	Below -5 to -20			He is normalized
	inclusive
In conditions of air-humidity in the absence of episodic water saturation, for example,						He is normalized
structures permanently (exposed to the ambient air, but protected from the effects of atmospheric precipitation)	Below -20 to -40 inclusive			He is normalized
	Below -5 to -20 inclusive

* For heavy and fine-grained concrete, frost resistance grades are not standardized;

** For heavy, fine-grained and light concrete, frost resistance grades are not standardized.

Note. Estimated winter outdoor temperature is taken as average temperature air of the coldest five-day period in the construction area.

2.5. Prestressed reinforced concrete structures should be designed mainly from class B 20 concrete; At 25; At 30 and At 35. For concrete preparation concrete of class B 3.5 and B5 should be used.

2.6. The requirements for rubble concrete in terms of strength and frost resistance are the same as for concrete and reinforced concrete structures.

2.7. For reinforcement of reinforced concrete structures made without prestressing, hot-rolled bar steel of a periodic profile of class A-III and A-II should be used. For mounting (distribution) fittings, it is allowed to use hot-rolled fittings of class A-I or ordinary smooth reinforcing wire of class B-I.

When the design winter temperature is below minus 30°C, reinforcing steel of class A-II grade VSt5ps2 is not allowed to be used.

2.8. As prestressed reinforcement of prestressed reinforced concrete elements, heat-strengthened reinforcement of the At-VI and At-V classes should be mainly used.

It is also allowed to use hot-rolled rebar class A-V, A-VI and heat-strengthened reinforcement of class At-IV.

When the calculated winter temperature is below minus 30°C, reinforcing steel of class A-IV grade 80C is not used.

2.9. Anchor rods and embedded elements should be made of rolled strip steel of class S-38/23 (GOST 380-88) grade VSt3kp2 at a design winter temperature of up to minus 30°C inclusive and grade VSt3psb at a design temperature of minus 30°C to minus 40°C WITH. For anchor rods, steel S-52/40 grade 10G2S1 is also recommended at a design winter temperature of up to minus 40°C inclusive. The thickness of the strip steel must be at least 6 mm.

It is also possible to use reinforcing steel of class A-III for anchor rods.

2.10. In prefabricated reinforced concrete and concrete structural elements, mounting (lifting) loops must be made of reinforcing steel of class A-I grades Vst3sp2 and Vst3ps2 or from steel of class Ac-II grade 10GT.

When the design winter temperature is below minus 40°C, the use of VSt3ps2 steel for hinges is not allowed.

3. TYPES OF RETAINING WALLS

3.1. According to the constructive solution, retaining walls are divided into massive and thin-walled.

In massive retaining walls, their resistance to shear and overturning when exposed to horizontal soil pressure is mainly ensured by the own weight of the wall.

In thin-walled retaining walls, their stability is ensured by the own weight of the wall and the weight of the soil involved in the work of the wall structure.

As a rule, massive retaining walls are more material-intensive and more labor-intensive to erect than thin-walled ones, and can be used with an appropriate feasibility study (for example, when they are built from local materials, the absence of precast concrete, etc.).

3.2. Massive retaining walls differ from each other in the shape of the transverse profile and material (concrete, rubble concrete, etc.) (Fig. 1).

Rice. 1. Massive retaining walls

a - c - monolithic; g - e - block

Rice. 2. Thin-walled retaining walls

a - corner console; b - corner anchor;

c - buttress

Rice. 3. Pairing of prefabricated front and foundation slabs

a - with the help of a slotted groove; b - using a loop joint;

1 - front plate; 2 - foundation plate; 3 - cement-sand mortars; 4 - concrete embedding

Rice. 4. Construction of a retaining wall using a universal wall panel

1 - universal wall panel (UPS); 2 - monolithic part of the sole

3.3. In industrial and civil construction, as a rule, thin-walled retaining walls of the corner type are used, shown in Fig. 2.

Note. Other types of retaining walls (cellular, sheet pile, shells, etc.) are not considered in this Manual.

3.4. According to the manufacturing method, thin-walled retaining walls can be monolithic, prefabricated and prefabricated-monolithic.

3.5. Thin-walled cantilever walls of the corner type consist of front and foundation slabs rigidly connected to each other.

CENTRAL RESEARCH

AND DESIGN AND EXPERIMENTAL INSTITUTE OF INDUSTRIAL BUILDINGS AND CONSTRUCTIONS (TsNIIpromzdaniy) of the State Construction Committee of the USSR

REFERENCE AID

to SNiP 2.09.03-85

Retaining wall design

and basement walls

Developed for SNiP 2.09.03-85 “Construction of industrial enterprises”. Contains the main provisions for the calculation and design of retaining walls and basement walls of industrial enterprises from monolithic and prefabricated concrete and reinforced concrete. Calculation examples are given.

For engineering and technical workers of design and construction organizations.

FOREWORD

The manual was compiled for SNiP 2.09.03-85 “Constructions of industrial enterprises” and contains the main provisions for the calculation and design of retaining walls and basement walls of industrial enterprises from monolithic, prefabricated concrete and reinforced concrete with calculation examples and the necessary tabular values of the coefficients that facilitate the calculation.

1. GENERAL INSTRUCTIONS

1.1. This Manual was compiled to SNiP 2.09.03-85 "Constructions of industrial enterprises" and applies to the design of: