Concrete retaining walls

A retaining wall is a structure erected to prevent the destruction of soil, embankments, slopes or deep excavations. The calculation of the retaining wall is carried out by trained specialists, since the strength and long service life of the entire structure under construction depends on the quality of the work done.

The retaining wall, made of various building materials, must have a base, the actual above-ground part of the supporting structure and drainage. The depth of the foundation depends on the height of the structure, but under any conditions, its width should be approximately 20 cm greater than the thickness of the wall body to ensure the necessary reliability and stability.

Such walls are fortifying and decorative. Based on the complexity of the assigned task, the wall can be:

1. monolithic, for the construction of which brick, rubble, concrete, buto- or reinforced concrete are used;

2. prefab made of reinforced concrete.

By their structure, monolithic ones are divided into:

• corner retaining walls (cantilever), in the structure of which there are vertical and foundation slabs;

• buttresses, to increase the strength of which ribs or buttresses installed across are used.

National teams are divided into:

• cantilever retaining walls mounted on site from segments made of separate blocks or slabs; the main difference from monolithic ones is precisely in the use of such sections for the assembly of structures;

• fence, made in the form of solid pillars, in the intervals between which plates are placed.

The basis of any structure is a shallow foundation or a deep foundation (which is 1.5 times its depth in depth).

When choosing the height of the support wall, you need to pay attention to the size of the available drop:

• more than 20 meters - high structures;

• from 10 to 20 meters - medium;

• up to 10 meters - low.

There are retaining walls and based on their structure:

• massive, which ensure the stability of mobile soils and prevent overturning under the yoke of their own weight;

• anchor ones are especially effective in the presence of a large difference in height;

• thin-walled, the distinctive feature of which is that for this group there is a rate of probable bending under the influence of loads.

Among other things, the size of the retaining wall is extremely important, which is set based on the force of soil pressure, the own mass of the wall, loads that do not go beyond the boundaries of the prism of the collapse of the soil mass.

The maximum possible stability, resistance to high levels of pressure are extremely important properties that must be characterized by a high-quality retaining wall. Otherwise, the structure can fall apart without much effort, and the soil can slide. As a result, it is necessary to bear in mind every factor on which the reliability of the supporting walls depends.

Therefore, it is necessary to figure out what still affects the retaining walls.The effect of the wall's own mass, the forces of friction and adhesion between soil particles, the force effect of the soil, the additional mass of elements that may be on it - all this is of great importance.

What is able to influence the structure of the structure:

• an increase in the volume of soil in winter;

• wind strength (when the retaining wall is higher than 2 meters);

• the level of mechanical vibrations (in particular, if a railway is located nearby);

• any seismic activity (each region has its own characteristics);

• washing away by atmospheric precipitation in the form of rain.

An additional condition that has a great influence on the degree of constancy of the structure is the wall thickness. It is determined by the type of soil and the height of the structure itself. When the soil is soft and the retaining wall is high, then, of course, the width of the protective "shield" must be increased.

When creating a project of retaining structures, structural schemes should be adopted that ensure the required reliability, stability and spatial rigidity of the structure as a whole, as well as some of its components at all stages of construction and use.

Work on the creation of a design for the structures of retaining walls in the presence of an environment that causes the destruction of materials and products from them or the deterioration of their characteristics, must be carried out taking into account the special requirements of the chapter of SNiP III-23-76.

Let's take a look at the main steps to be taken when erecting retaining walls.

At the initial stage, it is required to dig a ditch, which will be located along the contour of the structure under construction. To speed up the process, as a rule, they resort to the help of excavator equipment, nevertheless, the final cleaning of the walls and the adjustment of the ditch are performed manually with shovels. The depth of the trench depends on the dimensions of the support, and if its height is not more than 1 m, then it makes sense to deepen by 40 cm.If the decision is made to do without a ditch, and this allows the future structure, before assembling the formwork, it is necessary to carefully prepare the soil surface. Preparation consists in cleaning the site from weeds and leveling it (we cut off all the bumps and irregularities with a shovel).

The structure of the formwork for the support wall must be bulky as it needs to withstand the pressure of the heavy concrete. For this purpose, shields from a 30 mm board will fit, which in a horizontal position are docked with a bar of wood 50x100 mm and fixed on stakes dug in with a step of 0.5 m. The installation of the formwork starts from the rear wall. To prevent the wood frame from bending, iron rods are dug in along the wall. At this stage, a drainage system must be made.

A well-designed drainage system removes water from the rear wall of the substructure and prevents soil washout. Drainage types:

• transverse system;

• longitudinal system;

• mixed longitudinal-transverse.

When installing a transverse drainage system, holes with a diameter of 10 cm are created in the retaining wall or finished pipes are laid. In order for the drainage to ensure the removal of liquid beyond the boundaries of the support, it is performed at an angle. The spacing of the drainage pipes is 1 meter.

It is built for a wide variety of walls, the height of which is higher than 0.3 m.The design features depend on the soil on which the work is carried out, as well as on the characteristics of the body. When there is a lot of clay in the soil, preference is given to a strip foundation formed from blocks. On weak soils, including a lot of sand (mainly "floating"), the base is arranged on piles. Low walls (0.3 m or less) are buried in the earth without a foundation.

The depth of the bookmark depends on the height of the above-ground part. When it is low (0.3-0.8 m), the base has dimensions of 0.2-0.3 m. For walls of 0.8-1.5 m, the depth will be 0.3-0.5 m, for higher (but not more than 2 m) - 0.7 m.With significant soil mobility or the nearby location of groundwater (less than 1.7 m), deepening is carried out, 1.5 times the width.

Reinforcement and concreting of the base is carried out. The iron bars sticking out of the concrete must be at least 0.5 m high. The sole is left to anchor for about a month. No work should be done before the end of this period.

In order for the concrete retaining wall to be reliable, not to collapse under the influence of temperature surges, it is required to use high-quality cement of frost-resistant grades. The calculation of the components for the solution is carried out in the ratio: a bucket of water, a bucket of cement, a bucket of gravel and 3 buckets of sand. All components are mixed in a concrete mixer or trough, and the resulting mixture must be carefully poured deep into the formwork.

First of all, a geotextile cloth is laid or drainage soil is poured. After that, layers of selected soil are placed 20-40 cm each, each of which is carefully compacted. On top, the vegetative layer of soil cut off before this is laid.

The cladding of the retaining walls is carried out on top of the main building material from which the structure is erected, in order to decorate its appearance. Walls built from foam blocks, concrete, masonry bricks and so on will look uninteresting. To add decorativeness to such a structure, cladding will allow. The specialized building materials that are used in this case will make it possible for the structure to harmoniously fit into the design of the garden plot and unite with its nature.

The concrete wall is characterized by the most ingenious construction technology, has high strength, does not require significant expenditures of the used building materials and, as a result, money. You can build such a wall with your own hands, without special skills and knowledge. But concrete is a nondescript building material, and such a wall will greatly attract attention against the backdrop of lush vegetation. In this regard, it is simply necessary to revet it in this case. Plastering is the simplest solution. You can apply the composition in such a way that the surface does not come out smooth, but has a texture, which will look much more interesting. Equally decorative to the structure will give a stone - natural or artificial, it is up to you to decide.

As already mentioned, concrete bases do not stand out for their sophistication and have a porous surface that can absorb moisture, and therefore require additional finishing. It can be finished:

• by covering with a special water-repellent paint intended for concrete surfaces;

• decorative tiles for outdoor cladding;

• plaster;

• wood panels;

• artificial stone.

When selecting finishing building materials, it is advisable to take into account the architectural style of the country house and the landscape design of the land plot. The price of decorative finishing works will depend on the selected finishing materials.

The choice of building material for retaining walls is determined by technical and economic concepts, strength requirements, working conditions, availability of local building materials and construction equipment.

It is recommended to construct concrete and reinforced concrete retaining walls from concrete of the design grade for compressive strength:

• for prefabricated reinforced concrete structures - M200, M300, M400;

• for monolithic concrete and reinforced concrete structures - M150, M200.

Stressed reinforced concrete structures must be mainly constructed from concrete of the M300, M400, M500, M600 brands. For the device of concrete preparation (pot concrete), it is necessary to use concrete of the M50 and M100 brands. Before building a retaining wall on a long slope, take care to give it a curved or broken configuration with frequent kinks. It will more effectively resist pressure by reducing the length of each span.

You can get acquainted with the process of erecting reinforced concrete retaining walls in this video.