Varieties of retaining walls and their purpose, depending on the material used, the device of the reinforcing structure, calculation of parameters and construction technology. A retaining wall is a vertical structure in rugged terrain that holds the ground and protects it from collapse or roll. It is made of materials with a large margin of safety. You can learn about the types of such structures and the technology of their formation from this article.
Features and structure of the retaining wall
The functional purpose of the retaining structure is to eliminate the problem of the unevenness of the territory. Most often it is erected on slopes that are difficult to operate. It is not very convenient to carry out work in such areas, therefore, terraces are formed - horizontal platforms held in a planned position by vertical structures. A building is being erected on flat areas for dividing and zoning the territory, as well as for decorating the landscape.
The structure of the retaining wall is as follows:
- Foundation … This is the underground part of the structure, which carries the main load from the retained mass of the soil.
- Body … This is the name of the structure that encloses the problem area. The profiles of the reinforcing walls are made trapezoidal or rectangular to withstand heavy loads.
- Drainage … It is necessary to remove moisture that accumulates in the lower part of the slope.
The retaining wall can be made from a variety of materials. Each option applies to specific situations. If the structure is to be used as a reinforcement, concrete and natural stone are needed. These materials are able to withstand heavy loads from sliding soil. The retaining structure for decorating the site can be built from wood, gabions or bricks.
In addition to the listed options, such a wall can be made of railway sleepers and boards impregnated with a protective agent, laid horizontally. Concrete blocks are also suitable. The stores sell ready-made sections of logs, which are enough to fix to the supporting structures.
The material for the wall is chosen for certain design ideas. Monumentality is created by textured material, for example, granite blocks, laid at large intervals. Large diameter logs are also suitable for this case. For an elegant wall, use small pebbles and plaster.
Preparatory work before installing the retaining wall
In order for the structure to perform its functions, it is necessary to ensure its stability. Therefore, the structure is erected only on solid ground - stone, clay, sandy loam, etc. The depth of soil freezing also matters - no more than 1.5 m. If these requirements are ignored when designing retaining walls, the structure will collapse, and the soil will creep.
The strength of the structure is influenced by many factors: the mass of the entire structure, the reliability of adhesion to the ground, the pressure from the held soil, the load from the additional elements fixed on it. The location of the territory is of no small importance. Railroad tracks can destroy the wall due to high vibration at the site, frequent rains lead to soil leaching in the area of the structure, etc. In addition, the structure is periodically influenced by such phenomena as soil swelling in winter and wind, especially if it is several meters high.
To withstand the load from the slope, the retaining wall is reinforced with a sole (wide foundation) that holds it upright. The wider the sole, the stronger the structure. The soil pressure is balanced by the following forces:
- Holding load on the back of the backfill … It is less than the shear force created by the soil, but it still needs to be taken into account.
- Friction force under the outsole that prevents the structure from sliding … Its value depends on the mass of soil poured onto it (surcharge). The greater the weight of the ground on it and the wider the base, the better the body will resist shear.
When building tall structures, it is recommended to contact a specialist who will perform retaining wall calculations based on all of the above factors. You can also use special programs for determining the design parameters, which can be found on the Internet.
A structure up to 1.0 m high can be disregarded for its strength. It is enough to follow our recommendations:
- Structures over 0.3 m are necessarily built with a strip foundation. The exception is low stone buildings, in which the first row is half buried in the ground.
- For walls of 30-60 cm, the foundation is poured to a depth of 15-30 cm, 60-100 cm - to a depth of 30-50 cm. The basic principle of creating a foundation: the softer the soil, the larger it is.
- The base width depends on the soil. In very soft soil it should be equal to 1/2 of the wall height, in medium density soil - 1/3 of the fence height, in dense - 1/4 of the height.
- To reduce the load on the back face, tilt the structure towards the slope by 10-15 degrees.
- The surface of the wall facing the terrace should not be smooth. In stone, brick and block structures, provide for protrusions, in concrete - perform chips.
- Often a console is made on the front of the partition, which increases the stability of the structure.
- Fill the gap between the wall and the slope with hollow material (expanded clay). It will reduce lateral loading.
- The underground part is made of strong heavy elements - stone, crushed stone, gravel, with the addition of cement mortar.
- If a lawn begins right next to the wall, make the foundation flush with the ground so that it does not interfere with mowing the grass.
- An important parameter for a wall is its thickness. At the sole, it should be 0, 5-0, 7 of its height, at the top - 0, 3-0, 4 m. Perform the lower part with a slight slope from the slope.
- The broken curvilinear shape of the structure increases its strength, because in this case, the spans are shorter.
- On the side of the retained soil, waterproof the surface of the structure with roofing material or roofing felts applied in two layers. If the soil is dry, cover it with bituminous mastic.
During construction, it is necessary to remember about the drainage of water accumulated under the slope in front of the wall. Drainage is not required if the soil is loose. In this case, moisture will not be able to accumulate and will go underground on its own. There are 3 types of drainage systems:
- Underground drainage … To create it, you need a special corrugated pipe with holes. Wrap it with geotextile and lay it along the wall from the inside. It will drain water into a collection well or through a structure to the outside. In the latter case, a tube must be provided at the bottom of the wall or a small opening must be left.
- Above ground drainage … Its purpose is to prevent overflow of water over the top of the structure. Made from any loose material. Coarse gravel or crushed stone is suitable, which is used to fill the space from wall to slope. You can alternate between layers of stone and soil to make it easier to tamp.
- Drainage in the wall … Typical for brick and masonry. To create it, it is enough to leave one vertical joint between the elements unfilled with a solution through 1 row of masonry, through which water flows out.
Retaining wall construction technology
The principle of forming retaining walls is the same for all structures, regardless of the material used, but the technology is different for each case. Consider the most popular options for buildings, as well as general recommendations for performing work.
Retaining wall made of wood
The use of lumber is considered the cheapest option for strengthening terraces. To create, you need to choose high-quality blanks with a diameter of 12-18 cm. Their height is determined according to certain rules. If the above-ground part of the structure does not exceed 1 m, the total length of the workpiece is 1.5 m, and 0.5 m is the underground part.
Cover all lumber with a special anti-rot and insect protection agent before laying. The lower part can also be burned in a fire until charring. A thick layer of ash that remains on the surface will reliably protect the timber from destruction. Connect the logs together with nails, and tie the upper parts with wire.
A lumber wall is constructed as follows:
- Dig a ditch 10-15 cm deep more than the underground part of the log and 15-20 cm wide more than its diameter.
- Cover the bottom of the pit with a mixture of gravel and sand and compact the pad thoroughly.
- Place the logs in the pit, set them in a vertical plane and fix them together with wire, bolts, or in another way.
- Fill the remaining space in the ditch with concrete.
Concrete retaining wall
Concrete is used to strengthen the slope in critical places. With the correct calculation, the wall can withstand the heaviest loads. Outwardly, it looks unpresentable, but this defect is corrected by decorative cladding.
The structure is made as follows:
- Dig a trench along a path that follows the shape of the boundary of the fenced area.
- Assemble the formwork using strong, rigid material. Thick boards are suitable, which from the outside are supported by metal pins driven into the ground. If the sole is not made, the width of the formwork and the wall will be the same. Dig a hole to increase the size of the foundation if necessary.
- Fill the bottom of the ditch with 10-15 cm gravel.
- Install reinforcement mesh in the ditch.
- Prepare the concrete and fill the formwork.
- After the mortar has hardened, remove the boards, seal the defects with cement mortar.
- Cover the structure with a decorative coating.
Retaining wall made of stone
For the construction of a retaining wall from this material, you will need very strong workpieces from granite, basalt, syenite. The building looks prestigious, especially if large samples are used. Such structures are quite rare due to the high cost of boulders and the laboriousness of the process.
Sandstones and limestones are less durable. They have the unpleasant property of being saturated with water and overgrowing with moss, which, by the way, gives them an original look. It must be remembered that under the action of water, limestone begins to release special compounds that pollute the soil. Therefore, it is not recommended to plant plants near such a wall. Often, soil is poured into prepared pockets between stones and flowers or grass are planted.
The work is performed in the following sequence:
- Dig a trench 0, 4-0, 5 m deep and 30-40 cm wider than the width of the wall. If the base is narrow, the entire structure will be unstable and will quickly collapse.
- Sort stones by size and geometry.
- Pour a 10-15 cm layer of gravel and sand on the bottom and tamp the "pillow".
- Fill the ditch with concrete, no more than 15 cm to the top.
- After the concrete has hardened, coat the foundation with a solution with the addition of lime, which increases the plasticity of the solution. It is prepared from cement, sand and lime, which are mixed in a ratio of 1: 4: 1. To prevent lumps from forming, add water to the mixture gradually.
- Apply the mixture to the foundation in a layer of 2-3 cm.
- Lay out the first row. Place large samples of regular shape in the corners of the building. They are also suitable for the lower rows. Place small stones in the middle. When laying, find the most stable position of the material.
- Lay out the entire wall in a similar manner. Apply the solution in a layer of no more than 1-1.5 cm, so that the seams do not come apart
A retaining fence up to 0.5 m is allowed to be laid out in a dry way. For construction, you will need stones in which two surfaces are more or less parallel. They are stacked on top of each other with a sling. A foundation is not required for such low structures, but the bottom row of stones must be half buried in the soil. For stability, lay a few long stones across the wall and sink into the slope. When laying, it is necessary to ensure that the vertical seams are staggered. The thickness of the structure should be up to 30 cm, but not more than 1/5 of its height.
Brick retaining wall
Before making a brick retaining wall, calculate its thickness correctly. Lay a structure up to 60 cm in height in half a brick, 60-100 cm in a whole brick, more than 1 m in one and a half bricks. Start construction with the construction of the foundation. It is made 20-30 cm wider than the wall.
When choosing the type of brick, consider its durability. Clinker, even after long-term use, will not lose its appearance. Ordinary building bricks will age quickly, but will fit well into the surroundings.
Retaining wall made of gabions
A wall of ready-made containers is built very quickly. If the height of the building is less than 1 m, simply install the gabions on a cleaned area. For a higher structure, a strip foundation is required, as for a stone and brick partition.
Fill containers with heavy material and then wire them together. The structure can be closed with decorative material, and the remaining gap can be filled with rubble, stone or cobblestone.
How to make a retaining wall - watch the video:
Retaining walls, built according to the correct calculations, can prevent the destruction of natural or artificially created slopes and make such areas of land suitable for use on which it was previously impossible to plant anything.
