Soil strengthening methods

Recommendation points

• Mechanical method
• Reinforcement with reinforced concrete piles
• Soil piles
• Installation of soil cushions, ramming / vibration, soil replacement
• Cementation and injection
• Mechanical mixing of soil with cement-sand mortar (cementation)
• Jet carburizing
• Plane soil strengthening (road construction)
• Mixing with natural granules
• Mixing with mineral binders
• Mixing soil with organic binders
• Drainage of soils
• Heat setting or firing
• Chemical method – mixing soil with chemical solutions
• Electric method
• Electrochemical method
• Reinforcement
• Geogrid
• Geotextile
• Geogrid
• Sowing grass

During the reconstruction of buildings and the construction of new structures, the problem of soft soil often arises. Such a base may not withstand the loads from the building. Today in our article we will talk about various methods of strengthening it..

The soil is a layer that absorbs the sum of all loads from the structure. Conventionally, all soils can be divided into stable and unstable. Stable – dense and dry enough to withstand foundation or road loads without special preparation. Unstable requires preliminary work to drain and seal.

Mechanical method

It implies the introduction of individual high-strength products (piles) or materials (soil, crushed stone), as well as compaction without changing the structure (ramming / vibration).

Reinforcement with reinforced concrete piles

The point is that a long pile passes through a layer of soft soil and rests against a more dense one. The load is transmitted vertically along the pile. It is also held by the friction of the soil against the surface of the pile. According to the immersion method, piles are rammed (driven into the ground with or without preliminary drilling), bored (liquid concrete is poured into the casing, immersed in the ground) and indentation piles (driven by a special machine-jack). The method requires the use of bulky and expensive equipment and a large construction site.

Soil piles

A prepared mixture of granulometric aggregate of different fractions is poured into a pre-drilled hole. It is rammed in layers. The effect is comparable to reinforced concrete piles, but much cheaper and more environmentally friendly.

Installation of soil cushions, ramming / vibration, soil replacement

They are used with a relatively small required layer thickness of the desired properties. Compaction is carried out with rollers (cam and smooth), vibrating plates and other equipment with or without vibration. Dusty sands are rammed with water. The method is optimal for the construction of airfields, roads and other large-area objects. If it is impossible to apply the method, the layer of soft soil is removed and replaced with a more durable one..

Cementation and injection

The bottom line is to give the soil the desired properties by adding cement to its composition.

Mechanical mixing of soil with cement-sand mortar (cementation)

A special auger drill with a hollow rod having holes along the length is used. Through them, the cement slurry is fed simultaneously with the operation of the screw, and it is mixed with the soil. The method is relatively cheap and proven. Mainly used in wet soils.

Jet carburizing

Separately, it is worth noting a modern approach to the classics: jet cementation. The cement slurry is fed through the pipe under very high pressure, simultaneously punching the injection site and mixing with the soil. Requires the use of special equipment.

Mechanical and jet grouting is quite applicable for strengthening the soils on which buildings are already standing, even in confined spaces. For this, compact injection units (the so-called jet piles) are used. They can be entered both vertically and at an angle. Works are carried out quickly, relatively quietly and suitable for city streets.

Plane soil strengthening (road construction)

In the construction of continuous pavements, combined methods of soil strengthening are used. Due to their length over the terrain, such objects can cover large areas, and, accordingly, a different composition of the base. The methods below are always used in combination with mechanical strengthening..

Mixing with natural granules

Modification of properties by adding granulometric or other aggregate. Depending on the condition of the soil, different natural materials are used to stabilize it: crushed stone, gravel, sand, clay, loam. The method is relatively cheap and environmentally friendly, does not require chemical components. Mixing takes place in a special auger hopper.

Mixing with mineral binders

Liming is a method known for a long time. Reduces plasticity and stickiness of clay soils, making them more resistant to wetting. Among the disadvantages is low frost resistance. Used to prepare the main (lower) road layers.

Mixing soil with organic binders

The principle does not differ from those described above. As an additive, various resins, bitumen, solid tar and liquid emulsions are used. The effect and scope are also roughly the same. Of the features, it is worth noting the high cost of organic material (or its synthetic substitute) and the aggressiveness of these components in relation to the natural environment. Therefore, this method is practically not used today..

Of the three described technologies, the first two can be independently applied in practice. Easily available and relatively inexpensive components and an elementary mixing technology make them in demand today. It is quite possible to strengthen a section of a dirt road or a courtyard area using a conventional motorized cultivator.

Drainage of soils

One of the main factors in the weakness of soils is the presence of water in their composition. Removing moisture from them leads to significant compaction and elimination of fluidity.

Heat setting or firing

Effective for soils with clay content. A perforated pipe made of heat-resistant steel is immersed in the drilled well. Then heated gases (hot air) are fed through it. Excess moisture evaporates, and a baking effect occurs in the clay. The peculiarity of this method: local fuel can be used to heat gases: coal, firewood.

Chemical method – mixing soil with chemical solutions

The most common of these is silicatization (silicatization). A very “broad” method consists in adding liquid glass and its solutions to the soil. It is pumped through pre-laid pipes, which are then removed. As a result of this preparation, the soil is petrified. Disadvantages – the same low frost resistance, fast hardening of the material, limited scope. Depending on the composition of the soil itself, the chemicals of the solution are also selected for work.

Electric method

In this case, the phenomenon of electroosmosis is used. There is a movement of water from “plus” to “minus”. Effective for soil dewatering.

Installation diagram for soil dehydration using the electroosmosis method: 1 – well with a metal filter inserted into it; 2 – deep pump; 3 – DC generator; 4 – metal rod

Electrochemical method

Application of electroosmosis with the addition of chemical solutions to pre-calculated areas of the field. This is done to facilitate the passage of water through the layers and give the movement the desired direction. An energy-consuming process that requires significant energy consumption.

With a sufficient level of knowledge and the presence of the necessary elements, electroosmosis can be assembled at home. Detailed assembly instructions are contained in the technical references. Electroosmosis is also used as a permanent drainage system for foundations.

Reinforcement

When constructing slopes, decorating banks and creating landscapes, a modern method is often used: reinforcement with polymer structural elements. It is effective both on flat horizontal surfaces (roads, footpaths) and in the presence of a slope.

Geogrid

As a rule, this is a three-dimensional structure consisting of polymeric perforated tapes. The very robust honeycomb construction allows movement in all planes. Any fine aggregate or local soil is simply poured into the honeycomb. No ramming required, compaction is done by spilling water. Layer thickness 10-25 cm.

Geotextile

Applied in the device of multilayer preparations. This multi-layer polymer cloth is, in fact, a high-strength filter. It allows water to pass through, but does not allow the layers to mix. At the same time, having a fair amount of strength, it distributes the load between the layers. Geotextile applications: road construction, agriculture and urban economy.

Geogrid

Accepts tensile loads. It is rarely used in soils, it is used as a thin layer reinforcement and in combination with other polymeric materials.

Sowing grass

A decorative way to strengthen the slopes from crumbling (slope no more than 1: 1.5). The grass is sown on mechanically compacted unheated slopes. Prevents washout and erosion.

There is no price for reinforcing elements on the personal plot. With their help, it becomes possible to create the most fantastic landscape designs. They also allow the creation of (imported) fertile layers for plants..