How to solve the problem of heaving soils

Construction projects may face serious difficulties due to heaving soils, especially in regions where seasonal variations result in soil expansion and contraction. These changes may result in expensive structural issues such as uneven flooring, foundation cracks, and other issues. Any building project that is going to be successful needs to understand the nature of heaving soils and how to address them.

Water content is one of the main reasons for soil heaving. Soil expands when it takes in water and contracts when it dries out. Over time, the tremendous pressure that this continuous movement can put on structures can cause damage. Builders can undertake measures to lessen these impacts by determining the kind of soil and its properties.

Heaving soils can be managed in a number of ways, such as by utilizing moisture barriers, choosing suitable foundation designs, and enhancing drainage around the construction site. Depending on the site’s particulars and the degree of heaving, each technique has benefits and is appropriate in a variety of scenarios.

Builders can guarantee the longevity and stability of their structures by proactively addressing the issue of heaving soils. Any project can benefit from a strong foundation and the reduction of soil movement’s negative effects with the appropriate strategy.

How heaving occurs

Water’s volume changes to the greater side when it freezes because its density is higher than ice’s. In light of this, the soil’s mass expands due to moisture content. Thus, the idea of frost heaving forces—that is, forces influencing the expansion of soil—was born. In this instance, the soil is referred to as heaving.

Practical! Typically, the soil expansion level is 0.01. This indicates that the volume of the soil will rise by at least 1 cm if the earth’s top layer freezes to a depth of 1 m.

Frost heaving happens for a number of reasons:

• Due to the depth of the upper aquifer. If the water is located close to the surface, then even if the clay is replaced with gravel sand, it will be ineffective.
• Based on the depth of soil freezing during the cold period in a particular region.
• Depending on the type of soil. Clay and loam contain the most water.

Heaving and non-heaving soils are distinguished by their soil composition and climate.

What is the difference between heaving and non-heaving foundations

GOST 25100-2011 classifies soils into 5 groups based on the degree of heaving they exhibit.

• Excessively heaving (the level of soil expansion is more than 12%);
• Strongly heaving – 12%;
• Moderately heaving – about 8%;
• Weakly heaving – about 4%;
• Non-heaving – less than 4%.

Since dry soil is almost nonexistent in the natural world, the final category is regarded as conditional. Such foundations can only be made of granite and coarse-grained rocks, but these kinds of soils are very uncommon in our environment.

When discussing heaving soil and how to identify it, it’s important to take into account both its composition and groundwater level.

Concrete structures are susceptible to serious damage from heaving soils, but with the right methods, you can effectively address this issue. You can safeguard your foundations and guarantee long-lasting stability by being aware of the behavior of the soil, utilizing appropriate drainage solutions, and putting techniques like soil stabilization and reinforcement into practice. This article will assist you in maintaining the integrity of your concrete projects by examining doable, straightforward steps for managing and mitigating the difficulties caused by heaving soils.

How to determine the degree of soil heaving yourself

The simplest method to find out whether your site has heaving soils at home is to excavate a pit (vertical excavation) that is about 2 meters deep and then watch it for a few days. It is required to drill a well 1.5 meters deeper using a garden drill if water has not formed at the bottom of the dug pit. A bar is used to measure the depth of the groundwater below the surface when water starts to appear in the well.

Visual inspection of the soil is sufficient to identify the type of soil. You can infer some general conclusions about the extent of the earth’s expansion during the cold season from this data.

The GWL will be lower than the predicted freezing depth if there is a small amount of soil heaving. The type of soil directly affects this value:

• silty sands – 0.5 m;
• sandy loam – no more than 1.0 m;
• loams – 1.5 m;
• clay – 2 m.

The groundwater level will be below the freezing depth if the soil is categorized as medium heaving by:

• 0.5 m, if sandy loams predominate;
• 1.0 m – loams;
• 1.5 – clay.

The GWL will be less if the soil is severely heaving by:

• 0.3 m – if the soil mainly consists of sandy loam;
• 0.7 m – loam;
• 1.0 m – clay.

This is not the ideal base for a shallow foundation if clay and loam are found relatively close to the estimated depth of soil freezing. That being said, this does not preclude building on such soils.

How to solve the problem of heaving soils

The degree of soil heaving can be decreased in a variety of ways. Let’s think about the most typical.

Soil replacement

Since replacing heaving soil requires completely excavating the soil at the location of the future building, it is thought to be the most costly and labor-intensive procedure. After that, the foundation is built on non-heaving soil and fresh soil, or coarse sand, and gravel are poured in.

Weighting the building

The building is more likely to be under soil pressure and swell during the winter months if its weight is lower. It is advised to construct larger structures in order to stop this from occurring. However, there are significant financial consequences as well.

Construction of a slab foundation

By using a slab foundation as the house’s base, you can increase the building’s weight and relieve soil pressure. Frost heaving forces will affect a solid monolithic slab buried deeper than 20 cm; however, in this instance, the slab will simply rise uniformly during the winter and return to its original position when the air temperature rises.

Slab foundation construction is technically simple (problems may only occur during the reinforcing phase), but the cost of this type of foundation will also be high.

Installation of a pile foundation

Installing a pile foundation will be the least expensive option if you want to survive with minimal casualties. It should be remembered, though, that these kinds of structures are limited to lightweight homes (frame, SIP panel structures, etc.).

The following can serve as a starting point:

• screw piles, which are screwed into the soil just below the freezing level;
• reinforced structures (in this case, it is necessary to prepare wells and install rods wrapped with roofing felt and a metal frame in them).

Following the pile installation, load-distributing slabs or beams (grillage), which are insulated with foam or polystyrene foam and placed around the perimeter of the future building, are used to connect the elements.

On heaving soils, some builders construct brick columnar buildings up to 60 cm high, deepening the foundation by approximately 15 cm; however, these foundations are only appropriate for summer kitchens, pavilions, and other non-living structures.

Permanent heating of the house

The soil beneath a heated and unheated house will have a temperature that is nearly 20% higher in the former scenario. In light of this, the heaving force will be minimal if residents live in the building year-round and it is heated.

Soil drainage

You can lower the ground’s water content to stop soil expansion. In order to accomplish this, a drainage well must be constructed and placed some distance away from the building. In order to create such a system, you must:

• Dig a trench around the house.
• Lay pipes with small holes on the sides in it. To ensure that water flows away from the house by gravity, you need to lay the pipes at a slight slope towards the drainage well. Accordingly, the closer the pipeline is to the well, the deeper it is laid.
• Sprinkle the pipes with gravel and cover them with geotextile.

Soil thermal insulation

One way to lessen soil heaving is to construct a blind area. Typically, a structure of this kind is constructed around the building’s perimeter to shield the foundation from precipitation. However, you can lessen the amount of soil expansion in the winter by adding more robust thermal insulation to the blind area.

You have to follow these guidelines in order to create an insulated blind area:

• The width of the blind area should be 1-1.5 m greater than the width of soil freezing.
• It is recommended to use sand as a base for the blind area, which is carefully tamped and poured with water.
• Expanded polystyrene or any other insulation is laid on the sand in a layer of about 10 cm.
• Waterproofing (roofing felt) is laid on top.
• Crushed stone is laid on the waterproofing layer and everything is poured with concrete.
• Before concreting, it is recommended to reinforce with a steel mesh with a diameter of 4 mm and a cell size of 15 x 15 mm.

Although handling heaving soils can be difficult, it is doable with the appropriate strategy. The first step is to understand the properties of soil and how moisture affects it. Soil heaving can be greatly decreased by installing appropriate drainage systems and making sure that water is directed away from the foundation.

Another way to lessen the issue is to apply soil stabilization techniques, like adding lime or other stabilizing agents. By altering the soil’s characteristics, these techniques reduce the soil’s propensity to expand and contract in response to variations in moisture.

A long-term fix for buildings already impacted by heaving soils can be found with underpinning and other foundation repair methods. By using these techniques, the current foundation is stabilized and additional movement brought on by the expanding soil is stopped.

In the end, treating heaving soils calls for a mix of preventative and corrective measures. You can safeguard your structures and keep them intact over time by being aware of the root causes and taking preventative action. Remember that the secret to effectively managing heaving soils is to have a well-planned strategy.

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