Foundations on collapsible soils

2-3x

shorter pile lengths

50+

completed projects

21-28 days

time to design strength

Practice has shown that the most effective method
for eliminating soil collapsibility is alkali treatment –
a chemical method of strengthening the foundation base.

What is alkali treatment of collapsible soils?

Alkali treatment is a chemical method of strengthening collapsible subgrades in which an alkaline solution is injected into the soil through injectors or through the shafts of helical piles. It reacts with clay particles, changing their structure, eliminating collapsibility, and increasing bearing capacity.

After treatment, collapsible or other clay soils acquire semi-rock-like properties. Such a base can carry significant loads from buildings and structures without the risk of unacceptable settlements. This makes it possible to safely build foundations on collapsible soils where other solutions are too expensive or too risky.

Eliminating soil collapsibility by alkali treatment is a proven technology that has been used in Russia for more than 40 years. The method was developed by Soviet scientists for VAZ facilities and has since been successfully used for industrial, civil, and transport projects on loess and clay bases.

Unlike costly soil replacement or the use of extra-long piles, treating collapsible soils makes it possible to save 20-60 % of the foundation budget while maintaining high reliability. This is especially important for large projects - agricultural facilities, factories, greenhouse complexes - where foundation costs can reach tens of millions of rubles.

Process diagram

injector / perforated helical pile

alkaline solution injection

chemical reaction

elimination of collapsibility

What soils is alkali treatment suitable for?

Alkali treatment is used where collapsible soils extend to depths of three meters or more and compaction or replacement do not deliver an economic benefit for building and structure foundations.

Suitable

cohesive (sandy loams, loams, and clays);
clayey fill soils;
collapsible loess;
water-saturated.

Limitations

organic content >5 %;
cohesionless (sandy and coarse-grained).

Alkali treatment and other methods of strengthening
collapsible soils

	Alkali treatment	Cementation	Silicatization	Resin grouting
Cost, RUB/m³	16,500	20,200	25,400	from 35,000
Strengthened volume	190 м³	940 м³	940 м³	940 м³
Type	Sandy loam	Sandy loam	Sandy loam	Sandy loam
Time to strength gain, days	21-30	28	14-21	7
Equipment requirements	Standard pumping equipment	Special equipment	Special equipment	Special equipment
Key limitations	Organic content no more than 5 %	Limited penetration into clay soils	K_f not less than 0.2 m/day	K_f not less than 0.5 m/day

Comparison of key parameters and cost
of different methods

Economic effect of alkali treatment

Shorter pile lengths reduce foundation construction costs in collapsible soils (illustrated by one of GlavFundament Group's projects).

Original design solution (before treatment):
1,500 piles, 11 m long.

72,500,000 RUB

Implemented design solution (after treatment):
1,500 piles, 3 m long.

40,200,000 RUB

Savings

RUB 32.3
million

Foundation types for collapsible soils:
design and construction

When traditional foundation types are used in collapsible soils, the negative impact of settlement must be considered, which requires increasing pile length and diameter or the width and thickness of strip and slab foundations. Alkali treatment eliminates collapsibility, making it possible to design foundations as if in ordinary non-collapsible soils.

Collapsible soil - which foundation type should you choose?

Traditional solutions and the benefits of alkali treatment.

01

Pile foundations

Traditional solution:the collapsible layer must be penetrated and the pile toes embedded into non-collapsible soils. Additional loading on the piles from the collapsible strata in case of wetting must also be considered.

With treatment: 50-70 % savings in pile length.

02

Strip foundations

Traditional solution:to eliminate settlement, the foundation width must be 2-3 times greater than foundations built in non-collapsible soils. This increases material consumption and excavation volume.

With treatment: reduced embedment depth and footing width.

03

Slab foundations

Traditional solution:when slab foundations are used, local wetting of the subgrade must be considered. This leads to uneven settlement and, consequently, the need to increase slab thickness and reinforcement.

With treatment: slab thickness reduced by 30-40 %.

04

Combined solutions

Traditional solution:the use of traditional foundation types together with alkali treatment removes the disadvantages caused by collapsibility, which means solutions similar to normal conditions can be used.

With treatment: maximum reliability at minimum cost.

Design and construction specifics of foundations on collapsible soils

Designing foundations on collapsible soils requires a comprehensive approach and consideration of many factors. The most important stage is analyzing the results of engineering and geotechnical surveys, determining the foundation type, and selecting optimal ground improvement measures.

During design, it is necessary to account for possible soil wetting during operation, calculate the amount of settlement, and provide measures to prevent it. Foundations are designed taking into account changes in soil properties after treatment, which makes it possible to optimize structural solutions and ensure the required bearing capacity at minimum cost.

Stages of developing structural foundation solutions for collapsible soils

Survey results: determine the thickness of the collapsible layer and the physical and mechanical properties of the soil.
Settlement analysis: determine the amount of settlement under wetting.
Improvement potential: assess the increase in bearing capacity after alkali treatment.
Foundation type: choose the optimal structural solution.
Safety assurance: confirm the adopted solutions through full-scale tests with wetting.

GlavFundament Group specializes in developing technical solutions for construction on collapsible soils, performing a full cycle of work: from survey analysis and design to implementing ground improvement and quality control. We ensure compliance with all regulatory requirements and provide long-lasting foundations for buildings and structures.

Piles in collapsible soils:
foundation design and pile length reduction

The classic solution for foundations on collapsible soils is to use long piles that pass through the collapsible layer and transfer the load to the strong stratum below. This increases construction cost and complicates the process.

The use of long piles leads to excessive material consumption and requires a large amount of drilling. And all this is needed only to "pass through" collapsible soils; this does not reflect actual joint action with the base.

10-11

meters - collapsible soil

Result:

long installation time

and high cost

11-13

meters - recommended piles

Alkali treatment and pile length reduction

After strengthening the soil mass, shorter piles can be used to work within the treated zone. Practice shows that pile length can be reduced 2-3 times without loss of foundation performance.

This solution significantly reduces material consumption and labor input in foundation construction and accelerates work without the need for extra-heavy equipment.

Project	Initial pile parameters	Pile parameters after alkali treatment	Savings
Greenhouse complex, Barnaul	length: 11 m diameter: 159 mm wall thickness: 6 mm	length: 3 m diameter: 108 mm wall thickness: 4 mm	58 % (510,000 RUB)
Production workshop, Rostov-on-Don	length: 24 m diameter: 600 mm	length: 6 m diameter: 273 mm wall thickness: 8 mm	52 % (380,000 RUB)
Apartment building, Ufa	length: 12 m section: 300x300 mm	length: 6 m section: 300x300 mm	64 % (1,800,000 RUB)

Construction of buildings on collapsible soils:
features and measures

Industrial facilities

Workshops, factories, warehouses, production buildings

Agricultural
complexes

Greenhouse complexes, farms, elevators, storage facilities

Apartment
buildings

Residential buildings of various
storeys

Engineering infrastructure

Roads, bridges, highways, utilities

Features of construction on collapsible soils

Construction on collapsible soils is complicated by the risk of differential settlement, cracking in walls, and structural failures when the base is wetted.

Collapsible soils are typical of southern regions of Russia (Orenburg Oblast, Krasnodar Krai, Rostov Oblast, Stavropol Krai, Volgograd Oblast, etc.) and require a special approach to foundation design and construction.

Alkali treatment makes it possible to purposefully change base properties both before construction starts and during operation, ensuring that foundations remain serviceable throughout the building's service life.

Alkali treatment during new construction and rehabilitation

The method is applicable both to new construction and to the rehabilitation of buildings on collapsible bases where uneven deformations have already appeared. Injectors are installed beneath the existing foundation without disturbing the integrity of load-bearing structures and gradually strengthen the soil.

Such strengthening of collapsible foundations in distressed buildings reduces additional settlements, stabilizes the overall foundation deformation, and allows further rehabilitation and vertical expansion without risk to the building as a whole.

Laying a gas pipeline in collapsible soils

Collapsible soils create risks not only for buildings but also for linear structures: pipelines, including gas pipelines and collectors. Differential settlements can lead to bends, leaks, and failures along the route.

Strengthening the collapsible foundation soils of pipeline support foundations makes it possible to level settlements with regard to operating conditions, reduce overall deformations, and ensure reliable pipeline operation and gas pipeline installation in collapsible soils.

Technology for eliminating soil collapsibility

Step-by-step process of strengthening collapsible soils with quality control at every stage.

Work stages

01

Site investigation and design calculation

Analysis of engineering and geotechnical survey results, determination of required soil parameters, layout of injectors, and required volume of alkaline solution to strengthen the base.

02

Injector installation

Installation of injectors / perforated helical piles in design position. Injector spacing is determined based on soil properties and the required improvement volume.

03

Alkaline solution injection

Injection of the alkaline solution with monitoring of flow rate and pressure. The solution spreads through the foundation mass, reacts chemically with clay minerals, and changes the soil structure.

04

Strength gain

A technological curing period is required to complete the chemical reactions and gain strength. During this time, the soil acquires semi-rock-like properties.

05

Quality control of the treated soil parameters

Control is carried out by field methods (static or dynamic sounding) or laboratory testing of treated soil based on samples recovered from boreholes. A report is issued.

06

Foundation construction

Once the design properties of the treated base have been confirmed, construction or rehabilitation on collapsible soils can begin in accordance with the design.

For most projects, this technological pause is sufficient to ensure construction proceeds without delays and with guaranteed treatment quality.

35-50 days

total duration before construction starts

Strengthening soil masses under slab foundations

When construction uses foundations with a large bearing area, such as slab foundations for apartment buildings, strengthening is performed with injectors installed on a grid at a prescribed spacing that covers the entire area of the problematic base.

For linear facilities - roads and utilities - the layout is selected so that strengthening is carried out along the route or in the most problematic zones, ensuring overall base stability.

from RUB 39.5 million

cost of work

Calculation example for a 25x50 m slab

Foundation area: 1,250 m²
Injector spacing: 1.5x1.5 m
Number of injectors: ~550 pcs.
Treatment depth: 8 m
Volume of treated soil: ~10,000 m³

Design and calculation of foundations on collapsible soils

Input data

Developing a ground treatment design requires data obtained during engineering and geotechnical investigations: thickness of the collapsible layer, filtration coefficient, moisture content, collapsibility indices, and other standard data obtained from laboratory tests.

Based on these data, the feasibility of treating collapsible soils is determined, the parameters of the alkaline solution are selected, and the injector layout is established to ensure the required bearing capacity of the foundation soil.

Documents required to prepare a technical solution:

engineering and geotechnical investigation report with a full set of laboratory soil tests;
site plan showing building locations;
loads on the foundation from the designed building or structure;
site hydrogeology for assessing the risk of wetting collapsible soils.

Calculation of foundations on collapsible soils taking treatment into account

In foundation design, the increase in strength and decrease in soil deformability after alkali treatment are taken into account. This makes it possible to optimize footing size, embedment depth, and foundation type.

GlavFundament Group uses an approach in which the treated base is analyzed by numerical modeling with the specified post-treatment properties. The behavior of treated and untreated soil under load is simulated. Since alkali treatment is carried out only in the zone of maximum stress development, all loads are carried by the strengthened soil mass. This makes it possible to obtain an integrated solution: a reliable base, predictable settlements, and an economical foundation.

Measures for construction on collapsible soils

Alkali treatment is part of a package of measures: besides ground improvement, drainage, wetting control, planning solutions, and protective measures for foundations may be used. This approach makes it possible not only to strengthen collapsible soils but also to manage the factors that cause settlement, which is especially important when constructing buildings and structures under difficult conditions.

01

Soil mass treatment

Chemical strengthening of collapsible soils is the main measure for
increasing base bearing capacity and eliminating collapsibility.

02

Water protection measures

Diversion of surface water or lowering groundwater levels to prevent wetting of collapsible soil during building operation.

03

Site planning solutions

Site grading to direct water away from foundations, with apron paving and storm drainage.

04

Deformation monitoring

Geodetic monitoring of foundation settlements during construction and in the first years of operation of buildings on collapsible soils.

Scientific support for construction on collapsible soils

The alkali treatment method is based on the results of many years of research
and the implementation of a large number of projects. At GlavFundament Group,
the development of the technology is led by its in-house research
and development department.

More than 5

Russian patents for the technology

50+

projects with alkali treatment

More than 40

years of practical experience

Our R&D department, including PhD-level specialists, provides scientific support for construction on collapsible soils. We analyze survey results, develop treatment solutions for collapsible soils, cooperate with designers, assist with expert review approval, and provide guarantees for the bearing capacity of the treated base. Our experience covers all regions of Russia, from Krasnodar to Volgograd and Orenburg Oblast.

Research on alkali treatment of collapsible

soils in Russia

The alkali treatment method in Russia was studied in detail by Felix Evseevich Volkov and his colleagues on clay and loess foundation soils of buildings, including industrial and civil facilities.

Results of field and laboratory tests showed the durability of the effect and the irreversibility of changes in soil structure, which makes it possible to confidently use alkali treatment to strengthen collapsible soils beneath buildings and structures.

Felix Evseevich Volkov

Key scientific publications on the alkali treatment method

Volkov F. E., Rozhnova T. N., Belyaev V. P. Study of the treatability of VAZ foundation loess-like soils by alkali treatment // Soil Mechanics. Ufa: 1986. pp. 65-77.
Volkov F. E., Zlochevskaya R. I., Voronkevich S. D. On the interaction of clay minerals with alkali solutions // Moscow State University Bulletin, Geology Series. 1976. No. 3. pp. 87-95.
Volkov F. E. Changes in the composition and physical-mechanical properties of clay soils as a result of interaction with alkali solutions. Extended abstract of Candidate of Geological and Mineralogical Sciences dissertation. Moscow: MSU, 1977. 24 p.
Zlochevskaya R. I., Volkov F. E., Voronkevich S. D., Divisilova V. I. Stabilization of clay and loess soils with concentrated alkali solutions // Issues of Engineering Geology and Soil Science. Moscow: MSU Press, 1983. Issue 5. pp. 384-397.
Volkov F. E., Zlochevskaya R. I. A new chemical method for stabilizing water-saturated loess and clay soils - "alkali treatment" // Engineering Geology. 1988. No. 1. pp. 15-29.

And 20 more scientific papers in Russian and international publications.

Examples of projects on collapsible soils

Real projects by GlavFundament for strengthening collapsible and loess soils by alkali treatment with confirmed savings.

Greenhouse complex

Altai Krai

Type:

Sandy loam collapsible
Layer thickness:

10 m
Before:

Piles 11 m x 1,500 pcs.
After:

Piles 3 m x 1,500 pcs.

RUB 42.3 million

45 % savings

Production workshop

Rostov-on-Don

Type:

Collapsible loam
Layer thickness:

20 m
Before:

Piles 24 m x 52
pcs.
After:

Piles 6 m x 52 pcs.

RUB 9.0 million

34 % savings

Apartment building

Volgograd

Type:

Collapsible loess
Layer thickness:

11 m
Before:

Piles 13 m x 120
pcs.
After:

Piles 6 m x 96 pcs.

RUB 6.0 million

24 % savings

In practical examples, savings of 20-60% on foundations are achieved through reductions in pile length, pile diameter, and work volume, while foundations on collapsible soils remain reliable and are confirmed by testing. Alkali treatment eliminates the risk of emergency deformations, reduces operating costs, and improves the safety of buildings and structures.

How to order strengthening of collapsible soils

What is needed to prepare a technical solution

To develop a technical solution for strengthening collapsible soils, it is necessary to provide engineering and geotechnical survey data, planned building loads, and the general site development layout.

Based on these materials, we select the alkali treatment scheme and foundation type and offer the client a clear solution with schedule and cost calculations.

Guarantees for soil bearing capacity

GlavFundament provides a guarantee for the bearing capacity of the treated soil for a term agreed with the client and fixed in the contract. The warranty obligations are based on test results and the scientifically grounded alkali treatment methodology.

After completion of the work and base testing, the client receives a package of documents confirming soil and base properties, which is important for construction supervision and building operation.

Stages of cooperation with GlavFundament Group:

Consultation: analysis of input data and project objectives.
Technical solution: calculation of the alkali treatment scheme and selection of the foundation type (3-5 days).
Commercial proposal: preparation of a work estimate with stage-by-stage breakdown.
Contract: signing the contract with schedule and warranty terms fixed.
Execution of works: alkali treatment with quality control (35-50 days).
Testing and documentation: confirmation of treated base characteristics.

Calculate cost

Anton Olegovich Glazachev

Head of R&D Department

niokr@glavfundament.ru

8 (967) 741-01-29

What are collapsible soils?

Collapsible soils are clayey and loess soils that, when soaked with water, sharply lose strength and undergo significant settlement (collapse settlement) under load. They are typical of southern Russian regions: Krasnodar Krai, Orenburg Oblast, Rostov Oblast, Stavropol Krai, Volgograd Oblast, Saratov Oblast, and others.

Collapsibility is determined by the coefficient ε_sl; when the value is >0.01, the soil is classified as collapsible.

How durable is the strengthening effect in collapsible soils?

Changes in soil structure after alkali treatment are irreversible. Studies by F.E. Volkov and observations of real projects have shown that this effect is preserved. GlavFundament provides a warranty on the bearing capacity of the strengthened foundation soil for the entire standard service life of the facility.

Can alkali treatment be carried out beneath operating buildings?

Yes. The method can be used to reconstruct and strengthen the foundations of any buildings. Injectors are inserted into the base beneath the existing foundation without disturbing the integrity of the load-bearing structures. The technology makes it possible to stabilize collapsible soils beneath buildings and structures, reduce deformations, and carry out further reconstruction without compromising safety.

What happens to groundwater after alkali treatment?

The alkaline solution remains localized within the collapsible-soil strengthening zone. With proper design, the impact on groundwater is minimal: the reaction with clay minerals continues until the alkali is fully consumed. The solution continuously binds with the clay minerals and does not migrate. During the work, groundwater pH is monitored in adjacent boreholes to control environmental impact.

What engineering and geotechnical investigations are required for alkali treatment?

An engineering and geotechnical survey report is required, including engineering-geological cross-sections, groundwater data, and the standard physical and mechanical properties of the investigated soils.

How does alkali treatment differ from cementation?

In alkali treatment, the injected solution is only one of the components required for the reaction. Alkali treatment works in clayey and loess collapsible soils by using the soil's own resources. The solution contains no particles and can therefore penetrate the soil pores freely.

Cementation involves introducing all components required for the reaction. Cement particles are much larger than the soil pores, so a high filtration coefficient is required. Alkali treatment is 20-30 % cheaper (RUB 16,500/m³ versus RUB 20,200/m³) and does not require special equipment to prepare and mix the solution. For collapsible soils, alkali treatment is the optimal solution in terms of price-to-performance ratio.

Can apartment buildings be constructed on collapsible soils?

Yes, provided the foundation soil is strengthened. Alkali treatment makes it possible to achieve the required soil bearing capacity for constructing buildings of various heights on collapsible soils. The method has been successfully used for residential developments in Volgograd, Rostov-on-Don, and other cities with collapsible soils.

Foundations on collapsible soils:eliminating soil collapsibility with savings of up to 60 %