PECULIARITIES OF DESIGN AND CONSTRUCTION OF BUILDINGS AND STRUCTURES IN THE ARCTIC ZONE

ОСОБЕННОСТИ ПРОЕКТИРОВАНИЯ И СТРОИТЕЛЬСТВА ЗДАНИЙ И СООРУЖЕНИЙ В АРКТИЧЕСКОЙ ЗОНЕ

Манжос Алина Леонидовна

студент, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

Прибега Руслан Юрьевич

студент, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

Юдина Ирина Ивановна

преподаватель, Национальный Исследовательский Московский Государственный Строительный Университет,

РФ, г. Москва

АННОТАЦИЯ

В данной статье рассматриваются факторы, которые следует учитывать при проектировании и строительстве зданий и сооружений в Арктической зоне; определяются основные проблемы, возникающие при строительстве зданий и сооружений в Арктических условиях; описываются основные типы разрушения бетонных и железобетонных конструкций, а также перечисляются современные технологии выполнения бетонных работ в Арктической зоне.

ABSTRACT

This article examines the factors that should be taken into account when designing and constructing buildings and structures in the Arctic zone; it identifies the main problems that arise during the construction of buildings and structures in Arctic conditions; it describes the main types of destruction of concrete and reinforced concrete structures, and it also lists modern technologies for concrete work in the Arctic zone.

Ключевые слова: арктическая зона, здания, сооружения, строительство, низкие температуры, технологии, строительные материалы.

Keywords: arctic zone, buildings, structures, construction, low temperatures, modern technologies, building materials.

The Arctic is the territory of the Arctic Ocean, the islands of the ocean and the northern outskirts of Europe, Asia, and America. The region is located in the Arctic climate zone. It is always cold here, even in summer the temperature does not exceed zero degrees. Winter temperatures vary significantly in different territorial areas.

The minimum temperature of 60 degrees below zero the region recorded a Celsius. However, despite such a cold climate, there is life there, various buildings and structures are being erected. The construction of residential buildings, the placement of production and other facilities necessary for life in the developing regions of the Arctic is an important task.

Certain factors must be taken into account when designing buildings and structures in the Arctic zone:

1. Climatic conditions (strong winds combined with low temperatures and a lot of snow)
2. Safety of buildings and structures and their protection from external negative environmental conditions
3. Correct choice of the location of the building, the rejection of high-rise buildings
4. Reduced number of windows (the need to exclude balconies, terraces and loggias)
5. Increased reliability of sealing windows and doors
6. Creation of comfortable working conditions

The main problem of the Arctic zone is the permafrost soil in the Arctic, on which it is very difficult to start building any structures. In the period 1930-1950, it was supposed to isolate a person from the external environment as much as possible. These proposals had no scientific justification, and the construction technique in cold areas with sufficiently low temperatures was not yet used at that time. It all came down to increasing the thickness of walls and fences in accordance with the calculated outdoor temperatures in a given construction area.

Let us consider some features of design and construction in permafrost conditions. Permafrost territories, like every natural and climatic zone, are unusual in their own way. And it is possible to build buildings and structures in any climatic conditions. First of all, it is necessary to follow certain requirements for construction and design. And then any building will function at the same level as in temperate latitudes.

What requirements must be observed during the construction and design of buildings in permafrost conditions? According to building codes, there are two principles of design and construction in permafrost conditions.

The first principle is that the permafrost state of the soil is preserved at the base of buildings and structures, both during construction and during the entire period of operation. This principle is applied in situations where the preservation of frozen soil in its original state is economically feasible. Following the first principle, preference is given to a pile or columnar foundation. But other solutions can also be applied, for example, a ribbon foundation. The only condition is to prevent the upper layer of the soil from changing its properties under the influence of heat from the operated structure. To do this, the underground is made cold. It is also possible to make a solid layer of thermal insulation with high insulating properties under the entire building, which will keep the soil in its natural state.

When laying foundations on permafrost, it is important to correctly determine the depth of its foundation. For different types of structures, its value is assigned separately:

1. For pile foundations, the depth of laying should be at least two meters greater than the thickness of the soil layer, since this soil seasonally thaws and freezes
2. For all other types of foundations, the depth of their laying is set to be greater than the thickness of seasonally thawing soil by one meter

The second principle is that before construction, the soils are thawed in advance or apply soils that thaw at the time of operation. In this case, the permafrost of the soils is not preserved. This method is used less often and provided that the soil on the construction site is not heaving. In this case, the soil is either thawed before the foundation is erected, or all necessary calculations are carried out and it is assumed that the base of the soil will thaw during the operation of the building.

One of the problems existing during construction in the Arctic zone is the process of design and construction of structures itself. Permafrost can cause displacement and deformation of the soil, and this can lead to damage or destruction of structures.

Another big problem is the influence of cold on the concrete components of buildings. Low temperatures create unfavorable conditions for construction work and can lead to deformation and destruction of concrete. In the cold season, concrete is subjected to cyclic freezing-thawing. The negative effect of low temperatures on concrete is primarily due to the freezing of chemically unrelated water, which is part of the concrete.

With alternating freezing and thawing, there are three main types of concrete destruction:

1. Peeling of the protective layer of concrete structures. This happens when carbon dioxide and moisture penetrate into the concrete body through its natural pores, and the lower the grade of concrete, the higher its porosity, and the faster this process will occur under favorable conditions. This process begins immediately from the moment of manufacture of the reinforced concrete structure and lasts the entire life cycle of concrete: calcium hydroxide gradually turns into its carbonate. During this reaction, the pH of concrete decreases from 12 to 9, resulting in a comfortable environment for reinforcement corrosion.
2. Corrosion of the reinforcement. It is the corrosion of reinforcement that can significantly reduce the service life of building structures. The destruction of metal, of course, does not happen instantly. In order to slow down or prevent metal corrosion, you need to think about ensuring that there are no impurities in the concrete that aggressively affect the metal. The manifestation of reinforcement corrosion in structures subjected to significant loads is especially dangerous. Reinforcement corrosion occurs under the influence of atmospheric and chemical factors on reinforced concrete, both aggressive atmospheric components (sulfates, carbonates, chlorides) and frequent frost–thaw cycles.
3. Surface chips of concrete structures. Chipping can lead to the exposure of steel rods, and, in turn, this can lead to the appearance and development of foci of corrosion. The reinforcement gradually loses its performance characteristics, which leads to deformation and subsequent destruction of concrete. Chips most often occur at the corners of the structure.

The destruction of concrete under the influence of negative temperatures can occur under the influence of various factors. The pressure of the liquid formed during ice formation has a negative effect on the walls of pores and capillaries of the cement frame. Additional efforts are also created due to various coefficients of temperature deformations between the skeleton and the ice. Osmotic influence and temperature forces are two more factors contributing to the destruction of concrete structures. When carrying out concrete and stone works, special requirements must be met:

1. The laying of concrete should be carried out on a base, the condition of which completely eliminates the freezing of the mixture along the joint line with it, as well as the possibility of deformations due to the heaviness of the soil. For these purposes, the base of the concreting site is heated until it reaches a positive temperature.
2. Immediately before the start of concreting work, the formwork and fittings are cleaned of ice and snow masses. If the diameter of the reinforcement exceeds 25 mm, or it is made of rigid profiled rolled products or contains metal embedded elements of significant size, then in conditions of negative temperatures less than 10 degrees below zero Celsius, the reinforcement should be heated.
3. Concreting processes at subzero temperatures are carried out quickly and continuously – each underlying layer of concrete should be covered with a new one.

Modern technologies for performing concrete works in permafrost conditions make it possible to achieve high-quality building structures at an optimal cost level. Modern technologies are conventionally divided into three groups:

1. Thermos technology based on the preservation of the initial heat of the mixture heated during the preparation or before laying at the work site, as well as on the use of heat generated by the reaction of cement with water during the curing of concrete
2. The technology of artificial heating of the concrete mix after its installation in the structure
3. Technology of chemical reduction of the freezing point of water in the composition of the concrete mixture and increase the reaction rate of cement

In the harsh weather conditions of the Arctic zone, it is necessary to significantly take into account and overcome these problems in order to ensure the reliability and durability of buildings and structures.

The following building materials are used for the construction of buildings in the Arctic:

1. Sulfur concrete. This is a special high-strength concrete with the addition of sulfur and turpentine-containing waste from deep processing of wood. This material quickly gains strength and does not depend on temperature conditions.
2. Flexible sandwiches. This is a new type of building material, which consists of two PVC awning layers with insulation between them. The flexible sandwich withstands frost, has high waterproofing properties, and the material is easy to install.
3. High-tech thermal insulation. This is a new thermal insulation material, which consists of special polyurethane foam and other components. High-tech thermal insulation allows you to create a closed thermal circuit in houses.
4. Ground concrete made of granulated slag. This is a special ground concrete based on granular slag, the material is used to strengthen river banks and prepare the foundation for the roadbed.

In conclusion, it should be noted that buildings and structures can be built in any climatic conditions with the use of certain materials and compliance with norms and rules, design and operation of buildings and structures.

References:

1. Moskvin V. M., Kapkin M. M., Mazur B. M., Podvalny A.M. Resistance of concrete and reinforced concrete at negative temperature. Gosstroyizdat,1967. 132c.
2. A. F. Milovanov. Reinforced concrete temperature-resistant structures. M.: Publishing House NIIZHB, 2005. 234c.
3. Kuntsevich O.V. High frost resistance concretes for structures of the Far North. L.: Stroyizdat, 1983. 130 p.
4. JSC KTB Reinforced Concrete [Electronic resource]/Access mode: https://www.ktbbeton.com/press/articles/rabota_i_razrushenie_betona_v_usloviyakh_vysokikh_/ (accessed 18.01.2021).
5. Technical expert. GOST 10060-2012 Concrete. Methods for determining frost resistance [Electronic resource]/Access mode: http://docs . cntd. ru/document.