In civil and industrial construction, when arranging underground communications, engineering networks, pipelines, and heating mains, impassable channels are very often used. This is the name of reinforced concrete products designed to protect shallowly laid engineering networks. What is the peculiarity of impassable channels, what products have characteristics and what gives their use? More on that later.
Why do we need impassable channels and what is it?
All communication networks that are laid at a shallow depth need protection from the influence of the external environment: very often pipelines are laid under roads, objects under construction, etc. Due to the use of impassable channels, pipelines are protected from mechanical damage. What does "impassable" mean? This means that workers will not walk along the canal, therefore, these structures are used only when the laid communications do not need frequent repairs or constant maintenance.
Produce products from reinforced concrete. They consist of 2parts:
- U-shaped frame element. It is installed and fixed at the bottom.
- Bottoms. This is a flat element with low sides on both sides. Despite the name, the bottom is not laid on the bottom of the pit, but on top of the frame element. Thanks to this, a closed channel is formed in which the laid networks are located.
Both the bottom and the frame element usually have the same dimensions. Products differ in the height of the sides and where the embedded elements and mounting loops are located.
Design characteristics
For the manufacture of products of impassable types, manufacturers use only heavy grade concrete. Products are reinforced with flexible but strong steel.
In the manufacture of impassable channels, all the recommendations mentioned in the regulatory documents are strictly observed. Thanks to this, reinforced concrete elements have the properties necessary for their operation:
- Resistant to organic decay.
- Strength.
- Frost resistance - from F75 and above.
- Water resistant higher than W4.
Advantages of reinforced concrete structures
The advantages of non-passing channels include such characteristics as:
- Exceptional durability - each piece is designed to last 40 years or more.
- Easy installation, which is possible at any time of the year, regardless of weather conditions.
- Strength. Thanks to the reinforcement of the structure, they perfectly resist soil movement, protecting the pipes inside.
- Resistant to many harsh environments.
- Excellent tolerance for long and significant temperature changes.
- Affordable price.
- Easy to make. Designs have a simple form, which does not complicate their production, so manufacturers can always offer the required number of products needed for a particular object.
Product classification
Non-through channels, according to their overall dimensions, are divided into several types (see table).
|
Product brand |
Height (cm) | Width (cm) | Length (cm) | Weight (kg) |
| KN-1 | 28 | 89 | 199 | 500 |
| KN-2 | 34 | 114 | 199 | 730 |
| KN-3 | 41 | 139 | 199 | 870 |
| KN-4 | 49 | 164 | 199 | 1050 |
| KN-5 | 54 | 174 | 199 | 1150 |
| KN-6 | 66 | 226 | 199 | 1720 |
| KN-7 | 78 | 308 | 149 | 2400 |
Note: in some cases, if necessary, manufacturers produce impassable channels weighing more than 2.4 tons. Such products are considered oversized and require the use of special vehicles for both transportation and installation.
The type of materials used in production depends on the type of products. So, on constructions of the type from KN-1 to KN-4, class B15 concrete is used. For the manufacture of impassable channels KN from 5 to 7 grades, only concrete of class B20 can be used. Reinforcement is done with steel Bp-I, A-III, A-I.
Features of use
Regulatory requirements state that non-through channels can only be used in the following cases when:
- Networks pass through non-subsidence soils.
- Soils are slightly aggressive towards concrete.
- Ground water at maximum rise does not reach the depth where the collector is laid.
The selection of the size of non-through channels suitable for installation on a particular object depends on several parameters:
- Heights of supports.
- The thickness of the thermal insulation of the pipeline.
- The distance at which adjacent utilities are laid.
- The presence of a road, a sidewalk, which will later pass through the laid system.
Installation andfurnishing
The installation of impassable channels for water supply, heating mains and other pressure networks begins with the preparation of the pit. Its depth depends on the dimensions of the installed elements. At the bottom of the pit, a pillow of concrete or sand is arranged. After that, U-shaped elements are installed with a slight slope, so that in the event of condensation or seepage of moisture from the soil, it flows to the place where it will be pumped out or it will continue to flow by gravity into the ground.
After the pressure network is laid inside the lower element, the bottom is laid on top and the joints are sealed with concrete mortar. On top of the structure, a pasting or coating waterproofing is equipped and then a layer of soil is poured. If it becomes necessary to repair or replace the network passing inside the impassable channel, you only need to open the ground to the mark where the top of the protective element is located and lift it by picking up the structure by the mounting loops.
Because getting to the pressure line is quite difficult - for this you need to take out a significant amount of soil, the structures are used only on those networks that do not need frequent repairs or constant maintenance.
Protection of the structure from groundwater ingress
Moisture is the main enemy of pipelines passing inside impassable channels: it destroys both the heat-shielding layer and the pipes themselves. So that in the spring or during the period of prolonged rains, sedimentary water does not get inside the channel, drainage will need to be arranged. It must be located withboth sides of the track.
Perforated asbestos-cement pipes are commonly used as drainage. Under their installation, they dig a pit with a depth lower than the bottom of the collector is located. 20-30 cm are added to the depth of the pit for drainage material. After that, drainage is made of sand, gravel, on which a perforated pipe is laid. It is first covered with gravel so that the water has access to the holes in the pipe. Only after that, the drainage structure is covered with soil.
