Reinforced concrete supports are a bearing element in the construction of power lines. They are loaded with heavy loads mainly from the effects of the environment, so the use of a combination of concrete and metal is fully justified. There are different types of such supports, each of which has its own purpose. The technology of installation is complicated by the fact that even in the simplest version the reinforced concrete support has a large mass and requires special equipment for installation.
Construction of reinforced concrete support
The basis of the support is concrete, reinforced with a metal frame. Depending on the purpose, different composition of solutions can be used. For example, the maintenance of power lines from 35 to 110 kV is carried out using supports from centrifuged mixtures of concrete. The advantages of the construction of reinforced concrete supports include resistance to corrosion processes, as well as the effects of chemicals and elements that are contained in the air. There are disadvantages to such supports. First of all, this is a significant mass, due to which the working operations for their installation and transportation are also complicated. Also, the material has a relative sensitivity to mechanical influences. For example, when transporting the supports are often damaged - on their surface there are cracks and chips.
Rigging of concrete supports
Supports of reinforced concrete can be supplied with a metal frame formed by reinforcing steel. Thanks to it, the design achieves high reliability and protection from external influences. Also the armature is intended for installation of wires on hooks or traverses. In the first variant, supports are used in which the corresponding holes for the introduction of hooks have been made at the factory. It is important to note that the supply of functional components can be carried out before the installation of reinforced concrete supports in the work area. This feature distinguishes such structures from wooden, the rigging of which can be carried out only after installation.
Classification by installation method
There are different approaches to the installation of reinforced concrete pillars. In this case we are talking about methods of fixation in the ground - with mounting on the foundation and with direct immersion in the ground. Supports that are attached to the basement are also of two types: narrow-base and classical. The first version is a construction that is installed on steel or reinforced concrete piles. The second option involves immersion in the ground with subsequent pouring of concrete. This reinforced concrete support is also called a frame or wire frame. It is used as an element of the foundation construction. Supports, which are directly fixed in the ground, are usually used as a load-bearing structure of lighting systems, electrical lines, etc.
Classification according to purpose
In essence, a simple and reliable design has led to a wide range of applications of such elements. To date, we can distinguish the following types of reinforced concrete supports, based on their designation:
- Corner. Used at the corners in the corners of the airway route (VL). Depending on the magnitude of the angle of rotation, other types of supports can be used for this purpose.
- Intermediate. Serves direct sections of the highways. Such models are designed to support cables and cables, but they can not be used if additional loads are assumed.
- Anchoring. Also used on straight sections of overhead lines, but have one feature. With the help of anchor supports, transitional zones are formed through natural barriers, engineering structures and other structures.
- The end. These supports begin and end air lines.
- A special reinforced concrete support is also distributed, which serves to change the configuration in the wires, and also provides support in complex areas with branches, junctions and intersections.
Features of supports for power lines
Supports made of reinforced concrete are the best solution for providing support for overhead power lines. Metal and wood analogues are also used for this purpose, but have a number of serious limitations. However, the reinforced concrete poles also have load sharing on the networks with which they can work. In particular, there are supports for lines from 10 to 1150 kV. In such a wide range, designs with different parameters are presented. The higher the voltage, the greater the mass and length of the beam is the reinforced concrete support included in the network. It would seem that if the lines are approximately equal to the distance from the ground and the physical load on the structure is the same, what causes the need to change the characteristics of the support? In fact, it is fully justified by technological requirements, which prescribe different standards for distances from the line to the support and the surface of the earth depending on the voltage.
Work activities are initiated only after completion of site preparation and delivery of components for installation. Next, the materials are laid out, analysis is carried out, a plan is drawn up and grounding is performed. After this, the assembly of the structure and its elements begins. Direct installation of reinforced concrete supports is performed by special machines: installation cranes or boom equipment. Stretching can also be carried out by the tractor. Also, a foundation pit is prepared, the diameter of which may exceed the analogous indicator of the rack by no more than 25%.
If you plan to install portal or double-column supports, then the installation is carried out in sequence: first one, and then the second post. Then follows the installation of traverses, endings of interstitial cross ligaments and fixation of their lower endings. When lifting and installation of supports by special equipment will be carried out, the constructions are temporarily unfastened by special braces, after which bolts are installed. To proceed to the final stage in the installation of supports with soil backfilling can be after the alignment of the position of the structure will be carried out.