Reinforced concrete supports are a supporting element in the construction of power lines. They bear heavy loads mainly from environmental influences, so the use of a combination of concrete and metal is justified. There are different types of such supports, each of which has its own purpose. The installation technology is complicated by the fact that even in the simplest version, the reinforced concrete support has a large mass and requires the use of special equipment for installation.
Reinforced concrete support structure
The base of the support is concrete reinforced with a metal frame. Depending on the purpose, different solution compositions can be used. For example, maintenance of power lines from 35 to 110 kV is carried out with the help of supports made of centrifuged concrete mixtures. The advantages that the construction of reinforced concrete supports possess include resistance to corrosion processes, as well as the effects of chemicals and elements that are contained in the air. Such supports also have disadvantages. First of all, this is a significant mass, due to which the work operations for their installation and transportation are complicated. Also, the material has a relative sensitivity to mechanical stress. For example, during transportation, the supports are often damaged - cracks and chips are found on their surface.
Reinforced concrete equipment
Reinforced concrete supports can be equipped with a metal frame formed by reinforcing steel. Thanks to it, the design gains high reliability and protection against external influences. Also, the fittings are designed to install wires on hooks or traverses. In the first version, supports are used, in which the corresponding holes for the introduction of hooks were made at the factory. It is important to note that the supply of functional components can be performed before the installation of reinforced concrete supports at the work site. This feature distinguishes such structures from wooden ones, the equipment of which can be carried out only after installation.
Classification by installation method
There are different approaches to installing reinforced concrete supports. 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. The supports, which are mounted on the basis of the foundation, also come in two types: narrow-base and classic. The first variety is a design that is installed on steel or reinforced concrete piles. The second option involves immersion in the ground, followed by pouring concrete. Such a reinforced concrete support is also called frame or frame. It is used as an element of the construction of foundations. Supports that are directly fixed in the ground are usually used as a supporting structure for lighting systems, electrical lines, etc.
Intended classification
In fact, a simple and reliable design has led to a wide range of applications for such elements. To date, the following types of reinforced concrete supports can be distinguished based on their purpose:
- Corner Used at corners in turns of the overhead line (VL) route. Depending on the size of the angle of rotation, other types of supports can be used for this purpose.
- Intermediate. Serve direct sections of the OHL routes. Such models are designed to support cables and cables, but they can not be used if additional loads are expected.
- Anchor. Also used on direct sections of overhead lines, but have one feature. Using anchor supports , transition zones are formed through natural barriers, engineering structures and other structures.
- End. These pillars begin and end overhead lines.
- A special reinforced concrete support is also common, 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
Reinforced concrete pylons are the optimal solution to provide support for overhead power lines. Metal and wood counterparts are also used for this purpose, but have a number of serious limitations. However, the reinforced concrete supports also have load sharing on the networks with which they can work. In particular, there are supports for lines from 10 to 1150 kV. Designs with different parameters are presented in such a wide range. The higher the voltage, the greater the mass and length of the beam has a reinforced concrete support, included in the network. It would seem that if the lines are at approximately equal distance from the ground and the physical load on the structure is the same, then what causes the need to change the characteristics of the support? In fact, this is fully justified by the technological requirements that prescribe different standards for the distances from the line to the support and the surface of the earth, depending on the voltage.
Mounting technology
Work activities begin only after completion of site preparation and delivery of components for installation. Next, 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 carried out by special machines: installation cranes or boom equipment. Pulling up the racks can also be carried out by the tractor. A pit is also being prepared, the diameter of which can exceed the same indicator at the rack by no more than 25%.
If you plan to install gantry or two-post supports, then the installation is performed in sequence: first one, and then the second rack. The following is the installation of traverses, endings of the inter-postal cruciate ligaments and fixing their lower ends. When the lifting and installation of supports by special equipment is completed, the structures are temporarily unfastened with special guy wires, after which the crossbars are installed. It is possible to start the final stage in the installation of supports with backfill after the alignment of the structure has been carried out.