When laying the foundations for buildings on weak and moving soils, special elements are used - composite driven piles. Due to this, structures acquire the necessary strength on unstable soils. Pile elements are made of wood, concrete, iron, but reinforced concrete is most in demand.
Design Benefits
The advantages of pile products include the following indicators:
- Durability.
- High strength.
- No defects.
- The ability to install to carry out land work in a minimal amount.
But most importantly, reinforced concrete structures are not afraid of aggressive chemicals and corrosion, which is very important when using products for installation on lands where groundwater rises close to the surface.
Scope of application
Consisting of two or more sections, reinforced concrete structures can have a maximum length of about 36 m. This indicator is very important, as the coppers for the installation of whole products have limited capabilities and can not perform their installation. The fact is that piles of any materials must go deep into the ground until they abut in high-density soils. Otherwise, their use cannot provide the required stability, and then during operation the building will sag.
Note: unstable soils are peatlands and peaty soils, silty and clayey lands. It is impossible to build buildings on them without using pile products.
Compound piles are used not only for the construction of new buildings, but also for the reconstruction of previously used ones. To do this, at an object where there is limited space and it is impossible to use integral analogues, they strengthen the base of the building with additional supports. Usually use structures consisting of several parts, each of which has a minimum length.
Reinforced concrete products from several sections are also used where long structures cannot be delivered due to inappropriate road or transport conditions. They use products of this type and construction companies that do not have a pile driver designed for driving structures with a length of 12 m or more.
Design features
According to GOST, composite piles are two joined elements - upper and lower. Products are available in the following section:
- With a length of 14-24 m - 30 x 30 cm.
- With a length of 14-28 m - 40 x 40 and 30 x 30 cm.
The upper and lower parts of the products can have the same or different lengths. For example, in products with a cross section of 0.3 x 0.3 m, the lower part can be from 7 to 12 m. The increment is 1 meter. Piles with a diameter of 0.4 x 0.4 and 0.3 x 0.3 m have a minimum length of the lower part of 8 m and a maximum of 14. The length of the upper sections is from 5 to 12 and from 6 to 14 meters, respectively.
An important detail: on the lower section, which plunges into the soil, there is a point. It is necessary to improve the efficiency of immersion in the soil of the element when driving or indenting.
Methods of connecting individual elements
The individual elements of the composite piles are joined in one of the following ways:
- Using the weld joint of the embedded glass.
- A sheet steel plate that compresses the barrel is used, which is connected by a weld.
- Compression parts are bolted together.
- Apply a sealing tape, conductor or rest on the key protrusions.
- Use a hinged lock.
- Pin connection.
- The use of construction high-strength glue, with the help of which the reinforcement protruding in the landing hole with the upper section is fixed.
The most reliable of the listed methods is considered to be a pin connection and the use of a welded glass - they are most resistant to deformation.
Product labeling
According to the technological requirements given in the document GOST No. 19804, the following types of composite piles of the series 1.011.1-10 are produced:
- Hollow with a circular cross section.
- Solid square construction.
- Pile sheaths.
All types of designs are produced according to the standards specified in separate documents:
- Hollow products and piles-shells (the skeleton is made of non-tensile reinforcement) are produced according to the requirements specified in GOST No. 19804.6-83.
- Piles-shells, the skeleton for which is made of tensile and non-tensile reinforcement - GOST No. 19804.91. Products are allowed for installation in any construction industry. An exception is the hydraulic industry.
- Products with a square cross section are available with a frame made of non-tensile and tensile reinforcement in accordance with GOST No. 19804-2012.
Each composite pile also has a unified marking. Type of marking - 260.30.. The designation is deciphered as follows:
- SP - reinforced concrete hollow pile having a square section. If the designation C is present, this is a continuous product, if CO is a pile casing, SK is a hollow circular construction.
- 260 - an indicator of the total length of all parts of the product in dm.
- 30 - diameter of the cross section of the barrel in centimeters.
- Connection type designation. CB - welded joint.
In addition to the above notations, there is an abbreviation in the marking. She points to part of the design. For example: NS - lower, AC - upper part, and A3 - its class.
Immersion technology
Structures are immersed in the ground using a hydraulic or diesel hammer. It is strictly forbidden to use vibration absorbers due to the fact that the welded joints of the frame can be deformed due to vibration. To facilitate the penetration of high density soil, it is recommended to use the leader drilling method . Using this method will help reduce soil resistance. This is very important if you have to hammer composite reinforced concrete piles to a depth of 20 meters or more. In order to rationally implement the immersion of structures, excavator equipment with a crane boom is additionally used. This will significantly speed up the installation, as the copier does not move the product at the construction site.