If the foundation became unusable during operation - it began to crumble and cracks appeared on it, then the main cause of such defects may be non-compliance with the rules of technology during pouring. It is possible that the foundation was built using low-quality concrete. In some cases, materials are affected by negative factors, and waterproofing is poor quality. In any case, over time, the foundation may need to be strengthened.
If the house is built on soft ground, then the foundation eventually loses its ability to withstand the loads that turn out to be a structure. In this case, it may also be necessary to strengthen the structure. These works allow to extend the life of the entire building. Reinforcing can be done in several ways depending on which part of the base needs to be reinforced.
Work on grillage
Today, there are several ways to strengthen the pile foundation grillage, which depend on the causes and typedamage. The process of restoring parts of an unburied and buried foundation is no different. Strengthening a pile foundation with a grillage provides for the repair of defects in the outer concrete layer. In this case, a cement mortar is used, which is applied to the surface of the damaged area under pressure. This approach eliminates cracks, corrosion and the effects of weathering.
The work is called shotcrete. Before they start, the surface of the grillage must be treated with a metal brush, and then blown with a compressor and rinsed with a jet of water, which is supplied under pressure. For reinforcement, a metal mesh should be used, the cells of which have a size ranging from 5 to 10 mm. The basis should be a wire with a diameter of 5 mm.
Using a perforator, holes are drilled on the damaged side in the next step. It is necessary to go deep by 25 cm, and the distance between the holes can be from 50 to 80 cm. Anchors are inserted inside, to which a metal mesh is fixed. The spraying is carried out under pressure within 0.6 MPa, while the layer thickness can reach 40 mm.
The work is carried out in such a way that centimeter strips are obtained as a result. You have to work from top to bottom. After the first layer has set, you can start applying the second and third. When considering how to strengthen a pile-screw foundation, you should pay attention to another technology that helps to eliminate larger-scale damage to the grillage. To do this, it is necessary to drill holes in the damaged area, placing them at an angle to the piles. These holes are called boreholes, and they must be positioned in such a way as to cover the damaged area as much as possible.
The diameter of the holes can be from 40 to 80 cm. The holes will have a length within 0.4 of the thickness of the foundation. This is true if drilling is carried out on both sides. Whereas when making holes on one side, the length of the holes should be 0.75 of the thickness of the base.
The number of holes is not limited and will depend on the size of the repaired area. It is important to position the boreholes between the rebars. After the holes are completed, they should be washed with a stream of water and poured with concrete mortar, which is prepared in a ratio of 1 to 10. If the destruction of the grillage is more impressive, then a clip is built on the damaged area. Strengthening with its help is carried out at the entire height of the grillage and along its entire length.
Strengthening trunks
Quite often reinforcement is used to reconstruct the base. How to strengthen the pile foundation, you can find out if you read the article below. The most convenient way is to strengthen the base with a high grillage, because the trunks are available for repair. If there are cracks on the pile pillars, a reinforced concrete casing with a thickness of 10 cm will have to be installed. The penetration into the ground is carried out by 1 m or more.
Strengthening of piles can be done by drilling the trunk with holessmall diameter. On each side of the support, 8 cm holes are drilled for this. One should fall on each side of the support. Cement mortar is poured into the wells, which forms a concrete jacket around the support and enhances the strength of the soil.
Strengthening the pile foundation can be carried out in the area of the columns. To do this, a reinforced concrete or metal pile is driven to the support shaft. Metal conical pipes are pressed in during the repair of columns in existing production shops and during repair work in basements.
Steel pipes are used for sheathing the piles, the length of which can vary from 2 to 3 m. In case of weak soil, the elements are squeezed out with a jack until a solid foundation is reached. In the process of deepening one pipe, a second one should be welded onto it until the design mark can be reached. After the pipe is submerged, it is poured with concrete.
Additional ways to strengthen supports
Strengthening the pile foundation can be carried out by placing additional supports next to the grillage. Such piles should be located on both sides of the base, and a beam is installed on their heads. To strengthen the structure in this way, the beam must be installed under the foundation itself or the frame of the building.
In order for the piles not to sag, the head is crimped with jacks on both sides. If a gap has formed between the head of the column and the beam, then metalwedges. This place at the next stage must be strengthened with reinforcement and filled with concrete.
Reinforcement of piles with bored supports
Strengthening the pile foundation can be carried out with the help of bored supports. Two wells are drilled near the columns, and then reinforcement and filling of the space with concrete are carried out. It is not worth reinforcing all the pillars in a row in this way, work should be carried out through one or two supports.
There are cases when the entire base is strengthened. Such work is relevant in case of significant destruction. The main reason for such consequences may be an increase in the bearing load on the base and weakening of the soil.
Strengthening the foundation by soil compaction
When the soil under the supports loses its bearing capacity, it must be strengthened. To do this, there are several methods, the simplest is the replacement of sagging soil. Strengthening can also be carried out by digging supports to the lower conical part. In this case, the soil can be compacted by pouring with a cement mixture or silicate resin.
Strengthening the pile foundation, installed on clay soil, is carried out by injecting carbamide resin into the soil around the supports. Strengthening the soil is carried out through submerged injectors, with the help of which resin is injected from two sides in turn by going from bottom to top.
Strengthening the pile-screw foundation
Strengthening a pile-screw foundation may involve the use of pipesor steel angle. The size of the first product should be 30 x 60 mm, as for the corner, its shelf should be 50 mm. These elements are installed around the perimeter; internal supports should not be excluded. As a result, you should get a structure in which all the piles are connected. This type of reinforcement of a pile-screw foundation is used when the supports are located high above the ground (more than 70 cm).
Work Methodology
Blanking with a corner or corrugated pipe enhances spatial rigidity. The elements should be placed diagonally between two supports with a small lifting height on the inside of the base, so as not to interfere with the installation of panels decorating piles. If the upper part of the supports protrudes more, then welding is carried out crosswise, and a steel plate with dimensions equal to 200 x 200 mm is installed in the central part of the intersection of the elements.
An alternative option for strengthening the pile foundation
Strengthening the pile foundation during the reconstruction of the building may also include the use of a channel, the dimensions of which are 160 or 200 mm. This method is used when the building is erected on peat soil. The width of the channel will depend on the thickness of the walls of the house. This element is welded to the top of the supports and replaces the head. The welding of all piles creates a rigid and durable structure, which is similar in principle to a strip foundation.
Using a channel
If you reinforce the pile foundation during the reconstruction of a building using a channel, then this increases the cost of the structure by 50% or more. The final cost of the foundation will be lower than the price of a strip foundation, while the speed of construction of the first foundation has no equal. For example, if you are planning to build a house 6 x 6 m, then it will require 12 supports, their average cost will be 43,200 rubles. Another 25,500 rubles must be added to the channel, the total amount is 68,700 rubles, while the delivery of the material is not taken into account.
Strengthening the pile foundation of an existing private house can be done by jacking the building to a minimum height. The use of a channel allows you to solve another problem, which is expressed in the sagging of the strapping crown. This eliminates the trampoline effect when the distance between the supports is too large.
Additional reinforcement by ground reinforcement
The soil around the trunks under their base can be strengthened in the following ways:
- resin;
- cementing;
- silicification;
- fired.
Specific technology is selected based on the type of soil. The method of strengthening the pile foundation, expressed in silicification, is relevant for forest-like and sandy soils, while resinization can be used for fine sands. For clay soil and gravelly soil, grouting is better suited. These methods are implemented using the same technology,however, the techniques differ in the composition of the solution injected into the soil.
Conclusion
During operation, the foundation may be subjected to aggressive impact. This includes groundwater and precipitation. In order to exclude corrosion, it is recommended to protect the piles with special paints, but sometimes this is not enough. Over time, it is necessary to strengthen the base, which is suitable for both new construction and major repairs of old buildings.
Such work may also be needed when the foundation shrinks, the cause of which is all the same groundwater, temperature changes and errors in the device of the primary foundation. In order to save the building, it is necessary to strengthen the foundation. The technology for implementing this idea has long been worked out. The house needs to be raised and appropriate work carried out. However, the likelihood of such work must be foreseen at the design stage of the building, then the costs will not be so impressive.
