- 1 The foundation on screw piles are pluses and minuses
- 1.1 House on stilts - fantasy or reality?
- 1.2 Advantages and disadvantages of pile construction
- 1.3 Types of screw piles
The foundation on screw piles are pluses and minuses
To any building, regardless of the destination, it was reliable and durable, it is being built on a solid basis. Today, the building is widely used many different types of foundations, and one of them is a pile-screw. Such a variant base structure under construction causes the greatest number of questions. Therefore, this publication will devote the issue: the foundation on screw piles are pluses and minuses, an overview of its structure, the possibility and expediency of the construction. Such aspects are interested in very many owners of land that occupied the first "estimates" of the future construction of his house.
The foundation on screw piles are pluses and minuses
Before stating the advantages and disadvantages of such a structure should probably consider some of the nuances, which directly affect the strength and durability of the pile foundation.
House on stilts - fantasy or reality?
Can I use a pile foundation for the construction of a residential home? I must say that there are some builders who strongly advised to do so, preferring the tape, columnar or of plate based on a house. These experts believe that the piles are more suitable for outbuildings or lung lodges.
However, it should be recalled that there are entire city whose houses are arranged solely on stilts, and they are worth more than a decade. Practice the use of these foundations has shown that they may even serve as a reliable basis for massive houses.
Of course, it is unlikely to be reasonable in our climate pile two-storey stone house on pile foundation, although it probably is not absolutely impossible. Yet in private construction is usually opt for wooden or frame buildings with a roof covered with roofing material easy.
Often, due to rugged terrain, or other terrain features, pile foundation is the only acceptable solution
In some cases, the pile bases are in general the only opportunity to build on the site of the house, for example, if the construction is planned for the site or permanently poured rugged spring flood areas.
In favor of such a design is the fact that such variants of foundations used in construction since ancient times, only earlier as piles used specially prepared for this purpose logs. At first, just piles hammered into the ground, and only at the beginning of the XIX century was invented screw installation method.
Screw support initially used for arranging moorings, but then their scope began to expand. For example, it is screw piles were used as the foundation in the construction of the beacon, which is erected in the UK on unstable ground Thames.
The first lighthouse built on screw piles - "Meplin Sands»
Since the beginning of the XX century building on pile foundations acquired a "second wind". This facilitated the emergence of new techniques for accurately and deep driving piles, which considerably speeds up the work of the construction of bases for further erecting of buildings. In 50-ies began active use of mechanical equipment for the screw-driving, which gave further impetus to the construction industry such as industrial and individual.
Very broadly, this method everything foundations began to be applied in military construction, as by comprehensive studies have shown that such structures are reliable, durable and suitable for use in permafrost, watered and heaving soils - in a word, the restrictions on their use is practically non-existent.
The first national scientific development, officially adopted as the standard for construction work began in 1955, prepared on the basis of long-term experiments work - TUVS-55 ( "Technical Guidelines for the design and installation of foundations, bridge piers on screw piles"). Many of its provisions and spilled over into modern building codes.
Advantages and disadvantages of pile construction
The technology of construction of houses on screw piles are used today around the world and has a lot of positives.
Numerous advantages of screw-pile foundations cause the growing popularity of such structures among private developers
For obvious advantages screw pile foundations may include the following:
- The design can be built on the grounds of almost any type of climate in different regions, including marshland and in regions with permafrost.
- On the improvement of this type of foundation does not have any significant effect of the level of the location of groundwater.
- Screw the foundation is perfect for building a house in the complex terrain.
- Screw piles can be installed at any time of the year, as the weather conditions do not affect the quality and durability of the design created - at a depth of immersion of screw terminals soil temperature is always stable.
Take on concreting the tape or slab foundation in the winter - a risky occupation. But for the foundation on screw piles such restrictions do not exist
- Screw-pile foundations are not subject to frost heaving during freezing of the soil.
- Installation works are carried out in the shortest time. For example, if you are lucky all the circumstances - good permeability of soil, well-coordinated team of craftsmen, etc., pile field under a medium-sized house can be prepared in just a day, especially if you are using a special technique. When this screw piles can be used for their binding and walling immediately after installation, i.e. they do not require time for curing, maturation, curing, as any reinforced concrete structures. None of the other types of foundation is not even close to the speed of erection of such indicators.
Using a special technique allows the creation of extremely accelerate pile field completely ready for further construction
- Piles can be screwed on the site allocated for construction of the house and on their own, with the involvement of several assistants, that is, without the use of special equipment. This factor is particularly important in the case in the construction area is not possible to order these services, or the owner of the future house simply on a tight budget.
There is no possibility to order the use of special construction equipment? - it does not matter, you can cope on its own.
- For the arrangement of the screw pile-foundation will not have to dig a pit and equip the formwork, which means that the area will not be selected debris soil, which will also have to get rid of, exporting it outside the area, and that also requires additional material cost. In addition, under the foundation will not have to carry out work on the construction site leveling.
- Screw pile-foundation does not pull the capillary moisture from the soil, so the walls and floors of the house will be dry.
- There is ample opportunity to carry out the design and installation of various utilities simultaneously with the installation of foundation elements or after its construction.
- With proper selection of high-quality and reliable piling their installation provides the basis durability, which is considered by many decades.
The space between the ground and strapping can be closed on the perimeter and warm, and sometimes - even find it useful application
- Well insulated foundation around the perimeter, you can get warm underground, so that the floor of the house will also be warm, so it does not become vyholazhivatsya from the ground. In addition, in some cases it is possible to build a house of some sort of "economic levels", without large-scale excavation.
- foundation design of screwed piles will cost up to 30 ÷ 40% cheaper than the concrete base. Given the fact that the construction of the foundation is always refers to the category of the most costly stages of construction of the house, the savings can be quite impressive.
All of the above listed advantages of the foundation on screw piles are only those structures that are built in compliance with all standards developed, with quality materials and with the obligatory account of all the characteristics of the terrain.
But in cases of deviation from the technology, using home-made piles and other violations of the construction process can occur and escalate typical pile-foundation screw disadvantages.
So, to "cons"Screw-pile foundation include the following points to be taken into account in the preparation of the project and during construction:
- Beyond the calculations and erection works lack this foundation can be called increased complexity or even impossibility of its construction on highly stony and rocky soils.
Under the influence of load strapping frame bent pile foundation - most likely the result of an incorrect determination of characteristics of the ground or incorrectly selected and set screw piles
- Excessive load on the screw piles can lead to a weakening of the foundation of all possible carrier and as a result - a strapping belt deformation and destruction of the walls.
- It is imperative to effective improvement of drainage systems installed piles, which leads to additional costs. However, storm sewer and drainage is recommended for installation around the foundations of any type.
- No way to completely eliminate the corrosion impact on the material piles. Qualitative products certainly obtained in the production process necessary protection - the zinc coating layer and the polymeric materials. However, sometimes improved chemical aggressiveness of soil does the "dirty work." Not recommended the creation of screw-pile foundations in the immediate vicinity of the electrified railways, cell phone towers, developed mines and quarries, large substations and high-voltage power lines. At such sites, a high probability of occurrence of stray ground currents which activate rapidly metal corrosion processes. And absolutely should be avoided the use of the foundation piles to create a home ground circuit.
Unfortunately, completely eliminate the effects of corrosion on the screw pile - while it is impossible
- Carrying capabilities of the proposed sale of screw piles - are not unlimited. However, in low-rise private construction it has a very indirect relationship - heavy loads that exceed the characteristics of well-chosen piles are not expected.
- No matter how hard you try, but go full basement basement with pile foundation under private construction will not be able to receive.
- During the construction of extensions to the house may be some difficulties with screwing piles at points close to the walls of the old building. However, it is usually solved by using a special technique.
- Not the shortcomings, but rather a kind of costs can be attributed to the fact that the construction of pile-foundation screw requires from the owners, customers continuous monitoring of the work of the guest team. Unfortunately, we must note that in this field strive for masteries many "pseudo-experts", and even frankly "sharomyzhnikov", trying one way or another benefit from violations pile installation technology. Thus, to ensure reliable protection against corrosion, the pile cavity technology is required to fill up to the top concrete. There are cases when guest workers ignore this step immediately after screwing navarivaya headroom.
Be sure to make sure that the cavity was filled with piles of concrete solutions for the most headroom.
There are instances when "shabashniks" brigade, working without supervision by the customer, not the pile is screwed to the full design depth - and check it out after the cutting of pipes, Weld end walls and strapping - is virtually impossible. And such a breach always entail a quick deformation creates a basis with all its consequences.
And, without a doubt, it is necessary to drive from his construction site workers, if observed that adjusting the height of the pile, they rotate them in the opposite direction of screwing. Such support can be directly considered as the rejected, since the estimated carrying capacity it already possess can not.
Conclusion - to invite a team of only organization with an impeccable reputation for quality of works, or not lose any phase of construction of the field of view, to control every action, provisions on technology. Well, if you have the desire and self-confidence - to carry out the installation of the piles themselves.
As you can see, the disadvantages are also quite serious. And in order to avoid or reduce to a minimum possible, piles must be chosen correctly, and the construction of the foundation run on the basis of calculations made, including assessment of future loads and determination of the bearing capacity of the supports.
Types of screw piles
Screw piles are divided into several types, which have their own features, consisting of a plurality of constructive and technological characteristics. Each of the types of products intended for use in different conditions that depend on the soil characteristics and the expected load on the foundation. Moreover, it is necessary to take into account the factor that is sometimes different types of piles are used in the construction of even a single object, as in different areas of the structure may provide a non-uniform load on the foundation. The use of different types of piles provide stock-based strength and increase the service life of the building.
Screw piles are divided according to the following parameters: the main purpose, the diameter of the pipe, the size and number of the blades, the type of tips on the stress (load capacity) on the stamp and thickness of steel, but also on the type anticorrosion coating.
These parameters should be considered in more detail in order to know which products are suitable for the construction of houses on the site-specific soil types.
Variations on the application of piles
The illustration below shows the four basic types that are very different even visually.
External differences of screw piles visible to the naked eye
a - shirokolopastnye piles one blade tip Placing on the bottom of the tube. The most common type in private construction, which allows to build foundations on most types of soil. Typically used for light farm buildings and single-storey houses made of wood panels or framework. However, the correct choice of diameter of the blades and the number of piles on these foundations to build houses and blocks of gas silicate.
b - piles with high bearing capacity, resistance to shrinkage and pull out resistance. Characteristic difference - the presence of two blades spaced along the height of the pile. Suitable for foundations of two-storey houses. The independent private construction are used infrequently, as by hand, without the use of specialized equipment, screw in a pile in the ground - is virtually impossible.
at - uzkolopastnye piles with a pronounced conical "screw" - used to build foundations on rocky soils.
g - Special piles intended to create foundations in permafrost conditions. Require the use of special screwing technology, so in practice the self-construction - is not used.
Of all these types, as can be seen, most often used for self-construction of the first, so in the sequel to the more attention will be paid to him
Sizes of screw piles for the foundation
Depending on the composition of the soil and structural loads, it is necessary to select the correct diameter of the pile shaft, which may vary from 57 to 133 mm. Together with the tube diameter and the diameter of the blades is changed, and it is higher than - the greater bearing load capacity.
The table below shows the main shirokolopastnyh various piles welded tip (they normally perform under the designation SAF - pile spiral welded)
|SAF-57. Pipe diameter - 57 mm, the blades - 150 mm. |
These products do not possess outstanding load capacity - load capacity to support only up to 800 kg.
And this causes a rather narrow scope of use - lightweight enclosure without becoming an obstacle the wind, that is, from the mesh-netting or rarely located picket.
Typically, for such purposes acquired by a 4-meter high piles, based on the two-meter dive in the ground and two meters high - on the fence height.
|1300 rub. + 100 rubles. |
Headroom SMF-57/200/200 - 260 rubles.
|SHS-76. Pipe diameter - 76 mm, the blades - 200 mm. |
The bearing capacity of the pile - up to 3000 kg.
Typical applications - windproof construction fences, i.e. having sail (e.g., often located wooden or metal picket flat slate, metal sheeting, polycarbonate and other similar materials).
Most often used length of 4000 mm, for the same reason as was indicated above.
|1450 rubles. + 100 rubles. |
Headroom SMF-76/200/200 - 300 rubles / pcs..
|SHS-89. Pipe diameter - 89 mm, the blades - 250 mm. |
The bearing capacity, depending on the soil, can reach up to 4 ÷ 5 tons.
The specifics of the application - the construction of foundations for supporting outbuildings, lightweight frame garages, garden pavilions and other facilities of a similar type and purpose.
Often used in the annexe to the dwelling house veranda.
Can also be used to create additional support required, e.g., when installing the heavy boiler equipment or use in the building masonry fireplace or furnace.
|1500 rubles. + 150 rubles. |
Headroom SMF-89/200/200 - 300 rubles / pcs..
|SHS-108. Pipe diameter - 108 mm, blade - 300 mm. |
The bearing capacity is estimated to be 5 - 9 tons.
Widely used in the construction of residential town houses not heavy construction - frame or timber for log house.
Proven effective, including on difficult terrain - wetlands or peat.
|1700 rubles. + 250 rubles. |
Headroom OBC-108/200/200 - 300 rubles / pcs..
|SHS-133. Pipe diameter - 133 mm, blade - 350 mm. |
The strongest support from the number used in individual housing. Inherent potential bearing capacity reaches 14 tons.
Such supports are used to build pile field for the construction of houses made sufficiently heavy wall materials - silicate blocks or brickwork.
With appropriate bearing capacity of soil often used reinforced concrete monolithic piles rail grillage and pouring concrete floor the ground floor.
|2250 rubles. + 350 rubles. |
Headroom OBC-133/300/300 - 350 rubles / pcs.
Number of blades
Screw piles may have one blade, as shown in the above table, or more. Accordingly, they are called single- and multi-blade.
Single blade piles - the most common in the field of private construction
Single blade piles are used for decorating the bases in areas with soils that have a high load capacity. However, using this type of product, especially with welded lugs, you have to be prepared for the fact that they can go to the "failure" to reach the critical load. In this case, the support loses its load-bearing capacity, which has a negative impact on the integrity of the foundation of the binding.
Multiblade products are used for decorating the bases on a variety of grounds, including the weak. They have a high load capacity and resistance to high loads of different types of &# 8212; dents, horizontal or pull out.
The bearing capacity of pile-blade - disproportionately higher but screw of hand, without the use of special equipment - is unlikely to succeed
The larger the number of blades on the pile bore enables the use of a product with a smaller diameter pipe having a sufficient wall thickness. The high efficiency of these piles is achieved an optimal arrangement of the blades on their trunk. The distance between the blades and the pitch angle of inclination calculated individually, taking into account the location of the soil layers and its composition at the particular construction site. Working with such supports, of course, it requires a skilled approach.
Tips screw piles are divided into welded and cast.
Products with cast lugs are definitely more reliable, since practically subject to deformation during driving through the ground, in contrast to a welded type. Piles alloy tips can be used for installation in permafrost, very dense soils, as well as having a solid natural or manmade inclusions. This type of tip is not deformed, even bumping into an obstacle, and is able to destroy it.
Now, to determine the number of piles for the foundation, you need to calculate what kind of load it is supposed to.
Evaluation of loads falling on the pile-foundation screw
In this option includes the weight of all building materials used for construction of the house, the weight of the furniture and other household equipment, external loads, of which the first place is always out of snow, as well as dynamic performance.
A precise calculation of the total load - this is a task of high complexity, which afford only to specialists. But some, albeit with a sufficient degree of accuracy, it can be done on their own, if the future home have a clear idea of its owners and have the initial outlines of his project.
Presumably, the owners already are, that will exhibit their future structure, so there is some opportunity to the approximate calculation of the load on the foundation
To simplify this task to the reader, the following is a calculator that allows to carry out the necessary calculations taking into account the characteristics of the future house.
Several explanations for its use:
- To estimate the mass of the walls of their area is requested and the material from which they are erected. Subject to the two options, for example, external walls and internal partitions, different material and (or) thick.
- A similar approach is applied to the slab. Here - as two variants, for example, for the floor of the first floor and attic floor. At the same time calculation program will include also the operating load on the ceiling.
- You will need to specify the area of the roof and the type of roofing material. Each type of roofing is characterized by its system of trusses and sheathing - all of these values are automatically taken into account in the calculation.
- To add a snow load, it is necessary for the map chart to identify the area of residence and indicate the number of the zone in the appropriate field calculator. In addition, for correct accounting snow load must specify the angle of slope of the roof of the future rays.
Map to determine the number of the zone on the level of snow load
- Piles foundation necessarily strapped before the erection of walls. If it uses a wooden beam, it can be included in the area of the wall - a large error will not. But it is often used for this purpose heavy-metal profile or even reinforced concrete raft foundation. But in this case, it is wise to specify binding parameters as well as the additional burden of it can be considerable. (If you use a timber, just in the "length of the raft foundation" keep the default value of zero).
All other calculations calculator will hold their own. The final value of the total load on the foundation will be displayed in kilograms and tons.
Calculator assess the total load provided by building on pile foundation
Enter the requested value and press "Calculate the total load falls on a pile foundation"house wall
The area of the walls gives the total, if you wish - you can minus the window and door openings.
(. Available options for the introduction of two, eg for bearing external walls and internal If option is not used, leave the area default - 0) Wall type №1wall material- brickwork in a half-brick (120 mm)- bricklaying 1 bricks (250mm)- bricklaying 1.5 of bricks (380 mm)- the walls of silicate D600 mark blocks, thickness 300 mm- log house, diameter 240 mm- the walls of the timber, thickness 150 mm- frame walls with warming, thickness 150 mm- the walls of the sandwich panels 150 mm, with mineral wool insulation- the walls of the sandwich panels 150 mm thick with insulation from expanded polystyrene or polyurethane foamWall area, m² Wall type №2wall material- brickwork in a half-brick (120 mm)- the walls of silicate D600 mark blocks, thickness 300 mm- log house, diameter 240 mm- the walls of the timber, thickness 150 mm- frame walls with warming, thickness 150 mm- frame plasterboard partitions- partitions of sandwich panels of thickness of 50-80 mm, with mineral wool insulation- septum of the sandwich panels 50 to 80 mm thick, with insulation from expanded polystyrene or polyurethane foamWall area, m²SLABS
If there is an opening in the ceiling, for example, for interfloor ladder, it should be excluded from the total area
(. Available options for the introduction of two, eg, for interstorey and attic floor If an option is not used, leave the default area - 0) Overlap, type №1 (interfloor)type of overlapping- overlapping interfloor socle or the wooden beams with a heater density up to 200 kg / m³- hollow-core floor slab- monolithic floor slabThe area of overlap m² Overlap, type №2 (attic)type of overlapping- overlapping the wooden beams attic insulation with a density of 200 kg / m³- hollow-core floor slab- monolithic floor slabThe area of overlap m²And the roof truss system
When choosing the type of roof will be automatically taken into account and the average weight of the roof system with a crate.
Simultaneously, the weight of the roof will be added to the approximate value of snow load, depending on the region and the construction of ramps slopeThe total roof area, m²type of roof- steel sheet, profiled, metal- soft polymer-bitumen roofing in two layers- abesto-cement roofing- TilesEnter the zone, according to a schematic map IIIIIIIVVVIVIIThe angle of slope of the roof skate - up to 25 degrees - from 26 to 59 Celsius degree - 60 degrees and steeperGRILLAGE
If strapping of piles used wooden beams, it can be simply taken into account in the area of the wall - a large error will not.
Grillage out of metal or concrete is best to take into account furtherThe length of the raft foundation (including the external perimeter and internal jumpers), metersMaterial grillage: - channel №30 - I beam №20 - monolithic reinforced concrete belt 300h200 mm
Number of screw piles
Thus, the results of both calculations we have two values - bearing capacity of single pile (with operating margin) and the total load to be transferred away from the building foundation. It is obvious that a simple division of the load on the load-bearing capacity show the required number of piles. For example, the first calculator appreciated permissible load on the pile of SHS-108, considering reliability in the correction factor 4.3 tons. A second calculator showed total load value of the planned erection of the building - 63.5 tons.
Simple arithmetic gives the desired result:
63.5 / 4.3 = 14.77
The value is always rounded up in a big way, that is, we get 15 piles.
I must say that this number is minimal and may well prove to be not yet final, as further into its own regulations to enter the balance of the pile supports.
The alignment of piles subject to certain rules, so that they sometimes estimated amount may increase
- For the frame, log and lumber piles houses are set in increments of no more than 3000 mm.
- For houses built from foam concrete, cinder and concrete blocks, supports the installation step is not more than 2000 mm.
- When erecting fences made of light construction materials distance may be 3000 ÷ 3500 mm. During the construction of fences of corrugated board or wood, a step should be 2500 ÷ 3000 mm, depending on the wind load.
When a particular installation of screw piles on the building plan, consider the following rules:
- Compulsory piles are installed at the corners of the building, as well as the points of intersection or junction bearing walls.
- Under all internal and external capital pile walls are installed with the same pitch, which is selected depending on the material of the walls and features of the building.
- For extensions, terraces, adjacent to the house sheds and other similar structures lungs pile field is always calculated separately and is not attached to the foundation of the house. By the way, for such extensions is quite possible to use a smaller diameter support - will be a significant savings.
- Another approach - to heavyweight objects located inside the house (oven, boiler and the like). Usually, at such points it requires reinforcement at least two additional piles, or the creation of a separate mini-base, non-basic and planned on the basis of separate behavior calculations.
So do not rule out the possibility, when the need to install additional supports svreh settlement amount, but that the overall load-bearing capacity of the foundation - will benefit. But to underestimate the amount, even if the alignment on the plane, it seems excessive - no way.
In conclusion, it is necessary to stress once again that the implementation of final payments, as well as the construction of pile-foundation screw, especially for the further construction of high-grade apartment building, it is advisable to entrust the proven and competent in such matters an organization that can guarantee the quality of their work. You should never handle unfamiliar to construction crews, even to those who position themselves super pros. Savings in this case will turn out highly questionable, and it is possible that after some time will manifest itself already an urgent need to call the real experts to correct mistakes. But then you have to lay out a very decent amount, since it is very often necessary to correct not only the "shoals" of the foundation, but also caused strain on the building.
"A good thesis" in favor of what has been said in the last paragraph can serve as proposed below video clip:
Video: The disadvantages of screw-pile foundations, which could not be