Each foundation of the house must be built and designed very carefully. This fully applies to the option with screw piles. The apparent simplicity of their installation actually hides many subtleties and nuances that simply cannot be ignored without the risk of encountering unpleasant consequences.
Pile type supports can be made with your own hands. But we must admit that such work is not easy and requires a lot of experience, a thorough study of the specifics of the problem. In order for the fastening part to easily enter the soil, it is necessary to carefully calculate the inclination of the spiral blade, its fastening to the cone of the tip. The situation is aggravated by the complete absence of state standards and the lack of reference products. You can’t buy or get one pile and make others on its model - even leading manufacturers often sell low-quality goods.
The typical composition of the structure is as follows:
- case - a pipe with a diameter of 7.6–35 cm with a wall thickness of 0.4 cm;
- lugs obtained by welding or casting peaks, the length of which is 2 own diameters, or cones;
- blades - spirals with one or two runs, and, as an option, a pair of screws 40–70 cm from each other;
- the cap is used in combination with wood grillages.
A typical head is made as a plate with special holes and a number of stiffeners. This plate is welded to a coil made of a pipe with an inner diameter slightly larger than the outer shell of the pile. Attention: for self-production of screw supports, it is worth using drawings distributed by any manufacturer. Then the risk of error with the dimensions of the blades is eliminated, the number of welds is reduced. The fewer such compounds, the smaller the weak areas around them.
According to professionals, it is worth choosing pipes produced according to GOST 8732 and 19281 or according to TU St20 and 09G2S replacing them. Such materials are distinguished by a light cut and simple bending of the petals. It is most convenient to form a tip from them. For the most part, home-made screw piles are made from 2 to 3 m long, if it is necessary to reach the bearing soil layers at a considerable depth, after screwing in, add a pipe length of 150-200 cm. Speaking of accessories, we can not mention the tips.
They are made of three different types, the approach concerns not only the nuances of technology, but also the magnitude of the part used. So, through dense soil, peaks of welded design or those obtained from a pipe “body” are best passed. But piercing the sand massif, peat deposits and sandy loam will be easier with cross-shaped tips. How long the foundation lasts does not depend on the type of peaks. But obvious differences are found when comparing the torque on the lever.
The use of a tubular body implies building it up by two diameters , since one of the ends of the workpiece becomes the tip of the future pile. Start by slicing a template. According to this template, the edge of the workpiece is marked into sectors. With a cut of the pipe, the lines drawn in chalk become a guideline for the formation of petals with cloves. Further, such petals are bent in the form of a strict cone, with the vertex being precisely aligned with the axis of the pipe; Having finished this manipulation, fragments are welded using the double seam method.
If the diameter of the pipe is 10.8–20 cm, five petals are prepared. With its smaller size (from 7.6 to 8.9 cm), four fragments are enough.
In addition to the welding machine, normal operation requires the use of tools such as:
- apparatus for plasma cutting;
- gas cutter;
- grinder with equipment for slots in the metal.
These cutting devices are interchangeable, but it is recommended that you always have at least two options at hand, and preferably all three. Then in case of any malfunction or difficulty there will be no hitch in the work. Then, using the resulting peaks, it will be possible to quickly immerse them at the required depth, pushing small and crushing large stones. If you have to build small architectural forms and light buildings, you can use welded tips, obtained in a similar way. Recommendation: the joining of the blades best occurs with peaks from the pipe lobes, and not with those obtained from sheet steel.
There is another approach that uses a slightly different scheme. Details are cut in the form of a triangle, complemented by stiffeners and a round plate that plugs the pipe from one end. When assembling, a large triangle is placed on top of the plug and a pair of ribs attached to the plate at an angle of 90 degrees. Welding must be taken at several points at once. The final fastening is done as a double seam.
The cross-shaped tip requires fixing the auger blades above the peaks. Therefore, high throughput of various rocks is achieved due to the increased tightening force. As for the blades, it is possible to simplify screwing them into the ground by putting a screw at the very bottom of the tip, leaving at least 2/3 of the length on top. The exemplary pitch of the blade is 50–70 mm. To obtain the blades, sheet steel of a large thickness of at least 0.5 cm is used.
A solid screw with one run requires you to spread the blades with a crowbar or mount to the selected step. If the structure is formed from several blanks at once, it is much more correct to cut single segments (no more than ½ circle). Separate sections are sequentially welded to a peak or to the pile body. The first approach makes it impossible to create a complex screw, however, it provides a stable geometry of the structure. In the second scheme, assembly of the auger with several runs is not particularly difficult, but care must be taken so that the view of the spiral is not disturbed.
Before manual cutting, workpieces are marked with an external diameter of 150–300 mm, this depends on the load per pile, most often they are limited to a corridor from 200 to 250 mm. They try to equate the inner diameter to the outer size of the pipe. Drawing a segment connecting the circle in the cavity and on the outside is carried out in a randomly selected place, but it is still worthwhile to approach this work more carefully. Parts need to be cut with a plasma cutter from a sheet with a thickness of 0.5-0.7 cm, instead of a plasma one you can take a gas cutter. When working, they carefully look so that the cut width is taken into account, and the seat is processed properly.
During the wiring, the section opposite the cut location is clamped in a vice and pushed apart with a crowbar or crowbar. When there is no vise, you can simply apply a gap in massive steel structures. But in any case, it is worth constantly observing whether the screw has a normal pitch at the screw or not. To obtain piles with multiple runs, you can apply other options. So, in one of them, the marking of the inner diameter is made the same as the external size of the pipe (200-300 mm).
The ring obtained with this markup is divided into a pair of segments into identical half-rings. Figured cutting implies the ability to perform actions in any sequence, but here a professional-class tool is already required. The technique of "installation on a pile" assumes that, according to screw marking, they grab the initial half-ring and verify compliance with the right angle. If everything is correct, other half rings are put on the same line - as many as it is planned to make turns. Attention: slight deflection of half rings is allowed for more exact correspondence to their design dimensions and geometry.
No matter how high-quality the pipe itself is made, anti-corrosion protection is also very important. According to the results of special engineering surveys, it was found that the annual loss of piles and their blades is 0.01 mm of walls and this is in almost ideal conditions. If the soil is very chemically active, if the effects are large, wear can be accelerated several times.
After descaling and when processing completely new pipes, the following can be used:
- enamel from two components is made specifically for underground metal products, service life - at least 60 years;
- enamel based on polyurethane requires preliminary application of VL05 primer, will last at least three decades;
- fiberglass. Before applying it, you will have to treat the base with a cold zinc coating. The total service life (theoretically calculated) reaches 3-4 centuries; a stable resistance to electrochemical corrosion is ensured.
But fiberglass can hardly be called affordable material. In order to save, most often use complex coatings based on epoxy resin. As for the initial steel, the standard St20 or GOST 8732-74 allows you to count on the reliable operation of the supporting element in ordinary home construction. Only under very high loads or under harsh operating conditions does it make sense to focus on GOST 19281. For the most part, the corresponding piles are used in industrial and multi-story construction, for the development of a personal plot their characteristics are redundant. Regardless of the type of supports used, their length is selected in such a way as to accurately get to a layer of solid soil.
At the same time, it is necessary not only to achieve it, but also to leave a reserve for deepening by 30–35 cm. When it is planned to bring piles higher above the ground, you can even further increase this gap. Timely reserve in height avoids the subsequent tedious build-up and potential errors associated with it. To determine the required diameter of the pipe with its independent manufacture, as well as with the selection of finished structures, it is worth considering the norms of SNiP 2.02.03-85. Yes, it’s quite difficult, but it will help to do everything very accurately and clearly.
Most often, pipes with a diameter of 4.7-7.6 cm are used in the construction of light types of fence and barrier structures. By increasing it to 7.7–8.9 cm, you can be sure of the stability of a brick bath, a capital gazebo or a powerful brick fence. But for frame buildings, for log houses and houses of two, three floors, it is recommended to use piles with a diameter of 10.8 cm. You should not always strive for the maximum value, since this entails only unjustified consumer expenses. Important: in artisanal conditions it is extremely difficult to make piles larger than 10.8 cm.
For such products, reinforced blades need to be mounted, and only industrial production can make them efficiently. In addition, increasing the diameter, complicate the formation of the screw. The walls of the trunk along with this, even under the lightest structures on favorable soil, cannot be thinner than 0.4 cm. When choosing the right thickness in a particular case, it is recommended not to forget that the bend of the cone will have to be provided with hammer blows. So here too the principle “the more the better” does not work here.
Advantages and disadvantages
The undoubted advantages of the pile-screw base for the house are the following:
- the ability to do without special machines with a small scale of work;
- exclusion of formwork and socle;
- equally high-quality work in any season;
- ventilation under the floor of the house;
- the ability to dismantle any structural element.
But even such an attractive solution has a number of disadvantages. It cannot be erected on rocks, and regardless of the quality of protection, the risk of corrosion must always be considered. The level of load on the foundation is limited; in addition, screw piles are much more demanding on the quality of work. The slightest deviation from normal technology can provoke the failure of the supports, their curvature or pushing up. These negative aspects, however, do not allow to ignore the fact that the screw substrate is good on the banks of rivers and lakes, on moorings, in wooded areas, and so on.
Just preparing piles for work, even very good ones, will not be enough. The installation of a pile-screw foundation under the house has a number of specific features that cannot be ignored. Screw piles, resembling huge screws in appearance, are immune to freezing of soils and can penetrate to various depths. Screwing into the soil, folded by any rocks, is facilitated by a pointed end with a cutting part. Piles compact the soil around themselves and effectively suppress its expansion.
Corrosion resistance is largely determined by the type of protective coating used. Polymers provide the best cover, but putting them on metal is extremely difficult. The use of screw piles for temporary and utility structures, for the infrastructure of personal plots is widespread. The foundation of them can withstand a total load of 50 tons, and a single pile can easily withstand pressures up to 9 tons during the entire normal service life. When a temporary structure ceases to be necessary or should be moved to another place, even transported, you can take a pile with you and save on foundation materials. By the type of tip used, the screw structures are divided into elements with a narrow and wide blade, and the second are still divided into one or two turns.
A single-turn product is equipped with only one turn, hence the name. Its top is equipped with special holes to fix and use the drill. Single-turn solutions are preferred in the construction of fences and minor structures. A wide blade is attractive during the construction of a two-story house, as well as during any work in areas with unstable soil. The stability of the fastening increases markedly. But even among piles with narrow blades, there is a gradation - for multi-turn and tubular ones.
The presence of several turns allows the formation of pointed tips. Such a solution allows you to successfully pierce even very dense soil. The tubular product is preferably in the winter months when the ground is frozen and poorly cultivated. Special openings let ground pass through. Going inside, it makes the entire structure much more stable than in a full-bodied version.
In order to eliminate errors, it is important to remember that even formally related piles of Russian and foreign piles may differ from each other. The selection of a suitable solution should only be made after consultation with geologists and engineers.
The following factors are taken into account:
- soil characteristics;
- level of penetration of cold into the ground;
- climatic properties of the area;
- groundwater elevation.
Installed piles in any case need to be concreted. This will help to fix the support in the soil and at the same time cover it from corrosion processes. Coniferous wood can be used as a strapping. It is recommended to take blocks for strapping that are noticeably wider than the piles being mounted. The cone-shaped tip is placed on piles filled with cement, and if the slice is made oblique, when tightening, the support block must be filled with soil.
Varieties of piles
Which are there?
Galvanized piles are characterized by increased reliability and excellent durability. Zinc can be applied hot and cold. But even such a good layer will require special anti-corrosion treatment. Hot preparation is considered the best, since such a finish reduces the formation of scratches and other defects during installation. A galvanized pile performs well in the construction of aboveground structures and, if necessary, provide the highest environmental performance.
In most cases, concrete of low grades of the category (M200 and M300) is taken for concreting screw supports. M200 mortar is used for one-story and two-story buildings with light and medium floors. Cast and welded tips are two key options that screw piles are equipped with. Welded technology involves the attachment of metal blades of 0.3-0.5 cm; it is cheaper than casting or concrete products, but reliability is still insufficient. When screwing into solid substrates, destruction or even separation of parts from each other occasionally occurs.
The cast version has another advantage: it is done much more precisely, steel of the 25th grade is used for work. Be sure to heat treatment of castings, which increases the strength of structures. The tips of the cast version are equipped with blades with a base 1.3 cm thick, and the closer to the edge, the finer the product. Such a solution allows you to confidently pass even very complex soil masses, there is no need for early loosening. The spread in size will be minimal, the behavior of piles during installation will be completely predictable for developers.
For what soil?
Galvanized elements can be embedded in any soil, for this purpose they are equipped with tips in the form of a cone. The use of such supports is quite possible even in mountainous areas. Attention: screw piles must not be mounted in soil composed of coarse rocks and rocky inclusions. A large-detrital base is considered to be such that it is formed from mechanically uncoupled fragments of rocky stones and weathering rocks. In such a soil, fragments larger than 0.2 cm fall from 50% of the total mass and volume.
The reason for the ban is simple - large pieces of stone can cause damage to even the most durable metals and alloys. It should be borne in mind that when the location of problematic mineral structures is deeper than 150 cm, installation is usually not difficult. But the final decision should be made only by qualified engineers, since the slightest mistake threatens with serious consequences. Sandy soil is more favorable for passing through screw piles and usually does not bring unpleasant surprises. Already at a depth of 1.5 m, the strength of the substrate material most often allows the building to be supported as reliably as possible.
Dusty clay is slightly worse because it is prone to very significant swelling. Sandy loam and loam in this regard is slightly better, but inferior to the sand base. You can solve the problem by increasing the depth of implementation. If the blades abut against strong material, the piles will definitely stay in place and will be able to maintain the integrity of the house for many years. As for subsidence soils, the construction on them is extremely difficult, and you will definitely have to conduct test drilling and evaluate the properties of soils.
Design and Calculation
Having chosen the appropriate option for the execution of piles, you need to start calculating their linear parameters and drawing up projects, to the formation of drawings.
Only careful calculations allow you to choose the following:
- the necessary height of the structures;
- total number of supports;
- the diameter of each of them;
- bookmark depth;
- the amount of expenses for the construction of the foundation.
The sequence of calculations is not determined arbitrarily, it is very clearly fixed in SNiP 2.02.03.85. According to this standard, when determining the necessary structural properties, one cannot limit oneself only to data on the topography and depth of groundwater circulation. It is extremely important to focus on the real amount of precipitation falling in a particular climate zone. If for some reason it is impossible to perform high-quality geodetic research, you have to take the minimum design load as a basis. The determination of the number of screw piles is made by multiplying the total load by the result of dividing the reliability coefficient by the maximum permissible load level.
It is recommended that the load on each of the piles be proportional to the total load from the structure. Proper construction that complies with GOST standards always provides for uniform load distribution under load-bearing walls and under areas of increased pressure. Additionally, the roll force is analyzed. In many cases, it is possible to guarantee the service life of a building no less than a certain bar only when contacting specialists. A simpler method for determining the size and physical parameters of structures is to use special software.
When calculating the created load, it is required to take into account the mass of ceilings and operating pressure from people in the house, from their property. At the same time, professional architects do not forget about the load formed by gusts of wind, draft of the building and jerky temperatures. Piles with a wide blade and a cast tip are considered the best solution for low-rise buildings on relatively simple soil. If you take structures with many blades placed at different levels, this will help to withstand even very powerful loads in complex soil. Variable perimeter products are introduced into the project if it is necessary to solve a specific range of problems; finally, a narrow blade with a molten end with teeth will do fine with stony ground and even permafrost.
Pile trunks obtained from a suture pipe by welding the blades are considered the least reliable solution . Use of such structures is permissible only with a limited amount of loads and on “good” soil. It is believed that a pile with a diameter of 8.9 cm with a blade size of 25 cm can withstand a maximum of 5000 kg. This is exactly the operational load created by a one-story frame-panel house. A structure with a diameter of 10.8 cm with a blade of 30 cm can easily withstand up to 7000 kg, that is, it is already suitable for two-story timber and block buildings.
When it is planned to use aerated concrete blocks and bricks for building a house, the project provides for the use of piles with a diameter of 13.3 cm with a blade 35 cm wide.
Many years of practice have allowed the formation of universal requirements for the length of the supports, namely:
- in loams located up to 100 cm from the surface, a rod 250 cm long is introduced;
- in loose soil and quicksand they introduce such a pile that is able to reach a dense mass;
- the difference in areas with uneven terrain can reach 50 cm.
If, according to the results of calculations, it turns out that you will have to make this difference larger, you really need to either refuse to use piles at all, or carefully smooth out the unevenness of the terrain, remove excess soil or pour in the lowlands. When it is planned to put a wooden frame or a block house on top, the distance can be from 2 to 2.5 m. A little further, you can extend the supports exposed under the structures of logs and timber. To ensure that everything is reliable and lasts a long time, you must not raise the base higher than 0.6 m. A margin of 200–300 mm is left along the length of the piles.
Particular attention should be paid when designing the most problematic places. Usually they are the corners of buildings and the intersection between the bearing wall and the internal partitions. The loads arising at the entrance groups and around the perimeter are quite large. To enter to hold the stove and fireplace requires at least two piles. At least one support should be placed under the bearing walls in those places where the mezzanine, balcony are located.
If, from actual operating conditions, it follows the need to add the number of screw piles compared to the calculated one, one should not be afraid of such a step. On the contrary, increased strength will provide real cost savings, since the quality of the building will be optimal for the entire time of use. When calculating a grillage of any type and height, they calculate as carefully as possible how the foundation as a whole and each corner will be pressed. Additionally, bending energy is calculated. In the variant with a high type grillage, 100% of the load is superimposed on the piles, and therefore accurate calculation without outside help or at least without specialized software will be quite complicated.
The most thorough calculations and the most well-thought-out projects will not give a positive result, if you approach the pile driving thoughtlessly. Although their developers and manufacturers are actively introducing solutions into their designs that make it possible to compensate for some of the construction errors, it is better to install supports under the house or other structure in accordance with all the rules. And this means thorough preparation of the site, even when “just” a bathhouse or a garage is being built. The matter is not limited to geological exploration and collection of data on the desired type of piles, on the required depth of their laying, and so on. Sometimes it is necessary to screw or hammer pile elements in the form of a sample in order to better evaluate the characteristics of a particular site from experience.
On construction sites with strong soil, it will be enough to level the territory , remove all bushes, trees, grass and their roots, remove garbage of any kind. But where the earth is loose, very soft or not very stable, you need to level the site. In places with a high groundwater table, preparation often involves the removal of melt drains and drainage. To guarantee the absence of any kind of vegetation under the house, sometimes it is even necessary to remove the fertile layer, removing 200-300 mm of soil mass from the surface.
The importance of the initial clearing is not only that it opens up opportunities for construction work. Only in this way can one correctly mark the zero level and start reading from it the tiers of the building as a whole. The marking is made not only on the plan, but also on the ground. To make it more explicit and convenient for use, pulling a rope or wire held by stakes will help. A simpler option is to dig small recesses filled with lime. Connecting anchor points of the line are drawn directly on the surface with the help of shovels and other trench tools.
Having drawn the lines, their and boundary points must be checked once again with the drawing and plans. It is better to spend even a few hours on it, than to complain for years about the mistake made. Regardless of the strength of the piles to be mounted, it is necessary to take into account the probability of their destruction from external influences. Experienced builders always take maximum care to protect the supports from water and soil mass migration. Even the insulation of the site under the house is quite justified.
When it is decided to fill the tape over the pile foundation, the entire area to its sole is saturated with soil mass. Before pouring the mixture, it is necessary to cover the empty spots on the piles with a primer layer or other waterproofing agent. This will provide an air cushion between the building and the ground to the thickness of the tape. Only when all this has been done can we proceed to the installation of the foundation itself. To do it manually or at the expense of special equipment - this must be decided individually in each case.
Knowledge of piling technology is significant for any builder. If you make a mistake, you may encounter a decrease in working life and a decrease in the strength of the base. Depth with the required bearing capacity should be determined below the freezing mark. When purchasing piles taking into account this depth, it is necessary to take into account the rise of 50 cm above the ground, which makes it possible to level the pile field.
The axes of the load-bearing walls are marked immediately after this, along with them the marking is carried out for any structures that create a load, such as:
- staircase in the house;
- stove or fireplace.
Do-it-yourself or bought piles require immersion in well-drilled leading holes. Cutting out the ends protruding outward is made under the general horizontal level. The strapping is carried out using a grillage and stiffening parts, but you need to resort to both elements only when the pile height is more than 1.5 m above the ground. Piles that do not have a zinc coating must be concreted from the inside to prevent corrosion. This requirement is important even for structures with a polymer or fiberglass layer, which inside the pipe cannot be monolithic for technical reasons.
The role of experimental twists is great, they complement the picture that geological surveys provide, and in some cases they completely refuse to pay for the help of geologists. One pile is alternately introduced in several selected places to finally determine the depth of placement of the bearing soil. In addition, it turns out whether there is a top water, how strong it is, whether there is a waterproof soil at the bottom. Having dealt with all these points, you should proceed to the marking, which is carried out by cords on the castoffs. The points where the centers of the piles should be introduced must be marked with crosses.
Guiding holes are drilled along these crosses or pits are dug. To twist the lighthouse piles (angular), placed in the places of mating walls, relies primarily. Only this technique guarantees the coincidence of real and design contours of the building. Minor deviations of individual supports are eliminated due to heads with extended platforms. It is rather difficult to manage without leading holes; they significantly simplify vertical positioning of tubular structures and the introduction of spirals into the ground.
The maximum permissible error when using lighthouse piles does not exceed 50 mm. At intermediate points, support blocks can be installed with less stringency. However, if all the beacons are made correctly, the probable deviation will be within the limits without additional efforts. A pile field at the installation site of a major furnace or other heavy source must have 4 piles with a grillage in the form of a plate. Under stationary pumps over 400 kg there should also be a pile.
If you plan to install a backup generator on top, the upper part of the grillage is covered with a tape that isolates vibration. Depending on the expected mass, 2 or 4 piles are placed under the internal stairs. The foundation under the porch is formed strictly individually, while paying attention to the geometry and nuances of the structure, to the layout of the house and the arrangement of the adjacent territory, including the blind area. The main thing is not to forget about all these piles, so that you do not have to screw them in hastily, revealing rough floors and breaking an already debugged system. At this stage of work, you should deal with the installation of utilities, with their thermal insulation and with the addition of heating cables.
Screwing piles into the foundation using special equipment is quite expensive , so almost every builder prefers other options. Completely manual work requires the participation of three people, the SHS is rotated by two of them, and the third controls. By mechanizing the process (using a drill with a planetary gear), you can limit yourself to two participants. One monitors the vertical entry of the product, and the other facilitates the initial stage of implementation. Despite the increased labor costs, a completely manual technique is more practical, it allows you to immediately identify the entrance to the bearing layers by the growth of the pulling force.
To reduce construction costs, it is necessary immediately, at the time of design, to decide whether or not headings are needed. But it is useful to take into account that a significant deviation during operation from the normal axis will nevertheless force the installation of these elements. It is not necessary to set the heads over the grillages made of metal and reinforced concrete. Since the welding of the tips to the piles forms corrosion foci, it is required to use paints containing zinc and aluminum for protection. They perform their function only when slag and scale are removed from the surface.
Screwing in a pile can cause its tip to move to the side. Plates help align the wall axes when the pile floor is tied with a grillage. It is impossible to do without a tip where a grillage made of wood cannot be fixed on a round pipe. It is also useful where beams from channels welded onto a rib are used, the support area of which should be increased, otherwise welding seams cannot be formed. As for pushing piles apart from the wall axis, the tip helps to fix defects up to 100 mm in both directions.
In any other case, there is no need to use welded plates. The foundation of the SVF under a brick house necessarily requires a monolithic grillage. Under the log cabins and two-story, three-story frame houses, the reserve of the fortress is achieved due to the I-beam or channels. When it is planned to put light housing at the top, you can restrict yourself to timber or boards. Monolithic grillages are created with formwork, reinforcement is carried out through the pile bodies, it is bricked up in concrete along with the heads.
I-beams and channels need to be welded to piles without heads. When the pile field is on a slope with a change in height of more than 150 cm from one opposite wall to another, it is impossible to do without reinforcing strapping with rigid struts or vertical connecting elements. Flanges are needed to attach them. Such technology guarantees a total foundation resource of at least 70 years.
When all the necessary data are collected and the depth of freezing is estimated, it is required to free the construction site from everything that can interfere with the work, even to a small degree. Additionally check the grade of steel and specify the parameters of the necessary pipes. When marking up the territory, you can focus on the drawings of both the house as a whole and its first floor. A pile with a transitional head at the top is mounted in a certain hole in advance and fixed through a hole. When turning protruding levers becomes difficult, use pipe levers.
When the pile sinks, the heads are changed to shorter ones. If it was not possible to go through the freezing line, the cause may lie in solid stone. They simply bypass it, moving nearby. So move the support if necessary until the barrier is broken. The twisted piles are cut to one horizontal and saturated with a solution of concrete.
Details on how to tighten screw piles, you can see in this video.