EP0481079A1 - Method and tool for producing a pile - Google Patents

Abstract

The method for pile production consists of supplying a binding construction material (6) to a drilled hole (1) or to the ground, while producing high-voltage discharges in the construction material (6) and of moving the region (7) of the construction material supply and of the discharge excitation above the height of the pile which is to be produced. A total discharge energy at a given depth is selected such that the expansion of a corresponding section of the drilled hole (1) or of the ground is achieved at this depth up to the desired diameter of the pile. A region (8) of anchored ground with an increased strength, and a region (9) of compressed ground with improved building properties are formed around the pile under the influence of discharges. The pile production tool contains a pipe (3) for supplying the construction material and a discharge device, having electrodes (10, 11) which are arranged coaxially and are displaced with respect to one another and which are mounted on an insulating bar (15) which runs inside the first electrode (10). The first electrode (10) is connected to the end of the pipe (3), where its outlet opening (7) is located, in such a manner that its axis is parallel to the axis of the pipe (3) and a distance between the second electrode (11) and the outlet opening (17) of the pipe (3) is not smaller than a distance (16) between the electrodes. <IMAGE>

Description

Technical field

The invention relates to a method and a tool for the manufacture of a pile and can be used in the manufacture of pile foundations in the construction and reconstruction of buildings and engineering structures.

Previous state of the art

A method for pile production is known (DE, C, 2651023), which is used to reinforce the existing foundations, and to bring down boreholes with the help of rotary impact drills while protecting casing pipes, to attach fittings and to insert a pipe for pumping a sand cement mortar into the drill block includes. After a mortar has been pumped in, an injection pipe is inserted into the borehole before it is set and a cement mortar is pumped in through this pipe under increased pressure, so that an extension is formed on the base of the resulting pile.

A disadvantage of this method is a low load-bearing capacity of the pile over its side surface, because a borehole is formed by excavating the floor and a loosened layer of soil is formed on its walls, which does not take part in the joint work with the pile. Therefore, you are forced to run a long-length pile so that its lower end is supported against a solid foundation (a rock, a moraine).

Another disadvantage of the method is also a low work output, because the operations for drilling a borehole, attaching casing pipes, pulling out a drilling tool, inserting a pipe into the borehole for pumping a sand cement mortar, filling the borehole with this mortar, pulling out the Formwork pipes and the pipe for pumping in the sand cement mortar, for inserting an injection pipe into the borehole and for pumping in a cement mortar one after the other, whereby a technological break must be taken between the latter two of the specified operations, which is related to the setting of a pile building material, which serves as a packer when pumping the cement mortar under high pressure.

A tool for producing a pile with a pipe for supplying a setting building material is known (US, A, 4060994), which is connected to a mortar pump. The pipe is immersed in a borehole and, under pressure, it is fed with a setting building material which forms a pile body, the pipe being pulled out during the borehole filling with building material.

A disadvantage of this tool is that a pile made with the aid has a low load-bearing capacity because the tool only ensures that the building material is fed into the borehole without compaction of the surrounding soil. The reduction in the load-bearing capacity of a pile is also connected with the fact that when the setting building material is fed into the borehole, it is inevitably mixed with water or soil. In addition, continuity of the pile building material over the length of the pile is possible due to the breakthrough of groundwater or clay flushing into the interior of the pipe.

A disadvantage of the tool is also that it takes a long time to use it to make a pile because, in addition to drilling the hole and filling it with setting mortar, there are operations to protect the hole from collapse of its walls, i.e. install casing pipes in it or fill it with clay flushing.

Disclosure of the invention

The invention has for its object to develop a method and a tool for the manufacture of a pile, by means of which a floor area with increased density is formed around the pile, which cooperates with the pile, and the time of pile manufacture by reducing the Number of operations can be shortened.

This object is achieved according to the invention in a method for producing a pile by feeding a setting building material into the pile formation area in that electrical high-voltage discharges are generated in this building material when the building material is fed into the pile formation area, the area of the building material supply and the generation of discharge over the depth of the pile formation area is moved during the formation of a pile body and the total discharge energy is selected at each depth of the pile formation area in such a way that an increase in the diameter of a corresponding section of this area up to the desired diameter of the pile is ensured at this depth.

The increase in the load-bearing capacity of the pile produced by the method according to the invention is associated with the fact that when the high-voltage discharges are generated in the setting building material supplied to the pile formation area, there is a periodic, sudden increase in pressure, which expands this area, compresses the soil around this area, pushes the seepage and Pore water and infiltration of the setting building material into the freed-up soil pores. As a result, an area of anchored soil and an area of compacted soil are formed around a pile around the first area. In addition, according to the method according to the invention, the cross-sectional area of the pile can be changed along its length by changing the total energy of the discharges over the depth of the pile formation area, as a result of which the load-bearing capacity of the pile can be adjusted depending on the type of soil during its manufacture.

In the method according to the invention, no operations are required to protect the borehole walls from collapse in accordance with the existing known methods (casing pipes, clay flushing), and the production time is also shortened by simultaneously carrying out the operations for supplying building materials, forming the pile body and soil compaction.

The setting building material can be fed to a pilot borehole, which represents a pile formation area.

The imaging building material can also be fed directly to the soil, which in this case represents a pile formation area. An additional reduction in the time for pile production is achieved in that no borehole drilling is required.

If the pile is manufactured with a radius that changes along its length, when the area of the building material supply and the discharge generation is shifted, it is expedient to change the number of discharges in such a way that in a given depth of the pile formation area this number is directly related to the desired radius of the pile at this depth is proportional.

If the pile is manufactured with a radius that can vary in length, you can change the sequence of the discharges by shifting the area of the building material supply and the discharge generation so that their value in a given depth of the pile formation area is directly proportional to the target radius of the pile at this depth is.

beträgt, wobei

r

Sollradius eines Pfahls in einer gegebenen Tiefe, m;

r_o

Radius eines Pilotbohrlochs, m;

W

Energie einer Entladung in dieser Tiefe, J;

K

Intensitätsfaktor einer Speicherung der bleibenden Bodenverformungen und

χ

Koeffizient, der von Bodeneingenschaften abhängt, bedeuten.

When making piles in a pilot well, it is desirable that the number of discharges n be at a given depth of the pile formation area

is, where

r

Target radius of a pile at a given depth, m;

r _o

Radius of a pilot borehole, m;

W

Energy of a discharge at this depth, J;

K

Intensity factor of a storage of the permanent soil deformations and

χ

Coefficient that depends on soil properties mean.

beträgt,wobei

r

Sollradius eines Pfahls in einer gegebenen Tiefe,m,

W

Energie einer Entladung in dieser Tiefe, J,

K

Intensitätsfaktor einer Speicherung der bleibenden Bodenverformungen und

χ

Koeffizient, der von Bodeneigenschaften abhängt, bedeuten.

According to one variant of pile manufacture directly in the ground, the area of the building material supply and the discharge generation is moved into the ground depth, the number of Given discharges n at a depth

is, where

r

Target radius of a pile at a given depth, m,

W

Energy of a discharge at this depth, J,

K

Intensity factor of a storage of the permanent soil deformations and

χ

Coefficient, which depends on soil properties, mean.

wobei

d

maximales Querschnittsmaß des Werkzeugs, das die Baustoffzufuhr und die Entladungserzeugung sicherstellt, mm und

f

Bodenfestigkeitszahl nach Protodjakonow bedeuten

und die Anzahl der Entladungen n in einer gegebenen Tiefe bei der Aufwärtsbewegung des besagten Bereichs nach dem Verhältnis

ermittelt, wobei

W

Energie einer Entladung in dieser Tiefe bei einer Aufwärtsbewegung des Bereichs der Baustoffzufuhr und der Entladungserzeugung, J;

r

Sollradius des Pfahls in dieser Tiefe, m;

K

Intensitätsfaktor einer Speicherung der bleibenden Bodenverformungen; Koeffizient, der von Bodeneigenschaften abhängt, und

d

maximales Querschnittsmaß des Werkzeugs, das die Baustoffzufuhr und die Entladungserzeugung sicherstellt, m bedeuten

According to the other variant of the pile manufacture directly in the ground, the area of the building material supply and the discharge generation is moved to the ground depth and after a given depth has been reached, which corresponds to the corresponding desired pile length, said area is moved upwards, the energy W 1 being one Discharge when moving down this area according to the ratio

in which

d

maximum cross-sectional dimension of the tool, which ensures the supply of building materials and the generation of discharge, mm and

f

Soil strength number according to Protodjakonow mean

and the number of discharges n at a given depth upon the upward movement of said area according to the ratio

determined where

W

Energy of a discharge at this depth with an upward movement of the area of the building material supply and the discharge generation, J;

r

Target radius of the pile at this depth, m;

K

Intensity factor of storage of permanent soil deformations; Coefficient that depends on soil properties and

d

maximum cross-sectional dimension of the tool, which ensures the supply of building material and the generation of discharge, m mean

ermittelt wird, wobei

b

zulässige relative Abweichung vom Solradius eines Pfahls, Sollwinkel des Pfahlkegels, m und

r' und r''

Pfahlsollradius am vorherigen bzw. am nächsten Schritt bedeuten.

If a conical pile is produced, it is expedient to move the area of the building material supply and the discharge generation with in a step Δ h, which is according to a ratio

is determined, whereby

b

permissible relative deviation from the sol radius of a pile, nominal angle of the pile cone, m and

r 'and r''

Target pile radius at the previous or next step.

The object is also achieved in that the tool for producing a pile with a tube for supplying a setting building material according to the invention additionally contains an electrical discharge device with coaxially arranged and mutually displaced electrodes, the first of which is designed in a ring shape and on an insulating rod running inside it is attached and the second is attached to the end of this rod and is connected to a current-carrying rod which is arranged inside the insulating rod and is connected to the central core of a coaxial cable, the shielding braid of which is connected to the first electrode, the diameter of the second electrode being larger than the diameter of the insulating rod, the first electrode is rigidly connected to the pipe end at which the outlet opening of the pipe is located, such that the axis of the first electrode is parallel to the pipe axis and the distance of the second electrode from the outlet opening pipe is not less than the electrode gap.

Thanks to a discharge device, which is arranged on the pipe for supplying a setting building material in the vicinity of its outlet opening, the tool according to the invention can be used when carrying out the method according to the invention, since it can generate high-voltage discharges therein simultaneously with the supply of a setting building material. The tool is suitable for producing a pile both in a borehole and directly in the ground.

The invention is explained in more detail with examples using the drawing.

Brief description of the drawings

Fig.1

den Vorgang der Pfahlherstellung nach der einen Ausführungsvariante der Erfindung,

Fig.2

den Vorgang der Pfahlherstellung nach der zweiten Ausführungsvariante der Erfindung,

Fig.3

die erste Stufe des Vorgangs der Pfahlherstellung nach der dritten Ausführungsvariante der Erfindung,

Fig.4

die zweite Stufe des Vorgangs einer Pfahlherstellung nach der dritten Ausführungsvariante der Erfindung,

Fig.5

ein Werkzeug zur erfindungsgemäßen Pfahlherstellung und

Fig.6

Änderungen der Bodenkennzahlen um einen erfindungsgemäß hergestellten Pfahl.

It shows:

Fig. 1

the process of pile manufacture according to one embodiment variant of the invention,

Fig. 2

the process of pile manufacture according to the second embodiment of the invention,

Fig. 3

the first stage of the pile manufacturing process according to the third variant of the invention,

Fig. 4

the second stage of the pile manufacturing process according to the third embodiment of the invention,

Fig. 5

a tool for pile production according to the invention and

Fig. 6

Changes in the soil parameters for a pile manufactured according to the invention.

Best embodiments of the invention

The method according to the invention is carried out as follows. According to any known method, for example by rotary drilling, a pilot borehole 1 (FIG. 1) is drilled with a diameter that is smaller than the diameter of a manufacturing pile (in the case of a cylindrical pile) or as the minimum diameter of a pile to be manufactured ( in the case of a pile with a diameter that varies in length). In borehole 1, if necessary, an armature and a tool 2 in the lower part of the borehole 1, which contains a pipe 3 for supplying a setting material and an electrical discharge device 4. The pipe 3 is connected to a mortar pump (not shown) and the discharge device 4 to a current pulse generator 5. An electrically conductive setting building material 6, for example based on cement or synthetic binders, is supplied continuously or in portions via the tube 3 and current pulses are applied to the electrodes of the discharge device 4 by the generator 5, whereby 6 high-voltage electrical discharges are generated in the building material. The area 7 below the lower end of the tool 2 thus represents an area of the building material supply and the discharge generation. Each discharge causes a sudden increase in pressure in the borehole 1, which is partially or completely filled with building material 6. Under impact, the building material 6 is compacted in the area 7, the borehole 1 is expanded in its lower part, the seepage and pore water is pressed away from the adjacent soil and the building material 6 penetrates into the water-free soil pores to form an area 8 an anchored floor, which has an increased strength, and an area 9 of a compacted floor around the area 8, which has improved construction properties (the load-bearing capacity of the floor is increased by reducing the pore number and increasing the modulus of the soil deformation). A free volume that arises when the building material 6 is compacted is constantly filled with new building material portions, so that each subsequent discharge takes place in a new volume of the setting building material.

A total discharge energy, in this case a number of discharges, is selected in such a way that an expansion of the lower section of the borehole 1 up to the desired diameter of the pile in the lower pile part is ensured. In this way, the pile sole is formed.

The inventors have found in experiments that the energy of each discharge has to be at least 5 kJ, and the pressure of a hydraulic current in borehole 1 can be increased to 50-200 MPa. In the case of discharges with an energy of less than 5 kJ, the time of the pile formation exceeds the setting time of a setting building material, which causes a reduction in the strength of the pile building material. It is impractical to generate discharges with an energy of more than 200 kJ, because such an increase in the loads on borehole walls can cause the permissible vibration velocity in the ground to be exceeded and, from a seismic point of view, harmful effects on neighboring buildings and structures. In addition, when the discharge energy is increased, the mass and dimensions of the system with which the method is carried out are increased.

wobei

r

Sollradius eines Pfahls und

b

zulässige relative Abweichung von Pfahlsollradius bedeuten.

Thereafter, the tool 2 and consequently the area of the building material supply and the discharge generation located below this are moved with a step Δh and the process described above is repeated, whereby the next sections of the pile body are formed. In this case, if a pile with a length that can be varied in length is produced, the number of discharges at the next step is increased compared to that at the previous step when the pile radius is increased and vice versa. The size of the step Δ h is determined depending on the existing law of a change in the radius of a pile over its length and on the required accuracy of the pile position. In the manufacture of a cylindrical pile, the step Δh remains constant and its size

$\text{Δh = r Sin [arcCos (1-b)] (6)}$

in which

r

Target radius of a pile and

b

permissible relative deviation from the target pile radius.

wobei

r' und r''

Pfahlsollradius am vorherigen bzw. nächsten Schritt und
Sollwinkel eines Pfahlkegels bedeuten.

When a cone pile is made, the step Δh becomes the ratio

in which

r 'and r''

Target pile radius at the previous or next step and
Mean target angle of a pile cone.

With this step value, the number n of discharges on each step can be selected such that the radius of a pile section to be produced falls below the target radius r by an amount b _r on each step. This is connected with the fact that on each step a pile section is produced in the form of a spherical segment with a surface whose circumference exceeds that of one and the same pile section with the nominal radius. The method thus gives the possibility of reducing the volume of a pile produced without deteriorating the load-bearing capacity and thereby saving on the building material.

The operations described are continued until the pile body with the length h is completely formed and then the tool 2 is removed. When the building material 2 is supplied, its throughput is adjusted so that the building material level in the borehole 1 lies in the plane of its mouth.

wobei

χ

Koeffizient, der von Bodeneigenschaften abhängt, und

W

Energie einer Entladung, J bedeuten.

In experiments, it has been found that, as a result of the first discharge, the radius r _{o of} a pilot borehole 1 is expanded to a value r 1 which is

in which

χ

Coefficient that depends on soil properties and

W

Energy of a discharge, J mean.

des Radius eines Bohrlochs 1 nach einer empirischen Abhängigkeit ermitteln:

${\text{Δr}}_{\text{n}}\text{= r₁(K ln n +1) (9)}$

wobei

Δr₁ = r₁-r_o

Radiuszuwachs des Bohrlochs unter der Wirkung der ersten Entladung und

K

Intensitätsfaktor der Speicherung der bleibenden Bodenverformungen bedeuten.

After the number of n discharges there is an increase ${\text{Δr}}_{\text{n}}{\text{= rr}}_{\text{O}}$

determine the radius of a borehole 1 based on an empirical dependency:

${\text{Δr}}_{\text{n}}\text{= r₁ (K ln n +1) (9)}$

in which

Δr₁ = r₁-r _o

Borehole radius increase under the effect of the first discharge and

K

Intensity factor of the storage of permanent soil deformations mean.

From the expressions (8) and (9) it follows that a number of n discharges is required to form a pile section with the diameter r, which is

The K and χ numbers are determined empirically. The K number depends on the soil condition and changes in the range from 0.2 to 0.7. The χ number depends on the type of soil and increases with increasing soil density. The χ number for sand is 0.00163 and for clay soil 0.0021.

In the case under consideration, when producing a pile with a radius that varies in length, the total discharge energy during the movement of the tool 2 is changed in proportion to the required change in the pile radius, as follows from expression (10). The tool is moved discretely with a step Δh, the repetition frequency of the discharges is constant in this case and it is selected depending on the desired duration of a pile production taking into account the properties of the setting building material used, but not below 0.05 Hz. It is it is also possible to regulate a total discharge energy over the length of a pile to be manufactured by changing the repetition frequency of the discharges in accordance with changing the pile radius. It is obvious that the larger the required pile radius at a depth, the greater the repetition frequency of the discharges should be at this depth and vice versa. In this case, the tool 2 is moved continuously at a constant speed.

When choosing a repetition frequency of the discharges, it must be taken into account that the process of pile formation involves an expansion of the borehole 1 and a soil compaction around it around. This process proceeds in various ways depending on the ratio of the discharge frequency to the rate of pressure reduction in the borehole filled with a building material. If the repetition frequency of discharges is not more than 0.1 Hz, each next discharge takes place after a full pressure reduction and after an end of consolidation of the soil, which is compacted when the discharge is generated. With a frequency increase above 0.1 Hz, the processes of destruction of the soil structure and soil compaction coincide, which accelerates the pile body formation. On the one hand, the energy of each discharge can be reduced when the repetition frequency of discharges is increased, but their total energy is ensured, which is sufficient to destroy the soil structure and to compact the soil. On the other hand, with a high repetition rate of discharges, every next discharge takes effect under conditions of unfinished soil compaction, which are caused by filtration properties of the soil, which determine the rate at which water is released. As a result, the effectiveness of each discharge decreases and the energy expenditure for pile production increases. For example, with an initial value of the number of pores in a soil of 0.690, the compression effect of a discharge is reduced 9-fold when the repetition frequency of discharges increases from 0.09 Hz to 6 Hz. The change in the repetition frequency of discharges enables the pile manufacturing speed to be regulated in a very wide range. It is not recommended to reduce the repetition frequency of discharges below 0.05 Hz because the time it takes for a pile body to form is comparable to the setting time of a setting building material. In this case, the effects of the discharges have negative consequences for the formation of a building material structure when setting, which reduces the load-bearing capacity of a pile. The upper limit of the repetition frequency of discharges is given by the possibilities of a current pulse generator.

wobei

r

Pfahlsollradius in einer gegeben Tiefe bedeutet.

In the embodiment variant of the invention under consideration, the pile is produced in a pilot borehole 1. In accordance with another variant of the pile production, a floor serves as the area of formation of the pile, ie the pile is produced directly in the floor without drilling the borehole. In this case, the tool 2 (FIG. 2) is introduced into the ground to a depth of 0.3 to 0.5 m by any known method, for example turning bores or indentation, and a setting building material 6 is introduced, such as it is described above, wherein a bottom section is wetted and generates in this section electrical high-voltage deposits in a number which allows the upper section of a pile to be formed with a nominal diameter. Then the tool 2 is moved to the ground depth with a step Δh, which is determined according to the ratio (6) or (7) depending on the shape of the pile to be produced. Since the building material 6 is fed into the ground, the number n of discharges is greater than that when the building material is fed into the borehole and is determined by a ratio

in which

r

Target pile radius at a given depth means.

When a depth h is reached, which is equal to the pile length, the tool 2 is pulled out and, if necessary, a fitting is inserted into the pile. In the manufacture of a pile, a throughput of the building material is set so that the building material 6 comes to coincide with the upper part of the pile.

In contrast to the variant of pile production in the borehole, an additional increase in the load-bearing capacity of a pile is achieved in this case in that no ground lifting takes place when a borehole is drilled and the pile is shaped by expanding the floor "from zero" to the target radius of the pile. In addition, an undoubted advantage of pile manufacturing in the ground is a gain in terms of material and time, that no borehole should be drilled.

As with the manufacture of the pile with the radius that varies in length in the borehole, the number of pulses cannot be changed when the tool 2 moves, but the pulse repetition frequency can be changed in accordance with the specified law of changing a pile radius over the pile length. The considerations set out above regarding the choice of the discharge energy and the repetition frequency of discharges also apply if a pile is produced directly in the ground.

wobei

d

maximales Querschnittsmaß des Werkzeugs, mm und

f

Bodenfestigkeitszahl nach Protodjakonow bedeuten.

The manufacture of piles in the ground "from top to bottom" is useful when strengthening the foundations of existing buildings and structures if there are cavities and caverns under a foundation that are formed by the action of groundwater. Another way of making piles in the ground is possible, which is to be preferred when installing intermediate supports in the basements of the buildings and structures to be reconstructed or when establishing new foundations when building buildings and structures. According to this variant of the invention, the tool 2 (FIG. 3) is lowered into the ground and an electrically conductive building material 6 is fed in, producing electrical high-voltage discharges in the ground. However, one chooses a discharge energy in such a way that each discharge creates a funnel with a radius below the lower end of the tool 2 which is approximately equal to a diameter half of the tool 2. This funnel formation under the lower end of the tool 2 facilitates its penetration into the ground - the tool 2 lowers itself into the ground or is pressed into it by a small force. So that an independent penetration of the tool 2 is ensured in the ground, the energy quantity W 1 should be a discharge

in which

d

maximum cross-sectional dimension of the tool, mm and

f

Soil strength number according to Protodjakonow mean.

The repetition frequency of discharges is selected so that the required plunge speed V of the tool is guaranteed:

The speed V is given in the ratio (13) in m / h.

bestimmt wird, wobei

W

Energie einer Entladung auf einem Schritt, J bedeutet.

After a depth has been reached which corresponds to the full pile length, a pile is placed as described above, but from the bottom upwards, by lifting the tool 2 (FIG. 4) in increments of Δh, the number n of Discharges on every step through the ratio

is determined, whereby

W

Energy of a discharge on one step, J means.

In this case, the pile is made from its sole to the head, while the supply of building material and the generation of discharges during the tool transport to the place where the pile sole is formed is only for the purpose of reducing the ground resistance to the downward movement of the tool.

The tool for pile production contains a tube 3 (FIG. 5) for the supply of setting building material and an electrical discharge device with electrodes 10 and 11 which are arranged coaxially and displaced relative to one another along their axis. The tube 3 consists of several sections, which are added when the tool is immersed in a borehole or in the ground; 5 shows the end of the lower section of the tube 3. The electrode 10, which is the upper one in the operating position of the tool, is as a ring which is screwed onto a metal sleeve 12 and the lower electrode 11 as a cone with one large cone angle executed, the tip of which points downwards. This version of the lower electrode 11 makes it easier to immerse tools in the ground, but it is not an obligatory one; the lower electrode can be designed as a flat disk or as a ring. As a whole with the lower electrode 11, a current-carrying rod 13 is embodied, which runs along the axis of the discharge device inside the sleeve 12 and is connected to the central wire of a coaxial cable 14, which is connected to the one connection of a current pulse generator (not shown) . The cable 14 should have a length which allows a tool to be immersed in a desired depth which corresponds to the length of a pile to be produced. A space inside the sleeve 12, the current-carrying rod 13 to the lower electrode 11 and a section of the cable 14 connected to the rod 13 are filled with an insulating material, for example polyethylene, whereby an insulating rod 15 is formed. The diameter of this rod 15 is smaller than the diameter of the electrode 11, for example by 8 to 10 mm, so that a space between the lower end face of the electrode 10 and an annular peripheral portion of the upper surface of the electrode 11, which protrudes over the rod 15, one Electrode spacing 16 forms.

The upper electrode 10 is welded to the end of the tube 3, a distance between an outlet opening 17 of the tube 3 and the lower electrode 11 is not less than the electrode spacing 16. Another connection of the tube 3 to the electrode 10 is conceivable, e.g. the tube 3 can be screwed into this electrode. In this case, when the electrode distance 16 is set, the tube 3 can be separated from the electrode 10 beforehand by moving the electrode 10 in the sleeve 12, which simplifies the preparation of the tool for operation.

The tube 3 is electrically connected to the braided shield of the coaxial cable 14, which is connected to another connection of the current pulse generator, which is connected to its housing. So that stresses between the electrodes 10 and 11 in the event of discharges do not loosen the fastening of the current-carrying rod 13 in the insulating rod 15, the current-carrying rod 13 has annular projections 19.

In the lower part of the tube 3, a check valve 19 is arranged next to its outlet opening 17, which prevents soil penetration into the tube 3. This function can exercise a fender instead of the valve 19, which is attached to the tube 3 below its outlet bore.

The electrode 10 and the electrode 11 with the current-carrying rod 13 are made of a tough steel to harden the surface layer in order to reduce the metal removal from surfaces of the electrodes during the discharges.

The tool is brought into the vertical position, for example in a drilling device (not shown), in that the pipe 3 is clamped in the rotating device of this device. By moving the electrode 10 in the sleeve 12, a required electrode spacing 16 is set, which ensures the conversion of the electrical discharge energy into mechanical work with the greatest efficiency. If the pile is produced in a borehole, the tool is lowered onto the bottom of the borehole, the pipe 3 being added by sections when it is lowered. When the bottom of the borehole is reached, the cable 14 is connected to the output of a current pulse generator and the pipe 3 to a mortar pump (not shown). Via the pipe 3, a binding building material is supplied under pressure to the bottom of the borehole and at the same time the generator is switched on, which applies current pulses to the electrodes 10 and 11. High-voltage discharges occur in the electrode spacing 16, which expand the lower borehole section, which is filled with the setting building material, and anchor and compact the soil around this section. After a pile section is made, the tool is gradually moved up. A tool movement is monitored, for example, on the basis of markings which are applied to the pipe side surface or on the feed plate of the rotary device of the drilling device.

If the pile is made in the ground, push the tool into the ground to a depth of 0.3 to 0.5 m and make the pile in the same way by moving the tool to the ground.

6 shows experimental data which show the change in soil strength around a pile 20 produced according to the invention. A distance 1 from the pile axis in meters is plotted on the diagram and a depth h in meters is plotted vertically. As can be seen from FIG. 6, the area 8 of an anchored floor with a compressive strength R 0.4 to 1 MPa and the area of a compacted floor, consisting of three partial areas 21, 22 and 23 with values, have arisen around the pile 20 of the soil deformation module E of 480, 330 or 310 MPa. To the left of the diagram, which shows the pile 20 with the adjacent floor, an engineering-geological section of a place is shown, on which this pile was manufactured. The bottom layer 24 provides sand with an average grain size and a pore number e = 0.75, the bottom layer 25 - fine water-saturated sand (e = 0.72, E = 190 MPa), the layer 26 - dust-like sand (e = 0.67, E = 150 MPa, angle φ of the internal friction of the soil 28 ^o , adhesion C = 0.04 kPa) and the layer 27 - fine water-saturated sand with the same characteristics as the layer 25. Below the layer 27 there is a moraine. A comparison of the key figures of the starting floor with the key figures of the floor that bears against the pile 20 shows that the load-bearing capacity of the floor around the pile and under its sole is increased by 1.5 to 3 times.

Concrete exemplary embodiments of the method according to the invention are given below.

example 1

Production of a section of a cylindrical pile with a diameter of 0.3 m and a length of 1 m in the water-saturated sandy soil with tool movement from top to bottom, as described for Fig.2.
Setting building material:
Cement mortar.
Intensity factor K of the storage of permanent soil deformations 0.54
Coefficient χ, which depends on soil parameters: 0.00163
Maximum cross-sectional dimension of the tool: 0.09 m
Cement mortar throughput: 2.3 m³ / h
Discharge energy: 50 kJ
Discharge repetition rate: 1 Hz
Number of steps: 14
Step size: 0.071 m
Discharge number per one step: 16
Time to make a pile section on one step: 0.0044 n
Time to manufacture a pile section with a length of 1 m: 0.062 h.

Example 2

Production of a tapered pile section with a minimum diameter of 0.3 m, a length of 1 m and a taper angle of 14 ^o in the dense clay soil by moving the tool from bottom to top, as described for FIGS. 3 and 4.
Setting building material: sand cement mortar.
Intensity factor K of the storage of permanent soil deformations: 0.07
Coefficient χ, which depends on soil parameters: 0.00302
Maximum cross-sectional dimension of the tool: 0.09 m

A. Dipping tools into the ground to a depth of 1 m

Discharge energy: 33.34 kJ
Discharge repetition rate: 0.18 Hz
Stress on the tool for its immersion: 1 kN speed of the tool immersion: 40 m / h
Tool immersion time: 0.025 h

B. Tool movement upwards

Discharge energy: 50 kJ
Discharge repetition rate: 1 Hz
Number of steps: 6
The table below contains other data. Step no. Pile diameter at a given depth, m Step size, m Number of discharges per step Manufacturing time of a pile section on one step, h 0 0.3 0.13 3rd 8.3x10⁻⁴ 1 0.33 0.14 4th 1.1x10⁻³ 2nd 0.36 0.16 5 1.4x10⁻³ 3rd 0.4 0.17 7 1.94x10⁻³ 4th 0.44 0.19 11 3.1x10⁻³ 5 0.49 0.21 18th 5.0x10⁻³ 6 0.54 31 8.6x10⁻³

Example 3

Production of a cylindrical pile section with a diameter of 0.4 m, a height of 1 m in a pilot borehole with a diameter of 0.13 m and a depth of 1 m, which was carried out in a clayey soil. The pile was made as described for Fig.1.
Setting building material: sand cement mortar
Intensity factor K of the storage of permanent soil deformations: 0.7
Coefficient χ that depends on soil properties: 0.00302 Maximum cross-sectional dimension of the tool: 0.09 m
Sand cement mortar throughput: 2.02 m³ / h
Discharge energy: 50 kJ
Discharge repetition rate: 1 Hz
Number of steps: 12
Step size: 0.087 m
Number of discharges per one step: 16
Manufacturing time of a pile section on one step: 0.0044 h
Manufacturing time of a pile section with a length of 1 m: 0.062 h.

Although the production variants of the invention described deal with the manufacture of a cylindrical and a conical pile, it goes without saying that the invention also applies to the manufacture of piles of other shapes, e.g. Stepped profile piles (i.e. piles consisting of several cylindrical sections with different diameters), which are expedient to manufacture in a floor, the one or more layers of which have a greatly reduced strength, and which can be used by cylindrical-conical piles. In addition, a change in a pile radius over the pile length can be achieved not only by changing the number of discharges or the sequence frequency of the discharges during the tool movement, but also by regulating the energy of individual discharges. The change in the energy of discharges can also be combined with a change in their number or repetition frequency.

The possibility of producing piles of any profile depending on specific construction site conditions allows the load-bearing capacity of a pile to be controlled in its manufacture in accordance with physical-mechanical soil properties. Thanks to the anchoring and the compaction of the soil around a pile, the load-bearing capacity of the pile is achieved which is 5 to 6 times greater than that of a site pile manufactured according to the known method.

The invention also ensures a lowering or, if the pile is made directly in the ground, a complete elimination of the effort for drilling a borehole and makes it possible to dispense with the use of casing pipes and a clay rinse, i.e. reduce the number of operations, thereby reducing the time to manufacture a pile.

Industrial applicability

The invention can be used in the manufacture of pile foundations during the construction and reconstruction of buildings and engineering structures.

Claims (10)

A method for producing a pile by feeding a setting building material (6) into the pile formation area, characterized in that when a building material (6) is fed into the pile formation area, electrical high-voltage discharges are generated therein, the area (7) of the building material supply and the discharge generation being over the depth of the pile formation area is moved during the formation of a pile body and the total discharge energy is selected in a given depth of the pile formation area in such a way that an increase in the diameter of the corresponding section of this area up to the desired pile diameter is ensured at this depth. A method according to claim 1, characterized in that the setting building material (6) is fed to a pilot borehole (1) which represents a pile formation area. A method according to claim 1, characterized in that the setting building material (6) is fed directly to the floor, which represents a pile formation area. Method according to one of claims 2 or 3, characterized in that in the event that the pile is produced with a radius which can vary in length, the discharge number is changed during the movement of the area (7) of the building material supply and the discharge generation so that in Given a depth of the pile formation area, this number is directly proportional to the pile radius at this depth. Method according to one of claims 2 or 3, characterized in that, if the pile is produced with a radius which is variable in length, the sequence of the discharges is changed when the area (7) of the building material supply and the discharge generation is moved such that it at a given depth of the pile formation area to the target pile radius at that depth is directly proportional. Method according to claim 2, characterized in that the number n of discharges in a given depth of the pile formation area

is, where r target pile radius at a given depth, m, r _o radius of a pilot borehole, m W energy of a discharge at this depth, J K intensity factor of storage of permanent soil deformations and χ mean coefficient that depends on soil properties. Method according to claim 3, characterized in that the area (7) of the building material supply and the discharge generation is moved to the ground depth, the number n of discharges at a given depth

is, where r target pile radius at a given depth, m, W energy of a discharge at this depth, J, K intensity factor of storage of permanent soil deformations and χ mean coefficient that depends on soil properties. Method according to claim 3, characterized in that the area (7) of the building material supply and the discharge generation is moved into the soil depth and after a depth which corresponds to a desired pile length has been reached, the area (7) of the building material supply and the discharge generation is moved upwards is, it is determined an energy W₁ a discharge during the downward movement the area (7) of the building material supply and the discharge generation according to the ratio

in which d maximum cross-sectional dimension of a tool that ensures the supply of building materials and generation of discharge, mm and f means the soil strength number according to Protodjakonow, and the number n of discharges upon an upward movement of the area (7) of the building material supply and the discharge generation according to the ratio

in which W energy of a discharge at a given depth during the upward movement of the area of the building material supply and the discharge generation, J, r target pile radius at this depth, m, K intensity factor of storage of permanent soil deformations, χ coefficient, which depends on soil properties, and d mean the maximum cross-sectional dimension of a tool that ensures the supply of building materials and the generation of discharges. A method according to claim 4, characterized in that when producing a conical pile, the area (7) of the building material supply and the discharge generation is moved with a step Δh which is determined by the ratio

$$\text{Δh = r '(1-b) Sin {2 arctg [(1-b) tg}\frac{\text{α}}{\text{2nd}}\text{]} at r '>r''}$$

and

$$\text{Δh = r '(1-b) tg {2 arctg [(1-b) tg}\frac{\text{α}}{\text{2nd}}\text{]} at r '<r''}$$

is determined, whereby b permissible relative deviation from the target pile radius, χ Target angle of the pile cone and r 'and r''mean the target pile radius at the previous or next step. Tool for producing a pile with a tube for supplying a setting building material, characterized in that it additionally contains an electrical discharge device with coaxially arranged and mutually displaced electrodes (10, 11), the first (10) of which is ring-shaped and on an in its inner insulating rod (15) is attached and the other (11) is attached to the end of this rod and is connected to a current-carrying rod (13) which is arranged inside the insulating rod (15) and connected to the central wire of a coaxial cable (14) whose screen braid is connected to the first electrode (10), the diameter of the second electrode (11) being larger than the diameter of the insulating rod (15), the first electrode (10) with the end of the tube (3), whereupon its outlet opening (17) is rigid and is connected such that the axis of the first electrode (10) is parallel to the axis of the tube (3) and ei n The distance between the inlet opening (17) of the tube (3) and the second electrode (11) is not less than an electrode distance (16).

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