RU2771363C1 - Injection pile and the method for its installation - Google Patents

Abstract

FIELD: construction industry.

SUBSTANCE: inventions relate to construction, in particular to the injection pile and the method for erecting pile foundations and foundations in weak soils, and can be used in industrial and civil construction both in the construction of new buildings and structures and in the reconstruction of existing ones. The injection pile includes a hollow perforated injection tube with a conical tip at the end and cutting elements. The injection tube is placed inside the pile shell, which has a cone seal and a conductor at the lower end, which is a guide sleeve for centering the retractable part of the pipe during immersion. The cone seal is arranged at the point of transition from the diameter of the conductor sleeve to the diameter of the trunk of the pile shell. Screw blades or a multi-step spiral are used as cutting elements of the tip. Above the tip of the injection tube there is an expander made in the form of a sleeve put on the pipe, with chopping knives as cutting elements placed at the end of the sleeve along its circumference. The shell pile is also equipped with screw blades of the same pitch as the blade of the injection tube.

EFFECT: increase in the bearing capacity of the pile in weak soils.

10 cl, 6 dwg

Description

The invention relates to construction, in particular to methods for erecting piled foundations and foundations in soft soils, and can be used in industrial and civil construction, both in the construction of new buildings and structures, and in the reconstruction of existing ones.

The method and arrangement of telescopic screw piles with a retractable injection rod are used for soil cementation in order to form a support core in weakly bearing soils.

There are various ways of arranging injection piles and their structures.

A known method of drilling-injection piles, carried out without extracting the soil (application of the Russian Federation No. 2000117934/03, IPC E02D 5/34, E02D 5/44) soil compaction, in which it is performed by an impact tip that provides compaction only at the base of the well. Methods for erecting a stuffed pile (RF patents for inventions No. 1280084, IPC E02D 5/34, published on December 30, 1986 and No. 1656928, IPC E02D 5/34, published on December 15, 1993), in which sealing is performed by pressing a pipe with an annular expander, with simultaneous filling of the annular space with concrete mixture or sand after the pipe is removed. This method has the following disadvantages: no soil compaction due to shaft expansion, pile formation occurs with internal soil inclusions, which does not provide high soil and material bearing capacity, especially for horizontal loads.

A known method of erecting an injection pile using casing pipes (RF patent for the invention No. 2263745, IPC E02D 5/34, E02D 5/46, published 11/10/2005), in which a phased, along the length, injection of a hardening solution from the bottom up, lifting casing pipe and injection rod or leaving the latter as a reinforcement element in the pile body. The disadvantage of the known method is that it is difficult to remove the casing after injection of the solution, and it is also impossible to use in cramped conditions due to the use of overall machinery and equipment.

A known method of constructing a well without extracting soil (RF patent for the invention No. 2238366, IPC E02D 5/34, E02D 5/44, E02D 7/26, published 10/20/2004), in which the injector pipe is pressed with a tip consisting of a disk , the diameter of which exceeds the diameter of the injection rod and having cutting plates, from the action of which grooves are formed to expand the injection zone. In contrast to the proposed method, injection in the known method is carried out with the formation of a shaft of soil concrete for the entire height of the pile. The well-known patent has the following disadvantages: insufficient strength of piles in terms of material, since they consist of soil-concrete for the entire height of the pile, which is unacceptable for the perception of horizontal loads in the upper zone, lack of protection against possible slippage of the borehole walls, low manufacturability, since a large amount of time for layer-by-layer formation of the trunk, there is a need for overall equipment, the difficulty of using in cramped conditions.

The method according to the RF patent for invention No. 2550620 (IPC E02D 5/34, published on May 10, 2015) is the closest to the proposed technical solution in terms of the essential features and, accordingly, is taken as a prototype. According to this method, a well is constructed without extracting the soil by pressing a perforated injector pipe into the soil with a conical tip fixed from below, consisting of a disk, the diameter of which exceeds the diameter of the injector pipe, and cutting plates. A hardening solution is injected into the injector pipe under pressure, filling the arranged well, the wellhead is plugged, and when the conical tip reaches the design mark and the injection is completed, the injector pipe with the conical tip is left in the well. An injector pipe with a perforated lower part is pressed into the soil, the injection of the hardening solution is carried out simultaneously with the indentation of the injector pipe, and step by step from top to bottom as the lower perforated part of the injector pipe is immersed in the indentation process. The wellhead is plugged before injection of the hardening solution immediately after the conical tip of the injection pipe is pressed into the soil. At the first stage, additional protection is provided against the exit of the injected hardening solution, for example, using a casing put on the perforated part of the injection pipe and installed above the plugging device, and after immersing the perforated part of the injection pipe into the ground at the first stage and filling the well with hardening solution to a height the perforation zones additionally expand the resulting pile shaft by additional injection of a hardening solution under pressure. Then the injection pipe is again pressed to the height of the perforation zone with simultaneous injection of the hardening solution and subsequent additional expansion of the resulting pile shaft. Then, the operations for forming the pile shaft at each subsequent stage of immersion of the injection pipe to the height of the perforation zone are repeated again in the same sequence until the conical tip of the design mark is reached.

The well-known patent has the same disadvantages as the previous technical solutions, namely, it requires the use of large-scale equipment, so it cannot be used in cramped conditions, there is no protection against possible well wall slippage, low manufacturability, since a lot of time is spent on layer-by-layer formation of the wellbore .

The proposed solution differs from the previously published ones in the use of a telescopic type retractable part of the pile as an injection part, with the development of the necessary design solution. The creation of a load perception system, based on the core of the soil reinforced by injection, in combination with the load perception by the side surfaces of the shell pile, due to soil compaction when immersed by screwing, distinguishes the proposed solution from the known methods previously patented.

Thus, the technical problem in the area under consideration is the low bearing capacity of the screw pile in soft soils, as well as the impossibility of forming a support core due to soil compaction. The proposed technical solution allows solving the existing technical problem by increasing the bearing capacity of piles in soft soils in a technological way, without the need for additional operations. Additional operations are understood as: drilling, strengthening of the walls of the well, the use of casing pipes, reinforcement, the use of heavy, expensive machinery and equipment. Thanks to the proposed technical solution, a support core is formed from soil-concrete, increased in volume, surrounded by a layer of soil reinforced by plugging under the support cone of a screw pile (shell pile) filled with concrete.

The technical result consists in improving the technical characteristics of the proposed solution, namely, in increasing the bearing capacity of the pile in soft soils, due to the formation of a support core from soil concrete, the section increased in volume, surrounded by a layer of soil reinforced by plugging, and creating a reinforced structure of the pile itself.

The technical result is achieved by the fact that in the injection pile, which includes a hollow perforated injection pipe with a conical tip at the end and cutting elements, according to the invention, the injection pipe is placed inside the pile-shell with a cone seal at the lower end and a conductor, which is a guide sleeve for centering of the retractable part of the pipe during immersion, and the cone seal is arranged at the point of transition from the diameter of the bushing of the conductor to the diameter of the pile-shell shaft, helical blades or a multi-step spiral are used as cutting elements of the tip, there is an expander above the tip of the injection pipe, made in the form of a sleeve put on pipe, with grinding knives as cutting elements, placed at the end of the sleeve along its circumference, while the pile-shell is also equipped with helical blades of the same pitch as the injection pipe blade.

Additional features of the invention:

- pile-shell is made of metal;

- pile-shell is made of polymeric material;

- screw blades have 1.5-2 screw pitches;

- the tip is made cast or welded;

- perforation on the injection pipe is made only on the lower retractable part;

- chopping knives have a rectangular or trapezoidal shape;

- the conductor is connected by welding by means of radial plates with the shaft of the pile-shell made of metal;

- the conductor is glued to a pile-shell made of a polymeric material.

The technical result is also achieved due to the fact that in the method of arranging the injection pile described above, which includes plunging the pile without removing the soil by pressing the tip and injecting the hardening fixing solution through the injection pipe, according to the invention, at the first stage, simultaneous immersion is carried out by screwing the assembly kit, consisting of an injection pipe and a shell pile fastened to it to the design mark for placing the lower end of the shell pile, then the injection pipe and the shell pile are separated, and the injection pipe is screwed up to the design mark for placing its tip, the solution is injected through the injection pipe shaft into the voids loosened soil located below the sealing cone of the shell pile, until a failure to absorb the solution occurs, and after the injection process is completed, the shell pile is not removed, but filled with concrete and remains in the soil, as a pile with a broadened heel, while ohm, the injection pipe remains in the body of the screw pile as a reinforcement element.

The essence of the invention is illustrated by the following graphics, represented by the figures:

fig. 1, which shows the immersion of the assembly kit to the design mark of the lower edge of the shell pile, where 1 is the injection pipe; 2 - pile-shell; 3 - tip of the injection pipe; 4 - expander with chopping knives; 5 - conductor of the pile-shell; 6 - design mark of the lower end of the pile-shell; 7 - hole for connection with the seat of the gearbox; 8 - connection of the pile-shell and injection pipe; 9 - non-bearing bulk soil; 10 - weakly bearing soil;

fig. 2, which shows the immersion of the injection pipe, where: 11 is the design mark of the tip of the retractable injection pipe; 12 - perforated part of the injection pipe;

fig. 3, which shows the injection of soil (stage 3 "Filling the pile body with concrete"), where: 13 - trace of the blade (spiral) of the retractable pile; 14 - soil zone with improved characteristics; 15 - core made of soil concrete, compacted with excess pressure; 16 - concrete, sand concrete;

fig. 4 showing an injection pipe with a molded vane tip;

fig. 5 showing a spiral type welded tip injection pipe;

fig. 6, which shows an injection pipe with a paddle-type welded tip and a conical opener, where 17 are chopping knives.

In the injection pile, which includes a hollow perforated injection pipe 1 with a conical tip 3 at the end and cutting elements, the injection pipe is placed inside the pile-shell 2, screw blades and chopper knives 17 are used as cutting elements of the tip 3, the lower end of the pile-shell 2 has cone-shaped and equipped with a jig 5, which is a guide sleeve for centering the retractable part of the pipe when immersed, above the tip 3 of the injection pipe there is an expander 4, made in the form of a sleeve, put on the pipe, with chopping knives 17, placed around the circumference of the pipe, while pile-shell 2 is also equipped with helical blades. Pile-shell 2 is made of metal or polymeric material. Helical blades are made with a pitch of 1.5-2 propeller pitches or in the form of a multi-pitch spiral. Helical blades are used to create an axial force to overcome the reactive thrust of the soil when the pile is immersed and, in combination with grinding knives placed above the tip of the injection pipe at the end of the expander, are also cutting elements. Tip 3 is cast or welded with helical or spiral blades. Perforation on the injection pipe is made only on the lower retractable part. The chopping knives 17 may have a rectangular or trapezoidal shape.

In the method for installing an injection pile, which includes immersing the pile without extracting the soil by pressing the tip 3 and injecting the hardening fixing solution through the injection pipe, at the first stage, simultaneous immersion is carried out by screwing the assembly kit consisting of the injection pipe and the pile-shell 2 fastened to it to the design marks 6 for placing the lower support end of the pile-shell 2, then the injection pipe and the pile-shell 2 are separated, and the injection pipe is screwed up to the design mark 11 for placing its tip, the solution is injected through the trunk of the injection pipe into the voids of the loosened soil below the support cone of the pile-shell 2 before the failure to absorb the solution, and after the end of the injection process, the shell pile is not removed, but filled with concrete and remains in the ground, as a pile with a widened heel, the injection pipe remains in the body of the screw pile as a reinforcement element.

The screw tip 3 has a larger diameter than the diameter of the perforated injection pipe, which makes it possible to create an expansion chamber for receiving grouting slurry and creating an overpressure zone for injecting the injection mixture into the soil. After filling the expansion chamber and the voids in the zone of injection of the injection mixture with cement slurry, the core is expanded by additional injection of the hardening slurry under pressure. The injection of the solution into the voids of the soil continues until a failure occurs in the absorption of the solution (reducing the flow rate of the solution to 5-10 l / min at an overpressure of 0.1-0.5 MPa). The mixture injected under pressure fills all the free space in the ground, crushed by knives, which is formed in the joint of the tip 3 with the injection pipe, as well as the track 13 from the blades (spiral), forming, when setting, a core 15 of high-density soil concrete, surrounded by a zone reinforced during plugging soil. To prevent the "leaving" of the injection mixture during plugging and injection into the cavity of the main pile, the role of protection, as a casing, is performed by the pipe of the conductor 5, arranged in the cone of the tip of the main pile, or the cavity of the main pile is filled ahead of time with concrete. Upon completion of concreting the main pile shaft, the perforated injection pipe remains in the pile body as a reinforcement element.

Strengthening by cementation is carried out for dispersed, coarse-clastic and coarse- and medium-grained sands with a filtration coefficient of 50 ... 100 m / day.

Soils are predominantly fine-grained and silty sands, sandy loams, with a filtration coefficient of 0.3 and above m/day, are strengthened by injection with solutions based on finely dispersed cements with a plasticizer or soil silicization.

Cohesive soils - loams and clays, with a filtration coefficient of 0.3 and above m/day, are strengthened by injection of cement-clay mortars.

Before starting the immersion, the injection pipe 1 of the screw pile is connected to the pile-shell 2 in the assembly kit, fixed in the saddle of the twisting mechanism drive gearbox, and installed vertically in the design position. The immersion of the assembly kit at this stage is carried out by means of the blades (spirals) of both piles, while the soil is compacted along the side surfaces of the shell pile 2. Joint immersion is carried out up to the design mark 6 of the location of the lower end of the shell pile.

At this stage, the piles (see Fig. 2) are separated, and the inner injection pipe is lowered by means of the screw of the blade (spiral) of the tip 3 to the design mark 11 of the tip of the pipe. In this case, a well is formed larger than the diameter of the perforated part 12 of the injection pipe 1, as well as loosening the soil with knives 17 arranged at the junction of the screw tip 3 with the expander 4. As a result of lowering, a chamber with loosened soil is formed, prepared for filling with grouting slurry, into which the perforated part 12 of the injection pipe 1 extended from the conductor enters.

After filling the expansion chamber (see Fig. 3) and the voids in the zone of injection of the injection mixture with cement slurry, the core is expanded by additional injection of the hardening slurry under pressure.

The injection of the solution into the voids of the soil continues until a failure occurs in the absorption of the solution (reducing the flow rate of the solution to 5-10 l / min at an overpressure of 0.1-0.5 MPa). The mixture injected under pressure fills all the free space in the soil, crushed by the knives of the grinder, arranged in the docking point of the tip 3 with the perforated part 12 of the pipe 1, as well as the track 13 from the blades (spiral). In this case, after setting, a core 15 is formed from high-density ground concrete, surrounded by a zone reinforced during plugging of the soil. To prevent the “leaving” of the injection mixture during plugging and injection into the cavity of the main pile, the role of protection, as a casing, is performed by the pipe of the conductor 5, arranged in the cone of the tip of the shell pile, or the cavity of the main pile is filled ahead of time with concrete. Upon completion of concreting the shell pile shaft, the injection pipe 1 remains in the pile body as a reinforcement element, which makes it possible to construct a 2-level cap and rigidly connect the pile to the grillage.

Thus, thanks to the proposed technical solution, the bearing capacity of the pile in soft soils is increased due to the formation of a support core made of soil-concrete, the cross-section increased in volume and surrounded by soil reinforced by plugging, as well as due to the proposed design of the pile.

Claims (10)

1. Injection pile, including a hollow perforated injection pipe with a conical tip at the end and cutting elements, characterized in that the injection pipe is placed inside the pile-shell, which has a cone seal at the lower end and a jig, which is a guide sleeve for centering the retractable part of the pipe when immersed, and the cone seal is arranged at the point of transition from the diameter of the bushing of the conductor to the diameter of the pile-shell shaft, helical blades or a multi-step spiral are used as cutting elements of the tip, there is an expander above the tip of the injection pipe, made in the form of a sleeve put on the pipe, with chopping knives as cutting elements placed at the end of the sleeve along its circumference, while the pile-shell is also equipped with helical blades of the same pitch as the blade of the injection pipe. 2. Injection pile according to claim 1, characterized in that the pile-shell is made of metal. 3. Injection pile according to claim 1, characterized in that the pile-shell is made of a polymeric material. 4. Injection pile according to claim 1, characterized in that the helical blades have 1.5-2 screw pitches. 5. Injection pile according to claim 1, characterized in that the tip is cast or welded. 6. Injection pile according to claim 1, characterized in that the perforation on the injection pipe is made only on the lower retractable part. 7. Injection pile according to claim 1, characterized in that the chopping knives have a rectangular or trapezoidal shape. 8. Injection pile according to claim 1, characterized in that the conductor is connected by welding by means of radial plates with a pile-shell, 9. Injection pile according to claim 1, characterized in that the conductor is connected to the pile-shell with an adhesive joint. 10. The method of arranging an injection pile according to claim 1, including immersing the pile without extracting the soil by pressing the tip and injecting a hardening fixing solution through the injection pipe, characterized in that, at the first stage, simultaneous immersion is carried out by screwing the assembly kit, consisting of an injection pipe and a fastened shell piles with it to the design mark of the lower end of the shell pile, then the injection pipe and the shell pile are separated and the injection pipe is screwed up to the design mark of its tip placement, the solution is injected through the injection pipe shaft into the voids of the loosened soil located below the cone compactor shell piles, before the failure of the absorption of the solution, and after the end of the injection process, the shell pile is filled with concrete and left in the ground as a pile with a widened heel, the injection pipe is left in the body of the screw pile as a reinforcement element.

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