RU2150549C1 - Method and device for moulding of cast-in- place pile in ground - Google Patents

Abstract

FIELD: civil engineering, in particular, construction equipment intended for moulding of cast-in-place piles and production of floor bedding on ground. SUBSTANCE: the method includes operations in driving of a longitudinal cavity (bore-hole) in the vertical or inclined direction with a subsequent filling of it with a fixing mortar, for instance, with concrete one. The novelty of the invention is in the fact that before driving of the longitudinal cavity fixing mortar is injected about the longitudinal axis of the cast-in-place pile to be moulded, and then the cast-in-place pile is moulded in the ground zone being injected. The device for realization of the method has a percussion mechanism, expander, fixing mortar feeding pile-line. The novelty of the device is the fact that it is provided with radial protrusions projecting from the peripheral outline of the device. The radial protrusions have longitudinal ducts and lateral ducts communicating with them outcoming to the surface of the radial protrusions; the longitudinal ducts are connected to a pump feeding the injection mortar. EFFECT: enhanced efficiency of driving of bore-holes in grounds both with a high strength and low one. 9 cl, 11 dwg

Description

 The invention relates to the field of construction equipment and is intended for forming printed piles, strengthening slopes, creating bases for floors on the ground.

 A known method of forming concrete piles on and.with. 4311281, containing operations for screwing a lead rod into the ground with an unremovable perforated screw tip, filling the well with concrete mix through the annular space between the well wall and the bar, injecting the waterproofing concrete mixture at the same time, and then displacing the latter from the rod cavity with a sand-cement mortar. The design of the piles has an increased ability due to the implementation of its helical. Its disadvantage is the complexity of manufacturing. This is due to the emergence of large tangential forces, and when the leading rod is removed from the soil, the walls of the well are destroyed. In addition, the protrusions (indentations) in the soil are placed only along the helix, which occupies part of the surface area of the pile, and reduces its bearing capacity.

 The method of forming piles by pneumatic punchers is widely known (see, for example, the Instructions for the Installation of Packed Piles Using Pneumatic Punchers BCN6610-78. M. Ministry of Construction of the USSR, 1978, or A.S. 838003 USSR, 1972 "Method for manufacturing a stuffed reinforced pile", the essence of which is in the penetration of a longitudinal cavity (well) by radial compaction of the soil with a pneumatic punch followed by filling of the formed cavity with concrete mortar or a semi-dry mixture.Multiple penetration of the cavity with successive expansion of its diameter is possible, while the cavity after each penetration, it is filled with concrete mortar (mixture), or first the cavity in the soil is made of the required diameter, and at the end a single cavity is filled in. The disadvantages inherent in this method are as follows: When forming piles in relatively dense soils, large resistance forces arise from the soil This leads to a decrease in the rate of penetration and a decrease in the diameter of the formed wells, i.e., ultimately, the technological capabilities of the method under consideration are reduced. On the other hand, the large resistance forces arising affect the working body of the device for forming piles, which leads to high stresses in the structural elements. As experience shows, it is not yet possible to develop a percussion device having a large diameter expander and at the same time having great durability and performance.

 On the other hand, when drilling wells for subsequent formation of printed piles in weak soils, the walls of the well are not stable, the use of self-propelled shock devices is difficult, since there is no sufficient adhesion to the ground, which ensures its extraction from the well.

 A device for drilling holes in the soil with the subsequent expansion of its diameter by a.s. 241164 - known in construction as a pneumatic punch. It contains a cylindrical body, inside of which a striker moves reciprocating, striking either the front of the body or the rear, depending on the direction of movement of the device. The movement of the hammer and the device itself is controlled by an air distribution mechanism. An expander with conical and cylindrical surfaces is rigidly fixed to the body. The device is intended for driving wells in the ground and cannot be used to supply a fixing solution to the surrounding soil.

 A device for drilling holes in the soil according to the patent of Poland 41749, containing a percussion mechanism located in a cylindrical body. On the body there are protruding planes used to stabilize the direction of movement of the device. It is impossible to use a known device for supplying a fixing solution to the surrounding soil and it is not intended for this.

 The problem solved in the proposed technical solution is to increase the efficiency of well drilling in soils, both with increased strength and in weak ones.

This is achieved due to the fact that before penetrating into the soil of the longitudinal cavity, a fixing solution is injected around the longitudinal axis of the formable rammed pile, and then, in the injected ground zone, the rammed pile is formed. This sequence of operations allows you to simultaneously solve several problems, namely:
a) when forming a stuffed pile in strong soils, temporary softening of the soil is provided, i.e., during the formation of piles, the resistance forces become significantly less, which allows you to pass wells of larger diameter and at a faster speed;
b) in the case of pile formation in soft soils, when the well walls are unstable, the use of the proposed method allows the soil to be fixed in the vicinity of the longitudinal cavity, and then pass it. In other words, the proposed technical solution allows you to expand technological capabilities in the formation of printed piles in difficult soil conditions.

 It is advisable to drive a longitudinal cavity 5-8 hours after injection of the solution into the ground, i.e. after it begins to set, but before it acquires maximum strength. This sequence of operations allows you to pass a longitudinal cavity in soft soils, because by this time, the soil as a result of injection will begin to gain strength, which will exclude the possibility of destruction of the walls of the longitudinal cavity and at the same time, the strength of the soil will still be relatively small to create large resistance forces during penetration.

 It is advisable to drive a longitudinal cavity (well) in the soil before starting the setting of the solution. This operation allows you to soften the soil with moisture in the fixing solution, and to pass longitudinal cavities in strong soils, dramatically reducing the resistance force.

 It is advisable to form radial grooves emanating from the longitudinal cavity and displaced relative to each other around the circumference into which the fixing solution is then pumped. Such an operation allows the fixing solution to be injected into the soil to a greater depth while reducing the necessary hydrostatic pressure of the solution.

 It is advisable to drive a longitudinal cavity by radial compaction of the soil in the injected zone. Such an operation provides an increase in the efficiency of the molding process, because simultaneously fixing the soil and its compaction, which helps to achieve greater soil strength, and therefore increase the bearing capacity of piles. It is advisable to inject the fixing solution into the soil simultaneously with the passage of the radial grooves through the formed radial cavities. Such an operation increases the productivity of the process, because allows you to reduce the preparatory operations between the main and instead of two penetrations to carry out one.

 A device for implementing the proposed method of forming a packed pile in soil contains a self-propelled mechanism, an expander, a pipeline for supplying a fixing solution, while it is provided with radial protrusions extending beyond the peripheral contour of the device, and in the radial protrusions there are longitudinal channels and transverse channels communicating with them on the side surface of the radial protrusions, the longitudinal channels are connected to a pump supplying an injection solution. This design allows you to implement the proposed method of forming a printed pile in the ground.

 It is advisable to perform the transverse channels of the radial protrusions tangential, extending to the side surfaces of the radial protrusions. This embodiment of the device allows you to apply a fixing solution on both sides of the radial protrusions, which ensures uniform flow of the solution around the longitudinal cavity.

 It is advisable to carry out the transverse channels of the radial protrusions in the radial direction, facing the peripheral surface of the radial protrusions. This embodiment of the design of the device provides the supply of the fixing solution in the radial direction along the slip plane formed in the soil when forming the radial protrusions.

 The essence of the proposed method of forming a packed pile in the soil is that before the penetration of the longitudinal cavity (well), an injector 2 with holes 3 is inserted into the soil and the fixing solution is injected into the soil around the longitudinal axis of the molded printed pile, and then the packed pile is molded as shown in FIG. 1.

 It is possible to penetrate the longitudinal cavity 4 (Figs. 2-4) before setting the fixing solution (in the case of pile formation in dense soils) or after it setting until maximum strength is reached (in the case of pile formation in soft soils). In this case, it is possible to inject the fixing solution in the radial direction from the side of the longitudinal cavity or in the tangential direction with the formation of radial grooves 5 in this case (Fig. 9). The latter allows you to increase the radius of the fixed zone, without increasing the hydrostatic pressure in the injected solution. The final operation is to fill the longitudinal cavity 4 and grooves 5 (if any) with concrete 6 or concrete mixture (Fig. 6).

 The essence of the proposed method of molding in the soil of the printed piles is illustrated by the example of a specific application. Shown in: FIG. 1 injection of soil-fixing solution; FIG. 2 - a longitudinal cavity formed after removing the injector from the ground; FIG. 3 - well sinking by a percussion device (pneumatic punch); FIG. 4 - expansion of the well with a pneumatic punch with an expander; FIG. 5 - formed longitudinal cavity (well) with soil fixed around it; FIG. 6 - stuffed pile; FIG. 7 - device with radial protrusions; FIG. 8 is a view along arrow A of FIG. 7; FIG. 9 - operation for driving a longitudinal cavity and grooves; FIG. 10 - a device with channels located in radial protrusions; FIG. 11 is an embodiment of injection channels (view along arrow B of FIG. 10).

 A device for forming a printed pile contains a percussion mechanism. It can be placed on the surface (in Fig. 1, 7 it is used, but not shown) or immersed (Fig. 4, 9, 10). In the latter case, it is advisable to use a pneumatic piercer 7 with an expander 8. In this case, it is possible to use them together or only a pneumatic piercer 7 without an expander 8. The expander 8 is rigidly mounted on the housing of the pneumatic piercer 7, which usually has a cylindrical shape, which becomes conical in front. The radial ribs 9 can be fixed, for example, by welding on the injector 2 (Fig. 1) or on the expander 8 (Fig. 9). In the radial ribs 9 there are longitudinal 10 and transverse 11 channels (Figs. 7, 8, 10, 11) connected to each other and to the pump (not shown in the drawings), the latter being located on the surface and can be connected to the longitudinal channel by a hose 12. Transverse channels 5 can be directed in the radial direction (Fig. 9) or in the tangential (Fig. 11).

 The principle of work on the formation of printed piles.

 An injector 2 having holes (or slits) 3 is introduced into the soil 1 along the entire length over which it is embedded in the soil. Then the fixing solution is injected into the ground. The chemical composition of the solution can be any, in particular, it can be in the form of cement milk, bitumen emulsions, silicate-aluminum solution, etc. Usually in construction, cement-based fixing mortars are the most applicable and widely studied. Their physical properties are as follows. With the same expenditure of work on compaction, depending on whether compaction has begun immediately after the mixture has been wetted or after 3 to 5 hours have passed after the cement has been applied and the mixture has been moistened, materials can be obtained that differ from each other by a density of 1.1 or more times and by strength by 2 or more times (IM Shcheikhet, AF Tsarev "On the issue of optimal humidity and maximum density of cement-bonded cohesive soils." Materials for the VI All-Union meeting on fixing and compaction of soils ("Theory and methods of artificial improvement priming in various petrographic types). Because of the Moscow University, 1968).

 If the soil is relatively strong, then the injector 2 is removed from it while the longitudinal cavity (well) 4 remains with stable walls (Fig. 2). If it is necessary to mold a pile in unstable soft soils, it is necessary to wait a while for the fixing solution to begin to set (approximately 4 hours after injection), as a result of which the soil will acquire some strength sufficient for the walls of the longitudinal cavity to be stable 4. If a fixing solution based on cement, then 3 to 5 hours after injection, you can continue to work, while the soil has not yet acquired maximum strength, but also ceased to be unstable.

 The next operation is to extract injector 2 from the soil (depending, as described above, immediately after injection or after a few hours). As a result, a longitudinal cavity 4 is formed (Fig. 2). Then pass shock self-propelled device (pneumatic punch) 7 well 4 (Fig. 3). If a relatively powerful pneumatic piercer 7 is used or the soil has low strength, then an expander 8 can be used that is rigidly mounted on the pneumatic piercer 7 (Fig. 4). In this case, a well 4 will be formed with a diameter exceeding the diameter of the pneumatic punch body 7. Here and below, for convenience, a longitudinal cavity 4 will be understood to mean a small diameter well formed after the injector 2 is removed from soil 1, or a well with longitudinal grooves 5. Extension of the longitudinal cavity 4 (wells) to the desired diameter (Fig. 5) can be carried out due to several penetrations, that is, changing the diameters of the expander 8, sequential expansion of the longitudinal cavity (well) 4. Given that the soil 1 has however, a small strength (natural or achieved as a result of wetting it with an still not fixed solution) can form a well 4 at a relatively low cost of energy. In practice, this leads to the possibility of using relatively low-power percussion devices for the formation of large diameter wells at a high penetration rate, and these parameters can be varied. When driving a well 4, a radial compaction of the soil around its longitudinal axis is observed (Fig. 5) and the displacement of moisture in the radial and axial directions. The latter effect contributes to an increase in the fixing zone, while the simultaneous compaction and consolidation of the soil further contributes to an increase in its strength around the pile. The final operation is the filling of the formed well 4 with concrete and its compaction. The result is a molded pile (Fig. 6) with a fixed and compacted soil lying around and at the front end of the pile. All together forms a common system of a stuffed pile - an injected and compacted soil base that works as a unit.

 It is advisable to increase the efficiency of the process of forming a printed pile. This can be achieved due to the fact that the injection of the fixing solution into the soil 1 is carried out as far as possible in the radial direction from the longitudinal axis of the injector 2. In this case, the injector 2 is made with radial protrusions 9, fixed, for example, by welding, to a cylindrical pipe. The latter has channels (longitudinal 10 and transverse 11). The longitudinal channels 10 are connected to the channels 11 made in the radial protrusions 9, while they can go to the lateral surface of the radial protrusions in the tangential (Fig. 11) or radial directions (Fig. 7, 10). As the injector 2, a cylindrical element clogged from the surface (Fig. 7) with a special impact drive (not shown) can be used, or a self-propelled impact device — a pneumatic punch 7 (FIG. 9 - 11), which has radial protrusions, can be used 9, mounted on the surface of the expander 8. In these protrusions there are longitudinal 10 and transverse 11 channels connected by a hose 12 to a pump located on the surface (not shown in the drawings). The transverse channels 11 may also extend onto the radial or tangential lateral surfaces of the radial projections 9.

 When using the considered devices with radial protrusions 9 for the formation of longitudinal grooves 5 in the soil 1, the injection of the fixing solution into the soil will occur at a certain distance from the longitudinal axis of the printed pile. This will allow injecting the fixing solution at a greater distance from the longitudinal axis of the pile with the application of less hydrostatic pressure in the solution, because they will not need to push through a layer of soil near the injectors. With the direction of the mouth of the longitudinal channels 10 in the radial direction (Fig. 7, 10) to a greater extent, the solution will spread in the radial direction). In the case of the execution of the mouth of the transverse channels 11 in the tangential direction (Fig. 11), the fixing solution will spread to a greater extent around the formed printed pile. The injection of the fixing solution into the soil can be carried out simultaneously with the penetration of the well and grooves (Fig. 9), or on the reverse stroke of the device when it leaves the well 4. When the penetration of the fixing solution is carried out simultaneously with the injection, the shock impulses produced by the impact device contribute to a deeper penetration of the solution into the soil from the axis of the well surface being formed.

 The application of the proposed method and device for forming printed piles allows you to expand the technological capabilities of the process, because a stuffed pile interacts with a soil with great strength. In addition, the proposed technical solution allows the formation of a printed pile with greater productivity due to changes in the physicomechanical properties of the soil in the process of drilling a well. The reduction of the resistance force, achieved at the same time, helps to increase the durability of the actuator, especially the shock action, which is currently the most effective means for molding wells in the ground.

Claims (9)

 1. A method of forming a stuffed pile in the soil, including the operation of sinking a longitudinal cavity (well) in the soil in a vertical or inclined direction and then filling it with a fixing solution, for example concrete, characterized in that before fixing the longitudinal cavity, a fixing solution is injected around the longitudinal axis to be molded stuffed piles, and then in the injected soil zone molded stuffed piles.  2. A method of molding a packed pile according to claim 1 in a soil, characterized in that a longitudinal cavity is drilled 6-8 hours after injection of the solution into the soil, i.e. after it begins to set, but before it acquires maximum strength.  3. The method of molding in the soil of a stuffed pile according to claims 1 and 2, characterized in that the sinking of the longitudinal cavity in the soil is carried out before the setting of the injected solution begins.  4. The method of molding in the soil of a stuffed pile according to claims 1 and 2, characterized in that the penetration of the longitudinal cavity is carried out by radial compaction of the soil in the injected zone.  5. The method of molding in the soil of a stuffed pile according to claims 1 to 4, characterized in that they form radial grooves in the soil, emanating from the limiting cavity, displaced relative to each other in a circle into which the fixing solution is then pumped.  6. The method of molding in the soil of a stuffed pile according to claims 1 to 5, characterized in that the injection of the fixing solution into the soil is carried out through the moldable grooves and simultaneously with the sinking of the latter.  7. A device for implementing a method of forming a stuffed pile in soil containing a percussion mechanism, an expander, a pipe for supplying a fixing solution, characterized in that it is provided with radial protrusions extending beyond the peripheral contour of the device, while in the radial protrusions there are longitudinal and communicating with them transverse channels extending to the surface of the radial protrusions, the longitudinal channels being connected to the pump supplying the injection solution.  8. A device for implementing the method of forming in a soil a printed pile according to claim 7, characterized in that the transverse channels of the radial protrusions are tangential, extending to the side surfaces of the radial protrusions.  9. A device for implementing the molding method in the soil pile according to claim 7, characterized in that the transverse channels of the radial protrusions are made in the radial direction, facing the peripheral surface of the radial protrusions.

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