CN116427396A

CN116427396A - Stirring pile construction method and composite pile construction method thereof

Info

Publication number: CN116427396A
Application number: CN202210001351.9A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Zhejiang Hejian Building Materials Co ltd
Current assignee: Zhejiang Hejian Building Materials Co ltd
Priority date: 2022-01-04
Filing date: 2022-01-04
Publication date: 2023-07-14

Abstract

The invention belongs to the field of soft soil foundation treatment, and particularly relates to a stirring pile construction method, which comprises the steps of drilling and spraying liquid, cutting and crushing soil underground at a preset pile position and simultaneously injecting liquid to a first preset depth position to form a stirring pile hole, and injecting dry concrete containing powder from the first preset depth position of the stirring pile hole until the dry concrete reaches a second preset depth position in the step of powder concrete pile forming to form a stirring pile body, so that the water content in the stirring pile hole is effectively reduced, the pile body strength is rapidly improved, and the bearing capacity of the soft soil foundation is effectively improved. The invention also provides a composite pile construction method, which comprises the stirring pile construction method, and further comprises a pile planting step carried out after the powder concrete pile forming step, wherein a precast pile is inserted into the stirring pile to a preset depth before the stirring pile is not solidified, and the composite pile remarkably improves the mechanical bearing performance of the soft soil foundation and provides stronger support for a building on the composite pile.

Description

Stirring pile construction method and composite pile construction method thereof

Technical Field

The invention relates to the field of soft soil foundation treatment, in particular to a stirring pile construction method and a composite pile construction method thereof.

Background

Because the bearing capacity of the soft soil foundation is weaker, the construction requirement of a building can be met on the soft soil foundation by carrying out reinforcement treatment on the soft soil foundation, the cement mixing pile is a common method for reinforcing the soft soil foundation, the cement mixing pile construction is divided into wet construction and dry construction according to different media sprayed to soil, because the water content of the soft soil foundation is higher, if the wet construction is adopted, normal cement slurry mixing ratio is adopted, cement slurry and the soft soil are sprayed into the soft soil for forced mixing, the water content of the soft soil can be increased instead, the pile body strength is slowly increased, the construction period is long, the cement soil strength after consolidation is lower, the single pile bearing capacity of the pile formed by the cement mixing pile is very low and even the pile cannot be formed, if the soft soil foundation is treated by adopting the dosage of the cement slurry, the construction cost is high, the economical efficiency is poor and the soil solidification effect is poor, so that a person skilled in the field places the research center on the dry construction. The existing dry construction is usually cement powder as a medium sprayed to the soil body, and the strength of the pile body of the stirring pile formed by mixing the cement powder with the soil body is low, so that the bearing capacity of the foundation is poor, and the requirement of high-rise building construction on the foundation with high bearing capacity cannot be met.

Disclosure of Invention

The invention aims to provide a construction method of a stirring pile, which is characterized in that dry concrete materials are injected into pile holes of the stirring pile to be mixed with slurry, so that the water content of a pile body is effectively reduced, the strength of the pile body is rapidly improved, and the stirring pile with high strength is obtained.

Another object of the present invention is to provide a composite pile construction method, in which a precast pile is inserted before a stirring pile formed by the above stirring pile construction method is consolidated to form a soft soil foundation having a high bearing capacity.

In order to achieve the above object, the present invention provides a method for constructing a stirring pile, comprising:

drilling and spraying liquid: cutting the crushed soil body underground at a preset pile position and forming a stirring pile hole along with injecting liquid to a first preset depth position;

piling the powder concrete: and injecting dry concrete containing powder from the first preset depth position of the pile hole of the stirring pile until the dry concrete rises to the second preset depth position, so as to form the pile body of the stirring pile.

Further, the method also comprises a pile head hole manufacturing step before the drilling and spraying step; in the pile head hole manufacturing step, excavating soil at the top of a preset pile position to form a pile head hole for temporarily storing slurry, wherein the cross section area of the pile head hole is larger than that of a stirring pile hole; and the bottom of the pile head hole is positioned above or flush with the second preset depth position, and/or a steel member or a prefabricated member is adopted to manufacture the retaining wall structure of the pile head hole.

Further, the method also comprises a stirring pile body re-stirring step which is synchronously carried out with or is carried out subsequently to the powder concrete pile forming step; in the stirring pile body re-stirring step, stirring equipment is adopted to uniformly stir the dry concrete material and part of liquid in the pile hole of the stirring pile.

Further, in the step of drilling and spraying liquid, a chain drill is adopted to manufacture a stirring pile hole with a rectangular cross section; the chain drill is connected with the pile machine by a telescopic drill rod or an extension drill rod.

Further, the chain drill comprises a slurry conveying pipeline for injecting liquid and a material conveying pipeline for injecting dry concrete materials; in the drilling and spraying step, the slurry conveying pipeline is conducted, and the slurry conveying pipeline is closed; in the step of piling the powder concrete, the material conveying pipeline is communicated, and the slurry conveying pipeline is closed.

Furthermore, in the step of forming the powder concrete pile, a material injection pipe is adopted to extend into the bottom of a pile hole of the stirring pile, then dry concrete is injected, and the material outlet of the material injection pipe is lifted or intermittently lifted while being injected, and the material injection pipe is of an extension pipe or telescopic sleeve structure.

Further, when the discharge hole of the material injection pipe is lifted to a second preset depth position, the injection of the dry concrete material is stopped; and/or injecting gas while the injection pipe is lifted; and/or, the inner aperture of the material injection pipe is greater than or equal to 9.9 cm.

Further, the dry concrete material comprises powder and particles, wherein the particles comprise sand aggregate and/or recycled aggregate; wherein the particle size of the powder is less than or equal to 100 microns; the particulate matter includes fine particulate matter having a particle diameter of 4.75 mm or less and coarse particulate matter having a particle diameter of 40 mm or less.

Further, in the step of forming the powder concrete pile, a slurry pump is adopted to suck and discharge slurry in a pile hole of the stirring pile above a second preset depth position.

In order to achieve the above purpose, the invention also provides a composite pile construction method, comprising the stirring pile construction method, and further comprising the following pile planting step of the powder concrete pile forming step, wherein a precast pile is inserted into the stirring pile to a preset depth before the stirring pile is not solidified; the cross section shape of the stirring pile is the same as that of the precast pile; and/or the cross section shape of the stirring pile and the cross section shape of the precast pile are regular polygons.

Compared with the prior art, the invention has the following beneficial effects:

in the drilling and spraying step, the crushed soil body is cut underground at a preset pile position, and a stirring pile hole is formed along with the injection of liquid to a first preset depth position, so that the liquid substances in the stirring pile hole can ensure that the soil body flows fully and is uniformly mixed, and the soil body can be crushed and uniformly stirred. In the powder concrete pile forming step, dry concrete materials containing powder are injected from the first preset depth position of the stirring pile hole until the powder is lifted to the second preset depth position, so that a stirring pile body is formed, the dry concrete materials are injected into the stirring pile hole through a dry construction method, the water content in the stirring pile hole is effectively reduced, the strength of the pile body is rapidly improved, the mechanical bearing performance of a soft soil foundation is improved, the aggregate plays a role of a skeleton and filling pores in cement soil, the compactness and strength of the soft soil foundation are increased, and the bearing capacity of the soft soil foundation is effectively improved.

Drawings

Fig. 1 is a schematic view of a construction flow of a stirring pile according to a first embodiment of the present invention;

FIG. 2 is a schematic illustration of a drill bit spray step;

FIG. 3 is a schematic diagram of a powder concrete piling step;

fig. 4 is a top view of a composite pile.

In the accompanying drawings: soil body 1; a stirring pile hole 2; a filling pipe 3; a discharge port 31; a slurry pump 4; pile head hole 5; a retaining wall structure 6; stirring piles 7; precast piles 8; a chain drill 9; a telescopic drill rod 91; a movable plate 10; a telescopic member 11; a first depth position a; a second depth position b.

Detailed Description

In order to better understand the aspects of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and detailed description.

In the present specification, the terms "upper, lower, inner, outer" and the like are established based on the positional relationship shown in the drawings, and the corresponding positional relationship may be changed according to the drawings, so that the terms are not to be construed as absolute limitation of the protection scope; moreover, relational terms such as "first" and "second", and the like, may be used solely to distinguish one element from another element having the same name, without necessarily requiring or implying any actual such relationship or order between such elements.

Example 1

As shown in fig. 1 to 4, the method for constructing a stirring pile disclosed in this embodiment is suitable for reinforcement treatment of a soft soil foundation, and obtains a stirring pile with high strength, and includes a drilling and spraying step and a powder concrete pile forming step, wherein the drilling and spraying step is located before the powder concrete pile forming step.

As shown in fig. 2, in particular, the drilling and spraying step: the method comprises the steps of cutting and crushing soil bodies 1 underground at preset pile positions, and forming a stirring pile hole 2 along with injecting liquid to a first preset depth position a, wherein the liquid substance in the stirring pile hole 2 can ensure that the soil bodies are fully and uniformly flowed and crushed, the stirring pile hole 2 is formed by adopting a chain drill 9 in the embodiment, the chain drill 9 is connected with a pile machine (not shown in the figure) by adopting a telescopic drill rod 91 or an extension drill rod, the chain drill 9 is convenient for downwards drilling the preset depth of a soft soil foundation by adopting the chain drill 9, the chain drill 9 comprises a slurry conveying pipeline (not shown in the figure) for injecting liquid, the liquid can be water or liquid mixed with one or more substances of mud, cement, a gelling agent, an adhesive, a curing agent and an expanding agent in the water, the liquid injected in the embodiment is preferably cement slurry, and the cement slurry can be used as a cementing material to greatly improve the pile body strength of the stirring pile. Of course, in order to reduce the material cost, the water or slurry may be injected liquid, while satisfying the basic requirement of being convenient for cutting and stirring the soil body uniformly.

Specifically, when the chain drill 9 is vertically inserted into a stratum, the chain drives the cutter to vertically rotate, raw soil is stirred and mixed, liquid is injected, the drilling resistance is reduced, the refinement and flow of soil are accelerated, and then the chain drill 9 is used for manufacturing the stirring pile hole 2 with the rectangular cross section. Of course, in other embodiments, a double milling wheel stirring device, a stirring drill rod set, a mixing square hole device such as a lyo Fang Kongzuan device and the like may be used to manufacture a mixing pile hole with a rectangular cross section, and a rotary drilling machine, a spiral drilling machine and the like may also be used to manufacture a mixing pile hole with a circular cross section.

As shown in fig. 3, the powder concrete piling step: and (3) injecting dry concrete containing powder from the first preset depth position a of the stirring pile hole 2 until the dry concrete rises to the second preset depth position b, so as to form a stirring pile body. The dry concrete material is injected into the soil body 1, so that the water content of the soil body 1 in the pile hole 2 of the stirring pile can be effectively reduced, the pile body of the stirring pile is solidified, the strength of the stirring pile is improved, meanwhile, the dry concrete material contains aggregate, the aggregate plays a role in forming a framework and filling pores in the soil body 1, the compactness and strength of a soft soil foundation are improved, the pile body strength is rapidly improved, the bearing capacity of the soft soil foundation is further effectively improved, the mechanical property of the soil body 1 is improved, and the foundation settlement is reduced.

In this embodiment, the dry concrete material includes powder and particles, which are used as main agents of the dry concrete material, wherein the powder includes one or more of cement powder, fly ash, lime, gypsum powder, stone powder, ceramic powder, slag powder, coal slag powder, steel slag powder, silica fume, plant ash, the particles include sand stone aggregate and/or recycled aggregate, the sand stone aggregate includes crushed stone, sand, slag, pebbles, bricks and tiles, and the recycled aggregate mainly refers to waste concrete or masonry material; wherein, the grain diameter of the powder is less than or equal to 100 micrometers; the particulate matter includes fine particulate matter having a particle diameter of 4.75 mm or less and coarse particulate matter having a particle diameter of 40 mm or less.

Of course, the dry concrete includes, in addition to the above main agents, auxiliary agents such as water absorbing agents or water removing agents for accelerating the absorption of moisture in the soil and improving the water absorbing effect, such as swelling resin, water absorbing resin, soaping slag, diatomaceous earth, etc., exciting agents for catalyzing the reaction between the components, exciting the activity of the mixed material, such as alkali exciting agents such as sodium hydroxide, sodium silicate, magnesium oxide and calcium oxide, and reinforcing exciting agents such as halogen salts, sulfate salts, aluminate salts, etc., dispersing agents for better dispersing the water absorbing agents in the sludge particles, such as polyethylene wax, reinforcing agents for further exciting the hydration hardening reaction, increasing the curing compactness, such as one or more of kaolin, calcium chloride, aluminum chloride, water glass, glass fiber, calcium acetate, triisopropanolamine, sodium formate, potassium nitrate, etc.

Because the density is different, the powder and the dropping speed of different particles are different when the dry concrete material is downwards injected, and the dry concrete material can be added with sticky auxiliary agents when being stirred, so that the powder is uniformly attached to the surface of the particles as much as possible, the powder in the dry concrete material is uniformly distributed when being injected into the pile hole 2 of the stirring pile, and the uneven distribution of the powder content in the dry concrete material injected into the pile hole 2 caused by the local accumulation of the powder is avoided, thereby indirectly causing the uneven strength of the pile body of the stirring pile. The auxiliary agent can be one or more of slag, silica fume or red mud, and can be other components capable of achieving the same or similar effects.

The components, proportion, mixing ratio and the like of the dry concrete material are comprehensively determined according to the factors such as the water content of the soft soil foundation, the soil condition, the construction requirement and the like. An example of each component and parts by weight of each component of the dry concrete is given as follows: 20-25 parts of sand: 20-40 parts of stone: 40-80 parts of water remover: 5-10 parts of reinforcing agent, 0.5-5.5 parts of exciting agent: 0.5-4.5 parts.

In the step of forming the powder concrete pile, as shown in fig. 3, a dry concrete material is injected after a material injection pipe 3 extends into the bottom of a pile hole 2 of the stirring pile, the dry concrete material is premixed uniformly before injection, and a discharge hole 31 of the material injection pipe 3 is lifted or intermittently lifted while being injected. When the discharge hole 31 of the injection pipe 3 is lifted to the second predetermined depth position b, the injection of the dry concrete is stopped, the dry concrete is prevented from overflowing out of the ground, and the waste of materials and the pollution of the surface environment are prevented.

The bottom of the side wall of the material injection pipe 3 is hinged or pin-jointed with a movable plate 10, the material injection pipe 3 is also connected with a telescopic piece 11, the extending end of the telescopic piece 11 is connected with the movable plate 10, the movable plate 10 is in a furled state in the process that the material injection pipe 3 is sunk to a first preset depth position a of a stirring pile hole 2, the movable plate forms an included angle of 0-10 DEG with the vertical axis of the material injection pipe 3, the whole stirring pile hole 2 is filled with grout, the movable plate 10 is in an unfolding state by driving the telescopic piece 11 in the lifting process of the material injection pipe 3, in order to enable the movable plate 10 to obtain a better drainage effect, the edge of the movable plate 10 is attached to the inner wall of the stirring pile hole 2 as much as possible or the gap is smaller, the movable plate 10 is used as a dry-wet boundary, the mixture of dry concrete material and grout is arranged below the movable plate 10 in the stirring pile hole 2, the stirring pile hole 2 is grout above the movable plate 10, the movable plate 10 is in the second preset depth position b in the lifting process of the material injection pipe 3, the grout in the stirring pile hole 2 is discharged to a second preset depth position b by the movable plate 10, so that the grout in the stirring pile hole 2 is pumped out by the slurry pump 4, and the water content in the stirring pile hole 2 is reduced.

In this embodiment, the telescopic member 11 adopts an air cylinder to realize the folding and unfolding of the movable plate 10, and of course, the telescopic member 11 can also adopt one or more combination structures of a hydraulic cylinder, a spring, a telescopic rod and a rope with elastic deformation or telescopic function, of course, a combination structure of the hydraulic cylinder and the spring can also be adopted, and of course, the telescopic member 11 can not be connected with the injection pipe 3, but can be only connected with the movable plate 10, so long as the two structures of folding and unfolding of the movable plate 10 can be realized, and the telescopic member can be selected according to specific construction conditions.

In order to further reduce the water content of the soil body 1 and shorten the consolidation time of the stirring pile 7, as shown in fig. 3, in the step of forming the powder concrete pile, slurry in the pile hole 2 of the stirring pile is pumped and discharged above the second preset depth position b by adopting a slurry pump 4, and redundant slurry in the pile hole 2 of the stirring pile is pumped out in time by the slurry pump 4, so that the consolidation efficiency of the stirring pile is improved, and the dosage of dry concrete is reduced. Optionally, the inner hole diameter of the material injection pipe 3 is larger than or equal to 9.9 cm, and preferably the inner hole diameter of the material injection pipe 3 is larger than 10.1 cm, so as to meet the requirement of injecting sand and aggregate into the soil body 1. And the inner wall of the material injection pipe 3 is provided with a wear-resistant coating, so that the service life of the material injection pipe 3 is prolonged.

As shown in fig. 3, in order to meet the requirement of injecting dry concrete material to a predetermined depth of the soil body 1, the applicability of the injection pipe 3 is improved, the injection pipe 3 is of an extension pipe or telescopic pipe structure, and when the injection pipe 3 is of an extension pipe, the extension pipe is formed by axially sealing, abutting and assembling more than two sections of injection pipes. Of course, the injection pipe can also be a telescopic pipe structure, the length of the injection pipe can be changed by axially reciprocating motion, and specifically, the injection pipe comprises an outer pipe, an inner pipe axially sliding in the outer pipe and a driving mechanism for driving the inner pipe to axially slide, and a sliding sealing device is arranged between the inner pipe and the outer pipe. Other structures capable of realizing the length change of the injection pipe through telescopic movement are also possible, no limitation is made here, and the specific structure of the injection pipe is specifically selected according to the actual construction situation. In this embodiment, the injection pipe 3 is of a telescopic sleeve structure, and the cross section of the injection pipe 3 is the same as the cross section of the peripheral pile hole 2, so that the dry concrete is uniformly distributed in the soil in the stirring pile hole 2. For example, the cross-sectional shape of the filling pipe 3 and the cross-sectional shape of the stirring stake hole 2 are both substantially square.

Example two

In this embodiment, the same reference numerals are given to the same parts as those of the first embodiment, and the same description is omitted.

In order to fully disperse the dry concrete into the pile hole 2 of the stirring pile, in the step of forming the powder concrete pile, the injection pipe 3 is lifted and gas is injected while the dry concrete is injected, the injected gas has the effect of stirring soil, the stirring uniformity of the dry concrete and the soil is increased, the dry concrete is injected into the pile hole 2 of the stirring pile from the discharge hole 31 of the injection pipe 3 in a spraying manner, the discharge hole 31 of the injection pipe 3 is prevented from being blocked, and the compactness of the pile body of the stirring pile can be improved.

Example III

The embodiment also comprises a stirring pile body re-stirring step which is synchronously carried out with or carried out after the powder concrete pile forming step, wherein in the stirring pile body re-stirring step, stirring equipment is adopted to uniformly stir the dry concrete material and part of liquid in the stirring pile hole 2, so that the stirring times and time are increased, the dry concrete material is uniformly distributed along the depth direction of the stirring pile body, the strength of the whole pile body of the stirring pile tends to be consistent along each part of the vertical and cross section, the uniformity of the pile body is good, the pile forming time of the stirring pile is shortened, the construction period is shortened, the dosage of the dry concrete material is reduced, the cost is saved, and the manufacturing cost is reduced. The stirring equipment adopts a chain drill 9, and other stirring equipment such as a double-wheel milling stirring device, a rotary drilling rig, a spiral drilling rig and the like can be adopted.

Example IV

The method further comprises a pile head hole manufacturing step before the drilling and spraying liquid step, wherein in the pile head hole manufacturing step, soil is excavated and taken out from the top of a preset pile position to form a pile head hole 5 for temporarily storing slurry, and the cross section area of the pile head hole 5 is larger than that of a stirring pile hole 2; the bottom of the pile head hole 5 is located above or flush with the second predetermined depth position b, the pile head hole 5 has a larger area, more slurry can be stored, and water or slurry stored in the pile head hole 5 can be timely pumped out by the slurry pump 4. The chain drill 9 cuts the crushed soil body 1 into the ground at the position of the pile head hole 5 and simultaneously injects liquid to the first preset depth position a to form the stirring pile hole 2.

In order to prevent the phenomenon of hole wall collapse or sand flow in the process of hole forming and pile forming, wall protection measures are added, and steel components or prefabricated components are adopted to manufacture the wall protection structure 6 of the pile head hole 5, so that the problem that the wall protection effect is poor due to the fact that the hole wall does not form a solid crust due to insufficient specific gravity of slurry or unsatisfactory performance indexes can be avoided, the construction is simple, the durability is realized, and the wall protection effect is good.

Example five

The difference between this embodiment and the first embodiment is that the manner of injecting the dry concrete into the pile hole 2 of the mixing pile is different, in this embodiment, the dry concrete is injected into the pile hole 2 of the mixing pile by using the conveying pipeline carried by the chain drill 9 instead of the injection pipe 3, specifically, the chain drill 9 further includes a conveying pipeline (not shown in the figure) for injecting the dry concrete, in the step of spraying the liquid into the mixing pile, the chain drill 9 gradually cuts the crushed soil 1 downward, while the conveying pipeline is conducted and the liquid is injected into the soil 1 while the chain drill 9 moves downward, at this time, the conveying pipeline is closed, in the step of forming the powder concrete, the chain drill 9 lifts while the soil 1 is cut, while the conveying pipeline is conducted and the dry concrete is injected into the pile hole 2 of the mixing pile while the chain drill 9 lifts, at this time, the conveying pipeline is closed. The dry concrete material is fully mixed with part of liquid in the pile hole 2 of the stirring pile by the cutting and stirring action of the chain drill 9, so that the purpose of re-stirring the pile body of the stirring pile is achieved.

In this embodiment, the step of forming the powder concrete pile and the step of re-stirring the pile body of the stirring pile are performed synchronously, and the chain drill 9 itself has a slurry conveying pipeline and a material conveying pipeline, so that the stirring can be performed while the dry concrete material is injected.

Example six

The embodiment provides a composite pile construction method, which comprises a stirring pile construction method and a pile planting step carried out after a powder concrete pile forming step, wherein the stirring pile construction method adopts any one of the methods in the embodiments 1 to 5 according to the actual condition of a soft soil foundation, and the pile planting step comprises the following steps: before the stirring pile is not consolidated, a precast pile 8 is inserted into the stirring pile 7 to a predetermined depth. As shown in fig. 4, the composite pile includes the stirring pile 7 as described above and the precast pile 8 inserted into the stirring pile 7, i.e., the precast pile 8 serves as an inner core and the stirring pile 7 serves as an outer core. The composite pile obviously improves the bearing capacity and stability of the soft soil foundation and provides stronger support for the building on the composite pile. The cross section shape of the stirring pile 7 is the same as that of the precast pile 8, so that the binding force between each side face of the pile body of the precast pile 8 and surrounding soil bodies 1 is the same, the pulling resistance and the bearing capacity of the precast pile 8 are improved, and the bearing capacity of the composite pile is improved. The cross section shape of the stirring pile 7 and the cross section shape of the precast pile 8 are regular polygons, for example, the cross section shape of the stirring pile 7 and the cross section shape of the precast pile 8 are approximately square, so that the mechanical bearing performance of the pile foundation is further improved, the pile planting mode can not model soil squeezing and floating soil effects, and engineering quality is ensured.

The stirring pile construction method and the composite pile construction method provided by the invention are described in detail above. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the core concepts of the invention. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims

1. The stirring pile construction method is characterized by comprising the following steps of:

piling the powder concrete: and injecting dry concrete containing powder from the first preset depth position of the stirring pile hole until the dry concrete rises to the second preset depth position, so as to form a stirring pile body.

2. The method of constructing a mixing pile according to claim 1, further comprising a pile head hole making step prior to said drilling and spraying step;

in the pile head hole manufacturing step, excavating soil at the top of a preset pile position to form a pile head hole for temporarily storing slurry, wherein the cross section area of the pile head hole is larger than that of a stirring pile hole;

and the bottom of the pile head hole is positioned above or flush with the second preset depth position, and/or a steel member or a prefabricated member is adopted to manufacture the retaining wall structure of the pile head hole.

3. A method of constructing a mixing pile according to claim 1 or claim 2, further comprising a mixing pile body re-mixing step carried out in synchronism with or subsequent to the powder concrete piling step;

in the stirring pile body re-stirring step, stirring equipment is adopted to uniformly stir the dry concrete material and part of slurry in the pile hole of the stirring pile.

4. The method for constructing the mixing pile according to claim 1 or 2, wherein in the step of drilling and spraying liquid, a mixing pile hole with a rectangular cross section is manufactured by adopting a chain drill;

the chain drill is connected with the pile machine by a telescopic drill rod or an extension drill rod.

5. A method of constructing a mixing pile according to claim 4, wherein the chain drill comprises a slurry pipe for injecting liquid and a material pipe for injecting dry concrete;

in the drilling and spraying step, the slurry conveying pipeline is conducted, and the slurry conveying pipeline is closed;

in the step of piling the powder concrete, the material conveying pipeline is communicated, and the slurry conveying pipeline is closed.

6. The method of construction of mixing piles according to claim 4, wherein in the step of forming the powder concrete piles, a material injection pipe is adopted to extend into the bottom of a pile hole of the mixing pile, then dry concrete material is injected, the material injection pipe is lifted or intermittently lifted while the material injection is carried out at the discharge hole of the material injection pipe, and the material injection pipe is of an extension pipe or telescopic pipe structure.

7. The method of constructing a mixing pile according to claim 6, wherein injection of the dry concrete is stopped when the discharge port of the injection pipe is lifted to a second predetermined depth position;

and/or injecting gas while injecting dry concrete material while lifting the injection pipe.

8. The method of constructing a mixing pile according to claim 6, wherein the inner wall of the injection pipe has a wear-resistant coating;

and/or, the inner aperture of the material injection pipe is greater than or equal to 9.9 cm.

9. A method of constructing a mixing pile according to claim 1, wherein the dry concrete material comprises powder and particulate matter, the particulate matter comprising sand aggregate and/or recycled aggregate;

wherein the particle size of the powder is less than or equal to 100 microns;

the particulate matter includes fine particulate matter having a particle diameter of 4.75 mm or less and coarse particulate matter having a particle diameter of 40 mm or less.

10. A composite pile construction method comprising the stirring pile construction method according to any one of claims 1 to 9, further comprising:

a pile planting step which is carried out after the powder concrete pile forming step, wherein a precast pile is inserted into the stirring pile to a preset depth before the stirring pile is not solidified;

the cross section shape of the stirring pile is the same as that of the precast pile;

and/or the cross section shape of the stirring pile and the cross section shape of the precast pile are regular polygons.