Root type concrete press-grouting pile combined foundation and construction method

Abstract

The invention discloses a root type concrete press-grouting pile combined foundation and a construction method, and relates to the technical field of constructional engineering, and the root type concrete press-grouting pile combined foundation comprises a vertical main root pile body and multiple stages of fibrous root expansion units distributed in a forked mode. The outer side of the grouting guide rod is fixedly sleeved with an extrusion head pressing the top of the main reinforcement cage, a plurality of auxiliary reinforcement cages are evenly distributed on the periphery of the main reinforcement cage, the auxiliary reinforcement cages are obliquely distributed on the periphery of the main reinforcement cage, and a net cover is fixedly installed on the top of the main reinforcement cage. The mesh enclosure and the auxiliary reinforcement cage are symmetrically distributed in the horizontal direction and are associated with each other, a sealing piece for providing sealing performance is mounted in the main reinforcement cage in a sleeving manner, and the sealing piece is attached to the top of the mesh enclosure in an extrusion manner and is in extrusion contact with the extrusion head at the same time. The root type concrete press-grouting pile combined foundation and the construction method have the effects of high structural strength, high stability and high bearing performance.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, and in particular to a root-type concrete pressure grouting pile combined foundation and its construction method. Background Technology

[0002] Traditional cast-in-place concrete piles or pressure-grouted piles are typically single cylindrical or slightly enlarged-base pile structures. These foundations rely on the side friction and end resistance of the pile body to bear the vertical pressure load transmitted by the superstructure. However, when facing special geological conditions or complex load conditions, such as collapsible loess areas, recently filled areas, or structures such as transmission towers, wind turbine towers, and offshore platforms subjected to uplift forces, horizontal forces, or huge overturning moments, traditional pile foundations have the disadvantage of low efficiency.

[0003] In traditional concrete pressure grouting pile foundations, pull-out force mainly relies on the side friction of the pile body to resist it, and gravity bearing also mainly relies on friction and end resistance to resist it. To improve efficiency, it is necessary to increase the pile length or pile diameter, which is not economical. Moreover, the pile body is like a cantilever beam, generating a large bending moment at depth, which can easily lead to pile cracking. In existing technologies, although reinforcement measures such as enlarged base piles and anchor rods are used, the construction is complicated, the reliability is greatly affected by geological conditions, and the synergistic reinforcement effect on multi-directional loads is limited. Summary of the Invention

[0004] This invention discloses a root-type concrete pressure-grouted pile combined foundation and construction method, aiming to solve the technical problem that the bearing capacity of traditional concrete pressure-grouted pile foundations mainly relies on the side friction of the vertical pile body and the resistance at the pile bottom, resulting in the need to improve both operating efficiency and structural strength.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A root-type concrete pressure grouting pile composite foundation and construction method, comprising a vertical main root pile body and a multi-level root extension unit with a branched distribution, wherein a longitudinal foundation pit, an inclined pile hole and a longitudinal pile hole are sequentially formed on the ground by a drilling rig. The main root pile includes a main reinforcing cage. Inside the main reinforcing cage, grouting guide rods for concrete grouting are vertically distributed. An extrusion head is sleeved and fixed on the outside of the grouting guide rods and pressed against the top of the main reinforcing cage. A mesh cover is fixedly installed on the top of the main reinforcing cage. A sealing member that provides sealing is sleeved and installed inside the main reinforcing cage. The sealing member is pressed and fitted against the top of the mesh cover and simultaneously pressed and contacted with the extrusion head. Several evenly distributed outward expansion bars are prefabricated and welded to the lower outside of the mesh cover. The bottom of the outward expansion bars is provided with a barb-shaped tail hook, which is hooked to the outside of the stirrup member. The multi-stage root extension unit includes several secondary reinforcing cages evenly distributed around the main reinforcing cage. The secondary reinforcing cages are inclinedly distributed around the main reinforcing cage and located inside the inclined pile hole.

[0006] Based on traditional concrete pressure-grouted pile foundation and construction techniques, this method incorporates multiple individual secondary reinforcement cages that work in conjunction with the main reinforcement cage. First, positioning plates facilitate the quick installation of the secondary reinforcement cages. Then, connecting structures such as mesh covers and closure components complete the combined use of the secondary and main reinforcement cages. On one hand, the main and secondary reinforcement cages form a root-like distribution structure along the foundation's interior. On the other hand, pressure grouting causes the formed foundation to develop tree-like splits along the pile holes, providing an "anchor bar" effect through inclined branches. This significantly increases the bearing capacity compared to traditional piles of the same volume. Simultaneously, the secondary reinforcement cages greatly increase the effective width and moment of inertia of the foundation, effectively enhancing its resistance to bending moments and horizontal forces. Furthermore, the multi-directional branches work together with the main piles to efficiently distribute complex spatial loads to deeper and wider areas of soil, resulting in a more rational stress pattern and high stability, thus enabling this foundation to have a wider range of applications and value.

[0007] In a preferred embodiment, the positioning plate has several inclined positioning openings through its interior. Inclined pile holes are drilled along the foundation sidewall through the positioning openings, and then the secondary reinforcing cage is inserted into the inclined pile holes through the positioning openings.

[0008] By setting up inclined positioning ports inside the positioning plate, the positioning ports assist workers in processing inclined pile holes and installing and fixing secondary steel reinforcement cages, thereby improving the convenience of this combined foundation construction.

[0009] In a preferred embodiment, the main body of the secondary reinforcing cage is composed of several longitudinal reinforcing bars evenly distributed around an axis. At the same time, several evenly distributed stirrups are welded and fixed to the outside of the longitudinal reinforcing bars. The main reinforcing cage and the secondary reinforcing cage have the same structure but different dimensions. Several evenly distributed outward-expanding bars are prefabricated and welded to the lower outer side of the mesh cover. The outward-expanding bars and the longitudinal reinforcing bars are in contact by compression. The bottom of the outward-expanding bars is provided with a barb-shaped tail hook, which is hooked to the outside of the stirrup.

[0010] By adding an externally expanding bar structure with a built-in tail hook to the mesh cover, the external expansion and compression of the bar firstly causes the secondary steel cage to contact the mesh cover, improving the structural strength and stability of the concrete composite foundation after grouting and solidification. At the same time, the tail hook at the bottom of the bar can engage with the stirrups of the secondary steel cage, improving the resistance to upward pull of the main and secondary steel cages when workers perform pressurized grouting on the foundation, thereby significantly improving the operational reliability of the equipment.

[0011] In a preferred embodiment, the interior of the closure has a plurality of evenly distributed grouting ports, each of which is distributed close to a secondary reinforcing cage.

[0012] By adding grouting ports inside the enclosure, after the workers complete the initial grouting of the foundation, they can use the grouting pipes at the grouting ports to perform secondary grouting at the location of each secondary steel cage, thereby improving the density between the foundation and the subgrade.

[0013] A construction method for a root-type concrete pressure-grouted pile composite foundation includes the following steps; S1: The worker first controls the drilling machine to prepare the initial longitudinal foundation pit along the set point. The longitudinal foundation pit and the outer dimensions of the positioning plate are the same. Then the worker splices the two positioning plates along the hole wall and attaches them to the inner wall of the hole to prevent the hole wall from collapsing. S2: The worker controls the tilt of the drilling rig, changes the drill bit, and drills an inclined pile hole along the inner side of the positioning plate towards the side wall of the longitudinal foundation pit. S3: The worker removes the positioning plate and resets the drilling rig. He drills deep holes along the longitudinal foundation pit to form longitudinal pile holes. At the same time, he inserts several of the auxiliary steel cages into the inclined pile holes in sequence. Then, he uses a crane to lift the main steel cage into the longitudinal pile hole. S4: The worker controls the external punching machine connected to the grouting guide rod, which drives the extrusion head to press the main steel cage to a specified depth in the longitudinal pile hole, so that the mesh cover and several of the secondary steel cages are connected and the sealing member covers the secondary steel cages. S5: Subsequently, the worker controls the external punching machine to pull the grouting guide rod and the extrusion head upwards and vertically lift them apart. During this process, the grouting guide rod slowly injects concrete grout into the interior of the main steel reinforcement cage. S6: Use the sealing element to maintain the grouting pressure inside the pile hole, then perform a second sealing and grouting, and remove the sealing element from the top of the main reinforcement cage to complete the workflow.

[0014] The present invention provides a root-type concrete pressure grouting pile combined foundation and construction method, which has the following technical effects.

[0015] Based on traditional concrete pressure grouting pile foundation and construction technology, multiple individual secondary steel cages are set up to work in combination with the main steel cage. First, the secondary steel cages are quickly installed using positioning plates. Then, the secondary steel cages and the main steel cages are used in combination using connecting structures such as mesh covers and closures, thereby achieving the following effects. Firstly, the main and secondary steel reinforcement cages form a root-like distribution structure along the interior of the foundation. Based on this, the pressure grouting method is used to cause the formed foundation to produce tree-like splits along the interior of the foundation. This provides an effect similar to "anchor bars" by using inclined branches, and the bearing capacity can be significantly improved compared with traditional piles of the same volume.

[0016] Secondly, the use of secondary steel reinforcement cages can significantly increase the effective width and rotational inertia of the foundation, multiplying its ability to resist bending moments and horizontal forces. Furthermore, the multi-directional branches work together with the main piles to efficiently distribute and transfer complex spatial loads to deeper and wider soil masses, resulting in a more rational stress pattern and high stability, which makes this foundation applicable to a wider range of environments and has greater value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure proposed in this invention.

[0018] Figure 2 This is a schematic diagram of the main view structure proposed in this invention.

[0019] Figure 3 This is a schematic diagram of the secondary steel cage structure proposed in this invention.

[0020] Figure 4 This is an exploded view of the overall structure proposed in this invention.

[0021] Figure 5 This is a schematic diagram of the closure structure proposed in this invention.

[0022] Figure 6 This is a schematic diagram of the mesh structure proposed in this invention.

[0023] Figure 7 This is a schematic diagram of the structure after the main steel cage proposed in this invention is installed.

[0024] Figure 8 The present invention proposes Figure 7 Enlarged view of the structure at point A in the middle.

[0025] Figure 9 This is a top view of the secondary steel cage structure proposed in this invention.

[0026] Figure 10 This is a schematic diagram of the longitudinal foundation pit structure proposed in this invention.

[0027] Figure 11 This is a schematic diagram of the inclined pile hole structure proposed in this invention.

[0028] Figure 12 This is a schematic diagram of the longitudinal pile hole structure proposed in this invention.

[0029] Figure 13This is a schematic diagram of the state when the tail hook of the present invention comes into contact with the stirrup. The arrow indicates the direction of tail hook deformation.

[0030] Figure 14 This is a schematic diagram of the state after the tail hook of the present invention comes into contact with the stirrup. The arrow indicates the direction of tail hook deformation.

[0031] In the diagram: 1. Main reinforcing cage; 2. Grouting guide rod; 3. Extrusion head; 4. Positioning plate; 401. Positioning port; 402. Handle; 5. Secondary reinforcing cage; 501. Longitudinal reinforcement; 502. Stirrup; 6. Mesh cover; 601. Outward expansion reinforcement; 602. Tail hook; 603. Through opening; 7. Sealing component; 701. Bolt sleeve; 702. Grouting port; 8. Longitudinal foundation pit; 9. Inclined pile hole; 10. Longitudinal pile hole. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0033] The present invention discloses a root-type concrete pressure grouting pile combined foundation and construction method, which is mainly applied to the installation and construction of a combined concrete pressure grouting pile foundation.

[0034] Reference Figures 1 to 14 A type of root-type concrete pressure grouting pile composite foundation includes a vertical main root pile body and a multi-level root extension unit with a branched distribution. A longitudinal foundation pit 8, an inclined pile hole 9 and a longitudinal pile hole 10 are formed on the ground in sequence by a drilling rig. The main root pile includes a main steel cage 1. Inside the main steel cage 1, there are vertically distributed grouting guide rods 2 for concrete grouting. The outer side of the grouting guide rods 2 is sleeved and fixed with an extrusion head 3 that presses against the top of the main steel cage 1. A mesh cover 6 is fixedly installed on the top of the main steel cage 1. Inside the main steel cage 1, there is a sealing member 7 that provides sealing. The sealing member 7 is squeezed and fitted against the top of the mesh cover 6 and is in contact with the extrusion head 3. Several evenly distributed outward expansion bars 601 are prefabricated and welded to the lower outer side of the mesh cover 6. The bottom of the outward expansion bars 601 is provided with a barbed tail hook 602. The tail hook 602 is hooked to the outside of the stirrup member 502. The multi-level root extension unit includes several secondary reinforcing cages 5 evenly distributed around the main reinforcing cage 1. The secondary reinforcing cages 5 are inclinedly distributed around the main reinforcing cage 1 and located inside the inclined pile hole 9.

[0035] In this embodiment: The worker first controls the drilling machine to prepare the initial longitudinal foundation pit 8 along the set points. The longitudinal foundation pit 8 and the positioning plate 4 have the same outer dimensions. Then, the worker splices two positioning plates 4 along the hole wall and attaches them to the inner wall of the hole to prevent the hole wall from collapsing and to provide guidance for subsequent drilling and the pre-embedded secondary reinforcing cage 5. Next, the worker controls the drilling machine to tilt, changes the drilling machine, and drills an inclined pile hole 9 along the inner side of the positioning plate 4 towards the side wall of the longitudinal foundation pit 8. Then, the positioning plate 4 is removed, and the drilling machine is reset. Then, a deep hole is drilled along the longitudinal foundation pit 8 to form a longitudinal pile hole 10. Immediately afterwards, several secondary reinforcing cages 5 are inserted into the inclined pile hole 9 in sequence. Then, using… The crane lifts the main reinforcing cage 1 into the longitudinal pile hole 10. Then, the external punching machine connected to the grouting guide rod 2 is controlled to drive the extrusion head 3 to press the main reinforcing cage 1 to a specified depth inside the longitudinal pile hole 10, so that the mesh cover 6 and several secondary reinforcing cages 5 are connected and the sealing part 7 is covered on top of the secondary reinforcing cages 5. Then, the worker controls the external punching machine to pull the grouting guide rod 2 and the extrusion head 3 to be vertically lifted and detached. During this process, the grouting guide rod 2 slowly injects concrete grout into the interior of the main reinforcing cage 1. At the same time, the sealing part 7 is used to maintain the grouting pressure inside the pile hole. A second sealing and grouting is then carried out. Finally, the sealing part 7 is removed from the top of the main reinforcing cage 1 to complete the work process.

[0036] It is worth noting that the drilling rig of this application can be used with either a rotary drilling bit or an auger bit according to construction needs. When constructing the longitudinal foundation pit 8, a rotary drilling bit can be used for rotary drilling; when constructing the inclined pile hole 9, an auger bit can be used for rotary drilling; when constructing the longitudinal pile hole 10, a rotary drilling bit can continue to be used for rotary drilling. These are existing construction techniques and will not be described in detail here. It is also worth noting that, such as Figure 10 and Figure 12 As shown, the inner opening size of the longitudinal foundation pit 8 is larger than that of the longitudinal pile hole 10. This is to provide more working space for the construction of the inclined pile hole 9 and the installation of the secondary steel cage 5, and to ensure that the installation of the main steel cage 1 is not affected by the secondary steel cage 5. During the construction of the longitudinal pile hole 10, when the rotary drilling bit is raised, some excess soil may enter the longitudinal foundation pit 8 and the inclined pile hole 9. The inclined pile hole 9 can be sealed with a baffle in advance to prevent excess soil from entering, and the excess soil in the longitudinal foundation pit 8 can be cleaned up later using a soil suction machine.

[0037] Specifically, the size of the rotary drilling bit used in the construction of the longitudinal foundation pit 8 should be larger than the size of the drill bit used in the construction of the longitudinal pile hole 10, so as to ensure that the inner opening size of the longitudinal foundation pit 8 is larger than the inner opening size of the longitudinal pile hole 10.

[0038] In addition, the root extension units of this application are provided in two or more groups, while the attached figures of this application show four groups as an example.

[0039] The positioning plate 4 has several inclined positioning holes 401 that are opened through its interior. Inclined pile holes 9 are drilled along the side wall of the foundation through the positioning holes 401, and the secondary steel cage 5 is inserted into the inclined pile holes 9 through the positioning holes 401. Each positioning plate 4 has a handle 402 fixedly installed on its top for easy hand operation by workers. The positioning plate 4 is made of elastic metal material, such as thin stainless steel plate.

[0040] Reference Figure 4 , Figures 6 to 8 In a preferred embodiment, the main body of the secondary reinforcing cage 5 is composed of several longitudinal reinforcing bars 501 evenly distributed around the axis. At the same time, several evenly distributed stirrups 502 are welded and fixed to the outside of the longitudinal reinforcing bars 501. The main reinforcing cage 1 and the secondary reinforcing cage 5 have the same structure but different dimensions. Several evenly distributed outward expansion bars 601 are prefabricated and welded to the lower outside of the mesh cover 6. The outward expansion bars 601 and the longitudinal reinforcing bars 501 are in contact by compression. The bottom of the outward expansion bars 601 is provided with a barbed tail hook 602, which is hooked to the outside of the stirrup 502.

[0041] When the extrusion head 3 presses the main steel cage 1 to a specified depth inside the longitudinal pile hole 10, the outer expansion bar 601 on the outside of the mesh cover 6 and the longitudinal reinforcement members 501 of several secondary steel cages 5 will connect and contact each other. The tail hook 602 located at the bottom of the outer expansion bar 601 will hook onto the outside of the stirrup member 502 of the secondary steel cage 5. At this time, the sealing member 7 is attached to the inner wall of the longitudinal foundation pit 8 and covers the upper part of the secondary steel cage 5. Then, the worker controls the external punching machine to pull the grouting guide rod 2 and the extrusion head 3 to be vertically lifted and separated. During this process, the grouting guide rod 2 slowly injects concrete slurry into the interior of the main steel cage 1. At the same time, the sealing member 7 is used to maintain the grouting pressure inside the pile hole. During this process, the main steel cage 1 and the secondary steel cage 5 will form a whole due to the connection and fixation of the tail hook 602, thereby improving the anti-uplift ability of the entire foundation during grouting.

[0042] It is worth noting that, such as Figure 7 and Figure 8 As shown, after the secondary reinforcing cage 5 is inserted into the inclined pile hole 9, part of the upper end of the secondary reinforcing cage 5 will be exposed. The exposed part will not affect the installation of the main reinforcing cage 1, but it is necessary to ensure that the tail hook 602 and the stirrup 502 of the secondary reinforcing cage 5 can contact each other. During the contact process, the tail hook 602 and the outward expansion bar 601 will be deformed by inward compressive force (such as...). Figure 13 As shown (the arrow indicates the deformation direction of the tail hook 602), and after the main reinforcing cage 1 is installed to the specified depth, the tail hook 602 is located below the stirrup 502, and is reset by the deformation of the outer expansion bar 601 (as shown). Figure 14As shown (the arrow indicates the deformation direction of the tail hook 602), the tail hook 602 is hooked on the outside of the stirrup 502, which can improve the resistance to upward pull during the sealing grouting. The tail hook 602 has an outward arc shape, which ensures that the tail hook 602 can contact the stirrup 502 and deform as the main steel cage 1 descends. After it is located below the stirrup 502, it will form a hook locking structure.

[0043] The mesh cover 6 has several evenly distributed openings 603 inside to allow concrete slurry to flow.

[0044] Reference Figure 5 In a preferred embodiment, the top of the closure 7 is provided with symmetrically distributed bolt sleeves 701. The outer surface of the bolt sleeves 701 is provided with a groove. The bolt sleeves 701 are slidably sleeved on the outside of the main steel cage 1 and tightened by a nut. During the tightening process, the bolt sleeves 701 will tighten through the groove, thereby fixing the closure 7 to the outside of the main steel cage 1.

[0045] Under normal circumstances, the sealing component 7 is fixed to the outside of the main steel cage 1 by the bolt sleeve 701. After the worker completes the pressure grouting of the entire composite foundation, the worker rotates the nut installed on the outside of the bolt sleeve 701 to remove the sealing component 7.

[0046] Specifically, the interior of the sealing component 7 has several evenly distributed grouting ports 702. Each grouting port 702 is closely distributed with a secondary steel reinforcement cage 5. After the workers complete the initial grouting of this composite foundation, additional grouting pipe structures are inserted at the grouting ports 702. Then, secondary grouting is performed at each inclined pile hole 9 through the grouting pipes. Through pressure grouting and secondary grouting, radial or branched "branch-like extensions" can be formed at the bottom and inner wall of the inclined pile hole 9 and the longitudinal pile hole 10, similar to the extension of tree roots, thereby improving the bearing capacity of the pile foundation.

[0047] Working principle: During use, the worker first controls the drilling machine to prepare the initial longitudinal foundation pit 8 along the set points (e.g., Figure 10 As shown), the longitudinal foundation pit 8 and the positioning plate 4 have the same outer dimensions. Afterwards, the workers splice the two positioning plates 4 along the hole wall and attach them to the inner wall of the hole to prevent the hole wall from collapsing. Then, the workers control the drilling rig to tilt, change the drill bit, and drill an inclined pile hole 9 (as shown) along the inner side of the positioning plate 4 towards the side wall of the longitudinal foundation pit 8. Figure 11 As shown), the workers then removed the positioning plate 4, then controlled the drilling rig to reset, and drilled deep holes along the longitudinal foundation pit 8 to form longitudinal pile holes 10 (as shown). Figure 12As shown), several secondary reinforcing cages 5 are sequentially inserted into the inclined pile holes 9. Then, a crane is used to hoist the main reinforcing cage 1 into the longitudinal pile hole 10. Workers then control an external punching machine connected to the grouting guide rod 2, driving the extrusion head 3 to press the main reinforcing cage 1 to a specified depth within the longitudinal pile hole 10. During this process, the tail hook 602 on the outside of the mesh cover 6 will contact the longitudinal reinforcement members 501 of several secondary reinforcing cages 5. After the main reinforcing cage 1 is installed in the designated position, the tail hook 602 is located below the stirrup member 502 and is reset by the deformation of the outer expansion bar 601, thus causing the tail hook 602 to hook onto the outside of the stirrup member 502. At this time, the sealing member 7 adheres to the inner wall of the longitudinal foundation pit 8 and covers the upper part of the secondary reinforcing cage 5. Afterwards, workers control the external... The press, along with the grouting guide rod 2 and the extrusion head 3, is vertically lifted and detached. During this process, the grouting guide rod 2 slowly injects concrete grout into the main reinforcing cage 1. At the same time, the sealing member 7 maintains the grouting pressure inside the pile hole. As the grouting height increases, the grout will eventually fill the longitudinal pile hole 10 and the inclined pile hole 9. During this process, the main reinforcing cage 1 and the secondary reinforcing cage 5 are connected and formed as a whole by the tail hook 602, thereby increasing the upward resistance of the sealing member 7 and improving the anti-uplift ability of the entire pile foundation during grouting. After the grouting is completed, secondary grouting is carried out into the inclined pile hole 9 to improve the grouting effect of the inner wall of the inclined pile hole 9. Finally, the sealing member 7 is removed to complete the workflow.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A root-type concrete pressure-grouted pile composite foundation, comprising a vertical main root pile body and a multi-level root extension unit distributed in a branched manner, characterized in that, The drilling rig sequentially forms a longitudinal foundation pit (8), an inclined pile hole (9), and a longitudinal pile hole (10) on the ground. The main root pile body includes a main steel cage (1), and grouting guide rods (2) for concrete grouting are vertically distributed inside the main steel cage (1). An extrusion head (3) is fixedly sleeved on the outside of the grouting guide rod (2) and pressed against the top of the main steel cage (1). A mesh cover (6) is fixedly installed on the top of the main steel cage (1). A sealing member (7) for providing sealing is sleeved inside the main steel cage (1). The sealing member (7) is pressed against the top of the mesh cover (6) and presses against the extrusion head (3). Several evenly distributed outward expansion bars (601) are prefabricated and welded on the lower outside of the mesh cover (6). The bottom of the outward expansion bars (601) is provided with a barb-shaped tail hook (602). The multi-level root extension unit includes several secondary reinforcing cages (5) evenly distributed around the main reinforcing cage (1). The secondary reinforcing cages (5) are inclinedly distributed around the main reinforcing cage (1) and located inside the inclined pile hole (9). The main body of the secondary steel cage (5) is composed of several longitudinal reinforcement members (501) evenly distributed around the axis. At the same time, several evenly distributed stirrup members (502) are welded and fixed on the outside of the longitudinal reinforcement members (501), and the tail hook (602) is hooked on the outside of the stirrup members (502).

2. The root-type concrete pressure-grouted pile combined foundation according to claim 1, characterized in that, The longitudinal foundation pit (8) is provided with a positioning plate (4) on its inner wall. The positioning plate (4) has several inclined positioning ports (401) through which a drilling machine drills an inclined pile hole (9) along the side wall of the foundation through the positioning port (401). Then the auxiliary steel cage (5) is inserted into the inclined pile hole (9) through the positioning port (401).

3. The root-type concrete pressure-grouted pile combined foundation according to claim 2, characterized in that, Each of the positioning plates (4) is fixedly fitted with a handle (402) on its top.

4. The root-type concrete pressure-grouted pile combined foundation according to claim 1, characterized in that, The main steel cage (1) and the secondary steel cage (5) have the same structure but different dimensions.

5. A root-type concrete pressure-grouted pile combined foundation according to claim 4, characterized in that, The outer expansion rib (601) and the longitudinal rib (501) are in extrusion contact.

6. A root-type concrete pressure-grown pile composite foundation according to claim 1, characterized in that, The mesh cover (6) has several evenly distributed openings (603) running through its interior.

7. A root-type concrete pressure-grouted pile combined foundation according to claim 1, characterized in that, The top of the closure (7) is provided with symmetrically distributed bolt sleeves (701). The bolt sleeves (701) are slidably sleeved on the outside of the main steel cage (1) and tightened by nuts to fix the closure (7) to the outside of the main steel cage (1).

8. A root-type concrete pressure-grouted pile combined foundation according to claim 1, characterized in that, The interior of the closure (7) is provided with several evenly distributed grouting ports (702), each of which is close to a secondary steel cage (5).

9. A construction method for a root-type concrete pressure-grouted pile combined foundation according to claim 2, characterized in that, Includes the following steps; S1: The worker first controls the drilling machine to prepare the initial longitudinal foundation pit (8) along the set point. The longitudinal foundation pit (8) and the positioning plate (4) have the same outer dimensions. After that, the worker splices the two positioning plates (4) along the hole wall and attaches them to the inner wall of the hole to prevent the hole wall from collapsing. S2: The worker controls the drilling rig to tilt, changes the drill bit and drills the inclined pile hole (9) along the inner side of the positioning plate (4) towards the side wall of the longitudinal foundation pit (8). S3: The worker removes the positioning plate (4), resets the drilling machine, drills deep holes along the longitudinal foundation pit (8) and forms a longitudinal pile hole (10), and inserts several of the auxiliary steel cages (5) into the inclined pile hole (9) in sequence. Then, the main steel cage (1) is hoisted into the longitudinal pile hole (10) using a crane. S4: The worker controls the external punching machine connected to the grouting guide rod (2), drives the extrusion head (3) to press the main steel cage (1) to a specified depth in the longitudinal pile hole (10), so that the mesh cover (6) and several secondary steel cages (5) are connected, and the sealing member (7) covers the secondary steel cage (5). S5: After that, the worker controls the external punching machine to pull the grouting guide rod (2) and the extrusion head (3) to be lifted vertically upward and separated. During this process, the grouting guide rod (2) slowly injects concrete grout into the interior of the main steel cage (1). S6: Use the sealing element (7) to maintain the grouting pressure inside the pile hole, then perform a second sealing and grouting, and remove the sealing element (7) from the top of the main steel cage (1) to complete the workflow.

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