Miniature steel pipe pile foundation reinforced by confined space anchor type pile cap beam counter pressure and construction method thereof

Abstract

The present application relates to a confined space anchor type pile cap beam counter pressure micro steel pipe pile foundation and its construction method, the construction method mainly includes: first, through the grouting pipe positioning mold in the bridge bored pile week carries out accurate grouting reinforcement; second, a new type of pile cap beam is constructed on the original connection beam; then the original connection beam is removed, and the pile cap beam is used to set a counter pressure hole to limit the steel pipe pile, and a pile press is used to press the segmented micro steel pipe pile into the soil, and a steel pipe pile lengthening support is used to weld the segmented micro steel pipe pile; finally, a hanging and supporting formwork system is used to restore the original connection beam, so that the top end of the micro steel pipe pile is anchored in the connection beam. The present application solves the technical problem of active and efficient reinforcement of the existing bridge pile foundation in the confined space, and ensures the safe operation of the bridge.

Description

Technical Field

[0001] This invention relates to the field of bridge foundation reinforcement technology, specifically to a method for reinforcing existing bridge pile foundations under confined space conditions and the resulting reinforcement structure. Background Technology

[0002] With the acceleration of urbanization and the increasing density of urban road networks, underground engineering projects such as cut-and-cover tunnels are becoming more and more common, passing under existing highway bridges. The excavation of tunnel foundations inevitably disturbs the strata surrounding the bridge piles, disrupting the original stress balance of the piles and easily leading to uneven settlement or deformation. If this settlement or deformation is not controlled in a timely and effective manner, it will seriously threaten the stability of the bridge foundation, thereby endangering the safety of the superstructure and potentially affecting the normal traffic flow of the highway.

[0003] Currently, several methods exist in the industry for controlling ground displacement and reinforcing pile foundations to address the problems of ground displacement and pile foundation instability caused by tunnel excavation, such as grouting reinforcement and isolation reinforcement. However, these conventional methods have significant limitations under specific working conditions. Especially in situations where the space under the bridge is confined (i.e., "restricted space") and the bridge needs to maintain continuous operation, traditional large-scale construction machinery and processes are difficult to implement, resulting in a serious lack of applicability of existing methods. Furthermore, single reinforcement methods are often insufficient to effectively compensate for the significant loss of pile foundation bearing capacity caused by tunnel excavation, failing to meet the safety requirements of bridge structures under complex working conditions.

[0004] Therefore, there is an urgent need to develop a new reinforcement technology that can adapt to confined space operations, not interrupt bridge traffic, and efficiently and proactively restore the bearing capacity of pile foundations. Summary of the Invention

[0005] The purpose of this invention is to address the problem that existing reinforcement methods are unable to efficiently and fully restore the bearing capacity of pile foundations lost due to tunnel excavation within the confined space under the bridge, while ensuring the continuous operation of the bridge. This invention provides a method for reinforcing pile foundations with anchored pile cap beams and micro steel pipes in confined spaces, and innovatively adds a pile cap beam to the original connecting beam and uses it as a reaction foundation to insert micro steel pipe piles. Finally, the original connecting beam is removed and rebuilt, so that the top of the newly planted steel pipe pile is anchored in the rebuilt connecting beam.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution: A method for constructing a confined space anchored pile cap beam reinforced with micro-steel pipe includes the following steps:

[0007] Step 1, Positioning and Grouting: Install grouting pipe positioning molds on the bored piles of the existing bridge, drill holes through the grouting pipe openings on the grouting pipe positioning molds and grout, forming a pile perimeter reinforcement zone;

[0008] Step 2, Construction of the pier cap beam: Construct the pier cap beam on the existing connecting beam, and reserve counter-pressure holes on the pier cap beam;

[0009] Step 3: Demolition of the original tie beam: Retain the main reinforcement joints of the original tie beam and demolish the original tie beam in sections;

[0010] Step 4: Driving of micro steel pipe piles: Using the pier beam completed in Step 2 as the reaction foundation, the micro steel pipe piles are driven into the soil section by section through the counter-pressure holes.

[0011] Step 5: Reconstruction of the original connecting beam: Reconstruct the connecting beam by connecting the new reinforcing bars with the main reinforcement joints retained in Step 3, so that the top of the micro steel pipe pile is anchored in the newly poured connecting beam.

[0012] In step one, the grouting pipe positioning mold includes an L-shaped mold and a straight mold that are fixed to the first clamp by a connector; the first clamp is fastened to the bored pile.

[0013] In step two, a square hanging frame is installed on the existing connecting beam, and a square cone mold is installed at the bottom of the square hanging frame; after the concrete of the pier beam is poured and cured, the square cone mold is removed to form a counter-pressure hole.

[0014] In step four, during the pressing process, the segmented steel pipes are aligned and welded using a steel pipe pile extension support set on the ground; the steel pipe pile extension support includes a base plate, uprights, and a circular clamp installed on the upper end of the uprights.

[0015] In step five, the formwork support system used when rebuilding the tie beam includes:

[0016] Small support brackets for the middle section of connecting beams, with their tops supporting standardized plastic formwork; and

[0017] The hanging brackets used for connecting the two sides of the beam include a square support frame assembled on the cap beam and a double row of hangers suspended at its bottom.

[0018] The side formwork of the connecting beam is fixed by tie rods and a second clamp; the second clamp is fastened to the column, one end of the tie rod is connected to the second clamp, and the other end passes through the side formwork and presses it tight.

[0019] A confined space anchored pile foundation reinforced with micro steel pipes for counter-pressure is constructed using the above-mentioned construction method.

[0020] Working principle and beneficial effects:

[0021] 1. Solving the problem of construction in confined spaces: This invention successfully solves the technical problem of active reinforcement in confined spaces such as under bridges by using customized and miniaturized molds (such as grouting pipe positioning molds and square cone molds) and equipment (such as micro hydraulic pile drivers) and an innovative template system (combining hanging and support).

[0022] 2. Ensure continuous bridge operation: The entire construction method is completed under the bridge without occupying bridge traffic, and the construction process has little impact on the bridge structure, which can ensure the safe operation of the bridge during the reinforcement period.

[0023] 3. High reinforcement efficiency and good effect: This invention is an active reinforcement technology. It first reinforces the soil layer by grouting, and then implants micro steel pipe piles to transfer the load to a deeper stable stratum. Its integrity and bearing capacity are superior to the original structure.

[0024] 4. Strong process applicability: The components used in this invention (such as steel pipe pile extension brackets, molds with threaded connections, etc.) are easy to operate and assemble, and are suitable for use in operating environments with limited space and requiring rapid construction, which significantly improves work efficiency.

[0025] 5. Provide long-term safety assurance: By constructing new abutment beams, inserting micro steel pipe piles and anchoring them in the reconstructed connecting beams, a stable composite pile foundation system is formed, providing long-term and stable safety assurance for the bridge. Attached Figure Description

[0026] Figure 1 This is a plan view of the grouting pipe positioning mold of the present invention;

[0027] Figure 2 This is a schematic diagram of the reverse pressure hole construction structure of the present invention;

[0028] Figure 3 This is a side view of the construction and extension of the steel pipe piles according to the present invention;

[0029] Figure 4 This is a schematic diagram of the steel pipe pile extension support structure of the present invention;

[0030] Figure 5 This is a top view of the steel pipe pile construction of the present invention;

[0031] Figure 6 This is a schematic diagram of the structure of the foundation beam formwork system of the present invention.

[0032] In the diagram, 1. Grouting pipe positioning mold; 2. L-shaped mold; 3. Straight mold; 4. Connector; 5. First clamp; 6. Connecting buckle; 7. Connecting plate; 8. Connecting rod; 9. Grouting pipe orifice; 10. Square hanging frame; 11. Square cone mold; 12. Connecting cap; 13. Connecting cylinder; 14. Tie beam; 15. Bored pile; 16. Cap beam; 17. Miniature steel pipe pile; 18. Steel pipe pile extension bracket; 19. Pipe cap beam; 20. Counterpressure hole; 21. Vertical pole; 22. Diagonal brace; 23. Circular clamp; 24. Fastener; 25. Limiting plate; 26. Base plate; 27. Micro steel pipe pile opening; 28. Grouting reinforcement hole opening; 29. ​​Pile foundation; 30. Counterpressure hole opening; 31. Square support frame; 32. Hanger; 33. Second clamp; 34. Connecting pipe; 35. Tie rod; 36. Standardized plastic template; 37. Small support bracket; 38. Fastening nut. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0034] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0035] Example 1

[0036] This invention provides a construction method for reinforcing existing pile foundations with micro-steel pipes using anchored pier beams in confined spaces. Under conditions of continuous bridge operation and limited space under the bridge, this method involves adding a pier beam as a reaction foundation, implanting micro-steel pipe piles, and finally anchoring the steel pipe piles in the reconstructed connecting beam, thereby achieving active reinforcement of the existing pile foundation.

[0037] like Figures 1 to 6 As shown, the specific steps of the preferred embodiment of the present invention are as follows:

[0038] Step 1: Installation of positioning mold and grouting

[0039] The purpose of this step is to pre-reinforce the soil layer around the bridge pile foundation 29, i.e., the bored pile 15, without disturbing the existing structure, thus forming a pile perimeter reinforcement zone. (Refer to...) Figure 1 First, around the bored pile 15 of the bridge above the tunnel, the first clamp 5 is used to install the grouting pipe positioning mold 1 on the bored pile 15. The grouting pipe positioning mold 1 is provided with a grouting pipe orifice 9. A small drilling machine is used to drill through the grouting pipe orifice 9 to form a grouting reinforcement orifice 28. Its depth reaches the bottom of the soil layer around the pile that needs to be reinforced. The sleeve valve pipe is slowly inserted into the grouting reinforcement orifice 28 along the grouting pipe orifice 9 on the grouting pipe positioning mold 1 to complete the grouting of the soil layer around the pile.

[0040] Specifically, the grouting pipe positioning mold 1 includes an L-shaped mold 2, a straight mold 3, connectors, and a first clamp 5. The L-shaped mold 2 and the straight mold 3 are made of lightweight plastic and are connected and secured together using connecting buckles 6. The first clamp 5 is made of galvanized steel and is assembled from two semicircles to secure it to the bored pile 15. Connectors are used to install the molds and the first clamp 5. The connectors include a connecting rod 8 and a connecting plate 7. The connecting rod 8 is made of galvanized steel, with one end welded to the first clamp 5 and the other end connected to the connecting plate 7. The connecting plate 7 is also made of galvanized steel and is bolted to the mold.

[0041] The L-shaped mold 2 and the straight mold 3 are equipped with grouting pipe openings 9, the diameter of which is larger than the diameter of the drill bit of the small drilling rig.

[0042] The grouting pipe positioning mold 1 is provided with grouting pipe orifices 9 with equal spacing. The grouting pipe positioning mold 1 is fastened to the bored pile 15, that is, the bridge pile foundation 29, 1m above the ground. A small drilling rig can pass through the grouting pipe orifice 9 and drill vertically. After drilling is completed, the sleeve valve pipe also passes through the grouting pipe orifice 9 and is inserted into the hole.

[0043] Step 2: Construction of the Abutment Beam

[0044] A square hanging frame 10 is installed on the connecting beam 14, and a square cone mold 11 is installed at its bottom. The mold is vertically fixed below the connecting beam 14. Then, a disc-type support is set up for rebar tying and formwork erection for the foundation beam 19, and concrete for the foundation beam 19 is poured. When removing the formwork after the concrete has cured, the pouring formwork is removed first, and then the connection between the square cone mold 11 and the square hanging frame 10 is removed. The square cone mold 11 is then removed from the bottom of the foundation beam 19, forming a back pressure orifice 30.

[0045] Specifically, the square hanging frame 10 is made of steel profiles, and its shape matches the connecting beam 14, so it can be assembled on the connecting beam 14.

[0046] A connecting cap 12 is provided below the square hanging frame 10, and is fixed to the square hanging frame 10 by bolt connection. A connecting cylinder 13 is provided below the connecting cap 12, and the connecting cylinder 13 is welded to the connecting cap 12. The connecting cylinder 13 has internal threads inside.

[0047] The square cone mold 11 has a quadrilateral cone at the top and a cylinder at the top. The outer surface of the cylinder has external threads. The square cone mold 11 is fixed to the bottom of the connecting cylinder 13 by a threaded connection. The resulting back pressure orifice 30 is quadrilateral in shape. The size of the top back pressure orifice 30 is smaller than that of the bottom back pressure orifice 30.

[0048] When removing the square cone mold 11, first remove the bolts between the connecting cap 12 and the square hanging frame 10, then rotate the connecting cylinder 13 to remove it from the square cone mold 11. Then gently tap the top of the square cone mold 11 to move it downwards and remove the square cone mold 11 from the bottom of the pier beam 19.

[0049] Step 3: Demolition of the original bridge connecting beams

[0050] Before demolition, the positions of the main reinforcement bars of the original connecting beam 14 were marked, and the joints of the main reinforcement bars that need to be retained were identified. The original connecting beam 14 was demolished in sections using small crushing machinery (such as hydraulic breakers).

[0051] Step 4: Driving and extending the 17-segment miniature steel pipe piles

[0052] The Ø300 micro steel pipe pile 17 is processed into 2m sections. The two ends of each section are welded together. A micro hydraulic pile driver is installed above the pier beam 19. The pier beam 19 provides the reaction force to press the segmented micro steel pipe pile 17 into the borehole one by one. At the same time, a steel pipe pile extension bracket 18 is installed on the ground directly opposite the position of the micro steel pipe pile 17. The ends of each section of steel pipe are clamped with circular clamps and then welded. After the micro steel pipe pile 17 is implanted, the top of it extends into the connecting beam 14 by about 0.1m.

[0053] The steel pipe pile extension bracket 18 mainly includes a diagonal rod 22, an upright rod 21, a circular clamp 23, fastening bolts, a limiting plate 25, and a base plate 26. One end of the diagonal rod 22 is installed on one side of the base plate 26, and the other end is installed on the top of the upright rod 21. The bottom of the upright rod 21 is welded to the base plate 26. The center of the base plate 26 has a circular hole slightly larger than the diameter of the micro steel pipe pile 17. Symmetrical limiting plates 25 are provided on both sides of the circular hole. The circular clamp 23 is installed on the upper end of the upright rod 21. The diameter of the circular clamp 23 is slightly smaller than that of the micro steel pipe pile 17. The circular clamp 23 is equipped with fasteners 24.

[0054] Step 5: Reconstruction of the original bridge connecting beams

[0055] Using the existing main reinforcement joints of the original connecting beam 14, the newly fabricated connecting beam 14 reinforcement bars were connected to the original main reinforcement bars by welding or mechanical connection. The stirrups and other structural reinforcement bars were restored according to the original design drawings of connecting beam 14. Using the cap beam 16, columns, and abutment beam 19 as supports, the formwork of connecting beam 14 was constructed by hanging scaffolds and small support scaffolds 37. Concrete with the same strength grade as the original structure was then poured to restore the original bridge connecting beam 14.

[0056] Specifically, the middle part of the connecting beam 14 uses a small support bracket 37 as a template support. The top of the small support bracket 37 supports a standardized plastic template 36. This standardized plastic template 36 has a semi-circular opening and is assembled into a whole by snap-fit ​​connection. The diameter of the circular opening after assembly is the same as the diameter of the micro steel pipe pile 17.

[0057] Furthermore, hanging brackets are used as template supports on both sides of the connecting beam 14, and a square support frame 31 made of channel steel is assembled on the cap beam 16. The bottom of the square support frame 31 is provided with double rows of hanging rods 32. The bottom of the hanging rods 32 passes through the standardized plastic template 36 and is fixed to the bottom of the template with fastening nuts 38. A small support bracket 37 is provided at the bottom of the template on the side near the pile foundation 29.

[0058] Furthermore, the side formwork of the middle section of the connecting beam 14 is fixed by a tie rod, and the side formwork at both ends of the connecting beam 14 is fixed to both ends of the connecting beam 14 by tie rods 35 in the form of clamps.

[0059] The tie rod 35 is made of steel pipe, with an external thread at one end that is threaded to the second clamp 33, and the other end passes through the side mold and is fixed to the side of the end of the connecting beam 14 by fastening the nut 38.

[0060] The diameter of the second clamp 33 is the same as that of the column, and a connecting pipe 34 with internal threads is welded to its surface. The connecting pipe 34 is connected to the tie rod 35 with external threads.

[0061] Example 2

[0062] Based on the same concept, this embodiment provides a construction method for reinforced pile foundations with micro-steel pipes under counter-pressure on confined space anchored pile cap beams:

[0063] Step 1: Installation of positioning mold and grouting

[0064] The purpose of this step is to pre-reinforce the soil layer around the bridge pile foundation 29, i.e., the bored pile 15, without disturbing the existing structure, thus forming a pile perimeter reinforcement zone. (Refer to...) Figure 1First, around the bridge bored pile 15 above the tunnel, the grouting pipe positioning mold 1 is installed and fastened to the bored pile 15 using the first clamp 5. The grouting pipe positioning mold 1 preferably includes an L-shaped mold 2 and a straight mold 3, and the molds can be spliced ​​together by connecting buckles 6. The mold is fixed to the first clamp 5 by connecting parts 4.

[0065] Specifically, the connector 4 may include a connecting rod 8 and a connecting plate 7. One end of the connecting rod 8 is welded to the first clamp 5, and the other end is connected to the connecting plate 7. The connecting plate 7 is fixed to the L-shaped mold 2 and the straight mold 3 by bolts or other means. After installation, a small drilling rig is used to drill through the pre-set grouting pipe orifices 9 on the grouting pipe positioning mold 1 to form grouting reinforcement orifices 28 in the soil around the pile. Figure 5 As shown, the grouting reinforcement holes 28 are distributed along both sides of the pile cap beam 19. Subsequently, the sleeve valve pipe is placed into the grouting reinforcement hole 28, and grouting is performed through the sleeve valve pipe to form a uniform and stable pile perimeter reinforcement zone.

[0066] Step 2: Construction of the Abutment Beam

[0067] The purpose of this step is to construct a new pile cap beam 19 below the existing connecting beam 14, and to use this pile cap beam 19 to provide a reaction foundation for the subsequent driving of the micro-steel pipe piles 17. Simultaneously, counter-pressure holes 20 need to be pre-drilled in the pile cap beam 19. (Refer to...) Figure 2 First, a square hanging frame 10 is installed on the existing connecting beam 14. The shape of the square hanging frame 10 matches the connecting beam 14, allowing it to be assembled on the connecting beam 14. A square conical mold 11 is installed at the bottom of the square hanging frame 10 to form the counter-pressure hole 20. For easy installation and disassembly, the square hanging frame 10 is connected to the square conical mold 11 via a connecting cap 12 and a connecting cylinder 13. Preferably, the connecting cylinder 13 has internal threads, and the top of the square conical mold 11 has a cylinder with external threads; the two are connected by screwing. Using the connecting beam 14 and the square hanging frame 10 as supports, the reinforcement of the foundation beam 19 is tied, the formwork is erected, and the concrete is poured. After the concrete has cured to its strength, the formwork is removed, and the square conical mold 11 is taken out from the bottom of the foundation beam 19 by unscrewing the connecting cylinder 13, thereby forming the counter-pressure hole 20 on the foundation beam 19. Figure 5 As shown, this hole is the counterpressure hole 30 on the plane of the pier beam 19, and its position is staggered with the existing pile foundation 29.

[0068] Step 3: Demolition of the original bridge connecting beams

[0069] After the foundation beam 19 is completed and can bear the load, the original connecting beam 14 will be demolished. Before demolition, the positions of the main reinforcement bars of the original connecting beam 14 should be marked so as to preserve the main reinforcement joints for subsequent reconstruction. Small breaking machinery (such as hydraulic breakers) will be used to demolish the original connecting beam 14 in sections.

[0070] Step 4: Segmented driving and splicing of miniature steel pipe piles

[0071] Reference Figure 3 and Figure 4 In this step, the newly constructed pier beam 19 serves as the reaction foundation, and micro steel pipe piles 17 are driven in. The micro steel pipe piles 17 (for example, processed in 2-meter sections) are placed above the pier beam 19 and driven into the soil section by section using a micro hydraulic pile driver through the pre-drilled counter-pressure holes 20 (i.e., counter-pressure hole openings 30) from step two. During the driving process, to ensure the alignment and welding quality of the segmented steel pipes, steel pipe pile extension supports 18 are installed on the ground directly opposite the micro steel pipe piles 17. (Refer to...) Figure 4 The steel pipe pile extension bracket 18 includes a base plate 26, uprights 21, diagonal braces 22, and circular clamps 23. The base plate 26 has a circular hole at its center for the micro-steel pipe pile 17 to pass through, and limiting plates 25 can be installed on both sides of the hole. The circular clamps 23 are installed at the upper end of the uprights 21. The circular clamps 23 clamp and fix the ends of the segmented steel pipes using fasteners 24 for precise alignment and welding. The process continues segment by segment pressing and extension until the top of the micro-steel pipe pile 17 extends into the designed position of the original connecting beam 14. Figure 5 As shown, the opening of the completed micro steel pipe pile 17 on the plane of the pier beam 19 is the micro steel pipe pile opening 27.

[0072] Step 5: Reconstruction of the original bridge connecting beams

[0073] Reference Figure 6 The purpose of this step is to restore the structural function of the connecting beam 14 and to anchor the top of the micro steel pipe pile 17 into the new connecting beam 14, forming a pile-beam integrated load-bearing structure.

[0074] First, using the original main reinforcement joints of the connecting beam 14 retained in step three, the newly processed reinforcing bars are connected to the original main reinforcement bars by welding or mechanical connection, restoring the reinforcing steel skeleton of the connecting beam 14. Then, the formwork for the connecting beam 14 is erected. This invention employs a formwork support system combining suspended scaffolds and small support brackets 37. For example... Figure 6 As shown, in the middle part of the connecting beam 14, a small support bracket 37 is used as a template support, and its top supports a standardized plastic template 36.

[0075] The standardized plastic formwork 36 has semi-circular openings matching the diameter of the micro steel pipe piles 17. It is assembled into a whole using snap-fit ​​connections, precisely enclosing the micro steel pipe piles 17. Suspended supports are used on both sides of the connecting beam 14. A square support frame 31 is assembled on the cap beam 16, with double-row hanging rods 32 suspended from the bottom of the frame. The bottom of the hanging rods 32 passes through the standardized plastic formwork 36 and is secured with fastening nuts 38. The side forms at both ends of the connecting beam 14 are secured by tie rods 35 and second clamps 33. The second clamp 33 is fastened to the column, and its surface is welded with a connecting pipe 34 with internal threads. One end of the tie rod 35 is threaded to the connecting pipe 34, and the other end passes through the side formwork, pressing the side formwork against the side of the connecting beam 14 end with a fastening nut 38. After the formwork is erected, concrete with the same strength grade as the original structure is poured to restore the original bridge connecting beam 14, so that the top of the micro steel pipe pile 17 is firmly anchored in the newly poured connecting beam 14.

[0076] Example 3

[0077] This invention also protects a confined space anchored pile cap beam reinforced with micro-steel pipes, constructed using the above method. The structure includes the original bored pile 15, a pile cap beam 19 added below the original connecting beam 14, micro-steel pipe piles 17 passing through the pile cap beam 19 and driven into the soil, and a connecting beam 14 reconstructed at the original connecting beam 14 location and anchored to the top of the micro-steel pipe piles 17.

[0078] The parts of this invention not described in detail are prior art, therefore they are not described in detail here.

[0079] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes made to their shape or structure, any technical solution that is the same as or similar to that of this application falls within the protection scope of this invention.

Claims

1. A construction method of a confined space anchor type pile foundation reinforced by a cap beam counter pressure micro steel pipe, characterized in that, Includes the following steps: Step 1, Positioning and Grouting: Install the grouting pipe positioning mold (1) on the bored pile (15) of the existing bridge, and drill through the grouting pipe hole (9) on the grouting pipe positioning mold (1) and grout to form a pile perimeter reinforcement zone; Step 2, Construction of the foundation beam: Construct the foundation beam (19) on the existing connecting beam (14) and reserve the counter-pressure hole (20) on the foundation beam (19); install a square hanging frame (10) on the existing connecting beam (14) and install a square cone mold (11) at the bottom of the square hanging frame (10). The square cone mold (11) is vertically fixed below the connecting beam (14). Then, set up a disc-type bracket for steel bar binding and foundation beam (19) formwork erection, and pour concrete for the foundation beam (19); after the concrete of the foundation beam (19) is poured and cured, remove the square cone mold (11) to form the counter-pressure hole (20). Step 3: Removal of the original connecting beam: The main reinforcement joints of the original connecting beam (14) are retained, and the original connecting beam (14) is removed in sections. Step 4: Pressing in micro steel pipe piles: Using the pier beam (19) completed in Step 2 as the reaction foundation, press the micro steel pipe piles (17) into the soil section by section through the counter-pressure hole (20); Step 5: Reconstruction of the original connecting beam: Reconstruct the connecting beam (14) by connecting the new steel bars with the main reinforcement joints retained in Step 3, so that the top of the micro steel pipe pile (17) is anchored in the newly poured connecting beam (14).

2. The construction method according to claim 1, characterized in that, In step one, the grouting pipe positioning mold (1) includes an L-shaped mold (2) and a straight mold (3) fixed to the first clamp (5) by a connector (4); the first clamp (5) is fastened to the drilled pile (15).

3. The construction method according to claim 1, characterized in that, The square hanging frame (10) is connected to the externally threaded cylinder at the top of the square cone mold (11) via a connecting cap (12) and a connecting cylinder (13) with internal threads.

4. The construction method according to claim 1, characterized in that, In step four, during the pressing process, the segmented steel pipes are aligned and welded by the steel pipe pile extension bracket (18) set on the ground; the steel pipe pile extension bracket (18) includes a base plate (26), a vertical pole (21) and a circular clamp (23) installed on the upper end of the vertical pole (21).

5. The construction method according to claim 1, characterized in that, In step five, the formwork support system used when rebuilding the connecting beam (14) includes: Small support brackets (37) for the middle section of the connecting beam (14), the top of which supports a standardized plastic template (36); and The hanging brackets for both sides of the connecting beam (14) include a square support frame (31) assembled on the cap beam (16) and a double row of hanging rods (32) suspended at its bottom.

6. The construction method according to claim 5, characterized in that, The side formwork of the connecting beam (14) is fixed by a tie rod (35) and a second clamp (33); the second clamp (33) is fastened to the column, one end of the tie rod (35) is connected to the second clamp (33), and the other end passes through the side formwork and presses it tightly.

7. A confined space anchored reinforcement type pile cap beam counter-pressure micro steel pipe reinforced pile foundation, characterized in that, It is produced by using the construction method described in any one of claims 1 to 6.

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