A pile body repairing and reinforcing construction method for soft soil foundation

Abstract

The application discloses a pile body repairing and reinforcing construction method for soft soil foundation, which takes the center of a to-be-repaired pile body in the soft soil foundation as a rotating center, inserts a spiral grouting pipe into soft soil around the pile body through a spiral drilling machine, the spiral grouting pipe has upper and lower end openings, and a high-pressure grouting device is connected to one end of the spiral grouting pipe above the ground; after the spiral drilling machine inserts the spiral grouting pipe into a predetermined position below the ground, the spiral drilling machine reversely rotates, pulls out the spiral grouting pipe upwards while injecting grout from the lower end opening of the spiral grouting pipe to the surroundings of the pile body, and the spiral grouting pipes respectively inject resin and cement slurry to form reinforced bodies with grout and reinforcement, repair the damaged pile body, reinforce the pile body, and improve the bearing capacity of the pile body.

Description

Technical Field

[0001] This invention relates to the field of building construction, and specifically to a method for pile repair and reinforcement of soft soil foundations. Background Technology

[0002] The soil layers in my country's eastern coastal areas are mostly soft soil layers formed by long-term alluvial and siltation from rivers and lakes. These layers are characterized by high water content, high fluidity, and poor bearing capacity. Soft soil has a small internal friction angle and high lateral pressure, making it prone to soil displacement. This displacement and compression of foundation piles can lead to instability and fracture. With the rapid economic development of the eastern coastal areas, the development and construction of soft soil areas is inevitable. Properly addressing the repair and reinforcement of fractured or unstable piles in soft soil foundations will contribute to the overall development of the region and boost economic growth.

[0003] Existing technologies include methods for dealing with pile instability or fracture, such as pile splicing, in-situ re-piling, and pile replacement. However, these treatments are often not very effective in soft soil foundations, and some treatment solutions have long construction cycles, high costs, and certain safety risks. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a construction method for repairing and reinforcing piles in soft soil foundations. This method involves multiple grouting injections using spirals of different diameters around the pile to repair and reinforce the damaged pile, thereby improving its bearing capacity.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] A method for repairing and reinforcing piles in soft soil foundations involves using the center of the pile to be repaired in the soft soil foundation as the rotation center. A spiral grouting conduit is inserted into the soft soil surrounding the pile using a spiral drilling rig. The spiral grouting conduit has openings at both the upper and lower ends, and a high-pressure grouting device is connected to the end of the spiral grouting conduit above ground. After the spiral drilling rig inserts the spiral grouting conduit into a predetermined position below ground, the rig rotates in the opposite direction, simultaneously pulling the spiral grouting conduit upwards while grouting is performed around the pile from the lower opening of the spiral grouting conduit. The grouting includes injecting resin and injecting cement slurry.

[0007] The spiral grouting conduit uses a double-ended threaded connection sleeve, including a first spiral grouting conduit, a second spiral grouting conduit, and a third spiral grouting conduit. The grouting process includes:

[0008] S1: After drilling the first spiral grouting pipe into the predetermined position through the spiral drilling machine, resin is injected around the pile body while pulling it out in the opposite direction; a certain distance is left between the first spiral grouting pipe and the outer wall of the pile body, and the resin is left to stand for a period of time to cure after the injection is completed.

[0009] S2: After drilling the second spiral grouting pipe into the predetermined position using a spiral drilling rig, cement grout is injected around the pile body while simultaneously pulling it out in the reverse direction; the diameter of the second spiral grouting pipe is smaller than that of the first spiral grouting pipe but larger than that of the pile body to be repaired.

[0010] S3: After the third spiral grouting pipe is drilled into the predetermined position by the spiral drilling machine, it is pulled out in the opposite direction and cement grout is injected around the pile body; the diameter of the third spiral grouting pipe is larger than that of the first spiral grouting pipe.

[0011] To optimize the above technical solution, the specific measures / limitations also include:

[0012] The predetermined positions in steps S1, S2 and S3 all refer to 1-2m downwards from the bottom of the pile.

[0013] If the pile is a hollow pile with a through hole in the middle, proceed to step S4 after step S3 is completed:

[0014] S4: High-pressure injection of cement grout through the through hole in the middle of the pile body to form a bond with the already injected cement grout.

[0015] The first and second spiral grouting conduits are constant cross-section conduits; the third spiral grouting conduit is a variable cross-section conduit, with its diameter gradually increasing from top to bottom. The spiral grouting conduits use double-end threaded connection sleeves.

[0016] The horizontal distance between the edge of the first spiral grouting pipe facing the pile body and the outer wall of the pile body is 0.8-1.2m; the horizontal distance between the edge of the second spiral grouting pipe facing the pile body and the outer wall of the pile body is 0.4-0.6m; and the horizontal distance between the edge of the third spiral grouting pipe facing the pile body and the outer wall of the pile body is 1.5-2m.

[0017] The resin mentioned in step S1 is an anchoring resin; after the resin is injected, it is left to stand for a period of time, which is 3-6 minutes.

[0018] Steps S2 and S3 are performed consecutively; if step S4 is included, steps S2, S3, and S4 are performed consecutively.

[0019] The high-pressure grouting device is an air compressor; the grouting pressure in steps S1, S2 and S3 is 2MPa to 2.5MPa.

[0020] The grouting pressure in step S4 is 2MPa to 4MPa.

[0021] The required holding time for grouting is that the holding time after the pressure reaches the design value shall not be less than 5 minutes.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention addresses pile foundations in soft soil geology. When piles break or become unstable, it employs multiple grouting injections using spiral grouting pipes of different diameters to enhance the overall stability and strength of the pile.

[0024] This invention employs a series of spiral grouting conduits of different diameters. Using a low-speed, high-torque spiral drilling rig, the conduits are slowly inserted into the soft soil layer, with the pile diameter as the rotation center. The inserted conduits wind around the pile body like springs. Upon reaching the predetermined position, the drilling rig rotates in the opposite direction, simultaneously pulling the conduits upwards and injecting grout from the lower opening around the pile. Resin and cement grout are injected into the different conduits, ultimately forming a reinforced structure with integrated grout and reinforcement. This structure can repair damaged piles and strengthen existing piles, improving their bearing capacity.

[0025] First, the first spiral grouting pipe injects resin under high pressure around the pile body. After a period of curing, it forms resin reinforcing bars. Cement grout is then injected into the inner side of the resin reinforcing bars using a second spiral grouting pipe to form an inner cement pile body. Its function is to wrap the original pile body and reinforce it with the resin reinforcing bars. Cement grout is then injected into the outer side of the resin reinforcing bars using a third spiral grouting pipe to form an enlarged pile body. Its function is to wrap the resin reinforcing bars to form an enlarged pile. The cement grout injected under high pressure through the central hole of the original pile body is integrated with the cement grout injected through the spiral grouting pipe, which can further enhance the reinforcement effect.

[0026] This invention enables the reinforcement of piles in soft soil foundations by using spiral conduits to wrap and reinforce the piles in layers, forming an axial trapezoidal pile cross-section. This increases the friction between the pile and the soil, thereby achieving an overall reinforcement effect and improving the load-bearing capacity of the pile. Attached Figure Description

[0027] Figure 1 : A schematic diagram of the construction process of the pile repair and reinforcement method for soft soil foundation of the present invention.

[0028] Figure 2 : A schematic diagram of the solidified body formed after the construction of this invention is completed.

[0029] Figure 3 : A schematic diagram of the spiral grouting conduit used in this invention.

[0030] Figure 4 Contour maps showing the displacement distribution of unreinforced piles and reinforced piles according to the present invention; Figure 4 In the diagram, a represents the unreinforced pile body, and b represents the reinforced pile body of the present invention.

[0031] Figure 5Comparison of displacement and deformation between unreinforced piles and reinforced piles of the present invention; Figure 5 In the diagram, a represents the unreinforced pile, b represents the reinforced pile of the present invention, and c represents a comparison of displacement and deformation. Detailed Implementation

[0032] The present invention will be further described in detail below through embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0033] Example 1

[0034] A method for repairing and reinforcing piles in soft soil foundations involves using the center of the pile to be repaired in the soft soil foundation as the rotation center. A spiral grouting conduit is inserted into the soft soil surrounding the pile using a spiral drilling rig. The spiral grouting conduit has openings at both the upper and lower ends, and a high-pressure grouting device is connected to the end of the spiral grouting conduit above ground. After the spiral drilling rig inserts the spiral grouting conduit into a predetermined position below ground, the rig rotates in the opposite direction, pulling the spiral grouting conduit upward while simultaneously grouting around the pile from the lower opening of the spiral grouting conduit. The grouting includes injecting resin and injecting cement slurry.

[0035] The spiral grouting conduit includes a first spiral grouting conduit, a second spiral grouting conduit, and a third spiral grouting conduit. The first and second spiral grouting conduits are conduits with a constant cross-section; the third spiral grouting conduit is a conduit with a variable cross-section, whose diameter gradually increases from top to bottom. The grouting process includes:

[0036] S1: Drill the first spiral grouting conduit into the bottom of the pile body through the spiral drilling machine and then down 1.5m. At the same time, pull it out in the opposite direction and inject anchoring agent resin 115# around the pile body. The grouting pressure is 2Mpa. The horizontal distance between the edge of the first spiral grouting conduit facing the pile body and the outer wall of the pile body is 1m. After the resin injection is completed, let it stand for 5 minutes to cure.

[0037] S2: The second spiral grouting pipe is drilled into the bottom of the pile body by a spiral drilling machine and then 1.5m down. At the same time, it is pulled out in the opposite direction and cement grout is injected around the pile body. The grouting pressure is 2Mpa. The diameter of the second spiral grouting pipe is smaller than that of the first spiral grouting pipe. The horizontal distance between the edge of the second spiral grouting pipe facing the pile body and the outer wall of the pile body is 0.5m.

[0038] S3: The third spiral grouting pipe is drilled into the bottom of the pile body by a spiral drilling machine and then 1.5m down. At the same time, it is pulled out in the opposite direction and cement grout is injected around the pile body. The grouting pressure is 2Mpa. The diameter of the third spiral grouting pipe is larger than that of the first spiral grouting pipe. The horizontal distance between the edge of the third spiral grouting pipe facing the pile body and the outer wall of the pile body is 1.5m.

[0039] The reinforced body formed after the construction of Example 1 is as follows: Figure 2 As shown,

[0040] The performance of the reinforced pile in Embodiment 1 of the present invention was measured through experiments, including displacement distribution contour lines and displacement deformation measurements, as well as a comparison diagram with the unreinforced pile. Figure 4 , Figure 5 The spiral shape shown in the picture is formed after the resin has cured, and it acts like a "steel bar".

[0041] Example 2

[0042] For hollow piles with a through hole in the middle, proceed to step S4 after step S3 is completed:

[0043] S4: Cement grout is injected under high pressure through the through hole in the middle of the pile body at a grouting pressure of 4 MPa, and it is integrated with the injected cement grout.

[0044] The remaining steps are the same as in Example 1.

[0045] This invention can be applied to both solid piles and hollow piles.

[0046] This invention involves injecting resin and cement grout into soft soil foundations using different spiral grouting conduits to form a reinforced structure that integrates grout and reinforcement. This repairs and strengthens damaged piles, improving their bearing capacity. Furthermore, the spiral conduits layer by layer wrap the reinforced piles, forming an axial trapezoidal pile cross-section, which increases the friction between the pile and the soil, thereby achieving an overall reinforcement effect and improving the pile's bearing capacity.

[0047] The spiral grouting conduit in this invention uses a double-ended threaded connection sleeve, which can be connected in sections to the required length according to the construction length.

[0048] The solution of this invention is more suitable for using double-ended threaded connection sleeves, which has advantages over single-spiral grouting pipes. Single-spiral grouting pipes are fixed-length grouting pipes, and for piles of different lengths, the length of the grouting pipe corresponding to the pile length cannot be adjusted; while double-spiral grouting pipes can be connected in sections to form a spiral grouting pipe, so that the required spiral grouting pipe length can be connected according to the actual situation of the project.

[0049] The grouting pressure in the grouting pipe is:

[0050] The pressure for pile side grouting (S1-S3) is 2MPa to 2.5MPa. The lower value is used for large diameter, short pile length, shallow grouting point burial depth and thick mud skin, and the higher value is used for the opposite. The pressure for pile bottom grouting (S4) is 2MPa to 4MPa. The higher value is used for dense clay.

[0051] The required holding time for grouting is that the holding time after the pressure reaches the design value shall not be less than 5 minutes.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for pile repair and reinforcement construction for soft soil foundations, characterized in that: Using the center of the pile to be repaired in the soft soil foundation as the rotation center, a spiral grouting pipe is inserted into the soft soil around the pile using a spiral drilling rig. The spiral grouting pipe has openings at both the upper and lower ends, and a high-pressure grouting device is connected to the end of the spiral grouting pipe above the ground. After the spiral drilling rig inserts the spiral grouting pipe into the predetermined position below the ground, the spiral drilling rig rotates in the opposite direction, pulling the spiral grouting pipe upward while simultaneously grouting from the lower opening of the spiral grouting pipe into the area around the pile. The grouting includes injecting resin and injecting cement slurry. The spiral grouting conduit uses a double-ended threaded connection sleeve, including a first spiral grouting conduit, a second spiral grouting conduit, and a third spiral grouting conduit. The grouting process includes: S1: After drilling the first spiral grouting pipe into the predetermined position through the spiral drilling machine, resin is injected around the pile body while pulling it out in the opposite direction; a distance is left between the first spiral grouting pipe and the outer wall of the pile body, and the resin is left to stand for a period of time to cure after the injection is completed. S2: After drilling the second spiral grouting pipe into the predetermined position using a spiral drilling rig, cement grout is injected around the pile body while simultaneously pulling it out in the reverse direction; the diameter of the second spiral grouting pipe is smaller than that of the first spiral grouting pipe but larger than that of the pile body to be repaired. S3: After the third spiral grouting pipe is drilled into the predetermined position by the spiral drilling rig, cement grout is injected into the pile body while being pulled out in the reverse direction; the diameter of the third spiral grouting pipe is larger than that of the first spiral grouting pipe.

2. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: The predetermined positions in steps S1, S2 and S3 all refer to 1-2m downwards from the bottom of the pile.

3. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: If the pile is a hollow pile with a through hole in the middle, proceed to step S4 after step S3 is completed: S4: High-pressure injection of cement grout through the through hole in the middle of the pile body to form a bond with the already injected cement grout.

4. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: The first and second spiral grouting conduits are conduits with equal cross-sections; the third spiral grouting conduit is a conduit with variable cross-sections, and its diameter gradually increases from top to bottom.

5. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: The horizontal distance between the edge of the first spiral grouting pipe facing the pile body and the outer wall of the pile body is 0.8-1.2m; the horizontal distance between the edge of the second spiral grouting pipe facing the pile body and the outer wall of the pile body is 0.4-0.6m; and the horizontal distance between the edge of the third spiral grouting pipe facing the pile body and the outer wall of the pile body is 1.5-2m.

6. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: The resin mentioned in step S1 is an anchoring resin; after the resin is injected, it is left to stand for a period of time, which is 3-6 minutes.

7. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: Steps S2 and S3 are performed consecutively.

8. The pile repair and reinforcement construction method for soft soil foundation according to claim 1, characterized in that: The high-pressure grouting device is an air compressor; the grouting pressure in steps S1, S2 and S3 is 2MPa to 2.5MPa.

9. The pile repair and reinforcement construction method for soft soil foundation according to claim 3, characterized in that: The grouting pressure in step S4 is 2MPa to 4MPa.

10. The pile repair and reinforcement construction method for soft soil foundation according to claim 8 or 9, characterized in that: The required holding time for grouting is that the holding time after the pressure reaches the design value shall not be less than 5 minutes.

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