Construction method for prefabricated pipe pile to pass through local hard soil layer
By injecting thixotropic mud into precast pipe piles to reduce frictional resistance and subsequently injecting cement grout for reinforcement, the difficulty of driving precast pipe piles through local hard soil layers was solved, achieving efficient and economical construction results and ensuring the bearing capacity and quality of the pile foundation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA CONSTRUCTION SIXTH ENGINEERING DIVISION CO LTD
- Filing Date
- 2026-04-30
- Publication Date
- 2026-05-29
AI Technical Summary
When encountering localized hard soil layers during the construction of precast pipe piles, existing technologies often lead to increased pile driving resistance and pile damage. Furthermore, traditional treatment methods are costly and inefficient, making it difficult to economically and efficiently penetrate hard soil layers while ensuring project quality.
The construction method adopts the approach of first injecting thixotropic mud to reduce frictional resistance, and then injecting cement grout for reinforcement. By setting circumferential grouting diffusion components and sealing plugs inside the precast pipe piles, the thixotropic mud is used to lubricate the pile driving and then replaced with cement grout for reinforcement, ensuring the smooth passage and bearing capacity of the pile foundation.
This enabled the successful penetration of precast pipe piles into localized hard soil layers, ensuring the bearing capacity and construction quality of the pile foundation, reducing costs, and improving construction efficiency and reliability.
Smart Images
Figure CN122106059A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of building engineering, and in particular to a construction method for precast pipe piles to penetrate local hard soil layers. Background Technology
[0002] Precast concrete pipe piles have been widely used in industrial and civil construction, bridges, ports, and other engineering fields due to their advantages such as high single pile bearing capacity, fast construction speed, stable quality, and relatively low cost. However, geological surveys are usually based on a limited number of borehole points, making it difficult to accurately reveal all the changes in the strata in the horizontal and vertical directions. In actual construction, local hard soil layers that are not revealed in the geological survey report are often encountered, such as ancient sand layers, dense gravel layers, calcareous nodule layers, ginger stone layers, or local lenses of hard plastic cohesive soil.
[0003] When encountering such localized hard soil layers during the driving of precast pipe piles, the driving resistance often increases dramatically, leading to pile head damage, pile body cracking, failure to reach the design elevation, or even "refusal to drive." Traditional solutions mainly include: 1. Moving the drilling rig and re-drilling, but this method is costly, inefficient, and may damage adjacent pile foundations; 2. Extending the hammering time to force penetration, which easily causes pile body damage and leaves potential quality issues; 3. Pile cutting, which not only wastes materials but may also reduce bearing capacity due to insufficient pile length, requiring additional piles or design changes, seriously affecting the construction period.
[0004] Therefore, how to solve the problem of precast pipe piles penetrating local hard soil layers economically and efficiently without damaging the pile body and ensuring project quality is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] The present invention aims to address the shortcomings of the prior art by providing a construction method for precast pipe piles to penetrate local hard soil layers.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A construction method for precast pipe piles penetrating locally hard soil layers includes the following steps:
[0008] S1. Driving precast pipe piles:
[0009] Precast pipe piles are composed of multiple pipe pile sections connected together. Each pipe pile section has a central cavity that runs vertically through it. Between the central cavity and the side wall of the pipe pile section, there are several circumferential grouting diffusion components arranged from top to bottom. Each circumferential grouting diffusion component includes several circumferentially distributed pre-embedded steel pipes, and the inner cavity of the pre-embedded steel pipes forms a grouting channel.
[0010] The precast pipe piles are driven into the local hard soil layer, ensuring that the pre-embedded steel pipe of at least one circumferential grouting diffusion component on the precast pipe pile is within the depth range of the local hard soil layer.
[0011] S2. Lowering the grouting pipe:
[0012] A grouting pipe is lowered into the central cavity of the precast pipe pile. The grouting pipe is equipped with two or more sealing plugs. The sealing plugs are sealed to the inner wall of the central cavity. A grouting hole is opened on the side wall of the grouting pipe between two adjacent sealing plugs. The position of the grouting pipe is adjusted so that the grouting hole corresponds to the position of the pre-embedded steel pipe within the depth range of the local hard soil layer.
[0013] S3. Inject drag-reducing mud:
[0014] Thixotropic mud is injected under high pressure through the grouting pipe. The thixotropic mud diffuses into the local hard soil layer through the grouting hole and the grouting channel of the pre-embedded steel pipe in sequence, so as to reduce the frictional resistance between the local hard soil layer and the precast pipe pile interface.
[0015] S4. Continue driving the piles to the design elevation:
[0016] Immediately after injecting thixotropic mud, a driving force is applied to the precast pipe piles to enable them to successfully penetrate the local hard soil layer and sink to the design elevation.
[0017] S5, Replacement cement grout:
[0018] After the precast pipe piles are driven to the design elevation, the grouting pipes are lowered again from the central cavity, so that the grouting holes are aligned with the pre-embedded steel pipes within the depth range of the local hard soil layer. Cement grout is injected under high pressure to replace the previously injected thixotropic mud, filling and reinforcing the gap between the local hard soil layer and the precast pipe pile interface.
[0019] In step S1, a concave-convex fit structure is provided at the connection between adjacent pipe pile sections to prevent relative misalignment of the pipe pile sections during the hammer driving process.
[0020] In step S1, the specific steps for driving the precast pipe piles are as follows:
[0021] Place a T-shaped pile cap on top of the first pipe pile section and drive the pile with a hammer. After the first pipe pile section has sunk to the correct position, remove the T-shaped pile cap from the top of the first pipe pile section. Connect and weld the second pipe pile section to the first pipe pile section using the convex-concave fit structure. Then place the T-shaped pile cap on top of the second pipe pile section and drive the pile again with a hammer. Repeat this process until at least one circumferential grouting diffusion component of the precast pipe pile is located within the depth range of the local hard soil layer.
[0022] Before driving the pile, the outer end of the pre-embedded steel pipe is temporarily sealed with biodegradable tape or foam blocks.
[0023] A rubber or cloth pad is laid between the T-shaped pile cap and the contact surface of the pipe pile section.
[0024] In step S2, the sealing plug is an elastic rubber block, and the diameter of the sealing plug is not less than the inner diameter of the central cavity; the grouting pipe is a steel pipe, and the grouting holes are distributed in a quincunx pattern on the side wall of the grouting pipe. The distance between the sealing plugs and the diameter and number of the grouting holes are adjusted according to the actual situation.
[0025] The thixotropic mud injected in step S3 consists of bentonite, water, and additives, and the proportions are dynamically adjusted according to the density, permeability, and required drag reduction effect of the local hard soil layer 2.
[0026] In step S5, cement grout is injected using a compaction grouting process. The grouting pressure is controlled based on the depth of the local hard soil layer and the pressure of the overlying soil to ensure that the cement grout is evenly diffused in the local hard soil layer.
[0027] After grouting is completed in step S5, cement grout is reinjected into the central cavity. The height of the reinjected cement grout is at least 1 meter higher than the top surface of the local hard soil layer to maintain the stability of the replacement grout.
[0028] The beneficial effects of this invention are: by using the process of "first injecting mud to reduce drag and then injecting cement grout to enhance strength", this invention not only ensures that the pipe pile can successfully penetrate the hard layer, but also ensures the final bearing capacity of the pile foundation. It has the advantages of continuous construction, low cost and reliable quality. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the structure of the present invention;
[0030] Figure 2 This is a schematic diagram of the precast pipe pile in this invention;
[0031] Figure 3 for Figure 2 Sectional view of AA;
[0032] In the diagram: 1-Precast pipe pile; 2-Local hard soil layer; 3-Grouting pipe; 4-Sealing plug; 5-Grouting hole; 6-T-type pile cap;
[0033] 101-Pipe pile section; 102-Central cavity; 103-Embedded steel pipe; 104-Grouting channel; 105-Concave-convex fit structure;
[0034] The following will describe in detail, with reference to the accompanying drawings, embodiments of the present invention. Detailed Implementation
[0035] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.
[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0038] A construction method for precast pipe piles penetrating locally hard soil layers, such as Figure 1 As shown, it includes the following steps:
[0039] S1. Driving precast pipe pile 1:
[0040] Precast pipe pile 1 is composed of multiple pipe pile sections 101 connected together, such as Figure 2 , Figure 3 As shown, the pipe pile section 101 has a central cavity 102 that runs vertically through it. Between the central cavity 102 and the side wall of the pipe pile section 101, there are several circumferential grouting diffusion components arranged from top to bottom. Each circumferential grouting diffusion component includes several circumferentially distributed pre-embedded steel pipes 103. The inner cavity of the pre-embedded steel pipes 103 forms a grouting channel 104. The connection between adjacent pipe pile sections 101 is provided with a concave-convex fitting structure 105 to prevent relative displacement of the pipe pile sections 101 during the hammer driving process.
[0041] The bottom of the first section of the pipe pile, section 101, is equipped with a conical head structure.
[0042] The precast pipe pile 1 is driven into the local hard soil layer 2, ensuring that the pre-embedded steel pipe 103 of at least one circumferential grouting diffusion component on the precast pipe pile 1 is located within the depth range of the local hard soil layer 2.
[0043] The specific steps for driving precast pipe pile 1 are as follows:
[0044] The T-shaped pile cap 6 is placed on top of the first pipe pile section 101. A rubber or cloth pad is laid between the T-shaped pile cap 6 and the pipe pile section 101 to buffer the hammering stress caused by the tamping hammer and avoid damage to the pipe pile. The pile is then driven by dropping the hammer. Before driving the pile, the outer end of the pre-embedded steel pipe 103 is temporarily sealed with biodegradable tape or foam blocks to prevent soil from entering during the sinking process and affecting the subsequent grouting effect. The biodegradable tape and foam blocks can be blown open under high pressure during grouting without affecting the grouting process. Grouting process: After the first section of pipe pile 101 is driven into place, the T-shaped pile cap 6 on the top of the first section of pipe pile 101 is removed. The second section of pipe pile 101 is connected and welded to the concave-convex mating structure 105 of the first section of pipe pile 101. Then the T-shaped pile cap 6 is placed on the top of the second section of pipe pile 101, and the pile is driven by hammering. This process is repeated until at least one circumferential grouting diffusion component of the precast pipe pile 1 is located within the depth range of the local hard soil layer 2.
[0045] S2, Lowering the grouting pipe 3:
[0046] A grouting pipe 3 is lowered into the central cavity 102 of the precast pipe pile 1. The grouting pipe 3 is equipped with two or more sealing plugs 4, which are sealed to the inner wall of the central cavity 102. A grouting hole 5 is opened on the side wall of the grouting pipe 3 between two adjacent sealing plugs 4. The position of the grouting pipe 3 is adjusted so that the grouting hole 5 corresponds to the position of the pre-embedded steel pipe 103 within the depth range of the local hard soil layer 2.
[0047] The sealing plug 4 is an elastic rubber block, and the diameter of the sealing plug 4 is not less than the inner diameter of the central cavity 102; the grouting pipe 3 is a steel pipe, and the grouting holes 5 are distributed in a quincunx pattern on the side wall of the grouting pipe 3. The distance between the sealing plugs 4 and the diameter and number of the grouting holes 5 are adjusted according to the actual situation.
[0048] S3. Inject drag-reducing mud:
[0049] Thixotropic mud is injected under high pressure through grouting pipe 3. The thixotropic mud diffuses into the local hard soil layer 2 through grouting hole 5 and grouting channel 104 of pre-embedded steel pipe 103 in sequence, so as to reduce the frictional resistance between the local hard soil layer 2 and the precast pipe pile 1 interface.
[0050] The thixotropic mud consists of bentonite, water, and additives, with the proportions dynamically adjusted based on the density, permeability, and desired drag reduction effect of the local hard soil layer 2.
[0051] S4. Continue driving the piles to the design elevation:
[0052] Immediately after injecting thixotropic mud, a driving force is applied to the precast pipe pile 1, so that the precast pipe pile 1 can smoothly pass through the local hard soil layer 2 and sink to the design elevation.
[0053] S5, Replacement cement grout:
[0054] After the precast pipe pile 1 is driven to the design elevation, the grouting pipe 3 is lowered again from the central cavity 102, so that the grouting hole 5 is aligned with the pre-embedded steel pipe 103 within the depth range of the local hard soil layer 2. Cement grout is injected under high pressure, and the cement grout replaces the previously injected thixotropic mud, filling and reinforcing the gap between the local hard soil layer 2 and the precast pipe pile 1.
[0055] Cement grout is injected using a compaction grouting process. The grouting pressure is controlled based on the depth of the local hard soil layer 2 and the pressure of the overlying soil to ensure that the cement grout is evenly diffused in the local hard soil layer 2.
[0056] After grouting is completed, cement grout is reinjected into the central cavity 102. The height of the reinjected cement grout is at least 1 meter higher than the top surface of the local hard soil layer 2 to maintain the stability of the replacement grout.
[0057] The present invention achieves precise and uniform grouting at the pile-soil interface by pre-embedding a circumferential grouting channel 104 on the side wall of the precast pipe pile 1, thus avoiding grout waste and disturbance to other soil layers.
[0058] This invention employs a two-step construction process of "first injecting thixotropic mud to reduce drag, then injecting cement grout to reinforce," which cleverly solves the contradiction between the difficulty of pile driving and insufficient bearing capacity. The mud lubrication in the early stage ensures the smooth progress of pile driving, while the cement grout replacement in the later stage restores the frictional resistance of the pile side, ensuring the long-term stability of the pile foundation.
[0059] The present invention utilizes a grouting pipe 3 with double sealing plugs 4 to form a sealed grouting section in the narrow central cavity 102 of the precast pipe pile 1, ensuring that high-pressure grout can only be squeezed out from the predetermined pre-embedded steel pipe 103, thereby improving the reliability and efficiency of construction.
[0060] The concave-convex fit structure 105 at the connection of the pipe pile section 101 of the present invention can effectively transfer energy under the high stress of hammer driving, prevent the pipe section from shifting, and protect the integrity of the precast pipe pile 1.
[0061] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or direct application to other occasions without modification, are all within the protection scope of the present invention.
Claims
1. A construction method for precast pipe piles penetrating locally hard soil layers, characterized in that, Includes the following steps: S1. Driving precast pipe piles (1): The precast pipe pile (1) is composed of multiple pipe pile sections (101) connected together. The pipe pile section (101) has a central cavity (102) that runs vertically through it. Between the central cavity (102) and the side wall of the pipe pile section (101), there are several circumferential grouting diffusion components arranged from top to bottom. Each circumferential grouting diffusion component includes several circumferentially distributed pre-embedded steel pipes (103). The inner cavity of the pre-embedded steel pipes (103) forms a grouting channel (104). The precast pipe pile (1) is driven into the local hard soil layer (2) to ensure that the pre-embedded steel pipe (103) of at least one circumferential grouting diffusion component on the precast pipe pile (1) is within the depth range of the local hard soil layer (2); S2, Lower the grouting pipe (3): A grouting pipe (3) is lowered into the central cavity (102) of the precast pipe pile (1). The grouting pipe (3) is provided with two or more sealing plugs (4). The sealing plugs (4) are sealed to the inner wall of the central cavity (102). A grouting hole (5) is opened between two adjacent sealing plugs (4) on the side wall of the grouting pipe (3). The position of the grouting pipe (3) is adjusted so that the grouting hole (5) corresponds to the position of the pre-embedded steel pipe (103) within the depth range of the local hard soil layer (2). S3. Inject drag-reducing mud: Thixotropic mud is injected under high pressure through the grouting pipe (3). The thixotropic mud diffuses into the local hard soil layer (2) through the grouting hole (5) and the grouting channel (104) of the pre-embedded steel pipe (103) in sequence, so as to reduce the frictional resistance between the local hard soil layer (2) and the precast pipe pile (1). S4. Continue driving the piles to the design elevation: Immediately after injecting thixotropic mud, a driving force is applied to the precast pipe pile (1) so that the precast pipe pile (1) can smoothly pass through the local hard soil layer (2) and sink to the design elevation. S5, Replacement cement grout: After the precast pipe pile (1) is sunk to the design elevation, the grouting pipe (3) is lowered again from the central cavity (102) so that the grouting hole (5) is aligned with the pre-embedded steel pipe (103) within the depth range of the local hard soil layer (2) and cement grout is injected under high pressure. The cement grout replaces the previously injected thixotropic mud, filling and reinforcing the gap between the local hard soil layer (2) and the precast pipe pile (1).
2. The construction method for precast pipe piles penetrating locally hard soil layers according to claim 1, characterized in that, In step S1, a concave-convex fit structure (105) is provided at the connection of adjacent pipe pile sections (101) to prevent relative displacement of the pipe pile sections (101) during the hammer driving process.
3. The construction method for precast pipe piles penetrating locally hard soil layers according to claim 2, characterized in that, In step S1, the specific steps for the installation of precast pipe piles (1) are as follows: Place the T-shaped pile cap (6) on top of the first section of the pipe pile (101) and drive the pile with a hammer. After the first section of the pipe pile (101) has sunk to the position, remove the T-shaped pile cap (6) from the top of the first section of the pipe pile (101), connect and weld the concave-convex fit structure (105) of the second section of the pipe pile (101) to the first section of the pipe pile (101), then place the T-shaped pile cap (6) on top of the second section of the pipe pile (101) and drive the pile with a hammer. Repeat this process until at least one circumferential grouting diffusion component of the precast pipe pile (1) is located within the depth range of the local hard soil layer (2).
4. A construction method for precast pipe piles penetrating locally hard soil layers according to claim 3, characterized in that, Before driving the pile, the outer end of the pre-embedded steel pipe (103) is temporarily sealed with biodegradable tape or foam blocks.
5. A construction method for precast pipe piles penetrating locally hard soil layers according to claim 3, characterized in that, A rubber pad or cloth pad is laid between the contact surface of the T-shaped pile cap (6) and the pipe section (101).
6. A construction method for precast pipe piles penetrating locally hard soil layers according to claim 1, characterized in that, In step S2, the sealing plug (4) is an elastic rubber block, and the diameter of the sealing plug (4) is not less than the inner diameter of the central cavity (102); the grouting pipe (3) is a steel pipe, and the grouting holes (5) are distributed in a plum blossom shape on the side wall of the grouting pipe (3). The distance between the sealing plugs (4) and the diameter and number of the grouting holes (5) are adjusted according to the actual situation.
7. A construction method for precast pipe piles penetrating locally hard soil layers according to claim 1, characterized in that, The thixotropic mud injected in step S3 consists of bentonite, water and additives, and the ratio is dynamically adjusted according to the density, permeability and required drag reduction effect of the local hard soil layer (2).
8. A construction method for precast pipe piles penetrating locally hard soil layers according to claim 1, characterized in that, In step S5, cement grout is injected using a compaction grouting process. The grouting pressure is controlled based on the depth of the local hard soil layer (2) and the pressure of the overlying soil to ensure that the cement grout is evenly diffused in the local hard soil layer (2).
9. A construction method for precast pipe piles penetrating locally hard soil layers according to claim 8, characterized in that, After grouting is completed in step S5, cement grout is injected back into the central cavity (102). The height of the injected cement grout is at least 1 meter higher than the top surface of the local hard soil layer (2) to maintain the stability of the replacement grout.