Post-grouting FRP steel pipe pile construction method and device and miniature composite pile

Abstract

The invention provides a post-grouting FRP steel pipe pile construction method and device and a miniature composite pile. The method comprises the steps that firstly, bottom positioning parameters of a composite pile comprising multiple sections of pile body rod units are obtained, and according to the bottom positioning parameters, segmented grouting equipment comprising an air bag, an air injection hose and a grouting hose is hoisted to the bottom of the pile; the air bag is inflated through the air injection hose to form a closed grouting space; cement paste is injected into the space through a grouting hose, and the cement paste is injected into an external soil body around the pile body rod unit through a one-way circulation hole in the pile body rod unit; when the interior of the pile body of the composite pile is filled with cement paste and external grouting is completed, grouting is stopped, and air in the air bag is released; and the equipment is lifted to the previous section of pile body rod unit, and the steps are repeated till full-length grouting of the pile body is completed. Through precise positioning, segmented grouting and intelligent control, it is ensured that the pile body and soil around the pile are filled with cement paste, the bearing capacity and corrosion resistance of a pile foundation are enhanced, and efficient and durable foundation reinforcement is achieved.

Description

Technical Field

[0001] The present application belongs to the field of grouting pile foundation, and in particular relates to a post-grouting FRP steel pipe pile construction method, device and micro composite pile. Background Art

[0002] Coastal soft soil areas have low bearing capacity, high compressibility, and are prone to settlement. Furthermore, soft soil in marine sedimentary environments is susceptible to seawater erosion, placing high demands on the corrosion resistance of foundation reinforcement materials. Traditional foundation treatment methods struggle to effectively control settlement, especially in confined spaces like substation renovations and expansions, where large machinery cannot operate. Therefore, an efficient, durable foundation reinforcement technology that is adaptable to confined spaces is urgently needed. Summary of the Invention

[0003] The purpose of this application is to overcome the defects in the above-mentioned prior art and provide a post-grouting FRP steel pipe pile construction method, device and micro composite pile.

[0004] The present application provides a post-grouting FRP steel pipe pile construction method, comprising:

[0005] S1 obtains positioning parameters of the bottom of a composite pile, where the composite pile includes multiple pile shaft units;

[0006] S2: hanging and placing the segmented grouting equipment to the bottom of the composite pile according to the positioning parameters, wherein the segmented grouting equipment includes an air bag, an air injection hose, and a grouting hose;

[0007] S3: Inflate the airbag through the air injection hose to form a closed grouting space;

[0008] S4: injecting cement slurry into the enclosed grouting space through the grouting hose, and injecting the cement slurry into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit;

[0009] S5: When the cement slurry fills the interior of the composite pile and the external soil grouting is completed, stop grouting;

[0010] S6 releases the gas in the airbag;

[0011] S7: lifting the segmented grouting equipment to the upper pile shaft unit;

[0012] S8 repeats steps S3 to S7 until the full-length grouting of the pile is completed.

[0013] Optionally, the airbag includes:

[0014] The diameter of the airbag after inflation is greater than the inner diameter of the pile body, and the number of the airbags is set according to the segmented length of the pile body.

[0015] Optionally, the pile shaft unit comprises: a steel pipe and an FRP material layer on the outer surface of the steel pipe;

[0016] The FRP material layer and the steel pipe are coated with epoxy resin gradient to form a composite anti-corrosion layer, and the surface of the pile shaft rod unit is provided with a coarse sand friction layer.

[0017] Optionally, the composite pile further comprises: a GFRP pile head;

[0018] The GFRP pile head is provided with a cross-pointed pressure plate, the cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole is provided inside the GFRP pile head, and a one-way valve is configured in the rear grouting hole;

[0019] After the full-length grouting of the pile is completed, secondary grouting is performed through the preset pile top closed grouting connector, including: when the grouting pressure exceeds the preset threshold, the one-way valve opens to allow cement slurry to penetrate the post-grouting hole and be injected into the external soil, while the one-way valve prevents soil moisture from flowing back.

[0020] Optionally, when cement slurry is injected into the enclosed grouting space through the grouting hose and the cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit, the method includes:

[0021] The cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole provided on the pile shaft rod unit. A double-restriction ring anti-backflow structure is provided in the one-way flow hole.

[0022] The present application also provides a post-grouting FRP steel pipe pile construction device, comprising:

[0023] An acquisition module is used to acquire positioning parameters of the bottom of a composite pile, where the composite pile includes multiple pile shaft units;

[0024] A hanging module is used to hang and place the segmented grouting equipment to the bottom of the composite pile according to the positioning parameters, wherein the segmented grouting equipment includes an air bag, an air injection hose and a grouting hose;

[0025] An inflation module, for inflating the air bag through the air injection hose to form a closed grouting space;

[0026] A grouting module, injecting cement slurry into the closed grouting space through the grouting hose, and the cement slurry is injected into the external soil around the pile shaft unit through the one-way flow hole on the pile shaft unit;

[0027] The stopping module stops grouting when the cement slurry fills the interior of the composite pile and the external soil grouting is completed; the gas in the air bag is released; the segmented grouting equipment is lifted to the upper pile shaft unit; and the inflation module is repeated to the stopping module until the grouting of the entire length of the pile is completed.

[0028] Optionally, the airbag includes:

[0029] The diameter of the airbag after inflation is greater than the inner diameter of the pile body, and the number of the airbags is set according to the segmented length of the pile body.

[0030] Optionally, the pile shaft unit comprises: a steel pipe and an FRP material layer on the outer surface of the steel pipe;

[0031] The FRP material layer and the steel pipe are coated with epoxy resin gradient to form a composite anti-corrosion layer, and the surface of the pile shaft rod unit is provided with a coarse sand friction layer.

[0032] Optionally, the composite pile further comprises: a GFRP pile head;

[0033] The GFRP pile head is provided with a cross-pointed pressure plate, the cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole is provided inside the GFRP pile head, and a one-way valve is configured in the rear grouting hole;

[0034] After the full-length grouting of the pile is completed, secondary grouting is performed through the preset pile top closed grouting connector, including: when the grouting pressure exceeds the preset threshold, the one-way valve opens to allow cement slurry to penetrate the post-grouting hole and be injected into the external soil, while the one-way valve prevents soil moisture from flowing back.

[0035] Optionally, the grouting module injects cement slurry into the closed grouting space through the grouting hose, and the cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit, comprising:

[0036] The cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole provided on the pile shaft rod unit. A double-restriction ring anti-backflow structure is provided in the one-way flow hole.

[0037] The present application also provides a post-grouting FRP steel pipe micro composite pile, comprising a GFRP pile head, a pile end rod unit and at least one pile body rod unit;

[0038] The GFRP pile head, pile end rod unit and at least one pile shaft rod unit are connected in sequence from bottom to top;

[0039] The pile shaft unit is composed of a steel pipe covered with an FRP material layer, and the FRP material layer and the steel pipe are gradiently coated with epoxy resin to form a composite anti-corrosion layer;

[0040] The side wall of the pile shaft rod unit is provided with a one-way flow hole, and a double-layer anti-backflow structure consisting of an inner restriction ring and an outer restriction ring is provided in the one-way flow hole. The inner restriction ring is hinged to the flow hole baffle through a rotating shaft, and the flow hole baffle is kept in a closed state under the action of a torsion spring;

[0041] A cross-pointed pressure plate is provided at the end of the GFRP pile head. The cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole equipped with a one-way valve is provided inside the GFRP pile head.

[0042] The beneficial effects of this application are:

[0043] The present application provides a post-grouting FRP steel pipe pile construction method, comprising: S1 obtaining positioning parameters of the bottom of a composite pile, the composite pile comprising multiple pile shaft rod units; S2 hanging and lowering a segmented grouting device to the bottom of the composite pile according to the positioning parameters, the segmented grouting device comprising an air bag, an air injection hose, and a grouting hose; S3 inflating the air bag through the air injection hose to form a closed grouting space; S4 injecting cement slurry into the closed grouting space through the grouting hose, the cement slurry being injected into the external soil around the pile shaft rod unit through a one-way flow hole on the pile shaft rod unit; S5 stopping grouting when the cement slurry fills the interior of the composite pile and grouting of the external soil is completed; S6 releasing the gas in the air bag; S7 lifting the segmented grouting device to the upper pile shaft rod unit; and S8 repeating steps S3 to S7 until grouting of the entire length of the pile body is completed. This application ensures that the cement slurry fully fills the pile body and the soil around the pile through precise positioning, segmented grouting and intelligent control of the grouting process, effectively enhances the bearing capacity and anti-corrosion performance of the pile foundation, and realizes efficient and durable foundation reinforcement in a limited space. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the construction process of post-grouting FRP steel pipe piles in this application;

[0045] Figure 2 It is a schematic diagram of the overall structure of the micro composite pile in this application;

[0046] Figure 3 Schematic diagram of the pile shaft unit and connector of the micro composite pile in this application;

[0047] Figure 4 Schematic diagram of the cross-sectional structure of the one-way flow hole of the micro composite pile in this application;

[0048] Figure 5 Schematic diagram of the internal structure of the GFRP pile head of the micro composite pile in this application;

[0049] Figure 6 This is a schematic diagram of the structure of the closed grouting connector at the top of the micro composite pile in this application;

[0050] Figure 7 is a schematic diagram of the pile cap structure of the micro composite pile in this application;

[0051] Figure 8Schematic diagram of the cross-sectional structure of the GFRP pile head of the micro composite pile in this application;

[0052] Figure 9 This is a schematic diagram of the one-way flow hole structure of the micro composite pile in this application;

[0053] Figure 10 It is a schematic diagram of the structure of the segmented grouting equipment of the micro composite pile in this application;

[0054] Figure 11 It is a schematic diagram of the construction of micro composite piles in this application. DETAILED DESCRIPTION

[0055] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it is understood that various forms of implementing the present disclosure are not limited by the embodiments set forth herein. Rather, the embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0056] The present application provides a post-grouting FRP steel pipe pile construction method, which is implemented based on a post-grouting FRP steel pipe micro-composite pile provided in the present application.

[0057] Please refer to Figures 1 to 10 As shown, the pile end rod unit 1 of the pile is equipped with an upper pile end joint 11 and a lower pile end joint 12, and the pile body rod unit 2 includes a steel pipe 23, an FRP material layer 24, a coarse sand surface 25, an upper pile body joint 21 with an internal thread, and a lower pile body joint 22 with an external thread. The rod units are quickly connected and disassembled through threads, which facilitates flexible combination according to different pile length requirements, thereby improving construction adaptability and efficiency.

[0058] The composite structure formed by the steel pipe 23 and the FRP material layer 24 has both the high strength characteristics of FRP and the corrosion resistance advantages of the steel pipe.

[0059] By increasing the roughness of the pile surface, such as a coarse sand surface 25, the friction between the pile and the soil can be significantly enhanced, thereby improving the bearing capacity of the pile.

[0060] The segmented grouting equipment 3 integrates components such as a grouting pipe connector 31, a slurry outlet pipe 32, and an air bag 33. The air bag 33 is inflated to form a closed grouting space, which can effectively prevent cement slurry leakage during the grouting process and ensure the stability of the grouting pressure and the grouting effect.

[0061] The air injection hose 37 and the air injection machine 38 respectively regulate the expansion pressure of the air bag 33, flexibly adjusting the grouting parameters according to various geological conditions. The L-shaped flow channel formed by the slurry outlet 35 and the grouting hose 39 prevents the slurry from flowing back.

[0062] The air injection machine 38 and the air bag 33 work together to enhance the sealing reliability and adapt to the grouting needs under complex geological conditions. The GFRP pile head 5 is equipped with an external threaded pile head connecting screw 51, a cross-pointed pressure plate 52 and a pile head rear grouting hole 53 and a one-way valve is set inside the rear grouting hole 53.

[0063] The externally threaded pile head connecting screw 51 facilitates quick connection with the pile end rod unit 1, the cross-pointed pressure plate 52 facilitates penetration of the soil layer, and a one-way valve structure is configured inside the pile head rear grouting hole 53 to realize pressure grouting, which can further fill the external soil gap and improve the pile end bearing capacity and pile stability.

[0064] The pile top sealed grouting connector 6 is equipped with a grouting port 61 , an external threaded grouting connector 62 , a grouting top plate 63 and a sealed rubber pad 64 .

[0065] The external thread connection cooperates with the sealed rubber pad 64 to ensure the sealing of the grouting.

[0066] The one-way flow hole 7 structure includes an external connecting frame 71, an inner limiting ring 72, a flow hole baffle 73, an outer limiting ring 74 and a rotating shaft 75. The inner limiting ring 72 and the outer limiting ring 74 form a double insurance anti-backflow structure to achieve one-way flow control of cement slurry, prevent cement slurry from flowing back into the pile, and ensure the quality of grouting.

[0067] The rotating shaft 75 is provided with a torsion spring to automatically reset the flow hole baffle 73, thereby preventing external impurities from entering the pile body and improving the durability and safety of the pile body.

[0068] The pile shaft rod unit 2 has a length of 1-2m and a diameter of 100-200mm, making it extremely convenient to transport and carry, and reducing the difficulty of construction. The internal thread of the upper joint 21 of the pile shaft cooperates with the external thread of the lower joint 22 of the pile shaft to achieve a threaded connection. This design allows construction personnel to quickly and flexibly connect multiple pile shaft rod units 2 according to the actual pile length requirements. The threaded connection method not only has high connection strength and stability, but also can effectively transmit force when the pile body is subjected to vertical and horizontal loads, ensuring the integrity and stability of the pile body. Its self-locking property can prevent the pile shaft rod unit 2 from loosening or disjointing when subjected to force, thereby enhancing the reliability and safety of the pile body.

[0069] The pile cap 4 is provided with a pile cap bearing head 41 and a connecting nut 42 . The connecting nut 42 is provided with an external thread and is connected to the pile shaft upper joint 21 of the pile shaft rod unit 2 through a threaded connection.

[0070] The pile cap bearing head 41 can disperse the load on the top of the pile body and transfer it evenly to the pile body rod unit 2, avoiding local excessive load from damaging the pile body. At the same time, the threaded connection between the pile cap 4 and the pile body rod unit 2 provides pre-tightening force, thereby enhancing the connection strength and bearing capacity of the pile body top and improving the overall stability of the pile body.

[0071] The closed end 36 of the segmented grouting equipment 3 is precisely positioned with the help of the fixing ring 34, which stabilizes the grouting position and ensures that the grouting operation is carried out smoothly at the preset position throughout the process. The air bag 33 realizes independent expansion pressure control through the air injection hose 37. The construction personnel can flexibly adjust the grouting pressure according to the geological conditions and grouting requirements. Whether it is a loose sandy soil layer or a dense clay layer, accurate grouting can be achieved, which enhances the adaptability of the equipment to complex geological conditions.

[0072] The slurry outlet 35 and the grouting hose 39 form an L-shaped flow channel, which effectively prevents the slurry from flowing back. Its unique design ensures unidirectional flow of the slurry, ensures continuous and stable grouting, avoids grouting interruptions, and reduces the mixing of slurry bubbles, improves the density and strength of the cement slurry, and ensures that the soil gaps around the pile are fully filled.

[0073] The gas injection machine 38 provides gas pressure for the air bag 33 so that it fits inside the pile body to form a closed grouting space, effectively preventing cement slurry leakage and ensuring stable grouting pressure.

[0074] The GFRP pile head features a symmetrical four-edged structure, with the cutting edge angle of its cross-pointed pressure plate at 30°±1°. This design allows the pile head to cut the soil from four directions simultaneously when it is driven into the soil, significantly improving the efficiency of soil penetration and thus shortening construction time. Furthermore, the grouting holes behind the pile head are equipped with a one-way valve structure, allowing cement slurry to flow unidirectionally into the external soil voids, effectively preventing the backflow of soil moisture and impurities. Through this pressure grouting technology, the external soil voids are densely filled, thereby improving the bearing capacity of the soil at the pile end.

[0075] Installation of FRP steel pipe micro composite piles:

[0076] The GFRP pile head 5 is tightly screwed into the pile end rod unit 1. After selecting a suitable piling location, the piling equipment is activated and the assembled GFRP pile head 5 and pile end rod unit 1 are slowly pressed into the soil. The FRP material layer 24 on the pile body has excellent corrosion resistance, effectively resisting chloride ion erosion of the pile structure. At the same time, the coarse sand surface 25 design enhances friction between the pile body and the surrounding soil, promoting a close bond between the pile body and the soil, thereby improving the bearing capacity of the pile foundation.

[0077] Pile connection:

[0078] Stop pressing the pile when the pile body is pressed into the soil until the upper joint 11 of the pile end, screw and connect the lower joint 22 of the pile body rod unit 2 and the upper joint 11 of the pile end rod unit 1 that has been pressed into the soil, and press the pile. Repeat this step and connect the remaining pile body rod units 2 until the composite pile reaches the set soil layer.

[0079] Please refer to Figure 11As shown, the present application provides a post-grouting FRP steel pipe pile construction method, comprising:

[0080] S1, obtaining positioning parameters of the bottom of a composite pile, where the composite pile includes multiple pile shaft units;

[0081] The pile bottom coordinates are determined by the end position of the pressed-in pile end rod unit 1 (the position exposed by the pile end upper joint 11).

[0082] S2. Hanging a segmented grouting device to the bottom of the composite pile according to the positioning parameters, wherein the segmented grouting device includes an air bag, an air injection hose, and a grouting hose;

[0083] The segmented grouting equipment 3 is hoisted and placed at the bottom of the composite pile. The closed end 36 of the segmented grouting equipment 3 is adjusted so that the segmented grouting equipment 3 is located at the center of the composite pile. The segmented grouting equipment 3 is vertically hoisted into the composite pile hole by a lifting device. The closed end 36 is adjusted so that it contacts the bottom of the pile end rod unit 1, ensuring that the equipment axis coincides with the center of the pile body.

[0084] S3, inflating the airbag through the air injection hose to form a closed grouting space;

[0085] The air injection hose 37 is connected to the air injection pipe joint 311 to inflate the air bag 33 to ensure that the air bag fits tightly to the pile rod unit to construct a closed grouting space.

[0086] S4, injecting cement slurry into the closed grouting space through the grouting hose, and injecting the cement slurry into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit;

[0087] After starting the grouting machine 310, cement slurry flows into the L-shaped flow channel through the grouting hose 39 and is finally injected into the confined space from the grouting port 35. Under the action of the grouting pressure, the slurry fills the interior of the pile shaft unit 2 and penetrates to the outside through the preset one-way flow hole 7.

[0088] S5. When the cement slurry fills the interior of the composite pile and the external soil grouting is completed, stop grouting;

[0089] Under the action of internal pressure, the cement slurry will flow into the external soil through the one-way flow hole 7 provided on the pile body rod unit and form cement soil with the external soil. The one-way flow hole 7 is provided with an inner limiting ring 72 to prevent the cement slurry from flowing back into the pile. After grouting of a section of rod unit is completed, the grouting is stopped.

[0090] S6. releasing the gas in the airbag;

[0091] The gas in the airbag 33 is extracted through the air injection hose 37 to return the airbag 33 to its initial deflated state.

[0092] S7, lifting the segmented grouting equipment to the upper pile shaft unit;

[0093] The segmented grouting equipment 3 is hoisted upwards to the upper rod unit.

[0094] S8. Repeat steps S3 to S7 until the grouting along the entire length of the pile is completed.

[0095] Repeat this step to complete the grouting of the entire composite pile.

[0096] Furthermore, full pile reinforcement grouting:

[0097] The grouting portion 62 of the sealed grouting connector 6 at the pile top is tightly screwed into the upper joint 21 of the pile shaft unit 2. Cement grout is then poured into the composite pile through the grouting port 61. Under the action of internal pressure, the grout smoothly passes through the grouting holes 53 of the GFRP pile head 5 and flows into the soil outside the pile body, where it merges with the external soil to form a solid cement-soil. Simultaneously, the internal pressure ensures that the grout completely fills the tiny gaps within the pile body, significantly improving the overall safety of the pile foundation.

[0098] Pile cap installation:

[0099] The connecting nut 42 of the pile cap 4 is screwed and connected to the upper joint 21 of the pile shaft rod unit 2 to complete the installation of the pile foundation.

[0100] The present application also provides a post-grouting FRP steel pipe pile construction device, comprising:

[0101] An acquisition module is used to acquire positioning parameters of the bottom of a composite pile, where the composite pile includes multiple pile shaft units;

[0102] A hanging module is used to hang and place the segmented grouting equipment to the bottom of the composite pile according to the positioning parameters, wherein the segmented grouting equipment includes an air bag, an air injection hose and a grouting hose;

[0103] An inflation module, for inflating the air bag through the air injection hose to form a closed grouting space;

[0104] A grouting module, injecting cement slurry into the closed grouting space through the grouting hose, and the cement slurry is injected into the external soil around the pile shaft unit through the one-way flow hole on the pile shaft unit;

[0105] The stopping module stops grouting when the cement slurry fills the interior of the composite pile and the external soil grouting is completed; the gas in the air bag is released; the segmented grouting equipment is lifted to the upper pile shaft unit; and the inflation module is repeated to the stopping module until the grouting of the entire length of the pile is completed.

[0106] Furthermore, the airbag includes:

[0107] The diameter of the airbag after inflation is greater than the inner diameter of the pile body, and the number of the airbags is set according to the segmented length of the pile body.

[0108] Furthermore, the pile shaft unit comprises: a steel pipe and an FRP material layer on the outer surface of the steel pipe;

[0109] The FRP material layer and the steel pipe are coated with epoxy resin gradient to form a composite anti-corrosion layer, and the surface of the pile shaft rod unit is provided with a coarse sand friction layer.

[0110] Furthermore, the composite pile further comprises: a GFRP pile head;

[0111] The GFRP pile head is provided with a cross-pointed pressure plate, which adopts a four-edged symmetrical structure. A rear grouting hole is provided inside the GFRP pile head, and a one-way valve is configured in the rear grouting hole.

[0112] Furthermore, the grouting module injects cement slurry into the closed grouting space through the grouting hose, and the cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit, including:

[0113] The cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole provided on the pile shaft rod unit. A double-restriction ring anti-backflow structure is provided in the one-way flow hole.

[0114] like Figures 1 to 10 As shown, the present application also provides a post-grouting FRP steel pipe micro composite pile, comprising a GFRP pile head, a pile end rod unit and at least one pile body rod unit;

[0115] The GFRP pile head, pile end rod unit and at least one pile shaft rod unit are connected in sequence from bottom to top;

[0116] The pile shaft unit is composed of a steel pipe covered with an FRP material layer, and the FRP material layer and the steel pipe are gradiently coated with epoxy resin to form a composite anti-corrosion layer;

[0117] The side wall of the pile shaft rod unit is provided with a one-way flow hole, and a double-layer anti-backflow structure consisting of an inner restriction ring and an outer restriction ring is provided in the one-way flow hole. The inner restriction ring is hinged to the flow hole baffle through a rotating shaft, and the flow hole baffle is kept in a closed state under the action of a torsion spring;

[0118] A cross-pointed pressure plate is provided at the end of the GFRP pile head. The cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole equipped with a one-way valve is provided inside the GFRP pile head.

[0119] The pile end rod unit 1 is equipped with an upper pile end joint 11 and a lower pile end joint 12. The pile body rod unit 2 includes a steel pipe 23, an FRP material layer 24, a coarse sand surface 25, an upper pile body joint 21 with an internal thread, and a lower pile body joint 22 with an external thread. The rod units are quickly connected and disassembled through threads, which facilitates flexible combination according to different pile length requirements, thereby improving construction adaptability and efficiency.

[0120] The composite structure formed by the steel pipe 23 and the FRP material layer 24 not only has the high strength characteristics of FRP, but also inherits the corrosion resistance advantages of the steel pipe.

[0121] By increasing the roughness of the pile surface, such as a coarse sand surface 25, the friction between the pile and the soil can be significantly enhanced, thereby improving the bearing capacity of the pile.

[0122] The segmented grouting equipment 3 integrates components such as a grouting pipe connector 31, a slurry outlet pipe 32, and an air bag 33. The air bag 33 is inflated to form a closed grouting space, which can effectively prevent cement slurry leakage during the grouting process and ensure the stability of the grouting pressure and the grouting effect.

[0123] The air injection hose 37 and the air injection machine 38 respectively regulate the expansion pressure of the air bag 33, flexibly adjusting the grouting parameters according to various geological conditions. The L-shaped flow channel formed by the slurry outlet 35 and the grouting hose 39 prevents the slurry from flowing back.

[0124] The air injection machine 38 and the air bag 33 work together to enhance the sealing reliability and adapt to the grouting needs under complex geological conditions. The GFRP pile head 5 is equipped with an external threaded pile head connecting screw 51, a cross-pointed pressure plate 52 and a pile head rear grouting hole 53.

[0125] The externally threaded pile head connecting screw 51 facilitates quick connection with the pile end rod unit 1, the cross-pointed pressure plate 52 facilitates penetration of the soil layer, and the grouting hole 53 behind the pile head is equipped with a one-way valve structure to realize pressure grouting, which can further fill the external soil voids and improve the pile end bearing capacity and pile stability.

[0126] The pile top sealed grouting connector 6 is equipped with a grouting port 61 , an external threaded grouting connector 62 , a grouting top plate 63 and a sealed rubber pad 64 .

[0127] The external thread connection cooperates with the sealed rubber pad 64 to ensure the sealing of the grouting.

[0128] The one-way flow hole 7 structure includes an external connecting frame 71, an inner limiting ring 72, a flow hole baffle 73, an outer limiting ring 74 and a rotating shaft 75. The inner limiting ring 72 and the outer limiting ring 74 form a double insurance anti-backflow structure to achieve one-way flow control of cement slurry, prevent cement slurry from flowing back into the pile, and ensure the quality of grouting.

[0129] The rotating shaft 75 is provided with a torsion spring to automatically reset the flow hole baffle 73, thereby preventing external impurities from entering the pile body and improving the durability and safety of the pile body.

[0130] The pile shaft rod unit 2 has a length of 1-2m and a diameter of 100-200mm, making it extremely convenient to transport and carry, and reducing the difficulty of construction. The internal thread of the upper joint 21 of the pile shaft cooperates with the external thread of the lower joint 22 of the pile shaft to achieve a threaded connection. This design allows construction personnel to quickly and flexibly connect multiple pile shaft rod units 2 according to the actual pile length requirements. The threaded connection method not only has high connection strength and stability, but also can effectively transmit force when the pile body is subjected to vertical and horizontal loads, ensuring the integrity and stability of the pile body. Its self-locking property can prevent the pile shaft rod unit 2 from loosening or disjointing when subjected to force, thereby enhancing the reliability and safety of the pile body.

[0131] The pile cap 4 is provided with a pile cap bearing head 41 and a connecting nut 42 . The connecting nut 42 is provided with an external thread and is connected to the pile shaft upper joint 21 of the pile shaft rod unit 2 through a threaded connection.

[0132] The pile cap bearing head 41 can disperse the load on the top of the pile body and transfer it evenly to the pile body rod unit 2, avoiding local excessive load from damaging the pile body. At the same time, the threaded connection between the pile cap 4 and the pile body rod unit 2 provides pre-tightening force, thereby enhancing the connection strength and bearing capacity of the pile body top and improving the overall stability of the pile body.

[0133] The closed end 36 of the segmented grouting equipment 3 is precisely positioned with the help of the fixing ring 34, which stabilizes the grouting position and ensures that the grouting operation is carried out smoothly at the preset position throughout the process. The air bag 33 realizes independent expansion pressure control through the air injection hose 37. The construction personnel can flexibly adjust the grouting pressure according to the geological conditions and grouting requirements. Whether it is a loose sandy soil layer or a dense clay layer, accurate grouting can be achieved, which enhances the adaptability of the equipment to complex geological conditions.

[0134] The slurry outlet 35 and the grouting hose 39 form an L-shaped flow channel, which effectively prevents the slurry from flowing back. Its unique design ensures unidirectional flow of the slurry, ensures continuous and stable grouting, avoids grouting interruptions, and reduces the mixing of slurry bubbles, improves the density and strength of the cement slurry, and ensures that the soil gaps around the pile are fully filled.

[0135] The gas injection machine 38 provides gas pressure for the air bag 33 so that it fits inside the pile body to form a closed grouting space, effectively preventing cement slurry leakage and ensuring stable grouting pressure.

[0136] The GFRP pile head features a symmetrical four-edged structure, with the cutting edge angle of its cross-pointed pressure plate at 30°±1°. This design allows the pile head to cut the soil from four directions simultaneously when it is driven into the soil, significantly improving the efficiency of soil penetration and thus shortening construction time. Furthermore, the grouting holes behind the pile head are equipped with a one-way valve structure, allowing cement slurry to flow unidirectionally into the external soil voids, effectively preventing the backflow of soil moisture and impurities. Through this pressure grouting technology, the external soil voids are densely filled, thereby improving the bearing capacity of the soil at the pile end.

[0137] Installation of FRP steel pipe micro composite piles:

[0138] The GFRP pile head 5 is tightly screwed into the pile end rod unit 1. After selecting a suitable piling location, the piling equipment is activated and the assembled GFRP pile head 5 and pile end rod unit 1 are slowly pressed into the soil. The FRP material layer 24 on the pile body has excellent corrosion resistance, effectively resisting chloride ion erosion of the pile structure. At the same time, the coarse sand surface 25 design enhances friction between the pile body and the surrounding soil, promoting a close bond between the pile body and the soil, thereby improving the bearing capacity of the pile foundation.

[0139] Pile connection:

[0140] Stop pressing the pile when the pile body is pressed into the soil until the upper joint 11 of the pile end, screw and connect the lower joint 22 of the pile body rod unit 2 and the upper joint 11 of the pile end rod unit 1 that has been pressed into the soil, and press the pile. Repeat this step and connect the remaining pile body rod units 2 until the composite pile reaches the set soil layer.

[0141] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to the above embodiments can be made, and the general principles described herein can be applied to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the present disclosure are intended to fall within the scope of protection of the present invention.

Claims

1. A post-grouting FRP steel pipe pile construction method, characterized in that: include: S1 、 Obtaining positioning parameters of the bottom of a composite pile, the composite pile comprising multiple pile shaft units; S2. Hanging a segmented grouting device to the bottom of the composite pile according to the positioning parameters, wherein the segmented grouting device includes an air bag, an air injection hose, and a grouting hose; S3, inflating the airbag through the air injection hose to form a closed grouting space; S4, injecting cement slurry into the closed grouting space through the grouting hose, and injecting the cement slurry into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit; S5. When the cement slurry fills the interior of the composite pile and the external soil grouting is completed, stop grouting; S6. releasing the gas in the airbag; S7, lifting the segmented grouting equipment to the upper pile shaft unit; S8. Repeat steps S3 to S7 until the grouting along the entire length of the pile is completed.

2. A post-grouting FRP steel pipe pile construction method according to claim 1, characterized in that: The airbag comprises: a diameter after inflation is larger than the inner diameter of the pile body, and the number of the airbags is set according to the segment length of the pile body.

3. A post-grouting FRP steel pipe pile construction method according to claim 1, characterized in that: The pile shaft unit comprises a steel pipe and an FRP material layer on the outer surface of the steel pipe; The FRP material layer and the steel pipe are coated with epoxy resin gradient to form a composite anti-corrosion layer, and the surface of the pile rod unit is provided with a coarse sand friction layer.

4. A post-grouting FRP steel pipe pile construction method according to claim 1, characterized in that: The composite pile further comprises: a GFRP pile head; The GFRP pile head is provided with a cross-pointed pressure plate, the cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole is provided inside the GFRP pile head, and a one-way valve is configured in the rear grouting hole; After the full-length grouting of the pile body is completed, secondary grouting is performed through the preset pile top closed grouting connector, including: when the grouting pressure exceeds the preset threshold, the one-way valve opens to allow cement slurry to penetrate the rear grouting hole and be injected into the external soil, and at the same time the one-way valve prevents the mud in the soil from flowing back.

5. The post-grouting FRP steel pipe pile construction method according to claim 1, characterized in that: Injecting cement slurry into the enclosed grouting space through the grouting hose, and injecting the cement slurry into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit, comprising: The cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole provided on the pile shaft rod unit. A double-restriction ring anti-backflow structure is provided in the one-way flow hole.

6. A post-grouting FRP steel pipe pile construction device, characterized in that: include: An acquisition module is used to acquire positioning parameters of the bottom of a composite pile, where the composite pile includes multiple pile shaft units; A hanging module is used to hang and place the segmented grouting equipment to the bottom of the composite pile according to the positioning parameters, wherein the segmented grouting equipment includes an air bag, an air injection hose and a grouting hose; An inflation module, for inflating the air bag through the air injection hose to form a closed grouting space; A grouting module, injecting cement slurry into the closed grouting space through the grouting hose, and the cement slurry is injected into the external soil around the pile shaft unit through the one-way flow hole on the pile shaft unit; The stopping module stops grouting when the cement slurry fills the interior of the composite pile and the external soil grouting is completed; the gas in the air bag is released; the segmented grouting equipment is lifted to the upper pile shaft unit; and the inflation module is repeated to the stopping module until the grouting of the entire length of the pile is completed.

7. A post-grouting FRP steel pipe pile construction device according to claim 6, characterized in that: The pile shaft unit comprises a steel pipe and an FRP material layer on the outer surface of the steel pipe; The FRP material layer and the steel pipe are coated with epoxy resin gradient to form a composite anti-corrosion layer, and the surface of the pile rod unit is provided with a coarse sand friction layer.

8. The post-grouting FRP steel pipe pile construction device according to claim 6, characterized in that: The composite pile further comprises: a GFRP pile head; The GFRP pile head is provided with a cross-pointed pressure plate, the cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole is provided inside the GFRP pile head, and a one-way valve is configured in the rear grouting hole; After the full-length grouting of the pile is completed, secondary grouting is performed through the preset pile top closed grouting connector, including: when the grouting pressure exceeds the preset threshold, the one-way valve opens to allow cement slurry to penetrate the post-grouting hole and be injected into the external soil, while the one-way valve prevents soil moisture from flowing back.

9. The post-grouting FRP steel pipe pile construction device according to claim 6, characterized in that: The grouting module injects cement slurry into the closed grouting space through the grouting hose, and the cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole on the pile shaft rod unit, including: The cement slurry is injected into the external soil around the pile shaft rod unit through the one-way flow hole provided on the pile shaft rod unit. A double-restriction ring anti-backflow structure is provided in the one-way flow hole.

10. A post-grouting FRP steel pipe micro composite pile, characterized in that: It includes a GFRP pile head, a pile end rod unit and at least one pile shaft rod unit; The GFRP pile head, pile end rod unit and at least one pile shaft rod unit are connected in sequence from bottom to top; The pile shaft unit is composed of a steel pipe covered with an FRP material layer, and the FRP material layer and the steel pipe are gradiently coated with epoxy resin to form a composite anti-corrosion layer; The side wall of the pile shaft rod unit is provided with a one-way flow hole, and a double-layer anti-backflow structure consisting of an inner restriction ring and an outer restriction ring is provided in the one-way flow hole. The inner restriction ring is hinged to the flow hole baffle through a rotating shaft, and the flow hole baffle is kept in a closed state under the action of a torsion spring; A cross-pointed pressure plate is provided at the end of the GFRP pile head. The cross-pointed pressure plate adopts a four-edged symmetrical structure, and a rear grouting hole equipped with a one-way valve is provided inside the GFRP pile head.

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