Reinforcing method and reinforcing device of ocean platform pile foundation and construction method of ocean platform pile foundation

Abstract

The invention discloses an ocean platform pile foundation reinforcing method and device and a construction method of the ocean platform pile foundation reinforcing device. A grouting pipe column with a grouting cap at the lower end is put downwards from a pipe opening of an ocean platform steel pipe pile located on an ocean platform deck, and a twisting pile machine drives the grouting pipe column to rotate; and cement paste is injected into the bottom of the ocean platform steel pipe pile from the grouting pipe column and the grouting cap through a grouting pump, and a lower pile pipe of the ocean platform steel pipe pile and a soil layer on the periphery of the lower pile pipe are reinforced. A motor in the torsion pile machine is connected with the upper end of the grouting pipe column, and a sliding rail of the torsion pile machine is fixed in the ocean platform steel pipe pile through a clamp and a fixed connecting piece; the grouting pump is connected with a slurry feeding hole in the upper portion of the grouting pipe column through a grouting pipeline, and cement slurry is injected into the pile foundation bottom end and the periphery of the ocean platform steel pipe pile through the grouting pipe column and the grouting cap. The service life of the ocean platform can be prolonged, and the operation cost of production or operation projects carried out on the ocean platform is remarkably reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine engineering pile foundation reinforcement, in particular to a method and device for reinforcing a marine platform pile foundation and a construction method thereof. Background Art

[0002] Offshore platforms are complex and expensive structures, with a typical design life of approximately 20 years. During their long service lives, offshore platforms are constantly exposed to harsh operating and natural environments. These structures are susceptible to aging-related functional degradation, such as corrosion damage, fatigue cracks, and mechanical damage like localized dents. The long-term accumulation of these damages significantly reduces the stability of the platform structure, leading to a decrease in the bearing capacity of both the structural components and the entire platform, seriously impacting the safety of the platform's service life.

[0003] The aging of offshore platform structures has become a global problem. According to statistics, two-thirds of the world's existing fixed offshore platforms have been in service for more than 15 years, entering the latter stages of their designed service life. Statistics on the service life of in-service offshore platforms reveal that a significant number have been in service for over 20 years, some even exceeding 30 years, and the majority have entered the aging stage.

[0004] Many of my country's offshore platforms are also entering their final stages of service. Some of these aging platforms are still in good working order, and forced scrapping would be a significant waste. Furthermore, with the advancement of offshore oil development technologies and the need to conserve investment, these platforms are often required to continue operating beyond their service life.

[0005] For these aging platforms, the biggest challenge in maintaining continued service is safety. The stability of their steel pipe piles is particularly crucial. Effectively extending the service life of offshore platforms while ensuring their safety can significantly reduce the cost of offshore oil development and generate significant economic benefits. According to preliminary estimates, over 30% of my country's aging platforms in service could continue to serve safely and reliably for another 5-10 years after reassessment and repair and reinforcement, potentially saving a substantial amount of money.

[0006] Due to the limited space on existing and operational offshore platforms, which makes it difficult to access large-scale piling equipment, the development of corresponding offshore platform pile foundation construction technology is restricted. Therefore, how to effectively and conveniently implement the reinforcement of fixed offshore platform steel pipe pile foundations has become a major issue in the field of marine engineering structures.

[0007] A search revealed no technical solutions for reinforcing steel pipe pile foundations for offshore platforms. The only solutions that could be found were those for reinforcing underwater bridge structures unrelated to steel pipe pile foundation reinforcement for offshore platforms, such as the following: Application No. CN202110809590.2 proposes a method for reinforcing underwater bridge structures, relating to the field of bridge engineering. The method includes the following steps: S1. Construction Preparation: Build an overwater channel and an operating platform. Divers use the operating platform to survey the pile foundation and determine the shape, size, and condition of the caissons surrounding the pile foundation; S2. Clean the pile foundation; S3. Install a concrete support device; and S4. Concrete pouring. Divers are used to survey the pile foundation underwater, allowing construction workers to determine the specific length from the pile foundation tie beam to the riverbed based on the divers' feedback. This facilitates the subsequent installation of the concrete support device and, in turn, the pouring of concrete. Compared to traditional cofferdam construction methods, the method for reinforcing underwater bridge structures in the aforementioned application offers the advantage of lower costs.

[0008] However, the underwater structure of the bridge is completely different from that of the offshore platform and the wading depth of the bridge is much shallower than that of the offshore platform. Therefore, the above invention cannot be applied to the reinforcement of the steel pipe pile foundation of the offshore platform.

[0009] Application No. CN202210724763.5 discloses a construction method for a front-mounted lightweight composite column-type platform to widen and reinforce a bridge. It includes the following steps: filling and compacting the widened side of the existing bridge to form a widened roadbed slope; constructing steel sheet piles on the widened side of the existing bridge to form a protective structure; excavating the surface of the widened roadbed slope to form a construction platform; constructing a cap beam pile foundation and a platform front pile foundation on the construction platform; constructing a tie beam between the two platform front pile foundations, constructing a diagonal bracing beam between the platform front pile foundation and the cap beam pile foundation, and arranging the diagonal bracing beam downwardly in the direction toward the platform front pile foundation; constructing a cap beam on the top of the cap beam pile foundation; backfilling the construction platform, constructing a slab, and erecting a bridge deck. The above invention improves the deformation stability of the bridge and the seismic performance of the abutment by arranging a cap beam, a cap beam pile foundation, a platform front pile foundation and a diagonal bracing beam. The use of reusable steel sheet piles saves protective engineering and reduces engineering costs.

[0010] However, the underwater structure of the bridge is completely different from that of the offshore platform and the wading depth of the bridge is much shallower than that of the offshore platform. Therefore, the above invention cannot be applied to the reinforcement of the steel pipe pile foundation of the offshore platform.

[0011] Application number CN201920421314.7 discloses a maintenance and reinforcement platform for circular pier wading pile foundations, comprising a lightweight clamp, a hanger, steps, and a guardrail. The lightweight clamp comprises a pair of semicircular steel plates, lifting ears, a stiffening joint, a rubber pad, and fastening bolts. Two lifting ears are provided on each semicircular steel plate, and stiffening joints are located at both ends of each semicircular steel plate. The two semicircular steel plates are connected by fastening bolts through the stiffening joint. The hanger comprises a short hanging rod, a vertical hanging rod, a horizontal support rod, a diagonal rod, and a pad. The vertical hanging rod, horizontal support rod, and diagonal rod are connected to each other by welding. The short hanging rod is welded to the upper end of the vertical hanging rod. The steps are bolted to the two horizontal support rods. The outer ends of the horizontal support rods are welded to circular steel pipes. Vertical steel bars are provided inside the circular steel pipes. The vertical steel bars are tied and connected to several horizontal steel bars. The above-mentioned utility model has a simple structure, is easy to construct, does not damage the bridge structure, is easy to load and unload, can be recycled, and is economical and practical.

[0012] Similarly, the underwater structure of the bridge is completely different from that of the offshore platform and the wading depth of the bridge is much shallower than that of the offshore platform. Therefore, the above invention cannot be applied to the reinforcement of the steel pipe pile foundation of the offshore platform.

[0013] Therefore, the reinforcement methods and equipment for offshore platform steel pipe pile foundations are in urgent need of development and application. Summary of the Invention

[0014] The present invention aims to provide a method and device for reinforcing offshore platform pile foundations, as well as a construction method thereof, which can be used within the confined space of offshore platforms and can reinforce the bottom of offshore platform steel pipe pile foundations. This can extend the service life of offshore platforms and reduce the costs of oil development and production or business projects using offshore platforms.

[0015] The technical solution of the present invention is: a method for reinforcing an offshore platform pile foundation, comprising: lowering a grouting pipe string with a grouting cap at the lower end into the pipe mouth of an offshore platform steel pipe pile located above the offshore platform deck; allowing a torsion pile driver to rotate the grouting pipe string; and injecting cement slurry from the grouting pipe string and the grouting cap into the bottom of the offshore platform steel pipe pile through a grouting pump, thereby reinforcing the lower pile pipe of the offshore platform steel pipe pile and the soil layer around the lower pile pipe.

[0016] A method for reinforcing an offshore platform pile foundation includes an offshore platform pile foundation reinforcement device, comprising a torsion pile driver, a grouting pipe string, and a grouting cap, wherein the grouting pipe string, the lower end of which is connected to the grouting cap, is lowered into the upper end pipe opening of the offshore platform steel pipe pile in the offshore platform deck, the motor in the torsion pile driver is connected to the upper end of the grouting pipe string; the sliding track of the torsion pile driver is fixed in the offshore platform steel pipe pile by a clamp and a fixed connector; the grouting pump is connected to the grouting hole on the upper part of the grouting pipe string through a grouting pipeline, and cement slurry is injected into the pile base and outer periphery of the offshore platform steel pipe pile through the grouting pipe string and the grouting cap.

[0017] Preferably, the fixed connector is a ┓-shaped structural plate composed of two arc-shaped plates, one end of the horizontal plate is welded to the sliding track, and the inner and outer arc surfaces of the vertical plate are clamped between the clamp and the offshore platform steel pipe pile.

[0018] Preferably, the clamp is provided with a clamp and a fastening bolt, and the clamp is provided with two and has connecting wings at both ends and can be connected by fastening bolts; the inner diameter formed by the two clamps is smaller than the outer diameter formed by the offshore platform steel pipe pile and the fixed connection piece, and the two clamps and fastening bolts can tightly fix the offshore platform steel pipe pile and the fixed connection piece together.

[0019] Preferably, a sleeve with an inner connection is welded at the lower end of the output shaft of the motor of the torsion pile driver, and the inner connection in the sleeve matches the outer connection of the grouting pipe column connector welded at the upper end of the grouting pipe column, and the grouting pipe column connector at the upper end of the grouting pipe column can be stuck into the inner connection in the sleeve at the lower end of the motor output shaft.

[0020] Preferably, the grouting pipe string is connected by a hollow drill rod, the grouting hole arranged at the upper part of the grouting pipe string is connected to the grouting pipeline of the grouting pump through a sealing joint, and the lower end of the grouting pipe string is threadedly connected to the grouting cap; the total length of the grouting pipe string and the grouting cap is greater than the height of the offshore platform steel pipe pile to be reinforced.

[0021] Preferably, the grouting cap is provided with a guide tube body, a grouting hole and a spiral blade. The upper part of the guide tube body is provided with a thread and can be threadedly connected to the hollow drill rod of the grouting pipe column. The lower part of the guide tube body is the grouting body; the grouting hole is arranged in the grouting body at the lower part of the guide tube body, and the spiral blade is arranged outside the lower outer wall of the guide tube body.

[0022] Preferably, the outer diameter of the grouting cap is 0.75 times to 0.85 times the inner diameter of the offshore platform steel pipe pile; and the number of grouting holes provided in the grouting body is more than two and is evenly distributed in the grouting body.

[0023] The construction method used for the offshore platform pile foundation reinforcement device includes the following steps: A. processing a grouting cap and determining the height of the grouting pipe string after assembly; B. connecting the grouting cap to the bottom of the hollow drill rod at the lowest end of the grouting pipe string, and lowering it from the pipe mouth of the offshore platform steel pipe pile located above the offshore platform deck to the surface of the soil layer inside the offshore platform steel pipe pile; C. installing a torsion pile driver, rotating and lowering the grouting cap to the grouting reinforcement position inside the offshore platform steel pipe pile; D. connecting the hollow drill rod to the upper end of the grouting pipe string and connecting it to a grouting pump to start injecting cement slurry; E. grouting the pile bottom; screwing the grouting cap into the horizontal position of the bottom end of the offshore platform steel pipe pile, gradually increasing the grouting pressure, controlling the grouting volume, and monitoring the change in grouting pressure; F. after standing and waiting for solidification, leaving the grouting cap at the bottom end of the offshore platform steel pipe pile and removing the grouting pipe string to complete the construction.

[0024] Preferably, the grouting reinforcement position in the offshore platform steel pipe pile is set at a position three times the outer diameter of the steel pipe pile upward from the bottom end of the steel pipe pile, and the height of the grouting reinforcement position is equal to or less than the length of the connected hollow drill rod. Cement slurry is injected at the grouting reinforcement position and stirred by the grouting cap during grouting to form high-strength concrete. The grouting pressure at the beginning of injecting cement slurry is controlled below 2 MPa and gradually increased to 6-8 MPa.

[0025] Preferably, when the grouting pressure increases to 6-8 MPa, the grouting amount of the grouting pump is controlled at The above and monitor the changes in grouting pressure. The grouting pressure at this time is equal to or less than the reaction force provided by the reinforced soil in the offshore platform steel pipe pile above the grouting cap; The grouting amount is the grouting volume, where: л is pi; R 3 It is the cube of the outer wall radius of the offshore platform steel pipe pile; standing and waiting for setting means that after the grouting is completed, it is left standing for more than hours to wait for the cement slurry to solidify.

[0026] The significant effect of the present invention is that: due to the limited space of the offshore platforms that have been built and put into service, it is impossible to use large-scale piling equipment to reinforce the steel pipe piles of the platforms. The method and device of the present invention are used to reinforce the pile foundation of the offshore platform steel pipe piles without the need for large-scale construction equipment, and the reinforcement effect can be achieved.

[0027] The present invention connects a torsion pile driver to a grouting pipe column with a grouting cap installed at the bottom end in the pile pipe opening on the platform deck, and then lowers the pile driver into the bottom end of the pile pipe of the offshore platform steel pipe pile. The injected cement slurry reinforces the soil at the bottom, bottom end and periphery of the pile pipe bottom end, thereby significantly improving the bearing capacity of the pile foundation. The advantages are as follows: 1. The present invention utilizes a torsion pile driver to rotate and insert a grouting cap into an existing offshore platform steel pipe pile to reinforce the pile base and periphery with cement slurry. This method eliminates the need for large-scale construction equipment, reduces installation and operating costs, and is technically reliable and economically feasible. 2. The grouting reinforcement position within the offshore platform steel pipe pile is located three times the outer diameter of the steel pipe pile upward from the bottom end of the pile. Grouting reinforcement begins at this point and continues to the pile bottom end face. Grouting pressure is gradually increased at the bottom of the pile, the grouting volume is controlled, and changes in grouting pressure are monitored. The reaction force provided by the soil above the grouting cap is used to constrain and stabilize the position of the grouting cap, ensuring that the grouting pressure at the pile bottom does not decay and forming a reinforced and expanded cement body below the pile bottom. Excess cement slurry becomes upward return cement slurry and returns to a certain height along the outer wall of the offshore platform steel pipe pile, forming a cement reinforcement layer on the outer wall of the offshore platform steel pipe pile. The reinforced and expanded cement body becomes a cement plug after solidification. The cement plug and the cement reinforcement layer formed by the upper return cement slurry on the outside of the offshore platform steel pipe pile play a joint reinforcement role, significantly improving the bearing capacity of the offshore platform steel pipe pile.

[0028] 3. The present invention can realize the reinforcement of the steel pipe pile foundation of the offshore platform, filling the gap of the current lack of relevant construction methods and devices, and can extend the service life and service life of the offshore platform, significantly reducing the operating costs of oil development and production or operation projects using offshore platforms.

[0029] 4. The reinforcement method and device of the present invention are simple, technically feasible, and have low construction costs. They are suitable for reinforcing steel pipe piles of offshore platforms, have significant use effects, and can achieve significant economic and social benefits, and have good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 This is a working state diagram of the device of the present invention before grouting.

[0031] Figure 2 yes Figure 1 Schematic diagram of the structure in the A-A direction.

[0032] Figure 3 This is a diagram showing the reinforcement effect of the device of the present invention on the pile foundation after grouting.

[0033] Figure 4 yes Figure 1 Main view of the schematic diagram of the grouting cap structure.

[0034] Figure 5 yes Figure 4 Top view of .

[0035] In the figure: torsion pile driver 1, offshore platform steel pipe pile 2, grouting pipe string 3; Grouting cap 4, grouting hole 41, spiral blade 42; Grouting pump 5, upper return cement slurry 6, slurry delivery hole 7, clamp 8, motor 9, sliding block 10, sliding track 11, fixed connection part 12, guide plate 13. DETAILED DESCRIPTION

[0036] The accompanying drawings are for reference and illustration purposes only and are not intended to limit the scope of protection of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] In the description of the present invention, it should be understood that the terms "length," "width," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating positions or location relationships, are based on the positions or location relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, in the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

[0039] See also Figure 1 - Figure 5 A method for reinforcing an offshore platform pile foundation comprises: lowering a grouting pipe string 3 with a grouting cap 4 at its lower end into the pipe mouth of an offshore platform steel pipe pile 2 located above the offshore platform deck; rotating the grouting pipe string 3 with a torsion pile driver 1; and injecting cement slurry from the grouting pipe string 3 and the grouting cap 4 into the bottom of the offshore platform steel pipe pile 2 via a grouting pump 5, thereby reinforcing the lower pile pipe of the offshore platform steel pipe pile 2 and the soil layer surrounding the lower pile pipe.

[0040] The torsion pile driver 1 is an existing small-scale pile driving construction equipment, which is mainly composed of components such as a motor 9, a sliding block 10, a sliding track 11 and a guide plate 13. When the torsion pile driver 1 is used for piling, the motor 9 drives the drill rod to rotate, and the motor 9 is fixed together with the sliding block 10 that can move linearly up and down along the sliding track 11. The guide plate 13 is fixed at the bottom of the sliding track 11, and the drill rod driven by the motor 9 can move up and down in the guide plate 13. The guide plate 13 restricts the lateral movement of the drill rod and ensures that the drill rod moves vertically downward. The present invention utilizes the grouting pipe column 3 driven by the motor 9 in the torsion pile driver 1, connects the grouting cap 4 at the bottom of the grouting pipe column 3, and sends the grouting cap 4 to the lower part of the pile foundation of the offshore platform steel pipe pile 2 through the motor 9 and the grouting pipe column 3, stirs the soil in the pile foundation and injects cement slurry, and reinforces the bottom of the pile foundation with cement slurry.

[0041] A marine platform pile foundation reinforcement device used in a method for reinforcing an offshore platform pile foundation comprises a torsion pile driver 1, a grouting pipe string 3 and a grouting cap 4, wherein: the grouting pipe string 3, the lower end of which is connected to the grouting cap 4, is lowered into the upper end pipe opening of the offshore platform steel pipe pile 2 in the offshore platform deck; the motor 9 in the torsion pile driver 1 is connected to the upper end of the grouting pipe string 3; the sliding track 11 of the torsion pile driver 1 is fixed in the offshore platform steel pipe pile 2 via a clamp 8 and a fixed connector 12; the grouting pump 5 is connected to the grouting hole 7 on the upper part of the grouting pipe string 3 via a grouting pipeline, and injects cement slurry into the pile base and outer periphery of the offshore platform steel pipe pile 2 through the grouting pipe string 3 and the grouting cap 4.

[0042] Based on the above embodiment 1, the present invention also has the following embodiments: In a preferred embodiment, the fixed connector 12 is a ┓-shaped structure composed of two curved plates, with one end of the transverse plate welded to the sliding track 11, and the inner and outer curved surfaces of the vertical plate clamped between the clamp 8 and the offshore platform steel pipe pile 2. The clamp 8 and the fixed connector 12 securely fasten the sliding track 11 to the inner wall of the offshore platform steel pipe pile 2, allowing the motor 9 to drive the grouting pipe 3 and grouting cap 4 to move up and down within the guide plate 13.

[0043] In a preferred embodiment, the clamp 8 is provided with a clamp and a fastening bolt. The clamps are provided with two connecting wings at both ends and can be connected by the fastening bolts. The inner diameter formed by the two clamps is smaller than the outer diameter formed by the offshore platform steel pipe pile 2 and the fixed connector 12. The two clamps and the fastening bolts can tightly fix the offshore platform steel pipe pile 2 and the fixed connector 12 together, ensuring the stability of the sliding track 11 within the offshore platform steel pipe pile 2.

[0044] In a preferred embodiment, a sleeve with an inner connection is welded to the lower end of the output shaft of the motor 9 of the twist pile driver 1. The inner connection of the sleeve aligns with the outer connection of the grouting pipe column connector welded to the upper end of the grouting pipe column 3. The grouting pipe column connector at the upper end of the grouting pipe column 3 can be snapped into the inner connection of the sleeve at the lower end of the output shaft of the motor 9. When the motor 9 rotates and moves downward along the sliding track 11, it can drive and compress the grouting pipe column 3 to perform a vertical downward rotational motion along the guide plate 13.

[0045] In a preferred embodiment, the grouting string 3 is formed by connecting hollow drill rods. A grouting hole 7 provided at the top of the grouting string 3 is connected to the grouting line of the grouting pump 5 via a sealed joint. The lower end of the grouting string 3 is threadedly connected to the grouting cap 4. The combined length of the grouting string 3 and the grouting cap 4 is greater than the height of the offshore steel pipe pile 2 being reinforced. After the grouting reinforcement process of the offshore steel pipe pile 2 is completed, the grouting string 3 and the grouting cap 4 can be disengaged by rotating the twisting pile driver 1 in the reverse direction, leaving the grouting cap 4 in the cement plug formed by the cement slurry injected into the offshore steel pipe pile 2, and the grouting string 3 can be removed.

[0046] A preferred embodiment: the grouting cap 4 is provided with a guide pipe body, a grouting hole 41 and a spiral blade 42; the upper part of the guide pipe body is provided with a thread and can be threadedly connected to the hollow drill rod of the grouting pipe column 3; the lower part of the guide pipe body is a grouting body; the grouting hole 41 is provided in the grouting body at the lower part of the guide pipe body, and the spiral blade 42 is provided outside the lower outer wall of the guide pipe body.

[0047] In a preferred embodiment, the outer diameter of the grouting cap 4 is 0.75 to 0.85 times the inner diameter of the offshore platform steel pipe pile 2 ; and the number of grouting holes 41 in the grouting body is more than two and is evenly distributed in the grouting body.

[0048] The construction method applied to the offshore platform pile foundation reinforcement device comprises the following steps: A. Processing the grouting cap 4 and determining the height of the assembled grouting string 3; in this step, the outer diameter of the grouting cap 4 must be determined based on the inner diameter of the steel pipe pile 2 of the offshore platform to be reinforced, so that the outer diameter of the grouting cap 4 is 0.75 to 0.85 times the inner diameter of the offshore platform steel pipe pile 2 being constructed; the height of the grouting string 3 formed by connecting hollow drill rods is selected based on the construction height of the torsion pile driver 1 on the platform deck; B. Connect the grouting cap 4 to the bottom of the hollow drill rod at the lowest end of the grouting pipe string 3 and lower it into the soil surface inside the offshore steel pipe pile 2 from the pipe opening of the offshore steel pipe pile 2 located above the offshore deck; C. Install the torsion pile driver 1 and rotate and lower the grouting cap 4 to the grouting reinforcement position in the offshore platform steel pipe pile 2. During this process, select a torsion pile driver 1 with appropriate power according to the soil properties of the construction marine area and the size of the grouting cap 4. Fix the motor 9 and the sliding track 11 of the torsion pile driver 1 in the offshore platform steel pipe pile 2. Apply torque and vertical downward pressure to the grouting cap 4 through the torsion pile driver 1 and the grouting pipe string 3 connected thereto, and gradually screw the grouting cap 4 into the soil layer and rotate it to the grouting reinforcement position in the offshore platform steel pipe pile 2.

[0049] D. Connect a hollow drill pipe to the upper end of the grouting string 3 and connect it to the grouting pump 5. Start injecting cement slurry. The water-cement ratio is adjusted according to the soil properties at the construction site, and the grouting pressure is controlled. The grouting cap 4 is screwed in while grouting. The cement slurry is pressed into the surrounding soil within the offshore platform steel pipe pile 2 through the grouting hole 41 and mixed with the surrounding soil by the screwed-in grouting cap 4.

[0050] E. Grouting at the bottom of the pile; screw the grouting cap 4 into the horizontal position of the bottom end of the offshore platform steel pipe pile 2, gradually increase the grouting pressure, control the grouting volume, and monitor the changes in the grouting pressure; use the reaction force provided by the soil above the grouting cap 4 to restrict and stabilize the position of the grouting cap 4, ensuring that the grouting pressure at the bottom end of the pile does not decay. As the grouting volume increases, the slurry injection range gradually expands in a hemispherical shape, forming a reinforced and expanded cement body below the bottom end of the pile. Excess cement slurry flows back to a certain height along the outer wall of the offshore platform steel pipe pile 2, and the returned cement slurry 6 forms a cement reinforcement layer on the outer wall of the offshore platform steel pipe pile 2. After the reinforced and expanded cement body solidifies, it becomes a cement plug. This cement plug and the cement reinforcement layer formed by the returned cement slurry 6 on the outside of the offshore platform steel pipe pile play a reinforcing role together, significantly improving the bearing capacity of the offshore platform steel pipe pile 2.

[0051] F. After standing and waiting for solidification, the grouting cap 4 is retained at the bottom of the offshore platform steel pipe pile 2 and the grouting string 3 is removed, completing the construction. During this process, the grouting string 3 is rotated in the opposite direction by the twisting pile driver 1, separating the hollow drill rod at the bottom from the grouting cap 4, which has solidified in the concrete. The hollow drill rod in the grouting string 3 is then recovered in sections, and the twisting pile driver 1 is disassembled, completing the reinforcement of the offshore platform steel pipe pile 2.

[0052] A preferred embodiment: The grouting reinforcement position in the offshore platform steel pipe pile 2 is set at a position three times the outer diameter of the steel pipe pile upward from the bottom end of the steel pipe pile. The height of the grouting reinforcement position is equal to or less than the length of the connected hollow drill rod. Cement slurry is injected at the grouting reinforcement position and stirred by the grouting cap 4 while grouting to form high-strength concrete. The grouting pressure at the beginning of injecting cement slurry is controlled below 2 MPa and gradually increased to 6-8 MPa.

[0053] A preferred embodiment: When the grouting pressure increases to 6-8 MPa, the grouting amount of the grouting pump 5 is controlled at The above and monitor the changes in grouting pressure. The grouting pressure at this time is equal to or less than the reaction force provided by the reinforced soil in the offshore platform steel pipe pile 2 above the grouting cap 4; otherwise, under the recoil effect of the grouting pressure, the grouting cap 4 will be forced to move upward and squeeze into the offshore platform steel pipe pile 2, which will affect the reinforcement effect below the bottom end and the periphery of the offshore platform steel pipe pile 2.

[0054] The grouting amount is the grouting volume, where: л is pi; R 3 It is the cube of the outer wall radius of the offshore platform steel pipe pile 2; standing and waiting for setting means that after the grouting is completed, it is left standing for more than 3 hours to wait for the cement slurry to solidify.

[0055] The present invention assembles and connects the assembled grouting cap 4 with the grouting pipe column 3 and then lowers the assembled grouting cap 4 to the surface of the soil layer in the steel pipe pile 2 of the offshore platform.

[0056] The grouting cap 4 is then rotated and lowered into the grouting reinforcement position within the offshore platform steel pipe pile 2 using the twisting pile driver 1. The top of the grouting pipe string 3 is connected to the grouting pump 5 via the grouting hole 7. Pressure grouting is performed while the grouting cap 4 is rotated and lowered. The reaction force provided by the grouting cap 4 and the soil above it forms a reinforced and expanded cement body below the bottom end of the pile base, and a cement reinforcement layer is formed around the pile foundation. The cement slurry in the reinforced and expanded cement body solidifies into a cement plug, which interacts with the cement reinforcement layer formed around the pile foundation, effectively increasing the bearing capacity of the offshore platform steel pipe pile 2.

[0057] After grouting is completed, reverse torque is applied to the torsion pile driver 1 to detach the grouting cap 4 solidified in the cement plug from the grouting pipe string 3 connected thereto, and the grouting pipe string 3 is pulled out and the torsion pile driver 1 is disassembled to complete the reinforcement construction of the offshore platform steel pipe pile 2 foundation.

[0058] The embodiments described above are merely typical embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and enlightenment of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection is not limited to the above description.

Claims

1. A method for reinforcing an offshore platform pile foundation, characterized by: A grouting pipe column (3) with a grouting cap (4) at its lower end is lowered into the pipe mouth of an offshore platform steel pipe pile (2) located above the offshore platform deck, and the torsion pile driver (1) drives the grouting pipe column (3) to rotate. Cement slurry is injected from the grouting pipe column (3) and the grouting cap (4) into the bottom of the offshore platform steel pipe pile (2) through a grouting pump (5), thereby reinforcing the lower pile pipe of the offshore platform steel pipe pile (2) and the soil layer around the lower pile pipe.

2. The offshore platform pile foundation reinforcement device used in the offshore platform pile foundation reinforcement method according to claim 1, characterized in that: A torsion pile driver (1), a grouting pipe column (3) and a grouting cap (4) are provided, wherein: the grouting pipe column (3) with the grouting cap (4) connected to the lower end is lowered from the upper end pipe mouth of the marine platform steel pipe pile (2) in the marine platform deck, and the motor (9) in the torsion pile driver (1) is connected to the upper end of the grouting pipe column (3); the sliding track (11) of the torsion pile driver (1) is fixed in the marine platform steel pipe pile (2) through a clamp (8) and a fixed connection piece (12); the grouting pump (5) is connected to the grouting hole (7) on the upper part of the grouting pipe column (3) through a grouting pipeline, and the cement slurry is injected into the pile base end and the outer periphery of the marine platform steel pipe pile (2) through the grouting pipe column (3) and the grouting cap (4).

3. The offshore platform pile foundation reinforcement device according to claim 2, characterized in that: The fixed connection member (12) is a ┓-shaped structural plate body composed of two arc-shaped plates, one end of the horizontal plate body is welded to the sliding track (11), and the inner and outer arc surfaces of the vertical plate body are clamped between the clamp (8) and the offshore platform steel pipe pile (2).

4. The offshore platform pile foundation reinforcement device according to claim 3, characterized in that: The clamp (8) is provided with a clamp and a fastening bolt, wherein two clamps are provided and both ends of the clamps are provided with connecting wings and can be connected by fastening bolts; the inner diameter formed by the two clamps is smaller than the outer diameter formed by the offshore platform steel pipe pile (2) and the fixed connection piece (12), and the two clamps and the fastening bolts can tightly fix the offshore platform steel pipe pile (2) and the fixed connection piece (12) together.

5. The offshore platform pile foundation reinforcement device according to claim 2, characterized in that: The lower end of the output shaft of the motor (9) of the twist pile driver (1) is welded with a sleeve with an inner connection square, and the inner connection square in the sleeve matches the outer connection square of the grouting pipe column connector welded at the upper end of the grouting pipe column (3). The grouting pipe column connector at the upper end of the grouting pipe column (3) can be clamped into the inner connection square in the sleeve at the lower end of the output shaft of the motor (9).

6. The offshore platform pile foundation reinforcement device according to claim 5, characterized in that: The grouting pipe string (3) is formed by connecting hollow drill rods. A grouting hole (7) provided at the upper portion of the grouting pipe string (3) is connected to the grouting pipeline of the grouting pump (5) via a sealing joint. The lower end of the grouting pipe string (3) is threadedly connected to the grouting cap (4). The total length of the grouting pipe string (3) and the grouting cap (4) is greater than the height of the offshore platform steel pipe pile (2) to be reinforced.

7. The offshore platform pile foundation reinforcement device according to claim 6, characterized in that: The grouting cap (4) is provided with a guide pipe body, a grouting hole (41) and a spiral blade (42); the upper portion of the guide pipe body is provided with a thread and can be threadedly connected to the hollow drill rod of the grouting pipe column (3); the lower portion of the guide pipe body is a grouting body; the grouting hole (41) is provided in the grouting body at the lower portion of the guide pipe body, and the spiral blade (42) is provided outside the lower outer wall of the guide pipe body.

8. The offshore platform pile foundation reinforcement device according to claim 7, characterized in that: The outer diameter of the grouting cap (4) is 0.75 to 0.85 times the inner diameter of the offshore platform steel pipe pile (2); and the grouting holes (41) provided in the grouting body are provided in two or more numbers and are evenly distributed in the grouting body.

9. The construction method for the offshore platform pile foundation reinforcement device according to any one of claims 2 to 8, characterized in that: The following steps are involved: A. Process the grouting cap (4) and determine the height of the grouting pipe column (3) after assembly; B. Connect the grouting cap (4) to the bottom of the hollow drill rod at the lowest end of the grouting pipe column (3) and lower it from the pipe mouth of the offshore platform steel pipe pile (2) located on the offshore platform deck to the soil surface inside the offshore platform steel pipe pile (2); C. Install the torsion pile driver (1) and rotate the grouting cap (4) and lower it to the grouting reinforcement position inside the offshore platform steel pipe pile (2); D. Connect the hollow drill rod to the upper end of the grouting pipe column (3) and start injecting cement slurry after connecting it to the grouting pump (5); E. Grouting the pile bottom; Screw the grouting cap (4) into the horizontal position of the pile bottom end of the offshore platform steel pipe pile (2), gradually increase the grouting pressure, control the grouting volume, and monitor the change of the grouting pressure; F. After standing and waiting for solidification, leave the grouting cap (4) at the pile bottom end of the offshore platform steel pipe pile (2) and remove the grouting pipe column (3) to complete the construction.

10. The construction method of the offshore platform pile foundation reinforcement device according to claim 9, characterized in that: The grouting reinforcement position in the offshore platform steel pipe pile (2) is set at a position three times the outer diameter of the steel pipe pile upward from the bottom end of the steel pipe pile. The height of the grouting reinforcement position is equal to or less than the length of the connected hollow drill rod. Cement slurry is injected at the grouting reinforcement position and stirred by the grouting cap (4) while grouting to form high-strength concrete. The grouting pressure at the beginning of the cement slurry injection is controlled to be below 2MPa and the grouting pressure is gradually increased to 6-8MPa.

11. The construction method of the offshore platform pile foundation reinforcement device according to claim 10, characterized in that: When the grouting pressure increases to 6-8 MPa, the grouting volume of the grouting pump (5) is controlled at The above and monitoring of the change of grouting pressure, the grouting pressure at this time is equal to or less than the reaction force provided by the reinforced soil in the offshore platform steel pipe pile (2) above the grouting cap (4); the grouting amount is the grouting volume, where: л is pi; R 3 It is the cube of the outer wall radius of the offshore platform steel pipe pile (2); standing and waiting for setting means that after the grouting is completed, it is left standing for more than (3) hours to wait for the cement slurry to solidify.

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