A construction method for anti-floating of a cast-in-place pile reinforcement cage

Abstract

The present application relates to the technical field of foundation engineering, and aims to solve the problems of insufficient constraint of traditional cast-in-place pile construction reinforcement cage, easy floating, shifting, deviation, concrete feeding speed regulation relying on manual experience, unguaranteed construction quality, too fast pouring speed in each stage, easy damage and failure of protective layer in highland cold working conditions, leading to freeze-thaw damage of pile body, and provide a cast-in-place pile reinforcement cage anti-floating construction method, comprising: S1: preparation before construction; S2: making reinforcement cage and installing anti-floating plate and anti-floating rib plate thereon; S3: laying monitoring system and connecting monitoring system to control system; S4: laying composite heat preservation anti-seepage protective layer in cast-in-place pile hole; S5: lowering reinforcement cage and guide pipe and carrying out speed control pouring construction; the present application composites the whole section of reinforcement cage from pile bottom to pile top, avoids its floating, deviation and shifting, adopts segmented speed control pouring construction, the process is accurate and controllable, and gets rid of the dependence on manual experience.

Description

Technical Field

[0001] This invention relates to the field of basic engineering technology, and more specifically, to a method for anti-buoyancy construction of cast-in-place pile reinforcement cages. Background Technology

[0002] Due to its advantages such as high bearing capacity, strong adaptability to geological formations, and low construction noise, cast-in-place piles have become the main foundation type for major projects such as bridges and high-rise buildings.

[0003] The following technical problems exist in the construction of cast-in-place piles in the existing technology: 1. Traditional cast-in-place pile construction methods rely solely on simple anchor bars at the borehole opening to fix the reinforcing cage, which only restrains the top of the cage. Underwater buoyancy of the concrete, negative pressure eddies during tremor pipe pulling, lateral extrusion pressure on the concrete, and grouting force at the pile bottom can cause the lower and bottom sections of the reinforcing cage to float, shift, and deviate. This floating of the reinforcing cage can lead to major quality defects such as insufficient protective layer, rebar misalignment, pile breakage, insufficient bearing capacity, and unqualified pile foundation testing. 2. In traditional cast-in-place pile construction, the control of concrete pouring speed relies entirely on the operator's on-site experience and judgment. There are no quantitative speed limits for different pouring sections, nor is there a dynamic adjustment mechanism linked to the real-time burial depth of the tremie pipe. This extensive manual control mode results in pouring parameters for each pile location varying from person to person and from time to time, leading to significant fluctuations in construction quality and making it difficult to achieve construction standardization and quality control. 3. The initial grouting speed at the bottom of the pile is too fast, which disturbs the sediment at the bottom of the hole, resulting in excessive mud and sediment at the bottom of the pile. 4. Excessive flow velocity in sections with densely packed reinforcing cages leads to a surge in jacking force, which is the core cause of the reinforcing cages floating. 5. The pouring speed at the top of the pile is too fast, which causes air bubbles and excessive laitance to be trapped, resulting in a loose and insufficiently dense pile top. 6. Under the harsh conditions of high altitude and cold, the three major destructive factors of water seepage, frost heave and soil compression and abrasion coexist and interact for a long time. Traditional piles do not have a protective layer or the protective layer is mostly a single-layer structure. Under multiple conditions of frozen soil water seepage, temperature difference frost heave and soil compression and abrasion, the protective layer is prone to damage and failure, resulting in freeze-thaw damage to the pile body. Summary of the Invention

[0004] This invention aims to provide a method for anti-buoyancy construction of reinforcing cages for cast-in-place piles, in order to solve the problems of insufficient restraint of reinforcing cages in traditional cast-in-place pile construction, easy floating, movement and displacement, reliance on manual experience to control the concrete pouring speed, inability to guarantee construction quality, excessively fast pouring speed at each stage, easy damage and failure of the protective layer in the cold conditions of high altitude, and freeze-thaw damage to the pile body.

[0005] This invention is achieved using the following technical solution: This invention provides a method for anti-buoyancy construction of cast-in-place pile reinforcement cages, comprising the following steps: S1: Pre-construction preparations; S2: Fabricate a steel cage and install anti-buoyancy plates and anti-buoyancy ribs on it; S3: Deploy the monitoring system and connect it to the control system; S4: Install a composite thermal insulation and seepage prevention protective layer inside the grouting pile hole; S5: Lower the steel cage and guide pipe to carry out controlled-speed grouting construction.

[0006] As a preferred technical solution: The anti-buoyancy construction method for cast-in-place pile reinforcement cages also includes S6: performing post-construction finishing.

[0007] As a preferred technical solution: Step S1 specifically includes: After completing the drilling and initial cleaning of the cast-in-place pile, measure the hole depth, sediment thickness, and verticality of the hole wall.

[0008] As a preferred technical solution: Step S1 also includes: Once the three parameters of hole depth, sediment thickness and hole wall verticality all meet the design specifications, proceed to step S2; if any one of them does not meet the requirements, clean the hole again and retest until all parameters meet the standards.

[0009] As a preferred technical solution: Step S2 specifically includes: The steel cage is manufactured according to the design drawings. The steel cage includes a reinforced area and an unreinforced area. The reinforced area is the upper part of the steel cage. The anti-buoyancy plate is fixedly connected to the main reinforcement bar at the bottom of the steel cage by connecting steel bars. The anti-buoyancy plate is used to be placed at the bottom of the hole. Multiple anti-buoyancy ribs are arranged at intervals along the length of the steel cage and fixedly connected to the steel cage; the anti-buoyancy ribs are inclined toward the main reinforcement. The top of the reinforcing cage is constrained by hanging bars at the opening.

[0010] As a preferred technical solution: In step S3: The monitoring system includes a level sensor, a pressure sensor, and an automatic flow control valve; Three liquid level sensors are fixedly installed on the main reinforcement of the steel cage, namely concrete liquid level sensor one, concrete liquid level sensor two and concrete liquid level sensor three. Concrete liquid level sensor one is installed on the main reinforcement of the steel cage at the finished surface of the initial pouring height. Concrete liquid level sensor two is installed on the bottom of the densified area on the main reinforcement of the steel cage. Concrete liquid level sensor three is installed on the main reinforcement of the steel cage at the design elevation of the pile top. A pressure sensor is installed at the end of the conduit. The pressure measured by the pressure sensor is P=ρgh. The control system 7 calculates the embedment depth of the conduit end in the concrete. An automatic flow control valve is installed on the hopper. The automatic flow control valve includes a flow sensor and a valve body. The flow sensor is used to monitor the discharge flow rate in real time, and the valve body is used as an actuator to control the discharge speed and flow rate. The level sensor, pressure sensor, flow sensor, and valve body are all connected to the control system. The control system executes a preset program and outputs commands based on the data collected by the level sensor, pressure sensor, and flow sensor, driving the valve body to change the valve opening and thus achieving automatic control of the concrete pouring speed.

[0011] As a preferred technical solution: In step S3: The control system has four preset control programs, which set corresponding target pouring speeds for the initial pouring section at the bottom of the pile, the middle section of the pile, the reinforced cage densification zone at the top of the pile, and the over-pouring section at the top of the pile.

[0012] As a preferred technical solution: Step S4 specifically includes: According to the depth of the frozen soil, a release agent is applied to the inner wall of the casing within the frozen soil layer. Then, a composite thermal insulation and seepage prevention protective layer is covered on the inner wall of the casing. The composite thermal insulation and seepage prevention protective layer includes an inner seepage prevention layer, a middle thermal insulation layer and an outer wear-resistant and pressure-resistant layer, which are integrated into one structure. The outer wear-resistant and pressure-resistant layer is used to contact the borehole wall after the casing is removed, and the inner seepage-proof layer is used to contact the pile body formed by the subsequent pouring of concrete.

[0013] As a preferred technical solution: Step S5 specifically includes: Lower the steel cage until the anti-buoyancy plate is placed at the bottom of the hole, with the steel cage centered and located inside the composite thermal insulation and seepage prevention protective layer. The guide pipe is lowered into the hole; the guide pipe is used to pour concrete. A second cleaning of the hole was carried out, and concrete was poured after the cleaning was completed. Controlled-rate grouting construction includes: In the initial grouting section at the bottom of the pile, the concrete level rises from 0 to the initial grouting height. The control system maintains a low grouting speed of 8~12m³ / h to reduce the scouring energy of the concrete, avoid disturbing the sediment at the bottom of the pile, and prevent mud from being trapped at the bottom of the pile. After the concrete completely covers the bottom of the guide pipe and forms a stable burial depth, the pouring speed is increased. In the middle section of the pile, from the initial pouring height to the bottom of the reinforcement cage's denser zone, the control system dynamically adjusts the concrete pouring speed based on the tremie pipe's embedment depth. When the buried depth of the guide pipe end is 2-4m, the control system controls the pouring to be carried out at a standard pouring speed of 15-20m³ / h. When the burial depth of the guide pipe end is 4-6m, the control system controls the speed to be reduced to 80% of the standard pouring speed for pouring. When the burial depth of the guide pipe end is greater than 6m, the control system reduces the pouring speed to 50% of the standard pouring speed. In the reinforced cage densification zone at the top of the pile, the concrete level rises from the bottom of the densification zone to the top of the pile. The control system controls the pouring at a low speed of 30% to 50% of the standard pouring speed to ensure that the concrete is full and dense in the reinforced cage densification zone. In the over-pouring section at the top of the pile, the control system controls the pouring speed to be 8~12m³ / h within the specified height above the pile top, slowly venting air, reducing concrete segregation, and suppressing laitance.

[0014] As a preferred technical solution: Step S6 specifically includes: After the concrete pouring is completed and the concrete level is stable, the guide pipes are removed one by one. After the concrete has initially set but before it has fully set, the casing is removed. The composite thermal insulation and seepage prevention protective layer is then bonded to the wall of the grouting pile hole. A membrane is then laid on top of the over-grouting section of the pile and covered with thermal insulation material for full-coverage and closed curing.

[0015] As a preferred technical solution: Among them, the insulation material can be an insulation quilt.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This invention effectively achieves composite positioning of the steel cage from the bottom to the top of the pile by adding an anti-buoyancy plate at the bottom of the steel cage, adding an anti-buoyancy rib plate in the middle, and supplementing the existing cage top constraint, thus completely eliminating the floating, displacement, and movement of the cast-in-place pile steel cage. Simultaneously, segmented speed-controlled grouting construction is adopted, dividing the underwater concrete grouting of the cast-in-place pile into four segments: the initial grouting segment at the pile bottom, the middle segment, the reinforced concrete cage densification zone at the pile top, and the over-grouting segment at the pile top. Different target grouting speeds are set, and speed adjustments are made for different segments to achieve precise and controllable grouting throughout the entire process. This effectively avoids many problems such as reinforced concrete cage floating, pile breakage, and defects in pile integrity, while taking into account multiple effects such as sediment protection, anti-floating, anti-segregation, and pile top compaction. The design of anti-floating plates and anti-floating ribs, as well as the use of an intelligent speed control system (controller), achieves standardized and digital construction, eliminates reliance on manual experience, and ensures high stability of construction quality.

[0017] For the extremely cold regions of high altitudes, a composite thermal insulation and seepage-proof protective layer is applied to the borehole walls for the permafrost layer and below. This integrated structure, consisting of an inner seepage-proof layer, a middle thermal insulation layer, and an outer wear-resistant and pressure-resistant layer, provides multi-dimensional protection from waterproofing, thermal insulation, and wear resistance, blocking the freeze-thaw damage path. It is precisely matched to the permafrost conditions of high altitudes and solves problems such as freeze-thaw damage, easy corrosion, and frost heave at the pile-soil interface of traditional pile foundations. Attached Figure Description

[0018] Figure 1 This is a flowchart of the anti-buoyancy construction method for cast-in-place pile reinforcement cages according to the present invention.

[0019] Figure 2 This is a structural schematic diagram of the construction of the reinforcing cage for the cast-in-place pile according to the present invention.

[0020] Icons: 1-Reinforcing cage, 2-Anti-buoyancy plate, 3-Anti-buoyancy rib, 401-Concrete level sensor one, 402-Concrete level sensor two, 403-Concrete level sensor three, 5-Composite thermal insulation and seepage prevention protective layer, 501-Inner seepage prevention layer, 502-Middle thermal insulation layer, 503-Outer wear-resistant and pressure-resistant layer, 6-Automatic flow control valve, 7-Control system, 8-Casing. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 like Figure 1 and Figure 2 As shown in the figure, this embodiment proposes a method for anti-buoyancy construction of cast-in-place pile reinforcement cages, including the following steps: S1: Pre-construction preparations; After completing the drilling and initial cleaning of the cast-in-place pile, measure the hole depth, sediment thickness, and hole wall verticality. Once all three parameters meet the design specifications, proceed to step S2; if any one of them fails to meet the specifications, clean the hole again and retest until all parameters meet the requirements.

[0023] In addition, a casing 8 is installed at the borehole opening before the cast-in-place pile is formed. The central axis of the casing 8 coincides with the central axis of the cast-in-place pile. Generally, a steel casing 8 is used.

[0024] S2: Fabricate a steel cage 1 and install anti-buoyancy plate 2 and anti-buoyancy rib 3 on it; According to the design drawings, steel cage 1 is manufactured. Steel cage 1 includes a reinforced area and an unreinforced area. The reinforced area is the upper part of steel cage 1. The anti-buoyancy plate 2 is fixedly connected to the main reinforcement at the bottom of the steel cage 1 by connecting steel bars. The anti-buoyancy plate 2 is used to be placed at the bottom of the hole. The vertical distance h between the anti-buoyancy plate 2 and the bottom of the main reinforcement is equal to the hole depth and the distance from the bottom of the steel cage 1 to the top of the hole. Multiple anti-buoyancy ribs 3 are arranged at intervals on the steel cage 1 along the length of the steel cage 1, and the anti-buoyancy ribs 3 are fixedly connected to the steel cage 1. The spacing between two adjacent anti-buoyancy ribs 3 is 4m-6m. The anti-buoyancy ribs 3 are inclined towards the main reinforcement. The anti-buoyancy ribs 3 are made of alloy material. The top of the steel cage 1 is constrained by conventional means, such as the hole lifting bar, which is erected at the hole opening and connected to the steel cage 1. In this way, the bottom, middle and top of the steel cage 1 are three-dimensionally limited, so that the steel cage 1 can be prevented from floating without any blind spots along its entire length.

[0025] S3: Deploy the monitoring system and connect it to the control system 7; The monitoring system includes a level sensor, a pressure sensor, and an automatic flow control valve 6; Three liquid level sensors are fixedly installed on the main reinforcement of the steel cage 1, namely concrete liquid level sensor 1 401, concrete liquid level sensor 2 402 and concrete liquid level sensor 3 403. Concrete liquid level sensor 1 401 is installed on the main reinforcement of the steel cage 1 at the finished surface of the initial pouring height (the initial pouring height is obtained by pre-calculation, which is the prior art). Concrete liquid level sensor 2 402 is installed at the bottom of the densified area on the main reinforcement of the steel cage 1. Concrete liquid level sensor 3 403 is installed on the main reinforcement of the steel cage 1 at the designed elevation of the pile top. A pressure sensor is installed at the end of the conduit. The pressure measured by the pressure sensor is P=ρgh (where ρ is the density of concrete, g is the acceleration due to gravity, and h is the embedment depth of the pressure sensor, i.e. the embedment depth of the conduit end in the concrete). Based on this formula, the embedment depth of the conduit end in the concrete is calculated by the control system 7. An automatic flow control valve 6 is installed on the hopper. The automatic flow control valve 6 includes a flow sensor and a valve body. The flow sensor is used to monitor the discharge flow rate in real time, and the valve body is used as an actuator to control the discharge speed and flow rate. The level sensor, pressure sensor, flow sensor, and valve body are all connected to the control system 7. The control system 7 executes a preset program and outputs instructions based on the data collected by the level sensor, pressure sensor, and flow sensor, driving the valve body to change the valve opening and realizing automatic control of the concrete pouring speed. The control system 7 has four preset control programs, which set corresponding target pouring speeds for the initial grouting section at the bottom of the pile, the middle section of the pile, the reinforced cage densification zone at the top of the pile, and the over-grouting section at the top of the pile.

[0026] The control system 7 can be a controller, while the level sensor, pressure sensor, and automatic flow control valve 6 can be existing products.

[0027] S4: Install a composite thermal insulation and seepage prevention protective layer 5 inside the grouting pile hole; Based on the depth of the frozen soil, within the range of the frozen soil layer (starting from 500mm below the frozen soil layer, i.e., from...) Figure 2 A release agent is applied to the inner wall of the casing 8 (starting 500mm below the local frost line) (the release agent is applied to facilitate the removal of the casing 8 later). Then, a composite thermal insulation and seepage prevention protective layer 5 is tightly covered on the inner wall of the casing 8. To ensure the protective effect, the bottom of the composite thermal insulation and seepage prevention protective layer 5 is set 500mm below the frost line. The composite thermal insulation and seepage prevention protective layer 5 includes an inner seepage prevention layer 501, a middle thermal insulation layer 502, and an outer wear-resistant and pressure-resistant layer 503, which are integrated into one structure. The outer wear-resistant and pressure-resistant layer 503 is used to contact the borehole wall after the casing 8 is removed, and the inner seepage-proof layer 501 is used to contact the pile body (formed after the pile body is poured with concrete later); the outer wear-resistant and pressure-resistant layer 503 is in contact with the inner wall of the casing 8 before the casing 8 is removed, and in contact with the borehole wall of the cast-in-place pile after the casing 8 is removed later. The inner seepage-proof layer 501 uses a polymer seepage-proof coating or seepage-proof roll material to completely seal the fine pores in the pile concrete, block underground capillary water and surface seepage water from seeping into the pile body and pile-soil interface, and eliminate the cause of water frost heave damage from the root. The middle insulation layer 502 uses high-strength cold-resistant insulation fillers (such as aerogel powder fillers, high-strength rock wool / basalt fiber felt, high-density PIR rigid polyurethane, etc.) to isolate the huge temperature difference between day and night and all four seasons on the plateau, reduce the temperature difference between the pile body and the surrounding frozen soil, reduce the frequency of freeze-thaw cycles, and alleviate the squeezing and damage of the pile foundation caused by the freezing heave and thawing settlement deformation of the frozen soil. The outer wear-resistant and pressure-resistant layer 503 uses hard cold-resistant protective materials (such as high-density HDPE wear-resistant geotextile protective boards) to resist mechanical wear caused by the compression of surrounding frozen soil, soil friction, and stratum displacement, and to protect the inner seepage-proof layer 501 and the middle insulation layer 502 from damage, ensuring the long-term integrity of the protection system. Preferably, the inner waterproof layer 501, the middle insulation layer 502, and the outer wear-resistant and pressure-resistant layer 503 can be combined into one piece by hot pressing or bonding in the factory, but not limited to this method.

[0028] S5: Lower the steel cage 1 and the guide pipe to carry out controlled-speed grouting construction; Lower the steel cage 1 until the anti-buoyancy plate 2 is placed at the bottom of the hole. The steel cage 1 is arranged in the center and is located inside the composite thermal insulation and seepage prevention protective layer 5. The guide pipe is lowered into the hole; the guide pipe is used to pour concrete. A second cleaning of the hole was carried out, and concrete was poured after the cleaning was completed. Controlled-rate grouting construction includes: In the initial grouting section at the bottom of the pile, the concrete level rises from 0 (i.e., the bottom of the hole) to the initial grouting height. The control system 7 controls the grouting at a low speed (8-12 m³ / h) to reduce the scouring energy of the concrete, avoid stirring and disturbing the sediment at the bottom of the pile, and eliminate the defect of mud inclusion at the bottom of the pile. After the concrete completely covers the bottom end of the guide pipe and forms a stable burial depth, the pouring speed is increased to about 15 m³ / h. In the middle section of the pile, from the initial pouring height to the bottom of the reinforcement cage 1's denser zone, the control system 7 dynamically adjusts the concrete pouring speed according to the tremie pipe embedment depth. When the burial depth of the guide pipe end is 2 (inclusive) to 4 (inclusive), the control system 7 controls the pouring at the standard pouring speed (15 to 20 m³ / h); When the buried depth of the guide pipe end is 4 (excluding 4m) to 6m (including 6m), the control system 7 controls the speed to be reduced to about 80% of the standard pouring speed for pouring; When the burial depth of the guide pipe end is greater than 6m, the control system 7 controls the speed to be reduced to about 50% of the standard pouring speed for pouring. In this way, the upward flow velocity and buoyancy of the concrete can be significantly reduced, thus preventing the steel cage 1 from floating at the source of power. In the reinforced zone of the pile top, the concrete level rises from the bottom of the reinforced zone to the top of the pile. The control system 7 controls the low-speed pouring at 30% to 50% of the standard pouring speed to make the concrete fill and compact in the reinforced zone of the reinforced cage 1. In the over-pouring section at the top of the pile, within 1.2m above the top of the pile, the control system 7 controls the pouring at a low speed (8~12m³ / h) to slowly vent air, reduce concrete segregation, and suppress laitance, strictly controlling the thickness of laitance at the top of the pile to within 20cm, which greatly improves the density and integrity of the concrete at the top of the pile.

[0029] Preferably, during the concrete pouring process, as the concrete level rises, the guide pipe is slowly raised in sections, so that the guide pipe is buried 2 to 6 meters below the concrete level. Before each pipe pull, the material feeding is paused for 30 seconds to release the pressure inside the pipe and the impact force of the concrete. The guide pipe is then slowly raised in small increments, with a single pipe pull height not exceeding 1.5 meters, to prevent negative pressure eddies from carrying the reinforcing steel bars to float.

[0030] S6: Perform final finishing touches; After the concrete pouring is completed and the concrete level is stable, the guide pipes are removed one by one. After the initial setting of the concrete but before its final setting, the casing 8 is removed, and the composite thermal insulation and seepage prevention protective layer 5 is bonded to the wall of the cast-in-place pile hole. A membrane is then laid on the top of the over-grown section of the pile and covered with thermal insulation cotton quilts for full-coverage and closed curing. This method can adapt to the low temperature, strong wind, and strong ultraviolet radiation environment of the plateau, prevent the pile concrete from freezing and cracking due to water loss in the early stage, ensure the rapid setting and hardening of low-temperature early-strength concrete, shorten the plateau construction and maintenance cycle, improve the overall forming quality and structural stability of the pile foundation, and complete the entire construction process.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for anti-buoyancy construction of reinforced concrete cages for cast-in-place piles, characterized in that: Includes the following steps: S1: Pre-construction preparations; S2: Fabricate a steel cage and install anti-buoyancy plates and anti-buoyancy ribs on it; S3: Deploy the monitoring system and connect it to the control system; S4: Install a composite thermal insulation and seepage prevention protective layer inside the grouting pile hole; S5: Lower the steel cage and guide pipe to carry out controlled-speed grouting construction.

2. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 1, characterized in that: It also includes S6: for post-production finishing touches.

3. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 1, characterized in that: Step S1 specifically includes: After completing the drilling and initial cleaning of the cast-in-place pile, measure the hole depth, sediment thickness, and verticality of the hole wall.

4. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 3, characterized in that: Step S1 also includes: Once the three parameters of hole depth, sediment thickness and hole wall verticality all meet the design specifications, proceed to step S2; if any one of them does not meet the requirements, clean the hole again and retest until all parameters meet the standards.

5. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 1, characterized in that: Step S2 specifically includes: The steel cage is manufactured according to the design drawings. The steel cage includes a reinforced area and an unreinforced area. The reinforced area is the upper part of the steel cage. The anti-buoyancy plate is fixedly connected to the main reinforcement bar at the bottom of the steel cage by connecting steel bars. The anti-buoyancy plate is used to be placed at the bottom of the hole. Multiple anti-buoyancy ribs are arranged at intervals along the length of the steel cage and fixedly connected to the steel cage; the anti-buoyancy ribs are inclined toward the main reinforcement. The top of the reinforcing cage is constrained by hanging bars at the opening.

6. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 5, characterized in that: In step S3: The monitoring system includes a level sensor, a pressure sensor, and an automatic flow control valve; Three liquid level sensors are fixedly installed on the main reinforcement of the steel cage, namely concrete liquid level sensor one, concrete liquid level sensor two and concrete liquid level sensor three. Concrete liquid level sensor one is installed on the main reinforcement of the steel cage at the finished surface of the initial pouring height. Concrete liquid level sensor two is installed on the bottom of the densified area on the main reinforcement of the steel cage. Concrete liquid level sensor three is installed on the main reinforcement of the steel cage at the design elevation of the pile top. A pressure sensor is installed at the end of the conduit. The pressure measured by the pressure sensor is P=ρgh. The control system calculates the embedment depth of the conduit end in the concrete. An automatic flow control valve is installed on the hopper. The automatic flow control valve includes a flow sensor and a valve body. The flow sensor is used to monitor the discharge flow rate in real time, and the valve body is used as an actuator to control the discharge speed and flow rate. The level sensor, pressure sensor, flow sensor, and valve body are all connected to the control system. The control system executes a preset program and outputs commands based on the data collected by the level sensor, pressure sensor, and flow sensor, driving the valve body to change the valve opening and thus achieving automatic control of the concrete pouring speed.

7. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 6, characterized in that: In step S3: The control system has four preset control programs, which set corresponding target pouring speeds for the initial pouring section at the bottom of the pile, the middle section of the pile, the reinforced cage densification zone at the top of the pile, and the over-pouring section at the top of the pile.

8. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 1, characterized in that: Step S4 specifically includes: According to the depth of the frozen soil, a release agent is applied to the inner wall of the casing within the frozen soil layer. Then, a composite thermal insulation and seepage prevention protective layer is covered on the inner wall of the casing. The composite thermal insulation and seepage prevention protective layer includes an inner seepage prevention layer, a middle thermal insulation layer and an outer wear-resistant and pressure-resistant layer, which are integrated into one structure. The outer wear-resistant and pressure-resistant layer is used to contact the borehole wall after the casing is removed, and the inner seepage-proof layer is used to contact the pile body formed by the subsequent pouring of concrete.

9. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 7, characterized in that: Step S5 specifically includes: Lower the steel cage until the anti-buoyancy plate is placed at the bottom of the hole, with the steel cage centered and located inside the composite thermal insulation and seepage prevention protective layer. The guide pipe is lowered into the hole; the guide pipe is used to pour concrete. A second cleaning of the hole was carried out, and concrete was poured after the cleaning was completed. Controlled-rate grouting construction includes: In the initial grouting section at the bottom of the pile, the concrete level rises from 0 to the initial grouting height. The control system maintains a low grouting speed of 8~12m³ / h to reduce the scouring energy of the concrete, avoid disturbing the sediment at the bottom of the pile, and prevent mud from being trapped at the bottom of the pile. After the concrete completely covers the bottom of the guide pipe and forms a stable burial depth, the pouring speed is increased. In the middle section of the pile, from the initial pouring height to the bottom of the reinforcement cage's denser zone, the control system dynamically adjusts the concrete pouring speed based on the tremie pipe's embedment depth. When the buried depth of the guide pipe end is 2-4m, the control system controls the pouring to be carried out at a standard pouring speed of 15-20m³ / h. When the burial depth of the guide pipe end is 4-6m, the control system controls the speed to be reduced to 80% of the standard pouring speed for pouring. When the burial depth of the guide pipe end is greater than 6m, the control system reduces the pouring speed to 50% of the standard pouring speed. In the reinforced cage densification zone at the top of the pile, the concrete level rises from the bottom of the densification zone to the top of the pile. The control system controls the pouring at a low speed of 30% to 50% of the standard pouring speed to ensure that the concrete is full and dense in the reinforced cage densification zone. In the over-pouring section at the top of the pile, the control system controls the pouring speed to be 8~12m³ / h within the specified height above the pile top, slowly venting air, reducing concrete segregation, and suppressing laitance.

10. The anti-buoyancy construction method for cast-in-place pile reinforcement cages according to claim 2, characterized in that: Step S6 specifically includes: After the concrete pouring is completed and the concrete level is stable, the guide pipes are removed one by one. After the concrete has initially set but before it has fully set, the casing is removed. The composite thermal insulation and seepage prevention protective layer is then bonded to the wall of the grouting pile hole. A membrane is then laid on top of the over-grouting section of the pile and covered with thermal insulation material for full-coverage and closed curing.

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