Pile foundation self-balancing counter-force device and pile foundation detection method

Abstract

The invention relates to the field of pile foundation detection, and particularly discloses a pile foundation self-balancing counter-force device and a pile foundation detection method.The pile foundation self-balancing counter-force device comprises a steel reinforcement cage, a counter-force box and a detection module, the steel reinforcement cage comprises vertical steel bars, annular steel bars and at least three guide steel bars, the guide steel bars are vertically arranged and evenly distributed with the vertical steel bars, and the counter-force box is connected with the detection module; the annular reinforcing steel bars are bound on the vertical reinforcing steel bars and the guide reinforcing steel bars, and a first guide groove and a second guide groove are formed in the side, facing the interior of the reinforcement cage, of each guide reinforcing steel bar; the counter-force box is arranged in the second guide groove in a sliding mode, and the detection module is arranged in the first guide groove in a sliding mode. The detection module comprises an industrial camera. The invention aims to solve the technical problem of how to determine the friction force balance point.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pile foundation detection, and specifically discloses a pile foundation self-balancing counterforce device and a pile foundation detection method. BACKGROUND

[0002] Pile foundation bearing capacity detection is a core link to ensure engineering safety. The traditional methods mainly include the pile loading method and the anchor pile method. The pile loading method needs to stack hundreds to thousands of tons of counterweights on the top of the pile, which has problems such as large site occupation, high material transportation cost, and significant safety hazards, and is only suitable for pile foundations with a bearing capacity of less than 1000 tons. The anchor pile method can achieve large-tonnage loading, but it needs to pre-construct anchor piles and counterforce frames, which has a long cycle and high cost, and is difficult to implement in narrow sites, slopes or water environments. Both methods rely on external counterforce systems and cannot meet the detection needs of large-diameter super-long piles (>40m) and special sites in modern engineering.

[0003] In the prior art, a self-balancing method uses the side friction and end resistance of the pile to form a counterforce by embedding a load box (counterforce box), which avoids external pile loading and improves site adaptability. However, this method still has the following technical problems: 1. The embedding position of the load box needs to be accurately calculated to balance the resistance of the upper and lower piles. Deviation of geological parameters or variation of soil layers can easily cause the resistance on one side to fail prematurely, resulting in distorted test results, and even causing the pile to be "topped out" or unable to measure the true ultimate load; 2. The load box occupies the space of the pile hole (the hole diameter is reduced by about 50%), and the debris scraped off during the placement of the reinforcement cage cannot be easily removed, affecting the quality of the pile concrete.

[0004] In the above two technologies, for technical problem 1, geological exploration is conducted during the early stages of the project, but the soil structure is not planar, so the soil structure at each location is different and even has a large deviation. There is no good way to solve this problem, and only by conducting on-site exploration of the test pile hole can the friction balance point be determined. However, in actual practice, there is generally no further exploration, resulting in a significant defect in the self-balancing counterforce box detection method. For technical problem 2, there is certainly debris during the placement of the reinforcement cage, and there is a lot of debris. The only way that can meet the actual situation is manual debris removal, but this scheme is time-consuming and labor-intensive, and has a low safety factor, so debris removal is not performed in the actual situation. SUMMARY

[0005] Therefore, the present application aims to provide a pile foundation self-balancing counterforce device and a pile foundation detection method to solve the technical problem of how to determine the friction balance point.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A self-balancing reaction force device for pile foundations includes a reinforcing cage, a reaction box, and a detection module. The reinforcing cage includes vertical reinforcing bars, ring reinforcing bars, and guide reinforcing bars. There are at least three guide reinforcing bars, which are vertically arranged and evenly distributed with the vertical reinforcing bars. The ring reinforcing bars are tied to the vertical reinforcing bars and the guide reinforcing bars. A first guide groove and a second guide groove are provided on the side of the guide reinforcing bars facing the inside of the reinforcing cage. The reaction box is slidably disposed in the first guide groove, and the detection module is slidably disposed in the second guide groove. The detection module includes an industrial camera.

[0007] In this scheme, the reaction box can slide up and down in the second guide groove to adjust its position, and the industrial camera can move from bottom to top in the first guide groove to photograph the soil layer in the pile hole. Then, the photographed soil layer image is analyzed to analyze the soil layer type and length, and the soil layer friction equilibrium point is calculated.

[0008] Optionally, the detection module includes a cable displacement sensor, and a first steel cable is mounted on the industrial camera, with the first steel cable positioned on the cable displacement sensor. The cable displacement sensor is small in size, easy to carry, provides accurate detection, is relatively inexpensive, and highly practical.

[0009] Optionally, the middle of the first guide groove is located within the second guide groove, which is located at the middle of the guide reinforcement bar. The first guide groove vertically penetrates the guide reinforcement bar. Several slots are vertically arranged on both sides of the inner wall of the second guide groove, and ratchet teeth that can only rotate upwards are rotatably installed within these slots. Using this design, when the reaction box is placed in the second guide groove, upward movement of the reaction box can drive the ratchet teeth to rotate inwards, while downward movement of the reaction box will be blocked by the ratchet teeth. This achieves the function of unidirectional upward movement of the reaction box.

[0010] Optionally, the industrial camera includes a first camera and a second camera. A release groove is formed at the connection between the first guide groove and the lower end of the second guide groove. The first camera is provided with a first sliding base, which is slidably disposed at the lower part of the first guide groove. The first sliding base and the first camera can be disengaged from the release groove. The second camera is provided with a second sliding base, which is slidably disposed at the upper part of the first guide groove. The second sliding base can be disengaged from the upper end of the first guide groove. Both the first and second sliding bases are connected to a first steel cable. The reaction box is provided with several sets of pulley units, each set of pulley units corresponding to a detection module. Each set of pulley units includes four positioning pulleys, which are respectively disposed on the outer side of the upper end, the inner side of the upper end, the outer side of the lower end, and the inner side of the lower end of the reaction box. The first steel cable is disposed on the four positioning pulleys. When the first steel cable drives the first camera and the second camera to move, the first camera and the second camera can move upward under the limit of the first guide groove, ensuring the stable movement of the first camera and the second camera. When the first camera moves to the lower part of the reaction box, the first camera can be disengaged from the release groove and continue to move upward.

[0011] Optionally, at least 10% of the ring reinforcement bars are welded to the guide reinforcement bars. This method allows for a more stable connection between the guide reinforcement bars and the ring reinforcement bars.

[0012] Optionally, the reaction box is equipped with several pull rings, and each pull ring is equipped with a steel cable and a second steel cable. The second steel cable can be installed on a rope displacement sensor. In this configuration, the steel cable is mainly used to pull the reaction box upwards, and the second steel cable is mainly used to install on the rope displacement sensor for calculating the movement height.

[0013] Optionally, a limit block is provided on the reaction box, and the limit block is located in the gap of the vertical reinforcing bar. This design prevents the reaction box from rotating.

[0014] A method for detecting a self-balancing reaction force device in a pile foundation includes the following steps: S1, install the first camera at the bottom of the first guide groove, install the second camera at the bottom of the first guide groove, and connect the first camera and the second camera simultaneously using the first steel cable; install the reaction box at the bottom of the second guide groove, connect the steel cable to the pull ring, and tie the bottom of the second steel cable to the bottom of the steel cable. S2, set the first steel cable to the rope displacement sensor, lower the steel cage to the bottom of the pile hole, and the rope displacement sensor records the travel data of the first steel cable during the lowering process; S3, pull the first steel cable at a constant speed, and simultaneously start the first and second cameras to take pictures; S4, collect videos captured by the first and second cameras and analyze the location of the on-site frictional resistance equilibrium point; S5, Analysis Method: Step 1: Calculate the continuous length L of each soil layer by combining the camera movement speed (v) and frame time difference (Δt). i =v×(t 1,i -t 2,i ), where v is the moving speed of the first camera / second camera, t1 is the last time the soil layer appears, and t2 is the first time the soil layer appears; Step 2, calculate the total side friction provided by each soil layer: F s,i =q s,i ×π×D×L i ;where q s,i πD represents the standard value of the side skin friction of the soil layer. This standard value varies for different types of soil layers. D is the pile diameter, and πD is the pile perimeter. Step 3: Calculate the embedment depth H of the reaction box, so that the total side friction Fs of the pile segment above the load box is approximately equal to the sum of the total side friction Fs and the end resistance Fs of the pile segment below the load box. s,下 +F b ; Side friction resistance above the load cell: F s,上 =∑ k i=1k F s,i k represents the number of soil layers above a burial depth H; Side friction resistance + end resistance below the load cell: F s,下 +F b =∑ n j=k+1 F s,j +q b ×A b ;in, q b This is the standard value of end resistance. Ab = πD 2 / 4 is the cross-sectional area of ​​the pile tip; S6. After calculating the burial depth H of the reaction box, the reaction box is pulled to the designated position by steel cable. The ratchet can support the reaction box from below. Then, concrete is poured to form a pile for testing.

[0015] The working principle and beneficial effects of this solution are as follows: In this solution, the existing steel cage was improved by replacing some of the vertical steel bars with guide steel bars. The guide steel bars can be used to guide the industrial camera. As the industrial camera moves upward, it can photograph the soil layer inside the pile hole. Then, image analysis is performed to calculate the friction equilibrium point of the entire pile hole. Finally, the reaction box is moved to the position of the equilibrium point. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment; Figure 2 A partial structural diagram of the guide steel bars, detection module, and reaction box; Figure 3 This is an enlarged view of part of the structure of the second guide groove; Figure 4 This is a partial structural diagram of the reaction box.

[0017] The following are the markings in the attached diagram: 1. Vertical reinforcing bar; 2. Guide reinforcing bar; 3. Ring reinforcing bar; 4. Extension section; 5. Reaction box; 6. First guide groove; 7. Second guide groove; 8. Ratchet; 9. Second camera; 10. Positioning pulley; 11. Pull rope displacement sensor; 12. First steel cable; 13. First camera; 14. Pull ring; 15. Limiting block; 16. Slot; 17. Return spring; 18. Second sliding base; 19. Second protective cover; 20. Steel cable; 21. Second steel cable. Detailed Implementation

[0018] The following detailed description illustrates the specific implementation method: Example A self-balancing reaction force device for pile foundations includes a steel cage, a reaction box 5, and a detection module.

[0019] The reinforcing cage includes vertical reinforcing bars 1, annular reinforcing bars 3, and guide reinforcing bars 2. There are at least three guide reinforcing bars 2, which are vertically arranged and evenly distributed with the vertical reinforcing bars 1. The annular reinforcing bars 3 are tied to the vertical reinforcing bars 1 and the guide reinforcing bars 2, and at least 10% of the annular reinforcing bars 3 are welded to the guide reinforcing bars 2. A trapezoidal extension 4 is integrally formed on the side of the guide reinforcing bar 2 facing the center of the reinforcing cage. A first guide groove 6 and a second guide groove 7 are provided on the extension 4. The second guide groove 7 is located in the middle of the extension 4. The upper part of the first guide groove 6 is above the second guide groove 7, and the lower part of the first guide groove 6 is below the second guide groove 7. A release groove is provided at the junction of the lower part of the first guide groove 6 and the second guide groove 7. The middle part of the first guide groove 6 is located within the second guide groove 7, and the first guide groove 6 vertically penetrates the guide reinforcing bar 2. The inner wall of the second guide groove 7 is vertically provided with several slots 16 on both sides. The slots 16 are evenly distributed. A ratchet 8 that can only rotate upward is rotatably provided in the slots 16. The arrangement is as follows: the slots 16 are rectangular, the inner end of the ratchet 8 is semi-cylindrical and rotatably provided in the slots 16, and the outer end of the ratchet 8 can be flipped upward into the slots 16. A spring groove is provided in the slots 16, and a return spring 17 is provided in the spring groove. The ratchet 8 can press the return spring 17 into the spring groove.

[0020] The reaction box 5 is slidably disposed within the second guide groove 7. Several sets of pulley units are provided on the reaction box 5, each set corresponding to a detection module. Each set of pulley units includes four positioning pulleys 10, which are respectively disposed on the outer upper side, inner upper side, outer lower side, and inner lower side of the reaction box 5. A first steel cable 12 is disposed on the four positioning pulleys 10. Several pull rings 14 are provided on the reaction box 5, and steel cables 20 and second steel cables 21 are disposed on the pull rings 14. The second steel cable 21 can be installed on the pull rope displacement sensor 11, and the lower end of the second steel cable 21 is tied to the lower end of the steel cable 20. Several limiting blocks 15 are provided on both the upper and lower sides of the reaction box 5, and the limiting blocks 15 are located in the gaps of the vertical reinforcing bars 1.

[0021] The detection module includes a cable displacement sensor 11 and an industrial camera. The industrial camera includes a first camera 13 and a second camera 9. A first protective cover is fitted over the first camera 13, and a second protective cover is fitted over the second camera 9. Each protective cover has a detachable transparent plate aligned with the lens of either the first or second camera. A first sliding base is fixedly mounted on the outer wall of the first protective cover, slidingly positioned at the lower part of a first guide groove 6. The first sliding base and the first camera 13 can be detached from a release groove. A second sliding base 18 is fixedly mounted on the outer wall of the second protective cover, slidingly positioned at the upper part of the first guide groove 6. The second sliding base 18 can be detached from the upper end of the first guide groove 6. Both the first and second sliding bases 18 are connected to a first steel cable 12. The industrial camera is equipped with the first steel cable 12, which is mounted on the cable displacement sensor 11.

[0022] A method for detecting a self-balancing reaction force device in a pile foundation includes the following steps: S1, install the first camera 13 at the bottom of the first guide groove 6, install the second camera 9 at the bottom of the first guide groove 6, and connect the first camera 13 and the second camera 9 simultaneously using the first steel cable 12; install the reaction box 5 at the bottom of the second guide groove 7, connect the steel cable 20 to the pull ring 14, and tie the bottom of the second steel cable 21 to the bottom of the steel cable 20; S2, the first steel cable 12 is set on the rope displacement sensor 11, and the steel cage is lowered to the bottom of the pile hole using a lifting device. During the lowering process, the rope displacement sensor 11 records the travel data of the first steel cable 12. S3, pull the first steel cable 12 at a constant speed, and simultaneously start the first camera 13 and the second camera 9 to take pictures; S4. Collect videos taken by the first camera 13 and the second camera 9 and conduct on-site analysis of the position of the friction resistance balance point. For the first camera 13 located below, only the images or videos taken below it are used. The rope displacement sensor 11 records the cut-off time as the uppermost end of the pile hole where the first camera 13 detaches. S5. Analysis method: Step 1. Combine the camera movement speed (v) and the frame time difference (Δt) to calculate the continuous length of each type of soil layer. The soil layer length Li = v×(t1,i - t2,i), where v is the movement speed of the first camera 13 / second camera 9, t1 is the last appearance time of the soil layer, and t2 is the first appearance time of the soil layer. Compare the total length of the calculated soil layer with the length measured by the rope displacement sensor 11. If the error is less than 5%, the next step can be continued. There are many methods for analyzing soil layer images. For example, a lightweight CNN model such as Light-SoilNet can be used to identify sandy soil, clay, loam, etc. Step 2. Calculate the total side friction resistance provided by each section of the soil layer: Fs,i = qs,i×π×D×Li; where qs,i is the standard value of the side friction resistance of the soil layer, and this standard value is different for different types of soil layers. D is the pile diameter, and πD is the pile circumference. Step 3. Calculate the buried depth H of the reaction box 5 so that the total side friction resistance Fs, upper of the pile section above the load box is approximately equal to the sum of the total side friction resistance and the end resistance of the pile section below the load box Fs, lower + Fb Side friction resistance above the load box: Fs, upper = ∑ki = 1kFs,i; k is the number of soil layer segments above the buried depth H. Side friction resistance + end resistance below the load box: Fs, lower + Fb = ∑nj = k + 1Fs,j + qb×Ab; where qb is the standard value of the end resistance, and Ab = πD2 / 4 is the pile end cross-sectional area. S6. After calculating the buried depth H of the reaction box 5, pull the reaction box 5 to the specified position through the steel cable 20. The ratchet 8 can support the reaction box 5 from below, and then pour concrete to form a pile for testing.

[0023] During specific implementation: The detection method in this embodiment can be adaptively adjusted. For example, only one industrial camera can be used, which is attached to the bottom of the vertical steel frame. During the lowering of the rebar cage, the entire soil layer can be scanned and photographed. After the photographing is complete, the industrial camera can be pulled up. However, this method requires controlling the lowering speed of the rebar cage to be uniform, while minimizing the falling of pile hole debris during the lowering process. The advantages of this method are as follows: 1. Time-saving: photographing is completed during the lowering of the rebar cage; 2. Reduced computational cost: the original method required two industrial cameras, each taking photographs separately and then summarizing the results, which was cumbersome. This method only requires one calculation, making it relatively simple.

[0024] As the reaction box 5 moves upward, it pushes the ratchet 8 above it to rotate upward and enter the slot 16. At the same time, it compresses the return spring 17. When the reaction box 5 separates from the ratchet 8, the return spring 17 pops the ratchet 8 out and returns it to the horizontal state. Then, the reaction box 5 moves downward a certain distance and can land on the ratchet 8 to complete the support.

[0025] In this embodiment, the positioning pulley 10 is set to a relatively large size to ensure that there is enough space under the positioning pulley 10 for the industrial camera to pass through. The industrial camera can be stored using mobile storage or via wired transmission. Mobile storage eliminates the need for wiring, but data needs to be transmitted before image analysis and calculation; wired transmission allows for real-time calculation, but wiring is difficult.

[0026] In this embodiment, the first steel cable 12 is first installed onto the reinforcing cage. It is not counted during installation; counting only begins when the reinforcing cage is lowered to the bottom of the pile hole. The first steel cable 12 is subtracted from the count. The first steel cable 12 can be pulled back using a drum.

[0027] The equipment used in this embodiment includes an industrial camera, a rope displacement sensor 11, a drum, and a lifting device. These devices are all mature existing technologies with multiple types and models available. The improvement lies in the installation of the guide steel bar 2 and the positioning pulley 10 of the reaction box 5. However, these improvements are very simple, so the entire self-balancing reaction device has a simple structure, low cost, and good effect. The image analysis and friction balance point calculation in this embodiment are also not complicated, but their integration with the entire process can effectively and quickly calculate the friction balance point of the pile hole, reducing the error of the pile foundation test.

[0028] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics in the solutions is not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or its practicality.

Claims

1. A self-balancing reaction force device for pile foundations, characterized in that: The system includes a reinforcing cage, a reaction box, and a detection module. The reinforcing cage includes vertical reinforcing bars, ring reinforcing bars, and guide reinforcing bars. There are at least three guide reinforcing bars, which are vertically arranged and evenly distributed with the vertical reinforcing bars. The ring reinforcing bars are tied to the vertical reinforcing bars and the guide reinforcing bars. The guide reinforcing bars have a first guide groove and a second guide groove on the side facing the inside of the reinforcing cage. The reaction box is slidably disposed in the second guide groove, and the detection module is slidably disposed in the first guide groove. The detection module includes an industrial camera.

2. The self-balancing reaction force device for pile foundations according to claim 1, characterized in that: The detection module includes a cable displacement sensor, and the industrial camera is equipped with a first steel cable, which is mounted on the cable displacement sensor.

3. The self-balancing reaction force device for pile foundations and the pile foundation testing method according to claim 2, characterized in that: The middle part of the first guide groove is located inside the second guide groove, and the second guide groove is located in the middle of the guide bar. The first guide groove vertically penetrates the guide bar. Several slots are vertically arranged on both sides of the inner wall of the second guide groove, and ratchet teeth that can only rotate upward are rotatably arranged in the slots.

4. The self-balancing reaction force device for pile foundations according to claim 3, characterized in that: The industrial camera includes a first camera and a second camera. A release groove is formed at the connection between the first guide groove and the lower end of the second guide groove. The first camera is provided with a first sliding base, which is slidably disposed at the lower part of the first guide groove. The first sliding base and the first camera can be disengaged from the release groove. The second camera is provided with a second sliding base, which is slidably disposed at the upper part of the first guide groove. The second sliding base can be disengaged from the upper end of the first guide groove. Both the first and second sliding bases are connected to a first steel cable. The reaction box is provided with several sets of pulley units. Each set of pulley units corresponds to a detection module. Each set of pulley units includes four positioning pulleys, which are respectively disposed on the outer side of the upper end, the inner side of the upper end, the outer side of the lower end, and the inner side of the lower end of the reaction box. The first steel cable is disposed on the four positioning pulleys.

5. A self-balancing reaction force device for pile foundations according to claim 4, characterized in that: At least 10% of the ring-shaped reinforcing bars are welded to the guide reinforcing bars.

6. A self-balancing reaction force device for pile foundations according to claim 5, characterized in that: The reaction box is equipped with several pull rings, and the pull rings are equipped with steel cables and second steel cables. The second steel cable can be installed on the pull rope displacement sensor.

7. A self-balancing reaction force device for pile foundations according to claim 6, characterized in that: The reaction box is equipped with a limiting block, which is located in the gap of the vertical reinforcing bar.

8. The pile foundation testing method for a self-balancing reaction force device for pile foundations according to claim 7, characterized in that, Includes the following steps: S1, install the first camera at the bottom of the first guide groove, install the second camera at the bottom of the first guide groove, and connect the first camera and the second camera simultaneously using the first steel cable; install the reaction box at the bottom of the second guide groove, connect the steel cable to the pull ring, and tie the bottom of the second steel cable to the bottom of the steel cable. S2, set the first steel cable to the rope displacement sensor, lower the steel cage to the bottom of the pile hole, and the rope displacement sensor records the travel data of the first steel cable during the lowering process; S3, pull the first steel cable at a constant speed, and simultaneously start the first and second cameras to take pictures; S4, collect videos captured by the first and second cameras and analyze the location of the on-site frictional resistance equilibrium point; S5, Analysis Method: Step 1: Calculate the continuous length L of each soil layer by combining the camera movement speed (v) and frame time difference (Δt). i =v×(t 1,i -t 2,i ), where v is the moving speed of the first camera / second camera, t1 is the last time the soil layer appears, and t2 is the first time the soil layer appears; compare the calculated total length of the soil layer with the length measured by the rope displacement sensor, and if the error is less than 5%, proceed to the next step; Step 2, calculate the total side friction provided by each soil layer: F s,i =q s,i ×π×D×L i ;where q s,i πD represents the standard value of the side skin friction of the soil layer. This standard value varies for different types of soil layers. D is the pile diameter, and πD is the pile perimeter. Step 3: Calculate the embedment depth H of the reaction box, so that the total side friction Fs of the pile segment above the load box is approximately equal to the sum of the total side friction Fs and the end resistance Fs of the pile segment below the load box. s,下 +F b Side friction resistance above the load cell: F s,上 =∑ k i=1k F s,i k represents the number of soil layers above a burial depth H; Side friction resistance + end resistance below the load cell: F s,下 +F b =∑ n j=k+1 F s,j +q b ×A b ; in, q b This is the standard value of end resistance. Ab = πD 2 / 4 is the cross-sectional area of ​​the pile tip; S6. After calculating the burial depth H of the reaction box, the reaction box is pulled to the designated position by steel cable. The ratchet can support the reaction box from below. Then, concrete is poured to form a pile for testing.

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