Non-destructive positioning method and device for existing pile foundations

Abstract

The present application relates to a pile foundation non-destructive positioning method and device, wherein the non-destructive positioning method comprises: extracting initial pile foundation information in a to-be-tested area, and demarcating a first dynamic measurement path according to a projection area of an initial pile foundation reinforcement cage position contained in the initial pile foundation information on the ground surface; vertically transmitting a first electromagnetic wave into the ground along the first dynamic measurement path, and receiving a first electromagnetic echo reflected by the ground; forming a first electromagnetic echo waveform diagram and analyzing to obtain current pile foundation reinforcement cage position information and pile foundation fracture deviation position information. The present application can accurately position the pile foundation fracture deviation position and reinforcement distribution information by using two-stage non-destructive accurate positioning of the pile foundation in the to-be-tested area by electromagnetic waves of different frequencies, thereby providing accurate information for subsequent further detection to reduce equipment loss of subsequent detection and reduce damage to the pile foundation structure.

Description

Technical Field

[0001] This invention belongs to the field of pile foundation testing technology, and specifically relates to a non-destructive positioning method and device for existing pile foundations. Background Technology

[0002] In water conservancy and hydropower construction projects, due to the complex and harsh geological environment, reinforced concrete cast-in-place piles and pipe piles are often used as part of the foundation structure. In actual projects, it is common to encounter situations where, after the project is completed, due to the harsh environment and the effects of water, the building structure may experience dam displacement, foundation settlement, or other issues after a period of use. This may be caused by the hollowing out of the foundation structure or the breakage and displacement of the foundation piles. In such cases, it is necessary to use the core drilling method to test the original pile foundation.

[0003] Since these are already completed projects, the original pile positions are often obscured by cast-in-place beams and backfilling. Therefore, the core drilling points need to be repositioned. Currently, pile positioning often relies on surveying and marking points, estimating the current location of the foundation piles using displacement monitoring and data from the original pile positions. However, without original pile position data, positioning errors are prone to occur, causing the drilling rig to deviate from the pile or even drill into the reinforcing steel, damaging the drill bit and the pile foundation, resulting in unnecessary time and economic losses. Alternatively, excavating with an excavator to expose the capping beam pile heads requires a large working space, results in extensive damage, and has a long operation period. Summary of the Invention

[0004] The purpose of this invention is to provide a non-destructive positioning method and device for existing pile foundations, so as to solve the problems that existing pile foundation positioning technology is prone to pile foundation positioning deviation, large workload and long time of pile foundation positioning, and easy to cause unnecessary equipment damage and pile foundation structure damage.

[0005] The technical solution provided by this invention to solve its technical problem is as follows:

[0006] In a first aspect, the present invention provides an existing non-destructive positioning method for pile foundations, comprising: extracting initial pile foundation information in the area to be tested; delineating a first dynamic testing path based on the projection area of ​​the initial pile foundation reinforcement cage position on the ground surface contained in the initial pile foundation information; transmitting a first electromagnetic wave vertically into the ground along the first dynamic testing path and receiving a first electromagnetic echo reflected from the ground; forming a waveform diagram of the first electromagnetic echo and analyzing it to obtain the current pile foundation reinforcement cage position information and pile foundation fracture deviation position information.

[0007] Secondly, the present invention provides an existing non-destructive positioning device for pile foundations, comprising: a transmitting unit for transmitting electromagnetic waves of no less than two main frequency ranges along a dynamic measurement path according to control commands, within a set range, direction, and angle; a receiving unit for receiving and transmitting a first electromagnetic echo reflected by a medium layer through which the first electromagnetic wave passes and a second electromagnetic echo reflected by a medium layer through which the second electromagnetic wave passes; and a main control unit for issuing control commands to the transmitting unit, storing, processing, and displaying the first and second electromagnetic echoes transmitted by the receiving unit to form a first electromagnetic echo waveform diagram and a second electromagnetic echo waveform diagram, and analyzing the first electromagnetic echo waveform diagram, the second electromagnetic echo waveform diagram, and the combination thereof to obtain pile foundation positioning information.

[0008] The beneficial effects of this invention include:

[0009] This invention employs electromagnetic waves of different frequencies in a two-stage, non-destructive, and precise positioning method for pile foundations in the test area. The first stage involves scanning the pile foundations in the test area with high-frequency electromagnetic waves and using echo analysis to determine the position of each pile's reinforcing cage, thus pinpointing the current location of the pile. The second stage involves using low-frequency electromagnetic waves to perform a tomographic scan on each pile, obtaining information on the position of the reinforcing cage and / or internal reinforcing bars, as well as the location of pile fractures and deviations. This allows for precise positioning of the pile fracture and deviation locations and the distribution of reinforcing bars, providing accurate information for subsequent testing and reducing equipment wear and damage to the pile foundation structure. Attached Figure Description

[0010] The invention will now be further described with reference to the accompanying drawings.

[0011] Figure 1 This is a flowchart of the non-destructive positioning method for existing pile foundations provided in an embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of the first dynamic testing path arrangement and a schematic diagram of the first electromagnetic wave transmission and reception provided in an embodiment of the present invention;

[0013] Figure 3 This is a flowchart of the initial pile foundation positioning steps provided in an embodiment of the present invention;

[0014] Figure 4 This is a schematic diagram of the second dynamic measurement path arrangement and a schematic diagram of the second electromagnetic wave transmission and reception provided in the embodiments of the present invention;

[0015] Figure 5 This is a schematic diagram of the structure of the non-destructive positioning device for existing pile foundations provided in an embodiment of the present invention.

[0016] Attached image labels:

[0017] 1-Pile foundation reinforcement cage; 2-Ground surface; 3-First dynamic measurement path; 31-Outer perimeter line; 32-Diameter line; 41-First electromagnetic wave; 42-First electromagnetic echo; 5-Second grid-shaped dynamic measurement path; 51-Parallel dynamic measurement line; 52-Vertical dynamic measurement line; 61-Second electromagnetic wave; 62-Second electromagnetic echo. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0019] Before the use of core drilling to inspect pile foundations, existing pile foundation positioning methods were often not precise enough, leading to damage to drilling equipment and pile foundation structure during the core drilling process. This invention uses non-destructive testing to determine the distribution of reinforcing bars and reinforcing cages, thereby determining the actual location of underground cast-in-place piles and pipe piles, and identifying the pile center. This facilitates the use of core drilling to inspect the integrity of the pile body, concrete strength, and the characteristics of the bearing stratum at the pile bottom. It also allows for the precise location of the pile body to study and analyze the specific causes of foundation displacement and settlement, and to formulate specific repair plans.

[0020] The earth is composed of different rocks, mineral bodies, and various geological structures, possessing different electrochemical properties such as conductivity, magnetism, and dielectric properties. In foundation engineering, backfill soil, concrete, and reinforcing steel have significantly different physical properties such as resistivity and conductivity. By applying an electromagnetic field to the foundation engineering and using specialized receiving equipment to receive the electromagnetic field, the computer automatically analyzes its data characteristics to locate the displaced or settled foundation piles, providing accurate data for further detection and analysis of the causes of problems.

[0021] Please refer to Figure 1 , 2 This invention provides a non-destructive positioning method for existing pile foundations, comprising the following steps: S1, extracting initial pile foundation information from the area to be tested, and delineating a first dynamic testing path 3 based on the projection area of ​​the initial pile foundation reinforcement cage 1 position on the ground surface 2 contained in the initial pile foundation information; S2, transmitting a first electromagnetic wave 41 vertically into the ground along the first dynamic testing path 3, and receiving a first electromagnetic echo 42 reflected from the ground; S3, forming a waveform diagram of the first electromagnetic echo 42 and analyzing it to obtain the current position information of the pile foundation reinforcement cage 1 and the pile foundation fracture deviation position information.

[0022] Specifically, most construction projects have foundation data for pile foundations. If the project is undergoing completion inspection or routine testing, or if the degree of displacement or settlement is minor, the existing foundation data can be directly used as the initial pile foundation information. The area to be tested refers to the area with displacement or settlement that needs to be inspected or delineated. Since the outer ring of concrete in the pile foundation structure is often larger than the outer circumference of the reinforcing cage or internal steel bars, the dynamic testing path is delineated by the outer ring of the reinforcing cage or steel bars. Electromagnetic emission and retrieval equipment is placed on the ground surface along the dynamic testing path to perform non-destructive positioning testing. This allows for scanning for fractures and displacements within the pile foundation, including the concrete and steel bar areas. Because the scanning is performed in the same medium perpendicular to the ground surface, low-frequency electromagnetic waves have greater penetrating power and are more sensitive, clear, and recognizable to reflected signal waves from fracture surfaces in the medium layer, making them suitable for tomographic scanning.

[0023] Furthermore, for some construction projects with a long service life, the initial pile foundation information is no longer available, or the displacement or settlement has been significant due to adverse geological conditions or other reasons. In such cases, initial pile foundation positioning is required before the aforementioned non-destructive positioning. Please refer to [the relevant documentation]. Figure 3 , Figure 4 In the absence of initial pile foundation information or with a large degree of pile foundation fracture and displacement, the initial pile foundation positioning specifically includes the following steps: S01, on the ground surface 2 of the area to be measured, several parallel dynamic measurement lines 51 and several dynamic measurement lines 52 perpendicular to the parallel dynamic measurement lines are demarcated to form a second grid-like dynamic measurement path 5; S02, along the second grid-like dynamic measurement path 5, a second electromagnetic wave 61 is sent underground at a set range, direction, and angle, and the second electromagnetic echo 62 reflected from the ground is received; S03, a waveform diagram of the second electromagnetic echo 62 is formed and analyzed to obtain the initial pile foundation information including the location of the initial pile foundation reinforcement cage 1.

[0024] Specifically, in the area to be inspected, there are one or more pile foundations. To locate their positions, the electromagnetic wave scanning range is relatively large. The scanning media layers include soil, rock, and the steel reinforcement and concrete layers of the pile foundations. Because the propagation speed of high-frequency electromagnetic waves varies significantly in different media, especially metals and other media, high-frequency electromagnetic waves are more effective for locating steel reinforcement / cages over large areas. The scanning direction and angle of the dynamic measurement line should ideally be based on the comprehensive yet non-repetitive scanning of the second grid-shaped dynamic measurement path planned in this scheme. The electromagnetic wave emission along the moving direction of the dynamic measurement path should be a fan shape with an amplitude of approximately 45 degrees on both sides. The inclination angle from forward to downward should ideally be within 90 degrees and around 45 degrees. The specific setting should be determined through testing to cover different pile foundations with corresponding pile depths, diameters, and lengths.

[0025] For further information, please continue to refer to [link / reference]. Figure 2The first dynamic measurement path 3 includes an outer perimeter line 31 projected onto the ground surface 2 along the initial pile foundation reinforcement cage 1 position, and several diameter lines 32 evenly distributed along the outer perimeter line 31.

[0026] Specifically, the first dynamic testing path 2 should ideally have at least three monitoring points within the range from the outer perimeter to the inner diameter of the cross-section of the pile foundation parallel to the ground. This scheme uses the outer perimeter line 31 projected onto the ground surface 2 of the pile foundation reinforcement cage 1 and several diameter lines 32 as the first dynamic testing path 3. For pile foundations with smaller diameters, two perpendicular diameter lines 32 are sufficient to meet the testing standards. If the pile foundation diameter is larger, more than two diameter dynamic testing lines can be planned. By combining the first dynamic testing path 3 with the first electromagnetic wave 41 using low-frequency electromagnetic waves, the entire pile foundation can be penetrated from top to bottom for tomographic scanning, and the steel reinforcement and concrete can be distinguished, providing accurate information for subsequent core drilling operations.

[0027] Furthermore, the main frequency range of the first electromagnetic wave 41 is set to identify the fracture displacement location of the same medium by analyzing its echo energy.

[0028] Specifically, the first electromagnetic wave 41 uses a low-frequency electromagnetic wave, which has stronger penetrating power and is more suitable for scanning the cross-section and depth of the same medium layer.

[0029] For further information, please continue to refer to [link / reference]. Figure 4 The grid size of the second grid-shaped dynamic testing path 5 is adjusted so that the extended line of the axis of each initial pile foundation steel cage 1 intersects with the grid intersection point of the second grid-shaped dynamic testing path 5.

[0030] The advantage of using a grid-like dynamic measurement path is that it provides a more comprehensive scanning surface when the area to be measured is large. However, when the location, diameter, and length of the pile foundations are unclear, it is necessary to perform multiple small-scale tests and adjustments to the grid size to ensure that the axis of each pile foundation coincides with the intersection of the grid. This results in a more balanced electromagnetic wave scanning and more accurate waveform analysis.

[0031] Furthermore, the main frequency range of the second electromagnetic wave 61 is set to be able to distinguish between the steel reinforcement layer and other dielectric layers.

[0032] Specifically, the second electromagnetic wave 61 is a high-frequency electromagnetic wave. The loss of high-frequency electromagnetic waves varies in different dielectric layers. In particular, the echo waveforms of high-frequency electromagnetic waves are significantly different when passing through metallic and non-metallic dielectric layers, which helps to identify and distinguish the steel cage / internal steel bars from other dielectric layers.

[0033] Furthermore, the first electromagnetic echo waveform 42 and the second electromagnetic echo waveform 62 are extracted and analyzed together to form the position, spacing, diameter and length information of the current pile foundation reinforcement cage and / or internal reinforcement.

[0034] Specifically, the first electromagnetic echo waveform (42 waveforms) can distinguish and identify information about the reinforcing cage / reinforcing bar and other media layers, while the second electromagnetic echo waveform (62 waveforms) can better identify information such as the diameter and length of the reinforcing bar within the same medium, the spacing between reinforcing bars, and the length of the reinforcing bar. By analyzing both together, the reinforcing bar and concrete can be clearly located and distinguished, including offset information, providing accurate data for subsequent core drilling operations, thereby reducing drill bit wear and damage to the pile foundation structure.

[0035] Please refer to Figure 5 The present invention also provides an existing non-destructive positioning device for pile foundations, comprising: a transmitting unit for transmitting electromagnetic waves of no less than two main frequency ranges along a dynamic measurement path according to control commands, within a set range, direction, and angle; a receiving unit for receiving and transmitting a first electromagnetic echo reflected by a medium layer through which the first electromagnetic wave passes and a second electromagnetic echo reflected by a medium layer through which the second electromagnetic wave passes; and a main control unit for issuing control commands to the transmitting unit, storing, processing, and displaying the first and second electromagnetic echoes transmitted by the receiving unit to form a first electromagnetic echo waveform diagram and a second electromagnetic echo waveform diagram, and analyzing the first electromagnetic echo waveform diagram, the second electromagnetic echo waveform diagram, and the combination thereof to obtain pile foundation positioning information.

[0036] Specifically, when the first electromagnetic wave is vertically transmitted underground, the transmitting and receiving units are located at the same dynamic measurement point. The reflected echo reflects information about faulting or displacement that occurs when penetrating the same medium layer. When the second electromagnetic wave is transmitted within a certain range, direction, and angle, the second electromagnetic wave passes through different medium layers at an inclined angle to generate echoes. In this case, the receiving unit is set on the other side of the pile foundation location, opposite to the transmitting unit. In both stages of this non-destructive testing, the transmitting and receiving units are both located on the surface dynamic measurement path. Because this two-stage testing method obtains echo signals by scanning the underground with electromagnetic waves on the surface, there is no need to drill holes or place additional control devices underground. It is a truly non-destructive testing method with very high detection accuracy.

[0037] Furthermore, the electromagnetic waves with no less than two dominant frequency ranges include: a first electromagnetic wave that can distinguish the fracture displacement location of the same medium and a second electromagnetic wave that can distinguish the steel reinforcement layer from other medium layers.

[0038] Furthermore, the pile foundation positioning information includes: initial pile foundation information, which is derived from: debugging and marking several parallel dynamic measurement lines and several dynamic measurement lines perpendicular to the parallel dynamic measurement lines on the ground surface of the area to be measured to form a second grid-like dynamic measurement path; the transmitting unit sends a second electromagnetic wave into the ground along the second grid-like dynamic measurement path at a set range, direction, and angle; the receiving unit receives the second electromagnetic echo reflected from the ground and transmits it to the main control unit; the main control unit generates a second electromagnetic echo waveform diagram based on the second electromagnetic echo and analyzes it to obtain the initial pile foundation information including the location of the initial pile foundation reinforcement cage; and current pile foundation information, which is derived from: the initial pile foundation information extracted by the main control unit from the area to be measured. The system uses a non-destructive testing method to determine the first dynamic testing path based on the projection area of ​​the initial pile foundation reinforcement cage position on the ground surface, as contained in the initial pile foundation information. The transmitting unit continuously transmits a first electromagnetic wave vertically into the ground along this path. The receiving unit receives the first electromagnetic echo reflected from the ground and transmits it to the main control unit. The main control unit generates a first electromagnetic echo waveform diagram based on the first electromagnetic echo and analyzes it to obtain the current pile foundation reinforcement cage position information and pile foundation fracture deviation location information. The current pile foundation reinforcement cage and / or internal reinforcement information is obtained by the main control unit through joint analysis of the first and second electromagnetic echo waveform diagrams, determining the position, spacing, diameter, and length of the current pile foundation reinforcement cage and / or internal reinforcement. This precise pile foundation positioning information obtained through this non-destructive testing can be used to assess the basic health of the building's pile foundation and also to provide accurate information for subsequent further testing.

[0039] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. For those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. This specification should not be construed as a limitation of the present invention.

Claims

1. A non-destructive positioning method for existing pile foundations, characterized in that, The method includes the following steps: S1, extract the initial pile foundation information in the area to be measured, and delineate the first dynamic measurement path based on the projection area of ​​the initial pile foundation reinforcement cage position on the ground surface contained in the initial pile foundation information. S2, emits a first electromagnetic wave vertically into the ground along the first dynamic testing path, and receives the first electromagnetic echo reflected from the ground. S3, generate the first electromagnetic echo waveform and analyze it to obtain the current pile foundation reinforcement cage position information and pile foundation fracture deviation position information; If the initial pile foundation information is unavailable or the pile foundation fracture deviation is significant, an initial pile foundation positioning step is included before step S1, specifically including: S01, In the area to be measured, several parallel dynamic measurement lines and several dynamic measurement lines perpendicular to the parallel dynamic measurement lines are delineated on the ground surface to form a second grid-like dynamic measurement path; S02, send the second electromagnetic wave into the ground along the second grid-shaped dynamic measurement path in a set range, direction and angle, and receive the second electromagnetic echo reflected from the ground; S03, form the second electromagnetic echo waveform and analyze it to obtain the initial pile foundation information including the position of the initial pile foundation reinforcement cage; The first dynamic testing path includes an outer perimeter line projected onto the ground along the initial pile foundation reinforcement cage position, and several diameter lines evenly distributed along the outer perimeter line. The first electromagnetic wave is a low-frequency electromagnetic wave, and the second electromagnetic wave is a high-frequency electromagnetic wave.

2. The non-destructive positioning method for existing pile foundations according to claim 1, characterized in that, The first electromagnetic wave frequency range is set to identify the fracture displacement location of the same medium by analyzing its echo energy.

3. The non-destructive positioning method for existing pile foundations according to claim 1, characterized in that, The grid size of the second grid-like dynamic testing path is adjusted so that the extended axis of each initial pile foundation reinforcement cage position intersects with the grid intersection point of the second grid-like dynamic testing path.

4. The non-destructive positioning method for existing pile foundations according to claim 1, characterized in that, The second electromagnetic wave frequency range is set to be able to distinguish the steel reinforcement layer from other dielectric layers.

5. The non-destructive positioning method for existing pile foundations according to claim 1, characterized in that, After step S3, step S4 is also included: extracting the first electromagnetic echo waveform and the second electromagnetic echo waveform and jointly analyzing them to form the position, spacing, diameter and length information of the current pile foundation steel cage and / or internal steel bars.

6. A non-destructive positioning device for existing pile foundations, characterized in that, include: The transmitting unit is used to transmit electromagnetic waves of no less than two main frequency ranges along the dynamic test path according to the control command and within the set range, direction, and angle. The receiving unit is used to receive and transmit the first electromagnetic echo reflected by the dielectric layer through which the first electromagnetic wave passes and the second electromagnetic echo reflected by the dielectric layer through which the second electromagnetic wave passes. The main control unit is used to send control commands to the transmitting unit, and to store, process and display the first electromagnetic echo and the second electromagnetic echo transmitted by the receiving unit to form the first electromagnetic echo waveform diagram and the second electromagnetic echo waveform diagram, and to analyze the first electromagnetic echo waveform diagram, the second electromagnetic echo waveform diagram and the combination of the two to obtain the pile foundation positioning information; The pile foundation positioning information includes: The initial pile foundation information is derived from: debugging and marking several parallel dynamic measurement lines and several dynamic measurement lines perpendicular to the parallel dynamic measurement lines on the ground surface of the area to be measured to form a second grid-shaped dynamic measurement path; the transmitting unit sends a second electromagnetic wave into the ground along the second grid-shaped dynamic measurement path with a set range, direction, and angle; the receiving unit receives the second electromagnetic echo reflected from the ground and transmits it to the main control unit; the main control unit forms a second electromagnetic echo waveform diagram based on the second electromagnetic echo and analyzes it to obtain the initial pile foundation information including the location of the initial pile foundation reinforcement cage. The current pile foundation information is derived from: the main control unit extracts the initial pile foundation information in the area to be measured, delineates the first dynamic measurement path based on the projection area of ​​the initial pile foundation reinforcement cage position on the ground surface contained in the initial pile foundation information, the transmitting unit continuously transmits the first electromagnetic wave vertically into the ground along the first dynamic measurement path, the receiving unit receives the first electromagnetic echo reflected from the ground and transmits it to the main control unit, the main control unit forms the first electromagnetic echo waveform based on the first electromagnetic echo and analyzes it to obtain the current pile foundation reinforcement cage position information and pile foundation fracture deviation position information; Current pile foundation reinforcement cage and / or internal reinforcement information: The main control unit generates the current pile foundation reinforcement cage and / or internal reinforcement information, including position, spacing, diameter and length, based on the first electromagnetic echo waveform and the second electromagnetic echo waveform. The first dynamic testing path includes an outer perimeter line projected onto the ground along the initial pile foundation reinforcement cage position, and several diameter lines evenly distributed along the outer perimeter line. The first electromagnetic wave is a low-frequency electromagnetic wave, and the second electromagnetic wave is a high-frequency electromagnetic wave.

7. The non-destructive positioning device for pile foundations according to claim 6, characterized in that, The electromagnetic waves with no less than two dominant frequency ranges include: a first electromagnetic wave that can distinguish the fracture displacement location of the same medium and a second electromagnetic wave that can distinguish the steel reinforcement layer from other medium layers.

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