Three-component probe-based anchor rod nondestructive testing auxiliary device and method

Abstract

The application discloses a kind of based on three-component probe's anchor rod nondestructive testing auxiliary device, it includes three-component acceleration sensor and hammer, the hammer includes hammer shell, first steel needle, second steel needle, third steel needle, fourth steel needle, first steel ball, second steel ball, third steel ball, first spring, second spring, third spring, fourth spring, rubber connecting spring device and end, the three-component acceleration sensor of the present application can effectively eliminate the direct wave influence that is directly transmitted to sensor probe by vibration source knocking, to amplify reflected wave signal, and further improve the signal-to-noise ratio of acquisition signal, while designing knocking hammer, in the case where not increasing vibration source energy, make the incident stress wave front superposition in anchor rod, increase the propagation energy of incident stress wave, so that the reflected wave information obtained will be more abundant, especially suitable for long anchor rod deep reflected wave signal acquisition, to improve anchor rod detection efficiency and detection accuracy is higher.

Description

Technical Field

[0001] This invention relates to the field of anchor bolt anchorage quality testing technology, specifically to an auxiliary device and method for non-destructive testing of anchor bolts based on a three-component probe. Background Technology

[0002] Anchor bolt anchoring is a crucial step in support engineering, and its construction quality directly affects the safety and stability of the project, thus it is widely used in engineering construction. During non-destructive testing of anchor bolts, the direct wave energy propagating directly to the accelerometer from the anchor bolt impact is strong and has a long duration. This can suppress reflected wave signals from areas of incomplete grouting and the bottom of the hole, making it difficult for non-destructive testing to accurately and effectively capture the length of incomplete grouting sections and the overall anchor bolt length. This results in a low signal-to-noise ratio in the test data, a problem that is particularly severe in the testing of long anchor bolts.

[0003] In existing technologies, to obtain abundant stress reflection wave signals, the energy of the vibration source can be increased, thereby allowing the stress wave to propagate further. However, if the energy generated by the hammer is too high, it will cause data drift and distortion, making it difficult to effectively and comprehensively obtain various defects on the anchor bolt and the reflected wave signals at the bottom of the anchor bolt. Ultimately, this makes it difficult to determine the grouting density and length of the anchor bolt. Summary of the Invention

[0004] The purpose of this invention is to provide an auxiliary device and method for non-destructive testing of anchor bolts based on a three-component probe. This invention has a simple structure, a high signal-to-noise ratio for the test signal, and can improve the energy of reflected waves, especially the energy of deep reflected wave signals, without increasing the energy of the hammer impact.

[0005] To achieve this objective, the present invention provides an auxiliary device for non-destructive testing of anchor bolts based on a three-component probe. This device includes a three-component accelerometer sensor and a hammer. The hammer comprises a hammer housing, a first steel needle, a second steel needle, a third steel needle, a fourth steel needle, a first steel ball, a second steel ball, a third steel ball, a first spring, a second spring, a third spring, a fourth spring, a rubber connecting spring device, and an end cap. The bottom of the first steel needle is fixedly connected to the top of the second steel needle, the bottom of the second steel needle is fixedly connected to the top of the third steel needle, the bottom of the third steel needle is fixedly connected to the top of the fourth steel needle, and the bottom of the fourth steel needle is fixedly connected to the end cap. The first steel ball is restricted to slide between the rubber connecting spring device and the bottom end of the first steel needle. The second steel ball... The ball is restricted to slide between the bottom of the second steel needle and the first steel ball; the third steel ball is restricted to slide between the bottom of the third steel needle and the second steel ball. The top of the first spring is connected to the rubber connecting spring device, the bottom of the first spring is connected to the top of the first steel ball, the top of the second spring is connected to the bottom of the first steel ball, the bottom of the second spring is connected to the top of the second steel ball, the top of the third spring is connected to the bottom of the second steel ball, the bottom of the third spring is connected to the top of the third steel ball, the bottom of the third steel ball is connected to the top of the fourth spring, the bottom of the fourth spring is connected to the end. The rubber connecting spring device is placed on the top of the hammer housing. The top of the first steel needle passes through the top of the hammer housing and the rubber connecting spring device, and the end is fixed to the bottom of the hammer housing. The Z-axis component of the three-component accelerometer is parallel to the anchor rod axis.

[0006] The beneficial effects of this invention are: This invention employs a three-component accelerometer to effectively eliminate the influence of direct waves generated by vibration source impacts that are directly transmitted to the sensor probe, thereby amplifying the reflected wave signal and improving the signal-to-noise ratio of the acquired signal. Simultaneously, the design of the impact hammer allows for the superposition of the incident stress wave wavefront within the anchor bolt without increasing the vibration source energy, thus increasing the propagation energy of the incident stress wave and resulting in richer information about the acquired reflected wave. This invention is particularly suitable for acquiring deep reflected wave signals from long anchor bolts, thereby improving anchor bolt detection efficiency and accuracy. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the working state of the present invention; Figure 2 This is a top enlarged view of the end of the anchor rod in this invention; Figure 3 This is a schematic diagram of the hammer structure in this invention.

[0008] Among them, 1-surrounding rock, 2-anchor bolt grouting section, 3-anchor bolt exposed section, 4-three-component acceleration sensor, 5-anchor bolt end, 6-hammer, 6.1-hammer housing, 7-anchor bolt non-destructive testing instrument host, 8-signal line, 9-sensor cross section, 10-impact position, 11-steel needle end protective rubber, 12-steel needle, 13-rubber connecting spring device, 14-first spring, 15-first steel ball, 16-second steel needle, 17-second spring, 18-second steel ball, 19-third steel needle, 20-third spring, 21-third steel ball, 22-fourth steel needle, 23-fourth spring, 24-end, 25-schematic surface of stress wave front superposition. Detailed Implementation

[0009] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: like Figures 1-3 The diagram illustrates an auxiliary device for non-destructive testing of anchor bolts based on a three-component probe. It includes a three-component accelerometer 4 and a hammer 6. The hammer 6 comprises a hammer housing 6.1, a first steel needle 12, a second steel needle 16, a third steel needle 19, a fourth steel needle 22, a first steel ball 15, a second steel ball 18, a third steel ball 21, a first spring 14, a second spring 17, a third spring 20, a fourth spring 23, a rubber connecting spring device 13, and an end 24. The bottom of the first steel needle 12 is fixedly connected to the top of the second steel needle 16, the bottom of the second steel needle 16 is fixedly connected to the top of the third steel needle 19, the bottom of the third steel needle 19 is fixedly connected to the top of the fourth steel needle 22, and the bottom of the fourth steel needle 22 is fixedly connected to the end 24. The first steel ball 15 is restricted to slide between the rubber connecting spring device 13 and the bottom of the first steel needle 12, and the second steel ball 18 is restricted to slide between the bottom of the second steel needle 16 and the first steel ball 15. The third steel ball 21... The hammer 6 is restricted to sliding between the bottom of the third steel needle 19 and the second steel ball 18. The top of the first spring 14 is connected to the rubber connecting spring device 13, the bottom of the first spring 14 is connected to the top of the first steel ball 15, the top of the second spring 17 is connected to the bottom of the first steel ball 15, the bottom of the second spring 17 is connected to the top of the second steel ball 18, the top of the third spring 20 is connected to the bottom of the second steel ball 18, the bottom of the third spring 20 is connected to the top of the third steel ball 21, the bottom of the third steel ball 21 is connected to the top of the fourth spring 23, the bottom of the fourth spring 23 is connected to the end 24, the rubber connecting spring device 13 is placed on the top of the hammer housing 6.1, the top of the first steel needle 12 passes through the top of the hammer housing 6.1 and the rubber connecting spring device 13, and the end 24 is fixed to the bottom of the hammer housing 6.1. This design allows the hammer 6 to generate three strikes without increasing the striking energy, so that the incident stress wave wavefront is superimposed, thereby increasing the incident stress wave energy. The Z-axis (direction perpendicular to the plane at the end of the anchor rod) component of the three-component accelerometer 4 is parallel to the axis of the anchor rod. This design can directly collect the reflected wave along the anchor rod direction, thus eliminating the need for vector analysis. Since the Z component is in the same direction as the reflected wave of the anchor rod, and the X and Y components are perpendicular to the reflected wave direction of the anchor rod, only the Z component stores the reflected wave of the anchor rod, thereby improving the signal-to-noise ratio.

[0010] In the above technical solution, the first steel needle 12, the second steel needle 16, the third steel needle 19, and the fourth steel needle 22 are coaxially arranged. The diameter of the fourth steel needle 22 is larger than the diameter of the third steel needle 19, the diameter of the third steel needle 19 is larger than the diameter of the second steel needle 16, the diameter of the second steel needle 16 is larger than the diameter of the first steel needle 12, the third steel ball 21 can slide on the third steel needle 19, the second steel needle 16, and the first steel needle 12, and can strike the fourth steel needle 22, the second steel ball 18 can slide on the second steel needle 16 and the first steel needle 12, and can strike the third steel needle 19, and the first steel ball 15 can slide on the first steel needle 12, and can strike the second steel needle 16. Since the first steel ball 15 is the furthest from the anchor rod when it strikes, the second steel ball 18 is the furthest, and the third steel ball 21 is the furthest, to generate stress wave front superposition when the stress wave propagation speed is the same, the only way to generate stress wave front superposition is to ensure that the first steel ball 15, the second steel ball 18, and the third steel ball 21 strike in that order. That is, the first steel ball 15, which is farther away, strikes first, followed by the second steel ball 18 and the third steel ball 21.

[0011] In the above technical solution, the top of the first steel needle 12 is provided with a steel needle tip protective rubber 11 to prevent the testing personnel from accidentally touching it and being punctured.

[0012] A method for non-destructive testing of anchor bolts using the aforementioned auxiliary device, such as... Figure 1 As shown, it includes the following steps: Step 1: Install the three-component accelerometer 4 on the end 5 of the anchor rod. The anchor rod is located in the surrounding rock 1. The section between the anchor rod and the surrounding rock 1 is the grouting section of the anchor rod. The part of the anchor rod that extends out of the surrounding rock 1 is the exposed section 3 of the anchor rod. The Z component of the three-component accelerometer 4 is parallel to the axis of the anchor rod. The three-component accelerometer 4 is connected to the host of the anchor rod non-destructive testing instrument 7 through the connecting signal line 8. Step 2: Place the hammer 6 on the end 5 of the anchor rod, hold the hammer 6 and pull the rubber connecting spring device 13 to move the first steel ball 15 to the top of the hammer housing 6.1. Release the rubber connecting spring device 13 to make the hammer 6 strike the end 5 of the anchor rod once (pulling the spring causes all three steel balls to be under the tension of the spring and have potential energy. When the rubber connecting spring device is released, all three steel balls will have kinetic energy, thus striking the steel needle in sequence to form three strikes). This strike forms three consecutive strikes, in the following order: the first steel ball 15 strikes the second steel needle 16, causing the end 24 to strike the end 5 of the anchor rod; the second steel ball 18 strikes the third steel needle 19, causing the end 24 to strike the end of the anchor rod. Part 5, the third steel ball 21 strikes the steel needle 22, causing the hammer end 24 to strike the anchor rod end 5. (Since the first steel ball is furthest from the anchor rod, it needs to strike first, followed by the second and third steel balls. When the rubber connecting spring device 13 is pulled to move the first steel ball 15 to the top of the hammer housing 6.1, the third steel ball experiences the least spring tension, followed by the second spring, and the first spring experiences the greatest tension. Therefore, under the same distance, the first steel ball strikes first, followed by the second and third steel balls.) The inspector holds the hammer 6 and strikes 5 continuously in this manner. The anchor rod test waveform should meet the requirements of the "Specification for Non-destructive Testing of Anchor Rods in Hydropower and Water Conservancy Projects" (DL / T). 5424-2009) Section 7.4 requires that the stress wave generated by the hammer 6 includes the direct wave generated by the hammer and transmitted directly to the three-component accelerometer 4, and the reflected wave generated by the anchor grouting defect (incomplete grouting) and the bottom interface of the hole. The Z-component receiving module of the three-component accelerometer 4 receives the above-mentioned reflected wave and stores its Z-component data. Step 3: The main unit 7 of the anchor bolt non-destructive testing instrument uses any one of the three or more waveforms mentioned above, and calculates the defects and bottom section of the anchor bolt grouting based on the travel time of the reflected wave in the Z component of the waveform (the travel time represents the time it takes for the reflected wave to travel from the impact point to the defect location and back to the impact point). It also calculates the anchor bolt length and grouting density.

[0013] In the above technical solution, the specific method for calculating the defects and bottom section of the anchor bolt grouting based on the travel time of the reflected wave in the Z component is as follows: In the formula: x represents the distance from the sensor to the defect interface. When the defect is at the bottom of the hole, the value of x is equal to the length of the anchor rod. Δtx is the travel time of the defect-reflected wave, and cm represents the wave velocity on the anchor rod. This invention can calculate the location of the defect based on the travel time and velocity of multiple reflected waves, and can calculate the length of the anchor rod using the travel time and velocity of the bottom-reflected wave.

[0014] In step 3 of the above technical solution, the grouting density of the anchor bolt is calculated based on the ratio of the total length of the defective section of the anchor bolt to the effective bonding length of the anchor bolt, and the length of the anchor bolt is calculated based on the travel time of the reflected wave at the bottom of the hole, thereby realizing non-destructive testing of the anchor bolt.

[0015] In the above technical solution, the specific method for calculating the grouting density of the anchor bolt based on the ratio of the total length of the defective section of the anchor bolt to the effective bonding length of the anchor bolt is as follows: In the formula: D represents the grouting density of the anchor bolt; Lr is the designed anchorage length of the anchor bolt; Lx is the total length of the defective section of the anchor bolt.

[0016] In the above technical solution, the specific method for calculating the anchor bolt length based on the travel time of the reflected wave at the bottom of the hole is as follows: In the formula: x1 represents the distance from the sensor to the bottom of the hole. At this time, the value of x1 is equal to the length of the anchor rod, and Δtx1 is the travel time of the reflected wave from the bottom of the hole.

[0017] In step 2 of the above technical solution, since the deformation inside the anchor rod is linear elastic, when the anchor rod is subjected to multiple stress waves in the same area at the same time, the stress and velocity within that area are equal to the superposition (vector sum) of each stress source in that area. Therefore, this impact forms three consecutive impacts with the stress waves propagating in the same direction. At the instant the wavefronts of the three waves (the wavefront refers to the propagation surface of the wave, which can also be regarded as the tangent of the wave surface; the shape of the wavefront can be used to describe the propagation speed and shape of the wave) meet, the stress on the meeting plane immediately becomes three times the original. As the wavefronts of the three waves continue to travel, the stress value in the overlapping area stabilizes, thereby achieving the effect of stress wave wavefront superposition. Figure 3 Schematic diagram of stress wave front superposition 25.

[0018] The stress σ and velocity v of the vector composite state are expressed as: Where σ1, σ2, and σ3 represent the stresses generated by the three impacts propagating in the same direction, v1, v2, and v3 represent the particle velocities of the stress waves generated by the three impacts propagating in the same direction, ρ is the density of the rod, and c is the propagation velocity of the stress waves generated by the three impacts propagating in the same direction within the rod. This formula shows that without increasing the energy of the vibration source, the wavefront superposition of the incident stress waves within the anchor rod increases the propagation energy of the incident stress waves, resulting in richer information about the reflected waves. This is particularly suitable for acquiring deep reflected wave signals from long anchor rods, thereby improving the efficiency and accuracy of anchor rod detection. In step 2 of the above technical solution, the line connecting the center of the hammer 6's striking position 10 and the center of the sensor head of the three-component accelerometer 4 is aligned with the X-component direction of the three-component accelerometer 4. The Y-component direction of the three-component accelerometer 4 is in the same plane as the X-component direction and has a 90° angle with it. The plane containing the X and Y components is perpendicular to the anchor rod axis. Figure 2 As shown, the X component direction, Y component direction and Z component direction are marked in the sensor cross section 9.

[0019] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. An auxiliary device for non-destructive testing of anchor bolts based on a three-component probe, characterized in that, It includes a three-component accelerometer (4) and a hammer (6), the hammer (6) including a hammer housing (6.1), a first steel needle (12), a second steel needle (16), a third steel needle (19), a fourth steel needle (22), a first steel ball (15), a second steel ball (18), a third steel ball (21), a first spring (14), a second spring (17), a third spring (20), a fourth spring (23), a rubber connecting spring device (13), and an end (24), wherein the bottom of the first steel needle (12) is fixedly connected to the top of the second steel needle (16), the bottom of the second steel needle (16) is fixedly connected to the top of the third steel needle (19), and the bottom of the third steel needle (19) is fixedly connected to the top of the fourth steel needle (6.1). The top of the needle (22) is fixedly connected, the bottom of the fourth steel needle (22) is fixedly connected to the end (24), the first steel ball (15) is restricted to slide between the rubber connecting spring device (13) and the bottom of the first steel needle (12), the second steel ball (18) is restricted to slide between the bottom of the second steel needle (16) and the first steel ball (15); the third steel ball (21) is restricted to slide between the bottom of the third steel needle (19) and the second steel ball (18), the top of the first spring (14) is connected to the rubber connecting spring device (13), the bottom of the first spring (14) is connected to the top of the first steel ball (15), the top of the second spring (17) is connected to the bottom of the first steel ball (15), and the second spring (17)... The bottom end of the first steel needle (12) is connected to the top end of the second steel ball (18), the top end of the third spring (20) is connected to the bottom end of the second steel ball (18), the bottom end of the third spring (20) is connected to the top end of the third steel ball (21), the bottom end of the third steel ball (21) is connected to the top end of the fourth spring (23), the bottom end of the fourth spring (23) is connected to the end (24), the rubber connecting spring device (13) is placed on the top of the hammer housing (6.1), the top end of the first steel needle (12) passes through the top of the hammer housing (6.1) and the rubber connecting spring device (13), and the end (24) is fixed to the bottom of the hammer housing (6.1); the first steel needle (12), the second steel needle (16), the third steel needle (19), the fourth steel needle (12) and the rubber connecting spring device (13) pass ... passes through the top end of the hammer housing (6.1); the first steel needle (12), the second steel needle (16), the third steel needle (19), the fourth steel needle (12) and the rubber connecting spring device (13) pass through the top of the hammer The needles (22) are coaxially arranged. The diameter of the fourth steel needle (22) is larger than that of the third steel needle (19). The diameter of the third steel needle (19) is larger than that of the second steel needle (16). The diameter of the second steel needle (16) is larger than that of the first steel needle (12). The third steel ball (21) can slide on the third steel needle (19), the second steel needle (16) and the first steel needle (12) and can strike the fourth steel needle (22). The second steel ball (18) can slide on the second steel needle (16) and the first steel needle (12) and can strike the third steel needle (19). The first steel ball (15) can slide on the first steel needle (12) and can strike the second steel needle (16). The Z-axis component of the three-component accelerometer (4) is parallel to the axis of the anchor rod.

2. The anchor bolt non-destructive testing auxiliary device based on a three-component probe according to claim 1, characterized in that: The top of the first steel needle (12) is provided with a steel needle end protective rubber (11).

3. A method for non-destructive testing of anchor bolts using the auxiliary device described in claim 1, characterized in that, It includes the following steps: Step 1: Install the three-component accelerometer (4) on the end (5) of the anchor rod, wherein the Z component of the three-component accelerometer (4) is parallel to the anchor rod axis; Step 2: Place the hammer (6) on the end (5) of the anchor rod, hold the hammer (6) and pull the rubber connecting spring device (13) to move the first steel ball (15) to the top of the hammer housing (6.1). Release the rubber connecting spring device (13) to make the hammer (6) strike the end (5) of the anchor rod once. This strike forms three consecutive strikes, namely, the first steel ball (15) strikes the second steel needle (16), causing the end (24) to strike the end (5) of the anchor rod, and the second steel ball (15) strikes the end (5) of the anchor rod. The bead (18) strikes the third steel needle (19), causing the end (24) to strike the end (5) of the anchor rod; the third steel bead (21) strikes the fourth steel needle (22), causing the end (24) of the small hammer to strike the end (5) of the anchor rod; the stress wave generated by the hammer (6) includes the direct wave generated by the strike that is directly transmitted to the three-component accelerometer (4) and the reflected wave generated by the anchor rod grouting defects and the bottom interface of the hole. The Z-component receiving module of the three-component accelerometer (4) receives the above-mentioned reflected wave; Step 3: Based on the travel time of the reflected wave in the Z component, calculate the defects and bottom section of the anchor bolt grouting, and calculate the anchor bolt length and grouting density.

4. The non-destructive testing method for anchor bolts according to claim 3, characterized in that: The specific method for calculating the defects and bottom section of the anchor bolt grouting based on the travel time of the reflected wave in the Z component is as follows: In the formula: x represents the distance from the sensor to the defect interface. When the defect is at the bottom of the hole, the value of x is equal to the length of the anchor rod. Δtx is the travel time of the defect reflected wave, and cm represents the wave velocity on the anchor rod.

5. The non-destructive testing method for anchor bolts according to claim 3, characterized in that: In step 3, the grouting density of the anchor bolt is calculated based on the ratio of the total length of the defective section of the anchor bolt to the effective bonding length of the anchor bolt, and the length of the anchor bolt is calculated based on the travel time of the reflected wave at the bottom of the hole.

6. The non-destructive testing method for anchor bolts according to claim 5, characterized in that: The specific method for calculating the grouting density of anchor bolts based on the ratio of the total length of the defective section to the effective bond length of the anchor bolt is as follows: In the formula: D represents the grouting density of the anchor bolt; Lr is the designed anchorage length of the anchor bolt; Lx is the total length of the defective section of the anchor bolt.

7. The non-destructive testing method for anchor bolts according to claim 5, characterized in that: The specific method for calculating the anchor bolt length based on the travel time of the reflected wave at the bottom of the borehole is as follows: In the formula: x1 represents the distance from the sensor to the bottom of the hole. At this time, the value of x1 is equal to the length of the anchor rod, and Δtx1 is the travel time of the reflected wave from the bottom of the hole.

8. The non-destructive testing method for anchor bolts according to claim 3, characterized in that: In step 2, since the deformation inside the anchor rod is linear elastic, when the anchor rod is subjected to multiple stress waves in the same area at the same time, the stress and velocity in that area are equal to the superposition of each stress source in that area. Therefore, this strike forms three consecutive strikes that generate stress waves with the same propagation direction. When the wavefronts of the three waves meet, the stress on the meeting plane immediately becomes three times the original. As the wavefronts of the three waves continue to travel, the stress value in the overlapping area stabilizes, thereby achieving the effect of stress wave wavefront superposition.

9. The non-destructive testing method for anchor bolts according to claim 3, characterized in that: In step 2, the line connecting the center of the striking position (10) of the hammer (6) and the center of the sensing head of the three-component accelerometer (4) is aligned with the X-component direction of the three-component accelerometer (4).

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