Anchor ball pad, anchor bolt locking force monitoring system and anchor bolt locking force monitoring method

Abstract

This invention relates to anchor bolt ball pads, an anchor bolt locking force monitoring system, and an anchor bolt locking force monitoring method. The anchor bolt ball pad includes a ball pad skeleton body with an axially oriented through hole in the center. Multiple ultrasonic element mounting holes are provided on the outer circumferential surface of the ball pad skeleton body, and ultrasonic probes are installed in each of these holes. Each ultrasonic probe includes a piezoelectric element, and a sealant is applied to the piezoelectric element to fix it within the ultrasonic element mounting hole. A wire is provided on the ball pad skeleton body, with one end of the wire fixedly connected to the piezoelectric element. A rigid washer ring is provided at the top of the ball pad skeleton body. The anchor bolt locking force monitoring system includes an anchor bolt locking force monitoring device, a data acquisition card, and a computer. The computer contains an anchor bolt locking force monitoring and analysis program. The anchor bolt ball pad, anchor bolt locking force monitoring system, and anchor bolt locking force monitoring method of this invention are used for anchor bolt locking force monitoring.

Description

Technical Field

[0001] This invention belongs to the field of anchor bolt locking force monitoring technology, specifically an anchor bolt ball pad, an anchor bolt locking force monitoring system including the anchor bolt ball pad, and an anchor bolt locking force monitoring method. Background Technology

[0002] As a critical support structure in geotechnical engineering, monitoring the anchoring performance of anchor bolts is essential for ensuring structural safety. Anchor bolt locking force is a crucial indicator of an anchor bolt's load-bearing capacity and its ability to maintain stable anchoring, directly impacting the safety and durability of the project. Continuous monitoring of anchor bolt locking force allows engineers and technicians to promptly assess the anchor bolt's condition and prevent safety hazards caused by anchor bolt failure. This practice not only helps extend the project's service life but also significantly reduces maintenance and repair costs. Therefore, monitoring locking force is an indispensable and crucial aspect during the construction and maintenance phases of geotechnical engineering projects, providing strong data support and scientific basis for ensuring the project's safety and stability.

[0003] An anchor bolt system generally consists of an anchor bolt (1), an anchor nut (2), an anchor plate (4), and a ball washer (3), such as... Figure 1 As shown. Common testing methods for anchor bolt locking force can be divided into active sensing and passive sensing technologies. Passive sensing does not emit signals but receives signals from sensors embedded in the target being tested. The strain method is the most commonly used passive monitoring method, which also includes fiber optic testing and piezoresistive impedance methods. Passive sensing methods rely on changes in the inherent characteristics of the sensing element to characterize the anchor bolt's properties. Observed values ​​are relative; if the initial force value or test zero point of the anchor bolt is unknown, accurately determining the true stress state of the anchor bolt becomes challenging.

[0004] Active sensing technology has been widely used in anchor bolt monitoring, one method being ultrasonic testing. Utilizing the linear relationship between anchor bolt load and the measured ultrasonic length, the anchor bolt load can be assessed by measuring the round-trip propagation time of the ultrasonic waves emitted from the anchor bolt head and reflected from the bottom surface. To directly obtain the absolute value of the bolt tightening force, a multi-wave method based on the velocity ratio of longitudinal and transverse waves is commonly used. Although active methods are typically employed to determine the absolute value of the bolt tightening force, the testing process is still affected by many interfering factors, and accurate quantification under zero load remains challenging.

[0005] The locking force of an anchor bolt can be converted into contact pressure between specific rough surfaces. The interaction between two rough surfaces is a key aspect of interfacial contact, as the magnitude and distribution of contact pressure directly affect contact performance. In theoretical studies of interfacial contact, as the actual contact area increases, the reflected wave gradually decreases, while the transmitted wave increases accordingly. This has been applied as an emerging testing method for the detection and monitoring of prestressed anchor cables. However, in interface studies, the interfaces studied are relatively simple, and pure reflected waves are often used as monitoring indicators. In actual anchor bolt systems, due to the presence of multiple interfaces in the structure, the propagation mechanism of ultrasonic signals is unclear, and energy dissipation at the signal propagation interface is complex. Therefore, selecting appropriate test interfaces and ultrasonic energy flow paths during testing is necessary to effectively ensure the validity and accuracy of the test.

[0006] Defects and shortcomings of existing technology:

[0007] (1) The anchor bolt locking force test in the anchor bolt anchoring system requires additional sensors to be installed, and each component cannot sense its own force.

[0008] (2) When using the ultrasonic method to measure the anchor bolt locking force, there is no effective design and selection of ultrasonic energy flow path;

[0009] (3) Traditional methods require pre-calibration of the zero point when monitoring the anchor bolt locking force, and can only measure the relative value of the locking force, but cannot effectively obtain the absolute value;

[0010] (4) When using the ultrasonic method to measure the anchor bolt locking force, there is no effective zero-point calibration method. Summary of the Invention

[0011] To achieve the above objectives, the present invention provides the following technical solution: an anchor ball pad, comprising a ball pad skeleton body, wherein a through hole is axially provided in the middle of the ball pad skeleton body, and a plurality of ultrasonic element mounting holes are provided on the outer circumferential surface of the ball pad skeleton body, wherein an ultrasonic probe is installed in each of the plurality of ultrasonic element mounting holes, the ultrasonic probe comprising a piezoelectric element, wherein a sealant is provided on the piezoelectric element, and the piezoelectric element is fixed in the ultrasonic element mounting hole by the sealant, wherein a wire is provided on the ball pad skeleton body, one end of the wire is fixedly connected to the piezoelectric element, and a rigid gasket ring is provided on the top of the ball pad skeleton body.

[0012] Preferably, the ball pad frame body is shaped like a frustum of a cone, and the lower end of the ball pad frame body is the smaller end, that is, the diameter of the lower end of the ball pad frame body is smaller than the diameter of the upper end of the ball pad frame body.

[0013] Preferably, the plurality of ultrasonic element mounting holes are arranged in a ring on the outer peripheral surface of the ball pad frame body, and the number of ultrasonic element mounting holes is generally four, corresponding to four ultrasonic probes.

[0014] Preferably, a wire routing groove is provided on the outer peripheral surface of the ball pad frame body. The wire routing groove is annularly surrounding the outer peripheral surface of the ball pad frame body. A portion of the wire is located within the wire routing groove. A routing groove sealing ring is provided within the wire routing groove to seal the wire within the wire routing groove.

[0015] Preferably, the top surface of the ball pad skeleton body is a rough surface.

[0016] Preferably, the top surface of the ball pad frame body is provided with a plurality of micro-protrusions, the micro-protrusions being cylinders or spheres, and the plurality of micro-protrusions being evenly distributed on the top surface of the ball pad frame body.

[0017] Preferably, the bottom surface of the rigid pad ring is a rough surface, and when the anchor rod is under load, the bottom surface of the rigid pad ring contacts the top surface of the ball pad frame body.

[0018] Preferably, the surfaces of the plurality of micro-protrusions are subjected to quenching and hardening treatment, and the hardened pad ring is made of cemented carbide.

[0019] The present invention also provides an anchor bolt locking force monitoring system including the above-mentioned anchor bolt ball pad, comprising an anchor bolt locking force monitoring device, a data acquisition card, and a computer. The anchor bolt locking force monitoring device includes an anchor bolt, an anchor bolt ball pad, and an anchor plate. The anchor bolt passes through a rigid washer ring, a through hole in the anchor bolt ball pad, and the anchor plate. The upper end of the anchor bolt is provided with an external thread, and a nut is provided at the upper end of the anchor bolt. The nut is located above the rigid washer ring, and a nylon washer is provided between the nut and the rigid washer ring. A spherical pad is provided at the lower end of the ball pad skeleton body, and the bottom of the spherical pad is placed on the anchor plate. The other end of the wire is connected to the data acquisition card, and the data acquisition card is connected to the computer via a data cable. The computer is equipped with an anchor bolt locking force monitoring and analysis program.

[0020] The present invention also provides a method for monitoring anchor bolt locking force using the above-described anchor bolt locking force monitoring system, which includes the following steps:

[0021] (1) Select the ball pad as the test position, apply load to the ball pad and anchor rod by tightening the nut, so that the ball pad skeleton body contacts the hard pad ring and the spherical pad plate;

[0022] (2) The piezoelectric sheet generates piezoelectric ultrasonic energy and ultrasonic transmission wave signal. Other ultrasonic probes receive the ultrasonic signal and transmit the ultrasonic transmission wave signal to the data acquisition card through the wire. The data acquisition card excites the received ultrasonic transmission wave signal and transmits it to the computer through the data line. The anchor bolt locking force monitoring and analysis program in the computer analyzes and processes the ultrasonic transmission wave signal to determine whether the anchor bolt locking force is within the safe range.

[0023] (3) The excitation signal is a 0~1MHz linear sweep frequency signal. The total signal energy is selected as the evaluation index. During the monitoring process, a limited number of sampling points are used, with 1,000,000 points collected each time. The formula for calculating the total signal energy is shown in Equation (1):

[0024] (1)

[0025] In the formula: E is the total energy of the signal; x[n] is the signal sequence;

[0026] (4) The anchor bolt locking force monitoring system is calibrated by a graded loading process. Different loads are applied to the anchor bolt, the energy of the ultrasonic signal in the anchor bolt ball pad is tested, and curve fitting is performed. A typical curve function is shown in equation (2):

[0027] (2)

[0028] In the formula: Et is the measured signal energy; Ezero is the energy value measured by the smart ball pad when the anchor is not under load; a and b are fitting parameters; x is the anchor locking force;

[0029] The zero-point of the test is calibrated by calculating the average value of the energy of the anchor rod when it is not under load, and the calculation formula is shown in equation (3):

[0030] (3)

[0031] In the formula: n is the number of tests; E i This represents the energy value obtained in each test.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] (1) The anchor ball pad is a component of the original anchoring system and is also used to evaluate the anchor bolt locking force, so no additional sensors are required;

[0034] (2) The zero point measured by the anchor ball pad is an absolute zero point, and the locking force measured by the anchor ball pad is an absolute value, not a relative value. It is suitable for evaluating the anchor locking force for unknown initial states.

[0035] (3) The design and selection method of ultrasonic energy flow path has reference value for similar monitoring.

[0036] (4) Establish the functional relationship between the fitting force energy and the anchor bolt locking force, and accurately monitor the anchor bolt locking force. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of an existing anchor bolt system;

[0038] Figure 2 This is a schematic diagram of the structure of the anchor ball pad of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of the ball pad skeleton body in the anchor ball pad of the present invention;

[0040] Figure 4 This is a schematic diagram of the piezoelectric element in the anchor ball pad of the present invention;

[0041] Figure 5 This is a schematic diagram of the wiring groove sealing ring in the anchor ball pad of the present invention;

[0042] Figure 6 This is a schematic diagram of the anchor bolt locking force monitoring system of the present invention;

[0043] Figure 7 This is a schematic diagram showing the arrangement of four ultrasonic probes T1, T2, T3, and T4 in an embodiment of the present invention;

[0044] Figure 8 This is a schematic diagram of the flow of ultrasonic signals when the anchor bolt is not under load and all components in the anchor bolt locking force monitoring device are completely separated in this invention;

[0045] Figure 9 This is a schematic diagram of the flow of ultrasonic signals when the components of the anchor bolt under external load and anchor bolt locking force monitoring device interact and come into contact in this invention;

[0046] Figure 10 These are time-domain signal diagrams measured by the piezoelectric element used for receiving signals under different loads in embodiments of the present invention.

[0047] Figure 11 This is a typical test signal fitting curve diagram in an embodiment of the present invention;

[0048] Figure 12 This is a comparison chart of the test load value and the actual load value during blind testing in an embodiment of the present invention. Detailed Implementation

[0049] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0050] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0051] This invention proposes an anchor ball pad, please refer to [reference needed]. Figures 2 to 5The device includes a ball pad frame body 5, with a through hole 6 axially arranged in the middle of the ball pad frame body 5. Multiple ultrasonic element mounting holes 7 are arranged on the outer circumferential surface of the ball pad frame body 5. An ultrasonic probe 8 is installed in each of the multiple ultrasonic element mounting holes 7. Each ultrasonic probe 8 includes a piezoelectric element 9, and a sealant 10 is provided on the piezoelectric element 9. The sealant 10 fixes the piezoelectric element 9 in the ultrasonic element mounting hole 7. A wire 11 is provided on the ball pad frame body 5, with one end of the wire 11 fixedly connected to the piezoelectric element 9. A rigid gasket ring 12 is provided on the top of the ball pad frame body 5.

[0052] Preferably, a wire wiring groove 13 is provided on the outer peripheral surface of the ball pad frame body 5. The wire wiring groove 13 is arranged in a ring around the outer peripheral surface of the ball pad frame body 5. A portion of the wire 11 is located in the wire wiring groove 13. A wiring groove sealing ring 14 is provided in the wire wiring groove 13 to seal the wire 11 in the wire wiring groove 13.

[0053] The top surface 15 of the ball pad frame body 5 is a rough surface. Multiple micro-protrusions 16 are provided on the top surface of the ball pad frame body 5. The micro-protrusions 16 are cylinders or spheres. The multiple micro-protrusions 16 are evenly distributed in a ring array on the top surface 15 of the ball pad frame body 5.

[0054] The bottom surface of the rigid pad ring 12 is rough, and when the anchor rod is under load, the bottom surface of the rigid pad ring 12 contacts the top surface of the ball pad frame body 5.

[0055] Preferably, the surfaces of the plurality of micro-protrusions 16 are subjected to quenching and hardening treatment to prevent plastic deformation during loading, thereby improving the uniformity of the rough interface and enhancing the consistency and robustness of test results. The hard pad ring 12 is made of cemented carbide to prevent plastic deformation during loading.

[0056] The present invention also provides an anchor bolt locking force monitoring system comprising the above-mentioned anchor bolt ball pad, such as Figure 6As shown, the device includes an anchor bolt locking force monitoring device 17, a data acquisition card 18, and a computer 19. The anchor bolt locking force monitoring device 17 includes an anchor bolt 20, an anchor bolt ball pad 21, and an anchor pad plate 22. The anchor bolt 20 passes through a rigid washer ring 12, a through hole 6 in the anchor bolt ball pad 21, and the anchor pad plate 22. The upper end of the anchor bolt 20 is provided with an external thread, and a nut 23 is provided at the upper end of the anchor bolt 20. The nut 23 is located above the rigid washer ring 12, and a nylon washer 24 is provided between the nut 23 and the rigid washer ring 12. A spherical pad 25 is provided at the lower end of the ball pad skeleton body 5 of the anchor bolt ball pad 21, and the bottom of the spherical pad 25 is provided on the anchor pad plate 22. The other end of the wire 11 is connected to the data acquisition card 18, and the data acquisition card 18 is connected to the computer 19 through a data cable 26. The computer 19 is equipped with an anchor bolt locking force monitoring and analysis program.

[0057] This invention analyzes the ultrasonic energy flow path within the anchor bolt anchoring system to determine the placement of the ultrasonic probe and fabricates an intelligent ball pad for monitoring anchor bolt locking force. The monitoring system, by installing the intelligent anchor bolt ball pad within the anchor bolt anchoring system (i.e., the anchor bolt locking force monitoring device), transmits and receives ultrasonic signals, excites and receives test signals, and programs corresponding to signal analysis and processing on a computer to achieve intelligent monitoring of the anchor bolt locking force.

[0058] The monitoring of anchor bolt locking force in this invention includes the following steps:

[0059] (1) Selection of ultrasonic energy flow path within the anchor bolt anchoring system to determine the location of the ultrasonic probe:

[0060] The anchor bolt locking force monitoring of this invention is based on the dissipation of ultrasonic energy. To improve the monotonicity between the test indicators and the anchor bolt locking force during the monitoring and testing process, it is necessary to ensure that the measured ultrasonic energy dissipation remains monotonically decreasing or monotonically increasing. Therefore, a suitable monitoring location must be selected within the anchor bolt anchoring system. For example... Figure 8 and Figure 9 As shown, anchor ball pad 21 is selected as the main test location. When the anchor 20 is not under load, the components of the anchor anchoring system, i.e., the anchor locking force monitoring device 17, are in a completely separated state. When the ultrasonic signal is excited and received in the anchor ball pad 21, there are mainly two types of ultrasonic energy flow: one is a direct wave 27, and the other is a reflected wave 28, as shown in the figure. Figure 8 As shown. When the anchor bolt 20 is subjected to an external load, the components of the anchor bolt anchoring system interact and come into contact. As the pressure increases, the contact area between the top surface of the ball pad skeleton body 5 and the rough contact interface of the hard pad ring 12 gradually increases. Therefore, the piezoelectric ultrasonic energy will flow from the anchor bolt ball pad 21 to the nut 23 and the anchor plate 22, i.e., the transmitted wave 29 gradually increases. Figure 9As shown. Since the ultrasonic energy dissipation in the anchor ball pad 21 is unidirectional and outward, it has little impact on the ultrasonic signal inside the anchor ball pad 21. Therefore, ultrasonic probes for emitting and receiving ultrasonic signals can be arranged around the anchor ball pad 21, which can be used for monitoring the anchor bolt locking force;

[0061] (2) Excitation and reception of ultrasonic signals:

[0062] Four piezoelectric ultrasonic probes are to be arranged in one anchor ball pad 21, and the arrangement number is as follows: Figure 7 As shown, the tests are divided into T1, T2, T3, and T4. During the test, one ultrasound probe can transmit a signal while another receives it, such as T1 transmitting and T3 receiving. Alternatively, to increase accuracy, multiple sets of test results can be used for evaluation. For example, ultrasound probe T1 can transmit a signal while other ultrasound probes receive it.

[0063] (3) Processing of test signals:

[0064] After the anchor ball pad 21 is installed in the anchor bolt tightening force monitoring device 17, the anchor bolt tightening force monitoring system extracts the test results of the anchor ball pad 21. The excitation signal can be a linear frequency sweep signal (0~1MHz). When using a frequency sweep signal for excitation, a typical received signal is as follows: Figure 10 As shown, the test data is the data without signal processing, used to quantify the test zero point value and fit the test relationship between the signal and the load. The signal cannot be directly used to evaluate the anchor bolt locking force, so the total signal energy is selected as the evaluation index. During the test, the NI USB-USB-6366 data acquisition card was used, and finite point sampling was adopted, with 1,000,000 points collected each time. The formula for calculating the total signal energy is shown in Equation (1).

[0065] (1)

[0066] In the formula: E is the total energy of the signal; x[n] is the signal sequence;

[0067] (4) Test result calibration and test zero point calibration:

[0068] When the anchor bolt anchoring system is unloaded, the ultrasonic energy transmitted within the anchor bolt ball pad does not flow outwards, thus reaching its maximum value, i.e., the absolute zero value. When the anchor bolt is under load, the contact area between the rough surfaces increases, leading to energy dissipation within the anchor bolt ball pad, resulting in a gradual decrease. Therefore, the ultrasonic energy value is used as the evaluation index for the anchor bolt locking force to obtain the absolute value of the anchor bolt locking force. To establish the relationship between the anchor bolt locking force and the test index (total signal energy), the anchor bolt ball pad testing process needs to be calibrated. The calibration process employs a graded loading calibration procedure for the anchor bolt system. By applying different loads to the anchor bolt, the energy of the ultrasonic signal in the anchor bolt ball pad is tested, and curve fitting is performed. Typical signals measured under different loads are shown below. Figure 10 As shown. The fitting curve needs to consider the influence of the test zero point. A typical test signal fitting curve is shown below. Figure 11 As shown, a typical curve function is shown in equation (2):

[0069] (2)

[0070] In the formula: Et is the measured signal energy; Ezero is the energy value measured by the anchor ball pad when the anchor is not under load; a and b are fitting parameters; x is the anchor locking force.

[0071] Since the zero point obtained by the method of this invention is an absolute value, the zero point can be calibrated by calculating the average value of the energy of the anchor rod when it is not under load, as shown in equation (3):

[0072] (3)

[0073] In the formula: n is the number of tests; E i The energy value obtained in each test;

[0074] pass Figure 10 The test signal set under different loads is used to obtain the characteristic index (such as energy) of the test signal by signal processing method. After multiple tests, the test zero point is quantified by formula (3). According to formula (2), the relationship between the characteristic index of the signal and the load is fitted to form a test function. The test signal can then be used to evaluate the actual load and be used for actual engineering testing.

[0075] (5) Intelligent monitoring of anchor bolt locking force:

[0076] By periodically excitation signals to the anchor ball pad, one ultrasonic probe emits an ultrasonic signal and collects the energy obtained by the other ultrasonic probes. Using the anchor bolt locking force monitoring and analysis program, the anchor bolt locking force is analyzed and calculated using a fitting formula to determine whether the anchor bolt locking force is within the safe range.

[0077] Equation (2) was used to evaluate the actual test load, and a blind test was conducted. By comparing the difference between the test value and the actual load value, the correctness and practicality of the test method were verified. The verification process is as follows: Figure 12 As shown.

[0078] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Anchor ball pad, comprising a ball pad skeleton body, characterized in that: The ball pad frame body has a through hole axially arranged in the middle. The outer circumferential surface of the ball pad frame body has multiple ultrasonic element mounting holes. Each ultrasonic element mounting hole has an ultrasonic probe installed in it. The ultrasonic probe includes a piezoelectric element. The piezoelectric element is covered with sealant and is fixed in the ultrasonic element mounting hole by the sealant. The ball pad frame body has a wire, one end of which is fixedly connected to the piezoelectric element. The top of the ball pad frame body has a rigid gasket ring.

2. The anchor ball pad according to claim 1, characterized in that: The main body of the ball pad frame is shaped like a frustum of a cone.

3. The anchor ball pad according to claim 2, characterized in that: The multiple ultrasonic element mounting holes are arranged in a ring on the outer circumferential surface of the ball pad frame body.

4. The anchor ball pad according to claim 3, characterized in that: A wire routing groove is provided on the outer circumferential surface of the ball pad frame body. The wire routing groove is annularly surrounding the outer circumferential surface of the ball pad frame body. A portion of the wire is located inside the wire routing groove. A routing groove sealing ring is provided inside the wire routing groove to seal the wire inside the wire routing groove.

5. The anchor ball pad according to claim 4, characterized in that: The top surface of the ball pad frame body is a rough surface.

6. The anchor ball pad according to claim 5, characterized in that: The top surface of the ball pad frame body is provided with a plurality of micro-protrusions, which are either cylinders or spheres, and the plurality of micro-protrusions are evenly distributed on the top surface of the ball pad frame body.

7. The anchor ball pad according to claim 6, characterized in that: The bottom surface of the rigid pad ring is rough, and when the anchor rod is under load, the bottom surface of the rigid pad ring contacts the top surface of the ball pad frame body.

8. The anchor ball pad according to claim 7, characterized in that: The surfaces of the plurality of micro-protrusions are subjected to quenching and hardening treatment, and the hardened pad ring is made of cemented carbide.

9. An anchor bolt locking force monitoring system comprising the anchor bolt ball pad as described in claim 8, characterized in that: The system includes an anchor bolt locking force monitoring device, a data acquisition card, and a computer. The anchor bolt locking force monitoring device includes an anchor bolt, an anchor bolt ball pad, and an anchor plate. The anchor bolt passes through a rigid washer ring, a through hole in the anchor bolt ball pad, and the anchor plate. The upper end of the anchor bolt has an external thread and a nut. The nut is located above the rigid washer ring, and a nylon washer is placed between the nut and the rigid washer ring. A spherical pad is placed at the lower end of the ball pad frame body, and the bottom of the spherical pad is placed on the anchor plate. The other end of the wire is connected to the data acquisition card, and the data acquisition card is connected to the computer via a data cable. The computer contains an anchor bolt locking force monitoring and analysis program.

10. A method for monitoring the anchor bolt locking force using the anchor bolt locking force monitoring system of claim 9, characterized in that: Includes the following steps: (1) Select the ball pad as the test position, apply load to the ball pad and anchor rod by tightening the nut, so that the ball pad skeleton body contacts the hard pad ring and the spherical pad plate; (2) The piezoelectric sheet generates piezoelectric ultrasonic energy and ultrasonic transmission wave signal. Other ultrasonic probes receive the ultrasonic signal and transmit the ultrasonic transmission wave signal to the data acquisition card through the wire. The data acquisition card excites the received ultrasonic transmission wave signal and transmits it to the computer through the data line. The anchor bolt locking force monitoring and analysis program in the computer analyzes and processes the ultrasonic transmission wave signal to determine whether the anchor bolt locking force is within the safe range. (3) The excitation signal is a 0~1MHz linear sweep frequency signal. The total signal energy is selected as the evaluation index. During the monitoring process, a limited number of sampling points are used, with 1,000,000 points collected each time. The formula for calculating the total signal energy is shown in Equation (1): （1） In the formula: E is the total energy of the signal; x[n] is the signal sequence; (4) The anchor bolt locking force monitoring system is calibrated by a graded loading process. Different loads are applied to the anchor bolt, the energy of the ultrasonic signal in the anchor bolt ball pad is tested, and curve fitting is performed. A typical curve function is shown in equation (2): （2） In the formula: Et is the measured signal energy; Ezero is the energy value measured by the smart ball pad when the anchor is not under load; a and b are fitting parameters; x is the anchor locking force; The zero-point of the test is calibrated by calculating the average value of the energy of the anchor rod when it is not under load, and the calculation formula is shown in equation (3): （3） In the formula: n is the number of tests; E i This represents the energy value obtained in each test.

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