Method and device for detecting the quality of a screw anchor

Abstract

The application provides a detection method and device for detecting the anchoring quality of a spiral anchor rod, relates to the technical field of anchoring structure analysis, and realizes real-time collection of vibration signals of the end of the anchor rod by installing and calibrating sensors, extracts the amplitude, phase and spectral peak value of the signals after pretreatment, further calculates vibration characteristic parameters, then establishes a finite element model of the spiral anchor rod based on a mechanical simulation software, obtains ideal vibration characteristic parameters through modal analysis, compares the ideal vibration characteristic parameters with actual parameters, generates a stability coefficient, then obtains anchor rod and surrounding soil parameters, analyzes the matching degree and stress distribution, determines a maximum stress influence area, finally combines the stability coefficient and the matching degree to establish an anchoring quality relationship, so as to evaluate the anchoring quality. The application establishes the relationship between the stability coefficient of the spiral anchor rod and the soil compactness by real-time monitoring through sensors and vibration characteristic analysis, so as to realize effective evaluation of the anchoring quality.

Description

Technical Field

[0001] This invention relates to the field of anchorage structure analysis technology, specifically to a testing method and apparatus for detecting the anchorage quality of helical anchor bolts. Background Technology

[0002] Helical anchors are widely used in civil engineering and underground engineering, mainly to provide additional support and stability. They are commonly used in foundation engineering, slope protection, tunnel support, and anchoring of various civil engineering structures. With the expansion of project scale and the improvement of technical requirements, ensuring the anchoring quality of helical anchors has become increasingly important, especially under extreme conditions such as earthquakes and wind loads, where their stability is directly related to the safety and durability of the structure. Commonly used methods for testing the anchoring quality of helical anchors include static load tests, dynamic tests, and acoustic tests. Although these methods can provide some information on anchoring performance, they are often limited by the following aspects: First, traditional methods usually require a long construction and testing cycle, affecting the project progress; second, many testing methods require destructive sampling or construction, which will affect the surrounding environment and the anchoring structure.

[0003] In existing technologies, traditional methods for testing helical anchor bolts often require a long time for static or dynamic tests, which not only affects the project progress but may also lead to project delays. Furthermore, traditional methods for testing helical anchor bolts can only provide an overall assessment of anchoring performance, lacking in-depth analysis of the characteristics of the anchor bolt itself and failing to determine the maximum stress influence area of ​​the anchoring system, thus neglecting the impact of the external environment on anchoring quality.

[0004] Therefore, it is necessary to propose a detection method and device for detecting the anchoring quality of helical anchor bolts to solve the aforementioned problem.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a testing method for detecting the anchoring quality of helical anchor bolts, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A testing method for detecting the anchoring quality of helical anchor bolts, comprising the following steps:

[0009] Step 1: Install strain sensors, acceleration sensors, and displacement sensors on the exposed end of the spiral anchor bolt to be tested and on the surrounding structural surface, and perform zero-point calibration and sensitivity calibration on all sensors;

[0010] Step 2: Real-time acquisition of the original vibration response signal at the end of the anchor bolt to be tested, filtering, denoising and normalizing the original vibration signal, extracting the amplitude, phase and spectral peak value in the original vibration signal and analyzing it, and calculating the vibration characteristic parameters in the anchoring system through time domain and frequency domain analysis methods, including characteristic modal frequency, damping ratio and stiffness coefficient.

[0011] Step 3: Establish a finite element model of the helical anchor rod based on mechanical simulation software, and perform modal analysis on it to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor rod. Based on the degree of deviation between the vibration characteristic parameters of the helical anchor rod to be tested and the ideal values ​​of the vibration characteristic parameters, generate the stability coefficient of the helical anchor rod to be tested.

[0012] Step 4: Obtain the parameters of the helical anchor to be tested and the soil parameters of the anchoring site, determine the compatibility between the helical anchor to be tested and the surrounding soil, and perform stress analysis on the helical anchor to be tested to determine the maximum stress influence area of ​​the anchoring system in the soil.

[0013] Step 5: Calculate the soil density in the maximum stress influence zone. Use the stability coefficient of the helical anchor to be tested, the compatibility between the helical anchor to be tested and the surrounding soil, and the soil density in the maximum stress influence zone to establish the anchoring quality relationship, so as to evaluate the anchoring quality of the helical anchor to be tested.

[0014] Furthermore, strain sensors, acceleration sensors, and displacement sensors are installed on the exposed end of the helical anchor bolt to be tested and on the surrounding structural surface, and zero-point calibration and sensitivity calibration are performed. The method used is as follows:

[0015] Before the deep-buried anchoring treatment of the spiral anchor bolt to be tested, strain sensors are installed in the middle and end of the anchor bolt respectively. Epoxy resin is used to fix the strain sensors in the predetermined position. Acceleration sensors are installed on the top of the anchor bolt and the main pipe to monitor the dynamic response affecting the anchoring. Displacement sensors are installed on the exposed end of the anchor bolt to monitor the displacement of the anchor bolt.

[0016] After the sensor is installed, ensure that there is no external force applied, read the output value of the strain sensor, record the value, and perform zero-point calibration based on the data acquisition system, setting the reading value to zero. Similarly, use the same method for the acceleration sensor and displacement sensor, setting the reading value to zero when the anchor rod is in a static state and an unloaded state, respectively.

[0017] A known strain is applied using a standard load applicator, and the output of the strain sensor is recorded. The sensitivity of the strain sensor is equal to the ratio of the voltage change to the strain. Using the same method, a known acceleration and displacement are applied, and the sensitivities of the acceleration and displacement sensors are calibrated. The sensitivity of the acceleration sensor is equal to the ratio of the voltage change to the acceleration change, and the sensitivity of the displacement sensor is equal to the ratio of the voltage change to the displacement change.

[0018] Furthermore, the amplitude, phase, and spectral peak values ​​of the original vibration signal were extracted and analyzed using the following method:

[0019] Bandpass filtering is used to filter the anchor bolt vibration frequency range, and the signal is smoothed by calculating the local mean of the original vibration signal. Finally, maximum normalization is used to adjust the signal amplitude. A Fourier transform is performed on the processed original vibration signal to convert the time-domain signal into a frequency-domain signal. The FFT returns a complex array containing the amplitude and phase of each frequency component. The formulas used to calculate the amplitude and phase are as follows:

[0020]

[0021]

[0022] in, This represents the complex form of the frequency domain signal after Fourier transform. Indicates frequency The amplitude at that point, It is the real part of the frequency domain signal, and it is the cosine component of the signal at that frequency. It is the imaginary part of the frequency domain signal, representing the sinusoidal component of the signal at that frequency. Indicates frequency The phase at a given point is expressed in radians;

[0023] A minimum peak spacing threshold is set, and a local maximum detection algorithm is used to identify spectral peaks.

[0024] Furthermore, the vibration characteristic parameters of the anchoring system, including characteristic modal frequencies, damping ratios, and stiffness coefficients, are calculated using the following method:

[0025] Record the frequency corresponding to each peak in the spectrum, and select the frequency with the highest peak as the characteristic mode frequency. Based on the acquired feature mode frequencies The amplitude point at which the spectral power drops to half of the peak spectral power is defined as the -3dB point, starting from the peak frequency. Find the two frequencies where the amplitude equals -3dB, to the left and to the right. and Calculate the frequency difference between these two frequencies, i.e., the bandwidth. The damping ratio is calculated based on the bandwidth and characteristic modal frequency, using the following formula:

[0026]

[0027] in, Indicates the damping ratio;

[0028] The stiffness coefficient is calculated based on the characteristic modal frequencies and mass, using the following formula:

[0029]

[0030] in, Indicates the stiffness coefficient. The total mass of the anchoring system.

[0031] Furthermore, the ideal values ​​of the vibration characteristic parameters of the helical anchor bolt are obtained using the following method:

[0032] Collect the geometric parameters of the helical anchor to be tested, including the length, diameter, and pitch of the helical part of the anchor. Also obtain the mechanical property parameters of the material used to make the helical anchor, including the elastic modulus, Poisson's ratio, and density. Based on the geometric parameters, use a modeling tool to draw the three-dimensional geometry of the helical anchor. Specify the material properties for the helical anchor by inputting the known elastic modulus, Poisson's ratio, and density.

[0033] The established three-dimensional geometric model of the helical anchor is meshed. The outer contour of the helical anchor and the thin-walled part of the helical structure are meshed using eight-node shell elements. For the main body of the helical anchor, eight-node cube elements are used. It is ensured that the shell elements and the cube elements are well connected to avoid discontinuous or overlapping meshes. Local mesh refinement is performed in the helical part and other stress concentration areas to increase the number and density of mesh elements.

[0034] Based on the constructed finite element model of the helical anchor, select the "modal analysis" option in the software to solve the vibration characteristics. The software outputs the characteristic frequencies and mode shapes of each mode. Extract the ideal values ​​of the vibration characteristic parameters under no external vibration disturbance from the simulation results, including the ideal values ​​of the characteristic mode frequencies, the ideal values ​​of the damping ratio, and the ideal values ​​of the stiffness coefficient.

[0035] Based on the ideal values ​​of the acquired vibration characteristic parameters and the vibration characteristic parameters of the helical anchor bolt to be tested, the stability coefficient of the helical anchor bolt to be tested is generated, and the formula used is as follows:

[0036]

[0037] in, This represents the stability coefficient of the helical anchor bolt under test. , , These represent the calculated measured values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These represent the ideal values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These are the weighting coefficients corresponding to each vibration characteristic parameter.

[0038] Furthermore, the fit between the helical anchor to be tested and the surrounding soil was determined, and stress analysis was performed on the helical anchor to determine the area of ​​maximum stress influence of the anchoring system in the soil. The method used was as follows:

[0039] Obtain the geometric parameters of the helical anchor to be tested, including the anchor length and diameter. Collect soil parameters at the anchoring site, including pore water pressure, total soil stress, soil cohesion, internal friction angle, and soil adhesion coefficient. The fit between the helical anchor and the surrounding soil is defined by the ratio of anchoring force to soil shear strength. The formula used to calculate the anchoring force and soil shear strength is as follows:

[0040]

[0041]

[0042]

[0043] in, This indicates the contact area between the helical anchor bolt to be tested and the surrounding soil. The diameter of the spiral anchor rod to be tested is [diameter value]. The length of the spiral anchor bolt to be tested that penetrates into the soil. Indicates anchoring force. The soil adhesion coefficient, The effective stress of the soil is equal to the difference between the total soil stress and the pore water pressure. Soil shear strength, For soil cohesion, The internal friction angle of the soil;

[0044] The formula for calculating the compatibility between the helical anchor bolt to be tested and the surrounding soil is:

[0045]

[0046] in, This indicates the degree of fit between the helical anchor rod to be tested and the surrounding soil;

[0047] Based on multiple historical pull-out failure tests of helical anchors, the pull-out force when the helical anchor system fails each time is obtained, and the average value of the pull-out force when the anchor system fails multiple times is taken as the critical bearing capacity of the anchor system.

[0048] In the finite element model, a graded loading experiment is conducted on the helical anchor to be tested. The helical anchor is installed at the predetermined position according to the designed depth and angle and is ensured to be fixed. After the helical anchor is anchored, the pull-out force is applied in stages. The method of graded loading is as follows: the initial pull-out force is set to 25% of the critical bearing capacity, and the pull-out force increment of each stage is set to 20% of the critical bearing capacity. The displacement of the helical anchor is monitored when each stage of pull-out force is applied. When the displacement of the helical anchor exceeds the set displacement threshold, the increase of pull-out force is stopped. It is determined whether the pull-out force applied at this time exceeds the critical bearing capacity. If it does not exceed the critical bearing capacity, the pull-out force applied at this time is set as the maximum pull-out force. If it exceeds the critical bearing capacity, the critical bearing capacity is set as the maximum pull-out force.

[0049] Using the probe tool in the finite element analysis software, the point on the anchor rod experiencing the highest stress in the finite element model of the helical anchor rod to be tested is identified, and the stress value at that point is recorded. The stress radius at that point is then calculated using the following formula:

[0050]

[0051] in, This indicates the maximum stress on the helical anchor bolt under test. This indicates the displacement of the helical anchor bolt under maximum pull-out force. This indicates the radius of the maximum stress-affected zone of the helical anchor bolt. This indicates the maximum pull-out force set.

[0052] Centered on the point on the anchor bolt where the pull-out force is greatest, and with... The maximum stress influence area of ​​the helical anchor bolt to be tested is defined by radius.

[0053] Furthermore, the soil density in the area affected by maximum stress was calculated, and an anchorage quality relationship was established to evaluate the anchorage quality of the helical anchor bolt under test. The method used was as follows:

[0054] The dry weight and area of ​​the soil in the region of maximum stress influence are collected to calculate the soil density in the region of maximum stress influence. The formula used is as follows:

[0055]

[0056] in, This indicates the soil density in the area of ​​maximum stress influence. The dry weight of the soil. This represents the area of ​​the soil in the region of maximum stress influence.

[0057] The formula upon which the anchorage quality relationship is based is:

[0058]

[0059] in, This indicates the anchoring quality of the spiral anchor bolt to be tested.

[0060] The present invention also provides a testing device for detecting the anchoring quality of a helical anchor bolt, the testing device being used to perform the above-described testing method for detecting the anchoring quality of a helical anchor bolt, comprising:

[0061] The sensor placement and excitation module is used to install strain sensors, acceleration sensors and displacement sensors on the exposed end of the spiral anchor bolt to be tested and on the surrounding structural surface, and to perform zero-point calibration and sensitivity calibration on all sensors.

[0062] The signal processing and feature analysis module is used to acquire the original vibration response signal of the end of the anchor bolt to be detected in real time, filter, denoise and normalize the original vibration signal, extract the amplitude, phase and spectral peak of the original vibration signal and analyze it, and calculate the vibration characteristic parameters in the anchoring system through time domain and frequency domain analysis methods, including characteristic modal frequency, damping ratio and stiffness coefficient.

[0063] The stability analysis module establishes a finite element model of the helical anchor rod based on mechanical simulation software, and performs modal analysis on it to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor rod. Based on the degree of deviation between the vibration characteristic parameters of the helical anchor rod under test and the ideal values ​​of the vibration characteristic parameters, the stability coefficient of the helical anchor rod under test is generated.

[0064] The parameter acquisition and stress assessment module is used to acquire the parameters of the helical anchor to be tested and the soil parameters of the anchoring site, determine the compatibility between the helical anchor to be tested and the surrounding soil, and perform stress analysis on the helical anchor to be tested to determine the maximum stress influence area of ​​the anchoring system in the soil.

[0065] The anchoring quality assessment module is used to calculate the soil density in the maximum stress influence zone. It establishes an anchoring quality relationship based on the stability coefficient of the helical anchor to be tested, the compatibility between the helical anchor to be tested and the surrounding soil, and the soil density in the maximum stress influence zone, in order to evaluate the anchoring quality of the helical anchor to be tested.

[0066] Compared with the prior art, the beneficial effects of the present invention are:

[0067] This invention enables rapid acquisition of the dynamic characteristics of anchor bolts by real-time monitoring and analysis of vibration response, thereby improving detection efficiency, shortening the construction cycle, reducing the impact on the surrounding environment, ensuring the reliability of anchoring quality, and comprehensively analyzing the vibration characteristic parameters of the anchoring system, such as characteristic modal frequencies, damping ratios, and stiffness coefficients, by extracting the amplitude, phase, and spectral characteristics of the vibration signal.

[0068] This invention determines the maximum stress influence area of ​​the helical anchor under test by conducting graded loading experiments on the anchor. Within the maximum stress influence area, the compatibility between the anchor and the soil is defined by calculating the ratio of anchoring force to soil shear strength. This comprehensive analysis improves the comprehensiveness and accuracy of anchoring quality assessment. Furthermore, the determination of the maximum stress influence area allows for more detailed design and optimization of that area, such as increasing anchoring force or improving anchor materials in key areas, thereby enhancing the safety and durability of the overall anchoring system. Attached Figure Description

[0069] Figure 1 This is a schematic diagram of the overall method flow of the present invention.

[0070] Figure 2 This is a schematic diagram of the system module flow of the present invention. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0072] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0073] Example:

[0074] Please see Figure 1 A testing method for detecting the anchoring quality of helical anchor bolts, comprising the following steps:

[0075] Step 1: Install strain sensors, acceleration sensors, and displacement sensors on the exposed end of the spiral anchor rod to be tested and on the surrounding structural surface, and perform zero-point calibration and sensitivity calibration on all sensors.

[0076] In a specific embodiment of this invention, by installing strain sensors, acceleration sensors, and displacement sensors on the exposed end of the helical anchor bolt and the surrounding structural surface, and performing zero-point calibration and sensitivity calibration, accurate monitoring of the dynamic response of the anchoring system can be achieved. This ensures the accuracy of the sensors under no external force, making data acquisition more reliable, and thus improving the real-time monitoring capability of the anchor bolt's stress, dynamic response, and displacement changes. This precise monitoring can promptly provide feedback on the anchoring status, prevent potential failure risks, and ensure the safety and stability of the project. Furthermore, sensitivity calibration quantifies the sensor's response characteristics, providing a solid foundation for subsequent data analysis and evaluation, and enhancing the reliability and practicality of the monitoring data.

[0077] Furthermore, strain sensors, acceleration sensors, and displacement sensors are installed on the exposed end of the helical anchor bolt to be tested and on the surrounding structural surface, and zero-point calibration and sensitivity calibration are performed. The method used is as follows:

[0078] Before the deep-buried anchoring treatment of the spiral anchor bolt to be tested, strain sensors are installed in the middle and end of the anchor bolt respectively. Epoxy resin is used to fix the strain sensors in the predetermined position. Acceleration sensors are installed on the top of the anchor bolt and the main pipe to monitor the dynamic response affecting the anchoring. Displacement sensors are installed on the exposed end of the anchor bolt to monitor the displacement of the anchor bolt.

[0079] After the sensor is installed, ensure that there is no external force applied, read the output value of the strain sensor, record the value, and perform zero-point calibration based on the data acquisition system, setting the reading value to zero. Similarly, use the same method for the acceleration sensor and displacement sensor, setting the reading value to zero when the anchor rod is in a static state and an unloaded state, respectively.

[0080] A known strain is applied using a standard load applicator, and the output of the strain sensor is recorded. The sensitivity of the strain sensor is equal to the ratio of the voltage change to the strain. Using the same method, a known acceleration and displacement are applied, and the sensitivities of the acceleration and displacement sensors are calibrated. The sensitivity of the acceleration sensor is equal to the ratio of the voltage change to the acceleration change, and the sensitivity of the displacement sensor is equal to the ratio of the voltage change to the displacement change.

[0081] Step 2: Real-time acquisition of the original vibration response signal at the end of the anchor bolt to be tested, filtering, denoising and normalizing the original vibration signal, extracting the amplitude, phase and spectral peak values ​​of the original vibration signal and analyzing them, and calculating the vibration characteristic parameters in the anchoring system through time domain and frequency domain analysis methods, including characteristic modal frequencies, damping ratio and stiffness coefficient.

[0082] In a specific embodiment of the present invention, by extracting and analyzing the amplitude, phase, and spectral peak of the original vibration signal, and combining the calculation of characteristic modal frequencies, damping ratios, and stiffness coefficients, the present invention achieves a comprehensive evaluation of the dynamic characteristics of the anchoring system. By using bandpass filtering and Fourier transform, the time-domain signal is converted into a frequency-domain signal, ensuring efficient and accurate processing of the vibration signal. This effectively eliminates noise interference, extracts useful vibration features, and provides reliable data support for identifying the vibration characteristics of the anchoring system, making the identification of characteristic modal frequencies and the calculation of damping ratios and stiffness coefficients more accurate.

[0083] The reason for setting up this series of sensors and signal processing methods is that traditional anchoring quality assessment often relies on static testing, which cannot fully reflect the actual performance of the anchoring system under dynamic conditions. By monitoring and analyzing vibration response in real time, potential problems can be identified in a timely manner, design and construction plans can be optimized, and the safety and stability of the anchoring system during use can be ensured.

[0084] Furthermore, the amplitude, phase, and spectral peak values ​​of the original vibration signal were extracted and analyzed using the following method:

[0085] Bandpass filtering is used to filter the anchor bolt vibration frequency range, and the signal is smoothed by calculating the local mean of the original vibration signal. Finally, maximum normalization is used to adjust the signal amplitude. A Fourier transform is performed on the processed original vibration signal to convert the time-domain signal into a frequency-domain signal. The FFT returns a complex array containing the amplitude and phase of each frequency component. The formulas used to calculate the amplitude and phase are as follows:

[0086]

[0087]

[0088] in, This represents the complex form of the frequency domain signal after Fourier transform. Indicates frequency The amplitude at that point, It is the real part of the frequency domain signal, and it is the cosine component of the signal at that frequency. It is the imaginary part of the frequency domain signal, representing the sinusoidal component of the signal at that frequency. Indicates frequency The phase at a given point is expressed in radians;

[0089] A minimum peak spacing threshold is set, and a local maximum detection algorithm is used to identify spectral peaks.

[0090] It should be noted that calculating the vibration characteristic parameters in the anchoring system only provides quantitative indicators for the dynamic characteristics of the anchoring system. The characteristic modal frequency is a key parameter describing the vibration characteristics of the structure. It reflects the natural vibration frequency of the anchoring system under specific conditions. By identifying the characteristic modal frequency, the response characteristics of the anchoring system under external excitation can be understood in real time. The damping ratio is an indicator characterizing the energy dissipation capacity of the system. A higher damping ratio means that the system can effectively absorb and attenuate vibration energy, thereby reducing damage to the structure. Calculating the damping ratio can assess the stability and safety of the anchoring system under dynamic loads. The stiffness coefficient characterizes the deformation resistance of the structure under stress and reflects the load-bearing capacity of the anchoring system. By calculating the stiffness coefficient, the strength and stability of the anchoring system can be assessed to ensure that it can withstand the expected load and maintain the overall safety of the structure.

[0091] Furthermore, the vibration characteristic parameters of the anchoring system, including characteristic modal frequencies, damping ratios, and stiffness coefficients, are calculated using the following method:

[0092] Record the frequency corresponding to each peak in the spectrum, and select the frequency with the highest peak as the characteristic mode frequency. Based on the acquired feature mode frequencies The amplitude point at which the spectral power drops to half of the peak spectral power is defined as the -3dB point, starting from the peak frequency. Find the two frequencies where the amplitude equals -3dB, to the left and to the right. and Calculate the frequency difference between these two frequencies, i.e., the bandwidth. The damping ratio is calculated based on the bandwidth and characteristic modal frequency, using the following formula:

[0093]

[0094] in, Indicates the damping ratio;

[0095] The stiffness coefficient is calculated based on the characteristic modal frequencies and mass, using the following formula:

[0096]

[0097] in, Indicates the stiffness coefficient. The total mass of the anchoring system.

[0098] Step 3: Establish a finite element model of the helical anchor rod based on mechanical simulation software, and perform modal analysis on it to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor rod. Based on the degree of deviation between the vibration characteristic parameters of the helical anchor rod under test and the ideal values ​​of the vibration characteristic parameters, generate the stability coefficient of the helical anchor rod under test.

[0099] In a specific embodiment of the present invention, the ideal values ​​of the vibration characteristic parameters of the helical anchor are obtained through finite element model and modal analysis, and the stability coefficient is calculated by combining the actual measured values. This provides a method for quantitatively evaluating the stability of the anchor structure. The advantage of this method is that it can identify deviations from the ideal state, indicate potential defects or performance degradation, and provide engineers with a scientific basis to optimize design and maintenance strategies, ensuring structural safety and reliability.

[0100] Furthermore, the ideal values ​​of the vibration characteristic parameters of the helical anchor bolt are obtained using the following method:

[0101] Collect the geometric parameters of the helical anchor to be tested, including the length, diameter, and pitch of the helical part of the anchor. Also obtain the mechanical property parameters of the material used to make the helical anchor, including the elastic modulus, Poisson's ratio, and density. Based on the geometric parameters, use a modeling tool to draw the three-dimensional geometry of the helical anchor. Specify the material properties for the helical anchor by inputting the known elastic modulus, Poisson's ratio, and density.

[0102] The established three-dimensional geometric model of the helical anchor is meshed. The outer contour of the helical anchor and the thin-walled part of the helical structure are meshed using eight-node shell elements. For the main body of the helical anchor, eight-node cube elements are used. It is ensured that the shell elements and the cube elements are well connected to avoid discontinuous or overlapping meshes. Local mesh refinement is performed in the helical part and other stress concentration areas to increase the number and density of mesh elements.

[0103] Based on the constructed finite element model of the helical anchor, select the "modal analysis" option in the software to solve the vibration characteristics. The software outputs the characteristic frequencies and mode shapes of each mode. Extract the ideal values ​​of the vibration characteristic parameters under no external vibration disturbance from the simulation results, including the ideal values ​​of the characteristic mode frequencies, the ideal values ​​of the damping ratio, and the ideal values ​​of the stiffness coefficient.

[0104] Based on the ideal values ​​of the acquired vibration characteristic parameters and the vibration characteristic parameters of the helical anchor bolt to be tested, the stability coefficient of the helical anchor bolt to be tested is generated, and the formula used is as follows:

[0105]

[0106] in, This represents the stability coefficient of the helical anchor bolt under test. , , These represent the calculated measured values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These represent the ideal values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These are the weighting coefficients corresponding to each vibration characteristic parameter; in the above formula, the weighting coefficients... , , The values ​​are all equal, and absolute deviation is used. , as well as To quantify the difference between actual measured values ​​and ideal values, when the measured value of any one of the parameters—characteristic modal frequency, damping ratio, and stiffness coefficient—deviates significantly from its ideal value, the stability coefficient of the helical anchor under test will decrease. The closer the stability coefficient is to 1, the closer the structure's performance is to the ideal state, and the higher its stability; conversely, if... A low value indicates a significant difference between actual performance and ideal conditions, which may require maintenance or reinforcement.

[0107] Step 4: Obtain the parameters of the helical anchor to be tested and the soil parameters of the anchoring site, determine the compatibility between the helical anchor to be tested and the surrounding soil, and perform stress analysis on the helical anchor to be tested to determine the maximum stress influence area of ​​the anchoring system in the soil.

[0108] In a specific embodiment of this invention, the focus is on the fit and stress analysis between the helical anchor rod to be tested and the surrounding soil to evaluate the performance and stability of the anchoring system. By obtaining the geometric parameters of the helical anchor rod and the relevant mechanical properties of the soil, the ratio of anchoring force to soil shear strength is defined as a quantitative indicator of the fit, thereby effectively evaluating the anchoring performance of the anchor rod in the soil. This invention establishes a systematic methodology to scientifically evaluate the fit and stress distribution of the helical anchor rod, ensuring structural safety. Through the analysis of historical pull-out test data, the critical bearing capacity is determined, and graded loading experiments are conducted in a finite element model to accurately monitor the relationship between pull-out force and displacement, providing reliable data for practical engineering applications.

[0109] It should be noted that the innovation of this invention lies in the first systematic determination of the maximum stress influence area of ​​the helical anchor bolt, and the detailed stress analysis within this area. By using the probe tool in the finite element analysis software to identify the point on the helical anchor bolt with the greatest stress, and using this as the center to delineate the maximum stress influence area, the stress analysis is not limited to the global situation, but focuses on specific, most critical local areas. This improves the accuracy of the assessment of the safety and stability of the anchor bolt. By delineating the maximum stress influence area, potential damage risks can be identified more effectively, providing more targeted guidance for subsequent monitoring and maintenance.

[0110] Furthermore, the fit between the helical anchor to be tested and the surrounding soil was determined, and stress analysis was performed on the helical anchor to determine the area of ​​maximum stress influence of the anchoring system in the soil. The method used was as follows:

[0111] Obtain the geometric parameters of the helical anchor to be tested, including the anchor length and diameter. Collect soil parameters at the anchoring site, including pore water pressure, total soil stress, soil cohesion, internal friction angle, and soil adhesion coefficient. The fit between the helical anchor and the surrounding soil is defined by the ratio of anchoring force to soil shear strength. The formula used to calculate the anchoring force and soil shear strength is as follows:

[0112]

[0113]

[0114]

[0115] in, This indicates the contact area between the helical anchor bolt to be tested and the surrounding soil. The diameter of the spiral anchor rod to be tested is [diameter value]. The length of the spiral anchor bolt to be tested that penetrates into the soil. Indicates anchoring force. The soil adhesion coefficient, The effective stress of the soil is equal to the difference between the total soil stress and the pore water pressure. Soil shear strength, For soil cohesion, The internal friction angle of the soil;

[0116] The formula for calculating the compatibility between the helical anchor bolt to be tested and the surrounding soil is:

[0117]

[0118] in, This indicates the degree of fit between the helical anchor rod to be tested and the surrounding soil;

[0119] Based on multiple historical pull-out failure tests of helical anchors, the pull-out force when the helical anchor system fails each time is obtained, and the average value of the pull-out force when the anchor system fails multiple times is taken as the critical bearing capacity of the anchor system.

[0120] In the finite element model, a graded loading experiment is conducted on the helical anchor to be tested. The helical anchor is installed at the predetermined position according to the designed depth and angle and is ensured to be fixed. After the helical anchor is anchored, the pull-out force is applied in stages. The method of graded loading is as follows: the initial pull-out force is set to 25% of the critical bearing capacity, and the pull-out force increment of each stage is set to 20% of the critical bearing capacity. The displacement of the helical anchor is monitored when each stage of pull-out force is applied. When the displacement of the helical anchor exceeds the set displacement threshold, the increase of pull-out force is stopped. It is determined whether the pull-out force applied at this time exceeds the critical bearing capacity. If it does not exceed the critical bearing capacity, the pull-out force applied at this time is set as the maximum pull-out force. If it exceeds the critical bearing capacity, the critical bearing capacity is set as the maximum pull-out force.

[0121] Using the probe tool in the finite element analysis software, the point on the anchor rod experiencing the highest stress in the finite element model of the helical anchor rod to be tested is identified, and the stress value at that point is recorded. The stress radius at that point is then calculated using the following formula:

[0122]

[0123] in, This indicates the maximum stress on the helical anchor bolt under test. This indicates the displacement of the helical anchor bolt under maximum pull-out force. This indicates the radius of the maximum stress-affected zone of the helical anchor bolt. This indicates the maximum pull-out force set.

[0124] Centered on the point on the anchor bolt where the pull-out force is greatest, and with... The maximum stress influence area of ​​the helical anchor bolt to be tested is defined by radius.

[0125] Step 5: Calculate the soil density in the maximum stress influence zone. Use the stability coefficient of the helical anchor to be tested, the compatibility between the helical anchor to be tested and the surrounding soil, and the soil density in the maximum stress influence zone to establish the anchoring quality relationship, so as to evaluate the anchoring quality of the helical anchor to be tested.

[0126] In a specific embodiment of this invention, soil compaction directly affects the soil's bearing capacity and stability, effectively reflecting the soil's actual performance under stress in the anchoring system. Through detailed analysis of the area affected by maximum stress, combined with measurements of dry weight and area, the soil compaction can be accurately calculated. Furthermore, the anchoring quality formula organically combines the soil's bearing capacity coefficient, compatibility, and soil compaction, providing a quantitative indicator for evaluating the overall anchoring quality of the helical anchor.

[0127] Furthermore, the soil density in the area affected by maximum stress was calculated, and an anchorage quality relationship was established to evaluate the anchorage quality of the helical anchor bolt under test. The method used was as follows:

[0128] The dry weight and area of ​​the soil in the region of maximum stress influence are collected to calculate the soil density in the region of maximum stress influence. The formula used is as follows:

[0129]

[0130] in, This indicates the soil density in the area of ​​maximum stress influence. The dry weight of the soil. The area of ​​the soil in the region of maximum stress influence is denoted as . In the above formula, soil density represents the weight of soil per unit area. This value reflects the compactness of the soil and its overall bearing capacity. Soil density can be derived from the relationship between the dry weight of the soil and its coverage area. Soil density is a key indicator that directly affects the stability, compressive strength, and settlement characteristics of buildings. Higher soil density usually indicates that the soil is more solid, which helps to support greater loads and reduces the risk of settlement.

[0131] The formula upon which the anchorage quality relationship is based is:

[0132]

[0133] in, This indicates the anchoring quality of the spiral anchor bolt to be tested; in the above formula, this term... Using a logarithmic function to adjust the relationship between the stability coefficient and the degree of fit exhibits nonlinear characteristics, making it possible for... and When the anchorage is small, the anchorage quality This will also decrease, but to simulate real-world conditions, the anchoring quality of the helical anchor bolt has an upper limit. Therefore, as... and As the value increases, the increasing trend of anchoring quality will gradually decrease; in the formula... This term, through an exponential function, amplifies the impact of soil density on anchorage quality, emphasizing the importance of density in anchorage quality assessment; the higher the soil density, the better. The higher the value, the better the anchoring quality. A higher value indicates better anchorage quality; in summary, anchorage quality... The higher the value, the higher the anchoring quality of the helical anchor bolt. This means that the anchoring system can better withstand the load, reduce the potential risk of failure, and thus enhance the safety and stability of the project.

[0134] The present invention also provides a testing device for detecting the anchoring quality of a helical anchor bolt, the testing device being used to perform the above-described testing method for detecting the anchoring quality of a helical anchor bolt, comprising:

[0135] The sensor placement and excitation module is used to install strain sensors, acceleration sensors and displacement sensors on the exposed end of the spiral anchor bolt to be tested and on the surrounding structural surface, and to perform zero-point calibration and sensitivity calibration on all sensors.

[0136] The signal processing and feature analysis module is used to acquire the original vibration response signal of the end of the anchor bolt to be detected in real time, filter, denoise and normalize the original vibration signal, extract the amplitude, phase and spectral peak of the original vibration signal and analyze it, and calculate the vibration characteristic parameters in the anchoring system through time domain and frequency domain analysis methods, including characteristic modal frequency, damping ratio and stiffness coefficient.

[0137] The stability analysis module establishes a finite element model of the helical anchor rod based on mechanical simulation software, and performs modal analysis on it to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor rod. Based on the degree of deviation between the vibration characteristic parameters of the helical anchor rod under test and the ideal values ​​of the vibration characteristic parameters, the stability coefficient of the helical anchor rod under test is generated.

[0138] The parameter acquisition and stress assessment module is used to acquire the parameters of the helical anchor to be tested and the soil parameters of the anchoring site, determine the compatibility between the helical anchor to be tested and the surrounding soil, and perform stress analysis on the helical anchor to be tested to determine the maximum stress influence area of ​​the anchoring system in the soil.

[0139] The anchoring quality assessment module is used to calculate the soil density in the maximum stress influence zone. It establishes an anchoring quality relationship based on the stability coefficient of the helical anchor to be tested, the compatibility between the helical anchor to be tested and the surrounding soil, and the soil density in the maximum stress influence zone, in order to evaluate the anchoring quality of the helical anchor to be tested.

[0140] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0141] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0142] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0143] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for detecting the anchoring quality of a helical anchor bolt, characterized in that, The specific steps include: Step 1: Install strain sensors, acceleration sensors, and displacement sensors on the exposed end of the spiral anchor bolt to be tested and on the surrounding structural surface, and perform zero-point calibration and sensitivity calibration on all sensors; Step 2: Real-time acquisition of the original vibration response signal at the end of the anchor bolt to be tested, filtering, denoising and normalizing the original vibration signal, extracting the amplitude, phase and spectral peak value in the original vibration signal and analyzing it, and calculating the vibration characteristic parameters in the anchoring system through time domain and frequency domain analysis methods, including characteristic modal frequency, damping ratio and stiffness coefficient. Step 3: Establish a finite element model of the helical anchor rod based on mechanical simulation software, and perform modal analysis on it to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor rod. Based on the degree of deviation between the vibration characteristic parameters of the helical anchor rod to be tested and the ideal values ​​of the vibration characteristic parameters, generate the stability coefficient of the helical anchor rod to be tested. Step 4: Obtain the parameters of the helical anchor to be tested and the soil parameters of the anchoring site, determine the compatibility between the helical anchor to be tested and the surrounding soil, and perform stress analysis on the helical anchor to be tested to determine the maximum stress influence area of ​​the anchoring system in the soil. Step 5: Calculate the soil density in the maximum stress influence area, and establish the anchoring quality relationship using the stability coefficient of the helical anchor to be tested, the fit between the helical anchor to be tested and the surrounding soil, and the soil density in the maximum stress influence area, so as to evaluate the anchoring quality of the helical anchor to be tested. The method used to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor bolt is as follows: Collect the geometric parameters of the helical anchor to be tested, including the length, diameter, and pitch of the helical part of the anchor. Also obtain the mechanical property parameters of the material used to make the helical anchor, including the elastic modulus, Poisson's ratio, and density. Based on the geometric parameters, use a modeling tool to draw the three-dimensional geometry of the helical anchor. Specify the material properties for the helical anchor by inputting the known elastic modulus, Poisson's ratio, and density. The established three-dimensional geometric model of the helical anchor is meshed. The outer contour of the helical anchor and the thin-walled part of the helical structure are meshed using eight-node shell elements. For the main body of the helical anchor, eight-node cube elements are used. It is ensured that the shell elements and the cube elements are well connected to avoid discontinuous or overlapping meshes. Local mesh refinement is performed in the helical part and other stress concentration areas to increase the number and density of mesh elements. Based on the constructed finite element model of the helical anchor, select the "modal analysis" option in the software to solve the vibration characteristics. The software outputs the characteristic frequencies and mode shapes of each mode. Extract the ideal values ​​of the vibration characteristic parameters under no external vibration disturbance from the simulation results, including the ideal values ​​of the characteristic mode frequencies, the ideal values ​​of the damping ratio, and the ideal values ​​of the stiffness coefficient. Based on the ideal values ​​of the acquired vibration characteristic parameters and the vibration characteristic parameters of the helical anchor bolt to be tested, the stability coefficient of the helical anchor bolt to be tested is generated, and the formula used is as follows: in, This represents the stability coefficient of the helical anchor bolt under test. , , These represent the calculated measured values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These represent the ideal values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These are the weighting coefficients corresponding to each vibration characteristic parameter; The compatibility between the helical anchor to be tested and the surrounding soil was determined, and stress analysis was performed on the helical anchor to determine the area of ​​maximum stress influence of the anchoring system in the soil. The method used was as follows: Obtain the geometric parameters of the helical anchor to be tested, including the anchor length and diameter. Collect soil parameters at the anchoring site, including pore water pressure, total soil stress, soil cohesion, internal friction angle, and soil adhesion coefficient. The fit between the helical anchor and the surrounding soil is defined by the ratio of anchoring force to soil shear strength. The formula used to calculate the anchoring force and soil shear strength is as follows: in, This indicates the contact area between the helical anchor bolt to be tested and the surrounding soil. The diameter of the spiral anchor rod to be tested. The length of the spiral anchor bolt to be tested that penetrates into the soil. Indicates anchoring force. The soil adhesion coefficient, The effective stress of the soil is equal to the difference between the total soil stress and the pore water pressure. Soil shear strength, For soil cohesion, The internal friction angle of the soil; The formula for calculating the compatibility between the helical anchor bolt to be tested and the surrounding soil is: in, This indicates the degree of fit between the helical anchor rod to be tested and the surrounding soil; Based on multiple historical pull-out failure tests of helical anchors, the pull-out force when the helical anchor system fails each time is obtained, and the average value of the pull-out force when the anchor system fails multiple times is taken as the critical bearing capacity of the anchor system. In the finite element model, a graded loading experiment is conducted on the helical anchor to be tested. The helical anchor is installed at the predetermined position according to the designed depth and angle and is ensured to be fixed. After the helical anchor is anchored, the pull-out force is applied in stages. The method of graded loading is as follows: the initial pull-out force is set to 25% of the critical bearing capacity, and the pull-out force increment of each stage is set to 20% of the critical bearing capacity. The displacement of the helical anchor is monitored when each stage of pull-out force is applied. When the displacement of the helical anchor exceeds the set displacement threshold, the increase of pull-out force is stopped. It is determined whether the pull-out force applied at this time exceeds the critical bearing capacity. If it does not exceed the critical bearing capacity, the pull-out force applied at this time is set as the maximum pull-out force. If it exceeds the critical bearing capacity, the critical bearing capacity is set as the maximum pull-out force. Using the probe tool in the finite element analysis software, the point on the anchor rod experiencing the highest stress in the finite element model of the helical anchor rod to be tested is identified, and the stress value at that point is recorded. The stress radius at that point is then calculated using the following formula: in, This indicates the maximum stress on the helical anchor bolt under test. This indicates the displacement of the helical anchor bolt under maximum pull-out force. This indicates the radius of the maximum stress-affected zone of the helical anchor bolt. This indicates the maximum pull-out force set. Centered on the point on the anchor bolt where the pull-out force is greatest, and with... Use the radius to define the maximum stress influence area of ​​the helical anchor bolt to be tested; The soil density in the area of ​​maximum stress influence was calculated, and an anchorage quality relationship was established to evaluate the anchorage quality of the helical anchor bolt to be tested. The method used was as follows: The dry weight and area of ​​the soil in the region of maximum stress influence are collected to calculate the soil density in the region of maximum stress influence. The formula used is as follows: in, This indicates the soil density in the area of ​​maximum stress influence. The dry weight of the soil. This represents the area of ​​the soil in the region of maximum stress influence. The formula upon which the anchorage quality relationship is based is: in, This indicates the anchoring quality of the spiral anchor bolt to be tested.

2. The method for detecting the anchoring quality of a spiral anchor bolt according to claim 1, characterized in that... Strain sensors, acceleration sensors, and displacement sensors were installed on the exposed end of the helical anchor bolt to be tested and on the surrounding structural surface. Zero-point calibration and sensitivity calibration were performed using the following method: Before the deep-buried anchoring treatment of the spiral anchor bolt to be tested, strain sensors are installed in the middle and end of the anchor bolt respectively. Epoxy resin is used to fix the strain sensors in the predetermined position. Acceleration sensors are installed on the top of the anchor bolt and the main pipe to monitor the dynamic response affecting the anchoring. Displacement sensors are installed on the exposed end of the anchor bolt to monitor the displacement of the anchor bolt. After the sensor is installed, ensure that there is no external force applied, read the output value of the strain sensor, record the value, and perform zero-point calibration based on the data acquisition system, setting the reading value to zero. Similarly, use the same method for the acceleration sensor and displacement sensor, setting the reading value to zero when the anchor rod is in a static state and an unloaded state, respectively. A known strain is applied using a standard load applicator, and the output of the strain sensor is recorded. The sensitivity of the strain sensor is equal to the ratio of the voltage change to the strain. Using the same method, a known acceleration and displacement are applied, and the sensitivities of the acceleration and displacement sensors are calibrated. The sensitivity of the acceleration sensor is equal to the ratio of the voltage change to the acceleration change, and the sensitivity of the displacement sensor is equal to the ratio of the voltage change to the displacement change.

3. The method for detecting the anchoring quality of a spiral anchor bolt according to claim 2, characterized in that, The method used to extract and analyze the amplitude, phase, and spectral peaks from the original vibration signal is as follows: Bandpass filtering is used to filter the anchor bolt vibration frequency range, and the signal is smoothed by calculating the local mean of the original vibration signal. Finally, maximum normalization is used to adjust the signal amplitude. A Fourier transform is performed on the processed original vibration signal to convert the time-domain signal into a frequency-domain signal. The FFT returns a complex array containing the amplitude and phase of each frequency component. The formulas used to calculate the amplitude and phase are as follows: in, This represents the complex form of the frequency domain signal after Fourier transform. Indicates frequency The amplitude at that point, It is the real part of the frequency domain signal, and it is the cosine component of the signal at that frequency. It is the imaginary part of the frequency domain signal, representing the sinusoidal component of the signal at that frequency. Indicates frequency The phase at a given point is expressed in radians; A minimum peak spacing threshold is set, and a local maximum detection algorithm is used to identify spectral peaks.

4. The method for detecting the anchoring quality of a spiral anchor bolt according to claim 3, characterized in that, The calculation of vibration characteristic parameters in the anchorage system includes characteristic modal frequencies, damping ratios, and stiffness coefficients. The method used is as follows: Record the frequency corresponding to each peak in the spectrum, and select the frequency with the highest peak as the characteristic mode frequency. Based on the acquired feature mode frequencies The amplitude point at which the spectral power drops to half of the peak spectral power is defined as the -3dB point, starting from the peak frequency. Find the two frequencies where the amplitude equals -3dB, to the left and to the right. and Calculate the frequency difference between these two frequencies, i.e., the bandwidth. The damping ratio is calculated based on the bandwidth and characteristic modal frequency, using the following formula: in, Indicates the damping ratio; The stiffness coefficient is calculated based on the characteristic modal frequencies and mass, using the following formula: in, Indicates the stiffness coefficient. The total mass of the anchoring system.

5. A testing device for detecting the anchoring quality of a spiral anchor bolt, characterized in that, The detection device is used to perform the detection method for detecting the anchoring quality of a spiral anchor bolt as described in any one of claims 1-4, including: The sensor placement and excitation module is used to install strain sensors, acceleration sensors and displacement sensors on the exposed end of the spiral anchor bolt to be tested and on the surrounding structural surface, and to perform zero-point calibration and sensitivity calibration on all sensors. The signal processing and feature analysis module is used to acquire the original vibration response signal of the end of the anchor bolt to be detected in real time, filter, denoise and normalize the original vibration signal, extract the amplitude, phase and spectral peak of the original vibration signal and analyze it, and calculate the vibration characteristic parameters in the anchoring system through time domain and frequency domain analysis methods, including characteristic modal frequency, damping ratio and stiffness coefficient. The stability analysis module establishes a finite element model of the helical anchor rod based on mechanical simulation software, and performs modal analysis on it to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor rod. Based on the degree of deviation between the vibration characteristic parameters of the helical anchor rod under test and the ideal values ​​of the vibration characteristic parameters, the stability coefficient of the helical anchor rod under test is generated. The parameter acquisition and stress assessment module is used to acquire the parameters of the helical anchor to be tested and the soil parameters of the anchoring site, determine the compatibility between the helical anchor to be tested and the surrounding soil, and perform stress analysis on the helical anchor to be tested to determine the maximum stress influence area of ​​the anchoring system in the soil. The anchoring quality assessment module is used to calculate the soil density in the maximum stress influence area. It establishes an anchoring quality relationship based on the stability coefficient of the helical anchor to be tested, the compatibility between the helical anchor to be tested and the surrounding soil, and the soil density in the maximum stress influence area, so as to evaluate the anchoring quality of the helical anchor to be tested. The method used to obtain the ideal values ​​of the vibration characteristic parameters of the helical anchor bolt is as follows: Collect the geometric parameters of the helical anchor to be tested, including the length, diameter, and pitch of the helical part of the anchor. Also obtain the mechanical property parameters of the material used to make the helical anchor, including the elastic modulus, Poisson's ratio, and density. Based on the geometric parameters, use a modeling tool to draw the three-dimensional geometry of the helical anchor. Specify the material properties for the helical anchor by inputting the known elastic modulus, Poisson's ratio, and density. The established three-dimensional geometric model of the helical anchor is meshed. The outer contour of the helical anchor and the thin-walled part of the helical structure are meshed using eight-node shell elements. For the main body of the helical anchor, eight-node cube elements are used. It is ensured that the shell elements and the cube elements are well connected to avoid discontinuous or overlapping meshes. Local mesh refinement is performed in the helical part and other stress concentration areas to increase the number and density of mesh elements. Based on the constructed finite element model of the helical anchor, select the "modal analysis" option in the software to solve the vibration characteristics. The software outputs the characteristic frequencies and mode shapes of each mode. Extract the ideal values ​​of the vibration characteristic parameters under no external vibration disturbance from the simulation results, including the ideal values ​​of the characteristic mode frequencies, the ideal values ​​of the damping ratio, and the ideal values ​​of the stiffness coefficient. Based on the ideal values ​​of the acquired vibration characteristic parameters and the vibration characteristic parameters of the helical anchor bolt to be tested, the stability coefficient of the helical anchor bolt to be tested is generated, and the formula used is as follows: in, This represents the stability coefficient of the helical anchor bolt under test. , , These represent the calculated measured values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These represent the ideal values ​​of the characteristic modal frequency, damping ratio, and stiffness coefficient, respectively. , , These are the weighting coefficients corresponding to each vibration characteristic parameter; The compatibility between the helical anchor to be tested and the surrounding soil was determined, and stress analysis was performed on the helical anchor to determine the area of ​​maximum stress influence of the anchoring system in the soil. The method used was as follows: Obtain the geometric parameters of the helical anchor to be tested, including the anchor length and diameter. Collect soil parameters at the anchoring site, including pore water pressure, total soil stress, soil cohesion, internal friction angle, and soil adhesion coefficient. The fit between the helical anchor and the surrounding soil is defined by the ratio of anchoring force to soil shear strength. The formula used to calculate the anchoring force and soil shear strength is as follows: in, This indicates the contact area between the helical anchor bolt to be tested and the surrounding soil. The diameter of the spiral anchor rod to be tested is [diameter value]. The length of the spiral anchor bolt to be tested that penetrates into the soil. Indicates anchoring force. The soil adhesion coefficient, The effective stress of the soil is equal to the difference between the total soil stress and the pore water pressure. Soil shear strength, For soil cohesion, The internal friction angle of the soil; The formula for calculating the compatibility between the helical anchor bolt to be tested and the surrounding soil is: in, This indicates the degree of fit between the helical anchor rod to be tested and the surrounding soil; Based on multiple historical pull-out failure tests of helical anchors, the pull-out force when the helical anchor system fails each time is obtained, and the average value of the pull-out force when the anchor system fails multiple times is taken as the critical bearing capacity of the anchor system. In the finite element model, a graded loading experiment is conducted on the helical anchor to be tested. The helical anchor is installed at the predetermined position according to the designed depth and angle and is ensured to be fixed. After the helical anchor is anchored, the pull-out force is applied in stages. The method of graded loading is as follows: the initial pull-out force is set to 25% of the critical bearing capacity, and the pull-out force increment of each stage is set to 20% of the critical bearing capacity. The displacement of the helical anchor is monitored when each stage of pull-out force is applied. When the displacement of the helical anchor exceeds the set displacement threshold, the increase of pull-out force is stopped. It is determined whether the pull-out force applied at this time exceeds the critical bearing capacity. If it does not exceed the critical bearing capacity, the pull-out force applied at this time is set as the maximum pull-out force. If it exceeds the critical bearing capacity, the critical bearing capacity is set as the maximum pull-out force. Using the probe tool in the finite element analysis software, the point on the anchor rod experiencing the highest stress in the finite element model of the helical anchor rod to be tested is identified, and the stress value at that point is recorded. The stress radius at that point is then calculated using the following formula: in, This indicates the maximum stress on the helical anchor bolt under test. This indicates the displacement of the helical anchor bolt under maximum pull-out force. This indicates the radius of the maximum stress-affected zone of the helical anchor bolt. This indicates the maximum pull-out force set. Centered on the point on the anchor bolt where the pull-out force is greatest, and with... Use the radius to define the maximum stress influence area of ​​the helical anchor bolt to be tested; The soil density in the area of ​​maximum stress influence was calculated, and an anchorage quality relationship was established to evaluate the anchorage quality of the helical anchor bolt to be tested. The method used was as follows: The dry weight and area of ​​the soil in the region of maximum stress influence are collected to calculate the soil density in the region of maximum stress influence. The formula used is as follows: in, This indicates the soil density in the area of ​​maximum stress influence. The dry weight of the soil. This represents the area of ​​the soil in the region of maximum stress influence. The formula upon which the anchorage quality relationship is based is: in, This indicates the anchoring quality of the spiral anchor bolt to be tested.

Images