Tunnel structure deformation measurement method based on millimeter wave radar

Abstract

The invention discloses a tunnel structure deformation measurement method based on millimeter wave radar, which belongs to the technical field of structure deformation monitoring, and comprises the following steps: measuring a tunnel section by using a measurement device, processing data through a power spectrum estimation method, and obtaining a frequency domain matrix; performing frequency tracking to obtain a corresponding frequency domain tracking matrix and a corresponding distance matrix; and obtaining the frequency corresponding to the section clearance, calculating the measurement distance of the tunnel clearance at each angle according to the tunnel clearance frequency, drawing the clearance of the tunnel section according to the tunnel clearance measurement distance and the scanning measurement angle, and completing the clearance imaging of the tunnel section. The measuring device can complete scanning measurement of the whole section of the tunnel, is high in real-time performance and anti-interference capability, and can adapt to tunnel section deformation measurement completed in a complex environment; the deformation amount of the tunnel section is accurately and quickly obtained through a power spectrum estimation method, and the efficiency and precision of tunnel section deformation detection are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of structural deformation monitoring, and in particular relates to a tunnel structure deformation measurement method based on millimeter wave radar. Background Art

[0002] Due to adverse geological conditions such as fault fracture zones and accumulation bodies, large deformation of the tunnel structure section is prone to occur during the construction of super-large railways, which may cause deformation of the tunnel wall, instability of the surrounding rock, and destruction of the stability of the tunnel structure. In severe cases, the tunnel may collapse, affecting the construction of the tunnel and the safety of personnel.

[0003] At present, the existing monitoring and measurement methods are mainly manual, time-consuming, with limited measurement points, and there is a time and space contradiction between tunnel construction and measurement. In addition, the accuracy of the measurement results is severely limited by the on-site measurement personnel. At the same time, the existing measurement devices such as total stations have poor real-time performance and cannot meet the continuous monitoring of tunnel sections. More advanced technologies such as laser technology are relatively expensive, and often require repositioning to continue measurement due to the movement of equipment during tunnel blasting, which is inconsistent with the complex construction site. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a tunnel structure deformation measurement method based on millimeter wave radar.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for measuring tunnel structure deformation based on millimeter wave radar comprises the following steps:

[0007] Step 1: Tunnel deformation section scanning data collection:

[0008] The tunnel section is measured using a measuring device, the millimeter wave radar of the measuring device collects data of the entire tunnel section, and records the scanning measurement angle and the corresponding scanning measurement times;

[0009] Step 2: Millimeter wave radar data preprocessing method:

[0010] The measured data is processed by the power spectrum estimation method, and the target and noise are distinguished to obtain a frequency domain matrix;

[0011] Step 3: Frequency domain tracking:

[0012] Taking the non-zero element in the first row vector of the frequency matrix as the starting node, frequency tracking is performed to obtain the corresponding frequency domain tracking matrix and the corresponding distance matrix;

[0013] Step 4: Tunnel section clearance imaging:

[0014] Obtain the corresponding frequency of the cross-section clearance, calculate the measurement distance of the tunnel clearance at various angles according to the tunnel clearance frequency, draw the clearance of the tunnel section according to the tunnel clearance measurement distance and the scanning measurement angle, and complete the clearance imaging of the tunnel section.

[0015] Furthermore, the measuring device includes a transparent and waterproof shell and a measuring component that can rotate to measure the tunnel section, and a power supply and a server are arranged in the shell; the measuring component includes a bracket, a motor, a rotary arm and a millimeter-wave radar, and the motor is fixed to the inner wall of the shell through the bracket, one end of the rotary arm is connected to the output shaft of the motor, and the other end is connected to the millimeter-wave radar, and the millimeter-wave radar and the motor are both connected to the power supply and the server.

[0016] Furthermore, in step 1, when the measuring device scans the tunnel section, the antenna part of the millimeter wave radar is fixed relative to the rotary arm during the scanning process; the measuring device measures the tunnel section in a rotation-stop-measurement-rotation mode, and the angle at which the i-th measurement is performed is α i , which is the scanning measurement angle; the number of scanning measurements i = 1, 2, ..., N; the difference between adjacent measurement angles is Δα.

[0017] Furthermore, in step 1, during a single measurement, the millimeter-wave radar generates a linear frequency modulated continuous wave signal, which is equally divided into two paths by a power divider, one of which is transmitted to the mixer as input, and the other is transmitted to the transmitting antenna of the millimeter-wave radar after passing through the power amplifier and emitted through the transmitting (TX) antenna. The form of the transmitted signal is:

[0018]

[0019] Among them, A e is the gain of the antenna; j represents an imaginary number; f c is the carrier frequency of the radar, that is, the starting frequency of the radar signal, S is the frequency modulation slope of the signal, t is the duration of the signal, and θ0 is the initial phase of the signal;

[0020] The receiving (RX) antenna of the millimeter wave radar receives the echo signal reflected from the tunnel surface. The echo signal is in the form of:

[0021] s r (t) = A r exp{j2π(f c (t-τ)+πS(t-τ) 2 )+θ0};

[0022] The echo signal waveform received by the receiving (RX) antenna is the signal after the transmitted signal waveform is delayed for a period of time. The delay time τ is the round-trip delay from the millimeter-wave radar to the target point; A ris the amplitude of the echo signal;

[0023] The mixer then mixes the transmitted signal and the echo signal to generate an intermediate frequency signal with a specific frequency:

[0024] s IF (t) = Aexp{j2πStτ+j2πf c τ}

[0025] Where A is the amplitude of the intermediate frequency signal; f c >>B, T>>τ, B is the bandwidth, T is the duration of the continuous frequency modulation signal.

[0026] Furthermore, in step 2, due to the influence of construction personnel and on-site equipment and devices during the actual measurement, the sampled data has multiple reflectors; assuming that in the i-th measurement, the sampled data has a total of M reflectors, and the reflected intermediate frequency signal is expressed as:

[0027]

[0028] In the formula, α i is the scanning measurement angle, the scanning measurement times i=1,2,……,N; A k , τ k are the reflected signal amplitude and the round-trip delay of the reflected signal of the kth reflector respectively.

[0029] Furthermore, in step 2, the frequency matrix construction process is as follows:

[0030] The intermediate frequency signal is digitized into a discrete random signal with L data points. Then Perform Fourier transform and get the transformation result For the original signal The real power spectrum The estimates are as follows:

[0031]

[0032] Since the number of reflectors M is unknown, take The first five peak frequencies are m={1,2,3,4,5}, i is the i-th measurement, and an N×5 frequency matrix Ψ is constructed from it, and the matrix Ψ is reconstructed into a 5N×1 column frequency vector Ψ'; the maximum value f in the frequency vector is obtained max and the minimum value f min ,

[0033] f max =max(Ψ'),f min =min(Ψ')

[0034] And the maximum value f max and the minimum value f min For the upper and lower limits, make a histogram with N bins. The histogram quantity vector is expressed as And construct the indicator vector Γ as follows:

[0035] Γ=[a1,a2,…,a N ] T ,a i =1,ifφ i ≠0; or a i =0

[0036] The connectivity is judged by the distribution of elements 0 and 1 in the indicator vector Γ. Without loss of generality, the connected area of ​​the histogram is divided into two sets Γ1 and Γ2, which are expressed as:

[0037] Γ1={a i ,a i+1 ,…,a n}

[0038] Γ2={a j ,a j+1 ,…,a k}

[0039] Among them, n+1 represents the number of elements in the Γ1 set, and the corresponding subscripts are i, i+1, ..., n; k+1 represents the number of elements in the Γ2 set, and the corresponding subscripts are j, j+1, ..., k;

[0040] Get its main frequency distribution interval, the histogram quantity vector and corresponding to the set Γ1 and Γ2 are expressed as:

[0041]

[0042] Pick The corresponding set is the main frequency distribution area Γ', which is the possible reflection of the tunnel lining surface, and the others are noise signals reflected by construction personnel and on-site machinery and equipment. The matrix elements corresponding to the noise frequencies of construction personnel and on-site machinery and equipment are set to 0, and the frequency matrix Ψ is updated to Ψ":

[0043]

[0044] Further, in step 3, the non-zero value elements in the frequency domain matrix Ψ" are defined as frequency nodes, and the non-zero elements in the first row vector of the frequency matrix Ψ" are As the starting point, frequency tracking is performed; let the current frequency node be represents the frequency node in the i-th row and m-th column, then and the row vector element of row i+1 The frequency domain distance dp (i,i+1) is expressed as:

[0045]

[0046] And add the corresponding node is the frequency domain node vector of the starting node

[0047]

[0048] And construct the distance vector d p :

[0049] d p =[d p (1,2),…,d p (i,i+1),…d p (N-1,N)] T

[0050] The corresponding frequency domain tracking matrix df and the corresponding distance matrix d can be obtained.

[0051] Furthermore, in step 4, the tracking frequency corresponding to the minimum value of the column vector in the distance matrix is ​​taken as the tunnel section clearance frequency df p , and according to the formula between tunnel clearance frequency and distance:

[0052]

[0053] Among them, R i is the clearance measurement distance of the ith tunnel, c is the speed of light, df i p is the ith tunnel clearance frequency, S is the signal frequency modulation slope set by the device;

[0054] Tunnel clearance measurement distance R i With scanning measurement angle α i Together constitute (R i ,α i ) polar coordinate pairs, the tunnel section clearance can be drawn in space based on the obtained polar coordinate pairs.

[0055] Compared with the prior art, the present invention has the following technical advances:

[0056] The present invention collects data of the entire cross-section of the tunnel through a measuring device, and uses power spectrum estimation and frequency domain tracking methods to complete the clearance imaging of the tunnel cross-section. The measuring device based on millimeter wave radar can perform multi-point continuous measurement to complete the scanning measurement of the entire cross-section of the tunnel; the scanning measurement of the measuring device has strong real-time performance and can quickly complete the scanning measurement of the entire cross-section of the tunnel; at the same time, the measuring device has strong anti-interference ability and can adapt to the deformation measurement of the tunnel cross-section completed in a complex environment without being interfered by external factors; the deformation of the tunnel cross-section is accurately and quickly obtained through the power spectrum estimation method, thereby improving the efficiency and accuracy of tunnel cross-section deformation detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0058] In the attached picture:

[0059] Figure 1 A schematic diagram of tunnel cross-section scanning measurement using the present invention;

[0060] Figure 2 The figure is a tunnel clearance diagram obtained by adopting the present invention.

[0061] Figure 3 A schematic diagram of the internal structure of a measuring device used in an embodiment of the present invention;

[0062] Figure 4 A schematic diagram of a housing of a measuring device used in an embodiment of the present invention;

[0063] In the figure:

[0064] 00-tunnel section, 01-measuring device; 1-housing; 2-power supply; 3-server; 4-bracket; 5-motor; 6-swing arm; 7-millimeter wave radar. DETAILED DESCRIPTION

[0065] The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0066] like Figure 1 , Figure 2 and Figure 3 As shown, a tunnel structure deformation measurement method based on millimeter wave radar includes the following steps:

[0067] Step 1: Tunnel deformation section scanning data collection:

[0068] The tunnel section is measured by using a measuring device. The millimeter wave radar of the measuring device can collect the data of the tunnel section 00 and record the scanning measurement angle and the corresponding scanning measurement times. Figure 3 , 4 As shown, the measuring device 01 includes a transparent and waterproof shell 1 and a measuring component that can rotate to measure the tunnel section, and a power supply 2 and a server 3 are arranged in the shell 1; the measuring component includes a bracket 4, a motor 5, a rotary arm 6 and a millimeter-wave radar 7, and the motor 5 is fixed to the inner wall of the shell 1 through the bracket 4, one end of the rotary arm 6 is connected to the output shaft of the motor 5, and the other end is connected to the millimeter-wave radar 7, and the millimeter-wave radar 7 and the motor 5 are both connected to the power supply 2 and the server 3.

[0069] The millimeter wave radar transmits a linear frequency modulation signal, which forms a reflected signal on the tunnel surface. By analyzing the transmitted and reflected signals, the distance and azimuth of the tunnel section can be measured, such as Figure 1 When scanning the tunnel section, the antenna part of the device is fixed relative to the arm during the scanning process, and no movement is involved. Data can be obtained continuously during the rotation, so it can realize the deformation measurement of the entire tunnel section. The specific measurement process is as follows:

[0070] The measuring device uses the mode of rotation-stop-measurement-rotation to measure the tunnel section. Let the angle of the i-th measurement be α i , which is the scanning measurement angle; the number of scanning measurements i = 1, 2, ..., N; the difference between adjacent measurement angles is Δα.

[0071] In a single measurement, the millimeter-wave radar generates a linear frequency modulated continuous wave signal, which is divided into two equal paths by a power divider. One path is transmitted to the mixer as input, and the other path is transmitted to the transmitting antenna of the millimeter-wave radar after passing through the power amplifier and emitted through the transmitting antenna (TX). The form of the transmitted signal is:

[0072]

[0073] Among them, A e is the gain of the antenna, f c is the carrier frequency of the radar, that is, the starting frequency of the radar signal, S is the frequency modulation slope of the signal, t is the duration of the signal, and θ0 is the initial phase of the signal.

[0074] The receiving antenna (RX) of the millimeter wave radar receives the echo signal reflected from the tunnel surface. The echo signal is in the form of:

[0075] s r (t) = A r exp{j2π(f c (t-τ)+πS(t-τ) 2)+θ0} (2);

[0076] The echo signal waveform received by the receiving antenna (RX) is the signal after the transmitted signal waveform is delayed for a period of time. The delay time τ is the round-trip delay from the millimeter-wave radar to the target point; A r is the amplitude of the echo signal;

[0077] The mixer then mixes the transmitted signal and the echo signal to generate an intermediate frequency signal (IF) with a specific frequency:

[0078] s IF (t) = s t (t)×s r * (t) = Aexp{j2πf c [t-(t-τ)]+jπS[t 2 -(t-τ) 2 ])} (3)

[0079] Simplifying, we get:

[0080] s IF (t) = Aexp{j2πf c τ+j2πStτ-jπSτ 2} (4)

[0081] The above formula can be rewritten as follows:

[0082]

[0083] Where A is the amplitude of the intermediate frequency signal; f c >>B, T>>τ, B is the bandwidth, T is the duration of the continuous frequency modulation signal. Therefore, the final intermediate frequency signal can be expressed as:

[0084] s IF (t) = Aexp{j2πStτ+j2πf c τ} (6)

[0085] Step 2: Millimeter wave radar data preprocessing method:

[0086] Due to the influence of construction personnel and on-site equipment and devices during the actual measurement process, the sampling data contains multiple reflectors.

[0087] Assume that there are M reflectors in total during the i-th measurement, and the intermediate frequency signal reflected back can be expressed as:

[0088]

[0089] In the formula, α i is the scanning measurement angle, i=1,2,……,N, N is the number of scanning measurements; Ak , τ k are the reflected signal amplitude and the round-trip delay of the reflected signal of the kth reflector respectively.

[0090] After the intermediate frequency signal is digitized, it becomes a discrete random signal with L data points. Then Perform Fourier transform and get the transformation result Then calculate the square of the amplitude of the transformation result and divide it by the number of data points L to obtain the square of the original signal. The real power spectrum Estimates:

[0091]

[0092] Since the number of reflectors M is unknown, take The first five peak frequencies are m={1,2,3,4,5}, i is the i-th measurement, and an N×5 frequency matrix Ψ is constructed from it, and the matrix Ψ is reconstructed into a 5N×1 column frequency vector Ψ'. Get the maximum value f in the frequency vector max and the minimum value f min ,

[0093] f max =max(Ψ'),f min =min(Ψ') (9)

[0094] And the maximum value f max and the minimum value f min As the upper and lower limits, make a histogram with N bins. The histogram quantity vector is represented as And construct the indicator vector Γ:

[0095] Γ=[a1,a2,…,a N ] T ,a i =1,ifφ i ≠0;ora i =0 (10)

[0096] The connectivity is judged by the distribution of elements 0 and 1 in the indicator vector Γ. Without loss of generality, the connected area of ​​the histogram is divided into two sets Γ1 and Γ2, which are expressed as:

[0097] Γ1={a i ,a i+1 ,…,a n}

[0098] Γ2={a j ,a j+1 ,…,a k} (11)

[0099] Among them, n+1 represents the number of elements in the Γ1 set, and the corresponding subscripts are i, i+1,…, n; k+1 represents the number of elements in the Γ2 set, and the corresponding subscripts are j, j+1,…, k.

[0100] Get its main frequency distribution interval, the histogram quantity vector and corresponding to the set Γ1 and Γ2 are expressed as:

[0101]

[0102] Pick The corresponding set is the main frequency distribution area Γ', which is the possible reflection of the tunnel lining surface, and the others are noise signals reflected by construction personnel and on-site machinery and equipment. The frequency matrix Ψ is updated to Ψ", where the corresponding matrix elements are set to 0 for the noise frequencies of construction personnel and on-site machinery and equipment according to the above analysis.

[0103]

[0104] Step 3: Frequency domain tracking:

[0105] Define the non-zero elements in the frequency domain matrix Ψ" as frequency nodes. Take the non-zero elements in the first row vector of the frequency matrix Ψ" Assume that the current frequency node is represents the frequency node in the i-th row and m-th column, then and the row vector element of row i+1 The frequency domain distance d p (i,i+1) is expressed as:

[0106]

[0107] And add the corresponding node is the frequency domain node vector of the starting node

[0108]

[0109] And construct the distance vector d p :

[0110] d p =[d p (1,2),…,d p (i,i+1),…d p (N-1,N)] T (16)

[0111] Then, the corresponding frequency domain tracking matrix df and the corresponding distance matrix d can be obtained.

[0112] Step 4: Tunnel section clearance imaging:

[0113] Get the corresponding frequency of the cross-section clearance: take the tracking frequency corresponding to the minimum value of the column vector in the distance matrix as the tunnel cross-section clearance frequency df p , and according to the formula between tunnel clearance frequency and distance:

[0114]

[0115] Among them, R i is the clearance measurement distance of the ith tunnel, c is the speed of light, df i p is the ith tunnel clearance frequency, and S is the signal frequency modulation slope set by the device.

[0116] Tunnel clearance measurement distance R i With scanning measurement angle α i Together constitute (R i ,α i ) polar coordinate pairs, the tunnel section clearance can be drawn in space according to the obtained polar coordinate pairs, such as Figure 2 shown.

[0117] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A method for measuring tunnel structure deformation based on millimeter wave radar, characterized in that: The following steps are involved: Step 1: Tunnel deformation section scanning data collection: The tunnel section is measured using a measuring device, the millimeter wave radar of the measuring device collects data of the entire tunnel section, and records the scanning measurement angle and the corresponding scanning measurement times; Step 2: Millimeter wave radar data preprocessing method: The measured data is processed by the power spectrum estimation method, and the target and noise are distinguished to obtain a frequency domain matrix; Step 3: Frequency domain tracking: Taking the non-zero element in the first row vector of the frequency matrix as the starting node, frequency tracking is performed to obtain the corresponding frequency domain tracking matrix and the corresponding distance matrix; Step 4: Tunnel section clearance imaging: Obtain the corresponding frequency of the cross-section clearance, calculate the measurement distance of the tunnel clearance at various angles according to the tunnel clearance frequency, draw the clearance of the tunnel section according to the tunnel clearance measurement distance and the scanning measurement angle, and complete the clearance imaging of the tunnel section.

2. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 1, characterized in that: The measuring device includes a waterproof shell and a measuring component that can rotate to measure the tunnel section. A power supply and a server are arranged in the shell. The measuring component includes a bracket, a motor, a rotary arm and a millimeter-wave radar. The motor is fixed to the inner wall of the shell through the bracket. One end of the rotary arm is connected to the output shaft of the motor and the other end is connected to the millimeter-wave radar. The millimeter-wave radar and the motor are both connected to the power supply and the server.

3. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 2, characterized in that: In step 1, when the measuring device scans the tunnel section, the antenna part of the millimeter wave radar is fixed relative to the swing arm during the scanning process; the measuring device measures the tunnel section in a rotation-stop-measurement-rotation mode, and the angle at which the i-th measurement is performed is α i , which is the scanning measurement angle; the number of scanning measurements i = 1, 2, ..., N; the difference between adjacent measurement angles is Δα.

4. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 1, characterized in that: In step 1, during a single measurement, the millimeter-wave radar generates a linear frequency modulated continuous wave signal, which is divided into two equal paths by a power divider. One path is transmitted to the mixer as input, and the other path is transmitted to the transmitting antenna of the millimeter-wave radar after passing through the power amplifier and emitted by the transmitting antenna. The form of the transmitted signal is: Among them, A e is the gain of the antenna, j represents an imaginary number; f c is the carrier frequency of the radar, that is, the starting frequency of the radar signal, S is the frequency modulation slope of the signal, t is the duration of the signal, and θ0 is the initial phase of the signal; The receiving antenna of the millimeter wave radar receives the echo signal reflected from the tunnel surface. The echo signal is in the form of: s r (t)=A r exp{j2π(f c (t-τ)+πS(t-τ) 2 )+θ0}; The echo signal waveform received by the receiving antenna is the signal after the transmitted signal waveform is delayed for a period of time. The delay time τ is the round-trip delay from the millimeter-wave radar to the target point. r is the amplitude of the echo signal; The mixer then mixes the transmitted signal and the echo signal to generate an intermediate frequency signal with a specific frequency: s IF (t)=Aexp{j2πStτ+j2πf c t} Where A is the amplitude of the intermediate frequency signal; f c >>B, T>>τ, B is the bandwidth, T is the duration of the continuous frequency modulation signal.

5. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 4 is characterized in that: In step 2, due to the influence of construction personnel and on-site equipment and devices during the actual measurement, the sampled data has multiple reflectors; assuming that in the i-th measurement, the sampled data has a total of M reflectors, and the reflected intermediate frequency signal is expressed as: In the formula, α i is the scanning measurement angle, the scanning measurement times i=1,2,……,N; A k , τ k are the reflected signal amplitude and the round-trip delay of the reflected signal of the kth reflector respectively.

6. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 5, characterized in that: In step 2, the frequency matrix construction process is as follows: The intermediate frequency signal is digitized into a discrete random signal with L data points. Then Perform Fourier transform and get the transformation result For the original signal The real power spectrum The estimates are as follows: Since the number of reflectors M is unknown, take The first five peak frequencies are m={1,2,3,4,5}, i is the i-th measurement, and an N×5 frequency matrix Ψ is constructed from it, and the matrix Ψ is reconstructed into a 5N×1 column frequency vector Ψ'; Get the maximum value f in the frequency vector max and the minimum value f min , f max =max(Ψ'),f min =min(Ψ') And the maximum value f max and the minimum value f min For the upper and lower limits, make a histogram with N bins. The histogram quantity vector is expressed as And construct the indicator vector Γ as follows: Γ=[a1,a2,…,a N ] T ,a i =1,ifφ i ≠0;or a i =0 The connectivity is determined by the distribution of elements 0 and 1 in the indicator vector Γ. Assume that the connected regions of the histogram are divided into two sets Γ1 and Γ2, which are expressed as: Γ1={a i ,a i+1 ,…,a n } Γ2={a j ,a j+1 ,…,a k } Among them, n+1 represents the number of elements in the Γ1 set, and the corresponding subscripts are i, i+1, ..., n; k+1 represents the number of elements in the Γ2 set, and the corresponding subscripts are j, j+1, ..., k; Get its main frequency distribution interval, the histogram quantity vector and corresponding to the set Γ1 and Γ2 are expressed as: Pick The corresponding set is the main frequency distribution area Γ', which is the reflection from the tunnel lining surface, and the others are noise signals reflected by construction personnel and on-site machinery and equipment. The matrix elements corresponding to the noise frequencies of construction personnel and on-site machinery and equipment are set to 0, and the frequency matrix Ψ is updated to Ψ":

7. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 6, characterized in that: In step 3, the non-zero value elements in the frequency domain matrix Ψ" are defined as frequency nodes, and the non-zero elements in the first row vector of the frequency matrix Ψ" are As the starting point, frequency tracking is performed; let the current frequency node be represents the frequency node in the i-th row and m-th column, then and the row vector element of row i+1 The frequency domain distance d p (i,i+1) is expressed as: And add the corresponding node is the frequency domain node vector of the starting node And construct the distance vector d p : d p =[d p (1,2),…,d p (i,i+1),…d p (N-1,N)] T The corresponding frequency domain tracking matrix df and the corresponding distance matrix d can be obtained.

8. The method for measuring tunnel structure deformation based on millimeter wave radar according to claim 7, characterized in that: In step 4, the tracking frequency corresponding to the minimum value of the column vector in the distance matrix is ​​taken as the tunnel section clearance frequency df p , and according to the formula between tunnel clearance frequency and distance: Among them, R i is the clearance measurement distance of the ith tunnel, c is the speed of light, df i p is the ith tunnel clearance frequency, S is the signal frequency modulation slope set by the device; Tunnel clearance measurement distance R i With scanning measurement angle α i Together constitute (R i ,α i ) polar coordinate pairs, the tunnel section clearance can be drawn in space based on the obtained polar coordinate pairs.

Images