A method for analyzing the results of polymer grouting repair in areas of dam panel voids.

Abstract

A method for analyzing the results of polymer grouting repair in areas with voids in embankment panels includes the following steps: using ground-penetrating radar (GPR) to detect the embankment and acquire detection data; processing the detection data to obtain information on the location of voids in the embankment panels; establishing a GPR electromagnetic wave calculation model for polymer grouting repair under different repair levels based on the location information of the voids in the embankment panels; obtaining a database of forward-modeled images and single-channel images of the embankment repaired with polymer grouting under the corresponding repair levels through the calculation model; detecting the location of voids in the embankment panels during the polymer grouting repair process using GPR and acquiring GPR data; comparing the GPR detection data of the embankment after polymer repair with the database; and analyzing the polymer repair results of the embankment panel voids based on the amplitude and transmission time interval of the GPR profile before and after the repair, as well as the reflection amplitude, transmission time interval, and reflection morphology data in the single-channel waveform images.

Description

Technical Field

[0001] This invention belongs to the field of non-destructive testing technology for dams, specifically relating to a method for analyzing the results of polymer grouting repair in areas of voids in dam panels based on ground-penetrating radar. Background Technology

[0002] Dikes are common components of water conservancy projects, playing a vital role in flood prevention and water retention, and are an important part of water conservancy projects. After long-term use, coupled with natural disasters and improper maintenance, dikes have gradually developed shallow hidden defects such as panel delamination, seriously threatening the safety of the dikes and the lives and property of people downstream.

[0003] After the concrete panel is poured, the dam fill will settle under its own weight and hydrostatic pressure, causing the compression sidewalls to deform downwards. Because the rigid concrete panel and the dam fill (compression sidewalls) deform inconsistently, the concrete panel may no longer be in close contact with the compression sidewalls in certain areas, resulting in voids. This localized voiding is extremely detrimental to the stress distribution of the concrete panel. When large-scale voiding occurs at the bottom of the panel, the overall stress distribution changes, complicating the situation. The concrete dam surface, lacking the tight support of the compression sidewalls, will sink. If the sinking deflection is excessive, the concrete panel is prone to developing through-cracks, reducing its seepage prevention function and posing a significant threat to the safe use of the reservoir dam. Voiding of concrete panels has become one of the most common defects in concrete-faced rockfill dams. As the first line of defense against water erosion in reservoir dams, regular inspection of voiding areas and thicknesses and timely and effective treatment of voiding areas are among the urgent problems to be solved in concrete-faced rockfill dams.

[0004] The traditional repair method for concrete panel voids involves chiseling away the broken panels, filling the voided areas, and then recasting the panels. This method is inefficient, costly, and the bonding between the recast panels and the old panels is uncertain. With the development of grouting technology, cement, fly ash, and polymers are commonly used to repair voids in concrete panels. However, using cement-fly ash stabilized grout, a mixture of cement and fly ash, has drawbacks such as large grouting holes, damage to panel integrity, difficulty in controlling grouting pressure, poor grout fluidity, the need for curing time, and grout shrinkage. When the voids are large, cement-fly ash grouting may still result in significant deformation later. Polymer grouting, as a novel repair technology, offers advantages such as minimal disturbance to dams, earthquake and crack resistance, strong ability to coordinate deformation with the soil, low cost, and no water pollution. It has been applied to the repair of voids in dam panels. However, there is still a lack of in-depth research on the evaluation method of polymer grouting effect for dam panel voids. Summary of the Invention

[0005] The purpose of this invention is to provide a highly reliable and practical method for analyzing the results of polymer grouting repair in areas of voids in dam panels based on ground-penetrating radar.

[0006] A method for analyzing the results of polymer grouting repair in areas of voids in dam panels includes the following steps:

[0007] Step 1: Process the profile image obtained by ground-penetrating radar of the dam to obtain the location information of the void defect area of ​​the dam panel;

[0008] Step 2: Based on the location information of the voided area of ​​the dam panel obtained in Step 1, establish a ground-penetrating radar electromagnetic wave calculation model for polymer grouting repair under different repair levels based on the finite difference method and the PML boundary conditions of the fully matched layer.

[0009] Step 3: Using the computational model established in Step 2, numerical simulations were performed on the panel void defect area to obtain forward modeling images and single-channel wave image databases of the dam repaired by polymer grouting under the corresponding repair level;

[0010] Step 4: Use ground-penetrating radar again to detect the location of the voided area of ​​the dam panel during the polymer grouting repair process, and obtain ground-penetrating radar profile and corresponding data, single-channel waveform and corresponding data;

[0011] Step 5: Compare the ground-penetrating radar data of the dam after polymer repair with the database from Step 3 to evaluate the polymer repair effect on the voided areas of the dam panel.

[0012] Furthermore, in the method for analyzing the results of polymer grouting repair in areas of voided dam panels, the step 1 of acquiring the location information of voided dam panel areas using ground-penetrating radar includes: collecting data of the dam panel to be inspected, including panel thickness and detection depth; and calculating the antenna detection parameters of the ground-penetrating radar based on the above data; the antenna detection parameters include the antenna center frequency f and the distance between measuring points n. x Horizontal resolution d h The vertical resolution Δh was then used to detect the dam. Subsequently, the CrossPoint processing method was used to process the detection data for time zero-point, filtering, gain, and offset imaging to remove noise, clutter, and the influence of multiple waves in the direct wave and the original signal, highlighting the abnormal locations in the radar profile. Based on the amplitude and waveform abrupt change locations in the ground penetrating radar profile, the panel void defect area was determined, and the void defect area was identified and marked.

[0013] The selection of ground-penetrating radar antenna detection parameters follows the formula below:

[0014] Antenna center frequency

[0015] In the formula, x represents the spatial relative resolution, in meters; ε r is the relative permittivity; f is the antenna center frequency, in MHz;

[0016] The spacing between measurement points is determined by the antenna center frequency and the electromagnetic properties of the propagation medium at discrete points; the arrangement of measurement point spacing should conform to Nyquist's law, i.e., the formula is...

[0017]

[0018] In the formula, λ is the wavelength of the Ricker wavelet in the propagation medium. It is obtained from the dielectric properties of the medium; v is the propagation speed of electromagnetic waves in the devitrified medium;

[0019] The horizontal resolution is:

[0020] In the formula, c is the speed of light, f is the center frequency of the antenna, h is the burial depth of the target, and ε is the velocity of light. r It is the relative permittivity;

[0021] The vertical resolution is:

[0022] In the formula B eff It refers to the effective bandwidth of the electromagnetic wave signal spectrum received by the receiving antenna;

[0023] Based on the reflection amplitude and abrupt changes in the electromagnetic wave waveform during electromagnetic wave propagation in the ground-penetrating radar profile, the horizontal length 'a' of the voided area can be calculated as: a = n x ×(b2-b1)(5)

[0024] The measurement points are numbered starting from the location where the ground penetrating radar begins to measure. In the formula, the numbers b1 and b2 represent the starting and ending measurement point numbers where the electromagnetic wave waveform changes abruptly, respectively.

[0025] The height between the upper and lower interfaces of the panel delamination area:

[0026] In the formula: v is the propagation speed of electromagnetic waves in the void diseased medium, and Δt0 is the propagation time of electromagnetic waves propagating in the vertical direction between the upper and lower horizontal interfaces of the void diseased area.

[0027] Electromagnetic propagation speed in a medium:

[0028] In the formula: c is the speed of electromagnetic wave propagation in air, which is 0.30 m / ns; ε r is the relative permittivity of the medium.

[0029] Furthermore, the method for analyzing the results of polymer grouting repair in the voided area of ​​the dam panel, wherein step 2 is as follows: based on the ground-penetrating radar profile of the voided area of ​​the dam panel obtained in step 1, based on the waveform abrupt change and amplitude increase in the profile, the range values ​​of the horizontal x direction and the range values ​​of the vertical y direction of the voided area of ​​the panel are obtained, and the shape of the voided area of ​​the panel is determined.

[0030] Based on the changes in image amplitude in the ground-penetrating radar profile, the distribution of each medium layer is obtained, according to the data acquisition parameters: antenna center frequency f, sampling time window w, and measurement point spacing n. x Horizontal resolution d h The numerical dispersion conditions of the relative permittivity μ, conductivity σ, permeability μ0, and stability conditions of the solution of the finite-difference time-domain method were determined by the vertical resolution Δh and the properties of each layer of medium: relative permittivity μ, conductivity σ, permeability μ0, and stability conditions of the solution of the finite-difference time-domain method. The distribution of each layer of medium was determined by the gprmax method. Based on the finite-difference method and the boundary conditions of the perfectly matched layer PML, a ground-penetrating radar electromagnetic wave calculation model for polymer grouting repair under different repair degrees was established.

[0031] The sampling window refers to the maximum value of the sampling time range for electromagnetic reflection signals by the radar system; the sampling window directly determines the detection depth, and is calculated using the following formula:

[0032]

[0033] In the formula: w is the sampling time window, in ns; hmax ν represents the maximum depth detected by radar, in meters (m); v represents the wave speed of electromagnetic waves in the medium, in m / ns.

[0034] In the stability condition of the finite-difference time-domain (FDTD) method solution, the relationship between the time step Δt of the TM wave and the spatial steps Δx and Δy in the x-axis and y-axis directions must satisfy:

[0035]

[0036] To reduce numerical dispersion caused by the difference approximation, the time step Δt and the spatial steps Δx and Δy satisfy the following relationship:

[0037]

[0038] In the formula, λ is the minimum wavelength during electromagnetic wave propagation, and T is the period of the electromagnetic wave signal.

[0039] To simulate the propagation of ground-penetrating radar (GPR) electromagnetic waves within a dam, a Yee grid was used to establish a GPR electromagnetic wave computational model. Let f(x,y,t) represent the current component of the electric field E or magnetic field H in a rectangular coordinate system. The model region was divided into grids, with x, y, and t corresponding to i, j, and n components, respectively: x = iΔx, y = jΔy, t = nΔt. The discretization in the time and spatial domains is represented by the following symbols:

[0040]

[0041] In the formula This is a shorthand for f(iΔx,jΔy,nΔt), which will be discussed later. and These represent the current components of the electric field E and the magnetic field H in the rectangular coordinate system, respectively.

[0042] The Finite-Difference Time-Domain (FDTD) method selects radar electromagnetic waves propagating in the TM mode on the x, y plane. In the two-dimensional case, the finite-difference form of Maxwell's equations is:

[0043]

[0044]

[0045]

[0046] In the formula: ε0 is the initial permittivity; μ0 is the initial permeability; σ is the conductivity; Δt is time; Δd ​​is the spatial step size; σ (i,j) ,ε (i,j) These are the conductivity and dielectric constant for spatial position (i, j) in the Yee cell set, respectively. Let be the electric field value of the z-component of the electric field located at position (i, j) in the Yee cell set, propagating to time n+1; Let z be the electric field value of the z component of the electric field located at position (i, j) in the Yee cell set, propagating to time n; Let z be the electric field value of the z component of the electric field located at position (i, j+1) in the Yee cell set, propagating to time n; Let z be the electric field value of the z component of the electric field located at position (i+1, j) in the Yee cell group, propagating to time n; Let be the magnetic field value of the x component of the magnetic field located at position (i, j+1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let be the magnetic field value of the x component of the magnetic field located at position (i, j-1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the magnetic field component located at position (i, j+1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the magnetic field component located at position (i+1 / 2, j) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the y component of the magnetic field located at position (i-1 / 2, j) in the Yee cell set, propagating to time n+1 / 2;

[0047] The perfectly matched layer PML absorbing boundary is achieved by placing a special non-physical absorbing medium layer at the boundary, preventing the incident wave from being reflected and allowing it to directly enter the medium through the interface; in the case of a two-dimensional TM wave, its FDTD differential scheme in the PML layer is as follows:

[0048]

[0049]

[0050]

[0051]

[0052] In the formula: ε is the permittivity; μ0 is the initial permeability; σ x ,σ y Let x and y represent the conductivity in the x and y directions, respectively. E represents the equivalent magnetoresistive force in the x and y directions, respectively. zx E zy For E z Two subcomponents;

[0053] It is the electric field value of the x-direction sub-component of the z-component of the electric field at position (i, j) in the Yee cell group, propagated to time n+1; It is the electric field value of the y-direction sub-component of the z-component of the electric field at position (i, j) in the Yee cell group, propagated to time n+1.

[0054] These are the magnetic field values ​​of the x and y components of the magnetic field propagating from position (i+1 / 2, j) in the Yee cell set to time n+1 / 2. It is the magnetic field value of the x component of the magnetic field propagating from position (i+1 / 2, j) in the Yee cell set to time n; It is the magnetic field value of the partial derivative of the y component of the magnetic field with respect to x at position (i, j) in the Yee cell set up to time n+1 / 2. It is the magnetic field value of the partial derivative of the magnetic field x component with respect to y when it propagates from position (i, j) in the Yee cell set to time n+1 / 2; It is the electric field value of the z-component of the electric field at position (i+1 / 2, j) in the Yee cell set, propagating to time n with respect to x; This is the electric field value of the z-component of the electric field at position (i+1 / 2, j) in the Yee cell set, propagating to time n with respect to the y-partial derivative. Using an exponential time variable to expand the two-dimensional Maxwell equations, the general solution of the x-direction subcomponent of the electric field z-component is obtained as follows: The value after one time step is Therefore and These are the general solution iteration coefficients for the x-direction subcomponent of the electric field z-component, the y-direction subcomponent of the electric field z-component, the x-component of the magnetic field, and the y-component of the magnetic field, respectively, after one time step.

[0055] Furthermore, in the method for analyzing the results of polymer grouting repair in the voided area of ​​the dam panel, step 3 involves using the computational model established in step 2 to perform numerical simulation on the voided area of ​​the panel, thereby obtaining forward modeling images and single-channel wave image databases of the dam under different repair levels.

[0056] Furthermore, in the method for analyzing the results of polymer grouting repair in the voided area of ​​the dam panel, step 5 involves comparing the ground-penetrating radar images of the voided area of ​​the dam panel during and after the repair process with the database in step 3. The analysis includes examining the shape of the image curves, number of clusters, curvature, amplitude, and time intervals in the ground-penetrating radar profile images before and after repair, as well as the number of reflected waves, amplitude, and time intervals between reflected waves in the single-channel wave pattern. Based on the data differences between the ground-penetrating radar profile images and the single-channel wave pattern before and after repair, the repair effect of the shallow defects of the dam is evaluated.

[0057] Furthermore, the method for analyzing the results of polymer grouting repair in the voided area of ​​the dam panel includes a ground-penetrating radar profile image before repair showing obvious amplitude abrupt changes and fault phenomena at the location of the voided area. Unlike the surrounding medium, the image exhibits two distinct abrupt change curves, resulting in two clusters of curves. The times corresponding to the tops of these curves represent the time it takes for the ground-penetrating radar to reach the upper and lower interfaces of the voided area. Based on the transmission time interval Δt0 between the upper and lower interfaces, the height h0 between the upper and lower interfaces of the voided area can be inferred. Electromagnetic waves, in the form of short pulses, are incident from the ground to the ground. When encountering interfaces with electrical differences, the electromagnetic waves generate reflected waves. The time required for the reflected waves to return to the ground is:

[0058]

[0059] In the formula: H f denoted as the depth of the reflecting interface; v is the electromagnetic propagation speed in the medium.

[0060] Furthermore, the method for analyzing the results of polymer grouting repair in the voided area of ​​the dam panel involves ground-penetrating radar (GPR) profiles during the repair process showing significant amplitude abrupt changes and fault phenomena at the location of the voided area. These abrupt changes differ from the characteristics of the surrounding medium, resulting in three distinct abrupt change curves in the image. These curves represent three clusters: the upper and lower interfaces of the voided area and the interface between the polymer and the filling medium. The time of generation of the tops of these three clusters of curves differs depending on the degree of repair, and the time intervals between the curves are also different. When the GPR electromagnetic wave passes through the voided area, three distinct reflected waves appear sequentially in the single-channel waveform diagram from entry to exit. The first and third reflected waves exhibit an inverse relationship, and the time interval between the first and second reflected waves differs from that between the second and third reflected waves. The distribution of the filling medium and polymer within the voided depth range can be inferred from the time intervals of the reflected waves, thus allowing for the estimation of the polymer repair status.

[0061] Furthermore, in the method for analyzing the results of polymer grouting repair in the voided area of ​​the dam panel, the ground-penetrating radar profile after complete repair of the voided area of ​​the dam panel shows two clusters of curves. The amplitude at the top of the two clusters of curves is smaller than the amplitude before repair, and the time interval between the two clusters of curves is smaller than the time interval between the two curves before repair.

[0062] This invention provides a method for analyzing the results of polymer grouting repair in areas of voided dam panels. When creating cross-sectional and single-wave patterns of voided dam panels before and after polymer grouting repair, the method effectively interprets the degree of polymer grouting repair based on data such as the number of curve clusters, peak amplitude, and wave propagation time interval in the cross-sectional pattern, as well as the number of reflected waves, reflected wave amplitude, and time interval in the single-wave pattern. Therefore, ground-penetrating radar can be used to effectively evaluate the effect of polymer grouting repair in voided dam panels. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0064] Figure 2 This is a schematic diagram of the forward modeling of dam panel voids before and after polymer repair using the method of the present invention;

[0065] Figure 3 This is a forward modeling cross-section of the dam panel voids before and after polymer repair using the method of this invention.

[0066] Figure 4 This is a schematic diagram of the single-channel waveform of the dam panel voids before and after the polymer repair method of the present invention. Detailed Implementation

[0067] This invention provides a method for analyzing the results of polymer grouting repair in areas of voids in dam panels, such as... Figure 1 As shown, the steps include:

[0068] Step 1: Process the profile image obtained by ground-penetrating radar of the dam to obtain the location information of the dam panel void;

[0069] Step 2: Based on the location information of the voided area of ​​the dam panel obtained in Step 1, establish a ground-penetrating radar electromagnetic wave calculation model for polymer grouting repair under different repair levels (corresponding to various repair levels) based on the finite difference method and the PML boundary conditions of the fully matched layer.

[0070] Step 3: Using the computational model established in Step 2, numerical simulations were performed on the panel void defect area to obtain forward modeling images and single-channel wave image databases of the dam repaired by polymer grouting under the corresponding repair level;

[0071] Step 4: Use ground-penetrating radar again to detect the location of the voided area of ​​the dam panel during the polymer grouting repair process, and obtain ground-penetrating radar profile and corresponding data, single-channel waveform and corresponding data;

[0072] Step 5: Compare the ground-penetrating radar data of the dam after polymer repair with the database from Step 3 to evaluate the polymer repair effect on the voids in the dam panel.

[0073] Step 1, which involves using ground-penetrating radar to acquire location information of areas with voids in the embankment panel, includes: collecting data on the embankment panel to be inspected, including panel thickness and detection depth; and calculating the antenna detection parameters of the ground-penetrating radar based on the data. The antenna detection parameters include the antenna center frequency f and the distance between measurement points n. x Horizontal resolution d h The vertical resolution Δh was then used to detect the dam. Subsequently, the CrossPoint processing method was used to process the detection data for time zero-point, filtering, gain, and offset imaging to remove noise, clutter, and the influence of multiple waves in the direct wave and the original signal, highlighting the abnormal locations in the radar profile. Based on the amplitude and waveform abrupt change locations in the ground penetrating radar profile, the panel void defect area was determined, and the void defect area was identified and marked.

[0074] The selection of ground-penetrating radar antenna detection parameters follows the formula below:

[0075] Antenna center frequency

[0076] In the formula, x represents the spatial relative resolution, in meters; ε r is the relative permittivity; f is the antenna center frequency, in MHz;

[0077] The spacing between measurement points is determined by the antenna center frequency and the electromagnetic properties of the propagation medium at discrete points; the arrangement of measurement point spacing should conform to Nyquist's law, i.e., the formula is...

[0078]

[0079] In the formula, λ is the wavelength of the Ricker wavelet in the propagation medium. It is obtained from the dielectric properties of the medium; v is the propagation speed of electromagnetic waves in the devitrified medium;

[0080] The horizontal resolution is:

[0081] In the formula, c is the speed of light, f is the center frequency of the antenna, h is the burial depth of the target, and ε is the velocity of light. r It is the relative permittivity;

[0082] The vertical resolution is:

[0083] In the formula B eff It refers to the effective bandwidth of the electromagnetic wave signal spectrum received by the receiving antenna;

[0084] Based on the reflection amplitude and abrupt changes in the electromagnetic wave waveform during electromagnetic wave propagation in the ground-penetrating radar profile, the horizontal length 'a' of the voided area can be calculated as: a = n x ×(b2-b1) (twenty four)

[0086] The measurement points are numbered starting from the location where the ground penetrating radar begins to measure. In the formula, the numbers b1 and b2 represent the starting and ending measurement point numbers where the electromagnetic wave waveform changes abruptly, respectively.

[0087] The height between the upper and lower interfaces of the panel delamination area:

[0088] In the formula: v is the propagation speed of electromagnetic waves in the void diseased medium, and Δt0 is the propagation time of electromagnetic waves propagating in the vertical direction between the upper and lower horizontal interfaces of the void diseased area.

[0089] Electromagnetic propagation speed in a medium:

[0090] In the formula: c is the speed of electromagnetic wave propagation in air, which is 0.30 m / ns; ε r is the relative permittivity of the medium.

[0091] Step 2 describes the following: Based on the ground-penetrating radar profile of the dam panel detachment obtained in Step 1, the range values ​​of the horizontal x-direction and the vertical y-direction of the panel detachment disease area are obtained based on the waveform abrupt change and amplitude increase in the profile, and the shape of the panel detachment disease area is determined.

[0092] Based on the changes in image amplitude in the ground-penetrating radar profile, the distribution of each medium layer is obtained, according to the data acquisition parameters: antenna center frequency f, sampling time window w, and measurement point spacing n. x Horizontal resolution d h The numerical dispersion conditions, along with the vertical resolution Δh and the properties of each layer of the medium (relative permittivity μ, conductivity σ, permeability μ0) and the stability conditions of the finite-difference time-domain solution, are used to determine the distribution of each layer of the medium using the gprmax method. Based on the finite-difference method and the PML boundary conditions of the perfectly matched layers, a ground-penetrating radar electromagnetic wave calculation model for polymer grouting repair under different repair levels is established. The gprmax method described here is processed using the gprmax software.

[0093] The sampling window refers to the maximum value of the sampling time range for electromagnetic reflection signals by the radar system; the sampling window directly determines the detection depth, and is calculated using the following formula:

[0094]

[0095] In the formula: w is the sampling time window, in ns; hmax ν represents the maximum depth detected by radar, in meters (m); v represents the wave speed of electromagnetic waves in the medium, in m / ns.

[0096] In the stability condition of the finite-difference time-domain (FDTD) method solution, the relationship between the time step Δt of the TM wave and the spatial steps Δx and Δy in the x-axis and y-axis directions must satisfy:

[0097]

[0098] To reduce numerical dispersion caused by the difference approximation, the time step Δt and the spatial steps Δx and Δy satisfy the following relationship:

[0099]

[0100] In the formula, λ is the minimum wavelength during electromagnetic wave propagation, and T is the period of the electromagnetic wave signal.

[0101] To simulate the propagation of ground-penetrating radar (GPR) electromagnetic waves within a dam, a Yee grid was used to establish a GPR electromagnetic wave computational model. Let f(x,y,t) represent the current component of the electric field E or magnetic field H in a rectangular coordinate system. The model region was divided into grids, with x, y, and t corresponding to i, j, and n components, respectively: x = iΔx, y = jΔy, t = nΔt. The discretization in the time and spatial domains is represented by the following symbols:

[0102]

[0103] In the formula This is a shorthand for f(iΔx,jΔy,nΔt), which will be discussed later. and These represent the current components of the electric field E and the magnetic field H in the rectangular coordinate system, respectively.

[0104] The Finite-Difference Time-Domain (FDTD) method selects radar electromagnetic waves propagating in the TM mode on the x, y plane. In the two-dimensional case, the finite-difference form of Maxwell's equations is:

[0105]

[0106]

[0107]

[0108] In the formula: ε0 is the initial permittivity; μ0 is the initial permeability; σ is the conductivity; Δt is time; Δd ​​is the spatial step size; σ (i,j) ,ε (i,j) These are the conductivity and dielectric constant for spatial position (i, j) in the Yee cell set, respectively. Let be the electric field value of the z-component of the electric field located at position (i, j) in the Yee cell set, propagating to time n+1; Let z be the electric field value of the z component of the electric field located at position (i, j) in the Yee cell set, propagating to time n; Let z be the electric field value of the z component of the electric field located at position (i, j+1) in the Yee cell set, propagating to time n; Let z be the electric field value of the z component of the electric field located at position (i+1, j) in the Yee cell group, propagating to time n; Let be the magnetic field value of the x component of the magnetic field located at position (i, j+1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let be the magnetic field value of the x component of the magnetic field located at position (i, j-1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the magnetic field component located at position (i, j+1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the magnetic field component located at position (i+1 / 2, j) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the y component of the magnetic field located at position (i-1 / 2, j) in the Yee cell set, propagating to time n+1 / 2;

[0109] The perfectly matched layer PML absorbing boundary is achieved by placing a special non-physical absorbing medium layer at the boundary, preventing the incident wave from being reflected and allowing it to directly enter the medium through the interface; in the case of a two-dimensional TM wave, its FDTD differential scheme in the PML layer is as follows:

[0110]

[0111]

[0112]

[0113]

[0114] In the formula: ε is the permittivity; μ0 is the initial permeability; σ x ,σ y Let x and y represent the conductivity in the x and y directions, respectively. E represents the equivalent magnetoresistive force in the x and y directions, respectively. zx E zy For E z Two subcomponents;

[0115] It is the electric field value of the x-direction sub-component of the z-component of the electric field at position (i, j) in the Yee cell group, propagated to time n+1; It is the electric field value of the y-direction sub-component of the z-component of the electric field at position (i, j) in the Yee cell group, propagated to time n+1.

[0116] These are the magnetic field values ​​of the x and y components of the magnetic field propagating from position (i+1 / 2, j) in the Yee cell set to time n+1 / 2. It is the magnetic field value of the x component of the magnetic field propagating from position (i+1 / 2, j) in the Yee cell set to time n; It is the magnetic field value of the partial derivative of the y component of the magnetic field with respect to x at position (i, j) in the Yee cell set up to time n+1 / 2. It is the magnetic field value of the partial derivative of the magnetic field x component with respect to y when it propagates from position (i, j) in the Yee cell set to time n+1 / 2; It is the electric field value of the z-component of the electric field at position (i+1 / 2, j) in the Yee cell set, propagating to time n with respect to x; This is the electric field value of the z-component of the electric field at position (i+1 / 2, j) in the Yee cell set, propagating to time n with respect to the y-partial derivative. Using an exponential time variable to expand the two-dimensional Maxwell equations, the general solution of the x-direction subcomponent of the electric field z-component is obtained as follows: The value after one time step is Therefore and These are the general solution iteration coefficients for the x-direction subcomponent of the electric field z-component, the y-direction subcomponent of the electric field z-component, the x-component of the magnetic field, and the y-component of the magnetic field, respectively, after one time step.

[0117] In step 3, the computational model established in step 2 is used to perform numerical simulation on the panel void defect area to obtain forward modeling images and single-channel wave image databases of the dam repaired by polymer grouting under the corresponding repair level.

[0118] In step 5, the ground-penetrating radar images of the dam panel void defect area during and after the repair process are compared with the database in step 3. The shape of the image curves, number of clusters, curvature, amplitude, and time interval in the ground-penetrating radar profile images before and after the repair of the panel void defect area are analyzed, as well as the number of reflected waves, amplitude, and time interval between reflected waves in the single-channel wave pattern. Based on the data differences between the ground-penetrating radar profile images and single-channel wave patterns before and after the repair, the repair effect of the shallow defects of the dam is evaluated.

[0119] In one scenario: Before the repair of the voided area of ​​the dam panel, the ground-penetrating radar profile shows obvious amplitude abrupt changes and fault phenomena at the location of the defect. Unlike the characteristics of the surrounding medium, there are two distinct abrupt change curves in the image. At this time, the image presents two clusters of curves. The time corresponding to the top of the curves is the time when the ground-penetrating radar reaches the upper and lower interfaces of the voided area. Based on the transmission time interval Δt0 between the upper and lower interfaces, the height h0 between the upper and lower interfaces of the voided area of ​​the panel can be inferred.

[0120] Electromagnetic waves are incident from the ground into the ground in the form of short pulses. When they encounter an interface with a difference in electrical charge, the electromagnetic waves are reflected. The time required for the waves to reflect back to the ground is:

[0121] In the formula: H f denoted as the depth of the reflecting interface; v is the electromagnetic propagation speed in the medium.

[0122] In another scenario, during the repair process of voided areas in the dam panel, the ground-penetrating radar profile shows obvious amplitude abrupt changes and fault phenomena at the location of the void. Unlike the surrounding medium, the image clearly shows three distinct abrupt change curves, forming three clusters of curves. These clusters represent the upper and lower interfaces of the void and the interface between the polymer and the filling medium. The time of generation of the tops of the three clusters of curves differs depending on the degree of repair, and the time intervals between the curves are also different. When the ground-penetrating radar electromagnetic wave passes through the voided area, three distinct reflected waves appear sequentially in the single-channel waveform diagram from entry to exit. Following the chronological order, the first and third reflected waves exhibit opposite phenomena, and the time interval between the first and second reflected waves differs from that between the second and third reflected waves. Based on the time intervals of the reflected waves, the distribution of the filling medium and polymer within the void depth range can be inferred, thus estimating the polymer repair status.

[0123] In another scenario, the ground-penetrating radar profile after complete repair of the voided area on the dam panel shows two clusters of curves. The amplitude at the top of the two clusters of curves is smaller than the amplitude before repair, and the time interval between the two clusters of curves is smaller than the time interval between the two curves before repair.

[0124] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments.

[0125] As a preferred embodiment of the above, such as Figure 2 As shown, the dam panel delamination defect was established before repair ( Figure 2 (as shown in part a), 50% repair ( Figure 2 (as shown in part b) and complete repair ( Figure 2The model shown in section c) indicates the medium distribution and void locations. Ground penetrating radar (GPR) is used to detect the model and obtain GPR data.

[0126] As a preferred embodiment of the above, such as Figure 3 As shown, the defects of the dam panel before repair were obtained. Figure 3 (as shown in part a), 50% repair ( Figure 3 (as shown in part b) and after complete repair ( Figure 3 The ground-penetrating radar profile shown in section c) is as follows. Figure 3 As shown in section a, the ground-penetrating radar profile of the dam panel before repair of the void defect area presents two clusters of curves, representing the upper and lower interfaces of the void defect. The height of the void defect can be inferred from the time interval between the transmission between the upper and lower interfaces. Figure 3 As shown in section b, the ground-penetrating radar profile during the repair process of the voided area of ​​the dam panel presents three clusters of curves, representing the upper and lower interfaces of the voided area and the interface between the polymer and the filling medium. The time of generation of the tops of the three clusters of curves differs under different repair levels, and the time interval between the curves also varies; for example... Figure 3 As shown in section c, the ground-penetrating radar profile of the dam panel after complete repair of the voided area shows two clusters of curves, with the amplitude at the top of the curves and the time interval between curve transmissions being smaller than before the repair.

[0127] As a preferred embodiment of the above, such as Figure 4 As shown, the defects of the dam panel before repair were obtained. Figure 4 (as shown in part a), 50% repair ( Figure 4 (as shown in part b) and after complete repair ( Figure 4 The single-channel waveform diagrams (shown in section c) are shown below. The left side of each diagram represents the overall single-channel waveform, while the right side shows a magnified view of a local area. Both the pre-repair and fully repaired single-channel waveforms show two reflected waves. The amplitude of the reflected waves and the time interval between their propagation are greater before repair than after full repair. Furthermore, the first reflected wave before repair exhibits a reverse polarity. The single-channel waveform diagram with 50% repair shows three reflected waves, with the first and third reflected waves exhibiting a reverse polarity.

[0128] As a preferred embodiment of the above, the method for judging the polymer repair effect in step 5 of the dam panel void disease is as follows: if the ground-penetrating radar profile obtained during the repair process shows three clusters of curves with large peak amplitudes, then the dam panel void disease has not been completely repaired and polymer repair needs to continue. The polymer repair effect of the dam panel void disease can be judged based on the transmission time interval between the curves. If the ground-penetrating radar profile obtained during the repair process shows two clusters of curves with large peak amplitudes, and the transmission time interval between the curves is less than the peak amplitude of the curves in the ground-penetrating radar profile of the dam panel void disease, then the dam panel void disease has been completely repaired.

[0129] As a preferred embodiment of the above, the method for judging the polymer repair effect in the dam panel void defect in step 5 is as follows: if there are three reflected waves in the ground penetrating radar single-channel waveform obtained during the repair process, the dam panel void defect has not been completely repaired; if there are two reflected waves in the ground penetrating radar single-channel waveform obtained during the repair process, and the peak amplitude and the time interval between the two reflected waves are less than before the repair, the dam panel void defect has been completely repaired.

[0130] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

[0131] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for analyzing the results of polymer grouting repair in areas of voids in dam panels, characterized in that: Includes the following steps: Step 1: Process the cross-sectional image obtained from the ground-penetrating radar (GPR) of the dam to obtain the location information of the dam panel void. This step includes: collecting data on the dam panel to be inspected, including panel thickness and detection depth; and calculating the GPR antenna detection parameters based on this data. The antenna detection parameters include the antenna center frequency f and the distance between measurement points n. x Horizontal resolution d h The vertical resolution Δh was then used to detect the dam. Subsequently, the CrossPoint processing method was used to process the detection data for time zero-point, filtering, gain, and offset imaging to remove noise, clutter, and the influence of multiple waves in the direct wave and the original signal, highlighting the abnormal locations in the radar profile. Based on the amplitude and waveform abrupt change locations in the ground penetrating radar profile, the panel void defect area was determined, and the void defect area was identified and marked. The selection of ground-penetrating radar antenna detection parameters follows the formula below: Antenna center frequency In the formula, x represents the spatial relative resolution, in meters; ε r is the relative permittivity; f is the antenna center frequency, in MHz; The spacing between measurement points is determined by the antenna center frequency and the electromagnetic properties of the propagation medium at discrete points; the arrangement of measurement point spacing should conform to Nyquist's law, i.e., the formula is... In the formula, λ is the wavelength of the Ricker wavelet in the propagation medium. Obtained based on the dielectric properties of the medium; v is the propagation speed of electromagnetic waves in the devitrified medium; ε r is the relative permittivity of the medium; The horizontal resolution is: In the formula, c is the speed of light, f is the center frequency of the antenna, h is the burial depth of the target, and ε is the velocity of light. r is the relative permittivity of the medium; The vertical resolution is: In the formula B eff It refers to the effective bandwidth of the electromagnetic wave signal spectrum received by the receiving antenna; Based on the reflection amplitude and abrupt changes in the electromagnetic wave waveform during electromagnetic wave propagation in the ground-penetrating radar profile, the horizontal length 'a' of the voided area is calculated as: a = n x ×(b2-b1)(5) The measurement points are numbered starting from the location where the ground penetrating radar begins to measure. In the formula, the numbers b1 and b2 represent the starting and ending measurement point numbers where the electromagnetic wave waveform changes abruptly, respectively. The height between the upper and lower interfaces of the panel delamination area: In the formula: v is the propagation speed of electromagnetic waves in the void diseased medium, and Δt0 is the propagation time of electromagnetic waves propagating in the vertical direction between the upper and lower horizontal interfaces of the void diseased area. Electromagnetic propagation speed in a medium: In the formula: c is the speed of electromagnetic wave propagation in air, which is 0.30 m / ns; ε r is the relative permittivity of the medium; Step 2: Based on the ground-penetrating radar profile of the dam panel containing the void defect area obtained in Step 1, obtain the range values ​​of the horizontal x-direction and the vertical y-direction of the void defect area of ​​the panel based on the waveform abrupt change and amplitude increase in the profile, and determine the shape of the void defect of the panel. Based on the changes in image amplitude in the ground-penetrating radar profile, the distribution of each medium layer is obtained, according to the data acquisition parameters: antenna center frequency f, sampling time window w, and measurement point spacing n. x Horizontal resolution d h The numerical dispersion conditions of the relative permittivity μ, conductivity σ, permeability μ0, and stability conditions of the solution of the finite-difference time-domain method were determined by the vertical resolution Δh and the properties of each layer of medium: relative permittivity μ, conductivity σ, permeability μ0, and stability conditions of the solution of the finite-difference time-domain method. The distribution of each layer of medium was determined by the gprmax method. Based on the finite-difference method and the boundary conditions of the perfectly matched layer PML, a ground-penetrating radar electromagnetic wave calculation model for polymer grouting repair under different repair degrees was established. The sampling window refers to the maximum value of the sampling time range for electromagnetic reflection signals by the radar system; the sampling window directly determines the detection depth, and is calculated using the following formula: In the formula: w is the sampling time window, in ns; h max ν represents the maximum depth detected by radar, in meters (m); v represents the wave speed of electromagnetic waves in the medium, in m / ns. In the stability condition of the finite-difference time-domain (FDTD) method solution, the relationship between the time step Δt of the TM wave and the spatial steps Δx and Δy in the x-axis and y-axis directions must satisfy: To reduce numerical dispersion caused by the difference approximation, the time step Δt and the spatial steps Δx and Δy satisfy the following relationship: In the formula, λ is the minimum wavelength during the electromagnetic wave propagation process, and T is the period of the electromagnetic wave signal; To simulate the propagation of ground-penetrating radar (GPR) electromagnetic waves within a dam, a Yee grid was used to establish a GPR electromagnetic wave computational model. Let f(x,y,t) represent the current component of the electric field E or magnetic field H in a rectangular coordinate system. The model region was divided into grids, with x, y, and t corresponding to i, j, and n components, respectively: x = iΔx, y = jΔy, t = nΔt. The discretization in the time and spatial domains is represented by the following symbols: In the formula This is a shorthand for f(iΔx,jΔy,nΔt), which will be discussed later. and These represent the current components of the electric field E and the magnetic field H in the rectangular coordinate system, respectively. The Finite-Difference Time-Domain (FDTD) method selects radar electromagnetic waves propagating in the TM mode on the x, y plane. In the two-dimensional case, the finite-difference form of Maxwell's equations is: In the formula: ε0 is the initial permittivity; μ0 is the initial permeability; σ is the conductivity; Δt is time; Δd ​​is the spatial step size; σ (i,j) ,ε (i,j) These are the conductivity and dielectric constant for spatial position (i, j) in the Yee cell set, respectively. Let be the electric field value of the z-component of the electric field located at position (i, j) in the Yee cell set, propagating to time n+1; Let z be the electric field value of the z component of the electric field located at position (i, j) in the Yee cell set, propagating to time n; Let z be the electric field value of the z component of the electric field located at position (i, j+1) in the Yee cell set, propagating to time n; Let z be the electric field value of the z component of the electric field located at position (i+1, j) in the Yee cell group, propagating to time n; Let be the magnetic field value of the x component of the magnetic field located at position (i, j+1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let be the magnetic field value of the x component of the magnetic field located at position (i, j-1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the magnetic field component located at position (i, j+1 / 2) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the magnetic field component located at position (i+1 / 2, j) in the Yee cell set, propagating to time n+1 / 2; Let y be the magnetic field value of the y component of the magnetic field located at position (i-1 / 2, j) in the Yee cell set, propagating to time n+1 / 2; The perfectly matched layer PML absorbing boundary is achieved by placing a special non-physical absorbing medium layer at the boundary, preventing the incident wave from being reflected and allowing it to directly enter the medium through the interface; in the case of a two-dimensional TM wave, its FDTD differential scheme in the PML layer is as follows: In the formula: ε is the permittivity; μ0 is the initial permeability; σ x ,σ y Let x and y represent the conductivity in the x and y directions, respectively. E represents the equivalent magnetoresistive force in the x and y directions, respectively. zx E zy For E z Two subcomponents; It is the electric field value of the x-direction sub-component of the z-component of the electric field at position (i, j) in the Yee cell group, propagated to time n+1; It is the electric field value of the y-direction sub-component of the z-component of the electric field at position (i, j) in the Yee cell group, propagated to time n+1. These are the magnetic field values ​​of the x and y components of the magnetic field propagating from position (i+1 / 2, j) in the Yee cell set to time n+1 / 2. It is the magnetic field value of the x component of the magnetic field propagating from position (i+1 / 2, j) in the Yee cell set to time n; It is the magnetic field value of the partial derivative of the y component of the magnetic field with respect to x at position (i, j) in the Yee cell set up to time n+1 / 2. It is the magnetic field value of the partial derivative of the magnetic field x component with respect to y when it propagates from position (i, j) in the Yee cell set to time n+1 / 2; It is the electric field value of the z-component of the electric field at position (i+1 / 2, j) in the Yee cell set, propagating to time n with respect to x; This is the electric field value of the z-component of the electric field at position (i+1 / 2, j) in the Yee cell set, propagating to time n with respect to the y-partial derivative. Using an exponential time variable to expand the two-dimensional Maxwell equations, the general solution of the x-direction subcomponent of the electric field z-component is obtained as follows: The value after one time step is Therefore and These are the general solution iteration coefficients after one time step for the x-direction subcomponent of the z-component of the electric field, the y-direction subcomponent of the z-component of the electric field, the x-component of the magnetic field, and the y-component of the magnetic field; Step 3: Using the computational model established in Step 2, numerical simulations were performed on the panel void defect area to obtain forward modeling images and single-channel wave image databases of the dam repaired by polymer grouting under the corresponding repair level; Step 4: Use ground-penetrating radar again to detect the location of the voided area of ​​the dam panel during the polymer grouting repair process, and obtain ground-penetrating radar profile and corresponding data, single-channel waveform and corresponding data; Step 5: Compare the ground-penetrating radar images of the dam panel void defect area during and after the repair process with the database in Step 3. Analyze the image curve shape, cluster number, curvature, amplitude, and time interval in the ground-penetrating radar profile images before and after the repair of the panel void defect area, as well as the number of reflected waves, amplitude, and time interval between reflected waves in the single-channel wave pattern. Based on the data differences between the ground-penetrating radar profile images and single-channel wave patterns before and after the repair, evaluate the repair effect of the shallow defects of the dam.

2. The method for analyzing the results of polymer grouting repair in areas of voided dam panels according to claim 1, characterized in that: Before repair, the ground-penetrating radar profile of the dam panel delamination area showed obvious amplitude abrupt changes and discontinuities at the location of the delamination. Due to differences in characteristics with the surrounding medium, two distinct abrupt change curves were clearly visible in the image, resulting in two clusters of curves. The times corresponding to the tops of these curves represent the time it took for the ground-penetrating radar to reach the upper and lower interfaces of the delamination area. Based on the transmission time interval Δt0 between the upper and lower interfaces, the height h0 between the upper and lower interfaces of the panel delamination area can be inferred. Electromagnetic waves, in the form of short pulses, are incident from the ground to the ground. When encountering interfaces with electrical differences, the electromagnetic waves generate reflected waves. The time required for the reflected waves to return to the ground is: In the formula: H f denoted as the depth of the reflecting interface; v is the electromagnetic propagation speed in the medium.

3. The method for analyzing the results of polymer grouting repair in areas of voided dam panels according to claim 1, characterized in that: During the repair process of the voided area of ​​the dam panel, the ground-penetrating radar profile showed obvious amplitude abrupt changes and fault phenomena at the location of the voided area. Unlike the surrounding medium, the image clearly showed three different abrupt change curves, which presented three clusters of curves. These represented the upper and lower interfaces of the voided area and the interface between the polymer and the filling medium. The generation time of the top of the three clusters of curves was different for different repair levels, and the transmission time interval between the curves was also different. When the ground-penetrating radar electromagnetic wave passed through the voided area, three obvious reflected waves appeared in sequence in the single-channel waveform diagram from the entry to the exit of the voided area. According to the time sequence, the first and third reflected waves showed an opposite phenomenon, and the time interval between the first and second reflected waves was different from that between the second and third reflected waves. Based on the time interval of the reflected waves, the distribution of the filling medium and polymer within the voided depth range was inferred, and the polymer repair status was estimated.

4. The method for analyzing the results of polymer grouting repair in areas of voided dam panels according to claim 1, characterized in that: The ground-penetrating radar profile of the dam panel after complete repair of the voided area shows two clusters of curves. The amplitude at the top of the two clusters of curves is smaller than that before the repair, and the time interval between the two clusters of curves is smaller than the time interval between the two curves before the repair.

Images