CN112014474A - Concrete strength detection method based on ultrasonic surface wave frequency dispersion curve - Google Patents
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Abstract
The invention provides a concrete strength detection method based on an ultrasonic surface wave frequency dispersion curve, which comprises the following steps of: carrying out ultrasonic detection on the concrete member to obtain an ultrasonic surface wave seismic record of the concrete member; carrying out data conversion processing on the ultrasonic surface wave seismic record to obtain a phase velocity dispersion curve of the ultrasonic surface wave seismic record; layering the concrete member according to the fluctuation condition of the phase velocity dispersion curve, calculating the average surface wave phase velocity of each layer of the concrete member, and calculating the concrete strength of each layer of the concrete member according to the average surface wave phase velocity; evaluating the overall strength of the concrete member according to the concrete strength of each layer of the concrete member.
Description
Technical Field
The invention relates to a concrete strength detection technology, in particular to a concrete strength detection method based on an ultrasonic surface wave frequency dispersion curve.
Background
In recent years, infrastructure construction is vigorously carried out in China, wherein concrete members are important materials for buildings. In order to ensure the engineering quality, the nondestructive testing is very important in the strength testing of the concrete member. At present, the concrete strength nondestructive detection methods are also many, such as a rebound method, an ultrasonic rebound synthesis method, a Rayleigh wave method and the like. The rebound method is the most commonly used method and is relatively simple and convenient, but when the rebound method is used for measuring the surface strength of concrete, the rebound method is limited by factors such as increase of the components of the concrete admixture, use of an additive, gradual reduction of the particle size of the coarse aggregate, and continuous increase of the mortar proportion. If the test is performed only by the rebound method, accurate determination of the strength of the solid concrete cannot be achieved. The comprehensive ultrasonic resilience method for detecting the compressive strength of the concrete is a method for comprehensively detecting the compressive strength of the concrete by adopting at least more than two single methods or parameters (including mechanics, acoustics, physics and the like), but factors such as different cement varieties, frequencies of different devices, measuring distances and the like can greatly influence the precision of the method, and the method is relatively complicated in operation and relatively low in efficiency. The rayleigh wave method is used for evaluating the concrete strength by extracting a dispersion curve to invert the transverse wave speed and establishing a relation between the transverse wave speed and the concrete strength, but due to the reasons of instruments and equipment and the like, the rayleigh wave method cannot be used for a concrete member body with a small volume, so that the application range is limited.
Disclosure of Invention
Aiming at the problems, the invention provides a concrete strength detection method based on an ultrasonic surface wave frequency dispersion curve. The method mainly comprises the following steps:
s100, carrying out ultrasonic detection on the concrete member to obtain an ultrasonic surface wave seismic record of the concrete member;
s200, performing data conversion processing on the ultrasonic surface wave seismic record to obtain a phase velocity dispersion curve of the ultrasonic surface wave seismic record;
s300, layering the concrete member according to the fluctuation condition of the phase velocity dispersion curve, calculating the average surface wave phase velocity of each layer of the concrete member, and taking the average surface wave phase velocity as the Rayleigh wave phase velocity of the layer so as to calculate the concrete strength of each layer of the concrete member;
s400, calculating the total concrete strength of the concrete member according to the concrete strength of each layer of the concrete member.
According to an embodiment of the present invention, the step S100 includes the steps of:
s110, arranging a transmitting probe and a receiving probe of the ultrasonic detector according to a planimetry method;
s120, transmitting ultrasonic waves to the concrete member by using a transmitting probe of the ultrasonic detector;
and S130, detecting ultrasonic signals at a plurality of positions on the surface of the concrete member in sequence by using a receiving probe of the ultrasonic detector to obtain an ultrasonic surface wave seismic record consisting of a group of ultrasonic surface wave data.
According to an embodiment of the present invention, the step S200 includes the following steps:
s210, performing data conversion processing on the ultrasonic surface wave seismic record to obtain a frequency dispersion energy diagram of the ultrasonic surface wave seismic record;
and S220, extracting a phase velocity dispersion curve of the ultrasonic surface wave seismic record from the dispersion energy diagram.
According to an embodiment of the present invention, the step S210 specifically includes:
and carrying out high-resolution linear radon transformation processing on the ultrasonic surface wave seismic record to obtain a frequency dispersion energy diagram of the ultrasonic surface wave seismic record.
According to an embodiment of the present invention, the step S300 includes the following steps:
s310, segmenting the phase velocity dispersion curve according to the fluctuation condition of the phase velocity dispersion curve, and layering the concrete member according to the segmentation condition of the phase velocity dispersion curve:
s320, calculating the average surface wave frequency and the average surface wave phase velocity of each section of the phase velocity dispersion curve, taking the average surface wave frequency and the average surface wave phase velocity as the average surface wave frequency and the average surface wave phase velocity of each layer of the concrete member, and calculating the thickness of each layer of the concrete member according to the average surface wave frequency and the average surface wave phase velocity of each layer of the concrete member;
and S330, calculating the concrete strength of each layer of the concrete member by taking the average surface wave phase velocity of each layer of the concrete member as the Rayleigh wave velocity of each layer.
According to an embodiment of the present invention, in the step S320, the thickness of each layer of the concrete member is calculated according to the following formula:
hi=vi/2fi
in the formula, hiIs the thickness of the i-th layer of the concrete member, viIs the average surface wave phase velocity, f, of the i-th layer of the concrete memberiIs the average surface wave frequency of the ith layer of the concrete element.
According to an embodiment of the present invention, in the step S330, the concrete strength of each layer of the concrete member is calculated according to the following formula:
in the formula, RcAnd VrIs the concrete strength and rayleigh wave velocity of a layer in the concrete member, and A, B is a correlation coefficient.
According to an embodiment of the present invention, the step S400 specifically includes:
calculating the overall strength of the concrete member according to the concrete strength of each layer of the concrete member, wherein the overall strength of the concrete member is equal to the arithmetic mean of the concrete strengths of the layers of the concrete member.
According to another embodiment of the present invention, the step S400 specifically includes:
calculating an overall strength of the concrete member from the concrete strength of each layer of the concrete member, wherein the overall strength of the concrete member is equal to a weighted average of the concrete strengths of the layers of the concrete member.
According to an embodiment of the invention, the weighting coefficients in the calculation of the weighted average are determined in dependence of the thickness of the layers of the concrete element.
Compared with the prior art, the concrete strength detection method based on the ultrasonic surface wave frequency dispersion curve has the following advantages or beneficial effects:
the ultrasonic surface wave data acquisition device preferably utilizes an ultrasonic detector, arranges the transmitting probe and the receiving probe according to a planimetric method, sequentially moves the receiving probe to a plurality of measuring points of the concrete member, records signals of ultrasonic waves sent by the transmitting probe in the concrete member to obtain a group of ultrasonic surface wave data, and acquires the ultrasonic surface waves through the ultrasonic detector.
The method preferably extracts the frequency dispersion curve of the ultrasonic surface wave by utilizing high-resolution linear radon transform, then carries out layered modeling on the concrete member directly according to the fluctuation condition of the frequency dispersion curve of the ultrasonic surface wave without inversion to obtain the average surface wave phase speed and thickness of each layer, and then obtains the strength of the concrete member according to an empirical formula between the Rayleigh surface wave phase speed and the concrete strength.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
FIG. 1 is a schematic diagram of a concrete form member and a predetermined line drawing according to a first embodiment of the present invention;
FIG. 2 is a schematic illustration of an ultrasonic surface wave seismic record according to a first embodiment of the invention;
FIG. 3 is a schematic diagram of a frequency dispersion energy diagram and a frequency dispersion curve of an ultrasonic surface wave according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of the phase velocity model obtained by averaging the dispersion curves of the present invention and by inversion;
FIG. 5 is a schematic illustration of the averaging of the dispersion curves by the present invention versus the strength of the concrete by inversion;
FIG. 6 is a flowchart of the steps of the method for detecting concrete strength based on the ultrasonic surface wave dispersion curve according to the present invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details or with other methods described herein.
Example one
The principle of the invention is first described below.
Surface wave exploration is a geophysical exploration method which is started in recent years, and particularly in the aspect of engineering geophysical prospecting, the transverse wave velocity of a shallow surface underground medium can be accurately obtained by inverting a dispersion curve of a surface wave, so that mechanical parameters of the shallow surface underground medium can be obtained. The surface wave has no dispersion characteristic in the uniform half space, but the dispersion phenomenon occurs when the surface wave is in a medium which is not the uniform half space, namely the change of the frequency and the movement speed are changed, and the change of the pulse wave caused by the change of the distance is caused. Generally, the fluctuation is rarely a single frequency wave, and it is also possible that many single frequency waves are superposed. The phase velocity is the velocity of one of the frequency waves, the propagation velocity after the summation of the maximum values of the amplitudes of all the frequency waves is the group velocity u, and the relationship between the two is as follows:
Wherein u is the group velocity and λ is the wavelength; k is the wavenumber and v is the phase velocity.
When the surface wave propagates in the form of a monochromatic wave, the wavelength is constant, i.e., there is no dispersion phenomenon in a uniform medium, but in reality, such an ideal model does not exist. In fact, the physical parameters in the medium cannot be the same, that is, each frequency wave composing the wave will propagate forward with different speed, so that the wave continuity obtained after the waves are overlapped increases, and because the time changes, a wave becomes a series of waves, which is the dispersion phenomenon. In surface wave exploration, depth detection can be carried out by utilizing different wavelengths of surface waves.
For a two-dimensional wavefield, defined herein as d (x, t), a Fourier transform is performed in the time domain for each pass to obtain d (x, f). The standard radon transform of the fourier transformed amplitude spectrum and phase spectrum has the following formula:
the formula (2) can be expressed as a matrix:
d=Lm (4)
wherein L is ei2πfpxFor the forward transform operator in the Linear Radon Transform (LRT), m and d represent the radon matrix and shot gather records, respectively.
Like before, equation (3) can be changed to the following form:
madj=LTd (5)
in the formula madjIs to indicate a use of a transposition or adjoint operator LTThe operator does not have a good inverse operator for the low resolution radon matrix.
In a mixture equation, an objective function is generally desired:
J=||d-Lm||2 (6)
the value of (c) converges to a minimum, and this problem can be solved by the least squares method:
m=(LTL)-1LTd (7)
in practical applications, it is generally necessary to introduce a damping factor λ to make the inversion process more stable:
m=(LTL+λI)-1LTd (8)
for the general case, the least squares inversion method may provide greater accuracy in the radon domain. And the data limit of the noise-containing model can be well reduced by selecting a reasonable damping factor. With proper pre-weighting:
d=LWm -1Wmm (9)
the sparse solution can be obtained, and the resolution of the model can be effectively improved. The objective function then becomes:
by solving equations
Such a model can be found.
Wherein I represents an identity matrix; wdA weight matrix representing the data. In practice, WdIs generally expressed as a standard deviation r ═ LWm -1Wmm-d to determine the diagonal matrix form. The weight matrix of the model is represented by WmRepresentation is very important in designing high resolution radon operators (e.g., resolution and smoothness W)m -TIs Wm -1Transpose of (1); the meaning of λ represents a trade-off between data error and model constraints. Equation (11) can be solved quickly by the conjugate gradient method.
For ultrasonic surface wave recording, a high-resolution linear radon transform method is adopted to extract a frequency dispersion curve. The main idea of the radon transform method is to imagine the process of frequency dispersion analysis as a geophysical inversion process, and reduce the model data limitation by using a pre-weighted conjugate gradient algorithm, so that the resolution is obviously improved. In each iteration process of inversion, the algorithm continuously modifies the pre-weighting matrix, so that the resolution of the dispersion energy is higher one time, and finally a high-resolution dispersion energy map can be obtained. The resolution depends on the iterative process in the conjugate gradient algorithm. At the beginning of the iteration, this method is not different from the standard linear radon transform. The resolution of this method increases from time to time as the number of iterations increases.
In the field of surface wave exploration, when a surface wave meets a layered medium, a dispersion curve of the surface wave is known to have an inflection point, the obtained dispersion curve is analyzed, the dispersion curve is segmented according to the inflection point condition, a concrete member is subjected to layered analysis, and the average frequency and the phase velocity of each segment are recorded. And is represented by the formula hi=vi/2fiThe thickness and phase velocity of each layer of the concrete wall can be calculated. In the formula, hiIs the thickness of the i-th layer of the concrete member, viIs the average surface wave phase velocity, f, of the i-th layer of the concrete memberiIs the average surface wave frequency of the ith layer of the concrete element.
The surface wave method is used for detecting the concrete strength, and firstly, the relation between the concrete strength and the surface wave speed is established. The best fit using the power function equation has been demonstrated by regression comparisons using the linear equation, exponential equation, parabolic equation, and power function equation. That is, the concrete strength is fitted to the surface wave velocity (Rayleigh velocity V) by using a power function equationr) Has the following relationship:
in the formula: rcIs concrete strength (MPa); A. b is the correlation coefficient.
Further, the concrete strength and the Rayleigh wave velocity V can be obtained by analyzing according to the log-linear regressionrThe expression of the relationship:
in the formula:is the equivalent value (MPa) of the concrete strength; the correlation coefficients were 0.91 and 1.64. In this case, the average relative error was 8.5%, and the relative standard error was 9.8%.
From the above formula, it is only necessary to know the Rayleigh wave velocity VrValue, the concrete strength can be convertedThe value is obtained.
Thus, the concrete strength of each layer of the concrete member can be calculated from the above-described relationship, and the overall strength of the concrete member can be further evaluated on the basis of the concrete strength of each layer of the concrete member.
Based on the principle, the invention provides a concrete strength detection method based on an ultrasonic surface wave frequency dispersion curve. In real time, firstly, an ultrasonic detector is utilized, a transmitting probe and a receiving probe are arranged according to a planimetric method, the receiving probe is sequentially moved to a plurality of measuring points of a concrete member, signals of ultrasonic waves transmitted by the transmitting probe in the concrete member are recorded, a group of ultrasonic surface wave data is obtained, then a high-resolution linear radon transform is utilized to extract a dispersion curve of the ultrasonic surface waves, then the concrete member is subjected to layered modeling directly according to the fluctuation condition of the ultrasonic surface wave dispersion curve without inversion, the average surface wave phase velocity and the thickness of each layer are obtained, and the strength of the concrete member is obtained according to an empirical formula between the surface wave velocity phase velocity and the concrete strength.
In this embodiment, the method mainly includes the following steps:
(1) firstly, an ultrasonic detector is utilized to arrange a transmitting probe and a receiving probe according to a planimetry method, the receiving probe is sequentially moved to a plurality of measuring points of a concrete member, and signals of ultrasonic waves transmitted by the transmitting probe in the concrete member are recorded to obtain a group of ultrasonic surface wave data.
(2) And carrying out high-resolution linear radon transformation on the acquired ultrasonic surface wave data to obtain a frequency dispersion energy diagram of the actually measured data, and extracting a phase velocity frequency dispersion curve from the frequency dispersion energy diagram.
(3) When the surface wave meets a layered medium, a frequency dispersion curve of the surface wave can have an inflection point, so that the obtained frequency dispersion curve is analyzed, the frequency dispersion curve is segmented according to the inflection point condition of the frequency dispersion curve so as to perform layered analysis on the concrete member, and the average frequency and average phase speed of each segment of the frequency dispersion curve are recorded.
(4) Based on the formula hi=vi/2fiThe thickness and average phase velocity of each layer in the concrete member are calculated.
(5) And taking the average surface wave phase velocity of each layer as the Rayleigh wave velocity of each layer, and obtaining the concrete strength of each layer in the concrete member according to an empirical calculation formula between the Rayleigh wave phase velocity and the concrete strength.
(6) The overall strength of the concrete member was evaluated based on the concrete strength of each layer in the concrete member.
Example two
On the exemplary concrete member body as shown in fig. 1, an RSM-SY6 foundation pile acoustic detector was used to detect ultrasonic waves inside reinforced concrete. And extracting a dispersion curve according to the ultrasonic seismic record obtained by detection, and estimating the total strength of the cement concrete through the surface wave phase velocity.
Firstly, connecting two probes, then starting up to set parameters, wherein the number of sampling points is 1024, and the sampling time interval is 1 microsecond. The method comprises the steps of measuring the side surface of concrete for 5 times respectively, enabling the offset distance to be 5 cm, enabling the track interval to be 5 cm, enabling 26 tracks to be arranged on the side surface, coating vaseline on two probes, enabling the probes to be well coupled with the concrete wall, fixing the first probe at the position of a first point to serve as a signal transmitting probe, enabling the second probe to serve as a signal receiving probe, moving the probes point by point sequentially along the set point, storing recorded waveform data respectively, and finally obtaining a plurality of ultrasonic surface wave data, namely seismic records of the ultrasonic surface wave data, which are also called ultrasonic surface wave seismic records.
Fig. 2 is a seismic record of the obtained ultrasonic surface wave data, and the surface wave is very obvious and strong in energy. The dispersion energy map and dispersion curve shown in fig. 3 are obtained by performing high-resolution linear radon transform processing on the data recorded in the seismic data of fig. 2.
As can be seen from fig. 3, the dispersion curve has a relatively obvious dispersion at the low frequency, and enters a uniform medium at a shallow layer, i.e., at a high frequency, and the phase velocity tends to be flat without any obvious abrupt change. It can be concluded that there is a small dispersion at 4kHz-4.5kHz, i.e. 4.5kHz corresponds to an inflection point where the ultrasound enters another medium. Therefore, the output is at the place of about 7.2kHzNow the inflection point is present, so the reinforced concrete can be divided into 2 layers, and the surface of the concrete wall is known to have a cover layer, so the reinforced concrete has 3 layers in total. Further, the phase velocities in each uniform medium layer are extracted according to the dispersion curve, so that 3 average phase velocities need to be extracted here. Wherein the average value of the 4kHz-4.5kHz sampling surface wave phase velocity is 2128.7m/s, the average value of the intermediate frequency part sampling surface wave phase velocity is 2076.5m/s, and the average value of the high frequency part sampling surface wave phase velocity is 1477.8 m/s. By the formula hi=vi/2fiThe thickness of each layer of the concrete wall can be calculated. As can be seen from Table 1 below, the cover layer was about 0.03 m, the thicknesses of the two layers were 0.17 m and 0.25 m in this order, and the total thickness was 0.45 m, which is consistent with the results of the actual measurement.
TABLE 1 analytical parameters of the dispersion curve averaging method
The solid line in fig. 4 represents a phase velocity structure converted from a shear velocity structure obtained by inversion in the prior art; the dashed line represents the phase velocity profile with layer thickness obtained by the dispersion curve-based averaging method of the present invention. As can be seen from fig. 4, the difference between the two curves is larger in the shallow cap portion and smaller in the middle and deep portions. According to the judgment of actual conditions, the dispersion curve averaging method provided by the invention is more practical, and the inversion method has small errors in shallow layers. Further, the overall strength of the concrete member was analyzed using an empirical calculation between the surface wave phase velocity and the concrete strength based on two methods, respectively (as shown in fig. 5). Tests show that the strength of the concrete block is C30, namely, fcu is more than or equal to 30MPa and less than 35MPa, and the strength of the concrete wall obtained by the method is about 32.5MPa, which is completely consistent with the actual strength value of the concrete. This fully illustrates the accuracy of the method of the invention. And compared with the result of an inversion method, the method disclosed by the invention is found to be even better than the result obtained by the inversion method in the shallow layer. This further demonstrates that the process of the invention is more efficient and stable.
EXAMPLE III
In summary, the present invention aims to provide a concrete strength detection method based on an ultrasonic surface wave dispersion curve. As shown in fig. 6, in the third embodiment, the method mainly includes the following steps:
s100, carrying out ultrasonic detection on the concrete member to obtain an ultrasonic surface wave seismic record of the concrete member;
s200, performing data conversion processing on the ultrasonic surface wave seismic record to obtain a phase velocity dispersion curve of the ultrasonic surface wave seismic record;
s300, layering the concrete member according to the fluctuation condition of the phase velocity dispersion curve, calculating the average surface wave phase velocity of each layer of the concrete member, and taking the average surface wave phase velocity as the Rayleigh wave phase velocity of the layer so as to calculate the concrete strength of each layer of the concrete member;
s400, calculating the total concrete strength of the concrete member according to the concrete strength of each layer of the concrete member.
It is to be understood that the disclosed embodiments of the invention are not limited to the particular process steps or materials disclosed herein, but rather, are extended to equivalents thereof as would be understood by those of ordinary skill in the relevant art. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.
Reference in the specification to "an embodiment" means that a particular feature, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrase "an embodiment" appearing in various places throughout the specification are not necessarily all referring to the same embodiment.
It will be appreciated by those of skill in the art that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described in a functional general in the foregoing description for the purpose of illustrating clearly the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
Although the embodiments of the present invention have been described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A concrete strength detection method based on an ultrasonic surface wave frequency dispersion curve comprises the following steps:
s100, carrying out ultrasonic detection on the concrete member to obtain an ultrasonic surface wave seismic record of the concrete member;
s200, performing data conversion processing on the ultrasonic surface wave seismic record to obtain a phase velocity dispersion curve of the ultrasonic surface wave seismic record;
s300, layering the concrete member according to the fluctuation condition of the phase velocity dispersion curve, calculating the average surface wave phase velocity of each layer of the concrete member, and calculating the concrete strength of each layer of the concrete member according to the average surface wave phase velocity;
and S400, evaluating the overall strength of the concrete member according to the concrete strength of each layer of the concrete member.
2. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 1, wherein the step S100 comprises the steps of:
s110, arranging a transmitting probe and a receiving probe of the ultrasonic detector according to a planimetry method;
s120, transmitting ultrasonic waves to the concrete member by using a transmitting probe of the ultrasonic detector;
and S130, detecting ultrasonic signals at a plurality of positions on the surface of the concrete member in sequence by using a receiving probe of the ultrasonic detector to obtain an ultrasonic surface wave seismic record consisting of a group of ultrasonic surface wave data.
3. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 1, wherein the step S200 comprises the steps of:
s210, performing data conversion processing on the ultrasonic surface wave seismic record to obtain a frequency dispersion energy diagram of the ultrasonic surface wave seismic record;
and S220, extracting a phase velocity dispersion curve of the ultrasonic surface wave seismic record from the dispersion energy diagram.
4. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 3, wherein the step S210 specifically comprises:
and carrying out high-resolution linear radon transformation processing on the ultrasonic surface wave seismic record to obtain a frequency dispersion energy diagram of the ultrasonic surface wave seismic record.
5. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 1, wherein the step S300 comprises the steps of:
s310, segmenting the phase velocity dispersion curve according to the fluctuation condition of the phase velocity dispersion curve, and layering the concrete member according to the segmentation condition of the phase velocity dispersion curve:
s320, calculating the average surface wave frequency and the average surface wave phase velocity of each section of the phase velocity dispersion curve, taking the average surface wave frequency and the average surface wave phase velocity as the average surface wave frequency and the average surface wave phase velocity of each layer of the concrete member, and calculating the thickness of each layer of the concrete member according to the average surface wave frequency and the average surface wave phase velocity of each layer of the concrete member;
and S330, calculating the concrete strength of each layer of the concrete member by taking the average surface wave phase velocity of each layer of the concrete member as the Rayleigh wave velocity of each layer.
6. The method for detecting concrete strength based on an ultrasonic surface wave dispersion curve according to claim 5, wherein in step S320, the thickness of each layer of the concrete member is calculated according to the following formula:
hi=vi/2fi
in the formula, hiIs the thickness of the i-th layer of the concrete member, viIs the average surface wave phase velocity, f, of the i-th layer of the concrete memberiIs the average surface wave frequency of the ith layer of the concrete element.
7. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 5, wherein in the step S330, the strength of the concrete of each layer of the concrete member is calculated according to the following formula:
in the formula, RcAnd VrIs the concrete strength and rayleigh wave velocity of a layer in the concrete member, and A, B is a correlation coefficient.
8. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 7, wherein the step S400 specifically comprises:
calculating the overall strength of the concrete member according to the concrete strength of each layer of the concrete member, wherein the overall strength of the concrete member is equal to the arithmetic mean of the concrete strengths of the layers of the concrete member.
9. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 7, wherein the step S400 specifically comprises:
calculating an overall strength of the concrete member from the concrete strength of each layer of the concrete member, wherein the overall strength of the concrete member is equal to a weighted average of the concrete strengths of the layers of the concrete member.
10. The method for detecting the strength of the concrete based on the ultrasonic surface wave dispersion curve as claimed in claim 9, wherein:
the weighting coefficient in calculating the weighted average is determined according to the thickness of each layer of the concrete member.
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