Comprehensive test method and system for concrete damage evolution process in water environment

Abstract

The invention discloses a comprehensive test method and system for a concrete damage evolution process in a water environment. The test method comprises the following steps: obtaining a concrete test piece; applying external force to the concrete test piece to obtain the evolution process of the external crack of the concrete; obtaining the internal damage position of the concrete; determining the concrete damage degree according to the damage position; and determining an internal damage failure mode of the concrete according to the damage degree of the concrete, and completing a comprehensive test. The concrete damage evolution process is comprehensively and accurately evaluated by simulating a real water environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete damage evolution detection, and particularly relates to a comprehensive test method and system for the concrete damage evolution process under a water environment. Background Art

[0002] With the continuous development of modern construction engineering technology, concrete, as one of the main building materials, has been widely used in various infrastructure projects. Especially in projects such as bridges, tunnels, dams, and marine engineering, concrete is exposed to underwater or humid environments for a long time, and its performance and durability are affected by various environmental factors, such as water erosion, freeze-thaw cycles, chemical corrosion, etc. These factors will accelerate the concrete damage evolution process, thereby affecting the safety and service life of engineering structures. Therefore, in-depth research on the concrete damage evolution mechanism under a water environment is of great significance for ensuring the long-term stable operation of engineering structures.

[0003] Currently, the research on the concrete damage evolution process is mostly based on test methods under laboratory standard conditions. However, these methods are often difficult to accurately simulate the complex conditions under the actual water environment, resulting in a large difference between the test results and the actual situation. In addition, existing test methods mostly focus on the evaluation of single factors (such as mechanical properties, durability), lacking a comprehensive consideration of the concrete damage evolution process. Therefore, it is particularly urgent to develop a comprehensive test method for the concrete damage evolution process that can simulate the real water environment and comprehensively consider various influencing factors. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes a comprehensive test method and system for the concrete damage evolution process under a water environment, which comprehensively and accurately evaluates the concrete damage evolution process by simulating the real water environment.

[0005] The present invention provides a comprehensive test method for the concrete damage evolution process under a water environment, which is characterized by including:

[0006] Obtain concrete specimens;

[0007] Apply an external force to the concrete specimens to obtain the evolution process of external cracks in the concrete;

[0008] Obtain the internal damage positions of the concrete;

[0009] Determine the concrete damage degree according to the damage positions;

[0010] Determine the internal damage failure mode of the concrete according to the concrete damage degree to complete the comprehensive test.

[0011] Optionally, the concrete specimen is filled with a strain-sensing optical fiber, and a strain gauge is pasted on the surface of the concrete specimen. Among them, the strain-sensing optical fiber is used to obtain the internal damage position of the concrete, and the strain gauge is used to accurately measure the strain change curve on the surface of the concrete specimen.

[0012] Optionally, obtaining the evolution process of external cracks in the concrete according to the concrete specimen includes:

[0013] Collect the speckle image of the concrete specimen, and obtain a grayscale image by performing analog-to-digital conversion on the speckle image;

[0014] Based on the grayscale image, determine the reference image sub-region and the target image sub-region;

[0015] Obtain the correlation between the reference image sub-region and the target image sub-region, and according to the correlation, obtain the displacement field and strain field of the surface deformation of the concrete specimen;

[0016] According to the displacement field and strain field, obtain the evolution process of external cracks in the concrete.

[0017] Optionally, obtaining the correlation between the reference image sub-region and the target image sub-region includes:

[0018] Calculate according to the images before and after deformation and the average grayscale values before and after deformation to obtain the correlation between the reference image sub-region and the target image sub-region.

[0019] Optionally, determining the degree of concrete damage according to the damage position includes:

[0020] Based on the damage position, use acoustic emission characteristic parameters to determine the degree of concrete damage; among them, the acoustic emission characteristic parameters include: acoustic emission basic parameters, change rate parameters, and cumulative parameters.

[0021] Optionally, determining the internal damage failure mode of the concrete according to the degree of concrete damage includes:

[0022] According to the acoustic emission characteristic parameters, determine the acoustic emission parameters;

[0023] According to the acoustic emission parameters, combined with the degree of concrete damage, determine the internal damage failure mode of the concrete.

[0024] The present invention also provides a comprehensive test system for the concrete damage evolution process under a water environment, including: a concrete specimen module, an external crack evolution module, an internal damage failure module, and a comprehensive test module;

[0025] The concrete specimen module is used to obtain a concrete specimen;

[0026] The external crack evolution module is used to obtain the evolution process of external cracks in concrete;

[0027] The internal damage failure module is used to determine the internal damage failure mode of concrete;

[0028] The comprehensive test module is used to complete a comprehensive test according to the evolution process of external cracks in concrete and the internal damage failure mode of concrete.

[0029] Optionally, the inside of the concrete specimen is filled with strain sensing optical fibers, and strain gauges are pasted on the surface of the concrete specimen. Among them, the strain sensing optical fibers are used to obtain the internal damage position of the concrete, and the strain gauges are used to accurately measure the strain change curve on the surface of the concrete specimen.

[0030] Optionally, the external crack evolution module includes: an image acquisition unit, a correlation calculation unit, and a surface field calculation unit;

[0031] The image acquisition unit is used to acquire the speckle image and grayscale image of the concrete specimen;

[0032] The correlation calculation unit is used to obtain the correlation between the reference image sub-region and the target image sub-region;

[0033] The surface field calculation unit is used to obtain the displacement field and strain field of the surface deformation of the concrete specimen.

[0034] Optionally, the internal damage failure module includes: a damage position module, a damage degree module;

[0035] The damage position module is used to obtain the internal damage position of the concrete;

[0036] The damage degree module is used to determine the damage degree of the concrete according to the damage position.

[0037] The invention has the following advantages and technical effects:

[0038] The present invention comprehensively and accurately evaluates the damage evolution process of concrete by simulating the real water environment. The present invention helps to deeply understand the damage mechanism of concrete in the water environment, and provides a scientific basis for the optimal design of concrete materials, the improvement of construction technology, and the formulation of maintenance strategies. Description of the Drawings

[0039] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0040] Figure 1It is a flowchart of a comprehensive test method for the concrete damage evolution process in an embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of digital image processing technology in an embodiment of the present invention;

[0042] Figure 3 It is a schematic diagram of acoustic emission detection principle in an embodiment of the present invention;

[0043] Figure 4 It is a crack failure mode diagram in an embodiment of the present invention. Specific embodiments

[0044] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail this application.

[0045] It should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0046] This embodiment provides a comprehensive test method for the concrete damage evolution process in a water environment, as Figure 1 shown, specifically including:

[0047] Obtain concrete specimens;

[0048] Apply an external force to the concrete specimens to obtain the evolution process of external cracks in the concrete;

[0049] Obtain the internal damage location of the concrete;

[0050] Determine the concrete damage degree according to the damage location;

[0051] Determine the internal damage failure mode of the concrete according to the concrete damage degree to complete the comprehensive test.

[0052] Specifically, the multi-scale test system for the damage of the concrete dam structure surface consists of digital image processing technology (DIC), acoustic emission technology (AE), a strain acquisition system, and a distributed strain sensing optical fiber system. As Figure 2 shown, the digital image processing technology (DIC) is used to monitor the deformation of the observation surface of the above-mentioned concrete specimens with prefabricated cracks after applying water pressure, and its debugging mainly includes the calibration of the detection range, and the monitoring surface is the structure surface with speckles made; as Figure 3As shown in the figure, acoustic emission technology (AE) is used to monitor the internal damage of pre-cracked concrete specimens; the strain acquisition system monitors the strain at the paste position by pasting full-bridge strain gauges at the crack tips and structural surfaces of pre-cracked concrete specimens and then connecting the strain gauges to a static acquisition board through wires; the distributed strain sensing optical fiber system monitors the strain inside concrete members by embedding distributed optical fibers at appropriate positions inside the concrete specimens.

[0053] Furthermore, strain sensing optical fibers are filled inside the concrete specimens, and strain gauges are pasted on the surface of the concrete specimens. Among them, the strain sensing optical fibers are used to obtain the internal damage positions of the concrete, and the strain gauges are used to accurately measure the strain change curve on the surface of the concrete specimens.

[0054] Specifically, the specific steps for preparing concrete specimens include: assembling the mold, welding the pre-cracked plate, fixing the distributed strain sensing optical fiber, painting the release agent, pouring, demolding, and curing.

[0055] (1) The mold consists of 5 steel plates, each fixed by bolts. Among them, a sufficient number of holes are drilled on the two steel plates with the largest length and height; and, small holes through which the distributed strain sensing optical fiber can pass are drilled on the two steel plates with the largest width and height.

[0056] (2) Lay the distributed strain sensing optical fiber;

[0057] Distributed optical fiber sensing technology is an advanced monitoring technology. It uses optical fibers as sensors and transmission media and can realize continuous distributed measurement of various physical parameters such as temperature, strain, and vibration. According to the measurement requirements, lay the optical fiber along a predetermined path in the monitoring area, pass the optical fiber through the small holes of the prefabricated mold, and paint an appropriate amount of release agent on each contact surface of the steel plate, pre-cracked plate, and concrete with a brush; this facilitates the removal of the mold without damaging the optical fiber.

[0058] (4) Subsequently, start pouring. Pouring means weighing the corresponding amounts of stones, sand, water, and water reducer according to the mix ratio, pouring them into a vertical mixer in a certain order, stirring, and after the stirring is completed, taking out the mixture, placing it on the steel plate, and then manually turning it over 2 - 3 times to make the moisture distribution of the mixture more uniform, and then loading it into the steel mold and vibrating it to make it stand and take shape. The mix ratio is the ratio of stones, sand, water, and water reducer selected according to the actual project or a ratio specially set according to the test needs. The specific order is to first pour the stones and sand into the vertical mixer, stir evenly, then pour in the cement, stir evenly again, then pour in a part of the mixture of water and water reducer, stir evenly, and then pour in the remaining mixture of water and water reducer and stir evenly. Vibration is carried out using a vibrating rod. When a certain amount of the mixture is put in, use the vibrating rod to vibrate according to the requirements to make the concrete dense.

[0059] (5) Wait for the specimen to be formed. After it reaches a certain hardness, remove the formwork and cover it with geotextile. Sprinkle water for curing every day and continue curing for 28 days.

[0060] Specifically, pasting strain gauges on concrete structures is a technique for accurately measuring material strain and stress, which is widely used in the monitoring and research of important engineering structures such as bridges, dams, and tunnels. First, the concrete surface needs to be properly pretreated, including removing oil stains, dust, and other impurities on the surface to ensure the surface is clean and flat. Use sandpaper or a grinding machine to slightly polish the surface to increase the adhesion of the adhesive. Apply a thin layer of base glue, such as epoxy resin glue, evenly on the cleaned concrete surface. This layer of base glue helps to improve the bonding performance between the strain gauge and the concrete surface. Place the strain gauge accurately at the predetermined position and gently press it to ensure good contact with the concrete surface. If necessary, cover it with a transparent film and press gently to help expel air bubbles and make the adhesive distribute more evenly. Connect the strain gauge wires to the data acquisition device. Ensure that all connections are firm and reliable to avoid loosening or breaking during subsequent use. After the adhesive is completely cured, take necessary protective measures for the strain gauge, such as applying a moisture-proof agent or installing a protective cover, to prevent environmental factors such as moisture and temperature changes from affecting the measurement accuracy. Through the strain gauge, the strain process on the concrete surface during the water load action can be directly obtained.

[0061] Debug the fiber optic demodulator: The optical fiber is both a sensor and a data transmission medium. Inject an optical signal into the optical fiber through a light source. When the optical signal travels in the optical fiber, it will change due to the influence of the external environment. These changed signals are captured by the receiver at the end of the optical fiber and converted into electrical signals. The received electrical signals are amplified and processed, and the spatial distribution and change information of physical quantities such as temperature, strain, and vibration are analyzed through specific algorithms. Connect the distributed strain sensing optical fiber to the Omnisens modem and adjust the system parameters and channel parameters.

[0062] The data measured by the distributed optical fiber is the Brillouin frequency shift value. The corresponding relationship between the Brillouin frequency shift and strain is: every 0.05 MHz frequency shift corresponds to 1 με, and every 1 MHz frequency shift corresponds to 1 °C. It is calculated through the formula strain = (end Brillouin frequency shift value - initial Brillouin frequency shift value) * 1000 / 0.05. The distributed optical fiber can monitor the internal strain and stress changes in the concrete during the application of the water load.

[0063] Furthermore, based on the concrete specimen, obtaining the evolution process of external cracks in the concrete includes:

[0064] Collect the speckle images of the concrete specimen, and obtain the grayscale image by performing analog-to-digital conversion on the speckle images;

[0065] Based on the grayscale image, determine the reference image sub-region and the target image sub-region;

[0066] Obtain the correlation between the reference image sub-region and the target image sub-region, and based on the correlation, obtain the displacement field and strain field of the surface deformation of the concrete specimen;

[0067] Based on the displacement field and strain field, obtain the evolution process of the external cracks of the concrete.

[0068] Specifically, the digital image correlation technology collects the speckle images randomly distributed on the surface of the specimen through a digital camera, and tracks the movement of each point on the surface of the specimen by comparing and analyzing the speckle characteristics randomly distributed on the surface of the specimen before and after deformation, so as to obtain the deformation information of the surface of the specimen. After the digital camera collects the speckle images, the gray-scale images are obtained through analog-to-digital conversion, and certain correlation operations are performed on the two gray-scale images to obtain the displacement field and strain field of the surface deformation of the specimen.

[0069] After the image is sampled and analog-to-digital converted, the light intensity of each pixel on the image is represented by gray scale. The gray-scale eigenvalue function f(x, y) is used to represent the image before deformation, and the gray-scale eigenvalue function g(x’, y’) is used to represent the image after deformation. Since during the test, the focal length, position and illumination environment of the digital camera do not change, the gray-scale distribution of the image before deformation and the gray-scale distribution of the image after deformation have both certain similarities and certain differences, that is, they have a certain correlation. Therefore, a region of a certain size can be selected as the reference image sub-region with the point to be observed P(x o , y o ) as the center. In the image g(x’, y’) after deformation, calculate according to the correlation function to obtain the target image sub-region with P(x o ’, y o ’) as the center.

[0070] Furthermore, obtaining the correlation between the reference image sub-region and the target image sub-region includes:

[0071] Calculate according to the images before and after deformation and the average gray-scale values before and after deformation to obtain the correlation between the reference image sub-region and the target image sub-region.

[0072] In this step, as an additional embodiment:

[0073]

[0074] In the formula, f m is the average gray-scale value of the reference image sub-region, g m is the average gray-scale value of the target image sub-region. When C = 1, the two sub-regions are completely correlated. When C = 0, the two sub-regions are completely uncorrelated.

[0075] The measurement point P(x o , yo ) The displacements are: u = x0′ - x0, v = y0′ - y0. By taking the difference of the displacements, the displacement field and strain field on the surface of the specimen can be obtained, where x0 is the abscissa before deformation, x0′ is the abscissa after deformation, y0 is the ordinate before deformation, and y0′ is the ordinate after deformation.

[0076] Furthermore, according to the damage location, determining the concrete damage degree includes:

[0077] Based on the damage location, using acoustic emission characteristic parameters to determine the concrete damage degree; among them, the acoustic emission characteristic parameters include: acoustic emission basic parameters, change rate parameters, and cumulative parameters.

[0078] Specifically, when concrete is subjected to external forces, internal damage and failure will occur, mainly manifested as the formation, propagation of cracks, and the gradual evolution of the fracture process zone. Experimental observations have found that after the concrete component is loaded, in addition to undergoing a certain degree of elastic deformation, the original fissures and defects will also undergo a series of changes. These changes include the closure or opening of fissures, and the appearance and gradual expansion of microcrack regions at the ends of fissures, ultimately leading to unstable failure. This process can be regarded as the process of the evolution of internal defects in concrete to unstable failure, and the damage of concrete materials is the result of continuous accumulation during this process. During the loading process of the concrete specimen, the occurrence and propagation of internal cracks are the main sources of acoustic emission signals. These dynamic defects continuously release energy in the form of elastic waves and trigger acoustic emission events. In order to accurately determine the location of the acoustic emission source, sensors are arranged on the surface of the specimen and a sensor network is constructed. By detecting the signal characteristics (such as arrival time and amplitude) captured by each sensor, the three-dimensional coordinates of the acoustic emission source are calculated using a location algorithm. From the acoustic emission signals, a series of key characteristic parameters can be obtained to deeply analyze the dynamic behavior inside the measured component. The acoustic emission characteristic parameters include acoustic emission basic parameters, change rate parameters, and cumulative parameters. The basic parameters usually refer to some parameters based on the signal waveform, such as amplitude, energy, ring count, etc. The change rate parameters are generally used to describe the change of acoustic emission signal parameters per unit time, usually related to the deformation rate and crack propagation rate inside the material. The acoustic emission cumulative parameter refers to the cumulative value of a certain basic parameter of the acoustic emission signal during an acoustic emission process, usually used to describe the cumulative situation of internal damage in the material and the total intensity of acoustic emission during the entire acoustic emission process.

[0079] In this step, as an additional embodiment:

[0080] The acoustic emission slope b-value describes the crack propagation size through the acoustic emission amplitude distribution. When the crack propagates on a larger scale, the proportion of signals with large amplitudes in the acoustic emission signals is high, and at this time, the acoustic emission b-value is small; conversely, when the crack propagates on a smaller scale, the proportion of signals with small amplitudes in the acoustic emission signals is low, and at this time, the acoustic emission b-value is large. The b-value reflects the degree of crack propagation and is independent of the propagation distance. The change trend of the b-value corresponds to the formation and propagation of cracks. The rising trend of the b-value corresponds to the formation of microcracks; the falling trend of the b-value corresponds to the formation of larger cracks; when the b-value is less than 1, macroscopic cracks are formed inside the material. Therefore, the evolution process and damage degree of structural cracks can be analyzed through the change trend of the b-value.

[0081] The relationship between amplitude and frequency during the damage process of concrete structures is obtained through the G-R criterion, which is used to describe that the number of impacts generated during minor cracking of concrete is more than that generated during macroscopic fracture. The Gutenberg-Richter equation of acoustic emission is defined as follows:

[0082]

[0083] where N is the incremental frequency, representing the number of acoustic emission signals with amplitudes greater than A dB ; a and b are both empirical constants obtained through linear curve fitting. a is the intercept of the straight line; b is the slope, that is, the b-value; A dB is the amplitude of the acoustic emission signal, with the unit of dB, and 20 is a scaling factor, a constant introduced during unit conversion, without other physical meanings.

[0084] During the calculation of the b-value, the least squares method is used to fit the linear curve, and the fitting formula is as follows:

[0085]

[0086] x = A dB - A0, y = lnN

[0087]

[0088]

[0089] In the formula, A dB is the amplitude of the acoustic emission signal, A0 is the starting amplitude; N is the total number of acoustic emission amplitudes; m is the total number of acoustic emission parameters in the Rth group, x is the change value of the acoustic emission amplitude, which is the acoustic emission signal amplitude - starting amplitude, is the average value of m acoustic emission amplitude change values within the Rth group, x R is the total amplitude of the acoustic emission parameters in the Rth group, y is the logarithm of the total number of acoustic emission amplitudes, is the average value of the logarithms of the total number of m acoustic emission amplitudes within the R group, y R is the sum of the logarithms of the total number of m acoustic emission amplitudes within the R group, is the total amplitude value x of m acoustic emission parameters within the R group R and the sum of the logarithms of the total number of acoustic emission amplitudes y R of the product average value.

[0090] Furthermore, according to the degree of concrete damage, it is determined that the internal damage failure modes of concrete include:

[0091] According to the acoustic emission characteristic parameters, the acoustic emission parameters are determined;

[0092] According to the acoustic emission parameters and combined with the degree of concrete damage, the internal damage failure modes of concrete are determined.

[0093] In this step, as an additional embodiment:

[0094] According to two acoustic emission parameters, it can be determined whether the concrete crack is a tensile crack or a shear crack, as Figure 4 shown:

[0095] AF = ring count / duration

[0096] RA = rise time / amplitude

[0097] The classification of crack modes is based on the characteristics of waveform parameters. Tensile cracks have a shorter rise time, a higher average frequency, and a lower RA value compared to shear cracks. In contrast, the typical characteristics of shear cracks are a longer rise time, a lower average frequency, and a higher RA value. Therefore, by performing a correlation analysis on the RA value and the average frequency, the structural damage failure mode can be qualitatively judged.

[0098] This embodiment also provides a comprehensive test system for the concrete damage evolution process under a water environment, including: a concrete specimen module, an external crack evolution module, an internal damage failure module, and a comprehensive test module;

[0099] The concrete specimen module is used to obtain concrete specimens;

[0100] The external crack evolution module is used to obtain the evolution process of concrete external cracks;

[0101] The internal damage failure module is used to determine the internal damage failure modes of concrete;

[0102] The comprehensive test module is used to complete a comprehensive test according to the evolution process of concrete external cracks and the internal damage failure modes of concrete.

[0103] Further, the concrete specimen is filled with strain-sensing optical fibers, and strain gauges are pasted on the surface of the concrete specimen. Among them, the strain-sensing optical fibers are used to obtain the internal damage location of the concrete, and the strain gauges are used to accurately measure the strain change curve on the surface of the concrete specimen.

[0104] Further, the external crack evolution module includes: an image acquisition unit, a correlation calculation unit, and a surface field calculation unit;

[0105] The image acquisition unit is used to acquire the speckle image and grayscale image of the concrete specimen;

[0106] The correlation calculation unit is used to obtain the correlation between the reference image sub-region and the target image sub-region;

[0107] The surface field calculation unit is used to obtain the displacement field and strain field of the surface deformation of the concrete specimen.

[0108] Further, the internal damage failure module includes: a damage location module and a damage degree module;

[0109] The damage location module is used to obtain the internal damage location of the concrete;

[0110] The damage degree module is used to determine the concrete damage degree according to the damage location.

[0111] The above is only a preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A comprehensive testing method for concrete damage evolution process in water environment, characterized in that: include: Obtain concrete test specimens; Applying external force to the concrete specimen to obtain the evolution process of concrete external cracks; Obtain the location of internal damage in concrete; Determining the degree of concrete damage according to the damage location; According to the concrete damage degree, the internal damage failure mode of the concrete is determined and the comprehensive test is completed.

2. According to claim 1, a comprehensive testing method for concrete damage evolution process in water environment is characterized in that: The concrete specimen is filled with strain sensing optical fiber, and the surface of the concrete specimen is pasted with strain gauges, wherein the strain sensing optical fiber is used to obtain the damage position inside the concrete, and the strain gauge is used to accurately measure and obtain the strain change curve of the surface of the concrete specimen.

3. The comprehensive testing method for concrete damage evolution process in water environment according to claim 1 is characterized in that: According to the concrete specimen, obtaining the evolution process of concrete external cracks includes: Acquiring a speckle image of the concrete specimen, and performing analog-to-digital conversion on the speckle image to obtain a grayscale image; Based on the grayscale image, determining a reference image sub-region and a target image sub-region; Obtaining the correlation between the reference image sub-area and the target image sub-area, and obtaining the displacement field and strain field of the surface deformation of the concrete specimen according to the correlation; The evolution process of concrete external cracks is obtained according to the displacement field and strain field.

4. The comprehensive testing method for concrete damage evolution process in water environment according to claim 3 is characterized in that: Obtaining the correlation between the reference image sub-region and the target image sub-region includes: The correlation between the reference image sub-region and the target image sub-region is obtained by performing calculations based on the images before and after the deformation and the average grayscale values ​​before and after the deformation.

5. The comprehensive testing method for concrete damage evolution process in water environment according to claim 1 is characterized in that: Determining the degree of concrete damage according to the damage location includes: Based on the damage location, the degree of damage to the concrete is determined using acoustic emission characteristic parameters; wherein the acoustic emission characteristic parameters include: acoustic emission basic parameters, change rate parameters and accumulation parameters.

6. A comprehensive testing method for concrete damage evolution process in water environment according to claim 5, characterized in that: According to the concrete damage degree, the concrete internal damage failure mode is determined to include: Determining acoustic emission parameters according to the acoustic emission characteristic parameters; The internal damage failure mode of the concrete is determined according to the acoustic emission parameters and in combination with the concrete damage degree.

7. A comprehensive testing system for concrete damage evolution process in water environment, characterized in that: include: Concrete specimen module, external crack evolution module, internal damage failure module and comprehensive test module; The concrete specimen module is used to obtain the concrete specimen; The external crack evolution module is used to obtain the evolution process of concrete external cracks; The internal damage failure module is used to determine the internal damage failure mode of concrete; The comprehensive test module is used to complete a comprehensive test according to the concrete external crack evolution process and the concrete internal damage failure mode.

8. A comprehensive testing system for concrete damage evolution process in water environment according to claim 7, characterized in that: The concrete specimen is filled with strain sensing optical fiber, and the surface of the concrete specimen is pasted with strain gauges, wherein the strain sensing optical fiber is used to obtain the damage position inside the concrete, and the strain gauge is used to accurately measure and obtain the strain change curve of the surface of the concrete specimen.

9. The comprehensive testing system for concrete damage evolution process in water environment according to claim 7 is characterized in that: The external crack evolution module includes: an image acquisition unit, a correlation calculation unit and a surface field calculation unit; The image acquisition unit is used to acquire the speckle image and grayscale image of the concrete specimen; The correlation calculation unit is used to obtain the correlation between the reference image sub-region and the target image sub-region; The surface field calculation unit is used to obtain the displacement field and strain field of the surface deformation of the concrete specimen.

10. The comprehensive testing system for concrete damage evolution process in water environment according to claim 7, characterized in that: The internal damage failure module includes: a damage location module and a damage degree module; The damage location module is used to obtain the damage location inside the concrete; The damage degree module is used to determine the damage degree of concrete according to the damage location.

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