A method for determining the mechanical strength of concrete based on ultrasound

Abstract

The present invention belongs to the technical field of concrete mechanical strength determination, and specifically discloses a concrete mechanical strength determination method based on ultrasound, which includes: making each test sample and detecting its structural data; performing ultrasonic detection on the test sample, recording each propagation time and detection environment data; judging whether to perform ultrasonic detector calibration, and if it is judged to perform calibration, performing ultrasonic detector calibration; building a concrete sample mechanical strength assessment model; confirming the number of test points to be set, and performing ultrasonic detection on the concrete component to be measured; setting a test compensation factor, and then confirming the measured mechanical strength of the concrete component to be measured, and outputting it. The present invention fully considers the individual differences of concrete characteristics and components, comprehensively considers the influence of various factors on strength, improves the accuracy, reliability and effectiveness of concrete mechanical strength determination, and can better meet actual engineering needs.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete mechanical strength determination, and in particular, relates to a method for determining concrete mechanical strength based on ultrasound. Background Art

[0002] Concrete is one of the most widely used building materials in modern construction projects. It has many advantages, such as abundant raw materials, low cost, high compressive strength, and good durability. The mechanical strength of concrete is a key indicator of its quality. The accuracy of its mechanical strength determination is crucial to the safety and durability of the project.

[0003] Prior art, such as a system for predicting the strength of concrete at a construction site disclosed in the Chinese invention patent application with application number 202010346759.0, includes: a temperature and humidity sensor, a data center, and a user terminal. The temperature and humidity sensor is connected to the Internet, and monitors and transmits real-time temperature and humidity data inside the concrete. The data center is connected to the Internet, and is used to store real-time temperature and humidity data inside the concrete under two environments obtained from the Internet, as well as concrete mix ratio information and concrete strength information manually input from the user terminal, and calculates the concrete strength prediction results under the on-site construction environment through the concrete strength prediction system software, thereby meeting the monitoring needs of the concrete structure strength of high-rise or super-high-rise buildings.

[0004] Prior art, such as a concrete solid structure construction cycle control system disclosed in the Chinese invention patent application with application number 202010429030.X, includes a data acquisition instrument, a cloud storage server, an input end, a cloud computing server, an output end, and construction equipment. The early mechanical parameters of the concrete material collected by the data acquisition instrument are imported into the cloud storage server, and a database of early mechanical parameters of the concrete material is established. At the same time, the construction unit inputs the risk index threshold R' through the input end, and the cloud computing server extracts the early mechanical parameter data of the concrete in the cloud storage server based on the received risk index threshold R', and determines the safe construction age T' of the structure accordingly. The output end outputs the safe construction age T' and generates a construction rhythm control instruction to control the construction rhythm of the construction equipment, so that the overall strength of the concrete structure can be quickly determined in the on-site construction environment.

[0005] With regard to the above technical solutions, it is obvious that the current determination of concrete mechanical strength still has the following deficiencies: 1. The factors considered in the determination of concrete mechanical strength are relatively single, and there is a lack of comprehensive consideration of multiple factors. The mechanical strength of concrete is a physical quantity that is interactively affected by multiple complex factors. The lack of comprehensive consideration will lead to poor accuracy of the determination results, and thus the representativeness and authenticity of the determination results cannot be guaranteed.

[0006] 2. The accuracy of the equipment monitoring data was not further verified and corrected. In a complex construction site environment, the stability of the monitoring equipment may be affected, resulting in inaccurate monitored data, which in turn affects the effectiveness of the concrete strength prediction results.

[0007] 3. The difference between the test samples and the actual concrete components is not taken into account, and thus the reference value of the concrete strength prediction results cannot be guaranteed. Summary of the invention

[0008] In view of this, in order to solve the problems raised in the above background technology, a method for determining the mechanical strength of concrete based on ultrasound is proposed.

[0009] The purpose of the present invention can be achieved through the following technical solutions: The present invention provides a method for determining the mechanical strength of concrete based on ultrasound, the method comprising: S1, test component preparation: based on the current actual concrete mix ratio, standard concrete specimens of different ages are made as test samples, and their structural data are detected.

[0010] S2. Test component detection: Start the ultrasonic detector to emit pulses multiple times at each test point position pre-set on each test sample, and record each propagation time and test environment data.

[0011] S3, detection and calibration confirmation: import the data detected in step S2, determine whether to calibrate the ultrasonic detector, and if it is determined to be calibrated, calibrate the ultrasonic detector.

[0012] S4. Strength measurement model construction: Build a concrete sample mechanical strength assessment model.

[0013] S5. Actual component information detection: import the age of the concrete component to be measured, and detect the structural data and environmental data of the concrete component to be measured, and then confirm the number of test points to be set. At the same time, start the ultrasonic detector to emit pulses based on each test point of the concrete component to be measured, and record the propagation time.

[0014] S6. Concrete component data analysis: The measured mechanical strength of each test point of the concrete component to be measured is evaluated by the concrete sample mechanical strength evaluation model, and based on the structural data and environmental data, a test compensation factor is set to confirm the measured mechanical strength of the concrete component to be measured.

[0015] S7. Test result output: output the measured mechanical strength of the concrete component to be measured.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention prepares test components by making standard specimens of different ages, performs ultrasonic testing on the test specimens and the actual components to be measured and records relevant data, builds a mechanical strength evaluation model and sets compensation factors based on component structure, environment and other data, and finally outputs the measured mechanical strength. This can more systematically and comprehensively consider the influence of various factors, improve the accuracy and reliability of concrete mechanical strength determination, and better adapt to actual engineering needs.

[0017] (2) The present invention effectively solves the problem of the current lack of further verification and correction of the accuracy of the equipment monitoring data by determining whether to calibrate the ultrasonic detector and calibrating the ultrasonic detector when it is determined to be calibrated, thereby ensuring the stability of the monitoring equipment and the accuracy of the corresponding inspection data of the monitoring equipment, thereby providing a strong guarantee for the effectiveness of the concrete strength prediction results.

[0018] (3) The present invention constructs a concrete sample mechanical strength assessment model by taking into account the testing environment and the age of concrete construction, which effectively solves the problem of a single factor being considered in the current determination of concrete mechanical strength, realizes comprehensive consideration of multiple factors, and further ensures the accuracy of subsequent concrete mechanical strength determination results. At the same time, it also ensures the representativeness and authenticity of subsequent concrete mechanical strength determination results.

[0019] (4) When constructing a mechanical strength assessment model for concrete specimens, the present invention sets a mechanical environment assessment compensation factor and a comprehensive assessment compensation factor by combining the structural data of the test specimens and the detection environment data. This can make the assessment result closer to the actual strength and dynamically adjust the strength assessment according to the actual environmental conditions, thereby improving the reliability of the assessment and enhancing the versatility of the model and its applicability to different environmental conditions.

[0020] (5) The present invention sets the test compensation factor according to the structural data and environmental data of the concrete component to be measured, thereby fully considering the difference between the test sample and the actual concrete component, thereby further ensuring the reference value of the concrete strength prediction result. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 The present invention is a schematic flow chart of the steps for implementing the method.

[0023] Figure 2 This is a schematic diagram of the implementation process of step S3 of the present invention.

[0024] Figure 3 It is a schematic diagram of the process of building a concrete sample mechanical strength evaluation model according to the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1 As shown, the present invention provides a method for determining the mechanical strength of concrete based on ultrasound, the method comprising: the method comprising: S1, test component preparation: based on the current actual concrete mix ratio, standard concrete specimens of different ages are made as test specimens, and their structural data are detected.

[0027] S2. Test component detection: Start the ultrasonic detector to emit pulses multiple times at each test point position pre-set on each test sample, and record each propagation time and test environment data.

[0028] Please participate Figure 2 As shown, S3, detection and calibration confirmation: import the data detected in step S2, determine whether to calibrate the ultrasonic detector, and if it is determined to be calibrated, calibrate the ultrasonic detector.

[0029] S4. Strength measurement model construction: Build a concrete sample mechanical strength assessment model.

[0030] S5. Actual component information detection: import the age of the concrete component to be measured, and detect the structural data and environmental data of the concrete component to be measured, and then confirm the number of test points to be set. At the same time, start the ultrasonic detector to emit pulses based on each test point of the concrete component to be measured, and record the propagation time.

[0031] S6. Concrete component data analysis: The measured mechanical strength of each test point of the concrete component to be measured is evaluated by the concrete sample mechanical strength evaluation model, and based on the structural data and environmental data, a test compensation factor is set to confirm the measured mechanical strength of the concrete component to be measured.

[0032] S7. Test result output: output the measured mechanical strength of the concrete component to be measured.

[0033] The embodiment of the present invention prepares test components by making standard specimens of different ages, performs ultrasonic testing on the test specimens and the actual components to be measured and records relevant data, builds a mechanical strength evaluation model and sets compensation factors in combination with component structure, environment and other data, and finally outputs the measured mechanical strength. It can more systematically and comprehensively consider the influence of various factors, improve the accuracy and reliability of concrete mechanical strength judgment, and better adapt to actual engineering needs.

[0034] Regarding step S1, the structural data are the detection values ​​corresponding to each structural monitoring indicator.

[0035] In a specific embodiment, the structural monitoring indicators include but are not limited to surface finish, the number of defects and the area of ​​each defect.

[0036] For example, the number of defects and the area of ​​each defect can be detected by a camera on each surface of the standard concrete specimen, and image recognition technology can be used to identify whether each surface has defects such as honeycombs, rough surfaces, cracks, etc. If these defects exist, their number and area are recorded.

[0037] Understandably, honeycomb refers to the local looseness of concrete, with gaps between stones, like a honeycomb, and pitting refers to the numerous small pits on the surface of concrete. In a specific embodiment, image recognition technology is a relatively mature technology, and its specific recognition process will not be repeated here.

[0038] It should be added that the detection methods of surface finish include but are not limited to the roughness comparison sample method, the surface profiler method and the optical interference method. Understandably, the specific detection process of surface finish is as follows: 1) Roughness comparison sample method: First, obtain a set of suitable roughness comparison samples. The roughness range of these samples should cover the roughness conditions that may occur in concrete specimens. Then, under sufficient light, the surface of the specimen is compared in parallel with the surface of the sample. Observe which sample the texture and peaks and valleys of the surface of the specimen are closest to, so as to determine its surface finish. For example, if the surface of the specimen looks similar to the sample marked as Ra3.2μm, then it can be roughly considered that the arithmetic mean roughness of the surface of the specimen is Ra3.2μm, that is, the reciprocal of the arithmetic mean roughness is taken as the surface smoothness.

[0039] 2) Surface profilometer method: Select a surface profilometer with appropriate range and accuracy, and gently place the stylus of the instrument on the test area on the surface of the concrete specimen. The test area should be representative to avoid measuring at local locations with obvious defects or unevenness. Start the instrument and allow the stylus to pass a certain length, such as 4-5mm, on the surface of the specimen at a certain speed. The instrument will record the displacement data of the stylus, and through the supporting software or internal calculation module, the arithmetic mean roughness Ra and root mean square roughness Rq can be obtained. The arithmetic mean roughness (Ra) is the arithmetic mean of the absolute value of the profile deviation within the sampling length, where , , is the sampling length, The contour curve function formed by the stylus displacement is then As a surface light section, is a natural constant.

[0040] Understandably, the stylus moves at a certain speed, usually set according to the instrument requirements and the surface conditions of the test piece, such as 0.5-1 mm / s, and travels a certain length on the surface of the test piece, specifically 4-5 mm.

[0041] 3) Optical interference method: Use an optical interference microscope or similar instrument to place the specimen on the stage and adjust the position. Focus the surface of the specimen so that the interference fringes are clearly displayed. Then, obtain the image data of the interference fringes through the image acquisition and analysis system of the instrument. According to the interference theory of light, the spacing of the interference fringes is related to the surface height difference. For example, for double-beam interference, the fringe spacing is With wavelength Height difference between surfaces The relationship is: ,in, is the number of fringes. By processing and calculating the fringes image, we can get the quantitative index of surface roughness, such as the maximum height difference Rz. As a surface light section.

[0042] It should be added that the above involves multiple surfaces and is described using one surface as an example. For ease of analysis, the average of the smoothness of the surface where the test point is located and the surface opposite to the test point can be selected as the surface smoothness of the concrete standard specimen.

[0043] Regarding step S2, it is necessary to add that before conducting ultrasonic testing, a pair of ultrasonic transducers need to be installed at predetermined measuring points, and the axis of the transducer should be consistent with the test direction. Apply an appropriate amount of coupling agent, such as vaseline, butter or special ultrasonic coupling agent, between the transducer and the concrete test surface. The thickness of the coupling agent should be controlled at 2-3mm. The transducer and the test surface should be closely fitted with appropriate pressure to reduce energy loss during ultrasonic propagation.

[0044] The detection environment data includes, but is not limited to, the temperature and humidity at each detection time point.

[0045] Regarding step S3, it is determined whether to calibrate the ultrasonic detector, including: S31, based on each propagation time, calculate the propagation speed of the ultrasonic wave in the concrete corresponding to each propagation, and import it into the set concrete strength-ultrasonic wave speed relationship curve, and output the measured concrete strength of each test point corresponding to each test sample at each age at each propagation.

[0046] S32, calculating the standard deviation of the measured concrete strength of each test sample at the same age corresponding to the same test point at each propagation, recording the calculation result as the propagation strength difference, and confirming the test deviation of the test samples at each age.

[0047] S33. Analyze the interference degree of the detection environment based on the recorded detection environment data.

[0048] S34, determine whether the detection environment interference is 0, if it is 0, determine whether there is a test deviation of the test sample at a certain age that is greater than the set reference value, if so, perform calibration as the judgment result, if not, do not perform calibration as the judgment result.

[0049] S35, if it is not 0, the detection environment interference degree is matched and compared with the set detection environment interference degree corresponding to each test deviation degree to obtain a matching test deviation degree.

[0050] S36. If the test deviation of the test sample at a certain age is greater than the matching test deviation, calibration will be performed as a judgment result. Otherwise, no calibration will be performed as a judgment result.

[0051] The embodiment of the present invention effectively solves the problem that the accuracy of the equipment monitoring data is not further verified and corrected by judging whether to calibrate the ultrasonic detector and calibrating the ultrasonic detector when it is judged to be calibrated, thereby ensuring the stability of the monitoring equipment and the accuracy of the corresponding inspection data of the monitoring equipment, thereby providing a strong guarantee for the effectiveness of the concrete strength prediction results.

[0052] Understandably, the specific calculation process of calculating the propagation velocity of the ultrasonic wave in the concrete corresponding to each propagation in step S31 is as follows: according to the ultrasonic wave propagation time t at the test point and the actual propagation distance L between the transducers, in mm, the propagation velocity v of the ultrasonic wave in the concrete is calculated according to the formula v=L / t, in km / s. The propagation distance L can be determined according to the geometric dimensions for regular test pieces, and can be measured by tools such as a rangefinder for irregular components.

[0053] It should be noted that when using the relationship curve, it should be ensured that the tested concrete is similar or comparable to the concrete when the curve was established in terms of raw materials, mix ratio, construction technology, etc. Otherwise, the relationship curve needs to be revised or a relationship curve suitable for the current concrete needs to be re-established. For example, if the current concrete uses a new type of admixture, and the original curve does not involve sample data on the effect of the admixture on ultrasonic propagation and strength, then the admixture may change the internal microstructure and hardening characteristics of the concrete, resulting in changes in the relationship between ultrasonic propagation velocity and strength. At this time, it is necessary to re-produce a series of standard test specimens containing different amounts of the admixture, measure ultrasonic wave velocity and compressive strength of these test specimens at different ages, and revise the original relationship curve based on the new data points or re-fit a strength-wave velocity relationship curve specifically for this type of concrete containing the new admixture, and perform substitution analysis.

[0054] For example, the source or gradation of aggregates used in the current concrete is very different from when the original curve was established. The hardness, shape, porosity and other characteristics of the aggregate will have an important impact on ultrasonic propagation, which in turn affects the corresponding relationship between strength and wave velocity. In this case, it is necessary to collect new aggregate samples to make multiple groups of test specimens with different strength grades and ages, re-measure their ultrasonic propagation characteristics and compressive strength, and by comparing and analyzing the new and old data, determine how to adjust the original relationship curve to adapt to the impact of this aggregate change. If the difference is too large, the relationship curve needs to be rebuilt to ensure that the mechanical strength of concrete can be accurately inferred from the ultrasonic wave velocity.

[0055] When the original relationship curve needs to be adjusted due to aggregate changes, the relationship curve can be corrected according to the following detailed steps: J1. Determine the apparent density, bulk density, porosity, crushing index, hardness, needle-like particle content and adhesion with cement paste of the new aggregate.

[0056] Understandably, the above characteristics will directly affect the density, uniformity and stress transfer mode of the internal structure of concrete, and further correlate the relationship between ultrasonic propagation velocity and mechanical strength.

[0057] J2. Use new aggregates and make standard test specimens of concrete of different ages, such as 7 days, 14 days, 28 days, etc., according to a concrete mix ratio framework similar to that when the original relationship curve was established.

[0058] Understandably, during the test sample production process, raw material measurement, mixing process, molding method and curing conditions are strictly controlled to ensure the accuracy and comparability of the data.

[0059] J3. Apply a suitable coupling agent to the test point of the test sample and place the ultrasonic transducer to emit ultrasonic pulses and accurately record the propagation time. Repeat the measurement for each test point multiple times, remove the abnormal values ​​and take the average value as the propagation time data of the point. At the same time, accurately calculate the ultrasonic propagation distance based on the size of the test sample, so as to obtain the propagation speed of ultrasonic waves in new aggregate concrete.

[0060] J4. Use a pressure testing machine to load the test specimen at a standard loading rate until it fails, record the failure load and calculate the compressive strength value.

[0061] J5. Compare and analyze the newly acquired ultrasonic propagation velocity data and compressive strength data with the data of the original relationship curve. Observe the difference between the new aggregate concrete and the concrete represented by the original curve at the same strength level or similar propagation velocity. If it is found that the new aggregate causes the overall ultrasonic propagation velocity to be higher or lower, and the corresponding strength value also changes accordingly, it is necessary to determine the direction and amplitude of the adjustment.

[0062] In a specific embodiment, a common adjustment method for determining the direction and magnitude of adjustment is based on linear regression analysis. Assume that the relationship of the original relationship curve is , is the compressive strength, is the ultrasonic wave velocity, and a new straight line equation is fitted through the new data , , , and are constants, respectively. and , and For example, if Compare If the new aggregate has a large influence on the strength of the ultrasonic wave velocity, it means that the new aggregate has changed the influence of the ultrasonic wave velocity on the strength. When using the original curve to calculate the strength, it is necessary to multiply it by a corresponding correction coefficient to adjust it. More complex fitting methods such as polynomial regression can also be used for adjustment. If the influence of the new aggregate presents nonlinear characteristics, such as a greater influence on the strength in certain wave velocity ranges and a smaller influence in other ranges, polynomial regression can better capture this complex relationship. By adjusting the coefficients of the polynomial to correct the original relationship curve, it can more accurately reflect the relationship between the strength of the new aggregate concrete and the ultrasonic wave velocity, so as to achieve an accurate determination of the mechanical strength of the concrete.

[0063] Among them, the specific steps for confirming the correction coefficient are: 1. Value correction factor: calculation Value correction factor , ,if , which means that the new aggregate makes the ultrasonic wave velocity contribute more to the strength than before. For example, , ,but When using the original relationship curve to estimate the strength of new aggregate concrete, for a given ultrasonic wave velocity, the original calculated strength needs to be multiplied by 1.2 to make a correction. , indicating that the new aggregate reduces the effect of wave velocity on strength. , ,but At this time, the intensity calculated by the original curve should be multiplied by 0.8 for correction.

[0064] two, Value correction factor: calculated value Value correction factor , , The change in the value reflects the change in the intensity estimate when the wave speed is. , the intercept increases, meaning that the overall intensity estimate improves in regions with lower wave speeds. For example, , ,but This indicates that when the wave speed is low, the original calculated intensity needs to be multiplied by 1.2 to correct it. , the intercept decreases, and the intensity estimate decreases in the region of lower wave speed. , ,but At this time, in the area with lower wave speed, the intensity calculated by the original curve should be multiplied by 0.8 for correction.

[0065] In practical applications, for a given ultrasonic wave velocity , , the relationship formula of the corrected original relationship curve is , and then comprehensively considered Value and In this way, the original relationship curve is corrected using the data obtained from the test specimens of new aggregate concrete, so that the mechanical strength of new aggregate concrete can be determined more accurately based on the ultrasonic wave velocity.

[0066] Understandably, age refers to the time that concrete has experienced since the addition of water and mixing. Age is a key factor in the development of concrete performance. As age increases, a series of complex hydration reactions occur inside the concrete. Mineral components in cement, such as tricalcium silicate and dicalcium silicate, react with water to produce products such as hydrated calcium silicate gel, which gradually fill the pores inside the concrete and make the structure of the concrete denser. For the mechanical strength of concrete, the length of age directly affects the development of strength. Generally speaking, in the early stage, such as within 7 days, the strength of concrete increases rapidly. As time goes by, the growth rate of strength gradually slows down, but there will still be a certain degree of growth over a long period of time, such as several years or even decades. For example, at the age of 28 days, the strength of ordinary concrete can reach most of the design strength grade, usually between 70% and 100%, depending on factors such as the mix ratio. After that, the strength will continue to grow slowly, so the age of the concrete sample needs to be considered when conducting concrete mechanical strength tests.

[0067] Understandably, the step S32 confirms the test deviation of the test samples at each age, including: E1, recording the test points whose propagation intensity difference is greater than the set first reference propagation intensity difference as deviation points, and counting the number of deviation points of each test sample at each age.

[0068] E2. If the number of deviation points of each test sample at a certain age is less than or equal to 1, and the propagation intensity difference of the deviation points of each test sample is less than or equal to the second reference propagation intensity difference, 0 is taken as the test deviation of the test sample at this age. If the propagation intensity difference of the deviation points in each test sample is greater than the second reference propagation intensity difference, the maximum value is selected from the propagation intensity difference of the deviation points of each test sample, which is recorded as ,Will As the test deviation of the test sample at this age, To set the first reference propagation intensity difference.

[0069] E3. If the number of deviation points of a test sample at a certain age is greater than 1, the ratio of the number of deviation points to the total number of test points is statistically calculated and recorded as the deviation ratio. The maximum value is selected from the deviation ratios of each test sample at this age as the test deviation degree of the test sample at this age, thereby obtaining the test deviation degree of the test samples at each age.

[0070] In a specific embodiment, the first reference propagation strength difference can be set to 5% of the corresponding mean of the measured concrete strength of each propagation, and the second reference propagation strength difference can be set to 10% of the corresponding mean of the measured concrete strength of each propagation.

[0071] Understandably, the analysis of the detection environment interference in step S33 includes: extracting the temperature and humidity at each detection time point from the detection environment data, calculating the standard deviation respectively, and using the calculation results as the temperature fluctuation and humidity fluctuation respectively, and recording them as and .

[0072] The temperature at each detection time point is averaged and recorded as , and at the same time, the maximum humidity is selected from the humidity at each detection time point and recorded as .

[0073] based on , , and Define each evaluation variable and record it as variable ,variable ,variable and variables , calculate the interference degree of the detection environment , .

[0074] It should be added that , , , ,in, and The temperature fluctuation and humidity fluctuation of the reference are set respectively. , and They are the suitable temperature, allowable temperature difference and suitable humidity for setting reference respectively.

[0075] In a specific embodiment, The value can be 5℃. The value can be 10%. The value can be 20℃. The value can be 15℃. The value can be 80%.

[0076] Understandably, what needs to be added about step S3 is that if it is determined that the ultrasonic detector needs to be calibrated, it is first calibrated using a standard calibration block. The material and acoustic properties of the standard calibration block are known, and its ultrasonic propagation time has a precise calibration value. Place the transmitting transducer and the receiving transducer at the specified position of the standard calibration block, and adjust the relevant parameters of the instrument such as gain, time zero, etc. according to the steps in the instrument operation manual, so that the propagation time measured by the instrument is consistent with the calibration value of the calibration block, and the error is controlled within a very small range, for example, ±0.1μs. During the calibration process, ensure that the transducer is in close contact with the surface of the calibration block, the coupling agent is evenly applied, and the environmental conditions are stable. After the calibration is completed, measure the test sample again to verify the calibration effect and ensure the accuracy and reliability of the propagation time measurement.

[0077] See also Figure 3 As shown, the construction of a concrete sample mechanical strength assessment model in step S4 includes: S41, calculating the mean of the measured concrete strength of each test point corresponding to each test sample at each age at each transmission, obtaining the average measured concrete strength of each test point corresponding to each test sample at each age, and screening out the minimum average measured concrete strength of each test sample at each age.

[0078] S42. Calculate the standard deviation of the minimum measured concrete strength of different test samples at the same age to obtain the difference in the corresponding measured values ​​of the test samples at each age.

[0079] S43. Set environmental assessment compensation factors based on the detected environmental data .

[0080] S44. Based on the structural data, set the comprehensive evaluation compensation factor of the test samples at each age.

[0081] S45. Extract the mechanical strength evaluation model of concrete samples at various ages from the database. If the corresponding measured value difference of the test samples at a certain age is less than or equal to the set measured value difference, modify the mechanical strength evaluation model of concrete samples at that age based on the environmental assessment compensation factor.

[0082] S46. If the difference of the measured values ​​of the test samples at a certain age is greater than the set difference of the measured values, the mechanical strength evaluation model of the concrete samples at that age is modified based on the comprehensive evaluation compensation factor of the test samples at that age.

[0083] S47. Integrate the revised mechanical strength assessment models of concrete samples at various ages to obtain a mechanical strength assessment model for concrete samples.

[0084] The embodiment of the present invention builds a concrete sample mechanical strength evaluation model taking into account the detection environment and the age of concrete construction, which effectively solves the problem of a single factor being considered in the current determination of concrete mechanical strength, realizes comprehensive consideration of multiple factors, and further ensures the accuracy of subsequent concrete mechanical strength determination results, while also ensuring the representativeness and authenticity of subsequent concrete mechanical strength determination results.

[0085] Understandably, setting the environmental assessment compensation factor in step S43 includes: The setting of the environmental assessment compensation factor includes: T1, extracting the temperature and humidity at each detection time point from the detection environment data, calculating the average humidity at each detection time point, and obtaining the average humidity, which is recorded as .

[0086] T2, average humidity The upper limit of the reference humidity range is set For comparison, if it exceeds the upper limit of the set reference humidity range, As the environmental assessment compensation factor, .

[0087] T3, if the average humidity Lower than the lower limit of the set reference humidity range , then As the environmental assessment compensation factor, , and the environmental assessment compensation factor is obtained by setting , The value is or .

[0088] In a specific embodiment, and The values ​​can be 40% and 60% respectively.

[0089] It should be added that sufficient water can ensure that the cement particles are fully hydrated, so that the pores inside the concrete are filled with hydration products, thereby improving the density of the concrete. At the same time, high humidity can reduce the self-drying shrinkage of concrete and avoid cracks caused by shrinkage. In a high humidity environment, the results of concrete strength measurement are usually too large. This is because concrete can be fully hydrated under good humidity conditions to form a denser structure, thus showing higher strength in strength tests. A low humidity environment will cause concrete to lose water. It will cause concrete to shrink by self-drying. As a result, the results of concrete strength measurement are usually too small.

[0090] It should also be added that since temperature has little instantaneous effect on concrete specimens and under normal circumstances the temperature rarely changes suddenly or seriously exceeds the test range, the influence of temperature is ignored when setting the environmental assessment compensation factor.

[0091] It can be understood that the comprehensive evaluation compensation factor for the test samples at each age is set in step S44, including: F1, extracting the detection value corresponding to each structural monitoring indicator from the structural data, and comparing it with the appropriate detection value range corresponding to each structural monitoring indicator, counting the number of structural monitoring indicators whose detection values ​​are within the appropriate detection value range corresponding to the corresponding structural monitoring indicator, and dividing it by the total number of structural monitoring indicators to obtain the compliance ratio of each test sample.

[0092] F2. Compare the compliance ratio of each test sample with the set reference compliance ratio, count the number of test samples whose compliance ratio is greater than the set reference compliance ratio, and divide it by the total number of test samples to obtain the structural consistency of the test samples at each age, recorded as , Indicates the age number, .

[0093] F3. Set the comprehensive evaluation compensation factor of the test samples at different ages , , To set the structural fit of the reference.

[0094] It should be added that The specific value can be 0.6.

[0095] When building a mechanical strength assessment model for concrete specimens, the embodiment of the present invention sets a mechanical environment assessment compensation factor and a comprehensive assessment compensation factor in combination with the structural data of the test specimens and the detection environment data, so that the assessment result can be closer to the actual strength. At the same time, the strength assessment can be dynamically adjusted according to the actual environmental conditions, thereby improving the reliability of the assessment and enhancing the versatility of the model and its applicability to different environmental conditions.

[0096] The step S5 confirms the setting of the number of test points, including: S51, extracting the test values ​​corresponding to each structural monitoring index from the structural data of the concrete component to be measured, and obtaining the structural conformity of the concrete component to be measured by the same statistical method of the structural conformity of the test samples at each age, which is recorded as .

[0097] S52, Statistics setting test points , , The default number of test points for the specified concrete element is set. To set the reference structural fit, The round-up symbol.

[0098] In a specific embodiment, the reference structural consistency can be specifically set to a value of 0.7.

[0099] The setting of the test compensation factor in step S6 includes: extracting the humidity at each test time point from the environmental data, and evaluating the compensation factor according to the environment. The setting method is similar to setting the current environment compensation factor .

[0100] Based on the structural data of the concrete components to be measured, the compliance ratio of the concrete components to be measured is calculated and recorded as .

[0101] like and Established, 0 is used as the test compensation factor, is the difference in the environmental compensation factor for setting the reference, To set the reference standard ratio, otherwise As the test compensation factor, denoted as , and thus obtain the test compensation factor , The value is or 0.

[0102] It should be added that after confirming the number of test points, the position of each test point should also be confirmed. Generally, the test points are evenly arranged on two opposite sides. The distance between the test points should generally not be less than 200mm, and should not be less than 100mm from the edge of the sample to ensure that the ultrasonic propagation path can effectively reflect the overall condition inside the sample. At the same time, avoid obvious defects on the surface of the sample, such as honeycombs, pockmarks, etc., as well as corners, because these areas may cause abnormal reflection or scattering of the ultrasonic wave, affecting the accuracy of the propagation time measurement. For example, for a cubic sample with a side length of 150mm, 3-5 test points can be arranged diagonally on each side.

[0103] In a specific embodiment, The value can be 0.1. The value can be 0.6.

[0104] Regarding confirming the measured mechanical strength of the concrete component to be measured in step S6, it includes: calculating the standard deviation of the measured mechanical strength of each test point, if the standard deviation calculation result is within the set range, calculating the mean of the measured mechanical strength of each test point, and using the calculation result as the benchmark measured mechanical strength.

[0105] If the calculated standard deviation exceeds the set range, the minimum value is selected from the measured mechanical strengths of each test point and used as the benchmark for measuring the mechanical strength.

[0106] The benchmark mechanical strength is recorded as ,Will As a measure of the mechanical strength of concrete components.

[0107] The embodiment of the present invention sets the test compensation factor according to the structural data and environmental data of the concrete component to be measured, thereby fully considering the difference between the test sample and the actual concrete component, thereby further ensuring the reference value of the concrete strength prediction result.

[0108] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, they shall all fall within the protection scope of the present invention.

Claims

1. A method for determining the mechanical strength of concrete based on ultrasound, characterized in that: The method includes: S1. Preparation of test components: based on the current actual concrete mix ratio, standard concrete specimens of different ages are made as test specimens, and their structural data are tested; S2. Test component detection: Start the ultrasonic detector to transmit pulses multiple times at each test point position pre-set on each test sample, and record each propagation time and test environment data; S3, detection and calibration confirmation: import the data detected in step S2, determine whether to calibrate the ultrasonic detector, and if it is determined to be calibrated, calibrate the ultrasonic detector; The determining whether to perform ultrasonic detector calibration includes: Based on each propagation time, the propagation velocity of the ultrasonic wave in the concrete corresponding to each propagation is calculated, and imported into the set concrete strength-ultrasonic wave velocity relationship curve, and the measured concrete strength of each test point corresponding to each test sample at each age at each propagation is output; Calculate the standard deviation of the measured concrete strength of each test sample at the same test point at each propagation at the same age, record the calculation result as the propagation strength difference, and confirm the test deviation of the test samples at each age; Analyze the interference degree of the testing environment based on the recorded testing environment data; Determine whether the detection environment interference is 0. If it is 0, determine whether the test deviation of the test sample at a certain age is greater than the set reference value. If so, calibration will be performed as the judgment result. If not, no calibration will be performed as the judgment result. If it is not 0, the detection environment interference degree is matched and compared with the set detection environment interference degree corresponding to each test deviation degree to obtain the matching test deviation degree; If the test deviation of the test sample at a certain age is greater than the matching test deviation, calibration will be performed as the judgment result, otherwise, no calibration will be performed as the judgment result; S4. Strength determination model construction: Build a concrete sample mechanical strength assessment model; S5. Actual component information detection: import the age of the concrete component to be measured, and detect the structural data and environmental data of the concrete component to be measured, and then confirm the number of test points to be set, and at the same time start the ultrasonic detector to emit pulses based on each test point of the concrete component to be measured, and record the propagation time; S6. Concrete component data analysis: evaluating the measured mechanical strength of each test point of the concrete component to be measured by using the concrete sample mechanical strength evaluation model, and setting a test compensation factor based on the structural data and environmental data, thereby confirming the measured mechanical strength of the concrete component to be measured; S7. Test result output: output the measured mechanical strength of the concrete component to be measured.

2. The method for determining the mechanical strength of concrete based on ultrasound according to claim 1, characterized in that: The determination of the test deviation of the test samples at each age includes: The test points whose propagation intensity difference is greater than the set first reference propagation intensity difference are recorded as deviation points, and the number of deviation points of each test sample at each age is counted; If the number of deviation points of each test sample at a certain age is less than or equal to 1, and the propagation intensity difference of the deviation points of each test sample is less than or equal to the second reference propagation intensity difference, 0 is taken as the test deviation of the test sample at this age. If the propagation intensity difference of the deviation points in each test sample is greater than the second reference propagation intensity difference, the maximum value is selected from the propagation intensity difference of the deviation points of each test sample, which is recorded as ,Will As the test deviation of the test sample at this age, To set the first reference propagation intensity difference, is a natural constant; If the number of deviation points of a test sample at a certain age is greater than 1, the ratio of the number of deviation points to the total number of test points is statistically calculated and recorded as the deviation ratio. The maximum value is selected from the deviation ratios of each test sample at that age as the test deviation degree of the test sample at that age, thereby obtaining the test deviation degree of the test samples at each age.

3. The method for determining the mechanical strength of concrete based on ultrasound according to claim 2, characterized in that: The analyzing and detecting environmental interference degree comprises: The temperature and humidity at each detection time point are extracted from the detection environment data, and the standard deviation is calculated respectively. The calculation results are used as the temperature fluctuation and humidity fluctuation, and are recorded as and ; The temperature at each detection time point is averaged and recorded as , and at the same time, the maximum humidity is selected from the humidity at each detection time point and recorded as ; based on , , and Define each evaluation variable and record it as variable ,variable ,variable and variables , calculate the interference degree of the detection environment , ;in , , , , and The temperature fluctuation and humidity fluctuation of the reference are set respectively. , and They are the suitable temperature, allowable temperature difference and suitable humidity for setting reference respectively.

4. The method for determining the mechanical strength of concrete based on ultrasound according to claim 3, characterized in that: The construction of the concrete sample mechanical strength evaluation model comprises: The measured concrete strength of each test point of each test sample at each age is averaged and calculated to obtain the average measured concrete strength of each test point of each test sample at each age, and the minimum average measured concrete strength of each test sample at each age is screened out; The standard deviation of the minimum measured concrete strength of different test samples at the same age is calculated to obtain the difference in the corresponding measured values ​​of the test samples at different ages; Set environmental assessment compensation factors based on test environment data ; Based on the structural data, set the comprehensive evaluation compensation factor of the test samples at each age; Extract the mechanical strength evaluation model of concrete samples at various ages from the database. If the difference of the corresponding measured values ​​of the test samples at a certain age is less than or equal to the set measured value difference, the mechanical strength evaluation model of the concrete samples at that age is corrected based on the environmental assessment compensation factor. If the difference of the measured values ​​of the test samples at a certain age is greater than the set difference of the measured values, the mechanical strength evaluation model of the concrete samples at this age is modified based on the comprehensive evaluation compensation factor of the test samples at this age; The modified mechanical strength assessment models of concrete samples at different ages are integrated to obtain the mechanical strength assessment model of concrete samples.

5. The method for determining the mechanical strength of concrete based on ultrasound according to claim 4, characterized in that: The setting of the environmental assessment compensation factor includes: The temperature and humidity at each detection time point are extracted from the detection environment data, and the humidity at each detection time point is averaged to obtain the average humidity, which is recorded as ; The average humidity The upper limit of the reference humidity range is set For comparison, if it exceeds the upper limit of the set reference humidity range, As the environmental assessment compensation factor, ; If the average humidity Lower than the lower limit of the set reference humidity range , then As the environmental assessment compensation factor, , and the environmental assessment compensation factor is obtained by setting , The value is or .

6. The method for determining the mechanical strength of concrete based on ultrasound according to claim 4, characterized in that: The comprehensive evaluation compensation factors of the test samples at different ages are set, including: Extracting the detection value corresponding to each structural monitoring indicator from the structural data, and comparing it with the appropriate detection value interval corresponding to each structural monitoring indicator, counting the number of structural monitoring indicators whose detection values ​​are within the appropriate detection value interval corresponding to the corresponding structural monitoring indicator, and dividing it by the total number of structural monitoring indicators to obtain the compliance ratio of each test sample; The compliance ratio of each test sample is compared with the set reference compliance ratio, and the number of test samples whose compliance ratio is greater than the set reference compliance ratio is counted and divided by the total number of test samples to obtain the structural consistency of the test samples at each age, which is recorded as , Indicates the age number, ; Set the comprehensive evaluation compensation factor of the test samples at different ages , , To set the structural fit of the reference.

7. The method for determining the mechanical strength of concrete based on ultrasound according to claim 6, characterized in that: The confirmation and setting of the test points include: The detection values ​​corresponding to each structural monitoring index are extracted from the structural data of the concrete component to be measured, and the structural consistency of the concrete component to be measured is obtained by the same statistical method according to the statistical method of the structural consistency of the test samples at each age, which is recorded as ; Statistics setting test points , , The default number of test points for the specified concrete element is set. To set the reference structural stability, The round-up symbol.

8. The method for determining concrete mechanical strength based on ultrasound according to claim 6, characterized in that: The setting of the test compensation factor includes: Extract the humidity at each detection time point from the environmental data, and evaluate the compensation factor according to the environment The setting method is similar to setting the current environment compensation factor ; Based on the structural data of the concrete components to be measured, the compliance ratio of the concrete components to be measured is calculated and recorded as ; like and If true, the test compensation factor is 0. is the difference in the environmental compensation factor for setting the reference, To set the reference standard ratio, otherwise As the test compensation factor, denoted as , and thus obtain the test compensation factor , The value is or 0.

9. The method for determining concrete mechanical strength based on ultrasound according to claim 8, characterized in that: The step of confirming the measured mechanical strength of the concrete component to be measured comprises: The standard deviation of the measured mechanical strength of each test point is calculated. If the standard deviation calculation result is within the set range, the mean of the measured mechanical strength of each test point is calculated, and the calculation result is used as the benchmark mechanical strength; If the calculated standard deviation exceeds the set range, the minimum value is selected from the measured mechanical strength of each test point and used as the benchmark mechanical strength; The benchmark mechanical strength is recorded as ,Will As a measure of the mechanical strength of concrete components.

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