Method, device and system for detecting water seepage height in concrete impermeability test

Abstract

The present invention relates to the technical field of concrete impermeability detection, in particular to a method, device and system for detecting the water seepage height in a concrete impermeability test. A method for detecting the water seepage height in a concrete impermeability test proposed by this method utilizes the characteristic that when the water seepage height of concrete changes and it serves as the dielectric between the electrodes of a capacitor, the capacitance value will change with the water seepage height to test the water seepage height. The implementation of the present invention can complete the two tests of the step-by-step pressure method and the water seepage height method within the time of one experiment, can fully realize automatic detection without human intervention, will greatly save the test time of the water seepage height method, and improve work efficiency and the quality of detection data. The present invention solves the defects of complex operation and low efficiency in the prior art of the water seepage height method.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete impermeability detection, and in particular to a method, device and system for detecting the water seepage height in a concrete impermeability test. Background Art

[0002] The methods for concrete impermeability tests mainly include the water seepage height method and the step-by-step pressure method, which are used to detect the water penetration resistance of ordinary concrete.

[0003] For the water seepage height method, the production of specimens needs to follow specific standards. There are strict regulations on the maximum nominal size of aggregates, specimen size, flatness of the bearing surface, etc. The specimens are required to be cured under standard curing conditions until the specified age. Before the test, the specimens are sealed. The sides of the specimens need to be sealed with materials such as melted paraffin to ensure the accuracy of the test. The test process starts from 0.1 MPa, and the water pressure is increased by 0.1 MPa every 8 hours until water seepage occurs in 3 out of 6 specimens, and then the test is terminated. The specimens taken out from the impermeability tester are placed on a press, and two steel spacer bars with a diameter of 6 m should be placed along the diameter direction at the center of the upper and lower end faces of the specimens, and it should be ensured that they are in the same vertical plane. Then start the press and split the specimens into two halves along the longitudinal section. After the specimens are split, use a waterproof pen to trace the water marks. Place the trapezoidal plate on the split surface of the specimens, and use a steel ruler to measure the water seepage height values of 10 measuring points at equal intervals along the water marks. The readings should be accurate to 1 mm. When reading, if a certain measuring point is blocked by aggregates, the arithmetic mean of the water seepage heights near both ends of the aggregates can be used as the water seepage height of this measuring point.

[0004] The step-by-step pressure method is also used to determine the water penetration resistance of ordinary concrete. The production, curing and sealing treatment of specimens are the same as those of the water seepage height method. The test process starts from a low water pressure and gradually increases the water pressure. Each level of pressure is maintained for a certain period of time until the predetermined pressure is reached or obvious water seepage is observed. Record the water seepage situation at each level of pressure and the number of specimens that finally do not show water seepage to calculate the impermeability grade of the concrete.

[0005] Generally speaking, both the water seepage height method and the step-by-step pressure method can evaluate the impermeability performance of concrete. After the water seepage height method test is completed, use a press to split the specimens into two halves along the longitudinal section, and use a steel ruler to measure the water seepage height values of 10 measuring points at equal intervals along the water marks, which can accurately judge the water seepage situation of each specimen and has higher accuracy than the step-by-step pressure method.

[0006] However, after the water seepage height method test is completed, using a press to split the specimens into two halves along the longitudinal section and then evaluating the water seepage situation is a time-consuming and laborious task, which restricts the large-scale promotion of this method to a certain extent. Summary of the Invention

[0007] In order to overcome the defects of complex operation and low efficiency of the existing water seepage height method in the above-mentioned prior art, the present invention proposes a method for detecting the water seepage height in a concrete impermeability test, which realizes the rapid detection of the water seepage height, avoids the cumbersome process of splitting the specimen with a press for measurement, effectively saves time, and reduces costs.

[0008] A method for detecting the water seepage height in a concrete impermeability test proposed by the present invention takes the concrete specimen and the internal water seepage therein as the inter-electrode medium of a capacitor, arranges a capacitance sensor for clamping the concrete specimen around the concrete specimen, and the capacitance sensor is insulated from the concrete specimen; then calculates the water seepage height according to the capacitance value.

[0009] Preferably, it is applicable to a parallel plate capacitor, and when detecting, the parallel plate capacitor is arranged horizontally up and down to clamp the concrete specimen;

[0010] The method first combines a calibration sample to fit the relationship between the capacitance value of the concrete specimen and the water seepage height. The water seepage height calculated by combining the known capacitance value and the relationship is denoted as the fitted water seepage height value, and the water seepage height calculated by combining the known capacitance value and the theoretical formula is denoted as the theoretical water seepage height value; constructs a ratio change curve of the fitted water seepage height value and the theoretical water seepage height value at different capacitance values on the calibration sample;

[0011] Then uses a parallel plate capacitor to detect the concrete specimen to be tested, obtains the measured capacitance value, calculates the theoretical water seepage height value of the concrete specimen to be tested, and looks up the ratio change curve to obtain the target ratio corresponding to the measured capacitance value, and calculates the product of the target ratio and the theoretical water seepage height value of the concrete specimen to be tested as the detection result of the water seepage height of the concrete specimen to be tested.

[0012] Preferably, the relationship is expressed as: ; where a and b are parameters to be fitted, C is the capacitance value, h is the water seepage height.

[0013] Preferably, the theoretical formula is expressed as:

[0014] ;

[0015] where, is the theoretical water seepage height value; is the dielectric constant of the water seepage concrete; is the dielectric constant of the dry concrete; is the height of the specimen; is the area of the plate; C is the capacitance value.

[0016] Preferably, an annular capacitor is used to detect the capacitance value of the concrete specimen. The two clamping plates of the annular capacitor are symmetrically arranged on the left and right sides of the concrete specimen and clamp the concrete specimen. The seepage height detection model applicable to the annular capacitor is:

[0017] ;

[0018] Wherein, is the seepage height; is the dielectric constant of the seepage concrete; is the dielectric constant of the dry concrete; is the height of the specimen; is the measured capacitance value; is the opening angle of the annular capacitor; is the correction coefficient.

[0019] Preferably, the correction coefficient is obtained by fitting on the calibration sample.

[0020] Preferably, the opening angle has a value range of [85°, 89.5°].

[0021] A device for detecting the seepage height of a concrete impermeability test proposed by the present invention includes a capacitor structure, a capacitance testing instrument, and a computer; the computer stores a seepage height detection model corresponding to the capacitor structure. The capacitor structure uses the concrete specimen as a medium, and the capacitance testing instrument is used to detect the capacitance value of the capacitor structure. The computer obtains the capacitance value measured by the capacitance testing instrument and substitutes it into the seepage height detection model for calculating the seepage height;

[0022] When the capacitor structure is a parallel-plate capacitor composed of two plate members, the seepage height detection model is:

[0023] ;

[0024] Wherein, is the seepage height; is the theoretical value of the seepage height calculated by substituting the detected capacitance value into the theoretical model; let C - f s is the ratio of the fitting value to the theoretical value of the seepage height of the concrete specimen under different capacitance values f s relationship correction function; f s,C represents the correction function C - f s the ratio corresponding to the detected capacitance value on f s ;

[0025] When the capacitor structure is an annular capacitor composed of two clamping plates, the water seepage height detection model is as follows:

[0026] ;

[0027] Among them, is the water seepage height; is the dielectric constant of the water-seeped concrete; is the dielectric constant of the dry concrete; is the height of the specimen; is the measured capacitance value; is the opening angle of the annular capacitor; is the correction coefficient.

[0028] A system for detecting the water seepage height of a concrete impermeability test proposed by the present invention includes a memory and a processor. A computer program is stored in the memory, and the processor is connected to the memory. The processor is used to execute the computer program to implement the method for detecting the water seepage height of the concrete impermeability test.

[0029] A storage medium proposed by the present invention stores a computer program, and when the computer program is executed, it is used to implement the method for detecting the water seepage height of the concrete impermeability test.

[0030] The advantages of the present invention are as follows:

[0031] A method for detecting the water seepage height of a concrete impermeability test proposed by the present method utilizes the characteristic that when the water seepage height of the concrete changes and it serves as the inter-electrode medium of the capacitor, the capacitance value will change with the water seepage height to measure the water seepage height. The implementation of the present invention can complete the two tests of the step-by-step pressure method and the water seepage height method within the time of one experiment, can fully realize automatic detection without manual intervention, will greatly save the test time of the water seepage height method, and improve work efficiency and the quality of detection data.

[0032] The present invention utilizes the characteristic that the concrete specimen can be clamped by the capacitor during the concrete impermeability test to perform capacitance measurement, which is convenient and fast, does not require splitting the concrete for observation, improves the efficiency of concrete detection, and reduces the operation cost and difficulty.

[0033] The present invention proposes two capacitor structures and capacitance measurement methods, namely a flat capacitor and an annular capacitor, in combination with the characteristic that the concrete specimen is usually frustum-shaped. Corresponding water seepage height detection models are proposed for different capacitance measurement methods, providing multiple ways for the capacitance detection of concrete specimens, facilitating selection according to the environment; at the same time, it is also convenient to verify the detection results through different detection methods. Description of the Drawings

[0034] Figure 1It is a flowchart of a method for detecting the water seepage height in a concrete impermeability test;

[0035] Figure 2 It is a schematic diagram of a flat capacitor;

[0036] Figure 3 It is a schematic diagram of the detection state of a flat capacitor;

[0037] Figure 4 It is a schematic diagram of the detection state of an encircling capacitor;

[0038] Figure 5 It is an angle display;

[0039] Figure 6 It is the test site of a flat capacitor;

[0040] Figure 7 It is a display of a fitting function;

[0041] Figure 8 It is a display of the detection error shown in Table 2 of Example 1;

[0042] Figure 9 It is a display of the detection error shown in Table 3 of Example 1;

[0043] Figure 10 It is the test site of an encircling capacitor;

[0044] Figure 11 It is a display of the detection error shown in Table 4 of Example 2;

[0045] Figure 12 It is a display of the detection error shown in Table 5 of Example 2;

[0046] Figure 13 It is a display of the detection error shown in Table 6 of Example 2. Specific implementation manners

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] Refer to Figure 1, in the present invention, the concrete specimen and the water seepage inside it are regarded as the dielectric between the electrodes of a capacitor. Special capacitance sensors are arranged around the concrete specimen. When the height of water seepage inside the concrete changes, the dielectric constant of the dielectric between the electrodes of the capacitor changes, resulting in a change in the capacitance value. Through testing, it is found that the change in the capacitance value shows a certain linear variation law with the height of water seepage. Therefore, the height of water seepage in the concrete impermeability test can be quickly achieved through the solution of the present invention, avoiding the cumbersome process of splitting the specimen with a press for measurement, effectively saving time and reducing costs.

[0049] The present invention provides two capacitor structures.

[0050] The first capacitor structure is composed of plate members 1 arranged vertically and parallel to each other, simply referred to as a parallel-plate capacitor, as Figure 3 shown.

[0051] The parallel-plate capacitor is a basic and important electronic component, widely used in various circuits. The capacitance value of the parallel-plate capacitor C involves several key parameters including: the relative dielectric constant ε r of the insulating dielectric e between the electrodes, ε 0 the vacuum permittivity, S the plate area, d and the distance between the plates, Figure 2 specifically refer to

[0052] ;

[0053] It can be seen from the above formula that the main factors affecting the capacitance of the capacitor are as follows:

[0054] 1. Different types of insulating dielectrics (such as air, mica, glass, etc.) will affect the dielectric constant;

[0055] 2. The area size of the upper and lower plates of the capacitor;

[0056] 3. The distance between the upper and lower plates of the capacitor.

[0057] When using a parallel-plate capacitor to detect the height of water seepage in a concrete specimen, the two plate members 1 of the parallel-plate capacitor are arranged vertically on the two end faces of the concrete specimen, so that the two plate members 1 are horizontally arranged and clamp the concrete specimen 2 up and down, and the result is as Figure 3 shown. It should be noted that the concrete specimen 2 and the two plate members 1 are arranged insulated from each other.

[0058] Thus, with the area of the plate fixed, the distance between the plates is the height of the concrete specimen. When water penetrates the concrete specimen, the composite dielectric constant of the medium between the electrodes changes. The higher the water penetration height, the greater the water content, the larger the composite dielectric constant of the medium between the electrodes, and the larger the capacitance value of the capacitor. Conversely, the lower the water penetration height, the smaller the water content, and the smaller the composite dielectric constant of the medium between the electrodes.

[0059] When using a parallel-plate capacitor to measure the water penetration height, the water penetration height can be calculated through the water penetration height detection model shown in the following formula (1):

[0060] ;

[0061] where, is the water penetration height; is the dielectric constant of the water-penetrated concrete, is the dielectric constant of the dry concrete; is the height of the concrete specimen; is the capacitance value measured by the parallel-plate capacitor; is the area of the plate; let C - f s is a correction function characterizing the ratio relationship between the fitting value and the theoretical value of the water penetration height of the concrete specimen under different capacitance values; f s,C represents the value when the capacitance value is C.

[0062] where, and can be obtained by looking up the table.

[0063] The acquisition of the correction function C - f s includes the following steps.

[0064] S11. Construct a detection environment and determine the height of the concrete specimen and the area

[0065] of the plates of the parallel-plate capacitor; measure the capacitance of the concrete specimen using the parallel-plate capacitor in the detection environment; the two plates of the parallel-plate capacitor are horizontally arranged and clamp the concrete specimen up and down, and the plates are insulated from the concrete specimen; h , C p S12. Obtain the calibration samples ( h of the concrete specimen, where C p is the water penetration height of the concrete specimen set during calibration, hCapacitance value at that time; specifically, the concrete specimen can be first measured for capacitance, and then split to measure the seepage height to obtain a calibration sample ( h , C p );

[0066] S13. Fit the seepage height based on the calibration sample h and the calibrated capacitance C p as the seepage height fitting formula.

[0067] Specifically, in this embodiment, the seepage height fitting formula can be set as , so as to fit the parameters a and b based on the calibration sample.

[0068] S14. Calculate the theoretical value of the seepage height of the concrete specimen corresponding to the calibrated capacitance C p : h s :

[0069] ;

[0070] where is the theoretical value of the seepage height; is the dielectric constant of the seepage concrete, is the dielectric constant of the dry concrete; is the height of the specimen; is the area of the plate;

[0071] S15. Obtain the correction function C - f s , that is, construct the ratio h of the seepage height h s to the theoretical height f s with respect to the capacitance C p as the correlation curve, f s = h / h s .

[0072] The second capacitor structure is an annular capacitor formed by two clamping plates 3 as electrode plates. The annular capacitor is arranged on the outer periphery of the concrete specimen. The two clamping plates 3 clamp the concrete specimen from left and right and are insulated from the concrete specimen; a gap is reserved between the two clamping plates 3, and the two clamping plates 3 are symmetrically arranged about the concrete specimen from left and right, as Figure 4 shown, where the dotted line 4 represents the water level line.

[0073] The second capacitor structure can be equivalent to the first capacitor structure, and its influencing parameters are the same as those of the parallel plate capacitor. When the water seepage height of the concrete specimen changes, the comprehensive dielectric constant of the dielectric between the capacitors changes. The higher the water seepage height, the greater the water content, the greater the comprehensive dielectric constant of the dielectric between the electrodes, and the larger the capacitance value of the capacitor. On the contrary, the same linear change occurs in the law.

[0074] For the cylindrical concrete specimen, the clamping plate 3 is provided with an arc surface structure attached to the circumferential surface of the concrete specimen. At this time, the water seepage height of the concrete specimen can be calculated according to the water seepage height detection model shown in the following formula (2):

[0075] ;

[0076] is the water seepage height; is the dielectric constant of the water-seeped concrete; is the dielectric constant of the dry concrete; is the height of the specimen; is the measured capacitance value; is the opening angle of the slits of the ring-shaped capacitor, as shown in Figure 5; is the correction coefficient, which can be specifically obtained by sample fitting.

[0077] Specifically, the fitting method of the correction coefficient is as follows: First, obtain the calibration samples of the concrete specimens ( h , C p ), and then let C = C p Substitute the calibration samples into formula (2) to fit the correction coefficient .

[0078] The following combines specific embodiments to verify the above water seepage height detection model.

[0079] Embodiment 1

[0080] In this embodiment, a parallel plate capacitor is used for measurement to verify formula (1).

[0081] In this embodiment, a simulated concrete specimen container made of acrylic material is fabricated. The internal volume of the container is the same as the volume of the standard concrete specimen, with a height of 150 mm, a lower bottom circle diameter of 185 mm, and an upper bottom circle diameter of 175 mm.

[0082] The experimental settings are as follows:

[0083] Capacitance test instrument: The test level is 1 V, and the test frequency is 1 kHz;

[0084] Parallel-plate capacitor: The plate is made of an aluminum sheet with an area of 300×300 mm and a thickness of 2 mm;

[0085] Medium inside the container: Sand and water;

[0086] During the experiment, the water level inside the container is separated by a thin film up and down to control the water level line, that is, the seepage height; The part above the thin film is dry sand, and the part below the thin film is a sand-water mixture.

[0087] The experimental scheme is carried out in 5 steps.

[0088] Step 1: There is no water in the acrylic specimen container. Use a capacitance testing instrument to measure the capacitance value at this time and record it;

[0089] Step 2: Put water to a height of 1 / 4 of the volume in the acrylic specimen container. Use a capacitance testing instrument to measure the capacitance value at this time and record it;

[0090] Step 3: Put water to a height of 2 / 4 of the volume in the acrylic specimen container. Use a capacitance testing instrument to measure the capacitance value at this time and record it;

[0091] Step 4: Put water to a height of 3 / 4 of the volume in the acrylic specimen container. Use a capacitance testing instrument to measure the capacitance value at this time and record it;

[0092] Step 5: Fill the acrylic specimen container with water. Use a capacitance testing instrument to measure the capacitance value at this time and record it.

[0093] First, perform a data calibration, repeat the above experiment, record the data 2 times and take the average value, and then perform formula calculation. Figure 6 This is a field picture at 3 / 4 water level in this implementation.

[0094] Perform data calibration on this scheme, and the recorded data is shown in Table 1 below.

[0095] Table 1: Capacitance values at different water levels

[0096] ;

[0097] Perform data fitting on the above calibration data to obtain:

[0098] ;

[0099] Determine the parameter . The calibration data and the fitting function are as Figure 7 shown. In this embodiment, formula (1-1) is used to calculate the theoretical water level values at different capacitance values C p to calculate the ratio of the actual water level value to the theoretical value at different capacitance values C p and construct a correction functionC - f s 。

[0100] In this embodiment, the test was carried out twice again, data was collected, and the water level was inversely calculated by combining with the seepage height detection model shown in formula (1). The results are shown in Table 2, Table 3, and Figure 8 、 Figure 9 as shown.

[0101] Table 2: Statistical results of the inverse calculation error in the first experiment

[0102] ;

[0103] Table 3: Statistical results of the inverse calculation error in the second experiment

[0104] ;

[0105] It can be seen that the error in this embodiment is always lower than 3%, which proves the reliability of the method. Embodiment

[0106] In this embodiment, a ring-shaped capacitor is used for measurement to verify formula (2).

[0107] The simulated concrete specimen container and the capacitance testing instrument in this embodiment are as shown in Embodiment 1. The medium in the container is sand and water. A thin film is set at the water level for seepage isolation, so that the part above the film is dry sand and the part below the film is a sand-water mixture.

[0108] The clamping plate 3 of the ring-shaped capacitor is an arc-shaped copper sheet attached to the outer periphery of the simulated concrete specimen container, with an area of 150×295 mm and a thickness of 0.3 mm. When testing, the opening angle of the ring-shaped capacitor is 89°.

[0109] In this embodiment, first, a calibration sample ( h , C p ) is substituted into formula (2) to fit the correction coefficient to be 8.5; then, the formula (2) is verified according to the measured capacitance value in the test.

[0110] The experimental scheme steps are as follows.

[0111] Step 1: There is no water in the acrylic specimen container, and the capacitance value at this time is measured using a capacitance testing instrument and recorded;

[0112] Step 2: The water level with a volume of 1 / 4 height is placed in the acrylic specimen container, and the capacitance value at this time is measured using a capacitance testing instrument and recorded;

[0113] Step 3: Set the water level at 2 / 4 of the internal volume of the acrylic specimen container, use a capacitance testing instrument to measure the capacitance value at this time and record it;

[0114] Step 4: Set the water level at 3 / 4 of the internal volume of the acrylic specimen container, use a capacitance testing instrument to measure the capacitance value at this time and record it;

[0115] Step 5: Fill the acrylic specimen container with water, use a capacitance testing instrument to measure the capacitance value at this time and record it.

[0116] Repeat the above experiment, record the data three times, and calculate the water level inversely according to the measured capacitance value combined with formula (2). The results are shown in Table 4 - Table 6 and Figures 11 - 13 as follows.

[0117] Table 4: Statistical data of the first detection in Example 2

[0118] ;

[0119] Table 5: Statistical data of the second detection in Example 2

[0120] ;

[0121] Table 6: Statistical data of the third detection in Example 2

[0122] ;

[0123] From the above three detection results, it can be seen that when using the ring - shaped capacitor for testing, the error is always lower than 6%; however, it can be seen from Figures 11 - 13 that the linear characteristic of the ring - shaped capacitor is more significant, which is better than that of the flat - plate capacitor. It can be seen that the ring - shaped capacitor is more suitable for practical applications.

[0124] Of course, for those skilled in the art, the present invention is not limited to the details of the above - mentioned exemplary embodiments, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0125] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0126] The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. A method for detecting water seepage height in a concrete anti-seepage test, characterized in that: The concrete specimen and the water seepage inside it are regarded as the inter-electrode medium of the capacitor, and a capacitive sensor for clamping the concrete specimen is arranged outside the concrete specimen, and the capacitive sensor is insulated from the concrete specimen; then the water seepage height is calculated according to the capacitance value; Applicable to flat plate capacitors. During testing, the flat plate capacitors are arranged horizontally up and down to clamp the concrete test piece; The method firstly combines the calibration sample to fit the relationship between the capacitance value and the water seepage height of the concrete specimen, records the water seepage height calculated by combining the known capacitance value and the relationship as the water seepage height fitting value, and records the water seepage height calculated by combining the known capacitance value and the theoretical formula as the water seepage height theoretical value; constructs a ratio change curve of the water seepage height fitting value and the water seepage height theoretical value under different capacitance values ​​on the calibration sample; Then, a flat plate capacitor is used to detect the concrete specimen to be tested, and the measured capacitance value is obtained. The theoretical value of the water seepage height of the concrete specimen to be tested is calculated, and the ratio change curve is searched to obtain the target ratio corresponding to the measured capacitance value. The product of the target ratio and the theoretical value of the water seepage height of the concrete specimen to be tested is calculated as the water seepage height detection result of the concrete specimen to be tested; The theoretical formula is expressed as: ； in, is the theoretical value of water seepage height; is the dielectric constant of permeable concrete, is the dielectric constant of dry concrete; is the specimen height; is the plate area; C is the capacitance value.

2. The method for detecting water seepage height in concrete anti-seepage test according to claim 1, characterized in that: The relationship is expressed as: ; where a and b are the parameters to be fitted, C is the capacitance value, h is the water seepage height.

3. A system for detecting water seepage height in concrete anti-seepage test, characterized in that: It comprises a memory and a processor, wherein a computer program is stored in the memory, and the processor is connected to the memory, and the processor is used to execute the computer program to implement the method for detecting the water seepage height of the concrete impermeability test as claimed in claim 1 or 2.

4. A storage medium, characterized in that: A computer program is stored, and when the computer program is executed, it is used to implement the method for detecting the water seepage height of the concrete impermeability test as claimed in claim 1 or 2.

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