A diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing

Abstract

The application discloses a diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing. After obtaining the temperature rise values at different depths of the diaphragm wall before and after pouring of concrete, the average temperature rise value is obtained by averaging. The position with a temperature rise value less than the average temperature rise value is positioned as a pouring defect position, thereby realizing qualitative identification of defects. The temperature rise values outside the defect position are averaged again to obtain a normal area temperature rise value. The ratio of the temperature rise value of the defect position to the normal area temperature rise value is set as a temperature rise rate, and the effective cross-sectional area at the defect position is obtained from the temperature rise rate. The effective cross-sectional area is a smaller cross-sectional area without defects equivalent to a larger preset cross-sectional area with defects, thereby realizing quantitative evaluation of defects. Thus, the defects can be positioned in time, early, accurately and reliably during pouring of the diaphragm wall, and the severity of the defects can be accurately quantitatively evaluated, thereby greatly helping to ensure construction safety, and the method is simple and easy to operate, has low requirements on operators, and has a wide application scenario.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quality detection of diaphragm wall pouring, and in particular to a diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing. BACKGROUND

[0002] As an important deep foundation pit support and underground enclosure structure, the diaphragm wall is widely used in high-rise buildings, subways, tunnels, water conservancy projects and other fields. Its quality directly affects the stability of the foundation pit, the safety of surrounding buildings and structures, and the long-term durability of the project. During construction, especially during underwater or deep trench concrete pouring, various factors such as complex geological conditions, fluctuation of mud performance, and pipe blockage can easily cause different types of pouring defects such as mud inclusion, sand inclusion, cavities, honeycombs, and non-compaction inside or at the interface of the diaphragm wall. These defects significantly weaken the impermeability, mechanical bearing capacity, and structural integrity of the diaphragm wall, becoming a key hidden danger point for the safety of foundation pit projects, and engineering accidents such as leakage and collapse caused by defects have occurred in history.

[0003] In the prior art, the traditional methods for diaphragm wall quality detection mainly include drilling core method, ultrasonic method, reflected wave method, and electromagnetic method. Although the drilling core method is reliable, it is a destructive detection method that may introduce new weak areas affecting the impermeability. The ultrasonic method and the reflected wave method have limited resolution, are prone to defect omission, and are complex to operate, requiring high technical personnel. The electromagnetic method is easily disturbed by the surrounding environment, resulting in inaccurate measurement results.

[0004] Therefore, it is of great significance to develop an effective, accurate, and reliable diaphragm wall defect detection and evaluation method to ensure construction safety. SUMMARY

[0005] To solve the above problems, the present application provides a diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing, which can timely, early, accurately, and reliably locate defects during diaphragm wall pouring, accurately quantify the severity of the defects, greatly help ensure construction safety, and has a wide range of application scenarios.

[0006] The technical solutions adopted by the present application are as follows:

[0007] A diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing, including defect qualitative identification and defect quantitative evaluation;

[0008] The defect detection and evaluation method includes obtaining the temperature rise values of the diaphragm wall at different depths before and after concrete pouring ;

[0009] The defect qualitative identification method is as follows:

[0010] Temperature rise values at different depths of the diaphragm wall Average temperature rise values are obtained by averaging ;

[0011] Temperature rise values at different depths are compared with average temperature rise values Temperature rise values less than average temperature rise values are positioned as pouring defect positions, realizing defect qualitative identification;

[0012] The defect quantitative evaluation mode is:

[0013] Temperature rise values not less than average temperature rise values are averaged again to obtain normal area temperature rise values ;

[0014] Temperature rise values at pouring defect positions are set as defect temperature rise values , and a ratio of to is set as a temperature rise rate ;

[0015] An effective cross-sectional area at the defect position is obtained from the temperature rise rate , and the effective cross-sectional area is a smaller cross-sectional area without defects equivalent to a larger preset cross-sectional area with defects, realizing defect quantitative evaluation; in combination with comparison of the effective cross-sectional area and a design cross-sectional area, the severity of the defect is evaluated. As a further improvement of the above technical solution:

[0016] It further comprises deploying an optical cable along a longitudinal reinforcement of the diaphragm wall reinforcement cage, and the optical cable is fixed on the longitudinal reinforcement of the reinforcement cage by binding; the optical cable is connected with a distributed temperature demodulator to obtain the temperature of the diaphragm wall at different depths.

[0017] The optical cable is deployed in a U shape along the longitudinal reinforcement of the reinforcement cage, forming two optical cables vertically arranged along the reinforcement cage; the temperature of the diaphragm wall at different depths is an average value of the temperature of the two optical cables at the same depth.

[0018] Before pouring the concrete, the temperature of the diaphragm wall is obtained as an initial temperature; during the hydration process after pouring the concrete, the peak temperature of the diaphragm wall at different depths is obtained; and the temperature change amount of the diaphragm wall at different depths is obtained by subtracting the initial temperature from the peak temperature.

[0019] Before pouring the concrete, the temperature of the diaphragm wall is obtained as an initial temperature; during the hydration process after pouring the concrete, the peak temperature of the diaphragm wall at different depths is obtained; and the temperature change amount of the diaphragm wall at different depths is obtained by subtracting the initial temperature from the peak temperature.

[0020] ​​​The diaphragm wall often penetrates different strata in the depth direction, and the thermal properties of different strata are different, resulting in different temperature diffusion speeds. The temperature variation at different depths is corrected, and the correction value is taken as the temperature rise value of the diaphragm wall at different depths .

[0021] The thermal diffusion coefficient is calculated according to the following formula:

[0022]

[0023] Wherein, k is the thermal conductivity of the stratum; c is the specific heat capacity of the stratum; and p is the density of the stratum.

[0024] From the beginning of pouring the diaphragm wall concrete, continuous measurement is carried out to obtain the peak temperature in the hydration process of the concrete; at the peak temperature, the difference between the pouring defects and the normal area is most obvious.

[0025] The heat at the top and bottom of the diaphragm wall diffuses to the air and the bottom stratum respectively, and the temperature rise value at different depths obtained The temperature values in the preset length at the top and bottom of the diaphragm wall are removed, and the preset length is not less than the width size of the diaphragm wall.

[0026] The temperature measurement point position on the cross section of the diaphragm wall is taken as the boundary center, the width size of the diaphragm wall is taken as the side length to form a square, and the area of the square is taken as the complete preset cross-sectional area The preset cross-sectional area is the square of the width size of the diaphragm wall; the effective cross-sectional area is the difference between the preset cross-sectional area and the defect area in the range; The greater the pouring quality is.

[0027] The temperature rise rate is obtained, and the effective cross-sectional area at the defect position is obtained, which satisfies the following formula:

[0028] .

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The present application can locate defects in time, early, accurately and reliably during the pouring period of the diaphragm wall, and can accurately quantify and evaluate the severity of the defects, greatly helping to ensure construction safety;

[0031] The present application also has the following advantages:

[0032] Through the monitoring of the hydration temperature in the pouring of the diaphragm wall concrete, early detection of pouring defects is realized, which not only plays a warning role, but also greatly helps to shorten the construction period;

[0033] The peak temperature in the hydration process of the concrete is reasonably and skillfully utilized, the defects can be accurately positioned through the temperature abnormal area, and the severity of the quantitative defects is realized;

[0034] The pouring defect detection and evaluation is carried out based on the hydration temperature of the concrete, the whole process is simple and easy to operate, the skill requirement of the operator is low, is suitable for practical engineering application, and has a wide application scene. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a flowchart of the defect detection and evaluation method of the application.

[0036] Figure 2 It is a schematic view of the application along the diaphragm wall for optical cable deployment.

[0037] Figure 3 It is a temperature curve schematic view of the diaphragm wall with defects along the depth direction.

[0038] Figure 4 It is a conceptual schematic view of the effective cross-sectional area.

[0039] Figure 5 It is a calibration schematic view of the effective cross-sectional area and the temperature rise rate.

[0040] 1, diaphragm wall; 2, effective cross-sectional area; 3, defect; 4, complete diaphragm wall profile temperature curve; 5, diaphragm wall profile temperature curve with defects; 6, temperature curve at the defect; 8, optical cable;

[0041] 101, cross section with defects; 102, equivalent complete cross section;

[0042] 701, longitudinal reinforcement. DETAILED DESCRIPTION

[0043] The specific embodiments of the application will be described below in conjunction with the accompanying drawings.

[0044] As shown in the drawings, a diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing includes: Figure 1 First step: optical cable deployment;

[0045] Second step: temperature acquisition;

[0046] Third step: temperature correction;

[0047] Fourth step: defect identification;

[0048] The application has the advantages that:

[0049] Step 5: Defect severity assessment.

[0050] The defect identification in the fourth step of the defect detection and evaluation method is the qualitative identification of defects, and the defect severity assessment in the fifth step is the quantitative assessment of defects.

[0051] Defect detection and assessment methods include obtaining the temperature rise values ​​at different depths of the diaphragm wall before and after concrete pouring. .

[0052] The method for qualitative defect identification is as follows:

[0053] Temperature rise at different depths of the diaphragm wall The average temperature rise value is obtained by averaging. ;

[0054] Temperature rise at different depths With average temperature rise Comparison, temperature rise value Less than the average temperature rise The location is determined as the location of the casting defect, enabling qualitative identification of the defect.

[0055] The method for quantitative assessment of defects is as follows:

[0056] It will be no less than the average temperature rise. temperature rise value The average temperature rise value of the normal region was obtained again. ;

[0057] Set the temperature rise value at the location of the casting defect Defect temperature rise value ,Will and The ratio is set as the temperature rise rate. ;

[0058] By temperature rise rate Obtain the effective cross-sectional area at the defect location. Effective cross-sectional area To reduce the size of the pre-set cross-sectional area with defects A smaller cross-sectional area, equivalent to a defect-free form, enables quantitative assessment of defects.

[0059] The severity of defects can be assessed by comparing the effective cross-sectional area with the design cross-sectional area; for example, the severity of defects at the current depth cross-sectional area can be assessed based on the ratio of the effective cross-sectional area to the design cross-sectional area.

[0060] In this embodiment, the design cross-sectional area can adopt a preset cross-sectional area S, and the severity of the defect is evaluated by comparing the effective cross-sectional area with the preset cross-sectional area S, such as the ratio, the closer the ratio is to 1 or even greater than 1, the lower the severity, and the smaller the ratio is to 1 and the farther the ratio is from 1, the higher the severity.

[0061] The defect detection and evaluation method of this embodiment can timely, early, accurately and reliably locate defects during the pouring period of the diaphragm wall, and can accurately quantify the severity of the defects, greatly helping to ensure construction safety.

[0062] In this embodiment, the effective cross-sectional area is the area of the concrete other than the defect, and the temperature rise rate is obtained by monitoring the hydration temperature of the diaphragm wall concrete during pouring. The quantitative relationship between the effective cross-sectional area of the diaphragm wall and the temperature rise rate is established, and the effective cross-sectional area of the diaphragm wall is obtained, so as to realize the quantitative evaluation of the severity of the diaphragm wall defect.

[0063] Figure 2 As shown in the first step of the cable deployment, the optical cable 8 is deployed along the longitudinal reinforcement 701 of the diaphragm wall 1, and the optical cable 8 is fixed on the longitudinal reinforcement 701 of the diaphragm wall 1 by binding; the optical cable 8 is connected with the distributed temperature demodulator to obtain the temperature of the diaphragm wall at different depths.

[0064] In the embodiment shown in Figure 2 , the optical cable 8 is deployed in a U shape along the longitudinal reinforcement 701 of the diaphragm wall, forming two optical cables arranged vertically along the diaphragm wall; the temperature of the diaphragm wall at different depths is the average temperature of the two optical cables at the same depth, so as to more accurately detect and evaluate the defect of the diaphragm wall.

[0065] In this embodiment, the preset cross-sectional area S can be set as the cross section formed between the U-shaped optical cables 8.

[0066] The temperature acquisition in the second step includes: before the concrete pouring, the temperature of the diaphragm wall is obtained as the initial temperature; during the hydration process after the concrete pouring, the peak temperature of the diaphragm wall at different depths is obtained; and the temperature change of the diaphragm wall at different depths is obtained by subtracting the initial temperature from the peak temperature.

[0067] In this embodiment, the hydration temperature of the diaphragm wall concrete during pouring is monitored to realize early detection of pouring defects, which not only plays a warning role, but also greatly helps to shorten the construction period.

[0068] In this embodiment, the initial temperature can be detected according to the requirement at different depths; in actual operation, since the initial temperature at different depths has little difference, the same detection temperature can be used as the initial temperature to facilitate the actual operation.

[0069] From the beginning of the diaphragm wall concrete pouring, continuous measurement is carried out to obtain the peak temperature in the concrete hydration process; at the peak temperature, the difference between the pouring defects and the normal area is most obvious, as shown in Figure 3 Therefore, the peak temperature in the concrete hydration process is obtained to calculate the temperature change amount.

[0070] In this embodiment, the peak temperature in the concrete hydration process is reasonably and ingeniously utilized, and the defects can be accurately positioned through the temperature abnormal area, and the severity of the quantitative defects is also achieved.

[0071] The temperature correction in the third step is that the diaphragm wall often passes through different strata in the depth direction, and the thermal properties of different strata are different, such as different thermal conductivity, density, and specific heat capacity, which will result in different temperature diffusion speeds and will affect the diaphragm wall defect detection and evaluation; therefore, the thermal diffusion coefficient is introduced to correct the temperature change amount at different depths, and the correction value is taken as the temperature rise value of the diaphragm wall at different depths .

[0072] The thermal diffusion coefficient is calculated according to the following formula:

[0073]

[0074] Wherein, k is the thermal conductivity of the stratum; c is the specific heat capacity of the stratum; and p is the density of the stratum.

[0075] In this embodiment, the thermal diffusion coefficient is used to correct the temperature to eliminate the influence of the stratum properties on the temperature measurement of the optical cable 8, so as to ensure the reliability and accuracy of the defect detection and evaluation.

[0076] In actual operation, the ratio of the temperature change amount at different depths to the thermal diffusion coefficient can be obtained to obtain the correction value.

[0077] Considering that the heat at the top and bottom of the diaphragm wall will diffuse to the air and the bottom stratum respectively, the temperature rise value at different depths The temperature values in the preset length at the top and bottom of the diaphragm wall are removed, and the preset length is not less than the width size of the diaphragm wall.

[0078] The temperature measurement point position on the cross section of the diaphragm wall is taken as the boundary center, and the width size of the diaphragm wall is taken as the side length to form a square, and the area of the square is taken as the complete preset cross-sectional area , the preset cross-sectional area is the square of the width size of the diaphragm wall; the effective cross-sectional area is the difference between the preset cross-sectional area and the defect area in the range; The greater the pouring quality is, the better.

[0079] In Figure 4 The concept of effective cross-sectional area is illustrated in the embodiments shown, the left figure contains defects 3 in the defective cross section 101, and the effective cross-sectional area 2 is formed outside the defects 3; the right figure is obtained by removing the defects 3 in the left figure, and the equivalent complete cross section 102 without defects is obtained, which is equivalent to the effective cross-sectional area 2.

[0080] In this embodiment, for the U-shaped optical cable 8, the preset cross-sectional area S corresponds to the setting of the square, that is, the temperature measuring points of the vertical part on both sides of the optical cable 8 are taken as the center of the side length, and the width of the diaphragm wall is taken as the side length, to form a preset square cross section; through temperature detection before and after pouring, the defects on the preset square cross section are quantitatively evaluated by the defect detection evaluation method.

[0081] The effective cross-sectional area at the defect position is obtained by the temperature rise rate , which satisfies the following formula:

[0082] .

[0083] In Figure 5 The embodiments shown, by calibrating the temperature measurement on the model with different effective cross-sectional areas, a plurality of temperature rise rate and effective cross-sectional area corresponding test data are obtained, curve fitting is performed, and a calibration formula of the relationship between the temperature rise rate and the effective cross-sectional area is obtained, and the correlation coefficient close to 1 can also indicate the fitting effect of the curve.

[0084] In this embodiment, the pouring defect detection and evaluation is based on the hydration temperature of the concrete, the whole process is simple and easy to operate, the skill requirement of the operator is low, it is suitable for practical engineering application, and has a wide application scene.

[0085] The application can timely, early, accurately and reliably locate defects during the pouring of the diaphragm wall, and can accurately quantify the severity of the defects, greatly helping to ensure construction safety, and has a wide application scene.

[0086] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between each embodiment can be mutually referred to.

[0087] The above description is an explanation of the present application, not a limitation of the present application, the scope of the present application is defined by the claims, within the protection scope of the present application, any form of modification can be made.

Claims

1. A diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing, characterized by: The method comprises defect qualitative identification and defect quantitative evaluation. The defect detection evaluation method comprises obtaining temperature rise values at different depths of the diaphragm wall before and after concrete pouring ; The defect qualitative identification is achieved by: temperature rise values at different depths of the diaphragm wall obtaining average temperature rise values by averaging ; The temperature rise values at different depths are compared with the average temperature rise value The temperature rise values at different depths are compared with the average temperature rise value The temperature rise values at different depths are compared with the average temperature rise value The temperature rise values at different depths are compared with the average temperature rise value The position with a temperature rise value smaller than the average temperature rise value is positioned as a pouring defect position, and qualitative identification of defects is realized. The defect quantitative evaluation is achieved by: obtained by averaging the temperature rise values obtained by averaging the temperature rise values obtained by averaging the temperature rise values of the normal region Setting a temperature rise value at a position of a casting defect The temperature rise value for the defect , the ratio of and is set as a temperature rise rate ; obtained by the temperature rise rate obtained by the temperature rise rate obtained by the temperature rise rate obtained by the temperature rise rate obtained by the temperature rise rate 2. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing according to claim 1, characterized in that: The method further comprises deploying optical cables along the longitudinal reinforcement of the diaphragm wall cage, and fixing the optical cables on the longitudinal reinforcement of the diaphragm wall cage by binding; the optical cables are connected with a distributed temperature demodulator to obtain the temperature of the diaphragm wall at different depths.

3. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 2, wherein: The optical cables are deployed in a U shape along the longitudinal reinforcement of the diaphragm wall cage, and form two optical cables arranged vertically along the diaphragm wall cage; the temperature of the diaphragm wall at different depths is the average value of the temperature of the two optical cables at the same depth.

4. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 1, wherein: Before pouring the concrete, the temperature of the diaphragm wall is obtained as an initial temperature; during the hydration process after pouring the concrete, the peak temperature of the diaphragm wall at different depths is obtained; and the temperature variation of the diaphragm wall at different depths is obtained by subtracting the initial temperature from the peak temperature.

5. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing according to claim 4, characterized in that: Considering that the diaphragm wall often passes through different strata in the depth direction, the thermal properties of different strata are different, and the temperature diffusion speed is different, therefore, the thermal diffusion coefficient is introduced The temperature change amount at different depths is corrected, and the correction value is taken as the temperature rise value of the diaphragm wall at different depths .

6. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 5, wherein: the thermal diffusivity was calculated as follows: ； Wherein, k is the thermal conductivity of the stratum; c is the specific heat capacity of the stratum; and p is the density of the stratum.

7. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 4, wherein: From the beginning of pouring the concrete of the diaphragm wall, continuous measurement is performed to obtain the peak temperature in the hydration process of the concrete; at the peak temperature, the difference between the pouring defects and the normal area is most obvious.

8. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 1, wherein: Considering the heat of the top and bottom of the diaphragm wall diffuses to the air and the bottom stratum respectively, the temperature rise values at different depths are obtained The temperature values within the preset length of the top end and bottom end of the diaphragm wall are removed, and the preset length is not less than the width size of the diaphragm wall.

9. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 1, wherein: The temperature measuring point position on the diaphragm wall cross section is taken as the boundary center, the diaphragm wall width dimension is taken as the side length to form a square, and the square area is taken as the complete preset cross-sectional area , the preset cross-sectional area is the square of the diaphragm wall width dimension; the effective cross-sectional area is the difference between the preset cross-sectional area and the defect area in the range; The greater the pouring quality is.

10. The diaphragm wall pouring defect detection and evaluation method based on optical fiber sensing of claim 1, wherein: The temperature rise rate obtaining the effective cross-sectional area at the defect location which satisfies the following equation: 。

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