Sleeve grouting defect detection method based on full-coverage line source

Abstract

The invention discloses a sleeve grouting defect detection method based on a full-coverage line source, and relates to the field of engineering structure detection.The sleeve grouting defect detection method comprises the following steps that a target fabricated building is selected, and a plurality of grouting sleeves are manufactured to be used for fabricated building component nodes; the grouting sleeve is placed in the fabricated building, and the sleeve position is positioned according to an inlet and an outlet of the grouting sleeve; a full-coverage line source is arranged on the outer side of the fabricated building along the whole grouting sleeve, and the full-coverage line source serves as a transducer and a reflected wave sensor; signals received by the strain sensor and the reflected wave sensor are subjected to data processing and then subjected to time domain analysis, the defect detection result in the sleeve is obtained, and the defect detection result reflects the result of the grouting defect in the sleeve. The line source is emphasized to perform full-coverage detection on the whole grouting sleeve, the sleeve grouting defects can be accurately detected from multiple detection angles, and the problems that traditional sleeve grouting detection is repeated for multiple times and the detection precision is low are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering structure detection, and in particular relates to a sleeve grouting defect detection method based on a full-coverage line source. Background Art

[0002] At present, prefabricated buildings are gradually being widely used. The main connection methods for prefabricated building components include sleeve grouting connection, grout anchor connection and anchor bolt connection. Among them, sleeve grouting connection refers to connecting the longitudinal stress-bearing steel bars of two prefabricated concrete components with grouting sleeves, and connecting the stress-bearing steel bars by using the high-strength and shrinkage-free properties of the grouting material, so that the load is transmitted to the stress-bearing components through the grouting sleeves. However, in the actual construction process, operational errors of construction personnel and lack of grouting technology will lead to sleeve grouting defects. Common grouting sleeve defects include top grouting defects, horizontal grouting defects, middle grouting defects, missing steel bars, steel bar eccentricity, etc. Grouting defects of different degrees will affect the quality of the concrete structure, reduce the bearing capacity and seismic performance of the structure, and thus cannot guarantee the integrity and safety of the building. Therefore, it is necessary to test the quality of the grouting sleeve.

[0003] At present, the traditional detection methods for sleeve grouting quality are mainly destructive testing and non-destructive testing. Among them, the destructive testing method will damage the grouting sleeve itself, and the damage caused to it cannot be estimated. Most non-destructive testing methods are only used in the laboratory stage. The actual process is complicated and the cost is high. A single point source is often used as the excitation signal, and the detection accuracy is not high. In order to solve the above problems, a sleeve grouting defect detection method based on a full coverage line source is proposed.

[0004] It should be noted that the above contents belong to the technical knowledge of the inventor and do not necessarily constitute prior art. Summary of the invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a detection method for sleeve grouting defects based on full coverage line source. By using full coverage line source excitation, only a single detection is required to fully reflect the internal situation of the entire grouting sleeve. The received signal can fully display the interface information inside the sleeve, and the data processing is simple and the application conditions are low.

[0006] To achieve the above object, the present invention proposes a method for detecting sleeve grouting defects based on a full coverage line source, the detection method comprising the following steps: S1: Select a target prefabricated building and make multiple grouting sleeves for the prefabricated building component nodes.

[0007] The manufacturing method of the grouting sleeve is: Before grouting, a strain sensor is embedded in the sleeve, and the sleeve is placed in the prefabricated building to connect two steel bars connected end to end. Then, grouting material is poured into the sleeve to form a grouting sleeve.

[0008] S2: Place the grouting sleeve into the prefabricated building and locate the sleeve according to the inlet and outlet of the grouting sleeve; S3: A full coverage line source is set along the entire grouting sleeve on the outside of the prefabricated building. The full coverage line source serves as both a transducer and a reflected wave sensor.

[0009] S4: The strain sensor and reflected wave sensor collect data through the acquisition card.

[0010] S5: After data processing, the signals received by the strain sensor and the reflected wave sensor are subjected to time domain analysis to obtain defect detection results inside the sleeve. The defect detection results reflect the results of grouting defects inside the sleeve.

[0011] Furthermore, the strain sensor is arranged on the inner wall of the sleeve and is parallel to the sleeve, and its length runs through the sleeve, so as to collect the strain response inside the entire sleeve.

[0012] Furthermore, the strain sensor is an optical fiber sensor.

[0013] Furthermore, the full coverage line source adopts ultrasonic signals excited by a linear array probe.

[0014] Furthermore, the full coverage line source includes a signal trigger.

[0015] Furthermore, in S5, MATLAB is used to perform time domain analysis.

[0016] The sleeve grouting defect detection method based on full coverage line source proposed by the present invention can bring the following beneficial effects: 1. The detection method of the present invention adopts full coverage line source excitation, and only a single detection is required to fully reflect the internal situation of the entire grouting sleeve. The received signal can fully display the interface information inside the sleeve, and the data processing is simple and the application conditions are low; 2. The detection method of the present invention adopts full coverage line source excitation, which can collect structural information inside the sleeve through strain sensors, and can also collect echo signals from the outside of the building through reflection wave sensors. Different signals and different signal collection methods can clearly obtain information inside the structure; 3. The detection method of the present invention provides a new idea for sleeve grouting defect detection, and proposes a new method for detecting grouting sleeve defects based on full-coverage line source excitation signals. The detection method based on full-coverage line source excitation signals can intuitively and effectively detect the internal defects of the sleeve grouting, and after time domain analysis and processing of the signal, the detection results of the internal defects of the sleeve can be intuitively obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 This is a flow chart of a method for detecting sleeve grouting defects based on a full coverage line source according to the present invention; Figure 2 It is a schematic diagram of detecting sleeve grouting defects based on the full coverage line source method of the present invention; Figure 3 Schematic diagram of concrete model with different sleeve grouting defects; Figure 4 This is a schematic diagram of the full coverage line source layout and signal collection points; Figure 5 The simulation results of the interface strain inside the sleeve of the sleeve grouting defective concrete model; Figure 6 The simulation results of reflected waves from the outer side of the prefabricated building of the sleeve grouting defect concrete model; Figure 7 Set up plots for point source and full coverage line source models; Figure 8 The comparison diagram of simulation results of interface strain response in the point source and full coverage line source sleeves; Fig. 9 Comparison of simulation results of reflected wave response on the outer side of prefabricated buildings for point source and full coverage line source. DETAILED DESCRIPTION

[0018] The specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings and numerical simulation example results.

[0019] A method for detecting sleeve grouting defects based on full coverage line source, such as Figure 1 As shown, the detection method comprises the following steps: S1: Select a target prefabricated building and make multiple grouting sleeves for the prefabricated building component nodes; Prefabricated buildings include concrete and steel bars.

[0020] The method for making the grouting sleeve is as follows: Before grouting, a sensor is embedded in the sleeve, and the sleeve is placed in the prefabricated building to connect two end-to-end steel bars, and then the grouting material is poured into the sleeve to form a grouting sleeve; The embedded sensor is a strain sensor, which is arranged on the inner wall of the sleeve and parallel to the sleeve. The strain sensor runs through the sleeve and is used to collect the strain response inside the entire sleeve.

[0021] The strain sensor may be an optical fiber sensor or other sensor to receive the strain response, and its diameter is usually very small, so the impact on the integrity and safety of the sleeve grouting can be ignored.

[0022] S2: Place the grouting sleeve into the prefabricated building and locate the sleeve according to the entrance and exit of the grouting sleeve.

[0023] S3: A full coverage line source is set along the entire grouting sleeve on the outside of the prefabricated building.

[0024] The full coverage line source acts as both a transducer and a reflected wave sensor to receive reflected wave signals from the inside of the sleeve. The full coverage line source is used to excite ultrasonic signals.

[0025] The ultrasonic signal passes through the concrete box sleeve and reaches the inside of the sleeve. The excited ultrasonic signal will cause different responses at the dense grouting area and the defective area inside the sleeve, so that the strain sensor can collect the strain signal and the reflected wave sensor can also receive the echo signal.

[0026] The full coverage line source can use ultrasonic signals excited by a linear array probe.

[0027] The full coverage line source includes a signal trigger for issuing acquisition instructions to the acquisition system.

[0028] S4: The strain sensor and reflected wave sensor collect data through the acquisition card.

[0029] S5: After data processing, the signals received by the strain sensor and the reflected wave sensor are analyzed in the time domain using MATLAB to obtain the defect detection results inside the sleeve. The defect detection results can directly reflect the results of the grouting defects inside the sleeve qualitatively and quantitatively.

[0030] A specific numerical simulation case of a sleeve grouting defect detection method based on full coverage line source is as follows: Different sizes of sleeve grouting defective concrete models were selected for simulation, such as Figure 2 As shown, the defective concrete model is electrically connected to the signal generator and the data acquisition system, as shown in Figure 3 As shown, the model includes a grouting sleeve and concrete and steel bars on a prefabricated building.

[0031] The grouting defect of the grouting sleeve is set as vacuum. Since the top grouting defect is more common in actual construction, the model geometry setting is mainly based on the numerical model of the top grouting defect, and the models with grouting defect sizes of 125mm and 65mm in length are selected for comparative simulation. The embedded strain sensor is extremely small and will not cause any damage to the grouting sleeve, so it can be ignored in the model geometry setting.

[0032] In the simulation, Figure 4 As shown, the ultrasonic wave is excited by a full-coverage line source, and the Ricker wavelet is selected as the excitation signal of the transmitting source. The ultrasonic wave passes through the concrete to reach the sleeve and then reaches the inside of the sleeve. After a part of the ultrasonic wave reaches the inside of the sleeve, the strain sensor detection point set on the inside of the sleeve can detect the strain change. The other part of the ultrasonic wave is reflected back at the interface inside the sleeve due to the interface acoustic impedance, and is detected and received by the reflected wave sensor detection point on the outside of the prefabricated building. This embodiment sets a total of 251 detection points along the height direction of the sleeve, and outputs the strain response signal of the collection point inside the sleeve and the reflected wave signal of the collection point outside the prefabricated building.

[0033] The strain response signal is analyzed in the time domain after being processed by MATLAB data, such as Figure 5 As shown in the figure, it can be seen that the strain response at the grouting defect area is significantly smaller than that at the grouting dense area, and there is a clear boundary between the grouting defect area and the grouting dense area. This is because the grouting defect area is in a vacuum state, so there is no response to the strain signal, while there is a strain response at the grouting dense area. As the grouting defect size set by the geometric model decreases, the defect area shown in the time domain result diagram also decreases. The defect area size shown in the time domain result diagram corresponds to the defect size set by the numerical model.

[0034] The reflected wave signal is analyzed in the time domain after being processed by Matlab data, such as Figure 6 As shown in the figure, it can be seen that the energy of the reflected wave at the grouting defect is significantly stronger than that of the grouting dense area, and the boundary between the grouting defect area and the grouting dense area is obvious. This is because the acoustic impedance of the sleeve-defect interface is greater than the acoustic impedance of the sleeve-grouting material interface, so the energy of the reflected wave is stronger. As the grouting defect size set by the geometric model decreases, the defect area shown in the time domain result diagram also decreases. The defect area size shown in the time domain result diagram corresponds to the defect size set by the numerical model.

[0035] Verify the advantages of this detection method over previous technologies: Existing non-destructive detection of grouting sleeve defects mostly sets the excitation signal in a point source manner, but the point source excitation cannot fully display the internal defects of the sleeve, and the selection of the point source position is somewhat difficult. The present invention uses a method based on a full-coverage line source to detect internal defects of the sleeve grouting, which solves the shortcomings of the point source excitation.

[0036] Take the numerical model of 125mm defect length as an example. Figure 3 As shown in Figure 2, two different excitation sources are set, namely, conventional point source excitation and full coverage line source excitation. Figure 7 As shown, the numerical simulation results are compared to explore the advantages of full coverage line source.

[0037] According to the comparison of the strain response simulation results of the point source and the full coverage line source sleeve inner interface, Figure 8 As shown in the figure, it can be seen that for the same concrete numerical model with a sleeve grouting defect length of 125 mm, the simulation results of the point source and the full coverage line source are significantly different. The numerical simulation results of the strain response based on the point source excitation can hardly show the grouting defect area, while the reflected wave signal on the outside of the prefabricated building based on the point source excitation, such as Fig. 9 As shown in the figure, the grouting defect area cannot be displayed. On the contrary, the numerical simulation results based on the full coverage line source can intuitively and comprehensively display the internal situation of the grouting sleeve. Therefore, compared with the conventional point source excitation method, the detection method of sleeve grouting defects based on a full coverage line source has obvious advantages.

[0038] It can be seen that the time domain analysis results of strain response signal and reflected wave signal can well present the quantitative analysis of the internal defect size of the sleeve of different sleeve grouting defect concrete models. Therefore, the result analysis based on full coverage line source sleeve grouting defect detection can quantitatively detect the internal defects of sleeve grouting.

[0039] The full coverage line source proposed in the present invention does not need to repeatedly detect the grouting sleeve. The internal defects of the grouting sleeve can be obtained through a single detection, and the result is intuitive and effective. Therefore, the present invention combines the full coverage line source with the sleeve grouting defect detection, takes different signal acquisition methods as an example, and provides theoretical support for the realization of the present invention through specific numerical simulation cases.

[0040] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0041] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for detecting sleeve grouting defects based on full coverage line source, characterized in that: The detection method comprises the following steps: S1: Select a target prefabricated building and make multiple grouting sleeves for the prefabricated building component nodes; The manufacturing method of the grouting sleeve is: Before grouting, a strain sensor is embedded in the sleeve, and the sleeve is placed in the prefabricated building to connect two steel bars connected end to end, and then the grouting material is poured into the sleeve to form a grouting sleeve; S2: Place the grouting sleeve into the prefabricated building and locate the sleeve according to the inlet and outlet of the grouting sleeve; S3: A full coverage line source is set along the entire grouting sleeve on the outside of the prefabricated building. The full coverage line source serves as both a transducer and a reflected wave sensor; S4: strain sensor and reflected wave sensor collect data through acquisition card; S5: After data processing, the signals received by the strain sensor and the reflected wave sensor are subjected to time domain analysis to obtain defect detection results inside the sleeve. The defect detection results reflect the results of grouting defects inside the sleeve.

2. The method for detecting sleeve grouting defects based on full coverage line source according to claim 1 is characterized in that: The strain sensor is arranged on the inner wall of the sleeve and is parallel to the sleeve. The strain sensor runs through the sleeve and is used to collect the strain response inside the entire sleeve.

3. The method for detecting sleeve grouting defects based on full coverage line source according to claim 1 is characterized in that: The strain sensor is an optical fiber sensor.

4. The method for detecting sleeve grouting defects based on full coverage line source according to claim 1 is characterized in that: The full coverage line source adopts ultrasonic signals excited by linear array probes.

5. The method for detecting sleeve grouting defects based on full coverage line source according to claim 1 is characterized in that: The full coverage line source includes a signal trigger.

6. The method for detecting sleeve grouting defects based on full coverage line source according to claim 1 is characterized in that: In S5, MATLAB is used to perform time domain analysis.

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