CN109470769B - Method and system for detecting sleeve grouting fullness by ultrasonic reflection method - Google Patents

Abstract

The invention provides a method and system for detecting the fullness of grouting sleeve by ultrasonic reflection method. frequency to enable the identification of smaller defects. The detection method includes arranging a plurality of measuring points on the outer surface of the protective layer of the concrete member grouting sleeve along the length direction of the sleeve; arranging ultrasonic transducers with functions of exciting ultrasonic waves and receiving ultrasonic waves at the measuring points; The ultrasonic transducer receives the intensity of the reflected wave signal at the inner wall of the sleeve to judge the fullness of the grouting inside the sleeve. The detection method of the invention directly arranges the measurement points on the surface of the concrete member, is simple and quick, does not need to pre-embed the sensor in advance, and belongs to the non-destructive detection technology.

Description

Method and system for detecting sleeve grouting fullness by ultrasonic reflection method

technical field

The invention relates to the technical field of prefabricated buildings, in particular to a method and a system for detecting the fullness of sleeve grouting by an ultrasonic reflection method.

Background technique

A prefabricated building means that some or all of the components and parts of the building are produced in a prefabricated factory, and then transported to the construction site. Reliable connection methods and installation machinery are used to assemble the components to form a building with design and use functions. Compared with the cast-in-place structure, the prefabricated structure has the advantages of convenient construction, fast project progress, less impact on the surrounding environment, and easy to ensure the quality of building components. Prefabricated structures are widely used in industrial buildings in my country. In the past ten years, they have been vigorously promoted and applied in civil buildings, especially residential buildings.

Sleeve grouting connection is one of the main connection methods of steel bars in prefabricated concrete structures. This technology realizes steel bar connection through special sleeves and high-strength non-shrinkage grouting materials. It has the advantages of fast construction, simple stress, small additional stress, and wide application Wide, easy to absorb construction errors and other advantages. Because the number of joints in the same section of the component is 100%, and it is generally in the important stress-bearing part of the component, the quality of the connection is very important. If the grouting inside the sleeve is not full, the steel bar connection will not reach the expected performance of the design. , it may bring serious structural safety hazards.

During the construction process, there were frequent occurrences of grout leakage, less irrigation and blockage inside the sleeve, and engineering problems that the connection quality of the sleeve did not meet the requirements were also reported. During the project acceptance, the problem of grouting fullness was particularly concerned. The sleeve is mainly made of steel and is embedded in the concrete. The steel bars are inserted into the sleeve and then grouted into the sleeve. Therefore, it is difficult to detect the grouting defect inside the sleeve from the concrete surface. The sleeve designs of different diameters and manufacturers are slightly different. The average cross-sectional size of the grouting material in the common sleeve cavity is about 10mm, and the minimum size is about 5mm. Identifying grouting defects below 10mm is extremely challenging for concrete nondestructive testing technology. of.

At present, many scholars have studied the detection of the internal defects of the sleeve by ultrasonic waves on the concrete surface. Considering the influence of the aggregate in the concrete, it is necessary to find a balance between the ultrasonic frequency and the minimum identifiable defect size. Low-frequency ultrasound cannot identify defects below the 10mm level. Due to the complexity of the detection object, the research progress of non-destructive testing technology for detecting grouting defects inside the sleeve through ultrasonic penetration of concrete is slow, and the existing results cannot meet the requirements of engineering use.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide a method and system for detecting the fullness of sleeve grouting by ultrasonic reflection method, which can not damage the surface of the concrete member, nor does it need pre-embedded sensors, and can accurately A method and system for detecting internal grouting fullness of a fabricated structural sleeve.

According to one aspect of the present invention, there is provided a method for detecting the fullness of sleeve grouting by ultrasonic reflection method, comprising the following steps:

Arranging a plurality of measuring points along the length direction of the sleeve on the outer surface of the protective layer of the grouting sleeve of the concrete member;

An ultrasonic transducer with functions of exciting ultrasonic waves and receiving ultrasonic waves is arranged at the measuring point as a whole or as a separate body;

After the ultrasonic transducer excites the ultrasonic wave, the ultrasonic wave propagates in the concrete protective layer and the grouting sleeve of the concrete member, and the ultrasonic wave is reflected at the interface between the concrete and the sleeve, the interface between the sleeve and the grouting material, etc. When there is grouting material inside the sleeve, the ultrasonic wave is weakly reflected at the interface between the inner wall of the sleeve and the grouting material, and most of the ultrasonic waves continue to propagate; Strong reflection occurs at the interface between the inner wall of the sleeve and the air; the ultrasonic transducer receives the reflected wave signal;

Determine whether there is grouting material in the sleeve at the measuring point according to the signal strength of the reflected wave at the inner wall of the sleeve, and judge whether the sleeve has grouting material in the sleeve at a plurality of the measuring points. fullness of grout inside.

Preferably, the frequency of the ultrasonic transducer is between 0.5MHz and 2MHz.

Preferably, the signal strength of the reflected wave includes the amplitude of the reflected wave at the inner wall of the sleeve.

Preferably, it also includes the following steps:

Count the amplitude values of the reflected waves at the inner wall of the sleeve with the same protective layer, the same specification and model, and dense grouting to determine the standard amplitude A _k of the reflected wave signal, and take the critical amplitude A ₀ =K·A _k , the value of the coefficient K is greater than 1; compare the amplitude A of the reflected wave at the inner wall of the measured sleeve with the critical amplitude A ₀ , when A is greater than A ₀ , it is judged that there is no grouting inside the sleeve at the measuring point material; or,

By exchanging ultrasonic transducers of different frequencies, or adjusting the parameters of ultrasonic transmitting and receiving signals, the ultrasonic transducer cannot receive the reflected wave signal at the inner wall of the sleeve when there is grouting material inside, and receives the reflected wave signal when there is no grouting material inside. If there is an obvious reflected wave signal at the inner wall of the sleeve, when there is an obvious reflected wave signal, it is judged that there is no grouting material inside the sleeve at the measuring point.

Preferably, measuring lines are arranged along the length direction of the sleeve on the outer surface of the protective layer, and a plurality of the measuring points are sequentially arranged on the surface of the protective layer along the measuring lines.

Preferably, the distance between a plurality of the measuring points is 5mm to 20mm.

Preferably, the thickness of the protective layer is 15mm to 50mm.

According to another aspect of the present invention, there is provided a method for detecting the fullness of sleeve grouting by ultrasonic reflection method, which is used for the above-mentioned detection method, comprising:

concrete elements;

Grouting sleeves inside concrete elements;

Ultrasonic transducer with the functions of exciting ultrasonic wave and receiving ultrasonic wave as one or separate parts;

The sound wave emission, collection and analysis device is connected with the ultrasonic transducer and is used to control the ultrasonic transducer to emit sound waves and collect data for analysis and judgment.

Preferably, the thickness of the protective layer is 15mm to 50mm.

As can be seen from the above technical solutions, the advantages and positive effects of the present invention are:

Aiming at the deficiencies in the prior art, the detection method of the invention utilizes the reflected wave propagation characteristics of ultrasonic waves when the grouting is not full, and directly arranges the measuring points on the surface of the concrete member, without pre-embedding sensors in advance, and avoids damage to the concrete protective layer. It belongs to non-destructive testing means, and has simple operation steps, good applicability, intuitive testing results, high reliability, and can accurately judge the fullness of grouting in the sleeve. Random sampling inspection can be realized, and no repair measures are required after the inspection is completed, which improves the inspection efficiency and reduces the implementation cost.

Description of drawings

The above and other features and advantages of the present invention will become more apparent from the detailed description of example embodiments thereof with reference to the accompanying drawings.

1 is a schematic diagram of a concrete member in a detection method according to an embodiment of the present invention;

2 is a schematic diagram of a concrete member in a detection method according to another embodiment of the present invention;

FIG. 3 is a schematic top view showing that there is grouting material inside the sleeve during the detection process of FIG. 1;

FIG. 4 is a schematic top view showing that there is no grouting material inside the sleeve during the detection process of FIG. 2;

Fig. 5 is a survey line layout diagram of an embodiment of the present invention;

Fig. 6 is the reflected wave signal of testing grouting full place according to the detection method of the present invention;

Fig. 7 is the reflected wave signal of testing ungrouted place according to the detection method of the present invention;

In the figure: 1. Ultrasonic transducer; 2. Sound wave emission and acquisition and analysis device; 3. Sleeve; 4. Grouting port; 5. Grouting port; 6. Upper steel bar; 7. Lower steel bar;

Detailed ways

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments, however, can be embodied in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed descriptions will be omitted.

According to the existing structural design specifications, the thickness of the protective layer is generally between 15mm and 50mm. The detection of the grouting fullness of the sleeve can only focus on the propagation characteristics of ultrasonic waves in the concrete protective layer and the sleeve. When analyzing whether there is grouting material in the sleeve, the ultrasonic propagation path is short, which is different from the traditional detection of internal defects in concrete, which must use a low-frequency ultrasonic transducer. Identification of small defects.

From the wave propagation characteristics, it can be known that for the vertically incident ultrasonic wave, its sound pressure reflectivity is:

Among them, Z ₁ and Z ₂ are the acoustic impedance values of the first medium and the second medium, respectively.

When the ultrasonic wave propagates in the medium, the attenuation of its displacement amplitude with the propagation distance can be calculated according to the following formula:

A=A ₀ e ^-α(x) (2)

Among them, A represents the displacement amplitude after propagation x distance, A ₀ represents the initial amplitude, and α(x) represents the attenuation coefficient of the medium.

In comparison, since the ultrasonic impedances of concrete and steel are relatively close, it can be seen from formula (1) that the reflected energy of ultrasonic waves at the interface of concrete and steel is relatively small, and most of the ultrasonic waves continue to propagate into the grouting sleeve. If there is dense grouting material in the sleeve, since the ultrasonic impedance of the steel and the grouting material is relatively close, the ultrasonic wave is still mainly transmitted at the interface between the inner wall of the sleeve and the grouting material; if there is no grouting material in the sleeve, due to the steel and air The ultrasonic impedance difference is very large, then the ultrasonic wave is mainly reflected at the inner wall of the sleeve and the air interface. At this time, the propagation path of the reflected wave head wave signal received by the transducer is approximately equal to 2 of the sum of the thickness of the protective layer and the wall thickness of the sleeve. times. The high-frequency ultrasonic wave attenuates quickly in concrete, and the thickness of the component is much larger than the thickness of the concrete protective layer. It can be seen from formula (2) that when there is grouting material inside the sleeve, the amplitude of the first wave of the received ultrasonic reflection signal is low, Even the reflected wave information cannot be received; when there is no grouting material inside the sleeve, the amplitude of the first wave of the received ultrasonic reflected signal is high.

Based on the above principles, referring to FIG. 1 to FIG. 7 , an embodiment of the present invention discloses a method and a system for detecting the fullness of grouting of a sleeve by an ultrasonic reflection method. The detection method includes the following steps:

In this example, ultrasonic reflection method is used to detect the grouting fullness of the sleeve of the fabricated structure. The fabricated structure includes a concrete member 8 in which a grouting sleeve 3 is pre-embedded. The sleeve 3 is injected with grouting material from the grouting port 4, and the grouting material fills the inner space of the sleeve 3. After the grouting material is solidified, the upper steel bar 6 and the lower steel bar 7 inserted into the sleeve 3 are connected, so as to realize the concrete structure. Rebar connection in 9.

According to the design drawing shown in FIG. 5 , the shear wall concrete member 8 pre-embedded with grouting sleeves of different plumpness is fabricated and processed. A survey line is arranged on the surface of the concrete member 8 along the length direction of the sleeve 3 . In this embodiment, the sleeve 3 is arranged vertically, so the longitudinal direction of the sleeve 3 is also the vertical direction. Each measuring point is longitudinally arranged on the sleeve 3 in turn along the measuring line, and the ultrasonic transducer 1 is arranged at each measuring point. Can ensure the accuracy of detection.

According to the thickness of the protection and the thickness of the sleeve wall, high-frequency ultrasonic transducers with different working frequencies, such as transducers with a working frequency of 1.5MHz, are selected. The integrated ultrasonic transducer 1 is convenient for on-site operation and makes the overall structure simple.

After the ultrasonic transducer 1 excites the ultrasonic wave, the ultrasonic wave propagates in the concrete member 8, and the high-frequency ultrasonic wave has a weak first reflection at the interface between the protective layer and the outer wall of the sleeve 3, and the rest Part of it continues to propagate in the sleeve 3. When there is dense grouting material inside the sleeve 3, the ultrasonic wave will have a weak second reflection at the interface between the inner wall of the sleeve 3 and the grouting material. The remaining parts continue to propagate, as shown in Figures 1 and 3; when there is no grouting material inside the sleeve 3, the ultrasonic waves are strongly reflected at the interface between the inner wall of the sleeve 3 and the air, and the receiving The main propagation path to the ultrasonic reflected first wave signal is equal to twice the sum of the wall thickness of the grouting sleeve and the thickness of the protective layer, as shown in Figures 2 and 4. In the case that there is grouting material inside the sleeve and there is no grouting material inside the sleeve, the reflected signal of ultrasonic waves at the inner wall of the sleeve is quite different, so the sleeve at the measuring point can be judged according to the strength of the received reflected wave signal. Whether there is grouting material in the cylinder 3. When there is grouting material in the sleeve, the reflected signal received from the inner wall of the sleeve is weak, as shown in Figure 6; when there is no grouting material in the sleeve, the reflected signal received from the inner wall of the sleeve is stronger, as shown in Figure 6 7 is shown. The fullness of the grouting in the sleeve 3 is comprehensively judged according to whether there is grouting material in the sleeve 3 at a plurality of measuring points.

In this embodiment, statistics are made on the reflected wave amplitude values at the surface of the concrete member with the same protective layer and the same specification and model embedded in the casing 3 and the grouting is densely received from the inner wall of the casing, and the standard amplitude A _k of the reflected wave signal is determined. , take the critical amplitude A ₀ =1.2·A _k . Compare the reflected wave amplitude A at the measured location with the critical amplitude A ₀ . When A is greater than A ₀ , it is judged that there is no grouting material in the sleeve 3 at the measuring point. On the contrary, it is judged that there is grouting in the sleeve 3 at the measuring point. material. Finally, comprehensively judge the fullness of the grouting of the sleeve 3 according to whether there is grouting material in the sleeve 3 at multiple measuring points. For example, if there is grouting material at half of the measuring points and no grouting material at half of the measuring points, the fullness of grouting is judged to be 50%.

The detection method of the present invention aims at the deficiencies in the prior art. As shown in Fig. 1 to Fig. 4, the detection device is directly arranged on the surface of the concrete member 8, no sensor needs to be arranged in advance, and the damage to the concrete protective layer is also avoided, and the operation steps are simple, It has good applicability, intuitive detection results, and high reliability. It belongs to random non-destructive testing, and can accurately judge the fullness of the grouting in the sleeve 3 . No need to take any repair measures after the detection is completed, the detection efficiency is improved, and the implementation cost is reduced.

As shown in FIG. 1 to FIG. 4 , an embodiment of the present invention also discloses a system for detecting the fullness of grouting of an assembled structural sleeve by an ultrasonic reflection method, which is used for the above-mentioned detection method. The detection system includes:

The prefabricated concrete member 8 is provided with a grouting sleeve 3 inside; the concrete protective layer is located on the radial outer side of the sleeve 3; the ultrasonic transducer 1 can both excite ultrasonic waves and receive ultrasonic waves; It is connected with the ultrasonic transducer 1 and is used to control the ultrasonic transducer 1 to emit sound waves and collect data for analysis and judgment. The transmitting and collecting analysis device 2 is also used to record the waveform of the reflected wave and analyze and determine the amplitude of the reflected wave.

In the detection system, the concrete member 8 can be directly detected, without destroying the surface of the concrete member 8, and without reserving a detection position or pre-embedding a sensor, which improves the detection efficiency. In addition, the safety and durability of the concrete member 8 are not affected, and the integrity of the structure is ensured.

Exemplary embodiments of the present invention have been specifically shown and described above. It should be understood that this invention is not limited to the disclosed embodiments, but on the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (7)

1. a method for detecting sleeve grouting plumpness by ultrasonic reflection method, is characterized in that, comprises the steps: Arranging a plurality of measuring points along the length direction of the sleeve on the outer surface of the protective layer of the grouting sleeve of the concrete member; An ultrasonic transducer with functions of exciting ultrasonic waves and receiving ultrasonic waves is arranged at the measuring point; After the ultrasonic transducer excites the ultrasonic wave, the ultrasonic wave propagates in the concrete protective layer of the concrete member and the grouting sleeve, and the ultrasonic wave is reflected at the interface between the concrete and the sleeve and the interface between the sleeve and the grouting material. When there is grouting material inside the sleeve, the ultrasonic wave is weakly reflected at the interface between the inner wall of the sleeve and the grouting material, and most of the ultrasonic waves continue to propagate; when there is no grouting material inside the sleeve, the ultrasonic wave is reflected in the Strong reflection occurs at the interface between the inner wall of the sleeve and the air; the ultrasonic transducer receives the reflected wave signal; Determine whether there is grouting material in the sleeve at the measuring point according to the signal strength of the reflected wave at the inner wall of the sleeve, and judge whether the sleeve has grouting material in the sleeve at a plurality of the measuring points. internal grouting fullness; The frequency of the ultrasonic transducer is between 0.5MHz and 2MHz; It also includes the following steps: Count the amplitude values of the reflected waves at the inner wall of the sleeve with the same protective layer, the same specification and model, and dense grouting to determine the standard amplitude A _k of the reflected wave signal, and take the critical amplitude A ₀ =K·A _k , the value of the coefficient K is greater than 1; compare the amplitude A of the reflected wave at the inner wall of the measured sleeve with the critical amplitude A ₀ , when A is greater than A ₀ , it is judged that there is no grouting inside the sleeve at the measuring point material; or, By exchanging ultrasonic transducers of different frequencies, or adjusting the parameters of ultrasonic transmitting and receiving signals, the ultrasonic transducer cannot receive the reflected wave signal at the inner wall of the sleeve when there is grouting material inside, and receives the reflected wave signal when there is no grouting material inside. If there is an obvious reflected wave signal at the inner wall of the sleeve, when there is an obvious reflected wave signal, it is judged that there is no grouting material inside the sleeve at the measuring point. 2 . The method for detecting grouting fullness of a sleeve by ultrasonic reflection method according to claim 1 , wherein the signal strength of the reflected wave includes the amplitude of the reflected wave at the inner wall of the sleeve. 3 . 3. The method for detecting sleeve grouting fullness by ultrasonic reflection method according to claim 1, wherein a measuring line is arranged along the length direction of the sleeve on the outer surface of the protective layer, and a plurality of the measuring lines are arranged. Points are sequentially arranged on the surface of the protective layer along the survey line. 4 . The method for detecting fullness of sleeve grouting by ultrasonic reflection method according to claim 1 , wherein the distance between a plurality of the measuring points is 5 mm to 20 mm. 5 . 5 . The method for detecting sleeve grouting fullness by ultrasonic reflection method according to claim 1 , wherein the thickness of the protective layer is 15mm to 50mm. 6 . 6. A system for detecting the fullness of sleeve grouting by ultrasonic reflection method, for the detection method according to any one of claims 1 to 5, characterized in that, comprising: concrete elements; Grouting sleeves inside concrete elements; Ultrasound transducer with functions of exciting ultrasound and receiving ultrasound; The sound wave emission, collection and analysis device is connected with the ultrasonic transducer and is used to control the ultrasonic transducer to emit sound waves and collect data for analysis and judgment. 7 . The system for detecting the fullness of sleeve grouting by ultrasonic reflection method according to claim 6 , wherein the thickness of the protective layer is 15 mm to 50 mm. 8 .

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