Nondestructive testing method for whether the connecting steel bars at the sleeve assembly end in prefabricated walls are cut off

Abstract

The present invention discloses a nondestructive detection method for whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off. In the working condition where the upper prefabricated wall and the lower prefabricated wall are connected by grouting of the steel sleeve, a radiograph and an imaging plate are used for detection; the floor slab, the upper prefabricated wall and the lower prefabricated wall cooperate to form a cross area, the radiograph and the imaging plate are placed in the cross area and arranged diagonally in staggered layers, the ray emission window of the radiograph is arranged obliquely upward and toward the bottom of the sleeve, and the imaging plate is arranged obliquely downward and toward the bottom of the sleeve; the X-ray machine is started for shooting, and an imaging image of the connecting steel bars at the assembly end passing through the inside of the joint of the floor slab and the bottom of the wall and inserted into the sleeve is obtained, and whether the connecting steel bars at the assembly end are cut off under the sleeve is identified from the imaging image. The present invention does not need to be chiseled, and can nondestructively detect whether the connecting steel bars at the sleeve assembly end are cut off, and the result is accurate and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of prefabricated buildings, and in particular to a nondestructive detection method for determining whether a connecting steel bar at an assembly end of a sleeve in a prefabricated wall is cut off. Background Art

[0002] At present, most of the vertical connections of stress-bearing steel bars in my country's prefabricated concrete structures are made by sleeve grouting. The connection nodes of prefabricated components are theoretically weak links in prefabricated concrete structures, and the connecting steel bars in the sleeves are the main bearers of load transfer between different prefabricated components. However, whether the connecting steel bars in the sleeves can play a connecting role in transferring loads is not only related to the fullness of the grouting in the sleeves, but also has an important premise that the connecting steel bars at the sleeve assembly end must be fully anchored to the lower structure and are not allowed to be cut off at the horizontal joints below the sleeves.

[0003] Grouting sleeves can be divided into semi-grouting sleeves and full-grouting sleeves according to their forms. The upper and lower steel bars in the full-grouting sleeve are connected by sleeve grouting, the lower steel bars in the semi-grouting sleeve are connected by sleeve grouting, and the upper steel bars are connected by mechanical connection. Whether it is a full-grouting sleeve or a semi-grouting sleeve, the upper steel bars in the sleeve are installed when the component is made, and the construction accuracy is easy to ensure. The problem mainly exists in the connection of the lower steel bars at the on-site assembly end. Due to deviations during component production or on-site installation, the lower steel bars will deviate from the sleeve position. When the component is installed, some of the lower steel bars cannot be inserted into the sleeve. In this case, in order to catch up with the construction progress, the hoisting workers will directly cut off the steel bars that are in the way, and continue to install the component after "a little treatment".

[0004] In order to evade detection and create the illusion that the steel bar has not been cut, there are currently several ways to deal with the cut steel bar on site: (1) directly insert the cut steel bar into the sleeve, and the steel bar will be placed in an inclined state in the sleeve. After the sleeve is filled with grout, the steel bar will still be in an inclined state; (2) drill a shallow hole in the floor slab directly below the sleeve, and then insert the lower end of the steel bar into the shallow hole and the upper end into the sleeve. At this time, the steel bar can remain upright in the sleeve. (3) spot weld the lower end of the steel bar to the remaining section of the steel bar exposed on the floor slab or the remaining section of the steel bar buried in the shallow part of the floor slab, and insert the upper end into the sleeve. At this time, the steel bar can remain upright in the sleeve. For the first treatment method, since the steel bar is in an inclined state, it can be discovered by arranging X-ray machines and imaging plates on the same layer on both sides of the wall and performing X-ray detection. However, for the second and third treatment methods, the steel bars are still in an upright state after the grouting is completed in the sleeve. The X-ray method is limited by the placement of the imaging plate and the radiation angle when the rays are emitted from the emission window. The lower edge of the actual imaging part of the imaging plate placed on the upper surface of the floor slab after removing the frame is almost flush with the bottom of the sleeve. Therefore, the X-ray method cannot capture the bottom of the sleeve and the part below the bottom of the sleeve. Figure 1 As shown, it is impossible to determine whether the bottom of the steel bar is cut off only from the upright shape of the steel bar in the image.

[0005] At present, the only judgment method is the damage inspection method, which is to open the bottom joint under the prefabricated wall from the side where the sleeve connects the steel bars, and "completely" clean the sealing grouting material around the bottom joint and the grouting material covering the position of the steel bars. After the connecting steel bars are exposed, it is necessary to use an impact drill to remove the concrete in the floor slab below the root of the steel bars. After this part of the concrete is chiseled out, if the steel bars are found to be discontinuous through endoscope observation, it can be determined that the steel bars are cut off. This method involves a large amount of chiseling, and it is easy to accidentally damage the steel bars during chiseling, which causes certain damage to the connection parts of the structure.

[0006] Therefore, it is necessary to develop a nondestructive detection method for whether the connecting steel bars at the sleeve assembly end in the prefabricated wall are cut off. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a non-destructive detection method for whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off, which can detect and judge the connecting steel bars without chiseling, and the result is accurate and reliable.

[0008] In order to solve the above technical problems, the present invention provides a non-destructive detection method for whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off, comprising an upper prefabricated wall and a lower prefabricated wall, wherein a sleeve is arranged at the bottom of the upper prefabricated wall, and the connecting steel bars at the assembly end extend out of the top of the lower prefabricated wall, and the connecting steel bars at the assembly end pass through the floor slab between the upper prefabricated wall and the lower prefabricated wall and the joint at the bottom of the wall and then are inserted into the sleeve to form a grouting connection, characterized in that: a X-ray machine and an imaging plate are used for detection;

[0009] The floor slab, the upper prefabricated wall and the lower prefabricated wall cooperate to form a cross area, the X-ray machine and the imaging plate are placed in the cross area and arranged diagonally in staggered layers, the imaging plate is arranged on the surface of the upper prefabricated wall at a side that is closer to the measured sleeve at a vertical distance; the X-ray emission window of the X-ray machine is arranged obliquely upward and toward the bottom of the sleeve, the X-ray machine is close to the node between the lower prefabricated wall and the floor slab, the imaging plate is arranged obliquely downward and toward the bottom of the sleeve, and the imaging plate is close to the node between the upper prefabricated wall and the floor slab;

[0010] The X-ray machine is started to take pictures to obtain an image of the assembly end connecting steel bar passing through the inside of the joint between the floor slab and the bottom of the wall and inserted into the sleeve, and it is identified from the image whether the assembly end connecting steel bar is cut off under the sleeve.

[0011] Furthermore, the X-ray machine is arranged according to the following steps:

[0012] Determine the direction of the main axis of the ray, make a cross-section of the prefabricated wall and floor through the center axis of the sleeve, the intersection of the center axis of the sleeve and the upper surface of the floor in the cross-section is defined as the shooting center point, the intersection of the lower prefabricated wall and the lower surface of the floor in the ray machine layout area in the cross-section is defined as the ray incident point, and the line between the shooting center point and the ray incident point is the main axis direction of the ray;

[0013] Determine the angle between the ray emission window and the horizontal plane. The thickness of the prefabricated wall is b, the distance from the central axis of the sleeve to the near end surface of the upper prefabricated wall is a, the thickness of the floor is c, and the angle between the ray emission window and the horizontal plane is ;

[0014] Determine the setting position of the center of the ray emission window. The control distance f between the center of the ray emission window and the ray incident point is set between 300㎜ and 500㎜. The vertical distance between the center of the ray emission window and the surface of the lower prefabricated wall is , the vertical distance between the center of the ray emission window and the lower surface of the floor ;

[0015] Install the X-ray machine on the X-ray machine lifting frame, use an angle ruler to adjust the angle between the X-ray emission window and the horizontal plane to α, adjust the vertical distance between the center of the X-ray emission window and the surface of the lower prefabricated wall to d, raise the height of the X-ray machine lifting frame, and adjust the vertical distance between the center of the X-ray emission window and the lower surface of the floor to e.

[0016] Further, the imaging plate is arranged according to the following steps:

[0017] Determine the angle between the imaging plate and the vertical plane. The imaging plate is kept perpendicular to the main axis of the ray, and the angle between the imaging plate and the vertical plane is equal to α;

[0018] Determine the placement positions of the upper and lower ends of the imaging board. The lower end of the imaging board is supported on the upper surface of the floor slab, and the upper end of the imaging board is supported on the surface of the upper prefabricated wall. The height of the imaging board is h;

[0019] The vertical distance between the support point at the bottom of the imaging plate and the surface of the upper prefabricated wall , the vertical distance between the support point at the top of the imaging plate and the upper surface of the floor ;

[0020] The imaging plate is arranged obliquely according to the positions of the fulcrum at the lower end and the fulcrum at the upper end of the imaging plate.

[0021] Furthermore, the tube voltage of the X-ray machine during shooting is greater than 300 kV, and the exposure time is not less than 0.3 min.

[0022] Furthermore, the effective imaging area of ​​the imaging plate is not less than 300 mm×400 mm.

[0023] Furthermore, the following features are used to determine whether there are signs of truncation of the connecting steel bars at the assembly end below the sleeve:

[0024] The steel bar connected to the assembly end is presented as a single bar in the image, and the steel bar is inserted into the bottom of the sleeve in a straight line, which is judged to be uncut;

[0025] The steel bar connected to the assembly end is shown as a single bar in the image, and the steel bar is bent and deformed before being inserted into the bottom of the sleeve. It is judged that it is not cut off, but it shows that there is a misalignment between the steel bar connected to the assembly end and the sleeve, and the steel bar is bent before being inserted into the sleeve;

[0026] The assembly end connecting steel bars are presented as double roots in the image. The assembly end connecting steel bars form upper steel bars and lower steel bars. The overlapping length of the upper steel bars and the lower steel bars in the junction area is short, which is judged to be truncated. The upper steel bars and the lower steel bars are connected at the joint at the bottom of the wall and then inserted into the sleeve.

[0027] The assembly-end connecting steel bars appear as double roots as a whole in the imaging diagram. The assembly-end connecting steel bars form an upper section of steel bars and a lower section of steel bars. The overlapping length of the upper section of steel bars and the lower section of steel bars in the junction area is relatively long, and it is judged to be truncated. The upper section of steel bars is inserted into the sleeve after being implanted to a certain depth in the floor slab.

[0028] Furthermore, the control distance f between the center of the ray emission window and the ray incident point is set to 400 mm.

[0029] Furthermore, when determining the layout position of the X-ray machine at the construction site, first use a steel bar scanner and combine with the design drawings to determine the horizontal position of the sleeve center axis at the bottom of the upper prefabricated wall, and then determine the sleeve projection of the sleeve center axis on the surface of the upper prefabricated wall farther from the sleeve. The intersection of the extension line of the sleeve projection and the lower surface of the floor slab is the ray incident point, and the projection point of the ray emission window center on the surface of the lower prefabricated wall is located on the extension line of the sleeve projection.

[0030] Beneficial effects of the present invention:

[0031] 1. By arranging the X-ray machine and the imaging plate diagonally in staggered layers, the rays are emitted toward the bottom of the sleeve and received by the imaging plate which is also oriented toward the bottom of the sleeve. After image processing, an image of the assembly end connecting steel bar passing through the inside of the joint at the bottom of the floor slab and the wall and inserted into the sleeve can be formed. From the image, it can be identified whether the assembly end connecting steel bar is cut off under the sleeve. The present invention belongs to non-destructive testing technology, does not require chiseling, does not cause any damage to the structure, and is convenient and fast.

[0032] 2. By reasonably selecting the shooting center point, the position of the ray incident point and the direction of the ray main axis determined thereby, it is ensured that the key shooting area is covered, ensuring that the bottom of the sleeve, the joint area at the bottom of the wall and the thickness area of ​​the upper half of the floor slab can be photographed at the same time, and the penetration thickness of each ray corresponding to the key shooting area in the wall and floor slab is at a relatively small level. At the same time, it is also convenient for the inspection personnel to quickly determine the layout position of the X-ray machine.

[0033] 3. Thanks to the present invention, the whole process of the assembly-end connecting steel bar passing through the bottom joint of the floor slab and the wall and being inserted into the sleeve can be imaged. From the image, the four situations of "the assembly-end steel bar is not cut off and inserted into the sleeve normally", "the assembly-end steel bar is not cut off but is bent and inserted into the sleeve", "the assembly-end steel bar is cut off and connected at the bottom joint of the wall and then inserted into the sleeve" and "the assembly-end steel bar is cut off and inserted into the sleeve after being implanted to a certain depth in the floor slab" can be clearly distinguished, which is conducive to the demarcation of responsibilities and exploration of causes of engineering quality problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a detection schematic diagram of arranging X-ray machines and imaging plates on the same layer on both sides of the wall in the prior art;

[0035] Figure 2 It is a schematic diagram of the layout position of the present invention during detection;

[0036] Figure 3 This is a schematic diagram of the division of key shooting areas of the present invention under the working conditions of a wall thickness of 200 mm and a floor thickness of 130 mm;

[0037] Figure 4 is an image captured by sleeve No. 1 in Example 1 of the present invention;

[0038] Figure 5 The present invention Figure 4 The outer contour of the medium imaging image is outlined;

[0039] Figure 6 This is an image taken by sleeve No. 2 in Example 1 of the present invention;

[0040] Figure 7 The present invention Figure 6 The outer contour of the medium imaging image is outlined;

[0041] Figure 8 It is a structural diagram of the assembly end connecting steel bar being cut off and then reconnected at the bottom joint;

[0042] Fig. 9 It is a connection diagram in which the connecting steel bars at the assembly end are cut off and then embedded into the floor slab at a certain depth;

[0043] Fig.10 This is a schematic diagram of the division of key shooting areas of the present invention under the working conditions of 200mm thick wall and 120mm thick floor;

[0044] Fig.11 This is a schematic diagram of the division of key shooting areas of the present invention under the working conditions of a wall thickness of 250 mm and a floor thickness of 120 mm;

[0045] Fig.12 It is a schematic diagram of the division of key shooting areas of the present invention under the working conditions of a wall thickness of 250 mm and a floor thickness of 130 mm. DETAILED DESCRIPTION

[0046] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Example 1

[0047] An embodiment of a nondestructive detection method for determining whether a sleeve assembly end connecting steel bar is cut off in a prefabricated wall of the present invention comprises an upper prefabricated wall 1 and a lower prefabricated wall 2. This embodiment is working condition 1. The thickness b of the upper prefabricated wall and the lower prefabricated wall are both 200 mm. A sleeve 3 is arranged at the bottom of the upper prefabricated wall. The distance a from the central axis of the sleeve to the proximal surface of the upper prefabricated wall is 52 mm. The top of the lower prefabricated wall extends out of the assembly end connecting steel bar 4. The assembly end connecting steel bar passes through the upper prefabricated wall. The floor slab 5 between the wall and the lower prefabricated wall and the bottom joint of the wall are inserted into the sleeve to form a grouting connection. The thickness c of the floor slab is 130 mm, and the thickness of the bottom joint of the wall is 20 mm. The detection is carried out by using a ray machine 6 and an imaging board 7. The ray machine uses a portable X-ray machine of model XXG-3505D. The voltage setting range of the ray machine is 200kv-350kv. The maximum penetration ability of this model of ray machine to concrete medium is about 380 mm after testing. The imaging board uses a digital imaging board of model NDT1417. The height h of the imaging board is 380 mm. The effective imaging area of ​​the imaging board is 345.6 mm×420 mm. The large effective imaging area can ensure that even if the ray machine emission window is not fully aligned with the sleeve, the imaging can be successfully taken.

[0048] The floor slab, the upper prefabricated wall and the lower prefabricated wall cooperate to form a cross area, the X-ray machine and the imaging plate are placed in the cross area and arranged diagonally in staggered layers, the imaging plate is arranged on the surface of the upper prefabricated wall at a side that is closer to the measured sleeve at a vertical distance; the X-ray emission window of the X-ray machine is arranged obliquely upward and toward the bottom of the sleeve, the X-ray machine is close to the node between the lower prefabricated wall and the floor slab, the imaging plate is arranged obliquely downward and toward the bottom of the sleeve, and the imaging plate is close to the node between the upper prefabricated wall and the floor slab; Figure 2 shown.

[0049] When installing the prefabricated wall, if the assembly end connecting steel bar at the top of the lower prefabricated wall cannot be inserted into the sleeve at the bottom of the upper prefabricated wall, the installer will cut the assembly end connecting steel bar at the root position extending out of the floor slab, and then continue to install the upper prefabricated wall, but will not cut it in the middle or upper part of the extended section of the assembly end connecting steel bar, because the upper prefabricated wall cannot be installed in this way. Therefore, the key technical problem to be solved by the present invention is how to judge whether the assembly end connecting steel bar below the sleeve is cut off. In order to solve the above technical problems, it is required to obtain an image of the assembly end connecting steel bar passing through the inside of the joint of the floor slab and the bottom of the wall and inserting into the sleeve when taking an image by X-ray method, and then judge whether the assembly end connecting steel bar below the sleeve is cut off from the image. That is to say, for the part above the bottom of the sleeve, the range of shooting and imaging does not need to be too large, as long as the assembly end connecting steel bar can be seen entering the sleeve from the bottom of the sleeve. For the shooting and imaging range below the sleeve, the requirements are higher, and it is required to be able to show the state of the assembly end connecting steel bar in at least the upper half of the floor slab and the joint of the bottom of the wall. In summary, the key coverage areas for shooting are the bottom of the sleeve, the joint area at the bottom of the wall, and the thickness area of ​​the upper half of the floor slab.

[0050] In order to achieve the above imaging objectives, the X-ray machine is arranged according to the following steps:

[0051] Determine the direction of the main axis of the ray, make a cross-section of the prefabricated wall and floor through the center axis of the sleeve, the intersection of the center axis of the sleeve and the upper surface of the floor in the cross-section is defined as the shooting center point, the intersection of the lower prefabricated wall and the lower surface of the floor in the ray machine layout area in the cross-section is defined as the ray incident point, and the line between the shooting center point and the ray incident point is the main axis direction of the ray;

[0052] Determine the angle between the ray emission window and the horizontal plane. The thickness of the prefabricated wall is b, which is 200 mm. The distance from the central axis of the sleeve to the near end surface of the upper prefabricated wall is a, which is 52 mm. The thickness of the floor slab is c, which is 130 mm. The angle between the ray emission window and the horizontal plane is , the calculated result is 41°.

[0053] Determine the setting position of the center of the ray emission window. The control distance f between the center of the ray emission window and the ray incident point is set to 400㎜. The vertical distance between the center of the ray emission window and the surface of the lower prefabricated wall is , the calculated result of d is 302㎜, the vertical distance between the center of the ray emission window and the lower surface of the floor , the calculated result of e is 262㎜.

[0054] Install the X-ray machine on the X-ray machine lifting frame, use an angle ruler to adjust the angle between the X-ray emission window and the horizontal plane to α, α is 41°, adjust the vertical distance between the center of the X-ray emission window and the surface of the lower prefabricated wall to d, d is 302㎜, raise the height of the X-ray machine lifting frame, adjust the vertical distance between the center of the X-ray emission window and the lower surface of the floor to e, e is 262㎜.

[0055] In order to achieve better imaging effects, the emission window of the X-ray machine should be aimed at the sleeve to be photographed. When determining the layout position of the X-ray machine at the construction site, first use a steel bar scanner and combine the design drawings to determine the horizontal position of the sleeve center axis at the bottom of the upper prefabricated wall, and then determine the sleeve projection of the sleeve center axis on the surface of the upper prefabricated wall farther from the sleeve. The intersection of the extension line of the sleeve projection and the lower surface of the floor slab is the ray incident point. The projection point of the center of the X-ray machine emission window on the surface of the lower prefabricated wall is located on the extension line of the sleeve projection.

[0056] The imaging plates are arranged as follows:

[0057] Determine the angle between the imaging plate and the vertical plane. The imaging plate is perpendicular to the main axis of the ray. The angle between the imaging plate and the vertical plane is equal to α, which is 41°.

[0058] Determine the placement of the upper and lower ends of the imaging board. The lower end of the imaging board is supported on the upper surface of the floor slab, and the upper end of the imaging board is supported on the surface of the upper prefabricated wall. The height h of the imaging board is 380 mm.

[0059] The vertical distance between the support point at the bottom of the imaging plate and the surface of the upper prefabricated wall The calculated result of l is 249 mm, and the vertical distance between the support point at the top of the imaging plate and the upper surface of the floor slab is , the calculated result of g is 287㎜;

[0060] The imaging plate is arranged obliquely according to the positions of the fulcrum at the lower end and the fulcrum at the upper end of the imaging plate.

[0061] The key to whether the key shooting area can be successfully imaged is whether the thickness of the concrete medium penetrated by the rays passing through the key shooting area exceeds the penetration capacity of the ray machine. In order to demonstrate whether the key shooting area can be successfully imaged after the ray machine and imaging plate are arranged according to the above method, the CAD software is used to draw a schematic diagram of the cross area formed by the floor slab, the upper prefabricated wall and the lower prefabricated wall, and the key shooting area composed of the bottom of the sleeve, the bottom seam area of ​​the wall and the upper thickness area of ​​the floor slab is divided into upper and lower boundaries. The main axis of the ray and other rays passing through the key shooting area are drawn in the schematic diagram, such as Figure 3 shown. Figure 3In the figure, the upper boundary line 1 is located at a height of 40 mm above the upper surface of the floor slab, that is, at a height of 20 mm above the bottom of the sleeve, and the ray passing through the intersection of the upper boundary line 1 and the sleeve wall close to the side of the X-ray machine is defined as the ray corresponding to the upper boundary line 1; the upper boundary line 2 is located at a height of 60 mm above the upper surface of the floor slab, that is, at a height of 40 mm above the bottom of the sleeve, and the ray passing through the intersection of the upper boundary line 2 and the sleeve wall close to the side of the X-ray machine is defined as the ray corresponding to the upper boundary line 2; the lower boundary line 1 is located at a height of 40 mm below the upper surface of the floor slab, and the ray passing through the intersection of the lower boundary line 1 and the center axis of the steel bar connected to the assembly end is defined as the ray corresponding to the lower boundary line 1; the lower boundary line 2 is located at a height of 80 mm below the upper surface of the floor slab, and the ray passing through the intersection of the lower boundary line 2 and the center axis of the steel bar connected to the assembly end is defined as the ray corresponding to the lower boundary line 2.

[0062] The thickness of the ray main axis, the ray corresponding to the upper boundary 1, the ray corresponding to the upper boundary 2, the ray corresponding to the lower boundary 1 and the ray corresponding to the lower boundary 2 penetrating the concrete medium is measured by CAD software, and the measurement results are shown in Table 1. As can be seen from Table 1, the maximum penetration thickness appears in the ray corresponding to the upper boundary 2, which is 366mm, which does not reach the upper limit of 380mm of the XXG-3505D portable X-ray machine's ability to penetrate concrete media.

[0063] Table 1 X-ray penetration thickness measurement table in Example 1

[0064] Except for the angle α, all other units in the table are mm

[0065] Working condition number Condition 1 (wall thickness 200, floor thickness 130) a 52 b 200 c 130 f 400 h 380 α angle 41° d 302 e 262 g 287 l 249 Ray main axis penetration thickness 266 The ray penetration thickness corresponding to the upper boundary 1 341 The ray penetration thickness corresponding to the upper boundary 2 366 The ray penetration thickness corresponding to the lower boundary 1 255 The ray penetration thickness corresponding to the lower boundary 2 320

[0066] From the results in Table 1, we can see that by reasonably selecting the shooting center point, the position of the ray incident point and the direction of the ray main axis determined thereby, the penetration thickness of each ray corresponding to the key shooting area in the wall and floor is at a relatively small level. It can be seen here that the shooting center point is not located at the center of the key shooting area (the area between the upper boundary line 2 and the lower boundary line 2), but is located in the middle and upper part of the key shooting area. This arrangement is mainly based on the structural characteristics of the joint between the wall and the floor, such as Figure 3 As shown in the figure, the penetration thickness of the ray above the main axis of the ray in the wall is constantly increasing. In addition, it also needs to penetrate into the floor slab on the right, and the thickness of the ray in the floor slab is also constantly increasing. Therefore, even for the part above the bottom of the sleeve, the length range of imaging is not required to be high, and full attention should be paid to the objective law that the ray penetration thickness is constantly increasing and the growth rate is relatively fast (the penetration thickness of the main axis of the ray is 266㎜, the ray penetration thickness corresponding to the upper boundary 1 increases to 341㎜, and the ray penetration thickness corresponding to the upper boundary 2 increases to 366㎜), and the shooting center point is arranged in the middle and upper part of the key shooting area; look at the ray below the main axis of the ray, as shown in Figure 3As shown, the penetration thickness in the wall is reduced first, but as the horizontal angle of the ray continues to decrease, the ray will enter the floor slab on the left, and then increase the penetration thickness of the ray in the concrete medium again (the penetration thickness of the main axis of the ray is 266㎜, the penetration thickness of the ray corresponding to the lower boundary 1 is reduced to 255㎜, and the penetration thickness of the ray corresponding to the lower boundary 2 is increased again to 320㎜). Considering the objective law that the penetration thickness of the ray below the main axis of the ray in the concrete medium first decreases and then increases, the shooting center point is arranged in the middle and upper part of the key shooting area, and the area within a longer range below the shooting center point can also be successfully imaged. In addition, the selection of the position of the shooting center point and the ray incident point in the present invention also facilitates the detection personnel to quickly determine the layout position of the ray machine.

[0067] Since the maximum penetration thickness of the ray in this embodiment occurs at the ray corresponding to the upper boundary 2, and the thickness to be penetrated is 366 mm, the tube voltage of the X-ray machine is set to 340 kV and the exposure time is set to 0.3 min.

[0068] Take a picture of the part corresponding to sleeve No. 1, and the image is as follows: Figure 4 As shown in the figure, the effect of outlining the outer contour of the sleeve and the steel bar connected to the assembly end is as follows Figure 5 shown.

[0069] Depend on Figure 4 and Figure 5 It can be seen that the steel bar connected to the assembly end is presented as a single bar in the image, and the steel bar is inserted into the bottom of the sleeve in a straight line, so it is judged to be uncut. In addition, the outer diameter of the sleeve in this embodiment can be found to be 41.4 mm according to the product manual. Figure 5 It can be seen that the imaging length of the part from the bottom of the sleeve upwards in the imaging image is not less than the outer diameter of the sleeve, that is, the height position corresponding to the upper boundary 2 can be imaged and identified; the imaging length of the part from the bottom of the sleeve downwards in the imaging image is about 2.5 times the outer diameter of the sleeve, which exceeds 100㎜, that is, starting from the upper surface of the floor slab, a length of 80㎜ downwards can be photographed, that is, the height corresponding to the lower boundary 2 can be imaged and identified.

[0070] The corresponding part of sleeve No. 2 is photographed, and the image is as follows Figure 6 As shown in the figure, the effect of outlining the outer contour of the sleeve and the steel bar connected to the assembly end is as follows Figure 7 shown.

[0071] Depend on Figure 6 and Figure 7 It can be seen that the connecting steel bar at the assembly end appears as a single bar as a whole in the image, and the steel bar is bent and deformed before being inserted into the bottom of the sleeve. Therefore, it is judged that it is not cut off. However, it shows that there is a misalignment between the connecting steel bar at the assembly end and the sleeve, and the steel bar is bent before being inserted into the sleeve.

[0072] In addition, the outer diameter of the No. 2 sleeve is also 41.4 mm. Figure 7 It can also be seen by comparing with the outer diameter of the sleeve that the height position corresponding to the upper boundary line 2 can be imaged and identified, and the height corresponding to the lower boundary line 2 can be imaged and identified.

[0073] Combination Figures 4 to 7 It can be seen that the present invention can ensure that the bottom of the sleeve, the bottom seam area of ​​the wall and the thickness area of ​​the upper half of the floor slab are captured at the same time by reasonably selecting the shooting center point, the position of the ray incident point and the direction of the ray main axis determined thereby, thereby directly judging from the imaging image whether the connecting steel bars at the assembly end are cut off.

[0074] The above are two cases where the connecting steel bars at the assembly end are not cut off. If the connecting steel bars at the assembly end are cut off, it can also be judged by the following characteristics:

[0075] The assembly end connecting steel bar is presented as a double root shape in the image. The assembly end connecting steel bar forms an upper steel bar 43 and a lower steel bar 44. The overlapping length of the upper steel bar and the lower steel bar in the junction area is short, and it is judged to be truncated. The upper steel bar and the lower steel bar are connected at the joint at the bottom of the wall and then inserted into the sleeve. The schematic diagram of the connection structure is shown in FIG. Figure 8 The sleeve on the left is shown in the middle;

[0076] The assembly end connecting steel bar is presented as a double root shape in the imaging figure. The assembly end connecting steel bar forms an upper steel bar 41 and a lower steel bar 42. The overlapping length of the upper steel bar and the lower steel bar in the junction area is long, and it is judged to be truncated. The upper steel bar is inserted into the sleeve after being implanted into the floor slab to a certain depth. The schematic diagram of its connection structure is shown in Fig. 9 The sleeve on the left is shown in FIG. Example 2

[0077] Example 2 lists the maximum thickness of the concrete medium that the rays need to penetrate in order to capture key areas such as the bottom of the sleeve, the joint area at the bottom of the wall, and the thickness of the upper half of the floor slab in three other common wall thickness and slab thickness conditions, to demonstrate that when these three common conditions occur, the maximum penetration thickness of the rays does not exceed the penetration ability of the XXG-3505D portable X-ray machine into the concrete medium.

[0078] like Fig.10As shown in Table 2, the thickness of the prefabricated wall in working condition 2 is 200 mm, the thickness of the floor slab is 120 mm, and the distribution of the upper and lower boundaries is exactly the same as that in working condition 1. According to the measurement by CAD software, the maximum penetration thickness appears in the ray corresponding to the upper boundary 2, which is 358 mm, which does not reach the upper limit of 380 mm of the penetration ability of the portable X-ray machine of XXG-3505D for concrete media. It can be inferred that for working condition 2, the tube voltage of the X-ray machine is set to 340 kV and the exposure time is set to 0.3 min. It is possible to image and identify whether the steel bars at the assembly end are cut in the area between the upper boundary 2 and the lower boundary 2.

[0079] like Fig.11 As shown in Table 2, the thickness of the prefabricated wall in working condition 3 is 250 mm, the thickness of the floor slab is 120 mm, the distribution of the upper boundary line 1 and the lower boundary line 1 is the same as that in working condition 1, the newly defined lower boundary line 3 is located at a height of 60 mm below the upper surface of the floor slab, and the ray passing through the intersection of the lower boundary line 3 and the central axis of the assembly end connecting steel bar is defined as the ray corresponding to the lower boundary line 3. Due to the thickening of the wall, the arrangement of the upper boundary line 2 is cancelled, because only by imaging the corresponding position of the upper boundary line 1, it can be judged whether the assembly end connecting steel bar enters the sleeve. The arrangement of the lower boundary line 2 is cancelled, and the upper floor slab The length range of 60㎜ below the surface is also sufficient to determine whether the connecting steel bars at the assembly end are cut off. According to the measurement by CAD software, the maximum penetration thickness appears in the ray corresponding to the upper boundary 1, which is 365㎜, which does not reach the upper limit of 380㎜ of the portable X-ray machine of XXG-3505D for the penetration of concrete media. It can be inferred that for working condition 3, the tube voltage of the X-ray machine is set to 340kv and the exposure time is set to 0.3min. It is possible to image and identify whether the steel bars at the installation end are cut off in the area between the upper boundary 1 and the lower boundary 3.

[0080] like Fig.12 As shown in Table 2, the thickness of the prefabricated wall in working condition 4 is 250 mm, the thickness of the floor slab is 130 mm, and the distribution of the upper and lower boundaries is the same as that of working condition 3. According to the measurement by CAD software, the maximum penetration thickness appears in the ray corresponding to the upper boundary 1, which is 371 mm, which does not reach the upper limit of 380 mm of the penetration ability of the portable X-ray machine of XXG-3505D for concrete media. It can be inferred that for working condition 4, the tube voltage of the X-ray machine is set to 340 kV and the exposure time is set to 0.3 min. It is possible to image and identify whether the steel bars at the installation end are cut off in the area between the upper boundary 1 and the lower boundary 3.

[0081] Table 2 is a table of the measurement of the ray penetration thickness in Example 2;

[0082] Except for the angle α in Table 2, all other units are mm

[0083] Working condition number Condition 2: Wall thickness 200, floor thickness 120 Condition 3: Wall thickness 250, floor thickness 120 Condition 4: Wall thickness 250, floor thickness 130 a 52 52 52 b 200 250 250 c 120 120 130 f 400 400 400 h 380 380 380 α angle 39° 31° 33° d 311 343 335 e 252 206 218 g 295 326 319 l 239 196 207 Ray main axis penetration thickness 257 292 299 The ray penetration thickness corresponding to the upper boundary 1 333 365 371 The ray penetration thickness corresponding to the upper boundary 2 358 / / The ray penetration thickness corresponding to the lower boundary 1 251 309 309 The ray penetration thickness corresponding to the lower boundary 2 324 / / The ray penetration thickness corresponding to the lower boundary 3 / 356 351

[0084] In summary, as the thickness of the prefabricated wall or the floor increases, the imaging area that can be used for identification will be compressed. However, as long as the reasonable shooting center point, the position of the ray incident point and the direction of the ray main axis determined thereby are selected according to the provisions of the present invention, even if the imaging area that can be used for identification is compressed, the area that needs to be photographed, namely, the bottom of the sleeve, the bottom seam area of ​​the wall and the upper thickness area of ​​the floor, can be covered. The present invention belongs to non-destructive testing technology, does not require chiseling, does not cause any damage to the structure, and is convenient and fast.

[0085] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A nondestructive detection method for whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off, comprising an upper prefabricated wall and a lower prefabricated wall, wherein a sleeve is arranged at the bottom of the upper prefabricated wall, and the connecting steel bars at the assembly end extend out of the top of the lower prefabricated wall, and the connecting steel bars at the assembly end pass through the floor slab between the upper prefabricated wall and the lower prefabricated wall and the bottom seam of the wall and then are inserted into the sleeve to form a grouting connection, characterized in that: Use X-ray machine and imaging plate to detect; The floor slab, the upper prefabricated wall and the lower prefabricated wall cooperate to form a cross area, the X-ray machine and the imaging plate are placed in the cross area and arranged diagonally in staggered layers, the imaging plate is arranged on the surface of the upper prefabricated wall at a side that is closer to the measured sleeve at a vertical distance; the X-ray emission window of the X-ray machine is arranged obliquely upward and toward the bottom of the sleeve, the X-ray machine is close to the node between the lower prefabricated wall and the floor slab, the imaging plate is arranged obliquely downward and toward the bottom of the sleeve, and the imaging plate is close to the node between the upper prefabricated wall and the floor slab; Start the X-ray machine to take pictures, and obtain an image of the assembly end connecting steel bar passing through the inside of the joint of the floor slab and the bottom of the wall and inserted into the sleeve, and identify from the image whether the assembly end connecting steel bar is cut off below the sleeve; Among them, the main axis direction of the X-ray machine is determined as follows: a cross-sectional view of the prefabricated wall and the floor is made through the center axis of the sleeve, the intersection of the center axis of the sleeve and the upper surface of the floor in the cross-sectional view is defined as the shooting center point, the intersection of the lower prefabricated wall and the lower surface of the floor in the X-ray machine layout area in the cross-sectional view is defined as the ray incident point, and the line between the shooting center point and the ray incident point is the main axis direction of the ray; the imaging plate is kept perpendicular to the main axis of the ray.

2. The non-destructive detection method for determining whether the connecting steel bars at the sleeve assembly end in the prefabricated wall are cut off as claimed in claim 1, characterized in that: The X-ray machine is arranged according to the following steps: Determine the angle between the ray emission window and the horizontal plane. The thickness of the prefabricated wall is b, the distance from the central axis of the sleeve to the near end surface of the upper prefabricated wall is a, the thickness of the floor is c, and the angle between the ray emission window and the horizontal plane is ; Determine the setting position of the center of the ray emission window. The control distance f between the center of the ray emission window and the ray incident point is set between 300㎜ and 500㎜. The vertical distance between the center of the ray emission window and the surface of the lower prefabricated wall is , the vertical distance between the center of the ray emission window and the lower surface of the floor ; Install the X-ray machine on the X-ray machine lifting frame, use an angle ruler to adjust the angle between the X-ray emission window and the horizontal plane to α, adjust the vertical distance between the center of the X-ray emission window and the surface of the lower prefabricated wall to d, raise the height of the X-ray machine lifting frame, and adjust the vertical distance between the center of the X-ray emission window and the lower surface of the floor to e.

3. The non-destructive detection method for determining whether the connecting steel bars at the sleeve assembly end in the prefabricated wall are cut off as claimed in claim 1, characterized in that: The imaging plates are arranged as follows: Determine the angle between the imaging plate and the vertical plane, which is equal to α; Determine the placement positions of the upper and lower ends of the imaging board. The lower end of the imaging board is supported on the upper surface of the floor slab, and the upper end of the imaging board is supported on the surface of the upper prefabricated wall. The height of the imaging board is h; The vertical distance between the support point at the bottom of the imaging plate and the surface of the upper prefabricated wall , the vertical distance between the support point at the top of the imaging plate and the upper surface of the floor ; The imaging plate is arranged obliquely according to the positions of the fulcrum at the lower end and the fulcrum at the upper end of the imaging plate.

4. The nondestructive detection method for determining whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off as claimed in claim 1, characterized in that: The tube voltage of the X-ray machine during shooting is greater than 300kv and the exposure time is not less than 0.3min.

5. The non-destructive detection method for determining whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off as claimed in claim 1, characterized in that: The effective imaging area of ​​the imaging plate shall not be less than 300 mm × 400 mm.

6. The non-destructive detection method for determining whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off as claimed in claim 1, characterized in that: The following features are used to determine whether the connecting steel bars at the assembly end are cut off below the sleeve: The steel bar connected to the assembly end is presented as a single bar in the image, and the steel bar is inserted into the bottom of the sleeve in a straight line, which is judged to be uncut; The steel bar connected to the assembly end is shown as a single bar in the image, and the steel bar is bent and deformed before being inserted into the bottom of the sleeve. It is judged that it is not cut off, but it shows that there is a misalignment between the steel bar connected to the assembly end and the sleeve, and the steel bar is bent before being inserted into the sleeve; The assembly end connecting steel bars are presented as double roots in the image. The assembly end connecting steel bars form upper steel bars and lower steel bars. The overlapping length of the upper steel bars and the lower steel bars in the junction area is short, which is judged to be truncated. The upper steel bars and the lower steel bars are connected at the joint at the bottom of the wall and then inserted into the sleeve. The assembly-end connecting steel bars appear as double roots as a whole in the imaging diagram. The assembly-end connecting steel bars form an upper section of steel bars and a lower section of steel bars. The overlapping length of the upper section of steel bars and the lower section of steel bars in the junction area is relatively long, and it is judged to be truncated. The upper section of steel bars is inserted into the sleeve after being implanted to a certain depth in the floor slab.

7. The non-destructive detection method for determining whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off as claimed in claim 2, characterized in that: The control distance f between the center of the ray emission window and the ray incident point is set to 400 mm.

8. The non-destructive detection method for determining whether the connecting steel bars at the sleeve assembly end in a prefabricated wall are cut off as claimed in claim 2, characterized in that: When determining the layout of the X-ray machine at the construction site, first use a steel bar scanner and combine it with the design drawings to determine the horizontal position of the sleeve center axis at the bottom of the upper prefabricated wall, and then determine the sleeve projection of the sleeve center axis on the surface of the upper prefabricated wall farther away from the sleeve. The intersection of the extension line of the sleeve projection and the lower surface of the floor slab is the ray incident point, and the projection point of the ray emission window center on the surface of the lower prefabricated wall is located on the extension line of the sleeve projection.

Images