Drawing device tool and underwater new and old concrete bonding performance testing method

Abstract

The invention relates to the technical field of concrete performance testing, in particular to a drawing device tool and an underwater new and old concrete bonding performance testing method. Comprising the following steps: S1, obtaining a core sample which comprises a tensile sample and a splitting sample; the tensile sample and the splitting sample are obtained from a new and old concrete combination; s2, performing a direct pull-out test on the tensile sample by using a pull-out tool, and recording a test result; s3, carrying out splitting bonding strength test on the splitting samples by using a splitting bonding strength method to obtain a test value of each splitting sample; s4, obtaining a tensile test value and a bonding strength test value; adding the tensile test value and the bonding strength test value to obtain a quality evaluation value, setting a quality evaluation grade, and comparing the quality evaluation value with the quality evaluation grade to obtain a quality evaluation grade of the new and old concrete combination; the device is used for testing the bonding performance of underwater new and old concrete after combination, and the overall stability and durability of the new and old concrete after combination are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of concrete performance testing, and in particular to a pulling device tooling and an underwater new-old concrete bonding performance testing method. Background Art

[0002] Concrete is a general term for engineering composite materials that are cemented into a whole by cementitious materials. Usually, concrete refers to cement as cementitious material, sand and stone as aggregates, water, admixtures and admixtures in a certain proportion, and the cement concrete obtained by mixing is widely used in water conservancy and civil engineering. Under various loads and corrosive environments, concrete structures have experienced quite serious aging, diseases and accidents, which have reduced the safety and durability of the structure and seriously affected the normal use of the building.

[0003] At present, the most commonly used and simple effective solution to the aging and disease phenomena of concrete structures is the reinforcement and repair method. The reinforcement and repair method adopts the method of increasing the cross-section, that is, firstly carry out certain treatment on the surface of the diseased concrete, such as applying interface adhesive, and then pouring new concrete on it, so that the new and old concrete are bonded into a whole to jointly bear the force of the original structure, that is, the new and old concrete combining process, through surface treatment, use of interface agent, mixing and pouring of new concrete, maintenance and other measures to combine the new concrete with the old concrete, so that the new and old concrete become a whole and work together.

[0004] The bonding performance test needs to be carried out for the whole after the new and old concrete are combined to ensure the overall bonding quality and strength after the new and old concrete are combined. However, the current bonding performance test method in non-water areas is not suitable for the bonding performance test of the new and old concrete combination underwater.

[0005] Therefore, there is an urgent need to provide a pulling device tooling and an underwater new and old concrete bonding performance testing method, which, compared with the existing technology, can test the bonding performance of the new and old concrete after being combined underwater to ensure the overall stability and durability after the new and old concrete are combined. Summary of the invention

[0006] The invention solves the technical problems existing in the prior art and provides a pulling device tooling and an underwater new and old concrete bonding performance testing method.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows: An underwater new and old concrete bonding performance testing method comprises the following steps: S1. Obtain core samples, which include tensile specimens and splitting specimens; prepare a combination of new and old concrete, where both tensile specimens and splitting specimens are obtained from the combination of new and old concrete; S2. Use the drawing tool to perform a direct drawing test on the tensile specimen and record the test results; S3. Using the splitting bond strength method, the splitting bond strength test is performed on the splitting specimens to obtain a test value of each splitting specimen; S4. Obtain the tensile test value according to the test results obtained in step S2; calculate the bonding strength test value according to all the test values ​​obtained in step S3; add the tensile test value and the bonding strength test value to obtain the quality evaluation value, set the quality evaluation grade, the quality evaluation grade includes good, qualified and unqualified, compare the quality evaluation value with the quality evaluation grade, and obtain the quality evaluation grade of the new and old concrete combination.

[0008] Furthermore, S2 specifically includes the following steps: S21, installing the pulling tool on the combination of new and old concrete; S22, placing the tensile specimen between the drawing fixture and the combination of new and old concrete; S23, driving the drawing tool to generate a tensile force on the tensile specimen, setting a set tensile force value, and controlling the drawing tool to gradually increase the tensile force on the tensile specimen to the set tensile force value; S24, recording whether the tensile specimen breaks when the tensile force of the drawing tool reaches the set tensile force value and the fracture position when the fracture occurs, and setting the tensile force value, whether the fracture occurs, and the fracture position as the test result; S25. When the tensile specimen has not broken when the tensile force of the drawing fixture reaches the set tensile force value, increase the tensile force of the drawing fixture to the breaking tensile force value, record the tensile force value of the drawing fixture when the tensile specimen breaks, and the fracture position of the tensile specimen, so that the tensile force value and fracture position of the drawing fixture when the tensile specimen breaks are the test results.

[0009] Furthermore, the set tensile force value and the breaking tensile force value are calculated by the following formulas: ; ; In the above formula, To set the tension value, is the pressure of the jack to reach the set pulling force value, r is the radius of the cylinder of the hydraulic jack, is the breaking tensile force value; It is the maximum pressing pressure of the jack.

[0010] Furthermore, S4 specifically includes the following steps: S41, scoring each tensile specimen, setting the evaluation grade of the tensile specimen, the evaluation grades of the tensile specimen include excellent, qualified and unqualified, setting the excellent grade to 90 points, the qualified grade to 75 points, and the unqualified grade to 60 points; sorting the scores of all tensile specimens from small to large, removing the maximum score and the minimum score, averaging the remaining scores, and obtaining the tensile test value; S42, sorting the test values ​​obtained in step S3 from small to large, removing the largest test value and the smallest test value, and averaging the remaining test values ​​to obtain a bonding strength test value; S43. Add the tensile test value and the bond strength test value to obtain a quality evaluation value, compare the quality evaluation value with the quality evaluation grade, and obtain the quality evaluation grade of the new-old concrete combination.

[0011] Furthermore, in step S43, when the quality evaluation value is greater than or equal to 170, it is evaluated as good, when the quality evaluation value is greater than or equal to 150 and less than 170, it is evaluated as qualified, and when the quality evaluation value is less than 150, it is evaluated as unqualified.

[0012] Furthermore, in step S41, when any of the following conditions is met, the tensile specimen is evaluated as excellent: (1) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the old concrete grade, and the fracture position is located in the old concrete slab; (2) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the new concrete grade, and the fracture position is located in the new concrete slab; (3) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface; The maximum tensile force applied to the tensile test specimen by the drawing fixture is the set tensile force value or greater than the set tensile force value.

[0013] Furthermore, in step S41, the condition for the tensile specimen to be evaluated as qualified is that the maximum tensile force applied to the tensile specimen by the pulling fixture is greater than or equal to 90% of the tensile strength of the old concrete grade and less than the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface; the condition for the tensile specimen to be evaluated as unqualified is that the maximum tensile force applied to the tensile specimen by the pulling fixture is less than 90% of the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface.

[0014] Furthermore, S1 specifically includes the following steps: S11, preparing a sample, firstly placing an old concrete slab into the bottom of a water tank or a pool, and then pouring a new concrete slab on the old concrete slab, thereby obtaining a combination of new and old concrete; S12, maintain the combination of new and old concrete; S13, using concrete coring equipment to cut multiple core sample rings on the new and old concrete combination after curing and strengthening in step S12 as tensile specimens, so that each tensile specimen includes a 3 cm thick old concrete slab; S14. A cutting and dividing method is used to prepare a plurality of splitting specimens on the combination of new and old concrete after equal strength curing in step S12. The number of splitting specimens is the same as the number of tensile specimens, so that the contact surface between the new concrete slab and the old concrete slab in each splitting specimen is located in the middle.

[0015] A pulling device tool, comprising a pulling tool, wherein the pulling tool is used in an underwater new-old concrete bonding performance test method described in any one of claims 1-8; the pulling tool comprises a hydraulic pump, a hydraulic jack, a beam, an anchor rod, a bolt, a gasket, a pad and a steel plate, the hydraulic jacks are respectively provided at both ends of the lower wall of the beam, the lower ends of the hydraulic jacks are fixedly connected to one of the steel plates, the anchor rod is arranged through the beam, the upper end of the anchor rod extending out of the beam is threadedly connected to the bolt, the part of the anchor rod extending out of the upper end of the beam is penetrated by the pad, the pad is in contact with the upper wall of the beam, the pad is located below the bolt, and the gasket is arranged between the pad and the bolt; the two hydraulic jacks are pressurized by one hydraulic pump.

[0016] Furthermore, the actual tonnage of the hydraulic jack is calculated by the following formula: ; ; ; In the above formula, represents the axial tensile strength of the concrete cube, Indicates the standard value of concrete cube compressive strength, represents the standard deviation of concrete strength, represents the brittleness reduction factor; Indicates the ideal tonnage of the hydraulic jack, Indicates the cylinder radius of the hydraulic jack, Indicates the actual tonnage of the hydraulic jack. represents the safety factor, Take 4-8.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention has a simple structure and strong practicability. It can be used not only for testing the bonding performance of new and old concrete in non-water areas, but also for testing the bonding performance of new and old concrete underwater. The present invention uses the whole process and all elements to simulate the concrete mix ratio, casting process, and maintenance method, extract and make samples, and compare the obtained direct pull-out test data with the data of the splitting bonding test of the same large plate sample, and the conclusion is scientific and reasonable. It avoids underwater operations and conducts bonding test operations in a non-water environment, which is safe and controllable; it tests the bonding performance of new and old concrete after bonding underwater, ensuring the overall stability and durability of the new and old concrete after bonding. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the drawing device tooling of the present invention.

[0019] Description of reference numerals: 1. Old concrete slab; 2. New concrete slab; 3. Pull-out tooling; 31. Crossbeam; 32. Anchor rod; 33. Bolt; 34. Gasket; 35. Pad; 36. Hydraulic jack; 37. Steel plate; 38. Hydraulic pump; 4. Tensile specimen. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. It should be noted that the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0021] The present invention provides an underwater new-old concrete bonding performance testing method, comprising the following steps: S1. Obtaining core samples, which include tensile specimens and splitting specimens; specifically comprising the following steps: S11. Prepare a sample. First, prepare an old concrete slab. Then put the prepared old concrete slab into the bottom of a water tank or a pool. Then, cast a new concrete slab underwater on the old concrete slab to obtain a combination of new and old concrete, i.e., the sample.

[0022] The specific method for preparing the old concrete slab is as follows: the old concrete slab is prepared according to the spatial structure of the door slot and the roughness of the bonding surface. The door slot is a hexahedral structure, of which four sides are the bonding surfaces of the new and old concrete; the old concrete slab is formed strictly in accordance with the original door slot concrete process and technical indicators. The old concrete around the door slot is installed with wooden formwork, the secondary concrete is poured, and the soft shaft vibrator is vibrated and compacted to form the old concrete slab; after the concrete is poured, it is covered with sacks and watered for 28 days under natural conditions. The formwork is removed 2 days after the concrete is formed, and the joint surface of the new and old concrete is treated by artificial chiseling to ensure that the surface slurry and loose layer are completely removed. The chiseling standards for joint surface treatment include chiseling rate and chiseling depth. The chiseling rate of the concrete surface should not be less than 90%, the chiseling depth should be between 6 and 8 mm, and 1 / 3 of the coarse aggregate is exposed on the surface.

[0023] The specific method of underwater pouring of new concrete slabs is: install aluminum alloy composite formwork in a water tank or pool, and pour new concrete underwater into the door slots and holes set in the old concrete slabs through the conduit method to form new concrete slabs. The mix ratio of the new concrete slabs is a special plant nanocellulose hydraulic fine stone concrete mix ratio, and the aluminum alloy composite formwork is removed after 2 days.

[0024] S12. Cure the prepared samples in water. The water temperature is determined according to the water temperature around the reservoir slot. The concrete curing period is appropriately extended or shortened according to the on-site slot water temperature and the standard curing temperature. When the on-site slot water temperature is lower than the standard curing temperature, the curing period is extended by 2℃ / 1d. When the on-site slot water temperature is higher than the standard curing temperature, the standard curing period is used, i.e. 28d.

[0025] S13. Obtain tensile specimens, and use concrete coring equipment to cut multiple core sample rings on the specimen cured in step S12 as tensile specimens. Six tensile specimens are preferred, and each tensile specimen includes a 3-cm thick old concrete slab. The end face flatness deviation of the tensile specimen is not greater than 0.1% of its diameter, and the verticality deviation of the tensile specimen with the central axis is not greater than 1°. The flatness deviation of the upper end of the tensile specimen and the flatness deviation are measured and calculated in accordance with the provisions of the "Concrete Test Mold Calibration Method".

[0026] S14, obtaining splitting specimens, using the cutting and dividing method to prepare multiple splitting specimens on the specimen cured in step S12, the number of splitting specimens is set the same as the number of tensile specimens, the number of splitting specimens is also preferably 6, and the specification of each splitting specimen is 150mm 150mm 150mm, and the contact surface between the new concrete slab and the old concrete slab is located in the middle of the splitting specimen.

[0027] The concrete coring equipment is an existing equipment, and the specific structure will not be described in detail here; the cutting and dividing method is an existing method, and the specific content will not be described in detail here.

[0028] S2. Use the bonding pull-out method to conduct a direct pull-out test on the tensile specimen. The specific method is as follows: S21. Bond the lower end of the steel plate of the pulling tool to the upper surface of the new concrete slab using a high-efficiency adhesive, and bond the lower wall of the steel plate of the pulling tool to the old concrete slab at the same time.

[0029] S22. Bond the tensile specimen between the upper surface of the new concrete slab and the anchor rod of the pulling fixture.

[0030] S23, driving the drawing tool to generate tension on the tensile specimen through the drawing tool, and controlling the tension applied by the drawing tool to gradually increase to a set tension value.

[0031] The set tension value is calculated by the following formula: ; In the above formula, To set the tensile strength value, it is usually set to the pull-out strength of the old concrete grade. is the pressing pressure of the jack to reach the set pulling force value, and r is the cylinder radius of the hydraulic jack.

[0032] S24. During the stretching process of the tensile specimen, record whether the tensile specimen breaks when the tensile force of the drawing tool reaches the set tensile force value and the fracture position when the fracture occurs.

[0033] S25. When the tensile specimen has not broken when the tensile force of the drawing fixture reaches the set tensile force, increase the tensile force of the drawing fixture to the breaking tensile force, and record the tensile force of the drawing fixture when the tensile specimen breaks, as well as the position where the tensile specimen breaks; the breaking tensile force is calculated by the following formula: ; In the above formula, is the breaking tensile force value; It is the maximum pressing pressure of the jack.

[0034] S3. Use the splitting bond strength method to test the splitting bond strength of 6 splitting specimens and obtain 6 test values.

[0035] S4, based on the direct pull-out test in step S2 and the splitting bond strength test in step S3, the quality of the new and old concrete combination is evaluated, specifically including the following steps: S41. Score each tensile specimen and set an evaluation grade for the tensile specimen. The evaluation grades for the tensile specimen include excellent, qualified, and unqualified. The excellent grade is set to 90 points, the qualified grade is set to 75 points, and the unqualified grade is set to 60 points. Sort the scores of the six tensile specimens from small to large, remove the maximum score and the minimum score after sorting, and average the remaining four scores to obtain the tensile test value.

[0036] The tensile specimen is evaluated as good when any of the following conditions are met: (1) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the old concrete grade, and the fracture position is located in the old concrete slab.

[0037] (2) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the new concrete grade, and the fracture position is located in the new concrete slab.

[0038] (3) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface.

[0039] The conditions for the tensile specimen to be evaluated as qualified are: the maximum tensile force applied to the tensile specimen by the pulling fixture is greater than or equal to 90% of the tensile strength of the old concrete grade and less than the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface.

[0040] The conditions for evaluating the tensile specimen as unqualified are: the maximum tensile force applied to the tensile specimen by the pulling fixture is less than 90% of the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface.

[0041] The maximum tensile force applied to the tensile test specimen by the drawing fixture is the set tensile force value or greater than the set tensile force value.

[0042] S42. Sort the six test values ​​obtained in step S3 from small to large, remove the largest test value and the smallest test value, and average the remaining four test values ​​to obtain a bonding strength test value.

[0043] S43. Combine the tensile test value and the bond strength test value to obtain a quality evaluation value, and set a quality evaluation grade. The quality evaluation grades include good, qualified and unqualified. When the quality evaluation value is greater than or equal to 170, it is evaluated as good, when the quality evaluation value is greater than or equal to 150 and less than 170, it is evaluated as qualified, and when the quality evaluation value is less than 150, it is evaluated as unqualified. Therefore, according to the quality evaluation value, the quality evaluation grade of the new and old concrete combination is obtained.

[0044] The quality evaluation value is calculated by the following formula: ; In the above formula, represents the quality evaluation value, Indicates the tensile test value, Indicates the bond strength test value.

[0045] like Figure 1 As shown, the present invention further provides a drawing device tool, including a drawing tool 3, the drawing tool 3 includes a hydraulic pump 38, a hydraulic jack 36, a crossbeam 31, an anchor rod 32, a bolt 33, a gasket 34, a pad 35 and a steel plate 37, two hydraulic jacks 36 are arranged on the lower wall of the crossbeam 31, the crossbeam 31 is a frame structure, the hydraulic jacks 36 are located at both ends of the lower wall of the crossbeam 31, the hydraulic jacks 36 are fixedly connected to the crossbeam 31, and the lower ends of the hydraulic jacks 36 are fixedly connected to a steel plate 37. The anchor rod 32 is set through the cross beam 31, and the upper end of the anchor rod 32 extends out of the cross beam 31 and is threadedly connected to the bolt 33. The part of the anchor rod 32 extending out of the upper end of the cross beam 31 is penetrated by a pad 35, and the pad 35 contacts the upper wall of the cross beam 31. The pad 35 is located below the bolt 33. A gasket 34 is provided between the pad 35 and the bolt 33, and the gasket 34 is sleeved on the outside of the anchor rod 32; two hydraulic jacks 36 are pressurized by a hydraulic pump 38, and the hydraulic pump 38 is connected to the two hydraulic jacks 36 at the same time through a Y-tube.

[0046] The actual tonnage of the hydraulic jack 36 is calculated by the following formula: ; ; ; In the above formula, represents the axial tensile strength of the concrete cube, Indicates the standard value of concrete cube compressive strength, represents the standard deviation of concrete strength, represents the brittleness reduction factor; Indicates the ideal tonnage of hydraulic jack 36, Indicates the actual tonnage of the hydraulic jack 36, represents the safety factor, Take 4-8.

[0047] Take the value from Table 1: Table 1

[0048] When the tensile specimen 4 is pulled, the lower wall of the tensile specimen 4 is bonded to the upper wall of the new concrete slab 2, the upper wall of the tensile specimen 4 is bonded to the lower end surface of the anchor rod 32, and the lower surface of the steel plate 37 is bonded to the upper surface of the new concrete slab 2 and the upper surface of the old concrete slab 1.

[0049] The present invention has a simple structure and strong practicability. It can be used not only for testing the bonding performance of new and old concrete in non-water areas, but also for testing the bonding performance of new and old concrete underwater. The present invention uses the whole process and all elements to simulate the concrete mix ratio, casting process, and maintenance method, extracts and makes samples, and compares the obtained direct pull-out test data with the data of the splitting bonding test of the same large plate sample, and the conclusion is scientific and reasonable. It avoids underwater operations and conducts bonding test operations in a non-water environment, which is safe and controllable; it tests the bonding performance of new and old concrete after bonding underwater, ensuring the overall stability and durability of the new and old concrete after bonding.

[0050] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for testing the bonding performance of new and old concrete underwater, characterized in that: The following steps are involved: S1. Obtain core samples, which include tensile specimens and splitting specimens; prepare a combination of new and old concrete, where both tensile specimens and splitting specimens are obtained from the combination of new and old concrete; S2. Use the drawing tool to perform a direct drawing test on the tensile specimen and record the test results; S3. Using the splitting bond strength method, the splitting bond strength test is performed on the splitting specimens to obtain a test value of each splitting specimen; S4, obtaining a tensile test value according to the test result obtained in step S2; According to all the test values ​​obtained in step S3, the bonding strength test value is calculated; the tensile test value and the bonding strength test value are added to obtain the quality evaluation value, and the quality evaluation grade is set. The quality evaluation grade includes good, qualified and unqualified. The quality evaluation value is compared with the quality evaluation grade to obtain the quality evaluation grade of the new and old concrete combination.

2. The underwater new-old concrete bonding performance testing method according to claim 1 is characterized in that: S2 specifically includes the following steps: S21, installing the pulling tool on the combination of new and old concrete; S22, placing the tensile specimen between the drawing fixture and the combination of new and old concrete; S23, driving the drawing tool to generate a tensile force on the tensile specimen, setting a set tensile force value, and controlling the drawing tool to gradually increase the tensile force on the tensile specimen to the set tensile force value; S24, recording whether the tensile specimen breaks when the tensile force of the drawing tool reaches the set tensile force value and the fracture position when the fracture occurs, and setting the tensile force value, whether the fracture occurs, and the fracture position as the test result; S25. When the tensile specimen has not broken when the tensile force of the drawing fixture reaches the set tensile force value, increase the tensile force of the drawing fixture to the breaking tensile force value, record the tensile force value of the drawing fixture when the tensile specimen breaks, and the fracture position of the tensile specimen, so that the tensile force value and fracture position of the drawing fixture when the tensile specimen breaks are the test results.

3. The underwater new-old concrete bonding performance testing method according to claim 2 is characterized in that: The set tensile force value and breaking tensile force value are calculated by the following formulas: ； ； In the above formula, To set the tension value, is the pressure of the jack to reach the set pulling force value, r is the radius of the cylinder of the hydraulic jack, is the breaking tensile force value; It is the maximum pressing pressure of the jack.

4. The underwater new-old concrete bonding performance testing method according to claim 2 is characterized in that: S4 specifically includes the following steps: S41, scoring each tensile specimen, setting the evaluation grade of the tensile specimen, the evaluation grades of the tensile specimen include excellent, qualified and unqualified, setting the excellent grade to 90 points, the qualified grade to 75 points, and the unqualified grade to 60 points; sorting the scores of all tensile specimens from small to large, removing the maximum score and the minimum score, averaging the remaining scores, and obtaining the tensile test value; S42, sorting the test values ​​obtained in step S3 from small to large, removing the largest test value and the smallest test value, and averaging the remaining test values ​​to obtain a bonding strength test value; S43. Add the tensile test value and the bond strength test value to obtain a quality evaluation value, compare the quality evaluation value with the quality evaluation grade, and obtain the quality evaluation grade of the new-old concrete combination.

5. The underwater new-old concrete bonding performance testing method according to claim 4 is characterized in that: In step S43, when the quality evaluation value is greater than or equal to 170, it is evaluated as good, when the quality evaluation value is greater than or equal to 150 and less than 170, it is evaluated as qualified, and when the quality evaluation value is less than 150, it is evaluated as unqualified.

6. The underwater new-old concrete bonding performance testing method according to claim 4 is characterized in that: In step S41, the tensile specimen is evaluated as excellent when any of the following conditions are met: (1) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the old concrete grade, and the fracture position is located in the old concrete slab; (2) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the new concrete grade, and the fracture position is located in the new concrete slab; (3) When the maximum tensile force of the tensile test specimen is greater than the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface; The maximum tensile force applied to the tensile test specimen by the drawing fixture is the set tensile force value or greater than the set tensile force value.

7. The underwater new-old concrete bonding performance testing method according to claim 4 is characterized in that: In step S41, the conditions for evaluating the tensile specimen as qualified are: the maximum tensile force applied to the tensile specimen by the pulling fixture is greater than or equal to 90% of the tensile strength of the old concrete grade and less than the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface; the conditions for evaluating the tensile specimen as unqualified are: the maximum tensile force applied to the tensile specimen by the pulling fixture is less than 90% of the tensile strength of the old concrete grade, and the fracture position is located on the bonding surface.

8. The underwater new-old concrete bonding performance testing method according to claim 4 is characterized in that: S1 specifically includes the following steps: S11, preparing a sample, firstly placing an old concrete slab into the bottom of a water tank or a pool, and then pouring a new concrete slab on the old concrete slab, thereby obtaining a combination of new and old concrete; S12, maintain the combination of new and old concrete; S13, using concrete coring equipment to cut multiple core sample rings on the new and old concrete combination after curing and strengthening in step S12 as tensile specimens, so that each tensile specimen includes a 3 cm thick old concrete slab; S14. A cutting and dividing method is used to prepare a plurality of splitting specimens on the combination of new and old concrete after equal strength curing in step S12. The number of splitting specimens is the same as the number of tensile specimens, so that the contact surface between the new concrete slab and the old concrete slab in each splitting specimen is located in the middle.

9. A drawing device tool, characterized in that: It comprises a pulling tool, and the pulling tool is used in an underwater new-old concrete bonding performance test method according to any one of claims 1 to 8; the pulling tool comprises a hydraulic pump, a hydraulic jack, a beam, an anchor rod, a bolt, a gasket, a pad and a steel plate, and the hydraulic jacks are respectively arranged at both ends of the lower wall of the beam, and the lower ends of the hydraulic jacks are fixedly connected to one of the steel plates, the anchor rod is arranged through the beam, and the upper end of the anchor rod extending out of the beam is threadedly connected to the bolt, and the part of the anchor rod extending out of the upper end of the beam is penetrated by the pad, and the pad is in contact with the upper wall of the beam, and the pad is located below the bolt, and the gasket is arranged between the pad and the bolt; the two hydraulic jacks are pressurized by one hydraulic pump.

10. A drawing device tool according to claim 9, characterized in that: The actual tonnage of the hydraulic jack is calculated by the following formula: ； ； ； In the above formula, represents the axial tensile strength of the concrete cube, Indicates the standard value of concrete cube compressive strength, represents the standard deviation of concrete strength, represents the brittleness reduction factor; Indicates the ideal tonnage of the hydraulic jack, Indicates the cylinder radius of the hydraulic jack, Indicates the actual tonnage of the hydraulic jack. represents the safety factor, Take 4-8.

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