Built-in three-dimensional cohesive slip testing device and installation testing method thereof

Abstract

The application discloses a built-in three-dimensional bond-slip testing device and a mounting testing method thereof, which is used for testing the bond-slip and vertical peeling at the interface of a steel plate-concrete composite structure, is mounted on the inner side of the steel plate before pouring the concrete, and comprises a steel shell and a core testing element located in the steel shell, wherein the steel shell is sealed with the bottom of the steel plate; the core testing element comprises a hollow conduit, a sliding head, a pre-tightening spring and six string strain gauges; two of the six string strain gauges are arranged along three directions of X, Y and Z respectively, and are used for testing the slip amount along the X and Y directions and the peeling amount along the Z direction between the steel plate and the concrete. The application is based on a novel internal structure, breaks through the defects of single testing direction and low dimension of the existing bond-slip testing, can realize the repetitive and intermittent non-continuous testing of the interface slip damage, and significantly improves the feasibility of long-term monitoring of the interface damage of the composite structure.

Description

Technical Field

[0001] This invention relates to the field of interface damage monitoring technology for steel plate-concrete composite structures, and particularly to a built-in three-dimensional bond-slip testing device and its installation and testing method. Background Technology

[0002] Currently, composite structures are widely used as the main load-bearing components of large-scale infrastructure. Effective bonding between steel and concrete fully utilizes the mechanical properties of both materials, serving as the foundation and prerequisite for ensuring the load-bearing performance of the composite structure. This has led to their widespread application as primary load-bearing components in large bridges and super high-rise buildings. Steel has high tensile strength but is prone to buckling under compression; concrete has good compressive strength but is prone to cracking under tension. Due to the differences in the mechanical parameters of the two materials, shear cracking easily occurs at the steel-concrete interface, and buckling of the steel plate in the compression zone can easily lead to separation between the steel plate and concrete. When interfacial slip or delamination damage occurs, the cooperative load-bearing mechanism between the steel plate and concrete is disrupted, significantly reducing the load-bearing capacity of the component. Furthermore, cracks between the steel plate and concrete are prone to corrosion caused by rainwater, further reducing the durability of the composite structure.

[0003] Many scholars have conducted damage tests based on methods for different types of interface defects, such as impact testing and ultrasonic testing. However, current methods for testing interface delamination face technical challenges, including low accuracy, inaccuracy, or even complete inability to measure these defects. Common testing methods primarily rely on direct testing based on relative displacement and strain differences. This involves using LVDT displacement sensors to measure the relative displacement between the steel plate and the concrete portion, or placing strain gauges in both the steel plate and concrete and calculating the differences between them. However, these methods are ineffective for conducting effective bond-slip tests.

[0004] Patent CN2551971Y provides a built-in electronic bond slip sensor for steel-concrete interface, patent CN207215011U provides a sensor for measuring bond slip at the interface between steel plate and concrete, and patent CN110208182 provides a measuring sensor for measuring bond slip at the interface between steel and concrete. However, the above patents can only perform unidirectional tests and cannot achieve three-dimensional bond slip testing. Regarding vertical peeling monitoring, there are currently no relevant literature reports. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a built-in three-dimensional bond slip testing device and its installation and testing method. Through built-in sensing elements in the X, Y, and Z directions, it enables slip testing on the horizontal plane in the X and Y directions and peeling testing in the Z direction of the interface, thus overcoming the application limitations of built-in sensors and improving the dimensionality and accuracy of steel plate-concrete interface damage testing.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide the following solutions:

[0007] On the one hand, a built-in three-dimensional bond-slip testing device is provided. The device is used to test bond-slip and vertical peeling at the interface of a steel plate-concrete composite structure. It is installed inside the steel plate before concrete pouring and includes a steel shell and a core testing element located in the steel shell. The steel shell is sealed to the bottom of the steel plate.

[0008] The core testing components include a hollow guide tube, a sliding head, a preload spring, and a six-string strain gauge. The hollow guide tube is vertically positioned in the middle of the steel shell, with its upper end passing through a positioning hole at the top of the steel plate and its lower end able to slide freely on the bottom contact surface of the steel shell. The sliding head is fitted onto the outside of the hollow guide tube and can slide up and down along it. The preload spring is located below the sliding head, with its upper end connected to the sliding head and its lower end contacting the bottom of the steel shell. The preload spring provides a preload force to make the sliding head contact the top of the steel plate.

[0009] The six string strain gauges are arranged in two along each of the X, Y, and Z directions, respectively, to test the amount of slippage between the steel plate and the concrete in the X and Y directions and the amount of peeling in the Z direction. One end of each string strain gauge is hinged to the sliding head, and the other end is hinged to the inner wall of the steel shell.

[0010] Preferably, the device is positioned and installed using positioning bolts, which, from top to bottom, include a nut, a variable cross-section screw, and a bottom thread. The positioning bolts are inserted into the hollow conduit through the positioning hole at the top of the steel plate and tightened with the bolt hole at the bottom of the steel shell. After the concrete is poured and hardened, the positioning bolts are removed to release the constraint on the sliding head, allowing it to slide freely in the X and Y directions.

[0011] Preferably, the steel shell is a square shell with an open top, and the steel shell and the bottom of the steel plate are sealed with a sealing ring, which is formed by applying silicone rubber to prevent moisture from entering before the concrete hardens.

[0012] Preferably, multiple studs are arranged on the outer side and bottom of the steel shell to enhance the connection with the concrete, prevent the concrete shrinkage from causing separation from the steel shell, and ensure the integrity of the testing device and the concrete.

[0013] Preferably, the sliding head has a cylindrical through hole in the middle, and the diameter of the cylindrical through hole is the same as the outer wall diameter of the hollow conduit, so that the sliding head can slide without constraint in the Z direction and the two can maintain the same degree of freedom in the X and Y directions.

[0014] Preferably, the six string strain gauges are a first X-direction string strain gauge, a second X-direction string strain gauge, a first Y-direction string strain gauge, a second Y-direction string strain gauge, a first Z-direction string strain gauge, and a second Z-direction string strain gauge.

[0015] The first X-direction string strain gauge and the second X-direction string strain gauge are symmetrically arranged, and the average value of their measurement results is taken as the test result of the X-direction slip; the first Y-direction string strain gauge and the second Y-direction string strain gauge are symmetrically arranged, and the average value of their measurement results is taken as the test result of the Y-direction slip; the first Z-direction string strain gauge and the second Z-direction string strain gauge are symmetrically arranged, and the average value of their measurement results is taken as the test result of the Z-direction peeling. This avoids the phenomenon that if only one string strain gauge is set in a single direction, the failure of a single string strain gauge will lead to inaccurate test data.

[0016] Preferably, the first X-direction string strain gauge, the second X-direction string strain gauge, the first Y-direction string strain gauge, the second Y-direction string strain gauge, the first Z-direction string strain gauge, and the second Z-direction string strain gauge all include a first support and a second support; wherein, the first support is hinged to the sliding head, and the second support is hinged to the inner wall of the steel shell.

[0017] Preferably, the sliding head is provided with a wire groove, the hollow guide tube is provided with an inlet hole and an outlet hole, and the wire of the string strain gauge is led out of the device in sequence along the wire groove, the inlet hole and the outlet hole.

[0018] Preferably, the lead wires of the six string strain gauges are externally connected to a multi-channel strain acquisition box, which is connected to a computer terminal.

[0019] On the one hand, an installation and testing method based on the aforementioned built-in three-dimensional adhesive slip testing device is provided, comprising the following steps:

[0020] Processing and manufacturing steel shells;

[0021] Multiple studs are welded to the outer wall of the steel shell;

[0022] A preload spring is provided at the bottom of the steel shell;

[0023] A sliding head is installed above the preload spring;

[0024] A hollow guide tube is installed in the middle of the sliding head;

[0025] Six string strain gauges are installed, two each in the X, Y, and Z directions; the six string strain gauges are all hinged to the sliding head and the inner wall of the steel shell;

[0026] The wire of the string strain gauge is led out through the sliding head and the hollow conduit;

[0027] Insert the positioning bolt into the hollow conduit through the positioning hole at the top of the steel plate, and tighten it with the bolt hole at the bottom of the steel shell;

[0028] The periphery of the steel shell and the bottom of the steel plate are sealed with silicone rubber and left to stand for more than 24 hours.

[0029] Pour concrete and cure for 28 days;

[0030] Connect the wires of the string strain gauge to the multi-channel strain acquisition box, which is then connected to a computer terminal.

[0031] Remove the positioning bolts to restore the sliding head's degrees of freedom in the X, Y, and Z directions;

[0032] Load and perform calibration tests;

[0033] After completing the calibration tests in the X, Y, and Z directions, it is used for actual testing.

[0034] The beneficial effects of the technical solutions provided by the embodiments of the present invention include at least the following:

[0035] This invention, based on a novel internal structure, symmetrically arranges six miniature string strain gauges as sensing elements in the X, Y, and Z directions. This enables simultaneous testing of bond slip in the X and Y directions and vertical peeling in the Z direction at the steel-concrete interface, overcoming the limitations of existing bond slip testing methods that are limited to a single direction and have low dimensionality. This invention also solves the technical drawbacks of traditional strain gauge-based sensing methods, which require continuous real-time power and cannot perform intermittent testing. It enables repeatable and intermittent non-continuous testing of interface slip damage, significantly improving the feasibility of long-term monitoring of interface damage in composite structures. Furthermore, this device offers significant advantages such as convenient installation, high testing accuracy, and stable performance, and can be widely applied to testing under various conditions, including monotonic loading, cyclic loading, and static-dynamic impact loading, as well as for health monitoring of steel-concrete composite structures. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a 3D perspective view of the built-in three-dimensional bonding and slip testing device provided in this embodiment of the invention;

[0038] Figure 2 This is an isometric cross-sectional view of the built-in three-dimensional bonding and slip testing device provided in an embodiment of the present invention;

[0039] Figure 3 This is a longitudinal cross-sectional view of the built-in three-dimensional bonding and slip testing device provided in an embodiment of the present invention;

[0040] Figure 4 This is a cross-sectional view of the built-in three-dimensional bonding and slip testing device provided in an embodiment of the present invention;

[0041] Figure 5 This is a 3D side view of the built-in three-dimensional bonding and slip testing device provided in an embodiment of the present invention;

[0042] Figure 6 This is a top view of the assembled built-in three-dimensional bonding and slip testing device provided in this embodiment of the invention;

[0043] Figure 7 This is a side view of the assembled built-in three-dimensional bonding and slip testing device provided in this embodiment of the invention;

[0044] Figure 8 This is a schematic diagram of the positioning screw provided in an embodiment of the present invention;

[0045] Figure 9 This is a schematic diagram of the hollow conduit provided in an embodiment of the present invention;

[0046] Figure 10 This is a schematic diagram of the positioning bolt holes on the steel shell provided in an embodiment of the present invention;

[0047] Figure 11 This is a schematic diagram of the top positioning hole of the combined structure steel plate provided in an embodiment of the present invention;

[0048] Figure 12 This is a schematic diagram of the structure of the sealing ring provided in an embodiment of the present invention;

[0049] Figure 13 This is a schematic diagram of the sliding head and preload spring provided in an embodiment of the present invention;

[0050] Figure 14 This is a schematic diagram of the structure of the core testing element provided in the embodiment of the present invention;

[0051] Figure 15 This is a cross-sectional view of the core testing element provided in an embodiment of the present invention;

[0052] Figure 16 This is a schematic diagram of the internal structure of the string strain gauge provided in an embodiment of the present invention;

[0053] Figure 17This is a side view of the string strain gauge provided in an embodiment of the present invention;

[0054] Figure 18 This is a schematic diagram of the structure of the testing system provided in an embodiment of the present invention;

[0055] Figure 19 This is a schematic diagram of the installation and testing process of the built-in three-dimensional bonding and slip testing device provided in an embodiment of the present invention.

[0056] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to the specific structure, device and environment. According to specific needs, those skilled in the art can adjust or modify these devices and environments, and such adjustments or modifications are still included in the protection scope of the present invention. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] An embodiment of the present invention provides a built-in three-dimensional bond slip testing device. Figures 1-7 These are, respectively, the 3D perspective view, isometric side section view, longitudinal section view, transverse section view, 3D side view, top view after assembly, and side view after assembly of the built-in three-dimensional bonding and slip testing device.

[0059] The device is used to test bond slip and vertical peeling at the interface of a steel plate-concrete composite structure. It is installed inside the steel plate before concrete is poured and includes a steel shell 1 and a core test element 2 located in the steel shell 1. The steel shell 1 is sealed to the bottom of the steel plate.

[0060] The core test element 2 includes a hollow guide tube 21, a sliding head 22, a preload spring 23, and six-string strain gauges 24. The hollow guide tube 21 is vertically arranged in the middle of the steel shell 1, with its upper end passing through the positioning hole at the top of the steel plate and its lower end able to slide freely on the bottom contact surface of the steel shell 1. The sliding head 22 is sleeved on the outside of the hollow guide tube 21 and can slide up and down along the hollow guide tube 21. The preload spring 23 is located below the sliding head 22, with its upper end connected to the sliding head 22 and its lower end in contact with the bottom of the steel shell 1. The preload spring 23 provides a preload force to make the sliding head 22 contact the top of the steel plate.

[0061] Six string strain gauges 24 are set up in two along each of the X, Y and Z directions, respectively, to test the amount of slippage between the steel plate and the concrete in the X and Y directions and the amount of peeling in the Z direction. One end of each string strain gauge 24 is hinged to the sliding head 22, and the other end is hinged to the inner wall of the steel shell 1.

[0062] Furthermore, the positioning and installation process of the device is as follows: Figures 8-11 As shown. The device is positioned and installed using positioning bolts 3. Positioning bolts 3, from top to bottom, include a nut 31, a variable cross-section screw 32, and a bottom thread 33. Positioning bolts 3 are inserted into the hollow guide tube 21 through positioning holes 8 at the top of the steel plate and tightened with bolt holes 11 at the bottom of the steel shell 1. After the concrete is poured and hardened, the positioning bolts 3 are removed to release the constraint on the sliding head 22, allowing it to slide freely in the X and Y directions.

[0063] In one specific embodiment of the present invention, the steel shell 1 is a square shell with an open top, and the steel shell 1 and the bottom of the steel plate are sealed with a sealing ring 4, as shown below. Figure 12 As shown, the sealing ring 4 is formed by applying silicone rubber to prevent moisture from penetrating before the concrete hardens.

[0064] To enhance the reliable bond between the testing device and the concrete, multiple studs 5 are arranged on the outer side and bottom of the steel shell 1 to strengthen the connection with the concrete, prevent the concrete from shrinking and causing separation from the steel shell 1, eliminate the gap between the two, maintain the integrity between the two, ensure that the testing device is tightly connected to the concrete, and keep the sliding direction and amount of sliding highly consistent, thereby improving the accuracy of the test.

[0065] Furthermore, such as Figure 13 As shown, a cylindrical through hole is provided in the middle of the sliding head 22. The diameter of the cylindrical through hole is the same as the outer wall diameter of the hollow guide tube 21, so that the sliding head 22 can slide freely in the Z direction and the degrees of freedom of both in the X and Y directions are consistent. The hollow guide tube 21 can slide freely on the bottom contact surface of the steel shell 1, thereby realizing the test of sliding in the X and Y directions. At the same time, the hollow guide tube 21 and the sliding head 22 remain parallel in the Z direction. When vertical peeling occurs, the sliding head 22 can move vertically along the hollow guide tube 21 under the preload of the preload spring 23, thereby realizing the test of peeling in the Z direction.

[0066] Furthermore, such as Figure 14 and Figure 15 As shown, the six string strain gauges 24 are respectively the first X-direction string strain gauge, the second X-direction string strain gauge, the first Y-direction string strain gauge, the second Y-direction string strain gauge, the first Z-direction string strain gauge, and the second Z-direction string strain gauge.

[0067] The first X-direction string strain gauge and the second X-direction string strain gauge are symmetrically arranged, and the average value of their measurement results is taken as the test result of the X-direction slip; the first Y-direction string strain gauge and the second Y-direction string strain gauge are symmetrically arranged, and the average value of their measurement results is taken as the test result of the Y-direction slip; the first Z-direction string strain gauge and the second Z-direction string strain gauge are symmetrically arranged, and the average value of their measurement results is taken as the test result of the Z-direction peeling. This avoids the phenomenon that if only one string strain gauge is set in a single direction, the failure of a single string strain gauge will lead to inaccurate test data.

[0068] In this embodiment of the invention, the structures of the first X-direction string strain gauge, the second X-direction string strain gauge, the first Y-direction string strain gauge, the second Y-direction string strain gauge, the first Z-direction string strain gauge, and the second Z-direction string strain gauge are as follows: Figure 16 and Figure 17 As shown, each string strain gauge 24 includes a first support 241 and a second support 242. Both the first support 241 and the second support 242 are hinged supports. Specifically, the first support 241 is hinged to the sliding head 22, and the second support 242 is hinged to the inner wall of the steel shell 1, to measure the slippage in the X and Y directions and the peeling in the Z direction, respectively.

[0069] Preferably, each string strain gauge 24 is equipped with a temperature compensation sensor to eliminate the influence of temperature changes and improve detection sensitivity.

[0070] Further, refer to Figure 9 and Figure 13 The sliding head 22 is provided with a wire groove 221, and the hollow guide tube 21 is provided with an inlet hole 211 and an outlet hole 212. The wire 243 of the string strain gauge 24 is led out of the device along the wire groove 221, the inlet hole 211 and the outlet hole 212 in sequence.

[0071] like Figure 18 As shown, the wires 243 of the six string strain gauges 24 are led out of the device and connected to the multi-channel strain acquisition box 6, which is then connected to the computer terminal 7. The computer terminal 7 analyzes the acquired strain data, thereby realizing the three-dimensional bond-slip damage test at the interface of the steel plate-concrete composite structure.

[0072] Accordingly, embodiments of the present invention also provide an installation and testing method based on the aforementioned built-in three-dimensional bond slip testing device, such as... Figure 19 As shown, the method includes the following steps:

[0073] Processing and manufacturing steel shells;

[0074] Multiple studs are welded to the outer wall of the steel shell;

[0075] A preload spring is provided at the bottom of the steel shell;

[0076] A sliding head is installed above the preload spring;

[0077] A hollow guide tube is installed in the middle of the sliding head;

[0078] Six string strain gauges are installed, two each in the X, Y, and Z directions; the six string strain gauges are all hinged to the sliding head and the inner wall of the steel shell;

[0079] The wire of the string strain gauge is led out through the sliding head and the hollow conduit;

[0080] Insert the positioning bolt into the hollow conduit through the positioning hole at the top of the steel plate, and tighten it with the bolt hole at the bottom of the steel shell;

[0081] The periphery of the steel shell and the bottom of the steel plate are sealed with silicone rubber and left to stand for more than 24 hours.

[0082] Pour concrete and cure for 28 days;

[0083] Connect the wires of the string strain gauge to the multi-channel strain acquisition box, which is then connected to a computer terminal.

[0084] Remove the positioning bolts to restore the sliding head's degrees of freedom in the X, Y, and Z directions;

[0085] Load and perform calibration tests;

[0086] After completing the calibration tests in the X, Y, and Z directions, it is used for actual testing.

[0087] Based on a novel internal structure, this invention uses six miniature string strain gauges symmetrically arranged in the X, Y, and Z directions as sensing elements. This allows for simultaneous bond slip testing in the X and Y directions and vertical peeling testing in the Z direction at the steel plate-concrete interface, overcoming the shortcomings of existing bond slip testing methods that are limited in direction and have low dimensionality.

[0088] This invention is based on string strain gauge measurement, which solves the technical drawbacks of traditional strain gauge sensing, which requires long-term real-time power supply and cannot achieve intermittent testing. It can realize repeatable and intermittent non-continuous testing of interface slip damage, and significantly improve the feasibility of long-term monitoring of interface damage in composite structures.

[0089] In addition, the device has significant advantages such as convenient installation, high testing accuracy, and stable performance. It can be widely used in testing various working conditions such as monotonic loading, cyclic loading, and static dynamic impact loading, as well as in health monitoring of steel plate-concrete composite structures.

[0090] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0091] The use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0092] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.

[0093] It is understood that the meanings of “on”, “above” and “above” in this disclosure should be interpreted in the broadest sense, such that “on” means not only “directly on” something, but also includes something with an intermediary feature or layer, and that “above” or “above” means not only “on” something, but also includes something “above” or “above” without an intermediary feature or layer.

[0094] Furthermore, spatially related terms such as “below,” “under,” “lower,” “above,” and “upper” are used herein for convenience to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the accompanying drawings. Spatially related terms are intended to cover different orientations in the use or operation of the device other than those depicted in the accompanying drawings. The device may be oriented in other ways, and the spatially related descriptive terms used herein can be interpreted similarly.

[0095] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0096] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A built-in three-dimensional cohesive slip test device, characterized by, The device is used for testing the bond slip and vertical peeling at the interface of steel plate-concrete composite structure, and is installed in the inside of the steel plate before pouring concrete, comprising a steel shell and a core test element in the steel shell, and the steel shell is sealed with the bottom of the steel plate; The core test element comprises a hollow conduit, a sliding head, a pre-tightening spring and six string strain gauges; the hollow conduit is vertically arranged in the middle of the steel shell, the upper end penetrates through the positioning hole in the top of the steel plate, and the lower end can freely slide on the bottom contact surface of the steel shell; the sliding head is sleeved on the outside of the hollow conduit and can slide up and down along the hollow conduit; the pre-tightening spring is arranged below the sliding head, the upper end is connected with the sliding head, and the lower end is in contact with the bottom of the steel shell, and the pre-tightening spring provides a pre-tightening force to make the sliding head in contact with the top of the steel plate; Six string strain gauges are arranged in two in each of X, Y and Z directions, respectively, for testing the slip amount in X and Y directions and the peeling amount in Z direction between the steel plate and the concrete, one end of each string strain gauge is hinged to the sliding head, and the other end is hinged to the inner wall of the steel shell.

2. The built-in three-dimensional cohesive slip test device according to claim 1, wherein The device is positioned and installed by positioning bolts, the positioning bolts sequentially comprise a nut, a variable cross-section screw rod and a bottom thread from top to bottom; the positioning bolts are inserted into the hollow conduit through the positioning hole in the top of the steel plate, and are screwed with the bolt hole in the bottom of the steel shell, after the concrete is hardened, the positioning bolts are removed to release the constraint on the sliding head, so that the sliding head freely slides in X and Y directions.

3. The built-in three-dimensional cohesive slip test device according to claim 1, wherein The steel shell is a square shell with an open top, the steel shell is packaged with the bottom of the steel plate by a sealing rubber ring, the sealing rubber ring is formed by applying silicone rubber, so as to avoid the intrusion of moisture before the concrete hardens.

4. The built-in three-dimensional cohesive slip test device of claim 1, wherein, Multiple studs are arranged on the outside and the bottom of the steel shell to enhance the link with the concrete, avoid the separation of the steel shell caused by the shrinkage of the concrete, and ensure the integrity of the test device and the concrete.

5. The built-in three-dimensional cohesive slip test device of claim 1, wherein, A cylindrical through hole is arranged in the middle of the sliding head, the diameter of the cylindrical through hole is consistent with the diameter of the outer wall of the hollow conduit, so that the sliding head can slide in Z direction without constraint, and the degrees of freedom of the sliding head and the hollow conduit in X and Y directions are consistent.

6. The built-in three-dimensional cohesive slip test device of claim 1, wherein, The six string strain gauges are respectively a first X-direction string strain gauge, a second X-direction string strain gauge, a first Y-direction string strain gauge, a second Y-direction string strain gauge, a first Z-direction string strain gauge and a second Z-direction string strain gauge; The first X-direction string strain gauge and the second X-direction string strain gauge are symmetrically arranged, the measurement results of the two are averaged, and the average value is taken as the test result of the X-direction slip amount; the first Y-direction string strain gauge and the second Y-direction string strain gauge are symmetrically arranged, the measurement results of the two are averaged, and the average value is taken as the test result of the Y-direction slip amount; the first Z-direction string strain gauge and the second Z-direction string strain gauge are symmetrically arranged, the measurement results of the two are averaged, and the average value is taken as the test result of the Z-direction peeling amount.

7. The built-in three-dimensional cohesive slip test device according to claim 6, wherein The first X-directional string strain gauge, the second X-directional string strain gauge, the first Y-directional string strain gauge, the second Y-directional string strain gauge, the first Z-directional string strain gauge and the second Z-directional string strain gauge each comprise a first support and a second support; wherein the first support is hinged to the sliding head, and the second support is hinged to the inner wall of the steel shell.

8. The built-in three-dimensional cohesive slip test device of claim 1, wherein, The sliding head is provided with a wire slot, the hollow conduit is provided with an inlet hole and an outlet hole, and the wires of the string strain gauges are led out of the device outside in sequence along the wire slot, the inlet hole and the outlet hole.

9. The built-in three-dimensional cohesive slip test device of claim 1, wherein, The wires of the six string strain gauges are connected to a multi-channel strain collection box after being led out of the device outside, and the multi-channel strain collection box is connected to a computer terminal.

10. A mounting test method based on the built-in three-dimensional cohesive slip test device according to any one of claims 1 to 9, characterized by, The method comprises the following steps: Processing and manufacturing a steel shell; Welding a plurality of pegs on the outer wall of the steel shell; Providing a pre-tightening spring at the bottom of the steel shell; Installing a sliding head above the pre-tightening spring; Installing a hollow conduit in the middle of the sliding head; Installing six string strain gauges, two in each of the X, Y and Z directions; the six string strain gauges are hinged to the sliding head and the inner wall of the steel shell; Leading the wires of the string strain gauges out through the sliding head and the hollow conduit; Inserting a positioning bolt through a positioning hole on the top of the steel plate into the hollow conduit and tightening it with a bolt hole at the bottom of the steel shell; Sealing the periphery of the steel shell with the bottom of the steel plate with silicone rubber, and placing it for more than 24 hours; Pouring concrete and curing it for 28 days; Connecting the wires of the string strain gauges to a multi-channel strain collection box, and connecting the multi-channel strain collection box to a computer terminal; Removing the positioning bolt to restore the freedom of the sliding head in the X, Y and Z directions; Loading and performing calibration test; After completing the calibration test in the X, Y and Z directions, the test is used for actual test.

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