A new and old concrete interface influence test device

Abstract

The present application relates to the technical field of simulation test device, and specifically relates to a new and old concrete interface influence test device, which comprises a test frame, a concrete pile and an extrusion and shearing coupling assembly, the extrusion and shearing coupling assembly is installed on the test frame, the concrete pile is installed on the extrusion and shearing coupling assembly, a loading assembly is arranged on the test frame, and the loading assembly is used for applying load to the concrete pile; the extrusion and shearing coupling assembly comprises a test box, an extrusion unit and a shearing stress applying unit, the extrusion unit and the shearing stress applying unit are arranged in the test box, and the extrusion unit is connected with the shearing stress applying unit, and the test box is filled with matrix particles, so that the technical problem that the existing new and old concrete interface test device cannot synchronously simulate the collaborative change of pile body resistance and extrusion effect in the pile sinking process is solved.

Description

Technical Field

[0001] This invention relates to the field of simulation test equipment technology, and specifically to a test device for the influence of the interface between new and old concrete. Background Technology

[0002] The interface between new and old concrete is widely present in bridge pile foundation engineering. During the service life of pile foundations, the interface between new and old concrete is often formed due to construction splicing, maintenance and reinforcement, or local damage repair. The mechanical properties of this interface area have a significant impact on the bearing capacity and durability of the entire pile. However, the bonding quality of the new and old concrete interface is constrained by a variety of factors. Studies have shown that factors such as interface roughness, type of interface agent, strength difference between new and old concrete, and curing conditions all significantly affect the bonding performance of the interface. Existing research mainly uses splitting tensile tests, double shear tests, and oblique shear tests to analyze the mechanical properties of the new and old concrete interface to evaluate the response characteristics of the interface under different stress modes. However, most of the above test methods are carried out under single shear or tensile conditions, which cannot truly reflect the complex stress environment of the interface area under the actual service conditions of the pile foundation.

[0003] In pile foundation engineering, when a pile sinks under vertical load, a relative misalignment tendency occurs between the pile and the surrounding soil medium, forming a shear stress distribution at the interface. This shear stress distribution tends to hinder pile sinking, and the stronger the shear stress, the greater the sinking. Simultaneously, the sinking process also exerts lateral pressure on the surrounding medium, creating a soil squeezing effect. This causes changes in the confining pressure exerted by the soil on the pile. The shear stress at the interface gradually increases, and the confining pressure intensifies with the degree of squeezing. In actual working conditions, these phenomena occur simultaneously and are coupled, jointly determining the actual load level and damage accumulation process at the interface between the old and new concrete. However, most current testing devices for the interface between old and new concrete can only simulate a single shear stress state and cannot simultaneously reproduce the complex mechanical environment of the coordinated changes in interface shear stress and soil squeezing effect during pile sinking. Furthermore, there is a lack of testing platforms capable of simulating this simultaneous change in both sinking-driven effects.

[0004] Therefore, in view of this, the inventors proposed a test device for the influence of the interface between new and old concrete to solve the above-mentioned technical problems. Summary of the Invention

[0005] One of the objectives of this invention is to provide a test device for the influence of the interface between new and old concrete, so as to solve the technical problem that existing test devices for the interface between new and old concrete cannot simultaneously simulate the coordinated changes of pile resistance and soil squeezing effect during pile sinking.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A test apparatus for the influence of the interface between new and old concrete includes a test frame, a concrete pile, and a soil squeezing shear coupling component. The soil squeezing shear coupling component is installed on the test frame, and the concrete pile is installed on the soil squeezing shear coupling component. A loading component is provided on the test frame for applying a load to the concrete pile. The soil squeezing shear coupling assembly includes a test chamber, a squeezing unit, and a shear stress application unit. The squeezing unit and the shear stress application unit are disposed inside the test chamber, and the squeezing unit is connected to the shear stress application unit. The test chamber is filled with matrix particles. When the loading component drives the concrete pile to sink, the concrete pile drives the extrusion unit to extrude the matrix particles to simulate the soil squeezing effect during the sinking process of the concrete pile; the shear stress application unit generates a gradually increasing clamping force on the concrete pile to simulate the interface shear stress on the pile body during the sinking process.

[0007] Furthermore, the test box is provided with a polygonal frame and a frame body, and the polygonal frame is fixedly installed inside the test box; The frame body is located outside the polygonal frame.

[0008] Furthermore, the extrusion unit includes a plurality of extrusion members, each of which is evenly distributed around the polygonal frame; The extrusion component includes a mounting platform, a gear, and a first rack. The gear is rotatably mounted on the mounting platform, and the first rack is slidably mounted on the mounting platform. The gear meshes with the first rack. One end of the first rack is provided with a conical block, and the other end of the first rack is connected to a push plate; each of the conical blocks is evenly distributed around the center of the polygonal frame.

[0009] Furthermore, a plurality of compression chambers are formed between the frame and the test box, and the compression chambers are filled with a medium. Each pusher plate extends into the corresponding compression chamber, and the pusher plate is capable of compressing the medium in the compression chamber.

[0010] Furthermore, the shear stress application unit includes several clamping members, each clamping member including a second rack and a shear stress transmission block. The second rack is slidably mounted on the mounting platform, and the second rack meshes with the gear. The first rack and the second rack are arranged parallel to each other, and the shear stress transmission block is fixedly connected to the second rack.

[0011] Furthermore, the surface of the shear stress transfer block that contacts the concrete pile is provided with a friction-enhancing layer or a pattern.

[0012] Furthermore, the cross-section of the shear stress transfer block is tapered, and an elastic buffer is provided between the shear stress transfer block and the second rack.

[0013] Furthermore, the loading assembly includes a loading plate, two first guide posts and a cylinder. The cylinder is fixedly mounted on the test frame, and the piston end of the cylinder is connected to the top of the loading plate. The two first guide posts are mounted on the loading plate and slidably mounted on the test frame. Two second guide posts are fixedly installed at the bottom of the loading plate.

[0014] Furthermore, a support plate is provided at the bottom of the second guide column, which is used to drive the concrete pile to move downward.

[0015] Furthermore, the lower end of the concrete pile is provided with a pile tip.

[0016] The beneficial effects of this invention are: A test chamber is filled with matrix particles to simulate the soil surrounding the pile. A concrete pile is installed in a soil-squeezing shear coupling assembly, creating a mating relationship between the concrete pile and the squeezing and shear stress application units within the assembly. The loading assembly is then activated to apply a vertical downward load to the concrete pile, causing it to gradually sink. During the sinking process, the contact between the concrete pile and the squeezing units causes the squeezing units to move, applying a squeezing force to the matrix particles filling the test chamber. As the sinking depth of the concrete pile increases, the squeezing force on the matrix particles gradually intensifies, thus simulating the soil-squeezing effect on the surrounding soil during pile sinking in pile foundation engineering.

[0017] Other advantages, objectives, and features of this application will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from practice of this application. The objectives and other advantages of this application may be realized and obtained through the detailed embodiments described below. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the test device for the influence of the interface between new and old concrete according to the present invention. Figure 2 This is a schematic diagram of the structure behind the hidden test box of the experimental device for testing the influence of the interface between new and old concrete according to the present invention; Figure 3 This is a partial structural schematic diagram of the experimental device for testing the influence of the interface between new and old concrete according to the present invention. Figure 4 This is a schematic diagram of the water-drive linkage component in the experimental device for testing the influence of the interface between new and old concrete in this invention. Figure 5 This is a schematic diagram of the disassembled structure of the water-drive linkage component in the experimental device for testing the influence of the interface between new and old concrete of the present invention. Figure 6 This is a cross-sectional schematic diagram of the water-drive linkage component of the experimental device for testing the influence of the interface between new and old concrete according to the present invention. Figure 7 In this invention Figure 6 A magnified structural diagram of part A; Figure 8 This is a schematic diagram of the concrete pile structure of the experimental device for testing the influence of the interface between new and old concrete according to the present invention; Figure 9 This is a schematic diagram of the steel mesh unit of the present invention before deformation when subjected to high-pressure water impact; Figure 10 This is a schematic diagram of the steel mesh unit of the present invention after deformation when subjected to high-pressure water impact; Figure 11 This is a cross-sectional structural diagram of the concrete pile in this invention; Figure 12 In this invention Figure 11 A schematic diagram of the enlarged structure of part B; Figure 13 This is a schematic diagram of the structure of the soil squeezing shear coupling component in this invention; Figure 14 In this invention Figure 13 Partial structural diagram; Figure 15 In this invention Figure 13 A partial sectional view of the structure; Figure 16 This is a schematic diagram showing the connection between the clamping components in this invention; Figure 17 This is a front view of the clamping component in this invention.

[0019] The components include: test frame 1, concrete pile 2, outer casing 21, old concrete column 22, new concrete column 23, installation slot 24, water-driven linkage assembly 3, clamping unit 31, rotating disk 312, clamping part 313, clamping block 3131, sliding pin 3132, arc groove 3133, slider 3134, slide rail 3135, spray column 314, water outlet 315, first flow channel 316, second flow channel 317, third flow channel 318, turbine unit 32, turbine housing 321, first turbine 322, second turbine 323, drive shaft 324, high-pressure water pipe 325, and steel mesh unit. 4. Fixed steel ring 41, sliding steel ring 42, reinforcing bar 43, connecting rod 44, push rod 45, heating unit 46, soil squeezing shear coupling assembly 5. Test box 51, squeezing unit 52, shear stress application unit 53, polygonal frame 54, frame body 55, squeezing component 56, mounting platform 561, gear 562, first rack 563, conical block 564, push plate 565, compression chamber 566, clamping component 57, second rack 571, shear stress transfer block 572, loading assembly 6, loading plate 61, first guide post 62, cylinder 63, second guide post 64, support plate 311. Detailed Implementation

[0020] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0021] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] This embodiment proposes a test device for the influence of the interface between new and old concrete, such as... Figures 1 to 17As shown, the test includes a test frame 1, a concrete pile 2, and a soil squeezing shear coupling assembly 5. The lower end of the concrete pile 2 is provided with a pile tip. The soil squeezing shear coupling assembly 5 is installed on the test frame 1, and the concrete pile 2 is installed on the soil squeezing shear coupling assembly 5. The test frame 1 is provided with a loading assembly 6, which is used to apply a vertical load to the concrete pile 2. The soil squeezing shear coupling assembly 5 includes a test box 51, a squeezing unit 52, and a shear stress application unit 53. The squeezing unit 52 and the shear stress application unit 53 are arranged inside the test box 51, and the squeezing unit 52 is connected to the shear stress application unit 53. The test box 51 is filled with matrix particles. When the loading assembly 6 drives the concrete pile 2 to sink, the concrete pile 2 drives the squeezing unit 52 to squeeze the matrix particles to simulate the soil squeezing effect during the sinking process of the concrete pile 2. The shear stress application unit 53 generates a gradually increasing clamping force on the concrete pile 2 to simulate the interface shear stress on the pile body during the sinking process.

[0023] In this embodiment, the test chamber 51 is first filled with matrix particles to simulate the soil around the pile. The concrete pile 2 is then installed in the soil squeezing shear coupling assembly 5, forming a cooperative relationship between the concrete pile 2 and the squeezing unit 52 and shear stress application unit 53 within the assembly 5. The loading assembly 6 is then activated to apply a vertical downward load to the concrete pile 2, driving it to gradually sink downwards. During the sinking process of the concrete pile 2, due to the contact between the concrete pile 2 and the squeezing unit 52, the downward movement of the concrete pile 2 causes the squeezing unit 52 to move. The squeezing unit 52 applies a squeezing action to the matrix particles filled in the test chamber 51, and as the sinking depth of the concrete pile 2 increases, the squeezing degree of the squeezing unit 52 on the matrix particles gradually increases, thereby simulating the soil squeezing effect on the surrounding soil when the pile sinks in a pile foundation project. Meanwhile, since the extrusion unit 52 is connected to the shear stress application unit 53, the action of the extrusion unit 52 is transmitted to the shear stress application unit 53, so that the shear stress application unit 53 begins to apply a clamping force to the concrete pile 2 as the concrete pile 2 sinks, thereby increasing friction and hindering the sinking of the pile. Furthermore, as the concrete pile 2 continues to sink, the degree of extrusion of the matrix particles by the extrusion unit 52 continuously increases, and the clamping force of the shear stress application unit 53 on the concrete pile 2 also gradually increases. This simulates the physical law that the interfacial shear stress (i.e., the resistance to the sinking of the pile) on the pile body gradually increases with the increase of settlement during the pile sinking process. Thus, the device, through the single sinking action of the concrete pile 2, and the linkage transmission between the extrusion unit 52 and the shear stress application unit 53, simultaneously realizes the synchronous and synergistic enhancement of the soil squeezing effect and the interfacial shear stress, reproducing the complex mechanical environment in actual working conditions where the two effects gradually increase with the depth of pile penetration.

[0024] In a preferred embodiment, a polygonal frame 54 and a frame body 55 are provided inside the test chamber 51. The polygonal frame 54 is fixedly installed inside the test chamber 51, and the frame body 55 is located outside the polygonal frame 54. Further, the extrusion unit 52 includes a plurality of extrusion members 56, each extrusion member 56 being evenly distributed around the polygonal frame 54. Each extrusion member 56 includes a mounting platform 561, a gear 562, and a first rack 563. The gear 562 is rotatably mounted on the mounting platform 561, and the first rack 563 is slidably mounted on the mounting platform 561, with the gear 562 meshing with the first rack 563. One end of the first rack 563 is provided with a conical block 564, and the other end of the first rack 563 is connected to a push plate 565. Each conical block 564 is evenly distributed around the center of the polygonal frame 54.

[0025] In this embodiment, when the loading component 6 drives the concrete pile 2 to sink downward, the bottom (or tip) of the concrete pile 2 contacts the inclined surface of each conical block 564 and applies downward pressure. Since the inclined surface of the conical block 564 converts the vertical force into a horizontal component, it forces each conical block 564 to move radially outward. The conical block 564 is fixedly connected to the first rack 563, so the first rack 563 also slides outward on the mounting platform 561. At the same time, the first rack 563 drives the meshing gear 562 to rotate, and the push plate 565 connected to the other end of the first rack 563 moves outward synchronously, providing displacement input for subsequent compression medium or triggering other linkage mechanisms. A plurality of compression chambers 566 are formed between the frame 55 and the test chamber 51. The compression chambers 566 are filled with a compressible medium, preferably a mixture of matrix particles and water. Each push plate 565 extends into the corresponding compression chamber 566 and can compress the medium in the compression chamber 566.

[0026] When the loading component 6 drives the concrete pile 2 to sink, the bottom of the concrete pile 2 pushes each conical block 564 to move radially outward. The conical block 564 drives the first rack 563 to slide outward on the mounting platform 561, thereby causing the push plate 565 at the other end of the first rack 563 to advance synchronously into the compression chamber 566. As the push plate 565 gradually penetrates deeper into the compression chamber 566, the volume of the compression chamber 566 continuously decreases, and the pressure of the medium gradually increases after being squeezed. The degree of compression of the medium is proportional to the displacement of the push plate 565, and the displacement of the push plate 565 directly depends on the sinking depth of the concrete pile 2. Therefore, the medium pressure increases monotonically with the increase of the pile sinking. This process simulates the lateral squeezing effect (i.e., soil squeezing effect) generated on the surrounding soil when the pile sinks in pile foundation engineering. The deeper the sinking, the larger the volume of soil displaced, and the stronger the squeezing of the medium around the pile, thus realistically reproducing the physical law that the soil squeezing effect gradually increases with the pile penetration depth. Meanwhile, the constraint effect of the compression chamber 566 on the medium ensures that the squeezing action is concentrated and controllable, which makes it easy to simulate the soil squeezing response characteristics under different soil conditions by changing the medium with different stiffness (such as liquids with different viscosities or rubbers with different elastic moduli).

[0027] It should be noted that this device does not simulate the complete process of the concrete pile 2 sinking indefinitely, but focuses on the mechanical response of the concrete pile 2 within a finite stroke from the initial contact compression unit 52 to the radial sliding of the conical block 564 to its limit position. In the actual structure, the inner wall of the test chamber 51 has stroke limits for the push plate 565 and the compression chamber 566. When the pile sinking displacement exceeds the maximum sliding distance of the conical block 564, the push plate 565 makes rigid contact with the bottom of the compression chamber 566 or the frame 55, and the compression effect no longer increases, thus forming a clear simulation range. This finite stroke corresponds precisely to the critical stage in actual pile foundation engineering where the soil squeezing effect and interface shear stress significantly increase with the increase of pile driving depth when the concrete pile 2 first penetrates the soil (usually within the range of 0.5 to 1 times the pile diameter). During this stage, the lateral compression of the concrete pile 2 on the surrounding soil and the increase of interface shear stress are most significant, which has important engineering value for studying the damage evolution of the interface between new and old concrete in the early stage of pile driving, and does not depend on the continuous infinite sinking of the concrete pile 2.

[0028] In a preferred embodiment, the shear stress application unit 53 includes several clamping members 57. Each clamping member 57 includes a second rack 571 and a shear stress transfer block 572. The second rack 571 is slidably mounted on the mounting platform 561. The second rack 571 meshes with the gear 562, and the first rack 563 is arranged parallel to the second rack 571. The shear stress transfer block 572 is fixedly connected to the second rack 571. The surface of the shear stress transfer block 572 that contacts the concrete pile 2 is provided with a friction enhancement layer or a pattern.

[0029] In this embodiment, when the concrete pile 2 sinks and causes each conical block 564 to move outward, the first rack 563 slides outward and drives the gear 562 to rotate. The gear 562 then drives the second rack 571 to move horizontally in the opposite direction (i.e., towards the center of the concrete pile 2). The shear stress transfer block 572 (e.g., a rubber block) fixedly connected to the second rack 571 gradually tightens inward, applying a gradually increasing clamping force to the outer wall of the concrete pile 2. Since the magnitude of the clamping force is directly related to the displacement of the first rack 563 (i.e., the sinking depth of the concrete pile 2), the deeper the sinking, the higher the degree of compression of the shear stress transfer block 572 on the pile body. This simulates the physical law that the interfacial shear stress (i.e., the resistance to the sinking of the pile body) between the pile body and the surrounding medium gradually increases with the increase of settlement during pile foundation engineering. To further enhance the realism of the simulation, the surface of the shear stress transfer block 572 in contact with the concrete pile 2 can also be provided with a friction enhancement layer or a pattern. These structures can increase the static friction coefficient between the shear stress transfer block 572 and the pile body, avoid relative slippage, and ensure that the clamping force can be effectively converted into tangential resistance acting on the pile surface, thereby making the simulation of interface shear stress more reliable.

[0030] In a preferred embodiment, the shear stress transfer block 572 has a tapered cross-section, and an elastic buffer (not shown) is provided between the shear stress transfer block 572 and the second rack 571. The cross-section of the shear stress transfer block 572 is designed as a tapered structure, that is, it gradually narrows inward or expands outward along the pile axis from top to bottom, so that the contact area or clamping angle between the shear stress transfer block 572 and the concrete pile 2 changes linearly with the sinking depth, thereby simulating the distribution law of interface shear stress at different depths of the pile. At the same time, an elastic buffer, such as a spring or rubber pad, is provided between the shear stress transfer block 572 (i.e., the main body of the shear stress transfer block 572) and the second rack 571. When the second rack 571 moves the shear stress transfer block 572 toward the concrete pile 2, the elastic buffer first undergoes compression deformation, changing the contact force between the shear stress transfer block 572 and the pile surface from soft to rigid, thus preventing abrupt changes in clamping force due to rigid impact. As the concrete pile 2 continues to sink, the second rack 571 advances further, the elastic buffer is gradually compressed, and the clamping force of the shear stress transfer block 572 on the pile increases steadily. This structure not only buffers the instantaneous impact at initial contact, protecting the surface of the concrete pile 2 and the shear stress transfer block 572, but also allows for adjustment of the clamping force growth rate with displacement by selecting and replacing elastic buffers of different stiffnesses, thereby simulating the nonlinear relationship between interfacial shear stress and pile settlement under different soil conditions. Furthermore, the tapered cross-section combined with the elastic buffer allows the shear stress transfer block 572 to adapt to slight pile eccentricity and surface unevenness during clamping, ensuring uniform distribution of clamping force and improving the repeatability and accuracy of the experiment.

[0031] In a preferred embodiment, the loading assembly 6 includes a loading plate 61, two first guide posts 62 and a cylinder 63. The cylinder 63 is fixedly mounted on the test frame 1, and the piston end of the cylinder 63 is connected to the top of the loading plate 61. The two first guide posts 62 are mounted on the loading plate 61 and are slidably mounted on the test frame 1. Two second guide posts 64 are fixedly mounted on the bottom of the loading plate 61.

[0032] In the loading assembly 6, a cylinder 63 is fixedly mounted on the test frame 1. The piston end of the cylinder 63 is connected to the top of the loading plate 61, providing driving force for the entire loading process. Two first guide posts 62 are installed on the loading plate 61. These two first guide posts 62 are slidably engaged in the guide holes or guide sleeves opened on the test frame 1 to ensure that the loading plate 61 can only rise and fall smoothly in the vertical direction under the drive of the cylinder 63, preventing deflection or shaking. Two second guide posts 64 are fixedly mounted on the bottom of the loading plate 61. The lower ends of the second guide posts 64 are used to contact the top of the concrete pile 2 or the support plate 311. When cylinder 63 is started, the piston rod extends and pushes loading plate 61 downward. The first guide column 62 slides synchronously on the test frame 1 to maintain vertical guidance accuracy. At the same time, loading plate 61 drives second guide column 64 to move downward together. The second guide column 64 then pushes concrete pile 2 (or indirectly pushes it through support plate 311) to perform vertical sinking action, providing stable displacement input for the subsequent linkage operation of soil squeezing shear coupling component 5.

[0033] In a preferred embodiment, a water-driven linkage assembly 3 is provided on the test frame 1. The concrete pile 2 is installed on the test frame 1. The water-driven linkage assembly 3 includes a clamping unit 31 and a turbine unit 32 connected to the clamping unit 31. The clamping unit 31 has a water outlet 315 at its center. When high-pressure water is introduced into the turbine unit 32, it drives the clamping unit 31 to clamp and destroy the concrete pile 2. At the same time, the high-pressure water is sprayed out from the water outlet 315 and acts on the end of the concrete pile 2 to simulate the peeling effect of water on the concrete pile 2. It also includes a steel mesh unit 4. The steel mesh unit 4 includes a fixed steel ring 41, a sliding steel ring 42 and several steel bars 43. The sliding steel ring 42 is located on the side close to the water outlet 315. When the high-pressure water is sprayed out from the water outlet 315, it impacts the sliding steel ring 42 and pushes the sliding steel ring 42 to move towards the fixed steel ring 41, causing the steel bars 43 to be displaced, simulating the deformation of the steel mesh unit 4.

[0034] In this device, the clamping unit 31, hydraulic stripping, and the deformation of the reinforcing mesh unit 4 are linked through the same high-pressure water source. This is because in actual underwater pile foundation reinforcement projects, the failure of the interface between the old and new concrete is not caused by a single factor. The hydraulic splitting wedge pressure generated when water seeps into the interface between the old and new concrete, the continuous impact erosion on the pile end, and the radial dynamic deformation of the reinforcing mesh under external water or earth pressure all exist simultaneously, are coupled, and are mutually causal. It should be particularly noted that under actual service conditions, the reinforcing mesh often does not immediately undergo significant geometric deformation, but rather first develops an inherent deformation tendency under external force (i.e., radial bending internal stress accumulates inside the reinforcing bars 43). This tendency changes the circumferential constraint stress distribution of the reinforcing mesh on the new concrete, thereby affecting the expansion of the hydraulic splitting path and the evolution of the interface's anti-stripping ability. If the test device can only simulate clamping or hydraulic stripping separately, and treats the reinforcing mesh as a stationary rigid body, it cannot capture the dynamic modulation effect of the reinforcing mesh's "about to deform but not yet fully deformed" state on the interface stress field and seepage field. It also cannot reveal the complete mechanical process of how the dynamic deformation of the reinforcing mesh under external forces changes the circumferential constraint force on the new concrete, thus affecting the hydraulic fracturing path and the interface's anti-stripping ability under real service conditions. Therefore, this device utilizes the same high-pressure water flow to simultaneously drive the turbine unit 32 to generate mechanical clamping, impact the pile end through the central outlet 315 to achieve hydraulic stripping, and impact the sliding steel ring 42 through the lateral outlet 315 to cause deformation of the reinforcing mesh unit 4. This allows the three actions to occur synchronously in time and space, influencing each other, thus realistically reproducing the progressive failure mechanism of the underwater pile foundation reinforcement interface under the coupled effects of water pressure, scour, and structural deformation. This overcomes the limitations of existing test devices that can only conduct single or two-factor tests, providing a new indoor simulation method for accurately evaluating the long-term durability of the interface between new and old concrete in a hydraulically coupled environment. To reproduce this coupled failure mechanism indoors, the concrete pile 2 was first installed on the test frame 1, and the water-driven linkage assembly 3 was arranged above the concrete pile 2. When the test was started, high-pressure water was introduced into the turbine unit 32. The high-pressure water drove the turbine unit 32 to rotate, and the turbine unit 32 drove the clamping unit 31 connected to it to move, so that the clamping unit 31 exerted a radial clamping effect on the concrete pile 2, simulating the mechanical clamping failure caused by external water pressure or soil pressure. At the same time, the same stream of high-pressure water was ejected at high speed through the water outlet 315 opened in the center of the clamping unit 31, directly impacting the end of the concrete pile 2, simulating the peeling and erosion effect of the high-pressure water flow on the pile end material.Furthermore, since the sliding steel ring 42 in the steel mesh unit 4 is located near the water outlet 315, when high-pressure water is sprayed out from the water outlet 315, its water force directly impacts the end face of the sliding steel ring 42, pushing the sliding steel ring 42 to move towards the fixed steel ring 41. The sliding steel ring 42, through several steel bars 43 connected to it, causes the steel bars 43 to have a tendency to displace, and has internal stress that causes displacement. Combined with the deformation of the steel mesh under external water pressure, the mechanical clamping of the clamping unit 31, the hydraulic peeling of the central water outlet 315, and the deformation of the steel mesh driven by the sliding steel ring 42 are simultaneously driven by a single high-pressure water source, realizing the synchronous linkage of the three in the same test.

[0035] In a preferred embodiment, the turbine unit 32 includes a turbine housing 321, a first turbine 322, and a second turbine 323. The first turbine 322 and the second turbine 323 are coaxially and fixedly connected. The first turbine 322 and the second turbine 323 are rotatably mounted inside the turbine housing 321. The second turbine 323 is coaxially and fixedly connected to a drive shaft 324. The turbine housing 321 is connected to a high-pressure water pipe 325. The high-pressure water pipe 325 introduces an external high-pressure water source into the inner cavity of the turbine housing 321. The high-pressure water flow first impacts the first turbine 322. Since the first turbine 322 and the second turbine 323 are coaxially and fixedly connected and synchronously rotated inside the turbine housing 321, the water flow drives the first turbine 322 to rotate while also acting on the second turbine 323, forming a two-stage series drive to fully utilize the kinetic energy of the water and improve the output torque. During its rotation, the second turbine 323 drives the drive shaft 324, which is coaxially fixed to it, to rotate together. The drive shaft 324 extends into the clamping unit 31, transmitting rotational power to subsequent actuators such as the rotating disk 312, thereby driving the clamping unit 31 to apply radial clamping force to the concrete pile 2. At the same time, the high-pressure water flow does not exit directly after passing through the first turbine 322 and the second turbine 323, but continues to be transported forward along the flow channel inside the turbine housing 321, and finally sprays out through the water outlet 315 in the center of the clamping unit 31, realizing the synchronous linkage of hydraulic stripping and turbine drive. This allows the same stream of high-pressure water to generate sufficient mechanical driving force through the dual-turbine structure, while maintaining its own water pressure for subsequent end-face impact, achieving efficient conversion and diversion of hydraulic energy into mechanical energy.

[0036] In a preferred embodiment, the clamping unit 31 includes a support plate 311, a rotating disk 312, and several clamping parts 313. The end of the turbine housing 321 facing away from the high-pressure water pipe 325 is fixedly connected to the support plate 311. The rotating disk 312 is rotatably mounted on the support plate 311. A drive shaft 324 passes through the support plate 311 and is coaxially fixedly arranged with the rotating disk 312. The clamping parts 313 are evenly distributed around the rotating disk 312. A spray column 3 is fixedly arranged on the rotating disk 312. 14. There are multiple water outlet holes 315, each water outlet hole 315 is located on the liquid spray column 314. A first flow channel 316 is opened on the support plate 311, a second flow channel 317 is opened on the rotating disk 312, and a third flow channel 318 is opened inside the liquid spray column 314. The first flow channel 316, the second flow channel 317 and the third flow channel 318 are interconnected. The first flow channel 316 is connected to the inner cavity of the turbine housing 321, and the third flow channel 318 is connected to each water outlet hole 315.

[0037] The clamping part 313 includes a clamping block 3131, with a sliding pin 3132 formed at the bottom of the clamping block 3131. An arc-shaped groove 3133 is provided on the rotating disk 312, and the sliding pin 3132 is disposed within the arc-shaped groove 3133. A slider 3134 is provided on the clamping block 3131, and a slide rail 3135 is provided on the support plate 311. The slider 3134 is slidably disposed on the slide rail 3135. The end of the turbine housing 321 facing away from the high-pressure water pipe 325 is fixedly connected to the support plate 311. The rotating disk 312 is rotatably mounted on the support plate 311, and the drive shaft 324 passes through the support plate 311 and is coaxially fixed with the rotating disk 312. When the high-pressure water drives the turbine unit 32 to rotate, the drive shaft 324 drives the rotating disk 312 to rotate synchronously. A spray column 314 is fixedly provided on the rotating disk 312, and multiple water outlet holes 315 are provided on the spray column 314. The support plate 311… The rotating disk 312 and the spray column 314 are respectively provided with a first flow channel 316, a second flow channel 317, and a third flow channel 318, which are interconnected. The first flow channel 316 is connected to the inner cavity of the turbine housing 321, and the third flow channel 318 is connected to each water outlet 315. This allows the high-pressure water to be smoothly transported through the first flow channel 316, the second flow channel 317, and the third flow channel 318 after flowing through the turbine, and then sprayed out through the water outlet 315 of the spray column 314, thus achieving the hydraulic stripping function. At the same time, the rotating disk 312 is provided with an arc-shaped groove 3133. The sliding pin 3132 at the bottom of the clamping block 3131 is placed in the arc-shaped groove 3133, and the slider 3134 at the upper end of the clamping block 3131 slides and engages with the slide rail 3135 on the support plate 311, restricting the clamping block 3131 to move only radially. When the rotating disk 312 rotates, the curved profile of the arc-shaped groove 3133 forces the sliding pin 3132 to undergo radial displacement relative to the rotating disk 312. Since the slide rail 3135 provides radial guidance to the clamping block 3131 through the slider 3134, the sliding pin 3132 drives the entire clamping block 3131 to move along the direction of the slide rail 3135 (i.e., towards the center of the concrete pile 2). Multiple clamping blocks 3131 are evenly distributed around the rotating disk 312. Driven by the continuous rotation of the rotating disk 312, all clamping blocks 3131 synchronously converge towards the center, thereby applying a gradually increasing radial clamping force to the concrete pile 2, simulating the circumferential compression effect of external water pressure or soil pressure on the pile body. Through this structure, the rotational power provided by the turbine is converted into the radial linear motion of the clamping block 3131, while the high-pressure water flow maintains an independent jet path, achieving synchronous linkage between clamping and hydraulic stripping.

[0038] In a preferred embodiment, the concrete pile 2 includes an outer casing 21, an old concrete column 22, and a new concrete column 23. The new concrete column 23 covers the outside of the old concrete column 22, and the outer casing 21 is disposed on the outside of the new concrete column 23. An installation groove 24 is formed between the outer casing 21 and the old concrete column 22. The reinforcing mesh unit 4 is disposed at the installation groove 24, and the end of the reinforcing bar 43 extends into the new concrete column 23. In the concrete pile 2 structure of this embodiment, the old concrete column 22 represents the old pile body that needs to be reinforced and repaired. The new concrete column 23 covers the outside of the old concrete column 22 to form a reinforcement layer, while the outer casing 21 is disposed on the outside of the new concrete column 23 to simulate the protection of the concrete pile 2. For simulation testing, an annular installation groove 24 is formed between the outer casing 21 and the old concrete column 22. The reinforcing mesh unit 4 is arranged in the installation groove 24, wherein the fixing steel ring 41 and the sliding steel ring 42 are located in the installation groove 24, and the end of the reinforcing bar 43 extends into the interior of the new concrete column 23. When high-pressure water is ejected from the outlet 315 and impacts the sliding steel ring 42, the sliding steel ring 42 moves towards the fixed steel ring 41, driving the reinforcing bar 43 to deform via the push rod 45 and connecting rod 44. Since the end of the reinforcing bar 43 extends and is anchored in the new concrete column 23, the stress on the reinforcing bar 43 under high pressure will generate radial tensile or compressive stress on the surrounding new concrete column 23, thereby dynamically changing the circumferential constraint effect of the reinforcing mesh unit 4 on the new concrete column 23. This is used to reproduce the physical process in actual underwater reinforcement projects where the reinforcing mesh unit 4 wrapped around the new concrete undergoes geometric changes under external water pressure or soil pressure, thus altering the constraint force on the new concrete. This allows the test device to simulate the hydraulic coupling failure behavior of the interface between the old and new concrete under dynamic constraint conditions.

[0039] Furthermore, among the multiple water outlets 315 on the spray column 314, at least a portion of the water outlets 315 have their spray direction facing the end face of the sliding steel ring 42.

[0040] When high-pressure water flows through turbine unit 32, first flow channel 316, second flow channel 317, and third flow channel 318, and finally exits at high speed from the outlet 315, part of the high-pressure water flow acts on the installation slot 24, impacting and damaging the end face of the new concrete column 23. At the same time, another part of the water flow directly impacts the end face of the sliding steel ring 42, applying an axial thrust to it in the same direction as the water flow. When this axial thrust pushes the sliding steel ring 42 to move, the push rod 45 connected to it moves synchronously. The push rod 45 acts on the middle hinge point of the connecting rod 44. Since one end of the connecting rod 44 is hinged to the fixed steel ring 41 and the other end is hinged to the reinforcing bar 43, the axial force of the push rod 45 forces the connecting rod 44 to rotate around its hinge point with the fixed steel ring 41, thereby causing the reinforcing bar 43 to undergo radial swing deformation around its hinge point with the fixed steel ring 41, resulting in radial pre-stress inside the new concrete column 23. The presence of this prestress alters the circumferential constraint state of the new concrete column 23 on the internal old concrete column 22, thereby affecting the anti-stripping ability of the interface between the new and old concrete and the hydraulic splitting propagation path. In other words, the high-pressure water not only exerts a hydraulic stripping effect on the end of the concrete pile 2 through the central outlet 315, but also converts the water pressure into a mechanical force that drives the dynamic deformation of the steel mesh unit 4 through the lateral outlet 315. Ultimately, it actively introduces radial prestress into the new concrete layer, thus simulating the complex mechanical behavior of the steel mesh unit 4 under water or earth pressure in actual underwater reinforcement projects, where geometric deformation occurs and the circumferential constraint effect on the new concrete changes.

[0041] Furthermore, the fixed steel ring 41 is fixedly connected to the old concrete column 22, and the reinforcing bar 43 is hinged to the fixed steel ring 41. A connecting rod 44 is hinged to the fixed steel ring 41. One end of the connecting rod 44 is hinged to the fixed steel ring 41, and the other end of the connecting rod 44 is hinged to the reinforcing bar 43. A push rod 45 is connected to the sliding steel ring 42, and the push rod 45 is hinged to the middle of the connecting rod 44. The connecting rod 44 is L-shaped and one end is hinged to the fixed steel ring 41. When the middle part is subjected to the axial thrust of the push rod 45, the connecting rod 44 rotates around its hinge point with the fixed steel ring 41, and its other end drives the reinforcing bar 43 to generate radial displacement around the hinge point with the fixed steel ring 41. This results in a gradually increasing radial compression or tension on the new concrete column 23 encased on the outside, simulating the dynamic geometric deformation of the steel mesh unit 4 under external water pressure, soil pressure or ice expansion force in actual engineering and its change on the circumferential constraint effect of the new concrete, realizing the complete transmission chain of water pressure, mechanical linkage and structural deformation.

[0042] In a preferred embodiment, a heating unit 46 is also included. The heating unit 46 includes a heating cylinder fitted onto the outer casing 21, and an electric heating wire is installed inside the heating cylinder. The electric heating wire is connected to a power source. As a key component for simulating the temperature environment, the heating unit 46 operates as follows: the heating cylinder is tightly fitted onto the outside of the outer casing 21. The electric heating wire inside generates Joule heat after being energized by an external power source. The heat is gradually transferred through the heating cylinder wall and the outer casing 21 to the new concrete column 23 and the old concrete column 22, so that the entire concrete pile 2 and its internal steel mesh unit 4 are in a controllable temperature rise environment.

[0043] It also includes a testing system, which includes an electromagnetic flowmeter and pressure sensor installed at the inlet of the high-pressure water pipe 325, and an adjustable electric ball valve installed between the outlet of the turbine housing 321 and the first flow channel 316; a rotary encoder is installed between the support plate 311 and the rotating disk 312 for real-time monitoring of the rotation angle of the rotating disk 312; a flexible thin-film pressure sensor is attached between the contact surface of each set of clamping blocks 3131 and the concrete pile 2; and a high-frequency dynamic pressure sensor is installed at the water outlet 315 of the spray column 314 for measuring water... The jet impact force; a pull-wire displacement sensor is installed between the fixed steel ring 41 and the sliding steel ring 42 of the steel mesh unit 4 to detect the axial displacement of the sliding steel ring 42, and micro strain gauges are attached at the hinge points of each connecting rod 44 and the steel bar 43; thermocouple temperature sensors are pre-embedded at different depths at the old concrete column 22, the new concrete column 23 and the interface between the old and new concrete of the concrete pile 2; a solid-state relay and a temperature control switch are connected in series in the electric heating wire circuit of the heating cylinder; a non-contact infrared temperature probe is installed on the outside of the outer casing 21. The signal lines of all the above sensors and actuators are gathered into a waterproof junction box, and then connected to a data acquisition card with an isolation module through a multi-core shielded cable. The data acquisition card is connected to the industrial control computer via USB or Ethernet interface; the industrial control computer has a built-in program and is also connected to the variable frequency water pump of the high-pressure water source, the electric ball valve and the power regulator of the heating unit 46 to form a closed-loop control circuit. All electronic components are fixed on the bracket reserved on the outside of test frame 1. The sensor installation positions are all avoided in the high-pressure water direct spray area and are sealed with sealant to ensure long-term safe and reliable operation.

[0044] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A test apparatus for the influence of the interface between new and old concrete, characterized in that, include: The test frame (1), the concrete pile (2) and the soil squeezing shear coupling assembly (5) are provided. The soil squeezing shear coupling assembly (5) is installed on the test frame (1). The concrete pile (2) is installed on the soil squeezing shear coupling assembly (5). The test frame (1) is provided with a loading assembly (6) for applying load to the concrete pile (2). The soil squeezing shear coupling assembly (5) includes a test box (51), a squeezing unit (52) and a shear stress application unit (53). The squeezing unit (52) and the shear stress application unit (53) are arranged in the test box (51), and the squeezing unit (52) is connected to the shear stress application unit (53). The test box (51) is filled with matrix particles. When the loading component (6) drives the concrete pile (2) to sink, the concrete pile (2) drives the extrusion unit (52) to extrude the matrix particles to simulate the soil squeezing effect during the sinking process of the concrete pile (2); The shear stress application unit (53) generates a gradually increasing clamping force on the concrete pile (2) to simulate the interface shear stress on the pile body during the sinking process of the concrete pile (2).

2. The test apparatus for the influence of the interface between new and old concrete according to claim 1, characterized in that: The test box (51) is provided with a polygonal frame (54) and a frame body (55), and the polygonal frame (54) is fixedly installed inside the test box (51). The frame body (55) is located outside the polygonal frame (54).

3. The test apparatus for the influence of the interface between new and old concrete according to claim 2, characterized in that: The extrusion unit (52) includes a plurality of extrusion members (56), each of the extrusion members (56) being evenly distributed around the polygonal frame (54); The extrusion member (56) includes a mounting platform (561), a gear (562) and a first rack (563). The gear (562) is rotatably mounted on the mounting platform (561), and the first rack (563) is slidably mounted on the mounting platform (561). The gear (562) meshes with the first rack (563). One end of the first rack (563) is provided with a conical block (564), and the other end of the first rack (563) is connected to a push plate (565); each of the conical blocks (564) is evenly distributed around the center of the polygonal frame (54).

4. The test apparatus for the influence of the interface between new and old concrete according to claim 3, characterized in that: A plurality of compression chambers (566) are formed between the frame body (55) and the test box (51). The compression chambers (566) are filled with a medium. Each push plate (565) extends into the corresponding compression chamber (566). The push plate (565) can compress the medium in the compression chamber (566).

5. The test apparatus for the influence of the interface between new and old concrete according to claim 4, characterized in that: The shear stress application unit (53) includes several clamping members (57), each clamping member (57) including a second rack (571) and a shear stress transmission block (572). The second rack (571) is slidably mounted on the mounting platform (561), and the second rack (571) meshes with the gear (562). The first rack (563) and the second rack (571) are arranged parallel to each other, and the shear stress transmission block (572) is fixedly connected to the second rack (571).

6. The test apparatus for the influence of the interface between new and old concrete according to claim 5, characterized in that: The surface of the shear stress transfer block (572) that contacts the concrete pile (2) is provided with a friction enhancement layer or a pattern.

7. The test apparatus for the influence of the interface between new and old concrete according to claim 6, characterized in that: The cross-section of the shear stress transfer block (572) is tapered, and an elastic buffer is provided between the shear stress transfer block (572) and the second rack (571).

8. The test apparatus for the influence of the interface between new and old concrete according to claim 7, characterized in that: The loading assembly (6) includes a loading plate (61), two first guide posts (62) and a cylinder (63). The cylinder (63) is fixedly installed on the test frame (1). The piston end of the cylinder (63) is connected to the top of the loading plate (61). The two first guide posts (62) are installed on the loading plate (61) and are slidably installed on the test frame (1). Two second guide posts (64) are fixedly installed at the bottom of the loading plate (61).

9. The test apparatus for the influence of the interface between new and old concrete according to claim 8, characterized in that: The bottom of the second guide column (64) is provided with a support plate (311), which is used to drive the concrete pile (2) to move downward.

10. The test apparatus for the influence of the interface between new and old concrete according to claim 9, characterized in that: The lower end of the concrete pile (2) has a pile tip.

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