Bituminous pavement interlayer drawing shear apparatus and testing method

Abstract

The invention discloses an asphalt pavement interlayer drawing shear apparatus and a test method, and belongs to the technical field of highway engineering test detection. The upper clamp and the lower clamp are vertically arranged in the cylinder body and form an interlayer test piece clamping space; the drawing loading mechanism is composed of a drawing electric push rod and a lever mechanism, and the torsional shear loading mechanism is composed of a torsional shear electric push rod, a reversing mechanism, a rack shaft, a rack and a gear. The reversing mechanism converts vertical linear reciprocating motion into horizontal rack reciprocating motion through cooperation of the guide groove and the roller and drives the gear to drive the lower connecting shaft to rotate so as to achieve torsional shear loading. The sensing assembly comprises a tension sensor, a torsion sensor and an axial displacement sensor and / or an angular displacement sensor, the control system synchronously acquires load and displacement or rotation angle data through the data acquisition card, and the strain analysis module calculates the strain or deformation process before the test piece fails; and drawing and torsional shear dual-mode testing, data dimension improvement and automatic evaluation output are realized.

Description

Technical Field

[0001] This invention relates to the field of highway engineering testing technology, specifically to an asphalt pavement interlayer pull-out shear tester and testing method. Background Technology

[0002] Asphalt pavements typically consist of multiple layers, including a surface layer, a subbase layer, and a base course. These layers are bonded together by tack coat or adhesive materials. The performance of this interlayer bonding directly affects the overall integrity, fatigue resistance, and service life of the pavement structure. Insufficient interlayer bonding can easily lead to defects such as slippage, shoving, cracking, and loosening under vehicle loads and temperature changes, thereby reducing the pavement's load-bearing capacity and shortening its service life.

[0003] Currently, the engineering evaluation of the interlayer bond performance of asphalt pavement mainly adopts two main types of methods: pull-out tests and shear tests. Pull-out tests are conducted using a specialized pull-out apparatus (such as the WXLB-10kN tester), which applies a vertical tensile force through hydraulic or mechanical means and measures the maximum pull-out force. Its advantage is its simplicity of operation, but it only reflects static tensile strength and cannot simulate the shearing action of actual road traffic.

[0004] Shear tests are divided into torsion shear tests (such as the WXNJ-500NM torsion shear tester) and direct shear tests. The former applies rotational torque, while the latter applies horizontal thrust. Torsion shear tests are closer to the shear action of tires, but existing equipment can only measure peak torque and cannot record the strain history before failure.

[0005] In the prior art, patent document CN115165612A discloses an integrated torsion-shear-pull-out testing device for detecting the interlayer bond strength of road structure. Its main body includes a fixed frame, handwheel, torque multiplier, transmission mechanism, and main shaft. The testing personnel apply torque to the handwheel, which is amplified and output by the torque multiplier. Its advantages lie in combining two types of testing functions and adopting a manual force application + torque multiplication driving method, reducing reliance on motor drive. Therefore, the publication emphasizes that it can reduce equipment weight, facilitate portability, simplify operation, and improve testing efficiency. While efficient, this solution also has the following shortcomings: the mode switching still relies on "installing / connecting the corresponding torsion-shear detection device or pull-out detection device," which may lead to errors and efficiency losses due to component replacement, assembly alignment, and repeated clamping in field applications; at the same time, its public focus is on the handwheel-multiplier-transmission mechanism to achieve torsion-shear / pull-out conversion, without explaining the synchronous acquisition of full-process data such as displacement / rotation angle before failure and the strain (deformation) history analysis based on the load-displacement / rotation angle curve, thus lacking in multi-dimensional full-process characterization and automation.

[0006] Publication No. CN111999243A proposes a "shear-pull-out" test device and evaluation method for the interlayer bond performance of asphalt pavement. The device is usually based on a specimen mold and a horizontal force application mechanism, and can be used in conjunction with loading equipment such as a universal testing machine to apply horizontal force to composite specimens containing interlayer structures and carry out corresponding bond performance evaluation. It focuses on simulating the interlayer bond determination under certain complex stress conditions. Publication No. CN108037071A emphasizes that in-situ or quantitative torsional load testing can be performed. Its technical focus is more on the torque measurement link and structural connection method.

[0007] In addition, CN101275903A discloses a test method for the shear strength of interlayer bonding materials for pavement, which includes the torsional shear test concept and data acquisition and analysis process; CN101598649A discloses an interlayer interface shear tester for pavement structure, which realizes interlayer shear failure test through specific shear structure (such as shear plane angle setting); CN206671165U discloses an interlayer bonding performance test device with multiple shear angles, focusing on test adaptation under different shear angle conditions.

[0008] Based on the aforementioned representative public disclosures and existing engineering applications, it can be seen that while existing solutions cover different approaches such as pull-out, torsion-shear / shear, and shear-pull-out, they generally share certain shortcomings. Specifically, pull-out and torsion-shear / shear methods often present a "dispersed device" or "switching achieved by replacing / connecting different detection components" format, resulting in numerous on-site operation steps, a large workload of repetitive clamping and alignment, and a tendency to introduce alignment errors and reduce detection efficiency. At the same time, many devices still use peak tensile force or peak torque as the main output indicators, making it difficult to simultaneously acquire process data such as displacement and rotation angle before failure. Therefore, it is impossible to form a full-process curve of load-displacement / rotation angle and further conduct in-depth evaluation of indicators such as modulus and energy. In addition, when attempting to integrate tensile force measurement and torque measurement in the same shaft system or to arrange multiple sensors coaxially, problems such as force-torsion coupling, high coaxial installation accuracy requirements, and signal interference are likely to occur, thus affecting the stability and repeatability of the test.

[0009] Therefore, it is necessary to provide a test scheme for interlayer bonding performance that can perform pull-out and torsion-shear tests on the same device and can be easily switched between the two modes. At the same time, it can simultaneously collect data such as tensile force / torque and displacement / rotation angle to obtain full-process characterization information before specimen failure. Structurally, it should reduce coupling interference and structural redundancy under coaxial integration conditions to meet the requirements of efficiency, data integrity and reliability for asphalt pavement construction quality inspection and maintenance assessment. Summary of the Invention

[0010] The technical problem this invention aims to solve is to overcome existing defects and provide an asphalt pavement interlayer pull-out shear tester and testing method. The pull-out loading mechanism and the torsion-shear loading mechanism are integrated into the same cylinder. Switching between pull-out and torsion-shear tests can be completed using the same set of upper and lower clamps, avoiding multiple equipment configurations or frequent clamp module replacements and improving testing efficiency. The lower connecting shaft simultaneously satisfies short-stroke axial movement and small-angle rotation. A decoupled connection that allows axial relative sliding and torque transmission is achieved through a sliding key or sliding flat key. Combined with the coaxial arrangement of the tension and torque sensors and the structures of the upper connecting shaft, upper bushing, and grooved flange, force-torsion coupling and signal interference are reduced, and test stability and repeatability are improved, effectively solving the problems in the background technology.

[0011] To achieve the above objectives, the present invention provides the following technical solution: an asphalt pavement interlayer pull-out shear tester and testing method, comprising a cylinder, an upper clamp, a lower clamp, a lower connecting shaft, a pull-out loading mechanism, a torsion-shear loading mechanism, a sensing component, and a control system. The upper and lower clamps are arranged vertically within the cylinder, forming a clamping space for clamping interlayer specimens. The upper clamp is used to fix and clamp the upper end of the interlayer specimen, and the lower clamp is used to clamp the lower end of the interlayer specimen. The clamps can be those found on existing pull-out testers. The pull-out loading mechanism drives the lower clamp to generate an axial pull-out displacement relative to the upper clamp. The lower clamp is drively connected to the lower connecting shaft. The pull-out loading mechanism includes... The system includes a pull-out electric actuator and a lever mechanism connected to the pull-out electric actuator. The lever mechanism is hinged to the lower end of the cylinder and transmits force. The extension and retraction of the pull-out electric actuator drives the lever mechanism to rotate, thereby causing the lower connecting shaft to move axially. A torsion-shear loading mechanism is used to drive the lower connecting shaft to rotate around its axis. The torsion-shear loading mechanism includes a torsion-shear electric actuator, a reversing mechanism connected to the torsion-shear electric actuator, a rack shaft linked to the reversing mechanism, a rack mounted on the rack shaft, and a gear meshing with the rack. The rack shaft is located at the bottom of the cylinder, and its axis is preferably arranged horizontally and perpendicular to the axis of the gear, so that the rack can reliably mesh with the gear. Both ends of the rack shaft are supported on the cylinder by guide supports. The rack shaft can reciprocate in a predetermined direction within the cylinder, maintaining stable posture and a relatively constant meshing clearance with the gear during movement. The rack is mounted on the rack shaft; when the reversing mechanism outputs a lateral reciprocating motion, it drives the rack shaft to reciprocate within the cylinder, thereby causing the rack to perform reciprocating linear motion and driving the gear to rotate. To ensure controllable stroke, limiting structures are installed at both ends of the rack shaft's movement direction within the cylinder to limit the reciprocating range of the rack shaft and prevent disengagement or interference. The gear is connected to the lower connecting shaft to drive its rotation. The sensing components include a tension sensor and a torque sensor. The upper clamp is connected to the upper connecting shaft, which is connected to the upper end of the cylinder via the tension sensor. The device is connected to a tension sensor via an upper connecting shaft to collect tensile loads. A torque sensor is coaxially mounted with the upper connecting shaft, and its upper end is fixedly connected to the upper end of the cylinder. This torque sensor is used to collect torsional shear torque. The torque sensor and the tension sensor are electrically connected to the control system. The displacement acquisition component includes an axial displacement sensor and / or an angular displacement sensor for collecting tensile displacement and / or torsional shear angle. The control system includes a data acquisition card and a strain analysis module. The data acquisition card is electrically connected to the tension sensor, the torque sensor, and the displacement acquisition component to synchronously collect data. The strain analysis module is used to output interlayer bonding performance evaluation results based on the collected load data and displacement / angle data. Furthermore, a top cover is provided on the top of the cylinder body, the cylinder body is set on the base, the lever is set in the base, the upper end of the pull electric push rod is hinged to the upper end of the cylinder body, the telescopic end of the pull electric push rod is hinged to one end of the lever, the other end of the lever is hinged to the lower connecting shaft, a display screen is set on the cylinder body, the display screen is electrically connected to the control system, and is used to display the pulling force, torque and test results.

[0012] Furthermore, the tensile sensor and the torque sensor are arranged coaxially and positioned above the upper fixture. The upper connecting shaft is connected to the upper bushing via a sliding key along the vertical direction. The upper bushing is connected to the grooved flange via a keyway. The grooved flange is fixedly connected to the torque sensor by bolts. This structural design is not only compact but also meets the requirements for transmitting force in both the upward and circumferential directions of the upper connecting shaft, thus satisfying the requirements for pull-out and torsion tests.

[0013] Furthermore, the lower connecting shaft is slidably connected to the gear via a sliding key, so as to transmit the rotational torque of the gear to the lower connecting shaft and drive the lower clamp to rotate, which can satisfy both circumferential rotational displacement and vertical displacement. The reversing mechanism includes a guide frame with a guide groove. A roller is set in the guide groove. One end of the roller is connected to the rack. The torsion shear electric actuator drives the roller assembly to move under the constraint of the guide groove, so as to convert the vertical linear reciprocating motion of the torsion shear electric actuator into the horizontal lateral reciprocating motion of the rack shaft. The guide frame passes through the lower end of the cylinder body, and the upper end of the guide frame is connected to the output end of the torsion shear electric actuator via a pin.

[0014] During interlaminar bonding performance testing, interlaminar specimens typically fracture under small axial separation displacement and small relative reversal angular displacement. Therefore, in pull-out mode, this device only needs to drive the lower connecting shaft to achieve a short-stroke axial movement to complete the entire process from loading to failure. In torsion-shear mode, it only needs to drive the lower connecting shaft to achieve relative rotation within a small rotation range to complete torsion-shear failure.

[0015] Based on the aforementioned failure characteristics of the specimen, the rotation and movement ranges of the lower connecting shaft are relatively small. This allows the allowable movement of the hinge structure itself to cover the actual rotation angle range required for the test, enabling attitude self-adaptation and micro-angle compensation during loading. This ensures smooth rotation and stable force transmission while avoiding complex structures such as large-angle universal joints, reducing mechanism redundancy and assembly difficulty. It also helps to reduce the impact of additional lateral forces or additional bending moments on the test data, improving test stability and repeatability.

[0016] The reversing mechanism can also be configured with common structures, including: crank-rocker mechanism, hinge-lever reversing mechanism, etc., as long as it is suitable for converting linear or reciprocating motion into oscillation.

[0017] Furthermore, the sensing component also includes at least one of an axial displacement sensor and an angular displacement sensor; wherein, the axial displacement sensor is fixedly mounted on the cylinder body and / or base, and its measuring end is connected to or abuts against the lower connecting shaft and / or the lower clamp, for collecting the axial displacement of the lower clamp relative to the upper clamp; the angular displacement sensor is disposed at the end of the lower connecting shaft and / or at the gear linked to the lower connecting shaft, for collecting the torsional shear angular displacement of the lower clamp relative to the upper clamp; the control system calculates the strain or deformation history of the interlaminar specimen before failure based on the collected displacement data and / or angular data.

[0018] Furthermore, a test method for an interlayer pull-out shear tester of asphalt pavement includes the following steps: S1. Prepare interlayer specimens and clamp the interlayer specimens between the upper and lower clamps; S2. Set the specimen size parameters and loading parameters through the control system, and select the pull-out test mode or the torsion-shear test mode; S3. When the pull-out test mode is selected, the pull-out electric push rod is controlled to extend and retract and drive the lower connecting shaft to move axially via the lever mechanism, so that the lower clamp generates a pull-out displacement relative to the upper clamp, and applies a pull-out load to the interlayer specimen; at the same time, the pull-out load data output by the tension sensor and the displacement data output by the axial displacement sensor are collected. S4. When the torsion shear test mode is selected, the control torsion shear electric push rod drives the rack shaft through the reversing mechanism to drive the rack to move, so that the rack drives the gear to rotate and drives the lower connecting shaft to rotate, so that the lower clamp generates torsion shear relative rotation with respect to the upper clamp, and applies torsion shear load to the interlayer specimen; at the same time, the torque data output by the torque sensor and the rotation angle data output by the angular displacement sensor are collected. S5. The control system records and processes the collected data and outputs the evaluation results of interlayer bonding performance.

[0019] Furthermore, the control system synchronously samples the tension sensor, torque sensor, and displacement acquisition component through the data acquisition card, and performs time alignment between the load data and the displacement / rotation angle data to obtain the pull-out load-displacement curve and / or torque-rotation angle curve.

[0020] Furthermore, in the pull-out test mode, loading is completed within the preset axial displacement limit before the interlaminar specimen fractures, and in the torsion-shear test mode, loading is completed within the preset reversal angle limit before the interlaminar specimen fractures, so that the axial movement range and rotation range of the lower connecting shaft are both small. Since the axial movement range and rotation range of the lower connecting shaft are small, the movable margin reserved by the hinge structure of the lower connecting shaft itself is used to realize attitude self-adaptation and micro-angle compensation during the loading process, thereby meeting the rotation range required for the torsion-shear test.

[0021] Furthermore, the strain analysis module in the control system calculates the interlayer bond strength, bond strength modulus, and / or strain energy index based on the collected load data and displacement / rotation data, and generates corresponding evaluation conclusions.

[0022] Furthermore, the control system generates a test report from the test process data and evaluation conclusions, and displays the pull-out force, torque, curve data and / or test results on the display screen; the control system can be connected to a computer via an external interface to export the test data.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. By arranging the pull-out loading mechanism and the torsion-shear loading mechanism in the same cylinder, the same set of upper and lower clamps can be used to switch between pull-out and torsion-shear tests, avoiding the need to configure two separate devices or frequently change clamps and modules, reducing the complexity of on-site operation and improving testing efficiency.

[0024] 2. The lower connecting shaft achieves short-stroke axial movement in pull mode and small-angle rotation in torque-shear mode. A connection method that allows axial relative sliding and torque transmission is achieved through a sliding key or sliding flat key, which decouples axial displacement and circumferential torque transmission in structure, reduces the additional lateral force or bending moment caused by coupling, and improves test stability and repeatability. At the same time, the tension sensor and torque sensor are arranged coaxially, and together with the upper connecting shaft, upper bushing, grooved flange and sliding flat key, the requirements for axial force transmission and circumferential torque transmission are taken into account, reducing the risk of force and torque coupling and signal interference under compact arrangement conditions.

[0025] 3. Based on the collection of pull-out force and torque, axial displacement sensors and / or angular displacement sensors are further configured. The data acquisition card of the control system synchronously collects load and displacement or rotation data, and combines it with the strain analysis module to calculate the strain or deformation history of the interlayer specimen before failure, and obtain force and displacement curves, torque and rotation curves and their coupling curves. This provides a data basis for the evaluation of indicators such as bond strength modulus and strain energy, thereby improving the dimension and interpretation capability of the test data.

[0026] 4. By using a guide frame and guide groove in conjunction with rollers, the vertical linear reciprocating motion of the torsion shear electric push rod is converted into the horizontal lateral reciprocating motion of the rack shaft. The torque output to the lower connecting shaft is then achieved through the rack and gear, improving the controllability and transmission stability of the torsion shear loading process. At the same time, the two detection functions of pulling and torsion shearing are integrated into the same cylinder. The sensors are coaxially nested and reuse the same transmission shaft system, which significantly reduces redundant mechanisms and external components, making the whole machine more compact, smaller in size, lighter in weight, and more portable. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention; Figure 2 This is a schematic diagram of the CC cross-sectional structure of the present invention; Figure 3 This is a front view structural diagram of the present invention; Figure 4 This is a schematic diagram of the BB cross-sectional structure of the present invention; Figure 5 This is a schematic diagram of the AA cross-sectional structure of the present invention.

[0028] In the diagram: 1. Top cover, 2. Display screen, 3. Cylinder body, 4. Base, 5. Pull-out electric push rod, 6. Lever, 7. Lower connecting shaft, 8. Lower clamp, 9. Upper clamp, 10. Upper connecting shaft, 11. Tension sensor, 12. Torque shear electric push rod, 13. Guide frame, 14. Rack shaft, 15. Rack, 16. Gear, 17. Torque sensor, 18. Lower bushing, 19. Guide groove, 20. Upper bushing, 21. Grooved flange. Detailed Implementation

[0029] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Example

[0030] Please see Figure 1-5 This invention provides a technical solution: an asphalt pavement interlayer pull-out shear tester and testing method, comprising an upper cover 1, a display screen 2, a cylinder 3, a base 4, a pull-out electric push rod 5, a lever 6, a lower connecting shaft 7, a lower clamp 8, an upper clamp 9, an upper connecting shaft 10, a tension sensor 11, a torque shear electric push rod 12, a guide frame 13, a rack shaft 14, a rack 15, a gear 16, a torque sensor 17, a lower bushing 18, a guide groove 19, an upper bushing 20, and a grooved flange 21; the cylinder... 3 is set on the base 4, and the upper cover 1 is set above the cylinder 3 to form a closed or semi-closed installation space; the upper clamp 9 and the lower clamp 8 are set inside the cylinder 3, and a clamping space for clamping interlayer specimens is formed between the upper clamp 9 and the lower clamp 8. The upper clamp 9 is used to fix and clamp the upper end of the interlayer specimen, and the lower clamp 8 is used to clamp the lower end of the interlayer specimen. In this embodiment, the clamps can directly adopt the existing universal clamp structure of the pull-out instrument, so as to facilitate quick clamping on the engineering site and be compatible with existing specimen specifications.

[0031] The pull-out loading mechanism is used to drive the lower clamp 8 to generate a pull-out displacement relative to the upper clamp 9 along the axial direction; the lower clamp 8 is connected to the lower connecting shaft 7 in a transmission manner; the pull-out loading mechanism includes a pull-out electric push rod 5 and a lever mechanism 6. The lever 6 is set in the base 4 and is hinged to the lower end of the cylinder 3 to form a fulcrum and play the role of transmitting force and changing the lever arm; the upper end of the pull-out electric push rod 5 is hinged to the upper end of the cylinder 3, the telescopic end of the pull-out electric push rod 5 is hinged to one end of the lever 6, and the other end of the lever 6 is hinged to the lower connecting shaft 7; when the pull-out electric push rod 5 extends or retracts, it drives the lever 6 to rotate around the fulcrum, thereby driving the lower connecting shaft 7 to make a short-stroke reciprocating movement along the axial direction, and then driving the lower clamp 8 to apply an axial pull-out load to the interlayer specimen held in the clamp.

[0032] In this embodiment, to ensure measurement accuracy and loading stability, the following selection scheme can be preferred for key components: the tension sensor adopts an S-beam structure with a range of 0 to 10 kN and an accuracy of ±0.5% of full scale; the torque sensor adopts a strain gauge structure with a range of 0 to 500 N·m and an overload capacity of 150%; the electric actuator adopts an industrial-grade 24V slow-speed high-thrust actuator with a rated tension of 5000 N, an actuator extension speed of 10 mm per second, a pulling stroke of 100 mm, a torsion-shear stroke of 50 mm, and works in conjunction with an inverter to achieve precise control of loading speed and displacement stroke.

[0033] The torsion shear loading mechanism is used to drive the lower connecting shaft 7 to rotate around its axis, thereby realizing relative torsional shear loading between the upper clamp 9 and the lower clamp 8. The torsion shear loading mechanism includes a torsion shear electric push rod 12, a reversing mechanism that is driven by the torsion shear electric push rod 12, a rack shaft 14 that is linked with the reversing mechanism, a rack 15 set on the rack shaft 14, and a gear 16 that meshes with the rack 15. Specifically, the reversing mechanism preferably adopts a structure in which a guide frame 13 and a guide groove 19 cooperate with a roller. The guide frame 13 passes through the lower end of the cylinder body 3, and a guide groove 19 is opened on the guide frame 13. A roller is set in the guide groove 19, and one end of the roller is connected to the rack 15. The upper end of the guide frame 13 is connected to the output end of the torsion shear electric push rod 12 through a pin. When the torsion shear electric push rod 12 makes linear reciprocating motion, it drives the guide frame 13 to move relative to it, so that the roller generates a predetermined trajectory displacement under the constraint of the guide groove 19, thereby loading the torsion shear electric push rod 12. The vertical linear reciprocating motion of the push rod 12 is converted into the horizontal lateral reciprocating motion of the rack shaft 14, which drives the rack 15 to reciprocate linearly and drives the gear 16 to rotate. The gear 16 is connected to the lower connecting shaft 7 to drive the lower connecting shaft 7 to rotate, which in turn drives the lower clamp 8 to twist relative to the upper clamp 9, thereby realizing the torsional shear failure loading on the interlayer specimen. As a preferred structure, the rack shaft 14 is set at the bottom of the cylinder 3, with its axis arranged in the horizontal direction and perpendicular to the axis of the gear 16, so that the rack 15 can reliably mesh with the gear 16. The two ends of the rack shaft 14 are supported on the cylinder 3 by guide supports, so that the rack shaft 14 reciprocates in a predetermined direction within the cylinder 3 and maintains a stable posture and a basically constant meshing gap with the gear 16. Limiting structures are set at both ends of the rack shaft 14 in the direction of movement within the cylinder 3 to limit the reciprocating range of the rack shaft 14 and avoid disengagement or interference.

[0034] To balance the axial movement of the lower connecting shaft 7 in pull-out mode and the circumferential torque transmission in torsion-shear mode, the lower connecting shaft 7 is slidably connected to the gear 16 via a sliding key. This allows for relative axial sliding while transmitting torque, satisfying both circumferential rotational displacement and vertical displacement. Since specimens in interlaminar bonding performance tests typically fracture under small axial separation displacement and small relative reversal angular displacement, this device only needs to drive the lower connecting shaft 7 to achieve a short-stroke axial movement in pull-out mode to complete the entire process from loading to failure. Similarly, in torsion-shear mode, it only needs to drive the lower connecting shaft 7 to achieve relative rotation within a small rotational range to complete torsion-shear failure. Based on this characteristic, the rotational and movement ranges of the lower connecting shaft 7 are relatively small. The allowable movement of the lower connecting shaft 7's hinged structure can cover the required rotational range for the test, achieving attitude self-adaptation and micro-angle compensation during loading. This ensures stable force transmission while reducing the complexity of the mechanism and minimizing the impact of additional lateral forces or bending moments on the test data.

[0035] The sensing components are used to collect tensile loads and torsional shear torques and cooperate with the control system to achieve synchronous recording. The sensing components include a tensile sensor 11 and a torsional sensor 17. The upper clamp 9 is connected to an upper connecting shaft 10, which is connected to the upper end of the cylinder 3 through the tensile sensor 11. The upper clamp 9 is connected to the tensile sensor 11 through the upper connecting shaft 10 to collect the tensile load. The torsional sensor 17 is coaxially arranged with the upper connecting shaft 10, and the upper end of the torsional sensor 17 is fixedly connected to the upper end of the cylinder 3. The torsional sensor 17 is used to collect torsional shear torque. In order to balance axial force transmission and circumferential torsion transmission and achieve a compact arrangement, the upper connecting shaft 10 is connected to the upper bushing 20 in the vertical direction through a sliding key. The upper bushing 20 is connected to the grooved flange 21 through a keyway. The grooved flange 21 is fixedly connected to the torsional sensor 17 by bolts, so that the upper connecting shaft 10 can move upward to transmit the tensile force and transmit the torque in the circumferential direction, which meets the requirements of tensile and torsional tests.

[0036] Furthermore, the sensing component also includes a displacement acquisition component, which includes at least one of an axial displacement sensor and an angular displacement sensor; the axial displacement sensor is fixedly mounted on the cylinder body 3 and / or the base 4, and its measuring end is connected to or abuts against the lower connecting shaft 7 and / or the lower clamp 8, for acquiring the axial displacement of the lower clamp 8 relative to the upper clamp 9; the angular displacement sensor is located at the end of the lower connecting shaft 7 and / or at the gear 16 that is linked with the lower connecting shaft 7, for acquiring the torsional shear angular displacement of the lower clamp 8 relative to the upper clamp 9; the tension sensor 11, the torque sensor 17 and the displacement acquisition component are electrically connected to the control system respectively.

[0037] The control system includes a data acquisition card and a strain analysis module. The data acquisition card is electrically connected to the tensile sensor 11, the torque sensor 17, and the displacement acquisition component to synchronously acquire data, and can perform time alignment between load data and displacement or rotational data. The strain analysis module is used to output interlayer bonding performance evaluation results based on the synchronously acquired load data and displacement or rotational data, such as calculating interlayer bonding strength, bonding strength modulus, and / or strain energy index, and generating corresponding evaluation conclusions. The display screen 2 is installed on the cylinder body 3 and electrically connected to the control system to display pull-out force, torque, and test results, and can display curve data or report key information.

[0038] The testing method of this device can be implemented according to the following procedure: First, prepare the interlaminar specimen and clamp it between the upper clamp 9 and the lower clamp 8; then, set the specimen size parameters and loading parameters through the control system, and select the pull-out test mode or the torsion-shear test mode; in the pull-out test mode, control the extension and retraction of the pull-out electric push rod 5 and drive the lower connecting shaft 7 to move axially through the lever 6 to apply a pull-out load to the interlaminar specimen, and simultaneously collect the load data of the tension sensor 11 and the displacement data of the axial displacement sensor; in the torsion-shear test mode, control the torsion-shear electric push rod 12 to drive the rack shaft 14 to move the rack 15 through the reversing mechanism, so that the rack 15 drives the gear 16 to rotate and drive the lower connecting shaft 7 to rotate, applying a torsion-shear load to the interlaminar specimen, and simultaneously collect the torque data of the torque sensor 17 and the rotation angle data of the angular displacement sensor; finally, the control system records and processes the collected data and outputs the interlaminar bonding performance evaluation results, and generates a test report when necessary and displays it on the display screen 2.

[0039] In addition to the guide groove and roller structure mentioned above, the reversing mechanism can also adopt the form of crank rocker mechanism, hinge lever reversing mechanism, etc., as long as it can convert linear or reciprocating motion into oscillation or lateral displacement to drive rack shaft 14 to reciprocate motion.

[0040] In this embodiment, the equivalent force arm of the torsional shear strength can be the distance from the point of force application of the clamp 8 to the specimen to the axis of the lower connecting shaft 7 or the effective radius of the lower clamp 8, and the maximum torque measured by the torque sensor 17 can be converted into the equivalent shear strength accordingly. The two ends of the rack shaft 14 are supported by guide supports, which can be linear guide rails and sliders or guide shafts and sliding sleeves, to ensure that the rack shaft 14 moves back and forth in a predetermined direction and the meshing gap with the gear 16 is basically constant. The two ends of the rack shaft 14 are also provided with limit structures, which can be blocks or limit screws, to limit the reciprocating range of the rack shaft 14 and prevent the rack 15 and the gear 16 from disengaging or interfering.

[0041] Furthermore, to facilitate direct implementation of the present invention by those skilled in the art and to obtain stable and repeatable test results, the tension sensor, torque sensor, and displacement acquisition component can be zeroed before testing under no-load conditions. Subsequently, the data acquisition card synchronously acquires the signals from each sensor and generates curves. The sampling frequency of the data acquisition card can be set to 100 to 1000 times per second, preferably 200 to 500 times per second, and a single clock trigger is used to achieve synchronous acquisition of tension signals, torque signals, and vertical displacement or rotation signals. Before loading, the initial values ​​of each sensor can be recorded as zero points. During loading, the real-time measured values ​​are subtracted from the zero points to eliminate initial bias. In the pull-out test mode, the electric pull rod is loaded at a constant speed along the vertical direction. The angle can be set from 0.5 mm to 20 mm per second, preferably from 5 mm to 12 mm per second. The upper limit of vertical displacement can be set from 0.5 mm to 10 mm, preferably from 3 mm to 6 mm. When the vertical displacement reaches the upper limit or the specimen shows obvious damage, the loading is stopped and the tensile force and vertical displacement data of the whole process are recorded. In the torsion shear test mode, the torsion shear electric push rod loads at a constant speed. The lower connecting shaft is continuously rotated through the rack and gear transmission and shearing action is applied to the specimen. The rotation angle loading speed can be set from 0.1 degree to 10 degrees per second, preferably from 0.5 degrees to 3 degrees per second. The upper limit of rotation angle can be set from 0.5 degrees to 15 degrees, preferably from 8 degrees to 12 degrees. When the rotation angle reaches the upper limit or the specimen shows obvious damage, the loading is stopped and the torque and rotation angle data of the whole process are recorded.

[0042] After the test, the control system processes the collected data and provides evaluation results. The interlayer bond strength can be taken as the maximum tensile force recorded during the test as the pull-out strength evaluation value, and the maximum tensile force is divided by the stress area of ​​the specimen to obtain the strength result. The torsional shear strength can be taken as the maximum torque recorded during the test as the torsional shear strength evaluation value, and the strength result is obtained by combining the stress area of ​​the specimen or the equivalent force arm. The bond strength modulus can be determined according to the upward trend of the tensile force versus vertical displacement curve in the initial stage. It is preferred to select the data from 10% to 40% of the peak value of the tensile force for linear fitting, and obtain the upward slope as the modulus or stiffness characterization index. The strain energy index can be obtained by accumulating the curve of the entire loading process. It is preferred to use numerical integration to accumulate the area of ​​the tensile force versus vertical displacement curve from zero to the failure point, or to accumulate the area of ​​the torque versus rotation curve from zero to the failure point, to characterize the amount of energy absorbed by the specimen before failure. The control system can summarize the curves, peak load or peak torque, strength results, modulus index, and energy index, and generate a test report for display or storage.

[0043] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. An interlayer pull-out shearing device for asphalt pavement, comprising a cylinder (3), an upper clamp (9), a lower clamp (8), a lower connecting shaft (7), a pull-out loading mechanism, a torsion shear loading mechanism, a sensing component, and a control system, characterized in that: The upper clamp (9) and the lower clamp (8) are set vertically in the cylinder (3), forming a clamping space between the upper clamp (9) and the lower clamp (8) for clamping interlayer specimens. The lower clamp (8) is driven to the lower connecting shaft (7). The pull-out loading mechanism includes a pull-out electric push rod (5) and a lever mechanism (6) driven to the pull-out electric push rod (5). The pull-out electric push rod (5) extends and retracts to drive the lever mechanism (6) to rotate, thereby driving the lower connecting shaft (7) to move axially. The torsion shear loading mechanism includes a torsion shear electric push rod (12), a reversing mechanism driven to the torsion shear electric push rod (12), a rack shaft (14) linked to the reversing mechanism (13), and a rack. The rack (15) on the shaft (14) and the gear (16) meshing with the rack (15) are connected to the lower connecting shaft (7) to drive the lower connecting shaft (7) to rotate. The sensing components include a tension sensor (11) and a torque sensor (17). The upper clamp (9) is connected to the upper connecting shaft (10). The upper connecting shaft (10) is connected to the upper end of the cylinder (3) through the tension sensor (11). The torque sensor (17) is coaxially arranged with the upper connecting shaft (10), and the upper end of the torque sensor (17) is fixedly connected to the upper end of the cylinder (3). The torque sensor (17) and the tension sensor (11) are electrically connected to the control system respectively.

2. The asphalt pavement interlayer pull-out shearing apparatus according to claim 1, characterized in that: A top cover (1) is provided on the top of the cylinder (3). The cylinder (3) is set on the base (4). The lever (6) is set in the base (4). The upper end of the pull electric push rod (5) is hinged to the upper end of the cylinder (3). The telescopic end of the pull electric push rod (5) is hinged to one end of the lever (6). The other end of the lever (6) is hinged to the lower connecting shaft (7). A display screen (2) is provided on the cylinder (3). The display screen (2) is electrically connected to the control system.

3. The asphalt pavement interlayer pull-out shearing apparatus according to claim 1, characterized in that: The tension sensor (11) and the torque sensor (17) are arranged coaxially and positioned above the upper clamp (9). The upper connecting shaft (10) is connected to the upper bushing (20) in the vertical direction via a sliding key. The upper bushing (20) is connected to the grooved flange (21) via a keyway. The grooved flange (21) is fixedly connected to the torque sensor (17) by bolts.

4. An asphalt pavement interlayer pull-out shear apparatus according to any one of claims 1-3, characterized in that: The lower connecting shaft (7) is slidably connected to the gear (16) via a sliding key. The reversing mechanism includes a guide frame (13), a guide groove (19) is provided on the guide frame (13), a roller is provided in the guide groove (19), one end of the roller is connected to the rack (15), and the torsion shear electric push rod (12) drives the roller assembly to move under the constraint of the guide groove (19) so as to convert the vertical linear reciprocating motion of the torsion shear electric push rod (12) into the horizontal lateral reciprocating motion of the rack shaft (14); the guide frame (13) passes through the lower end of the cylinder (3), and the upper end of the guide frame (13) is connected to the output end of the torsion shear electric push rod (12) via a pin.

5. An asphalt pavement interlayer pull-out shear apparatus according to any one of claims 1-4, characterized in that: The sensing assembly also includes at least one of an axial displacement sensor and an angular displacement sensor; wherein the axial displacement sensor is fixedly mounted on the cylinder (3) and / or the base (4), and its measuring end is connected to or abuts against the lower connecting shaft (7) and / or the lower clamp (8) to collect the axial displacement of the lower clamp (8) relative to the upper clamp (9); the angular displacement sensor is located at the end of the lower connecting shaft (7) and / or at the gear (16) that is linked with the lower connecting shaft (7).

6. A test method for interlayer pull-out shear test of asphalt pavement, characterized in that, The asphalt pavement interlayer pull-out shear apparatus according to any one of claims 1 to 5 includes the following steps: S1. Prepare interlayer specimens and clamp them between the upper clamp (9) and the lower clamp (8); S2. Set the specimen size parameters and loading parameters through the control system, and select the pull-out test mode or the torsion-shear test mode; S3. When the pull-out test mode is selected, the pull-out electric push rod (5) is controlled to extend and retract and drive the lower connecting shaft (7) to move axially via the lever mechanism (6), so that the lower clamp (8) generates a pull-out displacement relative to the upper clamp (9) and applies a pull-out load to the interlayer specimen; at the same time, the pull-out load data output by the tension sensor (11) and the displacement data output by the axial displacement sensor are collected. S4. When the torsion shear test mode is selected, the control torsion shear electric push rod (12) drives the rack shaft (14) through the reversing mechanism (13) to drive the rack (15) to move, so that the rack (15) drives the gear (16) to rotate and drives the lower connecting shaft (7) to rotate, so that the lower clamp (8) generates torsion shear relative rotation with respect to the upper clamp (9), and applies torsion shear load to the interlayer specimen; at the same time, the torque data output by the torque sensor (17) and the rotation angle data output by the angular displacement sensor are collected. S5. The control system records and processes the collected data and outputs the evaluation results of interlayer bonding performance.

7. The method according to claim 6, characterized in that, The control system synchronously samples the tension sensor (11), torque sensor (17) and displacement acquisition component through the data acquisition card, and performs time alignment between the load data and the displacement / rotation angle data to obtain the pull-out load-displacement curve and / or torque-rotation angle curve.

8. The method according to claim 6 or 7, characterized in that, In the pull-out test mode, the loading is completed within the preset axial displacement limit before the interlayer specimen breaks. In the torsion-shear test mode, the loading is completed within the preset reversal angle limit before the interlayer specimen breaks, so that the axial movement range and rotation range of the lower connecting shaft (7) are both small.

9. The method according to claim 6, characterized in that, The strain analysis module in the control system calculates interlayer bond strength, bond strength modulus and / or strain energy index based on the collected load data and displacement / rotation data, and generates corresponding evaluation conclusions.

10. The method according to claim 6, characterized in that, The control system generates a test report from the test process data and evaluation conclusions, and displays the pull-out force, torque, curve data and / or test results on the display screen (2); the control system can be connected to a computer through an external interface to export the test data.

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