A pavement interlayer shear scaling simulation device

Abstract

The present invention relates to a pavement interlayer shear scale simulation device, which includes a support platform and a mechanical body, wherein the mechanical body includes a shear box for carrying a test piece, a normal stress loading unit for simulating the pressure contact state between a vehicle tire and a pavement, a horizontal tension and pressure control unit for simulating the application of shear force, and a displacement measurement unit for measuring shear test data, wherein the shear box includes an upper shear box and a lower shear box which are stacked and respectively carry a surface layer test piece and a base layer test piece, wherein the lower shear box is fixed on the support platform, the normal stress loading unit is arranged above the upper shear box and acts vertically on the upper surface of the surface layer test piece, and the horizontal tension and pressure control unit and the displacement measurement unit are respectively arranged on two opposite sides of the upper shear box and are both connected to the upper shear box. Compared with the prior art, the present invention can realize comprehensive, efficient and accurate measurement of the shear resistance performance between pavement layers, so as to facilitate the refinement and scientificization of indoor tests and on-site pavement detection.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, and in particular to a pavement interlayer shear scaling simulation device. Background Art

[0002] Asphalt pavement is the main form of highway pavement in my country. In recent years, with the increase of traffic volume and serious overloading, asphalt pavement has frequently suffered early damage. The later core drilling results show that the bonding effect between the surface layer and the base layer of a considerable part of the asphalt pavement is poor, and the overall shear resistance of the pavement structure is insufficient, which is the direct cause of the pavement damage. The interlayer bonding state of asphalt pavement plays an important role in the stability and durability of the entire pavement structure, so it is necessary to study the interlayer shear strength of asphalt pavement.

[0003] At present, the methods for evaluating interlayer shear strength are mainly based on direct shear test and oblique shear test. In oblique shear test, the surface layer and base layer are placed in the test mold, and normal stress is applied to the top of the test mold, so that it is decomposed into normal stress and shear stress on the shear plane with a certain angle, so that the specimen is sheared. Although the oblique shear test can simulate the interface shear state well, there are problems such as large specimen size and fixed shear angle. The test results obtained cannot well reflect the bonding performance of the bonding layer itself. The direct shear test is based on the Mohr-Coulomb strength theory. Under different normal stresses, horizontal shear force is applied to the specimen along the fixed shear plane, and the maximum shear stress when the specimen is destroyed is taken as the shear strength of the specimen. As an important test for evaluating the interface friction shear strength in the field of highway geotechnical testing, the direct shear test is widely used because of its simple operation, strong adaptability, and short test time.

[0004] Existing direct shear methods mainly include horizontal direct shear and vertical direct shear. The vertical direct shear is mainly carried out by placing the target specimen horizontally and then applying normal stress to the side part of the upper surface layer. Although this method can conveniently perform shear operations, it does not take into account the pressurization effect of vehicle loads under actual conditions. The shear state of the specimen is overly simplified, resulting in inaccurate test results. Invention patent CN106596292A discloses a pavement material interlayer shear test device, and invention patent CN110542618A discloses a direct shear test method for the interlayer shear strength of an emulsified asphalt surface treatment layer. Both use a vertical direct shear method. The use of horizontal direct shear can avoid the above problems. The test device pushes and pulls the shear box under vertical pressure, which is also in line with the actual shear direction and stress state of the asphalt pavement. The shear data is recorded by a horizontal displacement sensor and a tension sensor to obtain the maximum shear stress. The test operation is simple. Therefore, it is necessary to invent a horizontal direct shear device between pavement material layers.

[0005] However, the existing horizontal direct shear devices in China are still upgraded and reconstructed based on the traditional geotechnical direct shear apparatus, and there are the following problems:

[0006] 1) The pressure and contact method are not realistic

[0007] At present, the vertical pressure loading method of the direct shear device is mainly to perform single-point reaction force pressurization through the lever principle, etc. The pressure point is single and cannot simulate the effects of the front and rear axles of the vehicle load; and most of the existing direct shear devices perform single-point concentrated pressurization of the vertical stress, which has certain constraints and cannot simulate the pressure action mode between the vehicle tire and the road surface material.

[0008] 2) The shear simulation effect is not good

[0009] When an asphalt pavement is subjected to shear force, the force should first act on the surface material, and then the shear resistance of the interlayer material should resist the shear force. The current test method is mainly to obtain the interlayer shear stress by pulling and pushing the base part of the specimen. Therefore, the maximum shear stress data obtained also have a certain error with the shear fatigue performance.

[0010] 3) Lack of shear fatigue test function

[0011] The existing direct shear test device can only apply unidirectional horizontal shear force, and thus can only measure the maximum shear stress data, but cannot test the shear fatigue performance of the pavement interlayer material under the overlying load.

[0012] 4) The effect of device scaling did not meet expectations

[0013] The existing interlayer shear device still needs to be improved in simulating the interlayer shear mode and shear fatigue performance of the pavement. It does not take into account the specimen size, load loading size, loading mode and other aspects, and focuses more on the shear performance of the interlayer material itself. However, the measurement of the shear performance of the interlayer material in the pavement structure still needs to be improved. Summary of the invention

[0014] The purpose of the present invention is to provide a pavement interlayer shear scaling simulation device in order to overcome the defects of the above-mentioned prior art.

[0015] The purpose of the present invention can be achieved by the following technical solutions:

[0016] A pavement interlayer shear scale simulation device, the device includes a support platform and a mechanical body arranged on the support platform, the mechanical body includes a shear box for carrying a test piece, a normal stress loading unit for simulating the pressure contact state between a vehicle tire and a road surface, a horizontal tension and pressure control unit for simulating the application of shear force, and a displacement measuring unit for measuring shear test data, the shear box includes an upper shear box and a lower shear box which are stacked and respectively carry a surface layer test piece and a base layer test piece, the lower shear box is fixed on the support platform, the normal stress loading unit is arranged above the upper shear box and acts vertically on the upper surface of the surface layer test piece, the horizontal tension and pressure control unit and the displacement measuring unit are respectively arranged on two opposite sides of the upper shear box and are both connected to the upper shear box.

[0017] Preferably, the normal stress loading unit includes a reaction mechanism, a jack assembly, a magnetic plate, a force transmission plate and a force transmission wheel assembly. The jack assembly is fixed to the force transmission plate through the magnetic plate, the top of the jack is fixed to the support platform through the reaction mechanism, and the force transmission wheel assembly is arranged at the bottom of the force transmission plate.

[0018] Preferably, the jack assemblies are arranged in two groups, and the two groups of jack assemblies are arranged in sequence along the shear force transmission direction. Each group of jack assemblies is fixed to the support platform through a reaction mechanism. Correspondingly, the force transmission wheel assemblies are arranged in two groups, which are respectively arranged at the position below the two groups of jack assemblies.

[0019] Preferably, the jack assembly comprises a jack, a vertical pressure sensor and a centering device, a vertical pressure sensor is arranged at the bottom of the jack and is connected to the centering device, and the centering device is mounted on the magnetic plate.

[0020] Preferably, the reaction mechanism includes a portal-type reaction frame, which includes a horizontal reaction rod and two vertical support rods. The horizontal reaction rod is installed above the jack assembly, and the two ends of the horizontal reaction rod are respectively supported and fixed by a vertical support rod. The bottom of the vertical support rod is anchored to the support platform. A circular groove is provided at the center line of the horizontal reaction rod, and the circular groove is used to be fixed with the top of the jack assembly to form a reaction loading point.

[0021] Preferably, the force transmission wheel assembly includes force transmission wheels for simulating wheels on both sides of the vehicle, the force transmission wheels are hingedly connected to the force transmission plate through a triangular wheel axle, the force transmission wheel includes a steel wheel hub and a rubber tire rim, and the steel wheel hub and the rubber tire rim are tightly attached.

[0022] Preferably, the front and rear ends of the upper shear box are respectively provided with a front end protrusion and a rear end protrusion connected to the horizontal tension and pressure control unit and the displacement measuring unit, the front end protrusion is provided with an external thread for connecting to the horizontal tension and pressure control unit, and the rear end protrusion is provided with a circular groove for connecting to the displacement measuring unit.

[0023] Preferably, the horizontal tension and pressure control unit includes a tension press, a connecting piece and a tension and pressure sensor, the front end of the connecting piece is connected to the tension press, the end of the connecting piece is provided with a circular groove and is adapted to the sensing front end of the tension and pressure sensor, the rear end of the tension and pressure sensor is provided with a circular groove, and the circular groove is provided with an internal thread adapted to the external thread of the front end protrusion of the upper shear box.

[0024] Preferably, the displacement measuring unit comprises a linear displacement sensor, a dial indicator, a 360° rotatable holding mechanism and a fixing rod; the linear displacement sensor and the dial indicator are both fixed on the 360° rotatable holding mechanism; the linear displacement sensor and the tip of the dial indicator are adapted to the circular groove on the rear end convex part of the shear box; and the 360° rotatable holding mechanism is fixed on the supporting platform via a fixing rod.

[0025] Preferably, the drawing press comprises a continuously variable speed drawing press.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The pavement interlayer shear scale simulation device provided by the present invention simulates the loading mode and constraint conditions under the real wheel-pavement coupling effect, and can not only measure the maximum shear stress of the interlayer material, but also measure the shear fatigue performance of the pavement interlayer, thereby achieving comprehensive, efficient and accurate measurement of the pavement interlayer shear performance, so as to facilitate indoor testing and on-site pavement testing;

[0028] (2) The present invention realizes free contact between tires and the road surface through two sets of front and rear force transmission wheel assemblies, eliminating the constraints of traditional devices. By reducing the tire scale, the actual pressure contact state between the tire load and the road surface is better simulated, and the load distribution of the front and rear axles is controlled by two sets of jacks and pressure sensors, which can accurately meet the actual stress state of the road surface. In addition, the setting of the force transmission wheel can also simulate the active fatigue shearing effect of the vehicle tire by pushing and pulling the upper shear box, realizing the effective interchange of the reference system, which meets the actual shearing mode of the road surface structure.

[0029] (3) The present invention can realize the conversion of displacement measurement mode (linear displacement sensor measurement mode, dial indicator measurement mode) by setting a 360° rotatable holding mechanism, thereby avoiding the error caused by a single measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of a pavement interlayer shear scaling simulation device of the present invention.

[0031] Figure 2 yes Figure 1 Schematic diagram of the main device structure.

[0032] Figure 3 It is a structural schematic diagram of the normal stress loading unit in the present invention.

[0033] Figure 4 It is a structural schematic diagram of the shear box in the present invention.

[0034] Figure 5 It is a force schematic diagram of the direct shear specimen of the present invention.

[0035] In the figure: 1 is a support frame; 2 is a test platform; 3 is a continuously variable speed pulling press; 4-1 is a first vertical support rod; 4-2 is a second vertical support rod; 5-1 is the first welding end; 5-2 is the second welding end; 6-1 is the first anchoring end; 6-2 is the second anchoring end; 7 is a connecting piece; 8 is a tension pressure sensor; 9 is a front end protrusion; 10 is an upper shear box; 11 is a lower shear box; 12-1 is a first jack; 12-2 is a second jack; 13-1 is a first vertical pressure sensor; 13-2 is a second vertical pressure sensor; 14-1 is a first centering device; 14-2 is a second centering device; 15 is a magnetic plate; 16 is a force transmission plate; 17 is a force transmission wheel assembly; 18 is a linear displacement sensor; 19 is a dial indicator; 20 is a 360° rotatable supporting mechanism; 21 is a brake bolt; 22 is a fixing rod; 23 is a rear end protrusion; 24 is a computer; 25 is a first horizontal reaction rod; 26 is a wheel axle; 27 is a force transmission wheel; 28 is a U-shaped steel; 29 is a bolt and nut assembly. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the following embodiments are merely illustrative in nature, and the present invention is not intended to limit its applicable objects or uses, and the present invention is not limited to the following embodiments.

[0037] Example

[0038] like Figures 1 to 4 As shown, this embodiment provides a pavement interlayer shear scale simulation device, which includes a support platform and a mechanical body arranged on the support platform, and the support platform includes a support frame 1 and a test platform 2. The mechanical body includes a shear box for carrying a test piece, a normal stress loading unit for simulating the pressure contact state between a vehicle tire and a pavement, a horizontal tension and pressure control unit for simulating the application of shear force, and a displacement measurement unit for measuring shear test data.

[0039] The horizontal tension and pressure control unit includes a continuously variable tension and pressure machine 3, a connecting piece 7 and a tension and pressure sensor 8, the normal stress loading unit includes a reaction mechanism, a first jack 12-1, a second jack 12-2, a first vertical pressure sensor 13-1, a second vertical pressure sensor 13-2, a first centering device 14-1, a second centering device 14-2, a magnetic plate 15, a force transmission plate 16 and a force transmission wheel assembly 17, the shear box includes an upper shear box 10 and a lower shear box 11, and the displacement measuring device includes a linear displacement sensor 18, a dial indicator 19, a 360° rotatable holding mechanism 20 and a fixing rod 22. The support platform includes a support frame 1 and a test platform 2.

[0040] The stepless speed pulling press 3 is loaded by Japanese Panasonic servo motor, and its technical parameters are as follows. Maximum shear load: 2.0×10 5 kN; shear load resolution: 1N; shear load resolution accuracy: better than ±0.5%; shear loading rate: 0-100mm / min adjustable; shear loading rate control accuracy: 0.5%; shear displacement measurement range: 0-150mm; shear displacement measurement resolution: 0.01mm; shear displacement measurement accuracy: ±0.5%. The shear rate and its accuracy are achieved through variable frequency speed regulation technology under PLC control, and unidirectional shear force can be applied by inputting direct current or bidirectional fatigue shear force by inputting sinusoidal current.

[0041] The reaction mechanism is divided into a first reaction mechanism and a second reaction mechanism according to the distance from the continuously variable speed pulling press 3. The structures and functions of the two reaction mechanisms are exactly the same, and both include a reaction frame and an anchor end. The first reaction mechanism is used as an example for explanation. The reaction frame includes a first horizontal reaction rod 25 and a first vertical support rod 4-1, and the two rods are internally welded to form a first welding end 5-1 with a fixed 90° angle. Preferably, the first welding end 5-1 is formed into a rectangular block by casting, physical grinding, etc., and the rectangular block has two perpendicular round ends to protect the test personnel; preferably, a circular groove is provided at the center line of the first horizontal reaction rod 25, which is used as the reaction force loading point of the first jack 12-1; the first anchor end 6-1 is composed of a left-right symmetrical U-shaped steel 28 and a bolt and nut assembly 29, preferably, the upper and lower parts of the U-shaped steel 28 each contain a large circular hole and four small circular holes, and the circular holes of the upper and lower parts are vertically aligned; the first vertical support rod passes through the upper and lower large circular holes of the U-shaped steel, and the bolt and nut assembly 29 passes through the upper and lower small circular holes of the U-shaped steel, and is tightened at the bottom to ensure the structural strength of the first vertical support rod 4-1. The second reaction mechanism is the same as the first reaction mechanism.

[0042] A circular shallow groove is provided at the end of the connector 7, and is adapted to the sensing front end of the tension and pressure sensor 8. The two are fixedly connected by embedding to ensure effective shear force transmission; a circular groove is also provided at the rear end of the tension and pressure sensor 8, and a thread is provided in the groove. Preferably, the tension and pressure sensor 8 in this embodiment adopts a resistance strain diaphragm pressure sensor.

[0043] The upper shear box 10 is provided with through holes at the top and bottom, and is provided with a front end protrusion 9 and a rear end protrusion 23 on the side; the front end protrusion 9 is cylindrical, and its surface is also provided with a thread adapted to the rear end groove of the above-mentioned tension and pressure sensor 8; the rear end protrusion 23 is cylindrical, with a smooth surface, and a circular groove on the bottom; the front end protrusion 9 is screwed and connected with the tension and pressure sensor 8 by a thread to fix the position of the applied shear force. Preferably, the physical parameters of the upper shear box 10 are as follows. According to the principle of geometric similarity, the internal geometric dimensions are determined as follows: 150mm×150mm×40mm; the external (excluding the front and rear end protrusions) geometric dimensions are: 200mm×200mm×45mm. The lower shear box 11 is open at the top, and the bottom surface is a rectangular steel sheet, which cooperates with the upper shear box 10; the lower shear box 11 is embedded with the test platform 2, and remains stationary during the test to ensure that the measured relative displacement data is effective and accurate. Preferably, the physical parameters of the lower shear box 11 are as follows. According to the principle of geometric similarity, the internal geometric dimensions are determined as: 150mm×150mm×90mm; the external geometric dimensions are: 200mm×200mm×100mm.

[0044] The technical parameters of the first jack 12-1 and the second jack 12-2 are as follows: Maximum vertical load: 1.0×10 5 kN; vertical load resolution: 1N; vertical load resolution accuracy: better than ±0.5%. The first jack 12-1 and the second jack 12-2 are placed on the first vertical pressure sensor 13-1 and the second vertical pressure sensor 13-2, respectively, and the first vertical pressure sensor 13-1 and the second vertical pressure sensor 13-2 are placed on the first centering device 14-1 and the second centering device 14-2, respectively. And the center lines of the first jack 12-1, the first vertical pressure sensor 13-1 and the first centering device 14-1 coincide; the center lines of the second jack 12-2, the second vertical pressure sensor 13-2 and the second centering device 14-2 coincide. The first centering device 14-1 and the second centering device 14-2 are placed in two limit card slots at the geometric center of the magnetic suction plate 15, and the internal dimensions of the limit card slots are adapted to the sizes of the first centering device 14-1 and the second centering device 14-2. The magnetic plate 15 is tightly connected to the underlying force transmission plate 16 by magnetic attraction to redistribute the upper vertical load. Preferably, in this embodiment, both the first vertical pressure sensor 13-1 and the second vertical pressure sensor 13-2 are resistive strain diaphragm pressure sensors.

[0045] Furthermore, the force transmission wheel assembly 17 is hingedly connected to the force transmission plate 16 through a triangular wheel axle 26, and the triangular wheel axle 26 is welded and fixed to the force transmission plate 16; the force transmission wheel assembly 17 includes two groups, front and rear, each group of force transmission wheel assemblies includes two left and right shafts, and is a single-axle double-wheel group; a single force transmission wheel 27 includes a steel wheel hub and a rubber tire rim, and the two are tightly attached. Preferably, the physical parameters of a single force transmission wheel 27 are as follows. According to the principle of physical similarity, the inner diameter d of the steel wheel hub is determined 1 =30mm, outer diameter D 1 =32mm; rubber tire rim d 2 =32mm, outer diameter D 2 =35mm, and uses steel radial tires.

[0046] Furthermore, the tips of the linear displacement sensor 18 and the dial indicator 19 fit into the circular groove in the rear end protrusion 23 and just touch the bottom of the groove, so that the shear displacement measured is more accurate; the linear displacement sensor 18 is fixed to the 360° rotatable holding mechanism 20 by two vertical bolts; the dial indicator 19 is fixed to the 360° rotatable holding mechanism 20 by a single bolt; the extended part of the 360° rotatable holding mechanism 20 contains a circular hole adapted to the above-mentioned fixed component, and the end of the 360° rotatable holding mechanism 20 is provided with a thread, and is connected to the fixed rod 22 by a brake bolt 21. The 360° rotatable holding mechanism 20 relying on the brake bolt 21 can realize the conversion between automatic displacement measurement and manual reading. The fixed rod 22 is anchored to the test platform 2, and the fixed rod 22 is kept perpendicular to the test platform 2.

[0047] In this embodiment, the linear displacement sensor 18 uses conductive plastic and a sliding brush to directly measure the displacement of the rear end protrusion 23, and flexible bearings are provided at both ends of the linear displacement sensor 18, which can play an effective buffering role and can be used for the determination of the maximum shear stress between layers and the control of the maximum displacement of shear fatigue; the dial indicator 19 is a clock-type dial indicator, which is only used for the determination of the maximum shear stress between layers, and its technical parameters are as follows. The large pointer range is 0-10mm, and the graduation value is 0.01mm; the small pointer range is 0-50mm, and the graduation value is 10mm; the total range is 0-50mm; the accuracy is better than ±0.2%.

[0048] Preferably, the front end of the test platform 2 is also provided with a storage groove that can accommodate a continuously variable speed pulling press. The storage groove is composed of rectangular plates with different heights at the front and back. The width of the storage groove is slightly larger than the width required for the normal operation of the pulling press to prevent vibration caused by unstable current from affecting the test, and a step is provided at the bottom of the storage groove to ensure that the shear force is applied to the middle of the upper shear box.

[0049] The test procedure of the present invention is as follows:

[0050] 1. Specimen preparation: The specimens were formed by rolling the wheel forming machine. According to the principle of geometric similarity, the surface specimen size was 150mm×150mm×40mm, and the base specimen size was 150mm×150mm×90mm. After the specimens were formed, the surface of the base specimens was coated with tack coat oil. The amount of tack coat oil was based on the recommended amount in the Technical Specifications for Highway Asphalt Pavement Construction, and 1.5kg / m 2 As the upper limit of the standard value. After applying the tack coat oil, let it stand for 5 minutes, then bond the bottom surface of the asphalt mixture surface layer specimen to the painted surface of the base layer specimen, and after bonding, let the specimen stand for 5 minutes to ensure the formation of the strength of the tack coat oil.

[0051] 2. Apply a proper amount of lubricating oil inside the upper shear box 10 and the lower shear box 11, then place the prepared composite specimen into the lower shear box 11, and adjust the specimen position to ensure that the side wall of the lower specimen of the tested composite specimen is in contact with the inner wall of the lower shear box 11; then place the upper shear box 10 on the lower shear box 11, and adjust the upper shear box 10 to ensure that the side wall of the upper specimen of the tested composite specimen is in contact with the inner wall of the upper shear box 10.

[0052] 3. Fix the tension pressure sensor 8, the linear displacement sensor 18 and the dial indicator 19 and make them in a free extension and retraction state.

[0053] 4. Place the normal stress loading units on the test piece in order from bottom to top, and adjust the vertical pressure sensors 13-1 and 13-2 to the test zero value, that is, the initial values ​​such as the deadweight of the lower overburden centering devices 14-1 and 14-2, the force transfer plate 16 and the force transfer wheel assembly 17 have been corrected; after the above operations are completed, the normal pressure value at the bottom of the loaded tire is controlled to be 0.7MPa, and according to the standard axle type used, the load is redistributed by adjusting the reaction force loading size of the first jack 12-1 and the second jack 12-2. According to the principle of physical similarity, the load ratio adopts the front axle: rear axle = 1:2, etc.

[0054] 5. Turn on the power supply, calibrate the initial values ​​of the tension pressure sensor 8, the linear displacement sensor 18 and the dial indicator 19 to zero, and test whether the connection between each sensor and the data acquisition computer 24 is good.

[0055] 6. After confirmation, if the maximum interlayer shear stress is to be measured, the continuously variable speed pulling press 3 should be set to a unidirectional shear stress application mode, and the shear rate required for the test should be selected, then the data acquisition computer 24 should be turned on and the continuously variable speed pulling press 3 should be started, the test should be carried out and the shear stress and displacement data should be collected; if the interlayer fatigue shear performance is to be measured, the continuously variable speed pulling press 3 should be set to a bidirectional tension and compression shear mode, that is, a sinusoidal current should be input, and the shear rate and single shear displacement limit required for the test should be set, then the data acquisition computer 24 should be turned on and the continuously variable speed pulling press 3 should be started, the test should be carried out and the shear stress, displacement and fatigue shear times and other data should be collected.

[0056] 7. After the test is completed, turn off the continuously variable speed pulling press 3 and all data acquisition devices.

[0057] The advantages of the present invention are that the device simulates the loading mode and constraint conditions under the real vehicle-road coupling, and can not only measure the maximum shear stress of the interlayer material, but also measure the shear fatigue performance of the interlayer of the road surface. The device realizes free contact between the tire and the road surface through the front and rear two sets of force transmission wheel assemblies, eliminates the constraint conditions of the traditional device, and better simulates the contact state between the real tire load and the road surface through the tire scale reduction method, and controls the load distribution of the front and rear axles through two sets of jacks and pressure sensors, which can accurately meet the axle load loading mode of the road surface in my country. In addition, the setting of the force transmission wheel can also simulate the active fatigue shearing effect of the vehicle tire by pushing and pulling the upper shear box, realizing the effective interchange of the reference system, which is in line with the actual shearing mode of the road surface. In addition, by setting a 360° rotatable support mechanism, the conversion of the displacement measurement mode can be realized, avoiding the error caused by a single measurement. Through this device, the comprehensive, efficient and accurate measurement of the shear resistance between the pavement layers can be achieved, so as to facilitate the refinement and scientificization of indoor tests and on-site road surface detection.

[0058] Figure 5 is a schematic diagram of the force of the direct shear specimen of the present invention, in which T is the shear stress applied by the horizontal tension and pressure control unit, P 11 , P 12 , P 21 , P 22 is the normal stress applied by the normal stress loading unit, where P 11 , P 12 As a group, they can be adjusted synchronously, P 21 , P 22 As a group, they can be adjusted synchronously. δ For displacement.

[0059] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention and are not intended to limit the present invention. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the above embodiments within the technical scope disclosed by the present invention, or perform equivalent replacements on some of the technical features thereof; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A pavement interlayer shear scaling simulation device, characterized in that: The device comprises a support platform and a mechanical body arranged on the support platform, wherein the mechanical body comprises a shear box for carrying a test piece, a normal stress loading unit for simulating the pressure contact state between a vehicle tire and a road surface, a horizontal tension and pressure control unit for simulating the application of shear force, and a displacement measuring unit for measuring shear test data. The shear box comprises an upper shear box (10) and a lower shear box (11) which are stacked and respectively carry a surface layer test piece and a base layer test piece, the lower shear box (11) is fixed on the support platform, the normal stress loading unit is arranged above the upper shear box (10) and acts vertically on the upper surface of the surface layer test piece, the horizontal tension and pressure control unit and the displacement measuring unit are respectively arranged on two opposite sides of the upper shear box (10) and are both connected to the upper shear box (10). The normal stress loading unit comprises a reaction mechanism, a jack assembly, a magnetic plate (15), a force transmission plate (16) and a force transmission wheel assembly (17); the jack assembly is fixed to the force transmission plate (16) via the magnetic plate (15); the top of the jack assembly is fixed to the support platform via the reaction mechanism; the force transmission wheel assembly (17) is arranged at the bottom of the force transmission plate (16); The front and rear ends of the upper shear box (10) are respectively provided with a front end protrusion (9) and a rear end protrusion connected to the horizontal tension and pressure control unit and the displacement measuring unit. The front end protrusion (9) is provided with an external thread for connecting to the horizontal tension and pressure control unit, and the rear end protrusion is provided with a circular groove for connecting to the displacement measuring unit. The displacement measuring unit comprises a linear displacement sensor (18), a dial indicator (19), a 360° rotatable holding mechanism (20) and a fixing rod (22); the linear displacement sensor (18) and the dial indicator (19) are both fixed on the 360° rotatable holding mechanism (20); the tips of the linear displacement sensor (18) and the dial indicator (19) fit into the circular groove on the rear end convex part of the shear box (10); and the 360° rotatable holding mechanism (20) is fixed on the supporting platform via the fixing rod (22).

2. A pavement interlayer shear scaling simulation device according to claim 1, characterized in that: The jack assemblies are arranged in two groups, and the two groups of jack assemblies are arranged in sequence along the shear force transmission direction. Each group of jack assemblies is fixed to the support platform via a reaction force mechanism. Correspondingly, the force transmission wheel assemblies (17) are arranged in two groups, which are respectively arranged at positions below the two groups of jack assemblies.

3. A pavement interlayer shear scaling simulation device according to claim 2, characterized in that: The jack assembly comprises a jack, a vertical pressure sensor and a centering device. The vertical pressure sensor is arranged at the bottom of the jack and is connected to the centering device. The centering device is mounted on the magnetic attraction plate (15).

4. The pavement interlayer shear scaling simulation device according to claim 2, characterized in that: The reaction mechanism includes a door-type reaction frame, which includes a horizontal reaction rod and two vertical support rods. The horizontal reaction rod is installed above the jack assembly, and the two ends of the horizontal reaction rod are respectively supported and fixed by a vertical support rod. The bottom of the vertical support rod is anchored to the support platform. A circular groove is provided at the center line of the horizontal reaction rod, and the circular groove is used to be fixed with the top of the jack assembly to form a reaction loading point.

5. The pavement interlayer shear scaling simulation device according to claim 2, characterized in that: The force transmission wheel assembly (17) comprises a force transmission wheel (27) for simulating wheels on both sides of a vehicle, the force transmission wheel (27) being hingedly connected to the force transmission plate (16) via a triangular wheel axle (26), the force transmission wheel (27) comprising a steel wheel hub and a rubber tire rim, the steel wheel hub and the rubber tire rim being tightly attached to each other.

6. The pavement interlayer shear scaling simulation device according to claim 1, characterized in that: The horizontal tension and pressure control unit comprises a tension press, a connecting piece (7) and a tension and pressure sensor (8), wherein the front end of the connecting piece (7) is connected to the tension press, the rear end of the connecting piece (7) is provided with a circular groove and is adapted to the sensing front end of the tension and pressure sensor (8), the rear end of the tension and pressure sensor (8) is provided with a circular groove, and the circular groove is provided with an internal thread adapted to the external thread of the front end protrusion (9) of the upper shear box (10).

7. A pavement interlayer shear scaling simulation device according to claim 6, characterized in that: The drawing press comprises a continuously variable speed drawing press (3).

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