Device for testing cyclic shear characteristics of structural interface of geotechnical material

Abstract

The invention relates to a testing device for cyclic shear characteristics of a geotechnical material structure interface. The testing device comprises a shear box system, a vertical loading mechanism, a horizontal loading mechanism and a horizontal supporting mechanism. And the shear box system comprises a shear box main body and a soil body chamber in the shear box main body. The horizontal loading mechanism drives the shear box body to move horizontally, the horizontal supporting mechanism penetrates through the side wall of the shear box body and supports the soil body chamber to limit horizontal movement of the soil body chamber, and the stress action lines of the horizontal supporting mechanism and the soil body chamber are collinear. The shear box body is flush with the top of the soil body chamber, and the bottom is filled with a structural plane material sample and injected with liquid. The soil body chamber is filled with a rock-soil sample, the bottom surface of the rock-soil sample is in contact with the top surface of the structural surface sample, and the top surface is lower than the liquid level. The vertical loading mechanism is used for applying a load to the rock-soil sample. Compared with the prior art, the problem that the test accuracy is reduced due to the fact that the contact surfaces of the two samples incline is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering and energy engineering physical experiment simulation technology, and in particular to a test device for the cyclic shear characteristics of the interface of geotechnical materials. Background Technology

[0002] In geotechnical engineering and deep energy extraction (such as shale gas extraction, geothermal energy utilization, and nuclear waste geological disposal), the mechanical properties of the interface between soil and rock materials and structures (such as pile foundations, anchors, casings, and support structures) directly affect the overall stability and safety of the project. Under cyclic loading conditions such as earthquakes, traffic loads, temperature fluctuations, and fluid pressure fluctuations, the strength and stiffness of this interface may deteriorate, leading to structural failure. Therefore, accurately simulating and testing the shear behavior of the interface under cyclic loading is crucial.

[0003] Chinese patent CN110987663A discloses a constant stiffness cyclic shear tester, monitoring system, and method with controllable interface humidity. This addresses the problem that existing shear testers cannot accurately simulate interface shear modes in actual engineering projects. It achieves constant stress or constant stiffness loading and can be used for shear tests on soil and rock structures with varying humidity levels. The technical solution includes an operating platform and a vertical loading device, a horizontal loading device, and a shear simulation device installed above the platform. The shear simulation device includes a lower shear box and an upper shear box nested together, with space between them for shear motion. A horizontal guide rail is provided between the lower shear box and the operating platform. The vertical loading device is located above the upper shear box and connected to a constant stiffness providing device. The horizontal loading device is installed on one side of the upper shear box and can push the lower shear box to move along the horizontal guide rail.

[0004] However, the aforementioned existing technologies have the following drawbacks: 1. Controlling local humidity at the interface by spraying or adding water to the contact surface can only control local humidity at the interface, and cannot simulate the complex atmospheric or underground temperature-humidity coupling environment of soil and rock in real engineering.

[0005] 2. The height of the upper edge of the lower shear box is significantly less than that of the upper shear box, and the supporting force on the upper shear box and the force acting on the lower shear box are not on the same straight line. Based on this, in the laboratory, under certain conditions (such as the corrosion of materials by moisture), the interface between the lower and upper shear boxes may tilt slightly, resulting in inaccurate measured friction force.

[0006] 3. Its mechanical sensor is located outside the lower shear box. When the system friction of the device (such as piston and slide rail friction) is large, it is impossible to separate the pure interface friction resistance from the system friction. This poses a huge challenge to accurately monitoring the subtle weakening characteristics of interface strength during cyclic shearing. Summary of the Invention

[0007] The purpose of this invention is to provide a test device for cyclic shear characteristics of the interface of geotechnical materials to overcome the defects of the prior art, which can solve the problem of reduced accuracy caused by the tilting of the contact surface of the two samples.

[0008] The objective of this invention can be achieved through the following technical solutions: A test device for cyclic shear characteristics of geotechnical material structural interface includes a shear box system, a vertical loading mechanism, a horizontal loading mechanism, and a horizontal support mechanism. The shear box system includes a shear box body and a soil chamber located within the shear box body. The horizontal loading mechanism contacts the outer wall of the shear box body and drives the shear box body to move horizontally. The horizontal support mechanism passes through the side wall of the shear box body and contacts the outer wall of the soil chamber, supporting the soil chamber and restricting its movement on the horizontal plane. The highest point of the shear box body is flush with the highest point of the soil chamber. The bottom of the shear box body is filled with a structural interface material sample, and liquid is injected above the structural interface material sample. The soil chamber is filled with a geotechnical sample. The vertical loading mechanism contacts the geotechnical sample in the soil chamber. The bottom surface of the geotechnical sample contacts the top surface of the structural interface material sample. The top surface of the geotechnical sample is lower than the liquid level in the shear box body. The driving force of the horizontal loading mechanism on the shear box body and the supporting force of the horizontal support mechanism on the soil chamber are on a straight line.

[0009] The horizontal support mechanism includes a first force sensor, which is located between the inner wall of the shear box body and the outer wall of the soil chamber.

[0010] The horizontal support mechanism includes a bracket and multi-stage support rods. The multi-stage support rods are mounted on the bracket and are horizontally arranged. The first force sensor is mounted on the multi-stage support rods, and a second force sensor is also mounted on the multi-stage support rods. The second force sensor is located outside the shear box body.

[0011] The soil chamber has a first through hole near the upper edge of its side wall for liquid to pass through.

[0012] The first through hole is evenly distributed around the soil chamber.

[0013] The device also includes a displacement sensor for detecting the horizontal displacement of the shear box body.

[0014] The device also includes a temperature and humidity simulation mechanism, which includes a transparent acrylic box, an air supply pipe, and a temperature-controlled steam generator. The output end of the temperature-controlled steam generator is connected to the transparent acrylic box through the air supply pipe. The shear box system and the horizontal support mechanism are both located inside the transparent acrylic box. The output end of the horizontal loading mechanism passes through the side wall of the transparent acrylic box and contacts the shear box body. The shear box system also includes an integrated temperature and humidity sensor.

[0015] The vertical loading mechanism includes a loading motor, a loading frame, and a loading top plate. The loading motor and the loading top plate are both mounted on the loading frame, and the loading motor drives the loading top plate to move vertically to apply a vertical load to the soil sample in the soil chamber.

[0016] The horizontal loading mechanism includes a circulating motor and a horizontal loading unit. The horizontal loading unit is connected to the circulating motor and applies a horizontal load to the shear box body under the drive of the circulating motor.

[0017] The device also includes a shearing base, on which a slider rail is provided, and at the bottom of the shearing box system a slider that cooperates with the slider rail.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Firstly, similar to existing technologies, by setting up a shear box body and a soil chamber of different sizes, the contact area between the two can be kept stable during shear tests. However, on this basis, by aligning the highest point of the shear box body with the highest point of the soil chamber, and by injecting a sufficiently high level of liquid inside the shear box body, the driving force of the horizontal loading mechanism on the shear box body and the supporting force of the horizontal support mechanism on the soil chamber can be aligned on a straight line. This straight line can be closer to the center of gravity of the two. Furthermore, since the driving force of the horizontal loading mechanism on the shear box body and the supporting force of the horizontal support mechanism on the soil chamber are aligned on a straight line, the contact surface between the soil sample in the soil chamber and the structural surface material in the shear box body will not tilt during horizontal loading, and will remain stable and horizontal, thereby improving the accuracy of the test.

[0019] 2. The first force sensor is located inside the shear box body, between the inner wall of the shear box body and the outer wall of the soil chamber. This allows for accurate measurement of the frictional force between the soil sample in the soil chamber and the structural surface material inside the shear box body, without introducing system friction into the device.

[0020] 3. By setting up internal and external dual sensors, the force applied externally can be compared with the friction force actually felt on the internal contact surface. This helps to identify and eliminate the system friction of the system components such as sliders and guide rails, thereby enabling a purer and more accurate measurement of the shear force between the soil sample and the structural surface material interface, significantly improving the accuracy of the test data.

[0021] 4. Allows the liquid injected into the shear chamber to communicate with the soil chamber, thereby maintaining the balance of hydraulic pressure inside and outside the soil chamber, avoiding deformation of the soil chamber or additional stress on the sample due to pressure difference, and ensuring that the test is carried out under the preset stress conditions.

[0022] 5. Uniform connectivity from all sides ensures balanced hydraulic pressure from all directions, preventing the soil chamber from deflecting or experiencing additional torque due to uneven force distribution in the horizontal direction. This further guarantees the horizontal stability of the contact interface and the uniformity of the stress state during the test.

[0023] 6. It can directly and in real-time measure the displacement of the shear box under horizontal load. Combined with the shear force measured by the force sensor, it can accurately plot the shear stress-displacement relationship curve, thereby analyzing key mechanical parameters such as stiffness degradation and damping characteristics of the interface during cyclic shearing.

[0024] 7. It can actively control and simulate the complex temperature and humidity coupling environment of soil and rock materials, overcoming the limitation of existing technologies that can only control the local humidity of the interface. This makes the test more realistically reflect the influence of temperature and humidity changes on the long-term mechanical properties of soil and rock structure interfaces in actual engineering. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a front view schematic diagram of the present invention; Figure 3 This is a schematic diagram of the clipboard system. Figure 4 A frontal view of the clipboard; Figure 5 This is a schematic diagram of the inside of the clipboard. The components include: 1. Loading motor, 2. Circulating motor, 3. Loading frame, 4. Loading top plate, 5. Air supply pipe, 6. Shear box system, 7. Transparent acrylic box, 8. Temperature-controlled steam generator, 9. Shearing instrument base, 10. Soil chamber, 11. First force sensor, 12. Second force sensor, 13. Support, 14. Displacement sensor, 15. Integrated temperature and humidity sensor, 16. Shear box body, 17. Structural surface material sample, 18. Slider, 19. Slider track. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0028] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "proximal," "distal," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Physical quantities in formulas, unless otherwise specified, should be understood as basic quantities in the International System of Units (SI), or derived quantities derived from basic quantities through mathematical operations such as multiplication, division, differentiation, or integration.

[0029] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0030] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] A test device for cyclic shear characteristics of interfacial structures in geotechnical materials, such as Figure 1 and Figure 2 As shown, it includes a shear box system 6, a vertical loading mechanism, a horizontal loading mechanism, and a horizontal support mechanism, as follows: Figures 3 to 5As shown, the shear box system 6 includes a shear box body 16 and a soil chamber 10 located in the shear box body 16. A horizontal loading mechanism contacts the outer wall of the shear box body 16 and drives the shear box body 16 to move horizontally. A horizontal support mechanism passes through the side wall of the shear box body 16 and contacts the outer wall of the soil chamber 10, supporting the soil chamber 10 and restricting its movement on the horizontal plane. The highest point of the shear box body 16 is flush with the highest point of the soil chamber 10. The bottom of the shear box body 16 is filled with a structural surface material sample 17. Liquid is injected above the structural surface material sample 17. The soil chamber 10 is filled with a soil and rock sample. A vertical loading mechanism contacts the soil and rock sample in the soil chamber 10. The bottom surface of the soil and rock sample contacts the top surface of the structural surface material sample 17. The top surface of the soil and rock sample is lower than the liquid level in the shear box body 16. The driving force of the horizontal loading mechanism on the shear box body 16 and the supporting force of the horizontal support mechanism on the soil chamber 10 are on a straight line.

[0032] First, similar to existing technologies, by setting up a shear box body 16 of different sizes and a soil chamber 10, the contact area between the two can be kept stable during shear tests. However, on this basis, by aligning the highest point of the shear box body 16 with the highest point of the soil chamber 10, and by injecting a sufficiently high level of liquid inside the shear box body 16, the driving force of the horizontal loading mechanism on the shear box body 16 and the supporting force of the horizontal support mechanism on the soil chamber 10 can be aligned in a straight line. This straight line can be closer to the center of gravity of the two. Furthermore, since the driving force of the horizontal loading mechanism on the shear box body 16 and the supporting force of the horizontal support mechanism on the soil chamber 10 are aligned in a straight line, the contact surface between the soil sample in the soil chamber 10 and the structural surface material in the shear box body 16 will not tilt during horizontal loading, and will remain stable and horizontal, thereby improving the accuracy of the test.

[0033] The horizontal support mechanism includes a first force sensor 11, which is located between the inner wall of the shear box body 16 and the outer wall of the soil chamber 10. The first force sensor 11 is located within the shear box body 16 and between its inner wall and the outer wall of the soil chamber 10, thus enabling precise measurement of the frictional force between the soil sample in the soil chamber 10 and the structural surface material in the shear box body 16, without introducing system friction into the device.

[0034] The horizontal support mechanism includes a bracket 13 and multi-stage support rods. The multi-stage support rods are mounted on the bracket 13 and are horizontally positioned. A first force sensor 11 is mounted on the multi-stage support rods, and a second force sensor 12 is also mounted on the multi-stage support rods. The second force sensor 12 is located outside the shear chamber body 16. To measure the force and displacement during the test, the shear chamber system 6 integrates multiple sensors. The first force sensor 11, connected to the soil chamber 10, and the second force sensor 12, connected to the shear chamber body 16, are used to measure the shear resistance during the shearing process. The displacement sensor 14 is also connected to the shear chamber body 16 to accurately record the horizontal shear displacement. These sensors are securely fixed to the shear apparatus base 9 via the bracket 13, ensuring the stability of the measurement reference.

[0035] Specifically, the soil chamber 10 has a first through hole near the upper edge of its side wall for liquid to pass through. The first through hole is evenly arranged around the soil chamber 10. The device also includes a displacement sensor 14 for detecting the horizontal displacement of the shear box body 16.

[0036] In addition, in this embodiment, the device also includes a temperature and humidity simulation mechanism, which includes a transparent acrylic box 7, an air supply pipe 5, and a temperature-controlled steam generator 8. The output end of the temperature-controlled steam generator 8 is connected to the transparent acrylic box 7 through the air supply pipe 5. The shear box system 6 and the horizontal support mechanism are both located inside the transparent acrylic box 7. The output end of the horizontal loading mechanism passes through the side wall of the transparent acrylic box 7 and contacts the shear box body 16. The shear box system 6 also includes a temperature and humidity integrated sensor 15. The transparent acrylic box 7 completely covers the entire shear box system 6, forming a sealed space. The temperature-controlled steam generator 8 can not only generate water vapor but also heat it to a specific temperature, thereby continuously delivering water vapor with a specific temperature and humidity into the box. The temperature and humidity integrated sensor 15 is attached to the inner side wall of the shear box body 16 and can monitor the relative humidity and temperature in the sealed space in real time. The operating power and heating level of the temperature-controlled steam generator 8 are adjusted in coordination with the readings of the temperature and humidity integrated sensor 15 by a controller (not shown), thereby achieving precise control and stable maintenance of the temperature and humidity of the test environment.

[0037] The vertical loading mechanism includes a loading motor 1, a loading frame 3, and a loading top plate 4. The loading motor 1 and the loading top plate 4 are both mounted on the loading frame 3, and the loading motor 1 drives the loading top plate 4 to move vertically to apply a vertical load to the soil sample in the soil chamber 10.

[0038] The horizontal loading mechanism includes a circulating motor 2 and a horizontal loading unit. The horizontal loading unit is connected to the circulating motor 2 and applies a horizontal load to the shear box body 16 under the drive of the circulating motor 2.

[0039] The device also includes a shearing device base 9, on which the entire device is mounted. Above the base 9, a loading motor 1 is mounted via a loading frame 3. This loading motor 1 is connected to a loading top plate 4 and applies and maintains a constant vertical pressure on the shearing box system 6 below to simulate the weight of the overlying soil or structure. A circulating motor 2 is fixed to the shearing box system 6 and drives it to perform a preset cyclic reciprocating motion in the horizontal direction via its power output end to simulate earthquakes or traffic loads.

[0040] A structural surface material sample 17 is installed at the bottom of the shear box body 16 to simulate the surface of structural materials in actual engineering. The shear box body 16 is fixed to two sliders 18 by screws. The sliders 18 are placed in slider rails 19 fixed on the shearing instrument base 9. The sliders 18 contain steel balls. This design can greatly reduce the frictional resistance of the shear box body 16 during horizontal movement and improve the accuracy of displacement control. The soil chamber 10 can slide inside the shear box body 16 to achieve relative shearing with the transparent acrylic box 7 fixed at the bottom. This design ensures that the effective contact area between the two remains unchanged no matter how large the shear displacement is, thus achieving constant interface stress conditions.

[0041] The experimental method operation procedure for the device in this application is as follows: Step S1: First, fix the structural surface material sample 17 to be tested to the bottom of the shear box body 16. Then, compact the soil and rock material in layers or place it directly in the soil chamber 10 to prepare a sample with the specified density. Place the assembled shear box system 6 on the slider track 19.

[0042] Step S2: Cover the shear box system with the transparent acrylic box 7 and fix it to the base 9, ensuring its airtightness. Connect the steam supply pipe 5 of the steam generator 8.

[0043] Step S3: Start the loading motor 1, apply a constant normal stress to the sample in the soil chamber 10 through the loading top plate 4, and wait for the sample to consolidate and stabilize.

[0044] Step S4: Turn on the temperature-controlled steam generator 8 to begin supplying water vapor into the acrylic chamber 7. Simultaneously monitor the readings of the integrated temperature and humidity sensor 15 until the temperature and humidity inside the chamber reach and stabilize at the target values ​​required for the test.

[0045] Step S5: Start the circulating motor 2 and drive the shear box system 6 to begin horizontal reciprocating motion according to the preset displacement or load amplitude and frequency.

[0046] Step S6: Throughout the shearing process, the data acquisition system records the output signals of the two force sensors and displacement sensor 14 in real time. After the test, the collected data is processed and analyzed to obtain key parameters such as the shear stress-displacement hysteresis curve, stiffness decay law, and strength characteristics of the soil-rock material-structure interface under specific normal stress, specific humidity environment, and specific cyclic loading mode.

[0047] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A test device for cyclic shear characteristics of geotechnical material structural interfaces, comprising a shear box system (6), a vertical loading mechanism, a horizontal loading mechanism, and a horizontal support mechanism, characterized in that, The shear box system (6) includes a shear box body (16) and a soil chamber (10) located in the shear box body (16). The horizontal loading mechanism contacts the outer wall of the shear box body (16) and drives the shear box body (16) to move horizontally. The horizontal support mechanism passes through the side wall of the shear box body (16) and contacts the outer wall of the soil chamber (10) to support the soil chamber (10) and restrict the movement of the soil chamber (10) on the horizontal plane. The highest point of the shear box body (16) is flush with the highest point of the soil chamber (10). (16) The bottom is filled with a structural surface material sample (17), liquid is injected above the structural surface material sample (17), the soil chamber (10) is filled with a soil sample, the vertical loading mechanism is in contact with the soil sample in the soil chamber (10), the bottom surface of the soil sample is in contact with the top surface of the structural surface material sample (17), the top surface of the soil sample is lower than the liquid level in the shear box body (16), and the driving force of the horizontal loading mechanism on the shear box body (16) and the supporting force of the horizontal support mechanism on the soil chamber (10) are on a straight line.

2. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The horizontal support mechanism includes a first force sensor (11), which is located between the inner wall of the shear box body (16) and the outer wall of the soil chamber (10).

3. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 2, characterized in that, The horizontal support mechanism includes a bracket (13) and a multi-stage support rod. The multi-stage support rod is mounted on the bracket (13) and is horizontally arranged. The first force sensor (11) is mounted on the multi-stage support rod, and the multi-stage support rod is also equipped with a second force sensor (12). The second force sensor (12) is located outside the shear box body (16).

4. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The soil chamber (10) has a first through hole near the upper edge of its side wall for liquid to pass through.

5. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 4, characterized in that, The first through hole is evenly arranged around the soil chamber (10).

6. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The device also includes a displacement sensor (14) for detecting the horizontal displacement of the shear box body (16).

7. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The device also includes a temperature and humidity simulation mechanism, which includes a transparent acrylic box (7), an air supply pipe (5), and a temperature-controlled steam generator (8). The output end of the temperature-controlled steam generator (8) is connected to the transparent acrylic box (7) through the air supply pipe (5). The shear box system (6) and the horizontal support mechanism are both located inside the transparent acrylic box (7). The output end of the horizontal loading mechanism passes through the side wall of the transparent acrylic box (7) and contacts the shear box body (16). The shear box system (6) also includes a temperature and humidity integrated sensor (15).

8. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The vertical loading mechanism includes a loading motor (1), a loading frame (3) and a loading top plate (4). The loading motor (1) and the loading top plate (4) are both mounted on the loading frame (3), and the loading motor (1) drives the loading top plate (4) to move vertically to apply a vertical load to the soil sample in the soil chamber (10).

9. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The horizontal loading mechanism includes a circulating motor (2) and a horizontal loading unit. The horizontal loading unit is connected to the circulating motor (2) and applies a horizontal load to the shear box body (16) under the drive of the circulating motor (2).

10. The test device for cyclic shear characteristics of rock and soil material structural interfaces according to claim 1, characterized in that, The device also includes a shearing base (9), on which a slider rail (19) is provided, and at the bottom of the shearing box system (6) a slider (18) is provided to cooperate with the slider rail (19).

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