A direct shear device for simulating actual boundary conditions of contact surface elements and soil elements

Abstract

The application discloses a direct shear device for simulating actual boundary conditions of a contact surface unit and a soil unit, which comprises a shear bottom plate (21), a shear device, a horizontal loading device, a shear force data acquisition device, a normal loading device and a normal displacement data acquisition device; the direct shear device for simulating actual boundary conditions of a contact surface unit and a soil unit of the application improves the upper shear box of a traditional direct shear device into an upper shear device composed of a force transfer plate and a shear plate; the boundary shear plate and the shear plate bear the same normal load during the shearing process; the shearing action between the boundary shear plate and the soil during the shearing process can effectively simulate the shearing between the soil around the contact surface unit and the structure in the actual working condition; the boundary conditions of the contact surface between the shear plate and the soil are the same as the boundary conditions of the actual contact surface unit; and thus the shearing force of the contact surface between the shear plate and the soil measured by the tension and compression force sensor is more accurate.

Description

Technical Field

[0001] This invention relates to a direct shear test apparatus for soil and structure, and particularly to a direct shear apparatus that simulates the actual boundary conditions of contact surface elements and soil elements. Background Technology

[0002] In geotechnical engineering construction, there are numerous soil-structure contact surfaces, which are the weak points in the soil-structure interaction system. Many scholars have used direct shear tests to study the shear mechanics properties of soil-structure contact surfaces. However, in traditional direct shear devices, the rigid shear box around the soil sample restricts the deformation of the soil during the shearing process, which does not match the boundary conditions of the contact surface elements and soil elements in actual working conditions. Summary of the Invention

[0003] The purpose of this invention is to provide a direct shear device that simulates the actual boundary conditions of contact surface units and soil units, thus solving the problems mentioned in the background art.

[0004] This invention is implemented as follows: a direct shearing device simulating the actual boundary conditions of contact surface units and soil units. The direct shearing device includes: a shearing base plate, a shearing device, a horizontal loading device, a shear force data acquisition device, a normal loading device, and a normal displacement data acquisition device. The shearing device is disposed on the shearing base plate, the horizontal loading device is disposed on the shearing base plate and positioned on one side of the shearing device, the shear force data acquisition device is disposed on the shearing base plate and positioned on the other side of the shearing device, the normal loading device is erected above the shearing device, and the normal displacement data acquisition device is erected above the shearing device and positioned on one side of the normal loading device.

[0005] A further technical solution of the present invention is that the shearing device includes a lower shearing device and an upper shearing device disposed on the lower shearing device.

[0006] A further technical solution of the present invention is as follows: the upper shearing device includes: a boundary force transmission plate, a boundary shearing plate, a force transmission plate, a shearing plate, a latex film, fixing screws, and fixing pins. The shearing plate is placed inside the boundary shearing plate, the latex film covers the perimeter of the shearing plate, the boundary force transmission plate and the boundary shearing plate are connected by fixing screws, the boundary force transmission plate and the force transmission plate are connected by fixing pins, and the bottom surface of the boundary shearing plate is provided with a rough surface.

[0007] A further technical solution of the present invention is: the lower shearing device includes: a shearing box, a groove, a ball bearing, and a limiting plate. The groove is formed on the shearing base plate. The shearing box is slidably connected to the shearing base plate through the groove. The ball bearing is disposed in the groove. The limiting plate is disposed on the upper edge of the shearing box.

[0008] A further technical solution of the present invention is: the horizontal loading device includes: a shearing device, a force transmission rod, a rotating handwheel, and a horizontal loading device circuit interface. The shearing device is disposed on the shearing base plate, the shearing device is connected to the rotating handwheel through the force transmission rod, and the horizontal loading device circuit interface is disposed on the shearing device.

[0009] A further technical solution of the present invention is as follows: the shear force data acquisition device includes: a shear force acquisition port, a tension / compression sensor, a fixed support, a limiter, a vertical slide rod, and a spring. The fixed support is connected to the shear base plate through the vertical slide rod and the spring. The limiter is disposed on the fixed support. One end of the tension / compression sensor is connected to the fixed support, and the other end of the tension / compression sensor is connected to the force transmission plate. The shear force acquisition port is disposed on the tension / compression sensor and connected to an external computer.

[0010] A further technical solution of the present invention is as follows: the normal loading device includes: a reaction frame, a normal loading device circuit interface, a normal loading device, and a boundary normal loading device. The bottom of the reaction frame is fixedly connected to the shear base plate. The normal loading device and the boundary normal loading device are both disposed on the reaction frame and positioned above the shear device. The normal loading device circuit interface is disposed on the normal loading device and the boundary normal loading device and is electrically connected to an external computer.

[0011] A further technical solution of the present invention is: the normal displacement data acquisition device includes: a normal displacement sensor disposed on the reaction frame and a normal displacement data acquisition port disposed on the normal displacement sensor, wherein the normal displacement data acquisition port is electrically connected to an external computer.

[0012] The beneficial effects of this invention are as follows: The direct shearing device of this invention, which simulates the actual boundary conditions of the contact surface unit and the soil unit, improves the upper shear box of the traditional direct shearing device into an upper shearing device composed of a force transmission plate and a shear plate. The boundary shear plate and the shear plate are subjected to the same normal load during the shearing process. During the shearing process, the shearing action between the boundary shear plate and the soil can effectively simulate the shearing of the soil and structure around the contact surface unit in actual working conditions, so that the boundary conditions of the contact surface between the shear plate and the soil are the same as the boundary conditions of the actual contact surface unit, thereby making the shear force of the contact surface between the shear plate and the soil measured by the tension and compression sensors more accurate. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of a direct shear device for simulating the actual boundary conditions of contact surface units and soil units provided by the present invention. Figure 2 This is a schematic diagram of the upper shearing device of a direct shearing device for simulating the actual boundary conditions of contact surface units and soil units provided by the present invention. Figure 3 This is a front view of a direct shear device for simulating the actual boundary conditions of contact surface units and soil units provided by the present invention. Figure 4 This is a front view of a direct shear device for simulating the actual boundary conditions of contact surface units and soil units provided by the present invention. Figure 5 This is a schematic diagram of the structure of a limiting plate of a direct shear device for simulating the actual boundary conditions of contact surface units and soil units provided by the present invention. Figure 6 This is a schematic diagram of the shear box structure of a direct shear device for simulating the actual boundary conditions of contact surface units and soil units provided by the present invention. Detailed Implementation

[0014] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0015] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0016] Example 1: Figures 1-6 A direct shear device for simulating the actual boundary conditions of contact surface elements and soil elements is shown; the device consists of five parts: a horizontal loading device, a shear force data acquisition device, a normal loading device, and a normal displacement data acquisition device.

[0017] The shearing device can be divided into an upper shearing device and a lower shearing device. The upper shearing device consists of a boundary force transmission plate 3, a boundary shear plate 4, a force transmission plate 14, a shear plate 23, a latex membrane 22, fixing screws 12, and fixing pins 15. A thin layer of latex membrane 22 surrounds the shear plate 23, which can be placed inside the boundary shear plate 4. The boundary force transmission plate 3 is connected to the force transmission plate 14 by fixing pins 15, and the force transmission plate and the shear plate, as well as the boundary force transmission plate 3 and the boundary shear plate 4, are connected by fixing screws 12. The boundary force transmission plate is used to transmit normal loads and horizontal shear forces to the boundary shear plate, and the boundary shear plate is used to transmit normal loads and horizontal shear forces to the shear plate. The shear plate and the boundary shear plate of the device are detachable and replaceable, and shear plates and boundary shear plates with suitable materials and rough surfaces 24 can be selected according to the actual working conditions. The lower shearing device consists of a shear box 18, a groove 19, ball bearings 20, and a limiting plate 27. The shear box holds the soil sample. The inner diameter of the upper surface of the shear box along the shearing direction is less than or equal to the length of the boundary shear plate, and the inner diameter perpendicular to the shearing direction is equal to the length of the boundary shear plate. The lower part of the shear box contacts the ball bearings, which are placed in grooves on the shear base plate. The limiting plate restricts lateral deformation of the soil during shearing and is connected to a spring at its bottom. Figure 5 As shown, the compressible spring undergoes downward displacement after being subjected to downward pressure from the boundary shear plate.

[0018] The horizontal loading device consists of a shearing base plate 21, a shearing device 6, a force transmission rod 7, a rotating handwheel 8, and a horizontal loading device circuit interface 5. The shearing base plate 21 supports the upper shearing device. The shearing device 6 is fixedly connected to the shearing base plate 21. The shearing device 6 can control the force transmission rod 7 to generate a shearing displacement at a specified rate along the shearing direction through both manual and electric control. The manual control method involves twisting the loading handwheel on the shearing device to control the shearing displacement of the force transmission rod 7. The electric control method involves connecting a computer to the circuit interface of the shearing device to control the force transmission rod to generate a shearing displacement at a specified rate along the shearing direction. The shearing device is existing technology and is available in both manual and automatic versions. The shearing device 6 is driven by a hand-cranked or electrically operated motor to apply a horizontal load.

[0019] The shear force data acquisition device consists of a shear force acquisition port 11, a tension / compression sensor 13, a fixed support 17, a limiter 16, a vertical slide bar 28, and a spring 29. The bottom of the fixed support 17 is fixedly connected to the vertical slide bar 28 and the spring 29. The vertical slide bar 28 can drive the fixed support 17 to slide up and down, without providing support force, and is used to control the vertical sliding direction. The spring 29 is used to support the fixed support 17. During shearing, soil dilatation or contraction will cause the force transmission plate to undergo vertical displacement. The spring design allows the sensor in contact with the force transmission plate to undergo vertical displacement simultaneously under the friction of the force transmission bar, reducing errors generated during measurement. Limiter 16 is fixedly connected to fixed support 17. Limiter 16 is used to limit the displacement of boundary force transmission plate during shearing. One end of tension and compression sensor 13 is fixedly connected to fixed support, and the other end is connected to force transmission plate 14. It is used to measure the shear force on the contact surface between shear plate and soil during shearing. Shear force acquisition port 11 is connected to computer to store the shear force on the contact surface during shearing that is collected in real time in the computer.

[0020] The normal loading device consists of a reaction frame 1, a normal loading device circuit interface 2, a normal loading device 25, and a boundary normal loading device 26. The reaction frame 1 is fixedly connected to the shear base plate 21. The normal loading device 25 and the boundary normal loading device 26 are fixedly connected to the reaction frame. During shearing, the lower part of the normal loading device 25 contacts the upper part of the force transmission plate 14, providing a normal load to the contact surface between the shear plate and the soil. The boundary normal loading device 26 contacts the boundary force transmission plate 3, providing normal stress to the contact surface between the boundary shear plate and the soil. The normal loading device circuit interface is connected to a computer, allowing the computer to control the normal loading device and the boundary normal loading device to provide a specified normal load.

[0021] The normal displacement data acquisition device consists of a normal displacement sensor 9 and a normal displacement data acquisition port 10. The normal displacement sensor is fixedly connected to the reaction frame. During the shearing process, the lower part of the normal displacement sensor contacts the force transmission plate to measure the normal deformation of the soil. The normal displacement data acquisition port is connected to a computer, which can save the real-time monitored normal displacement data to the computer.

[0022] Usage steps: First, place the soil sample into the shear box, then place the shear box above the ball bearings and connect one end of the shear box to the force transmission rod; then connect the boundary force transmission plates to each other using fixing pins, cover the shear plate with a thin layer of latex film, and then use fixing screws to connect the shear plate and the force transmission plate to each other, and connect the boundary shear plate to the boundary force transmission plate; place the assembled upper shearing device on top of the shear box, and adjust the position of the upper shearing device so that the outer diameter of the boundary shear plate at the front, back, and right sides coincides with the normal projection of the inner diameter of the shear box, such as... Figure 1As shown, adjust the limit switch to make it contact the boundary force transmission plate, adjust the tension and compression sensors to connect with the force transmission plate, and adjust the normal displacement sensor to make it contact the upper end of the force transmission plate. Before the shear test begins, zero each sensor, then control the normal loading device to apply the same normal load to the force transmission plate and the boundary force transmission plate, and control the shear device to start the constant rate shear loading test.

[0023] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A direct shear device for simulating the actual boundary conditions of contact surface elements and soil elements, characterized in that, The direct shear device simulating the actual boundary conditions of the contact surface unit and soil unit includes: a shear base plate (21), a shear device, a horizontal loading device, a shear force data acquisition device, a normal loading device, and a normal displacement data acquisition device. The shear device is set on the shear base plate, the horizontal loading device is set on the shear base plate and placed on one side of the shear device, the shear force data acquisition device is set on the shear base plate (21) and placed on the other side of the shear device, the normal loading device is erected above the shear device, and the normal displacement data acquisition device is erected above the shear device and placed on one side of the normal loading device. The shear device includes: a lower shear device and an upper shear device set on the lower shear device. The upper shear device includes: a boundary force transmission plate (3), a boundary shear plate (4), a force transmission plate (14), and a shear plate (23). The shearing device includes: a latex film (22), a fixing screw (12), and a fixing pin (15). The shearing plate (23) is placed inside the boundary shearing plate (4). The latex film (22) covers the perimeter of the shearing plate (23). The boundary force transmission plate (3) is connected to the boundary shearing plate (4) by the fixing screw (12). The boundary force transmission plate (3) is connected to the force transmission plate (14) by the fixing pin (15). The bottom surface of the boundary shearing plate (4) is provided with a rough surface (24). The lower shearing device includes: a shearing box (18), a groove (19), a ball (20), and a limiting plate (27). The groove (19) is opened on the shearing base plate. The shearing box (18) is slidably connected to the shearing base plate through the groove (19). The ball (20) is set in the groove (19). The limiting plate (27) is set on the upper edge of the shearing box (18).

2. The direct shear device for simulating the actual boundary conditions of contact surface units and soil units according to claim 1, characterized in that, The horizontal loading device includes: a shearing device (6), a force transmission rod (7), a rotating handwheel (8), and a horizontal loading device circuit interface (5). The shearing device (6) is mounted on the shearing base plate (21). The shearing device (6) is connected to the rotating handwheel (8) through the force transmission rod (7). The horizontal loading device circuit interface (5) is mounted on the shearing device (6).

3. The direct shear device for simulating the actual boundary conditions of contact surface units and soil units according to claim 2, characterized in that, The shear force data acquisition device includes: a shear force acquisition port (11), a tension / compression sensor (13), a fixed support (17), a limiter (16), a vertical slide bar (28), and a spring (29). The fixed support (17) is connected to the shear base plate (21) through the vertical slide bar (28) and the spring (29). The limiter (16) is set on the fixed support (17). One end of the tension / compression sensor (13) is connected to the fixed support (17), and the other end of the tension / compression sensor (13) is connected to the force transmission plate (14). The shear force acquisition port (11) is set on the tension / compression sensor (13) and connected to an external computer.

4. The direct shear device for simulating the actual boundary conditions of contact surface units and soil units according to claim 1, characterized in that, The normal loading device includes: a reaction frame (1), a normal loading device circuit interface (2), a normal loading device (25), and a boundary normal loading device (26). The bottom of the reaction frame (1) is fixedly connected to the shear base plate (21). The normal loading device (25) and the boundary normal loading device (26) are both set on the reaction frame (1) and placed above the shear device. The normal loading device circuit interface (2) is set on the normal loading device (25) and the boundary normal loading device (26) and electrically connected to an external computer.

5. The direct shear device for simulating the actual boundary conditions of contact surface units and soil units according to claim 4, characterized in that, The normal displacement data acquisition device includes: a normal displacement sensor (9) installed on the reaction frame (1) and a normal displacement data acquisition port (10) installed on the normal displacement sensor (9), wherein the normal displacement data acquisition port (10) is electrically connected to an external computer.

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