Dynamic single shear direct shear test device for large-size geosynthetics

Abstract

The utility model belongs to the technical field of testing machines for testing the strength characteristics of solid materials by mechanical stress, and provides a dynamic single-shear direct-shear testing device for large-size geosynthetics, which comprises an upper shear box, a lower shear box, a lower shear box and a lower shear box, and upper spike teeth are uniformly distributed on the lower surface of the upper shear box; the vertical load mechanism is connected with the upper shear box; the lower shearing box is arranged below the upper shearing box, a circle of smooth plane is arranged on the outer edge of the upper surface of the lower shearing box, and lower spike teeth are uniformly distributed in the middle of the lower shearing box; the horizontal load mechanism is connected with the lower shear box; the displacement measuring mechanism comprises a plurality of displacement measuring units, each displacement measuring unit comprises a hollow stacked ring and a displacement meter, the stacked rings of all the displacement measuring units are stacked on the smooth plane of the lower shear box, hollow areas in the stacked rings correspond to the positions of the lower spike teeth, and the displacement meters are connected with the stacked rings in a one-to-one correspondence mode. According to the utility model, the displacement and shear strength of each layer of geosynthetics of the composite liner system can be measured.

Description

Technical Field

[0001] This utility model belongs to the technical field of testing machines for testing the strength characteristics of solid materials under mechanical stress, and particularly relates to a dynamic single shear direct shear test device for large-size geosynthetics. Background Technology

[0002] Landfilling is the primary method of disposing of municipal solid waste, and composite liner systems, acting as a barrier between pollutants and the external environment, are an important component of modern municipal solid waste landfills. Currently, composite liner systems are generally composed of multiple layers of geosynthetic materials, including geotextiles, geomembranes, and special geosynthetic materials, to prevent seepage and isolate pollutants.

[0003] Currently, an increasing number of landfill projects are being constructed in earthquake-prone or well-connected areas. However, the shear strength between the interfaces of the various layers in a composite liner system is relatively low. In these areas, the soil is susceptible to slippage along the interfaces due to seismic stress and traffic dynamic loads, leading to changes in the shear strength of the composite liner system. Considering that both horizontal and vertical dynamic stresses have the greatest impact on the shear strength of the composite liner system, and that the system is composed of multiple layers of geosynthetic materials, testing the shear strength of each layer of geosynthetic material in the composite liner system is crucial.

[0004] However, existing large direct shear apparatuses can only measure the overall displacement of the lower shear box, and cannot obtain the displacement and shear strength of each layer of geosynthetic material, nor can they measure the displacement of the interfaces of each layer of composite liner without limiting the failure surface. Therefore, it is impossible to quantitatively measure the proportion of the failure surface displacement in the total displacement, and it is difficult to accurately measure the change in the shear strength of the composite liner system. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a dynamic single shear direct shear test device for large-size geosynthetics, which can measure the displacement and shear strength of each layer of large-size geosynthetics.

[0006] The technical solution adopted by this utility model to solve its technical problem is:

[0007] A dynamic single-shear direct shear test device for large-size geosynthetics includes an upper shear box, a vertical load mechanism, a lower shear box, a horizontal load mechanism, and multiple displacement measurement mechanisms.

[0008] The lower surface of the upper shear box is evenly covered with upper nail teeth, which are triangular saw teeth with a height of no more than 1 mm.

[0009] The vertical load mechanism is connected to the upper shear box and is used to drive the upper shear box to move in the vertical direction and measure the vertical displacement of the upper shear box.

[0010] The lower shear box is located below the upper shear box. The outer edge of the upper surface of the lower shear box is provided with a smooth plane, and the middle is evenly covered with lower nail teeth. The lower nail teeth are triangular saw teeth with a height of no more than 1mm.

[0011] The horizontal load mechanism is connected to the lower shear box and is used to drive the lower shear box to move in the horizontal direction and measure the horizontal displacement of the lower shear box.

[0012] The displacement measuring mechanism includes multiple displacement measuring units. Each displacement measuring unit includes a hollow stacked ring and a displacement gauge. The thickness of the stacked ring does not exceed 2 mm. All the stacked rings of the displacement measuring units are stacked on the smooth plane of the lower shear box. The hollow area inside the stacked ring corresponds to the position of the lower nail teeth. The displacement gauge is connected to the stacked ring in a one-to-one correspondence. The number of displacement measuring units is two fewer than the number of layers of geosynthetic material. The bottom layer of geosynthetic material is laid on the lower nail teeth and fixed by the lower nail teeth. Its top layer is nailed and fixed by the upper nail teeth. The remaining layers are laid on the corresponding stacked rings in sequence and fixed.

[0013] Optionally, the remaining layers of the geosynthetic material, except for the top and bottom layers, are fixed to the corresponding stacked rings with epoxy resin.

[0014] Optionally, the displacement measuring unit further includes an L-shaped tube fixedly installed on the outer periphery of the stacked ring. The horizontal tube of the L-shaped tube is connected to the stacked ring, and its vertical tube is set vertically upward and connected to the displacement gauge.

[0015] Optionally, the displacement measuring unit further includes a sphere and an L-shaped reinforcing rod that are snapped into the vertical tube of the L-shaped tube. The vertical rod of the L-shaped reinforcing rod is connected to the sphere, and its horizontal rod is connected to the displacement gauge.

[0016] Optionally, all L-shaped tubes of the stacked rings are staggered in the horizontal direction.

[0017] Optionally, the device may further include a water tank disposed around the lower shear box and the stacked rings, the height of which is greater than the sum of the heights of the lower shear box and all the stacked rings thereon.

[0018] Optionally, the displacement measuring unit further includes a fixed platform installed on the outer periphery of the water tank, on which all displacement gauges are installed.

[0019] The beneficial effects of this utility model are as follows: By setting up multiple displacement measurement units, specifically by stacking multiple rings on a lower shear box, the bottommost ring is placed on the smooth surface of the lower shear box, and the hollow area of ​​this ring corresponds to the position of the lower nail teeth, which can prevent the ring from being nailed by the lower nail teeth. The remaining rings are stacked in sequence, and each ring is connected to a corresponding displacement gauge. During measurement, the bottom layer of geosynthetic material is laid on the lower nail teeth and fixed. The remaining layers of material, except for the top layer, are laid on the corresponding rings in sequence and fixed. The top layer is laid on top and fixed by the upper nail teeth (the top layer of material itself is fixed and does not need to be measured for displacement, so it does not need to be fixed to the rings). As a hollow, thin-sheet structure, adjacent layers of geosynthetic material are in direct contact at the hollow part of the stacked rings, only not in contact at the perimeter due to the stacked rings. Activating the horizontal load mechanism moves the lower shear box horizontally, allowing the displacement of the lowest layer of geosynthetic material to be measured via the horizontal load mechanism, and the displacement of the geosynthetic material on the stacked rings connected to it to be measured via displacement gauges. This provides real-time horizontal displacement of each layer, and thus the shear strength of each layer. Furthermore, since the entire process can involve cyclic shearing or static shearing without limiting the failure surface, displacement of the interfaces between layers of the composite liner without limiting the failure surface can be measured, thereby quantitatively determining the proportion of the failure surface displacement in the total displacement and achieving precise measurement of the change in the shear strength of the composite liner system. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0021] Figure 1 This is a front view of an embodiment of the present utility model;

[0022] Figure 2 This is a top view of an embodiment of the present utility model;

[0023] Figure 3 This is a top view of the stacked ring in an embodiment of this utility model;

[0024] Figure 4 This is a front view of the stacked ring in an embodiment of this utility model.

[0025] In the diagram: 100-Vertical load mechanism; 101-Vertical displacement sensor; 102-Vertical actuator; 103-Vertical servo valve; 104-Vertical load sensor; 200-Horizontal load mechanism; 201-Horizontal load sensor; 202-Horizontal displacement sensor; 203-Horizontal actuator; 300-Displacement measuring mechanism; 301-Stacked ring; 302-Displacement gauge; 303-L-shaped tube; 304-Spherical ball; 305-L-shaped reinforcing rod; 400-Fixed platform; 500-Upper shear box; 501-Upper nail tooth; 600-Lower shear box; 601-Smooth plane; 602-Lower nail tooth; 700-Water tank. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0027] In the description of this utility model, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and 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, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 utility model based on the specific circumstances. Furthermore, in the description of this utility model, unless otherwise stated, "multiple" or "several" means two or more.

[0029] like Figures 1-4As shown, this utility model provides a dynamic single shear direct shear test device for large-size geosynthetics, including an upper shear box 500, a vertical load mechanism 100, a lower shear box 600, a horizontal load mechanism 200, and multiple displacement measuring mechanisms 300.

[0030] The lower surface of the upper shear box 500 is provided with evenly distributed upper nail teeth 501, and the lower nail teeth are triangular serrations with a height of no more than 1mm;

[0031] The vertical load mechanism 100 is connected to the upper shear box 500 and is used to drive the upper shear box 500 to move in the vertical direction and measure the vertical displacement of the upper shear box 500.

[0032] The lower shear box 600 is located below the upper shear box 500, and the outer edge of the upper surface of the lower shear box 600 is provided with a smooth flat surface 601. Figure 2 (The middle is blocked by the overlapping ring), the middle is evenly covered with lower nail teeth 602, and the lower nail teeth 602 are triangular saw teeth with a height of no more than 1mm;

[0033] The horizontal load mechanism 200 is connected to the lower shear box 600 and is used to drive the lower shear box 600 to move in the horizontal direction and measure the horizontal displacement of the lower shear box.

[0034] The displacement measuring mechanism 300 includes multiple displacement measuring units. Each displacement measuring unit includes a hollow stacked ring 301 and a displacement gauge 302. The thickness of the stacked ring 301 does not exceed 2 mm. All the stacked rings 301 of the displacement measuring units are stacked on the smooth plane 601 of the lower shear box 600. The hollow area inside the stacked ring 301 corresponds to the position of the lower nail teeth 602. The displacement gauges 302 are connected to the stacked rings 301 one by one. The number of displacement measuring units is two fewer than the number of layers of geosynthetic material. The bottom layer of geosynthetic material is laid on the lower nail teeth and fixed by them. Its top layer is fixed by the upper nail teeth. The remaining layers are laid on the corresponding stacked rings and fixed in sequence. The displacement of the bottom layer is consistent with the displacement of the lower shear box, so it does not need to be measured with the stacked rings; it can be fixed to the lower nail teeth. The top layer itself is fixed and does not need to be measured, so it does not need to be fixed to the stacked rings.

[0035] In order to allow all layers of geosynthetic material to be in direct contact in the hollow part of the stacked ring, the stacked ring should be as thin as possible. Considering the actual processing cost and difficulty, the thickness of the stacked ring in this embodiment is 1mm.

[0036] Because the stacked rings are very thin, it is not convenient to show individual displacement measurement units through the attached diagrams if they are stacked together. Figure 1 The overlapping rings are displayed with a certain distance between them, but in actual use, the overlapping rings are directly stacked together.

[0037] This utility model embodiment also includes a main frame not shown in the figures, as this application does not involve structural improvements to the main frame and therefore it is not shown in the figures. The main frame can be an existing direct shearing machine main frame, specifically including vertical frames on both sides of the lower shear box, a top platform on the top of the vertical frames, horizontal guide rails on the foundation, and a horizontal support at one end of the lower shear box. The upper shear box is slidably disposed within the vertical frames, the vertical load mechanism is mounted on the top platform, the lower shear box is slidably disposed on the horizontal guide rails, and the horizontal load mechanism is mounted on the horizontal support.

[0038] like Figure 1 , Figure 2 As shown, the vertical load mechanism 100 includes a vertical actuator 102 (which can be a vertical hydraulic actuator), a vertical displacement sensor 101 (which can be a vertical magnetostrictive displacement sensor), a vertical servo valve 103 (which can be a hydraulic servo valve), and a vertical load sensor 104 mounted on the vertical actuator. The upper shear box is fixedly mounted on the bottom of the vertical actuator. The vertical actuator applies normal stress to the upper shear box, enabling the upper shear box to move in the vertical direction. The vertical displacement sensor is used to acquire the vertical displacement information of the upper shear box, and the vertical load sensor is used to acquire the vertical load information received by the upper shear box.

[0039] like Figure 1 , Figure 2 As shown, the horizontal load mechanism 200 includes a horizontal actuator 203 (which can be a horizontal hydraulic actuator) and a horizontal load sensor 201 and a horizontal displacement sensor 202 (which can be a horizontal magnetostrictive displacement sensor) mounted on the horizontal actuator. The horizontal actuator is fixedly mounted on a horizontal support, and the lower shear box is slidably mounted on a horizontal guide rail. The horizontal actuator applies a horizontal load to the lower shear box, enabling the lower shear box to move in the horizontal direction. The horizontal displacement sensor is used to acquire the horizontal displacement information of the lower shear box, and the horizontal load sensor is used to acquire the horizontal load information received by the lower shear box.

[0040] The lower surface of the upper shear box and the upper surface of the lower shear box are machined with upper and lower nail teeth, respectively, and have a self-positioning function. Both the upper and lower nail teeth are triangular serrations with a height of no more than 1 mm. The tips of the triangular serrations can hold the material, fixing the geosynthetic material to the upper and lower shear boxes. However, due to the small height of the triangular serrations, they cannot and will not penetrate the geosynthetic material. The bottom layer of geosynthetic material is fixed by the lower nail teeth, but the lower nail teeth will not penetrate this material. If they did penetrate, they would also hold the material above, causing the upper and lower layers to be fixed as a whole, preventing relative displacement. The same applies to the upper nail teeth; if they penetrate the material, they will also restrict the displacement of the lower layer, affecting normal shear testing.

[0041] like Figure 3 , Figure 4 As shown, the stacked rings are hollow rectangular thin sheets with an inner diameter equal to the size of the load-bearing panel of the lower shear box. Multiple stacked rings are placed on the lower shear box, with both the upper and lower surfaces of the stacked rings open. Because the stacked rings are very thin and hollow, the geosynthetic materials of adjacent layers are in direct contact at the hollow part of the stacked rings, only not in contact at the perimeter due to being separated by the stacked rings. The stacked rings serve as an auxiliary measure for displacement measurement, with the shear surface located in the hollow part in the middle that is not in contact with the stacked rings.

[0042] In one embodiment, such as Figure 1 , Figure 2 As shown, in geosynthetic materials, the remaining layers except the top and bottom layers are fixed to corresponding stacked rings with epoxy resin. Multiple stacked rings fix the geosynthetic materials together with epoxy resin. Displacement gauges connected to the stacked rings can measure the displacement of each layer in real time. The top and bottom layers of the geosynthetic material are not fixed to the stacked rings for the following reasons: the upper and lower shear boxes have spikes that directly fix the materials; the displacement of the bottom layer is consistent with the displacement of the lower shear box, so there is no need to use the stacked rings for measurement; the top layer itself is stationary and its displacement does not need to be measured, therefore it does not need to be fixed to the stacked rings.

[0043] In one embodiment, such as Figures 1-4 As shown, the displacement measuring unit also includes an L-shaped tube 303 fixedly installed on the outer periphery of the stacked ring 301. The horizontal tube of the L-shaped tube 303 is connected to the stacked ring 301, and its vertical tube is vertically arranged upwards and connected to the displacement gauge. Since the stacked ring in this invention is very thin and difficult to connect directly to the displacement gauge, an L-shaped tube (which can be welded to the outer periphery of the stacked ring) is installed on the outer periphery of the stacked ring, and the L-shaped tube is used to connect to the displacement gauge.

[0044] Considering that the displacement gauge moves horizontally, it is difficult to directly connect it to the vertical pipe of the L-shaped tube. Therefore, in one embodiment, such as Figure 1 , Figure 2 As shown, the displacement measuring unit also includes a sphere 304 and an L-shaped reinforcing rod 305, which are snapped into the vertical tube of the L-shaped tube. The vertical rod of the L-shaped reinforcing rod is connected to the sphere, and its horizontal rod is connected to the displacement gauge. In this invention, the vertical tube of the L-shaped tube is a hollow cylinder, and the sphere and the vertical tube are precisely snapped together to form a fixed connection. The connection between the sphere and the displacement gauge is further enhanced by the L-shaped reinforcing rod, which can improve the rigidity and stability of the connection structure, avoid loosening of the connection due to horizontal load impact during the test, and ensure the linear accuracy of displacement transmission. Specifically, the horizontal rod of the L-shaped reinforcing rod and the displacement gauge can be connected by threads, which facilitates disassembly, assembly, debugging, and displacement gauge calibration and replacement, while ensuring the tightness of the connection and avoiding displacement deviation during long-term testing.

[0045] Considering the thinness of the stacked rings and the limited vertical space, in one embodiment, such as Figure 2 As shown, all the L-shaped tubes of the stacked rings are staggered in the horizontal direction.

[0046] In one embodiment, such as Figure 1 , Figure 2 As shown, the device also includes a water tank 700 disposed around the lower shear box and the stacked rings. The height of the water tank is higher than the sum of the heights of the lower shear box and all the stacked rings placed on it, ensuring that the water level in the tank can submerge the geosynthetic material after filling, thus simulating the actual damp conditions of a landfill and ensuring that the test conditions are consistent with the actual engineering situation. The water tank is a sealed container with a sealed bottom and sides to prevent leakage after filling and ensure the stability of the water environment in the test area.

[0047] In one embodiment, such as Figure 1 , Figure 2 As shown, the displacement measuring unit also includes a fixed platform 400 installed on the outer periphery of the water tank 700. All displacement gauges are installed on the fixed platform 400. Since the stacked rings are very thin, the displacement gauges have a small height difference after all the stacked rings are stacked. Therefore, all displacement gauges can be easily installed on the fixed platform for fixation.

[0048] The steps for conducting shear tests on multilayer geosynthetic materials using this invention are as follows.

[0049] First, the geosynthetic material is fixed. The number of stacked rings is selected according to the number of geosynthetic material layers. For example, in this embodiment, there are 11 layers of geosynthetic material, so 9 stacked rings are used. When placing the geosynthetic material, first place the first layer of geosynthetic material (the bottom layer) on the lower nail teeth of the lower shear box. This layer of geosynthetic material does not need to be fixed to the stacked rings with epoxy resin. Then place the first stacked ring, and place the second layer of geosynthetic material on the first stacked ring. Use epoxy resin to fix the second layer of geosynthetic material to the stacked ring. Place the second to ninth stacked rings in this manner to complete the placement of the third to tenth layers of geosynthetic material. Finally, place the eleventh layer of geosynthetic material (the top layer) on the tenth layer of geosynthetic material. The top layer of geosynthetic material does not need to be fixed to the stacked rings; it can be directly stacked. Control the vertical actuator to make the upper nail teeth of the upper shear box nail the top layer of material, thereby achieving the fixation of the geosynthetic material.

[0050] Then, install the displacement measuring mechanism. Install a displacement measuring unit for each stacked ring. Place the sphere inside the vertical rod of the connecting rod, and the two are locked together to form a fixed connection. Then, thread the L-shaped reinforcing rod to the displacement gauge. The displacement of each stacked ring can be determined by the reading of the high-precision displacement gauge, and thus the displacement of each layer of geosynthetic material can be obtained.

[0051] Fill the water tank with water up to 700 mm, ensuring the water level is above the geosynthetic material as required by the specifications.

[0052] Apply horizontal pressure using the horizontal actuator, and the entire test operation process should meet the requirements of the direct shear instrument operation procedure.

[0053] The dynamic control system in this invention, through hydraulic control, achieves bidirectional dynamic stress action in both horizontal and vertical directions. The process is easy to operate and control, restoring the dynamic characteristics of the sample interface. The entire process can involve cyclic shearing or static shearing without limiting the failure surface, obtaining the displacement and shear strength between each layer of material. Thus, the cohesion C and internal friction angle φ can be obtained through Mohr's Coulomb law; the shear stiffness K and damping ratio D can also be calculated.

[0054] This invention simulates a composite liner system composed of multiple layers of geosynthetic materials using stacked rings. The artificially constructed composite allows for single-shear testing, enabling rapid and accurate measurement of the shear strength of the composite liner and the displacement of each geosynthetic layer. This approach better reflects actual engineering conditions, and the large-size shear box can meet the simulation requirements of various working conditions. It can measure the shear strength of the composite liner under different conditions in real time, providing a larger shear interface area and effectively reducing the influence of size effects on the determination of interface shear strength. The test results are more accurate and can assist in the design and construction of composite liners for landfills in earthquake-prone and traffic-loaded areas.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all fall within the protection scope of the appended claims of this utility model.

Claims

1. A dynamic single-shear direct shear test device for large-size geosynthetics, characterized in that, It includes an upper shear box, a vertical load mechanism, a lower shear box, a horizontal load mechanism, and multiple displacement measurement mechanisms. The lower surface of the upper shear box is evenly covered with upper nail teeth, which are triangular saw teeth with a height of no more than 1 mm. The vertical load mechanism is connected to the upper shear box and is used to drive the upper shear box to move in the vertical direction and measure the vertical displacement of the upper shear box. The lower shear box is located below the upper shear box. The outer edge of the upper surface of the lower shear box is provided with a smooth plane, and the middle is evenly covered with lower nail teeth. The lower nail teeth are triangular saw teeth with a height of no more than 1mm. The horizontal load mechanism is connected to the lower shear box and is used to drive the lower shear box to move in the horizontal direction and measure the horizontal displacement of the lower shear box. The displacement measuring mechanism includes multiple displacement measuring units. Each displacement measuring unit includes a hollow stacked ring and a displacement gauge. The thickness of the stacked ring does not exceed 2 mm. All the stacked rings of the displacement measuring units are stacked on the smooth plane of the lower shear box. The hollow area inside the stacked ring corresponds to the position of the lower nail teeth. The displacement gauge is connected to the stacked ring in a one-to-one correspondence. The number of displacement measuring units is two fewer than the number of layers of geosynthetic material. The bottom layer of geosynthetic material is laid on the lower nail teeth and fixed by the lower nail teeth. Its top layer is nailed and fixed by the upper nail teeth. The remaining layers are laid on the corresponding stacked rings in sequence and fixed.

2. The dynamic single-shear direct shear test device for large-size geosynthetics according to claim 1, characterized in that, The geosynthetic material, except for the top and bottom layers, is fixed to the corresponding stacked rings with epoxy resin.

3. The dynamic single-shear direct shear test device for large-size geosynthetics according to claim 1, characterized in that, The displacement measuring unit also includes an L-shaped tube fixedly installed on the outer periphery of the stacked ring. The horizontal tube of the L-shaped tube is connected to the stacked ring, and its vertical tube is set vertically upward and connected to the displacement gauge.

4. The dynamic single-shear direct shear test device for large-size geosynthetics according to claim 3, characterized in that, The displacement measuring unit also includes a sphere that is snapped into the vertical tube of the L-shaped tube and an L-shaped reinforcing rod. The vertical rod of the L-shaped reinforcing rod is connected to the sphere, and its horizontal rod is connected to the displacement gauge.

5. The dynamic single-shear direct shear test device for large-size geosynthetics according to claim 3 or 4, characterized in that, All the L-shaped tubes of the stacked rings are staggered in the horizontal direction.

6. The dynamic single-shear direct shear test device for large-size geosynthetics according to claim 1, characterized in that, The device also includes a water tank disposed around the lower shear box and the stacked rings, the height of which is greater than the sum of the heights of the lower shear box and all the stacked rings stacked thereon.

7. The dynamic single-shear direct shear test device for large-size geosynthetics according to claim 6, characterized in that, The displacement measuring unit also includes a fixed platform installed on the outer periphery of the water tank, and all displacement gauges are installed on the fixed platform.

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