Multi-directional seepage direct shear test device for geosynthetic-soil interface

Abstract

The utility model discloses a kind of geosynthetic material-soil interface multidirectional seepage direct shear test device, including frame, seepage system, horizontal shear system, normal loading system, equipment control and data acquisition system, horizontal shear system and normal loading system are all installed on frame;Equipment control and data acquisition system are connected respectively control seepage system, horizontal shear system and normal loading system;Horizontal shear system includes upper shear box and lower shear box, and soil sample and rigid foundation are respectively mounted in upper shear box and lower shear box, and geosynthetic material is placed on the top surface of rigid foundation, and the left and right ends of geosynthetic material are fixed by sawtooth geosynthetic material fixing plate.The utility model can measure the flow velocity and flow under soil horizontal and vertical seepage path in the process of geosynthetic material and soil shear, realize the evolution law research to the interface shear seepage characteristic of geosynthetic material in the process of shear.

Description

Technical Field

[0001] This utility model relates to indoor mechanical testing devices for geotechnical engineering, and in particular to a shear-seepage coupling testing device for the interface between geosynthetics and soil under multi-dimensional seepage paths. Background Technology

[0002] Geosynthetics are increasingly used in geotechnical engineering, especially in reinforced soil structures. The interfacial properties between geosynthetics and soil have a significant impact on the stability and load-bearing capacity of the structure. The mechanical properties of the geosynthetic interface are key parameters in engineering design and construction. Accurately obtaining these strength parameters is of great practical significance for engineering design and construction. For example, through laboratory shear tests, we can understand the interfacial friction characteristics between different geosynthetics and soil, including the friction angle and cohesion. These parameters are crucial for predicting and designing the load-settlement response of reinforced soil structures.

[0003] Currently, the interfacial mechanical properties of geosynthetics-soil interaction are mainly obtained through laboratory tests, including conventional triaxial tests, direct shear tests, and pull-out tests. Under deep, high-stress, and highly permeable water pressure environments, or under karst conditions, the structural strength of reinforced soil structures continuously deteriorates, potentially leading to major disasters. The mechanical behavior of the geosynthetic-soil interface under shear and seepage coupling is a key factor affecting the stability of reinforced soil structures. Most existing direct shear testing equipment for reinforced soil can only perform shear tests with different shear directions or force variations, failing to accurately reflect the seepage characteristics of the geosynthetic shear surface, resulting in inaccurate evaluation of the mechanical properties of the reinforced-soil interface.

[0004] Chinese patent application CN115219350A discloses a triaxial compression-shear seepage testing system and method for multiphase rock. The system includes a triaxial compression-shear test module and a loading control and acquisition module. The triaxial compression-shear test module consists of a shear seepage chamber composed of a detachably connected upper cylinder and a lower cylinder. A sliding rail device and a shear cylinder drive the lower cylinder to move relative to the upper cylinder, transmitting independent shear pressure to the sample. The loading and control module provides independent axial, circumferential, and shear pressures, while a pneumatic module provides fluid pressure. This device is positioned for rock seepage testing within a closed triaxial cavity, which is incompatible with the experimental boundaries and parameter system of direct shear-hydraulic seepage at the reinforced-soil interface. Furthermore, its highly integrated structure and complex testing chain lack a targeted design of "shear chamber system + rigid foundation outlet channel + multidimensional seepage path organization + direct velocity / flow rate measurement," making it difficult to achieve coupled shear-seepage characterization of the reinforced-soil interface under multi-directional seepage paths without significant modifications.

[0005] Chinese patent application CN114235601A discloses a direct shear-seepage test device and method for soil-rock interface under constant normal stress. The test device includes a direct shear loading system, a seepage control system, and a monitoring system. The direct shear loading system includes an upper shear box and a lower shear box. The upper shear box contains a rock specimen, and the lower shear box contains a soil specimen. The rock specimen has a flow channel, one end of which corresponds to the inlet and the other end is located at the interface. The lower shear box has an outlet and a water tank. A vertical jack is located on the top of the upper shear box, and a servo motor and a loading rod are located on one side of the lower shear box. The seepage control system includes a water pipe, which supplies water through a water supply device. The monitoring system includes a normal load sensor, a shear load sensor, a shear displacement sensor, and a flow measurement device, which are connected to a data acquisition system for communication. The seepage organization of this device is closer to a single closed channel of "inlet-guide-interface-outlet / water tank", lacking a multi-path switchable / combinable structure of "inlet water from the top / side of the upper shear box - outlet water channel from the side of the upper box / lower rigid foundation". At the same time, its monitoring is more biased towards the flow characterization of the outlet side, making it difficult to synchronously measure and compare the horizontal and vertical inlet and outlet flow velocities and flow rates throughout the entire chain.

[0006] Chinese patent application CN105223087A discloses a device and method for direct shear testing of coarse-grained soil. The device includes an upper shear box and a lower shear box, a frame, a vertical load loading component, a horizontal load loading component, a permeation system, and a pressure measurement system. The permeation system includes an inlet device, an outlet device, and inlets and outlets located on opposite sides of the upper and lower shear boxes, respectively. The inlet device is connected to the inlet, and the outlet device is connected to the outlet via pipes. This device focuses on direct shear testing of coarse-grained soil under seepage conditions, achieving seepage-shear coupling through lateral inlets / outlets, and is equipped with pressure and flow monitoring. However, this patent application does not address the geosynthetic-soil interface, lacking design for interface boundary conditions such as reinforcement laying and end clamping, making it difficult to directly characterize the seepage-mechanical coupling response of the reinforcement-soil interface during shearing. Furthermore, its seepage path organization is mainly based on a single lateral through-flow, failing to cover the needs for multi-dimensional seepage path combinations and comparisons. Utility Model Content

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-directional seepage direct shear test device for geosynthetic-soil interface. This device can obtain the evolution law of shear seepage characteristics of geosynthetic interface under different stress states, realize the test of direct shear and seepage coupling of geosynthetic under multi-dimensional seepage paths, and enrich and improve the test device for studying the seepage characteristics of shear surface.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A geosynthetic-soil interface multi-directional seepage direct shear test device includes a frame, a seepage system, a horizontal shear system, a normal loading system, and an equipment control and data acquisition system. The horizontal shear system and the normal loading system are respectively installed on the frame. The equipment control and data acquisition system is connected to control the seepage system, the horizontal shear system, and the normal loading system. The horizontal shear system includes an upper shear box and a lower shear box installed on a slide rail. The upper and lower shear boxes respectively contain soil samples and a rigid foundation with a water outlet channel in the middle. Geosynthetic material is placed on the top surface of the rigid foundation, and the left and right ends of the geosynthetic material are fixed by serrated geosynthetic material fixing plates.

[0009] The serrated geosynthetic fixing plate is installed on the frame.

[0010] The slide rails are provided in multiple sections and are installed side by side on the horizontal plate inside the frame.

[0011] The seepage system includes an air compressor connected to a water supply device, which is connected to the top and inner sides of the upper shear box via an inlet channel. The seepage system also includes a water collection device, which is connected to the inner side of the upper shear box and the outlet channel of the rigid foundation in the lower shear box via a drainage channel.

[0012] The water inlet channel and the water outlet channel are respectively equipped with switches and water flow velocity and flow rate measuring instruments.

[0013] The inlet and outlet channels are fitted with permeable stones at their contact points with the upper shear box to prevent the soil samples from clogging them.

[0014] The water flow velocity and flow rate measuring instrument is connected to the equipment control and data acquisition system.

[0015] The air compressor, water supply device, water inlet channel, drainage channel, and water collection device are each provided in two sets.

[0016] The horizontal shearing system also includes a horizontal servo motor, which is horizontally loaded on one side of the lower shear box via a force transmission rod. A horizontal displacement sensor is installed on one side of the lower shear box, and a horizontal load sensor is installed on one side of the upper shear box. The horizontal displacement sensor and the horizontal load sensor are respectively connected to the equipment control and data acquisition system.

[0017] The normal loading system includes a vertical servo motor installed in the frame. The vertical servo motor acts on the pressure cap on the upper part of the soil sample in the upper shear box through a force transmission rod. A vertical load sensor is installed on the force transmission rod, and a vertical displacement sensor is installed on the pressure cap. The vertical load sensor and the vertical displacement sensor are respectively connected to the equipment control and data acquisition system.

[0018] The beneficial effects of this invention are: it enables the measurement of flow velocity and flow rate under horizontal and vertical seepage paths in the soil during the shearing process between geosynthetics and soil, allowing for the study of the evolution law of the interfacial shear seepage characteristics of geosynthetics during the shearing process, obtaining the evolution law of the interfacial shear seepage characteristics of geosynthetics under different stress states, realizing the experiment of the coupling of direct shear and seepage of geosynthetics under multi-dimensional seepage paths, and enriching and improving the study of seepage characteristics of shear surfaces. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model; The components include: 1. Frame; 2. Equipment control and data acquisition system; 3. Air compressor; 4. Water supply device; 5. Water inlet channel; 6. Switch; 7. Water flow velocity and flow rate measuring instrument; 8. Vertical load sensor; 9. Vertical displacement sensor; 10. Upper shear box; 11. Horizontal load sensor; 12. Geosynthetic material; 13. Serrated geosynthetic material fixing plate; 14. Drainage channel; 15. Water collection device; 16. Lower shear box; 17. Slide rail; 18. Rigid foundation; 19. Permeable stone; 20. Soil sample; 21. Horizontal servo motor; 22. Horizontal displacement sensor; 23. Pressurized top cover; 24. Dowel bar; 25. Vertical servo motor. Detailed Implementation

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

[0021] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the content disclosed herein. They are not intended to limit the scope of this utility model and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this utility model, 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 of description and are not intended to limit the scope of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this utility model's implementation.

[0022] like Figure 1As shown, a geosynthetic-soil interface multi-directional seepage direct shear test device includes a frame 1, a seepage system, a horizontal shear system, a normal loading system, and an equipment control and data acquisition system 2. The horizontal shear system and the normal loading system are respectively installed on the frame 1. The equipment control and data acquisition system 2 is connected to control the seepage system, the horizontal shear system, and the normal loading system. The horizontal shear system includes an upper shear box 10 and a lower shear box 16 installed on a slide rail 17. The upper and lower shear boxes 10 and 16 respectively contain soil samples 20 and a rigid foundation 18 with a water outlet channel in the middle. Geosynthetic material 12 is placed on the top surface of the rigid foundation 18, and the left and right ends of the geosynthetic material 12 are fixed by serrated geosynthetic material fixing plates 13. The serrated geosynthetic material fixing plates 13 are installed on the frame 1.

[0023] Multiple slide rails 17 are provided and installed side by side on the inner horizontal plate of frame 1.

[0024] The seepage system includes an air compressor 3, which is connected to a water supply device 4. The water supply device 4 is connected to the top and inner sides of the upper shear box 10 through an inlet channel 5. The seepage system also includes a water collection device 15, which is connected to the inner side of the upper shear box 10 and the outlet channel of the rigid foundation 18 in the lower shear box 16 through a drainage channel 14.

[0025] A switch 6 and a water flow velocity and flow rate measuring instrument 7 are respectively installed on the water inlet channel 5 and the drainage channel 14. Permeable stones 19 are installed at the contact points between the water inlet channel 5 and the drainage channel 14 and the upper shear box 10 to prevent the water inlet channel 5 and the drainage channel 14 from being blocked by the soil sample 20. The water flow velocity and flow rate measuring instrument 7 is connected to the equipment control and data acquisition system 2.

[0026] Two sets of air compressor 3, water supply device 4, water inlet channel 5, drainage channel 14 and water collection device 15 are respectively provided.

[0027] The seepage system is the core component of this experimental device. It is responsible for simulating the seepage process in the soil. The seepage system can control the direction and speed of the water flow. By precisely controlling the water flow, different seepage paths and seepage conditions can be simulated, such as horizontal seepage paths, vertical seepage paths, constant head, variable head, or heterogeneous seepage. By connecting with the equipment control and data acquisition system, the flow velocity and flow rate of the water in the inlet channel and the flow velocity and flow rate of the water in the outlet channel are collected in real time during the test.

[0028] The horizontal shear system is a key component of the experimental setup. It applies shear force to simulate the horizontal shearing motion between the geosynthetic material and the soil. The horizontal shear system also includes a horizontal servo motor 21, which is horizontally loaded onto one side of the lower shear box 16 via a force transmission rod 24. A horizontal displacement sensor 22 is mounted on one side of the lower shear box 16, and a horizontal load sensor 11 is mounted on one side of the upper shear box 10. The horizontal displacement sensor 22 and the horizontal load sensor 11 are connected to the equipment control and data acquisition system 2. The horizontal servo motor 21 is controlled to apply a constant or variable shear rate, and the shear displacement and shear force during the test are collected in real time.

[0029] The normal loading system is used to apply pressure perpendicular to the soil sample to simulate the load on the soil in the vertical direction. The normal loading system includes a vertical servo motor 25 installed in the frame 1. The vertical servo motor 25 acts on the upper shear box 10 through a force transmission rod 24. A vertical load sensor 8 is installed on the force transmission rod 24, and a vertical displacement sensor 9 is installed on the upper shear box 10. The vertical load sensor 8 and the vertical displacement sensor 9 are respectively connected to the equipment control and data acquisition system 2 to control the vertical servo motor 25 to apply the vertical load and to collect the normal load and vertical displacement in real time during the test.

[0030] The main experimental steps include: Take a rigid foundation 18 and place the rigid foundation 18 with a water outlet channel in the lower shear box 16. Place the cut geosynthetic material 12 on the top surface (i.e. the shear surface) of the rigid foundation 18 and fix it with the serrated geosynthetic material fixing plates 13 at the left and right ends respectively.

[0031] Install the upper shear box 10, put the saturated soil sample 20 into the upper shear box 10, and place the pressure top cover 23 on the top surface of the soil sample 20.

[0032] To test horizontal seepage, install the seepage system by sequentially connecting the water supply device 4, water inlet channel 5, switch 6, water flow velocity and flow rate measuring instrument 7, permeable stone 19, drainage channel 14, and water collection device 15. Connect the water flow velocity and flow rate measuring instrument 7 to the equipment control and data acquisition system 2. Turn on switch 6 and turn on air compressor 3 to saturate the soil sample 20. Turn off air compressor 3.

[0033] To test vertical seepage, the water supply device 4, water inlet channel 5, switch 6, water flow velocity and flow rate measuring instrument 7, permeable stone 19, drainage channel 14, and water collection device 15 were connected in sequence. The water flow velocity and flow rate measuring instrument 7 was connected to the equipment control and data acquisition system 2. Switch 6 was turned on, and air compressor 3 was turned on to saturate the soil sample 20. Air compressor 3 was then turned off.

[0034] The vertical servo motor 25 is activated to apply a normal load to the soil sample. The horizontal servo motor 21 is activated to apply a horizontal pushing force to the lower shear box 16 at the required shear rate, conducting a shear-seepage test between the geosynthetic material 12 and the soil. During the test, the data acquisition system can record all test data in real time, including shear force, shear displacement, normal load, vertical displacement of the soil, horizontal inlet water velocity and flow rate, horizontal outlet water velocity and flow rate, vertical inlet water velocity and flow rate, and vertical outlet water velocity and flow rate.

[0035] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A geosynthetic-soil interface multi-directional seepage direct shear test device, characterized in that, It includes a frame, a seepage system, a horizontal shear system, a normal loading system, and an equipment control and data acquisition system. The horizontal shear system and the normal loading system are respectively installed on the frame; the equipment control and data acquisition system is connected to control the seepage system, the horizontal shear system, and the normal loading system respectively. The horizontal shearing system includes an upper shear box and a lower shear box installed on a slide rail. The upper and lower shear boxes contain soil samples and a rigid foundation with a water outlet channel in the middle, respectively. Geosynthetic material is placed on the top surface of the rigid foundation, and the left and right ends of the geosynthetic material are fixed by serrated geosynthetic material fixing plates.

2. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 1, characterized in that, The serrated geosynthetic fixing plate is installed on the frame.

3. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 1, characterized in that, The slide rails are provided in multiple sections and are installed side by side on the horizontal plate inside the frame.

4. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 1, characterized in that, The seepage system includes an air compressor connected to a water supply device, which is connected to the top and inner sides of the upper shear box via an inlet channel. The seepage system also includes a water collection device, which is connected to the inner side of the upper shear box and the outlet channel of the rigid foundation in the lower shear box via a drainage channel.

5. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 4, characterized in that, The water inlet channel and the water outlet channel are respectively equipped with switches and water flow velocity and flow rate measuring instruments.

6. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 5, characterized in that, Permeable stones are provided at the contact points between the water inlet channel and the drainage channel and the upper shear box.

7. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 5, characterized in that, The water flow velocity and flow rate measuring instrument is connected to the equipment control and data acquisition system.

8. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 4, characterized in that, The air compressor, water supply device, water inlet channel, drainage channel, and water collection device are each provided in two sets.

9. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 1, characterized in that, The horizontal shearing system also includes a horizontal servo motor, which is horizontally loaded on one side of the lower shear box via a force transmission rod. A horizontal displacement sensor is installed on one side of the lower shear box, and a horizontal load sensor is installed on one side of the upper shear box. The horizontal displacement sensor and the horizontal load sensor are respectively connected to the equipment control and data acquisition system.

10. The geosynthetic-soil interface multi-directional seepage direct shear test device as described in claim 1, characterized in that, The normal loading system includes a vertical servo motor installed in the frame. The vertical servo motor acts on the pressure cap on the upper part of the soil sample in the upper shear box through a force transmission rod. A vertical load sensor is installed on the force transmission rod, and a vertical displacement sensor is installed on the pressure cap. The vertical load sensor and the vertical displacement sensor are respectively connected to the equipment control and data acquisition system.

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