Indoor test device and test method for simulating seepage erosion of soil-structure interface

Abstract

The invention discloses an indoor test device and a test method for simulating soil-structure interface seepage erosion, and belongs to the field of hydraulic structure and interface seepage damage simulation. The device comprises a seepage chamber, a structural interface module, a test soil body, a graduated scale, a pressure measuring pipe, a particle filter sieve, a drainage funnel, a water receiving container, a weighing device, a water supply tank, a water storage tank 19, a variable-height bracket and a water pump. The device adopts a double-outlet design to respectively measure the seepage flow at the soil body and the interface, and is matched with the four pressure measuring pipes to monitor the water pressure change at different positions in real time, so that the interface seepage characteristics can be accurately obtained, and the test error is effectively reduced. The three side faces of the seepage chamber are covered with the flexible rubber films and coated with vaseline, it is ensured that the seepage channel is only formed in the preset structural face, interference of the boundary effect on the test result is avoided, and the test precision is improved.

Description

Technical Field

[0001] This invention relates to the field of simulation of seepage failure of hydraulic structures and interfaces, and in particular to an experimental device for studying the seepage erosion mechanism of soil-structure interface, specifically a soil-structure interface seepage erosion experimental device with replaceable structural interface and controllable roughness. Background Technology

[0002] Seepage erosion at the soil-structure interface is a crucial and pervasive scientific problem in geotechnical engineering, directly impacting the long-term safety and stability of many critical infrastructure projects such as dams, tunnels, slopes, and diaphragm walls. Under the continuous action of seepage forces, fine particles in the soil migrate and are lost along the soil-structure interface, leading to deterioration of the interface contact properties and the formation of dominant seepage channels. This process significantly reduces the shear strength of the interface, causing uneven settlement, decreased bearing capacity, and even potentially catastrophic instability and failure. Current experimental research on the mechanism of interfacial seepage erosion mainly relies on indoor model tests to analyze the effects of different hydraulic gradients, interfacial roughness, and soil properties on seepage failure. However, existing experimental devices and technologies have several limitations that urgently need to be addressed.

[0003] First, the simulation capability of interface roughness is insufficient. In real engineering, the surface roughness of structures such as culverts, concrete linings, and sheet piles varies greatly, and roughness is a key factor controlling the initiation and development of interface erosion. Most existing experimental devices use fixed, uniform structural surfaces (such as smooth steel plates or standard sandpaper), making it difficult to flexibly and accurately simulate such complex and varied natural or artificial roughness. Although some studies have attempted to change roughness through manual grooving or surface sandblasting, these methods are inefficient and cannot guarantee the consistency and repeatability of roughness between different tests, seriously affecting the scientific validity and comparability of the experimental results. Second, traditional molds often use embedded structural surfaces, resulting in large fitting errors between the mold structural surface and the sample. Gaps or gaps are easily formed at the joints, leading to localized dominant seepage channels and thus increasing the experimental seepage flow. Finally, existing devices have significant experimental errors. Many devices require additional clamps or assembly steps to achieve contact between the soil and the structural surface, inevitably introducing additional contact interfaces that are not intended for the experiment. These additional interfaces may themselves become potential seepage paths or particle aggregation areas, interfering with the real soil-structure interface seepage field, resulting in distortion of the monitored erosion rate, effluent turbidity, and pore pressure data, and failing to accurately reflect the true seepage characteristics of the interface area.

[0004] Therefore, there is an urgent need for a test mold with modular replaceable structure, precise control of interface roughness, and significant reduction of systematic errors. This would reduce the systematic errors caused by the test device itself at the source, thereby deepening the research on the seepage erosion mechanism of the soil-structure interface and improving the reliability of test data. Summary of the Invention

[0005] To address the shortcomings of existing soil-structure interface seepage erosion testing devices, this application provides an indoor testing device and method for soil-structure interface seepage erosion with interchangeable structural surfaces and controllable roughness achieved through 3D printing. This device, through modular structural surface design and 3D printing technology, enables rapid switching and precise control of interface conditions, significantly improving test repeatability and measurement accuracy.

[0006] The technical solution of the present invention:

[0007] An indoor test apparatus for simulating seepage erosion at the soil-structure interface includes a seepage chamber 1, a structural interface module 3, a test soil 4, a scale 7, a pressure measuring tube 8, a particle filter 9, a drainage funnel 11, a water receiving container 12, a weighing device 13, a water supply tank 15, a water storage tank 19, a variable height support 20, and a water pump 18.

[0008] The seepage chamber 1 is filled from bottom to top with a gravel cushion layer 21, a porous plate 5, and test soil 4. The gravel cushion layer 21 and the porous plate 5 are used to evenly distribute the fluid and support the test soil 4. The top of the seepage chamber 1 is provided with a test soil drainage outlet 2 and a structural surface drainage outlet 26. The two are responsible for transporting water to different drainage funnels 11 and filtering it through a particle filter screen 9. The test soil drainage outlet 2 is located at the top edge of the seepage chamber 1, and the structural surface drainage outlet 26 is located at the top edge of the structural interface module 3. The particle filter sieve 9 is disposed inside the drainage funnel 11 and is installed on the support 10 together with the drainage funnel 11. The water receiving container 12 is located below the drainage funnel 11 and is placed on the weighing device 13. One side of the seepage chamber 1 is detachable and can be replaced with the structural interface module 3 during use. The bottom of the seepage chamber 1 is provided with an inlet 22, which is connected to the outlet 14 at the bottom of the water supply tank 15 through a conduit 6. The upper part of the water supply tank 15 is provided with an overflow port 17 and a water inlet 16. The water inlet 16 is connected to the water pump 18. The water pump 18 is installed inside the water storage tank 19 and is responsible for transporting water to the upper water supply tank 15 to realize a closed-loop water supply system, thereby ensuring stable test flow and sustainable operation. The overflow port 17 is connected to the water storage tank 19. The other side of the seepage chamber 1 has n holes spaced equally from top to bottom, each connected to n conduits 6. The conduits 6 are connected to n vertically parallel pressure measuring pipes 8, and the liquid level is recorded using a scale 7. The weighing device 13 is used to record the mass of water flowing out within a certain time. The water supply tank 15 can be adjusted in height using a variable height bracket 20.

[0009] Furthermore, the structural interface module 3 is made using 3D printing technology. The surface roughness can be quantitatively controlled according to the design parameters and the point cloud data is calculated by MATLAB software. Then, it is drawn into a 3D image in COMSOL Multiphysics and finally made using 3D printing technology.

[0010] Furthermore, a flexible rubber membrane 23 is installed between the three sides of the seepage chamber 1 (excluding the structural interface module 3) and the test soil 4, and Vaseline 24 is applied to the flexible rubber membrane 23 to increase the sealing of the interface, ensuring that the seepage channel is formed only at the structural surface and reducing test errors. Furthermore, the weighing device 13 is connected to a computer, and weight-grabbing software is used to monitor mass changes in real time.

[0011] The indoor test method for simulating seepage erosion at the soil-structure interface includes:

[0012] S1. Install the water supply system: Fill the water storage tank 19 with a certain amount of water, put the water pump 18 in, connect the water pump 18 to the water inlet 16 of the water supply tank 15, and connect the overflow outlet 17 to the water storage tank 19.

[0013] S2. Install the water pressure control system: Place the water supply tank 15 above the variable height bracket 20 and fix it. Connect the outlet 14 to the inlet 22 on the seepage chamber 1.

[0014] S3. Install the quality monitoring system: Place the particle filter screen 9 inside the drainage funnel 11, and then install the whole system on the bracket 10. Place the water receiving container 12 and the weighing device 13 directly below the drainage funnel. Finally, connect the weighing device 13 to the computer.

[0015] S4. Laying gravel cushion layer 21: Gravel is evenly laid at the bottom of seepage chamber 1, and the surface is kept flat.

[0016] S5. Install perforated plate 5: The perforated plate 5 is laid on the upper part of the gravel cushion layer 21;

[0017] S6. Install structural interface module 3;

[0018] S7. Install pressure measuring tubes 8: Drill a hole at intervals on one side of the seepage chamber 1, and connect the pressure measuring tubes 8 to the holes using the guide tube 6. The n pressure measuring tubes 8 should be placed parallel and at the same height, and a scale 7 should be placed next to them.

[0019] S8, Sealing of seepage chamber 1: A flexible rubber film 23 is laid on the three sides of seepage chamber 1, except for the structural interface module 3. The flexible rubber film 23 and seepage chamber 1 are glued together. A thin layer of petroleum jelly 24 is applied to the surface of the flexible rubber film 23 for sealing.

[0020] S9, Fill test soil 4;

[0021] S10. The test soil drainage outlet 2 and the interface drainage outlet 26 at the top of the seepage chamber 1 are connected to their respective quality monitoring devices.

[0022] S11. Gradual increase of water head: Adjust the height of the upstream water head by adjusting the height of the variable height support 20, and start the seepage scouring test;

[0023] S12. Record the pore pressure changes at different locations inside the test soil 4 under different water head conditions by measuring the height changes of the liquid in n pressure measuring tubes 8.

[0024] S13. Monitor the evolution of seepage flow at the soil and interface based on the real-time mass change of the weighing device 13.

[0025] S14. Based on the obtained experimental data, the experimental results are theoretically analyzed in conjunction with Darcy's law and Forchheimer's equation. The global average hydraulic gradient, local hydraulic gradient, flow rate and velocity at the interface are studied and analyzed under different roughness conditions of the soil-structure interface.

[0026] In summary, this application includes at least one of the following beneficial effects:

[0027] 1. Precise control and rapid replacement of soil-structure interface roughness were achieved. By using 3D printing technology to manufacture structural interface modules, surface roughness can be precisely controlled according to design parameters, and rapid switching between interfaces with different roughnesses can be achieved through modular design, greatly improving the flexibility and efficiency of the experiment.

[0028] 2. Significantly improved the accuracy and reliability of experimental data. The device employs a dual-outlet design to measure seepage flow at the soil and interface separately, and, in conjunction with four piezometers, monitors water pressure changes at different locations in real time, enabling precise acquisition of interfacial seepage characteristics and effectively reducing experimental errors.

[0029] 3. The isolation and control of the seepage channels were optimized. By covering the three sides of the seepage chamber with a flexible rubber film and applying petroleum jelly, it was ensured that the seepage channels formed only at the preset structural surfaces, avoiding the interference of boundary effects on the test results and improving the accuracy of the test.

[0030] 4. Automated monitoring and data acquisition of the experimental process were achieved. The weighing device is connected to a computer to record mass changes in real time and can automatically acquire key parameters such as seepage flow rate and seepage velocity, greatly improving the efficiency and accuracy of data acquisition.

[0031] 5. A comprehensive research apparatus for soil-structure interface seepage erosion is provided. This apparatus can simulate seepage erosion processes under different interface roughness conditions, providing an effective experimental means for studying the influence of interface roughness on seepage erosion mechanisms, and has significant theoretical and engineering application value. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the indoor test apparatus and test method for simulating soil-structure interface seepage erosion as described in this application;

[0033] Figure 2 This is a schematic diagram of different roughness structural surface modules of the indoor test apparatus and test method for simulating seepage erosion at the soil-structure interface as described in this application.

[0034] Figure 3 This is a schematic diagram of the structural surface module installation of the indoor test apparatus and test method for simulating soil-structure interface seepage erosion as described in this application;

[0035] Figure 4 This is a schematic diagram of the porous plate and gravel cushion layer laying for the indoor test apparatus and test method for simulating soil-structure interface seepage erosion as described in this application.

[0036] Figure 5 This is a schematic diagram of the seepage chamber seal and test soil of the indoor test apparatus and test method for simulating soil-structure interface seepage erosion as described in this application;

[0037] Figure 6 This is a flowchart of the indoor test apparatus and test method for simulating seepage erosion at the soil-structure interface as described in this application;

[0038] In the diagram: 1. Seepage chamber; 2. Drainage outlet of test soil; 3. Structural surface module; 4. Test soil; 5. Porous plate; 6. Guide tube; 7. Ruler; 8. Pressure measuring tube; 9. Granular filter screen; 10. Support; 11. Drainage funnel; 12. Water receiving container; 13. Weighing device; 14. Water outlet; 15. Water supply tank; 16. Water inlet; 17. Overflow outlet; 18. Water pump; 19. Water storage tank; 20. Variable height support; 21. Gravel cushion layer; 22. Water inlet; 23. Flexible rubber film; 24. Vaseline; 25. Fixing screw; 26. Structural surface drainage outlet. Detailed Implementation

[0039] The experimental models and methods in the embodiments of this application will be described in further detail and completely below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, and not all embodiments. (Refer to...) Figure 1-6 .

[0040] This embodiment provides an indoor test apparatus and method for simulating seepage erosion at the soil-structure interface, including a seepage chamber 1, a test soil drainage outlet 2, a structural surface module 3, test soil 4, a porous plate 5, a guide tube 6, a scale 7, a pressure measuring tube 8, a particle filter 9, a support 10, a drainage funnel 11, a water receiving container 12, a weighing device 13, a water supply tank outlet 14, a water supply tank 15, a water supply tank inlet 16, a water supply tank overflow outlet 17, a water pump 18, a water storage tank 19, a variable height support 20, a gravel cushion layer 21, a seepage chamber inlet 22, a flexible rubber film 23, Vaseline 24, fixing screws 25, and a structural surface drainage outlet 26. The seepage chamber 1 is made of acrylic material and filled with test soil 4. Water flowing through the soil and structural surface is transported to the drainage funnel 11 through two drainage outlets at the top, and then filtered by the particle filter 9. A particle filter sieve 9 is installed inside the drainage funnel 11, and both are mounted on the bracket 10. A replaceable structural interface module 3 is installed on one side of the seepage chamber 1. The structural interface module 3 is connected to the seepage chamber 1 by a sealing ring and fixing screws 25. A gravel cushion layer 21 and a porous plate 5 are set at the bottom of the seepage chamber 1 to evenly distribute the fluid and support the test soil 4. The inlet 22 is connected to the outlet 14. The outlet 16 is located at the bottom of the water supply tank 15. An overflow port 17 and a water inlet 16 are set at the top of the water supply tank 15. The water inlet 16 is connected to the water pump 18, which is installed inside the water storage tank 19 and is responsible for transporting water to the upper water supply tank 15 to realize a closed-loop water supply system, thereby ensuring stable test flow and sustainable operation. Four holes are equally spaced from top to bottom on one side of the seepage chamber 1, which are connected to four conduits 6. The conduits 6 are connected to four parallel pressure measuring tubes 8. The upstream water head height is changed by adjusting the height of the variable height bracket 20, and the weighing device 13 is used to record the mass change of the outflowing water from the interface and soil under different water head heights over a certain period of time.

[0041] In this embodiment, the seepage chamber measures 10cm × 10cm × 25cm. The four pressure measuring holes are located at distances of 0cm, 5cm, 10cm, and 15cm from the bottom of the test soil. A gravel cushion and a porous plate are installed at the bottom of the seepage chamber, with thicknesses of 4cm and 1cm respectively. A 5cm space is reserved at the top of the seepage chamber as a slow-flow zone. To simulate the rapid rise of the dam water level within a short period, this embodiment employs a rapid, small-step rise scheme of 2cm / 10min. The water head height is adjusted using a handle on a variable-height support, and seepage flow and pore pressure data are recorded simultaneously. The specific experimental steps are as follows:

[0042] S1. Install the water supply system: Fill the water storage tank 19 with a certain amount of distilled water, put it into the water pump 18, connect the water pump 18 to the water inlet 16 of the water storage tank 15, and connect the overflow outlet 17 to the water storage tank 19.

[0043] S2. Install the water pressure control system: Place the water storage tank 15 above the variable height bracket 20 and fix it with buckles. Connect the water outlet 14 to the water inlet 22 on the seepage chamber 1.

[0044] S3. Install the quality monitoring system: Place the particle filter screen 9 inside the drainage funnel 11, and then install the whole system on the bracket 10. Place the water receiving container 12 and the weighing device 13 directly below the drainage funnel, and then connect the weighing device 13 to the computer.

[0045] S4. Laying a gravel cushion layer 21: Use gravel with a particle size of 2cm to evenly lay at the bottom of the seepage chamber 1, with a thickness of about 4cm, and ensure that the surface is flat.

[0046] S5. Install the perforated plate 5: Use a 1mm diameter hole punch to evenly drill holes in the perforated plate 5, and lay the entire perforated plate 5 flat with a thickness of 1cm.

[0047] S6. Install structural surface module 3: Structural surface module 3 is 10cm wide and 15cm high. Drill holes at the four corners and install it on the seepage chamber 1 with fixing screws 25. Apply a thin layer of waterproof silicone sealant to the contact surface.

[0048] S7. Install pressure measuring tubes 8: Drill a hole every 5cm on the right side of the seepage chamber 3, and connect the pressure measuring tubes 8 to the holes using the guide tube 6. The four pressure measuring tubes 8 should be placed parallel and at the same height, and a scale 7 should be placed next to them.

[0049] S8. Sealing of seepage chamber 1: A flexible rubber film 23 is laid on the three sides of seepage chamber 1, excluding the structural interface module 3. The flexible rubber film 23 and seepage chamber 1 are glued together. A 2mm thick layer of petroleum jelly 24 is applied to the surface of the flexible rubber film 23 for sealing.

[0050] S9. Filling test soil 4: The filling is done in five stages, with a soil height of 3cm each time. The amount of soil to be used is calculated before filling, and the compaction degree is controlled at 0.95.

[0051] S10. Two holes are made at the top of the seepage chamber 3, namely the soil seepage outlet 2 and the interface seepage outlet 26, and connected to their respective quality measuring devices.

[0052] S11. Gradual increase of water head: Adjust the height of the upstream water head by adjusting the height of the variable height support 20, and start the seepage scouring test;

[0053] S12. By measuring the changes in the height of the liquid in the four pressure measuring tubes 8, record the changes in pore pressure at different locations inside the test soil 4 under different water head conditions.

[0054] S13. Monitor the evolution of seepage flow at the soil and interface based on the real-time mass change of the weighing device 13.

[0055] S14. Based on the obtained experimental data, the experimental results are theoretically analyzed in conjunction with Darcy's law and Forchheimer's equation. The global average hydraulic gradient, local hydraulic gradient, flow rate and velocity at the interface are studied and analyzed under different roughness conditions of the soil-structure interface.

Claims

1. An indoor experimental apparatus for simulating seepage erosion at the soil-structure interface, characterized in that, It includes a seepage chamber (1), a structural interface module (3), a test soil (4), a ruler (7), a pressure measuring tube (8), a particle filter screen (9), a drainage funnel (11), a water receiving container (12), a weighing device (13), a water supply tank (15), a water storage tank (19), a variable height support (20), and a water pump (18). The seepage chamber (1) is filled from bottom to top with a gravel cushion layer (21), a porous plate (5), and test soil (4). The gravel cushion layer (21) and the porous plate (5) are used to evenly distribute the fluid and support the test soil (4). The top of the seepage chamber (1) is provided with a test soil drainage outlet (2) and a structural surface drainage outlet (26). The two are responsible for transporting water to different drainage funnels (11) and filtering it through a particle filter screen (9). The test soil drainage outlet (2) is located at the top edge of the seepage chamber (1), and the structural surface drainage outlet (26) is located at the top edge of the structural interface module (3). The particle filter screen (9) is located inside the drainage funnel (11) and is installed on the support (10) together with the drainage funnel (11). The water receiving container (12) is located below the drainage funnel (11) and is placed on the weighing device (13). One side of the seepage chamber (1) is detachable and can be replaced with the structural interface module (3) when in use. The infiltration chamber (1) is provided with an inlet (22) at the bottom, which is connected to the outlet (14) at the bottom of the water supply tank (15) through a conduit (6); the water supply tank (15) is provided with an overflow port (17) and an injection port (16) at the top; the injection port (16) is connected to a water pump (18); the water pump (18) is installed inside the water storage tank (19) and is responsible for transporting water to the upper water supply tank (15) to realize a closed-loop water supply system, thereby ensuring the stability and reliability of the test flow. Continuous operation; the overflow port (17) is connected to the water storage tank (19); the other side of the seepage chamber (1) has n holes at equal intervals from top to bottom, which are connected to n conduits (6) respectively; the conduits (6) are connected to n vertically parallel pressure measuring tubes (8), and the liquid level is recorded using a ruler (7); the weighing device (13) is used to record the mass of water flowing out within a certain time; the water supply tank (15) can be adjusted in height by a variable height bracket (20).

2. The indoor test apparatus for simulating seepage erosion at the soil-structure interface according to claim 1, characterized in that, The structural interface module (3) is made using 3D printing technology. The surface roughness can be quantitatively controlled according to the design parameters and the point cloud data is calculated by MATLAB software. Then, a 3D image is drawn in COMSOL Multiphysics and finally made using 3D printing technology.

3. The indoor test apparatus for simulating seepage erosion at the soil-structure interface according to claim 1, characterized in that, A flexible rubber film (23) is set between the three sides of the seepage chamber (1) other than the structural interface module (3) and the test soil (4), and Vaseline (24) is applied to the flexible rubber film (23) to increase the sealing of the interface, ensuring that the seepage channel is formed only at the structural surface and reducing the test error; furthermore, the weighing device (13) is connected to a computer and the weight grabbing software is used to monitor the mass change in real time.

4. An indoor test method for simulating soil-structure interface seepage erosion using an indoor test apparatus for simulating soil-structure interface seepage erosion as described in any one of claims 1-3, characterized in that, include: S1. Install the water supply system: Fill the water storage tank (19) with a certain amount of water, put it into the water pump (18), connect the water pump (18) to the water inlet (16) of the water supply tank (15), and connect the overflow outlet (17) to the water storage tank (19). S2. Install water pressure control system: Place the water supply tank (15) above the variable height bracket (20) and fix it. Connect the outlet (14) to the inlet (22) on the seepage chamber (1). S3. Install the quality monitoring system: Place the particle filter screen (9) inside the drainage funnel (11), and then install it on the bracket (10). Place the water receiving container (12) and the weighing device (13) directly below the drainage funnel. Finally, connect the weighing device (13) to the computer. S4. Laying a gravel cushion layer (21): Gravel is evenly laid at the bottom of the seepage chamber (1) and the surface is kept flat. S5. Install the perforated plate (5): The perforated plate (5) is laid on the top of the gravel cushion layer (21); S6. Install the structural interface module (3); S7. Install pressure measuring tubes (8): Drill a hole at intervals on one side of the seepage chamber (1), and connect the pressure measuring tubes (8) to the holes using a conduit (6). The n pressure measuring tubes (8) should be placed parallel and at the same height, and a ruler (7) should be placed next to them. S8, sealing of seepage chamber (1): A flexible rubber film (23) is laid on the three sides of the seepage chamber (1) except for the structural interface module (3). The flexible rubber film (23) and the seepage chamber (1) are glued together. A thin layer of petroleum jelly (24) is applied to the surface of the flexible rubber film (23) for sealing. S9. Filling test soil (4); S10. The test soil drainage outlet (2) and interface drainage outlet (26) at the top of the seepage chamber 1 are connected to their respective quality monitoring devices. S11, gradually raising the water head: by adjusting the height of the variable height support (20), the upstream water head height is adjusted, and the seepage scouring test begins; S12. By measuring the height of the liquid in n pressure measuring tubes (8), record the changes in pore pressure at different locations inside the test soil (4) under different water head conditions. S13. Based on the real-time mass change of the weighing device (13), monitor the evolution of seepage flow at the soil and interface. S14. Based on the obtained experimental data, the experimental results are theoretically analyzed in conjunction with Darcy's law and Forchheimer's equation. The global average hydraulic gradient, local hydraulic gradient, flow rate and velocity at the interface are studied and analyzed under different roughness conditions of the soil-structure interface.

Images