Foam fluid inhibits soil permeability damage test device and test method thereof

Abstract

The application discloses a kind of foam fluid inhibits soil body permeability damage test device and its test method, the device includes main structure, variable head control unit, pore pressure monitoring unit, computer analysis unit, foam fluid injection unit, foam fluid injection unit includes liquid input module, gas input module, foam generator, liquid input module and gas input module are connected with foam generator, and foam generator output end is connected with main structure;The test method includes assembling device, fills sand sample in sand tank, and carries out test by injecting foam fluid into sand tank;Water head is promoted gradually, and after seepage is stabilized, next stage water head test is carried out, and the change process of the permeability damage area of sand sample top surface and the change of foam fluid occurrence range are recorded, and pore pressure monitoring unit is used to monitor the pore pressure in sand sample in real time, when permeability damage area and water inlet chamber are connected, stop test.The application can be used to verify and evaluate the effect of foam fluid inhibiting soil body permeability damage.

Description

Technical Field

[0001] This invention relates to soil seepage failure testing, and in particular to a foam fluid-based soil seepage failure testing device and testing method. Background Technology

[0002] How to scientifically prevent seepage failure is a pressing problem in levee engineering. The commonly used experimental method in existing technologies is the variable head seepage test. During the test, the water head is gradually increased, and the inflow, sand inflow, and piezometric head at different locations are observed and recorded to obtain the critical head for seepage failure. However, existing technologies cannot meet the experimental requirements of quantitatively injecting multiphase seepage fluids into the test soil layer to inhibit soil seepage failure, and soil pore pressure monitoring systems are not suitable for multiphase seepage systems. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide a foam fluid inhibition soil seepage damage test device and test method that is simple to operate, easy to maintain, and capable of monitoring the inhibitory effect of foam fluid on soil seepage damage.

[0004] Technical Solution: To achieve the above objectives, the foam fluid inhibition soil seepage failure test device of the present invention includes a main structure for soil seepage failure testing, a variable head control unit for water inlet and outlet, a pore pressure monitoring unit for monitoring the pressure of the main structure, and a computer analysis unit for analyzing the monitored pressure data. Its characteristic is that it further includes a foam fluid injection unit, which includes a liquid input module, a gas input module, and a foam generator. The output ends of the liquid input module and the gas input module are connected to the input end of the foam generator, and the foam fluid generated by the foam generator is injected into the main structure.

[0005] The main structure includes: an inlet chamber, an outlet chamber, and a sand trough. The inlet chamber and outlet chamber are respectively located on both sides of the sand trough. A porous baffle is installed between the inlet chamber, outlet chamber, and sand trough to prevent sand particles from being lost. At the same time, silicone pads are installed on both sides of the porous baffle. The inlet chamber, outlet chamber, sand trough, porous baffle, and silicone pads are tightened and fixed together by bolts and nuts.

[0006] The sand tank is equipped with a transparent top plate, and a silicone pad is placed between the transparent top plate and the sand tank. The sand tank is fixed by bolts and nuts. A sand outlet is provided on the side of the transparent top plate near the water outlet chamber. A sand tank for collecting sand generated by infiltration is attached to the sand outlet. The top of the sand tank is equipped with a drain hole and is connected to the water tank of the variable head control unit through a water pipe. A foam fluid injection hole is provided on the side of the transparent top plate near the water inlet chamber. A pressure monitoring hole is provided at the front end of the sand tank.

[0007] The water tanks of the variable head control unit include: an upstream water tank, a first downstream water tank, and a second downstream water tank. The upstream water tank is connected to the inlet of the inlet chamber, the first downstream water tank is connected to the drain hole on the top of the sand tank, and the second downstream water tank is connected to the outlet of the outlet chamber.

[0008] The pore pressure monitoring unit is equipped with a pore pressure sensor corresponding to the pressure monitoring hole. The sensor is connected to the pressure monitoring hole through a wire, and the signal collected by the sensor is transmitted to the computer analysis unit.

[0009] The liquid input module includes a horizontal flow pump and a piston container. The input end of the piston container is connected to the horizontal flow pump, and its output end is connected to the input end of the foam generator.

[0010] The gas input module is equipped with the following components in sequence: gas cylinder, first pressure gauge, pressure regulating valve, second pressure gauge, filter, gas flow controller, check valve, back pressure valve, and third pressure gauge, which are then connected to the input terminal of the foam generator.

[0011] A test method using a foam fluid-based test apparatus to inhibit soil seepage failure includes the following steps:

[0012] S1: Assemble the test device, fill the sand sample in layers in the sand tank, inject the pre-made foam fluid into the sand tank, and carry out the penetration damage test;

[0013] S2: Gradually increase the water head of the upstream water tank. After the seepage stabilizes, conduct the next level of water head test. Record the changes in the seepage damage area on the top surface of the sand sample and the changes in the foam fluid distribution range. Stop the test when the seepage damage area is connected to the inlet chamber.

[0014] The S1 assembly of the foam fluid-based soil seepage inhibition test device includes the following sub-steps:

[0015] S101: Apply Vaseline evenly to both sides of the sand tank, assemble the inlet chamber, silicone pad, porous partition, outlet chamber and sand tank, and tighten them with bolts and nuts;

[0016] S102: Connect the pore pressure sensor to the pressure measuring hole at the front end of the sand tank through a conduit, and connect it to the computer analysis unit through a data cable;

[0017] S103: Prepare test sand samples according to particle size distribution and density, and carry out underwater layered filling. After smoothing and compacting the sand samples, place the silicone pad and transparent top plate in sequence, and fix and tighten them with bolts.

[0018] S104: Open the liquid input module and gas input module, and inject the liquid and gas into the foam fluid generator to pre-form foam fluid through the horizontal flow pump and gas flow controller respectively;

[0019] S105: After the foam fluid reaches a dynamic stable state, connect the foam fluid generator to the foam fluid injection hole of the transparent top plate through a conduit, and inject the pre-made foam fluid into the sand tank through the foam injection hole.

[0020] S106: Connect the upstream water tank to the inlet of the inlet chamber, the first downstream water tank to the drain hole on the top of the sand tank, and the second downstream water tank to the outlet of the outlet chamber. Turn on the circulating water system of the variable head control unit to ensure that there is always enough water in the water tank.

[0021] The S2 penetration test includes the following sub-steps:

[0022] S201: Open the inlet and outlet sand outlet to start the seepage destruction test. Gradually increase the water head of the upstream water tank. After the seepage stabilizes, i.e., after multiple measurements of the seepage flow rate are basically stable, and there is no obvious sand movement near the outlet sand outlet and no sand flow out of the sand inrush pipe, proceed to the next level of water head test.

[0023] S202: After the test begins, record the corresponding water inflow and sand inflow at each water head, record the change process of the seepage damage area on the top surface of the sand sample and the change of the foam fluid occurrence range, and collect the pore pressure of the pressure monitoring hole in real time through the pore pressure monitoring unit.

[0024] S203: When the permeation damage area is connected to the inlet chamber, that is, when a channel is created on the top surface of the sand sample in the sand tank, water can enter the inlet chamber through the channel. Stop the test, stop data acquisition, and close all valves.

[0025] S204: After each set of tests, clean and dry the sand sample, and reset the test apparatus.

[0026] Beneficial effects: The present invention has the following advantages: 1. The present invention is multifunctional. When foam fluid is injected into the soil sample through the foam fluid injection hole by the foam fluid injection unit, a foam fluid inhibition soil seepage failure test can be carried out. When the foam fluid injection hole is closed, a traditional soil seepage failure test can be carried out. At the same time, foam fluid can be injected into foam fluid injection holes at different distances from the sand outlet to explore the influence of the foam fluid injection position on its effect on inhibiting the development of seepage failure.

[0027] 2. This invention can explore the diffusion law of foam fluids with different properties in different soils and the effect of inhibiting the development of seepage damage in different soils by changing the type of liquid, the type of gas, the liquid injection flow rate, and the gas injection flow rate;

[0028] 3. This invention modifies the hydraulic gradient in the soil sample by changing the upstream water head, collects inrush sand through an inrush sand tank, and collects inrush water through an outlet. It analyzes the variation law of inrush water and sand volume with hydraulic gradient during the development of soil seepage failure and the critical hydraulic gradient of seepage failure. Based on the evolution process of soil seepage failure area, the variation law of inrush water volume and sand volume, and the critical hydraulic gradient, it analyzes the mechanism of foam fluid inhibiting soil seepage failure.

[0029] 4. This invention uses a transparent top plate to visualize the development process of soil seepage failure, analyzes the evolution law of soil seepage failure area with hydraulic gradient, monitors the pore pressure at different measuring points in the soil in real time through pore pressure sensor, and explores the spatiotemporal variation law of seepage field in soil during the development process of seepage failure under conditions of foam fluid and non-foam fluid.

[0030] 5. This invention adopts a modular splicing design, which allows for adjustment of the model splicing according to the experimental purpose and facilitates equipment maintenance. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the test apparatus of the present invention;

[0032] Figure 2 This is a schematic diagram of the main structure for foam fluid injection according to the present invention;

[0033] Figure 3 This is a flowchart of the test method of the present invention. Detailed Implementation

[0034] The technical solution of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0035] like Figure 1 As shown, the foam fluid inhibition soil seepage failure test device of the present invention includes: a main structure 1, a variable head control unit 2, a pore pressure monitoring unit 3, a computer analysis unit 4, and a foam fluid injection unit 5. The foam fluid injection unit 5 includes: a liquid input module 51, a gas input module 52, and a foam generator 53. The output ends of the liquid input module 51 and the gas input module 52 are connected to the input end of the foam generator 53. The main structure 1 is provided with a foam injection hole 15.2 and a pressure monitoring hole 13.1. The foam fluid generated by the output end of the foam generator 53 is injected into the main structure 1 through the foam injection hole 15.2. The pressure monitoring hole 13.1 is connected to the pore pressure monitoring unit 3 through a wire. The variable head control unit 2 is provided with a water tank. The inlet and outlet of the main structure 1 are connected to the water tank.

[0036] like Figure 2As shown, the main structure 1 includes: an inlet chamber 11, an outlet chamber 12, and a sand trough 13. The inlet chamber 11 is provided with an inlet, and the outlet chamber 12 is provided with an outlet. The inlet chamber 11 and the outlet chamber 12 are respectively placed on both sides of the sand trough 13. A porous baffle 14 is provided between the inlet chamber 11, the outlet chamber 12, and the sand trough 13 to prevent the loss of sand particles. At the same time, silicone pads are provided on both sides of the porous baffle 14. The inlet chamber 11, the outlet chamber 12, the sand trough 13, the porous baffle 14, and the silicone pads are tightened and fixed together by bolts and nuts.

[0037] The water tank of the variable head control unit 2 includes: an upstream water tank 21, a first downstream water tank 22, and a second downstream water tank 23. The upstream water tank 21 is connected to the inlet of the inlet chamber 11, the first downstream water tank 22 is connected to the drain hole at the top of the sand tank 16, and the second downstream water tank 23 is connected to the outlet of the outlet chamber 12.

[0038] A transparent top plate 15 is provided on the sand tank 13, and a silicone gasket is also provided between the transparent top plate 15 and the sand tank 13. It is fixed by bolts and nuts. A sand outlet 15.1 is provided on the transparent top plate 15 near the water outlet chamber 12. A sand tank 16 for collecting sand generated by seepage damage is attached to the sand outlet 15.1. The top of the sand tank 16 is provided with a drain hole and is connected to the water tank of the variable head control unit 2 through a water pipe.

[0039] Three foam fluid injection holes are set on the transparent top plate 15 at positions 5cm, 10cm and 15cm away from the sand outlet 15.1 on the side near the water inlet chamber 11. The foam injection holes are connected to the foam fluid generator 33 through conduits to inject the pre-generated foam fluid into the sand tank 13.

[0040] The front end of the sand tank 13 is equipped with 24 pressure monitoring holes in 3 rows and 8 columns. The top row of pressure monitoring holes is 2cm away from the top plate. The monitoring holes are arranged starting from 10cm away from the water inlet chamber, with a horizontal spacing of 5cm and a vertical spacing of 3cm.

[0041] The pore pressure monitoring unit 3 is equipped with 24 high-precision pore pressure sensors, which correspond one-to-one with the pressure monitoring holes. The sensors are connected to the pressure monitoring holes 13.1 through wires, and the signals collected by the sensors are transmitted to the computer analysis unit 4.

[0042] The liquid input module 51 includes a horizontal flow pump 51.1 and a piston container 51.2. The input end of the piston container 51.2 is connected to the horizontal flow pump 51.1, and its output end is connected to the input end of the foam generator 53. The surfactant solution is stored in the piston container 51.2. The liquid flow rate is controlled by the horizontal flow pump 51.1 to provide the liquid required to generate foam fluid.

[0043] The gas input module 52 is sequentially equipped with: a gas cylinder 52.1, a first pressure gauge 52.2, a pressure regulating valve 52.3, a second pressure gauge 52.4, a filter 52.5, a gas flow controller 52.6, a one-way valve 52.7, a back pressure valve 52.8, and a third pressure gauge 52.9. It is then connected to the input terminal of the foam generator 53. The gas cylinder 52.1 provides the gas required to generate foam fluid. The filter 52.5 filters out any impurities that may be present in the gas. The gas flow controller 52.6 controls the gas flow rate, and the pressure regulating valve 52.3 adjusts the gas output pressure. The pressure gauge monitors the gas output pressure value. The gas and liquid are input into the foam fluid generator 33 through pipelines to generate foam fluid. All components are connected by high-pressure resistant pipelines.

[0044] The computer analysis unit 4 can control the flow rate of the liquid in the piston container 51.2 through the horizontal flow pump 51.1 and monitor the real-time changes in the liquid flow rate. At the same time, it can control the flow rate of the gas in the gas cylinder 52.1 through the gas flow controller 52.6 and monitor the real-time changes in the gas flow rate. The pore pressure analysis unit 5 can analyze the pressure at the monitoring point and the spatiotemporal variation law of the pressure gradient in the device in real time.

[0045] like Figure 3 As shown, a test method using a foam fluid-based soil seepage failure suppression test device includes the following steps:

[0046] Apply Vaseline evenly to both sides of the sand tank 13. Assemble the water inlet chamber 11, silicone pad, porous baffle 14, water outlet chamber 12 and sand tank 13, and tighten them with bolts and nuts. Connect the pore pressure sensor to the pressure measuring hole 13.1 at the front end of the sand tank 13 through a conduit, and connect it to the computer analysis unit 4 through a data cable.

[0047] Test sand samples were prepared according to particle size distribution and density and then poured underwater in layers. After smoothing and compacting the sand samples, the silicone pad and transparent top plate 15 were placed in sequence and fixed and tightened with bolts.

[0048] Open the liquid input module 51 and the gas input module 52, and inject the liquid and gas into the foam fluid generator 33 to pre-form foam fluid through the horizontal flow pump 51.1 and the gas flow controller 52.6 respectively;

[0049] After the foam fluid reaches a dynamic stable state, the foam fluid generator 33 is connected to the foam fluid injection hole 15.2 of the transparent top plate 15 through a conduit, and a certain amount of pre-made foam fluid is injected into the sand tank 13 through the selected foam injection hole 15.2.

[0050] Connect the upstream water tank 21 to the inlet 41.1 of the inlet chamber 11, connect the first downstream water tank 22 to the drain hole at the top of the sand tank 16, connect the second downstream water tank 23 to the outlet of the outlet chamber 12, and turn on the circulating water system of the variable head control unit 2 to ensure that there is always enough water in the tanks.

[0051] Open the inlet and outlet 15.1 to begin the seepage failure test. Gradually increase the water head of the upstream water tank 21. After the seepage stabilizes, the seepage flow rate is basically stable after multiple measurements. There is no obvious sand movement near the outlet 15.1 and no sand flows out of the sand inlet pipe. The water flow is clear. Then proceed to the next level of water head test.

[0052] After the experiment started, the corresponding water inflow and sand inflow were recorded at each water head level. The change process of the seepage damage area on the top surface of the sand sample and the change of the foam fluid occurrence range were also recorded. The pore pressure of the pressure monitoring hole 13.1 was collected in real time through the pore pressure monitoring unit 3.

[0053] When the infiltration damage area is connected to the water inlet chamber 11, that is, a channel is formed on the top surface of the sand sample in the sand tank 13, water can enter the water inlet chamber 11 through the channel, the test is stopped, data acquisition is stopped, and all valves are closed.

[0054] After each set of tests, the sand samples were cleaned and dried, and the test apparatus was reset.

Claims

1. A test method for a foam fluid-based test device for inhibiting soil seepage failure, characterized in that: Includes the following steps: S1: Assemble the test device, fill the sand sample in layers in the sand tank (13), inject the pre-made foam fluid into the sand tank (13), and carry out the penetration damage test; S2: Gradually increase the water head of the upstream water tank (21). After the seepage stabilizes, conduct the next level of water head test, record the change process of the seepage damage area on the top surface of the sand sample and the change of the foam fluid content range. When the seepage damage area is connected to the inlet chamber (11), stop the test. The test apparatus includes a main structure (1) for soil permeability failure test, a variable head control unit (2) for water intake and drainage, a pore pressure monitoring unit (3) for monitoring the pressure of the main structure (1), a computer analysis unit (4) for analyzing the monitored pressure data, and a foam fluid injection unit (5). The foam fluid injection unit (5) includes a liquid input module (51), a gas input module (52), and a foam generator (53). The output ends of the liquid input module (51) and the gas input module (52) are connected to the input end of the foam generator (53). The foam fluid generated by the foam generator (53) is injected into the main structure (1). The main structure (1) includes: an inlet chamber (11), an outlet chamber (12), and a sand trough (13). The inlet chamber (11) and the outlet chamber (12) are respectively placed on both sides of the sand trough (13). A transparent top plate (15) is provided on the sand trough (13). A silicone pad is also provided between the transparent top plate (15) and the sand trough (13). A sand outlet (15.1) is provided on the transparent top plate (15) on the side near the outlet chamber (12). A foam fluid injection hole (15.2) is provided on the transparent top plate (15) on the side near the inlet chamber (11). A pressure monitoring hole (13.1) is provided at the front end of the sand trough (13). The water tank of the variable head control unit (2) includes: an upstream water tank (21), a first downstream water tank (22), and a second downstream water tank (23). The upstream water tank (21) is connected to the inlet of the inlet chamber (11), the first downstream water tank (22) is connected to the drain hole at the top of the sand tank (16), and the second downstream water tank (23) is connected to the outlet of the outlet chamber (12).

2. The test method according to claim 1, characterized in that: A porous baffle (14) is provided between the water inlet chamber (11), the water outlet chamber (12), and the sand trough (13) to prevent the loss of sand particles. At the same time, silicone pads are provided on both sides of the porous baffle (14). The water inlet chamber (11), the water outlet chamber (12), the sand trough (13), the porous baffle (14), and the silicone pads are tightened and fixed together by bolts and nuts.

3. The test method according to claim 2, characterized in that: The transparent top plate (15) and the sand trough (13) and the silicone pad between them are tightened and fixed by bolts and nuts. A sand tank (16) for collecting sand generated by infiltration damage is glued at the sand outlet (15.1). The top of the sand tank (16) is provided with a drain hole and is connected to the water tank of the variable head control unit (2) through a water pipe.

4. The test method according to claim 3, characterized in that: The pore pressure monitoring unit (3) is equipped with a pore pressure sensor corresponding to the pressure monitoring hole (13.1). The sensor is connected to the pressure monitoring hole (13.1) through a wire, and the signal collected by the sensor is transmitted to the computer analysis unit (4).

5. The test method according to claim 4, characterized in that: The liquid input module (51) includes: a horizontal flow pump (51.1) and a piston container (51.2). The input end of the piston container (51.2) is connected to the horizontal flow pump (51.1), and its output end is connected to the input end of the foam generator (53).

6. The test method according to claim 5, characterized in that: The gas input module (52) is provided with the following components in sequence: gas cylinder (52.1), first pressure gauge (52.2), pressure regulating valve (52.3), second pressure gauge (52.4), filter (52.5), gas flow controller (52.6), one-way valve (52.7), back pressure valve (52.8), and third pressure gauge (52.9), and is connected to the input end of foam generator (53).

7. The test method according to claim 6, characterized in that: The S1 assembly of the foam fluid-based soil seepage inhibition test device includes the following sub-steps: S101: Apply Vaseline evenly to both sides of the sand tank (13), assemble the water inlet chamber (11), silicone pad, porous partition (14), water outlet chamber (12) with the sand tank (13), and tighten them with bolts and nuts; S102: Connect the pore pressure sensor to the pressure monitoring hole (13.1) at the front end of the sand tank (13) through a conduit, and connect it to the computer analysis unit (4) through a data cable. S103: Prepare test sand samples according to particle size distribution and density, and carry out underwater layered filling. After smoothing and compacting the sand samples, place the silicone pad and transparent top plate (15) in sequence, and fix and tighten them with bolts. S104: Open the liquid input module (51) and gas input module (52) to inject the liquid and gas into the foam fluid generator (33) through the horizontal flow pump (51.1) and gas flow controller (52.6) respectively to pre-form foam fluid; S105: After the foam fluid reaches a dynamic stable state, connect the foam fluid generator (33) to the foam fluid injection hole (15.2) of the transparent top plate (15) through a conduit, and inject the pre-made foam fluid into the sand tank (13) through the foam injection hole (15.2); S106: Connect the upstream water tank (21) to the inlet of the inlet chamber (11), connect the first downstream water tank (22) to the top drain hole of the sand tank (16), connect the second downstream water tank (23) to the outlet of the outlet chamber (12), and turn on the circulating water system of the variable head control unit (2) so that there is always enough water in the water tank.

8. The test method according to claim 7, characterized in that: The S2 penetration test includes the following sub-steps: S201: Open the inlet and outlet (15.1) to start the seepage failure test. Gradually increase the head of the upstream water tank (21). After the seepage is stable, the seepage flow rate is basically stable after multiple measurements. There is no obvious sand movement near the outlet (15.1) and no sand flows out of the sand inlet pipe. Then proceed with the next head test. S202: After the test begins, record the corresponding water inflow and sand inflow at each water head, record the change process of the seepage damage area on the top surface of the sand sample and the change of the foam fluid occurrence range, and collect the pore pressure of the pressure monitoring hole (13.1) in real time through the pore pressure monitoring unit (3); S203: When the permeation damage area is connected to the water inlet chamber (11), that is, a channel is generated on the top surface of the sand sample in the sand tank (13), and water can enter the water inlet chamber (11) through the channel. Stop the test, stop data acquisition, and close all valves. S204: After each set of tests, clean and dry the sand sample, and reset the test apparatus.

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