Multi-connected flexible wall permeation equipment and method for measuring permeability coefficient

Abstract

The invention relates to the technical field of penetration testing, and provides multi-connected flexible wall penetration equipment and a method for measuring a penetration coefficient. The equipment comprises a pressure control system, a gas-water conversion system and a plurality of flexible wall penetration testing systems. The pressure control system is provided with a first pressure passage and a second pressure passage, the first pressure passage outputs gas confining pressure, and the second pressure passage outputs gas osmotic pressure. And the gas-water conversion system is communicated with the second pressure passage and is used for converting the gas osmotic pressure into water osmotic pressure. The plurality of flexible wall penetration testing systems are communicated with the first pressure passage and the gas-water conversion system and are used for converting the gas confining pressure into water confining pressure and performing penetration testing on the plurality of samples under the consistent water confining pressure and water penetration pressure. According to the invention, synchronous and efficient penetration testing of a plurality of samples under the simulated actual stress condition is realized, and the device is especially suitable for low-permeability materials requiring accurate pressure gradient control and field stress condition simulation.

Description

Technical Field

[0001] The present application relates to the technical field of penetration testing, and in particular to a multi-connected flexible wall penetration device and a method for measuring the permeability coefficient. Background Art

[0002] Solidified soil is a hard soil material with high strength and low permeability, and is widely used in engineering such as contaminated site disposal, landfills, sewage treatment plants, hydraulic dams, and foundation pit retaining. The determination of the permeability performance of solidified soil is crucial for ensuring the safety and quality of the project. Accurately measuring the permeability coefficient of solidified soil can not only evaluate its anti-seepage performance, but also provide a scientific basis for engineering design, thereby effectively reducing environmental risks and resource waste.

[0003] Traditional rigid wall permeameters can apply pressure to the specimen through a fixed container and measure the seepage water volume. However, the rigid wall permeameter has the problem of side wall leakage, and the measurement time is long, making it difficult to simulate the true stress state of the specimen, resulting in inaccurate measurement results.

[0004] Although the flexible wall permeameter overcomes some defects of the rigid wall permeameter, since only a single specimen can be processed in one test, the efficiency is low, and the operation errors between different tests may affect the consistency and reliability of the data.

[0005] In the related art, a multi-connected flexible wall permeameter can measure multiple specimens simultaneously. However, it relies on the height difference between the liquid supply pipe and the specimen to provide the osmotic water pressure, so it is difficult to provide sufficient initial hydraulic gradient for hard soil materials such as solidified soil with low permeability. In addition, each connected permeameter usually needs to be equipped with an independent liquid supply pipe, which makes it difficult to keep the osmotic water pressure of each connected permeameter consistent and synchronous. Therefore, how to provide a penetration device that can realize synchronous testing of multiple specimens and provide stable and consistent osmotic water pressure for multiple specimens has become an urgent technical problem to be solved. Summary of the Invention

[0006] In order to solve the problem that it is difficult to provide stable and consistent osmotic water pressure for multiple specimens during multi-specimen penetration testing in the related art, the present application provides a multi-connected flexible wall penetration device and its usage method.

[0007] On the one hand, a multi-connected flexible wall penetration device is provided, including: A pressure control system having a first pressure path and a second pressure path, the first pressure path being configured to output a gas confining pressure, and the second pressure path being configured to output a gas osmotic pressure; A gas-water conversion system communicated with the second pressure path, the gas-water conversion system being configured to convert the gas osmotic pressure into a water osmotic pressure; Multiple flexible-wall permeability test systems, which are connected to the first pressure passage and the gas-water conversion system, are configured to convert the gas confining pressure into water confining pressure and perform permeability tests on multiple specimens under the water confining pressure and the water osmotic pressure.

[0008] With the above technical solution, by providing the gas confining pressure and the gas osmotic pressure respectively through the pressure control system, converting the gas osmotic pressure into water osmotic pressure by using the gas-water conversion system, converting the gas confining pressure into water confining pressure by the flexible-wall permeability test system, and then applying the same water confining pressure and water osmotic pressure to multiple flexible-wall permeability test systems simultaneously, synchronous and efficient permeability tests on multiple specimens under simulated actual stress conditions are achieved, which is especially suitable for low-permeability materials (such as solidified soil) that require precise control of the pressure gradient and simulation of in-situ stress conditions.

[0009] By converting the gas confining pressure into water confining pressure, the flexible-wall permeability test system has more uniform and stable pressure transmission compared with directly using gas as the confining pressure medium, and can transfer the pressure to each surface of the specimen more evenly. Moreover, by realizing the conversion of gas confining pressure to water confining pressure through the permeability test system itself, the system structure is greatly simplified, and the equipment cost and maintenance complexity are significantly reduced.

[0010] Optionally, the multi-unit flexible-wall permeability device further includes: A confining pressure main pipe that connects the first pressure passage to multiple flexible-wall permeability test systems; A permeation gas pipeline that connects the second pressure passage to the gas-water conversion system; A water osmotic pressure main pipe that connects the gas-water conversion system to multiple flexible-wall permeability test systems.

[0011] With the above technical solution, by providing the confining pressure main pipe, the permeation gas pipeline and the water osmotic pressure main pipe, it is ensured that the gas confining pressure and the gas osmotic pressure generated by the pressure control system, as well as the water osmotic pressure generated by the gas-water conversion system, can be stably, evenly and synchronously distributed to each flexible-wall permeability test system, guaranteeing that multiple specimens bear the same pressure boundary conditions during the test and improving the consistency and comparability of the parallel test results.

[0012] Optionally, the pressure control system includes: A gas source; A gas source pipeline that connects the gas source to the pressure control device; A pressure control device, including the first pressure passage and the second pressure passage.

[0013] With the above technical solution, the basic composition of the pressure control system is clarified, that is, a unified gas source supplies the pressure control device through a gas source pipeline, and then the pressure control device divides into two pressure paths. The structure is clear, which is convenient for centralized management and control of the pressure source, and provides a basis for accurately regulating the confining pressure and osmotic pressure.

[0014] Optionally, the first pressure path includes: A confining pressure gas source switch valve configured to control the connection between the first pressure regulating path and the gas source pipeline; A confining pressure regulating valve configured to regulate the confining pressure of the gas; A confining pressure pressure gauge configured to display the value of the confining pressure of the gas; A confining pressure output switch valve configured to control the connection between the first pressure regulating path and the confining pressure main pipeline; Alternatively, the second pressure path includes: An osmotic pressure gas source switch valve configured to control the connection between the second pressure regulating path and the gas source pipeline; An osmotic pressure regulating valve configured to regulate the osmotic pressure of the gas; An osmotic pressure pressure gauge configured to display the value of the osmotic pressure of the gas; An osmotic pressure output switch valve configured to control the connection between the second pressure regulating path and the osmotic pressure pipeline.

[0015] With the above technical solution, the specific control and monitoring components in the pressure path are specified in detail, enabling the operator to accurately open / close the gas source, adjust the pressure value, monitor the pressure reading in real time, and control the output of the pressure to the subsequent pipeline, thereby achieving independent, accurate, and reliable control and monitoring of the confining pressure or osmotic pressure of the gas.

[0016] Optionally, the gas-water conversion system includes: A gas-water conversion chamber, including a conversion chamber cavity, a conversion chamber top cover, and a conversion chamber bottom plate; A water source, which is connected to the gas-water conversion chamber and multiple flexible wall permeability test systems through a water source main pipeline.

[0017] With the above technical solution, the core component (gas-water conversion chamber) of the gas-water conversion system and its physical structure are defined, and the water source and its supply pipeline are clarified. This water source is not only used for gas-water conversion but also for filling water into the flexible wall permeability test system (confining pressure chamber), simplifying the system structure and ensuring the realization of the gas-water conversion function and the need for filling water in the confining pressure chamber.

[0018] Optionally, the conversion chamber top cover includes: A conversion chamber intake valve configured to control the connection between the conversion chamber cavity and the osmotic pressure pipeline; The conversion chamber exhaust valve is configured to control the communication between the conversion chamber cavity and the external air; The conversion chamber water injection valve is configured to control the communication between the conversion chamber cavity and the main water supply pipeline; Alternatively, the conversion chamber bottom plate includes: The conversion chamber water outlet valve is configured to control the communication between the conversion chamber cavity and the osmotic pressure pipeline.

[0019] With the above technical solutions, by setting specific control valves on the gas-water conversion chamber, it is convenient to control the entry of gas, the injection of water, the discharge of air in the chamber, and the output of the osmotic pressure of the converted water, ensuring the operability and reliability of the gas-water conversion process, and facilitating the realization of functions such as initial water filling, exhaust, pressure-bearing conversion, and pressure output of the chamber.

[0020] Optionally, the flexible wall permeability test system includes: The confining pressure chamber includes a confining pressure chamber cavity, a confining pressure chamber top cover, and a confining pressure chamber bottom plate. A specimen base is provided on the confining pressure chamber bottom plate, and the specimen base is configured to carry the specimen; The seepage water collection device is connected to the confining pressure chamber through a drainage pipeline to receive the seepage water flowing out from the specimen.

[0021] With the above technical solutions, the basic unit structure for testing a single specimen is defined, including the confining pressure chamber for applying confining pressure and accommodating the specimen, and the seepage water collection device for measuring the results, constituting a complete flexible wall permeability test functional module, which is convenient for realizing multi-unit arrangement.

[0022] Optionally, a first permeable stone, a first filter paper, the specimen, a second filter paper, a second permeable stone, and a specimen cap are sequentially provided on the specimen base in a direction away from the specimen base, and the outside of the specimen is wrapped with a rubber membrane.

[0023] With the above technical solutions, the flexible wall permeability test specimen installation method is adopted. The permeable stone and filter paper are used to ensure uniform water flow into and out of the specimen and prevent soil particles from flowing out, while the rubber membrane effectively isolates the specimen from the confining pressure medium in the confining pressure chamber, preventing side wall leakage, ensuring that the seepage water completely passes through the inside of the specimen, and guaranteeing the accuracy of the measurement of the permeability coefficient.

[0024] Optionally, the confining pressure chamber top cover includes: The confining pressure chamber three-way valve is configured to control the communication between the confining pressure chamber cavity and the main confining pressure pipeline and the external air; Alternatively, the confining pressure chamber bottom plate includes: The osmotic pressure switch valve is configured to control the communication between the specimen base and the main water osmotic pressure pipeline; The confining pressure chamber inlet valve is configured to control the connection between the confining pressure chamber cavity and the main water source pipeline; The seepage water valve is configured to control the connection between the specimen cap and the drainage pipeline.

[0025] With the above technical solutions, each test system is equipped with independent control valves, which can precisely control the application and release of the confining pressure of the unit (through the three-way air valve), the filling of water in the confining pressure chamber cavity (through the inlet valve), the on-off of the osmotic water pressure (through the osmotic pressure switch valve), and the collection of seepage water (through the seepage water valve), making the operation of each test unit more flexible, independent, and precise.

[0026] On the other hand, a method for measuring the permeability coefficient using the multi-connected flexible wall permeation device is provided, including: Setting specimens wrapped with rubber membranes in multiple confining pressure chambers; Generating gas confining pressure and gas osmotic pressure through a pressure control system; Outputting the gas confining pressure to multiple confining pressure chambers through the main confining pressure pipeline to drive the water in the confining pressure chamber to apply water confining pressure to the specimen; Converting the gas osmotic pressure into water osmotic pressure through a gas-water conversion system and applying the water osmotic pressure to the specimen through the main water osmotic pressure pipeline; Collecting and measuring the amount of seepage water seeping out from the specimen through a seepage water collection device; Determining the permeability coefficient of the specimen according to the amount of seepage water.

[0027] With the above technical solutions, a complete and standardized operation process is provided. Using the multi-connected flexible wall permeation device, the application of confining pressure and osmotic pressure to multiple specimens is synchronized, the amount of seepage water is independently measured, and the final permeability coefficient is calculated, ensuring the high efficiency, accuracy, and repeatability of the test process, and is particularly suitable for materials such as solidified soil that require simulating in-situ stress and precisely measuring low permeability.

[0028] In summary, the present application includes at least one of the following beneficial technical effects: 1. By setting a pressure control system to provide gas confining pressure and gas osmotic pressure respectively, using a gas-water conversion system to convert the gas osmotic pressure into water osmotic pressure, and then applying the gas confining pressure and water osmotic pressure to multiple flexible wall permeation test systems simultaneously, synchronous and efficient permeation tests on multiple specimens under simulated actual stress conditions are realized, especially suitable for low-permeability materials (such as solidified soil) that require precise control of the pressure gradient and simulation of in-situ stress conditions; 2. The flexible wall permeability testing system will convert the gas confining pressure into water confining pressure. Compared with directly using gas as the confining pressure medium, the pressure transmission is more uniform and stable, and it can transfer the pressure to each surface of the specimen more evenly. Moreover, through the permeability testing system itself, the conversion from gas confining pressure to water confining pressure is realized, greatly simplifying the system structure and significantly reducing the equipment cost and maintenance complexity. 3. Each testing system is equipped with an independent control valve, which can precisely control the application and release of the unit confining pressure (through a three-way air valve), the filling of water in the confining pressure chamber cavity (through a water inlet valve), the on-off of the osmotic water pressure (through an osmotic pressure switch valve), and the collection of the seepage water (through a seepage water valve), making the operation of each testing unit more flexible, independent, and precise. 4. A complete and standardized operation process is provided. Using the multi-unit flexible wall permeability equipment, the application of confining pressure and osmotic pressure, the independent measurement of the seepage water volume, and the calculation of the final permeability coefficient are realized for multiple specimens simultaneously, ensuring the high efficiency, accuracy, and repeatability of the testing process. It is especially suitable for materials such as solidified soil that require simulating in-situ stress and precisely measuring low permeability. Description of the Drawings

[0029] Figure 1 is a schematic structural diagram of the multi-unit flexible wall permeability equipment of the embodiment of the present application; Figure 2 is Figure 1 a schematic structural diagram of the pressure control system in Figure 3 is Figure 1 a schematic structural diagram of the gas-water conversion system in Figure 4 is Figure 1 a schematic structural diagram of the flexible wall permeability testing system in Figure 5 is a schematic flow diagram of the method for measuring the permeability coefficient using the multi-unit flexible wall permeability equipment of the embodiment of the present application.

[0030] Description of the reference numerals: 110, pressure control system; 120, gas-water conversion system; 130, flexible wall permeability testing system; 140, confining pressure main pipe; 150, permeation gas pipeline; 160, water osmotic pressure main pipe; 170, specimen; 210, gas source; 220, gas source pipeline; 230, pressure control device; 241, confining pressure gas source switch valve; 242, confining pressure regulating valve; 243, confining pressure pressure gauge; 244, confining pressure output switch valve; 251, osmotic pressure gas source switch valve; 252, osmotic pressure regulating valve; 253, osmotic pressure pressure gauge; 254, osmotic pressure output switch valve; 310, gas-water conversion chamber; 320, water source; 330, conversion chamber cavity; 340, conversion chamber top cover; 350, conversion chamber bottom plate; 360, conversion chamber tie rod; 321, water source main pipeline; 341, conversion chamber intake valve; 342, conversion chamber exhaust valve; 343, conversion chamber water injection valve; 351, conversion chamber water outlet valve; 410, confining pressure chamber; 420, seepage water collection device; 430, confining pressure chamber cavity; 440, confining pressure chamber top cover; 450, confining pressure chamber bottom plate; 460, specimen base; 470, confining pressure chamber tie rod; 480, drainage pipeline; 441, confining pressure chamber three-way valve; 451, osmotic pressure switch valve; 452, confining pressure chamber water inlet valve; 453, seepage water valve; 461, first permeable stone; 462, second permeable stone; 463, specimen cap. Detailed implementation manners

[0031] The following is a further detailed description of the present application in conjunction with Figure 1 - Figure 5 this application.

[0032] An embodiment of the present application discloses a multi-connected flexible wall permeation device, including: A pressure control system 110 having a first pressure path and a second pressure path, the first pressure path being configured to output a gas confining pressure, and the second pressure path being configured to output a gas osmotic pressure; A gas-water conversion system 120 communicated with the second pressure adjustment path, the gas-water conversion system 120 being configured to convert the gas osmotic pressure into a water osmotic pressure; A plurality of flexible wall permeability testing systems 130 communicated with the first pressure adjustment path and the gas-water conversion system 120, the flexible wall permeability testing system 130 being configured to convert the gas confining pressure into a water confining pressure and perform a permeability test on a specimen 170 under the water confining pressure and the water osmotic pressure.

[0033] Figure 1 is a schematic structural diagram of the multi-connected flexible wall permeation device according to the embodiment of the present application. Refer to Figure 1, the multi - unit flexible - wall permeability device includes a pressure control system 110, a gas - water conversion system 120, multiple flexible - wall permeability test systems 130, a confining pressure main pipe 140, a permeation gas pressure pipeline 150, and a water osmotic pressure main pipe 160, where a specimen 170 can be accommodated in the flexible - wall permeability test system 130.

[0034] The pressure control system 110 generates a first - path gas for outputting gas confining pressure and a second - path gas for outputting gas osmotic pressure. The first - path gas outputs the gas confining pressure into the confining pressure main pipe 140, and the second - path gas outputs the gas osmotic pressure into the permeation gas pressure pipeline 150. The gas - water conversion system 120 is connected to the permeation gas pressure pipeline 150 and the water osmotic pressure main pipe 160, where the gas - water conversion system 120 converts the gas osmotic pressure into water osmotic pressure and outputs the water osmotic pressure to the water osmotic pressure main pipe 160. Each flexible - wall permeability test system 130 is connected to the confining pressure main pipe 140 and the water osmotic pressure main pipe 160, and converts the gas confining pressure into water confining pressure, so that the specimen 170 in each flexible - wall permeability test system 130 can conduct a permeability test under consistent water confining pressure and water osmotic pressure.

[0035] Figure 2 is Figure 1 a schematic structural diagram of the pressure control system 110 in. Refer to Figure 2 , the pressure control system 110 includes a gas source 210, a gas source pipeline 220, and a pressure control device 230. The pressure control device 230 has a first pressure - regulating path (not shown in the figure) for regulating and controlling the gas confining pressure and a second pressure - regulating path (not shown in the figure) for regulating and controlling the gas osmotic pressure.

[0036] The gas source 210 can be a gas source device such as an air compressor or an air compression pump. The gas generated by it enters the pressure control device 230 through the gas source pipeline 220 and then enters the first pressure - regulating path and the second pressure - regulating path. The gas source pipeline 220 can be a steel pipe, a copper pipe, or a non - metallic flexible hose. The pressure control device 230 can control gas distribution and can adopt a mechanical or hydraulic control cabinet.

[0037] On the first pressure regulating path, in the flowing direction of the first path of gas, there are successively arranged a confining pressure gas source switch valve 241, a confining pressure regulating valve 242, a confining pressure pressure gauge 243, and a confining pressure output switch valve 244, which are connected to the confining pressure main pipe 140. Among them, the confining pressure gas source switch valve 241 is used to control the connection between the first pressure regulating path and the gas source pipeline 220, the confining pressure regulating valve 242 is used to regulate the confining pressure of the gas, the confining pressure pressure gauge 243 is used to display the value of the confining pressure of the gas, and the confining pressure output switch valve 244 is used to control the connection between the first pressure regulating path and the confining pressure main pipe 140.

[0038] On the second pressure regulating path, in the flowing direction of the second path of gas, there are successively arranged an osmotic pressure gas source switch valve 251, an osmotic pressure regulating valve 252, an osmotic pressure pressure gauge 253, and an osmotic pressure output switch valve 254, which are connected to the osmotic pressure pipeline 150. Among them, the osmotic pressure gas source switch valve 251 is used to control the connection between the second pressure regulating path and the gas source pipeline 220, the osmotic pressure regulating valve 252 is used to regulate the osmotic pressure of the gas, the osmotic pressure pressure gauge 253 is used to display the value of the osmotic pressure of the gas, and the osmotic pressure output switch valve 254 is used to control the connection between the second pressure regulating path and the osmotic pressure pipeline 150.

[0039] Among them, the gas source switch valve and the output switch valve can be ball valves, gate valves or butterfly valves, etc. The regulating valve can use a spring-loaded regulating valve or an electronic regulating valve, and the pressure gauge can be a mechanical or digital pressure gauge. Each component is connected through pipelines to achieve the distribution and control of the gas source.

[0040] Figure 3 is Figure 1 a schematic structural diagram of the gas-water conversion system 120 in. Refer to Figure 3 , the gas-water conversion system 120 includes a gas-water conversion chamber 310 and a water source 320. The gas-water conversion chamber 310 includes a conversion chamber cavity 330, a conversion chamber top cover 340, and a conversion chamber bottom plate 350. The conversion chamber cavity 330, the conversion chamber top cover 340, and the conversion chamber bottom plate 350 can be tightly fixed by conversion chamber tie rods 360. Among them, the conversion chamber cavity 330, the conversion chamber top cover 340, and the conversion chamber bottom plate 350 can be made of metal materials such as stainless steel and aluminum alloy, or can be made of non-metal materials such as high-strength plastics. The conversion chamber tie rods 360 can be metal rods or high-strength fiber rods.

[0041] A conversion chamber inlet valve 341, a conversion chamber exhaust valve 342, and a conversion chamber water injection valve 343 are provided at the top cover 340 of the conversion chamber. A conversion chamber outlet valve 351 is provided at the bottom plate 350 of the conversion chamber. The water source 320 is communicated with the conversion chamber water injection valve 343 through a total water source pipeline 321. The conversion chamber inlet valve 341 is communicated with the osmotic pressure pipeline 150. The conversion chamber outlet valve 351 is communicated with the total water osmotic pressure pipeline 160. Among them, the conversion chamber inlet valve 341, the conversion chamber exhaust valve 342, and the conversion chamber water injection valve 343 can be manual valves or automatic valves, and the conversion chamber outlet valve 351 can be a ball valve or a needle valve.

[0042] Among them, the water source 320 is communicated with the conversion chamber water injection valve 343 through the total water source pipeline 321 to fill water into the conversion chamber cavity 330. At this time, the conversion chamber exhaust valve 342 is opened to discharge the air in the conversion chamber cavity 330 during water filling. The osmotic pressure pipeline 150 outputs gas osmotic pressure, and the gas osmotic pressure enters the conversion chamber cavity 330 through the conversion chamber inlet valve 341 to drive the water in the conversion chamber cavity 330, so as to convert the gas osmotic pressure into water osmotic pressure. The conversion chamber outlet valve 351 is communicated with the total water osmotic pressure pipeline 160 to output the water osmotic pressure to the total water osmotic pressure pipeline 160.

[0043] Figure 4 is Figure 1 a schematic structural diagram of the flexible wall permeability test system 130 in. Refer to Figure 4 , the flexible wall permeability test system 130 includes a confining pressure chamber 410 and a seepage water collection device 420. The confining pressure chamber 410 includes a confining pressure chamber cavity 430, a confining pressure chamber top cover 440, and a confining pressure chamber bottom plate 450. A specimen base 460 is provided on the confining pressure chamber bottom plate 450. The confining pressure chamber cavity 430, the confining pressure chamber top cover 440, and the confining pressure chamber bottom plate 450 can be tightened and fixed through confining pressure chamber tie rods 470. The seepage water flowing out of the confining pressure chamber 410 can enter the seepage water collection device 420 through a drainage pipeline 480.

[0044] The specimen base 460 is used to carry the specimen 170. Among them, a first permeable stone 461, a first filter paper (not shown in the figure), the specimen 170, a second filter paper (not shown in the figure), a second permeable stone 462, and a specimen cap 463 are sequentially arranged along the direction away from the specimen base 460. The outside of the specimen 170 is wrapped with a rubber membrane (not shown in the figure), and the rubber membrane is sealed and fixed on the specimen base 460 and the specimen cap 463. Optionally, the specimen base 460 and the confining pressure chamber bottom plate 450 are integrated.

[0045] Among them, the rubber membrane can be fixed on the specimen base 460 and the specimen cap 463 through rubber rings. The specimen base 460 can be made of metal or non-metal materials and has good corrosion resistance. The first permeable stone 461 and the second permeable stone 462 can be natural stones or synthetic materials, and the first filter paper and the second filter paper can be qualitative filter paper or quantitative filter paper. The specimen 170 can be solidified soil or other hard materials. The rubber membrane can be a natural rubber membrane or a synthetic rubber membrane, and the rubber ring can be an ordinary rubber ring or a specially made high-strength rubber ring.

[0046] A three-way air valve 441 for the confining pressure chamber is provided at the top cover 440 of the confining pressure chamber, and the three-way air valve 441 for the confining pressure chamber is communicated with the confining pressure main pipe 140. An osmotic pressure switch valve 451, a confining pressure chamber water inlet valve 452 and a seepage water outlet valve 453 are provided at the bottom plate 450 of the confining pressure chamber. The osmotic pressure switch valve 451 is communicated with the water osmotic pressure main pipe 160. The confining pressure chamber water inlet valve 452 is communicated with the water source main pipeline 321, and the seepage water outlet valve 453 is communicated with the specimen cap 463 and the drainage pipeline 480. The seepage water collection device 420 is communicated with the drainage pipeline 480.

[0047] Among them, the water source 320 is communicated with the confining pressure chamber water inlet valve 452 through the water source main pipeline 321 to fill water into the confining pressure chamber cavity 430, so that the water level height in the confining pressure chamber cavity 430 is higher than the upper surface height of the specimen cap 463. At this time, the three-way air valve 441 for the confining pressure chamber is communicated with the air to discharge the air in the confining pressure chamber cavity 430 during water filling.

[0048] The confining pressure main pipe 140 provides gas confining pressure, and the gas confining pressure enters the confining pressure chamber cavity 430 through the three-way air valve 441 for the confining pressure chamber to drive the water in the confining pressure chamber cavity 430 to apply confining pressure to the specimen 170.

[0049] The water osmotic pressure main pipe 160 provides water osmotic pressure. The osmotic water enters the specimen base 460 through the osmotic pressure switch valve 451, and sequentially seeps through the first permeable stone 461, the first filter paper, the specimen 170, the second filter paper, the second permeable stone 462, and oozes out from the specimen cap 463. The seepage water oozing out from the specimen cap 463 is communicated with the drainage pipeline 480 through the seepage water outlet valve 453 and flows into the seepage water collection device 420 through the drainage pipeline 480.

[0050] The implementation principle of a multi-connected flexible wall penetration device according to an embodiment of the present application is as follows: 1. The multi - unit flexible - wall permeation device includes multiple of the flexible - wall permeation test systems 130, that is, it has multiple confining - pressure chambers 410 and multiple seepage - water collection devices 420. Each confining - pressure chamber 410 is communicated with the first - pressure path of the pressure control system 110 through the confining - pressure main pipe 140, so that multiple flexible - wall permeation test systems 130 share the gas confining - pressure of the same pipeline, and the flexible - wall permeation test system 130 converts the gas confining - pressure into water confining - pressure to ensure the confining - pressure consistency of multiple flexible - wall permeation test systems 130.

[0051] 2. By converting the gas osmotic pressure through the gas - water conversion system 120 to generate water osmotic pressure, it can meet the water - osmotic - pressure requirements for hard - soil materials such as solidified soil with low permeability.

[0052] 3. Each confining - pressure chamber 410 is communicated with the gas - water conversion system 120 through the water - osmotic - pressure main pipe 160, so that multiple flexible - wall permeation test systems 130 share the water osmotic pressure of the same pipeline to ensure the water - osmotic - pressure consistency of multiple flexible - wall permeation test systems 130.

[0053] The embodiments of the present application also disclose a method for measuring the permeability coefficient using the multi - unit flexible - wall permeation device, including the following steps: Set specimens 170 wrapped with rubber membranes in multiple confining - pressure chambers 410; Generate gas confining - pressure and gas osmotic pressure through the pressure control system 110; Apply the gas confining - pressure to multiple confining - pressure chambers 410 through the confining - pressure main pipe 140; Convert the gas osmotic pressure into water osmotic pressure through the gas - water conversion system 120, and apply the water osmotic pressure to the specimen 170 through the water - osmotic - pressure main pipe 160; Collect and measure the seepage water volume seeping out from the specimen 170 through the seepage - water collection device 420; Determine the permeability coefficient of the specimen 170 according to the seepage water volume.

[0054] Refer to Figure 5 , the method for measuring the permeability coefficient using the multi - unit flexible - wall permeation device includes the following steps: S1. Fill water into the conversion - chamber cavity 330 of the gas - water conversion chamber 310.

[0055] S2. Conduct water - flushing and air - exhausting for multiple seepage pipelines.

[0056] S3. Respectively set specimens 170 wrapped with rubber membranes on multiple specimen bases 460.

[0057] S4. Set up the confining pressure chamber cavities 430 and the confining pressure chamber top covers 440 on the bottom plates 450 of multiple confining pressure chambers.

[0058] S5. Fill water into the multiple confining pressure chamber cavities 430.

[0059] S6. Output gas confining pressure into the multiple confining pressure chambers 410 through the confining pressure main pipe 140 to drive the water in the confining pressure chambers 410 to apply water confining pressure to the specimen 170.

[0060] S7. Convert gas osmotic pressure into water osmotic pressure through the gas-water conversion system 120, and apply the water osmotic pressure to the multiple specimens 170 through the water osmotic pressure main pipe 160.

[0061] S8. Respectively collect and measure the seepage water volume seeping out from the specimen 170 through multiple seepage water collection devices 420, and determine the permeability coefficient of the specimen 170 according to the seepage water volume.

[0062] In step S1, fill water into the conversion chamber cavity 330 of the gas-water conversion chamber 310. Among them, open the conversion chamber exhaust valve 342 and the conversion chamber water injection valve 343, and fill water into the conversion chamber cavity 330 from the water source 320 through the water source main pipeline 321. When the water level reaches 80% - 90% of the volume of the conversion chamber cavity 330, stop filling water, and close the conversion chamber water injection valve 343 and the conversion chamber exhaust valve 342. Subsequently, according to the measurement conditions and the remaining water volume in the conversion chamber cavity 330, water can also be replenished into the conversion chamber cavity 330 according to the above process.

[0063] In step S2, conduct water passing and air exhausting for multiple seepage pipelines. Among them, open the osmotic pressure switch valve 451 and the seepage water valve 453 located at the bottom plate 450 of the confining pressure chamber, pass water to the specimen base 460 through the natural water head of the gas-water conversion chamber 310, and pass water through the drainage hole of the specimen cap 463 through the suction ball, so that the air bubbles in the above seepage pipelines are discharged to inhibit air resistance, and then close the osmotic pressure switch valve 451 and the seepage water valve 453.

[0064] In step S3, respectively set specimens 170 wrapped with rubber membranes on multiple specimen bases 460. Among them, sequentially set a first permeable stone 461, a first filter paper, the specimen 170, a second filter paper, a second permeable stone 462, and a specimen cap 463 on the specimen base 460. Put the rubber membrane into the membrane support cylinder, turn out both ends outside the cylinder, inhale air from the air suction hole of the membrane support barrel, so that the rubber membrane fits tightly against the inner wall of the membrane support cylinder, put it outside the specimen 170, release the air, turn up both ends of the rubber membrane, and take out the membrane support cylinder. Tie both ends of the rubber membrane to the specimen base 460 and the specimen cap 463 respectively with rubber bands.

[0065] In step S4, a confining pressure chamber cavity 430 (which can be a cylinder without a top surface and a bottom surface) and a confining pressure chamber top cover 440 are respectively arranged on the bottom plates 450 of multiple confining pressure chambers. Among them, the confining pressure chamber cavity 430, the confining pressure chamber top cover 440 and the confining pressure chamber bottom plate 450 are tightened and fixed by a confining pressure chamber tie rod 470.

[0066] In step S5, water is filled into multiple confining pressure chamber cavities 430. Among them, the three-way air valve 441 at the confining pressure chamber top cover 440 is communicated with air, and the confining pressure chamber water inlet valve 452 at the confining pressure chamber bottom plate 450 is opened and communicated with the main water source pipeline 321. After the water is filled into the confining pressure chamber cavity 430 from the water source 320 to a certain height above the upper surface of the specimen cap 463, the confining pressure chamber water inlet valve 452 is closed.

[0067] In step S6, a gas confining pressure is output into multiple confining pressure chambers 410 through a confining pressure main pipe 140 to drive the water in the confining pressure chamber 410 to apply a water confining pressure to the specimen 170. Among them, the three-way air valve 441 of the confining pressure chamber is communicated with the confining pressure main pipe 140, the confining pressure gas source switch valve 241 and the confining pressure output switch valve 244 of the pressure control device 230 are opened, the confining pressure regulating valve 242 is adjusted, and the confining pressure pressure gauge 243 is observed to adjust the confining pressure to a preset value. The magnitude of the gas confining pressure is determined according to the effective stress actually borne by the specimen 170.

[0068] In step S7, the gas osmotic pressure is converted into a water osmotic pressure through a gas-water conversion system 120, and the water osmotic pressure is applied to multiple specimens 170 through a water osmotic pressure main pipe 160. Among them, the conversion chamber air inlet valve 341 located at the conversion chamber top cover 340, the conversion chamber water outlet valve 351 located at the conversion chamber bottom plate 350 and the osmotic pressure switch valve 451 located at the confining pressure chamber bottom plate 450 are opened, the osmotic pressure gas source switch valve 251 and the osmotic pressure output switch valve 254 of the pressure control device 230 are opened, the osmotic pressure regulating valve 252 is adjusted, and the osmotic pressure pressure gauge 253 is observed to adjust the osmotic pressure to a preset value. In order to ensure that the rubber mold outside the specimen 170 is in close contact with the specimen 170 and avoid leakage from the side wall of the specimen 170, the osmotic pressure needs to be less than the confining pressure. Preferably, the osmotic pressure is 20 - 50 kPa less than the confining pressure.

[0069] S8. The seepage water collection devices 420 respectively collect and measure the seepage water volume seeping out from the specimen 170, and determine the permeability coefficient of the specimen 170 according to the seepage water volume. Among them, open the seepage water valve 453 located at the bottom plate 450 of the confining pressure chamber, read and record the weighed mass of the seepage water collection device 420, and record the water temperature. The seepage water volume is determined according to the weighed mass reading of the seepage water collection device 420 and the density of water. The time interval of reading can be determined according to the seepage water volume of the specimen 170. For specimens with a larger seepage water volume, readings can be taken every 3 - 5 minutes, and for specimens with a smaller seepage water volume, readings can be taken every 30 - 60 minutes. Each specimen needs to measure at least 6 data, and the measurement duration should be determined according to the stability of the seepage water volume. When the difference in the permeability coefficient calculated from the seepage water volume is not greater than 2×10 -n , the measurement can be stopped.

[0070] Among them, the specific data processing process includes: determining the head difference Δh according to the ratio of the applied osmotic pressure p to the unit weight γ of water w of water, and calculating the permeability coefficient k according to Darcy's law; converting the permeability coefficient k to the permeability coefficient k 20 at the standard temperature (20°C) according to the measured water temperature; selecting multiple (for example, 3 to 4) data results with similar values and within the allowable difference range from the test data results, and finding their average value, and taking this average value as the permeability coefficient of this solidified soil specimen under specific conditions. Among them, the allowable difference shall not exceed 2×10 -n .

[0071] The implementation principle of the method for measuring the permeability coefficient using the multi - type flexible - wall permeation device in the embodiments of the present application is as follows: A complete and standardized operation process is provided. By using the multi - type flexible - wall permeation device, the application of confining pressure and osmotic pressure, the independent measurement of seepage water volume, and the calculation of the final permeability coefficient are realized for multiple specimens synchronously, ensuring the high efficiency, accuracy, and repeatability of the test process, and being particularly suitable for materials such as solidified soil that require simulating in - situ stress and accurately measuring low permeability.

[0072] The above are all preferred embodiments of the present application. The protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A multi-connected flexible wall infiltration device, characterized in that: include: A pressure control system (110) having a first pressure passage and a second pressure passage, wherein the first pressure passage is configured to output a gas confining pressure, and the second pressure passage is configured to output a gas osmotic pressure; A gas-water conversion system (120) is in communication with the second pressure passage, and the gas-water conversion system (120) is configured to convert the gas osmotic pressure into water osmotic pressure; A plurality of flexible wall penetration test systems (130) are connected to the first pressure passage and the gas-water conversion system (120), and the plurality of flexible wall penetration test systems (130) are used to convert the gas confining pressure into a water confining pressure, and to perform penetration tests on a plurality of samples (170) under the water confining pressure and the water osmotic pressure.

2. The multi-connected flexible wall permeation device according to claim 1, characterized in that: Also includes: A confining pressure main pipe (140) connecting the first pressure passage with the plurality of flexible wall permeability testing systems (130); A permeate gas pressure pipeline (150) connecting the second pressure passage with the gas-water conversion system (120); The water osmotic pressure main pipe (160) connects the gas-water conversion system (120) with the plurality of flexible wall permeation test systems (130).

3. The multi-connected flexible wall permeation device according to claim 2, characterized in that: The pressure control system (110) comprises: Gas source (210); An air source pipeline (220) connecting the air source (210) with the pressure control device (230); The pressure control device (230) comprises the first pressure passage and the second pressure passage.

4. The multi-connected flexible wall permeation device according to claim 3, characterized in that: The first pressure path comprises: A confining pressure gas source switch valve (241) configured to control the communication between the first pressure regulating passage and the gas source pipeline (220); A confining pressure regulating valve (242), configured to regulate the confining pressure of the gas; A confining pressure gauge (243), configured to display the value of the gas confining pressure; a confining pressure output switch valve (244), configured to control the communication between the first pressure regulating passage and the confining pressure main pipe (140); Alternatively, the second pressure path comprises: an osmotic pressure gas source switch valve (251), configured to control the communication between the second pressure regulating passage and the gas source pipeline (220); an osmotic pressure regulating valve (252), configured to adjust the gas osmotic pressure; an osmotic pressure gauge (253), configured to display a numerical value of the gas osmotic pressure; The osmotic pressure output switch valve (254) is configured to control the communication between the second pressure regulating passage and the osmotic gas pressure pipeline (150).

5. The multi-connected flexible wall permeation device according to claim 2, characterized in that: The gas-water conversion system (120) comprises: The gas-water conversion chamber (310) comprises a conversion chamber cavity (330), a conversion chamber top cover (340) and a conversion chamber bottom plate (350); A water source (320) is connected to the gas-water conversion chamber (310) and the plurality of flexible wall permeability testing systems (130) through a water source main pipeline (321).

6. The multi-connected flexible wall permeation device according to claim 5, characterized in that: The conversion chamber top cover (340) comprises: A conversion chamber air inlet valve (341), configured to control the communication between the conversion chamber cavity (330) and the permeate gas pressure pipeline (150); A conversion chamber exhaust valve (342), configured to control the communication between the conversion chamber cavity (330) and external air; A conversion chamber water injection valve (343) configured to control the communication between the conversion chamber cavity (330) and the water source main pipeline (321); Alternatively, the conversion chamber bottom plate (350) comprises: The conversion chamber water outlet valve (351) is configured to control the communication between the conversion chamber cavity (330) and the permeate gas pressure pipeline (150).

7. The multi-connected flexible wall permeation device according to claim 5, characterized in that: The flexible wall penetration testing system (130) comprises: A confining pressure chamber (410), comprising a confining pressure chamber cavity (430), a confining pressure chamber top cover (440) and a confining pressure chamber bottom plate (450), wherein a sample base (460) is provided on the confining pressure chamber bottom plate (450), and the sample base (460) is configured to carry the sample (170); The seepage water collecting device (420) is connected to the confining pressure chamber (410) through a drainage pipeline (480) to receive the seepage water flowing out of the sample (170).

8. The multi-connected flexible wall permeation device according to claim 7, characterized in that: A first permeable stone, a first filter paper, the sample (170), a second filter paper, a second permeable stone (462) and a sample cap (463) are arranged in sequence on the sample base (460) in a direction away from the sample base (460), wherein the outside of the sample (170) is wrapped with a rubber film.

9. The multi-connected flexible wall permeation device according to claim 8, characterized in that: The confining pressure chamber top cover (440) comprises: A confining pressure chamber three-way air valve (441) configured to control the communication between the confining pressure chamber cavity (430), the confining pressure main pipe (140) and external air; Alternatively, the confining pressure chamber bottom plate (450) comprises: An osmotic pressure switch valve (451) configured to control the communication between the sample base (460) and the water osmotic pressure main pipe (160); A confining pressure chamber water inlet valve (452) configured to control the communication between the confining pressure chamber cavity (430) and the water source main pipeline (321); The seepage valve (453) is configured to control the communication between the sample cap (463) and the drainage pipeline (480).

10. A method for measuring permeability coefficient using the multi-connected flexible wall permeation device according to any one of claims 1 to 9, comprising: A sample (170) wrapped with a rubber membrane is arranged in a plurality of confining pressure chambers (410); generating a gas confining pressure and a gas osmotic pressure by a pressure control system (110); Outputting the gas confining pressure into the plurality of confining pressure chambers (410) through a confining pressure main pipe (140) to drive the water in the confining pressure chambers (410) to apply water confining pressure to the sample (170); converting the gas osmotic pressure into water osmotic pressure through a gas-water conversion system (120), and applying the water osmotic pressure to the sample (170) through a water osmotic pressure main pipe (160); collecting and measuring the amount of seepage water seeping from the sample (170) by means of a seepage water collecting device (420); The permeability coefficient of the sample (170) is determined according to the amount of seepage water.

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