Multi-connected flexible wall permeation equipment

Abstract

The utility model relates to the technical field of penetration testing, and provides multi-connected flexible wall penetration equipment which 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 permeation testing, in particular to a multi-connection flexible wall permeation device. BACKGROUND

[0002] Solidified soil is a hard soil material with high strength and low permeability, which is widely used in contaminated site disposal, landfill, sewage treatment plant, water conservancy dam and foundation pit support engineering. The determination of the permeability of solidified soil is crucial to ensure the safety and quality of the project. Accurate determination of the permeability coefficient of solidified soil not only can evaluate its impermeability, but also can provide scientific basis for engineering design, thereby effectively reducing environmental risk and resource waste.

[0003] The traditional rigid wall permeameter can apply pressure to the sample by a fixed container and measure the seepage water. However, the rigid wall permeameter has the problem of side wall leakage, and the measurement time is long, which is difficult to simulate the true stress state of the sample, resulting in inaccurate measurement results.

[0004] Although the flexible wall permeameter overcomes some of the defects of the rigid wall permeameter, it can only handle a single sample at a time, which is low in efficiency, and the operation error between different tests may affect the consistency and reliability of the data.

[0005] In related technologies, the multi-connection flexible wall permeameter can measure multiple samples at the same time, but it relies on the height difference between the liquid supply pipe and the sample to provide the permeation 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 permeameter usually needs to be equipped with an independent liquid supply pipe, which makes it difficult to keep the permeation water pressure of each permeameter consistent and synchronized. Therefore, how to provide a permeation device that can realize synchronous testing of multiple samples and provide stable and consistent permeation water pressure for multiple samples has become a technical problem to be solved. SUMMARY

[0006] In order to solve the problem that related technologies are difficult to provide stable and consistent permeation water pressure for multiple samples during multi-sample permeation testing, the present application provides a multi-connection flexible wall permeation device and a use method thereof.

[0007] The present application provides a multi-connection flexible wall permeation device, comprising:

[0008] 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 permeation pressure;

[0009] A gas-water conversion system in communication with the second pressure path, the gas-water conversion system being configured to convert the gas permeation pressure into a water permeation pressure;

[0010] a plurality of flexible wall permeation test systems in communication with the first pressure pathway and the gas-to-water conversion system, the plurality of flexible wall permeation test systems being configured to convert the gas confining pressure to a water confining pressure and to perform permeation tests on a plurality of samples under the water confining pressure and the water permeation pressure.

[0011] By providing the gas confining pressure and the gas permeation pressure by the pressure control system, and converting the gas permeation pressure to the water permeation pressure by the gas-to-water conversion system, and converting the gas confining pressure to the water confining pressure by the flexible wall permeation test system, and applying the same water confining pressure and water permeation pressure to the plurality of flexible wall permeation test systems, the simultaneous and efficient permeation tests on the plurality of samples under the simulated actual stress conditions are realized, which is especially suitable for the low-permeability materials (such as solidified soil) that need to precisely control the pressure gradient and simulate the field stress conditions.

[0012] By converting the gas confining pressure to the water confining pressure by the flexible wall permeation test system, the pressure transmission is more uniform and stable compared to directly using the gas as the confining pressure medium, and the pressure can be more uniformly transmitted to each surface of the sample. Moreover, the conversion of the gas confining pressure to the water confining pressure is realized by the permeation test system itself, which greatly simplifies the system structure and greatly reduces the equipment cost and maintenance complexity.

[0013] Optionally, the multi-connected flexible wall permeation equipment further comprises:

[0014] a confining pressure header in communication with the first pressure pathway and the plurality of flexible wall permeation test systems;

[0015] a permeation gas pressure pipeline in communication with the second pressure pathway and the gas-to-water conversion system;

[0016] a water permeation pressure header in communication with the gas-to-water conversion system and the plurality of flexible wall permeation test systems.

[0017] By providing the confining pressure header, the permeation gas pressure pipeline and the water permeation pressure header, it is ensured that the gas confining pressure and the gas permeation pressure generated by the pressure control system, and the water permeation pressure generated by the gas-to-water conversion system, can be stably, uniformly and synchronously distributed to each flexible wall permeation test system, which ensures that the plurality of samples bear the same pressure boundary conditions during the test, and improves the consistency and comparability of the parallel test results.

[0018] Optionally, the pressure control system comprises:

[0019] a gas source;

[0020] a gas source pipeline in communication with the gas source and the pressure control device;

[0021] The pressure control device comprises the first pressure passage and the second pressure passage.

[0022] The technical scheme makes clear the basic components of the pressure control system, i.e., the pressure control device is supplied with pressure by a unified gas source through a gas source pipeline, and then two pressure passages are branched out from the pressure control device, which is clear in structure and convenient for centralized management and control of the pressure source, and provides a basis for accurate regulation and control of confining pressure and osmotic pressure.

[0023] Optionally, the first pressure passage comprises:

[0024] The confining pressure gas source on-off valve is configured to control the communication of the first pressure regulating passage with the gas source pipeline;

[0025] The confining pressure pressure regulating valve is configured to regulate the gas confining pressure;

[0026] The confining pressure pressure gauge is configured to display the numerical value of the gas confining pressure;

[0027] The confining pressure output on-off valve is configured to control the communication of the first pressure regulating passage with the confining pressure header;

[0028] Alternatively, the second pressure passage comprises:

[0029] The osmotic pressure gas source on-off valve is configured to control the communication of the second pressure regulating passage with the gas source pipeline;

[0030] The osmotic pressure pressure regulating valve is configured to regulate the gas osmotic pressure;

[0031] The osmotic pressure pressure gauge is configured to display the numerical value of the gas osmotic pressure;

[0032] The osmotic pressure output on-off valve is configured to control the communication of the second pressure regulating passage with the osmotic pressure pipeline.

[0033] The technical scheme makes clear the specific control and monitoring elements in the pressure passage, so that the operator can accurately open / close the gas source, regulate the pressure value, monitor the pressure reading in real time, and control the output of the pressure to the subsequent pipeline, thereby realizing independent, accurate and reliable control and monitoring of the gas confining pressure or the gas osmotic pressure.

[0034] Optionally, the gas-water conversion system comprises:

[0035] The gas-water conversion chamber comprises a conversion chamber cavity, a conversion chamber top cover and a conversion chamber bottom plate;

[0036] The water source is communicated with the gas-water conversion chamber and the plurality of flexible wall permeation test systems through a water source header pipeline.

[0037] The technical scheme is characterized in that the core component (a gas-water conversion chamber) of the gas-water conversion system and the physical structure thereof are defined, and the water source and the supply pipeline thereof are also defined, the water source being used not only for gas-water conversion but also for water filling of a flexible wall permeation test system (an encircled pressure chamber), so that the system structure is simplified, and the realization of the gas-water conversion function and the need of water filling of the encircled pressure chamber are ensured.

[0038] Optionally, the top cover of the conversion chamber comprises:

[0039] The conversion chamber gas inlet valve is configured to control the communication between the conversion chamber cavity and the permeation gas pressure pipeline.

[0040] The conversion chamber gas outlet valve is configured to control the communication between the conversion chamber cavity and the external air.

[0041] The conversion chamber water injection valve is configured to control the communication between the conversion chamber cavity and the water source main pipeline.

[0042] Optionally, the bottom plate of the conversion chamber comprises:

[0043] The conversion chamber water outlet valve is configured to control the communication between the conversion chamber cavity and the permeation gas pressure pipeline.

[0044] The technical scheme is characterized in that specific control valves are arranged on the gas-water conversion chamber, so that the gas inlet, water injection, air outlet in the cavity and the output of the permeation pressure of the converted water can be conveniently controlled, the operability and reliability of the gas-water conversion process are ensured, and the functions of the cavity initialization water filling, air exhaust, pressure conversion and pressure output are facilitated.

[0045] Optionally, the flexible wall permeation test system comprises:

[0046] The encircled pressure chamber comprises an encircled pressure chamber cavity, an encircled pressure chamber top cover and an encircled pressure chamber bottom plate, wherein the encircled pressure chamber bottom plate is provided with a sample base configured to load the sample.

[0047] The exuded water collecting device is in communication with the encircled pressure chamber through a drainage pipeline to receive the exuded water from the sample.

[0048] The technical scheme is characterized in that the basic unit structure for single sample test is defined, including the encircled pressure chamber for applying encircled pressure and containing the sample and the exuded water collecting device for measuring the result, which constitutes a complete flexible wall permeation test function module and facilitates the realization of multi-connection arrangement.

[0049] Optionally, the encircled pressure chamber bottom plate and the sample base are integrated.

[0050] By adopting the technical scheme, the connection and assembly links between separate components are reduced by integrating the confining pressure chamber bottom plate and the sample base, thereby improving the rigidity and stability of the overall structure; potential gaps or connection interfaces between the bottom plate and the base are eliminated, the sealing performance of the system is enhanced, and the system is more reliable when bearing confining pressure; meanwhile, the manufacturing and installation process is simplified, and accurate fixing and alignment of the sample bearing position relative to other interfaces (such as the water inlet valve and the osmotic pressure switch valve) of the bottom plate can be ensured.

[0051] Optionally, a first water-permeable stone, a first filter paper, the sample, a second filter paper, a second water-permeable stone, and a sample cap are sequentially arranged on the sample base in a direction away from the sample base, and the sample is wrapped with a rubber film.

[0052] By adopting the technical scheme, the flexible wall permeation test sample installation method is adopted, the water-permeable stone and the filter paper are used to ensure uniform water inflow and outflow of the sample and prevent soil particles from being lost, and the rubber film effectively isolates the sample from the confining pressure medium in the confining pressure chamber to prevent side wall leakage, so that the permeation water flow completely passes through the inside of the sample, and the accuracy of the permeability coefficient measurement is ensured.

[0053] Optionally, the confining pressure chamber top cover comprises:

[0054] The confining pressure chamber three-way valve is configured to control the communication of the confining pressure chamber cavity with the confining pressure main pipe and external air;

[0055] Alternatively, the confining pressure chamber bottom plate comprises:

[0056] The osmotic pressure switch valve is configured to control the communication of the sample base with the water osmotic pressure main pipe;

[0057] The confining pressure chamber water inlet valve is configured to control the communication of the confining pressure chamber cavity with the water source main pipeline;

[0058] The effusion water valve is configured to control the communication of the sample cap with the drainage pipeline.

[0059] By adopting the technical scheme, each test system is provided with independent control valves, the application and removal of confining pressure of the unit (through the three-way valve), the water filling of the confining pressure chamber cavity (through the water inlet valve), the on-off of the osmotic water pressure (through the osmotic pressure switch valve), and the collection of effusion water (through the effusion water valve) can be accurately controlled, so that the operation of each test unit is more flexible, independent, and accurate.

[0060] In summary, the present application has at least one of the following beneficial technical effects:

[0061] 1. By setting up a pressure control system to provide gas confining pressure and gas permeation pressure respectively, and using a gas-water conversion system to convert the gas permeation pressure into water permeation pressure, and then applying the gas confining pressure and water permeation pressure to multiple flexible wall permeation test systems at the same time, the simultaneous and efficient permeation test of multiple samples under simulated actual stress conditions is realized, which is especially suitable for low permeability materials (such as solidified soil) that need to accurately control the pressure gradient and simulate the field stress conditions.

[0062] 2. Compared with directly using gas as confining pressure medium, the flexible wall permeation test system can more uniformly and stably transmit pressure to each surface of the sample by converting the gas confining pressure into water confining pressure, and the conversion of gas confining pressure into water confining pressure is realized by the permeation test system itself, which greatly simplifies the system structure and greatly reduces the equipment cost and maintenance complexity.

[0063] 3. Each test system is equipped with independent control valves, which can accurately control the application and removal of the unit confining pressure (through a three-way air valve), the water filling of the confining pressure chamber cavity (through a water inlet valve), the on-off of the permeation water pressure (through a permeation pressure switch valve), and the collection of the exuded water (through an exuded water valve), making the operation of each test unit more flexible, independent and accurate.

[0064] 4. A complete and standardized operation process is provided, which uses the multi-connected flexible wall permeation equipment to realize the simultaneous application of confining pressure and permeation pressure to multiple samples, independent measurement of exuded water volume, and calculation of the final permeability coefficient, ensuring the efficiency of the test process, the accuracy and repeatability of the results, and being especially suitable for solidified soil and other materials that need to simulate field stress and accurately measure low permeability. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 is a structural schematic diagram of the multi-connected flexible wall permeation equipment of the embodiment of the present application;

[0066] Figure 2 is a structural schematic diagram of the pressure control system in Figure 1 ;

[0067] Figure 3 is a structural schematic diagram of the gas-water conversion system in Figure 1 ;

[0068] Figure 4 is a structural schematic diagram of the flexible wall permeation test system in Figure 1 ;

[0069] Figure 5 is a flowchart of measuring the permeability coefficient using the multi-connected flexible wall permeation equipment of the embodiment of the present application.

[0070] BRIEF DESCRIPTION OF DRAWINGS 110, pressure control system; 120, gas-water conversion system; 130, flexible wall permeation test system; 140, confining pressure manifold; 150, permeation gas pressure line; 160, water permeation pressure manifold; 170, sample; 210, gas source; 220, gas source line; 230, pressure control device; 241, confining pressure gas source on-off valve; 242, confining pressure pressure regulating valve; 243, confining pressure pressure gauge; 244, confining pressure output on-off valve; 251, permeation pressure gas source on-off valve; 252, permeation pressure pressure regulating valve; 253, permeation pressure pressure gauge; 254, permeation pressure output on-off 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 pull rod; 321, water source manifold; 341, conversion chamber gas inlet valve; 342, conversion chamber gas outlet valve; 343, conversion chamber water inlet valve; 351, conversion chamber water outlet valve; 410, confining pressure chamber; 420, exuded water collection device; 430, confining pressure chamber cavity; 440, confining pressure chamber top cover; 450, confining pressure chamber bottom plate; 460, sample base; 470, confining pressure chamber pull rod; 480, water drainage line; 441, confining pressure chamber three-way valve; 451, permeation pressure on-off valve; 452, confining pressure chamber water inlet valve; 453, exuded water valve; 461, first water permeable stone; 462, second water permeable stone; 463, sample cap. DETAILED DESCRIPTION

[0071] The following description Figure 1 Figure 5 The present application is further described in detail.

[0072] The present application discloses a multi-connection flexible wall permeation device, comprising:

[0073] A pressure control system 110 has a first pressure passage and a second pressure passage, the first pressure passage is configured to output a gas confining pressure, and the second pressure passage is configured to output a gas permeation pressure;

[0074] A gas-water conversion system 120 is in communication with the second pressure regulating passage, and the gas-water conversion system 120 is configured to convert the gas permeation pressure into a water permeation pressure;

[0075] A plurality of flexible wall permeation test systems 130 are in communication with the first pressure regulating passage and the gas-water conversion system 120, and the flexible wall permeation test system 130 is used to convert the gas confining pressure into a water confining pressure and perform a permeation test on a sample 170 under the water confining pressure and the water permeation pressure.

[0076] Figure 1 is a structural schematic diagram of the multi-connection flexible wall permeation device of the present application. Referring to Figure 1 ​, the multi-connection flexible wall permeation equipment comprises a pressure control system 110, a gas-water conversion system 120, a plurality of flexible wall permeation test systems 130, a confining pressure main pipe 140, a permeation gas pressure pipe 150, and a water permeation pressure main pipe 160, wherein the flexible wall permeation test system 130 can accommodate a sample 170.

[0077] The pressure control system 110 generates a first gas for outputting a gas confining pressure and a second gas for outputting a gas permeation pressure. The first gas outputs the gas confining pressure into the confining pressure main pipe 140, and the second gas outputs the gas permeation pressure into the permeation gas pressure pipe 150. The gas-water conversion system 120 communicates with the permeation gas pressure pipe 150 and the water permeation pressure main pipe 160, wherein the gas-water conversion system 120 converts the gas permeation pressure into a water permeation pressure and outputs the water permeation pressure to the water permeation pressure main pipe 160. Each flexible wall permeation test system 130 communicates with the confining pressure main pipe 140 and the water permeation pressure main pipe 160, and converts the gas confining pressure into a water confining pressure, so that the sample 170 in each flexible wall permeation test system 130 can be subjected to permeation test under consistent water confining pressure and water permeation pressure.

[0078] Figure 2 is Figure 1 a structural schematic diagram of the pressure control system 110 in Figure 2 The pressure control system 110 comprises a gas source 210, a gas source pipe 220, and a pressure control device 230, wherein the pressure control device 230 has a first pressure adjustment passage (not shown in the figure) for adjusting and controlling a gas confining pressure and a second pressure adjustment passage (not shown in the figure) for adjusting and controlling a gas permeation pressure.

[0079] The gas source 210 can be a gas source device such as an air compressor or an air compression pump, which generates gas that enters the first pressure adjustment passage and the second pressure adjustment passage after passing through the gas source pipe 220 and entering the pressure control device 230. The gas source pipe 220 can be a steel pipe, a copper pipe, or a non-metallic hose. The pressure control device 230 can control gas source distribution, and can adopt a mechanical or hydraulic control cabinet.

[0080] The first pressure regulating passage is provided with, in sequence along the flow direction of the first route gas, an ambient pressure source on-off valve 241, an ambient pressure regulating valve 242, an ambient pressure gauge 243, and an ambient pressure output on-off valve 244, which are connected to the ambient pressure main pipe 140. The ambient pressure source on-off valve 241 is used to control the communication between the first pressure regulating passage and the gas source pipeline 220, the ambient pressure regulating valve 242 is used to regulate the gas ambient pressure, the ambient pressure gauge 243 is used to display the value of the gas ambient pressure, and the ambient pressure output on-off valve 244 is used to control the communication between the first pressure regulating passage and the ambient pressure main pipe 140.

[0081] The second pressure regulating passage is provided with, in sequence along the flow direction of the second route gas, a permeation pressure source on-off valve 251, a permeation pressure regulating valve 252, a permeation pressure gauge 253, and a permeation pressure output on-off valve 254, which are connected to the permeation gas pressure pipeline 150. The permeation pressure source on-off valve 251 is used to control the communication between the second pressure regulating passage and the gas source pipeline 220, the permeation pressure regulating valve 252 is used to regulate the gas permeation pressure, the permeation pressure gauge 253 is used to display the value of the gas permeation pressure, and the permeation pressure output on-off valve 254 is used to control the communication between the second pressure regulating passage and the permeation gas pressure pipeline 150.

[0082] The gas source on-off valve and the output on-off 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. The components are connected by pipelines to realize the distribution and control of the gas source.

[0083] Figure 3 is Figure 1 a structural diagram of the gas-water conversion system 120 in 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, which can be tightly fixed by a conversion chamber pull rod 360. 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 non-metal materials such as high-strength plastic. The conversion chamber pull rod 360 can be a metal rod or a high-strength fiber rod.

[0084] The conversion chamber top cover 340 is provided with a conversion chamber air inlet valve 341, a conversion chamber air outlet valve 342 and a conversion chamber water injection valve 343, and the conversion chamber bottom plate 350 is provided with a conversion chamber water outlet valve 351. The water source 320 is communicated with the conversion chamber water injection valve 343 through the water source main pipeline 321, the conversion chamber air inlet valve 341 is communicated with the gas permeation pressure pipeline 150, and the conversion chamber water outlet valve 351 is communicated with the water permeation pressure main pipeline 160. The conversion chamber air inlet valve 341, the conversion chamber air outlet valve 342 and the conversion chamber water injection valve 343 can be manual valves or automatic valves, and the conversion chamber water outlet valve 351 can be a ball valve or a needle valve.

[0085] The water source 320 is communicated with the conversion chamber water injection valve 343 through the water source main pipeline 321 to fill water in the conversion chamber cavity 330, and at this time the conversion chamber air outlet valve 342 is opened to exhaust air in the conversion chamber cavity 330 when filling water. The gas permeation pressure pipeline 150 outputs gas permeation pressure, and the gas permeation pressure enters the conversion chamber cavity 330 through the conversion chamber air inlet valve 341 to drive water in the conversion chamber cavity 330 to convert the gas permeation pressure into water permeation pressure. The conversion chamber water outlet valve 351 is communicated with the water permeation pressure main pipeline 160 to output the water permeation pressure to the water permeation pressure main pipeline 160.

[0086] Figure 4 is Figure 1 A structural schematic diagram of a flexible wall permeation test system 130 in the water source 320. Referring to Figure 4 , the flexible wall permeation test system 130 includes a confining pressure chamber 410 and a exuded water collecting 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, the confining pressure chamber bottom plate 450 is provided with a sample base 460, and the confining pressure chamber cavity 430, the confining pressure chamber top cover 440 and the confining pressure chamber bottom plate 450 can be tensioned and fixed by a confining pressure chamber pull rod 470, and the exuded water flowing out of the confining pressure chamber 410 can enter the exuded water collecting device 420 through a drain pipeline 480.

[0087] The sample base 460 is used to carry the sample 170, wherein a first water-permeable stone 461, a first filter paper (not shown in the figure), the sample 170, a second filter paper (not shown in the figure), a second water-permeable stone 462 and a sample cap 463 are sequentially arranged on the sample base 460 in a direction away from the sample base 460, the outside of the sample 170 is wrapped with a rubber film (not shown in the figure), and the rubber film is sealed and fixed on the sample base 460 and the sample cap 463. Optionally, the sample base 460 is integrated with the confining pressure chamber bottom plate 450.

[0088] The rubber film can be fixed on the sample base 460 and the sample cap 463 by a rubber ring. The sample base 460 can be made of metal or non-metal material with good corrosion resistance. The first and second water permeable stones 461 and 462 can be natural stones or synthetic materials, and the first and second filter papers can be qualitative or quantitative filter papers. The sample 170 can be a solidified soil or other hard material. The rubber film can be a natural rubber film or a synthetic rubber film, and the rubber ring can be a general rubber ring or a specially designed high-strength rubber ring.

[0089] The confining pressure chamber top cover 440 is provided with a confining pressure chamber three-way air valve 441 which is in communication with the confining pressure main pipe 140. The confining pressure chamber bottom plate 450 is provided with a osmotic pressure switch valve 451, a confining pressure chamber water inlet valve 452 and a exudation water valve 453. The osmotic pressure switch valve 451 is in communication with the water osmotic pressure main pipe 160, the confining pressure chamber water inlet valve 452 is in communication with the water source main pipe 321, and the exudation water valve 453 is in communication with the sample cap 463 and the drainage pipe 480. The exudation water collecting device 420 is in communication with the drainage pipe 480.

[0090] The water source 320 is in communication with the confining pressure chamber water inlet valve 452 through the water source main pipe 321 to fill water into the confining pressure chamber cavity 430, so that the water level in the confining pressure chamber cavity 430 is higher than the height of the upper surface of the sample cap 463. At this time, the confining pressure chamber three-way air valve 441 is in communication with air to exhaust air in the confining pressure chamber cavity 430 when water is filled.

[0091] The confining pressure main pipe 140 provides gas confining pressure which enters the confining pressure chamber cavity 430 through the confining pressure chamber three-way air valve 441 to drive the water in the confining pressure chamber cavity 430 to apply confining pressure to the sample 170.

[0092] The water osmotic pressure main pipe 160 provides water osmotic pressure. Osmotic water enters the sample base 460 through the osmotic pressure switch valve 451, and then flows through the first water permeable stone 461, the first filter paper, the sample 170, the second filter paper, the second water permeable stone 462, and exudes from the sample cap 463. The exuded water from the sample cap 463 is in communication with the drainage pipe 480 through the exudation water valve 453, and flows into the exudation water collecting device 420 through the drainage pipe 480.

[0093] Figure 5 is a flowchart of measuring the permeability coefficient using the multi-connection flexible wall permeation equipment according to the embodiment of the present application. Referring to Figure 5 , the steps of measuring the permeability coefficient using the multi-connection flexible wall permeation equipment include the following steps:

[0094] S1, filling water into the conversion chamber cavity 330 of the gas-water conversion chamber 310.

[0095] S2, water passing and air exhausting for the plurality of seepage pipes.

[0096] S3, respectively setting the sample 170 wrapped with rubber film on the plurality of sample bases 460.

[0097] S4, setting the confining pressure chamber cavity 430 and the confining pressure chamber top cover 440 on the plurality of confining pressure chamber bottom plates 450.

[0098] S5, filling water into the plurality of confining pressure chamber cavities 430.

[0099] S6, outputting gas confining pressure into the plurality of confining pressure chambers 410 through the confining pressure main pipe 140 to drive water in the confining pressure chambers 410 to apply water confining pressure to the samples 170.

[0100] S7, converting gas seepage pressure into water seepage pressure through the gas-water conversion system 120 and applying the water seepage pressure to the plurality of samples 170 through the water seepage pressure main pipe 160.

[0101] S8, respectively collecting and measuring the amount of exuded water from the samples 170 through the plurality of exuded water collecting devices 420 and determining the permeability coefficient of the samples 170 according to the amount of exuded water.

[0102] In step S1, water is filled into the conversion chamber cavity 330 of the gas-water conversion chamber 310. Wherein, the conversion chamber air exhaust valve 342 is opened, and the conversion chamber water filling valve 343 is opened, water is filled into the conversion chamber cavity 330 from the water source 320 through the water source main pipe 321, when the water level reaches 80% to 90% of the volume of the conversion chamber cavity 330, the water filling is stopped, the conversion chamber water filling valve 343 and the conversion chamber air exhaust valve 342 are closed. Subsequently, the conversion chamber cavity 330 can also be supplemented according to the measurement conditions and the amount of water remaining in the conversion chamber cavity 330 according to the above process.

[0103] In step S2, water is passed and air is exhausted for the plurality of seepage pipes. Wherein, the permeation pressure switch valve 451 and the exuded water valve 453 located at the confining pressure chamber bottom plate 450 are opened, water is passed to the sample base 460 through the natural water head of the gas-water conversion chamber 310, and water is passed through the water absorbing ball from the drain hole of the sample cap 463, so that the air bubbles in the above-mentioned seepage pipes are exhausted to inhibit air resistance, and the permeation pressure switch valve 451 and the exuded water valve 453 are closed.

[0104] In step S3, the sample 170 wrapped with a rubber film is arranged on the sample base 460. The first water-permeable stone 461, the first filter paper, the sample 170, the second filter paper, the second water-permeable stone 462, and the sample cap 463 are sequentially arranged on the sample base 460. The rubber film is sleeved in the film container, the two ends are turned out of the container, air is sucked from the air suction hole of the film container, the rubber film sleeve is tightly attached to the inner wall of the film container, the rubber film sleeve is sleeved on the sample 170, the air is released, the two ends of the rubber film are turned up, and the film container is taken out. The two ends of the rubber film are respectively tightly tied on the sample base 460 and the sample cap 463 by the rubber ring.

[0105] In step S4, the confining pressure chamber cavity 430 (which can be a cylinder without a top surface and a bottom surface) and the confining pressure chamber top cover 440 are arranged 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 are tightly fixed by the confining pressure chamber pull rod 470.

[0106] In step S5, water is filled into the confining pressure chamber cavities 430. The confining pressure chamber three-way air valve 441 at the confining pressure chamber top cover 440 is communicated with air, the confining pressure chamber water inlet valve 452 at the confining pressure chamber bottom plate 450 is opened to be communicated with the water source main pipeline 321, the confining pressure chamber cavities 430 are filled with water from the water source 320 until the water level exceeds the upper surface of the sample cap 463 by a certain height, and then the confining pressure chamber water inlet valve 452 is closed.

[0107] In step S6, the gas confining pressure is outputted to the confining pressure chambers 410 through the confining pressure main pipeline 140 to drive the water in the confining pressure chambers 410 to apply water confining pressure to the sample 170. The confining pressure chamber three-way air valve 441 is communicated with the confining pressure main pipeline 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 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 size of the gas confining pressure is determined according to the effective stress actually borne by the sample 170.

[0108] In step S7, the gas permeation pressure is converted into water permeation pressure by the gas-water conversion system 120, and the water permeation pressure is applied to the multiple samples 170 through the water permeation pressure main pipe 160. In this process, the conversion chamber gas inlet valve 341 at the top cover 340 of the conversion chamber, the conversion chamber water outlet valve 351 at the bottom plate 350 of the conversion chamber, and the permeation pressure switch valve 451 at the bottom plate 450 of the confining pressure chamber are opened, the permeation pressure gas source switch valve 251 and the permeation pressure output switch valve 254 of the pressure control device 230 are opened, the permeation pressure regulating valve 252 is adjusted, and the permeation pressure pressure gauge 253 is observed to adjust the permeation pressure to a preset value. In order to ensure that the rubber mold outside the sample 170 is tightly attached to the sample 170 and to avoid leakage of the sidewall of the sample 170, the permeation pressure needs to be less than the confining pressure. Preferably, the permeation pressure is 20-50 kPa less than the confining pressure.

[0109] In step S8, the amount of exuded water from the sample 170 is collected and measured by the multiple exuded water collection devices 420, and the permeation coefficient of the sample 170 is determined according to the amount of exuded water. In this process, the exuded water valve 453 at the bottom plate 450 of the confining pressure chamber is opened, the weight of the exuded water collection device 420 is read and recorded, and the water temperature is recorded. The amount of exuded water is determined according to the weight reading of the exuded water collection device 420 and the density of water. The time interval for reading can be determined according to the amount of exuded water of the sample 170. For samples with a large amount of exuded water, the reading can be taken every 3-5 minutes, and for samples with a small amount of exuded water, the reading can be taken every 30-60 minutes. At least 6 data points need to be measured for each sample, and the duration of the measurement should be determined according to the stability of the exuded water. When the difference in permeation coefficient calculated from the amount of exuded water is not greater than 2×10 -n , the measurement can be stopped.

[0110] The specific data processing process includes: determining the water head difference Δh according to the ratio of the applied permeation pressure p to the water specific weight γ w , and calculating the permeation coefficient k according to Darcy's law; converting the permeation coefficient k to the permeation coefficient k 20 at standard temperature (20°C) according to the measured water temperature; selecting multiple (e.g. 3-4) data points with similar values and within the allowable difference range from the test data results, calculating the average value, and taking the average value as the permeation coefficient of the solidified soil sample under specific conditions. The allowable difference should not exceed 2×10 -n .

[0111] The implementation principle of the multi-connection flexible wall permeation equipment according to an embodiment of the present application is as follows:

[0112] 1. The multi-connection flexible wall permeameter comprises a plurality of said flexible wall permeameter test systems 130, that is, a plurality of said confining pressure chambers 410 and a plurality of said water collection devices 420. Each of said confining pressure chambers 410 is connected to the first pressure passage of said pressure control system 110 through said confining pressure manifold 140, so that a plurality of said flexible wall permeameter test systems 130 share the same gas confining pressure pipeline and convert the gas confining pressure into water confining pressure by the flexible wall permeameter test systems 130, ensuring the consistency of the confining pressure of a plurality of said flexible wall permeameter test systems 130.

[0113] 2. The gas permeation pressure is converted by said gas-water conversion system 120 to generate water permeation pressure, which can meet the water permeation pressure requirements of hard soil materials such as solidified soil with low permeability.

[0114] 3. Each of said confining pressure chambers 410 is connected to said gas-water conversion system 120 through said water permeation pressure manifold 160, so that a plurality of said flexible wall permeameter test systems 130 share the same water permeation pressure pipeline, ensuring the consistency of the water permeation pressure of a plurality of said flexible wall permeameter test systems 130.

[0115] The above are preferred embodiments of the present application, which do not limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A multi-stage flexible wall permeation apparatus, characterized by, Comprising: a pressure control system (110) having a first pressure passage and a second pressure passage, the first pressure passage configured to output a gas confining pressure, the second pressure passage configured to output a gas permeation pressure; a gas-to-water conversion system (120) in communication with the second pressure passage, the gas-to-water conversion system (120) configured to convert the gas permeation pressure to a water permeation pressure; a plurality of flexible wall permeation test systems (130) in communication with the first pressure passage and the gas-to-water conversion system (120), the plurality of flexible wall permeation test systems (130) for converting the gas confining pressure to a water confining pressure and conducting permeation tests on a plurality of samples (170) under the water confining pressure and the water permeation pressure.

2. The multi-stage flexible wall permeation apparatus of claim 1, wherein, Further comprising: a confining pressure manifold (140) in communication with the first pressure passage and the plurality of flexible wall permeation test systems (130); a permeation gas pressure manifold (150) in communication with the second pressure passage and the gas-to-water conversion system (120); a water permeation pressure manifold (160) in communication with the gas-to-water conversion system (120) and the plurality of flexible wall permeation test systems (130).

3. The multi-stage flexible wall permeation apparatus of claim 2, wherein, The pressure control system (110) comprises: a gas source (210); a gas source manifold (220) in communication with the gas source (210) and a pressure control device (230); the pressure control device (230) including the first pressure passage and the second pressure passage.

4. The multi-stage flexible wall permeation apparatus of claim 3, wherein, The first pressure passage comprises: a confining pressure gas source on-off valve (241) configured to control communication of the first pressure regulating passage with the gas source manifold (220); a confining pressure pressure regulating valve (242) configured to regulate the gas confining pressure; a confining pressure pressure gauge (243) configured to display a value of the gas confining pressure; a confining pressure output on-off valve (244) configured to control communication of the first pressure regulating passage with the confining pressure manifold (140); alternatively, the second pressure passage comprises: a permeation pressure gas source on-off valve (251) configured to control communication of the second pressure regulating passage with the gas source manifold (220); a permeation pressure pressure regulating valve (252) configured to regulate the gas permeation pressure; a permeation pressure pressure gauge (253) configured to display a value of the gas permeation pressure; a permeation pressure output on-off valve (254) configured to control communication of the second pressure regulating passage with the permeation gas pressure manifold (150).

5. The multi-stage flexible wall permeation apparatus of claim 2, wherein, The gas-to-water conversion system (120) comprises: a gas-to-water conversion chamber (310) including a conversion chamber cavity (330), a conversion chamber top cover (340), and a conversion chamber bottom plate (350); a water source (320) in communication with the gas-to-water conversion chamber (310) and the plurality of flexible wall permeation test systems (130) via a water source manifold (321).

6. The multi-stage flexible wall permeation apparatus of claim 5, wherein, The conversion chamber top cover (340) comprises: a conversion chamber gas inlet valve (341) configured to control communication of the conversion chamber cavity (330) with the permeation gas pressure manifold (150); a conversion chamber gas outlet valve (342) configured to control communication of the conversion chamber cavity (330) with 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 line (321); Alternatively, the conversion chamber bottom plate (350) comprises: A conversion chamber water outlet valve (351) configured to control the communication between the conversion chamber cavity (330) and the permeation gas pressure line (150).

7. The multi-stage flexible wall permeation apparatus of claim 5, wherein, The flexible wall permeation test 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 the confining pressure chamber bottom plate (450) is provided with a sample seat (460) configured to carry the sample (170); A permeate water collection device (420) in communication with the confining pressure chamber (410) through a drain line (480) to receive the permeate water flowing out of the sample (170).

8. The multi-stage flexible wall permeation apparatus of claim 7, wherein, The confining pressure chamber bottom plate (450) and the sample seat (460) are integrated.

9. The multi-stage flexible wall permeation apparatus of claim 7, wherein, A first water-permeable stone, a first filter paper, the sample (170), a second filter paper, a second water-permeable stone (462), and a sample cap (463) are sequentially arranged on the sample seat (460) in a direction away from the sample seat (460), wherein the sample (170) is wrapped with a rubber film.

10. The multi-stage flexible wall permeation apparatus of claim 9, wherein, The confining pressure chamber top cover (440) comprises: A confining pressure chamber tee valve (441) configured to control the communication between the confining pressure chamber cavity (430) and the confining pressure main line (140) and external air; Alternatively, the confining pressure chamber bottom plate (450) comprises: A permeation pressure on-off valve (451) configured to control the communication between the sample seat (460) and the water permeation pressure main line (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 line (321); A permeate water valve (453) configured to control the communication between the sample cap (463) and the drain line (480).

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