Bentonite assembly hydraulic property co-evolution test system and method

Abstract

The invention provides a system and a method for testing hydraulic performance co-evolution of a bentonite assembly. The system comprises a joint self-closing / healing visual test assembly, a pressure / volume controller and a digital measurement assembly, wherein the visual test assembly is used for capturing macroscopic morphological characteristics in a joint self-closing / healing process of an assembly sample; the pressure / volume controller is used for controlling the water injection pressure and the water injection rate; the digital measuring assembly is used for achieving co-evolution recording of the macroscopic form, the expansive force, the water injection pressure and the accumulated water injection volume. On the basis of the construction joint self-closing / healing process, a visual test result of the joint self-closing / healing process and a macroscopic hydraulic property evolution test result are subjected to collaborative analysis for the first time, and a construction joint self-closing / healing action mechanism and a macroscopic hydraulic property response mechanism in the compacted bentonite are disclosed; and theoretical guidance is provided for the design of the bentonite buffer layer considering the construction joint in the repository engineering barrier.

Description

Technical Field

[0001] The present invention relates to the technical field of geological engineering, and particularly relates to a testing system and method for the collaborative evolution of the hydraulic properties of a bentonite assembly. Background Art

[0002] How to safely dispose of a large amount of high-level radioactive waste will become the key to the sustainable development of nuclear power. At present, the internationally recognized most feasible and reliable method is deep geological disposal, that is, sealing high-level radioactive waste in a stable rock mass at a depth of 500 - 1000 meters, and realizing its permanent sealing through a multi-barrier system of solidified bodies, metal waste cans, engineering barriers and natural barriers. High-compacted bentonite, due to its characteristics of high expansibility, low permeability and strong adsorption, is selected as the most ideal engineering barrier material.

[0003] In actual engineering, high-level radioactive waste deep geological disposal repositories usually use prefabricated compacted bentonite blocks filled in galleries to form engineering barriers. This inevitably generates construction joints, including between bentonite blocks, between blocks and waste cans, and between blocks and surrounding rocks. According to statistics, these construction joints account for about 6 - 14% of the total volume of bentonite, becoming preferential seepage channels and weak zones of mechanical strength, endangering the safety of the disposal repository. The research on high-level radioactive waste deep geological disposal in China began in the 1980s. Gansu Beishan has been selected as the site for the first disposal repository, and bentonite from Gaomiaozi (GMZ) in Inner Mongolia Autonomous Region is the preferred buffer / backfill material. At the same time, the construction of the first high-level radioactive waste disposal Beishan underground laboratory in China started in 2021, marking that China's deep geological disposal has fully entered the underground laboratory stage. As an important prerequisite for the long-term performance research of large-scale engineering barriers in underground laboratories, the research on the self-sealing / healing mechanism of construction joints in compacted bentonite assemblies and its influence mechanism on macroscopic hydraulic properties is extremely urgent and necessary. Summary of the Invention

[0004] The purpose of the present invention is to provide a system and method that are convenient for reliably studying the self-sealing / healing mechanism of construction joints in compacted bentonite assemblies and its influence mechanism on macroscopic hydraulic properties.

[0005] To achieve the above object, the present invention provides a testing system for the collaborative evolution of the hydraulic properties of a bentonite assembly, including a visualization test component for the self-sealing / healing of joints, a pressure / volume controller, and a digital measurement component:

[0006] The seam self-sealing / healing visualization test assembly is used to enable the hydration of the composite specimen under constant-volume rigid boundary conditions and support the macroscopic morphology observation of the seam self-sealing process; the seam self-sealing / healing visualization test assembly includes a standard light source observation box and a hydration device disposed in the observation box, and a collection assembly is provided above the hydration device; the hydration device includes a transparent top cover, a test ring, a base, and a pressure sensor: the test ring is used to place the compacted bentonite composite specimen with a seam; the test ring is fixed between the transparent top cover and the base; the pressure sensor is embedded in the side wall of the test ring for monitoring the swelling force;

[0007] The pressure / volume controller is connected to the hydration device for controlling the injection water pressure and the water injection rate;

[0008] The digital measurement assembly is signal-connected to the visualization test assembly, the pressure / volume controller, and the pressure sensor for realizing data set storage, and storing the macroscopic morphology evolution recorded by the visualization test assembly, the swelling force evolution monitored by the sensor, and the injection water pressure and cumulative injection water volume data recorded by the pressure / volume controller in a computer in a set manner.

[0009] Further, an exhaust hole is opened on the transparent top cover, and a metal water-permeable stone is provided at the bottom of the exhaust hole to ensure the smooth discharge of air in the test ring during the water injection process; the test ring is fixed at the central position of the base, and a metal water-permeable stone with the same inner diameter as the test ring is embedded at the central position of the base. A spiral groove is provided at the bottom of the metal water-permeable stone at the central position of the base to ensure the uniformity of water entering from the bottom of the specimen during the test process; the base is provided with a water inlet. During the test process, the relative positions of the exhaust hole, the test ring, and the base are fixed, so that the reserved seam direction in the test ring is perpendicular to the direction of the exhaust hole and consistent with the direction of the water inlet of the base.

[0010] Further, the metal water-permeable stone is made of metal copper to prevent the overflow of bentonite colloid during the hydration process and reduce the soil mass loss during the test process.

[0011] Further, the probe diameter of the pressure sensor is 6 mm, the maximum cross-sectional diameter is 16 mm, the maximum range is 10 MPa, and the accuracy is 0.01 MPa. It is embedded in the test ring through a threaded structure, and the surface of the sensor probe after screwing in is smooth and continuous with the inner wall of the test ring.

[0012] Furthermore, the side wall of the test ring is connected to the pressure sensor by adopting a three - stage stepped cutting structure. The three - stage stepped cutting structure is, from outside to inside, the first - stage cutting size, the second - stage cutting size, and the third - stage cutting size, which respectively correspond to the maximum cross - sectional diameter, the front - end thread size, and the probe size of the pressure sensor, so as to ensure that the final radial pressure sensor is exactly embedded in the side wall of the test ring, making the surface of the pressure sensor probe screwed into the test ring smooth and continuous with the inner wall of the test ring. During the screwing process, the pressure sensor is wound with a sealing tape to ensure complete sealing of the contact interface.

[0013] Furthermore, the hydration device is arranged inside a standard light source observation box to eliminate the influence of ambient light on the macroscopic morphology recording during the self - sealing / healing process of the joint. The standard light source observation box uses an LED cold light source for constant illumination and constant chamber temperature.

[0014] Furthermore, in the hydration device, O - ring seals are provided between the transparent top cover and the test ring, and between the base and the test ring to ensure the tightness of the cavity during the hydration process.

[0015] Furthermore, the acquisition component is a high - resolution camera. The high - resolution camera is installed inside the standard light source observation box and is located above the hydration device. Inside the standard light source observation box, the high - resolution camera is used to record the macroscopic morphological evolution characteristics of the self - sealing / healing process of the joint in real - time. Through a shutter release cable, the automatic image shooting interval is set and can be appropriately changed according to the macroscopic morphology results.

[0016] Furthermore, the transparent top cover is made of polymethyl methacrylate (PMMA) material, which has a high light transmittance to clearly observe the macroscopic morphological evolution. The thickness of the top cover is 15 mm to ensure sufficient strength to prevent the top cover from splitting caused by the hydration swelling force. The diameter of the exhaust hole is 3 mm. The test ring is made of 316L stainless steel material, with an inner diameter of 61.8 mm, a height of 20 mm, and an outer diameter of 88 mm, and is fixed at the central position of the base to ensure that the compacted bentonite composite specimen containing the joint undergoes hydration under the condition of a constant - volume rigid boundary.

[0017] Furthermore, the fixed base, the test ring, and the transparent top cover are sequentially fixed by bolts and nuts. The bolts and nuts are made of 316L stainless steel material, which has sufficient mechanical strength and can prevent corrosion problems that may occur during long - term tests, and are used to connect and fix the relative positions between the transparent top cover, the test ring, and the base.

[0018] Furthermore, the pressure sensor is connected to a paperless recorder, which converts the pressure value measured by the pressure sensor into an electrical signal and stores these signals as digital data for subsequent analysis and processing.

[0019] The present invention also proposes a bentonite assembly hydraulic performance co-evolution test method. Based on the bentonite assembly hydraulic performance co-evolution test system, the test method comprises the following steps:

[0020] S1: Calculate and weigh the target mass required for sample pressing;

[0021] S2: Install the instrument, screw the pressure sensor into the side wall of the test ring, and fix the base, test ring and transparent top cover in sequence;

[0022] S3: Turn on the LED light and high-resolution camera, set the interval time to automatically take an image, and when the macroscopic morphology of the sample evolves slowly, increase the shooting interval appropriately; turn on the pressure / volume controller, set the pressurization / water injection rate of the GDS standard pressure / volume controller, and record the water injection pressure and water injection volume data; open the water inlet at the base to allow deionized water to penetrate from the bottom of the test ring, and the original air in the test ring is compressed and discharged along the exhaust hole of the transparent top cover, which means that the hydration test has begun;

[0023] S4: After 3-5 months of long-term evolution, stop the test, use digital measurement components to store various data sets, and then turn off the power.

[0024] Furthermore, in step S1, before the sample is pressed, the suction of the bentonite powder is controlled by the gas phase method so that the sample has the same initial state; the soil powder after suction balance is taken, the moisture content is measured based on the drying method, and the target mass required for sample pressing is calculated and weighed; during the pressing process, static displacement control (0.5mm / min) is adopted, and after reaching the target displacement, it is left to stand for 1 hour before unloading; after unloading, the stainless steel plug embedded in the side wall of the test ring is removed and replaced with the pressure sensor in step 2.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] 1. The present invention is the first to collaboratively analyze the macroscopic morphological evolution, expansion force evolution, and injection pressure / volume evolution of the joint-containing assembly specimen, revealing the self-sealing / healing mechanism of the construction joints and the macroscopic hydraulic performance response mechanism of the joint-containing assembly, providing theoretical guidance for the design of bentonite buffer layers considering construction joints in the engineering barrier of the disposal repository.

[0027] 2. The present invention can monitor the macroscopic morphological evolution characteristics of the bentonite assembly containing joints in real time through a hydration device and a standard light source observation box, thereby revealing the expansion-cracking associated characteristics of the bentonite containing joints and a stage-by-stage division method for the self-sealing / healing process of the construction joints.

[0028] 3. By setting sensors and a pressure / volume controller, the present invention monitors in real time the co-evolution law of the swelling force, water injection pressure, and cumulative water injection volume, and clarifies the mechanism of the effect of the joint self-sealing / healing process on the stage evolution of the macroscopic hydro-mechanical properties of the compacted bentonite assembly.

[0029] 4. Through the system and method of the present invention, the initial joint width, water injection pressure, and flow rate can be accurately controlled to conduct self-sealing / healing tests on the compacted bentonite assembly under different joint volume ratios and different hydraulic paths, facilitating reliable in-depth research by researchers on the self-sealing / healing mechanism of construction joints in the compacted bentonite assembly and its influence mechanism on macroscopic hydro-mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of a test system for the co-evolution of the hydro-mechanical properties of a bentonite assembly according to an embodiment of the present invention;

[0031] Figure 2 It is a top view of the base of the hydration device according to an embodiment of the present invention;

[0032] 1 - High-resolution camera, 2 - LED cold light source, 3 - Standard light source observation box, 4 - Exhaust hole, 5 - Transparent top cover, 6 - O-ring seal, 7 - Bolts and nuts, 8 - Test ring, 9 - Bentonite sample, 10 - Base, 11 - Simulated construction joint, 12 - Radial swelling force sensor, 13 - Permeable stone, 14 - GDS standard pressure / volume controller, 15 - Data recording computer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below.

[0034] This embodiment provides a test system for the co-evolution of the hydro-mechanical properties of a bentonite assembly. Based on the construction joint self-sealing / healing process, its structure is as Figure 1 shown, including a hydration device, a high-resolution camera 1, a GDS standard pressure / volume controller 14, and a data recording computer 15. Among them, the hydration device is arranged in the standard light source observation box 3 to eliminate the influence of ambient light on the macroscopic morphology recording during the joint self-sealing / healing process; the standard light source observation box 3 uses an LED cold light source 2 for constant illumination and constant chamber temperature.

[0035] The hydration device is used to realize the hydration of the compacted bentonite assembly sample with joints under the condition of a constant volume rigid boundary and support the macroscopic morphology observation of the joint self-sealing process.

[0036] Its structure includes a transparent top cover 5, a test ring 8, a base 10, and a radial swelling force sensor 12, as Figure 1As shown in the figure, an exhaust hole 4 with a diameter of 3 mm is provided on the transparent top cover 5 at a distance of 37.6 mm from the cover edge. A metal water-permeable stone 13 is provided at the bottom of the exhaust hole 4 to ensure the smooth discharge of air in the test ring during the water injection process. The test ring 8 is fixed between the transparent top cover 5 and the base 10 and is used to place the compacted bentonite sample 9 with joints.

[0037] The test ring 8 is fixed at the central position of the base 10 through bolts and nuts 7. O-ring seals 6 are provided between the transparent top cover 5 and the test ring 8 and between the base 10 and the test ring 8 to ensure the sealing of the cavity during the hydration process. A metal water-permeable stone 13 with the same diameter as the compacted bentonite sample 9 with joints is embedded at the central position of the base 10. As Figure 2 shown in the schematic diagram of the base, a spiral groove is provided at the bottom of the metal water-permeable stone 13 at the central position of the base 10 to ensure the uniformity of water entering from the bottom of the sample during the test process. In addition, the base 10 is also provided with a water inlet. During the test, the relative positions of the exhaust hole 4, the test ring 8, and the base 10 are fixed, so that the reserved joint direction in the test ring 8 is perpendicular to the direction of the exhaust hole 4 and is consistent with the direction of the water inlet of the base 10. The radial expansion force sensor 12 is screwed into the side wall of the test ring 8 to monitor the expansion force. The radial expansion force sensor 12 is connected to a paperless recorder, which converts the pressure value measured by the pressure sensor into an electrical signal and stores these signals as digital data for subsequent analysis and processing, realizing functions such as data storage and analysis, real-time monitoring, and data sharing reports.

[0038] A high-resolution camera 1 is arranged above the hydration device to record the macroscopic morphological evolution characteristics of the self-sealing / healing process of the joints in the hydration device in real time. At the same time, a GDS standard pressure / volume controller 14 is connected to the hydration device. The controller 14 uses the Advanced Loading module in the GDSLAB software to accurately control the injection water pressure and injection rate, and realizes the automatic real-time data recording function through the Data Acquisition module in the GDSLAB software;

[0039] The data recording computer 15 is signal-connected to the high-resolution camera 1, the GDS standard pressure / volume controller 14, and the radial expansion force sensor 12, and is used to realize the collective storage of data. The macroscopic morphological evolution recorded by the high-resolution camera 1, the expansion force evolution recorded by the paperless recorder, and the injection water pressure and cumulative injection water volume data recorded by the pressure / volume controller 14 are collectively stored in the desktop computer 15.

[0040] In this embodiment, the metal water-permeable stone 13 is made of metal copper to prevent the overflow of bentonite colloid during the hydration process and reduce the soil mass loss during the test.

[0041] In this embodiment, the radial expansion force sensor 12 is of model CYY9, with a probe diameter of 6 mm, a maximum cross-sectional diameter of 16 mm, a maximum measuring range of 10 MPa, and an accuracy of 0.01 MPa. It is embedded in the test ring 8 through a threaded structure, and after screwing in, the surface of the probe of the sensor 12 is smooth and continuous with the inner wall of the test ring 8.

[0042] In this embodiment, the side wall of the test ring 8 is connected to the radial expansion force sensor 12 by adopting a three-stage stepped cutting structure. The three-stage stepped cutting structure is the first-stage cutting dimension, the second-stage cutting dimension, and the third-stage cutting dimension from the outside to the inside, which correspond to the maximum cross-sectional diameter, the front-end thread dimension, and the probe dimension of the radial expansion force sensor 12 respectively. The first-stage cutting dimension on the outside ensures that the maximum cross-sectional diameter (16 mm) of the sensor 12 can be accommodated. The second-stage cutting dimension is based on the front-end thread dimension (10 mm) of the sensor 12, and the third-stage cutting dimension is based on the probe characteristics (6 mm) of the sensor 12, so as to ensure that the radial expansion force sensor 12 is exactly embedded in the side wall of the test ring 8, making the surface of the probe of the sensor 12 screwed into the test ring 8 smooth and continuous with the inner wall of the test ring 8. During the screwing process, the radial expansion force sensor 12 is wound with polytetrafluoroethylene raw tape as a sealing tape to ensure complete sealing of the contact interface.

[0043] In this embodiment, the high-resolution camera 1 records the macroscopic morphological evolution characteristics of the joint self-sealing / healing process in real time. Through the shutter release cable, the automatic image shooting interval is set and can be appropriately changed according to the macroscopic morphological results.

[0044] In this embodiment, the transparent top cover 5 is made of polymethyl methacrylate (PMMA) material, which has a high light transmittance to clearly observe the macroscopic morphological evolution. The thickness of the top cover 5 is 15 mm to ensure sufficient strength to prevent the top cover from splitting caused by the hydration expansion force. The test ring 8 is made of 316L stainless steel material, with an inner diameter of 61.8 mm, a height of 20 mm, and an outer diameter of 88 mm. It is fixed at the central position of the base 10 to ensure that the compacted bentonite composite specimen 9 containing the joint undergoes hydration under the constant volume rigid boundary condition.

[0045] In this embodiment, the base 10, the test ring 8, and the transparent top cover 5 are sequentially fixed by bolts and nuts 7. Among them, the bolts and nuts 7 are made of 316L stainless steel material, which has sufficient mechanical strength and prevents the corrosion problem that may occur during long-term tests, and is used to connect and fix the relative positions among the transparent top cover 5, the test ring 8, and the base 10.

[0046] Based on the above bentonite composite hydro-mechanical property co-evolution test system, the hydro-mechanical property co-evolution test of the bentonite composite is carried out. The test method includes the following steps:

[0047] 1) Preparation of specimens: Before pressing the specimens, control the suction of bentonite powder by the gas phase method to ensure that the specimens have the same initial state (113 MPa). Take the soil powder after suction balance, measure the water content based on the drying method, and calculate and weigh the target mass required for specimen pressing. During the pressing process, use the static method for displacement control (0.5 mm / min). After reaching the target displacement, let it stand for 1 hour and then relieve the pressure;

[0048] 2) Installation of instruments: Remove the bolts embedded in the side wall of the test ring 8 during the specimen pressing process and screw them into the radial expansion force sensor 12. When the reading of the sensor 12 is 5 kPa, it is considered that the sensor 12 just contacts the specimen 9; Place the test ring 8 on the base 10 of the hydration device, and note that the joint direction of each group of specimens should be consistent with the water inlet direction of the base 10 and perpendicular to the air hole direction in the transparent top cover 5; Subsequently, the base 10, the test ring 8 and the transparent top cover 5 are fixed in sequence by bolts and nuts 7;

[0049] S3: Turn on the LED light source 2 and the high-resolution camera 1, set to automatically take an image every 2 minutes, and appropriately increase the shooting interval when the macroscopic morphology evolution of the specimen tends to be gentle; Turn on the GDS standard pressure / volume controller 14, set the pressurization / water injection rate of the GDS standard pressure / volume controller 14, and record the water injection pressure and water injection volume data; Open the water inlet of the base 10 so that deionized water seeps in from the bottom of the test ring, and the original air in the test ring 8 is compressed and discharged along the exhaust hole 4 of the transparent top cover 5, indicating the start of the hydration test;

[0050] S4: This test is a long-term evolution test, and the long-term evolution usually lasts for 3 - 5 months. After the test stops, collect and store the macroscopic morphology evolution recorded by the high-resolution camera 1, the expansion force evolution recorded by the paperless recorder, the water injection pressure and the cumulative water injection volume data recorded by the GDS pressure / volume controller 14 in the desktop computer 15, and then turn off the power supply.

[0051] The above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any person skilled in the art, without departing from the technical solution of the present invention, makes any form of equivalent substitution or modification and other changes to the technical solution and technical content disclosed by the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. A bentonite assembly hydraulic performance co-evolution test system, characterized in that: Including seam self-sealing / healing visualization test components, pressure / volume controller and digital measurement components: The joint self-sealing / healing visualization test assembly is used to realize hydration of the combined body sample under constant volume rigid boundary conditions and support macroscopic morphological observation of the joint self-sealing process; the joint self-sealing / healing visualization test assembly includes a standard light source observation box and a hydration device arranged in the observation box, and a collection assembly is arranged above the hydration device; the hydration device includes a transparent top cover, a test ring, a base and a pressure sensor: the test ring is used to place the combined sample containing joint compacted bentonite; the test ring is fixed between the transparent top cover and the base; the pressure sensor is embedded in the side wall of the test ring to monitor the expansion force; The pressure / volume controller is connected to the hydration device and is used to control the injection water pressure and injection rate; The digital measurement component is connected to the visual test component, the pressure / volume controller and the pressure sensor signal to realize data set storage.

2. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: An exhaust hole is provided on the transparent top cover, and a metal permeable stone is provided at the bottom of the exhaust hole; the test ring is fixed at the center of the base, and a metal permeable stone with the same inner diameter as the test ring is embedded at the center of the base, and a spiral groove is provided at the bottom of the metal permeable stone at the center of the base; the base is provided with a water inlet, and during the test experiment, the relative positions of the exhaust hole, the test ring and the base are fixed, so that the direction of the reserved seam in the test ring is perpendicular to the direction of the exhaust hole and consistent with the direction of the water inlet of the base.

3. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: The side wall of the test ring is connected to the pressure sensor by adopting a three-level stepped cutting structure, and the three-level stepped cutting structure is respectively the first-level cutting size, the second-level cutting size and the third-level cutting size from the outside to the inside, which respectively correspond to the maximum cross-sectional diameter, the front-end thread size and the probe size of the pressure sensor, so that the surface of the pressure sensor probe screwed into the test ring is smooth and continuous with the inner wall of the test ring; the pressure sensor is wrapped with a sealing tape.

4. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: The hydration device is arranged in a standard light source observation box, and the standard light source observation box adopts an LED cold light source to achieve constant lighting and a constant cavity temperature.

5. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: In the hydration device, sealing rings are provided between the transparent top cover and the test ring, and between the base and the test ring; the fixed base, the test ring and the transparent top cover are fixed in sequence by bolts and nuts.

6. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: The acquisition component is a high-resolution camera, which is installed in a standard light source observation box and located above the hydration device, and is used to acquire and record photo images in real time.

7. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: The transparent top cover is made of polymethyl methacrylate material, and the thickness of the top cover is 15mm; the diameter of the exhaust hole is 3mm; the test ring is made of 316L stainless steel material, with an inner diameter of 61.8mm, a height of 20mm, and an outer diameter of 88mm.

8. The bentonite assembly hydraulic performance co-evolution test system according to claim 1, characterized in that: The pressure sensor is connected to a paperless recorder to convert the pressure values ​​measured by the pressure sensor into electrical signals, and store the signals as digital data.

9. A method for testing the synergistic evolution of hydraulic properties of a bentonite assembly, based on the synergistic evolution testing system for hydraulic properties of a bentonite assembly as claimed in any one of claims 1 to 8, characterized in that: The test method includes the following steps: S1: Calculate and weigh the target mass required for sample pressing; S2: Install the instrument, screw the pressure sensor into the side wall of the test ring, and fix the base, test ring and transparent top cover in sequence; S3: Turn on the LED light and high-resolution camera, set the interval to automatically take an image, and when the macroscopic morphology of the sample tends to be flat, increase the shooting interval appropriately; turn on the pressure / volume controller, set the pressurization / water injection rate of the standard pressure / volume controller, and record the water injection pressure and water injection volume data; Open the water inlet of the base to allow deionized water to seep in from the bottom of the test ring. The original air in the test ring is compressed and discharged through the exhaust hole of the transparent top cover, which means the hydration test begins; S4: After 3-5 months of long-term evolution, stop the test, use digital measurement components to store various data sets, and then turn off the power.

10. The method for testing the synergistic evolution of hydraulic properties of bentonite assemblies according to claim 9, characterized in that: In step S1, before the sample is pressed, the suction of the bentonite powder is controlled by the gas phase method so that the sample has the same initial state; the soil powder after suction balance is taken, the moisture content is measured based on the drying method, and the target mass required for sample pressing is calculated and weighed; during the pressing process, the static displacement control (0.5mm / min) is adopted, and after reaching the target displacement, the pressure is released after standing for 1 hour.

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