Expansion force anisotropy testing device for bentonite construction joint self-healing

Abstract

The invention provides an expansive force anisotropy testing device for bentonite construction joint self-healing, and belongs to the technical field of testing devices.The expansive force anisotropy testing device comprises a base, a sample cavity is formed in the upper surface of the base, an embedding groove is formed in the upper surface of the sample cavity and covered with an acrylic transparent plate, the embedding groove is used for containing a sample, and a permeable stone is embedded into the bottom of the embedding groove; the permeable stone pipeline is connected with a volume / pressure controller, an axial pressure sensor used for measuring the axial expansive force of the sample is arranged between the base and the sample cavity, a radial pressure sensor connected with the sample and used for measuring the radial expansive force of the sample is arranged on the side edge of the sample cavity, and an image acquisition module connected with a terminal is erected above the sample. The system is used for recording sample expansion deformation and construction joint healing process in real time. According to the invention, the real-time visual recording of the bentonite expansion process is realized, the sensor layout is optimized, the association mechanism of the expansion force time history curve and the seam self-healing process is clarified, and the data acquisition precision and the test efficiency are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of testing devices, and in particular relates to an anisotropic expansion force testing device for self-healing of bentonite construction joints. Background Art

[0002] In the design concepts of high-level nuclear waste repositories worldwide, multiple barrier systems have been recognized as the safest and most effective system for preventing the migration and leakage of radionuclides. Highly compacted bentonite, as an engineering barrier material, absorbs water and expands, seals construction joints, and prevents radionuclides from leaking.

[0003] Due to limitations in construction methods, numerous construction joints are formed in engineering barriers constructed from pre-compacted bentonite blocks. These joints inevitably create dominant seepage pathways and mechanically weak zones, severely weakening the hydro-mechanical buffering properties of the engineering barriers. Therefore, researchers at home and abroad conducted swelling force-permeability tests on high-compacted bentonite with varying dry densities and joint sizes, simulating the construction joints between high-compacted bentonite and surrounding rock.

[0004] However, existing expansion force testing devices mostly use metal materials to cover the top of the specimen, which makes it impossible to directly observe the healing process of the construction joint. In addition, the sensors are mostly placed above the specimen and are susceptible to external interference. Summary of the Invention

[0005] The purpose of the present invention is to solve the above-mentioned problems of inconvenience in direct observation and susceptibility to external interference, and to provide an anisotropic expansion force testing device for self-healing of bentonite construction joints, characterized in that it includes a base, a sample cavity is placed on the upper surface of the base, a transparent acrylic plate is provided in the upper surface of the sample cavity, a groove is used to place the sample, a permeable stone is embedded in the bottom of the groove, and an image acquisition module connected to the terminal is mounted above the sample;

[0006] The permeable stone is connected to a volume / pressure controller through a pipeline, an axial pressure sensor is provided between the base and the sample cavity, and a radial pressure sensor connected to the sample is provided on the side of the sample cavity. Both the radial pressure sensor and the axial pressure sensor are connected to the paperless recorder signal.

[0007] The expansion force anisotropy test device uses an image acquisition module to record the expansion deformation of the sample, that is, the construction joint healing process, in real time, through the axial pressure sensor to measure the axial expansion force of the sample, and through the radial pressure sensor to measure the radial expansion force of the sample, thereby completing the visual expansion force anisotropy test.

[0008] Furthermore, an annular groove is provided on the upper surface of the base, and the force-bearing surface of the axial sensor faces upward and is embedded in the annular groove, thereby realizing real-time measurement of the axial expansion force of the sample.

[0009] Furthermore, a threaded hole connected to the inside of the embedding groove is provided on the side of the sample cavity, the radial pressure sensor is threadedly fixed to the threaded hole, and the sensor probe is arranged to contact the side wall of the sample.

[0010] Furthermore, the image acquisition module includes a module bracket and a high-definition camera and a ring-shaped fill light fixed on the module bracket. The high-definition camera is connected to the terminal signal. The image acquisition module ensures uniform illumination of the sample surface by adjusting the angle of the ring-shaped fill light.

[0011] Furthermore, the bottom surface of the acrylic transparent plate is in direct contact with the sample surface, and an annular sealing groove is provided in the upper surface of the sample cavity. The annular sealing groove surrounds the embedding groove and a silicone sealing ring is provided therein.

[0012] Furthermore, the light transmittance of the acrylic transparent plate is greater than 90%, thereby meeting the visual observation requirements of the experimental process.

[0013] Furthermore, the acrylic transparent plate is provided with a through hole connected to the embedded groove for discharging gas during the bentonite saturation process.

[0014] Furthermore, a limiting bolt is provided at the bottom of the acrylic transparent plate to prevent the application of additional axial stress.

[0015] Furthermore, the pipeline is provided with a one-way valve to prevent liquid backflow, and the permeable stone is made of porous ceramic material.

[0016] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0017] 1. The present invention realizes the visual real-time monitoring of the self-healing process of bentonite construction joints. By combining a highly transparent acrylic transparent plate with an image acquisition module, it realizes the high-definition real-time visual recording of the bentonite expansion and deformation process for the first time, providing important image data support for in-depth research on the bentonite self-healing mechanism.

[0018] 2. The device of the present invention optimizes the layout of pressure sensors. The axial sensor is installed in the bottom slot, and the radial sensor is threadedly fixed to the side wall of the cavity, which reduces external interference and significantly improves the measurement accuracy of expansion force anisotropy data.

[0019] 3. The device of the present invention integrates a paperless recorder to realize real-time, automatic recording and storage of test data, greatly reducing the error of manual data collection and improving test efficiency and reliability.

[0020] 4. The device of the present invention is equipped with a volume / pressure controller, which can accurately simulate the expansion of bentonite under various working conditions. It has strong test applicability and provides important experimental support and theoretical basis for the design of deep geological nuclear waste engineering barriers.

[0021] 5. The device of the present invention has a compact structure, convenient operation, moderate cost, and a high degree of automation, and is suitable for widespread promotion in relevant scientific research and engineering practice applications in the field of geotechnical engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is an overall structural diagram of the expansion force anisotropy testing device for bentonite construction joint self-healing of the present invention.

[0023] Figure 2 Schematic diagram of the assembly of the expansion force anisotropy testing device, volume / pressure controller and various force sensors of the present invention.

[0024] Figure 3 Schematic diagram of the installation of the image acquisition module in the expansion force anisotropy testing device of the present invention.

[0025] Among them, 1. Base; 2. Acrylic transparent plate; 3. Sample cavity; 4. Permeable stone; 5. Volume / pressure controller; 6. Axial stress sensor; 7. Radial stress sensor; 8. Paperless recorder; 9. High-definition camera; 10. Ring fill light; 11. Sample; 12. Silicone sealing ring; 13. Through hole; 14. Limit bolt. DETAILED DESCRIPTION

[0026] The following is a more detailed description of the anisotropic expansion force testing device for self-healing of bentonite construction joints of the present invention in conjunction with a schematic diagram, which shows a preferred embodiment of the present invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation of the present invention.

[0027] like Figure 1 As shown, a device for testing the anisotropic expansion force of bentonite construction joint self-healing includes a base 1, an acrylic transparent plate 2, a sample cavity 3, a permeable stone 4, a volume / pressure controller 5, a paperless recorder 8, a radial pressure sensor 7, an axial pressure sensor 6 and an image acquisition module, wherein the image acquisition module includes a module bracket, a high-definition camera 9 and a ring fill light 10.

[0028] The installation of the expansion force anisotropy test device includes:

[0029] 1. Overall assembly of the device

[0030] like Figure 2As shown, secure the base 1 horizontally to the test bench, ensuring its surface is flat. An annular groove is defined within the base 1, into which the axial pressure sensor 6 is inserted and secured with bolts. The force-bearing surface of the axial pressure sensor 6 faces upward, ensuring alignment with the groove at the bottom of the sample chamber 3. Mount the sample chamber 3 on the top surface of the base 1. A permeable stone 4, made of porous ceramic, is embedded in the bottom of the groove. Connect the volume / pressure controller 5 to the bottom of the permeable stone 4 via a pipeline. A check valve is installed at the pipeline interface to prevent liquid backflow.

[0031] 2. Installation of acrylic transparent plate 2 and sealing structure

[0032] An acrylic transparent plate 2 is placed over the upper surface of the sample chamber 3. The acrylic transparent plate 2 has an annular sealing groove embedded in it, into which a silicone sealing ring 12 is inserted. Bolts secure the acrylic transparent plate 2 to the sample chamber 3, ensuring uniform pressure on the silicone sealing ring 12 to form a sealed space. Limiting bolts 14 are also installed at the bottom of the acrylic transparent plate 2 to prevent the application of excessive axial stress.

[0033] 3. Pressure sensor installation and calibration

[0034] Connect the signal cable of the axial pressure sensor 6 to the paperless recorder 8 for zero point calibration. Create a threaded hole in the sidewall of the specimen chamber 3 and screw the radial pressure sensor 7 into the hole, extending the sensor probe of the radial pressure sensor 7 into the recess. Adjust the probe length so that it contacts the sidewall of the specimen 11, but avoid preload. Connect the signal cable to the paperless recorder 8 and calibrate the radial force measurement range.

[0035] 4. Image acquisition module integration

[0036] refer to Figure 3 Install the image acquisition module directly above the transparent acrylic plate 2. The module bracket is magnetically fixed to the test bench. An adjustable ring light 12 is attached to the module bracket to ensure uniform illumination of the surface of the specimen 11. Connect the HD camera 9 to the terminal (i.e., the computer), adjust the focal length and resolution, and set the real-time recording mode.

[0037] 5. Test operation process

[0038] Place the prepared sample 11 in the embedded groove, close to the lower surface of the acrylic transparent plate 2. Inject the test solution into the permeable stone 4 through the volume / pressure controller 5 until the sample 11 is completely immersed. Turn on the paperless recorder 8 to display the axial pressure and radial pressure data in real time. Start the image acquisition module, record the expansion and deformation process of the sample, and save the timestamp data synchronously. Adjust the solution pressure through the volume / pressure controller 5 to simulate different working conditions. Combine the image data (deformation variable) with the sensor data (pressure value) to generate the expansion force-deformation curve to illustrate the correlation mechanism between the joint self-healing process and the expansion force time history curve.

[0039] The above description is merely a preferred embodiment of the present invention and does not limit the present invention in any way. Any person skilled in the art who, without departing from the scope of the present invention, makes any equivalent substitution, modification, or other changes to the technical solution and technical content disclosed in the present invention shall be deemed to be within the scope of the present invention and still fall within the scope of protection of the present invention.

Claims

1. A device for testing the anisotropy of expansion force of bentonite construction joints for self-healing, characterized in that: The invention comprises a base (1), a sample cavity (3) is placed on the upper surface of the base, a groove is provided in the upper surface of the sample cavity and is covered with an acrylic transparent plate (2), the groove is used to place a sample (11), a permeable stone (4) is embedded in the bottom of the groove, and an image acquisition module connected to a terminal is mounted above the sample; The permeable stone is connected to a volume / pressure controller (5) via a pipeline, an axial pressure sensor (6) is provided between the base and the sample cavity, and a radial pressure sensor (7) connected to the sample is provided on the side of the sample cavity, and both the radial pressure sensor and the axial pressure sensor are connected to a paperless recorder (8) for signal transmission; The expansion force anisotropy testing device uses an image acquisition module to record the expansion deformation of the sample and the healing process of the construction joint in real time, uses an axial pressure sensor to measure the axial expansion force of the sample, and uses a radial pressure sensor to measure the radial expansion force of the sample, thereby completing a visual expansion force anisotropy test.

2. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 1, characterized in that: An annular groove is provided on the upper surface of the base, and the force-bearing surface of the axial sensor faces upward and is embedded in the annular groove, thereby achieving real-time measurement of the axial expansion force of the sample.

3. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 1, characterized in that: A threaded hole connected to the inside of the embedding groove is provided on the side of the sample cavity. The radial pressure sensor is threadedly fixed to the threaded hole, and the sensor probe is arranged in contact with the side wall of the sample.

4. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 1, characterized in that: The image acquisition module comprises a module bracket, a high-definition camera (9) and an annular fill light (10) fixed on the module bracket, the high-definition camera is connected to a terminal signal, and the image acquisition module ensures uniform illumination of the sample surface by adjusting the angle of the annular fill light.

5. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 1, characterized in that: The bottom surface of the acrylic transparent plate is in direct contact with the sample surface. An annular sealing groove is provided in the upper surface of the sample cavity. The annular sealing groove surrounds the embedding groove and is provided with a silicone sealing ring (12).

6. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 5, characterized in that: The light transmittance of the acrylic transparent plate is greater than 90%, thereby meeting the visual observation requirements of the experimental process.

7. The anisotropic expansion force testing device for bentonite construction joint self-healing according to claim 6, characterized in that: The acrylic transparent plate is provided with a through hole (13) communicating with the embedded groove, and is used for discharging gas generated during the test.

8. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 7, characterized in that: A limiting bolt is provided at the bottom of the acrylic transparent plate to prevent the application of additional axial stress.

9. The expansion force anisotropy testing device for bentonite construction joint self-healing according to claim 1, characterized in that: The pipeline is provided with a one-way valve to prevent liquid backflow, and the permeable stone is made of porous ceramic material.

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