Thermal-hydraulic-mechanical coupling visual test analysis system for hydraulic asphalt mixture seepage-proofing material and test method of thermal-hydraulic-mechanical coupling visual test analysis system

Abstract

The invention discloses a hydraulic asphalt mixture seepage-proofing material heat-water-force coupling visualization test analysis system and a test method thereof, and belongs to the technical field of hydraulic engineering material tests.The hydraulic asphalt mixture seepage-proofing material heat-water-force coupling visualization test analysis system comprises a clamp holder, a transparent heat shrink tube is arranged in an inner cavity of the clamp holder, and a hydraulic asphalt mixture seepage-proofing material is wrapped in the transparent heat shrink tube; the top of the clamp holder is connected with a loading and measuring subsystem, the loading and measuring subsystem is connected with a fluid control subsystem, the fluid control subsystem is connected with a temperature regulation and control subsystem, the clamp holder is externally connected with a visual observation subsystem, the visual observation subsystem is externally connected with a computer, and the computer is connected with a computer. The technical problem that an existing testing system cannot visually observe performance evolution in the asphalt mixture under the thermal-hydraulic-mechanical coupling effect is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic engineering material tests, and particularly relates to a thermal - water - hydraulic coupling visualization test analysis system for a hydraulic asphalt mixture impervious material and a test method thereof. Background Art

[0002] Hydraulic asphalt mixtures have strong impermeability due to their compact internal structure, can adapt to different climatic and geological conditions, have a simple construction process, do not require complex equipment technology, have a short cycle and low cost, and also have the durability of anti - aging and anti - erosion. When there is local damage, the impermeability performance can be restored through a simple repair process. It is a hydraulic engineering material with significant advantages. Researchers have started continuous research and practice on hydraulic asphalt concrete, which has promoted the development of the construction technology and theoretical research of asphalt concrete impervious bodies.

[0003] However, many researchers have found that water damage, low - temperature brittleness, and slope stability limit the large - scale application of asphalt impervious materials in hydraulic engineering. In particular, in extremely harsh environments such as high - cold and high - altitude areas, stress - seepage - temperature coupling is widespread. The performance evolution mechanism research of the weakening of the deformation and load - bearing capacity of hydraulic asphalt concrete materials, resulting in problems such as cracking, leakage, and failure, is extremely urgent. In recent years, a series of new devices have been developed to evaluate the water sensitivity of asphalt mixtures by comprehensively considering factors such as immersion, temperature, and mechanical loading. Scholars such as Momm developed a device that can independently conduct two - point bending complex modulus and fatigue tests on trapezoidal beam specimens in an immersion environment, and can adjust parameters such as a large temperature range, water flow rate, loading frequency, and deformation. The research found that the combined action of water and temperature will cause the performance of HMA specimens, such as complex modulus and fatigue life, to decline. Scholars such as Partl developed a test device that fixes annular specimens to a fixture with epoxy resin and places them in a water bath to conduct cyclic mechanical loading, and can test the mechanical property changes of specimens under the combined action of water, temperature, and load.

[0004] However, most of the above-mentioned studies are "invisible". Only some parameters can be measured upstream, downstream or on the surface of the specimen, and the internal performance evolution cannot be revealed, that is, the internal performance evolution of asphalt mixture under the coupled thermo-hydro-mechanical action cannot be visually observed. Chinese Patent CN117169082A discloses an asphalt concrete dynamic seepage test system and its test method for simulating vehicle load action, which realizes the simulation of dynamic seepage characteristics and long-term continuous monitoring of asphalt concrete under real vehicle load action, can continuously record seepage behavior for more than 48 hours, and reflects the dynamic seepage evolution of real asphalt pavement under reciprocating long-term vehicle load action. However, this test system mainly analyzes the seepage of asphalt concrete from the aspect of force, does not consider the influence of temperature, and cannot visually observe the internal performance evolution of asphalt mixture under the coupled thermo-hydro-mechanical action, so it is impossible to know the influence of factors such as immersion, temperature and mechanical loading on the water sensitivity of asphalt mixture. Aiming at this research defect, the present invention proposes a method for a visualization test system for asphalt composite materials under the coupled thermo-hydro-mechanical condition, which can directly observe the time-varying characteristics and evolution of performance such as the internal seepage path, internal pore evolution, strain deformation and temperature field evolution of the anti-seepage material of hydraulic asphalt mixture. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a thermo-hydro-mechanical coupling visualization test analysis system and its test method for the anti-seepage material of hydraulic asphalt mixture, which solves the technical problem that the existing test system cannot visually observe the internal performance evolution of asphalt mixture under the coupled thermo-hydro-mechanical action.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides a thermo-hydro-mechanical coupling visualization test analysis system for the anti-seepage material of hydraulic asphalt mixture, including a holder. A transparent heat-shrinkable tube is arranged in the inner cavity of the holder, and the anti-seepage material of hydraulic asphalt mixture is coated in the transparent heat-shrinkable tube. The top of the holder is connected with a loading and measuring subsystem, the loading and measuring subsystem is connected with a fluid control subsystem, the fluid control subsystem is connected with a temperature control subsystem, a visualization observation subsystem is connected to the outside of the holder, and the visualization observation subsystem is externally connected to a computer; The fluid control subsystem includes a first water tank. One end of the first water tank is connected with the loading and measuring subsystem through a top seepage channel, and the other end is connected with the holder through a bottom seepage channel. A high-precision piston pump is arranged on the first water tank.

[0007] In the above technical solution, the transparent heat-shrinkable tube is used to wrap the anti-seepage material, which is convenient for observing the specimen and is used to heat the anti-seepage material of hydraulic asphalt mixture from the outside.

[0008] In the above technical solution, pressure is applied by a liquid pressure pump, and a high-precision plunger pump injects seepage liquid and fluorescent magnetic particles into the impervious material of hydraulic asphalt mixture, so that both end faces and the ring of the impervious material of hydraulic asphalt mixture are subjected to uniform pressure. The pressure on both end faces simulates the tensile or compressive force received by the impervious material of hydraulic asphalt mixture, and the circumferential pressure simulates the lateral restraint force received by the impervious material of hydraulic asphalt mixture. Finally, a strain gauge senses the pressure change of the impervious material of hydraulic asphalt mixture, thereby controlling the pressure of the impervious material of hydraulic asphalt mixture, monitoring the deformation of the impervious material of hydraulic asphalt mixture in real time, and adjusting the pressure as needed.

[0009] Control principle of the high-precision plunger pump: It is equipped with a high-precision pressure sensor inside, which can monitor the output pressure of the high-precision plunger pump in real time and feed back the data to the controller. The controller automatically adjusts the movement speed and stroke of the high-precision plunger pump through an algorithm according to the feedback data of the pressure sensor, so as to achieve precise control of the pressure. The pressure sensor built in the high-precision plunger pump has the characteristics of high precision and low drift, and can achieve full-scale low-error pressure accuracy and drift under constant temperature conditions. The data collected by the pressure sensor is transmitted to a computer or other display device in real time through interfaces such as USB, which is convenient for real-time monitoring and recording.

[0010] Preferably, the visual observation subsystem includes a laser emitter 25, which is arranged on one side outside the gripper 4, and a micro-MRI receiver 26 is arranged on the other side; the computer 27 is connected to a three-dimensional XTDIC full-field strain measurement system 29 and several groups of high-speed CMOS cameras 28.

[0011] Preferably, there are 3 groups of the high-speed CMOS cameras 28, each group includes 2, and the 3 groups of high-speed CMOS cameras 28 are arranged at 120°.

[0012] In the above technical solution, the high-speed CMOS cameras collect images of the specimen during the loading process, and the XTDIC software processes the collected images. By real-time monitoring the data of the displacement sensor and the strain gauge, the displacement field and strain field on the surface of the specimen are calculated, and the damage evolution of the impervious material of hydraulic asphalt mixture during the loading process is recorded.

[0013] Preferably, the temperature control subsystem includes a material heating water tank 6-2-1, which is arranged between the first water tank 6-1 and the bottom seepage channel 7, and a transparent heat shrink tube heating water tank 6-2-2 is connected to the outside of the transparent heat shrink tube 1.

[0014] More preferably, heating elements 22 are arranged on the material heating water tank 6-2-1 and the transparent heat shrink tube heating water tank 6-2-2.

[0015] In the above technical solution, the material heating water tank is used to add water and heat the inside of the hydraulic asphalt mixture impermeable material, and the transparent heat shrinkable tube heating water tank is used to add water and heat the transparent heat shrinkable tube, so as to heat the hydraulic asphalt mixture impermeable material from the outside.

[0016] Preferably, a temperature regulator and a throttle valve are provided on the material heating water tank and the transparent heat shrinkable tube heating water tank.

[0017] In the above technical solution, the temperature regulator is used to set and maintain the temperature required for the test. When the temperature exceeds the set value, the heating element is turned off; when the temperature is lower than the set value, the heating element is turned on. The heating element is used to provide heat to heat the test environment or the sample hydraulic asphalt mixture impermeable material to the set temperature, and the power and heating rate of the heating element are controlled by the temperature regulator. In the above technical solution, the throttle valve is used to regulate the fluid flow rate from the material heating water tank and the transparent heat shrinkable tube heating water tank to the hydraulic asphalt mixture impermeable material and the transparent heat shrinkable tube, and the temperature of the hydraulic asphalt mixture impermeable material is regulated by controlling the fluid flow rate. Specifically, when cooling is required, the throttle valve is opened, and at the same time, the heating elements in the material heating water tank and the transparent heat shrinkable tube heating water tank are turned off, and a cooling medium is added to the first water tank, thereby increasing the flow rate of the cooling medium, so that the temperature of the fluid flowing to the hydraulic asphalt mixture impermeable material and the transparent heat shrinkable tube is reduced, achieving the effect of reducing the temperature of the hydraulic asphalt mixture impermeable material; when heating is required, the heating elements in the material heating water tank and the transparent heat shrinkable tube heating water tank are turned on, and the throttle valve is closed or reduced, so that the temperature of the fluid flowing to the hydraulic asphalt mixture impermeable material and the transparent heat shrinkable tube is increased, thereby achieving the effect of increasing the temperature of the hydraulic asphalt mixture impermeable material.

[0018] Preferably, the loading and measuring subsystem includes a transparent pressure chamber, which is arranged between the gripper and the transparent heat shrinkable tube, and an oil storage tank is externally connected to the transparent pressure chamber.

[0019] More preferably, a confining pressure and back pressure control device 16 is provided on the oil storage tank 15.

[0020] Preferably, the loading and measuring subsystem further includes a cross beam, the top of the cross beam is connected to an axial pressurizing device through an axial rod, and a motor is connected to the axial pressurizing device.

[0021] Preferably, a temperature sensor, a displacement sensor and a strain gauge are arranged inside the hydraulic asphalt mixture impermeable material, and the temperature sensor, the displacement sensor and the strain gauge are electrically connected to a data acquisition box, and the data acquisition box is arranged outside the hydraulic asphalt mixture impermeable material.

[0022] In the above technical solution, the temperature sensor is used to monitor the temperature of the test environment or the specimen in real time and transmit the data to the temperature regulator. The strain gauge is usually placed in the stress concentration or key deformation area to monitor the local deformation of the hydraulic asphalt mixture impervious material; the displacement sensor is installed above the hydraulic asphalt mixture impervious material to monitor the shear deformation of the specimen during the compression process; the temperature sensors are evenly distributed inside the hydraulic asphalt mixture impervious material, especially in the areas with large temperature gradients.

[0023] Preferably, a permeable plate is provided at the bottom of the hydraulic asphalt mixture impervious material.

[0024] In the above technical solution, the function of the permeable plate is to enable the seepage liquid and fluorescent magnetic particles to enter the hydraulic asphalt mixture impervious material more evenly and controllably through the permeable plate. At the same time, it can also support the hydraulic asphalt mixture impervious material to prevent water accumulation at its bottom.

[0025] The present invention also provides a method for conducting tests using the above thermal-hydro-mechanical coupling visualization test analysis system for the hydraulic asphalt mixture impervious material, including the following steps: 1) Load the hydraulic asphalt mixture impervious material into the clamp, and inject seepage liquid and fluorescent magnetic particles into the first water tank; 2) Turn on the visual observation subsystem, adjust its visual range to cover the entire hydraulic asphalt mixture impervious material, extract the cross-sectional slice images, and then adjust the laser section angle so that the visual observation subsystem vertically enters the hydraulic asphalt mixture impervious material to form a speckle field; 3) Turn on the temperature control subsystem to heat the inside and outer walls of the hydraulic asphalt mixture impervious material simultaneously; 4) Turn on the loading and measurement subsystem, set the confining pressure of the hydraulic asphalt mixture impervious material to a fixed value, and then apply an axial pressure to the top of the hydraulic asphalt mixture impervious material; 5) Open the top seepage channel and the bottom seepage channel to allow the seepage liquid and fluorescent magnetic particles to enter the clamping cavity through the permeable plate; 6) Use a computer to record the damage morphology, seepage morphology and experimental data of the hydraulic asphalt mixture impervious material at each stage.

[0026] Further preferably, a valve is provided in each of the top seepage channel and the bottom seepage channel to control the opening and closing of the two channels.

[0027] The above technical solution achieves the following technical effects through the coordinated action of each step: 1. Through fluorescence tracing (Step 1) and multimodal observation (Steps 2 and 6), the in-situ visualization of seepage paths, deformation fields, and temperature fields is achieved, intuitively presenting the internal performance evolution of materials and overcoming the limitation that existing testing systems cannot directly observe the internal performance evolution of asphalt mixtures under thermo-hydro-mechanical coupling; 2. The independent control and synchronous loading of confining pressure, axial load, temperature, and seepage (Steps 3, 4, and 5) accurately reproduce the thermo-hydro-mechanical multi-field coupling environment, overcoming the deficiency of single physical field simulation; 3. Through the data fusion of multiple sensors and observation devices, the full-scale correlation of apparent deformation-internal seepage-microstructure is established to support engineering life prediction, overcoming data fragmentation and lack of correlation.

[0028] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a thermo-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impervious materials, constructs a complete test platform for thermo-hydro-mechanical multi-field coupling, and realizes the in-situ observation of the internal performance evolution of asphalt materials under high pressure, seepage, and temperature changes. In this application, the hydraulic asphalt mixture impervious material (specimen) is wrapped with a transparent heat-shrinkable tube to ensure isolation from the external environment while maintaining transparency to support optical (laser, camera) and MRI observations, enabling direct observation of the internal seepage path of the specimen and avoiding destructive sampling; at the same time, multiple subsystems are connected. Specifically, the loading and measurement subsystem simulates the multi-axial stress state in actual engineering to quantify the stress-seepage coupling effect; the fluid control subsystem simulates the groundwater pressure gradient to quantify the permeability coefficient; the temperature regulation subsystem simulates the influence of geothermal or environmental temperature changes on asphalt materials; the visualization observation subsystem captures the three-dimensional seepage field and records the surface deformation. Thus, the purpose of intuitively observing the internal performance evolution of asphalt mixtures under thermo-hydro-mechanical coupling is achieved.

[0029] Furthermore, by setting up a visualization observation system to capture the surface-internal performance evolution process of materials on a full scale, the laser emitter excites the fluorescence magnetic particles to emit light to display the two-dimensional seepage field, and the micro-MRI receiver uses the hydrogen proton resonance signal to reconstruct the three-dimensional distribution of seepage liquid, realizing micro-macro seepage visualization.

[0030] Furthermore, three groups of high-speed CMOS cameras are arranged at 120°, and combined with digital image correlation technology, the surface crack propagation and full-field strain are captured.

[0031] Furthermore, the material heating water tank directly controls the internal temperature of the specimen to simulate the self-thermal conduction effect of the material. The transparent heat-shrinkable tube heating water tank realizes the heating of the outer wall of the transparent heat-shrinkable tube, avoiding deformation or rupture of the transparent heat-shrinkable tube caused by temperature difference and ensuring the observation stability. The two cooperate synergistically to accurately control the temperature of the hydraulic asphalt mixture impermeable material, thereby simulating different environmental temperature conditions and further enhancing the practicability and adaptability of the system.

[0032] Furthermore, the introduction of the throttle valve and the temperature regulator allows for more precise adjustment of the fluid flow rate, which helps to study the performance changes of the impermeable material at different flow velocities. At the same time, the temperature regulator is linked with the throttle valve. By adjusting the fluid flow rate and heating power, it can quickly respond to temperature changes and reduce the thermal lag effect.

[0033] Furthermore, the setting of the transparent pressure chamber enables the application of confining pressure to the material without disturbing the experimental environment. The incompressibility of the hydraulic oil in the transparent pressure chamber ensures uniform transmission of the confining pressure to the specimen surface. The transparent material allows unobstructed observation by lasers and cameras, facilitating the observation of the internal deformation of the material.

[0034] Furthermore, a pressure is applied to the specimen by pushing the axial rod with a motor to achieve multi-axial stress loading, simulating the complex stress state in actual engineering. The rigid frame of the crossbeam disperses the load, ensuring that the axial force acts vertically on the top of the specimen and avoiding stress non-uniformity caused by eccentric loading.

[0035] Furthermore, by setting temperature sensors to measure the temperature gradient, displacement sensors to monitor the axial compression of the specimen, and strain gauges to measure local strain, the internal temperature, deformation, and strain of the material are monitored in real time to construct a multi-field coupling constitutive model. The data acquisition box integrates a multi-channel signal conditioning module to convert the sensor signals into digital quantities and transmit them to the computer.

[0036] Furthermore, the permeable plate enables the seepage liquid and fluorescent magnetic particles to enter the hydraulic asphalt mixture impermeable material more uniformly and controllably through the permeable plate. At the same time, it can also support the hydraulic asphalt mixture impermeable material to prevent water accumulation at its bottom.

[0037] The present invention also provides a method for conducting tests using the above-mentioned thermal-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impermeable materials. First, by injecting fluorescent magnetic particles as tracers into the first water tank, it is beneficial to capture their movement trajectories through lasers and MRI subsequently, directly visualizing the seepage path and flow velocity distribution, and breaking through the limitation of traditional penetration experiments that only rely on indirect calculation of flow rate-pressure difference. Second, by vertically irradiating the specimen through the visualization observation subsystem, exciting the fluorescent particles and forming high-contrast speckles, providing a reference image for the full-field strain calculation of the XTDIC system and improving the deformation measurement accuracy. Third, by applying confining pressure and axial stress through the loading and measurement subsystem, simulating the high-confining pressure environment of deep strata and the multi-axial loads in engineering, the combined action of confining pressure and axial pressure restricts the specimen deformation and changes the pore structure, quantifying the influence of stress state on permeability. Fourth, by maintaining the pressure at the top seepage channel and the bottom seepage channel with a plunger pump, forming a stable seepage pressure difference to ensure the authenticity of the permeability coefficient test. If the temperature control subsystem is enabled, the seepage liquid is heated to the set temperature to synchronously study the coupling effect of temperature-seepage-stress. Fifth, the visualization observation subsystem captures the three-dimensional movement trajectories of the fluorescent particles, generates seepage path and porosity distribution maps, the high-speed camera combines with the XTDIC system to calculate the full-field strain, identify the initiation and propagation of cracks, and the temperature sensor and displacement sensor real-time feedback the internal temperature change and compression amount of the specimen. Finally, integrating the data of heat (temperature), water (seepage velocity, path), and force (stress-strain), constructing a multi-field coupling constitutive model to reveal the degradation mechanism of asphalt materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is a basic flow chart of the present invention; Wherein, 1 - transparent heat shrinkable tube; 2 - transparent pressure chamber; 3 - hydraulic asphalt mixture impermeable material; 4 - clamp; 5 - high-precision plunger pump; 6-1 first water tank; 6-2-1 material heating water tank; 6-2-2 transparent heat shrinkable tube heating water tank; 7 - bottom seepage channel; 8 - permeable plate; 9 - top seepage channel; 10 - data acquisition box; 11 - temperature sensor; 12 - displacement sensor; 13 - strain gauge; 14 - hydraulic pipeline system; 15 - oil storage tank; 16 - confining pressure and back pressure control device; 17 - axial pressurizing device; 18 - motor; 19 - cross beam; 20 - axial rod; 21 - temperature regulator; 22 - heating element; 23 - throttle valve; 24 - fluorescent magnetic particle; 25 - laser emitter; 26 - micro-MRI receiver; 27 - computer; 28 - high-speed CMOS camera; 29 - three-dimensional XTDIC full-field strain measurement system; 30 - liquid pressurizing pump; 31 - controller. DETAILED DESCRIPTION OF THE INVENTION

[0039] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0041] This application is based on micro-MRI (laser emitter 25 and micro-MRI receiver 26), and a three-dimensional XTDIC full-field strain measurement system 29 to develop a stress-seepage-temperature coupling visualization test system for hydraulic asphalt mixture impermeable materials. The system mainly includes a specimen clamping subsystem, a fluid control subsystem, a temperature control subsystem, a loading and measurement subsystem, and a visualization observation subsystem.

[0042] The following will further describe the present invention in detail with reference to the accompanying drawings: Embodiment 1 As Figure 1 shown, the present invention provides a thermal-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impermeable materials, including a clamp 4. A transparent heat-shrinkable tube 1 is arranged in the inner cavity of the clamp 4, and a hydraulic asphalt mixture impermeable material 3 is coated in the transparent heat-shrinkable tube 1. The top of the clamp 4 is connected to a loading and measurement subsystem, the loading and measurement subsystem is connected to a fluid control subsystem, the fluid control subsystem is connected to a temperature control subsystem, a visualization observation subsystem is arranged outside the clamp 4, and the visualization observation subsystem is externally connected to a computer 27; The fluid control subsystem includes a first water tank 6-1. One end of the first water tank 6-1 is connected to the loading and measurement subsystem through a top seepage channel 9, and the other end is connected to the clamp 4 through a bottom seepage channel 7. A high-precision plunger pump 5 is arranged on the first water tank 6-1.

[0043] Further preferably, a liquid pressure pump 30 is provided at the top of the high-precision plunger pump 5, and a controller 31 is provided inside the high-precision plunger pump 5.

[0044] Preferably, the specimen clamping subsystem includes using a special transparent heat-shrinkable tube 1 to wrap the specimen 3 of the hydraulic asphalt mixture impervious material and fixing it inside the cavity of the gripper 4.

[0045] Preferably, the fluid control subsystem is used to apply the osmotic pressure and includes a first water tank 6-1. One end of the first water tank 6-1 is connected to the loading and measuring subsystem through the top seepage channel 9, and the other end is connected to the gripper 4 through the bottom seepage channel 7. A high-precision plunger pump 5 is provided on the first water tank 6-1.

[0046] In the above technical solution, the high-precision plunger pump 5 mainly realizes the control and measurement of the seepage pressure. The pressure in the cavity can be controlled by means of the high-precision plunger pump 5 to apply loads to both end faces and the circumferential direction of the specimen.

[0047] Preferably, the loading and measuring subsystem includes a transparent pressure chamber 2, which is arranged between the gripper 4 and the transparent heat-shrinkable tube 1. An oil storage device 15 is connected to the outside of the transparent pressure chamber 2.

[0048] Further preferably, a confining pressure and back pressure control device 16 is provided on the oil storage device 15.

[0049] Preferably, the loading and measuring subsystem further includes a cross beam 19. The top of the cross beam 19 is connected to an axial pressurizing device 17 through an axial rod 20, and a motor 18 is connected to the axial pressurizing device 17.

[0050] Further preferably, transparent pressure chambers 2 are provided at both ends of the gripper 4 and around the transparent heat-shrinkable tube 1.

[0051] In the above technical solution, the transparent pressure chamber 2 is filled with hydraulic oil with a certain pressure around the specimen. The axial loading device 17 lifts the transparent pressure chamber 2 by starting the motor 18, so that it applies a reaction force to the specimen through the axial rod 20 perpendicular to the cross beam 19.

[0052] Preferably, the temperature control subsystem includes a material heating water tank 6-2-1, which is arranged between the first water tank 6-1 and the bottom seepage channel 7. A transparent heat-shrinkable tube heating water tank 6-2-2 is connected to the outside of the transparent heat-shrinkable tube 1.

[0053] Preferably, a temperature regulator 21 and a throttle valve 23 are provided on the material heating water tank 6-2-1 and the transparent heat-shrinkable tube heating water tank 6-2-2. The test pipeline and the ambient temperature during the whole test process can be adjusted and controlled.

[0054] Further preferably, heating elements 22 are provided on the material heating water tank 6-2-1 and the transparent heat-shrinkable tube heating water tank 6-2-2.

[0055] In the above technical solution, the temperature generated by the heating element 22 is sent to every corner of the test system through pipelines.

[0056] Preferably, a temperature sensor 11, a displacement sensor 12 and a strain gauge 13 are arranged in the hydraulic asphalt mixture impervious material 3. The temperature sensor 11, the displacement sensor 12 and the strain gauge 13 are electrically connected to a data acquisition box 10, and the data acquisition box 10 is arranged outside the hydraulic asphalt mixture impervious material 3.

[0057] In the above technical solution, the temperature sensor 11 and the computer program are used to collect the ambient temperature inside the cavity of the gripper 4 and on the surface of the specimen.

[0058] Further preferably, at the top of the specimen in the transparent pressure chamber 2, it is connected to the temperature sensor 11 and the displacement sensor 12, and at the bottom of the specimen, it is connected to the strain gauge 13.

[0059] A permeable plate 8 is provided at the bottom of the hydraulic asphalt mixture impervious material 3.

[0060] The visualization observation system applies a micro-MRI laser emitter 25, a micro-MRI receiver 26, and a three-dimensional XTDIC full-field strain measurement system 29 to record the evolution processes of the seepage field, damage field, and temperature field of the hydraulic asphalt mixture impervious material 3, and uses the three-dimensional XTDIC full-field strain measurement system 29 to record the evolution process of the soil / rock mass structure. The specific operation steps for the visualization of the seepage field and strain field are as follows: In the experiment, to achieve the visualization of the seepage field, a micro-MRI (laser emitter 25 and micro-MRI receiver 26) is used. Fluorescent magnetic particles 24 with a diameter of about 5 - 10 μm are added as tracers to the seepage liquid (previous experiments have proved that the seepage liquid will not react with the fluorescent magnetic particles 24); a double-pulse green Nd:YAG laser with a maximum energy of 30 mJ / pulse is used to form a laser sheet with a thickness of about 0.8 mm to illuminate the tracer particles in the flow domain; this system combines a micro-MRI (laser emitter 25 and micro-MRI receiver 26) to collect images of particle movement, and provides analysis software (DaVis 10.0) to process the captured images and calculate the flow field. The data during the experiment is transmitted into the computer 27 in real time.

[0061] In the experiment, to visualize the strain field, the three-dimensional XTDIC full-field strain measurement system 29 technology can accurately monitor the surface strain field during the progressive failure process of the hydraulic asphalt mixture impervious material 3, and can also observe the surface damage or crack propagation of the specimen under the action of load. In the three-dimensional XTDIC full-field strain measurement system 29, two cameras 28 form a group, and three groups of cameras 28 are evenly arranged around the visualization triaxial transparent pressure chamber 2 at 120°. During the experiment, the data acquisition system is turned on to collect data such as axial force, specimen surface deformation pictures, and top and bottom flow rates until the specimen fails and the experiment is terminated.

[0062] The above test method is used to carry out the thermo-hydro-mechanical coupling experiment.

[0063] First, a core drill is used to drill and polish the hydraulic asphalt mixture impervious material 3 (specimen) into specimens with a size of Φ50×100 mm. Then, the prepared specimens are dried in an oven at 80 °C for 48 h.

[0064] The experiment mainly studies the multi-field coupling mechanism of stress-temperature-seepage of the asphalt mixture impervious material specimen 3 under different temperatures (20, 40, 60 °C), different confining pressures (2, 4, 6 MPa), and variable axial pressures of 0-9 MPa.

[0065] The nitrogen seepage pressure at the test inlet is 0.5 MPa, and the outlet pressure is 0.1 MPa. Before the test starts, the prepared hydraulic asphalt mixture impervious material 3 is loaded into the model holder 4, the prepared seepage liquid is injected into the water tank 6 and a fluorescent agent is added, and the initial temperature of the specimen is set through the temperature control system.

[0066] After the test starts: Step 1: Turn on the laser emitter 25 and the micro-MRI receiver 26, and adjust the visual range to include the entire specimen, and extract cross-sectional slice images for later three-dimensional reconstruction of the specimen; Step 2: Turn on the laser emitter 25 and adjust the laser cutting plane angle so that it vertically enters the saturated transparent soil sample to form a speckle field; Step 3: Turn on the confining pressure backpressure control device 16, and the hydraulic oil connects the oil storage tank 15 with the hydraulic oil in the transparent pressure chamber 2 through the hydraulic pipeline system 14, so that the confining pressure applied by the confining pressure supply source acts on the specimen through the transmission of the hydraulic oil, and set the specimen confining pressure to a fixed value; Step 4: Turn on the motor 18 to apply axial pressure to the top of the specimen; Step 5: Turn on the inlet water valve and the outlet water valve, so that the seepage liquid enters the clamping cavity 4 through the permeable plate 8; Step 6: Use the computer 27 to record the damage morphology of the specimens, the seepage morphology, and the data of the data acquisition box 10 and the temperature sensor 11 in each period.

[0067] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. Visual test analysis system for thermo-hydro-mechanical coupling of hydraulic asphalt mixture impervious material, characterized in that, It includes a gripper (4). A transparent heat-shrinkable tube (1) is arranged in the inner cavity of the gripper (4). A hydraulic asphalt mixture anti-seepage material (3) is wrapped in the transparent heat-shrinkable tube (1). The top of the gripper (4) is connected to a loading and measuring subsystem. The loading and measuring subsystem is connected to a fluid control subsystem. The fluid control subsystem is connected to a temperature regulation subsystem. A visual observation subsystem is arranged outside the gripper (4). The visual observation subsystem is externally connected to a computer (27). The fluid control subsystem includes a first water tank (6-1). One end of the first water tank (6-1) is connected to the loading and measuring subsystem through a top seepage channel (9), and the other end is connected to the gripper (4) through a bottom seepage channel (7). A high-precision piston pump (5) is arranged on the first water tank (6-1).

2. The thermo-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 1, characterized in that The visual observation subsystem includes a laser emitter (25). The laser emitter (25) is arranged on one side outside the gripper (4), and a micro-MRI receiver (26) is arranged on the other side. The computer (27) is connected to a three-dimensional XTDIC full-field strain measurement system (29) and several groups of high-speed CMOS cameras (28).

3. The thermo-hydro-mechanical coupled visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 2, characterized in that There are 3 groups of the high-speed CMOS cameras (28). Each group includes 2 cameras. The 3 groups of high-speed CMOS cameras (28) are arranged at 120°.

4. The thermo-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 1, characterized in that The temperature regulation subsystem includes a material heating water tank (6-2-1). The material heating water tank (6-2-1) is arranged between the first water tank (6-1) and the bottom seepage channel (7). A transparent heat-shrinkable tube heating water tank (6-2-2) is connected to the outside of the transparent heat-shrinkable tube (1).

5. The thermo-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impervious material according to claim 4, characterized in that Temperature regulators (21) and throttle valves (23) are arranged on the material heating water tank (6-2-1) and the transparent heat-shrinkable tube heating water tank (6-2-2).

6. The thermo-hydro-mechanical coupled visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 1, characterized in that The loading and measuring subsystem includes a transparent pressure chamber (2). The transparent pressure chamber (2) is arranged between the gripper (4) and the transparent heat-shrinkable tube (1). An oil storage tank (15) is connected to the outside of the transparent pressure chamber (2).

7. The thermo-hydro-mechanical coupled visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 1, characterized in that The loading and measuring subsystem further includes a cross beam (19). The top of the cross beam (19) is connected to an axial pressing device (17) through an axial rod (20). A motor (18) is connected to the axial pressing device (17).

8. The thermo-hydro-mechanical coupled visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 1, wherein A temperature sensor (11), a displacement sensor (12) and a strain gauge (13) are arranged in the hydraulic asphalt mixture anti-seepage material (3). The temperature sensor (11), the displacement sensor (12) and the strain gauge (13) are electrically connected to a data acquisition box (10). The data acquisition box (10) is arranged outside the hydraulic asphalt mixture anti-seepage material (3).

9. The thermo-hydro-mechanical coupled visualization test analysis system for hydraulic asphalt mixture impervious materials according to claim 1, characterized in that A permeable plate (8) is arranged at the bottom of the hydraulic asphalt mixture anti-seepage material (3).

10. A method of conducting tests using the thermo-hydro-mechanical coupling visualization test analysis system for hydraulic asphalt mixture impervious materials described in claims 1 to 9, characterized in that, It includes the following steps: Load the hydraulic asphalt mixture anti-seepage material (3) into the inner cavity of the transparent heat-shrinkable tube (1), and inject seepage liquid and fluorescent magnetic particles (24) into the first water tank (6-1). Turn on the visual observation subsystem, adjust its visual range to cover the entire hydraulic asphalt mixture impervious material (3), and make the visual observation subsystem vertically irradiate into the hydraulic asphalt mixture impervious material (3) to form a speckle field; Turn on the temperature control subsystem to heat the interior and outer wall of the hydraulic asphalt mixture impervious material (3) simultaneously; Turn on the loading and measurement subsystem, set the confining pressure of the hydraulic asphalt mixture impervious material (3) to a fixed value, and then apply the axial pressure to the top of the hydraulic asphalt mixture impervious material (3); Open the top seepage channel (9) and the bottom seepage channel (7) to allow the seepage liquid and fluorescent magnetic particles (24) to enter the interior of the hydraulic asphalt mixture impervious material (3), and control the pressures of the top seepage channel (9) and the bottom seepage channel (7) through a high-precision plunger pump (5); Use a computer (27) to record the damage morphology, seepage morphology, and experimental data of the hydraulic asphalt mixture impervious material (3) at each stage.

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