Experimental apparatus and method for high-temperature rock thermal shock treatment

Abstract

This invention provides an experimental apparatus and method for rapidly cooling high-temperature rocks to induce thermal shock and for monitoring thermal shock damage during the process. The apparatus includes a heating furnace and a cooling tank. An upper water inlet connected to a storage tank allows coolant to be introduced into the cooling tank, while a lower water inlet allows coolant to flow out. Both the upper and lower water inlets are equipped with orifice flow meters. By setting the same flow rates for both inlet and outlet water, the coolant in the cooling tank can be kept flowing stably, thus maintaining a constant temperature of the coolant within the tank during the cooling of the high-temperature rocks. This invention enables rapid cooling of high-temperature rocks in a constant temperature field to induce thermal shock, and utilizes optical and acoustic technologies to achieve real-time monitoring of the evolution of internal thermal damage during the thermal shock process, allowing for quantitative characterization of the thermal shock damage in high-temperature rocks.

Description

Technical Field

[0001] This invention relates to the fields of rock mechanics and rock engineering disasters related to high temperature in deep underground engineering such as deep geothermal development and deep drilling, and in particular to a high-temperature rock thermal shock treatment experimental device and experimental method for monitoring rock damage during thermal shock by rapidly cooling. Background Technology

[0002] In the development and utilization of deep resources, high-temperature rock masses are not always at a relatively stable temperature; sometimes they experience rapid temperature changes, a process known as thermal shock. The thermal stress generated by thermal shock in the rock leads to the initiation and development of thermal cracks, thus affecting the physical and mechanical properties of the rock. While thermal shock in high-temperature rock masses facilitates the extraction of deep resources, it also threatens the safety of rock engineering. For example, during deep drilling, the drilling fluid cools the drill bit while simultaneously applying thermal shock to the surrounding rock, increasing the number of thermal cracks. This improves rock-breaking efficiency and makes drilling easier, but it also damages the wellbore, leading to rock deterioration and safety hazards. In deep geothermal development, geothermal energy is utilized by injecting cold water into the reservoir rock layer and then extracting hot water. While the hot rock exchanges heat with the cold water, it is also subjected to thermal shock. The resulting cracks increase heat exchange channels and improve heat extraction efficiency. However, thermal shock can also cause the geothermal wellbore to rupture, leading to borehole collapse and affecting the safe operation of the geothermal well.

[0003] Furthermore, in high-temperature-related disasters occurring in rock engineering (such as heat hazards in deep mineral deposits, tunnel or mine fires, etc.), the impact of thermal shock on the surrounding rock cannot be ignored. Fires in rock engineering expose the surrounding rock to a sudden high-temperature environment, and during firefighting, the surrounding rock undergoes rapid cooling. The resulting thermal shock can lead to cracking and instability of the surrounding rock, and the deterioration of the rock mass can significantly affect the stability and service life of the engineering structure. In summary, the topic of thermal shock damage to rocks has become a relatively active research direction in rock mechanics.

[0004] Currently, researchers mostly use indoor experiments to study the thermal shock phenomenon of rocks. However, there is a lack of established experimental platforms for thermal shock treatment of rock samples, resulting in the treatment effect being significantly affected by human factors. Common methods involve directly placing high-temperature samples in cooling media such as air, water, or liquid nitrogen, which cannot ensure the uniformity of the temperature field of the cooling medium during the thermal shock process. Current thermal shock treatments often use a single cooling medium (e.g., room temperature water or -196°C liquid nitrogen). This results in a relatively uniform cooling rate for the rock samples, making it impossible to compare the thermal shock test results under different cooling rates in the same cooling medium.

[0005] Furthermore, the lack of supporting experimental equipment makes it impossible to monitor the thermal shock damage state of the sample in real time during the thermal shock process, which affects people's understanding of the thermal shock damage mechanism and damage law.

[0006] Thermal stress generated in high-temperature rocks subjected to thermal shock can lead to localized stress concentration, resulting in thermal cracking and rock damage. Methods for observing rock damage include scanning electron microscopy (SEM) and polarized light microscopy; however, these methods require cutting or slicing the rock sample, which cannot maintain the integrity of the specimen. Furthermore, the observable range is limited, making them unsuitable for describing the overall damage of the rock sample. Non-destructive testing methods are also widely used for monitoring rock sample damage, such as acoustic emission (AE), computed tomography (CT), ultrasound, and digital image correlation (DIC) techniques. Acoustic emission, as an acoustic observation technique, utilizes the characteristic that some of the energy stored during crack formation and propagation is released as elastic waves to monitor the sound wave signal, thereby enabling real-time monitoring of the time, spatial location, and energy magnitude of internal rock damage. The propagation velocity of elastic waves in rock can characterize the integrity and density of the rock's internal structure; measuring changes in elastic wave velocity can reflect changes in the rock's internal microstructure and the degree of damage.

[0007] Digital speckle image analysis (DIC) is a global image analysis method based on grayscale digital images. It can calculate the changes in the three-dimensional coordinates, displacement field, and strain field of the surface during deformation by tracking changes in the digital speckle image of the surface of the object being measured. DIC can be used to measure the deformation of rock sample surfaces during thermal shock, identify the initiation and propagation paths of thermal cracks, and analyze the evolution of thermal shock damage.

[0008] Currently, there is a lack of devices for real-time monitoring of rock sample damage during thermal shock. Therefore, developing a rock thermal shock damage evolution monitoring device based on non-destructive technology is of great significance for quantitative characterization of rock thermal shock damage and analysis of aging deformation, thermal damage evolution law and progressive fracture mechanism under high temperature rock thermal shock conditions.

[0009] In view of this, it is necessary to design a high-temperature rock thermal shock treatment experimental device to solve the above problems. Summary of the Invention

[0010] The purpose of this invention is to provide an experimental device and method for high-temperature rock thermal shock treatment that achieves thermal shock treatment of high-temperature rocks through rapid cooling and monitors rock damage during the thermal shock process, so as to quantitatively characterize the thermal shock damage of rocks and help explore the damage mechanism inside rocks under thermal shock.

[0011] To achieve the above-mentioned objectives, this invention provides a high-temperature rock thermal shock treatment experimental apparatus, including a heating furnace for heating and heat preservation of rock samples; a storage tank for storing coolant; and an ultra-low temperature freezer for cooling the coolant and placing the prepared coolant.

[0012] A cooling tank, connected to the liquid storage tank, is used to load coolant to rapidly cool the rock sample in order to achieve thermal shock treatment of the rock sample.

[0013] A sample fixing device is installed inside the cooling tank to fix the rock sample and make the rock sample fit against the acoustic emission sensing probe.

[0014] A sample clamp is used to clamp a high-temperature sample from the heating furnace onto the sample fixing device in the cooling tank;

[0015] Acoustic emission monitoring equipment is used to monitor the acoustic signals of thermal damage to rock samples during thermal shock.

[0016] The DIC observation instrument is used to observe the entire process of surface crack propagation during thermal shock of rock samples.

[0017] Ultrasonic testing equipment is used to detect the longitudinal and transverse wave velocities of rock samples in real time before and after thermal shock.

[0018] A water inlet tap is provided between the upper end of the cooling tank and the liquid storage tank to control the connection between the two. A water outlet tap is provided at the lower end of the cooling tank. Both the water inlet tap and the water outlet tap are equipped with orifice plate flow meters. By controlling the water flow rates of the water inlet tap and the water outlet tap, the coolant in the cooling tank is kept to flow stably, thereby keeping the temperature of the coolant in the tank constant during the cooling of high-temperature rocks.

[0019] As a further improvement of the present invention, the cooling tank includes an inner wall, an outer wall, and an insulation interlayer between the inner wall and the outer wall, wherein the insulation interlayer is filled with insulation material; the inner wall of the cooling tank is made of corrosion-resistant stainless steel, and the longitudinal section of the inner wall is rectangular at the top and inverted trapezoidal at the bottom. A support portion is provided at the connection between the rectangle and the inverted trapezoid, which protrudes from the inner wall surface into the cooling tank and is used to support the sample fixing device.

[0020] As a further improvement of the present invention, the sample fixing device includes a disc base and four vertical clamp units disposed at the center of the disc base; each vertical clamp unit includes a perforated column and a fixing clip arranged parallel to each other, and two waveguide rods inserted into the perforated column. One end of the waveguide rod passes through the hole on the fixing clip and contacts the rock sample, and the other end is fitted with an acoustic emission sensor probe fixing cap, and an acoustic emission sensor probe is disposed inside the acoustic emission sensor probe fixing cap.

[0021] As a further improvement of the present invention, the perforated vertical column and the fixing clip are respectively provided with three holes for the waveguide rod to pass through. A spring is sleeved on the waveguide rod, one end of the spring abutting against the perforated vertical column and the other end abutting against the fixing clip.

[0022] As a further improvement of the present invention, the ultrasonic testing device includes a transmitting end sensor disposed on the top of the sample fixing device and a receiving end sensor disposed on the disc base of the sample fixing device.

[0023] As a further improvement of the present invention, the horizontal plane at which the bottom surface of the liquid storage tank is located is higher than the horizontal plane at which the top surface of the main body of the cooling tank is located.

[0024] As a further improvement of the present invention, an optical observation window is provided on one side of the cooling tank, and the DIC observer is positioned directly opposite the optical observation window to observe the entire process of crack propagation on the surface of the rock sample through a high-precision lens.

[0025] As a further improvement of the present invention, a spray nozzle connected to the liquid storage tank is also provided on the inner wall of the cooling tank.

[0026] As a further improvement of the present invention, the acoustic emission monitoring device includes an acoustic emission sensing probe, a signal repeater, an acoustic emission data receiving end, and a data transmission pipeline; the acoustic emission sensing probe is used to receive the acoustic signal emitted by the rock sample during the thermal shock process in real time; the signal repeater is used to decode the received acoustic signal, convert the acoustic signal into an electrical signal, and transmit the signal data; and the acoustic emission data receiving end is used to receive and analyze the data.

[0027] The present invention also provides an experimental method for a high-temperature rock thermal shock treatment experimental apparatus, comprising the following steps:

[0028] S1, The rock sample is heated to the target temperature using a heating furnace and held at that temperature;

[0029] S2, Assemble the acoustic emission monitoring equipment, install the acoustic emission sensing probe on the sample fixing device; install the transmitting end sensor on the top of the sample fixing device, and install the receiving end sensor inside the disc base of the sample fixing device.

[0030] S3, place and turn on the DIC observer so that it can record the full-field strain and crack development of the rock sample surface during thermal shock through the optical observation window on the side of the cooling tank, and transmit the image to the data acquisition and processing system;

[0031] S4, Select cooling mode: Immersion cooling mode or spray cooling mode.

[0032] Immersion cooling mode: Before the heating stage of the heating furnace ends, prepare the coolant at the required specific temperature using an ultra-low temperature freezer, pour it into the storage tank on one side of the cooling tank, and open the upper and lower water taps to keep the coolant flowing steadily in the cooling tank.

[0033] Spray cooling mode: Before the heating stage of the heating furnace ends, prepare the coolant at the required specific temperature using an ultra-low temperature freezer, pour it into the storage tank on one side of the cooling tank, turn on the spray switch, and spray the rock sample with the spray nozzle to cool it.

[0034] S5. After the rock sample is heated, quickly use the sample clamp to remove the rock sample from the heating furnace and place it on the sample fixing device.

[0035] S6, Place the sample fixing device and the rock sample fixed on the sample fixing device into the cooling tank, so that the high-temperature rock sample undergoes a thermal shock process in the coolant.

[0036] S7 processes the collected data and quantifies the thermal shock damage to rocks based on the monitoring data.

[0037] The beneficial effects of this invention are:

[0038] This invention provides an experimental device for thermal shock treatment of high-temperature rocks, which can rapidly cool high-temperature rock samples in a constant temperature field using coolants at different temperatures or different cooling media. By setting the same upper and lower water flow rates, the coolant in the cooling tank is kept in a stable flow, thereby maintaining a constant temperature of the coolant inside the tank during the cooling process of the high-temperature rock. Furthermore, optical and acoustic technologies are used to monitor the evolution of internal thermal damage in the rock in real time during the thermal shock process, and to quantitatively characterize the thermal shock damage of the high-temperature rock. This device reduces manual operation during the thermal shock treatment process and reduces the impact of human factors on the thermal shock treatment effect. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the experimental apparatus for high-temperature rock thermal shock treatment according to the present invention.

[0040] Figure 2 This is a schematic diagram of the heating furnace.

[0041] Figure 3 This is a schematic diagram of the structure of an ultra-low temperature freezer.

[0042] Figure 4 This is a structural diagram of the cooling tank and the liquid storage tank at one angle.

[0043] Figure 5 This is a structural diagram of the cooling tank and the liquid storage tank from another angle.

[0044] Figure 6 This is a schematic diagram of the cut-out structure of the cooling tank.

[0045] Figure 7 This is a cross-sectional schematic diagram of the cooling tank.

[0046] Figure 8 This is a schematic diagram of the sample fixing device at one angle.

[0047] Figure 9 This is a schematic diagram of the sample fixing device from another angle.

[0048] Figure 10 This is a structural schematic diagram of a vertical fixture unit.

[0049] Figure 11 This is a schematic diagram of the third angle of the sample fixing device.

[0050] Figure 12 This is a schematic diagram of the sample holder. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0053] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Please see Figures 1 to 12As shown, this invention provides a high-temperature rock thermal shock treatment experimental device 100 that achieves thermal shock treatment of high-temperature rocks through rapid cooling and monitors rock damage during the thermal shock process. The device includes a heating furnace 1 for heating and maintaining the temperature of the rock sample; a storage tank 2 for storing coolant; an ultra-low temperature freezer 3 for cooling the coolant and placing the prepared coolant; a cooling tank 4 connected to the storage tank for loading coolant to rapidly cool the rock sample to achieve thermal shock treatment; a sample fixing device 5, located inside the cooling tank 4, for fixing the rock sample and ensuring it is in contact with an acoustic emission sensing probe; a sample clamp 6 for clamping the high-temperature sample from the heating furnace 1 onto the sample fixing device 5 in the cooling tank 4; an acoustic emission monitoring device 7 for monitoring the acoustic signals of thermal damage to the rock sample during thermal shock; a DIC observer 8 for observing the entire process of surface crack propagation during thermal shock; and an ultrasonic testing device 9 for real-time detection of the longitudinal and transverse wave velocities of the rock sample before and after the thermal shock process.

[0055] Please see Figures 4 to 7 As shown, an upper water tap 21 is provided between the upper end of the cooling tank 4 and the liquid storage tank 2 to control the connection between the two. A lower water tap 22 is provided at the lower end of the cooling tank 4. Both the upper water tap 21 and the lower water tap 22 are equipped with orifice plate flow meters 23. By controlling the opening and closing of the upper water tap 21 and the lower water tap 22, the flow rate of coolant into and out of the cooling tank 4 is controlled. The flow rate of coolant is observed and monitored using the orifice plate flow meter 23, so that the coolant at any position in the cooling tank 4 maintains a constant temperature and a uniform temperature distribution, thereby ensuring that the temperature of coolant in the cooling tank 4 remains constant during the cooling of high-temperature rocks.

[0056] In this way, thermal shock treatment of high-temperature rocks is achieved by rapidly cooling them in a constant temperature field, and real-time monitoring of the evolution of internal thermal damage in the rocks is realized through optical and acoustic technologies, thereby quantifying the thermal shock damage of high-temperature rocks.

[0057] In this embodiment, heating furnace 1 is a box-type heating furnace, such as... Figure 2 As shown. The heating module for rock samples can simultaneously heat 1-9 cylindrical rock samples, with the heating temperature set to 100℃-1000℃ and the holding time set to more than 1 hour. The surface temperature of the rock samples is monitored in real time via thermocouples, and the temperature data is transmitted to the data acquisition and processing system. Figure 3 As shown, the ultra-low temperature freezer 3, as a refrigeration module for coolant, can cool approximately 40L of coolant to a minimum of -100℃ and store it. In the experiment, coolant can be prepared at a specific temperature above -100℃.

[0058] Specifically, the cooling tank 4 includes an inner wall 41, an outer wall 42, an insulation interlayer 43 between the two, and cooling tank support legs 44. The insulation interlayer 43 is filled with insulation material, which can realize thermal shock treatment of high-temperature rock samples using coolants at different temperatures or different cooling media.

[0059] The inner wall 41 of the cooling tank 4 is made of corrosion-resistant stainless steel, which not only keeps the coolant warm but also prevents the coolant from corroding the cooling tank 4. The longitudinal section of the inner wall 41 is rectangular at the top and inverted trapezoidal at the bottom. The inverted trapezoidal shape at the bottom prevents coolant residue and is connected to the drain faucet 22 of the cooling tank 4 via a pipe 45 to drain the coolant. At the junction of the rectangle and the inverted trapezoid, there is a support portion 411 protruding from the inner wall surface into the cooling tank 4. The support portion 411 is used to support the sample fixing device 5. In this embodiment, there are four support portions 411, which are evenly spaced on the inner wall 41. It should be understood that the number of support portions 411 can also be five, six, more, or fewer, and there is no specific limitation, as long as it can support the sample fixing device 5.

[0060] Several spray nozzles 412 are also provided on the inner wall 41 of the cooling tank 4. The spray nozzles 412 are connected to the storage tank 2 through water pipes 46. A spray mode switch 413 is provided on the water pipe. Turning on the spray mode switch 413 can switch the cooling mode from the immersion cooling mode to the spray cooling mode. The coolant in the storage tank 2 is dispersed into a mist by the spray nozzles 412 to cool the high-temperature rock sample.

[0061] Please see Figures 8 to 11 As shown, the sample fixing device 5 includes a disc base 51, four vertical clamping units 52 disposed at the center of the disc base 51, and a handle 53 disposed on the disc base 51. The disc base 51 is a hollow, corrosion-resistant stainless steel disc base, and has threaded holes for fixing the vertical clamping units 52. The diameter of the disc base 51 is slightly smaller than the diameter of the inner wall 41 of the cooling tank 4, and the disc base 51 can be fixed to the support part 411 of the cooling tank 4.

[0062] Each vertical clamp unit 52 includes a perforated vertical column 521 and a fixing clamp 522 arranged parallel to each other, and two waveguide rods 523 inserted into the perforated vertical column 522. The perforated vertical column 521 and the fixing clamp 522 each have three screw holes at corresponding positions (upper, middle, and lower). The waveguide rods 523 are configured with a thicker end connected to a thinner end, and both ends are threaded, with the screw holes matching the size of the thinner end. Specifically, the thinner ends of the two waveguide rods 523 pass sequentially through the holes near the lower end of the perforated vertical column 521 and the fixing clamp 522 before contacting the rock sample. In particular, a spring 524 is fitted onto the waveguide rod 523; one end of the spring 524 abuts against the perforated vertical column 521, and the other end abuts against the fixing clamp 522, for cushioning.

[0063] An acoustic emission sensor probe fixing cap 71 is fitted onto the thicker end of the waveguide 523. The acoustic emission sensor probe fixing cap 71 is a cylindrical shape with one side open, and a spring 73 is provided at the bottom of the cylinder. An acoustic emission sensor probe 72 is installed inside the acoustic emission sensor probe fixing cap 71. The waveguide 523 is connected to the acoustic emission sensor probe 72 after fixing the acoustic emission sensor probe 72 through the acoustic emission sensor probe fixing cap 71, thereby realizing the connection between the waveguide 523 and the acoustic emission sensor probe 72.

[0064] In this embodiment, four vertical clamping units 52 and four handles 53 are provided. The four vertical clamping units 52 are arranged in a cross shape at the center of the disc base 51, and the four handles 53 are evenly spaced on the outer periphery of the disc base 51. In this way, the four vertical clamping units 52 fix the rock sample in four directions, and the handles 53 can be used to put the sample fixing device 5 and the rock sample placed on it into the cooling tank 4.

[0065] Acoustic emission monitoring device 7 is used to monitor the acoustic signals of thermal damage to rock samples during thermal shock. Acoustic emission monitoring device 7 includes an acoustic emission sensing probe 72 connected to a waveguide rod 523, a signal repeater, an acoustic emission data receiver (host computer, such as a computer), and data transmission lines. The acoustic emission sensing probe 72 is used to receive the acoustic signals emitted by the rock sample during thermal shock in real time. The signal repeater is used to decode the received acoustic signals, convert the acoustic signals into electrical signals, and transmit the signal data. The acoustic emission data receiver uses specialized software to receive and analyze the data.

[0066] An optical observation window 421 is provided on one side of the cooling tank 4. The DIC observer 8 is positioned directly opposite the optical observation window 421, observing the entire process of crack propagation on the rock sample surface through a high-precision lens. The DIC observer 8 includes an image acquisition system, an image storage system, and an image processing and calculation system. The image acquisition system includes a laser positioner, two high-precision lenses, two CMOS high-speed industrial cameras, and a polarized illumination source, all mounted on a fixed bracket. The DIC observer 8 is an existing structure and will not be described in detail here. The professional graphics workstation is the image storage system and image calculation and analysis system, equipped with analysis software. This software triggers the acquisition system to automatically acquire images, store them on the hard drive, and finally perform image processing and calculation. The DIC observer 8 is used to monitor the displacement field and crack development process on the rock sample surface. It is connected to the data acquisition and processing system via control lines and works in conjunction with the DIC testing software.

[0067] An ultrasonic testing device 9 is used to detect the longitudinal and transverse wave velocities of a rock sample before and after a thermal shock process in real time. The ultrasonic testing device 9 includes a transmitting sensor 91 (i.e., an ultrasonic probe) mounted on the top of the sample fixing device 5, an ultrasonic probe moving rod 92, a receiving sensor 93 mounted on the base of the sample fixing device 5, and a bottom ultrasonic probe fixing assembly 94 for housing the receiving sensor 93. The ultrasonic probe moving rod 92 includes a vertical rod 921 vertically mounted on a disc base 51 and a horizontal rod 922 connected to the vertical rod 921. The transmitting sensor 91 is mounted on the free end of the horizontal rod 922. The ultrasonic probe moving rod 92 can rotate freely about the vertical rod 921 as its central axis. When ultrasonic testing of the rock sample is required, the ultrasonic probe moving rod 92 rotates to rotate the receiving sensor 93 to the top of the rock sample. The bottom ultrasonic probe fixing assembly 94 is fixedly mounted at the bottom center of the disc base 51.

[0068] The bottom surface of the liquid storage tank 2 is at a higher level than the top surface of the main body of the cooling tank 4.

[0069] Please see Figure 12 As shown, the sample clamp 6 includes a receiving part 61 for accommodating a high-temperature rock sample after heating and a clamping part 62 for controlling the opening and closing of the receiving part 61. The receiving part 61 has an insulating layer, and the sample clamp 6 can wrap around the rock sample when clamping, thereby reducing the temperature loss of the rock sample during the transfer process.

[0070] The present invention also provides an experimental method for a high-temperature rock thermal shock treatment experimental apparatus, comprising the following steps:

[0071] S1. Use a heating furnace to heat the rock sample to the target temperature and hold it at that temperature. In order to ensure that the rock sample is heated evenly inside and out, the target temperature is usually maintained in the heating furnace for 2 hours or longer after heating to the target temperature.

[0072] S2, Assemble the acoustic emission monitoring equipment by installing an acoustic emission sensing probe, a transmitting sensor 91, and a receiving sensor 93 at specific positions on the sample fixing device. Specifically, an acoustic emission sensing probe 72 is installed at the thick end of the waveguide rod 523 on the sample fixing device 5. An appropriate amount of Vaseline is applied to the outer end face of the thick end of the waveguide rod 523 and the surface of the acoustic emission sensing probe 72, and it is fixed using an acoustic emission sensing probe fixing cap 71. The transmitting sensor 91 is assembled on the ultrasonic probe moving rod 92 at the top of the sample, and the receiving sensor 93 is assembled at the bottom ultrasonic probe fixing assembly 94 at the bottom of the sample fixing device 5. Those skilled in the art should understand that the transmitting sensor 91 and the receiving sensor 93 can also be referred to as ultrasonic probes.

[0073] S3, place and turn on the DIC observer so that it can record the full-field strain and crack development of the rock sample surface during thermal shock through the optical observation window on the side of the cooling tank, and transmit the image to the data acquisition and processing system;

[0074] S4, Select cooling mode: Immersion cooling mode or spray cooling mode.

[0075] Immersion Cooling Mode: Before the heating stage of the furnace ends, prepare the required coolant at a specific temperature using an ultra-low temperature freezer, pour it into the storage tank on one side of the cooling tank, and open the upper and lower water taps to maintain a stable flow of coolant in the cooling tank. Specifically, before the heating stage ends, prepare the required coolant according to a specific ratio and refrigerate it in an industrial refrigerator to the specified temperature. After the coolant reaches the specified temperature, remove it and pour it into an external storage tank connected to the cooling tank. Open the upper water tap to allow the coolant to flow into the cooling tank. Once the coolant reaches the preset liquid level in the cooling tank, open the lower water tap. Set the orifice plate flow meters for the upper and lower water taps to ensure that the inflow and outflow rates of the coolant are consistent, thus ensuring a stable temperature of the coolant in the cooling tank. To prevent coolant loss and a gradual decrease in flow rate, while ensuring the coolant flow, pour oil of the same height as the lost coolant into the external storage tank. Observe through the scale indicator window until all the coolant in the storage tank has been drained. Throughout the entire process, the liquid level in the storage tank must remain constant.

[0076] Spray cooling mode: Before the heating stage of the furnace ends, prepare the required coolant at the specified temperature using an ultra-low temperature freezer, pour it into the storage tank on one side of the cooling tank, turn on the spray switch, and spray the rock sample through the spray nozzle for cooling. Specifically, before the heating stage ends, prepare the required coolant according to a specific ratio and place it in the ultra-low temperature freezer to cool it to the specified temperature. After the coolant reaches the specified temperature, remove it and pour it into an external storage tank connected to the cooling tank. Turn on the spray mode switch to spray the rock sample located in the center of the cooling tank.

[0077] S5. After the rock sample is heated, quickly use the sample clamp to clamp the rock sample from the heating furnace and place it on the sample fixing device. The rock sample is fixed by the four vertical clamp units 52 of the sample fixing device. Rotate the ultrasonic probe moving rod 92 at the top of the sample to the top of the sample.

[0078] S6, the sample fixing device and the rock sample fixed on the sample fixing device are placed into the cooling tank and fixed by the support on the inner wall of the cooling tank, so that the high temperature rock sample undergoes thermal shock in the coolant.

[0079] S7 collects data from various monitoring devices during the thermal shock process, processes the collected data, and quantitatively characterizes the thermal shock damage to rocks based on the monitoring data.

[0080] In summary, this invention provides an experimental device for thermal shock treatment of high-temperature rocks, which can rapidly cool high-temperature rock samples in a constant temperature field using coolants at different temperatures or different cooling media. Furthermore, it utilizes optical and acoustic technologies to achieve real-time monitoring of the evolution of internal thermal damage in the rock during the thermal shock process, enabling quantitative characterization of the thermal shock damage in high-temperature rocks. This device reduces manual operation during the thermal shock treatment process and minimizes the impact of human factors on the treatment effect.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-temperature rock thermal shock treatment experimental apparatus, characterized in that: It includes a heating furnace for heating and maintaining the temperature of rock samples; a storage tank for storing coolant; and an ultra-low temperature freezer for cooling the coolant and storing the prepared coolant. A cooling tank, connected to the storage tank, is used to load coolant to rapidly cool the rock sample to achieve thermal shock treatment. The cooling tank includes an inner wall, an outer wall, and an insulation interlayer between the inner and outer walls, the insulation interlayer containing insulation material. The inner wall of the cooling tank is made of corrosion-resistant stainless steel, and its longitudinal section is rectangular at the top and inverted trapezoidal at the bottom. A support portion protruding from the inner wall surface and extending into the cooling tank is provided at the junction of the rectangle and the inverted trapezoid, the support portion being used to support the sample fixing device. A sample fixing device, disposed within the cooling tank, is used to fix the rock sample and bring it into contact with the acoustic emission sensing probe. The sample fixing device includes a disc base and four vertical clamp units disposed at the center of the disc base. Each vertical clamp unit includes a perforated column and a fixing clip arranged parallel to each other, and two waveguide rods inserted into the perforated column. One end of each waveguide rod passes through a hole in the fixing clip and contacts the rock sample, while the other end is fitted with an acoustic emission sensing probe fixing cap, and an acoustic emission sensing probe is disposed inside the acoustic emission sensing probe fixing cap. A sample clamp is used to clamp a high-temperature sample from the heating furnace onto the sample fixing device in the cooling tank; Acoustic emission monitoring equipment is used to monitor the acoustic signals of thermal damage to rock samples during thermal shock. The DIC observation instrument is used to observe the entire process of surface crack propagation during thermal shock of rock samples. Ultrasonic testing equipment is used to detect the longitudinal and transverse wave velocities of rock samples in real time before and after thermal shock. A water inlet tap is provided between the upper end of the cooling tank and the liquid storage tank to control the connection between the two. A water outlet tap is provided at the lower end of the cooling tank. Both the water inlet tap and the water outlet tap are equipped with orifice plate flow meters. By controlling the water flow rate of the water inlet tap and the water outlet tap, the coolant in the cooling tank is kept to flow stably, thereby keeping the temperature of the coolant in the tank constant during the cooling of high-temperature rocks. The perforated vertical column and the fixing clip are respectively provided with three holes for the waveguide rod to pass through. A spring is sleeved on the waveguide rod, one end of the spring abuts against the perforated vertical column and the other end abuts against the fixing clip. The ultrasonic testing device includes a transmitting sensor disposed on the top of the sample fixing device and a receiving sensor disposed on the disc base of the sample fixing device. The bottom surface of the liquid storage tank is at a higher level than the top surface of the main body of the cooling tank.

2. The high-temperature rock thermal shock treatment experimental apparatus according to claim 1, characterized in that: An optical observation window is provided on one side of the cooling tank, and the DIC observer is positioned directly opposite the optical observation window to observe the entire process of crack propagation on the surface of the rock sample through a high-precision lens.

3. The high-temperature rock thermal shock treatment experimental apparatus according to claim 2, characterized in that: The inner wall of the cooling tank is also equipped with a spray nozzle connected to the liquid storage tank.

4. The high-temperature rock thermal shock treatment experimental apparatus according to claim 3, characterized in that: The acoustic emission monitoring device includes an acoustic emission sensor probe, a signal repeater, an acoustic emission data receiver, and a data transmission pipeline. The acoustic emission sensor probe is used to receive acoustic signals emitted by the rock sample during thermal shock in real time. The signal repeater is used to decode the received acoustic signals, convert the acoustic signals into electrical signals, and transmit the signal data. The acoustic emission data receiver is used to receive data and analyze and process it.

5. An experimental method using the high-temperature rock thermal shock treatment experimental apparatus as described in claim 4, characterized in that, Includes the following steps: S1, The rock sample is heated to the target temperature using a heating furnace and held at that temperature; S2, Assemble the acoustic emission monitoring equipment, install the acoustic emission sensing probe on the sample fixing device; install the transmitting end sensor on the top of the sample fixing device, and install the receiving end sensor on the disc base of the sample fixing device. S3, place and turn on the DIC observer so that it can record the full-field strain and crack development of the rock sample surface during thermal shock through the optical observation window on the side of the cooling tank, and transmit the image to the data acquisition and processing system; S4, Select cooling mode: Immersion cooling mode or spray cooling mode. Immersion cooling mode: Before the heating stage of the heating furnace ends, use an ultra-low temperature freezer to prepare the coolant at the required specific temperature, pour it into the storage tank on one side of the cooling tank, and open the upper and lower water taps to keep the coolant flowing steadily in the cooling tank. Spray cooling mode: Before the heating stage of the heating furnace ends, prepare the coolant at the required specific temperature using an ultra-low temperature freezer, pour it into the storage tank on one side of the cooling tank, turn on the spray switch, and spray the rock sample with the spray nozzle to cool it. S5. After the rock sample is heated, quickly use the sample clamp to remove the rock sample from the heating furnace and place it on the sample fixing device. S6, Place the sample fixing device and the rock sample fixed on the sample fixing device into the cooling tank, so that the high-temperature rock sample undergoes a thermal shock process in the coolant. S7 processes the collected data and quantifies the thermal shock damage to rocks based on the monitoring data.

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