A multi-functional mechanical experiment device with multiple heating methods and its usage method

Abstract

The present invention discloses a multi-functional mechanical experiment device with multiple heating methods and its usage method, belonging to the technical field of geotechnical engineering. The experimental device includes a kettle body for placing specimens, an annular constant temperature heat insulation box for heating the specimens, a distributed optical fiber temperature sensor for monitoring the temperature inside the kettle body or the specimens, a lateral displacement measuring device for detecting the lateral displacement of the specimens, a porous tube and a rubber sleeve for placing the specimens during permeability testing. The experimental device of the present invention can be used to realize mechanical experiments under convective heating, conductive heating or supercritical fluid heating, and is convenient for exploring the uniaxial mechanical properties and real-time high-temperature permeability of different geotechnical specimens, and can observe the experimental situation in real time, overcoming the problems of the existing devices with single use, inability to realize solid mechanics experiments under multiple heating conditions, measurement of the lateral displacement of specimens and real-time high-temperature seepage testing.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering, and particularly relates to the mechanical experiments of geotechnical specimens. Specifically, it is a multi-functional mechanical experiment device with multiple heating methods and its use method. Background Technique

[0002] With the continuous growth of energy demand, especially in the process of oil and gas exploration and production, the influence of temperature and pressure changes in the formation on the structure of rocks or soils has become particularly important. In a high-temperature and high-pressure environment, the mechanical properties of formation rocks will change significantly. For example, as the temperature rises, the solid skeleton of the rock will expand, and the increase in external stress may cause it to contract, making the mechanical behavior of rocks or soils more complex. Therefore, studying and testing the mechanical properties of rocks or soils under high-temperature conditions, especially uniaxial mechanical properties, has important engineering significance.

[0003] It has become particularly urgent to study the feasibility of CO2 deep geological storage technology. In order to evaluate the geological storage effect of CO2 in a high-temperature and high-pressure environment, it is necessary to deeply study the seepage mechanics and solid mechanics properties of rocks under such extreme conditions. Therefore, conducting mechanical experiments on rocks and soils under high-temperature and high-pressure conditions, especially the measurement of key mechanical parameters such as permeability and Poisson's ratio, has important theoretical value and broad application prospects.

[0004] However, the current experimental equipment generally has the limitation of being unable to perform real-time high-temperature mechanical tests under multiple heating methods. Most existing equipment only supports a single heating method (such as electric heating or convective heating) and cannot perform multi-parameter measurements under high-temperature and high-pressure environments. In addition, the existing experimental devices have relatively single functions and cannot fully meet the multiple requirements of permeability testing, mechanical testing, and displacement measurement. Especially in uniaxial mechanical experiments, the measurement of lateral displacement is often ignored, but it plays a key role in the study of material strain and deformation behavior. Accurately measuring the lateral displacement is crucial for understanding the lateral deformation, Poisson's ratio, and other mechanical properties of rocks or soils. Only through precise measurement and analysis of the lateral displacement can the comprehensive mechanical behavior of the material during the loading process be fully revealed, thus providing a more reliable theoretical basis for the design, application, and engineering practice of the material.

[0005] In summary, the existing experimental equipment has relatively single uses and all have the disadvantages of being unable to conduct solid mechanics experiments under multiple heating conditions or real-time high-temperature seepage, that is, it cannot achieve real-time testing of rock permeability and uniaxial mechanical properties under convective heating, conductive heating, or supercritical fluid heating, and the existing experimental equipment cannot measure the lateral displacement of the specimen during the high-temperature and high-pressure uniaxial mechanical test. Therefore, developing a multi-functional mechanical experimental device that can support multiple heating methods has important technical innovation significance and extensive practical application value. Such a device can not only conduct real-time high-temperature mechanical experiments under different heating methods, but also synchronously measure the lateral displacement, permeability, and other key mechanical parameters during the experiment, providing more accurate experimental data support for fields such as geotechnical engineering and geological storage technology. Summary of the Invention

[0006] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art, and provide a multi-functional mechanical experimental device with multiple heating methods, thereby solving the problems of single use of the existing device, inability to conduct solid mechanics experiments under multiple heating conditions, measurement of the lateral displacement of the specimen, and real-time high-temperature seepage test.

[0007] The present invention is achieved through the following technical solutions:

[0008] A multi-functional mechanical experimental device with multiple heating methods includes a kettle body, an annular constant-temperature heat-insulating box, a distributed optical fiber temperature sensor, and a lateral displacement measuring device.

[0009] A test cavity is arranged inside the kettle body, a top cover is installed on the top of the kettle body, and an annular pressure head is inserted at the central position of the top cover. The bottom end of the annular pressure head extends into the test cavity; a shaft pressure head is inserted into the annular pressure head, the bottom end of the shaft pressure head extends into the test cavity, the top end of the shaft pressure head extends out of the top end of the annular pressure head, and a permeating fluid outlet hole communicating with the test cavity is arranged on the shaft pressure head. One end orifice of the permeating fluid outlet hole is opened on the bottom surface of the shaft pressure head, and the other end orifice of the permeating fluid outlet hole is opened on the upper side wall of the shaft pressure head; a base is installed at the bottom of the kettle body, and a sample table extending upward is fixed at the central position of the top of the base. The sample table extends into the test cavity; a permeating fluid inlet hole communicating with the test cavity is arranged on the base. One end orifice of the permeating fluid inlet hole is opened on the lower side wall of the base, and the other end orifice of the permeating fluid inlet hole is opened on the top surface of the sample table; a heat-carrying fluid injection hole communicating with the test cavity is arranged on the base. One end orifice of the heat-carrying fluid injection hole is opened on the lower side wall of the base, and the other end orifice of the heat-carrying fluid injection hole is opened on the top surface of the base; an annular through hole for circulating water cooling is arranged at the bottom of the base.

[0010] The annular constant-temperature heat insulation box is sleeved outside the kettle body, and heating electric wires for heating are arranged inside the annular constant-temperature heat insulation box; four lateral displacement measurement holes penetrating through the annular constant-temperature heat insulation box and the kettle body and communicating with the test cavity are uniformly distributed on four sides of the annular constant-temperature heat insulation box and the kettle body as a whole, and the lateral displacement measurement holes are used for installing lateral displacement measurement devices; one multifunctional hole penetrating through the annular constant-temperature heat insulation box and the kettle body and communicating with the test cavity is arranged on one side of the annular constant-temperature heat insulation box and the kettle body as a whole, and is used for temperature and pressure detection and discharging of the heat-carrying fluid.

[0011] The distributed optical fiber temperature sensor is arranged on the sample stage, and the output end of the distributed optical fiber temperature sensor extends out of the annular constant-temperature heat insulation box and the kettle body as a whole through the multifunctional hole.

[0012] Four lateral displacement measurement devices are provided, and the four lateral displacement measurement devices are respectively and hermetically installed in the four lateral displacement measurement holes; the lateral displacement measurement device includes a probe, a hollow tube, a condensing tube and a high-pressure-resistant high-precision displacement measuring instrument. The high-pressure-resistant high-precision displacement measuring instrument is fixed at one end of the hollow tube. The probe is located inside the hollow tube and is coaxially arranged with the hollow tube. The end of the probe is connected to the high-pressure-resistant high-precision displacement measuring instrument. The front end of the probe extends out of the hollow tube and extends into the test cavity, and the condensing tube is wound around the outer wall of the hollow tube.

[0013] As a preferred technical solution, flange plates are arranged on the periphery of the top cover, the top and bottom peripheries of the kettle body, and the top periphery of the base. The top cover and the top of the kettle body are fixedly connected through the flange plates and bolts, and the base and the bottom of the kettle body are fixedly connected through the flange plates and bolts.

[0014] As a preferred technical solution, a gap sealing ring is arranged between the kettle body and the top cover, and the gap sealing ring is simultaneously sleeved outside the annular pressing head in a sealing manner. A gap sealing ring is arranged between the kettle body and the base, and a gap sealing ring is arranged between the annular pressing head and the axial pressing head.

[0015] As a preferred technical solution, a reflective material layer is arranged on the inner wall of the annular constant-temperature heat insulation box, and a high-efficiency heat insulation material layer is arranged on the outer wall of the annular constant-temperature heat insulation box.

[0016] As a preferred technical solution, connecting threads are arranged on the outer wall of one end of the hollow tube far away from the high-pressure-resistant high-precision displacement measuring instrument. The hollow tube is inserted into the lateral displacement measurement hole and is threadedly connected with the lateral displacement measurement hole through the connecting threads.

[0017] Furthermore, the present invention also provides a usage method of the above experimental device when performing a uniaxial mechanical experiment under various heating methods, which is specifically as follows:

[0018] 1) When performing a uniaxial mechanical experiment by adopting a convective heating method, it includes:

[0019] S1. Place the test piece on the sample stage, wrap the distributed fiber optic temperature sensor around the test piece in a ring shape without contacting the test piece; adjust the four lateral displacement measuring devices so that the front ends of the four probes pass through the distributed fiber optic temperature sensor and all contact the test piece; seal the permeating fluid outlet hole and the permeating fluid inlet hole with plugs.

[0020] S2. Inject the heat-carrying fluid at a specified temperature into the test cavity inside the autoclave through the heat-carrying fluid injection hole. After the heat-carrying fluid is discharged through the multi-functional hole, convective heating of the test piece is achieved.

[0021] S3. Observe the temperature detected by the distributed fiber optic temperature sensor. After the detected temperature reaches the specified temperature, perform heat preservation treatment, and then apply pressure to the test piece through the axial pressure head to conduct a uniaxial mechanical experiment at high temperature in real time. At the same time, detect the lateral displacement of the test piece through the lateral displacement measuring device.

[0022] 2) When performing a uniaxial mechanical experiment using the conduction heating method, it includes:

[0023] S1. Place the test piece on the sample stage, wrap the distributed fiber optic temperature sensor around the test piece in a ring shape without contacting the test piece; adjust the four lateral displacement measuring devices so that the front ends of the four probes pass through the distributed fiber optic temperature sensor and all contact the test piece; seal the permeating fluid outlet hole, the permeating fluid inlet hole and the multi-functional hole with plugs.

[0024] S2. Inject a protective gas into the test cavity inside the autoclave through the heat-carrying fluid injection hole. After the protective gas is injected, seal the heat-carrying fluid injection hole with a plug.

[0025] S3. Turn on the annular constant temperature heat insulation box to heat the test piece inside the autoclave.

[0026] S4. Observe the temperature detected by the distributed fiber optic temperature sensor. After the detected temperature reaches the specified temperature, perform heat preservation treatment, and then apply pressure to the test piece through the axial pressure head to conduct a uniaxial mechanical experiment at high temperature in real time. At the same time, detect the lateral displacement of the test piece through the lateral displacement measuring device.

[0027] 3) When performing a uniaxial mechanical experiment using the supercritical fluid heating method, it includes:

[0028] S1. Place the test piece on the sample stage, wrap the distributed fiber optic temperature sensor around the test piece in a ring shape without contacting the test piece; adjust the four lateral displacement measuring devices so that the front ends of the four probes pass through the distributed fiber optic temperature sensor and all contact the test piece; seal the permeating fluid outlet hole and the permeating fluid inlet hole with plugs.

[0029] S2. Inject supercritical fluid into the test cavity inside the autoclave through the heat-carrying fluid injection hole, and achieve convective heating of the specimen by controlling the temperature and pressure of the supercritical fluid.

[0030] S3. Observe the temperature detected by the distributed optical fiber temperature sensor. After the detected temperature reaches the specified temperature, perform heat preservation treatment, and then apply pressure to the specimen through the axial indenter to conduct a uniaxial mechanical experiment at high temperature in real time. At the same time, detect the lateral displacement of the specimen through the lateral displacement measuring device.

[0031] As a preferred technical solution, when performing a uniaxial mechanical experiment using the conduction heating method, nitrogen is used as the protective gas; when performing a uniaxial mechanical experiment using the supercritical fluid heating method, supercritical water or carbon dioxide is used as the supercritical fluid.

[0032] Furthermore, the multi-functional mechanical experiment device with multiple heating methods of the present invention can also perform real-time high-temperature permeability testing. When performing real-time high-temperature permeability testing, the experimental device further includes a porous tube, a rubber sleeve, and a back pressure valve. A number of holes are uniformly and penetratingly opened on the wall of the porous tube; the rubber sleeve is inserted into the porous tube, and the outer wall of the rubber sleeve is in close contact with the inner wall of the porous tube; at the top and bottom sleeve openings of the rubber sleeve, outward-turning washers are provided, and the outward-turning washers are in close contact with the top and bottom surfaces of the porous tube, and the outer diameter of the outward-turning washers is the same as the outer diameter of the porous tube.

[0033] The usage method of the above experimental device when performing real-time high-temperature permeability testing includes:

[0034] S1. Remove the four lateral displacement measuring devices, seal and install a back pressure valve on one of the lateral displacement measuring holes, and block the remaining three lateral displacement measuring holes and the multi-functional hole with plugs.

[0035] S2. Place the specimen in the rubber sleeve, place the combination of the specimen, rubber sleeve, and porous tube on the sample stage, connect the distributed optical fiber temperature sensor to the outer wall of the porous tube, apply axial pressure to the specimen through the axial indenter, and use the annular indenter to press the outward-turning washer of the rubber sleeve to achieve the sealing of the specimen by the rubber sleeve.

[0036] S3. Inject high-temperature heat-conducting oil with a specified pressure into the test cavity inside the autoclave through the heat-carrying fluid injection hole to apply confining pressure.

[0037] S4. Turn on the annular constant-temperature heat-insulating box to heat the specimen in the autoclave, and at the same time observe the temperature detected by the distributed optical fiber temperature sensor. After the detected temperature reaches the specified temperature, perform heat preservation treatment.

[0038] S5. Inject seepage fluid through the seepage fluid inlet hole and discharge the seepage fluid through the seepage fluid outlet hole, so as to test the permeability of the specimen.

[0039] Compared with existing traditional experimental equipment, the device of the present invention includes a complex heating system and a medium injection system, focusing on mechanical experiments under high-temperature environments; it can conduct high-temperature permeability and mechanical tests under various heating conditions, with strong versatility and flexibility; it can support high-temperature seepage or solid mechanics experiments under various heating conditions, such as supporting convective heating, conductive heating, and supercritical fluid heating; it mainly relates to fields such as geotechnical engineering and CO2 geological sequestration, focusing on the mechanical behavior and permeability characteristics of materials (such as soil, rock, etc.) under extreme temperatures and pressures, especially tests under supercritical fluid heating or high-temperature environments. The specific test contents include: uniaxial mechanical properties (i.e., mechanical properties such as compression, tension, and bending), high-temperature permeability test, and lateral displacement of the sample; the main technical advantage lies in its ability to conduct mechanical and permeability tests under extreme environments (such as supercritical fluids, high temperature and high pressure, etc.), and it solves the problem of the single use of traditional devices, paying more attention to multi-dimensional tests (including mechanical and permeability characteristics) under extreme environments (high temperature, high pressure, supercritical fluids, etc.).

[0040] In summary, the experimental device of the present invention is scientifically designed, ingeniously structured, and rich in functions. It can be used to conduct mechanical experiments under convective heating, conductive heating, or supercritical fluid heating, while facilitating the exploration of the uniaxial mechanical properties and real-time high-temperature permeability of different geotechnical specimens, and can observe the experimental situation in real time, overcoming the problems of the single use of existing devices, the inability to conduct solid mechanics experiments under various heating conditions, the measurement of lateral displacement of specimens, and real-time high-temperature seepage tests. At the same time, the experimental device of the present invention is safe, reliable, easy to operate, and convenient to repair, can adapt to specimens of various different sizes, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings here are used to provide further illustration of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0042] Figure 1 It is a schematic structural diagram of the device of the present invention.

[0043] Figure 2 It is a schematic structural diagram of the distributed optical fiber temperature sensor arranged in the autoclave body of the device of the present invention.

[0044] Figure 3 It is a schematic structural diagram of the porous tube of the device of the present invention.

[0045] Figure 4 It is a schematic structural diagram of the rubber sleeve of the device of the present invention.

[0046] Figure 5This is a schematic diagram of the external structure of the lateral displacement measurement device in the device of the present invention.

[0047] Figure 6 This is a schematic sectional view of the lateral displacement measurement device in the device of the present invention.

[0048] In the figure: 1 - autoclave body, 2 - annular constant - temperature heat - insulating box, 3 - distributed optical fiber temperature sensor, 4 - test cavity, 5 - top cover, 6 - annular pressure head, 7 - axial pressure head, 8 - permeating fluid outlet hole, 9 - base, 10 - sample stage, 11 - permeating fluid inlet hole, 12 - heat - carrying fluid injection hole, 13 - lateral displacement measurement hole, 14 - multi - functional hole, 15 - probe, 16 - hollow tube, 17 - condenser tube, 18 - high - pressure - resistant and high - precision displacement measuring instrument, 19 - annular through - hole, 20 - flange plate, 21 - gap sealing ring, 22 - porous tube, 23 - rubber sleeve, 24 - turned - out washer, 25 - connecting thread. Detailed implementation mode

[0049] In order to enable those skilled in the art to better understand the present invention, the present invention will be further clearly and completely described below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, without conflict, the implementation manners and features in the embodiments of the present application can be combined with each other. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] In the description of this embodiment, it should be understood that the orientation or positional relationships indicated by terms such as "inner", "outer", "periphery", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing this embodiment and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. Embodiment 1

[0051] As Figures 1 to 6 shown, this embodiment provides an experimental device for uniaxial mechanics with multiple heating methods and real - time high - temperature permeability testing. The experimental device includes an autoclave body 1 for placing the specimen, an annular constant - temperature heat - insulating box 2 for heating the specimen, a distributed optical fiber temperature sensor 3 for monitoring the temperature inside the autoclave body 1 or the specimen, a lateral displacement measurement device for detecting the lateral displacement of the specimen, a porous tube 22 and a rubber sleeve 23 for placing the specimen during permeability testing.

[0052] A test cavity 4 is arranged inside the kettle body 1. A top cover 5 is installed at the top of the kettle body 1, and a base 9 is installed at the bottom. The kettle body 1 is fixedly connected to the top cover 5 and the base 9 through flange plates 20 and bolts. Specifically: flange plates 20 are provided at the periphery of the top cover 5, the top periphery and the bottom periphery of the kettle body 1, and the top periphery of the base 9. The top cover 5 is fixedly connected to the top of the kettle body 1 through flange plates 20 and bolts, and the base 9 is fixedly connected to the bottom of the kettle body 1 through flange plates 20 and bolts. The connection and fixation method of the flange plates 20 can provide a good sealing effect for the experiment, reduce the risk of medium leakage, and ensure the safety and reliability of the device during operation. Gap sealing rings 21 are provided between the kettle body 1 and the top cover 5 and the base 9 respectively. Specifically: a downwardly extending circular boss is provided at the center of the bottom surface of the top cover 5, a stepped through hole communicating with its test cavity 4 is provided at the center of the top surface of the kettle body 1, the circular boss of the top cover 5 is adaptively inserted into the stepped groove of the stepped through hole on the top surface of the kettle body 1, and a gap sealing ring 21 is provided between the two; a downwardly concave circular groove is provided at the center of the top surface of the base 9, a downwardly extending circular boss is provided at the center of the bottom surface of the kettle body 1, the circular boss on the bottom surface of the kettle body 1 is adaptively inserted into the circular groove on the top surface of the base 9, and a gap sealing ring 21 is provided between the two. The setting of the gap sealing ring 21 can effectively prevent gas or liquid leakage and improve the sealing performance and safety of the device.

[0053] An annular indenter 6 is inserted at the central position of the top cover 5, and the bottom end of the annular indenter 6 extends into the test cavity 4. Specifically: the annular indenter 6 is slidably inserted into the circular boss of the top cover 5 and the stepped through hole of the autoclave body 1; a shaft indenter 7 is inserted into the annular indenter 6, the bottom end of the shaft indenter 7 extends into the test cavity 4, and the top end of the shaft indenter 7 extends out of the top end of the annular indenter 6. A gap seal ring 21 is arranged between the annular indenter 6 and the shaft indenter 7. The setting of the gap seal ring 21 can effectively ensure the sealing of the seepage fluid when pressure is applied, avoid external interference or leakage, and further improve the accuracy of the permeability test; a seepage fluid outlet hole 8 communicating with the test cavity 4 is arranged on the shaft indenter 7. One end orifice of the seepage fluid outlet hole 8 is opened on the bottom surface of the shaft indenter 7, and the other end orifice of the seepage fluid outlet hole 8 is opened on the upper side wall of the shaft indenter 7; the function of the seepage fluid outlet hole 8 is to serve as a discharge path for the seepage fluid during the real-time high-temperature permeability test, connect with an external seepage fluid collector, and the flow direction of the seepage fluid inside it is from bottom to top; the annular indenter 6 and the shaft indenter 7 form a pressure loading system. The shaft indenter 7 therein can accurately apply axial pressure to the specimen to ensure controlled pressure conditions for the specimen during heating and experiments. For example, the shaft indenter 7 can apply an axial pressure of 300 MPa; the annular indenter 6 has two functions: the first function is that the annular indenter 6 plays an accurate guiding role for the shaft indenter 7 during the test, ensuring its stability and reliability under high-temperature and high-pressure conditions and improving the experimental accuracy; the second function is that during the real-time high-temperature permeability test, the annular indenter 6 can effectively compress the porous tube 22 and the rubber sleeve 23 to form a sealing structure, preventing the confining pressure transfer medium from leaking into the specimen during the high-temperature permeability test, ensuring the accuracy of the experimental data. The annular indenter 6 can keep the rubber sleeve 23 in good sealing under high-temperature and high-pressure conditions and ensure that the heat-carrying fluid can fully contact the specimen during the test. The annular indenter 6 and the shaft indenter 7 are driven by an external pressure application device, such as a hydraulic drive system; the lengths of the annular indenter 6 and the shaft indenter 7 can be adjusted according to actual needs to meet specimens of different sizes, with wider versatility. The common size of the specimen is a diameter of 50 mm and a length of 50 - 180 mm.

[0054] At the center of the top of the base 9, there is a sample stage 10 which extends upward and is used to place the test piece. The sample stage 10 extends into the test cavity 4. The sample stage 10 provides a stable platform for placing the test piece, ensuring that the test piece will not be disturbed externally during the experiment. On the base 9, there is a permeating fluid inlet hole 11 which communicates with the test cavity 4. One end orifice of the permeating fluid inlet hole 11 is opened on the lower side wall of the base 9, and the other end orifice of the permeating fluid inlet hole 11 is opened on the top surface of the sample stage 10. The function of the permeating fluid inlet hole 11 is to connect with the external seepage fluid injection system during the real-time high-temperature seepage experiment and inject the seepage fluid required for the experiment. On the base 9, there is a heat-carrying fluid injection hole 12 which communicates with the test cavity 4. One end orifice of the heat-carrying fluid injection hole 12 is opened on the lower side wall of the base 9, and the other end orifice of the heat-carrying fluid injection hole 12 is opened on the top surface of the base 9. The function of the heat-carrying fluid injection hole 12 is to act as an injection pipe for the injection medium (such as supercritical water, superheated steam, high-temperature heat-conducting oil, etc.). During the experiment, it is connected to the external medium injection system. At the bottom of the base 9, there is an annular through-hole 19 for circulating water cooling. Cooling is achieved through the flow of circulating water in the annular through-hole 19 to realize precise temperature control and improve the stability of the device during the high-temperature experiment, avoiding equipment damage or experimental errors caused by excessive temperature.

[0055] The annular constant-temperature heat-insulating box 2 is sleeved outside the kettle body 1. Inside the annular constant-temperature heat-insulating box 2, there are heating wires for heating. The annular constant-temperature heat-insulating box 2 adopts an annular structure wrapped outside the kettle body 1, which can achieve uniform heating of 360 degrees. Its heating range is 25 - 550 °C. The heating wires inside it are wrapped in the heat-insulating box to reduce the risk of direct contact with high-temperature components. In order to improve the heating efficiency of the annular constant-temperature heat-insulating box 2, a reflective material layer, such as an aluminum foil layer, can be set on the inner wall of the annular constant-temperature heat-insulating box 2 to reduce heat dissipation and further increase the utilization rate of heat. An efficient heat-insulating material layer can also be set on the outer wall of the annular constant-temperature heat-insulating box 2 to reduce heat loss, improve the utilization efficiency of thermal energy, and further enhance the energy efficiency ratio of the heating system.

[0056] On the four sides of the annular constant-temperature heat-insulating box 2 and the kettle body 1 as a whole, four lateral displacement measurement holes 13 which penetrate through the annular constant-temperature heat-insulating box 2 and the kettle body 1 and communicate with the test cavity 4 are evenly distributed. The four lateral displacement measurement holes 13 are used to install lateral displacement measurement devices. Through the lateral displacement measurement holes 13, the lateral displacement measurement devices extend into the interior of the kettle body 1 and are in direct contact with the test piece to monitor and measure the lateral displacement of the test piece during the experiment in real time, providing accurate displacement data and improving the accuracy and reliability of the experiment. In addition, during the real-time high-temperature seepage experiment, a back-pressure valve can be installed in any one of the lateral displacement measurement holes 13 to precisely control the pressure in the experimental system.

[0057] On one side of the overall annular constant-temperature heat-insulating box 2 and the kettle body 1, there is a multi-functional hole 14 that penetrates through the annular constant-temperature heat-insulating box 2 and the kettle body 1 and communicates with the test cavity 4. The multi-functional hole 14 is used for temperature and pressure detection and the discharge of the heat-carrying fluid. On the one hand, the multi-functional hole 14 is used for the output end of the distributed optical fiber temperature sensor 3 to pass through and connect with the real-time temperature and pressure detection system. On the other hand, it serves as the discharge port of the heat-carrying fluid under different heating methods to ensure the stable discharge of the heat-carrying fluid and is effectively connected to the external medium collection system.

[0058] The distributed optical fiber temperature sensor 3 is arranged on the sample stage 10. The distributed optical fiber temperature sensor 3 is used to wrap around the test piece in a ring shape without contacting the test piece, forming a uniform temperature monitoring area to accurately monitor the temperature changes on the surface and around the test piece, avoiding the problem that local temperature anomalies are not detected. The output end of the distributed optical fiber temperature sensor 3 extends out of the overall annular constant-temperature heat-insulating box 2 and the kettle body 1 through the multi-functional hole 14 and is connected to the system host, which is used to monitor the temperature distribution around the test piece in real time. Based on the change of the optical signal in the distributed optical fiber temperature sensor 3, high-precision and continuous temperature monitoring is realized, and the monitoring data is transmitted to the system host for processing. The high-performance data processing unit of the system host can process the data from the distributed optical fiber temperature sensor 3 in real time, and by analyzing the temperature data and the preset temperature threshold, quickly judge whether the test piece is in an abnormal temperature state, further improving the safety of the device and the reliability of the experimental results.

[0059] There are four lateral displacement measuring devices, which are respectively and hermetically installed in four lateral displacement measuring holes 13. When measuring the lateral displacement of the specimen during the measurement experiment, the lateral displacement data of the specimen during the experiment can be obtained from four different directions. At the same time, using the measurement data in four directions, the vector information of the displacement can be calculated, and then the overall deformation and displacement trend of the specimen during the experiment can be comprehensively analyzed. The lateral displacement measuring device includes a probe 15, a hollow tube 16, a condenser tube 17 and a high-pressure resistant and high-precision displacement measuring instrument 18. The high-pressure resistant and high-precision displacement measuring instrument 18 is fixed at one end of the hollow tube 16. The probe 15 is located inside the hollow tube 16 and is coaxially arranged with the hollow tube 16. The end of the probe 15 is connected to the high-pressure resistant and high-precision displacement measuring instrument 18. The front end of the probe 15 extends into the test cavity 4 and is in full contact with the specimen. The condenser tube 17 is wound around the outer wall of the hollow tube 16. Among them, the high-pressure resistant and high-precision displacement measuring instrument 18 can work stably for a long time under high temperature and high pressure conditions, can withstand the thermal and pressure changes under extreme environmental conditions without damaging its measurement accuracy. At the same time, the lateral displacement generated by the high-pressure resistant and high-precision displacement measuring instrument 18 during the experiment is small and has high precision requirements, which is particularly suitable for the device of the present invention. When the lateral displacement measuring device is installed, a connecting thread 25 is provided on the outer wall of the end of the hollow tube 16 away from the high-pressure resistant and high-precision displacement measuring instrument 18. The hollow tube 16 is inserted into the lateral displacement measuring hole 13 and is threadedly connected to the lateral displacement measuring hole 13 through the connecting thread 25 to ensure the close combination of the lateral displacement measuring device and the experimental device, ensure the sealing performance of the experimental device, and real-time feedback the experimental data. Before the experiment starts, first make the high-pressure resistant and high-precision displacement measuring instrument 18 have a certain reading to ensure that the probe 15 has been in full contact with the specimen to avoid human error. At the same time, in order to prevent the influence of high-temperature thermal expansion and contraction on the lateral displacement measurement result, after heating to the specified temperature and keeping warm for a period of time, record the reading of the high-pressure resistant and high-precision displacement measuring instrument 18. Subsequently, after performing the uniaxial compression experiment, record the reading of the high-pressure resistant and high-precision displacement measuring instrument 18 again. The final test result is the difference between the two measurement readings to effectively eliminate the interference of temperature change on the measurement result, accurately measure the lateral displacement of the specimen, and ensure the accuracy and reliability of the measurement result. The function of winding the condenser tube 17 on the outer wall of the hollow tube 16 is to prevent the high temperature inside the autoclave 1 from being thermally conducted to the high-pressure resistant and high-precision displacement measuring instrument 18 through the probe 15 during the high-temperature mechanical experiment, resulting in a decrease in the accuracy of its measurement result.

[0060] The porous tube 22 and the rubber sleeve 23 are used during the permeability test. A number of holes are evenly distributed and drilled through the wall of the porous tube 22. The rubber sleeve 23 is inserted into the porous tube 22, and the outer wall of the rubber sleeve 23 is in close contact with the inner wall of the porous tube 22. At the top and bottom socket openings of the rubber sleeve 23, outward-turning washers 24 are provided. The outward-turning washers 24 are in close contact with the top and bottom surfaces of the porous tube 22, and the outer diameter of the outward-turning washers 24 is the same as the outer diameter of the porous tube 22. The rubber sleeve 23 is used to wrap the test piece. Its function is to isolate the high-temperature heat-conducting oil inside the autoclave body 1 from the test piece, prevent the high-temperature heat-conducting oil from affecting the experiment, reduce pressure, ensure airtightness, and prevent the test piece from loosening. The number of through holes opened on the porous tube 22 can effectively promote the contact between the high-temperature heat-conducting oil and the test piece, thereby improving the heating efficiency and ensuring uniform heating of the sample. At the same time, these holes also play a role in uniformly applying confining pressure. Through the circulating flow of the high-temperature heat-conducting oil, a stable and uniform confining pressure can be applied to the test piece. Example 2

[0061] This embodiment provides a method of using the experimental device described in Example 1 for uniaxial mechanical experiments under a convective heating method, which specifically includes the following steps:

[0062] S1. Place the test piece on the sample stage 10, so that the distributed fiber optic temperature sensor 3 is wrapped around the test piece in a ring shape and does not come into contact with the test piece; adjust the four lateral displacement measuring devices so that the front ends of the four probes 15 pass through the distributed fiber optic temperature sensor 3 and are all in contact with the test piece; block the permeating fluid outlet hole 8 and the permeating fluid inlet hole 11 with plugs.

[0063] S2. Inject the heat-carrying fluid at a specified temperature into the test cavity 4 inside the autoclave body 1 through the heat-carrying fluid injection hole 12. After the heat-carrying fluid is discharged through the multifunctional hole 14, convective heating of the test piece is achieved.

[0064] S3. Observe the temperature detected by the distributed fiber optic temperature sensor 3. After the detected temperature reaches the specified temperature, perform heat preservation treatment, and then apply pressure to the test piece through the axial pressure head 7 to conduct a uniaxial mechanical experiment at high temperature in real time. At the same time, detect the lateral displacement of the test piece through the lateral displacement measuring device; observe and record the experimental data in real time to ensure the accuracy and integrity of the data. Example 3

[0065] This embodiment provides a method of using the experimental device described in Example 1 for uniaxial mechanical experiments under a conduction heating method, which specifically includes the following steps:

[0066] S1. Place the test piece on the sample stage 10, and wrap the distributed optical fiber temperature sensor 3 around the test piece in a circular shape without contacting the test piece; adjust the four lateral displacement measuring devices so that the front ends of the four probes 15 pass through the distributed optical fiber temperature sensor 3 and are all in contact with the test piece; block the permeating fluid outlet hole 8, the permeating fluid inlet hole 11, and the multi-functional hole 14 with plugs.

[0067] S2. Inject the protective gas nitrogen into the test cavity 4 inside the kettle body 1 through the heat-carrying fluid injection hole 12. After the protective gas is injected, block the heat-carrying fluid injection hole 12 with a plug.

[0068] S3. Turn on the annular constant temperature heat insulation box 2 to heat the test piece inside the kettle body 1.

[0069] S4. Observe the temperature detected by the distributed optical fiber temperature sensor 3. After the detected temperature reaches the specified temperature, perform heat preservation treatment, and then apply pressure to the test piece through the axial pressure head 7 to conduct a uniaxial mechanical experiment at high temperature in real time. At the same time, detect the lateral displacement of the test piece through the lateral displacement measuring device; observe and record the experimental data in real time to ensure the accuracy and integrity of the data. Example 4

[0070] This example provides a usage method for the experimental device described in Example 1 to conduct a uniaxial mechanical experiment under the supercritical fluid heating method, which specifically includes the following steps:

[0071] S1. Place the test piece on the sample stage 10, and wrap the distributed optical fiber temperature sensor 3 around the test piece in a circular shape without contacting the test piece; adjust the four lateral displacement measuring devices so that the front ends of the four probes 15 pass through the distributed optical fiber temperature sensor 3 and are all in contact with the test piece; block the permeating fluid outlet hole 8 and the permeating fluid inlet hole 11 with plugs.

[0072] S2. Inject supercritical fluid into the test cavity 4 inside the kettle body 1 through the heat-carrying fluid injection hole 12. After the supercritical fluid is discharged through the multi-functional hole 14, convective heating of the test piece is achieved; the supercritical fluid can be supercritical water or carbon dioxide. The supercritical fluid is generated by a supercritical fluid generator, and the temperature and pressure of the supercritical fluid are controlled by the supercritical fluid generator to achieve convective heating of the test piece.

[0073] S3. Observe the temperature detected by the distributed optical fiber temperature sensor 3. After the detected temperature reaches the specified temperature, perform heat preservation treatment, and then apply pressure to the test piece through the axial pressure head 7 to conduct a uniaxial mechanical experiment at high temperature in real time. At the same time, detect the lateral displacement of the test piece through the lateral displacement measuring device; observe and record the experimental data in real time to ensure the accuracy and integrity of the data. Example 5

[0074] This embodiment provides a usage method of the experimental device described in Embodiment 1 when performing real-time high-temperature permeability testing, which specifically includes the following steps:

[0075] S1. Remove the four lateral displacement measuring devices, seal and install a backpressure valve on one of the lateral displacement measuring holes 13, and plug the remaining three lateral displacement measuring holes 13 and the multi-functional hole 14 with plugs.

[0076] S2. Place the specimen in the rubber sleeve 23, place the combination of the specimen, rubber sleeve 23, and porous tube 22 on the sample stage 10, connect the distributed fiber optic temperature sensor 3 to the outer wall of the porous tube 22, apply axial pressure to the specimen through the axial pressure head 7, and use the annular pressure head 6 to press the turned-up washer 24 of the rubber sleeve 23 to achieve the sealing of the specimen by the rubber sleeve 23; the rubber sleeve 23 can effectively maintain the sealing performance under high-temperature and high-pressure conditions, and the combination of the rubber sleeve 23 and the porous tube 22 can effectively protect the specimen during the test and ensure that the permeating fluid can fully contact the specimen through the porous tube 22 under high-temperature conditions.

[0077] S3. Inject high-temperature heat-conducting oil with a specified pressure into the test cavity 4 inside the autoclave 1 through the heat-carrying fluid injection hole 12 to apply confining pressure.

[0078] S4. Turn on the annular constant-temperature heat-insulating box 2 to heat the specimen in the autoclave 1, and at the same time observe the temperature detected by the distributed fiber optic temperature sensor 3. Due to the presence of the rubber sleeve 23, the heating temperature does not exceed 180 °C to prevent adverse effects on the experiment due to its thermal change; after the detected temperature reaches the specified temperature, perform heat preservation treatment.

[0079] S5. Inject the seepage fluid through the seepage fluid inlet hole 11 and discharge the seepage fluid through the seepage fluid outlet hole 8; observe in real time data such as the seepage fluid flow rate of the specimen under specified temperature, pressure, and pore pressure conditions, so as to test the permeability of the specimen, observe and record the experimental data in real time to ensure the accuracy and integrity of the data.

[0080] After the experiment is completed, discharge the high-temperature heat-conducting oil in the autoclave 1 through the heat-carrying fluid injection hole 12 on the base 9 to prevent environmental pollution and avoid waste of resources. Embodiment 6

[0081] After the experimental methods of the above embodiments are completed, it is possible to first ensure that all high-temperature and high-pressure parameters have returned to a safe level while still keeping the device airtight; then turn on the cooling system so that cooling water flows through the annular through-hole 19 of the base 9. The annular through-hole 19 surrounds the device base 9 to ensure uniform cooling. During the cooling process, use the distributed fiber optic temperature sensor 3 to monitor the temperature of the device to ensure that the temperature drops to the set safe range; keep the cooling water flowing for a period of time until the temperature of the device drops to the safe and operable range; when the temperature reaches the safe range, turn off the cooling system and stop the cooling water from flowing; after confirming that the device has cooled completely, then perform disassembly and subsequent processing according to the standard operating procedures.

[0082] In summary, the present invention provides a multi-functional mechanical experimental device with multiple heating methods for testing the uniaxial mechanical properties and permeability of minerals under high-temperature conditions, which solves the shortcomings of the existing devices having a single use and being unable to perform solid mechanics experiments or real-time high-temperature seepage under multiple heating conditions; the experimental device of the present invention can detect the uniaxial mechanical properties, permeability data and lateral displacement data of the specimen in real time under high-temperature conditions. At the same time, the experimental device of the present invention has the function of real-time monitoring of the temperature changes inside the specimen and the kettle body, and has the characteristics of safety and reliability, convenient operation and convenient maintenance.

[0083] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited to this. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the premise of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the patent protection scope determined by the claims submitted by the present invention.

Claims

1. A multi-functional mechanical experiment device with multiple heating methods, characterized in that: It includes a kettle body (1), an annular constant-temperature heat-insulating box (2), a distributed optical fiber temperature sensor (3), and a lateral displacement measuring device; Inside the kettle body (1), a test cavity (4) is provided. A top cover (5) is installed on the top of the kettle body (1). An annular pressure head (6) is inserted at the center position of the top cover (5), and the bottom end of the annular pressure head (6) extends into the test cavity (4). An axial pressure head (7) is inserted into the annular pressure head (6), and the bottom end of the axial pressure head (7) extends into the test cavity (4), and the top end of the axial pressure head (7) extends out of the top end of the annular pressure head (6). An osmotic fluid outlet hole (8) communicating with the test cavity (4) is provided on the axial pressure head (7). One end orifice of the osmotic fluid outlet hole (8) is opened on the bottom surface of the axial pressure head (7), and the other end orifice of the osmotic fluid outlet hole (8) is opened on the upper side wall of the axial pressure head (7). A base (9) is installed at the bottom of the kettle body (1). A sample stage (10) extending upward is fixed at the center position of the top of the base (9), and the sample stage (10) extends into the test cavity (4). An osmotic fluid inlet hole (11) communicating with the test cavity (4) is provided on the base (9). One end orifice of the osmotic fluid inlet hole (11) is opened on the lower side wall of the base (9), and the other end orifice of the osmotic fluid inlet hole (11) is opened on the top surface of the sample stage (10). A heat-carrying fluid injection hole (12) communicating with the test cavity (4) is provided on the base (9). One end orifice of the heat-carrying fluid injection hole (12) is opened on the lower side wall of the base (9), and the other end orifice of the heat-carrying fluid injection hole (12) is opened on the top surface of the base (9). An annular through hole (19) for circulating water cooling is provided at the bottom of the base (9); The annular constant-temperature heat-insulating box (2) is sleeved outside the kettle body (1), and electric heating wires for heating are provided inside the annular constant-temperature heat-insulating box (2). Four lateral displacement measuring holes (13) penetrating through the annular constant-temperature heat-insulating box (2) and the kettle body (1) and communicating with the test cavity (4) are evenly distributed on the four sides of the annular constant-temperature heat-insulating box (2) and the kettle body (1) as a whole, and the lateral displacement measuring holes (13) are used for installing the lateral displacement measuring device. A multi-functional hole (14) penetrating through the annular constant-temperature heat-insulating box (2) and the kettle body (1) and communicating with the test cavity (4) is provided on one side of the annular constant-temperature heat-insulating box (2) and the kettle body (1) as a whole, which is used for temperature and pressure detection and heat-carrying fluid discharge; The distributed optical fiber temperature sensor (3) is arranged on the sample stage (10), and the output end of the distributed optical fiber temperature sensor (3) extends out of the annular constant-temperature heat-insulating box (2) and the kettle body (1) as a whole through the multi-functional hole (14); Four lateral displacement measuring devices are provided. The four lateral displacement measuring devices are respectively and hermetically installed in four lateral displacement measuring holes (13); the lateral displacement measuring device includes a probe (15), a hollow tube (16), a condensation tube (17) and a high-pressure resistant and high-precision displacement measuring instrument (18). The high-pressure resistant and high-precision displacement measuring instrument (18) is fixed at one end of the hollow tube (16). The probe (15) is located inside the hollow tube (16) and is coaxially arranged with the hollow tube (16). The end of the probe (15) is connected to the high-pressure resistant and high-precision displacement measuring instrument (18). The front end of the probe (15) extends outside the hollow tube (16) and extends into the test cavity (4). The condensation tube (17) is wound around the outer wall of the hollow tube (16).

2. The multi-functional mechanical experiment device with multiple heating methods according to claim 1, characterized in that: Flange plates (20) are provided at the peripheral edge of the top cover (5), the top and bottom peripheral edges of the kettle body (1), and the top peripheral edge of the base (9). The top cover (5) and the top of the kettle body (1) are fixedly connected by the flange plate (20) and bolts. The base (9) and the bottom of the kettle body (1) are fixedly connected by the flange plate (20) and bolts.

3. The multi-functional mechanical experimental device with multiple heating methods according to claim 1, characterized in that: A gap sealing ring (21) is provided between the kettle body (1) and the top cover (5), and the gap sealing ring (21) is simultaneously hermetically sleeved outside the annular pressure head (6). A gap sealing ring (21) is provided between the kettle body (1) and the base (9). A gap sealing ring (21) is provided between the annular pressure head (6) and the axial pressure head (7).

4. A multi-functional mechanical experiment device with multiple heating methods according to claim 1, characterized in that: The inner wall of the annular constant temperature heat insulation box (2) is provided with a reflective material layer, and the outer wall of the annular constant temperature heat insulation box (2) is provided with a high-efficiency heat insulation material layer.

5. A multi-functional mechanical experiment device with multiple heating methods according to claim 1, characterized in that: A connecting thread (25) is provided on the outer wall of one end of the hollow tube (16) away from the high-pressure resistant and high-precision displacement measuring instrument (18). The hollow tube (16) is inserted into the lateral displacement measuring hole (13) and is threadedly connected to the lateral displacement measuring hole (13) through the connecting thread (25).

6. The multi-functional mechanical experimental device with multiple heating methods according to claim 1, characterized in that: It also includes a porous tube (22), a rubber sleeve (23) and a back pressure valve. A plurality of holes are uniformly and penetratingly opened on the tube wall of the porous tube (22); the rubber sleeve (23) is inserted into the porous tube (22), and the outer wall of the rubber sleeve (23) is in close contact with the inner wall of the porous tube (22); turnover washers (24) are provided at the top and bottom socket openings of the rubber sleeve (23). The turnover washers (24) are in close contact with the top and bottom surfaces of the porous tube (22), and the outer diameter of the turnover washers (24) is the same as the outer diameter of the porous tube (22).

7. A method for using a multi-functional mechanical experiment device with multiple heating methods as described in claim 1, characterized in that: 1) When performing a uniaxial mechanical experiment using the convection heating method, it includes: S1. Place the specimen on the sample stage (10), so that the distributed optical fiber temperature sensor (3) annularly wraps around the specimen without contacting the specimen; adjust the four lateral displacement measuring devices so that the front ends of the four probes (15) pass through the distributed optical fiber temperature sensor (3) and then contact the specimen; block the permeating fluid outlet hole (8) and the permeating fluid inlet hole (11) with plugs; S2. Inject a heat-carrying fluid at a specified temperature into the test cavity (4) inside the autoclave body (1) through the heat-carrying fluid injection hole (12). After the heat-carrying fluid is discharged through the multi-functional hole (14), convective heating of the specimen is achieved. S3. Observe the temperature detected by the distributed fiber optic temperature sensor (3). After the detected temperature reaches the specified temperature, perform heat preservation treatment. Subsequently, apply pressure to the specimen through the axial indenter (7) to conduct a uniaxial mechanical experiment at high temperature in real time, and at the same time, detect the lateral displacement of the specimen through the lateral displacement measuring device. 2) When conducting a uniaxial mechanical experiment using the conduction heating method, it includes: S1. Place the specimen on the sample stage (10) so that the distributed fiber optic temperature sensor (3) annularly wraps around the specimen without contacting the specimen; adjust the four lateral displacement measuring devices so that the front ends of the four probes (15) pass through the distributed fiber optic temperature sensor (3) and then contact the specimen; block the permeating fluid outlet hole (8), the permeating fluid inlet hole (11), and the multi-functional hole (14) with plugs. S2. Inject a protective gas into the test cavity (4) inside the autoclave body (1) through the heat-carrying fluid injection hole (12). After the protective gas is injected, block the heat-carrying fluid injection hole (12) with a plug. S3. Turn on the annular constant temperature heat insulation box (2) to heat the specimen inside the autoclave body (1). S4. Observe the temperature detected by the distributed fiber optic temperature sensor (3). After the detected temperature reaches the specified temperature, perform heat preservation treatment. Subsequently, apply pressure to the specimen through the axial indenter (7) to conduct a uniaxial mechanical experiment at high temperature in real time, and at the same time, detect the lateral displacement of the specimen through the lateral displacement measuring device. 3) When conducting a uniaxial mechanical experiment using the supercritical fluid heating method, it includes: S1. Place the specimen on the sample stage (10) so that the distributed fiber optic temperature sensor (3) annularly wraps around the specimen without contacting the specimen; adjust the four lateral displacement measuring devices so that the front ends of the four probes (15) pass through the distributed fiber optic temperature sensor (3) and then contact the specimen; block the permeating fluid outlet hole (8) and the permeating fluid inlet hole (11) with plugs. S2. Inject a supercritical fluid into the test cavity (4) inside the autoclave body (1) through the heat-carrying fluid injection hole (12). By controlling the temperature and pressure of the supercritical fluid, convective heating of the specimen is achieved. After the supercritical fluid is discharged through the multi-functional hole (14), convective heating of the specimen is achieved. S3. Observe the temperature detected by the distributed fiber optic temperature sensor (3). After the detected temperature reaches the specified temperature, perform heat preservation treatment. Subsequently, apply pressure to the specimen through the axial indenter (7) to conduct a uniaxial mechanical experiment at high temperature in real time, and at the same time, detect the lateral displacement of the specimen through the lateral displacement measuring device.

8. The usage method of a multi-functional mechanical experiment device with multiple heating methods according to claim 7, characterized in that: When conducting a uniaxial mechanical experiment using the conduction heating method, the protective gas is nitrogen; when conducting a uniaxial mechanical experiment using the supercritical fluid heating method, the supercritical fluid is supercritical water or carbon dioxide.

9. A method for using a multi-functional mechanical experiment device with multiple heating methods as described in claim 6, characterized in that: When conducting a real-time high-temperature permeability test, it includes: S1. Remove the four lateral displacement measuring devices, seal and install a backpressure valve on one of the lateral displacement measuring holes (13), and plug the remaining three lateral displacement measuring holes (13) and the multi-functional hole (14) with plugs; S2. Place the specimen in the rubber sleeve (23), place the combination of the specimen, the rubber sleeve (23), and the porous tube (22) on the sample stage (10), connect the distributed fiber optic temperature sensor (3) to the outer wall of the porous tube (22), apply axial pressure to the specimen through the axial pressure head (7), and use the annular pressure head (6) to compress the turned-out washer (24) of the rubber sleeve (23) to achieve the sealing of the specimen by the rubber sleeve (23); S3. Inject high-temperature heat-conducting oil with a specified pressure into the test cavity (4) inside the autoclave body (1) through the heat-carrying fluid injection hole (12) to apply confining pressure; S4. Turn on the annular constant-temperature heat-insulating box (2) to heat the specimen in the autoclave body (1), and at the same time observe the temperature detected by the distributed fiber optic temperature sensor (3). After the detected temperature reaches the specified temperature, perform heat preservation treatment; S5. Inject seepage fluid through the seepage fluid inlet hole (11) and discharge the seepage fluid through the seepage fluid outlet hole (8) to test the permeability of the specimen.

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