A rock direct shear test device capable of simulating the water-hydro-mechanical-thermal three-field coupling environment

Abstract

The present invention provides a direct shear test device for rocks that can simulate the coupled environment of water, force, and heat, belonging to the technical field of rock testing. It includes a sealed test box, and the sealed test box is composed of a force-bearing frame of the test box main body, a shear box, a high-temperature loading unit, a confining pressure loading unit, and a hydraulic fracturing unit. The shear box is arranged inside the force-bearing frame of the test box main body, and the high-temperature loading unit, the hydraulic fracturing unit, and the confining pressure loading unit are all arranged outside the shear box. The device provided by the present invention can realize multi-field coupled rock shear tests, solves the problem in the prior art that experiments can only be carried out under single physical field conditions and cannot effectively simulate the coupling effect of the three environments of water, force, and heat, and provides technical support for carrying out research on topics such as deep rock mass engineering in multi-field coupled environments such as deep geothermal energy.

Description

Technical Field

[0001] The present invention relates to the technical field of rock testing, and particularly to a direct shear experimental device for rocks that can simulate a coupled water-hydro-thermal environment. Background Art

[0002] With the increasing global demand for renewable energy, the development of deep geothermal energy has gradually become a hot area of concern. As a clean and sustainable form of energy, deep geothermal energy can effectively provide various applications such as industrial heating, heating, and power generation. However, the development of deep geothermal resources faces many challenges, especially the physical and mechanical properties of rocks have the greatest impact on development design and safety. Therefore, precise experimental research is needed to understand the behavior of rocks in high-temperature, high-pressure, and moisture environments.

[0003] During the development of deep geothermal energy, the strength and deformation characteristics of rocks have important implications for aspects such as the structural design, sealing, and hydraulic fracturing of geothermal wells. To meet these requirements, the direct shear experiment of rocks, as a key experimental method, is crucial for understanding the behavior of rocks in a coupled water-hydro-thermal environment. However, when existing rock direct shear experimental devices are applied to deep geothermal research, there are still some significant problems:

[0004] 1. Insufficient multi-field coupling ability: Traditional rock direct shear experimental devices can often only conduct experiments under a single physical field (such as static pressure or temperature), and do not have the ability to simultaneously simulate complex coupling conditions including deep high temperature, high pressure, and moisture environment. This limitation results in the experimental results being unable to truly reflect the actual response of rocks in deep geothermal development.

[0005] 2. Lack of temperature and pressure control accuracy: During the development of deep geothermal energy, temperature and pressure often change violently, but existing experimental devices have problems with insufficient accuracy in high-temperature and high-pressure control, making it difficult to meet strict experimental requirements. This affects the repeatability and reliability of the experiments, and thus affects the interpretation and application of experimental results.

[0006] 3. Heat and pressure leakage problems: The sealing and heat insulation designs of traditional rock direct shear experimental devices are often not perfect, which can lead to heat and pressure gas leakage problems during the experiment, reducing the accuracy of the experiment and potentially causing safety hazards.

[0007] 4. Insufficient simulation ability of the hydraulic fracturing process: In deep geothermal development, hydraulic fracturing is an important means to enhance resource extraction, but traditional direct shear devices often cannot achieve precise control of the fluid injection rate and pressure during the hydraulic fracturing process, seriously affecting the experimental results.

[0008] Therefore, there is an urgent need for a direct shear test device for rocks that can simulate the coupled environment of water, force, and heat. Summary of the Invention

[0009] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a direct shear test device for rocks that can simulate the coupled environment of water - force - heat, which can realize multi - field coupled rock shear tests, solve the problem that in the prior art, experiments can only be carried out under single physical field conditions and cannot effectively simulate the coupled effects of the three environments of water, force, and heat, and provide technical support for the research on deep rock mass engineering in multi - field coupled environments such as deep geothermal energy.

[0010] To achieve the above - mentioned purpose, the present invention provides the following solutions:

[0011] A direct shear test device for rocks that can simulate the coupled environment of water - force - heat, comprising a sealed test box, the sealed test box is composed of a test box main body force - bearing frame, a shear box, a high - temperature loading unit, a confining pressure loading unit, and a hydraulic fracturing unit. The shear box is arranged inside the test box main body force - bearing frame, and the high - temperature loading unit, the hydraulic fracturing unit, and the confining pressure loading unit are all arranged outside the shear box.

[0012] Preferably, the test box main body force - bearing frame is composed of an upper test box and a lower test box. The shear box is arranged in the cavity formed by the upper test box and the lower test box. A first heat - insulating plate is arranged between the bottom of the shear box and the upper surface of the lower test box. A second heat - insulating plate is arranged between one side of the shear box and the side walls of the upper test box and the lower test box. The top of the shear box is connected with an upper cover plate by bolts.

[0013] Preferably, the confining pressure loading unit includes an upper pressure head. The bottom end of the upper pressure head penetrates through the upper cover plate. The top end of the upper pressure head is connected with a first bearing plate. Between the first bearing plate and the inner wall of the top of the upper test box, there are several groups of bearing liquid columns, and several groups of the bearing liquid columns are evenly arranged between the first bearing plate and the upper test box.

[0014] Preferably, the bottom end of the upper pressure head is in contact with the upper shear box body inside the shear box. The upper shear box body is of an L - shaped structure. The vertical part side of the upper shear box body is in contact with a reverse bearing pressure head. One end of the reverse bearing pressure head penetrates through the side wall of the shear box, and the other end of the reverse bearing pressure head is connected with a reaction plate. The top of the reaction plate is fixedly connected with the upper test box.

[0015] Preferably, a specimen is arranged below the upper shear box body. The specimen is placed at the bottom of the shear box. Second bearing plates and third bearing plates are respectively arranged at both ends of the specimen, and the second bearing plate and the third bearing plate are respectively connected with the lower shear box body of the shear box.

[0016] Preferably, the high-temperature loading unit includes a heating pipe disposed on the outer wall of the shear box. A groove is axially formed on the outer wall of the shear box, and the heating pipe is embedded in the groove on the outer wall of the shear box.

[0017] Preferably, the hydraulic fracturing unit includes a plurality of groups of water injection ports. The plurality of groups of water injection ports are disposed on one side of the shear box and below the reverse bearing pressure head.

[0018] According to the specific embodiments provided by the present invention, compared with the prior art, the present invention discloses the following technical effects:

[0019] The present invention provides a rock direct shear test device capable of simulating a water-force-heat three-field coupling environment. The design of the device integrates the functions of high-temperature loading, confining pressure loading, and hydraulic fracturing, and can conduct experiments in the environments of three physical fields of water, force, and heat, realizing a multi-field coupling rock shear test and fully simulating the actual situation in geotechnical engineering. By adding a reaction bearing pressure head, a plurality of heat insulation plates, and a bearing plate, the temperature and pressure stability during the experiment are ensured, and the problems of heat and pressure leakage during the experiment are overcome. At the same time, the applicability of the experiment is greatly improved, and more accurate and reliable experimental data can be provided for rock mechanics research, providing technical support for the research on deep rock mass engineering in multi-field coupling environments such as deep geothermal energy. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0021] Figure 1 It is a structural sectional view of a rock direct shear test device capable of simulating a water-force-heat three-field coupling environment according to the present invention;

[0022] Figure 2 It is a sectional view of the position of the water injection port provided in the first embodiment of the present invention;

[0023] Figure 3 It is a sectional view of the position of the heating pipe provided in the first embodiment of the present invention;

[0024] Explanation of the reference numerals:

[0025] 1. Sealing test box; 2. Upper test box; 3. Lower test box; 4. Load-bearing liquid column; 5. First load-bearing plate; 6. Upper pressure head; 7. Shear box; 8. Upper cover plate; 9. First heat insulation plate; 10. Second heat insulation plate; 11. Second load-bearing plate; 12. Third load-bearing plate; 13. Upper shear box body; 14. Specimen; 15. Reverse load-bearing pressure head; 16. Reaction plate; 17. Water injection port; 18. Heating pipe. Specific embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] To make the objectives, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Embodiment 1

[0029] As Figure 1 shown, this embodiment provides a rock direct shear test device that can simulate the water-force-heat three-field coupling environment, including a sealing test box 1. The sealing test box 1 is composed of a test box main body stress frame, a shear box 7, a high-temperature loading unit, a confining pressure loading unit, and a hydraulic fracturing unit. The shear box 7 is arranged inside the test box main body stress frame to effectively isolate the external environment and ensure the stability of the experimental conditions; the high-temperature loading unit, the hydraulic fracturing unit, and the confining pressure loading unit are all arranged outside the shear box 7.

[0030] Specifically, the test box main body stress frame is composed of an upper test box 2 and a lower test box 3. A shear box 7 is arranged in the cavity formed by the upper test box 2 and the lower test box 3. A first heat insulation plate 9 is arranged between the bottom of the shear box 7 and the upper surface of the lower test box 3, and a second heat insulation plate 10 is arranged between one side of the shear box 7 and the side walls of the upper test box 2 and the lower test box 3. The structural settings of the first heat insulation plate 9 and the second heat insulation plate 10 are aimed at solving the problem of heat leakage in the high-temperature coupling environment. The top of the shear box 7 is connected with an upper cover plate 8 by bolts. The confining pressure loading unit includes an upper pressure head 6. The bottom end of the upper pressure head 6 penetrates through the upper cover plate 8. The top end of the upper pressure head 6 is connected with a first load-bearing plate 5. A number of groups of load-bearing liquid columns 4 are arranged between the first load-bearing plate 5 and the inner wall of the top of the upper test box 2. The number of groups of load-bearing liquid columns 4 are evenly arranged between the first load-bearing plate 5 and the upper test box 2, effectively realizing uniform confining pressure loading on the specimen 14 and ensuring the reliability of experimental data.

[0031] Among them, the bottom end of the upper platen 6 is in contact with the upper shear box body 13 inside the shear box 7. The upper shear box body 13 has an L-shaped structure, enabling it to have good mechanical properties and provide effective support during the shear experiment. The vertical part side of the upper shear box body 13 is in contact with the reverse bearing platen 15. One end of the reverse bearing platen 15 penetrates through the side wall of the shear box 7, and the other end of the reverse bearing platen 15 is connected to a reaction plate 16. The top of the reaction plate 16 is fixedly connected to the upper test box 2, solving the problem of pressure leakage, providing support in another direction for the confining pressure loading experiment, and ensuring the stability of the experiment. A specimen 14 is arranged below the upper shear box body 13. The specimen 14 is placed at the bottom of the shear box 7. Second bearing plates 11 and third bearing plates 12 are respectively arranged at both ends of the specimen 14. The second bearing plates 11 and the third bearing plates 12 are respectively connected to the lower shear box body of the shear box 7, ensuring the fixation and uniform stress of the specimen 14 during the experiment.

[0032] In addition, referring to Figure 3 , the high-temperature loading unit includes a heating pipe 18. The heating pipe 18 is arranged on the outer wall of the shear box 7. A groove is axially formed on the outer wall of the shear box 7. The heating pipe 18 is embedded in the groove on the outer wall of the shear box 7, which can effectively increase the temperature of the specimen 14, simulate the deep geothermal environment, and improve the authenticity of the experiment. Referring to Figure 2 , the hydraulic fracturing unit includes several groups of water injection ports 17. The several groups of water injection ports 17 are arranged on one side of the shear box 7 and are located below the reverse bearing platen 15, which can effectively simulate the process of hydraulic fracturing during the experiment and provide technical support for studying the mechanical behavior of rocks under hydraulic fracturing conditions.

[0033] Working principle: At the beginning of the experiment, the specimen 14 is placed at the bottom of the shear box 7. The two ends of the specimen 14 are respectively connected to the second bearing plates 11 and the third bearing plates 12 to ensure the stability of the specimen 14. Subsequently, start the external heating device, so that the heating pipe 18 starts to heat, and heat the shear box 7 to the temperature required for the experiment through the heating pipe 18 to simulate the deep geothermal environment. At the same time, the pressure application device can also be started to apply pressure to the upper shear box body 13 through the upper platen 6. By controlling the height of the bearing liquid column 4, the confining pressure borne by the specimen 14 can be controlled, and by setting the reverse bearing platen 15, the specimen 14 can be subjected to uniform confining pressure. Subsequently, inject water through the water injection ports 17 and control the pressure of the water through external equipment to simulate the hydraulic fracturing environment. Here, a step-by-step pressurization method can be adopted to ensure appropriate water pressure. Finally, start the shear loading experiment. During the above process, sensors and other monitoring structures can be installed on the experimental device to monitor the experimental process, and this belongs to the conventional technical means in this field and will not be elaborated too much.

[0034] Therefore, by adopting the above-mentioned direct shear test device for rock that can simulate the coupled environment of water, stress and heat, the design of this device integrates the functions of high-temperature loading, confining pressure loading and hydraulic fracturing, and can conduct experiments in the environments of three physical fields of water, stress and heat, realizing the multi-field coupled rock shear test and fully simulating the actual situation in geotechnical engineering; and by adding a reaction bearing pressure head, multiple heat insulation plates and a bearing plate, the temperature and pressure during the experiment are ensured to be stable, overcoming the problems of heat and pressure leakage during the experiment; at the same time, this device greatly improves the applicability of the experiment, can provide more accurate and reliable experimental data for rock mechanics research, and provides technical support for the research on topics such as deep rock mass engineering in multi-field coupled environments such as deep geothermal energy.

[0035] In this paper, specific examples are used to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment, characterized in that: The invention comprises a sealing test box, which is composed of a test box main body force frame, a shear box, a high temperature loading unit, a confining pressure loading unit and a hydraulic fracturing unit. The shear box is arranged inside the test box main body force frame, and the high temperature loading unit, the hydraulic fracturing unit and the confining pressure loading unit are all arranged outside the shear box. The main force-bearing frame of the test box is composed of an upper test box and a lower test box, the shear box is arranged in the cavity formed by the upper test box and the lower test box, a first heat insulation plate is arranged between the bottom of the shear box and the upper surface of the lower test box, a second heat insulation plate is arranged between one side of the shear box and the side wall of the upper test box and the side wall of the lower test box, and the top of the shear box is connected to an upper cover plate by bolts; the confining pressure loading unit includes an upper pressure head, the bottom end of the upper pressure head passes through the upper cover plate, the top end of the upper pressure head is connected to a first bearing plate, a plurality of groups of bearing liquid columns are arranged between the first bearing plate and the inner wall of the top of the upper test box, and the plurality of groups of bearing liquid columns are evenly arranged between the first bearing plate and the upper test box; The high temperature loading unit comprises a heating tube, which is arranged on the outer wall of the shear box, and a groove is axially opened on the outer wall of the shear box, and the heating tube is embedded in the groove of the outer wall of the shear box; the hydraulic fracturing unit comprises a plurality of groups of water injection ports, and the plurality of groups of water injection ports are arranged on one side of the shear box and are located below the reverse bearing pressure head; The bottom end of the upper pressure head is in contact with the upper shear box body inside the shear box, and the upper shear box body is an L-shaped structure. The vertical part of the upper shear box body is in contact with a reverse bearing pressure head, one end of the reverse bearing pressure head passes through the side wall of the shear box, and the other end of the reverse bearing pressure head is connected to a reaction plate, and the top of the reaction plate is fixedly connected to the upper test box; a specimen is arranged below the upper shear box body, and the specimen is placed at the bottom of the shear box, and a second bearing plate and a third bearing plate are respectively arranged at both ends of the specimen, and the second bearing plate and the third bearing plate are respectively connected to the lower shear box body of the shear box.

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