Rock direct shear experiment device capable of simulating water-force-heat three-field coupling environment

Abstract

The invention provides a rock direct shear experiment device capable of simulating a water-force-heat three-field coupling environment, and belongs to the technical field of rock tests.The rock direct shear experiment device comprises a sealed test box, and the sealed test box is composed of a test box body stress frame, a shear box, a high-temperature loading unit, a confining pressure loading unit and a hydraulic fracturing unit; the shear box is arranged in the test box main body stress frame, and the high-temperature loading unit, the hydraulic fracturing unit and the confining pressure loading unit are all arranged on the outer side of the shear box. The device provided by the invention can realize a multi-field coupling rock shear test, and solves the problem that in the prior art, an experiment can only be carried out under a single physical field condition and the coupling effect of three environments of water, force and heat cannot be effectively simulated; and a technical support is provided for developing the subject research of multi-field coupling environment deep rock mass engineering such as deep terrestrial heat and the like.

Description

Technical Field

[0001] The invention relates to the technical field of rock testing, in particular to a rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment. Background Art

[0002] As the global demand for renewable energy increases, 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 a variety of applications such as industrial heat, heating and electricity production. However, the development of deep geothermal resources faces many challenges, especially the physical and mechanical properties of rocks, which have the greatest impact on development design and safety. Therefore, precise experimental research is needed to understand the behavior of rocks under high temperature, high pressure and moisture environments.

[0003] In the process of deep geothermal development, the strength and deformation characteristics of rocks have an important impact on the structural design, sealing and hydraulic fracturing of geothermal wells. In order to meet these needs, rock direct shear experiments, as a key experimental method, are essential to understand the behavior of rocks in coupled water-mechanical-thermal environments. However, the existing rock direct shear experimental devices still have some significant problems when applied to deep geothermal research: 1. Insufficient multi-field coupling capability: Traditional rock direct shear test equipment can only conduct experiments under a single physical field (such as static pressure or temperature), and cannot 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.

[0004] 2. Lack of precision in temperature and pressure control: In the process of deep geothermal development, temperature and pressure often change dramatically, but the existing experimental equipment has insufficient precision in high temperature and high pressure control, which makes it difficult to meet the stringent experimental requirements. This affects the repeatability and reliability of the experiment, and further affects the interpretation and application of the experimental results.

[0005] 3. Leakage of heat and pressure: The sealing and thermal insulation design of traditional rock direct shear test equipment is often not perfect, which will lead to leakage of heat and pressure gas during the experiment, reduce the accuracy of the experiment and may cause safety hazards.

[0006] 4. Insufficient simulation capability of hydraulic fracturing process: In deep geothermal development, hydraulic fracturing is an important means to enhance resource extraction. However, traditional direct shear devices are often unable to achieve precise control of fluid injection rate and pressure during hydraulic fracturing, which seriously affects the experimental results.

[0007] Therefore, there is an urgent need for a rock direct shear experimental device that can simulate the coupled environment of water, force and heat. Summary of the invention

[0008] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a rock direct shear test device that can simulate the water-force-heat three-field coupling environment, which can realize multi-field coupled rock shear tests, and solves the problem that the prior art can only conduct experiments under a single physical field condition and cannot effectively simulate the three-field coupling effects of water, force and heat. It provides technical support for the research of deep rock engineering projects in multi-field coupling environments such as deep geothermal.

[0009] To achieve the above object, the present invention provides the following solutions: A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupled environment comprises a sealed test box, wherein the sealed test box 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.

[0010] Preferably, 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 insulation board is arranged between the bottom of the shear box and the upper surface of the lower test box, a second insulation board 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.

[0011] Preferably, 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, and a plurality of groups of bearing liquid columns are arranged between the first bearing plate and the top inner wall 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.

[0012] Preferably, 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.

[0013] Preferably, a sample is arranged below the upper shear box body, and the sample is placed at the bottom of the shear box. A second bearing plate and a third bearing plate are respectively arranged at both ends of the sample, and the second bearing plate and the third bearing plate are respectively connected to the lower shear box body of the shear box.

[0014] Preferably, the high-temperature loading unit comprises a heating tube, which is arranged on the outer wall of the shear box. 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.

[0015] Preferably, 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.

[0016] According to the specific embodiments provided by the present invention, compared with the prior art, the present invention discloses the following technical effects: The present invention provides a rock direct shear test device which can simulate the water-mechanics-heat three-field coupled environment. The design of the device integrates the functions of high-temperature loading, confining pressure loading and hydraulic fracturing. The experiment can be carried out in the environment of water, force and heat three physical fields, realizing multi-field coupled rock shear test and fully simulating the actual situation in geotechnical engineering. By adding a reaction force bearing pressure head, multiple insulation boards and a bearing plate, the temperature and pressure stability during the experiment are guaranteed, and the problem of heat and pressure leakage during the experiment is overcome. At the same time, the 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 of deep rock engineering in multi-field coupled environments such as deep geothermal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 This is a structural cross-sectional view of a rock direct shear test device of the present invention that can simulate a water-mechanical-thermal three-field coupling environment; Figure 2 A cross-sectional view of the water injection port position provided in the first embodiment of the present invention; Figure 3 A cross-sectional view of the position of the heating tube provided in the first embodiment of the present invention; Description of reference numerals: 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 thermal insulation board; 10. Second thermal insulation board; 11. Second load-bearing plate; 12. Third load-bearing plate; 13. Upper shear box body; 14. Test specimen; 15. Reverse load-bearing pressure head; 16. Reaction plate; 17. Water inlet; 18. Heating tube. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Embodiment 1 like Figure 1 As shown, this embodiment provides a rock direct shear test device that can simulate the water-mechanical-thermal three-field coupling environment, including a sealed test box 1, which is composed of a test box main body force 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 force 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 on the outside of the shear box 7.

[0022] Specifically, the main force frame of the test box 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 board 9 is arranged between the bottom of the shear box 7 and the upper surface of the lower test box 3. A second heat insulation board 10 is arranged between one side of the shear box 7 and the side wall of the upper test box 2 and the side wall of the lower test box 3. The structural arrangement of the first heat insulation board 9 and the second heat insulation board 10 is intended to solve the problem of heat leakage in a high-temperature coupling environment. The top of the shear box 7 is connected to 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 passes through the upper cover plate 8. The top of the upper pressure head 6 is connected to a first bearing plate 5. Several groups of bearing liquid columns 4 are arranged between the first bearing plate 5 and the inner wall of the top of the upper test box 2. Several groups of bearing liquid columns 4 are evenly arranged between the first bearing plate 5 and the upper test box 2, which effectively realizes uniform confining pressure loading on the sample 14 and ensures the reliability of the experimental data.

[0023] Among them, the bottom end of the upper pressure head 6 is in contact with the upper shear box body 13 inside the shear box 7. The upper shear box body 13 is an L-shaped structure, which has good mechanical properties and can provide effective support in the shear test. The vertical part of the upper shear box body 13 is in contact with a reverse bearing pressure head 15. One end of the reverse bearing pressure head 15 passes through the side wall of the shear box 7. The other end of the reverse bearing pressure head 15 is connected to a reaction plate 16. The top of the reaction plate 16 is fixedly connected to the upper test box 2, which solves the problem of pressure leakage, provides another direction of support for the confining pressure loading experiment, and ensures the stability of the experiment. A sample 14 is arranged below the upper shear box body 13. The sample 14 is placed at the bottom of the shear box 7. The second bearing plate 11 and the third bearing plate 12 are respectively arranged at both ends of the sample 14. The second bearing plate 11 and the third bearing plate 12 are respectively connected to the lower shear box 7 body of the shear box 7, which ensures that the sample 14 is fixed and uniformly stressed during the experiment.

[0024] In addition, refer to Figure 3 The high temperature loading unit includes a heating tube 18, which is arranged on the outer wall of the shear box 7. The outer wall of the shear box 7 is axially provided with a groove. The heating tube 18 is embedded in the groove of the outer wall of the shear box 7, which can effectively increase the temperature of the sample 14, simulate the deep geothermal environment, and improve the realism of the experiment. Figure 2 The hydraulic fracturing unit includes several groups of water injection ports 17, which are arranged on one side of the shear box 7 and below the reverse bearing pressure head 15. It can effectively simulate the hydraulic fracturing process during the experiment and provide technical support for studying the mechanical behavior of rock under hydraulic fracturing conditions.

[0025] Working principle: At the beginning of the experiment, the sample 14 is placed at the bottom of the shear box 7, and the two ends of the sample 14 are connected to the second bearing plate 11 and the third bearing plate 12 respectively to ensure the stability of the sample 14; then the external heating device is started to heat the heating tube 18, and the shear box 7 is heated to the required temperature of the experiment through the heating tube 18 to simulate the deep geothermal environment; at the same time, the pressure device can also be started to apply pressure to the upper shear box body 13 through the upper pressure head 6, and the confining pressure of the sample 14 can be controlled by controlling the height of the bearing liquid column 4, and the sample 14 is subjected to uniform confining pressure by setting the reverse bearing pressure head 15; then, water is injected through the water injection port 17, and the water pressure is controlled by external equipment to simulate the environment of hydraulic fracturing. Here, a gradual pressurization method can be used to ensure that the water pressure is moderate; finally, the shear loading experiment is started. In the above process, monitoring structures such as sensors 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 described in detail.

[0026] Therefore, the above-mentioned rock direct shear test device that can simulate the water-mechanics-heat three-field coupled environment is used. The design of this device integrates the functions of high-temperature loading, confining pressure loading and hydraulic fracturing. Experiments can be carried out in the environment of three physical fields of water, force and heat, realizing multi-field coupled rock shear tests and fully simulating the actual situation in geotechnical engineering; and by adding reaction-force bearing pressure heads, multiple insulation boards and bearing plates, the temperature and pressure stability during the experiment is guaranteed, and the problem of heat and pressure leakage during the experiment is overcome; at the same time, the device greatly improves the applicability of the experiment, and can provide more accurate and reliable experimental data for rock mechanics research, and provides technical support for the research of deep rock engineering in multi-field coupled environments such as deep geothermal.

[0027] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A rock direct shear test device that can simulate the water-mechanical-thermal three-field coupling environment. It is characterized in that It includes a sealed test box, which consists 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.

2. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment according to claim 1, It is characterized in that 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 insulation board is arranged between the bottom of the shear box and the upper surface of the lower test box. A second insulation board 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 to an upper cover plate by bolts.

3. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment according to claim 2, It is characterized in that 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, and a plurality of groups of bearing liquid columns are arranged between the first bearing plate and the top inner wall 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.

4. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment according to claim 3, It is characterized in that 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 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. The top of the reaction plate is fixedly connected to the upper test box.

5. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment according to claim 4, It is characterized in that A sample is arranged below the upper shear box body, and the sample is placed at the bottom of the shear box. A second bearing plate and a third bearing plate are respectively arranged at both ends of the sample, and the second bearing plate and the third bearing plate are respectively connected to the lower shear box body of the shear box.

6. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment according to claim 5, It is characterized in that The high-temperature loading unit includes a heating tube, which is arranged on the outer wall of the shear box. The outer wall of the shear box is axially provided with a groove, and the heating tube is embedded in the groove of the outer wall of the shear box.

7. A rock direct shear test device capable of simulating a water-mechanical-thermal three-field coupling environment according to claim 6, It is characterized in that The hydraulic fracturing unit comprises a plurality of groups of water injection ports, which are arranged on one side of the shear box and below the reverse bearing pressure head.

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