True triaxial loading mechanism for simulating ultra-deep drilling core dynamics

Abstract

The present invention provides a true triaxial loading mechanism for simulating the dynamics of ultra-deep drilling cores, comprising a reaction loading frame, a first principal stress loading assembly, a second principal stress loading assembly and a third principal stress loading assembly, wherein a high-pressure fluid loading chamber extending along the third principal stress direction is constructed inside the reaction loading frame, and a core sample is arranged in the high-pressure fluid loading chamber, wherein the first principal stress loading assembly, the second principal stress loading assembly and the third principal stress loading assembly provide principal stress loading for the core sample in three principal stress directions, and the third principal stress loading assembly is integrated in the reaction loading frame, and the third principal stress loading assembly blocks the high-pressure fluid loading chamber, so that the high-pressure fluid loading chamber is formed into an ultra-high pressure chamber. The present invention can simulate the dynamic true triaxial loading conditions of ultra-deep drilling cores in deep geological environments during the true triaxial loading process of the core sample, so as to obtain stress-strain information of the dynamic disturbance full destruction process.

Description

Technical Field

[0001] The invention relates to the technical field of deep rock mechanics, and in particular to a true triaxial loading mechanism simulating ultra-deep drilling core dynamics. Background Art

[0002] Deep rock engineering has disasters that induce rock deformation and failure under dynamic conditions, such as earthquake stick-slip deformation and instantaneous reactivation of faults. Deep rock excavation engineering has dynamic disturbances, such as the periodic dynamic contact between carbide tools and rocks in mechanical excavation, which are all within the scope of rock dynamics.

[0003] However, so far, no experimental research on rock dynamic deformation and failure behavior under geological environment conditions and real underground stress conditions (σ1>σ2>σ3>0, σ1, σ2, σ3 are maximum principal stress, intermediate principal stress, and minimum principal stress, respectively) has been carried out. The main reason is the lack of dynamic true triaxial instruments. In order to meet the needs of true triaxial dynamic testing of pilot geological drilling cores in deep earth engineering, it is necessary to develop ultra-deep drilling core true triaxial that meets the needs of small-size core testing. Summary of the invention

[0004] The present invention provides a true triaxial loading mechanism for simulating the dynamics of ultra-deep drill cores, which can not only effectively monitor and control the first principal stress and the second principal stress provided by the first principal stress loading component and the second principal stress loading component, but also provide dynamic force disturbance within 30 Hz, thereby simulating the dynamic true triaxial loading conditions of ultra-deep drill cores in a deep geological environment, so as to obtain stress-strain information of the full destruction process of the dynamic disturbance of the ultra-deep drill core sample.

[0005] In order to achieve the above-mentioned invention object, the technical solution provided by the present invention is as follows:

[0006] The true triaxial loading mechanism for simulating ultra-deep drilling core dynamics is suitable for performing principal stress loading on ultra-deep drilling core samples in the first principal stress direction, the second principal stress direction and the third principal stress direction, respectively, so as to simulate the stress of the core in a deep geological environment, and is characterized in that it comprises: a reaction force loading frame, a first principal stress loading component, a second principal stress loading component and a third principal stress loading component, wherein a high-pressure fluid loading chamber extending along the third principal stress direction is configured inside the reaction force loading frame, the first principal stress loading component, the second principal stress loading component and the third principal stress loading component are connected to the reaction force loading frame and communicated with the high-pressure fluid loading chamber, the reaction force loading frame provides a reaction force structure for the first principal stress loading and the second principal stress loading, the third principal stress loading component is integrated in the reaction force loading frame, the third principal stress loading component blocks the high-pressure fluid loading chamber, and the high-pressure fluid loading chamber is formed as an ultra-high pressure pressure chamber.

[0007] Optionally, the first principal stress loading assembly comprises a first hydraulic actuator, a second hydraulic actuator, a first force sensor and a first magnetostrictive displacement sensor, the first hydraulic actuator and the second hydraulic actuator are located on opposite sides of the reaction force loading frame in the direction of the first principal stress, the first hydraulic actuator and the second hydraulic actuator are connected to the reaction force loading frame and communicated with the high-pressure fluid loading chamber, the first force sensor is connected to the first hydraulic actuator and the second hydraulic actuator and is arranged at one end close to the high-pressure fluid loading chamber, and the first magnetostrictive displacement sensor is connected to the first hydraulic actuator and the second hydraulic actuator and is arranged at the other end away from the high-pressure fluid loading chamber;

[0008] The second principal stress loading assembly comprises a third hydraulic actuator, a fourth hydraulic actuator, a force sensor and a magnetostrictive displacement sensor, wherein the third hydraulic actuator and the fourth hydraulic actuator are located on opposite sides of the reaction force loading frame in the direction of the second principal stress, the third hydraulic actuator and the fourth hydraulic actuator are connected to the reaction force loading frame and communicated with the high-pressure fluid loading chamber, the first force sensor is connected to the third hydraulic actuator and the fourth hydraulic actuator and is arranged at one end close to the high-pressure fluid loading chamber, and the first magnetostrictive displacement sensor is connected to the third hydraulic actuator and the fourth hydraulic actuator and is arranged at the other end away from the high-pressure fluid loading chamber;

[0009] The third principal stress loading assembly comprises a first vertical confining pressure head, a second vertical confining pressure head, a tension guide column and a lifting mechanism. The first vertical confining pressure head and the second vertical confining pressure head are located at opposite ends of the reaction force loading frame along the third principal stress direction. The tension guide column is respectively connected to the first vertical confining pressure head and the second vertical confining pressure head at opposite ends along the third principal stress direction. The tension guide column is slidably connected to the reaction force loading frame. The first vertical confining pressure head, the second vertical confining pressure head and the tension guide column form a column-type pull-back tension frame. The lifting mechanism connects the column-type pull-back tension frame and drives the column-type pull-back tension frame to slide on the reaction force loading frame along the third principal stress direction. When the column-type pull-back tension frame slides to one end of the reaction force loading frame, the high-pressure fluid loading chamber is opened. When the column-type pull-back tension frame slides to the other end of the reaction force loading frame, the high-pressure fluid loading chamber is blocked.

[0010] Optionally, the first hydraulic actuator, the second hydraulic actuator, the third hydraulic actuator and the fourth hydraulic actuator have the same structure, including an actuator piston, a connecting terminal of the force sensor is arranged at the front end of the actuator piston, and the magnetostrictive displacement sensor is arranged at the rear end of the actuator piston, wherein the front end of the actuator piston is one end close to the high-pressure fluid loading chamber, and the rear end of the actuator piston is the other end away from the high-pressure fluid loading chamber.

[0011] Optionally, the reaction force loading frame is an annular frame, and four mounting holes of the same structure are opened at the opposite ends of the first principal stress direction and the opposite ends of the second principal stress direction to install the first principal stress loading component and the second principal stress loading component. The mounting hole includes an outer hole and an inner hole, the inner hole and the outer hole are interconnected, and the inner hole is connected to the high-pressure fluid loading chamber, the aperture of the inner hole is smaller than the aperture of the outer hole, and the mounting hole is a two-stage stepped hole, and the hole wall of the mounting hole is formed as the outer cylinder wall of the first hydraulic actuator and the second hydraulic actuator, and the piston is tightly matched with the outer cylinder wall.

[0012] Optionally, the first hydraulic actuator, the second hydraulic actuator, the third hydraulic actuator and the fourth hydraulic actuator have the same structure, and also include an actuator tail flange, an actuator cover, a load sensor, a pressure head and an anti-rotation mechanism, the actuator piston is a double-rod structure, the front end of the actuator piston is provided with a mounting countersunk hole for the load sensor, the rear end of the actuator piston is provided with a mounting countersunk hole for the anti-rotation mechanism, a through hole is provided between the mounting countersunk hole of the load sensor and the mounting countersunk hole of the anti-rotation mechanism, the actuator piston is located in the mounting hole of the reaction force loading frame, and a sliding seal is used between the actuator piston and the mounting hole;

[0013] The actuator tail flange is installed on the side of the reaction force loading frame, the actuator tail flange and the mounting hole on the reaction force loading frame are statically sealed, the actuator tail flange and the actuator piston are slidingly sealed, and the actuator tail flange is provided with a lead terminal mounting hole for the load sensor;

[0014] The actuator cover is installed on the actuator tail flange, the actuator cover and the actuator tail flange are statically sealed, the actuator cover is provided with a hysteresis telescopic displacement sensor lead terminal mounting hole, the actuator cover is provided with an anti-rotation guide column mounting hole, and the actuator cover is also provided with a hysteresis telescopic displacement sensor mounting hole;

[0015] The load sensor is installed in the load sensor mounting hole on the actuator piston, the pressure head is installed on the load sensor, the anti-rotation mechanism is installed in the anti-rotation mechanism mounting countersunk hole, and the anti-rotation mechanism is slidably matched with the anti-rotation guide column.

[0016] Optionally, a stress unloading oil chamber is formed between the actuator piston and the mounting hole on the reaction force loading frame, a stress loading oil chamber is formed between the actuator piston and the actuator tail flange, the reaction force loading frame is provided with corresponding stress loading oil chamber oil ports and stress unloading oil chamber oil ports, a pressure balancing oil chamber is formed between the actuator piston, the actuator tail flange and the actuator cover, and the pressure balancing oil chamber is connected to the high-pressure fluid loading chamber through a through hole on the actuator piston.

[0017] Optionally, the first vertical confining pressure head is configured as a two-stage stepped structure of a cylinder and a quadrangular prism, the quadrangular prism is connected to the four tension guide columns, the reaction force loading frame is provided with a through hole in the direction of the third principal stress, and a sliding seal is adopted between the first vertical confining pressure head and the through hole;

[0018] The second vertical confining pressure head adopts a stepped cylindrical structure, and the second vertical confining pressure head includes a first head section and a second head section. The diameter of the first head section is larger than that of the second head section. The first head section is connected to the four tension guide columns, and a sliding seal is adopted between the second head section and the through hole of the reaction force loading frame.

[0019] Optionally, a positioning frame for the core sample is provided in the high-pressure fluid loading chamber, the positioning frame is installed on the first vertical confining pressure head, the reaction force loading frame is provided with four equally divided through holes along the annular direction, the tension guide column passes through the four equally divided through holes of the reaction force loading frame, and the tension guide column is slidably matched with the reaction force loading frame.

[0020] Optionally, the lifting mechanism is a hydraulic bidirectional acting cylinder, and the lifting mechanism is connected to the first vertical confining pressure head. The lifting mechanism drives the first vertical confining pressure head, the second vertical confining pressure head, and the tension guide column to form the columnar return tension frame to reciprocate along the third principal stress direction.

[0021] Optionally, the second vertical confining pressure head is also provided with an oil inlet, an oil outlet and a displacement sensor lead outlet of the high-pressure fluid loading chamber, and the oil inlet, the oil outlet and the volume change sensor lead outlet pass through the second vertical confining pressure head and are connected to the high-pressure fluid loading chamber.

[0022] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0023] The above scheme simulates the true three-axis loading mechanism of ultra-deep drilling core dynamics. By arranging a force sensor and a hysteresis displacement sensor on any hydraulic actuator in the first principal stress loading assembly and the second principal stress loading assembly, it is possible to transmit a servo feedback signal to the motion control of the hydraulic actuator at any time, thereby effectively monitoring and controlling the first principal stress and the second principal stress provided by the first principal stress loading assembly and the second principal stress loading assembly.

[0024] The reaction force loading frame provides a reaction force structure for the first principal stress loading and the second principal stress loading. The third principal stress loading component is integrated in the reaction force loading frame. The third principal stress loading component blocks the high-pressure fluid loading cavity, and the high-pressure fluid loading cavity is formed into an ultra-high-pressure pressure chamber, which is conducive to meeting the needs of friction force, starting pressure and motion response frequency of the sealing interface in high-frequency response dynamic tests.

[0025] In some exemplary embodiments, the actuator piston hole is provided on the reaction force loading frame, and a two-stage stepped hole is used, which actually constitutes the outer cylinder wall of the actuator. The inner hole adopts a fine grinding process, and the sealing type between the piston and the actuator cylinder wall adopts a special sealing material, structure and compression amount to ensure low starting pressure and dynamic response characteristics.

[0026] In some exemplary schemes, a double-rod structure is adopted in the actuator piston, the front and rear end areas of the actuator piston are consistent, the pressure balance oil chamber is connected to the high-pressure fluid loading chamber, and both are under the action of confining pressure. It cleverly achieves self-balancing while having strong ability to resist lateral forces. The MOOG servo valve controls the oil port of the actuator stress loading oil chamber and the oil port of the stress unloading oil chamber, which can realize dynamic disturbance loading of rock samples with a frequency of up to 30Hz, meeting the excitation frequency response requirements caused by mechanical vibration and rock fracture in rock engineering.

[0027] In some exemplary schemes, the second vertical confining pressure head is also provided with an oil inlet, an oil outlet and a lead outlet of the body deformation sensor of the high-pressure fluid loading chamber, so as to ensure the large-flow dynamic test requirements of the hydraulic oil circuit, and further ensure the simulation effect of the true triaxial experiment with high-frequency dynamic stress control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0029] Figure 1 It is a structural schematic diagram of the true triaxial loading mechanism for simulating ultra-deep drilling core dynamics of the present invention;

[0030] Figure 2 For the present invention Figure 1 Schematic diagram of the cross section in the AA direction;

[0031] Figure 3 For the present invention Figure 1 A schematic diagram of the structure of another position in the direction shown;

[0032] Figure 4 For the present invention Figure 1 Schematic diagram of part of the structure in the direction shown.

[0033] The accompanying drawings are described as follows:

[0034] 100. True three-axis loading mechanism for simulating ultra-deep drilling core dynamics;

[0035] 1. Counterforce loading frame;

[0036] 01. First principal stress loading assembly; 011. First hydraulic actuator; 012. Second hydraulic actuator; 02. Second principal stress loading assembly; 021. Third hydraulic actuator; 022. Fourth hydraulic actuator; 03. Third principal stress loading assembly; 2. First vertical confining pressure head; 3. Second vertical confining pressure head; 4. Positioning frame; 5. Tension guide column; 6. Lifting mechanism; 7. Working platform; 8. Vertical through hole; 9. Four-divided through hole; 10. Actuator mounting hole; 11. Core sample; 12. Column-type back-force tension frame; 13. Equipment bottom plate; 14. High-pressure fluid loading chamber; 15. Oil inlet; 16. Oil outlet; 17 , the lead outlet of the body change sensor; 18, piston; 19, actuator cover; 20, actuator tail flange; 21, load sensor; 22, pressure head; 23, anti-rotation mechanism; 24, load sensor mounting countersunk hole; 25, anti-rotation mechanism mounting countersunk hole; 26, through hole, 27, load sensor lead terminal mounting hole; 28, hysteresis telescopic displacement sensor lead terminal mounting hole; 29, anti-rotation guide column mounting hole; 30, guide column; 31, hysteresis telescopic displacement sensor mounting hole; 32, stress unloading oil chamber; 33, stress loading oil chamber; 34, stress loading oil chamber oil port; 35, stress unloading oil chamber oil port; 36, pressure balance oil chamber. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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.

[0038] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "one" or "the" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0039] It should be noted that the terms "up", "down", "left", "right", "front", "back", etc. used in the present invention are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0040] Aiming at the dynamic test requirements of ultra-deep drill cores in deep geological environments and meeting the needs of high-frequency response dynamic tests, the present invention proposes a loading mechanism that can provide dynamic force disturbance within 30 Hz and simulate the dynamic true triaxial loading conditions of ultra-deep drill cores in deep geological environments.

[0041] like Figures 1 to 4 As shown, an embodiment of the present invention provides a true triaxial loading mechanism 100 for simulating ultra-deep drilling core dynamics, which is suitable for performing principal stress loading on an ultra-deep drilling core sample 11 in the first principal stress direction, the second principal stress direction and the third principal stress direction, respectively, so as to simulate the stress of the core in a deep geological environment, and comprises a reaction force loading frame 1, a first principal stress loading component 01, a second principal stress loading component 02 and a third principal stress loading component 03, wherein a high-pressure fluid loading chamber 14 extending along the third principal stress direction is constructed inside the reaction force loading frame 1.

[0042] It should be noted here that, combined with Figures 1 to 4 In the directions shown in , the first principal stress direction, the second principal stress direction and the third principal stress direction respectively simulate the directions of the maximum principal stress, the intermediate principal stress and the minimum principal stress under the geological environment conditions and the real ground stress conditions underground. Similarly, the first principal stress can be understood as the maximum principal stress, the second principal stress can be understood as the intermediate principal stress, and the third principal stress can be understood as the minimum principal stress. For ease of understanding and description, the first principal stress direction, the second principal stress direction and the third principal stress direction can be defined as the left-right direction, the front-back direction and the up-down direction, respectively. The Cartesian coordinate system can also be used to define the first principal stress direction, the second principal stress direction and the third principal stress direction as the horizontal axis direction, the longitudinal axis direction and the vertical axis direction, respectively.

[0043] like Figure 3 and Figure 4 As shown, the core sample 11 is arranged in the high-pressure fluid loading chamber 14, the first principal stress loading component 01 provides the first principal stress loading for the core sample 11, the second principal stress loading component 02 provides the second principal stress loading for the core sample 11, and the third principal stress loading component 03 provides the third principal stress loading for the core sample 11. The reaction force loading frame 1 provides a reaction force structure for the first principal stress loading and the second principal stress loading, and the third principal stress loading component 03 is integrated in the reaction force loading frame 1. The third principal stress loading component 03 blocks the high-pressure fluid loading chamber 14, and the high-pressure fluid loading chamber 14 is formed into an ultra-high pressure pressure chamber, which is conducive to meeting the needs of friction force, starting pressure and motion response frequency of the sealing interface in high-frequency response dynamic tests.

[0044] like Figure 1 As shown, the first principal stress loading component 01 includes a first hydraulic actuator 011, a second hydraulic actuator 012, a first force sensor (not shown in the figure) and a first magnetostrictive displacement sensor (not shown in the figure). The first hydraulic actuator 011 and the second hydraulic actuator 012 are located on opposite sides of the reaction force loading frame 1 in the direction of the first principal stress. The first hydraulic actuator 011 and the second hydraulic actuator 012 are connected to the reaction force loading frame 1 and communicated with the high-pressure fluid loading chamber 14. The first force sensor is connected to the first hydraulic actuator 011 and the second hydraulic actuator 012 and is arranged at one end close to the high-pressure fluid loading chamber 14. The first magnetostrictive displacement sensor is connected to the first hydraulic actuator 011 and the second hydraulic actuator 012 and is arranged at the other end away from the high-pressure fluid loading chamber 14.

[0045] Among them, the first hydraulic actuator 011 and the second hydraulic actuator 012 are both provided with the first force sensor and the first hysteresis displacement sensor, which can transmit servo feedback signals to the motion control of the first hydraulic actuator 011 and the second hydraulic actuator 012 at any time, so as to effectively monitor and control the first principal stress provided by the first principal stress loading component 01.

[0046] like Figure 2As shown, the second principal stress loading component 02 includes a third hydraulic actuator 021, a fourth hydraulic actuator 022, a second force sensor (not shown in the figure) and a second magnetostrictive displacement sensor (not shown in the figure). The third hydraulic actuator 021 and the fourth hydraulic actuator 022 are located on opposite sides of the reaction force loading frame 1 in the direction of the second principal stress. The third hydraulic actuator 021 and the fourth hydraulic actuator 022 are connected to the reaction force loading frame 1 and communicated with the high-pressure fluid loading chamber 14. The second force sensor is connected to the third hydraulic actuator 021 and the fourth hydraulic actuator 022 and is arranged at one end close to the high-pressure fluid loading chamber 14. The second magnetostrictive displacement sensor is connected to the third hydraulic actuator 021 and the fourth hydraulic actuator 022 and is arranged at the other end away from the high-pressure fluid loading chamber 14.

[0047] Among them, the third hydraulic actuator 021 and the fourth hydraulic actuator 022 are both provided with a second force sensor and a second hysteresis displacement sensor, which can transmit servo feedback signals at any time for the motion control of the first hydraulic actuator 011 and the second hydraulic actuator 012, so as to effectively monitor and control the second principal stress provided by the second principal stress loading component 02.

[0048] like Figure 3 As shown, the third principal stress loading assembly 03 includes a first vertical confining pressure head 2, a second vertical confining pressure head 3, a tension guide column 5 and a lifting mechanism 6. The first vertical confining pressure head 2 and the second vertical confining pressure head 3 are located at opposite ends of the reaction force loading frame 1 along the third principal stress direction. The tension guide column 5 is respectively connected to the first vertical confining pressure head 2 and the second vertical confining pressure head 3 at opposite ends along the third principal stress direction. The tension guide column 5 is slidably connected to the reaction force loading frame 1. A vertical confining pressure head 2, a second vertical confining pressure head 3 and a tension guide column 5 form a column-type pull-back tension frame 12. The lifting mechanism 6 connects the column-type pull-back tension frame 12 and drives the column-type pull-back tension frame 12 to slide along the third principal stress direction on the reaction loading frame 1. When the column-type pull-back tension frame 12 slides to one end of the reaction loading frame 1, the high-pressure fluid loading chamber 14 is opened. When the column-type pull-back tension frame 12 slides to the other end of the reaction loading frame 1, the high-pressure fluid loading chamber 14 is blocked.

[0049] In some embodiments, Figure 1 and Figure 2As shown, the first hydraulic actuator 011, the second hydraulic actuator 012, the third hydraulic actuator 021 and the fourth hydraulic actuator 022 have the same structure, including an actuator piston 18, a connection terminal of a force sensor is arranged at the front end of the actuator piston 18, and a hysteresis expansion displacement sensor is arranged at the rear end of the actuator piston 18, wherein the front end of the actuator piston 18 is one end close to the high-pressure fluid loading chamber 14, and the rear end of the actuator piston 18 is the other end away from the high-pressure fluid loading chamber 14. The force sensor connection terminal arranged on the actuator piston 18 ensures that the electrical signal is derived from the pressure chamber.

[0050] In some embodiments, Figure 2 As shown, the reaction force loading frame 1 can adopt an annular beam mechanism, and a low-friction dynamic actuator piston hole is processed every 90 degrees on the annular beam. The sample mounting structure is arranged in the upper and lower directions of the annular beam mechanism. In the closed state, the integrated structure is a reaction force frame of a dual-axis loading structure and also an ultra-high pressure pressure chamber. The annular beam mechanism adopts 4 actuator piston holes processed every 90 degrees, and adopts a two-stage stepped hole, which actually constitutes the outer cylinder wall of the actuator. The inner hole close to the high-pressure fluid loading chamber 14 adopts a fine grinding process. The sealing type between the piston 18 and the actuator cylinder wall adopts special sealing materials, structures and compression amounts to ensure low starting pressure and dynamic response characteristics.

[0051] In the above embodiment, Figure 2 As shown, the reaction force loading frame 1 is an annular frame, and four actuator mounting holes 10 of the same structure are opened at the opposite ends of the first principal stress direction and the opposite ends of the second principal stress direction of the annular frame to install the first principal stress loading component 01 and the second principal stress loading component 02. The actuator mounting hole 10 includes an outer hole and an inner hole, the inner hole and the outer hole are interconnected, and the inner hole is connected to the high-pressure fluid loading chamber 14, the inner hole diameter is smaller than the outer hole diameter, the actuator mounting hole 10 is a two-stage stepped hole, the hole wall of the mounting hole is formed as the outer cylinder wall of the first hydraulic actuator 011 and the second hydraulic actuator 012, and the piston 18 is tightly matched with the outer cylinder wall.

[0052] Alternatively, if Figures 1 to 4 As shown, the first hydraulic actuator 011, the second hydraulic actuator 012, the third hydraulic actuator 021 and the fourth hydraulic actuator 022 have the same structure, and also include an actuator tail flange 20, an actuator cover 19, a load sensor 21, a pressure head 22 and an anti-rotation mechanism 23. The actuator piston 18 is a double-rod structure. The front end of the actuator piston 18 is provided with a load sensor mounting countersunk hole 24, the rear end of the actuator piston 18 is provided with an anti-rotation mechanism mounting countersunk hole 25, a through hole 26 is provided between the load sensor mounting countersunk hole 24 and the anti-rotation mechanism mounting countersunk hole 25, the actuator piston 18 is located in the mounting hole of the reaction force loading frame 1, and a sliding seal is used between the actuator piston 18 and the mounting hole.

[0053] The actuator tail flange 20 is installed on the side of the reaction force loading frame 1. The actuator tail flange 20 and the mounting holes on the reaction force loading frame 1 are statically sealed, and the actuator tail flange 20 and the actuator piston 18 are slidingly sealed. The actuator tail flange 20 is provided with a lead terminal mounting hole 27 for the load sensor.

[0054] The actuator cover 19 is installed on the actuator tail flange 20. The actuator cover 19 and the actuator tail flange 20 are statically sealed. The actuator cover 19 is provided with a hysteresis telescopic displacement sensor lead terminal mounting hole 28, the actuator cover 19 is provided with an anti-rotation guide column mounting hole 29, and the actuator cover 19 is also provided with a hysteresis telescopic displacement sensor mounting hole 31;

[0055] like Figure 2 As shown, the load sensor 21 is installed in the load sensor mounting hole 24 on the actuator piston 18, the pressure head 22 is installed on the load sensor 21, the anti-rotation mechanism 23 is installed in the anti-rotation mechanism mounting counterbore 25, and the anti-rotation mechanism 23 is slidably matched with the anti-rotation guide column 30. The reaction force loading frame 1 is used as the outer wall of the four sets of actuators, the actuator is combined with the reaction force loading frame 1, and the force sensor is built into the actuator piston 18. The areas at both ends of the actuator piston 18 are the same, so that the two ends of the piston 18 are subjected to the same pressure. The actuator piston 18 is used as a traditional pressure chamber self-balancing piston 18, which will make the structure of the test device more compact and reduce the stiffness loss. At the same time, the force condition of the sample can be measured more accurately, and the piston 18 is provided with an anti-rotation mechanism 23, which essentially solves the rotation condition of the actuator piston 18.

[0056] Optionally, the load sensor 21 is a load sensor 21 with a rated load of 300 KN to 700 KN, so as to detect a load of the ultra-deep drilling core sample 11 within 700 MPa.

[0057] In some embodiments, in combination Figure 1 and Figure 3 A stress unloading oil chamber 32 is formed between the actuator piston 18 and the mounting hole on the reaction force loading frame 1, a stress loading oil chamber 33 is formed between the actuator piston 18 and the actuator tail flange 20, the reaction force loading frame 1 is provided with corresponding stress loading oil chamber oil ports 34 and stress unloading oil chamber oil ports 35, a pressure balancing oil chamber 36 is formed between the actuator piston 18, the actuator tail flange 20 and the actuator cover 19, and the pressure balancing oil chamber 36 is connected to the high-pressure fluid loading chamber 14 through the through hole 26 on the actuator piston 18.

[0058] In the above embodiment, Figure 2As shown, the actuator piston 18 adopts a double-rod structure, the front and rear end areas of the actuator piston 18 are consistent, the pressure balance oil chamber 36 is connected to the high-pressure fluid loading chamber 14, and under the action of confining pressure, it cleverly achieves self-balancing while having a strong ability to resist lateral forces. The MOOG servo valve controls the actuator stress loading oil chamber oil port 34 and the stress unloading oil chamber oil port 35 to achieve 30HZ dynamic disturbance loading on the core sample 11.

[0059] Alternatively, if Figure 3 and Figure 4 As shown, the first vertical confining pressure head 2 is configured as a two-stage stepped structure of a cylinder and a quadrangular prism, the quadrangular prism is connected to four tension guide columns 5, the reaction force loading frame 1 is provided with a vertical through hole 8 in the third principal stress direction, and a sliding seal is adopted between the first vertical confining pressure head 2 and the through hole.

[0060] In addition, the present invention utilizes the first vertical confining pressure head 2, the second vertical confining pressure head 3, and the tension guide column 55 to form a columnar back force tension frame 12 to achieve confining pressure sealing. The force bearing areas of the first vertical confining pressure head 2 and the second vertical confining pressure head 3 are set to be equal, and no displacement will occur under the action of confining pressure, ensuring that the core sample 11 will not be disturbed by stress in other third directions except confining pressure.

[0061] The second vertical confining pressure head 3 adopts a stepped cylindrical structure. The second vertical confining pressure head 3 includes a first head section and a second head section. The diameter of the first head section is larger than that of the second head section. The first head section is connected to four tension guide columns 5. The second head section and the vertical through hole 8 of the reaction force loading frame 1 are matched by a sliding seal.

[0062] In addition, a positioning frame 4 for the core sample 11 is provided in the high-pressure fluid loading chamber 14, and the positioning frame 4 is installed on the first vertical confining pressure head 2. The reaction force loading frame 1 is provided with four equally divided through holes 9 along the circumferential direction, and the tension guide column 5 passes through the four equally divided through holes 9 of the reaction force loading frame 1, and the tension guide column 5 is slidably matched with the reaction force loading frame 1.

[0063] In the above embodiment, the lifting mechanism 6 is a hydraulic bidirectional cylinder, and the lifting mechanism 6 is connected to the first vertical confining pressure head 2. The lifting mechanism 6 drives the first vertical confining pressure head 2, the second vertical confining pressure head 3, and the tension guide column 5 to form a columnar return tension frame 12 to reciprocate along the third principal stress direction.

[0064] In some embodiments, the second vertical confining pressure head 3 is also provided with an oil inlet 15, an oil outlet 16 and a body change sensor lead outlet 17 of the high-pressure fluid loading chamber 14. The oil inlet 15, the oil outlet 16 and the displacement sensor lead outlet pass through the second vertical confining pressure head 3 and are connected to the high-pressure fluid loading chamber 14.

[0065] In the above embodiment, the reaction loading frame 1 adopts a horizontal annular structure with four equal parts and central symmetry. The reaction loading frame 1 is a regular quadrangular prism. The reaction loading frame 1 is fixedly connected to the working platform 7. Vertical through holes 8 are provided at the centers of the upper and lower bottom surfaces of the reaction loading frame 1. Four equal parts and central symmetric through holes 9 are provided at the upper and lower bottom surfaces of the reaction loading frame 1. Central symmetric actuator mounting holes 10 are provided at the centers of the four side surfaces of the reaction loading frame 1. The actuator mounting holes 10 adopt two-stage stepped holes. The first vertical confining head 2 is a two-stage stepped structure of a cylinder and a quadrangular prism. The quadrangular prism of the first vertical confining pressure head 2 is bolted to four tension guide columns 5. A sliding seal is used between the first vertical confining pressure head 2 and the vertical through holes 8 of the reaction loading frame 1.

[0066] In some embodiments, the second vertical confining pressure head 3 adopts a stepped cylindrical structure, the large cylinder of the second vertical confining pressure head 3 is bolted to four tension guide pillars 5, and the small cylinder of the second vertical confining pressure head 3 is matched with the vertical through hole 8 of the reaction loading frame 1 by sliding sealing. The sample positioning frame 4 is used to fix and position the core sample 11, and the sample positioning frame 4 is installed on the end face of the first vertical confining pressure head 2; the tension guide pillar 5 passes through the four-equally divided through hole 9 of the reaction loading frame 1, and the tension guide pillar 5 is slidably matched with the reaction loading frame 1. The first vertical confining pressure head 2, the second vertical confining pressure head 3, and the tension guide pillar 5 form a four-column return tension frame 12, which is installed on the reaction loading frame 1. The lifting mechanism 6 is a hydraulic double-acting cylinder, which is fixed to the equipment bottom plate 13. The lifting mechanism 6 is connected to the first vertical enclosing head 2. The lifting mechanism 6 drives the columnar return tension frame 12 composed of the first vertical enclosing head 2, the second vertical confining pressure head 3, and the tension guide column 5 to move up and down.

[0067] When the first vertical enclosure head 2 is at the upper limit position of the lifting mechanism 6, the first vertical enclosure head 2 is higher than the upper bottom surface of the reaction force loading frame 1. When the first vertical enclosure head 2 is at the lower limit position of the lifting mechanism 6, the small cylinder of the first vertical enclosure head 2 is located in the vertical through hole 8 of the reaction force loading frame 1. The second vertical confining pressure head 3 and the vertical through hole 8 are matched with a sliding seal. The space enclosed by the reaction force loading frame 1, the first vertical enclosure head 2, and the second vertical confining pressure head 3 is used as the confining pressure high-pressure fluid loading chamber 14. The second vertical confining pressure head 3 is respectively provided with a confining pressure high-pressure fluid loading chamber oil inlet 15, a confining pressure high-pressure fluid loading chamber oil outlet 16, and a body change sensor lead outlet 17, so as to ensure the large flow dynamic test requirements of the hydraulic oil circuit, and then ensure the simulation effect of the true triaxial experiment of high-frequency dynamic stress control, and realize the full utilization of the precious ultra-deep drilling core.

[0068] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A true triaxial loading mechanism for simulating ultra-deep drilling core dynamics, suitable for performing principal stress loading on ultra-deep drilling core samples in the first principal stress direction, the second principal stress direction and the third principal stress direction, respectively, to simulate the stress of the core in a deep geological environment, characterized in that: include: A reaction force loading frame, a first principal stress loading component, a second principal stress loading component and a third principal stress loading component, wherein a high-pressure fluid loading chamber extending along the third principal stress direction is configured inside the reaction force loading frame, the first principal stress loading component, the second principal stress loading component and the third principal stress loading component are connected to the reaction force loading frame and communicated with the high-pressure fluid loading chamber, the reaction force loading frame provides a reaction force structure for the first principal stress loading and the second principal stress loading, the third principal stress loading component is integrated into the reaction force loading frame, the third principal stress loading component blocks the high-pressure fluid loading chamber, and the high-pressure fluid loading chamber is formed as an ultra-high pressure pressure chamber; Characterized in that the first principal stress loading assembly comprises a first hydraulic actuator, a second hydraulic actuator, a first force sensor and a first magnetostrictive displacement sensor, the first hydraulic actuator and the second hydraulic actuator are located on opposite sides of the reaction force loading frame in the direction of the first principal stress, the first hydraulic actuator and the second hydraulic actuator are connected to the reaction force loading frame and communicated with the high-pressure fluid loading chamber, the first force sensor is connected to the first hydraulic actuator and the second hydraulic actuator, and is arranged at one end close to the high-pressure fluid loading chamber, the first magnetostrictive displacement sensor is connected to the first hydraulic actuator and the second hydraulic actuator, and is arranged at the other end away from the high-pressure fluid loading chamber; The second principal stress loading assembly comprises a third hydraulic actuator, a fourth hydraulic actuator, a second force sensor and a second magnetostrictive displacement sensor, wherein the third hydraulic actuator and the fourth hydraulic actuator are located on opposite sides of the reaction force loading frame in the direction of the second principal stress, the third hydraulic actuator and the fourth hydraulic actuator are connected to the reaction force loading frame and communicated with the high-pressure fluid loading chamber, the second force sensor is connected to the third hydraulic actuator and the fourth hydraulic actuator and is arranged at one end close to the high-pressure fluid loading chamber, and the second magnetostrictive displacement sensor is connected to the third hydraulic actuator and the fourth hydraulic actuator and is arranged at the other end away from the high-pressure fluid loading chamber; The third principal stress loading assembly comprises a first vertical confining pressure head, a second vertical confining pressure head, a tension guide column and a lifting mechanism, wherein the first vertical confining pressure head and the second vertical confining pressure head are located at opposite ends of the reaction force loading frame along the third principal stress direction, the tension guide column is respectively connected to the first vertical confining pressure head and the second vertical confining pressure head at opposite ends along the third principal stress direction, the tension guide column is slidably connected to the reaction force loading frame, the first vertical confining pressure head, the second vertical confining pressure head and the tension guide column form a column-type pull-back tension frame, the lifting mechanism connects the column-type pull-back tension frame and drives the column-type pull-back tension frame to slide on the reaction force loading frame along the third principal stress direction, the column-type pull-back tension frame slides to one end of the reaction force loading frame to open the high-pressure fluid loading chamber, and the column-type pull-back tension frame slides to the other end of the reaction force loading frame to block the high-pressure fluid loading chamber; The lifting mechanism is a hydraulic double-acting oil cylinder, the lifting mechanism is connected to the first vertical confining pressure head, and the lifting mechanism drives the first vertical confining pressure head, the second vertical confining pressure head, and the tension guide column to form the column-type return force tension frame to reciprocate along the third principal stress direction; The second vertical confining pressure head is also provided with an oil inlet, an oil outlet and a displacement sensor lead outlet of the high-pressure fluid loading chamber, and the oil inlet, the oil outlet and the displacement sensor lead outlet pass through the second vertical confining pressure head and are connected to the high-pressure fluid loading chamber; The first hydraulic actuator, the second hydraulic actuator, the third hydraulic actuator and the fourth hydraulic actuator have the same structure, including an actuator piston, a connection terminal of the force sensor is arranged at the front end of the actuator piston, and the magnetostrictive displacement sensor is arranged at the rear end of the actuator piston, wherein the front end of the actuator piston is one end close to the high-pressure fluid loading chamber, and the rear end of the actuator piston is the other end away from the high-pressure fluid loading chamber; The reaction force loading frame is an annular frame, and the annular frame is provided with four mounting holes of the same structure at two opposite ends in the first principal stress direction and two opposite ends in the second principal stress direction, so as to mount the first principal stress loading component and the second principal stress loading component, and the mounting hole comprises an outer hole and an inner hole, the inner hole and the outer hole are mutually connected, and the inner hole is connected to the high-pressure fluid loading chamber, the inner hole diameter is smaller than the outer hole diameter, the mounting hole is a two-stage stepped hole, the hole wall of the mounting hole is formed as the outer cylinder wall of the first hydraulic actuator and the second hydraulic actuator, and the piston is tightly matched with the outer cylinder wall; The first hydraulic actuator, the second hydraulic actuator, the third hydraulic actuator and the fourth hydraulic actuator have the same structure, and also include an actuator tail flange, an actuator cover, a load sensor, a pressure head and an anti-rotation mechanism. The actuator piston is a double-rod structure. The front end of the actuator piston is provided with a mounting countersunk hole for the load sensor, and the rear end of the actuator piston is provided with a mounting countersunk hole for the anti-rotation mechanism. A through hole is provided between the mounting countersunk hole of the load sensor and the mounting countersunk hole of the anti-rotation mechanism. The actuator piston is located in the mounting hole of the reaction force loading frame, and a sliding seal is used between the actuator piston and the mounting hole; the actuator tail flange is installed on the side of the reaction force loading frame, and the actuator tail flange is in contact with the reaction force loading frame. The mounting hole on the frame adopts static sealing, the actuator tail flange and the actuator piston adopt sliding sealing, and the actuator tail flange is provided with a lead terminal mounting hole of the load sensor; the actuator cover is installed on the actuator tail flange, the actuator cover and the actuator tail flange adopt static sealing, the actuator cover is provided with a hysteresis telescopic displacement sensor lead terminal mounting hole, the actuator cover is provided with an anti-rotation guide column mounting hole, and the actuator cover is also provided with a hysteresis telescopic displacement sensor mounting hole; the load sensor is installed in the load sensor mounting hole on the actuator piston, the pressure head is installed on the load sensor, the anti-rotation mechanism is installed in the anti-rotation mechanism mounting countersunk hole, and the anti-rotation mechanism and the anti-rotation guide column are slidably matched; A stress unloading oil chamber is formed between the actuator piston and the mounting hole on the reaction force loading frame, a stress loading oil chamber is formed between the actuator piston and the actuator tail flange, the reaction force loading frame is provided with corresponding stress loading oil chamber oil ports and stress unloading oil chamber oil ports, a pressure balancing oil chamber is formed between the actuator piston, the actuator tail flange and the actuator cover, and the pressure balancing oil chamber is connected with the high-pressure fluid loading chamber through a through hole on the actuator piston.

2. The true triaxial loading mechanism for simulating ultra-deep drilling core dynamics according to claim 1, characterized in that: The first vertical confining pressure head is configured as a two-stage stepped structure of a cylinder and a quadrangular prism, the quadrangular prism is connected to the four tension guide columns, the reaction force loading frame is provided with a through hole in the direction of the third principal stress, and a sliding seal is adopted between the first vertical confining pressure head and the through hole; The second vertical confining pressure head adopts a stepped cylindrical structure, and the second vertical confining pressure head includes a first head section and a second head section. The diameter of the first head section is larger than that of the second head section. The first head section is connected to the four tension guide columns, and a sliding seal is adopted between the second head section and the through hole of the reaction force loading frame.

3. The true triaxial loading mechanism for simulating ultra-deep drilling core dynamics according to claim 1, characterized in that: A positioning frame for the core sample is provided in the high-pressure fluid loading chamber, the positioning frame is installed on the first vertical confining pressure head, the reaction force loading frame is provided with four equally divided through holes along the circumferential direction, the tension guide column passes through the four equally divided through holes of the reaction force loading frame, and the tension guide column is slidably matched with the reaction force loading frame.

Images