Rock true triaxial compression test device and method

Abstract

The invention discloses a rock true triaxial compression test device and method. The device comprises an annular force bearing frame; the heating box comprises a first box wall, a second box wall and a door body assembly which define a box body structure, the second box wall is provided with an operation opening, the door body assembly opens or closes the operation opening, the first box wall is provided with a first pressing head, and the second box wall or the door body assembly is provided with a second pressing head; the actuator assembly comprises a first actuator corresponding to the first pressure head and a second actuator corresponding to the second pressure head, and the first actuator is connected with the annular force bearing frame and the corresponding first pressure head; the enclasping telescopic assembly is connected with the annular force bearing frame and the second actuator and is configured to drive the second actuator to be close to or away from the second box wall; and the clamping device is configured to clamp or loosen the rock test piece and is configured to be in contact with the first pressure head and the second pressure head. Therefore, the rock test piece can be quickly loaded and unloaded, and the experimental efficiency and the authenticity and accuracy of experimental data are improved.

Description

Technical Field

[0001] The present application relates to the technical field of experimental equipment for rock mechanics, and in particular to a rock true triaxial compression test device and method. Background Art

[0002] Geothermal energy, a green, renewable, and clean energy source attracting widespread attention worldwide, holds enormous potential for development and utilization. Among currently exploitable geothermal resources, hot dry rock possesses the highest potential. Hot dry rock is an abnormally high-temperature rock mass with a temperature range of 180°C to 650°C and a burial depth of more than 3 km. The energy contained in hot dry rock geothermal resources located 3 to 10 km below the Earth's surface is equivalent to 30 times the energy stored in global fossil fuels. Therefore, hot dry rock is of great significance to geothermal power generation projects and possesses high development and utilization value.

[0003] In current true triaxial compression testing devices, the operation of replacing test specimens is rather cumbersome and inconvenient, which affects the test efficiency. Summary of the Invention

[0004] In view of this, the present application provides a rock true triaxial compression test device and method, which can simulate the relatively real conditions of rock specimens at high temperatures, and can realize rapid loading and unloading of samples, thereby improving experimental efficiency and the authenticity and accuracy of experimental data.

[0005] An embodiment of the first aspect of the present application provides a true triaxial compression test device for rock, comprising: an annular load-bearing frame; a heating box, arranged inside the annular load-bearing frame, the heating box comprising a first box wall, a second box wall and a door assembly that together form a box structure, the second box wall being provided with an operating port, the door assembly being connected to the second box wall to open or close the operating port, a first pressure head being provided on the first box wall, and a second pressure head being provided on the second box wall or the door assembly; an actuator assembly, comprising a first actuator corresponding to the first pressure head, and a second actuator corresponding to the second pressure head, the first end of the first actuator being connected to the annular load-bearing frame, and the second end of the first actuator being connected to the corresponding first pressure head; a clamping and telescopic assembly, connecting the annular load-bearing frame and the second actuator, the clamping and telescopic assembly being configured to drive the second actuator to approach the second box wall and abut against the second pressure head or away from the second box wall; a clamper, arranged inside the heating box, configured to clamp or release the rock specimen, and configured to contact the first pressure head and the second pressure head.

[0006] Exemplarily, the heating box is a hexahedral structure, and the second box wall is located on the left or right side of the heating box; the five first actuators are respectively arranged on the upper side, lower side, front side, rear side, and the side opposite to the second box wall of the heating box.

[0007] Exemplarily, the clamping and telescopic assembly includes: a clamping mechanism, a telescopic mechanism, and a clamping column, the clamping mechanism is connected to the second actuator, the first end of the telescopic mechanism is fixed to the annular load-bearing frame, the second end of the telescopic mechanism is connected to the clamping mechanism, the first end of the clamping column is fixed to the annular load-bearing frame, and the second actuator is passed through the clamping column; wherein, the clamping mechanism is configured to self-lock when the telescopic mechanism is closed to limit the relative movement of the second actuator and the clamping column, and to unlock when the telescopic mechanism is started.

[0008] Exemplarily, the clamp includes a pad and an elastic member, the pad is arranged opposite to the first pressure head and the second pressure head, and the pad is connected by the elastic member to enclose a space for accommodating the rock specimen, wherein at least the pad opposite to the second box wall is configured to be detachably connected to the adjacent pad.

[0009] Exemplarily, the elastic member is configured to contact the rock sample so that a gap exists between the rock sample and the spacer in a non-gravity direction.

[0010] Exemplarily, the rock true triaxial compression test device further includes: a fixing seat, the clamp is mounted on the fixing seat, and the fixing seat is detachably connected to the heating box.

[0011] Exemplarily, a heating device is provided inside the heating box, and the heating device includes a heating element corresponding to and connected to the first box wall and the second box wall.

[0012] Exemplarily, fans are further provided inside the heating box, and the fans are arranged in pairs on both sides of the heating box. A temperature sensor is also provided inside the heating box; and / or, the wall of the heating box is a steel shell part with embedded insulation material.

[0013] An embodiment of a second aspect of the present application provides a true triaxial compression test method for rock, using any of the above-mentioned true triaxial compression test devices for rock, the method comprising:

[0014] Based on the second actuator being in the waiting position, the door assembly opens the operating port of the heating box, places the rock specimen in the clamp from the operating port, and fixes the pad in the clamp opposite to the second box wall; controls the door assembly to close the operating port, controls the telescopic mechanism of the telescopic assembly to start, drives the second actuator to move to the test position and then closes the telescopic mechanism; performs a compression test on the rock specimen; based on the rock specimen completing the compression test, controls the telescopic mechanism to start, drives the second actuator to move to the waiting position and then closes the telescopic mechanism, controls the door assembly to open the operating port; removes the pad opposite to the second box wall in the clamp, takes out the damaged rock specimen from the operating port, and re-executes the step of placing the rock specimen in the clamp from the operating port.

[0015] Exemplarily, before the step of placing the rock sample into the holder through the operating port, the method further comprises:

[0016] The rock specimen is placed in the bearing shell;

[0017] The steps for conducting compression test on rock specimens include:

[0018] The first actuator and the second actuator are subjected to displacement control to complete the fixation of the clamp so that the rock specimen is centered and clamped; the heating device and the fan are controlled to work, and based on the detection information of the temperature sensor reaching the first preset value, the first actuator and the second actuator are controlled to perform loading operations, and the rock specimen is subjected to stepped true triaxial loading until the rock specimen is destroyed, and the first actuator, the second actuator, the heating device and the fan are controlled to stop working, and the data of the stress sensor are recorded; the rock specimen is waited for to cool down, and based on the temperature of the rock specimen cooling to the second preset value, the rock specimen completes the compression test.

[0019] The rock true triaxial compression test device and method provided in the embodiment of the present application realize the rock mechanics experiment of the true triaxial experimental equipment under high temperature conditions. Through the heating box, the real conditions of the rock specimen at high temperature (instantaneous 600°C, long-term 400°C) can be simulated, the rock specimen can be evenly heated, and the second actuator can be moved independently. The heating box can realize a side-opening door structure in the direction of the second actuator, which is convenient for taking out and replacing rock samples, can effectively reduce the sample loading time of the experiment, and improve the experimental efficiency. The five first actuators and the second actuator cooperate to realize true triaxial loading operation to simulate the real conditions of the stress environment of the rock specimen. At the same time, the first pressure head and the second pressure head are provided with position sensors, which can ensure the centering loading of each pressure head, improve the loading accuracy, and thus improve the authenticity and accuracy of the experimental data.

[0020] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. Throughout the drawings, the same reference numerals are used to denote the same components.

[0022] Figure 1 One of the structural schematic diagrams of the rock true triaxial compression test device provided in an embodiment of the present application is shown;

[0023] Figure 2 The second structural diagram of the rock true triaxial compression test device provided in an embodiment of the present application is shown;

[0024] Figure 3 One of the structural schematic diagrams of the heating box and the clamp provided in the embodiment of the present application is shown;

[0025] Figure 4 One of the flow charts of the rock true triaxial compression test method provided in the embodiment of the present application is shown.

[0026] in, Figures 1 to 3 The corresponding relationship between the reference numerals and component names is as follows:

[0027] 100 annular load-bearing frame, 200 heating box, 210 first box wall, 220 second box wall, 230 first pressure head, 240 fan, 250 heating device, 300 actuator assembly, 310 first actuator, 311 first largest principal stress actuator, 312 second largest principal stress actuator, 313 first intermediate principal stress actuator, 314 second intermediate principal stress actuator, 315 first minor principal stress actuator, 320 second actuator, 400 clamping and telescopic assembly, 410 clamping mechanism, 420 telescopic mechanism, 430 clamping column, 500 clamp, 510 elastic member, 520 pad, 530 fixed seat, 600 rock specimen. DETAILED DESCRIPTION

[0028] In order to more clearly understand the above-mentioned objects, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other in the absence of conflict.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0030] like Figure 1 、 Figure 2 and Figure 3As shown, an embodiment of the first aspect of the present application provides a rock true triaxial compression test device, comprising: an annular load-bearing frame 100; a heating box 200, arranged inside the annular load-bearing frame 100, the heating box 200 comprising a first box wall 210, a second box wall 220 and a door assembly that together form a box structure, the second box wall 220 being provided with an operation port, the door assembly being connected to the second box wall 220 to open or close the operation port, a first pressure head 230 being provided on the first box wall 210, and a second pressure head being provided on the second box wall 220 or the door assembly; an actuator assembly 300, comprising a first actuator 310 corresponding to the first pressure head 230 , and a second actuator 320 corresponding to the second pressure head, the first end of the first actuator 310 is connected to the annular load-bearing frame 100, and the second end of the first actuator 310 is configured to be connected to the corresponding first pressure head 230; a clamping and telescopic assembly 400, connecting the annular load-bearing frame 100 and the second actuator 320, the clamping and telescopic assembly 400 is configured to drive the second actuator 320 to approach the second box wall 220 and abut against the second pressure head or move away from the second box wall 220; a clamper 500, arranged inside the heating box 200, is configured to clamp or release the clamping part of the rock specimen 600, and is configured to contact the first pressure head 230 and the second pressure head.

[0031] Among them, Figure 3 As shown, the annular load-bearing frame 100 serves as a supporting structure of the rock true triaxial compression test device, and is used to support and install other components.

[0032] Among them, Figures 1 to 3 As shown, the heating box 200 is arranged inside the annular load-bearing frame 100, such as at the center. The clamp 500 is arranged inside the heating box 200, and the clamp 500 is configured to clamp or release the rock specimen 600. That is to say, after the rock specimen 600 is clamped by the clamp 500, it is contained in the heating box 200. It can be understood that the heating box 200 is provided with a heating device 250, so as to adjust the air flow temperature in the heating box 200 through the heating device 250 to simulate the high temperature environment of the rock specimen 600, improve the authenticity of the test environment conditions, and help improve the accuracy of the test. Specifically, the heating box 200 can simulate the real conditions of instantaneous 600°C and long-term 400°C.

[0033] Among them, Figure 1As shown, the heating box 200 includes a first box wall 210, a second box wall 220, and a door assembly that together form a box structure. The door assembly can open or close the operating port on the second box wall 220. A first pressure head 230 is provided on the first box wall 210, and a second pressure head is provided on the second box wall 220 or the door assembly. The first actuator 310 of the actuator assembly 300 corresponds to the first pressure head 230. The first end of the first actuator 310 is connected to the annular load-bearing frame 100, and the second end of the first actuator 310 is connected to the corresponding first pressure head 230. The second actuator 320 of the actuator assembly 300 corresponds to the second pressure head. The second actuator 320 is connected to the annular load-bearing frame 100 via a tightening and telescopic assembly 400. The tightening and telescopic assembly 400 is configured to drive the second actuator 320 to approach the second box wall 220 and abut against the second pressure head or move away from the second box wall 220.

[0034] Therefore, when the door assembly closes the operating port to put the heating box 200 in a sealed state, the telescopic assembly 400 drives the second actuator 320 to move toward the second box wall 220 and abut against the second pressure head, and then the first actuator 310 and the second actuator 320 are used to perform loading operations on the rock specimen 600 clamped by the clamp 500 from each side of the box through the first pressure head 230 and the second pressure head, thereby realizing a true triaxial compression test on the rock specimen 600 to simulate the stress environment of the rock specimen 600, thereby improving the authenticity of the test environment conditions and helping to improve the accuracy of the test.

[0035] When the compression test is completed, the telescopic assembly 400 drives the second actuator 320 to move away from the second box wall 220, leaving sufficient operating space for the door assembly to open the operating port. Then the door assembly opens the operating port, and the user can quickly and conveniently remove the rock specimen 600 clamped by the clamp 500 through the operating port, and replace it with a new rock specimen 600, so as to achieve rapid loading and unloading of the rock specimen 600 and improve test efficiency.

[0036] That is, the rock true triaxial compression test apparatus provided in the embodiment of the present application can simulate a high temperature environment of a rock specimen 600, such as a transient temperature of 600°C and a prolonged temperature of 400°C, through the heating box 200, thereby improving the authenticity of the test environment conditions and facilitating improved test accuracy and the authenticity of experimental data. By disposing a first actuator 310 and a second actuator 320 on each side wall of the heating box 200, respectively, the first actuator 310 and the second actuator 320 cooperate to act on the first indenter 230 and the second indenter 230 on the heating box 200 from different directions to transfer loads to the rock specimen 600 on the clamp 500 inside the heating box 200, allowing the rock specimen 600 to receive loads from different directions, thereby achieving true triaxial loading operations, simulating the stress environment of the rock specimen 600, improving the authenticity of the test environment conditions, and facilitating improved test accuracy and the authenticity of experimental data. By holding the telescopic component 400, the second actuator 320 is driven to move closer to or away from the second box wall 220 to ensure that the second actuator 320 can reliably contact the second pressure head, or leave enough space for the door body component to open the operating port. When the door body component opens the operating port, it is convenient for the user to install the rock specimen 600 to the clamp 500 or remove it from the clamp 500 through the operating port, so as to realize rapid loading and unloading of the rock specimen 600, and realize in-situ loading and unloading of the rock specimen 600, which greatly shortens the replacement time of the rock specimen 600, can significantly improve the test efficiency, and is suitable for popularization and application.

[0037] Among them, Figure 2 As shown, the annular load-bearing frame 100 is an octagonal frame. The first ends of the five first actuators 310 are fixed to the annular load-bearing frame 100 by fixing members. The fixing members can be at least one of a bolt structure, a plug-in structure, a clamping structure, a magnetic structure, and a mortise and tenon structure. Specifically, under normal circumstances, the fixing members are bolt structures.

[0038] The holder 500 is detachably connected to the heating box 200 to facilitate installation of holders 500 of varying sizes within the heating box 200, depending on the size of the rock specimen 600. This improves the reliability and stability of the holder 500 in gripping the rock specimen 600, thereby increasing the accuracy of the test data. Specifically, the holder 500 can be detachably connected to the heating box 200 using at least one of a bolt structure, a plug-in structure, a snap-fit structure, a mortise and tenon structure, and a magnetic structure. Specifically, a slide rail is provided at the bottom of the heating box 200 to facilitate removal of the holder 500 from the heating box 200 for maintenance or replacement.

[0039] Among them, the second pressure head can be set on the second box wall 220 or on the door body assembly. As long as it is ensured that after the door body assembly closes the operating port, the second actuator 320 moves in the direction close to the second box wall 220 to dock and contact with the second pressure head.

[0040] Among them, the first pressing head 230 and the second pressing head are both equipped with cooling devices, which can ensure that the first pressing head 230 and the second pressing head are not affected by the high temperature inside the heating box 200, so that the first actuator 310 and the second actuator 320 are also not affected by the high temperature inside the heating box 200.

[0041] Among them, the door body assembly is connected to the second box wall 220 through a bearing combination and a locking device, that is, the second box wall 220 is designed to be a side-opening door structure, which not only ensures the thermal insulation effect but also realizes the in-situ loading and unloading of the specimens, greatly shortens the specimen replacement time, and can significantly improve the test efficiency.

[0042] In some possible embodiments provided herein, the heating box 200 is a hexahedron, and the second box wall 220 is located on the left or right side of the heating box 200, that is, the operation port is located on the left or right side of the heating box 200. This facilitates the user to quickly load and unload the rock specimen 600 from the left or right side of the heating box 200. It will be appreciated that in some examples, the second box wall 220 may be located on the front or rear side of the heating box 200.

[0043] Among them, the five first actuators 310 are respectively arranged on the upper side, lower side, front side, rear side, and the side opposite to the second box wall 220 of the heating box 200. That is to say, when the second box wall 220 is located on the right side of the heating box 200, the second actuator 320 is located on the right side of the heating box 200, and the five first actuators 310 are respectively arranged on the upper side, lower side, front side, rear side, and left side of the heating box 200. When the second box wall 220 is located on the left side of the heating box 200, the second actuator 320 is located on the right side of the heating box 200, and the five first actuators 310 are respectively arranged on the upper side, lower side, front side, rear side, and right side of the heating box 200. Among them, the axial direction of the annular load-bearing frame 100 is the same as the front-to-back direction of the heating box 200, such as Figure 2 As shown by the arrow X in FIG, the horizontal two sides of the annular load-bearing frame 100 are parallel to the left and right directions of the heating box 200. Figure 1 and Figure 1 As shown by the arrow Z in FIG, the upper and lower surfaces of the annular load-bearing frame 100 are parallel to the upper and lower directions of the heating box 200. Figure 3 As shown by the arrow Y in .

[0044] Specifically, if Figure 1 and Figure 2As shown, taking the second box wall 220 located on the right side of the heating box 200 as an example, the first actuator 310 located on the upper side is the first large principal stress actuator 311, the first actuator 310 located on the lower side is the second large principal stress actuator 312, the first actuator 310 located on the front side is the first medium principal stress actuator 313, and the first actuator 310 located on the rear side is the second medium principal stress actuator 314; the first actuator 310 located on the left side is the first small principal stress actuator 315, and the second actuator 310 located on the right side is the first small principal stress actuator 316. The actuator 320 is a second small principal stress actuator. Thus, five first actuators 310 and one second actuator 320 are arranged in pairs to apply loads in different directions to the rock specimen 600 on the clamp 500 through the first pressure head 230 and the second pressure head from the three directions of up and down, front and back, left and right of the heating box 200, so as to realize true triaxial loading operation, simulate the actual stress environment of the rock specimen 600, improve the authenticity of the test environment conditions, and help improve the accuracy of the test and the authenticity of the experimental data.

[0045] Specifically, the first major principal stress actuator 311, the second major principal stress actuator 312, the first intermediate principal stress actuator 313, the second intermediate principal stress actuator 314, the first minor principal stress actuator 315, and the second actuator 320 have the same structure, including a cover, an annular end cap, a reaction cylinder, a piston, a piston rod, a sealing flange, a force sensor, etc., and only differ in their maximum loading force. Specifically, the first major principal stress actuator 311 and the second major principal stress actuator 312 are connected to the upper and lower surfaces of the annular load-bearing frame 100, the first intermediate principal stress actuator 313 and the second intermediate principal stress actuator 314 are connected to the horizontal surfaces of the annular load-bearing frame 100, and the first minor principal stress actuator 315 and the second actuator 320 are connected to the axial position of the annular load-bearing frame 100.

[0046] like Figure 1 As shown, in some possible embodiments provided in the present application, the clamping and telescopic assembly 400 includes: a clamping mechanism 410, a telescopic mechanism 420, and a clamping column 430. The clamping mechanism 410 is connected to the second actuator 320. The first end of the telescopic mechanism 420 is fixed to the annular load-bearing frame 100. The second end of the telescopic mechanism 420 is connected to the clamping mechanism 410. The first end of the clamping column 430 is fixed to the annular load-bearing frame 100. The second actuator 320 is passed through the clamping column 430. The clamping mechanism 410 is configured to self-lock when the telescopic mechanism 420 is closed to limit the relative movement of the second actuator 320 and the clamping column 430, and to unlock when the telescopic mechanism 420 is started.

[0047] Among them, the clamping column 430 is set parallel to the moving direction of the second actuator 320, such as the clamping column 430 is set parallel to the left and right directions of the heating box 200. It can be understood that the number of the clamping columns 430 can be multiple, such as the clamping columns 430 can be four, and the four clamping columns 430 are arranged symmetrically up and down.

[0048] Among them, the clamping mechanism 410 is connected to the second actuator 320, such as the clamping mechanism 410 and the second actuator 320 are integrated into one component, one end of the telescopic mechanism 420 is fixed on the annular load-bearing frame 100, and the other end is fixed on the clamping mechanism 410. When the telescopic mechanism 420 is started, the clamping mechanism 410 is unlocked, thereby releasing the restriction on the relative movement of the second actuator 320 and the clamping column 430, so that the second actuator 320 can move horizontally along the clamping column 430 to move toward the second box wall 220 or away from the second box wall 220. When the telescopic mechanism 420 is closed, the clamping mechanism 410 self-locks, that is, the clamping mechanism 410 automatically locks, and the relative movement of the second actuator 320 and the clamping column 430 is restricted. At this time, the clamping assembly and the second actuator 320 can be regarded as a whole. As a result, the problem of relative movement between the second actuator 320 and the clamping column 430 affecting the test accuracy when the second actuator 320 applies a load can be reduced, which is conducive to improving the test accuracy.

[0049] It can be understood that when the door assembly is needed to open the operating port of the heating box 200, the telescopic mechanism 420 is started, and the second actuator 320 is moved to the waiting position. The user stands next to the experimental device and operates the door assembly to open the operating port to facilitate the disassembly and assembly of the clamp 500 in the heating box 200, and the disassembly and assembly of the rock specimen 600 on the clamp 500, so as to facilitate the replacement of rock specimens and improve the test efficiency.

[0050] Specifically, the telescopic mechanism 420 may be a hydraulic telescopic rod, or other telescopic mechanisms 420 .

[0051] In this embodiment, when loading and unloading the rock sample, it is only necessary to move the second actuator 320 by controlling the telescopic mechanism 420, while the other parts remain in place, thereby achieving in-situ loading and unloading of the rock sample 600.

[0052] like Figure 3 As shown, in some possible embodiments provided in the present application, the clamp 500 includes a pad 520 and an elastic member 510, the pad 520 is arranged opposite to the first pressure head 230 and the second pressure head, and the pad 520 is connected through the elastic member 510 to enclose a space for accommodating the rock specimen 600, wherein at least the pad 520 opposite to the second box wall 220 is configured to be detachably connected to the adjacent pad 520.

[0053] In this embodiment, there are six pads 520, five pads 520 correspond one-to-one to the five first pressure heads 230, and one pad 520 corresponds to the second pressure head. In this way, uniform loading of the rock specimen 600 can be achieved, avoiding stress concentration.

[0054] By removing the pad 520 opposite to the second box wall 220 (i.e., the pad 520 corresponding to the second pressure head) and the adjacent pad 520, space can be provided for the rock specimen 600 to be placed in the clamp 500 or removed from the clamp 500, making it easier to install the rock specimen 600 in the clamp 500 or remove it from the clamp 500. This can effectively reduce the number of steps required to replace the rock specimen 600, reduce loading and unloading time, and achieve rapid replacement of the rock specimen 600. This is convenient to operate and is conducive to improving the loading and unloading efficiency of the rock specimen 600, thereby improving the testing efficiency. It is understandable that after replacing the rock specimen 600, the pad 520 opposite to the second box wall 220 (i.e., the pad 520 corresponding to the second pressure head) is connected to the adjacent pad 520 to complete the assembly of the clamp 500, which is convenient to operate.

[0055] Among them, since the pads 520 are connected by the elastic member 510 to enclose a space for accommodating the rock specimen 600, the pads 520 opposite to the second box wall 220 can be disassembled, separated or connected with the adjacent pads 520 by operating the elastic member 510. For example, by using tools or manually operating the elastic member 510, the pads 520 opposite to the second box wall 220 can be disassembled and assembled, which can effectively reduce the operating steps of replacing the rock specimen 600 and reduce the loading and unloading time. The operation is simple, convenient and fast, which is conducive to improving the loading and unloading efficiency of the rock specimen 600, thereby improving the test efficiency.

[0056] Specifically, the elastic member 510 may be a spring or other elastic structure. The number of the elastic member 510 may be multiple, such as 6, 8, 10 or other numbers of the elastic members 510.

[0057] In some possible embodiments provided in the present application, the elastic member 510 is configured to contact the rock specimen 600 so that a gap exists between the rock specimen 600 and the spacer 520 in the non-gravity direction.

[0058] The direction of gravity can be understood as the vertically downward direction, and the non-gravity direction is the front, back, left, right, and top directions. That is, under the action of gravity, or under the combined action of gravity and the elastic member 510, the rock specimen 600 contacts the pad 520 located at the bottom. Under the action of the elastic member 510, that is, when the spring fragment does not apply stress, gaps exist between the rock specimen 600 and the pads 520 in the five directions of front, back, left, right, and top. Therefore, after removing the pad 520 opposite the second actuator 320, the rock specimen 600 can be easily removed, reducing the problem of the rock specimen 600 being stuck inside the clamp 500 and being inconvenient to remove. This can effectively reduce the number of steps required to replace the rock specimen 600, shorten loading and unloading time, and achieve rapid loading and unloading.

[0059] In some embodiments, the holder 500 further includes a stress sensor to detect the stress of the rock specimen 600. The stress sensor can be disposed on the side of the rock specimen 600 opposite the first indenter 230. For example, the stress sensor can be disposed on the pad 520 opposite the first indenter 230, so that no stress sensor is disposed on the side of the rock specimen 600 opposite the second indenter. This eliminates the need to move the stress sensor when loading and unloading the rock specimen 600, reduces the frequency of moving the stress sensor, and effectively extends the service life of the stress sensor.

[0060] In some embodiments, to prevent eccentric loading, a position sensor, such as a high-precision position bed safety, is arranged on each first pressure head 230 and the second pressure head, thereby automatically identifying whether it is aligned, and automatically centering the pad 520 through computer control, thereby improving the loading accuracy and further improving the authenticity and accuracy of the experimental data.

[0061] In some embodiments, to prevent debris from collapsing during the experiment, which could result in an inability to capture an image of the complete rock specimen 600, the rock specimen 600 can be placed in a designed support case before loading. The support case covers the five sides (front, back, left, right, and bottom) and has an opening on the top. This effectively ensures the integrity of the rock specimen 600 at high temperatures and prevents debris from flying out and damaging the sensor circuits during the experiment, thereby improving the reliability of the device. Specifically, the support case can be a copper shell with an opening on the top.

[0062] like Figure 3As shown, in some possible embodiments provided herein, the rock true triaxial compression test apparatus further includes a fixing base 530, to which the clamp 500 is mounted, and the fixing base 530 is detachably connected to the heating box 200. Thus, the fixing base 530 allows the clamp 500 to be fixed to the heating box 200 as a whole, or removed from the heating box 200, to facilitate replacement or maintenance of the clamp 500. It is understood that the fixing base 530 can also be moved relative to the slide rails at the bottom of the heating box 200 to enable movement of the clamp 600 relative to the heating box 200.

[0063] Specifically, the clamp 500 can be detachably connected to the fixing seat 530 by means of a bolt structure, a plug-in structure, a mortise and tenon structure, a magnetic structure, etc., and the fixing seat 530 can be detachably connected to the box wall of the heating box 200 or the support frame inside the heating box 200 by means of a bolt structure, a plug-in structure, a mortise and tenon structure, a magnetic structure, etc.

[0064] like Figure 3 As shown, in some possible embodiments provided in the present application, a heating device 250 is provided inside the heating box 200, and the heating device 250 includes a heating element corresponding to and connected to the first box wall 210 and the second box wall 220. That is to say, the heating element is located on the six sides of the heating box 200 to achieve uniform heating of the heating box 200, and is conducive to increasing the temperature to meet the high temperature test conditions of the rock specimen 600, such as simulating the relatively real conditions of the rock specimen 600 at high temperature (instantaneous 600°C, long-term 400°C) to improve the authenticity and accuracy of the test data, to expand the scope of use of the test device, and to improve the accuracy of dry hot rock scientific research. Specifically, the heating element can be a heating wire, a heating tube, a heating plate, or other heating structure. Specifically, the heating box 200 is a cube structure and is placed in the center of the annular load-bearing frame 100. It can be understood that in some examples, the heating box 200 can also be a rectangular parallelepiped structure.

[0065] like Figure 3 As shown, in some possible embodiments provided herein, fans 240 are further provided inside the heating box 200. The fans 240 are arranged in pairs on both sides of the heating box 200 to convey and guide the airflow within the heating box 200, thereby improving the heating uniformity of the heating box. Specifically, the fans 240 can be arranged in pairs on the front and back sides, and / or the left and right sides, and / or the top and bottom sides of the heating box 200. Specifically, fans 240 are arranged on the front, back, left, and right sides of the heating box 200 to ensure uniform heating.

[0066] In some possible embodiments provided herein, the walls of the heating box 200 are made of a steel shell with an embedded thermal insulation material, thereby improving the heat resistance and reliability of the heating box 200. Specifically, the heating box 200 with an embedded thermal insulation material can withstand temperatures up to 600°C.

[0067] In some possible embodiments provided in the present application, a temperature sensor is further provided inside the heating box 200 for detecting the temperature inside the heating box 200 , so as to facilitate the control device to perform test operations according to the temperature sensor.

[0068] Furthermore, an operating port is provided on the right side of the heating box 200, that is, the heating box 200 is designed to be a side-opening door structure on the right side, which can achieve thermal insulation while also facilitating the opening of the operating port after cooling, so as to facilitate loading and unloading of the rock specimen 600. Among them, the center of the five directions of the heating box 200, namely, the top, bottom, front, back, and left sides, is provided with a first pressure head 230 of equal size, and the center of the right side is provided with a second pressure head. The first pressure head 230 and the second pressure head are of equal size. One end of the first pressure head 230 and the second pressure head located inside the heating box 200 is in contact with and connected to the pad 520 of the clamp 500. When loading, one end of the first pressure head 230 and the second pressure head located outside the heating box 200 is correspondingly connected to the first actuator 310 and the second actuator 320 for applying load in the experiment.

[0069] like Figure 4 As shown, an embodiment of the second aspect of the present application provides a rock true triaxial compression test method, using the rock true triaxial compression test device described above, the method comprising:

[0070] Step 410: Based on the second actuator being in the waiting position, the door assembly opens the operating port of the heating box, places the rock specimen in the clamp through the operating port, and fixes the pad in the clamp opposite to the second box wall.

[0071] The second actuator 320 is in the waiting position, away from the second box wall 220, providing space for the door assembly to open the operating opening of the second box wall 220. Opening the operating opening through the door assembly facilitates the user to place the rock specimen 600 in the holder 500 through the operating opening, and assemble the holder 500 by fixing the spacer 520 in the holder 500 opposite the second box wall 220, making the operation simple and convenient.

[0072] It is understood that when there is no rock specimen 600 in the holder 500, the previous rock specimen 600 is removed from the holder 500 by disassembling the spacer 520 opposite the second box wall 220. Therefore, after a new rock specimen 600 is loaded, the spacer 520 opposite the second box wall 220 is connected to the other spacers 520 to complete the assembly of the holder 500. Specifically, the spacer 520 opposite the second box wall 220 can be connected to the other spacers 520 by operating the elastic member 510 to connect with the other components.

[0073] Step 420: Control the door assembly to close the operating port, control the telescopic mechanism of the telescopic assembly to start, drive the second actuator to move to the test position, and then close the telescopic mechanism.

[0074] The door assembly is controlled to close the operating port to ensure the sealing of the heating box 200 .

[0075] By controlling the telescopic mechanism 420 of the clamping telescopic assembly 400 to start, the clamping mechanism 410 is released from self-locking. The telescopic mechanism 420 drives the second actuator 320 to move along the clamping column 430 toward the second box wall 220 to the test position, and then the telescopic mechanism 420 is closed to make the clamping mechanism 410 self-locking. The movement of the second actuator 320 relative to the clamping column 430 is limited, so that the two form an integral motion structure to complete the preparation work before the test.

[0076] It can be understood that the second actuator 320 in the test position contacts the second pressure head, so that the second actuator 320 can load the rock specimen 600 through the second pressure head and the corresponding pad 520.

[0077] Step 430: Perform a compression test on the rock specimen.

[0078] The rock specimen 600 can be heated and loaded to simulate the high temperature environment of the rock specimen 600, and a true triaxial loading operation can be implemented to simulate the stress environment of the rock specimen 600, thereby improving the authenticity of the test environment conditions and helping to improve the accuracy of the test and the authenticity of the experimental data.

[0079] Step 440: Based on the completion of the compression test of the rock specimen, the telescopic mechanism is controlled to start, the second actuator is driven to move to the waiting position and then the telescopic mechanism is closed, and the door assembly is controlled to open the operating port.

[0080] After the rock specimen 600 completes the compression test, the telescopic mechanism 420 is activated, releasing the self-locking of the clamping mechanism 410. The telescopic mechanism 420 drives the second actuator 320 to move along the clamping column 430 away from the second box wall 220 to a waiting position. The telescopic mechanism 420 then closes, causing the clamping mechanism 410 to self-lock and limiting the movement of the second actuator 320 relative to the clamping column 430, making the two a unitary moving structure. Simultaneously, the second actuator 320 in the waiting position provides operating space for the door assembly to open the operating port of the second box wall 220. The door assembly is then controlled to open the operating port, making it easier for the user to operate the rock specimen 600 in the heating box 200.

[0081] Step 450: Remove the spacer in the holder opposite to the second box wall, take out the damaged rock specimen from the operating port, and re-execute the step of placing the rock specimen in the holder from the operating port.

[0082] By removing the spacer 520 in the holder 500 that is opposite to the second box wall 220, operating space is provided for removing the rock specimen 600, thereby facilitating the user to remove the damaged rock specimen 600 from the operating port, thereby completing the unloading operation of the rock specimen 600. It is understood that in this state, the second actuator 320 of the testing device is in the waiting position, and the door assembly opens the operating port of the heating box 200. Therefore, the step of placing the rock specimen 600 from the operating port into the holder 500 can be repeated to complete the installation of the rock specimen 600 again.

[0083] The true triaxial compression test method for rock provided in the embodiment of the present application can perform long-term stable loading tests on the rock specimen 600 under high temperature and high stress conditions, and can effectively reduce the time for replacing the rock specimen 600, and does not require moving the stress sensor, or reduces the frequency of moving the stress sensor, thereby effectively improving the experimental efficiency and the service life of parts, and is suitable for promotion and application.

[0084] In some possible embodiments provided in the present application, before the step of placing the rock specimen into the holder through the operating port, the method further includes: placing the rock specimen into a carrying shell.

[0085] In this way, it is possible to prevent the rock specimen 600 from fragments collapsing during the experiment, which would result in the inability to obtain an image of the complete rock specimen 600. It is possible to effectively ensure the integrity of the rock specimen 600 at high temperatures, and to prevent fragments from flying out and damaging various sensor circuits during the experiment, thereby improving the reliability of the device.

[0086] In some possible embodiments provided in this application, the steps of performing a compression test on a rock specimen specifically include:

[0087] The first actuator and the second actuator are subjected to displacement control to complete the clamping of the clamp so as to center and clamp the rock specimen;

[0088] controlling the operation of the heating device and the fan, and based on the detection information of the temperature sensor reaching a first preset value, controlling the first actuator and the second actuator to perform a loading operation, performing a stepped true triaxial loading on the rock specimen until the rock specimen is destroyed, controlling the first actuator, the second actuator, the heating device and the fan to stop operating, and recording data from the stress sensor;

[0089] Waiting for the rock specimen to cool down, and based on the temperature of the rock specimen cooling to a second preset value, the rock specimen completes the compression test.

[0090] In this embodiment, during the compression test on the rock specimen 600, the first actuator 310 and the second actuator 320 are first displacement-controlled to secure the clamp 500 and center the rock specimen 600, thereby improving the uniformity of the force applied to the rock specimen 600. The heating device 250 and the fan 240 are then controlled to heat the heating box 200. When the temperature sensor's detection information reaches a first preset value, indicating that the temperature within the heating box 200 has met the test temperature requirement, the first actuator 310 and the second actuator 320 are then activated to perform a loading operation. For example, the stress loading injection pumps of the five first actuators 310 and the loading injection pump of the second actuator 320 are activated to apply stepped true triaxial loading to the rock specimen 600 to simulate the stress environment of the rock specimen 600. Until rock specimen 600 fails, first actuator 310, second actuator 320, heating device 250, and fan 240 are controlled to stop operating, thereby stopping the heating and loading operations. Stress sensor data is recorded to facilitate further analysis and research of rock specimen 600 based on the recorded data. The rock specimen 600 is allowed to cool. When the temperature of rock specimen 600 cools to a second preset value, such as when the interior of rock specimen 600 cools to room temperature, the compression test on rock specimen 600 is complete. This allows the user to remove the tested rock specimen 600 without the risk of burns from high temperatures, thereby improving the safety of the testing device.

[0091] In the description of this application, the term "plurality" refers to two or more, unless otherwise expressly defined. The orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship described in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application; the terms "connect", "install", "fixed", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0092] In the description of this application, the terms "one embodiment," "some embodiments," "specific embodiments," etc., mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of this application. In this application, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in any one or more embodiments or examples.

[0093] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A rock true triaxial compression test device, characterized in that: include: Annular load-bearing frame; A heating box is arranged inside the annular load-bearing frame, the heating box including a first box wall, a second box wall and a door assembly that together form a box structure, the second box wall is provided with an operating port, the door assembly is connected to the second box wall to open or close the operating port, a first pressure head is provided on the first box wall, and a second pressure head is provided on the second box wall or the door assembly; an actuator assembly, comprising a first actuator corresponding to the first pressure head and a second actuator corresponding to the second pressure head, wherein a first end of the first actuator is connected to the annular load-bearing frame, and a second end of the first actuator is connected to the corresponding first pressure head; a holding and telescopic assembly, connecting the annular load-bearing frame and the second actuator, the holding and telescopic assembly being configured to drive the second actuator to approach the second box wall and abut against the second pressure head or to move away from the second box wall; The clamper is arranged inside the heating box, configured to clamp or release the rock specimen, and configured to contact the first pressing head and the second pressing head.

2. The rock true triaxial compression test device according to claim 1, characterized in that: The heating box is a hexahedral structure, and the second box wall is located on the left or right side of the heating box; The five first actuators are respectively arranged on the upper side, the lower side, the front side, the rear side, and the side opposite to the second box wall of the heating box.

3. The rock true triaxial compression test device according to claim 1, characterized in that: The holding and telescopic assembly comprises: A clamping mechanism, a telescopic mechanism, and a clamping column, wherein the clamping mechanism is connected to the second actuator, the first end of the telescopic mechanism is fixed to the annular load-bearing frame, the second end of the telescopic mechanism is connected to the clamping mechanism, the first end of the clamping column is fixed to the annular load-bearing frame, and the second actuator is provided through the clamping column; The clamping mechanism is configured to self-lock when the telescopic mechanism is closed to limit the relative movement of the second actuator and the clamping column, and to unlock when the telescopic mechanism is started.

4. The rock true triaxial compression test device according to claim 1, characterized in that: The clamp includes a pad and an elastic member, wherein the pad is arranged opposite to the first pressure head and the second pressure head, and the pad is connected through the elastic member to enclose a space for accommodating the rock specimen, wherein at least the pad opposite to the second box wall is configured to be detachably connected to the adjacent pad.

5. The rock true triaxial compression test device according to claim 4, characterized in that: The elastic member is configured to contact the rock sample so that a gap exists between the rock sample and the spacer in a non-gravity direction.

6. The rock true triaxial compression test device according to claim 4, characterized in that: Also includes: A fixing seat, the clamp is installed on the fixing seat, and the fixing seat is detachably connected to the heating box.

7. The rock true triaxial compression test device according to claim 1, characterized in that: A heating device is provided inside the heating box, and the heating device includes heating elements corresponding to and connected to the first box wall and the second box wall.

8. The rock true triaxial compression test device according to claim 1, characterized in that: The heating box is further provided with fans, the fans are arranged in pairs on both sides of the heating box, and the heating box is further provided with a temperature sensor; and / or, The wall of the heating box is a steel shell part embedded with heat-insulating material.

9. A true triaxial compression test method for rock, using the true triaxial compression test device for rock according to any one of claims 1 to 8, characterized in that: The method comprises: Based on the second actuator being in the waiting position, the door assembly opens the operating port of the heating box, places the rock specimen in the holder through the operating port, and fixes the spacer in the holder opposite to the second box wall; Controlling the door assembly to close the operating port, controlling the telescopic mechanism of the holding telescopic assembly to start, driving the second actuator to move to the test position, and then closing the telescopic mechanism; performing a compression test on the rock specimen; Based on the rock specimen completing the compression test, controlling the telescopic mechanism to start, driving the second actuator to move to the waiting position, and then closing the telescopic mechanism, and controlling the door assembly to open the operating port; The spacer block in the holder opposite to the second box wall is removed, the damaged rock specimen is taken out from the operating port, and the step of placing the rock specimen in the holder from the operating port is performed again.

10. A true triaxial compression test method for rock according to claim 9, characterized in that: Before the step of placing the rock specimen into the holder through the operating port, the method further comprises: placing the rock specimen into a bearing shell; The step of performing a compression test on the rock specimen specifically includes: Implementing displacement control on the first actuator and the second actuator to complete the fixation of the clamper so as to center and clamp the rock specimen; controlling the operation of the heating device and the fan, and based on detection information from the temperature sensor reaching a first preset value, controlling the first actuator and the second actuator to perform a loading operation, performing a stepped true triaxial loading on the rock specimen until the rock specimen is destroyed, controlling the first actuator, the second actuator, the heating device, and the fan to stop operating, and recording data from the stress sensor; Waiting for the rock specimen to cool down, and based on the temperature of the rock specimen cooling down to a second preset value, the rock specimen completes the compression test.

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