A rock tensile strength testing unit

Abstract

The present application belongs to the technical field of rock mechanics, and particularly relates to a rock tensile strength testing unit. The rock tensile strength testing unit comprises a confining pressure container, a pressurizing assembly movably and sealingly arranged in the confining pressure container in a vertical direction, an upper end of the pressurizing assembly extending out of the confining pressure container, a placement table for placing a rock core arranged in the confining pressure container, the placement table being located below the pressurizing assembly, a supporting assembly arranged between the placement table and the pressurizing assembly, in an initial state, upper and lower ends of the supporting assembly supporting the placement table and the pressurizing assembly respectively, so as to avoid the pressurizing assembly from pressing the rock core in advance, and in a confining pressure state, the supporting assembly is compressed and shrunk under pressure, so that the pressurizing assembly can press the rock core.

Description

Technical Field

[0001] This invention belongs to the field of rock mechanics technology, specifically, it relates to a rock tensile strength testing unit. Background Technology

[0002] In fields such as petroleum and natural gas rock mechanics and underground geotechnical engineering, the tensile strength of formation rocks is a crucial fundamental mechanical parameter, widely applied in wellbore stability analysis, fracturing optimization design, tunnel excavation, and rock blasting. There are two main methods for testing rock tensile strength: the direct tensile method and the Brazilian disc splitting method. Direct tensile testing is challenging for rocks with weak cementation or well-developed bedding, and the accuracy of the results cannot be effectively guaranteed. Currently, the Brazilian disc splitting method is the internationally accepted method for testing rock tensile strength.

[0003] Buried rocks are subjected to pressure from overlying strata, formation pore pressure, and tectonic stress, placing them in a state of multi-faceted compression. If the influence of confining pressure is not considered during rock tensile strength testing, the measurement results will not accurately reflect the true properties of the rock, leading to significant errors in the measured tensile strength and posing numerous risks when used to guide construction. Currently, many tensile strength testing devices are designed using the Brazilian disc splitting method theory, but most of these devices cannot simulate the confining pressure environment under formation conditions.

[0004] Some tensile strength testing devices can achieve confining pressure loading during experiments. Although these devices can relatively closely simulate the formation pressure environment, they all involve covering the core with a rubber ring or sleeve and applying confining pressure by compressing the rubber ring or sleeve with pressurized liquid. This design brings unavoidable defects and application limitations. Specifically, when the rubber ring or sleeve is used to compress cores of weakly cemented, fractured, and bedding-developed mudstone, shale, oil shale, coal, etc., the rubber will inevitably penetrate into the core along the fractures or bedding planes. Even a small rubber intrusion can cause stress concentration effects, which not only fails to achieve the simulation purpose of completely closing the fractures using confining pressure, but may also lead to premature core failure.

[0005] In summary, there is an urgent need to develop a rock tensile strength testing device that can simulate formation pressure environment and prevent premature core failure. Summary of the Invention

[0006] In view of the technical problems mentioned above, the present invention aims to provide a rock tensile strength testing unit that can simulate the formation environment pressure and avoid premature core damage.

[0007] According to the present invention, a rock tensile strength testing unit is provided, comprising:

[0008] Confining pressure vessel;

[0009] A pressurizing assembly is vertically movable and sealed within the confining pressure container, with its upper end extending out of the confining pressure container;

[0010] A core placement platform is disposed within the confining pressure vessel and is located below the pressurization assembly.

[0011] A support component disposed between the placement platform and the pressurization component;

[0012] In the initial state, the upper and lower ends of the support component support the placement platform and the pressurization component respectively, to prevent the pressurization component from prematurely squeezing the rock core;

[0013] Under confining pressure, the support assembly contracts under pressure, enabling the pressurizing assembly to compress the rock core.

[0014] In one specific embodiment, a mounting hole is provided vertically at the lower end of the pressurizing component, and the support component includes:

[0015] A piston that is vertically movable and sealed within the mounting hole;

[0016] A support rod is fixedly disposed at the lower end of the piston, the cross-section of the support rod being smaller than the cross-section of the piston; and

[0017] An elastic element, the two ends of which are respectively connected to the upper end face of the mounting hole and the upper end face of the piston.

[0018] In one specific embodiment, the pressurization component includes:

[0019] A pressure rod is vertically movable and sealed inside the confining pressure container, with its upper end extending out of the confining pressure container;

[0020] A pressure head is fixedly installed at the lower end of the pressure rod;

[0021] Under confined pressure, the pressurizing component is subjected to an upward force under the action of pressure difference.

[0022] In one specific embodiment, a baffle is fixedly installed on the pressure rod, and a sealing sheet is provided between the baffle and the upper end face of the inner cavity of the confining container.

[0023] In one specific embodiment, a first arc-shaped surface is provided at the lower end of the pressure head, and a second arc-shaped surface is provided at the upper end of the placement platform. The rock core is located between the first arc-shaped surface and the second arc-shaped surface, and the axis of the rock core is parallel to the axes of the first arc-shaped surface and the second arc-shaped surface.

[0024] In one specific embodiment, slits are provided on both the first arcuate surface and the second arcuate surface. The slits intersect the generatrix of the arcuate surface and laterally cross the contact surface between the core and the arcuate surface.

[0025] In one specific embodiment, the slit is configured as a star-shaped pattern.

[0026] In one specific embodiment, a force sensor is disposed inside the placement platform, and the upper end face of the force sensor coincides with the upper end face of the placement platform.

[0027] In one specific embodiment, the confining pressure vessel includes:

[0028] The cylinder is a cylindrical structure that is closed at the top and open at the bottom, and the pressurizing component is movably and sealed through the upper end of the cylinder.

[0029] The base is sealed and fixed to the lower end of the cylinder, and the placement platform is fixedly mounted on the base.

[0030] In one specific embodiment, an exhaust port is provided at the upper end of the cylinder, and a pressurization port is provided on the lower end side wall of the cylinder.

[0031] Compared with the prior art, the advantages of this application are as follows.

[0032] The present invention is equipped with a confining pressure container, and the rock core is located inside the confining pressure container. By pressurizing the inside of the confining pressure container, confining pressure is provided to the rock core, thereby simulating formation pressure. This can solve the problem that the existing technology of using a rubber confining pressure sleeve to pressurize the rock core may cause stress concentration effect.

[0033] The rock tensile strength testing unit provided by this invention is used in conjunction with hydraulic equipment. During the experiment, downward pressure is applied to the pressurizing component by the hydraulic equipment, which is simple to operate.

[0034] The upper end of the pressurization component of this invention is not fixedly connected to the hydraulic equipment, thus allowing for more flexible movement. It also facilitates the placement and removal of core samples.

[0035] Since the upper end of the pressurizing component of this invention is not fixedly connected to the hydraulic equipment, the pressurizing component will be affected by gravity and squeeze the rock core downwards. To prevent the pressurizing component from prematurely squeezing and damaging the rock core under gravity, this invention is equipped with a support component, which can support the pressurizing component in the initial state, thereby preventing the pressurizing component from contacting the rock core. Under confined pressure, that is, after pressurization into the confined pressure container, the support component retracts and no longer supports the pressurizing component, thereby avoiding interference when pressure is subsequently applied through the pressurizing component. At the same time, the pressurizing component will also be subjected to an upward force under the pressure difference. Only when the hydraulic equipment applies a downward force to the pressurizing component will the pressurizing component move downwards and squeeze the rock core. Attached Figure Description

[0036] The present invention will now be described with reference to the accompanying drawings.

[0037] Figure 1 A schematic diagram of one embodiment of the rock tensile strength testing unit according to the present invention is shown;

[0038] Figure 2 A schematic diagram of one embodiment of the pressurization assembly according to the present invention is shown;

[0039] Figure 3 A schematic diagram of one embodiment of the support component according to the present invention is shown;

[0040] Figure 4 A schematic diagram of one embodiment of the base according to the present invention is shown;

[0041] Figure 5 A schematic diagram of one embodiment of the force sensor according to the present invention is shown.

[0042] In the picture:

[0043] 1. Confining pressure vessel; 11. Cylinder; 111. Vent port; 112. Pressurization port; 113. First control valve; 114. Second control valve; 115. Pressure gauge; 116. Indicator; 117. Second seal; 118. Screw; 12. Base; 121. Lower base; 122. Upper base;

[0044] 2. Pressurizing assembly; 21. Pressurizing rod; 22. Pressurizing head; 221. First arc-shaped surface; 23. Baffle; 24. Sealing plate; 25. First sealing element;

[0045] 3. Placement platform; 31. Second arc-shaped surface; 32. Support hole;

[0046] 4. Support assembly; 41. Mounting hole; 42. Piston; 43. Support rod; 44. Elastic element;

[0047] 5. Slit; 6. Force sensor; 7. Rock core; 100. Rock tensile strength testing unit.

[0048] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0049] The invention will now be described with reference to the accompanying drawings.

[0050] It should be noted that the directional terms or qualifiers used in this application, such as "up," "down," "front," "back," "left," and "right," are all specific to the referenced material. Figure 1 In other words, they are not used to define the absolute position of the components involved, but can vary depending on the specific circumstances.

[0051] Figure 1 The structure of the rock tensile strength testing unit 100 according to the present invention is shown, as follows: Figure 1 As shown, the rock tensile strength testing unit 100 includes a confining pressure container 1, a pressurizing component 2, a placement platform 3, and a support component 4.

[0052] In this embodiment, the confining pressure container 1 is constructed as a cylindrical hollow cylinder, and the rock core 7 (cylindrical rock) is placed inside the confining pressure container 1. Confining pressure can be applied to the rock core 7 by pressurizing the confining pressure container 1.

[0053] The pressurizing assembly 2 is vertically movable and sealed within the confining pressure vessel 1, with its upper end extending out of the vessel 1. A hydraulic device (not shown) can be used to provide downward pressure to the pressurizing assembly 2.

[0054] The placement platform 3 is located inside the confining pressure container 1 at the bottom and is used to place the rock core 7. The placement platform 3 is located directly below the pressurizing component 2. After the pressurizing component 2 moves downward relative to the confining pressure container 1, it can approach the placement platform 3, thereby applying pressure to the rock core 7 on the placement platform 3, and thus testing the compressive strength of the rock.

[0055] The support component 4 is positioned between the placement platform 3 and the pressurizing component 2. Initially, the core 7 is located on the placement platform 3, and the confining pressure container 1 is not pressurized. Since the pressurizing component 2 and the confining pressure container 1 are connected by a movable connection, and the upper end of the pressurizing component 2 is not fixed, the pressurizing component 2 is subject to gravity. To prevent the pressurizing component 2 from prematurely compressing and damaging the core 7 due to gravity, the upper and lower ends of the support component 4 abut against the placement platform 3 and the pressurizing component 2 respectively, creating a certain height distance between them. This distance is greater than the diameter of the core 7, thus preventing the pressurizing component 2 from prematurely compressing and damaging the core 7 due to gravity. Under confining pressure, the pressure inside the confining pressure container 1 increases, and the support component 4 contracts under pressure, no longer supporting the placement platform 3 and the pressurizing component 2. This allows the pressurizing component 2 to press the core 7 downwards under the pressure of the hydraulic equipment, preventing the support component 4 from affecting the experimental data.

[0056] like Figure 1 and Figure 3 As shown, in one specific embodiment, the pressurizing assembly 2 includes a pressurizing rod 21 and a pressurizing head 22 disposed at the lower end of the pressurizing rod 21. A mounting hole 41 for mounting the support assembly 4 is provided vertically at the lower end of the pressurizing head 22. The mounting hole 41 is cylindrical and is a blind hole closed at the upper end. Multiple mounting holes 41 are evenly distributed at intervals along the circumference of the pressurizing head 22.

[0057] The support assembly 4 includes a piston 42, a support rod 43, and an elastic element 44. The piston 42 is generally cylindrical and is coaxially and sealingly disposed within the mounting hole 41 in a vertical direction. The support rod 43 is also generally cylindrical and is fixedly disposed at the lower end of the piston 42. The elastic element 44 is disposed within the mounting hole 41 and located above the piston 42. Both ends of the elastic element 44 are connected to the upper end face of the mounting hole 41 and the upper end face of the piston 42, respectively.

[0058] With this setup, in the initial state, the support rod 43 extends downward under the action of the elastic element 44, axially abutting against the placement platform 3. The elastic force of the elastic element 44 overcomes the gravity of the pressurizing assembly 2, thereby preventing the pressurizing assembly 2 from squeezing the core 7 on the placement platform 3 under the action of gravity. Under confined pressure, the pressure inside the confined pressure container 1 increases, and the pressure on the lower end face of the piston 42 and the support rod 43 is greater than the pressure on the upper end face of the piston 42. This pressure difference can overcome the elastic force of the elastic element 44. Therefore, the piston 42 and the support rod 43 move upward and retract into the pressurizing head 22. The lower end of the support rod 43 no longer abuts against the placement platform 3, avoiding the support assembly 4 from affecting the experimental data when the pressurizing assembly 2 applies pressure to the core 7.

[0059] In this embodiment, the cross-section of the support rod 43 is smaller than the cross-section of the piston 42.

[0060] In a preferred embodiment, the placement platform 3 is provided with a support hole 32 for accommodating the support rod 43. The support hole 32 is generally cylindrical in shape and is a blind hole closed at the lower end.

[0061] According to the present invention, in one specific embodiment, such as Figure 1 and Figure 2 As shown, the pressure rod 21 of the pressurizing assembly 2 is generally cylindrical in shape. The pressure rod 21 is movably inserted through the confining pressure container 1, meaning that the lower end of the pressure rod 21 is located inside the confining pressure container 1, and the upper end is located outside the confining pressure container 1. A first sealing element 25 is provided between the outer wall of the pressure rod 21 and the confining pressure container 1, thereby sealing the pressure rod 21 with the confining pressure container 1. The pressure head 22 is generally cubic in shape and is coaxially fixedly mounted at the lower end of the pressure rod 21.

[0062] Under confined pressure, the pressurizing component 2 experiences an upward force due to the pressure difference. In this embodiment, the cross-sectional dimension of the pressurizing head 22 is larger than that of the pressurizing rod 21. Under confined pressure, the pressure inside the confined pressure container 1 increases, and the pressure on the lower end face of the pressurizing head 22 is greater than the pressure on the upper end face of the pressurizing head 22. Therefore, the pressurizing component 2 experiences an upward force under the pressure difference, overcoming its own weight. With this configuration, even if the support component 4 contracts, the pressurizing component 2 will not press down on the core 7 under the action of gravity, thus preventing the pressurizing component 2 from prematurely pressing the core 7 during the confined pressure pressurization process.

[0063] Furthermore, a baffle 23 is fixedly mounted on the pressure rod 21, and a sealing sheet 24 is disposed between the baffle 23 and the upper end face of the inner cavity of the confining pressure container 1. In this embodiment, the baffle 23 is generally disc-shaped, coaxially fixed to the outer wall of the pressure rod 21, and located inside the confining pressure container 1. The diameter of the baffle 23 is larger than the diameter of the pressure rod 21. The sealing sheet 24 is generally annular, with an outer diameter larger than the outer diameter of the pressure rod 21, and is coaxially fixed to the upper end face of the inner cavity of the confining pressure container 1. Under confining pressure, the pressure rod 21 is subjected to pressure difference and moves upward, thereby driving the baffle 23 to move upward, thus causing the baffle 23 to axially abut against the sealing sheet 24, enhancing the sealing effect. At the same time, the baffle 23 can also limit the pressure rod 21, preventing the pressure rod 21 from moving upward too far.

[0064] According to one specific embodiment of the present invention, such as Figure 1 , Figures 3-5As shown, a first arc-shaped surface 221 is provided at the lower end of the pressure head 22, and a second arc-shaped surface 31 is provided at the upper end of the placement platform 3. The core 7 is located between the first arc-shaped surface 221 and the second arc-shaped surface 31, and the axis of the core 7 is parallel to the axes of the first arc-shaped surface 221 and the second arc-shaped surface 31. Preferably, the curvature radii of the first arc-shaped surface 221 and the second arc-shaped surface 31 are designed so that their contact width with the core 7 is less than one-sixth of the radius of the core 7. It should be noted that the width here refers to... Figure 4 The maximum distance in the left and right directions of the groove on the upper part of the middle placement platform 3.

[0065] To ensure that the first arc-shaped surface 221 and the second arc-shaped surface 31 maintain surface contact with the core 7 during the experiment, avoiding contact stress while allowing the core 7 to be fully subjected to confining pressure, this embodiment provides slits 5 on both the first arc-shaped surface 221 and the second arc-shaped surface 31. Specifically, the slits 5 can be grooves of a certain depth on the first arc-shaped surface 221 and the second arc-shaped surface 31. The slits 5 intersect with the generatrices of the arc-shaped surfaces 221 and 31, and the slits 5 laterally span the contact surfaces between the core 7 and the arc-shaped surfaces 221 and 31. In other words, the slits 5 can intersect or be perpendicular to the generatrices of the arc-shaped surfaces 221 and 31, as long as the confining pressure can be transmitted through the slits 5 to the contact surfaces between the core 7 and the arc-shaped surfaces 221 and 31, ensuring that the confining pressure can fully act on the entire circumference of the core 7.

[0066] In a preferred embodiment, such as Figure 5 As shown, the slit 5 is set in a star shape.

[0067] According to the present invention, a force sensor 6 for testing the loading pressure on the core 7 is provided inside the placement platform 3, and the upper end surface of the force sensor 6 coincides with the upper end surface of the placement platform 3. Specifically, as shown... Figure 4 As shown, a groove is provided in the middle of the placement platform 3. The bottom surface of this groove is the second arc-shaped surface 31. The core 7 is placed in this groove, with the axis of the core parallel to the axis of the second arc-shaped surface 31. A force sensor 6, used to test the applied pressure, is placed directly below this groove. The upper surface of the force sensor 6 is also an arc-shaped surface, and the curvature of the upper arc surface of the force sensor 6 is consistent with the curvature of the second arc-shaped surface 31. The upper arc surface of the force sensor 6 is in contact with the core 7. A slit 5 is provided on the upper arc surface of the force sensor 6 to communicate the confining pressure, ensuring that the contact surface of the core is also subjected to confining pressure.

[0068] In a preferred embodiment, the width of the groove on the placement platform 3 is set to 0.8 times the diameter of the core 7.

[0069] In a specific embodiment, such as Figure 1 As shown, the confining pressure container 1 includes a cylinder 11 and a base 12.

[0070] The cylinder 11 is a cylindrical structure with a closed upper end and an open lower end. The pressure rod 21 of the pressure assembly 2 is movable and sealed through the upper end of the cylinder 11.

[0071] The base 12 is sealed and fixed to the lower end of the cylinder 11, and the placement platform 3 is fixedly mounted on the base 12. Specifically, as shown... Figure 4 As shown, the base 12 includes a lower cylindrical base 121 and an upper cylindrical base 122 coaxially connected, wherein the diameter of the upper cylindrical base 122 is smaller than the diameter of the lower cylindrical base 121. The outer wall of the upper cylindrical base 122 is adapted to the inner wall of the cylindrical body 11. At least one second sealing element 117 is provided between the outer wall of the upper cylindrical base 122 and the inner wall of the cylindrical body 11. The lower end face of the cylindrical body 11 axially abuts against the upper end face of the lower cylindrical base 121, and the cylindrical body 11 and the lower cylindrical base 121 are fixedly connected by a plurality of axially evenly distributed screws 118.

[0072] An exhaust port 111 is provided at the upper end of the cylinder 11, and a first control valve 113 is connected to the exhaust port 111. A pressurization port 112 is provided on the lower end side wall of the cylinder 11, and a second control valve 114 is connected to the pressurization port 112. In this embodiment, the pressure inside the confining pressure container 1 is increased by injecting liquid into the pressurization port 112, thereby providing confining pressure for the core 7. The exhaust port 111 can be used to discharge gas inside the confining pressure container 1.

[0073] In a preferred embodiment, a pressure gauge 115 is connected to the pressure port 112, and a reading meter 116 is connected to the force sensor 6. The reading meter 116 can display the pressure measured by the force sensor 6 numerically. It is easy to understand that the specific structures of the pressure gauge 115, the force sensor 6, and the reading meter 116 are well known to those skilled in the art and will not be described in detail here.

[0074] According to the present invention, the method for testing the tensile strength of rock is as follows.

[0075] Select core sample 7 with a diameter of 25.4 mm or 38.1 mm. The ratio of the height to the diameter of core sample 7 should be 0.75 (i.e., the core height is 19.05 mm or 28.58 mm).

[0076] Remove the screws 118 used to fix the cylinder 11 and the base 12 to separate the cylinder 11 and the base 12. The cylinder 11 is made of high-pressure resistant alloy steel.

[0077] Wrap the core 7 with 2 to 3 layers of oil-proof film or tin foil. This will prevent the core 7 from splashing when it breaks under load and will also fix the core 7 well in the second arc-shaped surface 31 to prevent the core 7 from shifting.

[0078] Align the support rod 43 of the support assembly 4 with the support hole 32 of the placement platform 3, push the base 12 into the cylinder 11, and use screws 118 to fix the base 12 and the cylinder 11 together.

[0079] With the cylinder 11 placed vertically, the first control valve 113 and the second control valve 114 are opened, and an external pressure pump connected to the pressure port 112 begins to inject hydraulic oil into the cylinder 11. The hydraulic oil enters through the pressure port 112, and the air inside the cylinder 11 is discharged through the vent port 111.

[0080] When oil begins to flow from the vent 111, it indicates that the cylinder 11 is full of hydraulic oil. The first control valve 113 is closed, while the second control valve 114 remains open, and the pressure pump begins to apply confining pressure. During pressure application, the pressure assembly 2 moves upward under the pressure difference, and the baffle 23 deforms the sealing plate 24, achieving a sealing effect. Simultaneously, the support rod 43 of the support assembly 4 retracts into the pressure head 22.

[0081] Observe the pressure gauge 115 reading in real time. When the required confining pressure is reached, close the second control valve 114 to stop the confining pressure loading. Wait 5 minutes and observe whether the pressure gauge 115 reading changes. If there is no change, the seal is good, and the test continues. Otherwise, check each seal and start the test again.

[0082] The rock tensile strength testing unit 100, under confining pressure, is moved onto a universal hydraulic press. The press is started, and a pressure of 0.1kN to 0.5kN is applied to push the pressure rod 21 downward. The readings on the indicator 116 connected to the force sensor 6 are observed in real time. Once the pressure head 22 begins to contact the rock core 7, the universal hydraulic press is loaded at a rate of 0.03MPa / s to 0.05MPa / s until the rock core 7 is destroyed. When the reading on the indicator 116 connected to the force sensor 6 suddenly drops, it indicates that the rock core 7 has been destroyed. The maximum value displayed on the indicator 116 is the breaking load. The breaking load and the phenomena observed during the loading process are recorded.

[0083] Open the second control valve 114 and slowly unload the confining pressure using the pressurization pump until the pressure gauge 115 reading drops to 0. As the confining pressure decreases, the support rod 43 of the support assembly 4 will extend again to support the pressurization head 22, protect the core 7, and facilitate observation of the damage state after the core 7 is removed.

[0084] When the first control valve 113 is opened, air enters the cylinder 11 through the exhaust port 111, and hydraulic oil flows out through the pressurization port 112. The hydraulic oil is then recovered and returned.

[0085] Unscrew screw 118 and remove base 12 from cylinder 11 to observe the damage pattern of core 7. If base 12 is difficult to remove, a simple air pump can be used to inject a small amount of air pressure into cylinder 11 through exhaust port 111 or pressurization port 112 to slowly push base 12 out.

[0086] Finally, the tensile strength test unit 100 for cleaned rocks was completed, and the test was finished.

[0087] This invention discloses a rock tensile strength testing unit 100 suitable for shallow strata under low confining pressure. It can simulate a low to medium confining pressure environment of ≤50MPa and is suitable for tensile strength testing of rocks at a burial depth ≤2000m under confining pressure conditions. This invention features a reasonable design and simple structure, effectively avoiding secondary damage to the rock core caused by confining pressure loading. It can be placed on any universal hydraulic press for testing. Furthermore, this invention is simple to operate, has low testing costs, and high testing efficiency, meeting the needs of large-scale testing.

[0088] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0089] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0090] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0091] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rock tensile strength testing unit, characterized in that, include: Confining pressure vessel (1); A pressurizing assembly (2) is vertically movable and sealed inside the confining pressure container (1), with the upper end of the pressurizing assembly (2) extending out of the confining pressure container (1); A core placement platform (3) is provided inside the confining pressure container (1), the core placement platform (3) being located below the pressurization assembly (2); A support assembly (4) disposed between the placement platform (3) and the pressurizing assembly (2); In the initial state, the upper and lower ends of the support component (4) support the placement platform (3) and the pressurizing component (2) respectively, so as to prevent the pressurizing component (2) from squeezing the core. Under confining pressure, the support component (4) is compressed and shrinks, enabling the pressurizing component (2) to squeeze the core.

2. The rock tensile strength testing unit according to claim 1, characterized in that, A mounting hole (41) is provided vertically at the lower end of the pressurizing assembly (2), and the support assembly (4) includes: A piston (42) that is vertically movable and sealed within the mounting hole (41); A support rod (43) is fixedly disposed at the lower end of the piston (42), the cross-section of the support rod (43) being smaller than the cross-section of the piston (42); and An elastic element (44) is provided, with its two ends connected to the upper end face of the mounting hole (41) and the upper end face of the piston (42), respectively.

3. The rock tensile strength testing unit according to claim 1, characterized in that, The pressurization assembly (2) includes: A pressure rod (21) is vertically movable and sealed inside the confining pressure container (1), with the upper end of the pressure rod (21) extending out of the confining pressure container (1); A pressure head (22) is fixedly installed at the lower end of the pressure rod (21); Under confined pressure, the pressurizing component (2) is subjected to an upward force under the action of pressure difference.

4. The rock tensile strength testing unit according to claim 3, characterized in that, A baffle (23) is fixedly installed on the pressure rod (21), and a sealing sheet (24) is provided between the baffle (23) and the upper end face of the inner cavity of the confining container (1).

5. The rock tensile strength testing unit according to claim 3, characterized in that, A first arc-shaped surface (221) is provided at the lower end of the pressure head (22), and a second arc-shaped surface (31) is provided at the upper end of the placement platform (3). The rock core is located between the first arc-shaped surface (221) and the second arc-shaped surface (31), and the axis of the rock core is parallel to the axes of the first arc-shaped surface (221) and the second arc-shaped surface (31).

6. The rock tensile strength testing unit according to claim 5, characterized in that, Cuts (5) are provided on both the first arc-shaped surface (221) and the second arc-shaped surface (31). The cuts (5) intersect the generatrices of the arc-shaped surfaces (221, 31) and the cuts (5) laterally cross the contact surface between the core and the arc-shaped surface.

7. The rock tensile strength testing unit according to claim 6, characterized in that, The slit (5) is set in a star shape.

8. The rock tensile strength testing unit according to any one of claims 1 to 7, characterized in that, A force sensor (6) is provided inside the placement platform (3), and the upper end face of the force sensor (6) coincides with the upper end face of the placement platform (3).

9. The rock tensile strength testing unit according to any one of claims 1 to 7, characterized in that, The confining container (1) includes: The cylinder (11) is constructed as a cylindrical structure with a closed upper end and an open lower end. The pressurizing component (2) is movable and sealed through the upper end of the cylinder (11). The base (12) is sealed and fixed at the lower end of the cylinder (11), and the placement platform (3) is fixedly set on the base (12).

10. The rock tensile strength testing unit according to claim 9, characterized in that, An exhaust port (111) is provided at the upper end of the cylinder (11), and a pressurization port (112) is provided on the lower end side wall of the cylinder (11).

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