Triaxial continuous indentation test apparatus and method for applying bi-directional confining pressure

Abstract

This invention provides a triaxial continuous scratch test instrument and method for applying biaxial confining pressure. The instrument includes: a fixture with a test cavity for placing the rock sample to be tested, the fixture being used to position the boundary of the rock sample; a confining pressure loading module housed within the test cavity, used to apply horizontal transverse and horizontal longitudinal confining pressure loads to the rock sample; a scratching tip for vertically scratching the test surface of the rock sample; and a data calculation module for collecting scratch data and calculating the triaxial compressive strength of the rock sample based on the scratch data. This invention is not limited to standards set by the International Commission on Rock Mechanics (ICR) and can achieve triaxial compressive strength testing of various rock materials under different confining pressures, without damaging the rock sample, thus shortening the testing time while accurately measuring the triaxial compressive strength of the rock sample.

Description

Technical Field

[0001] This invention belongs to the field of petroleum and natural gas engineering technology, and particularly relates to a triaxial continuous scratch test instrument and method for applying bidirectional confining pressure. Background Technology

[0002] Accurate measurement and characterization of the characteristic parameters of rock materials provide crucial support for rock mechanics theory and engineering applications. Among these, rock strength is a key bridge for research on wellbore stability and hydraulic fracturing. With the development and progress of oil and gas exploration and development, the field of oil and gas drilling is gradually moving towards deeper and even ultra-deep formations. The establishment of experimental testing methods for rock strength parameters is an important guarantee for achieving safe, stable, and efficient development.

[0003] Currently, the main method for measuring rock strength parameters is the conventional compression test, which obtains strength parameters by testing multiple sets of rock samples until they undergo shear failure. However, the rock samples for compression tests must strictly adhere to the standards set by the International Commission on Rock Mechanics, resulting in stringent requirements for core preparation. Furthermore, compression tests are time-consuming and can lead to complete sample destruction after testing, making them destructive tests that cannot be repeated, thus resulting in low accuracy of the test data. Alternatively, direct shear tests can be used to directly measure rock strength parameters through destructive testing, but this method is susceptible to numerous interfering factors that are difficult to control effectively and cannot guarantee the integrity of the specimen structure. Summary of the Invention

[0004] The main objective of this invention is to propose a triaxial continuous scratch test instrument and method for applying biaxial confining pressure, aiming to solve the technical problems of low accuracy and long testing time in existing rock strength parameter testing methods.

[0005] To achieve the above objectives, the present invention provides a triaxial continuous scratch test instrument for applying bidirectional confining pressure, the triaxial continuous scratch test instrument for applying bidirectional confining pressure comprising:

[0006] The fixture is provided with a test cavity for placing the rock sample to be tested, and the fixture is used to locate the boundary of the rock sample to be tested;

[0007] A confining pressure loading module is housed within the test chamber. The confining pressure loading module is used to apply horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested.

[0008] A scratching tip is used to scratch the test surface of the rock sample to be tested in a vertical direction.

[0009] The data calculation module is used to collect the scratch data of the test scratch and calculate the triaxial compressive strength of the rock sample to be tested based on the scratch data.

[0010] In this embodiment of the invention, the confining pressure loading module includes:

[0011] The confining pressure mechanism is provided with a sealed confining pressure cavity. The two confining pressure mechanisms are orthogonally arranged to apply horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested, respectively.

[0012] The injection pump set is used to inject confining fluid into the two sealed confining chambers;

[0013] The pump control terminal is used to adjust the pumping pressure of the injection pump group according to the preset confining pressure value.

[0014] In this embodiment of the invention, the confining pressure mechanism includes:

[0015] A pressure plate is provided with a pressure groove on the side facing the cavity wall of the test chamber;

[0016] A confining block is sealed inside the confining groove and is sealed to the confining plate. The confining plate and the confining block form the sealed confining cavity. The confining plate has a confining channel. One end of the confining channel is connected to the injection pump group, and the other end is connected to the sealed confining cavity.

[0017] In this embodiment of the invention, a sealing groove is provided on the outer periphery of the confining block, and the confining mechanism further includes a sealing ring that is snapped into the sealing groove, the sealing ring being used to seal against the groove wall of the confining groove.

[0018] In this embodiment of the invention, the two confining pressure mechanisms are arranged corresponding to the two corners of the test cavity and form an orthogonal cavity. The triaxial continuous scratch test instrument for applying bidirectional confining pressure also includes a stabilizing block housed in the orthogonal cavity. The stabilizing block is used to abut and limit the two confining pressure mechanisms.

[0019] This invention also proposes a triaxial continuous scratch test method under biaxial confining pressure, applied to the aforementioned triaxial continuous scratch test instrument under biaxial confining pressure. The triaxial continuous scratch test method under biaxial confining pressure includes:

[0020] The rock sample to be tested is processed according to the test cavity of the fixture so that the rock sample to be tested and the test cavity are matched;

[0021] The rock sample to be tested is placed into the test chamber for preliminary positioning;

[0022] The scratching tip is calibrated to adjust its position.

[0023] The confining pressure loading module applies horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested, and the scratching tip scratches the test surface of the rock sample to be tested in the vertical direction.

[0024] The data calculation module collects the scratch data of the test scratch and calculates the triaxial compressive strength of the rock sample under test based on the scratch data.

[0025] In this embodiment of the invention, applying horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample under test using the confining pressure loading module includes:

[0026] The preset confining pressure value is input to the pump control terminal, so that the pump control terminal adjusts the injection pump group according to the preset confining pressure value.

[0027] The injection pump group injects confining fluid into the sealed confining chambers of the two confining pressure mechanisms, so that the two confining pressure mechanisms respectively apply horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested.

[0028] In this embodiment of the invention, the step of calibrating the scratching tip position includes:

[0029] The test surface is then subjected to trial cutting using a scratching tip to a predetermined scratch depth.

[0030] The contact area between the scratching tip and the test surface is made to reach a specified area value.

[0031] In this embodiment of the invention, before placing the rock sample to be tested into the test chamber for preliminary positioning, the method further includes:

[0032] The test surface of the rock sample to be tested is polished until the smoothness of the test surface reaches the preset smoothness.

[0033] In this embodiment of the invention, the triaxial compressive strength is calculated according to the following formula:

[0034]

[0035] Where E is the triaxial compressive strength, w is the width of the scratching tip, d is the scratch depth of the test scratch, and F s The tangential force exerted by the scratching tip on the test surface.

[0036] Through the above technical solution, the triaxial continuous scratch test instrument for applying bidirectional confining pressure provided in this embodiment of the invention has the following beneficial effects:

[0037] When testing rock strength parameters using a triaxial continuous scratch test instrument with bidirectional confining pressure, the instrument can be assembled first. The confining pressure loading module is installed in the test chamber of the fixture, and the scratching tip is positioned corresponding to the test chamber. After the instrument assembly is completed, the rock sample to be tested can be initially positioned using the fixture, and then placed into the test chamber. At this time, a clearance gap can be formed between the confining pressure loading module and the rock sample. Then, the angle and scratching depth of the scratching tip can be adjusted to ensure uniform contact between the scratching tip and the test surface. Next, the confining pressure loading module can simultaneously apply horizontal transverse confining pressure and horizontal longitudinal confining pressure to the rock sample, while the scratching tip scratches the test surface of the rock sample in the vertical direction. This achieves both boundary constraint and triaxial confining pressure, meeting the testing requirements for deep and even ultra-deep rock properties, and is an important guarantee for safe, stable, and efficient development. The data calculation module can collect the scratch data of the test scratches and quickly and accurately calculate the triaxial compressive strength of the rock sample based on the scratch data. The scratching tip can continuously scratch the test surface, replacing destructive testing methods in existing technologies, ensuring the integrity of the rock sample, and facilitating subsequent repeatable experiments. The triaxial continuous scratch test instrument with bidirectional confining pressure in this invention is not limited to the standards manufactured by the International Commission on Rock Mechanics. It can perform triaxial compressive strength testing on various rock materials under different confining pressures, supplementing and improving current rock mechanics parameter testing methods. It also provides accurate testing and description of rock strength under real physical conditions, while avoiding damage to the rock sample, shortening the testing time, and accurately measuring the triaxial compressive strength of the rock sample.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0039] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is a schematic diagram of the structure of a triaxial continuous scratch test instrument for applying bidirectional confining pressure according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the confining pressure loading module structure of a triaxial continuous scratch test instrument that applies bidirectional confining pressure according to an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the confining pressure loading module of a triaxial continuous scratch test instrument that applies bidirectional confining pressure according to another embodiment of the present invention;

[0043] Figure 4This is a schematic diagram of the confining pressure plate structure of a triaxial continuous scratch test instrument that applies bidirectional confining pressure according to an embodiment of the present invention;

[0044] Figure 5 Figure showing the test results of rock compressive strength under confining pressure.

[0045] Figure 6 Schematic diagram of the cutting force analysis principle of the scratch-marking tool tip.

[0046] Explanation of reference numerals in the attached figures

[0047] Detailed Implementation

[0048] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0049] The following description, with reference to the accompanying drawings, describes a triaxial continuous scratch test apparatus according to the present invention, which applies bidirectional confining pressure.

[0050] like Figures 1 to 3 As shown in the embodiment of the present invention, a triaxial continuous scratch test instrument 100 for applying bidirectional confining pressure includes a fixture 1, a confining pressure loading module 2, a scratching tip 4, and a data calculation module. The fixture 1 is provided with a test cavity 11 for placing the rock sample to be tested, and the fixture 1 is used to position the boundary of the rock sample to be tested. The confining pressure loading module 2 is housed in the test cavity 11 and is used to apply horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested. The scratching tip 4 is used to scratch test marks on the test surface of the rock sample to be tested in the vertical direction. The data calculation module is used to collect the scratch data of the test marks and calculate the triaxial compressive strength of the rock sample to be tested based on the scratch data.

[0051] Understandably, the fixture 1 in this embodiment can be a hollow cubic metal shell, with an opening on the upward-facing side of the test cavity 11. The bottom and sides are solid shells used for boundary fixation of the rock sample to be tested. The data calculation module can be a computer terminal, capable of collecting and recording scratch data, and can collect data through image scanning, image processing, etc. In this embodiment, the vertical direction is the up-down direction in the figure, the horizontal direction is the left-right direction, and the vertical direction is the front-back direction. The scratching tip 4 can be a scratching machine in the prior art. The scratching tip 4 is electrically connected to the data calculation module, enabling signal transmission and uploading the scratching parameters of the scratching tip 4 to the data calculation module.

[0052] When using the triaxial continuous scratch test instrument 100 with bidirectional confining pressure in this embodiment to test rock strength parameters, the instrument can be assembled first. The confining pressure loading module 2 is installed in the test cavity 11 of the fixture 1, and the scratching tip 4 is set in the test cavity 11. After the instrument assembly is completed, the rock sample to be tested can be initially positioned by the fixture 1 and placed into the test cavity 11. At this time, an avoidance gap can be formed between the confining pressure loading module 2 and the rock sample to be tested. Then, the angle and scratching depth of the scratching tip 4 can be adjusted so that the scratching tip 4 and the test surface are in uniform contact. Then, the horizontal transverse confining pressure load and the horizontal longitudinal confining pressure load can be applied to the rock sample to be tested simultaneously by the confining pressure loading module 2. At the same time, the scratching tip 4 is used to scratch the test surface of the rock sample to be tested in the vertical direction. This achieves the constraint boundary while also performing triaxial confining pressure, which can meet the testing of deep and even ultra-deep rock properties and is an important guarantee for achieving safe, stable and efficient development. The data calculation module can collect scratch data from the test scratches and quickly and accurately calculate the triaxial compressive strength of the rock sample under test based on the scratch data. The scratching tip 4 can continuously scratch the test surface, which can replace the destructive testing in the prior art, ensure the integrity of the rock sample under test, and facilitate subsequent repeated experiments. The triaxial continuous scratch test instrument 100 with bidirectional confining pressure applied in this embodiment is not limited to the standards of the International Commission on Rock Mechanics. It can realize the triaxial compressive strength test of various rock materials under different confining pressures, supplement and improve the current rock mechanics parameter testing methods, and provide accurate testing and description of rock strength under real physical conditions. At the same time, it can accurately test the triaxial compressive strength of the rock sample without destroying the rock sample, shortening the test time.

[0053] Specifically, the confining pressure loading module 2 includes a confining pressure mechanism 21, a liquid injection pump group, and a pump group control terminal. The confining pressure mechanism 21 is provided with a sealed confining pressure chamber. Two confining pressure mechanisms 21 are orthogonally arranged and used to apply horizontal transverse confining pressure loads and horizontal longitudinal confining pressure loads to the rock sample to be tested, respectively. The liquid injection pump group is used to inject confining pressure fluid into the two sealed confining pressure chambers. The pump group control terminal is used to adjust the pumping pressure of the liquid injection pump group according to the preset confining pressure value. The confining pressure fluid can be liquid water, utilizing the incompressible characteristic of liquid water to achieve accurate loading of confining pressure. One confining pressure mechanism 21 extends in the front-to-back direction, and the other confining pressure mechanism 21 extends in the left-to-right direction. In this embodiment, by inputting the preset confining pressure value to the pump group control terminal, the two confining pressure mechanisms 21 can achieve accurate horizontal transverse confining pressure and horizontal longitudinal confining pressure, ensuring the uniformity, stability, and safety of the confining pressure loading. In other embodiments, confining pressure can be applied to the rock sample to be tested by a combination of bolts, nuts, or even screws.

[0054] like Figure 2As shown, the confining pressure mechanism 21 includes a confining pressure plate 211 and a confining pressure block 212. The confining pressure plate 211 has a confining pressure groove 2111 on the side facing the cavity wall of the test chamber 11. The confining pressure block 212 is sealed inside the confining pressure groove 2111 and is sealed to the confining pressure plate 211. The confining pressure plate 211 and the confining pressure block 212 form a sealed confining pressure cavity. The confining pressure plate 211 has a confining pressure channel 2113. One end of the confining pressure channel 2113 is connected to the injection pump group, and the other end is connected to the sealed confining pressure cavity. In this embodiment, the confining pressure plate 211 can be a hollow cuboid metal shell. The side of the confining pressure plate 211 facing the rock sample to be tested can be provided with a guide slope 2112. Each outer periphery of the confining pressure plate 211 is provided with a guide slope 2112. The confining pressure channel 2113 can be connected to the injection pump group through a high-pressure pipeline. The pumping of high-energy liquid ensures that the liquid acts uniformly on the confining pressure plate 211, thereby realizing the loading of confining pressure. In this embodiment, the confining pressure channel 2113 is L-shaped with openings at both ends. One opening is located at the top of the confining pressure plate 211, and the other opening is located at the center of the bottom wall of the confining pressure groove 2111. The cross-section of the confining pressure groove 2111 can be a rounded rectangle. The shape and size of the confining pressure block 212 and the confining pressure groove 2111 are matched, and the outer surface of the confining pressure block 212 is flush with the outer edge of the confining pressure groove 2111. In this embodiment, the confining pressure plate 211 and the confining pressure block 212 are detachably and sealedly connected to form a sealed confining pressure cavity, which applies confining pressure to the rock sample to be tested. This facilitates the assembly of the confining pressure mechanism 21 while ensuring the ease with which the confining pressure mechanism 21 can be placed into the test cavity 11.

[0055] like Figure 3 and Figure 4 As shown, a sealing groove 2121 is formed on the outer periphery of the confining pressure block 212. The confining pressure mechanism 21 also includes a sealing ring 213 that is snapped into the sealing groove 2121. The sealing ring 213 is used to seal against the groove wall of the confining pressure groove 2111. In this embodiment, the sealing ring 213 can be a rubber ring. The sealing ring 213 and the sealing groove 2121 on the outer periphery of the confining pressure block 212 are intertwined and pushed into the confining pressure plate 211 to apply confining pressure to the rock sample under test during the process of the confining pressure liquid pushing the confining pressure plate 2111. In this embodiment, after the sealing ring 213 and the sealing groove 2121 are snapped together, the sealing ring 213 can be press-fitted against the groove wall of the confining pressure groove 2111 to achieve a sealed connection between the confining pressure block 212 and the confining pressure plate 211. The structure is simple and easy to assemble.

[0056] In one embodiment, two confining pressure mechanisms 21 are arranged at the two corners of the test cavity 11 to form an orthogonal cavity. The triaxial continuous scratch test instrument 100 for applying bidirectional confining pressure also includes a stabilizing block 3 housed in the orthogonal cavity. The stabilizing block 3 is used to abut and limit the two confining pressure mechanisms 21. In this embodiment, the stabilizing block 3 is a solid cube, and all four edges of the stabilizing block 3 are provided with smooth arcs. The stabilizing block 3 is vertically inserted into the orthogonal cavity between the two mutually orthogonal confining pressure mechanisms 21, which can maintain the internal stability of the test cavity 11 during the confining pressure loading process.

[0057] This invention also proposes a triaxial continuous scratch test method under biaxial confining pressure, applied to the aforementioned triaxial continuous scratch test instrument 100 under biaxial confining pressure. The triaxial continuous scratch test method under biaxial confining pressure includes:

[0058] The rock sample to be tested is processed according to the test chamber 11 of the fixture 1 to make the rock sample to be tested and the test chamber 11 match.

[0059] The rock sample to be tested is placed into test chamber 11 for preliminary positioning;

[0060] The position of the scratch-pointing tip 4 is calibrated.

[0061] The confining pressure loading module 2 applies horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested, and the scratching tip 4 scratches the test surface of the rock sample to be tested in the vertical direction.

[0062] The data calculation module is used to collect the scratch data of the test scratches, and the triaxial compressive strength of the rock sample to be tested is calculated based on the scratch data.

[0063] In this embodiment, the rock sample to be tested is cubic in shape, with an edge length between 5mm and 7mm, a smooth and flat surface, and an average protrusion of no more than 0.1mm. The material can be downhole core samples, outcrop rock samples, artificial rock samples, or samples cut from other materials. Different sizes of rock samples are matched with corresponding sizes of fixtures 1, stabilizing blocks 3, and confining pressure mechanisms 21. The confining pressure loading range is 0–50 MPa, which can simulate the geostress state and fracturing parameters of most unconventional reservoirs.

[0064] In this embodiment of the invention, applying horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample under test using the confining pressure loading module 2 includes:

[0065] Input a preset confining pressure value into the pump control terminal, so that the pump control terminal adjusts the injection pump group according to the preset confining pressure value;

[0066] The injection pump unit injects confining fluid into the sealed confining chambers of the two confining pressure mechanisms 21, so that the two confining pressure mechanisms 21 respectively apply horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested.

[0067] In this embodiment, the pumping pressure of the injection pump group is controlled by the pump group control terminal, so that the injection pump group can simultaneously inject confining pressure liquid into the two confining pressure mechanisms 21 to achieve the preset confining pressure value, thus ensuring the accuracy and continuity of the confining pressure.

[0068] In this embodiment of the invention, calibrating the position of the scratching tip 4 includes:

[0069] The test surface was tested by using a scratching tip 4 to a predetermined scratch depth.

[0070] Make the contact area between the scratching tip 4 and the test surface reach the specified area value.

[0071] In this embodiment, the position of the cutting head can be calibrated by trial cutting to ensure that the scratching tip 4 and the test surface are in uniform contact, thus avoiding the situation where the scratching tip 4 fails to scratch properly.

[0072] In this embodiment of the invention, before placing the rock sample to be tested into the test chamber 11 for preliminary positioning, the following steps are also included:

[0073] The test surface of the rock sample to be tested is polished until the smoothness of the test surface reaches the preset smoothness.

[0074] In this embodiment of the invention, the triaxial compressive strength is calculated according to the following formula:

[0075]

[0076] Where E is the triaxial compressive strength of the sample under test, w is the width of the scratching tip 4, which can be measured by the data calculation module, d is the scratch depth of the test scratch, which can be obtained by image scanning by the data calculation module, and F s The scratching tip 4 exerts a tangential force on the test surface. A force sensor and an angle sensor are installed on the scratching tip 4. The force sensor detects the scratching force F exerted by the scratching tip 4 on the test surface. The data calculation module calculates the tangential and normal forces based on the component forces of the scratching force F. θ is the back tilt angle of the scratching tip 4. The friction angle between the scratching tip 4 and the test surface. Both θ and θ can be obtained through an angle sensor, such as Figure 6 As shown. In this embodiment, the triaxial compressive strength of the rock sample under test can be accurately obtained through specific data calculation, thus realizing the quantification of rock strength parameters.

[0077] First, the rock sample to be tested can be prepared according to the requirements for making scratch test samples. The prepared rock sample to be tested is placed in the test chamber 11 and the test chamber 11 is located in the center of the fixture 1 to achieve stability. At this time, the rock sample to be tested can contact the confining pressure loading module 2. The injection pump group is connected to the confining pressure channel 2113 of the confining pressure plate 211 through the high pressure pipeline, and the remaining liquid and air contact area of ​​the triaxial continuous scratch test instrument 100 with bidirectional confining pressure is sealed.

[0078] Push the confining pressure mechanism 21 on both sides inward so that the confining pressure mechanism 21 makes even contact with the placed rock sample to be tested. High pressure liquid is pumped into the sealed confining pressure chamber through the high pressure pipeline to apply confining pressure load to the rock sample in the horizontal transverse and horizontal longitudinal directions.

[0079] Calibrate the position of the cutting tip and perform a trial cut with a predetermined scratch depth to ensure that the scratching cutting tip 4 is in uniform contact with the test surface.

[0080] Next, while applying confining pressure to the rock sample to be tested, test scratches are made at a specified scratching speed and a specified scratching depth;

[0081] The same scratch depth can be repeated twice to reduce testing error, and the average of the scratch data points (100 points) in every 10mm segment can be used as a data sample.

[0082] Based on the scratch data samples obtained from the test, the triaxial compressive strength parameters of the rock sample under confining pressure are calculated.

[0083] This embodiment enables accurate testing of triaxial compressive strength parameters of rock materials, providing a new method for indirect rock strength measurement and promoting the integrity of indoor test evaluation of rock mechanical parameters. The fixture 1 uses a closed boundary to constrain the deformation and movement of the rock sample under test, maximizing the stability of the sample during clamping and testing, and minimizing errors in the test results caused by overall misalignment of the rock sample.

[0084] In this embodiment, the rock sample to be tested is processed into a cube to ensure a proper fit with the fixture 1. The test surface of the rock sample needs to be polished smooth and flat. The processed rock sample is placed in the fixture 1, and the high-pressure pipeline pump is started to inject confining pressure fluid to apply a confining pressure load, ensuring uniform contact between the scratching tip 4 and the test surface. The scratching depth and scratching rate are set to reduce experimental errors caused by multiple variables. Continuous scratching of the rock sample under confining pressure is performed. The data calculation module card uses a computer terminal to record the experimental data. The collected scratch data is organized and the arithmetic mean is calculated. The triaxial compressive strength of the rock sample under confining pressure is calculated using a formula based on the average value. By using different pumping pressures, the calculated triaxial compressive strength values ​​of the rock sample under different confining pressure loading conditions can be obtained.

[0085] 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0086] 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 part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0087] In the description of this specification, the 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 present 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0088] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A triaxial continuous indentation test apparatus for applying a bidirectional confining pressure, characterized by, The triaxial continuous scratch test instrument (100) for applying bidirectional confining pressure comprises: a fixer (1) provided with a test cavity (11) for placing a rock sample to be tested, the fixer (1) being used for positioning the boundary of the rock sample to be tested; a confining pressure loading module (2) accommodated in the test cavity (11), the confining pressure loading module (2) being used for applying horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested; a scratch sharp tool bit (4) used for scratching a test scratch on a test surface of the rock sample to be tested in a vertical direction; a data calculation module used for collecting scratch data of the test scratch and calculating triaxial compressive strength of the rock sample to be tested according to the scratch data; the confining pressure loading module (2) comprises: a confining pressure mechanism (21) provided with a sealed confining pressure cavity, two confining pressure mechanisms (21) being arranged orthogonally to each other and used for respectively applying horizontal transverse confining pressure load and horizontal longitudinal confining pressure load to the rock sample to be tested; a liquid injection pump group used for injecting confining pressure liquid into the two sealed confining pressure cavities; a pump group control terminal used for adjusting pump injection pressure of the liquid injection pump group according to a preset confining pressure value; the triaxial compressive strength is calculated according to the following formula: wherein E is the triaxial compressive strength, is the width of the scratch tip (4), is the scratch depth of the test scratch, is the tangential force of the scratch tip (4) acting on the test surface.

2. The triaxial continuous indentation test apparatus for applying bidirectional confining pressure according to claim 1, wherein, the confining pressure mechanism (21) comprises: a confining pressure plate (211) provided with a confining pressure groove (2111) on a cavity wall side of the test cavity (11); a confining pressure block (212) blocked in the confining pressure groove (2111) and sealingly connected with the confining pressure plate (211), the confining pressure plate (211) and the confining pressure block (212) surrounding the sealed confining pressure cavity, the confining pressure plate (211) being provided with a confining pressure channel (2113), one end of the confining pressure channel (2113) being in communication with the liquid injection pump group, and the other end being in communication with the sealed confining pressure cavity.

3. The triaxial continuous indentation test apparatus for applying bidirectional confining pressure according to claim 2, characterized by, a sealing groove (2121) is formed on the outer periphery of the confining pressure block (212), the confining pressure mechanism (21) further comprises a sealing ring (213) clamped in the sealing groove (2121), and the sealing ring (213) is used for sealingly cooperating with the groove wall of the confining pressure groove (2111).

4. The triaxial continuous indentation test apparatus for applying bidirectional confining pressure according to any one of claims 1 to 3, characterized by, The two confining pressure mechanisms (21) are arranged corresponding to two corners of the test cavity (11) and surround an orthogonal cavity, and the triaxial continuous scratch test instrument (100) for applying bidirectional confining pressure further comprises a stabilizing block (3) accommodated in the orthogonal cavity, the stabilizing block (3) being used for abutting and limiting the two confining pressure mechanisms (21).

5. A triaxial continuous indentation test method for applying a bi-directional confining pressure, characterized by, The triaxial continuous scratch test method applied to the triaxial continuous scratch test instrument (100) for applying bidirectional confining pressure of any one of claims 1 to 4 comprises: processing the rock sample to be tested according to the test cavity (11) of the fixer (1), so that the rock sample to be tested matches the test cavity (11); placing the rock sample to be tested into the test cavity (11) for preliminary positioning; performing tool bit position calibration on the scratch sharp tool bit (4); The lateral horizontal confining pressure and the longitudinal horizontal confining pressure are applied to the rock sample to be tested by the confining pressure loading module (2), and the test surface of the rock sample to be tested is marked by the scratch sharp cutter head (4) in the vertical direction; The data calculation module is used to collect the scratch data of the test scratch, and the triaxial compressive strength of the rock sample to be tested is calculated according to the scratch data; The confining pressure loading module (2) is used to apply the lateral horizontal confining pressure and the longitudinal horizontal confining pressure to the rock sample to be tested, and the test surface of the rock sample to be tested is marked by the scratch sharp cutter head (4) in the vertical direction; The pump group control terminal is inputted with the preset confining pressure value, so that the pump group control terminal adjusts the liquid injection pump group according to the preset confining pressure value; The liquid injection pump group injects confining pressure liquid into the sealed confining pressure cavity of the two confining pressure mechanisms (21), so that the two confining pressure mechanisms (21) respectively apply the lateral horizontal confining pressure and the longitudinal horizontal confining pressure to the rock sample to be tested; The triaxial compressive strength is calculated according to the following formula: wherein E is the triaxial compressive strength, is the width of the scratch tip (4), is the scratch depth of the test scratch, is the tangential force of the scratch tip (4) acting on the test surface.

6. The triaxial continuous indentation test method of applying a biaxial confining pressure of claim 5, wherein, The cutter head position calibration of the scratch sharp cutter head (4) includes: The test surface is trial cut by the scratch sharp cutter head (4) with a predetermined scratch depth; The contact area value of the scratch sharp cutter head (4) and the test surface reaches a specified area value.

7. The triaxial continuous indentation test method of applying a biaxial confining pressure according to any one of claims 5 to 6, wherein Before the rock sample to be tested is placed in the test cavity (11) for preliminary positioning, it further includes: The test surface of the rock sample to be tested is surface polished until the smoothness of the test surface reaches a preset smoothness.

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