A method and apparatus for preparing rock test samples

Abstract

This invention discloses a method and apparatus for preparing rock test samples. The method includes: pre-setting a sampling area; opening a first cutting groove in rock mass area A; inserting a drilling device into the first cutting groove; and opening a back groove in the drilling device perpendicular to the first cutting groove. During the back groove opening process, the drilling device, through reciprocating vibration of the cutting head, causes the saw blade, in conjunction with a spring, to grind out part of the space in the back groove. Driving a piston movement causes the liquid in the saw chamber to apply thrust to the saw blade until the saw blade grinds the rock mass in area A until its back side is separated from the original rock mass. In this invention, by opening the first cutting groove in rock mass area A and then cutting the back groove, the back side of rock mass area A is separated from the original rock mass, while rock mass area B remains integrated with the original rock mass. This allows for in-situ sample preparation of the rock mass, facilitating in-situ testing of the shear resistance of rock faults, avoiding disturbance to the sample caused by transportation and laboratory environmental differences, and improving the accuracy of the test results.

Description

Technical Field

[0001] This invention relates to the field of rock mass testing technology, and in particular to a method and apparatus for preparing rock test samples. Background Technology

[0002] Assessing the horizontal bearing capacity of the entire rock mass is crucial for many geological and civil engineering projects, particularly those involving infrastructure construction, mining, underground engineering, and geotechnical engineering. It not only helps ensure foundation stability but also predicts and prevents uneven settlement and deformation of building or other structure foundations. In underground engineering such as mining and tunnel excavation, the horizontal bearing capacity of the rock mass directly affects operational safety. Low rock mass bearing capacity can lead to collapse or subsidence in the underground excavation area. Therefore, accurately assessing the bearing capacity of the rock mass is key to designing a reasonable mining plan and determining the mining depth and extent.

[0003] To assess the horizontal bearing capacity of the entire rock mass, it is necessary to understand the shear properties of major faults within the rock mass, such as the internal friction angle φ and cohesion c. Currently, the common practice for studying shear properties is to sample the faults within the rock mass and then test the samples. During sampling, a core sample is drilled using a cutting machine, and the test sample is then taken back to the laboratory for shear testing using a specialized shear apparatus. However, the shear strength of faults is inherently low, several orders of magnitude lower than that of the rock itself. Furthermore, the core drilling process and sample transportation can disturb the fault structure, thus increasing experimental errors. Summary of the Invention

[0004] This invention provides a method and apparatus for preparing rock test samples, which can solve the problem of large test errors mentioned in the background art.

[0005] A method for preparing a rock test sample, comprising:

[0006] A sampling area is pre-defined, which is traversed by a fault fracture, forming rock mass area A and rock mass area B;

[0007] A first cutting groove is opened in the rock mass of area A, and a drilling device is installed in the first cutting groove. The drilling device has a back groove opened in a direction perpendicular to the first cutting groove.

[0008] During the process of creating the back groove, the drilling device uses a reciprocating vibrating cutting head to make the saw blade work with the spring to grind out part of the space of the back groove, and drives the piston to move so that the liquid in the saw chamber applies a thrust to the saw blade until the saw blade grinds the rock mass in area A to its back side and separates it from the original rock mass.

[0009] Preferably, the depth of the back groove is not less than the maximum distance between the first cutting groove and the fault crack.

[0010] Preferably, after the back groove is opened, a second cutting groove and a third cutting groove are opened downwards at the left and right ends of the first cutting groove, respectively, so that the rock mass in area A is separated from the original rock mass.

[0011] Preferably, when the fault crack is horizontal or the angle between it and the horizontal plane is no more than 30°, the order in which the second cutting groove and the third cutting groove are opened can be interchanged.

[0012] Preferably, when the fault crack is vertical or has an angle greater than 30° with the horizontal plane, the second cutting groove is opened first, followed by the third cutting groove.

[0013] Preferably, before opening the third cutting groove, a filler is placed in the second cutting groove to support the rock mass in area A.

[0014] A rock test sample preparation apparatus, applicable to a method for preparing rock test samples, comprising: a drilling device;

[0015] The drilling device includes: a saw chamber, and a plurality of retractable sleeves are provided at the lower end face of the closed side of the saw chamber, and saw blades are provided at the retractable ends of the sleeves;

[0016] A piston is installed inside the saw chamber, and the piston squeezes the liquid inside the saw chamber to drive the extension and retraction of the sleeve.

[0017] Preferably, the saw chamber is provided with a cavity, and the piston is located within the cavity.

[0018] Preferably, the piston is connected to a plurality of slide rods, the slide rods are connected to a drive rod, and the drive rod is connected to an external cylinder.

[0019] Preferably, a plurality of springs are provided inside the cavity, and each spring corresponds to a sleeve.

[0020] The beneficial effects of this invention are:

[0021] (1) In this invention, a first cutting groove is first opened in the rock mass of area A, and the drilling device is placed in the first cutting groove. A back groove perpendicular to the first cutting groove is cut by the cutting head, so that the rock mass of area A is ground to the point that its back is separated from the original rock mass. The rock mass of area B remains in the same state as the original rock mass. The rock mass can be prepared in situ, which facilitates the in situ testing of the shear resistance of the rock mass fault, avoids the disturbance of the sample caused by the environmental differences in transportation and laboratory, and improves the accuracy of the test results.

[0022] (2) In this invention, the spring force is used to drive the saw blade to grind out the initial depth of the back groove, and then the piston squeezes the liquid in the saw chamber. The liquid pushes the saw blade to continue grinding the back groove based on the squeezing action and its own incompressible property. The entire back groove can be operated based on the space of the first cutting groove, so that the sample of the required size can be prepared on a small operating surface, which greatly reduces the limitation of the operating surface. The prepared sample is less affected by the size effect, and the influence caused by disturbance during the sample preparation process is also smaller, so that the subsequent test results are more accurate. Attached Figure Description

[0023] Figure 1 A schematic diagram of a rock mass fault;

[0024] Figure 2 This is a schematic diagram of the structure of a test sample taken from a fault in a rock mass.

[0025] Figure 3 A flowchart illustrating a method for preparing a rock test sample provided by the present invention;

[0026] Figure 4 A simulated line drawing of a fault in a rock mass;

[0027] Figure 5 A schematic diagram of a rock mass with a first cutting groove in a fault, which is provided by the present invention for preparing a rock test sample;

[0028] Figure 6 A cross-section of the rock mass into which a back groove is to be opened on the basis of the first cutting groove to create a fault in the rock mass;

[0029] Figure 7 A schematic diagram of a rock mass into which a second cutting groove is to be opened in the fault of the rock mass based on the back groove;

[0030] Figure 8 A schematic diagram of a rock mass into which a third cutting groove is to be opened on the basis of the second cutting groove to create a fault in the rock mass;

[0031] Figure 9 for Figure 8 Rock mass profile in the middle;

[0032] Figure 10 This is a schematic diagram of a drill bit;

[0033] Figure 11 This is a top view of the drilling equipment;

[0034] Figure 12 A bottom view of the drilling rig Figure 1 ;

[0035] Figure 13 This is an exploded view of the drilling equipment;

[0036] Figure 14 This is a schematic diagram of the cutting head structure;

[0037] Figure 15 for Figure 14 Schematic diagram of the middle sleeve in its extended state;

[0038] Figure 16 A bottom view of the drilling rig Figure 2 .

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. First cutting groove; 2. Back groove; 3. Second cutting groove; 4. Third cutting groove; 5. Frame; 501. Connecting end face; 6. Cooling pipe; 7. Saw teeth; 8. Saw chamber; 801. Cavity; 9. Piston; 10. Slide rod; 11. Drive rod; 12. Cutting head; 121. Spring; 122. Sleeve; 123. Saw blade. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0042] For rock test samples, the transportation process from the rock mass to the laboratory can cause mechanical vibrations to the fault due to vehicle bumps, shocks, and collisions. This can lead to minor displacement or structural changes in the fault plane, especially for fragile faults, where the transportation process can easily alter their original shear strength. Furthermore, because the laboratory or transportation environment differs from the natural environment of the rock mass, samples may be subjected to different pressure conditions or temperature variations. These disturbances can alter parameters directly affecting shear strength, such as the moisture content and porosity of the rock and fault. Therefore, the preferred method for those skilled in the art is to prepare samples in situ from the rock mass and then test the shear strength of the fault in the samples on-site to avoid these disturbances.

[0043] like Figures 1-2 As shown, the inventors discovered that when preparing samples in situ on a rock mass, a sampling area of ​​the required size is usually demarcated at the fault, and then the sample outline is cut into the rock mass along the edge of the sampling area using a cutting machine. The cutting machine then cuts the back side of the sample ( Figure 2The sample (shaded area in the image) is separated from the parent rock mass, and the cut sample is then removed for on-site shear testing. However, cutting the back of the sample with a conventional cutting machine requires a very large working surface, which is often unacceptable in the field. The larger the sample size, the larger the working surface. Theoretically, the larger the sample size, the less it is affected by size effects (smaller samples have uneven stress distribution, surface and edge effects, pore pressure, and hydraulic effects, which affect the accuracy and reliability of subsequent test results). The impact of disturbance during sample preparation is also smaller, thus better reflecting the true condition of the fault. However, the sampling environment that simultaneously meets the requirements for sample size and working surface is quite demanding. Therefore, even if a large working surface exists at the sampling site, it is difficult to actually cut a sample that meets the large size requirements.

[0044] like Figure 3 As shown, the present invention provides a method for preparing a rock test sample, comprising:

[0045] S1, such as Figure 4 As shown, a sampling area is pre-defined, which is traversed by a fault fracture, forming rock masses in areas A and B. Area A is the sampling area rock mass on one side of the fault, and area B is the sampling area rock mass on the other side of the fault. The size of the sampling area can be planned according to the actual testing needs.

[0046] The shape of the sampling area is not limited, but a rectangle is preferred. Rectangular samples are easy to cut, it is easy to ensure a flat surface, and it is convenient to apply external force during subsequent testing.

[0047] S2, such as Figure 5 , Figure 10 As shown, the first cutting groove 1 was opened in the rock mass of area A using a drilling rig. This opening method is a conventional technique and can be achieved using a conventional drilling rig. The inventor provides a brief explanation of this method below.

[0048] When creating the first cutting groove 1, the electric motor on the conventional drilling rig drives the frame 5 to vibrate reciprocally with an amplitude of 8mm. The reciprocating motion of the saw teeth 7 grinds a deep groove in the rock mass of area A, which is the first cutting groove 1. The groove width depends on the width of the saw teeth 7, and the verticality of the first cutting groove 1 can be controlled by the guide rod on the drilling rig. During this process, the cooling pipe 6 is connected to an external water source and sprays cooling water onto the saw teeth 7 to remove the heat generated by the saw teeth 7 during cutting.

[0049] S3, such as Figure 6 , Figures 11-15 As shown, a drilling device is installed inside the first cutting groove 1, and the drilling device has a back groove 2 in a direction perpendicular to the first cutting groove 1.

[0050] In this embodiment, during the process of creating the back groove 2, the drilling device uses the reciprocating vibration of the cutting head 12 to grind out space with the saw blade 123. The spring 121 is gradually released, thereby pushing the sleeve 122 connected to the saw blade 123 to extend, allowing the saw blade 123 to further grind out a portion of the space in the back groove 2. After the saw blade 123, in conjunction with the spring 121, grinds out a portion of the space in the back groove 2, the thrust of the spring 121 gradually decreases as it is gradually released, until the thrust is insufficient to allow the sleeve 122 to continue extending. At this point, the multiple inner cylinders of the sleeve 122 are not completely pushed out, meaning the saw blade 123 is not completely pushed out, resulting in the groove depth of the back groove 2 not reaching the required depth.

[0051] Therefore, the inventor uses an external cylinder to drive the drive rod 11 towards the cutting head 12. The drive rod 11 drives the slide rod 10, which in turn drives the piston 9. The piston 9 compresses the liquid in the saw chamber 8. Utilizing the incompressibility of the liquid, the liquid in the saw chamber 8 applies a thrust to the saw blade 123. The sleeve 122 also gradually extends and provides space for the liquid. Under the thrust, the saw blade 123 continues to grind the rock until the rock mass in area A is ground to the point where its back side is separated from the original rock mass, and the back groove 2 is completed.

[0052] It should be noted that the depth of the back groove 2 is not less than the maximum distance between the first cutting groove 1 and the fault fracture, that is, the deepest part of the back groove 2 can extend into the rock mass of area B below the fault fracture.

[0053] In addition, during the process of opening the back groove 2, cooling water can be introduced into the first cutting groove 1. The water pressure of the cooling water will flush out the polished debris and further cool the saw blade 123.

[0054] S4, such as Figures 7-8 As shown, after opening the back groove 2, the drilling rig is used to open the second cutting groove 3 and the third cutting groove 4 downwards at the left and right ends of the first cutting groove 1, respectively. The deepest part of the second cutting groove 3 and the third cutting groove 4 needs to extend to the rock mass in area B below the fault fracture, so as to separate the rock mass in area A from the original rock mass.

[0055] Although the fault fractures divided the sample into rock masses in area A and area B, the rock masses in area A and area B are still connected due to intermolecular forces. Under normal circumstances, the rock mass in area A will not fall off due to separation from the original rock mass.

[0056] When the fault fracture is horizontal or the angle between it and the horizontal plane is no more than 30°, the order in which the second cutting groove 3 and the third cutting groove 4 are opened can be interchanged.

[0057] When the fault fracture is vertical or at an angle greater than 30° to the horizontal plane, the second cutting groove 3 is opened first, followed by the third cutting groove 4. Before opening the third cutting groove 4, a filler is placed in the second cutting groove 3 to support the rock mass in area A. Typically, a sponge is used as the filler. The sponge filling the second cutting groove 3 applies a thrust to the rock mass in area A based on its elasticity, achieving a supporting effect and preventing the sample from shifting or falling off due to its own weight during the cutting of the third cutting groove 4.

[0058] The angles mentioned above are all calculated clockwise from the fault fracture to the horizontal plane. If the angle between the fault fracture and the horizontal plane in the clockwise direction is greater than 90°, then the angle needs to be calculated counterclockwise. When calculating the angle counterclockwise, the opening positions of the second cutting groove 3 and the third cutting groove 4 are interchanged, that is, to ensure that the depth of the second cutting groove 3 above the fault fracture is greater than the depth of the third cutting groove 4 above the fault fracture.

[0059] like Figure 2 As shown, in existing technologies, when conducting shear tests on samples in the laboratory, the sample needs to be placed in a shear apparatus, and area B (or area A) needs to be fixed, ensuring that the fracture surface of the sample is perpendicular to the direction of the applied shear force, or as close as possible to the actual shear surface. An appropriate normal force σ (pressure perpendicular to the fracture surface) is applied to the unfixed area of ​​the rock sample. For example, after area B is fixed, a normal force is applied to area A, and vice versa. Generally, the normal force is used to simulate the natural state of rock under underground pressure. While keeping the normal force constant, a shear force τ parallel to the fracture surface is gradually applied to the rock surface in the same area. The shear force acts along the rock fracture surface, simulating the shearing process of rock under natural conditions. As the shear force increases, the rock sample deforms until the fracture surface slips or fails, i.e., the rock mass in area A and area B experiences relative displacement. When the rock sample fails or slips, the specific values ​​of the shear force and normal force are recorded. Based on the experimental data, a Mohr's circle or a shear force-normal force relationship diagram is plotted. These graphs allow for the estimation of rock shear strength parameters, particularly cohesion (c) and internal friction angle (φ). The cohesion and internal friction angle of the rock sample are calculated using the Mohr-Coulomb failure criterion. These two parameters describe the shear strength characteristics of the rock and can provide a basis for engineering design.

[0060] The formulas for calculating the cohesion and internal friction angle of a rock sample are: τ = c + σtanφ

[0061] In the formula:

[0062] τ is the shear force;

[0063] σ is the normal force;

[0064] c represents cohesion;

[0065] φ is the internal friction angle.

[0066] like Figure 9 As shown in this application, the first cutting groove 1 provides the operating space for applying a normal force σ to the rock mass in area A. If the space is insufficient, the groove space can be further expanded by drilling. Then, a shear force is applied to the rock mass in area A in a direction parallel to the fault plane. The back groove 2 provides sliding space for the rock mass in area A. When the rock mass in area A and the rock mass in area B undergo relative displacement, the specific values ​​of the shear force and normal force are recorded. Based on the experimental data, the cohesion and internal friction angle of the rock sample can be obtained, thereby understanding the shear resistance of the fault in the rock mass and evaluating the horizontal bearing capacity of the entire rock mass.

[0067] The method described in this application allows for in-situ sample preparation of rock masses, facilitating in-situ testing of the shear resistance of rock faults. This ensures that the testing environment of the rock samples is identical to the actual environment, avoiding disturbance to the samples caused by differences in transportation and laboratory environments, and improving the accuracy of the test.

[0068] This method eliminates the need to separate the rock sample from the rock mass during sample preparation, allowing the rock mass in area B to remain integrated with the original rock mass. The rock mass itself acts as a natural fixing device to secure the rock mass in area B. During testing, force can be applied directly to the rock mass in area A, avoiding the mechanical vibration and positioning errors caused by external fixing devices that could affect the accuracy of the test results.

[0069] First, a first cutting groove 1 is opened in the rock mass of area A. The drilling device is placed in the first cutting groove 1, and a back groove 2 perpendicular to the first cutting groove 1 is cut by the cutting head 12. The elastic force of the spring 121 drives the saw blade 123 to grind the back groove 2 to its initial depth. Then, the piston 9 squeezes the liquid in the saw chamber 8. The liquid, based on the squeezing action and its own incompressible property, pushes the saw blade 123 to continue grinding the back groove 2. The entire back groove 2 can be operated within the space of the first cutting groove 1, realizing the preparation of samples of the required size on a relatively small operating surface. Therefore, compared with the existing technology, the entire sample preparation process significantly reduces the limitation of the operating surface, the prepared sample is less affected by size effects, and the influence of disturbance during sample preparation is also smaller, thus making the subsequent test results more accurate and reflecting the true situation of the fault.

[0070] In one embodiment, the present invention provides an apparatus for preparing rock test samples, applicable to a method for preparing rock test samples. The apparatus includes a drilling rig and a drilling device.

[0071] like Figure 10As shown, a conventional drill bit can be used for the grinding end of the drilling rig. A conventional drill bit will have a frame 5, which is a hollow, thin-walled structure with several diamond saw teeth 7 at one end. The end face of the frame 5 away from the saw teeth 7 is the connecting end face 501, used to connect the motor. The frame 5 is also connected to several cooling pipes 6, which are connected to an external water source. These pipes spray cooling water through the frame 5 onto the saw teeth 7, carrying away the heat generated during cutting and using the force of the cooling water to flush out cutting debris.

[0072] In some embodiments, the cooling pipe 6 is not connected to the frame 5. When the first cutting groove 1, the second cutting groove 3, and the third cutting groove 4 are opened, the water outlet of the external cooling pipe 6 is directly directed toward the saw teeth 7. The cooling water cools the saw teeth 7 while also discharging grinding debris in a timely manner. This split-type cooling pipe 6 can reduce the manufacturing difficulty of the drilling rig.

[0073] like Figures 11-15 As shown, the drilling device includes: a saw chamber 8, which has a cavity 801 containing liquid, including but not limited to water and hydraulic oil. Several cutting heads 12 are provided on the lower end face of the closed side of the saw chamber 8. Each cutting head 12 includes a retractable sleeve 122, and a saw blade 123 is provided at the retractable end of the sleeve 122.

[0074] Specifically, each sleeve 122 consists of an outer sleeve fixed to the saw chamber 8 and several inner sleeves nested together. The inner sleeves gradually decrease in diameter from the outside to the inside, allowing them to nest and engage with each other. Sealing rings are installed between adjacent sleeves to further improve the overall sealing of the sleeve 122. Both the outer and inner sleeves are annular, and the innermost inner sleeve is fixedly fitted with a saw blade 123, which seals the telescopic ends of the sleeve 122. The number and length of the sleeve 122 sections are adjusted according to actual needs. For example, if the minimum depth of the back groove 2 in the currently excavated sample size is 125mm, then the fully extended length of the sleeve 122 is 130mm, which is greater than the minimum depth of the current back groove 2, and thus it can be used. If samples of other sizes need to be excavated, the sleeve 122 needs to be adjusted accordingly.

[0075] Several springs 121 are installed inside the cavity 801, and each spring 121 corresponds to a sleeve 122. One end of the spring 121 is fixed to the saw chamber 8, and the other end is fixed to the innermost inner cylinder of the sleeve 122, so that the spring 121 can drive the innermost inner cylinder to extend during the extension process, so that the saw blade 123 can grind deeper.

[0076] A piston 9 is installed in the cavity 801 inside the saw chamber 8. The piston 9 squeezes the liquid inside the saw chamber 8 to drive the extension and retraction of the sleeve 122. The space between the piston 9, the cavity 801 and the sleeve 122 is closed, preventing the liquid inside the saw chamber 8 from flowing out.

[0077] The piston 9 is connected to several slide rods 10, the slide rods 10 are connected to drive rods 11, and the drive rods 11 are connected to an external cylinder. The external cylinder can drive the drive rods 11 and slide rods 10 to move toward the sleeve 122, so that the piston 9 squeezes the liquid in the cavity 801.

[0078] In this embodiment, the back groove 2 can be ground out using a drilling device. The drilling device reciprocates the cutting head 12, and the saw blade 123 grinds downwards from the first cutting groove 1, gradually releasing the spring 121. This causes the sleeve 122 connected to the saw blade 123 to extend, further grinding out part of the space in the back groove 2. After the saw blade 123, in conjunction with the spring 121, grinds out part of the space in the back groove 2, the thrust of the spring 121 gradually decreases as it is gradually released, until the thrust is insufficient to allow the sleeve 122 to continue extending. At this point, the multiple inner cylinders of the sleeve 122 are not completely pushed out, meaning the saw blade 123 is not completely pushed out, resulting in the back groove 2 not reaching the required depth. Then, an external cylinder drives the drive rod 11 towards the cutting head 12, thereby driving the piston 9 to squeeze the liquid inside the saw chamber 8. Utilizing the incompressibility of the liquid, the liquid within the saw chamber 8 exerts a thrust on the saw blade 123. The sleeve 122 also gradually extends, providing space for the liquid. Under the thrust of the liquid, the saw blade 123 continues to grind the rock deeper until the rock mass in area A is ground to the point where its back side is separated from the original rock mass. The entire back groove 2 can be operated using only the space of the first cutting groove 1, enabling the preparation of samples of the required size on a relatively small operating surface. This equipment significantly reduces the limitations on the operating surface on site, and the prepared samples are less affected by size effects, making subsequent test results more accurate and reflecting the true situation of the fault.

[0079] It is understandable that, such as Figure 16 As shown, the number of cutting heads 12 varies according to their specifications. If the size of a saw blade 123 meets the requirements of the back groove 2, the drilling device can use one cutting head 12. Therefore, the variation in the number of cutting heads 12 is within the protection scope of this application.

[0080] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for preparing a rock test sample, characterized in that, include: A sampling area is pre-defined, which is traversed by a fault fracture, forming rock mass area A and rock mass area B; The rock mass in area A has a first cutting groove (1), and a drilling device is installed in the first cutting groove (1). The drilling device has a back groove (2) in a direction perpendicular to the first cutting groove (1). During the process of opening the back groove (2), the drilling device uses a reciprocating vibrating cutting head (12) to make the saw blade (123) work with the spring (121) to grind out part of the space of the back groove (2), and drives the piston (9) to move so that the liquid in the saw chamber (8) applies a thrust to the saw blade (123) until the saw blade (123) grinds the rock mass in area A to its back side and separates it from the original rock mass.

2. The method for preparing a rock test sample as described in claim 1, characterized in that, The depth of the back groove (2) is not less than the maximum distance between the first cutting groove (1) and the fault crack.

3. The method for preparing a rock test sample as described in claim 1, characterized in that, After the back groove (2) is opened, the second cutting groove (3) and the third cutting groove (4) are opened downward at the left and right ends of the first cutting groove (1) respectively, so that the rock mass in area A is separated from the original rock mass.

4. The method for preparing a rock test sample as described in claim 3, characterized in that, When the fault crack is horizontal or the angle between it and the horizontal plane is no more than 30°, the order in which the second cutting groove (3) and the third cutting groove (4) are opened can be interchanged.

5. The method for preparing a rock test sample as described in claim 3, characterized in that, When the fault crack is vertical or has an angle greater than 30° with the horizontal plane, the second cutting groove (3) is opened first, and then the third cutting groove (4) is opened.

6. The method for preparing a rock test sample as described in claim 5, characterized in that, Before opening the third cutting groove (4), a filler is placed in the second cutting groove (3) to support the rock mass in area A.

7. A rock test sample preparation apparatus, applicable to the rock test sample preparation method according to any one of claims 1-6, characterized in that, include: Drilling equipment; The drilling device includes: a saw chamber (8), and a plurality of retractable sleeves (122) are provided at the lower end face of the closed side of the saw chamber (8), and a saw blade (123) is provided at the retractable end of the sleeve (122). A piston (9) is installed inside the saw chamber (8). The piston (9) squeezes the liquid inside the saw chamber (8) to drive the sleeve (122) to extend and retract.

8. The rock test sample preparation apparatus as described in claim 7, characterized in that, The saw chamber (8) is provided with a cavity (801), and the piston (9) is located inside the cavity (801).

9. The rock test sample preparation apparatus as described in claim 8, characterized in that, The piston (9) is connected to several slide rods (10), the slide rods (10) are connected to drive rods (11), and the drive rods (11) are connected to an external cylinder.

10. The rock test sample preparation apparatus as described in claim 7, characterized in that, The cavity (801) is provided with several springs (121), and the springs (121) correspond one-to-one with the sleeves (122).

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