A true triaxial fractured rock mass torsional shear sample preparation mold

Abstract

The utility model belongs to the rock mass mechanics test technical field discloses a kind of true triaxial fractured rock mass torsional shear sample sample preparation mould, including bottom plate, enclosure cylinder structure, at least a pair of rotating locking device and fracture plugboard;Enclosure cylinder structure includes coaxial sleeve's inner square and outer square cylinder, and annular chamber with cross section being square is formed between the inner square and the outer square cylinder, as perfusion cavity;One open end of enclosure cylinder structure is detachably connected with the side surface of bottom plate, and another open end is used for perfusion forming material;Rotating locking device is symmetrically embedded on the two opposite outer side walls of outer square cylinder, and rotating locking device can rotate around its own axis;Fracture plugboard passes through rotating locking device, and penetrates perfusion cavity.The utility model realizes the independent or coordinated adjustment of fracture occurrence, fracture surface roughness and spatial relationship by rotating locking device;Mould is realized parameter replacement and function extension by detachable structure, reduces the number of repeated moulding, reduces material consumption and experimental cost.

Description

Technical Field

[0001] This utility model discloses a sample preparation mold for a true triaxial fractured rock mass torsion shear specimen, belonging to the field of rock mechanics testing technology. Background Technology

[0002] In the field of geotechnical engineering, the triaxial torsion shear test is an important tool for studying the mechanical behavior of rock masses under complex stress conditions. Specifically, this triaxial torsion shear test applies axisymmetric confining pressure and axial pressure, combined with torque to simulate shear action, to analyze the strength and deformation characteristics of rock and soil masses.

[0003] Such tests are based on the assumption that "the intermediate principal stress equals the minor principal stress," and cannot independently control the triaxial principal stresses, thus failing to accurately characterize the impact of intermediate principal stress changes on the mechanical behavior of rock masses. Therefore, with the increasing complexity of engineering requirements, the true triaxial torsion-shear test technique has been proposed, which simulates the actual stress state of rock masses more realistically by independently controlling the triaxial principal stresses and superimposing torsional loads.

[0004] However, the specimen morphology for conventional triaxial torsion shear tests and true triaxial torsion shear tests typically differs significantly. First, conventional triaxial torsion shear tests use hollow cylindrical specimens, while true triaxial systems require cubic or square specimens. This means that traditional specimens cannot be directly used in true triaxial equipment, limiting the continuity and comparability of experimental data. Second, existing fractured rock sample preparation techniques still have limitations. Currently used sample preparation molds are still based on a single controlled variable model, making it difficult to meet the sample preparation requirements under the synergistic effects of multiple factors such as fracture orientation, surface roughness, and spatial position. Finally, traditional molds are designed only for specific experimental conditions, requiring frequent changes in specimen type or mold adjustments, resulting in low efficiency, high cost, and an inability to meet the complex sample preparation needs under the interaction of multiple factors. Summary of the Invention

[0005] This utility model overcomes the shortcomings of the prior art and proposes a sample preparation mold for a true triaxial fractured rock mass torsional shear test specimen, including: a base plate, a surrounding cylinder structure, at least one pair of rotating locking devices and a fracture insert plate;

[0006] The surrounding structure includes an inner cube and an outer cube that are coaxially fitted together. The inner cube and the outer cube form an annular cavity with a square cross-section, which serves as an injection cavity.

[0007] One open end of the cylindrical structure is detachably connected to one side surface of the base plate, and the other open end is used for pouring molding material.

[0008] The rotating locking device is symmetrically embedded on the two opposite outer side walls of the outer square tube, and the rotating locking device can rotate around its own axis;

[0009] The slit insert passes through the rotating locking device and through the injection cavity.

[0010] Preferably, the rotary locking device has a disc-shaped structure with a plurality of anti-rotation protrusions evenly distributed on its outer circumference at preset intervals. The anti-rotation protrusions are used to limit the rotation angle of the rotary locking device.

[0011] Preferably, the side wall of the outer square tube is provided with a mounting hole that matches the outer diameter of the rotary locking device;

[0012] The rotating locking device is embedded in the mounting hole, and the anti-rotation protrusion engages with the groove on the inner wall of the mounting hole to limit circumferential movement.

[0013] Preferably, the rotating locking device has a clamping groove of a preset size for inserting and clamping the slit insert plate.

[0014] Preferably, the inner cube and the outer square tube are integrally formed structures;

[0015] The inner cube is a solid or hollow structure, and the outer tube is a square tube structure.

[0016] Preferably, the inner cube is a modular assembly structure, comprising four inner cladding panels;

[0017] The four inner cladding panels are detachably connected to one side surface of the base plate, forming a rectangular prism-shaped receiving cavity.

[0018] Preferably, the inner cube further includes a supporting structure;

[0019] The supporting structure is disposed within the square column-shaped receiving cavity and is used to support the inner cladding panel.

[0020] Preferably, the outer square tube is a split splicing structure, including four outer plates;

[0021] Adjacent panels in the outer perimeter are connected by inclined splicing or interlocking structures.

[0022] Preferably, it also includes a fixing hoop;

[0023] The fixing hoop is fitted onto the outer wall of the outer square tube and is fixedly connected to the base plate.

[0024] Preferably, the base plate is provided with a groove that matches the cylindrical structure.

[0025] Compared with existing technologies, the beneficial effects of this invention are as follows: Based on a true triaxial hollow torsion shear testing machine, this invention proposes a sample preparation mold for true triaxial fractured rock mass torsion shear specimens. A rotating locking device is installed to achieve independent or coordinated adjustment of fracture orientation (such as dip angle and strike), fracture surface roughness, and the spatial relationship of multiple fractures, allowing for flexible simulation of complex geological conditions. The mold's detachable structure enables parameter replacement and functional expansion, allowing the same mold to adapt to various testing needs, significantly reducing the number of mold re-runs, lowering material consumption and experimental costs, while simultaneously improving the consistency and efficiency of specimen preparation. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the mold in an embodiment of this utility model;

[0027] Figure 2 This is a top view of the mold in an embodiment of the present invention;

[0028] Figure 3 This is a longitudinal sectional view of the mold in an embodiment of this utility model;

[0029] Figure 4 This is a schematic diagram of the outer plate of the rotating locking device embedded in an embodiment of the present utility model;

[0030] Figure 5 This is a schematic diagram of the rotating locking device in an embodiment of the present invention;

[0031] Figure 6 This is a top view of the base plate in an embodiment of this utility model;

[0032] Figure 7 For standard JRC value cards.

[0033] In the diagram: 1. Base plate; 2. Outer plate; 3. Inner plate; 4. Support structure; 5. Fixing hoop; 6. Clamping groove; 7. Anti-rotation protrusion; 8. First mounting hole; 9. Second mounting hole; 10. First crack; 11. Second crack; 12. First groove; 13. Second groove. Detailed Implementation

[0034] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0035] Please see Figure 1As shown, this embodiment provides a sample preparation mold for a true triaxial fractured rock mass torsional shear test specimen, including: a base plate 1, a surrounding cylinder structure, at least one pair of rotating locking devices and a fracture insert plate;

[0036] The surrounding structure includes an inner cube and an outer cube that are coaxially nested together. The inner cube and the outer cube form an annular cavity with a square cross-section, which serves as the injection cavity.

[0037] One open end of the cylindrical structure is detachably connected to one side surface of the base plate 1, and the other open end is used for pouring molding material;

[0038] The rotating locking device is symmetrically embedded on the two opposite outer walls of the outer square tube, and the rotating locking device can rotate around its own axis;

[0039] The fissure insert passes through the rotating locking device and through the injection cavity to form a fissure.

[0040] In one embodiment of this invention, the rotating locking device is a conventional disc-shaped structure that can rotate around its own axis on two opposite outer walls of the outer square tube to adjust the inclination angle of the internally inserted slotted plate. In this embodiment, the specific number of symmetrical rotating locking devices is not limited; for example, there can be multiple pairs, as long as they are symmetrically arranged on two opposite outer walls of the outer square tube to achieve the purpose of symmetrically clamping the slotted plate.

[0041] Furthermore, in this embodiment, as Figure 5 As shown, in order to avoid the conventional rotary locking device from rotating during the sample preparation process and causing changes in the crack inclination angle, this utility model sets the rotary locking device as a disc-shaped structure with multiple anti-rotation protrusions 7 evenly distributed on the outer circumference. The anti-rotation protrusions 7 are used to limit the rotation angle of the rotary locking device, thereby avoiding the displacement of the crack insertion plate inclination angle caused by external force accidentally touching the rotary locking device during the sample preparation process.

[0042] It should be noted that the present invention does not limit the number and size of the anti-rotation protrusions 7. Those skilled in the art can set them according to the actual situation. The number of anti-rotation protrusions 7 determines the included angle between adjacent protrusions. In this embodiment, there are 12 anti-rotation protrusions 7, the included angle between each anti-rotation protrusion 7 is 30°, and each anti-rotation protrusion 7 is 1.5mm wide and 2mm high.

[0043] In this embodiment, as Figure 4 As shown, the outer square tube has two pairs of mounting holes on its side wall that match the outer diameter of the rotary locking device; specifically, it includes a first mounting hole 8 and a second mounting hole 9. In this embodiment, it includes two pairs of rotary locking devices, which are embedded in the two pairs of mounting holes. The anti-rotation protrusion 7 engages with the groove on the inner wall of the mounting hole to limit the rotation in the circumferential direction.

[0044] Furthermore, in this embodiment of the present invention, a clamping groove of a preset size is provided on the rotating locking device for clamping and fixing the fissure insert plate, thereby ensuring that the fissure insert plate maintains a preset tilt angle and position during installation and sample preparation, and avoiding displacement caused by external force contact or material pouring.

[0045] This embodiment of the invention does not limit the size and number of clamping slots 6 on the rotary locking device. Specifically, in this embodiment, the clamping slots 6 are designed to be 1mm wide and 8mm long, and their function is to achieve crack positioning by inserting and fixing the crack insert plate. When the crack insert plate passes through the rotary locking device corresponding to the first mounting hole 8, a first crack 10 is formed in the sample; similarly, when the crack insert plate passes through the rotary locking device corresponding to the second mounting hole 9, a second crack 11 is formed in the sample.

[0046] To further optimize the adjustability of crack size and distribution and flexibly adjust crack width, this invention configures the rotary locking device with multiple sets of clamping grooves 6. Each set of clamping grooves 6 has a different size (for example, in this embodiment, an 8mm long clamping groove 6 is used; other sets can be adapted to 6mm, 5mm, etc.). Crack width can be quickly adjusted by replacing the corresponding components. Simultaneously, the mounting holes of the outer square tube support multiple positions and quantities. When the outer square tube is replaced with a version with different mounting hole positions or quantities, the matching of the clamping grooves 6 of the rotary locking device with the crack insertion path allows for simultaneous control of the position, quantity, and spatial relationship of cracks in the sample (such as the distance and angle between the first crack 10 and the second crack 11). This design, through modular combination, enhances the mold's compatibility with complex crack parameters.

[0047] This embodiment of the invention does not specifically limit the materials of the base plate 1 and the surrounding cylinder structure; steel, transparent polymer materials (plexiglass, polycarbonate, etc.), or other materials can be used. In this embodiment, plexiglass is selected to make the mold for easy observation.

[0048] This utility model embodiment does not limit the form of the inner cube and the outer tube. They can be integrally formed structures or split splicing structures. The inner cube can be a solid structure or a hollow structure. Those skilled in the art can adjust it according to the actual situation.

[0049] In this embodiment, in order to achieve more flexible adjustment of mold parameters and reduce the consumption of mold materials, both the inner cube and the outer square tube are split splicing structures, and both the inner cube and the outer square tube are square tube structures.

[0050] Specifically, the inner cube includes four inner enclosure panels 3; all four inner enclosure panels 3 are detachably connected to one side surface of the base plate 1, forming a rectangular prism-shaped receiving cavity.

[0051] Specifically, in this embodiment, the inner cladding panel 3 is an acrylic sheet with a height of 110mm and a thickness of 5mm. Adjacent inner cladding panels 3 are joined by beveled surfaces. Specifically, the cross-sectional dimensions of the inner cladding panel 3 are an isosceles trapezoid with an upper base of 30mm, a lower base of 20mm, and a thickness of 5mm.

[0052] Furthermore, to prevent deformation of the four inner panels 3 of the inner cube, a support structure 4 is provided within the rectangular cavity formed by the inner cube to provide support. In this embodiment, the support structure 4 is specifically a solid plexiglass rod with a side length of 20mm and a height of 110mm.

[0053] Specifically, in this embodiment, the outer square tube includes four outer peripheral plates 2; the four outer peripheral plates 2 are detachably connected to one side surface of the bottom plate 1, and surround the square column-shaped receiving cavity formed by the inner peripheral plate 3, that is, an annular cavity with a square cross-section is formed between the inner peripheral plate 3 and the outer peripheral plate 2, which serves as the injection cavity.

[0054] Specifically, in this embodiment, the outer plate 2 is an organic glass plate with a height of 110mm and a thickness of 5mm, and adjacent outer plates 2 are spliced ​​together by bevels. Specifically, the cross-sectional dimensions of the outer plate 2 are an isosceles trapezoid with an upper base of 60mm, a lower base of 50mm, and a thickness of 5mm.

[0055] It should be noted that this utility model does not limit the connection method between adjacent inner panels 3 or outer panels 2. For example, the connection can also be achieved by means of interlocking, snap-fitting, or bolt fastening. As long as the purpose of ensuring a tight fit between the panels and a stable structure is achieved, it is acceptable.

[0056] Furthermore, to prevent the outer plate 2 from being squeezed after the molding material is poured into the injection cavity, a fixing hoop 5 is fitted on the outer wall of the outer square tube;

[0057] The fixing hoop 5 is fixedly connected to the base plate 1 and fits tightly against the outer wall of the outer plate 2.

[0058] Specifically, in this embodiment, the base plate 1 is a square acrylic sheet with a side length of 100mm and a thickness of 15mm, and the base plate 1 is provided with a groove that matches the surrounding cylinder structure. In practical applications, it specifically includes, for example... Figure 6 The first groove 12 and the second groove 13 shown are both 10mm deep. The first groove 12 is for the outer plate 2 to be inserted, and the second groove 13 is for the inner plate 3 and the support structure 4 to be inserted.

[0059] Based on the dimensions of the inner circumferential plate 3, outer circumferential plate 2, and bottom plate 1, the wall thickness of the corresponding injection cavity is 10mm and the height is 100mm.

[0060] Based on the specific structure of the mold in this embodiment of the present invention, the sample preparation method of the sample mold is as follows:

[0061] First, select low-strength organic materials, and then use 3D printing technology, according to... Figure 7 The standard JRC card shown is used to produce a slotted plate with a width of 8mm and a length of more than 50mm at a scale of 1:12.5.

[0062] Subsequently, a layer of petroleum jelly is evenly applied to the inner surface of the outer plate 2, the inner and outer surfaces of the inner plate 3, and the inner wall of the groove in the base plate 1. This facilitates mold assembly, reduces resistance during subsequent demolding, and protects the integrity of the sample.

[0063] Next, using hard matrix adhesive, the fixing hoop 5 is fixed to the predetermined position on the base plate 1 to ensure its stability and support function in subsequent steps.

[0064] After assembling the intermediate support structure 4 and the inner circumference plate 3, insert them as a whole into the second groove 13 of the base plate 1. According to the pre-set crack angle, install the rotating locking device in the mounting holes of the front / rear circumference plates 2, preparing for the insertion of the crack insert. Insert the front / rear outer circumference plates 2 and the left / right outer circumference plates 2 one by one into the first groove 12 of the base plate 1, ensuring that the four outer circumference plates 2 are tightly fitted with the surrounding fixing clamps 5, forming a complete mold space. As needed, select one of the prepared crack inserts and insert it into the clamping groove 6 of the rotating locking device.

[0065] The cement mortar, prepared in a certain proportion, is slowly poured into the mold cavity from another opening, while a vibrating tool is used to compact it to ensure that the cement mortar is uniform and dense within the cavity.

[0066] The mold filled with cement mortar was placed in a standard curing chamber for 3 days of curing. After curing, the mold was removed in the following order: "base plate 1 → supporting structure 4 → inner panel 3 → outer panel 2," completing the demolding operation. The demolded sample was then placed back into the standard curing chamber for further curing for 28 days. After curing, the sample was removed, and its upper and lower surfaces were polished with a grinder until smooth and flat to meet the needs of subsequent testing or research.

[0067] This invention, based on a true triaxial hollow torsion shear testing machine, proposes a sample preparation mold for true triaxial fractured rock mass torsion shear specimens. By optimizing the mold structure and its compatibility with the true triaxial torsion shear apparatus, the problem of mismatch between conventional triaxial torsion shear specimen size and loading method is solved. A rotating locking device is set up to achieve independent or coordinated adjustment of fracture orientation (such as dip angle and strike), fracture surface roughness, and spatial relationship of multiple fractures, which can flexibly simulate complex geological conditions. The mold can achieve parameter replacement and functional expansion through detachable components. The same mold can adapt to multiple test requirements, significantly reducing the number of mold re-runs, reducing material consumption and experimental costs, while improving the consistency and efficiency of specimen preparation.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A sample preparation mold for a true triaxial fractured rock mass torsional shear test specimen, characterized in that, include: Base plate, surrounding cylindrical structure, at least one pair of rotary locking devices and slotted inserts; The surrounding structure includes an inner cube and an outer cube that are coaxially fitted together. The inner cube and the outer cube form an annular cavity with a square cross-section, which serves as an injection cavity. One open end of the cylindrical structure is detachably connected to one side surface of the base plate, and the other open end is used for pouring molding material. The rotating locking device is symmetrically embedded on the two opposite outer side walls of the outer square tube, and the rotating locking device can rotate around its own axis; The slit insert passes through the rotating locking device and through the injection cavity.

2. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 1, characterized in that, The rotary locking device has a disc-shaped structure with multiple anti-rotation protrusions evenly distributed on its outer circumference at preset intervals. The anti-rotation protrusions are used to limit the rotation angle of the rotary locking device.

3. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 2, characterized in that, The outer square tube has mounting holes on its side wall that match the outer diameter of the rotary locking device; The rotating locking device is embedded in the mounting hole, and the anti-rotation protrusion engages with the groove on the inner wall of the mounting hole to limit circumferential movement.

4. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 1, characterized in that, The rotating locking device has a clamping groove of a preset size for inserting and clamping the slit insert plate.

5. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 1, characterized in that, The inner cube and the outer square tube are integrally formed structures; The inner cube is a solid or hollow structure, and the outer tube is a square tube structure.

6. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 1, characterized in that, The inner cube is a modular, spliced ​​structure, comprising four inner panels; The four inner cladding panels are detachably connected to one side surface of the base plate, forming a rectangular prism-shaped receiving cavity.

7. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 6, characterized in that, The inner cube also includes a supporting structure; The supporting structure is disposed within the square column-shaped receiving cavity and is used to support the inner cladding panel.

8. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 1, characterized in that, The outer square tube is a modular splicing structure, consisting of four outer panels; Adjacent panels in the outer perimeter are connected by inclined splicing or interlocking structures.

9. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 8, characterized in that, It also includes fixing hoops; The fixing hoop is fitted onto the outer wall of the outer square tube and is fixedly connected to the base plate.

10. The sample preparation mold for a true triaxial fractured rock mass torsional shear specimen according to claim 1, characterized in that, The base plate is provided with a groove that matches the cylindrical structure.

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