Rock fracture brittleness experiment device in non-uniform crustal stress field
By designing a non-uniform stress field rock fracture brittleness experimental device with modular ring components and contact components, the problem of the inability to quantitatively study the crack propagation and deformation failure law of rocks under tensile stress in existing technologies has been solved, and accurate simulation and stable transfer of loading force under non-uniform stress field have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NAT INST OF NATURAL HAZARDS MINISTRY OF EMERGENCY MANAGEMENT OF CHINA
- Filing Date
- 2026-01-21
- Publication Date
- 2026-04-21
AI Technical Summary
Existing mechanical testing machines and devices cannot quantitatively study the crack propagation and deformation failure laws of rocks under tensile stress, nor can they obtain the tensile strength and tensile failure process of rocks under triaxial stress.
An experimental device for testing the brittle fracture of rocks in a non-uniform stress field was designed. The non-uniform stress field was simulated by using modular ring components and contact components to apply differentiated pressures, forming a continuous stress gradient. The loading force was ensured to be transmitted along a preset direction by limiting rings and positioning components.
It achieves accurate simulation of rock fracture brittleness under non-uniform stress field, improves the accuracy of experimental results, avoids assembly errors and ring deformation, and ensures stable transmission of loading force.
Smart Images
Figure CN121898907A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of rock fracture brittleness test apparatus, specifically a rock fracture brittleness test apparatus in a non-uniform stress field. Background Technology
[0002] In fields such as oil and gas development and underground engineering construction, the study of the mechanical properties of rocks is crucial. Underground rocks or rock masses can withstand relatively low tensile stresses and are highly susceptible to tensile failure, posing significant obstacles to related engineering projects. Therefore, studying the deformation characteristics of rocks under tensile stress and accurately measuring the tensile fracture brittleness of rocks has important theoretical and practical significance for reservoir development and underground engineering construction.
[0003] Most existing mechanical testing machines and devices are unable to quantitatively study the crack propagation and deformation failure laws of rocks under tensile stress. They can only approximate the tensile fracture brittleness of rocks through splitting and uniaxial compression experiments, and cannot obtain the tensile strength and tensile failure process of rocks under triaxial stress. Summary of the Invention
[0004] To solve the above technical problems, the present invention is achieved through the following technical solution: an experimental device for rock fracture brittleness in a non-uniform stress field, comprising a base, a support rod fixedly connected to the top of the base, a top plate fixedly connected to the top of the support rod, a hydraulic cylinder fixedly connected to the middle of the top of the top plate, the output end of the hydraulic cylinder penetrating the top plate, and a connecting plate fixedly connected to the output end of the hydraulic cylinder. There are four support rods, which are evenly distributed at the top corner of the base. A pressure plate is fixedly connected to the bottom center of the connecting plate, and a positioning block is fixedly connected to the bottom edge of the connecting plate. The positioning block is arc-shaped, and there are four positioning blocks, which are evenly distributed around the pressure plate. The confining pressure assembly is fixedly installed at the top center of the base; The confining pressure assembly includes multiple rings. Each ring has a groove at its top and a protrusion at its bottom. A fixing block is fixedly connected to the outer side of each ring. The rings are installed on the top of a square plate, with the protrusion at the bottom of the ring positioned inside the positioning groove. Another ring is then stacked on top of the installed rings. After multiple rings are installed, the sample is placed in the center of the top of the square plate. The hydraulic rod then operates, pushing the contact assembly to apply a load to the sample, creating different layers of confining pressure on the rock sample to simulate a non-uniform stress field. The multiple rings form a protective shield that can directly block most of the fracture fragments. A hydraulic rod is fixedly connected to the outer side of the fixing block, and the output end of the hydraulic rod passes through the fixing block and extends into the interior of the ring. The output end of the hydraulic rod is fixedly connected to the contact assembly.
[0005] Preferably, multiple rings are evenly arranged vertically. The modular design of these rings allows for free combination according to sample height requirements, breaking the limitations of traditional fixed-height confining pressure components. Furthermore, the hydraulic rods on rings at different positions apply differentiated pressure, creating a continuous stress gradient along the sample height direction, more closely mimicking the non-uniform stress characteristics of field strata varying with burial depth. The protrusions on opposite sides of adjacent rings are located inside the grooves. Four fixing blocks are evenly distributed on each ring. Through the cooperation between the protrusions and grooves, the radial and circumferential displacement of each ring can be strictly limited. During installation, the protrusions of the rings can precisely embed into the grooves of adjacent rings, achieving coaxiality of each ring without additional calibration tools, thus avoiding localized stress concentration during confining pressure loading due to assembly misalignment. Meanwhile, the tight fit of the concave and convex structures can reduce the relative shaking between the rings, ensuring the stability of the confining pressure transmission path from the loading component to the rock sample, and avoiding interference from assembly errors in the accurate simulation of non-uniform stress fields. There are four protrusions on one ring, which are evenly distributed at the bottom of the ring. There are four grooves on one ring, which are evenly distributed at the top of the ring. Limiting rings are fixedly connected to the inner wall of the ring. The limiting rings are vertically distributed along the inner wall of the ring, which can evenly distribute the local stress generated when the hydraulic rod is loaded to the whole ring, preventing the ring from bulging or plastic deformation due to excessive local stress, and enabling the ring to maintain its shape stability. There are multiple limiting rings on one ring, which are evenly arranged along the vertical direction on the inner wall of the ring. A fixing ring is fixedly connected to the top edge of the ring.
[0006] Preferably, the contact assembly includes a pressure plate, which is fixedly connected to the output end of a hydraulic rod. A connecting block is fixedly connected to the end of the pressure plate away from the hydraulic rod. A slot is opened in the middle of the end of the connecting block away from the pressure plate. A spring plate is fixedly connected inside the slot. A magnetic block is fixedly connected to the outside of the pressure plate. There are two spring plates, which are symmetrically arranged with the middle rod as the center. In the initial state, the end of the block near the magnetic block is magnetic. The block and the magnetic block have the same magnetism. The sample is placed at the top center of the square plate. Then the hydraulic rod works, causing the hydraulic rod to push the contact assembly to apply a load force to the sample. At this time, the block contacts the outside of the sample and is squeezed. The block rotates around the middle rod under force, causing the contact point between the block and the middle sample to change. This can reproduce the dynamic adjustment process of the contact interface of the rock under pressure, making the experimental results closer to the rock fracture behavior under real geological conditions. There are two connecting blocks. Blocks are arranged on opposite sides of the connecting blocks. A middle rod is rotatably connected to the middle of the block. The two ends of the middle rod are located inside the slots of the two blocks, and the blocks are elliptical.
[0007] Preferably, the base includes a platform, a square plate is fixedly connected to the top center of the platform, a central groove is formed in the top center of the square plate, multiple side holes are formed on the inner side of the central groove, a positioning groove is formed in the top of the square plate, the number of positioning grooves is multiple, the multiple positioning grooves are evenly distributed on the top of the square plate with the central groove as the center, a protrusion at the bottom of a ring near the base is located inside the positioning groove, a positioning component is fixedly connected to the top center of the square plate, and an annular groove is formed in the top of the square plate, the number of annular grooves is multiple, the multiple annular grooves are evenly distributed on the square plate with the central groove as the center, the annular groove is located at the interval between the central groove and the positioning groove, a guide rod is fixedly connected inside the annular groove, and a fixing member is slidably connected inside the annular groove.
[0008] Preferably, the fixing component includes a movable block located inside the annular groove. A guide rod passes through the movable block, and the movable block is slidably connected to the annular groove via the guide rod. A compression spring is installed inside the annular groove. When the sample is placed on top of the circular plate, the sample side contacts the side plate, creating compression. The compression spring is compressed, causing the side plate to slide along the direction of the guide rod in the annular groove. Thus, the movable block and the side plate fix the bottom of the sample. Subsequently, the hydraulic cylinder operates, causing the hydraulic cylinder to move the bottom connecting plate and pressure plate downward, thereby fixing the top of the sample. At this time, the vertical direction of the sample is fixed, preventing sample displacement and ensuring effective transmission of the loading force. The two ends of the compression spring are fixedly connected to the movable block and the inner wall of the annular groove, respectively. A side plate is fixedly connected to the top of the movable block. The side plate is set perpendicular to the movable block, and the side of the side plate away from the compression spring is inclined. Two cylinders are fixedly connected to the outer side of the movable block, and the two cylinders are symmetrically arranged with the movable block as the center.
[0009] Preferably, the positioning component includes a circular plate, with a return spring fixedly connected to the center of the bottom of the circular plate. The return spring is located inside a central groove, and the end of the return spring away from the circular plate is fixedly connected to the bottom of the central groove. Multiple intermediate plates are fixedly connected to the bottom of the circular plate, evenly distributed around the return spring. Initially, the circular plate is positioned above the square plate, and the clamping plate is positioned above the cylinder. After the sample is placed, under the pressure of the top pressure plate and the sample's own weight, the return spring is compressed, causing the circular plate to move the bottom clamping plate. The cylinder moves downwards, positioning it between two adjacent clamping plates. This prevents the sample from shifting laterally or axially, ensuring stress is transmitted only in the preset direction. The middle plate is located inside the side hole, and a through hole is provided in the center of the circular plate. There are multiple through holes, evenly distributed around the return spring. The through holes and the annular groove are on the same vertical plane. The side plate passes through the circular plate via the through holes. A clamping plate is fixedly connected to the bottom of the circular plate. There are multiple clamping plates, divided into four groups. The clamping plates in each group are symmetrically arranged on both sides of the through hole.
[0010] This invention provides an experimental apparatus for testing the brittle fracture of rocks in a non-uniform stress field. It has the following advantages: (i) The experimental device for rock fracture brittleness in non-uniform stress field, through the modular design of multiple rings, can be freely combined according to the sample height requirements, breaking the limitations of traditional fixed height confining pressure components. Furthermore, the hydraulic rods on the rings at different positions apply differentiated pressures, forming a continuous stress gradient along the sample height direction, which is closer to the non-uniform stress characteristics of the strata in the field as the burial depth changes.
[0011] (ii) The rock fracture brittleness test device in the non-uniform stress field can reduce the relative shaking between the rings through the close fit of the concave and convex structure, ensuring the stability of the transmission path of the confining pressure from the loading component to the rock sample, and avoiding the interference of assembly errors on the accurate simulation of the non-uniform stress field.
[0012] (III) The experimental device for rock fracture brittleness in a non-uniform stress field, through the vertical distribution of the limiting ring along the inner wall of the ring, can evenly distribute the local stress generated when the hydraulic rod is loaded to the whole ring, avoid the ring from bulging or plastic deformation due to excessive local stress, and enable the ring to maintain its shape stability.
[0013] (iv) The experimental device for rock fracture brittleness in a non-uniform stress field moves the bottom plate downward through the circular plate, so that the cylinder on the moving block is located at the interval between two adjacent plates. At this time, the sample will not move laterally or axially, ensuring that the stress is transmitted only in the preset direction. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a partial structural schematic diagram of the present invention; Figure 3 This is a schematic diagram of the confining pressure assembly of the present invention; Figure 4 This is a partial structural schematic diagram of the confining pressure assembly of the present invention; Figure 5 This is a schematic diagram of the contact component of the present invention; Figure 6 This is a schematic diagram of the structure of the base of the present invention; Figure 7 This is a partial structural schematic diagram of the base of the present invention; Figure 8 This is a schematic diagram of the structure of the fastener of the present invention; Figure 9 This is a schematic diagram of the positioning component of the present invention.
[0015] In the diagram: 1. Base; 11. Platform; 12. Square plate; 13. Positioning assembly; 131. Round plate; 132. Clamping plate; 133. Return spring; 134. Through hole; 135. Middle plate; 14. Fixing component; 141. Compression spring; 142. Cylinder; 143. Moving block; 144. Side plate; 15. Positioning groove; 16. Annular groove; 17. Guide rod; 18. Middle groove; 2. Support rod; 3. Top 4. Plate; 5. Hydraulic cylinder; 6. Connecting plate; 7. Confining pressure assembly; 8. Ring; 9. Protrusion; 10. Groove; 11. Fixing ring; 12. Fixing block; 13. Hydraulic rod; 24. Contact assembly; 15. Pressure plate; 26. Magnetic block; 37. Connecting block; 48. Slot; 59. Spring plate; 60. Intermediate rod; 610. Block; 62. Limiting ring; 73. Pressure plate; 84. Positioning block. Detailed Implementation
[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0017] First embodiment, such as Figures 1 to 5 As shown, the present invention provides a technical solution: an experimental device for rock fracture brittleness in a non-uniform stress field, including a base 1, a support rod 2 fixedly connected to the top of the base 1, a top plate 3 fixedly connected to the top of the support rod 2, a hydraulic cylinder 4 fixedly connected to the middle of the top of the top plate 3, the output end of the hydraulic cylinder 4 penetrating the top plate 3, and a connecting plate 5 fixedly connected to the output end of the hydraulic cylinder 4. There are four support rods 2, which are evenly distributed at the top corner of the base 1. A pressure plate 7 is fixedly connected to the bottom middle of the connecting plate 5. A positioning block 8 is fixedly connected to the bottom edge of the connecting plate 5. The positioning block 8 is arc-shaped and there are four positioning blocks 8, which are evenly distributed around the pressure plate 7. Confining pressure assembly 6 is fixedly installed at the top center of the base 1; The confining pressure assembly 6 includes multiple rings 61. Each ring 61 has a groove 63 at its top and a protrusion 62 at its bottom. A fixing block 65 is fixedly connected to the outer side of each ring 61. The rings 61 are installed on the top of the square plate 12, with the protrusion 62 at the bottom of the ring 61 positioned inside the positioning groove 15. Another ring 61 is then stacked on top of the installed rings 61. After installing multiple rings 61, the sample is placed in the center of the top of the square plate 12. Then, the hydraulic rod 66 operates, pushing the contact assembly 67 to apply a load to the sample, creating different layers of confining pressure on the rock sample to simulate a non-uniform stress field. The multiple rings 61 form a protective shield that can directly block most of the fractured fragments. The hydraulic rod 66 is fixedly connected to the outer side of the fixing block 65. The output end of the hydraulic rod 66 passes through the fixing block 65 and extends into the interior of the ring 61. The output end of the hydraulic rod 66 is fixedly connected to the contact assembly 67.
[0018] Multiple rings 61 are evenly arranged vertically. The modular design of these rings allows for free combination according to sample height requirements, breaking the limitations of traditional fixed-height confining pressure components. Furthermore, the hydraulic rods 66 on rings 61 at different positions apply differentiated pressure, forming a continuous stress gradient along the sample height direction, more closely mimicking the non-uniform stress characteristics of field strata varying with burial depth. The protrusions 62 on opposite sides of adjacent rings 61 are located inside grooves 63. Four fixing blocks 65 are evenly distributed on each ring 61. Through the cooperation between the protrusions 62 and grooves 63, the radial and circumferential displacement of each ring can be strictly limited. During installation, the protrusions 62 of rings 61 can precisely embed into the grooves 63 of adjacent rings 61, achieving coaxiality of each ring 61 without additional calibration tools. This avoids localized stress concentration during confining pressure loading due to assembly misalignment. The concave-convex structure... The tight fit of the structure reduces the relative sway between the rings 61, ensuring a stable transmission path of confining pressure from the loading component to the rock sample, and avoiding interference with the accurate simulation of non-uniform stress field due to assembly errors. There are four protrusions 62 on one ring 61, which are evenly distributed at the bottom of the ring 61. There are four grooves 63 on one ring 61, which are evenly distributed at the top of the ring 61. The inner wall of the ring 61 is fixedly connected to a limiting ring 68, which is vertically distributed along the inner wall of the ring 61. It can evenly distribute the local stress generated when the hydraulic rod 66 is loaded to the whole ring 61, preventing the ring 61 from bulging or plastic deformation due to excessive local stress, and keeping the ring stable in shape. There are multiple limiting rings 68 on one ring 61, which are evenly arranged along the vertical direction on the inner wall of the ring 61. A fixing ring 64 is fixedly connected to the top edge of the ring 61.
[0019] The contact assembly 67 includes a pressure plate 671, which is fixedly connected to the output end of the hydraulic rod 66. A connecting block 673 is fixedly connected to the end of the pressure plate 671 away from the hydraulic rod 66. A slot 674 is formed in the middle of the end of the connecting block 673 away from the pressure plate 671. A spring plate 675 is fixedly connected inside the slot 674. A magnetic block 672 is fixedly connected to the outside of the pressure plate 671. There are two spring plates 675, which are symmetrically arranged with the middle rod 676 as the center. In the initial state, the end of the block 677 near the magnetic block 672 is magnetic. The block 677 and the magnetic block 672 have the same magnetism. The sample is placed at the top center of the square plate 12, and then... When the hydraulic rod 66 operates, it pushes the contact component 67 to apply a load force to the sample. At this time, the block 677 contacts the outer side of the sample and is squeezed. The block 677 rotates around the intermediate rod 676 under force, causing the contact point between the block 677 and the middle sample to change. This can reproduce the dynamic adjustment process of the contact interface of the rock under pressure, making the experimental results closer to the rock fracture behavior under real geological conditions. There are two connecting blocks 673. Blocks 677 are set on opposite sides of the connecting blocks 673. The intermediate rod 676 is rotatably connected to the middle of the block 677. The two ends of the intermediate rod 676 are located inside the slots 674 of the two blocks 677 respectively. The blocks 677 are elliptical in shape.
[0020] The second embodiment is based on the first embodiment; please refer to [link / reference]. Figures 6 to 8 As shown, the base 1 includes a platform 11, a square plate 12 fixedly connected to the top center of the platform 11, a central groove 18 formed in the top center of the square plate 12, multiple side holes formed on the inner side of the central groove 18, a positioning groove 15 formed in the top of the square plate 12, and multiple positioning grooves 15 evenly distributed on the top of the square plate 12 with the central groove 18 as the center. A protrusion 62 at the bottom of a ring 61 near the base 1 is located inside the positioning groove 15. A positioning component 13 is fixedly connected to the top center of the square plate 12. An annular groove 16 is formed in the top of the square plate 12, and multiple annular grooves 16 are evenly distributed on the square plate 12 with the central groove 18 as the center. The annular groove 16 is located at the interval between the central groove 18 and the positioning groove 15. A guide rod 17 is fixedly connected inside the annular groove 16, and a fixing member 14 is slidably connected inside the annular groove 16.
[0021] The fixing component 14 includes a movable block 143, which is located inside the annular groove 16. A guide rod 17 passes through the movable block 143, and the movable block 143 is slidably connected to the annular groove 16 via the guide rod 17. A compression spring 141 is installed inside the annular groove 16. When the sample is placed on top of the circular plate 131, the sample side contacts the side plate 144, causing compression. The compression spring 141 is compressed, causing the side plate 144 to be forced to slide the movable block 143 along the direction of the guide rod 17 in the annular groove 16. Thus, the movable block 143 and the side plate 144 fix the bottom of the sample. Subsequently, the hydraulic cylinder 4 operates, causing the hydraulic cylinder 4 to... The connecting plate 5 and pressure plate 7 at the bottom of the moving block move downwards to fix the top of the sample. At this time, the vertical direction of the sample is fixed to prevent sample displacement and ensure effective transmission of loading force. The two ends of the compression spring 141 are fixedly connected to the inner wall of the moving block 143 and the annular groove 16, respectively. The top of the moving block 143 is fixedly connected to a side plate 144, which is set perpendicular to the moving block 143. The side of the side plate 144 away from the compression spring 141 is inclined. The outer side of the moving block 143 is fixedly connected to a cylinder 142. There are two cylinders 142, which are symmetrically arranged with the moving block 143 as the center.
[0022] The third embodiment is based on embodiments one and two; please refer to [link / reference]. Figure 9 As shown, the positioning component 13 includes a circular plate 131. A return spring 133 is fixedly connected to the bottom center of the circular plate 131. The return spring 133 is located inside the intermediate groove 18. The end of the return spring 133 away from the circular plate 131 is fixedly connected to the bottom of the intermediate groove 18. An intermediate plate 135 is fixedly connected to the bottom of the circular plate 131. There are multiple intermediate plates 135, which are evenly distributed around the return spring 133. In the initial state, the circular plate 131 is located above the square plate 12, and the clamping plate 132 is located above the cylinder 142. After the sample is placed, under the pressure of the top pressure plate 7 and the weight of the sample itself, the return spring 133 is compressed, causing the circular plate 131 to drive the bottom clamping plate 132. The cylinder 142 on the moving block 143 is moved downwards, so that it is located at the interval between two adjacent clamping plates 132. At this time, the sample will not move laterally or axially, ensuring that the stress is transmitted only in the preset direction. The middle plate 135 is located inside the side hole. The circular plate 131 has a through hole 134 in the middle. There are multiple through holes 134. The multiple through holes 134 are evenly distributed around the reset spring 133. The through holes 134 and the annular groove 16 are located on the same vertical plane. The side plate 144 passes through the circular plate 131 through the through hole 134. The bottom of the circular plate 131 is fixedly connected to a clamping plate 132. There are multiple clamping plates 132. The multiple clamping plates 132 are divided into four groups. The multiple clamping plates 132 in one group are symmetrically arranged on both sides of the through hole 134.
[0023] In use, the ring 61 is installed on the top of the square plate 12, so that the protrusion 62 at the bottom of the ring 61 is located inside the positioning groove 15, so that another ring 61 is stacked on top of the installed ring 61, and multiple rings 61 are installed.
[0024] The sample is placed on top of the circular plate 131. The sample side contacts the side plate 144 and is squeezed. The compression spring 141 is compressed, which causes the side plate 144 to slide along the direction of the guide rod 17 in the annular groove 16. Thus, the moving block 143 and the side plate 144 fix the bottom of the sample. Then, the hydraulic cylinder 4 works, which causes the bottom connecting plate 5 and the pressure plate 7 to move downward, thereby fixing the top of the sample.
[0025] The hydraulic rod 66 operates, causing it to push the contact component 67 to apply a load force to the sample, forming different stratified confining pressures on the rock sample to simulate a non-uniform stress field.
[0026] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0027] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. An experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field, characterized in that, Includes a base (1), the top of which is fixedly connected to a support rod (2), there are four support rods (2), the four support rods (2) are evenly distributed at the top corner of the base (1), the top of which is fixedly connected to a top plate (3), the top of which is fixedly connected to a hydraulic cylinder (4), the output end of which penetrates the top plate (3), the output end of which is fixedly connected to a connecting plate (5), the bottom of which is fixedly connected to a pressure plate (7), the bottom edge of which is fixedly connected to a positioning block (8), the positioning block (8) is arc-shaped, there are four positioning blocks (8), the four positioning blocks (8) are evenly distributed around the pressure plate (7); Containment pressure assembly (6), which is fixedly installed at the top center of the base (1); The confining pressure assembly (6) includes a ring (61), and there are multiple rings (61). The top of the ring (61) is provided with a groove (63), and the bottom of the ring (61) is provided with a protrusion (62). A fixing block (65) is fixedly connected to the outside of the ring (61), and a hydraulic rod (66) is fixedly connected to the outside of the fixing block (65). The output end of the hydraulic rod (66) passes through the fixing block (65) and extends into the interior of the ring (61). A contact assembly (67) is fixedly connected to the output end of the hydraulic rod (66).
2. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 1, characterized in that: Multiple rings (61) are evenly arranged along the vertical direction. The protrusions (62) on opposite sides of two adjacent rings (61) are located inside the grooves (63). There are four fixing blocks (65) on one ring (61), which are evenly distributed on the ring (61). There are four protrusions (62) on one ring (61), which are evenly distributed at the bottom of the ring (61). There are four grooves (63) on one ring (61), which are evenly distributed at the top of the ring (61).
3. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 1, characterized in that: The inner wall of the ring (61) is fixedly connected to a limiting ring (68). There are multiple limiting rings (68) on a ring (61). The multiple limiting rings (68) are evenly arranged on the inner wall of the ring (61) along the vertical direction. A fixing ring (64) is fixedly connected to the top edge of the ring (61).
4. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 3, characterized in that: The contact assembly (67) includes a pressure plate (671), which is fixedly connected to the output end of a hydraulic rod (66). A connecting block (673) is fixedly connected to one end of the pressure plate (671) away from the hydraulic rod (66). A slot (674) is provided in the middle of the end of the connecting block (673) away from the pressure plate (671). A spring plate (675) is fixedly connected inside the slot (674). A magnetic block (672) is fixedly connected to the outside of the pressure plate (671). There are two connecting blocks (673). A block body (677) is provided on the opposite side of the connecting blocks (673). A middle rod (676) is rotatably connected to the middle of the block body (677). The two ends of the middle rod (676) are respectively located inside the slots (674) of the two blocks (677). The block body (677) is elliptical.
5. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 1, characterized in that: The base (1) includes a platform (11), and a square plate (12) is fixedly connected to the top center of the platform (11). A central groove (18) is provided in the top center of the square plate (12). Multiple side holes are provided on the inner side of the central groove (18). A positioning groove (15) is provided on the top of the square plate (12). There are multiple positioning grooves (15), and the multiple positioning grooves (15) are evenly distributed on the top of the square plate (12) with the central groove (18) as the center.
6. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 5, characterized in that: A protrusion (62) at the bottom of a ring (61) near the base (1) is located inside the positioning groove (15). A positioning component (13) is fixedly connected to the top center of the square plate (12). A ring groove (16) is opened on the top of the square plate (12). There are multiple ring grooves (16). The multiple ring grooves (16) are evenly distributed on the square plate (12) with the middle groove (18) as the center. The ring groove (16) is located at the interval between the middle groove (18) and the positioning groove (15). A guide rod (17) is fixedly connected inside the ring groove (16). A fastener (14) is slidably connected inside the ring groove (16).
7. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 6, characterized in that: The fixing component (14) includes a movable block (143), which is located inside the annular groove (16). The guide rod (17) passes through the movable block (143), and the movable block (143) is slidably connected to the annular groove (16) through the guide rod (17). A compression spring (141) is provided inside the annular groove (16), and the two ends of the compression spring (141) are fixedly connected to the inner wall of the movable block (143) and the annular groove (16) respectively.
8. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 7, characterized in that: A side plate (144) is fixedly connected to the top of the movable block (143). The side plate (144) is perpendicular to the movable block (143). The side of the side plate (144) away from the compression spring (141) is inclined. A cylinder (142) is fixedly connected to the outside of the movable block (143). There are two cylinders (142), and the two cylinders (142) are symmetrically arranged with the movable block (143) as the center.
9. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 8, characterized in that: The positioning component (13) includes a circular plate (131), a return spring (133) is fixedly connected to the bottom center of the circular plate (131), the return spring (133) is located inside the intermediate groove (18), one end of the return spring (133) away from the circular plate (131) is fixedly connected to the bottom of the intermediate groove (18), an intermediate plate (135) is fixedly connected to the bottom of the circular plate (131), there are multiple intermediate plates (135), the multiple intermediate plates (135) are evenly distributed around the return spring (133), the intermediate plates (135) are located inside the side hole, and a through hole (134) is opened in the middle of the circular plate (131).
10. The experimental apparatus for testing the brittle fracture of rock in a non-uniform stress field according to claim 9, characterized in that: There are multiple through holes (134), and the multiple through holes (134) are evenly distributed around the reset spring (133). The through holes (134) and the annular groove (16) are located on the same vertical plane. The side plate (144) passes through the circular plate (131) through the through holes (134). The bottom of the circular plate (131) is fixedly connected to a retaining plate (132). There are multiple retaining plates (132), and the multiple retaining plates (132) are divided into four groups. The multiple retaining plates (132) in one group are symmetrically arranged on both sides of the through hole (134).