Pre-static load three-dimensional dynamic brazilian splitting experiment device and method based on TEHB system

Abstract

The present application relates to the technical field of rock dynamics test, and discloses a pre-static load three-dimensional dynamic Brazilian disk splitting test device and method based on a TEHB system, which comprises a true triaxial electromagnetic loading assembly, a sealed test box, a plurality of dynamic sealing assemblies, two plane force transmission cushion blocks, two arc-shaped force transmission cushion blocks and a collection assembly, the true triaxial loading assembly is provided with X and Y axis orthogonal waveguide rods, the X axis rod end is fixed with a plane force transmission cushion block, the Y axis rod end is provided with arc-shaped force transmission cushion blocks opposite to each other, and the two arc-shaped force transmission cushion blocks abut against the end surface and the side wall of a Brazilian disk sample respectively, the sealed box is provided with corresponding openings and is provided with dynamic sealing assemblies in a sliding sealing fit with the waveguide rods; a high-pressure liquid source is connected to an injection port at the top of the box to provide independent radial confining pressure, and the above structure forms a three-direction static load independent adjustable system, which can solve the problem that the existing device is difficult to simulate deep three-direction unequal bias stress, and truly restore the three-dimensional dynamic tensile failure law of rocks under dynamic disturbance.

Description

Technical Field

[0001] This invention relates to the field of rock dynamics testing technology, specifically to a pre-static load three-dimensional dynamic Brazilian splitting test apparatus and method based on the TEHB system. Background Technology

[0002] As deep mining and underground engineering projects such as deep-buried tunnels extend into deeper strata, deep rock masses are subjected to high geostress environments for extended periods. They are also susceptible to the coupled effects of dynamic disturbances such as blasting operations, rockbursts, and earthquakes. Localized tensile fracture of the rock mass is one of the core forms of disasters induced in deep engineering projects. The Brazilian splitting test is a standard test method for indirect tensile strength of rock recommended by the International Society for Rock Mechanics. The dynamic Brazilian splitting test is a core experimental means to reveal the evolution of dynamic tensile failure of rock under dynamic disturbances and to obtain the true dynamic tensile strength of rock. Its test results have important theoretical support and engineering guidance significance for the evaluation of the dynamic stability of deep rock masses and disaster prevention and control.

[0003] Currently, dynamic Brazilian splitting tests of rocks mostly rely on split Hopkinson bar systems. Typically, axial static initial stress is applied through a hydraulic servo loading system at both ends of the incident and transmission bars. To simulate confining pressure effects, the Brazilian disc specimen is placed in a closed confining pressure cylinder, and static confining pressure loading is achieved by injecting high-pressure fluid. However, this type of device has significant limitations: the high-pressure fluid fills the lateral and radial directions of the Brazilian disc specimen, providing only uniform lateral and radial confining pressure. The lateral and radial static loads on the disc specimen are the same and cannot be independently controlled, making it difficult to simulate the triaxially unequal initial geostress bias environment of deep rock masses, and failing to accurately reproduce the three-dimensional dynamic tensile mechanical response characteristics of deep rocks.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a pre-static load three-dimensional dynamic Brazilian splitting test device and method based on the TEHB system, which aims to solve the problem that the existing dynamic Brazilian splitting test of rock cannot truly reproduce the three-dimensional dynamic tensile mechanical response characteristics of deep rocks.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows: The pre-static load three-dimensional dynamic Brazilian splitting experimental setup based on the TEHB system includes: A true triaxial electromagnetic loading assembly, featuring an X-axis waveguide and a Y-axis waveguide; A sealed test chamber, mounted on the true triaxial electromagnetic loading assembly, is used to house the Brazilian disc sample. The sealed test chamber has a transverse opening and a longitudinal opening. The transverse opening is sealed to the X-axis waveguide rod, and the longitudinal opening is sealed to the Y-axis waveguide rod. The top of the sealed test chamber has an injection port for connecting to an external high-pressure liquid pump to inject high-pressure liquid into the sealed test chamber. Multiple dynamic sealing components are respectively disposed at the transverse opening and the longitudinal opening, and cooperate with the waveguide rod of the true triaxial electromagnetic loading component; Two planar force transmission pads are fixedly installed at the ends of the X-axis waveguide rod to abut against the end face of the Brazilian disc sample. Two arc-shaped force transmission pads are fixedly installed at the ends of the Y-axis waveguide rod, and the arc-shaped surfaces of the two arc-shaped force transmission pads are arranged opposite each other to abut against the side wall of the Brazilian disc sample. A data acquisition component, mounted on the true triaxial electromagnetic loading component and / or the sealed test chamber, is used to acquire mechanical and / or physical signals during the experiment. The load-bearing frame; the sealing test chamber is slidably mounted on the load-bearing frame, and the top wall of the sealing test chamber is an elastic top wall; An energy storage top cover is installed on the load-bearing frame and located at the top of the sealing test chamber; an energy storage cavity is provided inside the energy storage top cover, the energy storage cavity corresponds to the top wall of the sealing test chamber, and a pneumatic channel is provided at the top of the energy storage top cover, the pneumatic channel being connected to an external high-pressure air pump through a pipe.

[0007] Furthermore, the top of the energy storage cover is provided with a through hole, and a sealing locking component is provided inside the through hole. The top of the injection port of the sealing test chamber is provided with a perforated boss, which cooperates with the sealing locking component.

[0008] Furthermore, the sealing and locking assembly includes: A sealing ring is disposed on the inner surface of the through hole; A pneumatic steel ball clamp is disposed on the inner surface of the through hole and is connected to the energy storage cavity; the outer surface of the boss is provided with a sealing groove and a locking groove, the sealing groove cooperates with the sealing ring, and the locking groove cooperates with the pneumatic steel ball clamp.

[0009] Furthermore, the load-bearing frame includes: Support plate; Four tie rods are installed through the support plate and fixed to the support plate with nuts; the energy storage top cover is provided with four through holes, the top of the tie rods passes through the through holes and is fixed to the energy storage top cover with nuts; Multiple guide rails are mounted on the support plate; sliders are mounted on the guide rails, and sliding tables are mounted on the sliders; the sealing test chamber is connected to the multiple sliding tables. A driving component is disposed on the support plate and connected to one of the slides to drive the slide to slide vertically along the guide rail.

[0010] Furthermore, the dynamic sealing assembly includes: A sealing flange is provided on the surface of the sealing test chamber and located at the corresponding transverse opening or longitudinal opening; the sealing flange is provided with a receiving hole for the waveguide rod on the true triaxial electromagnetic loading assembly to pass through; An annular placement groove is provided on the inner wall surface of the receiving hole; An annular sealing bladder is disposed within the annular placement groove; The gas injection pipe has one end connected to the inside of the annular sealing bladder and the other end connected to an external air pressure pump through the sealing flange to inject gas into the annular sealing bladder, so that it seals against the waveguide rod on the true triaxial electromagnetic loading assembly.

[0011] Furthermore, the inner membrane of the sealed test chamber is connected at both ends to the longitudinal opening.

[0012] Furthermore, the acquisition component includes: An acoustic emission probe is mounted on the surface of the sealed test chamber.

[0013] An experimental method for a pre-statically loaded three-dimensional dynamic Brazilian splitting experimental setup based on the TEHB system, as described above, comprising: The Brazilian disc sample is placed in the center position inside the dynamic sealed test chamber and moved to the sample loading position of the true triaxial electromagnetic loading assembly. The X-axis waveguide and the Y-axis waveguide are controlled to extend into the sealed test chamber through the corresponding through openings, and a pre-tightening force is applied to clamp and fix the Brazilian disc sample. The dynamic sealing assembly is activated to dynamically seal the waveguide rod and the opening. High-pressure fluid is injected into the sealed test chamber through the injection port to apply a set radial confining pressure to the Brazilian disc sample and maintain the pressure for stability. The true triaxial electromagnetic loading component and the acquisition component are activated simultaneously to apply a controllable dynamic stress wave to the Brazilian disc sample and to acquire the mechanical signals and rock fracture acoustic emission signals throughout the test. The test is completed after the sample splits and breaks.

[0014] Furthermore, the mechanical signals and rock fracture acoustic emission signals collected throughout the entire testing process will then include: The pad effect correction coefficient is calculated based on the contact polar angle between the arc-shaped force transmission pad and the Brazilian disc sample. The incident wave, reflected wave and transmitted wave signals were collected by strain gauges on the waveguide rod, and the actual dynamic peak fracture load at the moment of splitting failure of the sample was calculated by the three-wave method. A full-scale numerical model with a 1:1 ratio to the test setup was established. By applying a unit static pressure load, the stress response at the center of the specimen was extracted. The transverse static pressure suppression coefficient and the effective confining pressure stress reduction coefficient were obtained by calibrating the stress-to-load ratio. Based on the pad effect correction coefficient, dynamic peak cracking load, experimentally applied X-axis static preload, Y-axis static preload and radial confining pressure, the true three-dimensional dynamic tensile strength at the center crack initiation point of the specimen is calculated.

[0015] Compared with the prior art, the beneficial effects of the present invention are: In this invention, planar force transmission pads and arc-shaped force transmission pads are respectively mounted on the X-axis and Y-axis orthogonal waveguide rods of the true triaxial electromagnetic loading assembly. Combined with a sealed test chamber with lateral and longitudinal openings and corresponding dynamic sealing components, and high-pressure fluid introduced through the injection port at the top of the chamber to provide independent radial confining pressure, a loading system with bidirectional static preload and radial confining pressure that is independently adjustable in three directions is constructed. This effectively solves the core problems of existing dynamic Brazilian splitting devices, which can only apply uniform radial confining pressure, have the same lateral and radial static load magnitudes and cannot be independently adjusted, and are difficult to simulate the triaxial unequal bias stress environment of deep rock masses. It can truly restore the three-dimensional dynamic tensile failure evolution law of deep rocks under dynamic disturbance coupling. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 This is a cross-sectional structural diagram of the sealing test chamber of the present invention.

[0018] Figure 3 This is a schematic diagram of the Brazilian sample and waveguide rod structure of the present invention.

[0019] Figure 4 This is a cross-sectional view of the sealed test chamber and the energy storage top cover of the present invention.

[0020] Figure 5This is a schematic diagram of the guide rail and slide structure of the present invention.

[0021] Figure 6 This is a schematic diagram of the dynamic sealing component structure of the present invention.

[0022] Figure 7 This is a flowchart of the pre-static load three-dimensional dynamic Brazilian splitting experimental method based on the TEHB system of the present invention.

[0023] The numbers in the diagram represent: 1. X-axis waveguide; 2. Y-axis waveguide; 3. Sealing test chamber; 31. Boss; 32. Sealing groove; 33. Locking groove; 4. Dynamic sealing assembly; 41. Annular sealing bladder; 42. Injection pipe; 5. Acquisition assembly; 6. Load-bearing frame; 61. Support plate; 62. Tie rod; 63. Guide rail; 64. Slider; 65. Slide table; 7. Energy storage top cover; 71. Energy storage chamber; 72. Pneumatic channel; 73. Through hole; 74. Pneumatic steel ball clamp; 8. Brazilian disc sample. Detailed Implementation

[0024] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In the description of this invention, TEHB is an abbreviation for True-triaxial Electromagnetic Hopkinson Bar.

[0028] In view of the shortcomings of the prior art, this embodiment provides a pre-static load three-dimensional dynamic Brazilian splitting experimental device and method based on the TEHB system, which can be referred to as follows: As attached Figure 1 and attached Figure 3 As shown, a pre-static load three-dimensional dynamic Brazilian splitting experimental device based on the TEHB system includes a true triaxial electromagnetic loading assembly, a sealed test chamber 3, multiple dynamic sealing components 4, two planar force transmission pads, two arc-shaped force transmission pads, and a data acquisition assembly 5. The true triaxial electromagnetic loading assembly is equipped with mutually perpendicular X-axis waveguides 1 and Y-axis waveguides 2, enabling bidirectional independent static preloading and dynamic stress wave loading. The sealed test chamber 3 is assembled in the working area of ​​the true triaxial electromagnetic loading assembly and is used to seal and accommodate the Brazilian disc sample 8. The sealed test chamber 3 has mutually perpendicular transverse and longitudinal openings, which are respectively sealed and adapted to the X-axis waveguides 1 and Y-axis waveguides 2. The top of body 3 is equipped with an injection port, which can be connected to an external high-pressure liquid pump to inject high-pressure fluid into the sealed test chamber 3 to apply radial confining pressure; multiple dynamic sealing components 4 are respectively assembled at the transverse and longitudinal opening positions, and cooperate with the waveguide rod to achieve dynamic reciprocating sealing; two planar force transmission pads are fixed to the end of the X-axis waveguide rod 1 to axially abut against the end face of the Brazilian disc sample 8 to achieve static preload loading in the X direction; two arc-shaped force transmission pads are symmetrically fixed to the end of the Y-axis waveguide rod 2, arranged in an arc shape and fitting against the side wall of the sample to achieve controllable static preload clamping in the Y direction; the acquisition component 5 is assembled on the loading component and the sealed chamber to acquire the mechanical and physical signals of the test throughout the process, and realize the full-process recording of test data.

[0029] Among them, the true triaxial electromagnetic loading component is an electromagnetic power loading body that differs from traditional hydraulic loading. It can achieve independent, high-precision, and adjustable static preload and dynamic disturbance load output in both X and Y directions, with fast load response speed and high control accuracy. The sealed test chamber 3 is a high-pressure confined sealed bearing cavity that provides an independent and controllable fluid confined pressure environment for the sample. The orthogonal opening structure of the horizontal and vertical axes is adapted to the bidirectional waveguide rod insertion operation. The dynamic sealing component 4 is the dynamic sealing core of the waveguide rod reciprocating motion, which can keep the cavity sealed during the sliding of the rod and prevent high-pressure fluid leakage. The planar force transmission pad is a uniform force transmission component on the end face, ensuring that the axial pressure in the X direction is uniformly applied to the end face of the sample. The arc-shaped force transmission pad is a special force transmission component adapted to the arc-shaped sidewall of the Brazilian disc, which can accurately fit the sample contour and achieve uniform lateral clamping and preloading in the Y direction. The acquisition component 5 is the test data sensing unit, which is responsible for the synchronous acquisition of mechanical and physical signals, providing data support for the analysis of the dynamic mechanical properties of rocks.

[0030] Specifically, during device assembly, the true triaxial electromagnetic loading assembly is fixed in place to ensure that the X-axis waveguide rod 1 and the Y-axis waveguide rod 2 are orthogonal and coaxially aligned. The sealed test chamber 3 is positioned at the center of the bidirectional waveguide rods, with the horizontal and vertical openings of the chamber corresponding to the X and Y-axis waveguide rods 2, respectively. A dynamic sealing assembly 4 is installed at the openings to achieve dynamic sealing after the rods are inserted. Planar force transmission pads are fixedly installed at the ends of the two X-axis waveguide rods 1, and arc-shaped force transmission pads are installed at the ends of the two Y-axis waveguide rods 2 to ensure that the arc-shaped pads are accurately aligned with the side wall curvature of the Brazilian disc sample 8. Finally, the various sensing components of the acquisition assembly 5 are arranged at the test points of the chamber and the loading assembly.

[0031] During the test, the Brazilian disc sample 8 is placed in the center of the box, the bidirectional waveguide rod extends, and independent static preload is applied to the sample from both the X and Y directions through the flat pad and the arc pad. Then, high pressure fluid is injected through the top injection port to apply radial confining pressure. Finally, dynamic stress wave is output through the electromagnetic loading component, and the acquisition component 5 is started simultaneously to complete the acquisition of test data in all dimensions.

[0032] Compared to existing technologies, traditional SHPB (Split Hopkinson Pressure Bar) dynamic Brazilian splitting test devices can only rely on high-pressure fluid to provide uniform, isotropic lateral and radial confining pressure. They cannot achieve independent and controllable static preload adjustment in both the X and Y directions. The lateral and radial static loads on the sample are completely identical, failing to simulate the unequal triaxial stress environment of deep rock masses. This results in significant differences between the test boundary conditions and the actual state of deep rock masses, making it impossible to reproduce the three-dimensional dynamic tensile mechanical response of rocks, and leading to poor data accuracy and engineering reference value. This new solution utilizes a bidirectional electromagnetic loading structure with orthogonal horizontal and vertical axes, combined with planar and arc-shaped differentiated force transmission pads and an independent fluid confining pressure cavity structure. This achieves independent triaxial control of static preload in the X and Y directions and radial fluid confining pressure, completely overcoming the limitations of traditional devices with uniform and unadjustable confining pressure and a single load dimension.

[0033] Through the above technical solutions, this application constructs a three-dimensional dynamic Brazilian splitting test structure with independent and controllable triaxial loads. It can accurately simulate the real occurrence environment of high ground stress and triaxial unequal bias pressure in deep rock masses, and truly restore the three-dimensional dynamic tensile fracture evolution process of deep rocks under dynamic disturbance. It effectively improves the authenticity and accuracy of dynamic tensile strength test data, and provides more practical test support for the evaluation of dynamic stability of deep rock masses and the prevention and control of rockburst disasters.

[0034] Furthermore, the planar force transmission pad can increase the contact area between the X-axis waveguide rod 1 and the end face of the sample, transforming the concentrated load at the rod end into a uniformly distributed load. This avoids the hard rod end directly damaging the end face of the sample, causing local stress concentration and premature abnormal failure of the sample. It ensures that the static preload in the X direction is uniformly applied to the entire sample along the axial direction, improving the stability and loading accuracy of the static preload. At the same time, the pad can be adapted to disc samples of different diameters, making replacement convenient and broadening the sample compatibility range of the device.

[0035] The arc-shaped force transmission pad precisely matches the curvature of the side wall of the Brazilian disc specimen, transforming the traditional line contact loading of the Brazilian splitting test into surface contact loading. This significantly reduces the stress concentration at the loading point, effectively preventing local crushing failure on the loading side of the specimen and ensuring that the specimen produces standard tensile splitting failure along the central diameter surface, conforming to the mechanical loading specifications of the Brazilian splitting test. At the same time, the arc-shaped fit can form a radial limit on the specimen, preventing the specimen from slipping and shifting during loading, ensuring coaxial alignment during bidirectional loading, and improving the repeatability and accuracy of test data. In addition, by replacing the arc-shaped pads with different curvatures, it can be adapted to test specimens of various diameters, further enhancing the adaptability of the device to different operating conditions.

[0036] By using differentiated pad structures to adapt to the loading patterns of the end face and sidewalls, and in conjunction with the X and Y bidirectional independent loading mechanisms, the precise application of triaxial unequal bias loads can be stably achieved, providing reliable loading boundary support for simulating the real stress environment of deep rock masses, and ensuring the accuracy of the mechanical boundaries of the three-dimensional dynamic Brazilian splitting test from a hardware perspective.

[0037] As attached Figure 2 As shown, the pre-static load three-dimensional dynamic Brazilian splitting experimental device based on the TEHB system also includes a load-bearing frame 6 and an energy storage top cover 7. The load-bearing frame 6 serves as the foundation for the entire machine, providing a stable installation and operating benchmark for each component. The sealed test chamber 3 is slidably assembled on the load-bearing frame 6, enabling precise vertical displacement adjustment. The top wall of the sealed test chamber 3 is designed as an elastic top wall, providing elastic buffering and pressure adaptive compensation capabilities. The energy storage top cover 7 is fixedly assembled on the upper part of the load-bearing frame 6, correspondingly positioned directly above the sealed test chamber 3. A sealed energy storage cavity 71 is opened inside the energy storage top cover 7, which is directly aligned with the elastic top wall of the chamber. A pneumatic channel 72 is provided at the top of the energy storage top cover 7, which can be connected to a high-pressure air pump through an external pipeline to achieve precise control of the air pressure inside the energy storage cavity 71 and energy storage pressure stabilization.

[0038] Among them, the load-bearing frame 6 is the rigid load-bearing base of the whole machine, which has high strength and high stability. It can offset the structural deformation and vibration interference caused by high pressure loading and dynamic impact, and ensure the coaxiality and stability of the test. The energy storage top cover 7 is the core component of pneumatic energy storage and stabilization. The internal energy storage cavity 71 can store compressible gas and use the elastic characteristics of pneumatic pressure to offset the instantaneous pressure fluctuation of high pressure fluid in the chamber, so as to achieve long-term pressure maintenance during the test process and solve the defect of unstable pressure in traditional confining pressure test. The bottom wall of the energy storage top cover 7 is an elastic bottom wall, which matches the top wall of the sealed test chamber 3.

[0039] Specifically, during the test preparation stage, the vertical height of the sealed test chamber 3 is adjusted by the sliding structure to complete the alignment and assembly of the sample; before pressurizing the chamber, a preset pressure gas is injected into the energy storage cavity 71 of the energy storage top cover 7 by a high-pressure air pump and the pressure is maintained; when the chamber is injected with high-pressure fluid to carry out the confining pressure test, the elastic top wall, in conjunction with the air pressure energy storage function of the top energy storage cavity 71, compensates for the pressure fluctuation of the fluid in the chamber in real time, maintains the confining pressure in the cavity stable throughout the process, and provides constant pressure boundary conditions for the test.

[0040] Through the above technical solutions, the sliding box structure improves the convenience of equipment assembly and sample disassembly, and reduces the difficulty of test operation. The pressure-stabilizing combination structure of the elastic top wall and the energy storage chamber 71 can, on the one hand, compensate for pressure loss and fluctuations during the test in real time, maintain constant internal pressure in the sealed box throughout the process, and effectively unify the pressure boundary conditions of each test round. On the other hand, at the moment of sample splitting failure, the elastic top wall can generate a buffer through its own elastic deformation, and together with the compressible air pressure space of the energy storage chamber 71, absorb the instantaneous impact energy, avoid the pressure rise in the chamber from impacting the sealing structure, sensing elements and loading rods, effectively protect the core components of the equipment, and prevent pressure change from interfering with the accuracy of mechanical data acquisition at the end of the test. Ultimately, it greatly improves the repeatability, stability and accuracy of test data, and ensures the safe and standardized conduct of three-dimensional dynamic splitting tests.

[0041] In this embodiment, as shown in the appendix Figure 4 As shown, the top of the energy storage top cover 7 has a through hole 73, and a sealing and locking component is installed inside the through hole 73 to achieve precise sealing and mechanical locking. The top of the injection port of the sealing test chamber 3 has an integrally formed perforated boss 31 structure. The outer diameter of the boss 31 is precisely matched with the size of the through hole 73 of the energy storage top cover 7, and can be vertically inserted into the through hole 73 to form a precise fit with the sealing and locking component inside the through hole 73, so as to achieve a tight seal and mechanical locking of the injection port, and take into account the functions of fluid injection channel connection and sealing and leak prevention under high pressure conditions, as well as structural loosening prevention.

[0042] Among them, the energy storage top cover 7 through hole 73 is the reference channel for the injection port alignment and provides precise limit for the insertion and assembly of the boss 31; the sealing and locking assembly is an integrated functional unit of high pressure sealing and mechanical locking, which has the dual functions of sealing and preventing leakage and structural locking to prevent loosening; the perforated boss 31 on the top of the box is a special structure for liquid injection docking. The central through hole 73 retains the high pressure fluid injection channel, and the outer contour is used to cooperate with the sealing and locking assembly to achieve positioning and sealing. It is different from the traditional simple pipe docking structure and is suitable for the harsh test conditions of high pressure and dynamic impact.

[0043] Specifically, during equipment assembly and alignment, as the sealing test chamber 3 slides vertically upward, the perforated boss 31 on the top of the chamber is precisely inserted into the through hole 73 of the energy storage top cover 7, completing radial alignment and axial insertion. After insertion, the sealing locking component inside the through hole 73 is activated, tightly fitting and locking against the outer wall of the boss 31, achieving a gapless seal and mechanical locking fixation between the boss 31 and the through hole 73. During fluid injection, high-pressure fluid enters the sealing test chamber 3 through the central through hole 73 of the boss 31, and the locking component continuously maintains a sealed and locked state, preventing pipe loosening and fluid leakage throughout the test. After the test is completed and pressure is released, the locking component is released from its limit, and the chamber can slide down and reset, completing a single test procedure.

[0044] Through the above technical solutions, the precise insertion structure of the boss 31 and the through hole 73 improves the efficiency and accuracy of equipment alignment and assembly. The built-in sealing and locking components can achieve long-term sealing and mechanical anti-loosening under high pressure dynamic conditions, completely eliminating leakage, pressure relief and loosening faults of the liquid injection interface, and stably maintaining the constant confining pressure inside the chamber, improving the safety and reliability of high pressure test conditions, and further ensuring the stability of the boundary conditions of the three-dimensional dynamic splitting test.

[0045] In this embodiment, as shown in the appendix Figure 4 As shown, the sealing and locking assembly includes a sealing ring and a pneumatic ball clamp 74. The sealing ring is fixedly embedded in the inner surface of the through hole 73 of the energy storage top cover 7 to achieve radial fit and sealing. The pneumatic ball clamp 74 is simultaneously assembled on the inner surface of the through hole 73 and is in air pressure communication with the energy storage cavity 71 inside the energy storage top cover 7. It relies on air pressure to drive the clamping and releasing actions. The outer surface of the boss 31 of the sealing test chamber 3 is correspondingly provided with a sealing groove 32 and a locking groove 33. The sealing groove 32 fits precisely with the sealing ring to achieve a leak-proof sealing surface. The locking groove 33 engages with the pneumatic ball clamp 74 to achieve axial mechanical locking and positioning, forming a pneumatically driven adaptive sealing and locking structure.

[0046] Among them, the sealing ring is a flexible sealing component on the contact surface, which can fill the assembly gap between the boss 31 and the through hole 73, block the leakage channel of high pressure fluid, and achieve static fit and seal; the pneumatic steel ball clamp 74 is a pneumatically driven adaptive mechanical locking unit. It adopts existing technology and relies on the pneumatic power of the energy storage chamber 71 to achieve automatic clamping and loosening without manual operation, which is suitable for automated test processes; the sealing groove 32 and locking groove 33 on the outer side of the boss 31 are positioning and matching reference structures, which can accurately limit the sealing ring and the steel ball clamping structure, ensure uniform sealing and firm locking, and effectively adapt to complex test conditions of high pressure and dynamic impact.

[0047] Specifically, during the test, the air pressure continuously drives the steel ball to remain locked, and the sealing ring continuously seals to prevent leakage; after the test ends and the pressure is released, the steel ball retracts and releases the lock, and the boss 31 can smoothly disengage from the through hole 73, completing the unlocking and reset.

[0048] In this embodiment, as shown in the appendix Figure 2 and attached Figure 5As shown, the load-bearing frame 6 includes a support plate 61, four tie rods 62, multiple guide rails 63, a slider 64, a slide table 65, and a driving component. The support plate 61 is a horizontal rigid load-bearing base plate, serving as the assembly reference for the entire frame. The four tie rods 62 vertically penetrate the support plate 61 and are locked in place with nuts. The top of the tie rods 62 penetrates the through hole of the energy storage top cover 7 and is locked in place, achieving a rigid connection and fixation between the support plate 61 and the energy storage top cover 7, forming a rigid explosion-proof load-bearing frame. Multiple sets of guide rails 63 are fixed parallel to the upper surface of the support plate 61. The slider 64 and the slide table 65 are slidably mounted on the guide rails 63. The sealing test chamber 3 is fixed on the slide table 65 and can slide smoothly vertically along the guide rails 63 with the slide table 65. The driving component is fixedly mounted on the support plate 61, and its power output end is connected to the slide table 65, providing a precise and controllable driving force for the vertical sliding of the chamber.

[0049] Among them, the support plate 61 is the bottom rigid bearing benchmark, ensuring the overall levelness and bearing stability of the equipment and offsetting the overturning moment generated by high pressure loading; the vertical tie rod 62 is the overall frame tensioning and fixing component, which rigidly locks the top energy storage cover 7 to the bottom support plate, improving the overall structural rigidity and avoiding structural deformation caused by high pressure testing; the guide rail 63, slider 64, and slide table 65 are high-precision vertical guiding and sliding units, ensuring smooth lifting and lowering of the box, accurate alignment, and no offset or jamming; the drive component is the box displacement precision drive unit, realizing automated vertical lifting and alignment without manual adjustment, improving assembly accuracy and operation efficiency.

[0050] Specifically, during frame assembly, the support plate 61 is horizontally fixed and leveled to ensure a flat and stable bearing surface. Four tie rods 62 are vertically inserted through the support plate 61, with the bottom secured by nuts and the tops passing through the through holes of the energy storage top cover 7 and locked in place, forming a high-strength, closed, rigid frame. Multiple sets of parallel guide rails 63 are precisely arranged on the support plate 61, and sliders 64 and slide tables 65 are assembled. The sealed test chamber 3 is fixed to the top surface of the slide table 65. Finally, the drive unit is fixed and aligned with the slide table 65 to complete the power connection. During testing, starting the drive unit can precisely drive the slide table 65 and the chamber to rise and fall smoothly vertically along the guide rails 63, automatically completing the alignment, sealing assembly, and reset separation of the chamber and the energy storage top cover 7. The entire process is smooth and precise, ensuring the coaxiality of the equipment assembly and the accuracy of the test.

[0051] In this embodiment, as shown in the appendix Figure 1 and attached Figure 6As shown, the dynamic sealing assembly 4 includes a sealing flange, an annular placement groove, an annular sealing bladder 41, and an air injection pipe 42. The sealing flange is fixedly assembled on the outer surface of the transverse and longitudinal openings of the sealing test chamber 3, and a receiving hole is opened in the center of the flange, allowing the waveguide rod to slide through and be assembled. The annular placement groove is annularly opened on the inner wall of the receiving hole, providing a precise installation position for the sealing component. The annular sealing bladder 41 is embedded and fixed inside the annular placement groove, and can be inflated to achieve a tight seal. One end of the air injection pipe 42 is connected to the inside of the annular sealing bladder 41, and the other end passes through the sealing flange and is connected to an external air pressure pump, which can precisely control the inflation amount of the sealing bladder and achieve dynamic adaptive sealing between the outer wall of the waveguide rod and the flange receiving hole.

[0052] Among them, the sealing flange is the installation benchmark and fixing base of the sealing assembly, realizing the rigid fixation of the overall sealing structure and the box opening, ensuring the accuracy and stability of the sealing position; the annular placement groove is the sealing bladder limiting installation structure, preventing the sealing bladder from slipping and shifting, ensuring the accuracy of the sealing position; the annular sealing bladder 41 is the adaptive flexible sealing core, which can adjust the degree of expansion according to the inflation volume, closely fit the outer wall of the waveguide rod, and adapt to the dynamic sealing requirements of the reciprocating sliding of the rod; the air injection pipe 42 is the air pressure regulation channel, providing controllable inflation power for the sealing bladder, realizing precise and adjustable sealing force, and taking into account both sealing performance and low friction slip characteristics.

[0053] Specifically, during assembly, the sealing flange is fixed to the horizontal and vertical openings of the housing, ensuring that the receiving hole and the opening are coaxially aligned. An annular sealing bladder 41 is embedded in the annular placement groove on the inner wall of the receiving hole. The air injection pipe 42 passes through the flange to complete the pipeline connection, and an external air pressure pump is connected. Before the test, a preset pressure gas is injected into the annular sealing bladder 41 through the air injection pipe 42, causing the sealing bladder to expand appropriately and fit tightly against the outer wall of the waveguide rod, sealing the assembly gap between the rod and the flange to achieve high-pressure leak-proof sealing. During the test, the waveguide rod slides back and forth to carry out the loading operation. The flexible sealing bladder can adapt to the sliding of the rod and fit itself, maintaining a sealed state throughout the process. At the same time, the inflatable flexible structure has low friction and will not hinder the precise displacement of the rod. After the test, the pressure can be released and the bladder can be contracted, which is convenient for equipment maintenance and rod reset.

[0054] Through the above technical solutions, the inflatable flexible sealing structure can adaptively fit the outer wall of the waveguide rod, and the sealing force is controllable and adjustable. While ensuring zero leakage sealing effect under high pressure conditions, it minimizes the sliding friction resistance of the rod, ensuring accurate loading displacement and smooth operation of the waveguide rod; it effectively reduces the wear of sealing components, extends service life, and improves the long-term operational stability of the equipment. At the same time, it adapts to the requirements of high-precision dynamic loading operations, ensuring the accuracy of test loading and boundary sealing.

[0055] In this embodiment, a cylindrical isolation membrane is provided inside the sealed test chamber 3. The membrane extends longitudinally along the chamber, and its two ends are sealed and fixed to the longitudinal openings on both sides of the chamber, forming a sample containing space independent of the high-pressure fluid cavity. The Brazilian disc sample 8 is housed in the center of the membrane. The Y-axis waveguide rod 2 extends into the membrane after passing through the longitudinal opening and abuts against the sample side wall. The membrane completely physically isolates the high-pressure fluid in the chamber from the sample and the loading end of the waveguide rod. The high-pressure fluid acts on the outer wall of the membrane and uniformly transmits radial confining pressure to the sample surface through the flexible deformation of the membrane, completely blocking the direct contact between the fluid and the sample and rod.

[0056] Among them, the cylindrical isolation diaphragm is the core component that combines sealing and isolation with flexible pressure transmission. It is made of high-strength, high-elasticity, and high-pressure resistant flexible sealing material, which has strong deformation following ability and can uniformly transmit fluid pressure without generating additional stress interference. The two ends of the diaphragm are sealed to the longitudinal opening to form a fully enclosed sample isolation cavity. This ensures that the radial confining pressure is uniformly transmitted to the entire circumference of the sample, and completely isolates the high-pressure fluid from contact with the rock sample and the end face of the waveguide rod. Unlike the traditional independent diaphragm structure that only covers the sample, this avoids the problems of fluid leakage along the gaps between the rods and fluid intrusion at the edge of the sample.

[0057] Specifically, during device assembly, the cylindrical diaphragm is first inserted into the sealed test chamber 3, and both ends of the diaphragm are connected to the longitudinal openings on both sides of the sealed test chamber 3, so that the diaphragm and the side wall of the chamber enclose an independent sample receiving cavity. The high-pressure fluid can only act on the cavity space outside the diaphragm. When placing the sample, the Brazilian disc sample 8 is placed in the center position inside the diaphragm. The Y-axis waveguide rod 2 passes through the longitudinal opening, extends into the diaphragm, and abuts against the arc-shaped pad on the side wall of the sample. The X-axis waveguide rod 1 passes through the transverse opening and corresponds to the end face of the sample. During the test loading, the high-pressure fluid is injected into the outer cavity of the chamber and acts on the outer wall of the diaphragm. The diaphragm contracts uniformly and transfers the confining pressure to the circumference of the sample. The fluid does not contact the sample or the rods throughout the process. During the dynamic splitting process, the diaphragm adapts to the deformation and expansion of the sample, and continuously maintains an isolated and sealed state.

[0058] Through the above technical solution, the fixed-end cylindrical diaphragm achieves complete physical isolation between the high-pressure fluid and the sample and loading rods. This ensures that the radial confining pressure is uniformly and losslessly transmitted to the sample surface without interfering with the mechanical boundary of the three-dimensional stress loading. It also completely prevents the high-pressure fluid from intruding into the rock fissures and changing the mechanical properties of the sample. At the same time, it can catch rock fragments after the sample splits, preventing rock fragments from scattering and wearing down the sealing structure and contaminating the cavity. This significantly reduces the equipment cleaning and maintenance costs, further improves the stability of the confining pressure loading and the accuracy of the test data, and extends the service life of the equipment.

[0059] In this embodiment, as shown in the appendix Figure 3As shown, the acquisition component 5 includes an acoustic emission probe, which is fixedly fitted to the outer surface of the sealed test chamber 3 at preset monitoring points. It can capture the acoustic emission signals generated by the initiation, expansion, penetration and final splitting failure of micro-cracks inside the rock sample in real time throughout the test process, and realize the acoustic signal monitoring of the entire rock fracture process.

[0060] Among them, the acoustic emission probe is the core sensing component for dynamic sensing of rock fracture. It has the characteristics of high sensitivity and high sampling frequency, and can capture the weak acoustic signals of microscale rock fracture. It can provide real-time feedback on the entire process of damage evolution and crack propagation inside the sample, making up for the deficiency of pure mechanical monitoring in characterizing the micro-fracture mechanism.

[0061] As attached Figure 7 As shown, this application also provides a pre-static load three-dimensional dynamic Brazilian splitting test method based on the TEHB system, which, based on the above-mentioned experimental setup, includes the following steps: Step S100: Place the Brazilian disc sample in the center position inside the dynamic sealed test chamber and move it to the sample loading position of the true triaxial electromagnetic loading assembly. Step S200: Control the X-axis waveguide and the Y-axis waveguide to extend into the sealed test chamber through the corresponding through openings, and apply a pre-tightening force to clamp and fix the Brazilian disc sample. Step S300: Activate the dynamic sealing assembly to dynamically seal the waveguide rod and the opening; Step S400: High-pressure fluid is injected into the sealed test chamber through the injection port to apply a set radial confining pressure to the Brazilian disc sample and maintain the pressure for stability. In step S500, the true triaxial electromagnetic loading component and the acquisition component are started simultaneously to apply a controllable dynamic stress wave to the Brazilian disc sample and to acquire the mechanical signals and rock fracture acoustic emission signals throughout the test. The test is completed after the sample splits and breaks.

[0062] Among them, the sample positioning and assembly process is the test benchmark construction stage, ensuring that the sample is centered and symmetrically stressed, avoiding test errors caused by assembly deviations; the bidirectional waveguide rod clamping process is the three-dimensional preload foundation, realizing independent pre-pressure positioning in both X and Y directions; the dynamic sealing process is the guarantee process for high-pressure confining pressure test, eliminating fluid leakage and pressure fluctuations; the high-pressure confining pressure holding process simulates the radial geostress environment of deep rock mass; the dynamic stress wave loading process simulates the dynamic disturbance effects of blasting, rockburst and other dynamic disturbances; and the multi-source signal synchronous acquisition process realizes the integrated recording of macroscopic mechanical and microscopic fracture data, ensuring the integrity and traceability of test data.

[0063] Specifically, during the experiment, the equipment self-inspection, sensor calibration, and pneumatic and hydraulic system debugging were first completed. The Brazilian disc sample 8, covered with a protective film, was placed in the center of the sealed test chamber 3. The height of the chamber was adjusted by the drive component of the load-bearing frame 6 to achieve precise positioning. The X and Y axis electromagnetic waveguide rods were controlled to extend synchronously and clamp the sample from both directions using differentiated force transmission pads to ensure uniform and symmetrical force. The dynamic sealing component 4 was activated to inflate and seal, closing all gaps in the rod assembly. An external high-pressure liquid pump was used to inject liquid into the chamber to increase the pressure. After reaching the preset radial confining pressure value, the pressure was stabilized to maintain the load. The pressure stabilization system of the energy storage top cover 7 was activated simultaneously to maintain constant pressure inside the chamber. Finally, the TEHB electromagnetic loading system was triggered to output dynamic stress waves to simulate deep dynamic disturbance loads. Mechanical acquisition and acoustic emission acquisition were activated simultaneously, and the test data were recorded throughout the process. Loading and acquisition were stopped after the sample split and failed, completing the entire standardized test procedure.

[0064] Through the above technical solutions, this test method has constructed a standardized, integrated, and highly controllable three-dimensional dynamic Brazilian splitting test process, which can accurately simulate the real occurrence conditions of deep rock mass with three-dimensional unequal bias stress and dynamic disturbance coupling. The test procedure is standardized, the boundary conditions are stable, and the repeatability is strong, which greatly improves the standardization and working condition realism of rock dynamic tensile test, and provides standardized and reliable test method support for the study of dynamic mechanical properties of deep rocks.

[0065] Specifically, in one implementation of this embodiment, the following steps are included after step S500: Step S501: Calculate the pad effect correction coefficient based on the contact polar angle between the arc-shaped force transmission pad and the Brazilian disc sample. Step S502: The incident wave, reflected wave and transmitted wave signals are collected by the strain gauge on the waveguide rod, and the actual dynamic peak fracture load at the moment of splitting failure of the sample is calculated by the three-wave method. Step S503: Establish a full-scale numerical model with the test device at a 1:1 scale. By applying a unit static pressure load, extract the stress response at the center of the specimen. The transverse static pressure suppression coefficient and the effective confining pressure stress reduction coefficient are obtained by calibrating the stress-to-load ratio. Step S504: Based on the pad effect correction coefficient, dynamic peak cracking load, static preload applied in the X-axis, static preload applied in the Y-axis, and radial confining pressure, the true three-dimensional dynamic tensile strength at the center crack initiation point of the specimen is calculated.

[0066] Among them, full-scale numerical modeling is the foundation for accurate stress calibration, which can realistically reproduce the structure of the test device and the load transfer law; stress reduction factor calibration is used to correct the stress transfer loss of confining pressure and static pressure loads; three-wave data processing is the core means to eliminate inertial errors of high strain rate systems; pad effect correction is used to offset the stress concentration and load deviation caused by the contact of the arc-shaped pad; multi-parameter superposition calculation is the final step to integrate multi-dimensional loads and output real mechanical parameters, so as to achieve accurate correction and realistic reproduction of test data.

[0067] Specifically, to avoid premature crushing and stress concentration disasters caused by the waveguide rod impacting the rock disk with an absolute plane (line contact) under extremely high strain rates, or even violating the assumption of central crack initiation, this invention sets a pad assembly (or flexible deformable patch) between the waveguide rod and the end of the sample, so that it forms an effective contact central angle at the moment of loading. The surface contact. According to George Hondros's derivation, the horizontal tensile stress generated at the exact center of the disk (the theoretical crack initiation point) for: ; P: The maximum load at which the specimen fails, in N; D: Diameter of the disc sample, in mm; t: The thickness of the specimen, in mm; : The polar angle of contact between the loading pad and the sample, in rad.

[0068] It is only related to the physical dimensions of the device and the contact geometry. When the concave curvature of the pad is fixed, the known physical curvature value is directly substituted for calculation; if a flat-cut pad is used (engineering simplification to an ideal line contact state), the extreme value is taken. →0, The value is set to 1. For standard ISRM (International Society for Rock Mechanics and Rock Engineering) specimens, the preferred equivalent contact angle of this invention is... The range is 20°-30°.

[0069] After obtaining the contact state of the pad, during the dynamic impact splitting stage, the dynamic fracturing force at both ends of the disc specimen cannot be directly derived from the quasi-static model. It must be corrected based on the one-dimensional stress wave propagation theory and the inertial effect of the tested material. Stress wave signals are acquired by high-frequency strain gauges on the waveguide rod, and the incident wave ε under dynamic force equilibrium is extracted. i (t), reflected wave ε r (t) and transmitted wave εt (t). Based on the three-wave method, the actual dynamic peak fracturing load P that the specimen experiences at instantaneous failure is derived. d(max) The calculation formula is as follows: ; In the formula, A0 and E0 are the cross-sectional area and Young's modulus of the waveguide rod, respectively. This three-wave method eliminates the interference of inertial forces under high strain rates, and obtains accurate dynamic load input for rock fracture.

[0070] After clarifying the geometric correction law and dynamic peak load of the pad, the characteristics of static pressure in the Y direction, dynamic and static combination in the X direction, and frictionless confining pressure provided by the sealed high-pressure liquid within the cavity were further analyzed. Using the superposition principle of linear elasticity, the true three-dimensional dynamic tensile strength at the central crack initiation point inside the specimen was established. Obtain the model, that is: ; In the formula: P x0 With P y0 These are the orthogonal bidirectional end-face static loads (X-axis static preload and Y-axis static preload) that are pushed in, pre-applied and controlled by the waveguide rod assemblies along the X and Y directions in the initial stage. P d(max) During the disturbance phase, the waveguide rod along the X direction is independently fired and propagated, and then connected to P. x0 Instantaneous dynamic peak crack-inducing load superimposed on the coaxial axis; P c The static high-pressure source environment pressure that fills the sealed cavity as the third principal stress medium; The model decouples the system's stress state in both space and time. The positive terms in the formula fully record the sequential loading failure effect of "first subjected to constant tension, then subjected to explosive tension" along the X-axis, while the negative terms summarize the network of retardation and compression effects on the initial cracking phenomenon transmitted from the Y-axis waveguide rod end and the Z-axis water cavity.

[0071] The methods for deriving the three-dimensional correction parameters K and η are as follows: Due to the complex three-dimensional spatial effects within real rock samples, and the inevitable fluid-structure interaction effect brought about by flexible sheath isolation and seepage prevention, the transverse static pressure suppression coefficient K and the effective confining pressure stress reduction coefficient η introduced in the formula are difficult to obtain completely through simple two-dimensional analytical solutions. This invention provides the following standardized inversion calibration method in the calculation: A full-scale three-dimensional numerical model (such as finite element analysis platforms like ABAQUS / LS-DYNA) with a 1:1 physical scale to the actual experimental setup and flexible membrane was established. Unit-value hydrostatic control loads were independently applied to the model in the X-direction and at the liquid contact surface. The model was solved, and the three-dimensional principal stress components generated at the center point of the specimen (i.e., the crack initiation point) were directly extracted. The ratio of this extracted stress value to the unit load applied at the boundary was used as the calibration constants K and η specific to this experimental setup for a particular specimen configuration. This method incorporates system-level size effects into the computational closed loop through inversion, allowing any measurement condition to be substituted into the above formula framework for accurate calculation of the three-dimensional dynamic tensile strength in deep rock environments.

[0072] Through the above technical solutions, this paper constructs a multi-level, multi-dimensional precision data correction system, which can comprehensively eliminate various systematic errors caused by equipment structure, loading conditions, and high strain rate test environment. It can effectively correct adverse effects such as pad block effect, confining pressure reduction, and inertial interference, accurately restore the true three-dimensional dynamic tensile strength of rock under the coupled conditions of triaxial bias and dynamic disturbance, and greatly improve the accuracy and reliability of test data. This provides high-precision data support for the study of dynamic mechanical mechanism of deep rock and the design of engineering disaster prevention and control parameters.

[0073] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the solutions disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

Claims

1. A pre-static load three-dimensional dynamic Brazilian splitting experimental apparatus based on the TEHB system, characterized in that, include: A true triaxial electromagnetic loading assembly, featuring an X-axis waveguide and a Y-axis waveguide; A sealed test chamber, mounted on the true triaxial electromagnetic loading assembly, is used to house the Brazilian disc sample. The sealed test chamber has a transverse opening and a longitudinal opening. The transverse opening is sealed to the X-axis waveguide rod, and the longitudinal opening is sealed to the Y-axis waveguide rod. The top of the sealed test chamber has an injection port for connecting to an external high-pressure liquid pump to inject high-pressure liquid into the sealed test chamber. Multiple dynamic sealing components are respectively disposed at the transverse opening and the longitudinal opening, and cooperate with the waveguide rod of the true triaxial electromagnetic loading component; Two planar force transmission pads are fixedly installed at the ends of the X-axis waveguide rod to abut against the end face of the Brazilian disc sample. Two arc-shaped force transmission pads are fixedly installed at the ends of the Y-axis waveguide rod, and the arc-shaped surfaces of the two arc-shaped force transmission pads are arranged opposite each other to abut against the side wall of the Brazilian disc sample. A data acquisition component, mounted on the true triaxial electromagnetic loading component and / or the sealed test chamber, is used to acquire mechanical and / or physical signals during the experiment. The load-bearing frame; the sealing test chamber is slidably mounted on the load-bearing frame, and the top wall of the sealing test chamber is an elastic top wall; An energy storage top cover is installed on the load-bearing frame and located at the top of the sealing test chamber; an energy storage cavity is provided inside the energy storage top cover, the energy storage cavity corresponds to the top wall of the sealing test chamber, and a pneumatic channel is provided at the top of the energy storage top cover, the pneumatic channel being connected to an external high-pressure air pump through a pipe; The top of the energy storage top cover is provided with a through hole, and a sealing locking component is provided inside the through hole. The top of the injection port of the sealing test chamber is provided with a perforated boss, which cooperates with the sealing locking component. The sealing and locking assembly includes: A sealing ring is disposed on the inner surface of the through hole; A pneumatic steel ball clamp is disposed on the inner surface of the through hole and is connected to the energy storage cavity; the outer surface of the boss is provided with a sealing groove and a locking groove, the sealing groove cooperates with the sealing ring, and the locking groove cooperates with the pneumatic steel ball clamp; The dynamic sealing assembly includes: A sealing flange is provided on the surface of the sealing test chamber and located at the corresponding transverse opening or longitudinal opening; the sealing flange is provided with a receiving hole for the waveguide rod on the true triaxial electromagnetic loading assembly to pass through; An annular placement groove is provided on the inner wall surface of the receiving hole; An annular sealing bladder is disposed within the annular placement groove; The gas injection pipe has one end connected to the inside of the annular sealing bladder and the other end connected to an external air pressure pump through the sealing flange to inject gas into the annular sealing bladder, so that it seals against the waveguide rod on the true triaxial electromagnetic loading assembly.

2. The pre-static load three-dimensional dynamic Brazilian splitting experimental apparatus based on the TEHB system according to claim 1, characterized in that, The load-bearing frame includes: Support plate; Four tie rods are installed through the support plate and fixed to the support plate with nuts; the energy storage top cover is provided with four through holes, the top of the tie rods passes through the through holes and is fixed to the energy storage top cover with nuts; Multiple guide rails are mounted on the support plate; sliders are mounted on the guide rails, and sliding tables are mounted on the sliders; the sealing test chamber is connected to the multiple sliding tables. A driving component is disposed on the support plate and connected to one of the slides to drive the slide to slide vertically along the guide rail.

3. The pre-static load three-dimensional dynamic Brazilian splitting experimental apparatus based on the TEHB system according to claim 1, characterized in that, The inner membrane of the sealed test chamber is connected at both ends to the longitudinal opening.

4. The pre-static load three-dimensional dynamic Brazilian splitting experimental apparatus based on the TEHB system according to claim 1, characterized in that, The acquisition component includes: An acoustic emission probe is mounted on the surface of the sealed test chamber.

5. An experimental method for a pre-statically loaded three-dimensional dynamic Brazilian splitting experimental apparatus based on the TEHB system as described in any one of claims 1-4, characterized in that, The experimental methods include: The Brazilian disc sample is placed in the center position inside the sealed test chamber and moved to the sample loading position of the true triaxial electromagnetic loading assembly. The X-axis waveguide and the Y-axis waveguide are controlled to extend into the sealed test chamber through the corresponding through openings, and a pre-tightening force is applied to clamp and fix the Brazilian disc sample. The dynamic sealing assembly is activated to dynamically seal the waveguide rod and the opening. High-pressure fluid is injected into the sealed test chamber through the injection port to apply a set radial confining pressure to the Brazilian disc sample and maintain the pressure for stability. The true triaxial electromagnetic loading component and the acquisition component are activated simultaneously to apply a controllable dynamic stress wave to the Brazilian disc sample and to acquire the mechanical signals and rock fracture acoustic emission signals throughout the test. The test is completed after the sample splits and breaks.

6. The experimental method of the pre-static load three-dimensional dynamic Brazilian splitting experimental apparatus based on the TEHB system according to claim 5, characterized in that, The mechanical signals and acoustic emission signals from rock fracture collected throughout the entire test process, followed by: The pad effect correction coefficient is calculated based on the contact polar angle between the arc-shaped force transmission pad and the Brazilian disc sample. The incident wave, reflected wave and transmitted wave signals were collected by strain gauges on the waveguide rod, and the actual dynamic peak fracture load at the moment of splitting failure of the sample was calculated by the three-wave method. A full-scale numerical model with a 1:1 ratio to the test setup was established. By applying a unit static pressure load, the stress response at the center of the specimen was extracted. The transverse static pressure suppression coefficient and the effective confining pressure stress reduction coefficient were obtained by calibrating the stress-to-load ratio. Based on the pad effect correction coefficient, dynamic peak cracking load, experimentally applied X-axis static preload, Y-axis static preload and radial confining pressure, the true three-dimensional dynamic tensile strength at the center crack initiation point of the specimen is calculated.

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