Thermal-hydraulic-mechanical coupling experimental device and test method based on dynamic true triaxial electromagnetic Hopkinson bar system loading

Abstract

This invention provides a thermal-hydraulic-mechanical coupling experimental apparatus and testing method based on a dynamic true triaxial electromagnetic Hopkinson bar system. The experimental apparatus includes an X-axis dynamic loading system, a Y-axis lateral anti-seepage loading system, a Z-axis normal static pressure servo-controlled loading system, a seepage system, a temperature control system, and a data monitoring and acquisition system. Relying on a dynamic true triaxial electromagnetic Hopkinson bar system, the apparatus innovatively integrates shear loading, temperature regulation, and seepage control modules to simulate the real-world conditions of deep rock masses subjected to dynamic perturbations, osmotic pressure, and temperature coupling. This apparatus overcomes the limitations of traditional experimental systems in achieving multi-field coupled loading under high-speed shear conditions, providing an experimental approach for studying the dynamic response of fractured rock masses under complex multi-field environments.

Description

Technical Field

[0001] The present invention relates to the field of high-end equipment manufacturing, and in particular to experimental equipment of a Hopkinson bar system and applications thereof. Background Art

[0002] In deep projects such as underground mineral mining, geological disposal of nuclear waste, and deep energy storage, the rock mass is in a multi-field coupled environment of temperature, fluid, and dynamic disturbances for a long time. A large number of joints and fissures are developed inside the rock mass, which greatly affects the stability of deep rock mass engineering. The mechanical properties of the fissure surface are affected by temperature and fluid. Any geological tectonic activity or dynamic disturbance such as engineering blasting and excavation will cause the rock mass to easily suffer shear instability along the fissure surface, which in turn will cause dynamic disasters, resulting in serious consequences such as casualties, equipment damage, and project shutdown. The research of patent number US20210318216A1 proposes a dynamic true triaxial electromagnetic Hopkinson bar system and testing method, which can realize true triaxial static loading and three-axis six-way synchronous dynamic stress wave loading, with the advantages of high precision, large amplitude, and strong repeatability.

[0003] At present, there is no test equipment that can simultaneously achieve dynamic shear and stable seepage loading. If the traditional static shear seepage structure is directly introduced into the dynamic loading system, problems such as the seepage path being disconnected during the shear process and the seepage structure interfering with the propagation of stress waves will occur.

[0004] In traditional static shear seepage structures, seepage channels are often rigidly connected and embedded inside the specimen or loading system. If they are directly introduced into a dynamic loading system, especially during bidirectional high-speed shear, the fractured rock specimen is prone to severe shear deformation, causing the channel structure to tear, break, or fail to seal due to relative displacement, thereby causing the seepage path to be interrupted.

[0005] Regarding the interference of seepage structure with stress wave propagation, in traditional static experiments, the seepage system is often integrated inside the loading shaft. However, in dynamic loading systems, if the seepage structure is set inside the loading rod, it will cause local discontinuity in the rod structure, resulting in sudden changes in wave impedance, interfering with the propagation and reflection of stress waves, and thus affecting the loading accuracy and test stability of the Hopkinson bar system.

[0006] In order to achieve coordinated control of temperature field and seepage field during high-speed shearing and provide a reliable experimental basis for the stability analysis of deep rock engineering, this application provides a thermal-hydraulic-mechanical coupling experimental device and testing method loaded by a dynamic true triaxial electromagnetic Hopkinson bar system. Summary of the Invention

[0007] To solve the problems in the prior art, the present invention provides a thermal-hydraulic-mechanical coupling experimental device based on a dynamic true triaxial electromagnetic Hopkinson bar system. The device is based on a dynamic true triaxial electromagnetic Hopkinson bar system, adopts electromagnetic pulse shear loading, and integrates temperature, seepage, and dynamic disturbance coordinated control. The overall system is arranged centrally and symmetrically around a fractured specimen. The experimental device includes an X-axis dynamic loading system, a Y-axis lateral anti-seepage loading system, a Z-axis normal static pressure servo control loading system, a seepage system, a temperature control system, and a data monitoring and acquisition system. The fractured specimen is artificially manufactured, and a through-crack is split along the specimen's central axis using a splitting device to obtain an artificial fractured specimen.

[0008] The X-axis dynamic loading system adopts electromagnetic pulse technology to realize uniaxial and bidirectional shear loading. The stress waves on both sides are synchronously transmitted to the shear end to simulate the complex dynamic disturbance environment of the rock mass in the engineering. During the loading process, the X-axis dynamic loading system applies stress waves synchronously to the bidirectional Hopkinson rods in the X-axis direction. In the X+ direction, the stress wave is transmitted to the fracture specimen through the X+ waveguide rod and the X+ shear end. In the X- direction, the stress wave is transmitted to the fracture specimen through the X- waveguide rod and the X- shear end, so that the fracture specimen is subjected to impact shear stress waves of equal amplitude and pulse width in the X-axis direction at the same time, inducing The Y-axis lateral anti-seepage loading system provides sealing and anti-seepage, stabilizes seepage conditions, and performs lateral constraints to fix the anti-seepage assembly and limit the shear direction. The Z-axis normal static pressure servo control loading system provides stable normal stress through servo control and adjusts the initial static shear state to adapt to the loading requirements under different confining pressure conditions. The seepage system adjusts the fluid permeation environment of the fracture surface to meet the simulation requirements of different seepage environments in deep rock masses. The temperature control system provides constant or dynamic temperature fields to achieve temperature environment loading. The data monitoring and acquisition system records experimental data.

[0009] As a further improvement of the present invention, the seepage system is a separated anti-seepage combined structure, including an anti-seepage block-spring-L-shaped block-buffer pad, providing independent water inlet and outlet channels; wherein the anti-seepage blocks are upper and lower anti-seepage blocks, the springs are upper and lower springs, the L-shaped blocks are upper and lower L-shaped blocks, and the buffer pads are upper and lower buffer pads; wherein the right side of the upper anti-seepage block and the left side of the upper L-shaped block are provided with threaded holes, the left side of the upper spring is connected to the upper anti-seepage block, the right side of the upper spring is connected to the upper L-shaped block, and the upper buffer pad is provided on the right side of the upper L-shaped block; the lower spring is respectively connected to the lower anti-seepage block and the lower L-shaped block, and the lower buffer pad is provided on the left side of the lower L-shaped block. As a further improvement of the present invention, the X-axis is equipped with an independent servo control system to apply X-axis static pressure to the fracture specimen; during dynamic loading, the X+ direction waveguide rod and the X- direction waveguide rod are equipped with resistance strain gauges.

[0010] As a further improvement of the present invention, the Y-axis lateral anti-seepage loading system integrates active and passive anti-seepage measures; active anti-seepage is achieved by relying on the independent hydraulic oil pump and servo loading control system of the Y-axis, the hydraulic oil pump provides stable pressure to drive the Y+ direction waveguide rod and the Y- direction waveguide rod, which is transmitted through the Y+ direction slider and the Y- direction slider and acts evenly on the Y+ direction sealing plate and the Y- direction sealing plate, the Y+ direction sealing plate slides forward along the built-in limiting structure of the Y+ direction sealing end, and the forward direction is pointing to the center direction of the device. Similarly, the Y- direction sealing plate slides forward along the built-in limiting structure of the Y- direction sealing end, and the forward direction is pointing to the center direction of the device. Finally, the Y- direction sealing plate and the Y+ direction sealing plate are tightly fitted on both sides of the Y-axis of the crack sample; for passive anti-seepage, an embedded anti-seepage strip is set on the front side of the Y+ direction sealing end, and the anti-seepage strip is embedded into the front side of the Y+ direction sealing end through the structure.

[0011] As a further improvement of the present invention, a Z-axis normal static pressure servo-controlled loading system adopts a position and pressure dual closed-loop control mode. The Z-direction loading method is the same as the Z+ direction loading method. The Z+ direction static load end and the Z- direction static load end are fixed to the Z+ direction waveguide rod and the end of the Z- direction waveguide rod close to the crack specimen; during Z-direction loading, the loading cylinder pushes the Z- direction waveguide rod, driving the Z- direction slider and the Z- direction roller to move upward, and the normal static load passes through the Z- direction pad and is finally evenly transmitted to the bottom surface of the crack specimen; Z+ direction balls and Z- direction balls are respectively installed on the Z+ direction roller and the Z- direction roller.

[0012] As a further improvement of the present invention, the seepage system adopts a steady-state method, and transverse flat slots are opened on the X+ direction shear end and the X- direction shear end close to the sample side to connect the fracture surface seepage field of the fracture sample. The servo motor draws the liquid into the water inlet, and passes through the insulated water inlet pipe, the water inlet channel, and the water inlet slot in turn. After forming a stable water flow at the slot and penetrating the fracture surface, it is discharged through the water outlet slot, the water outlet channel, the insulated water outlet pipe, and the water outlet.

[0013] As a further improvement of the present invention, the temperature control system adopts a separate high-temperature environment box, which consists of the right side of the high-temperature environment box and the left side of the high-temperature environment box. The main body is vertically fixed by diagonal braces and starts heating after closing. A heater is fixedly installed above the inner wall on the left side of the high-temperature environment box. The gas enters from the heating air inlet, the air circulates from top to bottom, and is discharged from the heating exhaust port. Temperature monitoring is collected in real time by the temperature sensor, and the target temperature and heating rate are set by the temperature controller.

[0014] A test method for a thermal-hydraulic-mechanical coupling experiment based on a dynamic true triaxial electromagnetic Hopkinson bar system loading is provided, which utilizes any of the above-described thermal-hydraulic-mechanical coupling experimental devices based on a dynamic true triaxial electromagnetic Hopkinson bar system loading, and comprises the following steps:

[0015] Step 1: Assemble the anti-seepage assembly, including the upper anti-seepage assembly and the lower anti-seepage assembly, and ensure that the connection is stable;

[0016] Step 2: Preliminary positioning of the crack specimen, and adjustment of the X-axis rod for centering and leveling;

[0017] Step 3: Apply Y-axis static pressure to fix the anti-seepage assembly to enhance the sealing performance;

[0018] Step 4: Install the high temperature environment box;

[0019] Step 5: Adjust the Z-axis static pressure, set the environmental chamber temperature and heating rate;

[0020] Step 6: Start the seepage system;

[0021] Step 7: Apply dynamic shear, collect and analyze data. According to the experimental design, start the X-axis dynamic loading system, control the transmitting cavities on both sides to synchronously input incident stress waves of equal amplitude and pulse width to the X+ waveguide rod and the X- waveguide rod, and conduct dynamic impact loading to the fracture sample, thereby completing the thermal-hydraulic-mechanical coupling test of the rock fracture surface based on dynamic electromagnetic loading. The shear loading adopts a bidirectional impact mode to achieve the synchronous action of opposite shear forces, accurately simulating the shear instability process of the fracture surface under complex working conditions. During the test, the stress changes, deformation characteristics, seepage state and temperature changes of the fracture sample are recorded in real time through strain gauges, seepage monitoring systems and temperature sensors. During the dynamic impact process, the strain gauges are used to collect the incident wave and reflected wave signals in the rod. When the dynamic loads applied on both sides of the sample are basically the same, it is considered that the impact loading process has reached a stress equilibrium state. Based on the one-dimensional stress wave propagation theory, the dynamic stress and dynamic strain parameters are calculated according to the following formula:

[0022]

[0023] Where E and A are the elastic modulus and cross-sectional area of ​​the stress wave loaded rod, respectively; A S is the shear surface area of ​​the test specimen; ε 左入射 and ε 左反射 are the incident strain signal and reflected strain signal monitored by the strain gauge from the stress wave loading rod on the left, ε 右入射 and ε 右反射 They are the incident strain signal and reflected strain signal monitored by the strain gauge from the stress wave loading rod on the right side.

[0024] As a further improvement of the present invention, in step 5, after reaching the set temperature, the temperature is kept constant for t hours to ensure uniform temperature inside the sample and form a stable thermal field environment, and t is 1.5 to 2.5 hours.

[0025] As a further improvement of the present invention, in step 6, the seepage system is connected to the insulated water inlet pipe and the water outlet pipe, which are respectively connected to the water inlet channel and the water outlet channel. The permeation medium uses solutions of different concentrations to simulate the real chemical environment of groundwater. The target permeation pressure is applied through the servo control system, and the flow change is monitored. When the outlet flow reaches a stable state, it indicates that a stable seepage field has been established inside the fracture sample. At this time, the normal static pressure, seepage and high-temperature coupled loading of the experimental sample have been completed, creating ideal initial conditions for dynamic disturbance loading.

[0026] The beneficial effects of the present invention are:

[0027] To address the problem of disconnection of the seepage path during shearing, this application proposes a separate upper and lower anti-seepage combination structure, which adopts an integrated flexible combination of anti-seepage block-spring-L-shaped block-buffer pad. While ensuring the independent and unobstructed flow of the water inlet and outlet channels, it can provide flexible limiting and displacement buffering during rapid shearing, and cooperate with the Y / Z-axis confining pressure to form an active sealing force, thereby effectively avoiding structural dislocation and path interruption caused by shearing, and ensuring the stable connectivity of the seepage path under dynamic working conditions.

[0028] To address the issue of seepage structures interfering with stress wave propagation, this application adopts a structural decoupling solution. Key components of the seepage system (including the water inlet channel 19, the water outlet channel 23, and the upper and lower anti-seepage assemblies) are integrally arranged outside the main force transmission path of the waveguide rod. This avoids adverse effects such as scattering and diffusion caused by structural discontinuities during stress wave propagation, structurally achieving both independence and compatibility between the seepage system and the loading system. This effectively avoids interference with the loading performance of the Hopkinson system. The upper anti-seepage assembly includes an upper anti-seepage block 26, an upper spring 27, an upper L-shaped block 25, and an upper buffer pad 28, while the corresponding lower anti-seepage assembly includes a lower anti-seepage block 30, a lower spring 31, a lower L-shaped block 29, and a lower buffer pad 32.

[0029] Transient dynamic disturbance shearing technology: This invention is based on a true triaxial electromagnetic Hopkinson bar system and adopts electromagnetic pulse loading technology to break through the limitation of the servo loading system in traditional shearing equipment that is difficult to simulate transient dynamic disturbances. It innovatively designs a bidirectional shear loading method. This method can simultaneously apply opposite shear forces to achieve X-axis bidirectional shear dynamic loading (strain rate 10 1 ~10 3 S -1 ), the coordinated and precise control of the Y-axis lateral seal and the Z-axis normal static load can truly simulate the shear instability process of the crack surface under complex working conditions, which is suitable for studying the shear failure mechanism of cracks caused by dynamic disturbances.

[0030] Multi-field collaborative loading system: This application constructs a temperature-seepage-dynamic disturbance three-field collaborative loading system, which breaks through the limitations of traditional static shear test multi-field coupling loading methods and can achieve high temperature, high osmotic pressure and dynamic shear loading under high strain rate dynamic disturbance conditions. The system integrates a temperature control unit, which can accurately control the test temperature to simulate a geothermal environment with a maximum temperature of 100°C; combined with a seepage control unit, it can achieve stable and controllable osmotic pressure loading. By collaboratively controlling temperature, seepage and dynamic shear parameters, the system can accurately simulate complex working conditions in depth, thereby realizing the shear response test of rock fracture surfaces under multi-field coupling, and providing a reliable experimental platform for the study of the mechanical properties of rock fracture surfaces under thermal-hydraulic-mechanical coupling. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a three-dimensional diagram of a dynamic true three-axis electromagnetic Hopkinson bar system in the prior art;

[0032] Figure 2 This is a schematic diagram of the thermal-hydraulic-mechanical coupling experimental device system and process based on dynamic electromagnetic loading of the present invention;

[0033] Figure 3A This is a module diagram of the thermal-hydraulic-mechanical coupling experimental device based on dynamic electromagnetic loading of the present invention;

[0034] Figure 3B This is a three-dimensional diagram of the thermal-hydraulic-mechanical coupling experimental device based on dynamic electromagnetic loading of the present invention;

[0035] Figure 3C 3D cross-sectional schematic diagram of the thermal-hydraulic-mechanical coupling experimental device based on dynamic electromagnetic loading of the present invention;

[0036] Figure 4A Schematic diagram of the seepage system before the test of the present invention;

[0037] Figure 4B Schematic diagram of the seepage system after the test of the present invention;

[0038] Figure 4C Schematic diagram of the flat notch at the X-direction shearing end of the present invention;

[0039] Figure 5A is a cross-sectional view (XZ plane) of the thermal-hydraulic-mechanical coupling experimental device of the present invention;

[0040] Figure 5B is a cross-sectional view (YZ plane) of the thermal-hydraulic-mechanical coupling experimental device of the present invention;

[0041] Figure 6 This is a schematic diagram of the three-dimensional section of the X-axis dynamic shearing of the present invention;

[0042] Figure 7 This is a three-dimensional cross-sectional diagram of the Y-axis lateral sealing and anti-seepage system of the present invention;

[0043] Figure 8 It is a three-dimensional cross-sectional schematic diagram of the Z-axis normal static load of the present invention;

[0044] Figure 9A 3D front view of the temperature environment box of the present invention;

[0045] Figure 9B 3D rear view schematic diagram of the temperature environment box of the present invention;

[0046] Figure 9C It is a three-dimensional schematic diagram of the left side of the temperature environment box of the present invention;

[0047] Figure 10A 3D cutaway diagram of the sealing end of the present invention ( Figure 10A The reason why the middle limit structure 55 is not fully displayed is that this figure adopts a cutaway view to highlight the internal structure of the Y-axis sealing end, and the limit structure 55 in the lower right corner is located outside the cutaway plane);

[0048] Figure 10B Schematic diagram of the structure of the limiting structure 55 of the present invention.

[0049] The names of the components corresponding to the numbers in the figure are as follows:

[0050] 1-X+ direction waveguide rod, 2-X- direction waveguide rod, 3-Y+ direction waveguide rod, 4-Y- direction waveguide rod, 5-Z+ direction waveguide rod, 6-Z- direction waveguide rod, 7- crack specimen, 8-X+ direction shear end, 9-X- direction shear end, 10-Y+ direction sealing end, 11-Y- direction sealing end, 12-Z+ direction static load end, 13-Z- direction static load end, 14- right side of high temperature environmental chamber (the high temperature here is about 100 degrees), 15- left side of high temperature environmental chamber, 16- base, 17- water inlet, 18- thermal insulation water inlet pipe, 19- water inlet channel, 20- water inlet trough, 21- water outlet, 22- thermal insulation water outlet pipe, 23- water outlet channel, 24- water outlet trough, 25- upper L-shaped block, 26- upper anti-seepage block , 27-upper spring, 28-upper buffer pad, 29-lower L-shaped block, 30-lower anti-seepage block, 31-lower spring, 32-lower buffer pad, 33-Z + direction slider, 34-Z + direction roller, 35-Z + direction pad, 36-Z- direction slider, 37-Z- direction roller, 38-Z- direction pad, 39-Y- direction slider, 40-Y- direction sealing plate, 41-Y + direction slider, 42-Y + direction sealing plate, 43-anti-seepage strip, 44-base roller, 45-Z + direction ball, 46-Z- direction ball, 47-thermostat, 48-temperature sensor, 49-heating air inlet, 50-locking device, 51-brace, 52-pulley, 53-heating exhaust port, 54-heater, 55-limiting structure. DETAILED DESCRIPTION

[0051] The following is a detailed introduction to this application with reference to the accompanying drawings, and further explanation of the testing method.

[0052] Specific embodiment 1: A thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading.

[0053] The present invention provides a thermal-hydraulic-mechanical coupling experimental device based on a dynamic true triaxial electromagnetic Hopkinson bar system, which breaks through the limitation of existing experiments that cannot simultaneously consider temperature, seepage and dynamic disturbances. The device is compatible with true triaxial electromagnetic Hopkinson bar systems (such as Figure 1 (as shown in Figure 2), electromagnetic pulse shear loading is used to address the shortcomings of existing shear tests in simulating dynamic disturbances, improving the accuracy of rock mass dynamic response studies. Furthermore, the integrated loading of temperature, seepage, and dynamic disturbances enables precise simulation of shear motion on rock fracture surfaces in complex environments, providing a reliable experimental method for analyzing the stability of deep rock mass engineering.

[0054] This application is based on a dynamic true triaxial electromagnetic Hopkinson bar system and serves as its extension module, mainly used to simulate the dynamic shear response characteristics of fractured rock (fracture specimen 7) under complex thermal-hydraulic-mechanical coupling. Figure 5A and Figure 5B , which is the cross-sectional structure of the thermal-hydraulic-mechanical coupling experimental device system. The entire system is arranged symmetrically around the crack specimen 7 to ensure uniform loading and accurate mechanical response.

[0055] like Figure 3A 、 Figure 3B 、 Figure 3C 、 Figure 4A 、 Figure 4B As shown, a thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading includes an X-axis dynamic loading system, a Y-axis lateral anti-seepage loading system, a Z-axis normal static pressure servo control loading system, a seepage system, a temperature control system, and a data monitoring and acquisition system.

[0056] The X-axis dynamic loading system utilizes electromagnetic pulse technology to achieve uniaxial, bidirectional, high-strain-rate shear loading. Stress waves on both sides are synchronously transmitted to the shear end, simulating the complex dynamic disturbance environment experienced by rock masses in engineering projects. The Y-axis lateral anti-seepage loading system provides sealing and anti-seepage, stabilizes seepage conditions, and provides lateral constraints to secure the anti-seepage assembly and limit the shear direction. The Z-axis normal static pressure servo-controlled loading system provides stable normal stress through high-precision servo control and can adjust the initial static shear state to accommodate loading requirements under varying confining pressures. The seepage system adjusts the fluid permeation environment at the fracture surface, including factors such as the type of seepage fluid and the seepage pressure, to meet the diverse requirements of simulating seepage environments in deep rock masses. The temperature control system provides constant or dynamic temperature fields to enable loading in high-temperature environments (the high temperature in this case is approximately 100°C, with a temperature range of room temperature to 100°C). The data monitoring and acquisition system integrates multi-channel synchronous acquisition modules for load, displacement, stress, strain, temperature, and flow, ensuring high-precision recording of experimental data.

[0057] The test rock sample is intended to be a 52mm×52mm×52mm cubic specimen (preferred). Each edge of the specimen is chamfered 2mm (maximum deformation 1%) to prevent the axial gaskets from squeezing and colliding with each other when the specimen is subjected to compression and deformation. Artificial fractures can be created by using a splitting device to create a through-crack along the specimen's central axis to obtain an artificial fracture specimen.

[0058] Figure 6 The figure shows a three-dimensional cross-section of the X-axis dynamic loading system. During loading, bidirectional Hopkinson bars in the X-axis direction simultaneously apply stress waves. These stress waves are transmitted to the fractured specimen 7 (in this embodiment, a fractured rock sample) via the X+ waveguide rod 1, the X- waveguide rod 2, the X+ shear end 8, and the X- shear end 9. This causes the fractured specimen 7 to experience impact shear stress waves of equal amplitude and pulse width in the X-axis direction, inducing shear slip. Simultaneously, an independent servo control system in the X-axis applies static X-axis pressure to the fractured specimen 7 to adjust the specimen's initial stress state and improve the stability of the shear loading process. During dynamic loading, resistance strain gauges are installed on the X+ waveguide rod 1 and the X- waveguide rod 2. These strain gauges monitor and record the strain-time response of the rods during the dynamic impact. Combined with stress wave propagation theory, dynamic mechanical response results, such as stress-time, stress-strain, and strain rate-time, are calculated to achieve precise testing.

[0059] like Figure 7 The figure shows the Y-axis lateral anti-seepage loading system, which integrates active and passive anti-seepage measures.

[0060] Active anti-seepage is achieved by the independent hydraulic oil pump and servo loading control system of the Y axis. The hydraulic oil pump provides stable pressure to drive the Y+ waveguide rod 3 and the Y- waveguide rod 4, which is transmitted through the Y+ slider 41 and the Y- slider 39 and evenly acts on the Y+ sealing plate 42 and the Y- sealing plate 40 made of silicone rubber. The Y+ sealing plate 42 is located along the built-in limit structure 55 of the Y+ sealing end 10 (see Figure 10A and Figure 10B ) slides forward, pointing toward the center of the device. Similarly, the Y-direction sealing plate 40 slides forward along the internal limiting structure 55 of the Y-direction sealing end 11, pointing toward the center of the device. Ultimately, the Y-direction sealing plate 40 and the Y+ direction sealing plate 42 are tightly attached to both sides of the Y axis of the crack specimen 7. The pressure applied by the sealing end is monitored in real time by precision displacement sensors and pressure sensors and precisely controlled by the servo system to ensure uniform loading and reliable sealing.

[0061] In addition to setting an embedded anti-seepage strip 43 on the front side of the Y+ direction sealing end 10 (the anti-seepage strip 43 is embedded in the front side of the Y+ direction sealing end 10 through the structure), passive anti-seepage also uses silicone rubber anti-seepage strips (plates) to seal the front side of the X+ direction shear end 8, the front side of the X- direction shear end 9, the front side of the upper anti-seepage block 26, and the front side of the lower anti-seepage block 30. All of the above front sides refer to the side close to the center of the device. Compared with other commonly used sealing materials, silicone rubber material has better heat resistance and can meet high-temperature sealing requirements.

[0062] Figure 8 This is a Z-axis normal static pressure servo-controlled loading system, employing a dual closed-loop position and pressure control mode. Taking Z-axis loading as an example, the loading cylinder pushes the Z-axis waveguide rod 6, driving the Z-axis slider 36 and Z-axis roller 37 upward. The normal static load is evenly transmitted to the bottom surface of the fracture specimen 7 via the Z-axis pad 38. The Z+ and Z-axis sliders 33 and 36 guide the stable lifting and lowering motion of the roller assembly during Z-axis loading, ensuring that the normal load is effectively transmitted to the roller along a predetermined path. Z+ and Z-axis balls 45 and 46 are mounted on the Z+ and Z-axis rollers 34 and 37, respectively, to provide low-friction normal support, ensuring that the deformation and displacement of the fracture specimen during the test are determined solely by the mechanical properties of the fracture surface. During loading, displacement and pressure signals are synchronously transmitted to the industrial computer and regulated by the servo control system, achieving high-precision loading control. The system's maximum pressure is set at 20 MPa, with a rated operating pressure of 16 MPa. The Z+ and Z-axis loading methods are the same.

[0063] The seepage system of the present invention is a separate anti-seepage combined structure, which is mainly composed of - anti-seepage blocks (upper anti-seepage block 26, lower anti-seepage block 30) - springs (upper spring 27, lower spring 31) - L-shaped blocks (upper L-shaped block 25, lower L-shaped block 29) - buffer pads (upper buffer pad 28, lower buffer pad 32). While providing independent water inlet and outlet channels, sealing is achieved through the silicone rubber anti-seepage plates (Y-direction sealing plate 40, Y+ direction sealing plate 42) at the front ends of the anti-seepage blocks. The springs and buffer pads respectively assume the limiting and buffering functions, effectively avoiding severe deformation or peeling of the rock, and ensuring that the seepage path continues to be connected during high-speed shearing.

[0064] like Figure 4A and Figure 4C As shown, the seepage system adopts the steady-state method. A transverse flat notch with a length of 50 mm, a depth of 10 mm, and a height of 2 mm is opened on the X+ direction shear end 8 and the X- direction shear end 9 close to the sample side to connect the fracture surface seepage field of the fracture sample 7 and ensure that the water flow forms a stable seepage environment at the notch. A servo motor is used to allow liquid with a maximum seepage pressure of 10 MPa to enter from the water inlet 17, pass through the insulated water inlet pipe 18, the water inlet channel 19, and the water inlet notch 20 in sequence, form a stable water flow at the notch and penetrate the fracture surface, and then be discharged through the water outlet notch 24, the water outlet channel 23, the insulated water outlet pipe 22, and the water outlet 21. The water pipe made of thermal insulation material can effectively prevent the liquid from changing in a high temperature environment. After the liquid is discharged, the flow rate is measured by a high-precision electronic balance and transmitted to the computer in real time through a signal line to realize automatic data acquisition.

[0065] Regarding the relationship between the force-moving notches and seepage: During the shear process, the seepage path is directly connected to the fracture surface through the seepage channels within the upper and lower anti-seepage blocks, rather than relying on shear end components. Therefore, relative displacement of the shear ends does not interfere with the seepage system. Furthermore, the flexible structure of the upper and lower anti-seepage assemblies and the Y / Z-axis confining pressure seal design absorb disturbances caused by relative movement, ensuring the continued connectivity and sealing of the fracture surface seepage path, and ensuring the accuracy of seepage data collection during the test phase. There is no need to maintain long-term stability of the seepage field after the test.

[0066] Figure 9A 、 Figure 9B and Figure 9CThe system is a temperature control system that uses a separate high-temperature environmental chamber, consisting of a right side 14 and a left side 15. The main body is fixed vertically by a diagonal brace 51 and can be closed to start heating. A heater 54 is fixed above the inner wall of the left side 15 of the high-temperature environmental chamber, with a maximum heating temperature of 100°C. Gas enters through the heating air inlet 49, circulates from top to bottom, and is discharged from the heating exhaust port 53. Temperature monitoring is collected in real time by temperature sensor 48, and the target temperature and heating rate are set by thermostat 47. The inner chamber is made of 304 stainless steel, and the outer chamber is made of cold-rolled steel plate, which has excellent thermal insulation properties. After 2 hours of insulation, the temperature inside the environmental chamber can be ensured to be uniform and stable. Specific implementation 2:

[0068] like Figure 2 As shown, the test method of the thermal-hydraulic-mechanical coupling experiment based on the dynamic true triaxial electromagnetic Hopkinson bar system loading includes the following steps:

[0069] 1. Assemble the anti-seepage assembly and ensure the connection is firm, such as Figure 4B 、 Figure 5A .

[0070] Before the experiment, the upper and lower anti-seepage assemblies were assembled, wherein the right side of the upper anti-seepage block 26 and the left side of the upper L-shaped block 25 were provided with threaded holes, and the left side of the upper spring 27 was connected to the upper anti-seepage block 26. The length, width and height of the upper anti-seepage block 26 were 50mm, 25mm and 25mm respectively (these data are preferred data and can be adjusted according to the sample size), and the right side of the upper spring 27 was connected to the upper L-shaped block 25. The function of the upper L-shaped block 25 is, on the one hand, to enhance the fit between the upper anti-seepage block 26 and the crack sample 7, and on the other hand, it can use the upper buffer pad 28 to buffer the impact load transmitted by the upper part of the crack sample sliding to the right during dynamic shearing, effectively absorb local energy, and prevent damage to the anti-seepage structure or adjacent components. Similarly, the lower structure is connected to the lower spring 31 with the lower anti-seepage block 30 and the lower L-shaped block 29 respectively, and the lower buffer pad 32 is placed on the left side of the lower L-shaped block 29 to ensure that the connection of each component is stable.

[0071] like Figure 6 、 Figure 7 、 Figure 8 As shown, the X+ shear end 8, X- shear end 9, Y+ sealing end 10, Y- sealing end 11, Z+ static load end 12, and Z- static load end 13 are sequentially fixed to the front ends (closest to the specimen) of the X+ waveguide rods 1, X- waveguide rods 2, Y+ waveguide rods 3, Y- waveguide rods 4, Z+ waveguide rods 5, and Z- waveguide rods 6. The six-way port components are made of the same titanium alloy as the waveguide rods to ensure structural rigidity and loading synchronization. These six-way port components are the X+ shear end 8, X- shear end 9, Y+ sealing end 10, Y- sealing end 11, Z+ static load end 12, and Z- static load end 13.

[0072] 2. Preliminary positioning of the specimen, and adjustment of the X-axis rods for centering and leveling.

[0073] like Figure 3A As shown, the support 16 is placed on the central platform (this central platform refers to the platform at the center of the dynamic true three-axis electromagnetic Hopkinson bar experimental device), the long side of the support 16 is adjusted to be parallel to the X-axis, and the center of the support 16 is coaxially aligned with the Z-direction waveguide rod 6, and the Z-direction waveguide rod 6 is raised by the hydraulic servo control, as shown in FIG. Figure 8 As shown, the Z-direction ball 46 on top of the Z-direction static load end 13 is located at the same horizontal plane as the base roller 44. A 50mm×50mm×10mm titanium alloy Z-direction spacer 38, a 52mm×52mm×52mm cubic crack specimen 7, and a 50mm×50mm×10mm Z+ direction spacer 35 are placed sequentially above the Z-direction static load end 13, ensuring alignment between the spacers and the crack specimen.

[0074] Place the assembled lower anti-seepage assembly (the lower anti-seepage assembly includes the lower anti-seepage block 30, the lower spring 31, the lower L-shaped block 29 and the lower buffer pad 32) on the pedestal 16, located on the left side above the pedestal 16 (near X+), and push the lower anti-seepage assembly so that the lower anti-seepage block 30 fits tightly with the crack sample 7, and the lower L-shaped block 29 fits tightly with the Z-direction pad 38. Subsequently, control the X+ direction waveguide rod 1, the X- direction waveguide rod 2, the X+ direction shear end 8 and the X- direction shear end 9 to move forward close to the side of the crack sample. Similarly, place the assembled upper anti-seepage assembly on the X- direction shear end 9 so that the upper anti-seepage block 26 fits tightly with the crack sample 7, and the upper L-shaped block 25 fits tightly with the Z+ direction pad 35, preliminarily fix the crack sample 7, and adjust the X-axis rods (X+ direction waveguide rod 1, X- direction waveguide rod 2) to center and level with the crack sample 7 to ensure uniform loading. Figure 8 , and then further fix the sample, adjust the Z+ direction waveguide rod 5 to move downward, so that the Z+ direction static load end 12 contacts the Z+ direction pad 35, and fix the position of the Z+ direction waveguide rod 5, adjust the Z- direction waveguide rod 6 upward, and apply a certain static load (within 2MPa) to ensure the stability of the crack sample 7 on the Z axis.

[0075] 3. Apply Y-axis static pressure to fix the anti-seepage assembly to enhance the sealing performance.

[0076] like Figure 3AAs shown, the right side 14 and the left side 15 of the high-temperature environmental box are respectively placed on both sides of the Y-axis of the base 16, and the Y-axis rods (Y+ direction waveguide rod 3 and Y- direction waveguide rod 4) are adjusted to gradually move the Y+ direction waveguide rod 3 and the Y- direction waveguide rod 4 forward (center), so that the Y+ direction sealing plate 42 and the Y- direction sealing plate 40 with a length, width and thickness of 50 mm, 50 mm and 10 mm respectively fit the crack sample 7. Subsequently, a certain static load (within 2 MPa) is applied to fix the position of the upper and lower anti-seepage assemblies, limit the shear direction, and improve the fit between the sealing plate and the crack sample to prevent leakage.

[0077] 4. Install a high temperature environment box.

[0078] The positions of the three-axis six-direction loading axes have been initially fixed, such as Figure 4A , respectively connect the insulated water inlet pipe 18 and the insulated water outlet pipe 22 to the interfaces of the water inlet channel 19 and the water outlet channel 23. Finally, install the high-temperature environmental box, push the pulley 52 to move the right side 14 and the left side 15 of the high-temperature environmental box closer to the base, and then connect the other sides of the insulated water inlet pipe 18 and the insulated water outlet pipe 22 to the water inlet 17 and the water outlet 21 respectively. After the connection is completed, close the left and right environmental boxes and close the locker 50 to ensure the sealing of the internal temperature field (such as Figure 9A , Figure 9B , Figure 9A It shows that the heat-insulated water outlet pipe 22 is connected to the water outlet 21. Figure 9B The insulated water inlet pipe 18 is shown connected to the water inlet 17).

[0079] 5. Adjust the Z-axis static pressure and set the environmental chamber temperature and heating rate.

[0080] After installation, the confining pressure of the fractured specimen 7 is adjusted according to the test requirements. The Z-axis normal static pressure servo-controlled loading system pushes the Z+ waveguide rod 5 and the Z- waveguide rod 6 to apply the target normal pressure (e.g., 5 MPa) to the fractured specimen 7. The target temperature (maximum 100°C), heating rate, and holding time are then entered into the temperature controller to initiate the heating process. Once the set temperature is reached, the temperature is held for two hours to ensure a uniform temperature within the specimen and a stable thermal environment.

[0081] 6. Start the seepage system.

[0082] The seepage system is connected to insulated inlet and outlet pipes, connected to the inlet and outlet channels, respectively. Solutions of varying concentrations can be used as the seepage medium to simulate the actual chemical environment of groundwater. A servo control system applies a target seepage pressure (up to 10 MPa) and monitors flow changes. When the outlet flow rate reaches a steady state, a stable seepage field has been established within the fractured specimen. At this point, the normal static pressure, seepage, and high-temperature coupled loading of the experimental sample are complete, creating ideal initial conditions for dynamic perturbation loading.

[0083] 7. Apply dynamic shear, collect and analyze data.

[0084] According to the experimental design, the X-axis dynamic loading system is started, and the transmitting cavities on both sides are controlled to synchronously input incident stress waves of equal amplitude and pulse width to the X+ direction waveguide rod 1 and the X- direction waveguide rod 2. The dynamic impact loading is then applied to the fracture sample 7, thereby completing the thermal-hydraulic-mechanical coupling test of the rock fracture surface based on dynamic electromagnetic loading. Figure 3C and Figure 4B As shown. The shear loading adopts a bidirectional impact mode, which can realize the synchronous action of opposite shear forces and accurately simulate the shear instability process of the crack surface under complex working conditions. During the test, the stress changes, deformation characteristics, seepage status and temperature changes of the crack specimen are recorded in real time through various sensing components such as strain gauges, seepage monitoring systems and temperature sensors. It should be noted that during the dynamic impact process, the strain gauges are used to collect the incident wave and reflected wave signals in the rod. When it is shown that the dynamic loads applied on both sides of the specimen are basically the same, it can be considered that the impact loading process has reached a stress equilibrium state. Based on the one-dimensional stress wave propagation theory, the dynamic stress, dynamic strain and other parameters can be calculated according to the following formula:

[0085]

[0086] Where E and A are the elastic modulus (107.8 GPa) and cross-sectional area (1250 mm2) of the stress wave loaded rod, respectively. 2 );A S is the shear surface area of ​​the test specimen (2500mm 2 );ε 左入射 and ε 左反射 are the incident strain signal and reflected strain signal monitored by the strain gauge from the stress wave loading rod on the left, ε 右入射 and ε 右反射 They are the incident strain signal and reflected strain signal monitored by the strain gauge from the stress wave loading rod on the right side.

[0087] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A thermal-hydraulic-mechanical coupling experimental device based on a dynamic true triaxial electromagnetic Hopkinson bar system, characterized by: The device is based on a dynamic true triaxial electromagnetic Hopkinson bar system, adopts electromagnetic pulse shear loading, and integrates temperature, seepage and dynamic disturbance coordinated control. The overall system is arranged in a central symmetric manner around the fracture sample (7). The experimental device includes an X-axis dynamic loading system, a Y-axis lateral anti-seepage loading system, a Z-axis normal static pressure servo control loading system, a seepage system, a temperature control system and a data monitoring and acquisition system. The fracture sample (7) is artificially manufactured. The fracture is split along the central axis of the sample using a splitting device to split a through crack to obtain an artificial fracture sample. The X-axis dynamic loading system adopts electromagnetic pulse technology to realize uniaxial and bidirectional shear loading. The stress waves on both sides are synchronously transmitted to the shear end, simulating the complex dynamic disturbance environment of the rock mass in the engineering. During the loading process, the X-axis dynamic loading system applies stress waves synchronously to the bidirectional Hopkinson rods in the X-axis direction. In the X+ direction, the stress wave is transmitted to the fracture specimen (7) through the X+ direction waveguide rod (1) and the X+ direction shear end (8). In the X- direction, the stress wave is transmitted to the fracture specimen (7) through the X- direction waveguide rod (2) and the X- direction shear end (9), so that the fracture specimen (7) is subjected to equal amplitude and equal pulse width in the X-axis direction at the same time. The impact shear stress wave induces shear slip; the Y-axis lateral anti-seepage loading system provides sealing and anti-seepage, stabilizes seepage conditions, and performs lateral constraints to fix the anti-seepage assembly and limit the shear direction; the Z-axis normal static pressure servo control loading system provides stable normal stress through servo control and adjusts the initial static shear state to adapt to the loading requirements under different confining pressure conditions; the seepage system adjusts the fluid penetration environment of the fracture surface to meet the simulation requirements of different seepage environments in deep rock masses; the temperature control system provides constant temperature or dynamic temperature field to realize temperature environment loading; the data monitoring and acquisition system records experimental data; The seepage system is a separated anti-seepage combined structure, comprising an anti-seepage block, a spring, an L-shaped block, and a buffer pad, providing independent water inlet and outlet channels; wherein the anti-seepage blocks are an upper anti-seepage block (26) and a lower anti-seepage block (30), the springs are an upper spring (27) and a lower spring (31), the L-shaped blocks are an upper L-shaped block (25) and a lower L-shaped block (29), and the buffer pads are an upper buffer pad (28) and a lower buffer pad (32); wherein the right side of the upper anti-seepage block (26) and the left side of the upper L-shaped block (25) are both provided with threaded holes, the left side of the upper spring (27) is connected to the upper anti-seepage block (26), the right side of the upper spring (27) is connected to the upper L-shaped block (25), and the upper buffer pad (28) is provided on the right side of the upper L-shaped block (25); the lower spring (31) is respectively connected to the lower anti-seepage block (30) and the lower L-shaped block (29), and the lower buffer pad (32) is provided on the left side of the lower L-shaped block (29).

2. The thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 1, characterized in that: The X-axis is equipped with an independent servo control system to apply X-axis static pressure to the crack specimen (7); during the dynamic loading process, resistance strain gauges are installed on the X+ direction waveguide rod (1) and the X- direction waveguide rod (2).

3. The thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 1, characterized in that: The Y-axis lateral anti-seepage loading system integrates active anti-seepage and passive anti-seepage measures; the active anti-seepage is achieved by relying on the independent hydraulic oil pump and servo loading control system of the Y-axis. The hydraulic oil pump provides stable pressure to drive the Y+ direction waveguide rod (3) and the Y- direction waveguide rod (4), which is transmitted through the Y+ direction slider (41) and the Y- direction slider (39) and acts evenly on the Y+ direction sealing plate (42) and the Y- direction sealing plate (40). The Y+ direction sealing plate (42) moves along the built-in limit structure (55) of the Y+ direction sealing end (10) to the Y+ direction sealing plate (42). Slide forward, and forward refers to the direction of the center of the device. Similarly, the Y-direction sealing plate (40) slides forward along the limiting structure (55) built into the Y-direction sealing end (11), and forward refers to the direction of the center of the device. Finally, the Y-direction sealing plate (40) and the Y+ direction sealing plate (42) are tightly fitted on both sides of the Y axis of the crack specimen (7); for passive anti-seepage, an embedded anti-seepage rubber strip (43) is set on the front side of the Y+ direction sealing end (10), and the anti-seepage rubber strip (43) is embedded in the front side of the Y+ direction sealing end (10) through the structure.

4. The thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 1, characterized in that: A Z-axis normal static pressure servo control loading system adopts a position and pressure dual closed-loop control mode. The Z-direction loading method is the same as the Z+direction loading method. The Z+direction static load end (12) and the Z-direction static load end (13) are fixed to the Z+direction waveguide rod (5) and the Z-direction waveguide rod (6) at one end close to the crack specimen (7). During Z-direction loading, the loading cylinder pushes the Z-direction waveguide rod (6), driving the Z-direction slider (36) and the Z-direction roller (37) to move upward. The normal static load passes through the Z-direction pad (38) and is finally evenly transmitted to the bottom surface of the crack specimen (7). Z+direction roller (34) and Z-direction roller (37) are respectively installed with Z+direction ball (45) and Z-direction ball (46).

5. The thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 1, characterized in that: The seepage system adopts a steady-state method. A transverse flat notch is provided on the X+ direction shear end (8) and the X- direction shear end (9) close to the sample side to connect the fracture surface seepage field of the fracture sample (7). The servo motor allows the liquid to enter from the water inlet (17), and pass through the insulated water inlet pipe (18), the water inlet channel (19), and the water inlet notch (20) in sequence. After forming a stable water flow at the notch and penetrating the fracture surface, the liquid is discharged through the water outlet notch (24), the water outlet channel (23), the insulated water outlet pipe (22), and the water outlet (21).

6. The thermal-hydraulic-mechanical coupling experimental device based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 1, characterized in that: The temperature control system adopts a separate high-temperature environment box, which consists of the right side (14) and the left side (15) of the high-temperature environment box. The main body is fixed vertically by a diagonal support (51) and starts heating after closing. A heater (54) is fixed above the inner wall of the left side (15) of the high-temperature environment box. Gas enters from the heating air inlet (49), circulates from top to bottom, and is discharged from the heating exhaust port (53). Temperature monitoring is collected in real time by the temperature sensor (48), and the target temperature and heating rate are set by the temperature controller (47).

7. A test method for a thermal-hydraulic-mechanical coupling experiment based on a dynamic true triaxial electromagnetic Hopkinson bar system loading, utilizing the thermal-hydraulic-mechanical coupling experimental apparatus based on a dynamic true triaxial electromagnetic Hopkinson bar system loading according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Assemble the anti-seepage assembly, including the upper anti-seepage assembly and the lower anti-seepage assembly, and ensure that the connection is stable; Step 2: Preliminary positioning of the crack specimen (7), and adjustment of the X-axis rod for centering and leveling; Step 3: Apply Y-axis static pressure to fix the anti-seepage assembly to enhance the sealing performance; Step 4: Install the high temperature environment box; Step 5: Adjust the Z-axis static pressure, set the environmental chamber temperature and heating rate; Step 6: Start the seepage system; Step 7: Apply dynamic shear, collect and analyze data; According to the experimental design, the X-axis dynamic loading system is started, and the transmitting cavities on both sides are controlled to synchronously input incident stress waves of equal amplitude and pulse width to the X+ waveguide rod (1) and the X- waveguide rod (2), and the fracture sample (7) is subjected to dynamic impact loading through transmission, thereby completing the thermal-hydraulic-mechanical coupling test of the rock fracture surface based on dynamic electromagnetic loading. The shear loading adopts a bidirectional impact mode to achieve the synchronous action of the opposite shear forces, and accurately simulate the shear instability process of the fracture surface under complex working conditions. During the test, the stress changes, deformation characteristics, seepage state and temperature changes of the fracture sample are recorded in real time through a variety of sensor components such as strain gauges, seepage monitoring systems and temperature sensors. During the dynamic impact process, the incident wave and reflected wave signals in the rod are collected through the strain gauges. When the dynamic loads applied on both sides of the sample are basically the same, it is considered that the impact loading process has reached a stress equilibrium state. Based on the one-dimensional stress wave propagation theory, the dynamic stress and dynamic strain parameters are calculated according to the following formula: Where E and A are the elastic modulus and cross-sectional area of ​​the stress wave loaded rod, respectively; A S is the shear surface area of ​​the test specimen; ε 左入射 and ε 左反射 are the incident strain signal and reflected strain signal monitored by the strain gauge from the stress wave loading rod on the left, ε 右入射 and ε 右反射 They are the incident strain signal and reflected strain signal monitored by the strain gauge from the stress wave loading rod on the right side.

8. The test method of thermal-hydraulic-mechanical coupling experiment based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 7, characterized in that: In step 5, after reaching the set temperature, keep warm for t hours to form a stable thermal field environment, where t is 1.5 to 2.5 hours.

9. The test method of thermal-hydraulic-mechanical coupling experiment based on dynamic true triaxial electromagnetic Hopkinson bar system loading according to claim 7, characterized in that: In step 6, the seepage system is connected to the insulated inlet and outlet pipes, which are connected to the inlet and outlet channels respectively. Solutions of different concentrations are used as the infiltration medium to simulate the real chemical environment of groundwater. The target seepage pressure is applied through the servo control system, and the flow changes are monitored. When the outlet flow reaches a stable state, it indicates that a stable seepage field has been established inside the fracture sample. At this time, the normal static pressure, seepage and high-temperature coupled loading of the experimental sample have been completed, creating ideal initial conditions for dynamic disturbance loading.

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