SHPB device for simulating deep rock ground temperature, water pressure and stress coupling environment, control system and test method

Abstract

The invention discloses an SHPB device for simulating a deep rock ground temperature, water pressure and stress coupling environment, the SHPB device comprises an SHPB assembly, a water pressure loading assembly, a water bath heating circulation assembly and a mounting flat plate, the SHPB assembly is mounted at the upper end of the mounting flat plate, the water pressure loading assembly is arranged in the middle of the SHPB assembly, and the water bath heating circulation assembly is mounted on the mounting flat plate. A water outlet of the water pressure loading assembly is connected with a reflux inlet of the water bath heating circulation assembly through a connecting pipe, a water inlet of the water pressure loading assembly is connected with a water outlet of the water bath heating circulation assembly through a connecting pipe, and an outlet water stop valve is installed at a water outlet pipe opening of the water pressure loading assembly. An inlet water stop valve is installed at a water inlet pipe opening of the water pressure loading assembly. Simulation of the ground temperature, water pressure and stress coupling environment of the deep rock is achieved, and the technical problem that dynamic mechanical response tests of the deep rock mass under high prestress, high water pressure and high ground temperature in the real environment are difficult to achieve through existing dynamic equipment is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of deep rock dynamics, and in particular to a SHPB device, a control system and a test method for simulating the coupled environment of geothermal temperature, water pressure and stress of deep rock. Background Art

[0002] With the continuous depletion of shallow coal resources in China, coal mining has gradually advanced to the deep. In the mining environment, it faces a complex environment of high geothermal temperature, high karst water pressure, high ground stress and strong mining disturbance, which is extremely prone to frequent occurrence of major engineering dynamic disasters such as coal and gas outburst, earthquake, rock burst, and large deformation of roadway surrounding rock. Therefore, the deep coal mining environment and the rock mass engineering response have the characteristics of "three highs and one strong disturbance", which pose a huge challenge to the safe mining of deep coal resources. Based on this, studying and mastering the dynamic response mechanism of deep rock mining and the disaster prevention and control technology under the conditions of high geothermal temperature, high karst water pressure, high ground stress and strong mining disturbance have important scientific and engineering practical significance for ensuring the safe and efficient mining of coal resources.

[0003] At present, most of the research on the above engineering problems focuses more on the static mechanical properties and failure mechanisms of deep rock under geothermal temperature - water pressure - stress, while for the research on the dynamic mechanical properties of deep rock, only single or two or three coupled environment simulations are realized in simulating the environment where deep rock is located, and the coupled simulation of "three highs and one strong disturbance" multiple environments is not considered. There is no report on the research of the dynamic mechanical properties and fracture laws of rock mass under the coupled action of deep geothermal temperature - water pressure - stress. Only the Hopkinson pressure bar (SHPB) is used to simulate the strong disturbance load environment, and an improved confining pressure device is used to inject water into it to simulate the high karst water pressure and high ground stress environment where deep rock is located. For example, a rock dynamic performance test device and method under the coupling of high water pressure and high ground stress are disclosed in the patent number: CN112964540B, and the influence factors of high geothermal temperature environment are often not considered in this invention.

[0004] In view of this, it is necessary to invent a SHPB device and a test method for simulating the coupled environment of deep rock geothermal temperature - water pressure - stress, which is very necessary for studying the dynamic characteristics and fracture laws of rock under the coupled environment of deep geothermal temperature - water pressure - stress. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, an object of the present invention is to provide a SHPB device and a test method for simulating the coupled environment of geothermal temperature, water pressure and stress of deep rock, which realizes the simulation of the coupled environment of geothermal temperature, water pressure and stress of deep rock, and solves the technical problem that existing dynamic equipment is difficult to realize the dynamic mechanical response test of deep rock mass under the real environment of high prestress, high water pressure and high geothermal temperature.

[0006] In a first aspect, a Split Hopkinson Pressure Bar (SHPB) device for simulating the coupled environment of deep rock geothermal temperature, water pressure, and stress proposed by the present invention includes an SHPB assembly, a water pressure loading assembly, a water bath heating and circulating assembly, and a mounting plate. The SHPB assembly is installed at the upper end of the mounting plate. The water pressure loading assembly is arranged in the middle of the SHPB assembly. The water outlet of the water pressure loading assembly is connected to the return port of the water bath heating and circulating assembly through a connecting pipe. The water inlet of the water pressure loading assembly is connected to the water outlet of the water bath heating and circulating assembly through a connecting pipe. An outlet stop valve is installed at the water outlet pipe of the water pressure loading assembly, and an inlet stop valve is installed at the water inlet pipe of the water pressure loading assembly.

[0007] Preferably, the SHPB assembly includes an axial actuator, an impact bar, an incident bar, and a transmission bar. The water pressure loading assembly is arranged in the middle of the upper end of the mounting plate. There is a barrel on one side of the mounting plate where the water pressure loading assembly is located. The impact bar is slidably connected to the outlet of the barrel. The incident bar is connected to the side wall of the water pressure loading assembly close to the barrel. The axial actuator is located on the side of the mounting plate away from the barrel. The transmission bar is connected to the side wall of the water pressure loading assembly close to the axial actuator. The incident bar and the transmission bar both penetrate the side wall of the water pressure loading assembly and are slidably connected to the side wall of the water pressure loading assembly. The impact bar, the incident bar, and the transmission bar are on the same straight line. The incident bar and the transmission bar are both fixed to the mounting plate through multiple groups of mounting baffles. Connecting holes for the incident bar and the transmission bar to slide through are provided in the middle of multiple groups of the mounting baffles. An axial pressure retaining ring is sleeved in the connecting hole of the mounting baffle close to the impact bar side. The outer diameter of the axial pressure retaining ring close to the impact bar side is adapted to the aperture of the connecting hole, and the outer diameter of the axial pressure retaining ring away from the impact bar side is larger than the aperture of the connecting hole.

[0008] Preferably, the water pressure loading assembly includes a confining pressure actuator. A bearing expansion and contraction hole is provided in the side wall of the water pressure loading assembly. The bearing rod of the confining pressure actuator is connected to the bearing expansion and contraction hole.

[0009] Preferably, threaded holes are provided at the four corners of the mounting baffle. The mounting baffle is connected with axial pressure pull rods through the threaded holes. An adjusting bolt for adjusting the distance between the axial pressure pull rod and the axial actuator is provided at the connection between the mounting baffle and the axial pressure pull rod.

[0010] Preferably, a circular water stop cover one and a circular water stop cover two are respectively installed on the two side walls of the water pressure loading assembly along the arrangement direction of the incident bar.

[0011] Preferably, strain gauges for collecting stress electrical signal waveform data are installed on the side walls of the incident bar and the transmission bar.

[0012] Preferably, a plurality of support seats are provided at the bottom of the installation flat plate, and the lower ends of the support seats are fixed through installation bases.

[0013] Secondly, a control system proposed by the present invention includes any one of the above SHPB devices for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress, and further includes an axial pressure confining pressure servo controller. The axial pressure confining pressure servo controller includes an oil cylinder, a loading box body and a display controller II. The oil cylinder is arranged below the loading box body, and the display controller II is installed at the upper end of the loading box body. The signal output end of the display controller II is connected to the signal input end of the oil cylinder. The oil cylinder is provided with an axial pressure oil inlet and outlet control end and a confining pressure inlet and outlet control end. The axial pressure oil inlet and outlet connection end of the axial actuator is connected to the axial pressure oil inlet and outlet control end through an axial pressure hydraulic line, and the confining pressure oil inlet and outlet connection end of the confining pressure actuator is connected to the confining pressure inlet and outlet control end through a confining pressure hydraulic line.

[0014] Preferably, a temperature sensor for detecting temperature and a water pressure sensor for detecting water pressure are installed inside the water pressure loading assembly. The signal output ends of the temperature sensor and the water pressure sensor are connected to the signal input end of the display controller II.

[0015] Thirdly, a test method for an SHPB device proposed by the present invention includes any one of the above SHPB devices for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress. The method steps are as follows:

[0016] S1. Preparation stage: Pretreat the rock sample to be measured. After the pretreatment is completed, place the rock sample to be measured in the water pressure loading assembly and clamp both ends by the incident bar and the transmission bar respectively, and then execute step S2;

[0017] S2. Water body heating: The water bath heating circulation assembly works to make the water body of the water bath heating circulation assembly reach the target value, and then execute step S3;

[0018] S3. Applying stress: The axial actuator works to make the stress load received by the rock sample to be measured reach the target value, and then execute step S4;

[0019] S4. Simulating geothermal temperature: Open the inlet water stop valve and the outlet water stop valve, and the water body in the water bath heating circulation assembly enters the water pressure loading assembly. The temperature in the water pressure loading assembly is stabilized at the target value, and then execute step S5;

[0020] S5. Applying water pressure: Close the inlet water stop valve and the outlet water stop valve, open the confining pressure actuator, and change the volume inside the water pressure loading assembly by the telescopic movement of the bearing bar of the confining pressure actuator. When the water pressure reaches the target value, execute step S6;

[0021] S6. Start the SHPB component, launch the impact rod through the barrel, and the impact rod impacts the incident rod to apply a dynamic load to the rock sample to be measured, thereby realizing the environment of rock burst stress received by deep rocks.

[0022] S7. Collect the test block: After the stress signal wave acquisition is completed, the axial actuator releases the axial pressure and the confining pressure actuator releases the water pressure, and the rock sample to be measured is taken out.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The water pressure loading component is connected to the water bath heating and circulating component to realize two influencing conditions of water pressure and ground temperature. At the same time, the axial pressure system of the SHPB component provides axial pressure, so that axial pressure can be applied to the rock sample to be measured, and multi-field coupling dynamic mechanical property experiments under different impact loads can be carried out, solving the technical problem that it is difficult for existing dynamic equipment to realize dynamic mechanical response tests under high prestress, high water pressure and high ground temperature in the real environment of deep rock masses.

[0025] (2) The axial pressure and confining pressure servo controller in the control system receives the changes in temperature and water pressure in the water pressure loading component, and adjusts the stress load output by the axial actuator, so as to ensure that under the premise that the simulated water pressure and ground temperature meet the test requirements, the simulated stress load also meets the test requirements. Description of the Drawings

[0026] In the drawings:

[0027] Figure 1 is a schematic structural diagram of an SHPB device for simulating the coupling environment of ground temperature, water pressure and stress of deep rocks proposed by the present invention;

[0028] Figure 2 is a view of the water pressure loading component in the direction close to the confining pressure actuator of the present invention;

[0029] Figure 3 is a view of the water pressure loading component in the direction away from the confining pressure actuator of the present invention;

[0030] Figure 4 is a sectional view of the water pressure loading component proposed by the present invention;

[0031] Figure 5 is a schematic structural diagram of the axial pressure and confining pressure servo controller proposed by the present invention;

[0032] Figure 6 is a schematic structural diagram of the water bath heating and circulating component proposed by the present invention.

[0033] In the figure: 1 - SHPB component, 2 - water pressure loading component, 3 - water bath heating and circulating component, 4 - axial actuator, 5 - axial and confining pressure servo controller, 6 - mounting base, 7 - support base, 8 - base fixing bolt, 9 - mounting plate, 10 - mounting baffle, 11 - axial compression tie rod, 12 - impact rod, 13 - barrel, 14 - axial compression retaining ring, 15 - adjusting bolt, 16 - incident bar, 17 - transmission bar, 18 - circular seal cover I, 19 - adiabatic water pipe, 20 - inlet water stop valve, 21 - water pressure display, 22 - wire interface I, 23 - circular water stop cover I, 24 - confining pressure actuator, 25 - wire, 26 - confining pressure hydraulic line, 27 - axial compression hydraulic line, 28 - axial compression oil inlet and outlet connection end, 29 - hydrothermal circulation box, 30 - water body circulation cavity, 31 - hydrothermal circulation inlet and outlet, 32 - display controller I, 33 - strain gauge, 34 - oil cylinder, 35 - transmission pipeline, 36 - power switch, 37 - loading box, 38 - display controller II, 39 - controller switch, 40 - wire interface II, 41 - axial compression oil inlet and outlet control end, 42 - confining pressure inlet and outlet control end, 43 - water inlet fixing plate, 44 - water inlet fixing bolt, 45 - water inlet pipe orifice, 46 - outlet water stop valve, 47 - outlet pipe orifice, 48 - outlet water fixing bolt, 49 - outlet water fixing plate, 50 - circular water stop cover II, 51 - circular seal cover II, 52 - bearing bar, 53 - ferrule joint, 54 - rock sample to be measured, 55 - sealing ring, 56 - screw, 57 - internal water outlet hole. Detailed implementation mode

[0034] Refer to Figure 1, an SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress, comprising an SHPB assembly 1, a water pressure loading assembly 2 and a mounting plate 9. The SHPB assembly 1 includes an axial actuator 4, an impact rod 12, an incident rod 16 and a transmission rod 17. The water pressure loading assembly 2 is arranged in the middle of the upper end of the mounting plate 9. A barrel 13 is provided on one side of the mounting plate 9 where the water pressure loading assembly 2 is located. The impact rod 12 is slidably connected to the outlet of the barrel 13. The incident rod 16 is connected to the side wall of the water pressure loading assembly 2 close to the barrel 13. The axial actuator 4 is located on the side of the mounting plate 9 away from the barrel 13. The transmission rod 17 is connected to the side wall of the water pressure loading assembly 2 close to the axial actuator 4. Both the incident rod 16 and the transmission rod 17 penetrate through the side wall of the water pressure loading assembly 2 and are slidably connected to the side wall of the water pressure loading assembly 2. The impact rod 12, the incident rod 16 and the transmission rod 17 are on the same straight line. Both the incident rod 16 and the transmission rod 17 are fixed to the mounting plate 9 through multiple groups of mounting baffles 10. Connection holes for the sliding connection of the incident rod 16 and the transmission rod 17 are provided in the middle of the multiple groups of mounting baffles 10. An axial pressure retaining ring 14 is sleeved in the connection hole of the mounting baffle 10 close to the impact rod 12. The outer diameter of the side of the axial pressure retaining ring 14 close to the impact rod 12 is adapted to the aperture of the connection hole, and the outer diameter of the side of the axial pressure retaining ring 14 away from the impact rod 12 is larger than the aperture of the connection hole.

[0035] Obviously, based on the above, the impact force can be simulated by firing the impact rod 12 through the barrel 13, the water pressure can be simulated by the water pressure loading assembly 2, and the stress load can be simulated by the axial actuator 4, so as to realize the simulation of the impact force, water pressure and stress load. At the same time, when the axial actuator 4 outputs a load, the axial pressure retaining ring 14 abuts against the mounting baffle 10, the impact rod 12 impacts the axial pressure retaining ring 14, and the axial pressure retaining ring 14 can transmit the impact force to the incident rod 16, driving the incident rod 16 to displace together towards the water pressure loading assembly 2.

[0036] Specifically, referring to Figure 1 and Figure 4 , a circular sealing cover one 18 is provided at the connection between the incident rod 16 and the water pressure loading assembly 2, and a circular sealing cover two 51 is provided at the connection between the transmission rod 17 and the water pressure loading assembly 2. Both the circular sealing cover one 18 and the circular sealing cover two 51 are fixed to the water pressure loading assembly 2 through mounting screws 56. Sealing rings 55 for preventing water leakage are provided inside both the circular sealing cover one 18 and the circular sealing cover two 51.

[0037] In this embodiment, referring to Figure 1 , Figure 2 and Figure 3, including a water bath heating circulation component 3. The water outlet of the water pressure loading component 2 is connected to the return port of the water bath heating circulation component 3 through a connecting pipe, and the water inlet of the water pressure loading component 2 is connected to the water outlet of the water bath heating circulation component 3 through a connecting pipe. An outlet water stop valve 46 is installed at the water outlet pipe orifice 47 of the water pressure loading component 2, and an inlet water stop valve 20 is installed at the water inlet pipe orifice 45 of the water pressure loading component 2.

[0038] Specifically, the connecting pipe adopts a heat-insulating water pipe 19 to prevent heat loss. The water outlet and water inlet of the water pressure loading component 2 are respectively provided with a water outlet fixing plate 49 and a water inlet fixing plate 43. The water outlet fixing plate 49 is fixed to the connecting pipe through a water outlet fixing bolt 48, and the water inlet fixing plate 43 is fixed to the connecting pipe through a water inlet fixing bolt 44.

[0039] Obviously, based on the above, by controlling the opening of the outlet water stop valve 46 and the inlet water stop valve 20, the water body reaching the target temperature in the water bath heating circulation component 3 can enter the water pressure loading component 2 to achieve the purpose of simulating the geothermal temperature.

[0040] Specifically, referring to Figure 6 , the water bath heating circulation component 3 includes a hydrothermal circulation box body 29. A water body circulation cavity 30 is opened inside the hydrothermal circulation box body 29. A hydrothermal circulation inlet and outlet 31 communicating with the heating area is opened on the side wall of the water body circulation cavity 30. And a display controller 32 is installed on the top of the hydrothermal circulation box body 29. The display controller 32 controls the heating power of the heating area to heat the water body medium to the target temperature. The water bath heating temperature range is between 0 and 100 °C.

[0041] In this embodiment, referring to Figure 2 and Figure 4 , the water pressure loading component 2 includes a confining pressure actuator 24. A bearing expansion hole is opened on the side wall of the water pressure loading component 2. The bearing rod 52 of the confining pressure actuator 24 is connected to the bearing expansion hole.

[0042] Obviously, based on the above, the confining pressure actuator 24 changes the volume inside the water pressure loading component 2 through the expansion and contraction of the bearing rod 52, so as to adjust the water pressure inside the water pressure loading component 2.

[0043] In this embodiment, referring to Figure 1 , threaded holes are opened at the four corners of the installation baffle 10. The installation baffle 10 is connected with a shaft pressure pull rod 11 through the threaded holes. An adjusting bolt 15 for adjusting the distance between the shaft pressure pull rod 11 and the axial actuator 4 is provided at the connection between the installation baffle 10 and the shaft pressure pull rod 11.

[0044] Obviously, based on the above, when the axial actuator 4 applies a load, the axial compression tie rod 11 is used for limiting the position to prevent the axial actuator 4 from applying an excessive load, which may cause potential safety hazards due to the direct rupture of the rock sample 54 to be measured. At the same time, according to the size of the rock sample 54 to be measured, the distance between the axial compression tie rod 11 and the axial actuator 4 can be adjusted by the adjusting bolt 15, so that the incident rod 16 and the transmission rod 17 can clamp the rock sample 54 to be measured.

[0045] In this embodiment, referring to Figure 2 and Figure 3 , circular water stop caps I 23 and circular water stop caps II 50 are respectively installed on the two side walls of the water pressure loading assembly 2 along the arrangement direction of the incident rod 16.

[0046] Obviously, based on the above, the rock sample 54 to be measured can be placed inside the water pressure loading assembly 2 by opening the circular water stop caps I 23 and circular water stop caps II 50, which is convenient for fixing the rock sample 54 to be measured and collecting the rock sample 54 to be measured after the test.

[0047] In this embodiment, referring to Figure 1 , strain gauges 33 for collecting stress electrical signal waveform data are installed on the side walls of the incident rod 16 and the transmission rod 17.

[0048] Obviously, based on the above, specific parameter information of the SHPB assembly 1 can be collected through the strain gauges 33.

[0049] In this embodiment, referring to Figure 1 , multiple groups of support seats 7 are provided at the bottom of the mounting plate 9, and mounting bases 6 are provided at the lower ends of the support seats 7. The mounting bases 6 are fixed to the ground by base fixing bolts 8.

[0050] Obviously, based on the above, the setting of the support seats 7 and the mounting bases 6 ensures a stable working platform for the test.

[0051] As another embodiment of the present application, referring to Figure 1 and Figure 5 , this embodiment proposes a control system, which includes any one of the above SHPB devices for simulating the coupled environment of deep rock geothermal temperature, water pressure, and stress, and further includes an axial confining pressure servo controller 5. The axial confining pressure servo controller 5 includes an oil cylinder 34, a loading box 37, and a display controller II 38. The oil cylinder 34 is provided below the loading box 37, and the display controller II 38 is installed at the upper end of the loading box 37. The signal output end of the display controller II 38 is connected to the signal input end of the oil cylinder 34. The oil cylinder 34 is provided with an axial oil inlet and outlet control end 41 and a confining pressure inlet and outlet control end 42. The axial oil inlet and outlet connection end 28 of the axial actuator 4 is connected to the axial oil inlet and outlet control end 41 through an axial hydraulic line 27, and the confining pressure oil inlet and outlet connection end of the confining pressure actuator 24 is connected to the confining pressure inlet and outlet control end 42 through a confining pressure hydraulic line 26.

[0052] Obviously, based on the above, the display controller II 38 can adjust the bearing bar telescopic amount of the confining pressure actuator 24 and the output load of the axial actuator 4 by controlling the output oil pressure of the oil cylinder 34, so as to achieve the purpose of adjustable simulated water pressure and stress load.

[0053] Specifically, a power switch 36 and a controller switch 39 are also provided at the loading box 37, which are convenient for controlling the opening and closing of the axial and confining pressure servo controller 5.

[0054] In this embodiment, referring to Figure 1 and Figure 2 , a temperature sensor for detecting temperature and a water pressure sensor for detecting water pressure are installed inside the water pressure loading assembly 2. The signal output ends of the temperature sensor and the water pressure sensor are connected to the signal input end of the display controller II 38.

[0055] Obviously, based on the above, the temperature and water pressure information in the water pressure loading assembly 2 is fed back to the display controller II 38 in real time, and the display controller II 38 adjusts the bearing bar telescopic amount of the confining pressure actuator 24 and the output load of the axial actuator 4 in real time, so as to ensure that the simulated geothermal temperature, water pressure and stress meet the test standards.

[0056] Specifically, a wire interface I 22 is provided at the top of the water pressure loading assembly 2. Both the temperature sensor and the water pressure sensor are connected to the wire interface I 22 through wires. The wire interface I 22 is connected to the wire interface II 40 at the axial and confining pressure servo controller 5 through a wire 25. At the same time, a water pressure display 21 for displaying water pressure is also installed at the top of the water pressure loading assembly 2.

[0057] As another embodiment of the present application, this embodiment proposes a test method for the SHPB device, including any one of the above SHPB device schemes for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress. The method steps are as follows:

[0058] S1. Preparation stage: Pretreat the rock sample to be measured 54. After the pretreatment is completed, place the rock sample 34 to be measured inside the water pressure loading assembly 2, and clamp both ends by the incident bar 16 and the transmission bar 17 respectively, and then execute step S2;

[0059] In this embodiment: The polished rock sample to be tested 54 is placed in a water bath before the test and fully saturated with water in the corresponding heated water body for 48 hours to ensure that the internal temperature of the rock sample 54 to be tested reaches the corresponding geothermal temperature, improving the accuracy and reliability of the test. By opening the circular water stop cover 1 23 and placing it in the water pressure loading assembly 2, first use the axial jack to adjust the distance between the incident rod 16 and the transmission rod 17. There is a small gap between the rock sample 54 to be tested and the incident rod 16 and the transmission rod 17. Then apply axial pressure through the axial pressure and confining pressure servo controller 5. The axial pressure actuator 4 pushes the transmission rod 17 to gradually clamp the rock sample 54 to be tested, and finally fix the circular water stop cover 1 23.

[0060] S2. Water body heating: The water bath heating and circulation assembly 3 operates to make the water body of the water bath heating and circulation assembly 3 reach the target value, and then execute step S3;

[0061] In this embodiment: The water body circulation chamber 30 in the water bath heating and circulation assembly 3 is filled with water, and the heating system in the water bath heating and circulation assembly 3 is started to make the water body reach the corresponding temperature.

[0062] S3. Applying stress: The axial actuator 4 operates to make the stress load on the rock sample 34 to be tested reach the target value, and then execute step S4;

[0063] In this embodiment: Through the axial pressure and confining pressure servo controller 5 and the axial actuator 4 pushing the transmission rod 17 to gradually clamp the rock sample 54 to be tested, start to apply axial pressure to make the rock sample 54 to be tested receive the set stress load, simulating the influence of the maximum horizontal principal stress on deep rocks.

[0064] S4. Simulating geothermal temperature: Open the inlet water stop valve 20 and the outlet water stop valve 46. The water body in the water bath heating and circulation assembly 3 enters the water pressure loading assembly 2, and the temperature in the water pressure loading assembly 2 stabilizes at the target value, and then execute step S5;

[0065] In this embodiment: The water body at the corresponding temperature in the water bath heating and circulation assembly 3 is transported to the periphery of the rock sample 54 to be tested through the heat-insulating water pipe 19. Start the circulation button in the water bath heating and circulation assembly 3. By checking the temperature value on the axial pressure and confining pressure servo controller 5, make the temperature change of the water body around the rock sample 54 to be tested stable at the test value. At the same time, the heated water circulates back and forth for a certain time to exhaust the internal air, facilitating the application of water pressure to improve the accuracy of the test.

[0066] S5. Applying water pressure: Close the inlet water stop valve 20 and the outlet water stop valve 46, open the confining pressure actuator 24, and make the volume in the water pressure loading assembly 2 change through the expansion and contraction of the bearing bar 52 of the confining pressure actuator 24. When the water pressure reaches the target value, execute step S6;

[0067] S6. Start the SHPB component, fire the impact rod 12 through the barrel 13, and the impact rod 12 impacts the incident rod 16 to apply a dynamic load to the rock sample 54 to be measured, thereby realizing the environment of rock burst suffered by deep rocks.

[0068] S7. Collect the test block: After the stress signal wave acquisition is completed, the axial actuator 4 releases the axial pressure and the confining pressure actuator 24 releases the water pressure, and the rock sample 54 to be measured is taken out.

[0069] In this embodiment: After the stress signal wave acquisition is completed, the axial pressure is released to relieve the axial pressure and the circumferential pressure is released to relieve the water pressure, the water medium inside the water pressure loading assembly 2 is discharged, the circular water stop cover 1 is opened, and the axial jack is used to increase the distance between the incident rod 16 and the transmission rod 17 to facilitate the removal of the rock sample 54 to be measured.

[0070] During the test, according to the one-dimensional stress wave propagation theory, the strain data monitored by the strain gauge 33 can be calculated according to the following formula to obtain the dynamic compression strain rate in the SHPB loading test simulating the deep rock geothermal - water pressure - stress coupling environment. Dynamic compression strain ε(t) and dynamic stress σ(t):

[0071]

[0072] In the formula, A0, C0, and E0 are respectively the cross-sectional area, one-dimensional elastic wave velocity, and elastic modulus of the pressure bar, A S and L S are respectively the cross-sectional area and original length of the rock sample 54 to be measured, ε I (t), ε R (t), ε T (t) are the incident wave electrical signal, reflected wave electrical signal, and transmitted wave electrical signal recorded by the strain gauge.

[0073] During the test, based on the law of conservation of energy, the incident energy, reflected energy, transmitted energy, and absorbed energy during the impact of the rock sample 54 to be measured can be calculated according to the following formula:

[0074]

[0075]

[0076] W S =W I -W R -W T

[0077] In the formula: σ I (t), σ R (t), σ R (t) are respectively the incident stress, reflected stress, and transmitted stress during the impact; WI , W R , W T , W S are the incident energy, reflected energy, transmitted energy, and absorbed energy during the impact process, respectively.

Claims

1. A SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress, characterized in that: It includes an SHPB component (1), a hydraulic pressure loading component (2), a water bath heating and circulating component (3), and an installation flat plate (9). The SHPB component (1) is installed at the upper end of the installation flat plate (9). The hydraulic pressure loading component (2) is arranged in the middle of the SHPB component (1). The water outlet of the hydraulic pressure loading component (2) is connected to the return port of the water bath heating and circulating component (3) through a connecting pipe. The water inlet of the hydraulic pressure loading component (2) is connected to the water outlet of the water bath heating and circulating component (3) through a connecting pipe. An outlet water stop valve (46) is installed at the water outlet pipe orifice (47) of the hydraulic pressure loading component (2), and an inlet water stop valve (20) is installed at the water inlet pipe orifice (45) of the hydraulic pressure loading component (2).

2. The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress according to claim 1, characterized in that: The SHPB component (1) includes an axial actuator (4), an impact rod (12), an incident rod (16), and a transmission rod (17). The hydraulic pressure loading component (2) is arranged in the middle of the upper end of the installation flat plate (9). A barrel (13) is arranged on one side of the installation flat plate (9) where the hydraulic pressure loading component (2) is located. The impact rod (12) is slidably connected to the outlet of the barrel (13). The incident rod (16) is connected to the side wall of the hydraulic pressure loading component (2) close to the barrel (13). The axial actuator (4) is located on the side of the installation flat plate (9) away from the barrel (13). The transmission rod (17) is connected to the side wall of the hydraulic pressure loading component (2) close to the axial actuator (4). Both the incident rod (16) and the transmission rod (17) penetrate the side wall of the hydraulic pressure loading component (2) and are slidably connected to the side wall of the hydraulic pressure loading component (2). The impact rod (12), the incident rod (16), and the transmission rod (17) are on the same straight line. Both the incident rod (16) and the transmission rod (17) are fixed to the installation flat plate (9) through multiple groups of installation baffles (10). Connecting holes for the incident rod (16) and the transmission rod (17) to slide are opened in the middle of multiple groups of the installation baffles (10). An axial pressure retaining ring (14) is sleeved in the connecting hole of the installation baffle (10) close to the impact rod (12). The outer diameter of the axial pressure retaining ring (14) on the side close to the impact rod (12) is adapted to the aperture of the connecting hole, and the outer diameter of the axial pressure retaining ring (14) on the side away from the impact rod (12) is larger than the aperture of the connecting hole.

3. The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress according to claim 1, characterized in that: The hydraulic pressure loading component (2) includes a confining pressure actuator (24). A bearing expansion hole is opened in the side wall of the hydraulic pressure loading component (2). The bearing rod (52) of the confining pressure actuator (24) is connected to the bearing expansion hole.

4. The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress according to claim 1, characterized in that: Threaded holes are opened at the four corners of the installation baffle (10). The installation baffle (10) is connected with an axial pressure pull rod (11) through the threaded holes. An adjusting bolt (15) for adjusting the distance between the axial pressure pull rod (11) and the axial actuator (4) is arranged at the connection part of the installation baffle (10) and the axial pressure pull rod (11).

5. A SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress according to claim 1, characterized in that: On both side walls of the water pressure loading assembly (2) along the arrangement direction of the incident rod (16), a first circular water stop cover (23) and a second circular water stop cover (50) are respectively installed.

6. The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress according to claim 1, characterized in that: Strain gauges (33) for collecting stress electrical signal waveform data are installed on the side walls of the incident rod (16) and the transmission rod (17).

7. The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure and stress according to claim 1, characterized in that: Multiple groups of support seats (7) are provided at the bottom of the installation flat plate (9), and the lower ends of the support seats (7) are fixed through installation bases (6).

8. A control system, characterized in that: The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure, and stress according to any one of claims 1-7 further includes an axial pressure and confining pressure servo controller (5). The axial pressure and confining pressure servo controller (5) includes an oil cylinder (34), a loading box body (37), and a second display controller (38). The oil cylinder (34) is arranged below the loading box body (37), the second display controller (38) is installed at the upper end of the loading box body (37), the signal output end of the second display controller (38) is connected to the signal input end of the oil cylinder (34), the oil cylinder (34) is provided with an axial pressure oil inlet and outlet control end (41) and a confining pressure inlet and outlet control end (42), the axial pressure oil inlet and outlet connection end (28) of the axial actuator (4) is connected to the axial pressure oil inlet and outlet control end (41) through an axial pressure hydraulic line (27), and the confining pressure oil inlet and outlet connection end of the confining pressure actuator (24) is connected to the confining pressure inlet and outlet control end (42) through a confining pressure hydraulic line (26).

9. The control system according to claim 8, wherein: A temperature sensor for detecting temperature and a water pressure sensor for detecting water pressure are installed inside the water pressure loading assembly (2), and the signal output ends of the temperature sensor and the water pressure sensor are connected to the signal input end of the second display controller (38).

10. A test method for a SHPB device, characterized in that: The SHPB device for simulating the coupled environment of deep rock geothermal temperature, water pressure, and stress according to any one of claims 1-7, the method steps are as follows: S1. Preparation stage: Pretreat the rock sample to be measured (54). After the pretreatment is completed, place the rock sample to be measured (34) inside the water pressure loading assembly (2), and clamp both ends through the incident rod (16) and the transmission rod (17) respectively, and execute step S2; S2. Water body heating: The water bath heating and circulating assembly (3) works to make the water body of the water bath heating and circulating assembly (3) reach the target value, and execute step S3; S3. Applying stress: The axial actuator (4) works to make the stress load received by the rock sample to be measured (34) reach the target value, and execute step S4; S4. Simulating geothermal temperature: Open the inlet water stop valve (20) and the outlet water stop valve (46), and the water body inside the water bath heating and circulating assembly (3) enters the water pressure loading assembly (2), and the temperature inside the water pressure loading assembly (2) is stabilized at the target value, and execute step S5; S5. Applying water pressure: Close the inlet water stop valve (20) and the outlet water stop valve (46), open the confining pressure actuator (24), and make the volume inside the water pressure loading assembly (2) change through the expansion and contraction of the bearing rod (52) of the confining pressure actuator (24). When the water pressure reaches the target value, execute step S6; S6. Start the SHPB component, fire the impact rod (12) through the barrel (13), and the impact rod (12) impacts the incident rod (16) to apply a dynamic load to the rock sample to be tested (54), thereby realizing the environment of rock burst suffered by deep rocks; S7. Collect the test block: After the stress signal wave acquisition is completed, the axial actuator (4) releases the axial pressure and the confining pressure actuator (24) releases the water pressure, and the rock sample to be tested is taken out.

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