Rock tension and compression experimental machine based on electromagnetic force control and experimental method

Abstract

The present application relates to the technical field of rock mechanics testing, and particularly relates to a rock tension and compression mechanics testing machine based on electromagnetic force control and a testing method, which comprises an experimental platform, a computer, an electromagnetic loading assembly and a fixing assembly for fixing a cylindrical rock to be tested on the experimental platform; the fixing assembly is installed on the upper and lower ends of the cylindrical rock to be tested, and the fixing assembly and the cylindrical rock to be tested are provided with a measuring assembly for measuring the stress and deformation data of the cylindrical rock to be tested; the electromagnetic loading assembly is arranged above the experimental platform, and the electromagnetic loading assembly generates an attractive force or a repulsive force on the fixing assembly after being powered on; the computer is electrically connected with the measuring assembly and the electromagnetic loading assembly, the computer controls the direction of the current in the electromagnetic loading assembly, so that the electromagnetic loading assembly applies a tension or a compression to the cylindrical rock to be tested fixed on the experimental platform. This solves the shortcoming that the traditional rock testing machine cannot realize efficient tension and compression rapid interactive loading, and realizes efficient and sensitive interactive testing of rock tension and compression.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rock mechanics testing, and particularly relates to a rock tension and compression mechanics testing machine based on electromagnetic force control and a testing method. BACKGROUND

[0002] When a roadway is excavated, the stress of the surrounding rock will be redistributed, resulting in a large amount of local tensile stress in the engineering rock mass and tensile failure, so that the principal stresses are all in compression. Because the rock material has a typical low tensile-to-compressive strength ratio, the tensile stress induced by excavation unloading cannot be ignored in deep mining. With the continuous excavation process, the deep surrounding rock is in a long-term tensile and compressive state.

[0003] At present, the research on the instability characteristics of rock under cyclic loading is mostly limited to the fatigue failure characteristics in the compression state. The compression testing machine technology is more mature, which is conducive to the development of related compression experiments. However, the existing universal testing machine is still a difficult problem for the development of rock sensitive tensile and compressive cyclic experiments due to the limitations of hydraulic flow control technology and rock sample preparation. This also leads to a severe lack of related experimental research on rock under tensile and compressive cyclic loading, which is different from the real load form in the field excavation.

[0004] The above content is only used to assist in understanding the technical solutions of the present application and does not represent the acknowledgement of the above content as the closest prior art. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a rock tension and compression mechanics testing machine based on electromagnetic force control, which solves the shortcomings of traditional rock testing machines that cannot realize efficient and rapid interactive loading, and realizes efficient and sensitive interactive experiments of rock tension and compression.

[0006] To achieve the purpose, the technical scheme of the present application is as follows: an experimental platform, a computer, an electromagnetic loading assembly, and a fixing assembly for fixing a cylindrical rock to be tested on the experimental platform; the fixing assembly is installed at the upper and lower ends of the cylindrical rock to be tested, and the fixing assembly and the cylindrical rock to be tested are provided with a measuring assembly for measuring the stress and deformation data of the cylindrical rock to be tested; the electromagnetic loading assembly is arranged above the experimental platform, and the electromagnetic loading assembly generates an attractive force or a repulsive force after being energized; the computer is electrically connected with the measuring assembly and the electromagnetic loading assembly, and a control system arranged in the computer controls the direction of the current in the electromagnetic loading assembly, so that the electromagnetic loading assembly applies a compressive force or a tensile force to the cylindrical rock to be tested fixed on the experimental platform.

[0007] Preferably, the experimental platform is provided with a fixed circular table on the upper end face; the lower end of the fixed circular table is connected with the experimental platform, and a connecting bolt is arranged at the center of the upper end of the fixed circular table; the fixing assembly comprises a first fixed iron sheet and a second gasket; the second gasket is installed on the upper end of the cylindrical rock to be measured; the first fixed iron sheet is installed on the lower end of the cylindrical rock to be measured, and a bolt hole is arranged at the center of the first fixed iron sheet, and the internal thread of the bolt hole is in threaded connection with the external thread of the connecting bolt.

[0008] Preferably, it further comprises a vertical support platform; the experimental platform is installed at the bottom end of the vertical support platform; the electromagnetic loading assembly comprises a cylindrical iron core and an excitation coil; the cylindrical iron core is vertically arranged above the experimental platform, and the top end is fixedly connected with the lower end of the vertical connecting rod; the upper end of the vertical connecting rod is connected with the top of the vertical support platform; the excitation coil is wound along the length direction of the cylindrical iron core, and the excitation coil is electrically connected with the computer.

[0009] Preferably, the measuring assembly comprises a radial displacement sensor, an axial displacement sensor and a stress sensor, which are all electrically connected with the computer; the radial displacement sensor is sleeved on the cylindrical rock to be measured and closely adheres to the surface of the cylindrical rock to be measured; the upper end face of the first fixed iron sheet is provided with a connecting hole; the top end of the axial displacement sensor abuts against the lower end face of the second gasket, and the bottom end is in plug-in connection with the connecting hole; the stress sensor is installed on the upper end face of the cylindrical rock to be measured and located between the second gasket and the upper end face of the cylindrical rock to be measured.

[0010] Preferably, the electromagnetic loading assembly further comprises a pressure head; the pressure head is provided in the shape of a circular table, the diameter of the upper end face of the pressure head is the same as the diameter of the cylindrical iron core, and the diameter of the lower end face of the pressure head is the same as the diameter of the cylindrical rock to be measured.

[0011] Preferably, the axial displacement sensor has at least two and is symmetrically arranged on both sides of the cylindrical rock to be measured.

[0012] Preferably, the second gasket is a strong permanent magnet gasket; the connection between the first fixed iron sheet and the second gasket and the cylindrical rock to be measured is pasted with epoxy resin.

[0013] Preferably, it further comprises an electromagnetic protection shell and a tension and compression protection cover; the electromagnetic protection shell is sleeved outside the cylindrical iron core, the length of the electromagnetic protection shell is the same as the length of the cylindrical iron core, and the electromagnetic protection shell is made of high-strength insulating material; the tension and compression protection cover is made of transparent material, the cylindrical rock to be measured fixed on the fixed circular table is covered in the tension and compression protection cover, and the inner diameter of the tension and compression protection cover is greater than the outer diameter of the electromagnetic protection shell.

[0014] Preferably, the vertical support platform comprises a motor control box, a first vertical support box and a second vertical support box; the motor control box is horizontally placed, and the upper surface of the motor control box is connected with the bottom end of the experimental platform; the first vertical support box is fixedly connected with one side of the motor control box, and a first vertical lead screw is arranged in the first vertical support box; the second vertical support box is installed on the other side of the motor control box, and a second vertical lead screw is arranged in the second vertical support box; further comprising a cross beam; the two ends of the cross beam are respectively sleeved on the rods of the first vertical lead screw and the second vertical lead screw, and form a threaded screw rod transmission with the rods; the upper end of the vertical connecting rod is connected with the middle part of the cross beam; the bottom ends of the first vertical lead screw and the second vertical lead screw are provided with a transmission mechanism, and the transmission mechanism is driven to rotate the first vertical lead screw and the second vertical lead screw under the driving of the motor in the motor control box.

[0015] Preferably, the specific operation steps are as follows:

[0016] S1, first, prepare cylindrical rocks of different diameters as experimental samples, and first paste a first fixed iron sheet on the lower end surface of the cylindrical rock to be tested by using epoxy resin, and then paste a stress sensor on the upper end surface of the cylindrical rock to be tested, and then paste a second gasket on the stress sensor by using epoxy resin;

[0017] S2, rotate the first vertical lead screw and the second vertical lead screw by starting the motor in the motor control box, drive the cross beam to move upward, leave a space between the cylindrical iron core and the experimental platform for installing the cylindrical rock to be tested, align the bolt hole on the first fixed iron sheet with the top of the connecting bolt on the fixed circular table, and then rotate to form a threaded connection, so that the treated cylindrical rock to be tested is installed on the fixed circular table of the experimental platform;

[0018] S3, the radial displacement sensor is sleeved at the middle position of the cylindrical rock to be tested, the top end of the axial displacement sensor abuts against the lower end surface of the second gasket, the bottom end is inserted into the connecting hole in the first fixed iron sheet, a pressure head with the same diameter as the cylindrical rock to be tested is selected and placed on the upper end surface of the second gasket, and the position of the pressure head is adjusted so that the pressure head is coaxial with the cylindrical rock to be tested;

[0019] Start the motor in the motor control box to drive the first vertical lead screw and the second vertical lead screw to rotate in reverse, drive the cross beam to displace in the vertical direction, and then drive the cylindrical iron core to displace downward, and stop the cylindrical iron core from descending when the value displayed by the axial displacement sensor in the computer shows a significant value fluctuation; at this time, the lower end of the cylindrical iron core has contacted with the upper end surface of the pressure head;

[0020] S4, the excitation coil is energized, and a control system in the computer can automatically implement various tension-compression cyclic loading path commands, or a tension-compression cyclic loading path command is generated by manual coding of an experimenter, the current size and direction in the excitation coil are regulated, and thus the electromagnetic force size and direction on the cylindrical core are changed;

[0021] When the experimenter inputs a sinusoidal tension-compression cyclic loading command on the computer, the control system in the computer outputs a sinusoidal current value size, the excitation coil generates a sinusoidal electromagnetic force on the indenter through the cylindrical core, at this time, the magnetic pole direction of the indenter is the same as that of the second gasket (35) on the upper end surface of the cylindrical rock to be measured, and the cylindrical rock to be measured is pressurized by using the principle of repulsion between same poles;

[0022] When the experimenter inputs a negative sinusoidal tension-compression cyclic loading command on the computer, the computer changes the current direction in the excitation coil through the control system, at this time, the magnetic pole direction of the indenter is opposite to that of the second gasket, and the cylindrical rock to be measured is stretched by using the principle of attraction between different poles;

[0023] S5, the computer automatically collects data measured by the radial displacement sensor, the axial displacement sensor and the stress sensor in real time during the experiment, and analyzes and processes the measured data; the control system in the computer can obtain different mode electromagnetic force load spectra in the computer according to the relationship between the current size and direction in the excitation coil and the electromagnetic force;

[0024] S6, the current direction in the excitation coil is continuously changed through the control system in the computer, and the current size in the excitation coil is increased in steps until the cylindrical rock to be measured is damaged under the action of stress, the current in the excitation coil is stopped, the height of the cylindrical core is lifted by the motor, the cylindrical rock to be measured is taken out, the experimental platform is cleaned, and the experiment is ended.

[0025] The beneficial effects of the present application are as follows:

[0026] (1), the application realizes the regulation and change of the tension or pressure received by the rock sample by converting the current direction in the excitation coil on the cylindrical core, the micro-control current wave type and the current size through the control system inside the computer.When the sine wave tension and pressure cyclic loading command is selected, the computer control system outputs the current value of the sine wave type change, the cylindrical core generates the electromagnetic force of the sine wave type change under the action of the excitation coil on the pressure head, the magnetic pole direction of the strong permanent magnet piece on the upper end surface of the pressure head and the sample is the same, the rock sample is pressurized by using the principle of repulsion between the same poles, so that the rock sample receives the pressure. Similarly, the computer control system changes the current direction in the excitation coil, the magnetic pole direction of the strong permanent magnet piece on the upper end surface of the pressure head and the sample is opposite, the sample is stretched by using the principle of attraction between different poles. Through the pressure data transmitted by the stress sensor and the displacement data transmitted by the radial or axial displacement sensor, the tension and pressure process of the rock sample in the experiment can be observed in real time. This way of controlling and loading the stress received by the rock sample through electromagnetic force and real-time display of changes not only solves the shortcomings of traditional rock experiment machines that cannot realize efficient tension and pressure rapid interactive loading, realizes efficient and sensitive interactive rock tension and pressure experiment, but also can simulate the process that the stress in the rock sample is continuously redistributed as the construction continues in the natural environment, and can make the stress value received by the rock sample close to the value in the natural state, thereby improving the accuracy of the rock tension and pressure experiment results.

[0027] (2), the application is provided with a connecting bolt at the upper end center of the fixed circular table, the first fixed iron piece is installed at the lower end of the rock sample, and a bolt hole is arranged at the center of the first fixed iron piece, the internal thread of the bolt hole and the external thread of the connecting bolt are in threaded cooperation. Such design not only enables the rock sample to be stably installed on the experiment table during the experiment, but also ensures that the stress inside the rock sample can still continue to increase when the tension received by the rock sample exceeds its gravity, thereby improving the accuracy of the experimental results.

[0028] (3), the application sets the pressure head as a circular table, the diameter of the upper end surface of the pressure head is the same as the diameter of the cylindrical core, and the diameter of the lower end surface of the pressure head is the same as the diameter of the cylindrical rock to be measured. This enables the electromagnetic force received by the pressure head to be fully transmitted to the cylindrical rock to be measured, thereby improving the accuracy of the rock tension and pressure experimental data.

[0029] (4), the application adopts epoxy resin paste for the connection between the first fixed iron piece, the second gasket and the cylindrical rock to be measured, realizes the perfect connection between the rock and the iron of different materials, and ensures the feasibility of the experiment. Meanwhile, the second gasket is set as a strong permanent magnet gasket, so that the second gasket forms electromagnetic induction with the energized excitation coil and converts the electromagnetic force formed into pressure or tension and transmits it to the cylindrical rock to be measured, thereby improving the effect of the rock tension and pressure experiment. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 Structure diagram of the present application;

[0031] Fig. 2 Structure diagram of the present application;

[0032] Fig. 3 Structure diagram of the present application;

[0033] Fig. 4 Structure diagram of the present application;

[0034] Explanation of reference signs:

[0035] A-cylinder-shaped rock to be measured; 11, motor control box; 12, first vertical support box;

[0036] 13, first vertical lead screw; 14, cross beam; 15, second vertical support box;

[0037] 16, second vertical lead screw; 21, vertical connecting rod; 22, cylindrical iron core; 23, excitation coil;

[0038] 24, pressure head; 25, electromagnetic protective shell; 31, pull and pressure protective cover; 32, experimental platform;

[0039] 33, fixed circular table; 331, connecting bolt; 34, first fixed iron sheet; 341, bolt hole;

[0040] 342, connecting hole; 35, second gasket;

[0041] 41, radial displacement sensor; 42, axial displacement sensor; 43, stress sensor. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0043] Embodiment 1

[0044] Reference is made to Figs. 1 to 4 the drawings:

[0045] The application provides a rock tension and compression mechanical experiment machine based on electromagnetic force control, which comprises a vertical support platform, an experiment platform 32, a computer, an electromagnetic loading assembly, a measuring assembly and a fixing assembly for fixing a cylindrical rock A to be measured on the experiment platform 32.

[0046] The vertical support platform is composed of a motor control box 11, a first vertical support box 12, a cross beam 14 and a second vertical support box 15.

[0047] The motor control box 11 is horizontally placed on the ground, and the upper surface of the motor control box 11 is connected with the bottom end of the experiment platform 32.

[0048] The first vertical support box 12 is fixedly connected with one side of the motor control box 11, and a first vertical lead screw 13 is arranged in the first vertical support box 12. The second vertical support box 15 is installed on the other side of the motor control box 11, and a second vertical lead screw 16 is arranged in the second vertical support box 15. The two ends of the cross beam 14 are sleeved on the rods of the first vertical lead screw 13 and the second vertical lead screw 16 respectively, and form threaded screw rod transmission with the first vertical lead screw 13 and the second vertical lead screw 16. The bottom ends of the first vertical lead screw 13 and the second vertical lead screw 16 are provided with transmission mechanisms, the motor shaft drives the first vertical lead screw 13 and the second vertical lead screw 16 to rotate synchronously through a belt or a gear transmission connection mode, and the motor is preferably a reversible motor.

[0049] The motor is electrically connected with the computer, and the rotation speed and direction of the motor are adjusted by the control system of the computer, so as to drive the first vertical lead screw 13 and the second vertical lead screw 16 to rotate, and then drive the cross beam 14 to ascend or descend along the vertical direction of the first vertical lead screw 13 and the second vertical lead screw 16.

[0050] A fixing circular table 33 for fixing the cylindrical rock A to be measured is arranged on the upper end surface of the experiment platform 32, the lower end of the fixing circular table 33 is connected with the experiment platform 32, and a connecting bolt 331 is arranged at the upper end center of the fixing circular table 33.

[0051] The fixing assembly is composed of a first fixing iron sheet 34 and a second gasket 35. A connecting hole 342 is arranged on the upper end surface of the first fixing iron sheet 34. The first fixing iron sheet 34 is pasted on the lower end of the cylindrical rock A to be measured through epoxy resin, and a bolt hole 341 is arranged at the center of the first fixing iron sheet 34, and the internal thread of the bolt hole 341 and the external thread of the connecting bolt 331 of the fixing circular table 33 form threaded connection. The second gasket 35 is a strong permanent magnet gasket, and the second gasket 35 is pasted on the upper end surface of the cylindrical rock A to be measured through epoxy resin.

[0052] Before the experiment, the first fixed iron sheet 34 and the second gasket 35 are installed at both ends of the cylindrical rock A to be tested, and the first fixed iron sheet 34 is connected with the connecting bolt 331 of the fixed circular table 33 through the center of the bolt hole 341, so that the cylindrical rock A to be tested is fixed on the experimental platform 32, and can be disassembled after the experiment, which is convenient for the arrangement and cleaning of the experimental platform 32.

[0053] The electromagnetic loading assembly is composed of a vertical connecting rod 21, a cylindrical iron core 22, an excitation coil 23 and a pressure head 24. The top end of the vertical connecting rod 21 is connected with the middle part of the cross beam 14, and the bottom end of the vertical connecting rod 21 is fixedly connected with the upper end surface of the cylindrical iron core 22. The cylindrical iron core 22 is vertically arranged above the experimental platform 32, the excitation coil 23 is wound along the length direction of the cylindrical iron core 22, and the excitation coil 23 is electrically connected with the computer. It also includes an electromagnetic protective shell 25, which is sleeved outside the cylindrical iron core 22, and the length of the electromagnetic protective shell 25 is the same as that of the cylindrical iron core 22, and is made of high-strength insulating material.

[0054] The pressure head 24 is provided in a circular table shape and is made of a magnetic good conductor material such as iron material stamping. The upper end surface of the pressure head 24 has the same diameter as the cylindrical iron core 22, and the lower end surface of the pressure head 24 has the same diameter as the cylindrical rock A to be tested. When the excitation coil 23 is energized to generate electromagnetic force, the pressure head 24 can transmit all the electromagnetic force received to the cylindrical rock A to be tested, improving the accuracy of the rock tension and compression experiment data.

[0055] It also includes a tension and compression protective cover 31. The tension and compression protective cover 31 is made of transparent material, and the cylindrical rock A to be tested fixed on the fixed circular table 33 is covered therein, and the inner diameter of the tension and compression protective cover 31 is greater than the outer diameter of the electromagnetic protective shell 25. The tension and compression protective cover 31 can prevent the cylindrical rock A to be tested from breaking and flying in the experimental process, and improves the safety of the experimental machine.

[0056] The measuring assembly is composed of the radial displacement sensor 41, the axial displacement sensor 42 and the stress sensor 43. Before the experiment, the radial displacement sensor 41 is sleeved on the cylindrical rock A to be measured and tightly adheres to the surface of the cylindrical rock A to be measured. The top end of the axial displacement sensor 42 abuts against the lower end face of the second gasket 35, and the bottom end is in plug-in cooperation with the connecting hole 342 of the upper end face of the first fixed iron sheet 34. The stress sensor 43 is installed on the upper end face of the cylindrical rock A to be measured and located between the second gasket 35 and the upper end face of the cylindrical rock A to be measured. Before the experiment, the stress sensor 43 is generally pasted on the upper end face of the cylindrical rock A to be measured, and then the second gasket 35 is pasted on the upper end face of the cylindrical rock A to be measured through the epoxy resin. The axial displacement sensor 42 is composed of two small sensors for measuring axial displacement, and the two small sensors are connected through a spring telescopic rod. When the two ends of the small sensor are subjected to extrusion force, the two small sensors move towards each other.

[0057] The axial displacement sensor 42 is at least two and symmetrically arranged around the cylindrical rock A to be measured, so as to improve the measurement accuracy. At the same time, the radial displacement sensor 41, the axial displacement sensor 42 and the stress sensor 43 are electrically connected with the computer, and the measured data can be transmitted to the control system of the computer in real time during the experiment.

[0058] This way of controlling and loading the stress on the cylindrical rock A to be measured by adjusting the electromagnetic force and displaying the changes in real time not only solves the shortcomings of the traditional rock testing machine that cannot realize efficient and rapid interactive loading, but also realizes efficient and sensitive interactive rock testing. Moreover, the testing machine can simulate the process that the stress in the rock sample, i.e. the cylindrical rock A to be measured, is continuously redistributed as the construction is continuously carried out in the natural environment, and can make the stress value of the cylindrical rock A to be measured close to the value in the natural state, thereby improving the accuracy of the rock tensile and compressive test results of the cylindrical rock A to be measured.

[0059] Example 2

[0060] The specific operation steps of the experimental machine using method are as follows:

[0061] S1, first, different diameter cylindrical rocks A to be measured are prepared as experimental samples, the first fixed iron sheet 34 is pasted on the lower end face of the cylindrical rock A to be measured with the epoxy resin, the stress sensor 43 is pasted on the upper end face of the cylindrical rock A to be measured, and then the second gasket 35 is pasted on the upper end face of the cylindrical rock A to be measured with the epoxy resin;

[0062] S2, by opening the motor control box 11 in the motor driven first vertical lead screw 13 and the second vertical lead screw 16 rotation, cross beam 14 driven cylindrical core 22 to move up, between the cylindrical core 22 and the experimental platform 32 between the space can install cylindrical rock A to be measured, and then the first fixed iron sheet 34 on the bolt hole 341 and fixed circular table 33 on the connecting bolt 331 top alignment, rotation after making it constitute threaded connection, so that the cylindrical rock A to be measured installation to the experimental platform 32 on the fixed circular table 33;

[0063] S3, the radial displacement sensor 41 is installed in the middle of the cylindrical rock A to be measured, the top end of the axial displacement sensor 42 is in abutment with the lower end surface of the second gasket 35, the bottom end is inserted into the connecting hole 342 in the first fixed iron sheet 34, the pressure head 24 with the same diameter as the cylindrical rock A to be measured is selected and placed on the upper end surface of the second gasket 35, and the position of the pressure head 24 is adjusted so that the pressure head 24 is coaxial with the cylindrical rock A to be measured;

[0064] Open the motor control box 11 in the motor driven first vertical lead screw 13 and the second vertical lead screw 16 reverse rotation, driven cross beam 14 along the vertical direction down displacement, in turn driven cylindrical core 22 downward displacement, when the axial displacement sensor 42 in the computer display value appears obvious value fluctuation stop cylindrical core 22 down, at this time the lower end of the cylindrical core 22 and the upper end surface of the pressure head 24 have been contacted;

[0065] S4, energize the excitation coil 23, and automatically implement various tension-compression cyclic loading path commands through the control system in the computer, or generate tension-compression cyclic loading path commands by manual coding of the experiment personnel, regulate and control the current size and direction in the excitation coil 23, so as to change the electromagnetic force size and direction on the cylindrical core 22;

[0066] When the experiment personnel input the sinusoidal tension-compression cyclic loading command on the computer, the control system in the computer outputs the sinusoidal current value size, the excitation coil 23 generates the sinusoidal electromagnetic force on the pressure head 24 through the cylindrical core 22, at this time the pressure head 24 and the second gasket 35 on the upper end surface of the cylindrical rock A to be measured have the same magnetic pole direction, and the cylindrical rock A to be measured is pressed by using the principle of same pole repulsion;

[0067] When the experiment personnel input the negative sinusoidal tension-compression cyclic loading command on the computer, the computer changes the current direction in the excitation coil 23 through the control system, at this time the pressure head 24 and the second gasket 35 have opposite magnetic pole directions, and the cylindrical rock A to be measured is stretched by using the principle of different sex attraction;

[0068] S5, the computer internal system automatically collects the data measured by the radial displacement sensor 41, the axial displacement sensor 42 and the stress sensor 43 in the experiment process in real time, and analyzes and processes the measured data; the control system in the computer can obtain different mode electromagnetic force load spectrum in the computer according to the relationship between the size, direction and electromagnetic force of the current in the excitation coil 23;

[0069] S6, the control system in the computer continuously changes the current direction in the excitation coil 23, and makes the current size in the excitation coil 23 increase in steps, until the cylindrical rock to be tested A is damaged under the action of stress, the current in the excitation coil 23 is stopped, the height of the cylindrical iron core 22 is lifted by the motor, the cylindrical rock to be tested A is taken out, the experimental platform 32 is cleaned, and the experiment is ended.

[0070] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A rock tension-compression mechanical testing machine based on electromagnetic force control, characterized in that, The utility model relates to a kind of experimental platform for measuring the stress and deformation of cylindrical rock, including: Experimental platform (32), computer, electromagnetic loading assembly and the fixing assembly for fixing cylindrical rock (A) on experimental platform (32); The fixing assembly is installed at the upper and lower ends of cylindrical rock (A), and the fixing assembly and cylindrical rock (A) are provided with a measuring assembly for measuring the stress and deformation data of cylindrical rock (A); The electromagnetic loading assembly is arranged above the experimental platform (32), and the electromagnetic loading assembly generates attractive force or repulsive force after being energized; The computer is electrically connected with the measuring assembly and the electromagnetic loading assembly, and the control system in the computer controls the direction of current in the electromagnetic loading assembly, so that the electromagnetic loading assembly applies pressure or tension to the cylindrical rock (A) fixed on the experimental platform (32); The upper end surface of the experimental platform (32) is provided with a fixed circular table (33), the lower end of the fixed circular table (33) is connected with the experimental platform (32), the upper end of the fixed circular table (33) is provided with a connecting bolt (331) at the center, the fixing assembly includes a first fixed iron sheet (34) and a second gasket (35), the second gasket (35) is installed at the upper end of the cylindrical rock (A), the first fixed iron sheet (34) is installed at the lower end of the cylindrical rock (A), and the center of the first fixed iron sheet (34) is provided with a bolt hole (341), the internal thread of the bolt hole (341) is threadedly connected with the external thread of the connecting bolt (331); It also includes a vertical support platform, the experimental platform (32) is installed at the bottom end of the vertical support platform, the electromagnetic loading assembly includes a cylindrical iron core (22) and an excitation coil (23), the cylindrical iron core (22) is vertically arranged above the experimental platform (32), and the top end is fixedly connected with the lower end of a vertical connecting rod (21), the upper end of the vertical connecting rod (21) is connected with the top of the vertical support platform, the excitation coil (23) is wound along the length direction of the cylindrical iron core (22), and the excitation coil (23) is electrically connected with the computer.

2. The electromagnetic force controlled rock uniaxial and triaxial mechanical testing machine according to claim 1, wherein, The measuring assembly includes a radial displacement sensor (41), an axial displacement sensor (42) and a stress sensor (43) which are electrically connected with the computer, the radial displacement sensor (41) is sleeved on the cylindrical rock (A) and closely adheres to the surface of the cylindrical rock (A), the upper end surface of the first fixed iron sheet (34) is provided with a connecting hole (342), the top end of the axial displacement sensor (42) abuts against the lower end surface of the second gasket (35), and the bottom end is insertedly connected with the connecting hole (342), the stress sensor (43) is installed on the upper end surface of the cylindrical rock (A) and located between the second gasket (35) and the upper end surface of the cylindrical rock (A).

3. The electromagnetic force controlled rock uniaxial and triaxial mechanical testing machine of claim 2, wherein, The electromagnetic loading assembly further includes a pressure head (24), the pressure head (24) is arranged in the shape of a circular table, the diameter of the upper end surface of the pressure head (24) is the same as that of the cylindrical iron core (22), and the diameter of the lower end surface of the pressure head (24) is the same as that of the cylindrical rock (A).

4. The electromagnetic force controlled rock uniaxial and triaxial mechanical testing machine of claim 3, wherein, The axial displacement sensor (42) is at least two and symmetrically arranged on both sides of the cylindrical rock (A) to be measured.

5. The electromagnetic force controlled rock uniaxial and triaxial mechanical testing machine of claim 4, wherein, The second gasket (35) is a strong permanent magnet gasket; the connection between the first fixed iron sheet (34) and the second gasket (35) and the cylindrical rock (A) to be measured is adhered by epoxy resin.

6. The electromagnetic force controlled rock uniaxial and triaxial mechanical testing machine of claim 5, wherein, It also includes an electromagnetic shielding shell (25) and a tension and compression protective cover (31); the electromagnetic shielding shell (25) is sleeved outside the cylindrical iron core (22), and the length of the electromagnetic shielding shell (25) is the same as the length of the cylindrical iron core (22), and is made of high-strength insulating material; the tension and compression protective cover (31) is made of transparent material, and the cylindrical rock (A) to be measured fixed on the fixed circular table (33) is covered therein, and the inner diameter of the tension and compression protective cover (31) is greater than the outer diameter of the electromagnetic shielding shell (25).

7. The electromagnetic force controlled rock uniaxial and triaxial mechanical testing machine of claim 6, wherein, The vertical support platform includes a motor control box (11), a first vertical support box (12) and a second vertical support box (15); the motor control box (11) is horizontally placed, and the upper surface of the motor control box (11) is connected with the bottom end of the experimental platform (32); the first vertical support box (12) is fixedly connected with one side of the motor control box (11), and a first vertical lead screw (13) is arranged in the first vertical support box (12); the second vertical support box (15) is installed on the other side of the motor control box (11), and a second vertical lead screw (16) is arranged in the second vertical support box (15); further including a cross beam (14); the two ends of the cross beam (14) are sleeved on the rods of the first vertical lead screw (13) and the second vertical lead screw (16) respectively, and form threaded screw rod transmission with them; the upper end of the vertical connecting rod (21) is connected with the middle part of the cross beam (14); the bottom ends of the first vertical lead screw (13) and the second vertical lead screw (16) are provided with transmission mechanisms, and the transmission mechanisms drive the first vertical lead screw (13) and the second vertical lead screw (16) to rotate under the drive of the motor in the motor control box (11).

8. A method of experiment of a rock tension-compression mechanical experiment machine based on electromagnetic force control, characterized in that, The method for using the rock tension and compression mechanical experiment machine based on electromagnetic force control according to any one of the above claims 1-7 is as follows: S1, first, prepare cylindrical rocks (A) with different diameters as experimental samples, and paste a first fixed iron sheet (34) on the lower end surface of the cylindrical rock (A) to be measured by using epoxy resin, paste a stress sensor (43) on the upper end surface of the cylindrical rock (A) to be measured, and then paste a second gasket (35) by using epoxy resin; S2, rotate the first vertical lead screw (13) and the second vertical lead screw (16) by starting the motor in the motor control box (11), drive the cylindrical iron core (22) to move upwards by the cross beam (14), leave a space between the cylindrical iron core (22) and the experimental platform (32) for installing the cylindrical rock (A) to be measured, align the bolt hole (341) on the first fixed iron sheet (34) with the top of the connecting bolt (331) on the fixed circular table (33), and rotate to form threaded connection, so that the treated cylindrical rock (A) to be measured is installed on the fixed circular table (33) of the experimental platform (32); S3, the radial displacement sensor (41) is sleeved in the middle position of the cylindrical rock to be measured (A), the top end of the axial displacement sensor (42) abuts against the lower end surface of the second gasket (35), the bottom end is inserted into the connecting hole (342) on the first fixed iron sheet (34), a pressure head (24) with the same diameter as the cylindrical rock to be measured (A) is selected, and the pressure head (24) is placed on the upper end surface of the second gasket (35), the position of the pressure head (24) is adjusted, so that the pressure head (24) is coaxial with the cylindrical rock to be measured (A); Turn on the motor in the motor control box (11) to drive the first vertical lead screw (13) and the second vertical lead screw (16) to rotate in opposite directions, drive the cross beam (14) to displace in the vertical direction, and then drive the cylindrical iron core (22) to displace downward, stop the cylindrical iron core (22) from descending when the value displayed by the axial displacement sensor (42) in the computer shows obvious value fluctuation, at this time the lower end of the cylindrical iron core (22) has contacted the upper end surface of the pressure head (24); S4, energize the excitation coil (23), and automatically implement various tension-compression cyclic loading path commands through the control system in the computer, or manually generate tension-compression cyclic loading path commands through the experiment personnel, so as to adjust and control the current size and direction in the excitation coil (23), thereby changing the electromagnetic force size and direction on the cylindrical iron core (22); When the experiment personnel input the sine wave tension-compression cyclic loading command on the computer, the control system in the computer outputs the sine wave type changing current value size, the excitation coil (23) generates the sine wave type changing electromagnetic force on the pressure head (24) through the cylindrical iron core (22), at this time the pressure head (24) and the second gasket (35) on the upper end surface of the cylindrical rock to be measured (A) have the same magnetic pole direction, and the cylindrical rock to be measured (A) is pressed by using the principle of repulsion between the same poles; When the experiment personnel input the negative sine wave tension-compression cyclic loading command on the computer, the computer changes the current direction in the excitation coil (23) through the control system, at this time the pressure head (24) and the second gasket (35) have opposite magnetic pole directions, and the cylindrical rock to be measured (A) is stretched by using the principle of attraction between different poles; S5, the computer internal system automatically collects the data measured by the radial displacement sensor (41), the axial displacement sensor (42) and the stress sensor (43) in the experiment process in real time, and analyzes and processes the measured data; the control system in the computer can obtain different mode electromagnetic force load spectrum in the computer according to the relationship between the current size, direction and electromagnetic force in the excitation coil (23); S6, the control system in the computer continuously changes the current direction in the excitation coil (23), and makes the current size in the excitation coil (23) increase in steps until the cylindrical rock to be measured (A) is damaged under the action of stress, then stop the current in the excitation coil (23), lift the height of the cylindrical iron core (22) through the motor, take out the cylindrical rock to be measured (A), clean the experiment platform (32), and end the experiment.

Images