CN111157557A - Testing device and method for representing soil-rock mixture fracture process and matching with CT machine - Google Patents
Testing device and method for representing soil-rock mixture fracture process and matching with CT machine Download PDFInfo
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- CN111157557A CN111157557A CN202010097808.1A CN202010097808A CN111157557A CN 111157557 A CN111157557 A CN 111157557A CN 202010097808 A CN202010097808 A CN 202010097808A CN 111157557 A CN111157557 A CN 111157557A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
- G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/03—Investigating materials by wave or particle radiation by transmission
- G01N2223/04—Investigating materials by wave or particle radiation by transmission and measuring absorption
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2223/00—Investigating materials by wave or particle radiation
- G01N2223/10—Different kinds of radiation or particles
- G01N2223/101—Different kinds of radiation or particles electromagnetic radiation
- G01N2223/1016—X-ray
Abstract
The invention provides a test device and a test method for representing a cracking process of an earth-rock mixture and matching with a CT (computed tomography) machine, and belongs to the technical field of geotechnical engineering. The device comprises an axial compression system, a confining pressure system and a scanning system. The axial compression system comprises a servo motor, a speed reducer, a bearing sleeve, a piston, a shell and a lead screw. The servo motor is connected with the speed reducer. The confining pressure system comprises a pressure chamber, a pressure sensor, an upper pressure head, a lower pressure head, a lifting oil cylinder lifting rod, a lifting oil cylinder base and a lifting oil cylinder cross beam. The bottom of the pressure chamber is connected with the rotary table. The scanning system comprises an X-ray emitter, a detector, an X-ray source, a transmission motor, a transmission speed reducer, a transmission motor base, a transmission lead screw, a transmission bearing base, a transmission track groove, an iron pad, a vertical rack, a screw and a positioning hole. The transmission motor and the transmission bearing seat are fixed on the vertical rack through screws. The invention can obtain the internal deformation, crack development and damage of the sample in the cracking process in real time under the condition of a cyclic loading experiment.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a test device and a test method for representing a cracking process of a soil-rock mixture and matching with a CT machine.
Background
The surface mine dump is a part of a surface mine and receives and contains waste stripped from the surface mine. Once the side slope is unstable and slides down in the refuse dump, serious personal casualties and property losses can be caused. In the production of strip mine, a series of dynamic disturbances such as mining disturbance, blasting vibration, earthquake and the like can affect the internal structure of the earth-rock mixture of the dump, especially the blasting vibration, and the blasting vibration has strong shock wave and stress wave action and has repeated action. The field condition can be well fitted by collecting waveforms generated by a series of disturbances on the site of the refuse dump and then inputting the disturbances with the same waveforms into the sample in a laboratory. Under the dynamic loading and unloading disturbance such as blasting excavation, the environment of a soil and rock mixture in a refuse dump is changed, the loading and unloading will cause the pressure of a structural surface to have the characteristic of increasing and decreasing, even the phenomena of opening sliding and anti-sliding force drop suddenly occur, and the disturbance will also influence the mechanisms such as crack closing and expansion. These new scientific phenomena, which cannot be explained and analyzed by the traditional continuous medium mechanics theory, are usually mechanistically studied by laboratory tests. Therefore, by applying disturbance of actual vibration waveforms on the mine dump or applying equivalent waveform disturbances such as sine waves, triangular waves and square waves to the sample, the quantitative test of crack evolution regularity (such as crack width, length and spatial position) in the deformation and damage process of the soil-rock mixture, three-dimensional reconstruction of cracks of the soil-rock mixture, damage evolution and damage variable analysis are realized, and the method has great practical significance.
The soil-rock mixture is a special geological material between soil body and broken rock mass, and its deformation destruction mechanism accessible indoor triaxial test reachs under the stress action, but indoor triaxial can only be when the experiment finishes, takes out the sample and observes its final remaining state, can't observe the deformation rupture process of sample in real time.
Along with the development of industrial CT, the research on the fracture characterization of the soil-rock mixture under dynamic disturbance becomes possible, and the technical key lies in the research and development of a dynamic disturbance triaxial loading test device and a test method matched with the industrial CT machine.
Based on the requirements, the invention discloses a test device and a method for dynamically disturbing and triggering the fracture characterization of the soil-rock mixture and matching with an industrial CT machine.
The invention relates to a soil sample carrying device for medical CT scanning, which is published under the patent application No. 201811434122.6 and No. CN 109374657A. The invention discloses a soil-carrying sample device for medical CT scanning, which relates to the technical field of rock experimental instruments, and comprises a cylinder body, a sample storage device and a sample taking device, wherein the cylinder body is used for containing a soil sample; the two baffles are arranged in the cylinder body and can move along the length direction of the cylinder body, the soil sample is clamped between the two baffles, and the cross section of each baffle is the same as that of the inner cavity of the cylinder body and is in sliding fit with the inner wall of the cylinder body; the closing plates are respectively clamped at the two opening ends of the barrel body and are fixed by virtue of a fixing mechanism; the pushing bolts respectively penetrate through the threaded holes in the sealing plates at the two ends and are in threaded fit connection with the threaded holes, and one end of each pushing bolt, which is positioned in the cylinder body, is arranged in the circular groove on the side face of the baffle; the supporting seat is used for supporting the barrel, and a semicircular notch used for accommodating the barrel is formed in the supporting seat. The technical problem that the soil sample is easily disturbed in the processes of disassembly, transportation and CT scanning in the prior art is solved.
By contrast, the present invention has the following advantages:
1. the device is too simple, aims to ensure the stable state of the soil sample, and can apply actually-received waveform disturbance or equivalent waveform disturbance such as sine wave, triangular wave, square wave and the like to the sample by using the triaxial loading device taking the pressure chamber as the core, so that the action of a complicated stress disturbance path can be well simulated.
2. The invention uses a large amount of metal materials in the CT scanning area, which has a certain influence on the scanning quality. The whole set of device is made of high-strength low-density transparent aircraft glass material, the aircraft glass has excellent performance, the ray energy attenuation condition when X-rays pass through the pressure chamber is improved under the condition of meeting the functional requirements, the transparent material also realizes the visualization of deformation and damage of the sample, and clear internal images in the deformation process of the sample can be obtained in real time.
3. Said invention adopts medical CT, and said medical CT is used in rock mechanical test, but its medical CT ray energy is small, penetration capability is poor, imaging quality is not good, and it is difficult to implement high-accuracy test. In order to obtain the crack evolution (such as crack width, length and space position) process in the deformation and damage process of the soil-rock mixture, the invention uses the industrial CT machine, has the advantages of large ray energy, strong penetrating power, accurate scanning and the like, can greatly improve the imaging quality, and the loading device and the sample rotate in the experimental process, and the CT machine does not move. In addition, the loading device adopts wireless intelligent control, and the problem of line winding in the rotating process of the measuring and connecting system on the CT rotary table during testing is solved.
4. The above invention does not provide a scanning system and a detailed description of the scanning principle and method is not given. The scanning system comprises an X-ray emitter, an X-ray detector, an X-ray source, a transmission motor, a transmission speed reducer, a transmission motor base, a transmission lead screw, a transmission bearing seat, a transmission track groove, an iron pad, a vertical frame, a fixing screw and a positioning hole which are arranged on two sides of a pressure chamber, so that a complete system is formed. In addition, the operation method from the beginning of the CT scanning to the end of the CT scanning is elaborated, a clear description is provided for how the industrial CT and the experimental device are combined for use, and the visual and digital representation of the breaking process of the earth-rock mixture is realized.
Disclosure of Invention
The invention aims to solve the visualization and digitization problems of the soil-rock mixture fracture evolution process under the action of cyclic load, and provides a test device and a test method matched with a CT machine for soil-rock mixture fracture characterization.
The device comprises an axial compression system, a confining pressure system and a scanning system, wherein the axial compression system comprises a servo motor, a speed reducer, a bearing sleeve, a piston, a shell and a lead screw; the confining pressure system comprises a pressure chamber, a pressure sensor, an upper pressure head, a lower pressure head, a lifting oil cylinder lifting rod, a lifting oil cylinder base and a lifting oil cylinder cross beam, a sample is fixed in the pressure chamber through the upper pressure head and the lower pressure head, the pressure sensor is arranged on the upper portion of the upper pressure head, the lifting oil cylinder cross beam stretches across two sides of the device, the middle of the lifting oil cylinder cross beam is connected with a connecting piece, two ends of the lifting oil cylinder cross beam are connected with the lifting oil cylinder lifting rod, and the lifting oil cylinder lifting rod is fixed on the lifting; the scanning system is including the X ray transmitter of locating the pressure chamber both sides, the detector, the X ray source, driving motor, the transmission speed reducer, the transmission motor cabinet, drive screw, the transmission bearing frame, transmission track groove, vertical frame, screw and locating hole, drive motor and transmission bearing frame pass through the screw fixation in vertical frame, drive motor and transmission speed reducer pass through screwed connection, drive speed reducer and transmission motor cabinet pass through screwed connection, drive screw passes through the transmission motor cabinet and the installation of transmission bearing frame is fixed at the upper and lower end of vertical frame, X ray transmitter and detector respectively with both sides transmission track groove zonulae occludens, set up the locating hole in the vertical frame.
The deep groove ball bearing is mainly used for bearing radial load, when only bearing the radial load, a contact angle is zero, the deep groove ball bearing is suitable for operation at high rotating speed or extremely high rotating speed, and the deep groove ball bearing is very durable and does not need to be maintained frequently. The thrust ball bearing adopts a design capable of bearing thrust load during high-speed operation, and is composed of a washer-shaped ferrule with a raceway groove for rolling balls.
The screw rod converts the rotary motion into linear motion, the piston is connected with the screw rod, and finally the load is acted on the upper pressure head to pressurize the sample.
The upper portion and the lower portion of the pressure chamber are respectively the top portion and the bottom portion of the pressure chamber, the wall of the pressure chamber is arranged in the middle of the pressure chamber, the bottom portion of the pressure chamber is connected with the upper portion of the rotary table through a bottom connecting piece, the lower portion of the rotary table is arranged below the upper portion of the rotary table, the lower portion of the rotary table is arranged on a base stand of the testing machine, and the base stand of the testing machine is arranged on a rigid stand.
An X-ray source is arranged on the X-ray emitter.
The axial pressure system and the confining pressure system are both arranged on the CT rotating table.
The axial lead of the sample is aligned with the axial leads of the upper and lower indenters.
The upper and lower indenters rotate synchronously and the sample does not experience any torque.
In application, after the soil-rock mixture sample is prepared, the lifting oil cylinder is started, the lifting oil cylinder lifting rod drives the pressure chamber and the upper structure to ascend, and after the sample is installed, the lifting oil cylinder lifting rod descends. The bottom of the pressure chamber is connected with the rotary table through a bottom connecting piece, so that the pressure chamber is stably connected with the rotary table during working. And (3) filling nitrogen into the pressure chamber through the reserved air guide pipe during the application of the confining pressure, firstly opening a control valve of the supercharger, and filling the nitrogen in the supercharger into the pressure chamber along the reserved air guide pipe so as to apply the confining pressure on the sample.
When a sample is scanned, an X-ray emitter emits rays through an X-ray source, the X-rays penetrate through the soil-rock mixture sample, part of the rays are absorbed by a scanned object, and the transmitted rays are received by an X-ray detector. After scanning is finished, microscopic physical quantities in the deformation and damage process of the two-dimensional CT slices and three-dimensional reconstructed image region of interest (ROI) are quantitatively described by extracting, identifying and analyzing the CT number, crack distribution, porosity evolution, block stone movement, CT damage and strain localization characteristics, and the inherent mechanism of damage and cracking of the soil-stone mixture is disclosed. Through the deformation test of the soil-rock mixture sample under the action of different stress paths, the microscopic cracking mechanism of the soil-rock mixture is researched.
The axial pressure system and the confining pressure system are arranged on a CT rotary table, after an experiment is started, a device arranged on the upper portion of the rotary table rotates, a radioactive source emits X rays to penetrate through the wall of a pressure chamber and a sample, the X rays are received by a detector, and therefore the loading and scanning of the sample are achieved.
The whole set of device adopts the transparent aircraft glass material of high strength low density to make, and aircraft glass not only has excellent optical property, thermoplasticity and processability, ageing resistance, has characteristics such as proportion is little, high mechanical strength, resistance to compression tensile properties are outstanding moreover, has improved the ray energy attenuation condition when X ray passes through the pressure chamber under satisfying the functional requirement, and transparent material has also realized the visual to sample deformation destruction, can acquire the clear internal image of sample deformation in-process in real time. In addition, the pressure chamber also acts as a counter-force structure while exerting a confining pressure.
The device adopts wireless intelligence to control, measures the circuit winding problem of connecting system rotatory in-process on the CT revolving stage during the solution test.
The method for applying the test device comprises the following steps:
s1: preparing a soil-rock mixture sample, and wrapping the soil-rock mixture sample by using a transparent plastic pipe to prepare a test;
s2: loading a sample into a pressure chamber, wherein the axial lead of the sample is aligned with the axial leads of an upper pressure head and a lower pressure head of the pressure chamber;
s3: checking the upper device of the rotary table to determine that the fixation is good;
s4: the power distribution cabinet main power supply is closed, the power indicator lamp is on, the main power supply works normally, and each subsystem is electrified: sequentially closing power supplies of all subsystems, electrifying the X-ray emitter, electrifying the detector, the data acquisition system and the scanning control system;
s5: starting an X-ray transmitter, selecting a preheating mode according to the time length of last shutdown till now, preheating, simultaneously starting a computer system, establishing connection with an optical machine through Ethernet, and transmitting the scanned CT slices to the computer;
s6: setting soil and stone mixture sample information and selecting or modifying scanning parameters on a computer system control station;
s7: when scanning starts, the X-ray transmitter emits beams, the detector receives signals, the scanning device subsystem completes various required motions, and the scanning control subsystem performs real-time control;
s8: after confining pressure is applied through the air duct, a servo motor is started, axial load is applied to the sample, the servo motor and a speed reducer are adjusted during scanning to enable the sample loading to change, so that the effect of a complex stress disturbance path on the sample is achieved, the simultaneous loading and scanning of the soil-rock mixture are achieved, the X-ray emitter stops emitting beams when each scanning is finished, and all devices of a subsystem of the scanning device stop moving;
s9: when suspicious defects are found on the image, positioning the defect height on the image, and carrying out CT scanning reconstruction or secondary experiment on the specified detection height;
s10: closing the radioactive source of the CT machine, unloading the pressure chamber, dismantling the sample and ending the test;
s11: repeating the above steps S2-S10 to perform the test;
s12: after all detection tasks are completed and the X-ray transmitter is waited for heat dissipation, the power supply of the X-ray transmitter is turned off, the power supply of the computer and the power supply of the numerical control system are turned off, switches of all subsystems are turned off, and the main power supply of the system is turned off;
s13: and analyzing the obtained test data, acquiring fracture evolution information of the sample under dynamic disturbance, and realizing visualization and digitization of the fracture process of the soil-rock mixture.
The technical scheme of the invention has the following beneficial effects:
the device combines a loading device and an industrial CT machine together well by means of high-energy X rays and a high-precision rotary table of the industrial CT machine, simulates the in-situ dynamic disturbance condition of the soil-rock mixture, realizes the simultaneous scanning of the soil-rock mixture during loading, acquires the original texture of the soil-rock mixture, structural data after cracking, particularly the internal structure evolution law in the deformation and cracking process, and discloses the micro mechanism of the macroscopic mechanical behavior of the soil-rock mixture.
The X-ray emitter emits rays through the X-ray source, the X-rays penetrate through the soil-rock mixture sample, part of the rays are absorbed by the scanned object, and the transmitted rays are received by the X-ray detector. The absorption coefficient of the scanned object is obtained through a series of scans at different angles, and three-dimensional imaging is carried out.
The deep groove ball bearing and the thrust ball bearing in the bearing sleeve enable the axial pressure to be continuously and stably applied, and the axial pressure is uniformly transmitted to the sample.
The upper pressure head and the lower pressure head rotate synchronously, so that the sample does not suffer from any torque, and the real state of the sample is simulated more accurately.
The axial pressure system and the confining pressure system are arranged on a CT rotary table, and a device arranged on the upper part of the rotary table rotates after the experiment begins.
The whole set of device adopts the transparent aircraft glass material of high strength low density to make, and aircraft glass not only has excellent optical property, thermoplasticity and processability, ageing resistance, has characteristics such as proportion is little, high mechanical strength, resistance to compression tensile properties are outstanding moreover, has improved the ray energy attenuation condition when X ray passes through the pressure chamber under satisfying the functional requirement, and transparent material has also realized the visual to sample deformation destruction, can acquire the clear internal image of sample deformation in-process in real time. In addition, the pressure chamber also acts as a counter-force structure while exerting a confining pressure.
Drawings
FIG. 1 is a schematic structural diagram of a whole system for researching dynamic disturbance triggering soil-rock mixture fracture characterization according to the invention;
FIG. 2 is a schematic structural diagram of an axial compression system and a confining pressure system of the present invention;
FIG. 3 is a cross-sectional view of the construction of the axial compression system and confining pressure system of the present invention;
FIG. 4 is a schematic view of an assembly structure of an industrial CT machine according to the present invention;
FIG. 5 is a schematic view of a housing part according to the present invention;
FIG. 6 is a schematic diagram of a lift cylinder structure of the confining pressure system of the present invention;
wherein: 1-a servo motor; 2, a speed reducer; 3-a connector; 4-a shell; 5-bearing sleeve; 6-a piston; 7-a lead screw; 8-a pressure chamber; 9-pressure chamber top; 10-pressure chamber bottom; 11-pressure chamber wall; 12-a bottom end connector; 13-the upper part of the turntable; 14-lower part of the turntable; 15-testing machine base seat; 16-tester base rigid columns; 17-a pressure sensor; 18-sample; 19-deep groove ball bearing; 20-thrust ball bearing; 21-an upper pressure head; 22-lower ram; 23-a detector; a 24-X-ray transmitter; 25-an X-ray source; 26-a drive motor; 27-a transmission reducer; 28-a transmission motor base; 29-driving screw; 30-a transmission bearing seat; 31-a transmission track groove; 32-lifting cylinder lifting rod; 33-iron pad; 34-lifting the oil cylinder base; 35-a vertical frame; 36-a screw; 37-lifting the cylinder beam; 38-locating holes.
Detailed Description
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.
The invention provides a test device and a test method for representing a cracking process of a soil-rock mixture and matching with an industrial CT machine, which can simulate dynamic disturbance on the soil-rock mixture on a dump site, namely, the internal deformation, crack development and damage of a sample in the cracking process can be known in real time under the condition of a cyclic loading experiment.
As shown in fig. 1 and 2, the device comprises an axial compression system, a confining pressure system and a scanning system, wherein the axial compression system comprises a servo motor 1, a speed reducer 2, a bearing sleeve 5, a piston 6, a shell 4 and a lead screw 7, the servo motor 1 is directly connected with the speed reducer 2, the servo motor 1 is connected with the bearing sleeve 5 through a connecting piece 3, the shell 4 is arranged at the lower part of the bearing sleeve 5, as shown in fig. 4, the piston 6 and the lead screw 7 are arranged in the shell 4, the piston 6 is connected with the lead screw 7, and the lower part of the lead screw 7 is connected with the confining pressure system; the confining pressure system comprises a pressure chamber 8, a pressure sensor 17, an upper pressure head 21, a lower pressure head 22, a lifting oil cylinder lifting rod 32, a lifting oil cylinder base 34 and a lifting oil cylinder beam 37, a sample 18 is fixed in the pressure chamber 8 through the upper pressure head 21 and the lower pressure head 22, the pressure sensor 17 is arranged on the upper portion of the upper pressure head 21, the lifting oil cylinder beam 37 stretches across two sides of the device, the middle portion of the lifting oil cylinder beam 37 is connected with a connecting piece 3, as shown in fig. 5, two ends of the lifting oil cylinder beam 37 are connected with the lifting oil cylinder lifting rod 32, and the lifting oil cylinder lifting rod 32 is fixed on the lifting oil cylinder base 34; the scanning system comprises X-ray transmitters 24 arranged on two sides of a pressure chamber 8, a detector 23, an X-ray source 25, a transmission motor 26, a transmission speed reducer 27, a transmission motor base 28, a transmission lead screw 29, a transmission bearing seat 30, transmission rail grooves 31, a vertical rack 35, screws 36 and positioning holes 38, wherein the transmission motor 26 and the transmission bearing seat 30 are fixed on the vertical rack 35 through the screws 36, the transmission motor 26 and the transmission speed reducer 27 are connected through the screws 36, the transmission speed reducer 27 and the transmission motor base 28 are connected through the screws 36, the transmission lead screw 29 is fixedly arranged at the upper end and the lower end of the vertical rack 35 through the transmission motor base 28 and the transmission bearing seat 30, the X-ray transmitters 24 and the detector 23 are respectively tightly connected with the transmission rail grooves 31 on the two sides, and the positioning holes.
As shown in fig. 6, the bearing sleeve 5 is internally provided with a deep groove ball bearing 19 and a thrust ball bearing 20, and when the deep groove ball bearing 19 only bears radial load, the contact angle is zero; the thrust ball bearing 20 is constituted by a washer-like race with a raceway groove in which balls roll.
The upper portion and the lower portion of the pressure chamber 8 are respectively a pressure chamber top portion 9 and a pressure chamber bottom portion 10, the middle of the pressure chamber 8 is a pressure chamber cylinder wall 11, the pressure chamber bottom portion 10 is connected with a rotary table upper portion 13 through a bottom connecting piece 12, a rotary table lower portion 14 is arranged below the rotary table upper portion 13, the rotary table lower portion 14 is installed on a testing machine base seat platform 15, and the testing machine base seat platform 15 is installed on a testing machine base rigid upright post 16.
As shown in fig. 3, an X-ray source 25 is provided on the X-ray emitter 24.
The axial pressure system and the confining pressure system are both arranged on the CT rotating table.
The axis of the test piece 18 is aligned with the axes of the upper ram 21 and the lower ram 22.
The upper ram 21 and the lower ram 22 rotate synchronously and the test piece 18 is not subjected to any torque.
The device adopts wireless intelligence to control, measures the circuit winding problem of connecting system rotatory in-process on the CT revolving stage during the solution test.
In actual design, the whole set of device adopts transparent aircraft glass material of high strength low density to pour into a mould once and make, and aircraft glass not only has excellent optical property, thermoplasticity and processability, ageing resistance, has characteristics such as proportion is little, high mechanical strength, resistance to compression tensile properties are outstanding moreover, and the ray energy attenuation condition when having improved X ray and passing the pressure chamber under satisfying the functional requirement, transparent material has also realized the visual to sample deformation destruction, can acquire the clear internal image of sample deformation in-process in real time. In addition, when confining pressure is applied to the pressure chamber, the pressure chamber also serves as a counter-force structure, and counter-force in the test process is born by the wall of the pressure chamber, so that corresponding design is carried out on parameters of the pressure chamber, and as the soil-rock mixture is a special geological material between a soil body and a broken rock body, the applied load required for breaking is small, so that the thickness of the wall of the pressure chamber is designed to be 7mm, the maximum tensile strength is 50kN, and the bearable maximum confining pressure is 10 MPa.
The method for specifically applying the test device comprises the following steps:
s1: preparing a soil-rock mixture sample with the diameter of 50 multiplied by 100mm, and wrapping the sample by a transparent plastic tube for testing;
s2: and starting the lifting oil cylinder, enabling the lifting oil cylinder lifting rod to drive the pressure chamber and the upper structure to rise, then installing the sample, and enabling the lifting oil cylinder lifting rod to descend after the sample is installed, so that the lifting oil cylinder lifting rod is stably connected with the rotary table through a bottom connecting piece. In the process, the axial lead of the sample needs to be aligned with the axial leads of the upper pressure head and the lower pressure head of the pressure chamber;
s3: checking the upper device of the rotary table to determine that the fixation is good;
s4: and closing the main power supply of the power distribution cabinet, and lighting a power supply indicator lamp to indicate that the main power supply works normally. Powering on each subsystem: sequentially closing power supplies of all subsystems, electrifying the X-ray emitter, electrifying the detector, the data acquisition system and the scanning control system;
s5: starting the X-ray machine, selecting a preheating mode according to the time length of the last shutdown and the present, and preheating. Simultaneously starting a computer system, establishing connection through an Ethernet and an optical machine, and transmitting a series of CT slices obtained by scanning to the computer;
s6: setting soil and stone mixture sample information, selecting or modifying scanning parameters (such as scanning height range, rotary table rotating speed, lifting speed, translation speed, step length, micro-motion parameters and the like) on a computer system control station;
s7: the scan begins. The X-ray machine emits beams, the detector receives signals, the scanning device subsystem completes various required movements, and the scanning control subsystem performs real-time control. The initial state of the soil-rock mixture can be obtained by scanning in the initial stage;
s8: if the single-shaft test is directly loaded and unloaded by the piston in a grading way, the step is skipped. If the triaxial real-time scanning test of the sample is carried out, a booster control valve is opened, nitrogen in the booster is filled into a pressure chamber along a reserved air duct, confining pressure is applied to the sample, and the booster control valve is closed when the confining pressure reaches a pressure value set by the test;
s9: and starting the servo motor to rotate at a certain speed, and further applying load to the sample. During scanning, the servo motor and the speed reducer are adjusted to change the loading of the sample, so that the effect of a complex stress disturbance path on the sample is achieved, and the simultaneous loading and scanning of the soil-rock mixture are realized. During the experiment, each stage of loading and unloading is carried out with one CT scanning. When scanning is finished each time, stopping the X-ray machine to emit beams, and stopping the motion of each device of the subsystem of the scanning device;
s10: when suspicious defects are found on the image, positioning the defect height on the image, and carrying out CT scanning reconstruction or secondary experiment on the specified detection height;
s11: closing the radioactive source of the CT machine, unloading the pressure chamber, dismantling the sample and ending the test;
s12: the S2-S11 are CT scanning tests under the condition of one-time soil-rock mixture cyclic loading, and S2-S11 are repeated for a plurality of tests;
s13: after all detection tasks are finished, after the X-ray machine is cooled, turning off a power supply of the X-ray machine, turning off a power supply of a computer and a power supply of a numerical control system, turning off switches of all subsystems and turning off a main power supply of the system;
s14: by means of VGStaudiMAX industrial computer tomography data processing software, fine reconstruction is carried out on a two-dimensional CT slice, a crack evolution (such as crack width, length and space position) process of the deformation and damage process of the soil-rock mixture under different stress states (single axis or three axes) and different stress levels is obtained, three-dimensional reconstruction, damage evolution description and damage variable analysis are carried out on the cracks of the soil-rock mixture, and visualization and digital representation of the soil-rock mixture fracture process are achieved.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. The utility model provides a soil-rock mixture fracture process characterization and supporting test device of CT machine which characterized in that: the device comprises an axial compression system, a confining pressure system and a scanning system, wherein the axial compression system comprises a servo motor (1), a speed reducer (2), a bearing sleeve (5), a piston (6), a shell (4) and a lead screw (7), the servo motor (1) and the speed reducer (2) are directly connected, the servo motor (1) and the speed reducer (2) are connected with the bearing sleeve (5) through a connecting piece (3), the shell (4) is arranged at the lower part of the bearing sleeve (5), the piston (6) and the lead screw (7) are arranged in the shell (4), the piston (6) is connected with the lead screw (7), and the lower part of the lead screw (7) is connected with the confining pressure system; the confining pressure system comprises a pressure chamber (8), a pressure sensor (17), an upper pressure head (21), a lower pressure head (22), a lifting oil cylinder lifting rod (32), a lifting oil cylinder base (34) and a lifting oil cylinder cross beam (37), a sample (18) is fixed in the pressure chamber (8) through the upper pressure head (21) and the lower pressure head (22), the pressure sensor (17) is arranged on the upper portion of the upper pressure head (21), the lifting oil cylinder cross beam (37) stretches across two sides of the device, the middle of the lifting oil cylinder cross beam (37) is connected with a connecting piece (3), two ends of the lifting oil cylinder cross beam (37) are connected with the lifting oil cylinder lifting rod (32), and the lifting oil cylinder lifting rod (32) is fixed on the lifting oil cylinder base (34); the scanning system comprises X-ray transmitters (24) arranged on two sides of a pressure chamber (8), a detector (23), an X-ray source (25), a transmission motor (26), a transmission speed reducer (27), a transmission motor base (28), a transmission lead screw (29), a transmission bearing seat (30), a transmission track groove (31), a vertical rack (35), a screw (36) and a positioning hole (38), wherein the transmission motor (26) and the transmission bearing seat (30) are fixed on the vertical rack (35) through the screw (36), the transmission motor (26) is connected with the transmission speed reducer (27) through the screw (36), the transmission speed reducer (27) is connected with the transmission motor base (28) through the screw (36), the transmission lead screw (29) is fixedly arranged at the upper end and the lower end of the vertical rack (35) through the transmission motor base (28) and the transmission bearing seat (30), the X-ray transmitters (24) and the detector (23) are respectively and tightly connected with the transmission track grooves (31) on, the vertical frame (35) is provided with a positioning hole (38).
2. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: a deep groove ball bearing (19) and a thrust ball bearing (20) are arranged in the bearing sleeve (5), and when the deep groove ball bearing (19) only bears radial load, a contact angle is zero; the thrust ball bearing (20) is constituted by a washer-shaped race having a raceway groove in which balls roll.
3. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: pressure chamber top (9) and pressure chamber bottom (10) are respectively on pressure chamber (8) upper portion and lower part, are pressure chamber section of thick bamboo wall (11) in the middle of pressure chamber (8), and revolving stage upper portion (13) are connected through bottom connecting piece (12) in pressure chamber bottom (10), and revolving stage lower part (14) set up below revolving stage upper portion (13), and revolving stage lower part (14) are installed on testing machine base platform (15), and testing machine base platform (15) are installed on testing machine base rigidity stand (16).
4. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: an X-ray source (25) is arranged on the X-ray emitter (24).
5. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: and the axial pressure system and the confining pressure system are both arranged on the CT rotary table.
6. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: the axial lead of the sample (18) is aligned with the axial leads of the upper press head (21) and the lower press head (22).
7. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: the upper ram (21) and the lower ram (22) rotate synchronously, and the sample (18) is not subjected to any torque.
8. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: the device adopts wireless intelligence to control.
9. The testing device matched with the CT machine for the soil-rock mixture fracture process characterization according to claim 1 is characterized in that: the whole device adopts the structure that the strength is not lower than 1000MPa, and the density is not more than 2.6g/cm3Is made of the transparent glass material.
10. The method for characterizing the testing device matched with the CT machine by using the fracture process of the soil-rock mixture as claimed in claim 1 is characterized in that: the method comprises the following steps:
s1: preparing a soil-rock mixture sample, and wrapping the soil-rock mixture sample by using a transparent plastic pipe to prepare a test;
s2: loading a sample into a pressure chamber, wherein the axial lead of the sample is aligned with the axial leads of an upper pressure head and a lower pressure head of the pressure chamber;
s3: checking the upper device of the rotary table to determine that the fixation is good;
s4: the power distribution cabinet main power supply is closed, the power indicator lamp is on, the main power supply works normally, and each subsystem is electrified: sequentially closing power supplies of all subsystems, electrifying the X-ray emitter, electrifying the detector, the data acquisition system and the scanning control system;
s5: starting an X-ray transmitter, selecting a preheating mode according to the time length of last shutdown till now, preheating, simultaneously starting a computer system, establishing connection with an optical machine through Ethernet, and transmitting the scanned CT slices to the computer;
s6: setting soil and stone mixture sample information and selecting or modifying scanning parameters on a computer system control station;
s7: when scanning starts, the X-ray transmitter emits beams, the detector receives signals, the scanning device subsystem completes various required motions, and the scanning control subsystem performs real-time control;
s8: after confining pressure is applied through the air duct, a servo motor is started, axial load is applied to the sample, the servo motor and a speed reducer are adjusted during scanning to enable the sample loading to change, so that the effect of a complex stress disturbance path on the sample is achieved, the simultaneous loading and scanning of the soil-rock mixture are achieved, the X-ray emitter stops emitting beams when each scanning is finished, and all devices of a subsystem of the scanning device stop moving;
s9: when suspicious defects are found on the image, positioning the defect height on the image, and carrying out CT scanning reconstruction or secondary experiment on the specified detection height;
s10: closing the radioactive source of the CT machine, unloading the pressure chamber, dismantling the sample and ending the test;
s11: repeating the above steps S2-S10 to perform the test;
s12: after all detection tasks are completed and the X-ray transmitter is waited for heat dissipation, the power supply of the X-ray transmitter is turned off, the power supply of the computer and the power supply of the numerical control system are turned off, switches of all subsystems are turned off, and the main power supply of the system is turned off;
s13: and analyzing the obtained test data, acquiring fracture evolution information of the sample under dynamic disturbance, and realizing visualization and digitization of the fracture process of the soil-rock mixture.
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