CN112540005A - Experimental device and experimental method for measuring tensile strength of rock through centrifugal loading - Google Patents
Experimental device and experimental method for measuring tensile strength of rock through centrifugal loading Download PDFInfo
- Publication number
- CN112540005A CN112540005A CN202011499757.1A CN202011499757A CN112540005A CN 112540005 A CN112540005 A CN 112540005A CN 202011499757 A CN202011499757 A CN 202011499757A CN 112540005 A CN112540005 A CN 112540005A
- Authority
- CN
- China
- Prior art keywords
- rock sample
- rock
- force
- tensile strength
- holder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/16—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces applied through gearing
- G01N3/165—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces applied through gearing generated by rotation, i.e. centrifugal force
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention discloses an experimental device and an experimental method for measuring tensile strength of a rock by centrifugal loading, and aims to enable a rock sample to rotate at a high speed through a loading device, so that centrifugal force is generated at two ends of the rock sample, and the tensile strength of the rock sample is accurately measured by replacing the tensile force of the rock sample with the centrifugal force. The technical scheme adopted by the method is as follows: experimental device includes motor (1), and motor (1) passes through transmission shaft (3) and drives carousel (4) to make the rock sample that presss from both sides in two supports (8) rotatory around its center, install on mount (6) through embedding nut (13) support (8), it has certain contact to be equipped with force sensing resistance box (7) on mount (6) and rock sample, is used for surveying the rotational speed of rock sample when producing the crack, passes through signal output part (2) with these data again with wireless mode transfer to computer (14) in, reachs the relation of rock tensile strength sigma and rock deformation epsilon.
Description
Technical Field
The invention belongs to the technical field of rock experiments, and particularly relates to a device for measuring tensile strength of a rock by using a centrifugal loading method and an experiment method.
Background
At present, the tensile strength of the rock can be tested into two types, one is an indirect tensile test, such as a Brazilian splitting method, a point loading method, a square plate-to-shaft fracturing test and the like. The most widely used method is the Brazilian splitting method, namely, an upper filler strip and a lower filler strip are placed in the diameter direction of a cylindrical rock test piece, and opposite linear loads are applied to the test piece to enable the test piece to be damaged along the diameter direction of the test piece, so that the tensile strength of the test piece can be indirectly measured. The other type is a direct tensile test, the tensile strength test of the sample is carried out by clamping two ends of the sample by a clamp, but the stress concentration occurs at the position clamped by the clamp, such as a rock tensile strength test and a test method (CN201810463521.9), and the method has certain limitation due to the brittleness of the rock. At present, a Hopkinson bar experiment is carried out on the rock tensile strength directly and accurately, but the manufacturing cost is high, and the occupied area also has certain requirements. Although direct tensile testing for tensile strength of rock suffers from various difficulties, the method of pursuing other direct tensile tests is a breakthrough path for accurate testing of tensile strength of rock relative to the error of indirect tensile testing.
The existing experimental instrument and the experimental method (201510145188.3) for measuring the tensile strength of a soil body by utilizing centrifugal force provide ideas for the invention, namely an experimental device for measuring the tensile strength of rock by centrifugal loading and an experimental method matched with the experimental device are designed.
Disclosure of Invention
In order to solve the technical problem in the prior art, the invention provides an experimental device and an experimental method for measuring the tensile strength of a rock by centrifugal loading.
The experimental objects of the invention are a rock sample with tensile strength not more than about 15MPa and a rock soil sample poured artificially (for the upper limit constraint of the tensile strength test, the upper limit constraint is influenced by the maximum rotating speed of the current motor, the power of the motor is determined according to the requirement when the device is manufactured, the upper limit of the tensile strength determined by the invention is approximately determined according to the rotating speed of 20000 r/min.), and for the rock exceeding the tensile strength, the rock can be manufactured by using the motor with higher rotating speed, or the rock soil can be tested by using a Brazilian splitting experiment and a Hopkinson pull rod experiment method. The following description will be made only for the rock sample having grooves at both ends, and the other types of samples have the same principle.
The rock sample with grooves at two ends is horizontally placed in the device, the center of the sample is used as an axis for horizontal rotation, the centrifugal force generated by high-speed rotation in opposite directions at two ends of the rock sample is used for replacing the tensile force to enable the rock sample to be pulled and cracked so as to meet the direct tensile test of the tensile strength of the rock, the situation that the rock sample is pulled and cracked under the conditions of different rotating speeds is measured through the corresponding device, and a graph about the tensile strength sigma of the rock and the function of the deformation epsilon of the rock is formed according to different tensile stresses of the rock sample and the pulling and cracking degree of the rock sample through the corresponding computer program.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
an experimental device for measuring tensile strength of rock by centrifugal loading comprises a motor, wherein the motor is controlled by a frequency converter (the rotating speed of the motor is controlled by the frequency converter and the rotating speed of the motor is transmitted to a program of a computer by the wireless connection of the frequency converter), and the motor is connected with a transmission shaft;
furthermore, one end of the transmission shaft is connected with the motor, and the other end of the transmission shaft is provided with a gear which is used for being meshed with the turntable;
furthermore, the turntable is a circular cylinder and is divided into an upper part and a lower part, the inner side of the lower part of the turntable is provided with a gear which is used for being meshed with the gear at one end of the transmission shaft, the upper part of the turntable is used for installing a circuit, and meanwhile, the upper surface of the turntable is provided with two fixing frames;
furthermore, the main body structure of the fixing frame is a hollow rod, the upper part of the rod is provided with a certain part of threaded grooves, a force sensitive resistor box is arranged on the outer side of a part below the threaded grooves of the fixing frame, a small hole is reserved in the fixing frame at the position where the force sensitive resistor box is arranged, the two fixing frames are arranged on the same diameter of a circular ring on the upper surface of the rotary table, namely one end of each fixing frame is fixed on the upper surface of the rotary table, and the other end of each fixing frame is provided with a threaded groove for connecting a support;
furthermore, the resistance regulating valve is arranged on the outer side of the force-sensitive resistance box and used for regulating the length of the spring telescopic rod so as to regulate the initial pressure of the force-sensitive resistance and the rock sample, and the small hole at the installation position of the force-sensitive resistance box is used for connecting a circuit, namely, the pressure state borne by the force-sensitive resistance is transmitted to a signal output end through an electric signal and then transmitted to a program of a corresponding computer from the signal output end through wireless connection;
furthermore, the threaded groove fixes the support at the upper end of the fixing frame by embedding a nut; the embedded nut is connected with the bracket through threads on the inner side, and is connected with the fixed frame through threads on the outer side;
furthermore, the support is shaped like a 'T', the lower end of the support is provided with a thread and is used for being screwed on the inner side of the embedded nut, in addition, one end of the upper part of the support is also provided with a thread and is provided with a counterweight ring, the other end of the upper part of the support is provided with a hollow rod, the end of the upper part of the support is provided with a fixing pad and is used for supporting the weight of the rock sample, and meanwhile, the position of the fixing pad in a groove of the rock sample can be adjusted to ensure that the connecting line of the center of;
furthermore, the counterweight ring is a nut with certain mass and arranged at one end of the bracket, and the counterweight ring rotates on a thread at one end of the bracket, so that the rock sample is bounded by the center of the rock sample, and the left part and the right part are balanced, and the rock sample can rotate around a connecting line between the center of the rock sample and the circle center of the turntable;
furthermore, the fixing pad is filled with gas through the hollow end of the support, so that the loading pad is in close contact with the inner wall of the groove of the rock sample to transfer the weight of the rock sample to the support, and meanwhile, the fixing pad can provide gradually increased tangential force which is always horizontally vertical to the rock sample for the rock sample in the experimental process;
furthermore, when the rotation of the rock sample reaches a certain speed, the pressure of the force sensitive resistor contacted with the rock sample is increased when the rock sample generates cracks, the resistance value of the force sensitive resistor is changed, the current value of the whole circuit is further influenced, and then a current signal of the circuit and the rotating speed of the motor are transmitted to a corresponding computer program through a signal output end in a wireless connection mode;
furthermore, the shell is used for providing an approximate vacuum environment for the experiment so as to reduce the resistance brought by air when the rock sample rotates, and for achieving the purpose, the shell needs to cover the whole experiment device, and then the air in the shell is extracted through an air extraction valve of the shell so as to obtain the approximate vacuum environment in the shell.
Furthermore, in order to adjust the horizontal rotation of the turntable and the stability of the whole device, the lower end of the motor is provided with a base which is used for fixing the motor, meanwhile, the base is connected with a stabilizing frame, and the stability of the whole device during operation is jointly ensured through the combination of four stabilizing frames with the horizontal included angle of 90 degrees;
furthermore, one end of the stabilizing frame is connected with the base through a nut, and the other end of the stabilizing frame longitudinally penetrates through the stabilizing frame through a frame foot to adjust the height of the stabilizing frame, so that the stability of the device in operation is guaranteed, the rotating disc can be horizontally placed, and meanwhile, a coarse adjustment effect can be achieved on the horizontal state of the rock sample.
According to the experimental method, the centrifugal force replaces the tensile force through centrifugal loading, the trouble that the rock sample cannot be clamped due to brittleness is ingeniously avoided, the centrifugal loading is directly carried out on the rock sample, the actual tensile strength of the rock sample can be directly measured, and a function diagram can be drawn for the tensile strength sigma of the rock and the deformation epsilon of the rock through a corresponding program. And to the interference of experimentation, also can be accurate before the experiment record, so can improve the tensile strength's of rock sample precision.
Drawings
FIG. 1 is a schematic of the construction of the apparatus of the present invention;
FIG. 2 shows the engagement of the drive shaft with the gear of the turntable;
FIG. 3 is a connecting view of the bracket and the fixing frame;
FIG. 4 is a top view of the stabilizer and base;
FIG. 5 is an analysis diagram of rock tension measurement and calculation;
in the figure: 1. a motor; 2. a signal output terminal; 3. a drive shaft; 4. a turntable; 5. a circuit; 6. a fixed mount; 7. a force sensitive resistor cartridge; 8. a support; 9. a fixing pad; 10. a rock sample groove; 11. an exhaust valve; 12. a housing; 13. embedding a nut; 14. a computer; 15. a stabilizer frame; 16. a base;
wherein: 6-1, fixing frame threads; 6-2, reserving small holes;
7-1, resistance regulating valve; 7-2, force sensitive resistance; 7-3, a spring telescopic rod;
8-1, a counterweight ring; 8-2, an air inlet valve; 8-3, support screw threads; 8-4, counterweight threads;
15-1, a stand leg; 15-2, a nut;
the specific implementation mode is as follows:
the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, 2 and 3, an experimental device and an experimental method for measuring tensile strength of rock by centrifugal loading,
preparation work before the experiment: taking a rock sample as an example (the specification of the rock sample is that the specific gravity is gamma, the height is L, the radius is R, the radius of the opened groove is R, and the depth is m), one end of the bracket (8) with the fixing pad (9) is plugged into the rock sample groove (10). Then recording the pressure P of the gas filled in the fixed pad (9) so that the fixed pad (9) is just clamped at the groove (10) of the rock sample, and then measuring the maximum static friction force f between the fixed pad (9) and the rock sample horizontally placed by a dynamometermax(ii) a And when the fixing pad (9) is plugged into the rock sample groove (10) by the bracket (8), the same pressure P is filled into the fixing pad.
Furthermore, frame feet (15-1) on the adjusting stabilizing frame (15) are guaranteed not to shake when the whole device operates through the stabilizing base (16), and meanwhile, a horizontal measuring scale is placed on the upper surface of the rotary table, so that the rotary table can reach a horizontal state when the frame feet (15-1) are adjusted.
Further, the embedded nut (13) is screwed with the thread at the lower end of the bracket (8), then the bracket (8) is placed on the fixed frame (9), the embedded nut (13) is rotated reversely, and then the bracket (8) is fixed on the fixed frame (9); further, the force sensitive resistor box (7) is adjusted to enable the force sensitive resistor (7-2) and the rock sample to have initial pressure, and further, after the support (8) is fixed, the counterweight ring (8-1) at the other end of the support (8) is adjusted to enable the rock sample to rotate around the line between the center of the rock sample and the center of the circle of the turntable (4) when the rock sample is loaded.
The experimental process comprises the steps that a motor (1) is started, a rotating disc (4) is driven through a transmission shaft (3), a fixing frame (6), a support (8) and a rock sample are driven to rotate (the rotating speed of the motor can be controlled, namely, the rotation of the motor is in a gradually accelerated state, so that the rock sample is in the gradually accelerated state) and accelerated for a certain time, the centrifugal force of the left end and the centrifugal force of the right end of the rock sample are increased, when the tensile strength of the rock sample is achieved, the rock sample can generate cracks, the pressure of a force sensitive resistor (7-2) can be changed at the moment, current signals of a circuit (5) can be transmitted to a computer (14) through wireless connection on a pressure display (2), and the pressure f borne by the two force sensitive resistors on the fixing frame at the left end and the right end of the rock sample at the moment is given through a1And f2And simultaneously recording the rotating speed omega of the motor at the moment.
Data processing for the experiment: the rock sample is rotated in such a way that the centrifugal force applied to the center of the sample is theoretically the largest, but the rock sample does not necessarily generate cracks from the center, so that the force applied to the force sensitive resistors (7-2) at the left and right ends of the rock sample may be different, and the minimum value of the two forces is taken, and f is assumed to be the minimum value2At a minimum and a fracture-to-center distance of n (for a sample fracture, it is desirable to have the fracture occur as much as possible in the solid portion between two rock sample grooves (10), the ratio R/R can be increased as much as possible, or the ratio L/m can be increased) the experimental results are taken as the fracture between the grooves:
as shown in fig. 5, it is easy to know that:
Fpulling device＝FCentrifugal force-fmax-f2
Because the tensile strength of the existing rock is mostly less than 15MPa, the specific gravity of the rock is between 2.0 and 5.0, the requirement can be met when the rotating speed of the rock sample reaches about 20000r/min through preliminary estimation, and the type of the motor can be selected as required when the device is manufactured.
From the above, the following features of the present device can be summarized:
1) this device replaces pulling force to carry out direct tensile experiment to the rock sample through centrifugal force, and its tensile strength who surveys more accords with the reality.
2) This device can make the functional diagram out through the wireless connection of circuit with the condition of the tensile strength experiment of rock sample through corresponding procedure to rock tensile strength sigma and rock deformation epsilon.
3) The manufacturing of this device surveys the tensile strength of rock for hopkinson pole, and its manufacturing cost can some less relatively, and area also can be less.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim as designed.
Claims (5)
1. The utility model provides an experimental apparatus for tensile strength of rock is surveyed in centrifugal loading which characterized in that: the motor comprises a motor (1), wherein the motor (1) is connected with a transmission shaft (3), the motor (1) transmits power to a turntable (4) which is meshed with the transmission shaft (3) through a gear through the transmission shaft (3) which is connected with the motor, the turntable (4) rotates to drive a fixing frame (6) arranged on the turntable to rotate, and the fixing frame (6) rotates to drive a support (8) arranged on the fixing frame to rotate. The rotation of the bracket (8) drives the rotation of the rock sample with one end clamped in the rock sample groove (10), so that the rotation of the rock sample is realized, and the two ends of the rock sample generate centrifugal forces with opposite directions.
2. The device according to claim 1, wherein the rotary table (4) is a circular cylinder divided into an upper part and a lower part, the inner side of the lower part of the rotary table (4) is provided with a gear for meshing with the gear at one end of the transmission shaft (3), the upper part of the rotary table (4) is used for installing the circuit, and the two ends of the same diameter at the upper surface of the rotary table (4) and the same distance from the center of the rotary table (4) are respectively provided with a fixed frame (6).
3. The device according to claim 1, characterized in that the holder (6) is a hollow rod, the upper part of the rod is provided with a certain part of holder thread (6-1), the outer side of the part below the holder thread (6-1) of the holder (6) is provided with a force sensitive resistor box (7), and the holder is provided with a reserved small hole (6-2) at the position where the force sensitive resistor box (7) is arranged, one end of the holder (6) is fixed on the upper surface of the turntable (4), and the other end is provided with a holder thread (6-1) for connecting the bracket (8) by an embedded nut (13).
4. The device according to claim 1, characterized in that the force-sensitive resistor box (7) is provided with a resistance adjusting valve (7-1) on the outer side thereof for adjusting the length of the spring telescopic rod so as to adjust the initial pressure of the force-sensitive resistor (7-2) and the rock sample, and a reserved small hole (6-2) at the installation position thereof is used for connecting a circuit, namely, the pressure state of the force-sensitive resistor (7-2) is transmitted to the signal output end (2) through an electric signal, and then corresponding data is transmitted to a program of a corresponding computer (14) from the signal output end through a wireless connection.
5. The device according to claim 1, characterized in that the fixing mat (9) is arranged to fill the fixing mat (6) with gas through the hollow end of the holder (8) so that the fixing mat (6) is in close contact with the inner wall of the rock sample recess (10) for transferring the weight of the rock sample to the holder (8) while providing a tangential force to the rock sample so that the rock sample is always accelerated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011499757.1A CN112540005A (en) | 2020-12-18 | 2020-12-18 | Experimental device and experimental method for measuring tensile strength of rock through centrifugal loading |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011499757.1A CN112540005A (en) | 2020-12-18 | 2020-12-18 | Experimental device and experimental method for measuring tensile strength of rock through centrifugal loading |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112540005A true CN112540005A (en) | 2021-03-23 |
Family
ID=75019022
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011499757.1A Pending CN112540005A (en) | 2020-12-18 | 2020-12-18 | Experimental device and experimental method for measuring tensile strength of rock through centrifugal loading |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112540005A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113188906A (en) * | 2021-04-25 | 2021-07-30 | 重庆科技学院 | Rock uniaxial tension test device and method |
-
2020
- 2020-12-18 CN CN202011499757.1A patent/CN112540005A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113188906A (en) * | 2021-04-25 | 2021-07-30 | 重庆科技学院 | Rock uniaxial tension test device and method |
| CN113188906B (en) * | 2021-04-25 | 2022-05-20 | 重庆科技学院 | Rock uniaxial tension test device and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN201517988U (en) | Testing device of rheological behavior of magnetorheological fluid | |
| CN108318165B (en) | Bearing dynamic friction torque tester | |
| CN104880308B (en) | A kind of main shaft axial force isostatic pressed loading device | |
| CN210741740U (en) | Calibration device for torque sensor | |
| CN103411764B (en) | A kind of inner rotor type gyro motor proving installation | |
| CN112540005A (en) | Experimental device and experimental method for measuring tensile strength of rock through centrifugal loading | |
| CN109030267B (en) | Friction test device and test method thereof | |
| CN203432677U (en) | Dynamic calibration device of eddy current sensor | |
| CN106568658A (en) | Device and method for measuring different torsion and stretching properties of material in micro-nano level | |
| CN106123939B (en) | A kind of magnetic suspension sensor rigidity testing system and test method | |
| CN214150236U (en) | Experimental device for tensile strength of rock is surveyed in centrifugal loading | |
| CN211552699U (en) | Verticality measuring tool for long bolt installation screw hole | |
| CN110567731B (en) | Double-rotation brake performance tester inspection bench | |
| CN109781320B (en) | Friction moment tester and testing method for bearing without inner ring | |
| CN212559000U (en) | Main hoisting winch rope lining wearing and tearing volume rapid detection device | |
| CN207717804U (en) | A kind of wheel speed calibrating installation | |
| CN203287104U (en) | An accelerated speed vibration intensity sensor mounting structure | |
| CN108092475B (en) | A kind of assembling detection device of electric machine casing positioning bushing | |
| CN208953200U (en) | A kind of grinding wheel mass balance detection device | |
| CN209027789U (en) | Transmission test device based on Circular gratings | |
| CN208818151U (en) | A kind of external ball cage axiality detection device | |
| CN107014535A (en) | Conducting slip ring moment of friction device for accurately measuring | |
| CN106483067A (en) | Critical coefficient of rolling friction measures device and method | |
| CN206177216U (en) | Angle calibration and check out test set | |
| CN108254589B (en) | Positive step gravity acceleration generating device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |