CN112782007A - Dynamic shearing and friction measuring device and method based on Hopkinson pressure bar - Google Patents
Dynamic shearing and friction measuring device and method based on Hopkinson pressure bar Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N19/00—Investigating materials by mechanical methods
- G01N19/02—Measuring coefficient of friction between materials
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- 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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention discloses a dynamic shearing and friction measuring device based on a Hopkinson pressure bar, which comprises a separated Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder, wherein the dynamic shearing and friction device comprises a cylindrical surrounding pressure cylinder; the split Hopkinson pressure bar comprises a transmitting device, and a waveform shaper, an incident rod, a transmission rod and an axial preloading device which are separated from the transmitting device; the dynamic shearing and friction device is arranged at the joint of the incident rod and the transmission rod and used for placing a sample, the cylindrical confining pressure cylinder sleeve is arranged on the dynamic shearing and friction device, and the cylindrical confining pressure cylinder and the axial preloading device are communicated with the oil cylinder through oil pipes. The invention also discloses a measuring method of the dynamic shearing and friction measuring device based on the Hopkinson pressure bar. The dynamic shearing and friction measuring device based on the Hopkinson pressure bar aims to solve the problems of how to realize the measurement of the dynamic shearing performance and the internal friction angle phi of a rock sample under the conditions of different loading rates and different normal stresses and the measurement of the dynamic friction performance.
Description
Technical Field
The invention belongs to the technical field of rock dynamic physical mechanics measurement, and particularly relates to a dynamic shearing and friction measuring device and a measuring method based on a Hopkinson pressure bar.
Background
In geotechnical engineering and geophysical applications involving different scales, rocks may be damaged by dynamic loads from drilling, blasting, landslide or earthquakes. According to statistics, tens of earthquakes which can cause serious harm to human beings occur every year on the earth, the earthquakes often cause serious casualties, and secondary disasters such as tsunamis, landslides, collapses, ground cracks and the like can be caused. The occurrence of an earthquake involves physical processes such as nucleation of pregnancy, fault instability and crack propagation, and has high complexity. Most earthquakes in the crust occur along the original fault, and a rock friction experiment is one of the main means in the experimental study of fault mechanics and seismic source physics. Cohesion and internal friction angles are two material parameters used in coulombic models to predict rock failure in many rock engineering and geophysical applications. Although both parameters have been extensively quantified using direct shear or triaxial compression methods under static conditions, the effect of dynamic loading on these parameters is not clear. Accordingly, it is desirable to develop a method of determining a dynamic shear strength parameter of a rock material.
At present, various scholars at home and abroad also develop partial related experiments to research the dynamic friction behavior. Such as the "disc needle" test, but it is designed for low speed friction experiments, where dynamic friction is only evaluated under steady state conditions; the pressure shear plate impact test is used for researching friction considering time factors, and can deduce normal stress and shear stress history at one point, but can not change the normal stress to research the friction characteristics. Recently, the method of the kelsky-tie has been used to measure the coefficient of dynamic friction between steel and aluminum. In this approach, the clamp is designed to promote sliding at the interface that is subject to dynamic tensile loads, and normal pressure is applied by screw torque on the friction clamp. However, this method is not suitable for rock-like materials due to the particular way in which normal pressure is applied.
In the seventies and eighties of the last century, based on low-speed rock friction experiment results, rate-state variable friction constitutive relations are established, and are widely applied to seismic simulation nowadays, but the constitutive relations and a large number of constitutive parameters obtained through low-speed experiments cannot well reflect the influence of loading rate on dynamic constitutive parameters of rocks.
In view of the above, it is desirable to provide a dynamic shear and friction measuring device and a measuring method based on a hopkinson pressure bar to solve the above problems.
Disclosure of Invention
Technical problem to be solved
The invention solves the technical problem of how to realize the measurement of the dynamic shearing performance and the internal friction angle phi value of the rock sample under the conditions of different loading rates and different normal stresses, and can simultaneously realize the measurement of the dynamic friction performance.
(II) technical scheme
The invention provides a dynamic shearing and friction measuring device based on a Hopkinson pressure bar, which comprises a separated Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder, wherein the cylindrical surrounding pressure cylinder is arranged on the separating Hopkinson pressure bar; the split Hopkinson pressure bar comprises an emitting device, and a waveform shaper, an incident rod, a transmission rod and an axial preloading device which are separated from the emitting device, wherein the incident rod is connected with the transmission rod, the waveform shaper is arranged at one end, close to the emitting device, of the incident rod, the axial preloading device is installed on the incident rod and the transmission rod, a first strain gauge is arranged on the incident rod, and a second strain gauge is arranged on the transmission rod;
the dynamic shearing and friction device is arranged at the joint of the incident rod and the transmission rod and used for placing a sample, the cylindrical confining pressure cylinder sleeve is arranged on the dynamic shearing and friction device, and the cylindrical confining pressure cylinder and the axial preloading device are communicated with the oil cylinder through oil pipes.
Further, the dynamic shearing and friction device comprises a guide tube and a rear support seat, the incident rod is movably arranged through the guide tube, and one end of the rear support seat is clamped on the transmission rod through the axial preloading device; the other end of the rear supporting seat is of a hollow structure and is abutted to the sample.
Furthermore, the tube-shape is enclosed and is pressed jar and is included first fender lid, second fender lid and both sealed confined pressure chamber that forms, first fender lid fixed connection in the stand pipe, the second fender lid with enclose and press chamber fixed connection and set up in can slide on the transmission pole.
Furthermore, the bottom of the cylindrical surrounding pressure cylinder is provided with an oil injection hole, and the top of the cylindrical surrounding pressure cylinder is provided with an exhaust hole; and hole plugs are arranged on the oil injection hole and the exhaust hole.
Furthermore, a round table is arranged at one end, close to the launching device, of the guide pipe and used for limiting the first blocking cover.
Further, the incident rod is provided with two first blocking covers along the radial direction thereof symmetrically and/or the transmission rod is provided with two second blocking covers along the radial direction thereof symmetrically.
Further, the axial preloading device comprises a first end portion, a second end portion and a plurality of connecting rods, wherein the first end portion is installed on the incident rod, the second end portion is installed on the transmission rod, the first end portion is abutted to the guide tube, and two ends of each connecting rod are respectively connected with the first end portion and the second end portion.
Further, the guide tube and the rear support base are coincident with the axes of the incident rod and the transmission rod.
The second aspect of the invention provides a measurement method of a dynamic shearing and friction measurement device based on a Hopkinson pressure bar, which comprises the following steps:
assembling a separated Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder;
placing a sample in the dynamic shearing and friction device, adjusting the sample to be coaxial, and then utilizing an axial preloading device to stably clamp the sample;
applying shaft pressure until the reading of the pressure gauge is a first preset value, and then injecting hydraulic oil into the cylindrical confining pressure cylinder until the reading of the pressure gauge is a second preset value;
dynamically loading the sample through the split Hopkinson pressure bar;
acquiring corresponding incident waves, reflected waves and transmitted waves through the first strain gauge and the second strain gauge;
and acquiring the dynamic shear stress and the dynamic friction stress under the corresponding loading rate condition according to the stress-time curve.
Further, the method for obtaining the dynamic shear strength and the dynamic friction coefficient under the condition of corresponding loading rate according to the stress-time curve specifically comprises the following steps:
the time t of the first peak of the stress-time curve0Corresponding dynamic shear stress value tau0Recording as dynamic shear strength; the internal friction angle phi of the sample under the dynamic loading condition can be obtained through the dynamic shear strength obtained by different under-pressure tests by a molar coulomb formula;
recording the occurrence time of the trough after the first wave peak as t'1And the corresponding stress value is recorded as tau'1And the occurrence time of the second peak is recorded as t'2And the corresponding stress value is recorded as tau'2Prepared from τ'2The first occurrence later (τ'1+τ'2) The time of/2 is recorded as the start time t of the dynamic friction process1And the corresponding stress value is recorded as tau1Time t at which the curve shows a significant steep decrease2The end time of the dynamic friction process is recorded, and the corresponding stress value is recorded as tau2；
Wherein the dynamic mean frictional stress faveThe expression of (a) is:
dynamic mean frictional stress faveThe preset ratio of the pressure difference to the cylindrical confining pressure cylinder is the dynamic friction coefficient.
(III) advantageous effects
The dynamic shearing and friction measuring device based on the Hopkinson pressure bar comprises a separated Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder; the split Hopkinson pressure bar is used for providing a dynamic loading condition; the dynamic shearing and friction device is used for realizing the dynamic shearing and dynamic friction process of the brittle material; the cylindrical confining pressure cylinder is used for providing confining pressure so as to realize the dynamic shearing and friction process of materials under different confining pressures. The test device has the advantages of simple structure, reasonable design and convenient use, can be applied to research and engineering application of rock shearing damage at medium-high speed, can realize measurement of dynamic shearing performance and internal friction angle phi of a rock sample under different loading rates and different normal stress conditions by combining a measurement method, can simultaneously realize measurement of dynamic friction performance, and is good in use effect and convenient to popularize.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a dynamic shear and friction measuring device based on a Hopkinson pressure bar according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of a cylindrical confining cylinder in a dynamic shearing and friction measuring device based on a Hopkinson pressure bar according to an embodiment of the present invention;
fig. 3 is a typical shear stress versus time graph.
In the figure:
101-a transmitting device; 102-bullet; 103-waveform shaper; 104-an incident rod; 105-a transmission rod; 106-axial preloading means; 1061-a first end; 1062-second end; 1063-connecting rod; 107-first strain gauge; 108-a second strain gage; 201-a guide tube; 202-rear support; 301-a first flap; 302-a second flap; 303-confining pressure cavity; 304-oil holes; 305-vent hole; 306-a hole plug; 4-sample; and 5, an oil cylinder.
Detailed Description
The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, i.e., the invention is not limited to the embodiments described, but covers any modifications, alterations, and improvements in the parts, components, and connections without departing from the spirit of the invention.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the drawings. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.
According to a first aspect of the embodiments of the present invention, there is provided a dynamic shearing and friction measuring apparatus based on a hopkinson pressure bar, as shown in fig. 1-2, including a split hopkinson pressure bar, a dynamic shearing and friction apparatus, and a cylindrical confining pressure cylinder; the split Hopkinson pressure bar comprises a transmitting device 101, a waveform shaper 103, an incident rod 104, a transmission rod 105 and an axial preloading device 106, wherein the waveform shaper 103, the incident rod 104, the transmission rod 105 and the axial preloading device 106 are separated from the transmitting device 101, the incident rod 104 is connected with the transmission rod 105, the waveform shaper 103 is arranged at one end, close to the transmitting device 101, of the incident rod 104, the axial preloading device 106 is installed on the incident rod 104 and the transmission rod 105, a first strain gauge 107 is arranged on the incident rod 104, and a second strain gauge 108 is arranged on the transmission rod 105;
the dynamic shearing and friction device is arranged at the joint of the incident rod 104 and the transmission rod 105 and is used for placing the sample 4, the cylindrical confining pressure cylinder sleeve is arranged on the dynamic shearing and friction device, and the cylindrical confining pressure cylinder and the axial preloading device 106 are communicated with the oil cylinder 5 through oil pipes.
In the above embodiments, the split hopkinson strut is used to provide the dynamic loading condition; the dynamic shearing and friction device is used for realizing the dynamic shearing and dynamic friction process of the brittle material; the cylindrical confining pressure cylinder is used for providing confining pressure so as to realize the dynamic shearing and friction process of materials under different confining pressures. The test device has the advantages of simple structure, reasonable design and convenient use, can be applied to research and engineering application of rock shearing damage at medium-high speed, can realize measurement of dynamic shearing performance and internal friction angle phi of a rock sample under different loading rates and different normal stress conditions by combining a measurement method, can simultaneously realize measurement of dynamic friction performance, and is good in use effect and convenient to popularize.
The working principle is as follows: after the bullet 102 is fired, it collides with the incident rod 104 through the wave shaper 103 to generate a compression stress wave, which propagates along the incident rod 104 to the sample 4 and further continues to propagate toward the transmission rod 105.
In some alternative embodiments, the dynamic shearing and friction device comprises a guide tube 201 and a rear support block 202, the input rod 104 is movably inserted through the guide tube 201, one end of the rear support block 202 is clamped on the transmission rod 105 by an axial preloading device 106; the other end of the rear holder 202 is hollow and abuts against the sample 4.
In the above embodiment, the punch of the dynamic shearing and rubbing device is replaced by the incident rod 104.
In some alternative embodiments, the cylindrical confining pressure cylinder includes a first blocking cover 301, a second blocking cover 302 and a confining pressure cavity 303 formed by sealing the first blocking cover 301 and the second blocking cover 302, the first blocking cover 301 is fixedly connected to the guide tube 201, and the second blocking cover 302 is fixedly connected to the confining pressure cavity 303 and slidably disposed on the transmission rod 105.
Specifically, the confining pressure chamber 303 provides confining pressure for the sample 4 while not causing an axial friction effect on the split hopkinson bar and the sample 4.
In some optional embodiments, the bottom of the cylindrical surrounding pressure cylinder is provided with an oil hole 304, and the top of the cylindrical surrounding pressure cylinder is provided with an exhaust hole 305; both the oil filling hole 304 and the exhaust hole 305 are provided with hole plugs 306.
In some alternative embodiments, the end of the guide tube 201 close to the launching device 101 is provided with a truncated cone for limiting the first blocking cover 301. The step is a guide tube section with a larger diameter to prevent the cylinder from moving to the side of the input rod 104 away from the sample 4. Wherein, the launching device 101 may be an air gun.
In some alternative embodiments, the incident rod 104 is symmetrically provided with two first shutters 301 along the radial direction thereof and/or the transmission rod 105 is symmetrically provided with two second shutters 302 along the radial direction thereof. Specifically, the two first blocking covers 301 and the two second blocking covers 302 are disposed up and down symmetrically, so that they can generate uniform force to the incident rod 104 and/or the transmission rod 104.
In the above embodiment, the first and second retainers 301 and 302 are circular caps each having a hole bored in the center thereof and are screwed to the cylindrical confining cylinder. Wherein, the hole diameter of the central hollow is slightly larger than the pipe diameter of the guide pipe 201 and the rod diameters of the incident rod 104 and the projection rod 105.
In some alternative embodiments, the axial preloading device 106 comprises a first end 1061, a second end 1062 and a plurality of connecting rods 1063, wherein the first end 1061 is mounted on the incident rod 104, the second end 1062 is mounted on the transmission rod 105, the first end 1061 abuts against the guide tube 201, and two ends of each connecting rod 1063 are respectively connected with the first end 1061 and the second end 1062.
The axial preloading device 106 is used for applying axial prestress to the test piece 4 and holding the test piece stably. Specifically, the first end portion 1061 and the second end portion 1062 may be rectangular plate-shaped structures, the number of the connecting rods 1063 is 4, and the four connecting rods 1063 are sequentially distributed at four corners of the first end portion 1061 and the second end portion 1062.
In some alternative embodiments, the guide tube 201 and the rear support 202 coincide with the axis of the input rod 104 and the transmission rod 105.
In a specific embodiment, the diameter of the input rod 104 is 25.4mm, the outer diameter of the guide tube 201 is 38mm, which is the same as the diameter of the sample 4, and the inner diameter of the guide tube 201 is 25.6mm, which is 0.2mm larger than the diameter of the input rod 104.
The guide tube 201 has a step on one side, the step has a height of 16mm and a length of 15mm, the step is a guide tube section with a larger diameter to prevent the cylindrical confining cylinder from moving to the side of the incident rod 104 away from the sample 4, and the length of the guide tube 201 is 110.5 mm.
The rear support base 202 is a circular groove, the outer diameter of the rear support base is 38mm, the thickness of the rear support base is 10mm, the inner diameter of the groove is 25.8mm, the diameter of the groove is slightly larger than the diameter of the incident rod 104 by 0.4mm, the groove depth is 5mm, the guide tube 201 is used for collecting rock cores, the guide tube 201 is fixed outside the incident rod 104, the rear support base 202 is clamped at the front end part of the transmission rod 104 by using the axial preloading device 106, the axes of the incident rod 104, the guide tube 201, the rear support base 202 and the transmission rod 105 are kept coincident and consistent, and when the incident rod 104 impacts the sample 4, the guide tube 201 can still ensure that the incident rod 104 can freely slide in the rear.
According to a second aspect of embodiments of the present invention, there is provided a measurement method of a dynamic shear and friction measurement device based on a hopkinson pressure bar, the method including the steps of:
s1, assembling a split Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder;
s2, placing the sample 4 in a dynamic shearing and friction device, adjusting the sample to be coaxial, and then utilizing an axial preloading device 106 to stably add and hold the sample 5;
s3, applying axial pressure until the indication number of the pressure gauge is a first preset value, and then injecting hydraulic oil into the cylindrical surrounding pressure cylinder until the indication number of the pressure gauge is a second preset value;
s4, dynamically loading the sample 4 through a split Hopkinson pressure bar;
s5, acquiring corresponding incident waves, reflected waves and transmitted waves through the first strain gauge 107 and the second strain gauge 108;
and S6, acquiring the dynamic shear stress and the dynamic friction stress under the corresponding loading rate condition according to the stress-time curve.
In the above embodiment, in step S2, sample 4 is preferably a disk sample having an aspect ratio of less than 1.
In some optional embodiments, in step S6, the method for obtaining the dynamic shear stress and the dynamic friction stress under the corresponding loading rate condition according to the stress-time curve specifically includes the following steps:
s601, enabling the time t of the stress-time curve to appear as a first peak0Corresponding dynamic shear stress value tau0Recording as dynamic shear strength; the internal friction angle phi of the sample under the dynamic loading condition can be obtained through the dynamic shear strength obtained by different under-pressure tests by a molar coulomb formula;
s602, recording valley occurrence time after first peak as t'1And the corresponding stress value is recorded as tau'1And the occurrence time of the second peak is recorded as t'2And the corresponding stress value is recorded as tau'2Prepared from τ'2The first occurrence later (τ'1+τ'2) The time of/2 is recorded as the start time t of the dynamic friction process1And the corresponding stress value is recorded as tau1Time t at which the curve shows a significant steep decrease2The end time of the dynamic friction process is recorded, and the corresponding stress value is recorded as tau2；
Wherein the dynamic friction stress faveThe expression of (a) is:
dynamic frictional stress faveThe preset ratio of the friction coefficient to the confining pressure cylinder is the dynamic friction coefficient.
In the above embodiment, the split hopkinson pressure lever, the dynamic friction device and the cylindrical surrounding pressure cylinder are completely assembled, so as to ensure that the bullet 102, the incident rod 104, the guide tube 201, the rear support seat 202 and the axial preloading device 106 are on the same axis;
attaching a first strain gauge 107 and a second strain gauge 108 to symmetrical positions on the incident rod 104 and the transmission rod 105 respectively;
winding the processed sample 4 along the circumferential direction by using a waterproof adhesive tape, placing the wound sample between the guide pipe 201 and the rear support base 202, adjusting the wound sample to be coaxial, starting the axial preloading device 106 to apply axial prestress less than 1MPa to the sample 4, and stably supporting the axial prestress;
the second blocking cover 302 of the cylindrical surrounding pressure cylinder is pushed to the left side, so that the cylindrical surrounding pressure cylinder is in close contact with the first blocking cover 301, then the cylindrical surrounding pressure cylinder is fixed by using bolts, the axial pressure is continuously applied until the reading of the pressure gauge is 9MPa, and then the oil injection hole 304 is used for injecting hydraulic oil into the cylindrical surrounding pressure cylinder until the reading of the pressure gauge is 20 MPa.
After the steps are completed, the sample can be dynamically loaded through the split Hopkinson pressure bar;
the incident wave and the reflected wave are measured by a first strain gauge on an incident rod 104, the transmitted wave is measured by a second strain gauge 108 of a transmission rod 105, and all strain gauge signals are transmitted to an eight-channel Sigma digital oscilloscope through a signal conditioner and a Wheatstone bridge;
time t at which the first peak appears in the stress-time curve0Dynamic shear strength τ corresponding to (125. mu.s)0About 75MPa, the starting time t of the dynamic friction process1175 mus, end time t of the dynamic friction process 2250 mus of
Knowing the mean dynamic frictional stress faveAbout 30 MPa; as shown in FIG. 3, FIG. 3(a) is a shear stress-time curve at a confining pressure of 0MPa, and FIG. 3(b) is a shear stress-time curve at a confining pressure of 20 MPa;
and after the impact is finished, removing the axial pressure by using the oil pump, removing the confining pressure by using the oil pump, unscrewing the bolt, and taking out the sample.
It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the drawings. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.
The above are merely examples of the present application and are not intended to limit the present application. Various modifications and alterations to this application will become apparent to those skilled in the art without departing from the scope of this invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. A dynamic shearing and friction measuring device based on a Hopkinson pressure bar is characterized by comprising a separated Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder; the split Hopkinson pressure bar comprises an emitting device (101), a waveform shaper (103), an incident rod (104), a transmission rod (105) and an axial preloading device (106), wherein the waveform shaper (103), the incident rod (104), the transmission rod (105) and the axial preloading device (106) are separated from the emitting device (101), the incident rod (104) is connected with the transmission rod (105), the waveform shaper (103) is arranged at one end, close to the emitting device (101), of the incident rod (104), the axial preloading device (106) is arranged on the incident rod (104) and the transmission rod (105), a first strain gauge (107) is arranged on the incident rod (104), and a second strain gauge (108) is arranged on the transmission rod (105);
the dynamic shearing and friction device is arranged at the joint of the incident rod (104) and the transmission rod (105) and used for placing a sample (4), the cylindrical confining pressure cylinder sleeve is arranged on the dynamic shearing and friction device, and the cylindrical confining pressure cylinder and the axial preloading device (106) are communicated with the oil cylinder (5) through oil pipes.
2. The hopkinson pressure bar-based dynamic shear and friction measuring device of claim 1, wherein the dynamic shear and friction device comprises a guide tube (201) and a rear support block (202), the incident bar (104) is movably disposed through the guide tube (201), and one end of the rear support block (202) is clamped to the transmission bar (105) by the axial preload device (106); the other end of the rear supporting seat (202) is of a hollow structure and is abutted to the sample (4).
3. The dynamic shear and friction measurement device based on the Hopkinson pressure bar according to claim 2, wherein the cylindrical confining pressure cylinder comprises a first blocking cover (301), a second blocking cover (302) and a confining pressure cavity (303) formed by sealing the first blocking cover (301) and the second blocking cover (302), the first blocking cover (301) is fixedly connected to the guide pipe (201), and the second blocking cover (302) is fixedly connected with the confining pressure cavity (303) and is slidably arranged on the transmission rod (105).
4. The dynamic shear and friction measurement device based on the Hopkinson pressure bar of claim 3, wherein an oil hole (304) is formed at the bottom of the cylindrical surrounding cylinder, and an exhaust hole (305) is formed at the top of the cylindrical surrounding cylinder; and hole plugs (306) are arranged on the oil filling hole (304) and the exhaust hole (305).
5. The dynamic shear and friction measurement device based on a Hopkinson pressure bar according to claim 3, wherein one end of said guide tube (201) near said launcher (101) is provided with a truncated cone for limiting said first stop cover (301).
6. The Hopkinson pressure bar based dynamic shear and friction measurement device according to claim 3, wherein said incident bar (104) is provided with two said first shield caps (301) symmetrically along its radial direction and/or said transmission bar (105) is provided with two said second shield caps (302) symmetrically along its radial direction.
7. The Hopkinson pressure bar based dynamic shear and friction measurement device according to claim 2, wherein said axial preloading device (106) comprises a first end portion (1061), a second end portion (1062) and a plurality of connecting rods (1063), said first end portion (1061) is mounted on said incident rod (104), said second end portion (1062) is mounted on said transmission rod (105), said first end portion (1061) is abutted to said guide tube (201), and both ends of each of said connecting rods (1063) are respectively connected to said first end portion (1061) and said second end portion (1062).
8. The hopkinson pressure bar-based dynamic shear and friction measuring device of claim 2, wherein the guide tube (201), the rear support pedestal (202) coincide with the axis of the incident bar (104) and the transmission bar (105).
9. A method of measurement based on a hopkinson pressure bar based dynamic shear and friction measuring device of any one of claims 1 to 8, comprising the steps of:
assembling a separated Hopkinson pressure bar, a dynamic shearing and friction device and a cylindrical surrounding pressure cylinder;
placing a test sample (4) in the dynamic shearing and friction device, adjusting the test sample to be coaxial, and then using an axial preloading device (106) to stably hold the test sample (5);
applying shaft pressure until the reading of the pressure gauge is a first preset value, and then injecting hydraulic oil into the cylindrical confining pressure cylinder until the reading of the pressure gauge is a second preset value;
dynamically loading the sample (4) through the split Hopkinson pressure bar;
acquiring corresponding incident waves, reflected waves and transmitted waves through a first strain gauge (107) and a second strain gauge (108);
and acquiring the dynamic shear stress and the dynamic friction stress under the corresponding loading rate condition according to the stress-time curve.
10. The method for measuring a dynamic shear and friction measuring device based on a hopkinson pressure bar according to claim 9, wherein the method for obtaining the dynamic shear strength and the dynamic friction stress under the condition of corresponding loading rate according to the stress-time curve specifically comprises the following steps:
the time t of the first peak of the stress-time curve0Corresponding dynamic shear stress value tau0Recording as dynamic shear strength; the internal friction angle phi of the sample under the dynamic loading condition can be obtained through the dynamic shear strength obtained by different under-pressure tests by a molar coulomb formula;
recording the occurrence time of the trough after the first wave peak as t'1And the corresponding stress value is recorded as tau'1And the occurrence time of the second peak is recorded as t'2And the corresponding stress value is recorded as tau'2Prepared from τ'2The first occurrence later (τ'1+τ'2) The time of/2 is recorded as the start time t of the dynamic friction process1And the corresponding stress value is recorded as tau1Time t at which the curve shows a significant steep decrease2The end time of the dynamic friction process is recorded, and the corresponding stress value is recorded as tau2；
Wherein the dynamic mean frictional stress faveThe expression of (a) is:
dynamic mean frictional stress faveThe preset ratio of the pressure difference to the cylindrical confining pressure cylinder is the dynamic friction coefficient.
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