CN110441172B - Osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and test method - Google Patents
Osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and test method Download PDFInfo
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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
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/30—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight
- G01N3/317—Investigating strength properties of solid materials by application of mechanical stress by applying a single impulsive force, e.g. by falling weight generated by electromagnetic means
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- 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
- G01N2203/0001—Type of application of the stress
- G01N2203/001—Impulsive
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- 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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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract
The invention provides an osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and a testing method. The invention is based on the traditional one-dimensional SHPB, improves original equipment innovatively, introduces a loading and control system during infiltration compaction, and solves the technical problem that the existing dynamic test device cannot develop the research on the dynamic response of the rock mass under the coupling action of high infiltration water pressure, static pressure and dynamic disturbance, which is close to the real environment of the deep rock mass.
Description
Technical Field
The invention belongs to the field of rock dynamics research. More particularly, the invention relates to an osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and a test method for researching the rock dynamics characteristics and breaking mechanism under a deep underground real multi-field coupling environment. shPB: hopkinson bar.
Background
As shallow mineral resources are continuously exhausted, resource and energy exploitation gradually turns to deep development, and future deep exploitation becomes normalized. However, after deep mining, the environment in which the rock mass is located becomes very complex, and the deep in-situ rock mass is not only subjected to high-amplitude three-dimensional stress, but also often subjected to high osmotic water pressure and strong engineering disturbance (such as explosion waves, earthquakes, rock burst and the like), so that engineering disasters (such as rock burst, large deformation and the like) are frequent, and the safety of deep rock mass engineering is seriously endangered. Therefore, the research and the disclosure of the dynamic mechanical response and the destruction mechanism of the rock mass under the impact load effect under the deep ground stress-osmotic pressure coupling environment have very important significance for the development and the utilization of the deep underground rock mass engineering. At present, the research on the dynamic characteristics of the rock mass under the deep complex condition is mainly represented by the research on dynamic impact loading test based on a traditional one-dimensional Hopkinson pressure bar (SHPB) and the research on dynamic and static combined impact loading three-dimensional SHPB by utilizing an improved SHPB system, and although the research greatly promotes people to know the dynamic response rule of the rock mass under the deep high ground stress and dynamic impact loading condition, the existing research does not consider that the deep rock mass is actually under the static pressure and high osmotic water pressure and dynamic disturbance complex environment condition, so that the existing research result cannot truly, effectively and comprehensively reflect the dynamic mechanical characteristics and the destruction rule of the deep in-situ rock mass under the deep complex condition. The method is mainly used for considering the defect of research means of rock dynamics test under deep complex conditions, in particular to the defect of equipment for researching the dynamic characteristics and breaking mechanism of rock mass under the coupling action condition of simulating deep osmotic pressure and static pressure. Accordingly, there is a need in the art for improvement.
Disclosure of Invention
The invention provides a triaxial SHPB device for osmotic pressure and static force coupling electromagnetic loading and a testing method, which are used for improving original equipment creatively based on traditional one-dimensional SHPB, introducing an osmotic compaction loading and controlling system and solving the technical problem that the existing dynamic test device cannot develop rock mass dynamic response research under the coupling action of high osmotic water pressure, static pressure and dynamic disturbance close to the real environment of a deep rock mass.
The osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device comprises an electromagnetic pulse transmitting system, a spindle pressure servo control loading system, a confining pressure servo control loading system, an osmotic pressure loading system, a rod system and a data monitoring and collecting system.
The osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device is arranged in a bilateral symmetry mode by a supporting platform foundation platform, and the supporting platform plays a role in rough leveling device foundation and bearing self weight of the whole system and impact load in the testing process. The electromagnetic pulse emission system mainly comprises left and right electromagnetic pulse excitation cavities with the same processing parameters, processes and functions and a control system thereof, and mainly plays a role in providing dynamic load (incident stress wave) for the test system; the axial pressure servo control loading system mainly comprises left and right axial pressure loading fixed baffles, a connecting rod, left and right axial pressure loading oil cylinders, an axial pressure loading piston and an axial pressure servo control system, and mainly plays a role of providing axial static prestress for a test sample, and the axial pressure servo control loading system has the functions of loading, maintaining and unloading of a programmed control oil source system and can ensure that static axial pressure is kept relatively stable in the test process; the confining pressure servo control loading system mainly comprises a confining pressure loading cylinder confining baffle, a confining pressure loading cylinder, a screw, a confining pressure loading oil inlet, a confining pressure loading exhaust port sealing plug, a confining pressure oil meter and a confining pressure servo control system, and mainly plays a role in providing annular static pre-stress for a test sample, and the confining pressure servo control loading system has the functions of loading, maintaining and unloading a programmed control oil source system and can ensure that the static annular confining pressure is kept relatively stable in the test process; the osmotic pressure loading system mainly comprises a left osmotic pressure pipeline, a right osmotic pressure pipeline and an osmotic pressure pressurizing and controlling system, and mainly plays a role in providing pore water pressure and osmotic pressure for a test sample or providing water pressure in a hole for a sample containing an internal hole; the rod piece system mainly comprises left and right stress wave loading rods and supports thereof, wherein the diameters, the lengths and the materials of the left and right stress wave loading rods are equal to each other, and the left and right stress wave loading rods and the supports thereof meet different test requirements, and mainly play roles in transmitting incident stress waves and applying dynamic loads to test samples; the data monitoring and collecting system mainly comprises a multichannel high-speed synchronous recorder, a strain gauge, a Wheatstone bridge and a strain signal amplifier, and plays a role in real-time monitoring and completely recording and storing test signals.
In order to solve the problems in the prior art, the invention provides an osmotic pressure and static force coupling electromagnetic loading triaxial SHPB device, which comprises a supporting platform, a left axial pressure loading fixed baffle, a left axial pressure loading oil cylinder, a left axial pressure loading piston, a left electromagnetic pulse excitation cavity support, a connecting rod, a left stress wave loading rod, a stress wave loading rod support, a resistance strain gauge, a right axial pressure loading fixed baffle, a right axial pressure loading oil cylinder, a right axial pressure loading piston, a right electromagnetic pulse excitation cavity support, a right axial pressure wave loading rod, a confining pressure loading cylinder enclosure, a confining pressure loading cylinder, a connecting screw rod, a confining pressure loading oil inlet, a confining pressure loading exhaust port sealing plug, a confining pressure oil meter, a left osmotic pressure pipeline, a right osmotic pressure pipeline, a test sample and a rubber sleeve;
the device takes a test sample as a center and is arranged in a bilateral symmetry mode, wherein a left side axial pressure loading fixed baffle and a right side axial pressure loading fixed baffle are respectively fixed at the left end and the right end of a supporting platform, center mounting holes and peripheral mounting holes are respectively formed in the center and the periphery of the left side axial pressure loading fixed baffle and the right side axial pressure loading fixed baffle, a left side axial pressure loading oil cylinder and a right side axial pressure loading oil cylinder respectively penetrate through the center mounting holes of the left side axial pressure loading fixed baffle and the right side axial pressure loading fixed baffle and are welded with the center mounting holes to form an integral structure, and in addition, the left side axial pressure loading fixed baffle and the right side axial pressure loading fixed baffle are connected into a whole through connecting rods penetrating through the peripheral mounting holes of the left side axial pressure loading fixed baffle and the right side axial pressure loading fixed baffle and further form an integral frame system with the supporting platform; the left electromagnetic pulse excitation cavity is supported by a left electromagnetic pulse excitation cavity support and is arranged on a support platform, wherein the left end part of the left electromagnetic pulse excitation cavity is in free fit contact with the left axial pressure loading piston and is used for transmitting static axial pressure provided by the left axial pressure loading oil cylinder to the left electromagnetic pulse excitation cavity through the left axial pressure loading piston; the left stress wave loading rod is supported by a stress wave loading rod support and is arranged on a supporting platform, wherein the left end part of the left stress wave loading rod is in free fitting contact with the right end surface of the left electromagnetic pulse excitation cavity, and is used for further transmitting static axial pressure transmitted to the left electromagnetic pulse excitation cavity to the left stress wave loading rod and finally acting on a test sample, and is used for inputting incident stress waves generated by the left electromagnetic pulse excitation cavity to the left stress wave loading rod and transmitting the incident stress waves along the axial direction of the incident stress waves until a dynamic load from left to right is applied to the test sample;
Similarly, the right electromagnetic pulse excitation cavity is supported by the right electromagnetic pulse excitation cavity support and is arranged on the supporting platform, wherein the right end part of the right electromagnetic pulse excitation cavity is in free fit contact with the right axial pressure loading piston and is used for transmitting static axial pressure provided by the right axial pressure loading oil cylinder to the right electromagnetic pulse excitation cavity through the right axial pressure loading piston; the right stress wave loading rod is supported by a stress wave loading rod support and is arranged on a supporting platform, wherein the right end part of the right stress wave loading rod is in free fitting contact with the left end surface of the right electromagnetic pulse excitation cavity, and is used for further transmitting static axial pressure transmitted to the right electromagnetic pulse excitation cavity to the right stress wave loading rod and finally acting on a test sample, and is used for inputting an incident stress wave generated by the right electromagnetic pulse excitation cavity to the right stress wave loading rod and transmitting the incident stress wave to the right stress wave loading rod along the axial direction until a dynamic load from right to left is applied to the test sample;
the left stress wave loading rod and the right stress wave loading rod are provided with resistance strain gages;
the confining pressure loading device is formed by a confining pressure loading cylinder confining baffle, a confining pressure loading cylinder, a connecting screw, a confining pressure loading oil inlet, a confining pressure loading exhaust port sealing plug and a confining pressure oil meter, wherein a center mounting hole and a surrounding mounting hole are respectively formed in the center and the periphery of the confining pressure loading cylinder confining baffle, the center mounting hole is used for enabling a left stress wave loading rod and a right stress wave loading rod to penetrate through the center mounting hole and extend into the inside of the confining pressure loading cylinder to be in contact with a test sample, the screw is used for connecting the confining pressure loading cylinder confining baffle and the confining pressure loading cylinder into an integral structure through the surrounding mounting hole of the confining pressure loading cylinder confining baffle and is arranged on a supporting platform, in addition, a confining pressure loading oil inlet and a confining pressure loading exhaust port are respectively formed in the lower part and the upper part of the center mounting hole of the confining pressure loading cylinder confining baffle, a confining pressure servo control loading system is formed into a communication loop through the confining pressure loading oil inlet and the confining pressure loading exhaust port, and is used for enabling a hydraulic oil pump to be pumped into the confining pressure loading cylinder 18 to apply annular static confining pressure to the test sample wrapped in a rubber sleeve, and the confining pressure loading cylinder is matched with a pressure loading exhaust port for sealing the inside the confining pressure loading cylinder after exhausting the confining pressure loading cylinder.
The osmotic pressure loading device comprises a left osmotic pressure pipeline and a right osmotic pressure pipeline, wherein the apertures and the lengths of the left osmotic pressure pipeline and the right osmotic pressure pipeline are the same, the left osmotic pressure pipeline and the right osmotic pressure pipeline are respectively arranged at the right end part of a left stress wave loading rod and the left end part of the right stress wave loading rod and are in direct contact with the loading end surface of a test sample, when the osmotic pressure is applied, the osmotic liquid with set pressure is injected from the left osmotic pressure pipeline, and is discharged from the right osmotic pressure pipeline through a pore network channel communicated with the inside of the test sample under the driving of the osmotic pressure, and the osmotic pressure is kept constant at the set value.
As a further improvement of the invention, the center mounting holes and the periphery mounting holes of the left axial pressure loading fixed baffle, the right axial pressure loading fixed baffle and the confining pressure loading cylinder confining baffle are all circular holes.
As a further improvement of the invention, the left side axial pressure loading fixed baffle and the right side axial pressure loading fixed baffle are connected into a whole by four connecting rods through four small round holes on the periphery of the fixed baffle and further form a whole frame system with the supporting platform.
As a further improvement of the invention, the diameter of the central mounting hole of the confining pressure loading cylinder confining plate is 1+/-0.1 mm larger than the diameter of the stress wave loading rod.
As a further development of the invention, resistive strain gauges are arranged in the central positions of the left stress wave loading rod and the right stress wave loading rod.
As a further improvement of the invention, the confining pressure oil gauge is arranged at the upper part of the right side confining wall of the confining pressure loading cylinder confining wall.
As a further development of the invention, the left side stress wave loading rod and the right side stress wave loading rod are free to slide on the stress wave loading rod support.
The method for testing the osmotic pressure and static force coupling electromagnetic loading triaxial SHPB by using the device disclosed by any one of the above steps comprises the following specific steps:
firstly, synchronously controlling a left axial pressure loading oil cylinder and a right axial pressure loading oil cylinder through an axial pressure servo control loading system to boost the two and drive a left axial pressure loading piston and a right axial pressure loading piston to respectively move rightwards and leftwards so as to further push a left stress wave loading rod and a right stress wave loading rod to respectively apply axial pressure to a test sample at a set loading rate, stopping loading when an axial pressure value reaches a set value, and keeping the axial pressure constant by utilizing the axial pressure servo control loading system;
pumping anti-wear hydraulic oil into the confining pressure loading cylinder through a confining pressure loading oil inlet at a set speed by using a confining pressure servo control loading system, indicating that the confining pressure loading cylinder is filled with the anti-wear hydraulic oil when hydraulic oil flows out from a confining pressure loading exhaust port, screwing and sealing the confining pressure loading exhaust port by using a confining pressure loading exhaust port sealing plug at the moment, continuously applying confining pressure, stopping loading and keeping the confining pressure constant by using the confining pressure servo control loading system when the pressure reading of a confining pressure oil meter reaches a set confining pressure value, so that the circumferential confining pressure of a test sample is kept constant at a set value by the anti-seepage rubber sleeve; then, applying osmotic pressure to the test sample through the left osmotic pressure pipeline and the right osmotic pressure pipeline by utilizing an osmotic pressure loading system, and completing the coupling action conditions of applying static axial pressure, confining pressure and osmotic pressure to the test sample when the osmotic pressure difference between the left osmotic pressure pipeline () and the right osmotic pressure pipeline is constant to be a set value;
Then according to the test design, an electromagnetic pulse excitation control system is operated to drive a left electromagnetic pulse excitation cavity and a right electromagnetic pulse excitation cavity to synchronously excite and output incident stress waves, and the incident stress waves are respectively transmitted to a test sample along a stress wave loading rod at the left side and the right side and dynamically impact and load the test sample, so that a static pressure and osmotic pressure coupling impact loading triaxial SHPB test is completed;
the dynamic impact loading process is carried out by pasting on the left side and the right sideThe resistance strain gauge at the central position of the loading rod is used for monitoring an incident strain signal and a reflected strain signal in the stress wave loading rod in real time; when the strain signal data monitored by the strain gauge shows that the dynamic compression load applied by the left end face and the right end face of the test sample in the triaxial SHPB test process of the coupling impact loading of static pressure and osmotic pressure is basically consistent, the dynamic impact loading process of the test sample can be considered to reach a stress balance state, the dynamic compression strength sigma (t) of the test sample (26) is obtained by calculating according to the following formula by using the strain data monitored by the strain gauge according to the one-dimensional stress wave propagation theory, and the dynamic compression strain rate is obtainedAnd the strain ε (t) is:
wherein E, C and A are the elastic modulus, longitudinal wave velocity and cross-sectional area of the stress wave loading rod, respectively; a is that s To test the cross-sectional area of the test specimen, A s To test the length of the sample; epsilon Left incidence And epsilon Left reflection Incident strain signal and reflected strain signal respectively monitored by strain gauge from left stress wave loading rod Right incidence of And epsilon Right reflection The incident strain signal and the reflected strain signal monitored by the strain gauge from the right stress wave loading rod are respectively.
As a further improvement of the invention, the resistance strain gauge transmits an incident strain signal and a reflected strain signal in the stress wave loading rod to the signal amplifier through the Wheatstone bridge by the shielding wire, the strain signal is amplified by the signal amplifier and then is output to the data recorder for recording and storage through the shielding wire, and finally, the strain signal data is output to the computer through the data wire for analysis and processing.
The beneficial effects of the invention are as follows:
(1) An electromagnetic pulse emission system of an osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and a testing method can accurately control and highly repeatedly generate incident stress waves, and solves the technical problems that when an incident rod is impacted by a pneumatic bullet emission bullet of the traditional Hopkinson bar device to generate the incident stress waves, the incident stress waves are difficult to accurately control and the incident stress waves are highly repeatedly generated.
(2) The dynamic load of the osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and the testing method is synchronously loaded by the bidirectional electromagnetic pulse transmitting system, so that the defect that a traditional Hopkinson pressure bar can only apply dynamic load to a test sample from one direction is overcome, meanwhile, incident stress waves are synchronously loaded in a bidirectional mode, the time for achieving dynamic stress balance of the test sample loading process is shortened to about one third of that of the traditional test sample loading process from one direction, the effectiveness and the reliability of a dynamic test result are improved, and the phenomenon of pre-fracture of the fragile sample, which affects the effectiveness of the test result due to the fact that the time for achieving balance is too long, can be avoided.
(3) The axial pressure and confining pressure servo control loading system of the osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and the testing method can realize static axial pressure and confining pressure servo control loading and maintain the axial pressure and confining pressure relatively stable in the dynamic impact loading process, and the defect that the axial pressure and confining pressure of the existing improved SHPB triaxial loading device are difficult to maintain relatively stable in the dynamic loading process is overcome.
(4) The osmotic pressure loading system of the osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device and the testing method can be used for testing the osmotic pressure and pore water pressure applied under the action of triaxial static pressure application or providing the pore water pressure for a sample containing internal holes and maintaining the osmotic pressure, the pore water pressure or the pore water pressure at a set value, realizing an impact loading test under the action of osmotic pressure and static pressure coupling, solving the technical problem that the existing rock dynamics characteristic test based on the SHPB system cannot simulate osmotic pressure-static pressure multi-field coupling in the dynamic loading process, enabling the testing process to be closer to the true triaxial stress environment of a deep rock mass, and enabling the testing result to be more reliable and accurate.
Drawings
FIG. 1 is a three-dimensional view of an osmotic pressure and static pressure coupled electromagnetic loading triaxial SHPB device according to the present invention;
FIG. 2 is a front view of an osmotic pressure and static pressure coupled electromagnetic loading triaxial SHPB device according to the present invention;
FIG. 3 is a cross-sectional elevation view of an osmotic pressure and static pressure coupled electromagnetic loading triaxial SHPB device according to the present invention;
FIG. 4 is a three-dimensional view of the osmotic and confining pressure loading device of the invention;
FIG. 5 is a three-dimensional cutaway view of the osmotic and confining pressure loading device of the present invention in elevation;
FIG. 6 is a front elevation view in elevation of a cross-sectional view of a warm osmotic and confining pressure loading device of the present invention;
FIG. 7 is a top view in three-dimensional cutaway of the osmotic and confining pressure loading device of the present invention;
FIG. 8 is a top plan view in cross-section of the osmotic and confining pressure loading device of the present invention;
FIG. 9 is a three-dimensional view of a finite element computational model of the present invention;
FIG. 10 is a three-dimensional plot of the meshing of a complete stress wave loading rod in finite element calculations of the present invention;
FIG. 11 is a three-dimensional view of the meshing of the stress wave loading rod of the osmotic pressure pipe in the finite element calculation of the present invention;
FIG. 12 is a graph of finite element calculations of the effect of different osmotic tube diameters on stress wave propagation in a stress wave loading rod according to the present invention;
FIG. 13 is a three-dimensional cutaway view of the hydrostatic and in-bore coupling triaxial loading front view of a test specimen including a cylindrical bore according to the present invention;
FIG. 14 is a three-dimensional cutaway view of the hydrostatic and in-bore coupling triaxial loading of a test specimen containing a cylindrical bore according to the present invention;
FIG. 15 is a three-dimensional view of a test specimen containing a cylindrical hole in accordance with the present invention;
FIG. 16 is a top view of a test specimen containing cylindrical holes according to the present invention.
The reference numbers correspond to the component designations as follows:
the hydraulic test device comprises a 1-supporting platform, a 2-left axial pressure loading fixed baffle, a 3-left axial pressure loading oil cylinder, a 4-left axial pressure loading piston, a 5-left electromagnetic pulse excitation cavity, a 6-left electromagnetic pulse excitation cavity support, a 7-connecting rod, an 8-left stress wave loading rod, a 9-stress wave loading rod support, a 10-strain gauge, a 11-right axial pressure loading fixed baffle, a 12-right axial pressure loading oil cylinder, a 13-right axial pressure loading piston, a 14-right electromagnetic pulse excitation cavity, a 15-right electromagnetic pulse excitation cavity support, a 16-right stress wave loading rod, a 17-confining pressure loading cylinder confining baffle, a 18-confining pressure loading cylinder, a 19-screw rod, a 20-confining pressure loading oil inlet, a 21-confining pressure loading exhaust port, a 22-confining pressure loading exhaust port sealing plug, a 23-confining pressure oil meter, a 24-left osmotic pressure pipeline, a 25-right osmotic pressure pipeline, a 26-test sample, a 27-rubber sleeve and a 28-cylindrical hole.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Best mode 1:
fig. 1 is a three-dimensional diagram of an osmotic pressure and static pressure coupling electromagnetic loading triaxial SHPB device, wherein a test device is arranged on a supporting platform 1 and mainly comprises an electromagnetic pulse transmitting system, a shaft pressure servo control loading system, a confining pressure servo control loading system, an osmotic pressure loading system, a rod system and a data monitoring and collecting system. The test system is arranged in a side-to-side symmetrical fashion centered on the test specimen 26 (as shown in fig. 3). The left side and right side axial pressure loading fixed baffles 2 and 11 are respectively fixed at the left end and the right end of the supporting platform 1, the center and the periphery of the fixed baffles are respectively provided with a large round hole and a small round hole, the size of the fixed baffles is obtained based on the size comparison of the round holes at the center and the periphery, namely, the diameter of the center round hole is larger than that of the round holes at the periphery, so that the fixed baffles are clear. The left side axial pressure loading cylinder 3 and the right side axial pressure loading cylinder 12 respectively pass through the central big round holes of the left and right end axial pressure loading fixed baffles 2 and 11 and are welded with the central big round holes to form an integral structure, in addition, the left and right end axial pressure loading fixed baffles 2 and 11 are connected into a whole through four connecting rods 7 passing through four small round holes on the periphery of the connecting rods to form an integral frame system together with a supporting platform; the number of the connecting rods 7 is set according to actual needs, and four connecting rods are only one implementation example and not representative of the four connecting rods; the left electromagnetic pulse excitation cavity 5 is supported by the left electromagnetic pulse excitation cavity support 6 and is arranged on the support platform 1, wherein the left end part of the left electromagnetic pulse excitation cavity 5 is in free fit contact with the left axial pressure loading piston 4 and is used for transmitting static axial pressure provided by the left axial pressure loading oil cylinder 3 to the left electromagnetic pulse excitation cavity 5 through the left axial pressure loading piston 4; the left stress wave loading rod 8 is supported by the stress wave loading rod support 9 and is arranged on the supporting platform 1, wherein the left end part of the left stress wave loading rod 8 is in free fitting contact with the right end surface of the left electromagnetic pulse excitation cavity 5, and the left stress wave loading rod is used for further transmitting static axial pressure transmitted to the left electromagnetic pulse excitation cavity 5 to the left stress wave loading rod 8 and finally acting on the test sample 26, and is used for inputting an incident stress wave generated by the left electromagnetic pulse excitation cavity 5 to the left stress wave loading rod 8 and transmitting the incident stress wave along the axial direction of the incident stress wave loading rod until a dynamic load from left to right is applied to the test sample 26; similarly, the right electromagnetic pulse excitation cavity 14 is supported by the right electromagnetic pulse excitation cavity support 15 and is arranged on the support platform 1, wherein the right end part of the right electromagnetic pulse excitation cavity 14 is in free fit contact with the right axial pressure loading piston 13, and is used for transmitting static axial pressure provided by the right axial pressure loading oil cylinder 12 to the right electromagnetic pulse excitation cavity 14 through the right axial pressure loading piston 13; the right side stress wave loading rod 16 is supported by the stress wave loading rod support 9 and is arranged on the support platform 1, wherein the right end part of the right side stress wave loading rod 16 is in free abutting contact with the left end surface of the right side electromagnetic pulse excitation cavity 14, on the one hand, the static axial pressure transmitted to the right side electromagnetic pulse excitation cavity 14 is further transmitted to the right side stress wave loading rod 16 and finally acts on the test sample 26, and on the other hand, the incident stress wave generated by the right side electromagnetic pulse excitation cavity 14 is input to the right side stress wave loading rod 16 and propagates along the axial direction thereof until the dynamic load from right to left is applied to the test sample 26.
Fig. 4-8 are schematic diagrams of the structure and connection of an osmotic pressure and static pressure coupled electromagnetic loading triaxial SHPB device. The confining pressure loading device mainly comprises a confining pressure loading cylinder confining baffle 17, a confining pressure loading cylinder 18, a connecting screw 19, a confining pressure loading oil inlet 20, a confining pressure loading exhaust port 21, a confining pressure loading exhaust port sealing plug 22 and a confining pressure oil gauge 23, wherein a large round hole and a small round hole are respectively formed in the center and the periphery of the confining pressure loading cylinder confining baffle 17, the size of the confining pressure loading cylinder confining baffle is obtained based on the size comparison of the round holes in the center and the periphery, namely the diameter of the center round hole is larger than that of the round holes in the periphery, and therefore the confining pressure loading device is clear. The diameter of the large round hole is about 1mm larger than that of the stress wave loading rod, the stress wave loading rods 8 and 16 on the left side are respectively penetrated through the large round hole on the center and extend into the interior of the confining pressure loading cylinder 18 to be in contact with the test sample 26, the screw 19 connects the confining pressure loading cylinder confining plate 17 and the confining pressure loading cylinder 18 into a whole structure through the small round hole on the periphery of the confining pressure loading cylinder confining plate, and is arranged on the supporting platform 1; the osmotic pressure loading device mainly comprises a left osmotic pressure pipeline 24 and a right osmotic pressure pipeline 25, wherein the apertures and the lengths of the left osmotic pressure pipeline 24 and the right osmotic pressure pipeline 25 are the same, the left osmotic pressure pipeline 24 and the right osmotic pressure pipeline 25 are respectively arranged at the right end part and the left end part of the left stress wave loading rods 8 and 16 and are in direct contact with the loading end surface of the test sample, when the osmotic pressure is applied, the osmotic liquid with set pressure (0-60 MPa) is injected from the left osmotic pressure pipeline 24, the osmotic liquid is discharged from the right osmotic pressure pipeline 25 through a pore network channel communicated with the inside of the test sample 26 under the driving of the osmotic pressure, and the osmotic pressure is kept constant at the set value.
In the dynamic loading process, an electromagnetic pulse excitation control system is operated to drive a left electromagnetic pulse excitation cavity 5 and a right electromagnetic pulse excitation cavity 14 to synchronously excite and output incident stress waves with the same amplitude and duration to propagate to a test sample 26 along a left stress wave loading rod 8 and a right stress wave loading rod 16 respectively, and dynamic impact loading is carried out on the test sample, so that osmotic pressure and static pressure coupling impact loading triaxial SHPB test is completed; the dynamic impact loading process is characterized in that axial and circumferential static pressure is kept basically unchanged under the regulation and control of an axial pressure servo control loading system and a confining pressure servo control loading system respectively, so that a dynamic triaxial impact loading test under the conditions of constant static axial pressure and confining pressure is realized; the dynamic impact loading process can monitor the incident strain signal and the reflected strain signal in the stress wave loading rod in real time through the resistor strain sheets 10 stuck at the central positions of the loading rods at the left side and the right side, the incident strain signal and the reflected strain signal are transmitted to the signal amplifier through the Wheatstone bridge, the strain signal is amplified through the signal amplifier and then is output to the data recorder through the shielding wire for recording and storage, and finally, the strain signal data is output to the computer through the data wire for analysis and processing through the data recorder. When the strain signal data monitored by the strain gauge 10 shows that the dynamic compression load applied by the left end face and the right end face of the test sample 26 is basically consistent in the osmotic pressure-static pressure coupling impact loading triaxial SHPB test process, the dynamic impact loading process of the test sample 26 can be considered to reach a stress balance state, and according to the one-dimensional stress wave propagation theory, the strain data monitored by the strain gauge 10 can be calculated according to the following formula to obtain the dynamic compression strength sigma (t) of the test sample in the osmotic pressure-static pressure coupling impact loading triaxial SHPB test, and the dynamic compression strain rate And dynamic strain ε (t) are:
wherein E, C and A are the elastic modulus, longitudinal wave velocity and cross-sectional area of the stress wave loading rod, respectively; a is that s To test the cross-sectional area of sample 26, A s For testing the length of the specimen 26; epsilon Left incidence And epsilon Left reflection Incident and reflected strain signals, ε, respectively, monitored by strain gauges from left stress wave loading rod 8 Right incidence of And epsilon Right reflection The incident and reflected strain signals, respectively, are monitored by the strain gauge from the right side stress wave loading rod 16.
Furthermore, it should be noted that, due to the introduction of the osmotic pressure system, the left side osmotic pressure pipe 24 and the right side osmotic pressure pipe 25 are required to be respectively arranged at the left side and the right side stress wave loading rods 8 and 16 near the loading end of the test sample, and due to the introduction of the osmotic pressure transmission channel, the isotropy characteristic of the cylindrical stress wave loading rod is changed to a certain extent, and the local anisotropy characteristic is generated, so that the influence of the introduction of the osmotic pressure transmission channel on the one-dimensional stress wave propagation on the stress wave loading rods needs to be checked. Calculation by finite element modeling (exemplified by ABAQUS 6.14-5 software) shows that: when the diameter of the osmotic pressure pipe is less than or equal to 2mm, the influence of the introduction of the osmotic pressure transmission channel on the one-dimensional stress wave propagation on the stress wave loading rod is less than 1%, which can be ignored, and is particularly mainly shown in fig. 9, when the incident stress wave (half sine wave with the amplitude and the wavelength duration of 200MPa and 250 mus respectively) is transmitted from left to right along the stress wave loading rod from the left end of the stress wave loading rod, the difference between the amplitude of the stress wave monitored at the center point of the cross section of the monitored point A and the amplitude of the stress wave monitored at the same position of the stress wave loading rod of the complete osmotic pressure pipe is less than 1% (shown in fig. 12).
It should be noted that, the modeling and boundary condition information related to the numerical model calculation as shown in fig. 9 is as follows:
by contrast, a complete stress wave transmission rod model without an osmotic pressure pipeline is firstly established, wherein the stress wave loading rod is 3.05m in length and 50mm in diameter, the material is a homogeneous elastic titanium alloy, the density, the elastic modulus, the poisson ratio and the longitudinal wave speed of the stress wave loading rod are 4510kg/m3, 107.8GPa, 0.33 and 5000m/s respectively, the stress wave transmission rod model is subjected to grid division by adopting a tetrahedral grid free division method (the local grid division result is shown as a graph 10), and the total cell number obtained by the divided model is 72832;
subsequently, numerical calculation models of osmotic pressure pipelines with different diameters (2 mm, 1mm and 0.5mm respectively) are respectively built on the basis of the complete stress wave transmission rod model, wherein the lengths of the osmotic pressure transmission pipelines along the axial direction of the stress wave loading rod are 0.15m, the lengths and the diameters of the stress wave loading rod are 3.05m and 50mm respectively, the materials and the parameters of the stress wave loading rod are the same as those of the complete stress wave transmission rod model, and the obtained mesh unit numbers of the stress wave transmission rod models of the osmotic pressure pipelines with different diameters of 2mm, 1mm and 0.5mm are 290850, 260999 and 299936 respectively according to the same mesh division mode as the complete stress wave loading rod (the mesh division result of the part of the osmotic pressure pipelines is shown in fig. 11).
Best mode 2 for carrying out dynamic impact test research on complete water-saturated coal rock under osmotic pressure and static pressure coupling triaxial loading
The relevant equipment of the test system is arranged on a supporting platform 1 with the length, the width and the height of 6m,0.6m and 1m respectively according to the connection mode shown in figures 1-3, and the connection relation and the relevant functions of the equipment are specifically described as follows: the testing system is arranged on a supporting platform 1 in a bilateral symmetry mode by taking a testing coal rock (namely a testing sample 26) as a center, a left axial pressure loading fixed baffle plate 2 with the width, the height and the thickness of 600mm,400mm and 50mm respectively is firstly arranged at the left end of the supporting platform 1, wherein a left axial pressure loading oil cylinder 3 with the diameter and the length of 250mm and 200mm respectively passes through the center of the left axial pressure loading fixed baffle plate 2The large round hole is welded with the large round hole to form an integral structure, the diameter of the left axial pressure loading piston 4 is 100mm, the stroke length of the piston is 200mm, and the movement of the left axial pressure loading piston is controlled through the pressurization and depressurization of the left axial pressure loading cylinder 3; then, a left electromagnetic pulse excitation cavity 5 with the diameter and the length of 200mm and 200mm is supported and arranged on the supporting platform 1 by a left electromagnetic pulse excitation cavity support 6, wherein the left end part of the left electromagnetic pulse excitation cavity 5 is in free fit contact with a left axial pressure loading piston 4 and is used for transmitting static axial pressure provided by the left axial pressure loading oil cylinder 3 to the left electromagnetic pulse excitation cavity 5 through the left axial pressure loading piston 4, and the diameter of a stress wave output end face of the right end of the left electromagnetic pulse excitation cavity 5 is the same as the diameter of a stress wave loading rod (50 mm); the left side stress wave loading rod 8 of TC21 titanium alloy with the length of 2m and the diameter of 50mm is flatly placed on the stress wave loading rod support 9, the left side stress wave loading rod 8 can slide freely on the support, then the right side loading end face of the left side stress wave loading rod 8 is aligned with and fully attached to the left side loading face of fully saturated coal rock (namely test sample 26) with the length and the diameter of 50mm and the porosity of about 20 percent, meanwhile the left side stress wave loading end face of the left side stress wave loading rod 8 is aligned with and fully attached to the right side stress wave output end face of the left side electromagnetic pulse excitation cavity 5, and the function is mainly to further transmit static axial compression transmitted to the left side electromagnetic pulse excitation cavity 5 to the left side stress wave loading rod 8 and finally act on the coal rock (namely test sample 26), and on the other hand, to input incident stress waves generated by the left side electromagnetic pulse excitation cavity 5 to the left side stress wave loading rod 8 and propagate along the axial direction until dynamic load from left to right is applied to the coal rock; similarly, the right side system is arranged in the same way as the left side, a right side axial pressure loading fixed baffle plate 11 with the width, the height and the thickness of 600mm,400mm and 50mm respectively is firstly arranged at the right end of the supporting platform 1, wherein a right side axial pressure loading oil cylinder 12 with the diameter and the length of 250mm and 200mm respectively passes through a central large round hole of the right side axial pressure loading fixed baffle plate 11 and is welded with the right side axial pressure loading fixed baffle plate to form an integral structure, the diameter of the right side axial pressure loading piston 13 is 100mm, the stroke length of the piston is 200mm, and the piston is increased by the right side axial pressure loading oil cylinder 12 The pressure and the pressure reduction control the movement of the right shaft pressure loading piston; then, a right electromagnetic pulse excitation cavity 14 with the diameter and the length of 200mm is supported and arranged on the supporting platform 1 by utilizing a right electromagnetic pulse excitation cavity support 15, wherein the right end part of the right electromagnetic pulse excitation cavity 14 is in free fit contact with a right axial pressure loading piston 13 and is used for transmitting static axial pressure provided by a right axial pressure loading oil cylinder 12 to the right electromagnetic pulse excitation cavity 14 through the right axial pressure loading piston 13, and the diameter of the left end stress wave output end surface of the right electromagnetic pulse excitation cavity 14 is the same as the diameter of a stress wave loading rod (50 mm); the right side stress wave loading rod 16 of TC21 titanium alloy with the length of 2m and the diameter of 50mm is flatly placed on the stress wave loading rod support 9, the right side stress wave loading rod 16 can slide freely on the support, then the left side loading end face of the right side stress wave loading rod 16 is aligned and fully fitted with the right side loading face of coal rock (namely test sample 26) with the length and the diameter of 50mm and the porosity of about 20 percent, and meanwhile the right side stress wave loading end face of the right side stress wave loading rod 16 is aligned and fully fitted with the left side stress wave output end face of the right side electromagnetic pulse excitation cavity 14, and the function is mainly used for further transmitting static axial pressure transmitted to the right side electromagnetic pulse excitation cavity 14 to the right side stress wave loading rod 16 and finally acting on a sandstone sample 26, and on the other hand, inputting incident waves generated by the right side electromagnetic pulse excitation cavity 14 to the right side stress wave loading rod 16 and propagating along the axial direction until dynamic load from right to left is applied to coal; then 4 connecting rods 7 are utilized to pass through four small round holes on the periphery of the left side and the right side axial pressure loading fixed baffles 2 and 11 so as to connect the loading system into a whole and further form an integral frame system with the supporting platform; the confining pressure loading device is arranged on the periphery of the coal rock, and the specific installation steps are as follows: the full water coal rock is firstly taken down, then the left side axial pressure loading piston and the right side axial pressure loading piston are respectively pushed open to the left and the right ends under the non-axial pressure loading state, so that the left side stress wave loading rod 8 and the right side stress wave loading rod 16 can be respectively moved to the left side and the right side, space is further saved for installing the confining pressure loading device, and then the left side surrounding block and the right side surrounding block of the confining pressure loading cylinder surrounding block 17 are respectively sleeved on the left side stress wave loading rod 8 and the right side stress wave loading rod 8 as shown in fig. 4-8 And 16, then sleeving the surrounding pressure loading cylinder 18 on the left or right stress wave loading rod, then contacting the water-saturated coal rock wrapped in the anti-seepage rubber sleeve (such as 26-type fluororubber) 27 with the left and right stress wave loading rods 8 and 16, adjusting the coal rock to the symmetrical center position of the system, then synchronously controlling the left and right side axial pressure loading cylinders 3 and 12 to slowly pressurize and drive the left and right side axial pressure loading pistons 4 and 13 to respectively move rightward and leftward by an axial pressure servo control loading system, further driving the left and right side stress wave loading rods 8 and 16 to respectively slowly move rightward and leftward to clamp the water-saturated coal rock and apply axial pressure to the water-saturated coal rock, stopping loading and keeping the axial pressure constant when the axial pressure value reaches about 100KPa, thereby ensuring that the water-saturated coal rock and the whole axial loading system are in an axially fixed state, then butting the left and right side barriers of the surrounding pressure loading cylinder 17 with the surrounding pressure loading cylinder 18 and putting the surrounding pressure loading cylinder 18 in the symmetrical center position of the system so that the water-saturated coal rock loading cylinder 18 is located at the central position of the system, and then screwing the surrounding pressure loading cylinder 18 into the whole by using the screw rod structure 19; the whole system connection and sample installation steps are completed, and then corresponding loading operation can be carried out according to the test design, wherein the specific loading process is as follows: firstly, synchronously controlling a left side axial pressure loading cylinder 3 and a right side axial pressure loading cylinder 12 through an axial pressure servo control loading system to boost the pressure again and drive a left side axial pressure loading piston 4 and a right side axial pressure loading piston 13 to move rightwards and leftwards respectively, further pushing a left side stress wave loading rod 8 and a right side stress wave loading rod 16 to apply axial pressure to water-saturated coal rock respectively at a set loading rate, stopping loading when the axial pressure value reaches 5MPa, and keeping the axial pressure constant by utilizing the axial pressure servo control loading system; then, by using the confining pressure servo control loading system, the antiwear hydraulic oil (such as HEX T6002) is pumped into the confining pressure loading cylinder 18 through the confining pressure loading oil inlet 20 at a set speed, the confining pressure loading cylinder is filled with the antiwear hydraulic oil when the hydraulic oil flows out from the confining pressure loading exhaust port 21, at the moment, the confining pressure loading exhaust port 21 is screwed and sealed by using the confining pressure loading exhaust port sealing plug 22, and the confining pressure oil meter 23 to be installed on the upper part of the right side wall of the confining pressure loading cylinder enclosure 17 is arranged When the pressure reading reaches the set confining pressure value of 5MPa, stopping loading and keeping the confining pressure constant by using a confining pressure servo control loading system, so that the circumferential confining pressure acting on the water-saturated coal rock through the anti-seepage rubber sleeve (for example, 26-type fluororubber) 27 is kept constant at 5MPa; applying osmotic pressure of 5MPa to the saturated coal rock from one side of the left stress wave loading rod by using an osmotic pressure loading system through a left osmotic pressure pipeline 24, discharging the osmotic liquid from a right osmotic pressure pipeline 25 through a pore network channel communicated with the inside of the saturated coal rock under the driving of the osmotic pressure, and considering that the coupling action conditions of applying static axial pressure, confining pressure and osmotic pressure to the saturated coal rock are finished when the osmotic pressure difference between two ends of the left osmotic pressure pipeline 24 and the right osmotic pressure pipeline 25 is kept constant by 5MPa; then according to the test design, an electromagnetic pulse excitation control system is operated to drive a left electromagnetic pulse excitation cavity 5 and a right electromagnetic pulse excitation cavity 14 to synchronously excite and output incident stress waves with the amplitude of 300MPa and the duration of 300 mu s, and the incident stress waves are respectively transmitted to the water-saturated coal rock along a stress wave loading rod on the left side and the right side and dynamically impact and load the water-saturated coal rock, so that a dynamic impact test under osmotic pressure and static pressure coupling triaxial loading is completed; the dynamic impact loading process is characterized in that the axial and circumferential static pressures are kept basically unchanged under the regulation and control of the axial pressure servo control loading system and the confining pressure servo control loading system respectively, so that a dynamic triaxial impact loading test under the conditions of constant static axial pressure and confining pressure is realized; the dynamic impact loading process monitors an incident strain signal and a reflected strain signal in the stress wave loading rod in real time through the resistor strain sheets 10 stuck at the central positions of the loading rods at the left side and the right side, transmits the incident strain signal and the reflected strain signal to the signal amplifier through the Wheatstone bridge, amplifies the strain signal through the signal amplifier, outputs the amplified strain signal to the data recorder through the shielding wire for recording and storage, and finally outputs strain signal data to the computer through the data recorder for analysis and processing. When the strain signal data monitored by the strain gauge 10 shows that the dynamic compression load applied to the left end face and the right end face of the saturated water coal rock is basically consistent in the triaxial SHPB test process of osmotic pressure and static pressure coupled impact loading, the dynamic impact loading process of the saturated water coal rock can be considered to be achieved The stress balance state can be calculated according to the following formula by utilizing the strain data monitored by the strain gauge 10 according to the one-dimensional stress wave propagation theory to obtain the dynamic compression strength sigma (t) of the saturated water coal rock material under the coupling action of static pressure 5MPa and osmotic pressure 5MPa, and the dynamic compression strain rateAnd the strain ε (t) is:
wherein E, C and A are respectively the elastic modulus (107.8 GPa), longitudinal wave velocity (5000 m/s) and the cross-sectional area (1963.5 mm) of the stress wave loading rod 2 )；A s Is the cross-sectional area of water-saturated coal rock (1932.2 mm 2 The actual diameter of the water-saturated coal rock is 49.6 mm), A s Is the length (50 mm) of the water-saturated coal rock; epsilon Left incidence And epsilon Left reflection Incident and reflected strain signals, ε, respectively, monitored by strain gauges from left stress wave loading rod 8 Right incidence of And epsilon Right reflection The incident and reflected strain signals, respectively, are monitored by the strain gauge from the right side stress wave loading rod 16.
Best mode for carrying out the invention dynamic impact test study of the center-containing column Kong Yeyan under static pressure and in-bore pressure coupled triaxial loading
The relevant equipment of the test system is arranged on a supporting platform 1 with the length, the width and the height of 6m,0.6m and 1m respectively according to the connection mode shown in figures 1-3, and the connection relation and the relevant functions of the equipment are specifically described as follows: to test shale (i.e. test specimen 26) (with a central diameter of 8mm cylindrical hole 28 as shown in fig. 12-15), arranging the test system on the support platform 1 in a bilateral symmetry manner, firstly arranging left side axial pressure loading fixed baffles 2 with width, height and thickness of 600mm,400mm and 50mm at the left end of the support platform 1, wherein a left side axial pressure loading cylinder 3 with diameter and length of 250mm and 200mm respectively passes through the central large round hole of the left side axial pressure loading fixed baffle 2 and is welded with the left side axial pressure loading fixed baffle to form an integral structure, the diameter of the left side axial pressure loading piston 4 is 100mm, the stroke length of the piston is 200mm, and controlling the movement of the left side axial pressure loading piston through the pressurization and depressurization of the left side axial pressure loading cylinder 3; then, a left electromagnetic pulse excitation cavity 5 with the diameter and the length of 200mm and 200mm is supported and arranged on the supporting platform 1 by a left electromagnetic pulse excitation cavity support 6, wherein the left end part of the left electromagnetic pulse excitation cavity 5 is in free fit contact with a left axial pressure loading piston 4 and is used for transmitting static axial pressure provided by the left axial pressure loading oil cylinder 3 to the left electromagnetic pulse excitation cavity 5 through the left axial pressure loading piston 4, and the diameter of a stress wave output end face of the right end of the left electromagnetic pulse excitation cavity 5 is the same as the diameter of a stress wave loading rod (50 mm); next, the TC21 titanium alloy left side stress wave loading rod 8 with the length of 2m and the diameter of 50mm is horizontally placed on the stress wave loading rod support 9, and the left side stress wave loading rod 8 can slide freely on the stress wave loading rod support 9, then the right side loading end face of the left side stress wave loading rod 8 is aligned with and fully attached to the left side loading face of shale (namely, a test sample 26) with the length and the diameter of 50mm and the cylindrical hole 28 with the center diameter of 8mm, and meanwhile, the left side stress wave loading end face of the left side stress wave loading rod 8 is aligned with and fully attached to the right side stress wave output end face of the left side electromagnetic pulse excitation cavity 5, and the function is mainly used for further transmitting static axial compression transmitted to the left side electromagnetic pulse excitation cavity 5 to the left side stress wave loading rod 8 and finally acting on shale with the cylindrical hole 28 with the center diameter of 8mm, and on the other hand, for inputting incident stress waves generated by the left side electromagnetic pulse excitation cavity 5 to the left side stress wave loading rod 8 and transmitting dynamic load applied from the left side to the right side of the cylindrical hole 28 with the center diameter of 8mm along the axial direction until dynamic load applied to the left side of the cylindrical hole 28 with the center diameter of 8mm is applied together; similarly, the right side system is installed The arrangement mode is the same as that of the left side, a right-side axial pressure loading fixed baffle 11 with the width, the height and the thickness of 600mm,400mm and 50mm is firstly arranged at the right end of a supporting platform 1, wherein a right-side axial pressure loading oil cylinder 12 with the diameter and the length of 250mm and 200mm respectively penetrates through a central large round hole of the right-side axial pressure loading fixed baffle 11 and is welded with the right-side axial pressure loading fixed baffle to form an integral structure, the diameter of a right-side axial pressure loading piston 13 is 100mm, the stroke length of the piston is 200mm, and the movement of the right-side axial pressure loading piston is controlled through the pressurization and the depressurization of the right-side axial pressure loading oil cylinder 12; then, a right electromagnetic pulse excitation cavity 14 with the diameter and the length of 200mm is supported and arranged on the supporting platform 1 by utilizing a right electromagnetic pulse excitation cavity support 15, wherein the right end part of the right electromagnetic pulse excitation cavity 14 is in free fit contact with a right axial pressure loading piston 13 and is used for transmitting static axial pressure provided by a right axial pressure loading oil cylinder 12 to the right electromagnetic pulse excitation cavity 14 through the right axial pressure loading piston 13, and the diameter of the left end stress wave output end surface of the right electromagnetic pulse excitation cavity 14 is the same as the diameter of a stress wave loading rod (50 mm); next, a TC21 titanium alloy right side stress wave loading rod 16 with the length of 2m and the diameter of 50mm is flatly placed on a stress wave loading rod support 9, and the right side stress wave loading rod 16 is ensured to slide freely on the stress wave loading rod support 9, then a left side loading end face of the right side stress wave loading rod 16 is aligned with and fully abutted with a right side loading face of shale with a cylindrical hole 28 with the center diameter of 8mm and with the length and the diameter of 50mm, and meanwhile, the right side stress wave loading end face of the right side stress wave loading rod 16 is aligned with and fully abutted with a left side stress wave output end face of a right side electromagnetic pulse excitation cavity 14, and the function is mainly used for further transmitting static axial compression transmitted to the right side electromagnetic pulse excitation cavity 14 to the right side stress wave loading rod 16 and finally acting on shale with the cylindrical hole 28 with the center diameter of 8mm, and on the other hand, for inputting incident stress waves generated by the right side electromagnetic pulse excitation cavity 14 to the right side stress wave loading rod 16 and transmitting dynamic loads applied to the shale with the left side of the cylindrical hole 28 with the center diameter of 8mm along the axis direction until the shale is applied from the right side to the left side of the cylindrical hole 28 with the center diameter is fully abutted together; the loading system is then connected by means of 4 connecting rods 7 through four small circular holes in the periphery of the left and right axial pressure loading retainer plates 2 and 11 Is connected into a whole and forms an integral frame system with the supporting platform; the confining pressure loading device is then positioned around the shale sample containing the central cylindrical bore 28, with the following specific installation steps: shale containing cylindrical bore 28 with a central diameter of 8mm is removed, then left and right axial loading pistons are pushed open to left and right ends, respectively, in a shaftless loading state, so that left and right stress wave loading rods 8 and 16 can be moved to left and right sides, respectively, thereby freeing up space for installation of a confining pressure loading device, then left and right side confining shields of confining pressure loading cylinder confining shields 17 as shown in fig. 4-8 are respectively sleeved on both sides of loading ends of left and right stress wave loading rods 8 and 16, then confining pressure loading cylinder 18 is sleeved on the left or right stress wave loading rods, shale containing cylindrical bore 28 with a central diameter of 8mm wrapped in permeation-proof rubber sleeve (e.g. 26-type fluororubber) 27 is then contacted with left and right stress wave loading rods 8 and 16, and shale sample is adjusted to a system symmetrical central position, the left and right axial pressure loading pistons 4 and 13 are then driven to move rightward and leftward by the axial pressure servo control loading system to synchronously control the left and right axial pressure loading cylinders 3 and 12 to slowly pressurize, and further the left and right stress wave loading rods 8 and 16 are driven to slowly move rightward and leftward, respectively, to clamp and apply axial pressure to shale containing the cylindrical hole 28 with the center diameter of 8mm, when the axial pressure value reaches about 100KPa, loading is stopped and the axial pressure is kept constant, thereby ensuring that the shale containing the cylindrical hole 28 with the center diameter of 8mm and the whole axial loading system are in an axially fixed state, next, the left and right side fences of the confining pressure loading cylinder fence 17 are butted with the confining pressure loading cylinder 18 and the confining pressure loading cylinder 18 is in a system symmetrical center position, so that the shale containing the cylindrical hole 28 with the center diameter of 8mm is located in the center position of the confining pressure loading cylinder 18, the confining pressure loading cylinder enclosure 17 and the confining pressure loading cylinder 18 are connected by a connecting screw 19 and screwed into an integral structure; the whole system connection and sample installation steps are completed, and then corresponding loading operation can be carried out according to the test design, wherein the specific loading process is as follows: firstly, the left side and right side axial pressure loading cylinders 3 and 12 are synchronously controlled by an axial pressure servo control loading system to be boosted again and driven The left and right axial pressure loading pistons 4 and 13 respectively move rightward and leftward, so that the left and right stress wave loading rods 8 and 16 are pushed to apply axial pressure to shale containing a cylindrical hole 28 with the center diameter of 8mm at a set loading rate, and when the axial pressure value reaches 30MPa, loading is stopped and the axial pressure is kept constant by utilizing an axial pressure servo control loading system; then pumping antiwear hydraulic oil (such as HEX T6002) into the confining pressure loading cylinder 18 through the confining pressure loading oil inlet 20 at a set rate by using the confining pressure servo control loading system, indicating that the confining pressure loading cylinder is filled with the antiwear hydraulic oil when hydraulic oil flows out from the confining pressure loading exhaust port 21, screwing and sealing the confining pressure loading exhaust port 21 by using the confining pressure loading exhaust port sealing plug 22, stopping loading and keeping the confining pressure constant by using the confining pressure servo control loading system when the pressure reading of the confining pressure oil gauge 23 arranged at the upper part of the right side confining wall of the confining pressure loading cylinder confining 17 reaches a set confining pressure value of 30MPa, so that the confining pressure of shale acting on the cylindrical hole 28 with the center diameter of 8mm through the anti-seepage rubber sleeve (such as 26-type fluororubber) 27 is kept constant at 30MPa; then, applying internal pressure of 10MPa to shale containing a cylindrical hole 28 with the center diameter of 8mm through a left osmotic pressure pipeline 24 and a right osmotic pressure pipeline 25 by utilizing an osmotic pressure loading system, and completing the coupling action conditions of applying static axial pressure, confining pressure and in-hole pressure to shale containing the cylindrical hole 28 with the center diameter of 8mm when the internal pressure of the cylindrical hole 28 is constant at 10 MPa; then according to the test design, an electromagnetic pulse excitation control system is operated to drive a left electromagnetic pulse excitation cavity 5 and a right electromagnetic pulse excitation cavity 14 to synchronously excite and output incident stress waves with the amplitude of 500MPa and the duration of 400 mu s, and the incident stress waves are respectively transmitted to shale containing a cylindrical hole 28 with the center diameter of 8mm along a stress wave loading rod on the left side and a stress wave loading rod on the right side and dynamically impact and load the shale to finish a triaxial SHPB test of static pressure and in-hole pressure coupling impact loading; the dynamic impact loading process is characterized in that the axial and circumferential static pressures are kept basically unchanged under the regulation and control of the axial pressure servo control loading system and the confining pressure servo control loading system respectively, so that a dynamic triaxial impact loading test under the conditions of constant static axial pressure and confining pressure is realized; dynamic impact loading process The incident strain signal and the reflected strain signal in the stress wave loading rod can be monitored in real time through the resistance strain gauge 10 stuck at the central positions of the loading rods at the left side and the right side, the incident strain signal and the reflected strain signal are transmitted to the signal amplifier through the Wheatstone bridge through the shielding wire, the strain signal is amplified through the signal amplifier and then is output to the data recorder through the shielding wire for recording and storage, and finally, the strain signal data is output to the computer through the data wire for analysis and processing through the data recorder. When the strain signal data monitored by the strain gauge 10 shows that the dynamic compression load applied by the left end face and the right end face of the shale containing the cylindrical hole 28 with the center diameter of 8mm is basically consistent in the triaxial SHPB test process of static pressure and in-hole pressure coupling impact loading, the shale containing the cylindrical hole 28 with the center diameter of 8mm can be considered to reach a stress balance state in the dynamic impact loading process, according to the one-dimensional stress wave propagation theory, the strain data monitored by the strain gauge 10 can be used for calculation according to the following formula, and the dynamic compression strength sigma (t) of the shale containing the cylindrical hole 28 with the center diameter of 8mm under the coupling effect of the static pressure of 30MPa and the in-hole pressure of 10MPa in the center cylindrical hole can be obtained, and the dynamic compression strain rate is calculated And the strain ε (t) is:
wherein E, C and A are respectively the elastic modulus of the stress wave loading rod of 107.8 GPa), the longitudinal wave velocity (5000 m/s) and the cross-sectional area of the rod (1963.5 mm) 2 )；A s Cross-sectional area of shale (1881.94 mm) as cylindrical bore 28 with a central diameter of 8mm 2 50mm diameter), A) s A length of shale (50 mm) having a cylindrical bore 28 with a central diameter of 8 mm; epsilon Left incidence And epsilon Left reflection Incident and reflected strain signals, ε, respectively, monitored by strain gauges from left stress wave loading rod 8 Right incidence of And epsilon Right reflection The incident and reflected strain signals, respectively, are monitored by the strain gauge from the right side stress wave loading rod 16.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (9)
1. An osmotic pressure and static force coupling electromagnetic loading triaxial shPB device, which is characterized in that:
the device comprises a supporting platform (1), a left axial pressure loading fixed baffle (2), a left axial pressure loading oil cylinder (3), a left axial pressure loading piston (4), a left electromagnetic pulse excitation cavity (5), a left electromagnetic pulse excitation cavity support (6), a connecting rod (7), a left stress wave loading rod (8), a stress wave loading rod support (9), a resistance strain gauge (10), a right axial pressure loading fixed baffle (11), a right axial pressure loading oil cylinder (12), a right axial pressure loading piston (13), a right electromagnetic pulse excitation cavity (14), a right electromagnetic pulse excitation cavity support (15), a right stress wave loading rod (16), a confining pressure loading cylinder enclosure (17), a confining pressure loading cylinder (18), a connecting screw (19), a confining pressure loading oil inlet (20), a confining pressure loading exhaust port (21), a connecting plug (22), a confining pressure oil table (23), a left osmotic pressure pipeline (24), a right osmotic pressure pipeline (25), a test sample (26) and a rubber sleeve (27);
The device takes a test sample (26) as the center and is arranged in a bilateral symmetry mode, wherein a left side axial pressure loading fixed baffle plate (2) and a right side axial pressure loading fixed baffle plate (11) are respectively fixed at the left end and the right end of a supporting platform (1), center mounting holes and peripheral mounting holes are respectively formed in the centers and the peripheries of the left side axial pressure loading fixed baffle plate (2) and the right side axial pressure loading fixed baffle plate (11), a left side axial pressure loading oil cylinder (3) and a right side axial pressure loading oil cylinder (12) respectively penetrate through the center mounting holes of the left side axial pressure loading fixed baffle plate (2) and the right side axial pressure loading fixed baffle plate (11) and are welded with the center mounting holes to form an integral structure, and in addition, the left side axial pressure loading fixed baffle plate (2) and the right side axial pressure loading fixed baffle plate (11) penetrate through the peripheral mounting holes of the connecting rod (7) to connect the left side axial pressure loading fixed baffle plate and the right side axial pressure loading fixed baffle plate into an integral body and further form an integral frame system with the supporting platform (1); the left electromagnetic pulse excitation cavity (5) is supported by the left electromagnetic pulse excitation cavity support (6) and is arranged on the support platform (1), wherein the left end part of the left electromagnetic pulse excitation cavity (5) is in free fit contact with the left axial pressure loading piston (4) and is used for transmitting static axial pressure provided by the left axial pressure loading oil cylinder (3) to the left electromagnetic pulse excitation cavity (5) through the left axial pressure loading piston (4); the left stress wave loading rod (8) is supported by a stress wave loading rod support (9) and is arranged on the supporting platform (1), wherein the left end part of the left stress wave loading rod (8) is in free fit contact with the right end surface of the left electromagnetic pulse excitation cavity (5), and the left stress wave loading rod is used for further transmitting static axial pressure transmitted to the left electromagnetic pulse excitation cavity (5) to the left stress wave loading rod (8) and finally acting on the test sample (26), and is used for inputting incident stress waves generated by the left electromagnetic pulse excitation cavity (5) to the left stress wave loading rod (8) and transmitting the incident stress waves along the axial direction of the incident stress waves until a dynamic load from left to right is applied to the test sample (26);
Similarly, the right electromagnetic pulse excitation cavity (14) is supported by the right electromagnetic pulse excitation cavity support (15) and is arranged on the supporting platform (1), wherein the right end part of the right electromagnetic pulse excitation cavity (14) is in free fit contact with the right axial pressure loading piston (13) and is used for transmitting static axial pressure provided by the right axial pressure loading oil cylinder (12) to the right electromagnetic pulse excitation cavity (14) through the right axial pressure loading piston (13); the right stress wave loading rod (16) is supported by the stress wave loading rod support (9) and is arranged on the supporting platform (1), wherein the right end part of the right stress wave loading rod (16) is in free fit contact with the left end surface of the right electromagnetic pulse excitation cavity (14), and the right stress wave loading rod is used for further transmitting static axial pressure transmitted to the right electromagnetic pulse excitation cavity (14) to the right stress wave loading rod (16) and finally acting on the test sample (26), and is used for inputting incident stress waves generated by the right electromagnetic pulse excitation cavity (14) to the right stress wave loading rod (16) and transmitting the incident stress waves along the axial direction of the incident stress wave loading rod until a dynamic load from right to left is applied to the test sample (26);
a resistance strain gauge (10) is arranged on the left stress wave loading rod (8) and the right stress wave loading rod (16);
the confining pressure loading cylinder is surrounded by a confining pressure loading cylinder block (17), a confining pressure loading cylinder (18), a connecting screw (19), a confining pressure loading oil inlet (20), a confining pressure loading exhaust port (21), a confining pressure loading exhaust port sealing plug (22) and a confining pressure oil meter (23) to form a confining pressure loading device, wherein a center mounting hole and a surrounding mounting hole are respectively arranged at the center and the periphery of the confining pressure loading cylinder block (17) for respectively penetrating a left stress wave loading rod (8) and a right stress wave loading rod (16) through the center mounting hole into the confining pressure loading cylinder (18) to be in contact with a test sample (26), the connecting screw (19) connects the confining pressure loading cylinder block (17) and the confining pressure loading cylinder (18) into a whole structure through the surrounding pressure loading cylinder block surrounding mounting hole and is arranged on a supporting platform (1), besides, the lower part and the upper part of the center mounting hole of the right surrounding loading cylinder block (17) are respectively provided with the confining pressure loading hole (20) and the confining pressure loading exhaust port (21) for respectively, the confining pressure loading cylinder block (17) is communicated with a static oil pump (26) through the confining pressure loading oil inlet (20) and the confining pressure exhaust port (21) to the test sample (27), the outside of the confining pressure loading exhaust port (21) is provided with a confining pressure loading exhaust port sealing plug (22) for sealing the confining pressure loading cylinder after the air in the confining pressure loading cylinder is exhausted;
The osmotic pressure loading device comprises a left osmotic pressure pipeline (24) and a right osmotic pressure pipeline (25), wherein the pore diameters and the lengths of the left osmotic pressure pipeline (24) and the right osmotic pressure pipeline (25) are the same, the left osmotic pressure pipeline (24) and the right osmotic pressure pipeline are respectively arranged at the right end part of a left stress wave loading rod (8) and the left end part of a right stress wave loading rod (16) and are in direct contact with the loading end surface of a test sample, when the osmotic pressure is applied, the osmotic liquid with set pressure is injected from the left osmotic pressure pipeline (24), and is discharged from the right osmotic pressure pipeline (25) through a pore network channel communicated with the inside of the test sample (26) under the driving of the osmotic pressure, and the osmotic pressure is kept constant at the set value.
2. The osmotically and statically coupled electromagnetically loaded triaxial SHPB device of claim 1, wherein: the center mounting holes and the periphery mounting holes of the left side axial pressure loading fixed baffle (2), the right side axial pressure loading fixed baffle (11) and the periphery pressure loading cylinder surrounding baffle (17) are circular holes.
3. The osmotically and statically coupled electromagnetically loaded triaxial SHPB device of claim 1, wherein: the left side axial pressure loading fixed baffle plate (2) and the right side axial pressure loading fixed baffle plate (11) are connected into a whole through four small round holes on the periphery of the four connecting rods (7) and further form an integral frame system with the supporting platform.
4. The osmotically and statically coupled electromagnetically loaded triaxial SHPB device of claim 1, wherein: the diameter of the central mounting hole of the confining pressure loading cylinder confining baffle (17) is 1+/-0.1 mm larger than the diameter of the stress wave loading rod.
5. The osmotically and statically coupled electromagnetically loaded triaxial SHPB device of claim 1, wherein: and the center positions of the left stress wave loading rod (8) and the right stress wave loading rod (16) are provided with resistance strain gauges (10).
6. The osmotically and statically coupled electromagnetically loaded triaxial SHPB device of claim 1, wherein: the right side of the confining pressure loading cylinder confining baffle (17) is provided with the confining pressure oil gauge (23).
7. The osmotically and statically coupled electromagnetically loaded triaxial SHPB device of claim 1, wherein: the left stress wave loading rod (8) and the right stress wave loading rod (16) can slide freely on the stress wave loading rod support (9).
8. A method for testing osmotic pressure and static force coupling electromagnetic loading triaxial SHPB is characterized by comprising the following steps of: testing with the device of any one of claims 1 to 7, the specific method is as follows:
firstly, synchronously controlling a left axial pressure loading cylinder (3) and a right axial pressure loading cylinder (12) through an axial pressure servo control loading system to boost the two and drive a left axial pressure loading piston (4) and a right axial pressure loading piston (13) to respectively move rightwards and leftwards so as to further push a left stress wave loading rod (8) and a right stress wave loading rod (16) to respectively apply axial pressure to a test sample (26) at a set loading rate, and stopping loading and keeping the axial pressure constant by utilizing the axial pressure servo control loading system when the axial pressure value reaches a set value;
Then pumping antiwear hydraulic oil into the confining pressure loading cylinder (18) through a confining pressure loading oil inlet (20) at a set speed by using a confining pressure servo control loading system, indicating that the confining pressure loading cylinder is filled with the antiwear hydraulic oil when hydraulic oil flows out from a confining pressure loading exhaust port (21), screwing and sealing the confining pressure loading exhaust port (21) by using a confining pressure loading exhaust port sealing plug (22), continuously applying confining pressure, stopping loading and keeping the confining pressure constant by using the confining pressure servo control loading system when the pressure reading of a confining pressure oil meter (23) reaches a set confining pressure value, so that the circumferential confining pressure of a test sample (26) is constantly set by an anti-seepage rubber sleeve (27); then, an osmotic loading system is utilized to apply osmotic pressure to the test sample (26) through a left osmotic pressure pipeline (24) and a right osmotic pressure pipeline (25), and when the osmotic pressure difference between the left osmotic pressure pipeline (24) and the right osmotic pressure pipeline (25) is constant to be a set value, the coupling action conditions of static shaft pressure, confining pressure and osmotic pressure are applied to the test sample (26);
then according to the test design, an electromagnetic pulse excitation control system is operated to drive a left electromagnetic pulse excitation cavity (5) and a right electromagnetic pulse excitation cavity (14) to synchronously excite and output incident stress waves, and the incident stress waves are respectively transmitted to a test sample (26) along stress wave loading rods at the left side and the right side and dynamically impact and load the test sample, so that a static pressure and osmotic pressure coupling impact loading triaxial SHPB test is completed;
In the dynamic impact loading process, an incident strain signal and a reflected strain signal in the stress wave loading rod are monitored in real time through resistance strain sheets (10) stuck at the central positions of the stress wave loading rods at the left side and the right side; when strain signal data monitored by the strain gauge (10) shows that dynamic compression loads applied by the left end face and the right end face of the test sample (26) are basically consistent in the triaxial SHPB (short-term shock propagation) test process, the dynamic impact loading process of the test sample (26) can be considered to reach a stress balance state, and according to a one-dimensional stress wave propagation theory, the dynamic compression strength sigma (t) of the test sample (26) is obtained by calculating the strain data monitored by the strain gauge (10) according to the following formula by using the strain data monitored by the strain gauge (10), wherein the dynamic compression strain rate is obtained by using the following formulaAnd the strain ε (t) is:
wherein E, C and A are the elastic modulus, longitudinal wave velocity and cross-sectional area of the stress wave loading rod, respectively; a is that s To test the cross-sectional area of the specimen (26), L s For testing the length of the test specimen (26); epsilon Left incidence And epsilon Left reflection Incident strain signal and reflected strain signal respectively monitored by strain gauge from left stress wave loading rod (8), epsilon Right incidence of And epsilon Right reflection Incident strain signal and counter-strain respectively monitored by strain gauge from right stress wave loading rod (16) The strain signal is transmitted.
9. The osmotically and statically coupled electromagnetic loading triaxial SHPB test method of claim 8, characterized in that: the resistance strain gauge (10) transmits an incident strain signal and a reflected strain signal in the stress wave loading rod to the signal amplifier through the Wheatstone bridge by the shielding wire, the strain signal is amplified by the signal amplifier and then is output to the data recorder for recording and storage through the shielding wire, and finally, strain signal data is output to the computer through the data wire for analysis and processing by the data recorder.
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| PCT/CN2019/115487 WO2021017241A1 (en) | 2019-08-01 | 2019-11-05 | Electromagnetic loading triaxial shpb device and test method under coupling of osmotic pressure and static pressure |
| US17/568,929 US11921088B2 (en) | 2019-08-01 | 2022-01-05 | Thermal-stress-pore pressure coupled electromagnetic loading triaxial Hopkinson bar system and test method |
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| CN114720266A (en) * | 2022-05-11 | 2022-07-08 | 天津大学 | Multi-field coupling dynamic loading device and experimental method |
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| CN116642775B (en) * | 2023-07-26 | 2023-10-13 | 深圳市深勘工程咨询有限公司 | Testing device for underground space spalling strength |
| CN117517062A (en) * | 2023-10-17 | 2024-02-06 | 深圳大学 | Dynamic disturbance induced rock burst test device and test method |
| CN117664704A (en) * | 2024-01-02 | 2024-03-08 | 中国矿业大学 | Deep rock true triaxial power loading and unloading composite multifunctional equipment and method |
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