CN114486560A - Low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical test system and test method - Google Patents
Low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical test system and test method Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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Abstract
The invention discloses a low-temperature rock variable-frequency variable-amplitude dynamic shear acoustic physical test system and a test method, wherein the test system comprises a low-temperature control subsystem, a dynamic shear subsystem, an acoustic physical test subsystem and a measurement and control subsystem, the test machine realizes a variable-frequency and variable-amplitude fatigue cycle shear test through a frame system and an environment box, and simultaneously performs acoustic emission and ultrasonic test, can invert a seismic source mechanism in the process of shearing and breaking of a rock mass, can perform acoustic imaging on degradation of a microscopic structure in the process of deformation and breaking of the rock mass, has the characteristics of adjustable frequency and amplitude, capability of simultaneously performing acoustic emission and ultrasonic test, inverting the seismic source mechanism in the process of shearing and breaking of the rock mass, and performing acoustic imaging on degradation of the microscopic structure in the process of deformation and breaking of the rock mass.
Description
Technical Field
The invention belongs to the field of rock mechanical property testing, and particularly relates to a variable-frequency variable-amplitude dynamic shear acoustics physical test system and a test method for a low-temperature rock mass.
Background
The engineering side slope of the strip mine is often disturbed by excavation and frequent blasting stress waves, when the step side slope is far away from the blasting source, the blasting stress waves evolve into seismic waves, and the mechanical property degradation of the rock mass is promoted, so that the degradation of the rock mass structure of the mine side slope is a typical dynamic problem; according to incomplete statistics, the side slope of the open stope is unstable due to the penetration of a rock bridge and accounts for more than 60% of the total landslide, and typical open landslides comprise a climbing iron Zhujia peritectic landslide, an inner Mongolia Baiyun Ebo iron ore Dongbang landslide, an Indonege-Lasburg open mine landslide, an American Bingham valley open copper mine landslide and the like; the continuous occurrence of the slope landslide accident of the bedding rock slope of the strip mine seriously threatens the normal operation of mine enterprises and also greatly threatens the life safety of employees; compared with a plain mine in a low-altitude area, the side slope of the open-pit mine in the low-temperature cold area is disturbed by dynamic disturbance such as excavation, far-field blasting and the like, the frequent freezing and thawing action is another non-negligible factor causing the degradation of the rock bridge structure of the side slope, and the degradation variation of the rock bridge is accelerated by the frost heaving force and the moisture migration action generated in the water ice phase change process; mineral resources in cold regions of China are rich, in high-altitude and high-cold regions, in the face of severe natural environments, the understanding of disaster-causing mechanisms of geological disasters in the side slope environment is not deep enough, and effective prevention and control measures cannot be provided, so that a large number of catastrophic events are triggered by freezing and thawing degradation of a rock mass structure;
the literature research shows that a large number of scholars at home and abroad systematically research the fracture and penetration of the key rock bridge containing the locking section by adopting various means such as field in-situ tests, indoor tests, numerical calculation and the like, the model considers the development of the scale of the rock bridge in the rock from one to a plurality of groups, the model test considers the influences of the roughness, the spatial distribution, the arrangement form, the width and the normal stress of the rock bridge, the model test intensively discusses the mechanical properties, the failure mechanism, the strength and the penetration mode of the rock bridge of the fractured rock mass, and almost all researches are static loading environments at normal temperature without considering the influence of freeze thawing. However, the engineering rock mass is often disturbed frequently by environmental factors, excavation unloading, blasting vibration and seismic waves, so that the dynamic characteristics of the rock bridge fracture are different from the conventional static loading fracture, and the problem is a typical dynamic (medium strain rate) problem. At present, the research on dynamic loading mechanical tests of rock joints under the action of complex stress disturbance is more, mechanical tests of rock bridges under normal unloading conditions at normal temperature are sporadically reported, however, the research on the shear fracture mechanism of freeze-thaw rock bridges is less, and the research on the coupling mechanism of the rock bridges and the joints caused by volume expansion in the fracture process of the rock bridges is not deep enough;
when the porous medium of the rock mass is in a low-temperature environment, water in pores and cracks inside the rock mass is subjected to phase change and freezing, so that the physical mechanical properties of the rock mass are not only related to the physical structure of the rock mass, but also influenced by the water, the temperature and the stress state inside the rock mass; the rock mass can generate high tensile stress through contraction under the action of low temperature, joint cracks serving as initial defects in the rock mass can be further expanded due to nonuniform contraction among particles, the tensile stress can also be generated due to the temperature stress in the rock mass, pores or crack water in the rock mass are subjected to phase change at the low temperature, liquid water is changed into solid ice, the expansion of the volume generates frost heaving effect to aggravate the development of the cracks, and then the expansion and the fragmentation of the cracks are caused, and the physical and mechanical properties are suddenly reduced; in engineering construction, the redistribution of rock stress is caused by rock excavation, the mechanical property of the rock is changed along with the deformation and the damage of the rock, the shear damage has the greatest influence on engineering safety, and the rock is often subjected to dynamic disturbance of different frequencies and amplitudes caused by mechanical excavation, blasting or earthquake load, so that the research on the damage and rupture mechanism of the low-temperature rock under the dynamic shear disturbance of variable frequency and amplitude has important significance for guaranteeing the engineering safety construction in cold regions;
the existing acoustic physical testing technology comprises the technologies of ultrasonic imaging, acoustic emission positioning and the like, and provides a means for realizing the change characteristics of the internal structure of the rock body in the dynamic shear fracture process. Rock ultrasonic imaging is a method for obtaining data inside a rock body through ultrasonic testing, reconstructing an image inside the rock body according to the data and judging the internal situation according to the difference of sound velocity values on the image; the acoustic emission signals invert the internal structure change characteristics of the rock mass through a plurality of parameters such as acoustic emission counting, signal energy, acoustic emission amplitude and the like and waveform characteristics, the initiation of rock mass cracks is positioned, and the acoustic emission parameters and rich information such as waveforms can be described through theoretical research and related mathematical analysis methods, so that the nature of rock mass fracture is obtained;
at present, most of existing rock mass dynamic shearing equipment is static or quasi-static experimental equipment for direct shearing, a few of rock mass dynamic shearing equipment is impact shearing, the loading of variable-frequency variable-amplitude cyclic load cannot be realized, most of equipment does not consider the influence of low temperature on the rock mass shearing failure characteristic and uses an acoustic physical means to realize acoustic physical imaging in the rock mass shearing and cracking process, the dynamic shearing characteristic of jointed rocks under the action of various working conditions in the actual test engineering cannot be simulated, and the internal crack propagation mechanism in the rock mass damage and cracking process cannot be disclosed, so that the development of the low-temperature rock mass variable-frequency variable-amplitude dynamic shearing acoustic physical testing machine is very important.
Disclosure of Invention
Aiming at the existing problems, the invention aims to provide a low-temperature rock variable-frequency variable-amplitude dynamic shear acoustic physical test system and a test method, the test machine realizes a variable-frequency and variable-amplitude fatigue cycle shear test through a frame system and an environment box, simultaneously performs acoustic emission and ultrasonic test, can invert a seismic source mechanism in the process of shearing and breaking of a rock mass, can perform acoustic imaging on the degradation of a microscopic structure in the process of deforming and breaking of the rock mass, and has the characteristics of adjustable frequency and amplitude, capability of simultaneously performing acoustic emission and ultrasonic test, inversion on the seismic source mechanism in the process of shearing and breaking of the rock mass and acoustic imaging on the degradation of the microscopic structure in the process of deforming and breaking of the rock mass.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the low-temperature rock variable-frequency variable-amplitude dynamic shear acoustic physical test system comprises a low-temperature control subsystem, a dynamic shear subsystem, an acoustic physical test subsystem and a measurement and control subsystem;
the low-temperature control subsystem comprises an environment box, a refrigerating pipe and a temperature control collection box, wherein the environment box is arranged in the host frame and is connected with the temperature control collection box through the refrigerating pipe;
the dynamic shearing subsystem is arranged in the environment box and comprises an oil source, a vertical loading mechanism, a transverse shearing mechanism, a shearing box and a rock mass sample, wherein the oil source is respectively connected with the vertical loading mechanism and the transverse shearing mechanism through oil pipes, and the shearing box is arranged between the vertical loading mechanism and the transverse shearing mechanism;
the acoustic physical testing subsystem comprises an ultrasonic imaging system and an acoustic emission positioning system which are arranged on the shear box;
the measurement and control subsystem comprises a displacement measurement system and a data control acquisition calculation imaging system.
Preferably, vertical loading mechanism include vertical connection pad, vertical pressure head, piston and cylinder, the cylinder passes through vertical hydro-cylinder support ring and installs on the host computer frame, and is connected with oil pipe, the piston passes through vertical hydro-cylinder cap movable mounting in the inner chamber of cylinder, and installs the vertical clamp plate at the piston lower extreme and pass through vertical connection pad, vertical spliced pole and be connected with vertical pressure head, the lower extreme of vertical pressure head is provided with the top board, the top board uses with the cooperation of rock mass sample.
Preferably, the transverse shearing mechanism comprises a horizontal oil cylinder support ring, a horizontal oil cylinder cover, a horizontal connecting column, a horizontal pressure head and a horizontal counter-force assembly, the cylinder barrel is mounted on the host frame through the horizontal oil cylinder support ring and is connected with the oil pipe, the piston is movably mounted in an inner cavity of the cylinder barrel through the horizontal oil cylinder cover, a horizontal pressing plate mounted at the end part of the piston is connected with the horizontal pressure head through a horizontal connecting disc and the horizontal connecting column, and the horizontal pressure head is matched with the shearing box for use; horizontal counter force subassembly includes the level by the pole, by pole pressure head and counter force pole, the level is connected with host computer frame through circular nut by the pole, the counter force pole is connected by the pole with the level, by the end of pole pressure head setting at the counter force pole, and use with the cooperation of shearing box.
Preferably, the shearing box comprises an upper shearing box and a lower shearing box which are matched with each other, a guide strip is arranged between the upper shearing box and the lower shearing box, the upper shearing box and the lower shearing box respectively comprise a connecting plate, a side plate, a shearing jaw and a main push plate, the side plates are symmetrically arranged on two sides of the connecting plate and the main push plate and are connected with the connecting plate and the main push plate through connecting bolts, the shearing jaw is arranged on the inner side of the main push plate, a cavity for placing a rock sample is formed on the inner side of the shearing jaw, the main push plate is matched with the transverse shearing mechanism for use, the guide strip is arranged in a guide groove on the side plate, and a sliding mechanism is further arranged on the lower side of the lower shearing box; and the connecting plate, the side plate, the shearing jaw and the main push plate are all provided with mounting round openings with fixed sizes.
Preferably, slide mechanism include bottom plate, roller frame, rod frame connection cushion and a plurality of cushion, the bottom plate sets up the downside of shearing the box under, and the activity block is at the roller frame upside, slides along the rod that sets up on the roller frame, the roller frame is connected the cushion through rod frame and is connected with upper cushion, the cushion is provided with a plurality of pieces, and all connects through the cotter pin between each cushion, the bottom cushion passes through courtyard backing plate and host computer frame attach.
Preferably, the ultrasonic imaging subsystem comprises a plurality of ultrasonic probes and a sound wave controller, the ultrasonic probes are mounted in the middle of the side plates and the connecting plates on the two sides of the upper shearing box and the lower shearing box, the ultrasonic probes are connected with sensors in the sound wave controller, and the sound wave controller can receive ultrasonic signals and realize ultrasonic imaging of the internal structure of the rock body in a computer through computing software.
Preferably, the acoustic emission positioning subsystem comprises an acoustic emission probe and an acoustic emission controller, the acoustic emission probe is positioned on the side plates on the two sides of the upper shearing box and the lower shearing box, the acoustic emission probe is connected with a sensor in the acoustic emission controller, and the acoustic emission controller can receive acoustic emission signals and realize acoustic emission positioning imaging of the internal structure of the rock mass in a computer through computing software.
Preferably, the data control acquisition calculation imaging subsystem comprises a loading oil source controller and a computer, sensors in the loading oil source controller, the sound wave controller and the acoustic emission controller are all connected with the computer, automatic control of the loading system and data reading can be achieved, and ultrasonic imaging and acoustic emission positioning imaging can be achieved after processing through analysis software.
Preferably, the displacement measurement subsystem comprises a horizontal shearing displacement measurement mechanism and a vertical compression displacement measurement mechanism, the horizontal shearing displacement measurement mechanism and the vertical compression displacement measurement mechanism respectively comprise a grating ruler, a sensor bracket, a support, an adjusting rod and a contact piece, the support of the vertical compression displacement measurement mechanism is connected with the upper pressure plate through a connecting bolt, the support of the horizontal shearing displacement measurement mechanism is connected with a connecting plate of the lower shearing box through a connecting bolt, the adjusting rod is in threaded connection with the support, the tail end of the adjusting rod is provided with a knob, the contact piece is arranged on the adjusting rod, the grating ruler of the vertical compression displacement measurement mechanism is connected with the roller frame through the sensor bracket and the connecting bolt and is matched with the corresponding contact piece of the vertical compression displacement measurement mechanism for use, the grating ruler of the horizontal shearing displacement measurement mechanism is connected with a rod pressure head through the sensor bracket and the connecting bolt, and is used in cooperation with a contact piece of a corresponding horizontal shear displacement measuring mechanism.
The test method of the low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical test system comprises the following steps
S1, placing a rock mass sample into a shearing box, adjusting a knob to enable a grating ruler to be in contact with a contact piece and give appropriate pressure to the grating ruler, and then closing an environmental box door;
s2, connecting an acoustic emission probe and an ultrasonic probe, tightly attaching the acoustic emission probe and the ultrasonic probe to a rock sample, starting an acoustic controller, the acoustic emission controller and a computer, and testing the smoothness and effective signals of a circuit;
s3, starting a temperature control collection box, setting a certain low temperature in the environment box, and starting a refrigeration cycle; the real-time freezing and thawing, freezing and thawing treatment of the rock is realized, and the temperature and the freezing and thawing times in the environmental chamber can be automatically controlled;
s4, starting the dynamic shear testing machine and the loading oil source controller to test the disturbance power signal;
s5, setting a loading frequency, an amplitude and a cycle number for the testing machine through loading control software of a computer, resetting displacement data measured by the grating ruler, and transmitting ultrasonic waves and starting loading when the temperature in the environment box reaches a set value;
s6, in the loading process, data acquisition is carried out on the load, the displacement, the ultrasonic signal and the acoustic emission signal through a measurement and control system, and the change of a shear stress and a strain curve in the loading process is observed;
s7, stopping loading when the rock mass sample is damaged;
and S8, closing the temperature control collection box, opening an environmental box door, taking out the damaged rock mass sample after the temperature in the environmental box reaches the room temperature, and closing the low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustics physical test system.
The invention has the beneficial effects that: the invention discloses a low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical testing machine and a testing method, compared with the prior art, the invention has the improvement that:
(1) the invention designs a low-temperature rock variable-frequency variable-amplitude dynamic shear acoustic physical testing machine and a testing method, the testing machine realizes power loading, servo control and response of complex disturbance stress waveforms under the variable-frequency variable-amplitude condition through the design of a frame system and an environment box, and can perform accurate servo control and high-speed servo response on two servo valves of a main oil cylinder and a shear oil cylinder in the fatigue shearing process;
(2) meanwhile, the low-temperature control system can simulate the rock mass in complex environments such as low temperature, freeze-thaw cycle and the like, the dynamic shearing mechanical characteristics of the rock mass under the actual engineering general condition are truly restored, and the transparent and high-strength environmental box door can keep the closed state of the environmental box and can safely observe the rock mass sample plot form in the shearing process in real time;
(3) the design of the acoustic physical test system can realize ultrasonic imaging and acoustic emission positioning imaging, and can reveal the change characteristics of the internal structure of the rock body in the dynamic shear fracture process;
(4) the high-resolution dynamic measurement problem of rock sample deformation in the dynamic load process is solved by the grating ruler displacement sensor, the grating ruler displacement sensor has the advantages that the measuring range is larger than the precision, the dynamic measurement can be realized, the automation of measurement and data processing is easy to realize, in the experimental process, the frequency and the amplitude are adjustable, the acoustic emission and the ultrasonic testing can be simultaneously carried out, the inversion is carried out on a seismic source mechanism in the rock mass shearing and cracking process, and the acoustic imaging is carried out on the degradation of a microscopic structure in the rock mass deformation and cracking process.
Drawings
FIG. 1 is a structural schematic diagram of the whole system of the low-temperature rock frequency-conversion amplitude-variation dynamic shear acoustics physical test system.
FIG. 2 is a front view of the whole system structure of the low-temperature rock variable-frequency variable-amplitude dynamic shear acoustics physical test system.
FIG. 3 is a front view of the structure of the dynamic shear tester of the present invention.
FIG. 4 is a structural cross-sectional view of the dynamic shear tester of the present invention.
Fig. 5 is a schematic structural view of the shear box of the present invention.
FIG. 6 is a schematic diagram of the configuration of the acousto-physical testing subsystem of the present invention.
Fig. 7 is a schematic structural view of the sliding mechanism of the present invention.
FIG. 8 is a front view of the displacement measurement subsystem of the present invention.
FIG. 9 is a side view of the displacement measurement subsystem of the present invention.
FIG. 10 is a top view of the displacement measurement subsystem of the present invention.
Wherein: 1. a source of oil; 2. an oil supply control line; 3. an oil pipe; 4. a host frame; 5. a vertical cylinder cover; 6. a vertical oil cylinder support ring; 7. a vertical pressing plate; 8. a vertical connecting disc; 9. a vertical ram; 10, an upper pressing plate; 11. an upper shearing box; 12. a lower shear box; 13. an environmental chamber; 14. a stick is arranged; 15. the stick frame is connected with the cushion block; 16. cushion blocks; 17. a yard liner plate; 18. a grating scale; 19. a horizontal pressure head; 20. a horizontal connecting disc; 21. a horizontal pressing plate; 22. a refrigeration pipe; 23. a horizontal quilt rod; 24. a temperature control box; a computer; 26. a loading oil source controller; 27. a sound wave controller; 28. an acoustic emission controller; acoustic control line 29; 30. an acoustic emission control line; 31. a driven rod pressing head; 32. a reaction rod; 33. a knob; 34. a contact piece; 35. adjusting a rod; 36. a support; 37. an acoustic emission probe; 38. an ultrasonic probe; 39. a base plate; 40. a guide strip; 41. a sensor bracket; 42. a horizontal cylinder head; 43. a horizontal cylinder support ring; 44. a piston; 45. a stick; 46. a roller frame; 47. a horizontal connecting column; 48. a cylinder barrel; 49, a vertical connecting column; 50. cutting the jaw; 51. a main push plate; 52. a rock mass sample; 53. a side plate; a connecting plate.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the following further describes the technical solution of the present invention with reference to the drawings and the embodiments.
Referring to the accompanying drawings 1-10, the low-temperature rock variable-frequency variable-amplitude dynamic shear acoustic physical test system comprises a low-temperature control subsystem, a dynamic shear subsystem, an acoustic physical test subsystem and a measurement and control subsystem;
the low-temperature control subsystem comprises an environment box 13, a refrigerating pipe 22 and a temperature control collection box 24, wherein the environment box 13 is arranged in the main frame 4 and is connected with the temperature control collection box 24 through the refrigerating pipe 22, and when the system is used, the temperature control collection box 24 transmits cold air flow through the refrigerating pipe 22 so as to control the temperature in the environment box 13;
the dynamic shearing subsystem is arranged in the environment box 13 and comprises an oil source 1, a vertical loading mechanism, a transverse shearing mechanism, a shearing box and a rock mass sample 52, wherein the oil source 1 is respectively connected with the vertical loading mechanism and the transverse shearing mechanism through oil pipes 3 to provide loading pressure for the vertical loading mechanism and the transverse shearing mechanism, and the shearing box is arranged between the vertical loading mechanism and the transverse shearing mechanism and used for fixing the rock mass sample 52;
the acoustic physical testing subsystem comprises an ultrasonic imaging system and an acoustic emission positioning system which are arranged on the shear box;
the measurement and control subsystem comprises a displacement measurement system and a data control acquisition calculation imaging system.
Preferably, as shown in fig. 3-4, the dynamic testing machine realizes dynamic loading of complex disturbance stress waveforms of the rock mass sample 52 in the shear box under the condition of variable frequency and amplitude by combining the vertical loading subsystem with the transverse shearing subsystem; wherein the vertical loading mechanism comprises a vertical connecting disc 8, a vertical pressure head 9, a piston 44 and a cylinder barrel 48, the cylinder barrel 48 is arranged on the host frame 4 through a vertical cylinder supporting ring 6 and is connected with the oil pipe 3, the piston 44 is movably arranged in the inner cavity of the cylinder barrel 48 through a vertical cylinder cover 5, a vertical pressing plate 7 arranged at the lower end of the piston 44 is connected with the vertical pressure head 9 through the vertical connecting disc 8, a vertical connecting column 49 and a hexagon bolt, an upper pressing plate 10 is arranged at the lower end of the vertical pressure head 9, the upper pressing plate 10 is matched with a rock mass sample 52 for use, namely, in the process of axially pressurizing the rock mass sample 52, an oil source 1 pumps hydraulic oil into the cylinder barrel 48 through the oil pipe 3, the piston 44 is pushed to transmit axial pressure downwards along with the increase of the oil pressure in the cylinder barrel 48, and axial load is transmitted to the vertical pressure head 9 through the vertical pressing plate 7 and then transmitted on the lower pressing plate 10 downwards, applying axial pressure to the rock mass sample 52 by using the lower pressing plate 10;
the transverse shearing mechanism comprises a horizontal oil cylinder supporting ring 43, a horizontal oil cylinder cover 42, a horizontal connecting column 47, a horizontal pressure head 49 and a horizontal counter-force assembly, the cylinder barrel 48 is arranged on the main frame 4 through the horizontal oil cylinder supporting ring 43, and is connected with the oil pipe 3, the piston 44 is movably arranged in the inner cavity of the cylinder barrel 48 through the horizontal cylinder cover 42, and the horizontal pressing plate 21 arranged at the end part of the piston 44 is connected with the horizontal pressing head 19 through a horizontal connecting disc 20, a horizontal connecting column 47 and a hexagon bolt, the horizontal pressing head 19 is matched with the shearing box for use, when the horizontal shearing device is used, the oil source 1 pumps hydraulic oil into the cylinder 48 through the oil pipe 3, the piston 44 is pushed to apply a shearing load in the horizontal direction along with the increase of the oil pressure in the cylinder 48, the horizontal load is transmitted to the horizontal pressure head 19 through the horizontal pressure plate 21, and the horizontal pressure head 19 is used for applying the shearing load in the horizontal direction to the lower box body 12 of the shearing box; the horizontal counter force component comprises a horizontal driven rod 23, a driven rod pressure head 31 and a counter force rod 32, wherein the horizontal driven rod 23 is connected with the host frame 4 through a circular nut, the counter force rod 32 is connected with the horizontal driven rod 23, the driven rod pressure head 31 is arranged at the tail end of the counter force rod 32 and is matched with the upper box body 11 of the shear box for use, and a counter force is applied to the upper box body 11.
Preferably, as shown in fig. 5, the shear box includes an upper shear box 11 and a lower shear box 12 which are used in cooperation with each other, and a guide strip 40 is arranged between the upper shearing box 11 and the lower shearing box 12, the upper shearing box 11 and the lower shearing box 12 both comprise a connecting plate 54, a side plate 53, a shearing jaw 50 and a main push plate 51, the side plate 53 is symmetrically arranged at two sides of the connecting plate 54 and the main push plate 51, and is connected with the connecting plate 54 and the main push plate 51 through a connecting bolt to form a square box structure, the shearing jaw 50 is arranged at the inner side of the main push plate 51, and a cavity for placing a rock mass sample 52 is formed inside the shearing jaw 50, the main push plate 51 is matched with a transverse shearing mechanism for use, namely, when in use, the horizontal pressure head 19 applies a horizontal shearing load to the lower box body 12, and the rod pressure head 31 applies a reverse acting force to the upper box body 11; and when reducing the frictional resistance between the upper box body 11 and the lower box body 12 when exerting external force, the guide strip 40 sets up in the guide way on curb plate 53, utilizes horizontal shear force and the reaction force that acts on lower shear box 12 and upper shear box 11 to carry out the shearing to rock mass sample 52 when using, for avoiding the frictional force of lower part of lower shear box 12 to influence the shearing precision in the shearing process, still be provided with slide mechanism in the downside of lower shear box 12.
Preferably, slide mechanism include bottom plate 39, roller frame 46, rod frame connection cushion 15 and a plurality of cushion 16, bottom plate 39 sets up the downside of shearing box 12 down, and the card and the mode activity block through the slide rail draw-in groove are at roller frame 46 upside, rotate through last rod 14 on the roller frame 46 and install rod 45, bottom plate 39's downside still with rod 45 in close contact with, under the effect of shear force, slide along rod 45 side to side, roller frame 46 is connected cushion 15 and upper cushion 16 through rod frame, fixes roller frame 46, cushion 16 is provided with a plurality of, and all connects through the cotter pin between each cushion 16, cushion 16 is connected with host computer frame 4 through small hospital's cushion 17, supports upper portion loading mechanism.
Preferably, the connecting plate 54, the side plate 53, the shearing jaw 50 and the main push plate 51 are all provided with mounting round openings with fixed sizes, so that ultrasonic imaging and acoustic emission positioning of rock mass fracture in the dynamic shearing process are facilitated; the ultrasonic imaging subsystem comprises six ultrasonic probes 38 and an acoustic controller 27, the six ultrasonic probes 38 are mounted in the middle of side plates 53 and a connecting plate 54 on two sides of the upper shearing box 11 and the lower shearing box 13, the ultrasonic probes 38 are connected with sensors in the acoustic controller 27, and the acoustic controller 27 can receive ultrasonic signals and realize ultrasonic imaging of the internal structure of the rock body in a computer through computing software.
Preferably, the acoustic emission positioning subsystem comprises twelve acoustic emission probes 37 and an acoustic emission controller 28, the acoustic emission probes 37 are positioned on the side plates 53 on the two sides of the upper shear box 11 and the lower shear box 12, the acoustic emission probes 37 are connected with sensors in the acoustic emission controller 28, and the acoustic emission controller 28 can receive acoustic emission signals and realize acoustic emission positioning imaging of the internal structure of the rock mass in a computer through computing software.
Preferably, the data control acquisition computational imaging subsystem comprises a loading oil source controller 26 and a computer 25, sensors in the loading oil source controller 26, a sound wave controller 27 and a sound emission controller 28 are all connected with the computer 25, automatic control of the loading system and data reading can be realized through control of the computer 25, and ultrasonic imaging and sound emission positioning imaging can be realized after processing by analysis software.
Preferably, the displacement measurement subsystem comprises a horizontal shearing displacement measurement mechanism and a vertical compression displacement measurement mechanism, the horizontal shearing displacement measurement mechanism and the vertical compression displacement measurement mechanism both comprise a grating ruler 18, a sensor bracket 41, a support 36, an adjusting rod 35, a knob 33 and a contact piece 34, the support 36 of the vertical compression displacement measurement mechanism is connected with the upper press plate 10 through a connecting bolt, the support 36 of the horizontal shearing displacement measurement mechanism is connected with a connecting plate 54 of the lower shearing box 12 through a connecting bolt, the adjusting rod 35 is in threaded connection with the support 36, the knob 33 is arranged at the tail end of the adjusting rod 35 and used for adjusting the relative distance between the adjusting rod 35 and the support 36, the contact piece 34 is arranged on the adjusting rod 35, and meanwhile, the grating ruler 18 of the vertical compression displacement measurement mechanism is connected with the roller frame 46 through a sensor bracket 41 and a connecting bolt, the grating ruler 18 of the horizontal shearing displacement measuring mechanism is connected with the driven rod pressure head 31 through a sensor bracket 41 and a connecting bolt and is matched with the corresponding contact piece 34 of the horizontal shearing displacement measuring mechanism for use; when the vertical compression displacement measuring mechanism is used, when the vertical compression displacement of the rock mass sample 52 is measured, the grating ruler 18 on the sensor bracket 41 of the vertical compression displacement measuring mechanism is firstly contacted with the contact piece 34 and is in a pressed state, the bracket 36 is fixed on the upper pressing plate 10, and when the rock mass sample 52 is compressed, the upper pressing plate 10 drives the adjusting rod 35 and the contact piece 34 to displace downwards, so that the reading head of the grating ruler 18 is loosened to measure the vertical displacement; when the horizontal shearing displacement is measured, the grating ruler 18 on the sensor bracket 41 of the horizontal shearing displacement measuring mechanism is firstly contacted with the contact piece 34 and is in a pressed state, when the rock mass sample 52 generates shearing slippage, the lower shearing box 12 drives the adjusting rod 35 and the contact piece 34 to displace towards the direction of the counter force rod 32, and the reading head of the grating ruler 18 loosens along with the movement of the contact piece 34 to measure the horizontal shearing displacement.
Preferably, in the technical scheme provided by the embodiment of the invention, for convenience of observation, the environmental box door is made of a transparent material with certain strength, the test process inside the dynamic shear testing machine can be observed while the cooling circulation sealing of the environmental box 13 is realized, and a proper cooling liquid is selected to ensure that the lowest temperature inside the environmental box 13 reaches minus 65 ℃ when the testing machine normally works.
Preferably, the rock mass sample 52 can be a complete rock mass, a non-through fractured rock mass or a through fractured rock mass.
Preferably, the loading frequency range of the dynamic shear testing machine is 0-10 HZ, and the loadable range of the vertical load and the horizontal load is 0-1000 t.
Preferably, the shear box size may be 100mm × 100mm × 100mm or 100mm × 100mm × 200 mm; the loading height of the rock mass sample 52 can be adjusted by adjusting the number of the cushion blocks 15 when the shear boxes with different sizes are switched.
The invention discloses a test method of a variable-frequency variable-amplitude dynamic shear acoustics physical test system of a low-temperature rock mass, which comprises the following steps of:
s1, placing a rock mass sample 52 into a shear box, adjusting a knob 33 to enable a grating ruler 18 to be in contact with a contact sheet 34 and give proper pressure to the grating ruler 18, and then closing an environmental box door;
s2, connecting an acoustic emission probe and an ultrasonic probe, tightly attaching the acoustic emission probe and the ultrasonic probe to a rock sample, starting an acoustic controller 27, an acoustic emission controller 28 and a computer 25, and testing the smoothness and effective signals of a circuit;
s3, starting a temperature control collection box 24, setting a certain low temperature in the environment box, and then starting a refrigeration cycle; the real-time freezing and thawing, freezing and thawing treatment of the rock is realized, and the temperature and the freezing and thawing times in the environmental chamber can be automatically controlled;
s4, starting the dynamic shear testing machine and the loading oil source controller 26 to test the disturbance power signal;
s5, setting a loading frequency, an amplitude and a cycle number for the testing machine through loading control software of the computer 25, resetting displacement data of the grating ruler 18, transmitting ultrasonic waves and starting loading when the temperature in the environment box 13 reaches a set value;
s6, in the loading process, data acquisition is carried out on the load, the displacement, the ultrasonic signal and the acoustic emission signal through a measurement and control system, and the change of a shear stress-strain curve in the loading process is observed;
s7, stopping loading when the rock mass sample 52 is damaged;
and S8, closing the temperature control collection box 24, opening an environmental box door, taking out the damaged rock mass sample 52 after the temperature in the environmental box 13 reaches the room temperature, and closing the low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustics physical test system.
The low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustics physical test system has the following advantages:
(1) the test system can meet the requirements of most test scales, can realize variable-frequency variable-amplitude loading through the dynamic shearing system, the low-temperature control system, the acoustic physical test system and the measurement and control system, can consider the influence of low temperature on the shearing failure characteristic of the rock mass and realize acoustic physical imaging in the shearing and cracking process of the rock mass by using an acoustic physical means, can simulate the dynamic shearing characteristic of jointed rock under the action of various working conditions in the actual test engineering and disclose the internal crack propagation mechanism in the damage and cracking process of the rock mass, enriches the data obtained by the test, and improves the test quality;
2. the test system disclosed by the invention can be used for positioning the initiation of the internal cracks of the rock mass sample in the loading process by using an ultrasonic imaging technology and an acoustic emission positioning imaging technology in an acoustic physical test system, and can reveal the internal structure change characteristics of the rock mass in the dynamic shear fracture process;
3. according to the above embodiments, the testing machine of the testing system of the present invention employs the strain gauge and the strain gauge to measure the deformation of the sample under dynamic disturbance, the methods of measuring the deformation by the strain gauge are all averages of the deformation on the rock sample point or the surface, the measurement result is closely related to the strain measurement position, the sequentially calculated body strain is also local, and meanwhile, the deformation amount of the sample under the dynamic shearing action is large, and the precision is poor. According to the invention, the grating ruler displacement sensor is adopted to measure the deformation of the rock mass sample in the dynamic shearing process, so that the problem of high-resolution dynamic measurement of the rock mass sample deformation in the dynamic loading process is solved, and meanwhile, the grating ruler displacement sensor has the advantages of high measuring range and precision and the like, can realize dynamic measurement, and is easy to realize automation of measurement and data processing.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. Low temperature rock mass frequency conversion becomes width of cloth dynamic shear acoustics physical test system, its characterized in that: the system comprises a low-temperature control subsystem, a dynamic shearing subsystem, an acoustic physical testing subsystem and a measurement and control subsystem;
the low-temperature control subsystem comprises an environment box (13), a refrigerating pipe (22) and a temperature control collection box (24), wherein the environment box (13) is arranged in the main frame (4) and is connected with the temperature control collection box (24) through the refrigerating pipe (22);
the dynamic shearing subsystem is arranged in the environment box (13) and comprises an oil source (1), a vertical loading mechanism, a transverse shearing mechanism, a shearing box and a rock mass sample (52), wherein the oil source (1) is respectively connected with the vertical loading mechanism and the transverse shearing mechanism through oil pipes (3), and the shearing box is arranged between the vertical loading mechanism and the transverse shearing mechanism;
the acoustic physical testing subsystem comprises an ultrasonic imaging system and an acoustic emission positioning system which are arranged on the shear box;
the measurement and control subsystem comprises a displacement measurement system and a data control acquisition calculation imaging system.
2. The variable-frequency variable-amplitude dynamic shear acoustic physical test system for the low-temperature rock mass according to claim 1, which is characterized in that: vertical loading mechanism include vertical connection pad (8), vertical pressure head (9), piston (44) and cylinder (48), cylinder (48) are installed on host computer frame (4) through vertical hydro-cylinder support ring (6), and are connected with oil pipe (3), piston (44) are through vertical hydro-cylinder cap (5) movable mounting in the inner chamber of cylinder (48), and install vertical clamp plate (7) at piston (44) lower extreme and be connected with vertical pressure head (9) through vertical connection pad (8), vertical spliced pole (49), the lower extreme of vertical pressure head (9) is provided with top board (10), top board (10) are used with rock mass sample (52) cooperation.
3. The low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical test system as claimed in claim 2, which is characterized in that: the transverse shearing mechanism comprises a horizontal oil cylinder supporting ring (43), a horizontal oil cylinder cover (42), a horizontal connecting column (47), a horizontal pressure head (49) and a horizontal reaction force assembly, the cylinder barrel (48) is installed on the host frame (4) through the horizontal oil cylinder supporting ring (43) and is connected with the oil pipe (3), the piston (44) is movably installed in the inner cavity of the cylinder barrel (48) through the horizontal oil cylinder cover (42), the horizontal pressure plate (21) installed at the end part of the piston (44) is connected with the horizontal pressure head (19) through the horizontal connecting disc (20) and the horizontal connecting column (47), and the horizontal pressure head (19) is matched with the shearing box for use; the horizontal counter force component comprises a horizontal driven rod (23), a driven rod pressure head (31) and a counter force rod (32), the horizontal driven rod (23) is connected with the host frame (4) through a circular nut, the counter force rod (32) is connected with the horizontal driven rod (23), and the driven rod pressure head (31) is arranged at the tail end of the counter force rod (32) and is matched with the shearing box for use.
4. The low-temperature rock mass frequency-conversion amplitude-variation dynamic shear acoustic physical test system according to any one of claims 1 to 3, wherein: the shearing box comprises an upper shearing box (11) and a lower shearing box (12) which are matched with each other, a guide strip (40) is arranged between the upper shearing box (11) and the lower shearing box (12), the upper shearing box (11) and the lower shearing box (12) both comprise a connecting plate (54), a side plate (53), a shearing jaw (50) and a main push plate (51), the side plates (53) are symmetrically arranged at two sides of the connecting plate (54) and the main push plate (51), and is connected with a connecting plate (54) and a main push plate (51) through a connecting bolt, the shearing jaw (50) is arranged on the inner side of the main push plate (51), and a cavity for placing a rock mass sample (52) is formed at the inner side of the shearing jaw (50), the main push plate (51) is matched with a transverse shearing mechanism for use, the guide strip (40) is arranged in a guide groove on the side plate (53), and a sliding mechanism is further arranged on the lower side of the lower shearing box (12); and mounting round openings with fixed sizes are arranged on the connecting plate (54), the side plate (53), the shearing jaw (50) and the main push plate (51).
5. The variable-frequency variable-amplitude dynamic shear acoustic physical test system for the low-temperature rock mass according to claim 4, characterized in that: slide mechanism include bottom plate (39), roller frame (46), rod frame connection cushion (15) and a plurality of cushion (16), bottom plate (39) set up the downside of shearing box (12) down, and the activity block slides along rod (45) of setting on roller frame (46) at roller frame (46) upside, rod (45) rotate through last rod (14) and install on roller frame (46), roller frame (46) are connected cushion (15) and cushion (16) through rod frame, cushion (16) are folded and are equipped with a plurality of, prime cushion (16) are connected with host computer frame (4) through small yard backing plate (17).
6. The variable-frequency variable-amplitude dynamic shear acoustic physical test system for the low-temperature rock mass according to claim 4, characterized in that: the ultrasonic imaging subsystem comprises a plurality of ultrasonic probes (38) and an ultrasonic controller (27), the ultrasonic probes (38) are mounted in the middle of side plates (53) and connecting plates (54) on two sides of an upper shearing box (11) and a lower shearing box (13), the ultrasonic probes (38) are connected with sensors in the ultrasonic controller (27), and the ultrasonic controller (27) can receive ultrasonic signals and realize ultrasonic imaging of the internal structure of the rock mass in a computer through computer software.
7. The variable-frequency variable-amplitude dynamic shear acoustic physical test system for the low-temperature rock mass according to claim 6, which is characterized in that: the acoustic emission positioning subsystem comprises an acoustic emission probe (37) and an acoustic emission controller (28), the acoustic emission probe (37) is positioned on side plates (53) on two sides of the upper shear box (11) and the lower shear box (12), the acoustic emission probe (37) is connected with a sensor in the acoustic emission controller (28), and the acoustic emission controller (28) can receive acoustic emission signals and realize acoustic emission positioning imaging of the internal structure of the rock mass in a computer through calculation software.
8. The variable-frequency variable-amplitude dynamic shear acoustic physical test system for the low-temperature rock mass according to claim 7, which is characterized in that: the data control acquisition calculation imaging subsystem comprises a loading oil source controller (26) and a computer (25), wherein sensors in the loading oil source controller (26), a sound wave controller (27) and a sound emission controller (28) are connected with the computer (25), automatic control of the loading system and data reading can be achieved, and ultrasonic imaging and acoustic emission positioning imaging can be achieved after processing through analysis software.
9. The variable-frequency variable-amplitude dynamic shear acoustic physical test system for the low-temperature rock mass according to claim 5, characterized in that: the displacement measurement subsystem comprises a horizontal shearing displacement measurement mechanism and a vertical compression displacement measurement mechanism, the horizontal shearing displacement measurement mechanism and the vertical compression displacement measurement mechanism respectively comprise a grating ruler (18), a sensor bracket (41), a support (36), an adjusting rod (35) and a contact piece (34), the support (36) of the vertical compression displacement measurement mechanism is connected with an upper pressure plate (10) through a connecting bolt, the support (36) of the horizontal shearing displacement measurement mechanism is connected with a connecting plate (54) of a lower shearing box (12) through a connecting bolt, the adjusting rod (35) is in threaded connection with the support (36), a knob (33) is arranged at the tail end of the adjusting rod (35), the contact piece (34) is arranged on the adjusting rod (35), and the grating ruler (18) of the vertical compression displacement measurement mechanism is connected with a roller frame (46) through the sensor bracket (41) and the connecting bolt, and the grating ruler (18) of the horizontal shearing displacement measuring mechanism is connected with the driven rod pressure head (31) through a sensor bracket (41) and a connecting bolt and is matched with the corresponding contact piece (34) of the horizontal shearing displacement measuring mechanism for use.
10. The test method of the low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical test system according to claim 1, characterized in that: the method comprises the steps of
S1, placing a rock mass sample into a shearing box, adjusting a knob to enable a grating ruler to be in contact with a contact piece and give appropriate pressure to the grating ruler, and then closing an environmental box door;
s2, connecting an acoustic emission probe and an ultrasonic probe, tightly attaching the acoustic emission probe and the ultrasonic probe to a rock sample, starting an acoustic controller, the acoustic emission controller and a computer, and testing the smoothness and effective signals of a circuit;
s3, starting a temperature control collection box, setting a certain low temperature in the environment box, and starting a refrigeration cycle; the real-time freezing and thawing, freezing and thawing treatment of the rock is realized, and the temperature and the freezing and thawing times in the environmental chamber can be automatically controlled;
s4, starting the dynamic shear testing machine and the loading oil source controller to test the disturbance power signal;
s5, setting a loading frequency, an amplitude and a cycle number for the testing machine through loading control software of a computer, resetting displacement data measured by the grating ruler, and transmitting ultrasonic waves and starting loading when the temperature in the environment box reaches a set value;
s6, in the loading process, data acquisition is carried out on the load, the displacement, the ultrasonic signal and the acoustic emission signal through a measurement and control system, and the change of a shear stress and a strain curve in the loading process is observed;
s7, stopping loading when the rock mass sample is damaged;
and S8, closing the temperature control collection box, opening an environmental box door, taking out the damaged rock mass sample after the temperature in the environmental box reaches the room temperature, and closing the low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustics physical test system.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115656336A (en) * | 2022-10-31 | 2023-01-31 | 四川大学 | Acoustic real-time imaging system and method for testing state evolution of rock mass under deep-ground condition |
| CN118294298A (en) * | 2024-06-05 | 2024-07-05 | 东北大学 | Drop hammer test method for design process of deep engineering machinery rock breaking equipment |
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2021
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115656336A (en) * | 2022-10-31 | 2023-01-31 | 四川大学 | Acoustic real-time imaging system and method for testing state evolution of rock mass under deep-ground condition |
| CN118294298A (en) * | 2024-06-05 | 2024-07-05 | 东北大学 | Drop hammer test method for design process of deep engineering machinery rock breaking equipment |
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