CN114486560A - Low-temperature rock mass variable-frequency variable-amplitude dynamic shear acoustic physical test system and test method - Google Patents

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

Low temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical test system and test method

technical field

The invention belongs to the field of rock mechanical property testing, in particular to a low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical test system and a test method.

Background technique

Open-pit mine engineering slopes are often disturbed by excavation and frequent blasting stress waves. When the step slope is far away from the blast source, blasting stress waves evolve into seismic waves, which play a role in promoting the deterioration of rock mass mechanical properties. Deterioration of rock mass structure of mine slopes is a typical dynamic problem; according to incomplete statistics, the instability of open-pit stope slopes due to the penetration of rock bridges accounts for more than 60% of the total number of landslides. Landslides at Bao Iron Mine, Dongbang Landslides at Bayan Obo Iron Mine in Inner Mongolia, Landslides at Grasburg Open-pit Mine in Indonesia and Bingham Canyon Open-pit Copper Mine in the United States, etc. The continuous occurrence of open-pit mine landslides along bedrock rock slopes is not only a serious threat The normal operation of mining enterprises also poses a huge threat to the life safety of employees; compared with plain mines in low-altitude areas, in addition to dynamic disturbances such as excavation and far-field blasting, the slopes of open-pit mines in low-temperature and cold areas are frequently disturbed. The freeze-thaw effect is another factor that cannot be ignored that causes the structural deterioration of the rock bridge on the slope. The frost heave force generated by the water-ice phase transition process and the migration of water accelerate the deterioration and variation of the rock bridge; China's cold regions are rich in mineral resources, and In the high-altitude and cold areas, facing the harsh natural environment, the understanding of the disaster mechanism of slope environmental geological disasters is not deep enough, and effective prevention and control measures cannot be provided. Therefore, the freeze-thaw deterioration of rock mass structures triggers a large number of catastrophic events;

The literature survey shows that a large number of scholars at home and abroad have used various methods such as field in-situ tests, laboratory tests and numerical calculations to systematically study the fracture penetration of key rock bridges with locking sections. The model considers the scale of rock bridges in the rock. From one to multiple and multiple groups, the model test takes into account the influence of joint roughness, spatial distribution, arrangement form, rock bridge width and normal stress, focusing on the mechanical properties, failure mechanism, strength and strength of rock bridges in fractured rock mass. and through-through mode were discussed, almost all of the studies were static loading environments at room temperature, without considering the effects of freezing and thawing. However, because the engineering rock mass is frequently disturbed by environmental factors, excavation unloading, blasting vibration and seismic waves, the dynamic characteristics of rock bridge fractures are different from those of previous static loading fractures. rate) problem. At present, there are many studies on dynamic loading mechanical tests of rock joints under complex stress disturbances, and there are sporadic reports on mechanical tests of rock bridges under normal unloading conditions at room temperature. However, there are few studies on the shear fracture mechanism of freeze-thawed rock bridges. The research on the coupling mechanism between the rock bridge and the joint caused by the volume expansion during the rock bridge fracture process is not deep enough;

When the porous medium of rock mass is in a low temperature environment, the water existing in the pores and fissures of the rock mass undergoes phase change and freezes, resulting in the physical and mechanical properties of the rock mass not only related to its own physical structure, but also to its internal occurrence. The influence of water, temperature, and stress state; the rock mass suffers from low temperature, which will generate high tensile stress through shrinkage, and joint cracks, as the initial defects in the rock mass, will further expand due to the uneven shrinkage between particles, and the cracks in the rock mass will be further expanded. Temperature stress can also lead to the generation of tensile stress, and the pore or fissure water in the rock body undergoes a phase change at low temperature, from liquid water to solid ice, and the expansion of volume produces frost heave, which aggravates the development of fissures, and then causes fissures. In engineering construction, rock mass excavation causes stress redistribution of rock mass, and along with the deformation and failure of rock mass, its mechanical properties also change. The biggest impact on engineering safety is shear stress. However, the rock mass is often subjected to dynamic disturbances of different frequencies and amplitudes caused by mechanical excavation, blasting or seismic loads. The safety construction of the district project is of great significance;

At present, acoustic physical testing technologies, including ultrasonic imaging, acoustic emission positioning and other technologies, provide a means to realize the change characteristics of the internal structure of the rock mass during the dynamic shear fracture process. Rock ultrasonic imaging is a method of obtaining the data inside the rock mass through ultrasonic testing, reconstructing the internal image of the rock mass based on this data, and interpreting the internal situation according to the difference of the sound velocity value on the image; the acoustic emission signal is calculated by the acoustic emission count, signal energy, Acoustic emission amplitude and other parameters and waveform characteristics can be used to invert the internal structure change characteristics of the rock mass, and locate the initiation of rock mass cracks. Through theoretical research and related mathematical analysis methods, rich information such as acoustic emission parameters and waveforms can be analyzed. Describe, get the essence of rock mass rupture;

At present, most of the existing rock mass dynamic shearing equipment is static or quasi-static experimental equipment for direct shearing, and a few rock mass dynamic shearing equipment is impact shearing, which cannot realize the loading of variable frequency and variable amplitude cyclic loads, and most of the equipment does not have Considering the influence of low temperature on the shear failure characteristics of rock mass and using acoustic physical means to realize the acoustic physical imaging in the process of rock mass shear failure, it is impossible to simulate and test the dynamic shear characteristics of jointed rocks under various working conditions in actual engineering. To reveal the internal crack propagation mechanism in the process of rock mass damage and fracture, it is very important to develop a low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical testing machine.

SUMMARY OF THE INVENTION

In view of the above-mentioned problems, the present invention aims to provide a low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical test system and test method. Fatigue cyclic shear test, simultaneous acoustic emission and ultrasonic tests, can invert the source mechanism of the rock mass in the process of shear fracture, and can also perform acoustic imaging of the deterioration of the mesostructure in the process of rock mass deformation and fracture. , adjustable amplitude, can carry out acoustic emission and ultrasonic testing at the same time, invert the focal mechanism in the process of rock mass shearing and fracture, and carry out acoustic imaging of the deterioration of the mesoscopic structure in the process of rock mass deformation and fracture.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

Low temperature rock mass variable frequency variable amplitude dynamic shear acoustic physics test system, including low temperature control subsystem, dynamic shear subsystem, acoustic physics test subsystem and measurement and control subsystem;

The low temperature control subsystem includes an environmental box, a refrigeration pipe and a temperature control collection box, the environmental box is arranged in the frame of the main frame, and is connected to the temperature control acquisition box through the refrigeration pipe;

The dynamic shearing subsystem is arranged in the environmental box, including an oil source, a vertical loading mechanism, a transverse shearing mechanism, a shearing box and a rock mass sample, and the oil source is connected to the vertical loading mechanism and the transverse The shearing mechanism is connected, and the shearing box is arranged between the vertical loading mechanism and the transverse shearing mechanism;

The acoustic physics testing subsystem includes an ultrasonic imaging system and an acoustic emission positioning system arranged on the shear box;

The measurement and control subsystem includes a displacement measurement system and a data control acquisition computing imaging system.

Preferably, the vertical loading mechanism includes a vertical connecting plate, a vertical pressure head, a piston and a cylinder, the cylinder is mounted on the main frame through a vertical oil cylinder support ring, and is connected to the oil pipe, the piston The cylinder head is movably installed in the inner cavity of the cylinder through the vertical oil cylinder, and the vertical pressure plate installed at the lower end of the piston is connected with the vertical pressure head through the vertical connecting plate and the vertical connecting column, and the lower end of the vertical pressure head is connected with the vertical pressure head. An upper pressing plate is provided, and the upper pressing plate is used in cooperation with the rock mass sample.

Preferably, the transverse shearing mechanism includes a horizontal oil cylinder support ring, a horizontal oil cylinder head, a horizontal connecting column, a horizontal pressure head and a horizontal reaction force assembly, and the cylinder barrel is mounted on the main frame through the horizontal oil cylinder support ring, and Connected with the oil pipe, the piston is movably installed in the inner cavity of the cylinder through the horizontal oil cylinder cover, and the horizontal pressure plate installed at the end of the piston is connected with the horizontal pressure head through the horizontal connecting plate and the horizontal connecting column. Used in conjunction with a shear box; the horizontal reaction force assembly includes a horizontal quilt rod, a rod indenter and a reaction force rod, the horizontal quilt rod is connected with the main frame through a circular nut, and the reaction force rod is connected to the horizontal quilt rod connected, the rod indenter is arranged at the end of the reaction rod and used in cooperation with the shear box.

Preferably, the shearing box includes an upper shearing box and a lower shearing box that are used in cooperation with each other, and a guide bar is provided between the upper shearing box and the lower shearing box, and the upper shearing box and the lower shearing box are The shear box includes a connecting plate, a side plate, a shearing jaw and a main push plate. The side plates are symmetrically arranged on both sides of the connecting plate and the main push plate, and are connected to the connecting plate and the main push plate by connecting bolts. The cutting jaw is arranged on the inner side of the main push plate, and a cavity for placing the rock mass sample is formed on the inner side of the cutting jaw. The main push plate is used in cooperation with the transverse shearing mechanism, and the guide strip is arranged on the side plate In the guide groove of the lower shear box, the lower side of the lower shear box is also provided with a sliding mechanism; and the connecting plate, the side plate, the shearing jaw and the main push plate are all provided with installation round openings of a fixed size.

Preferably, the sliding mechanism includes a bottom plate, a roller frame, a roller frame connecting pad and a plurality of pad blocks, the bottom plate is arranged on the lower side of the lower shear box, and is movably engaged with the upper side of the roller frame, along the The stick on the roller frame slides, and the roller frame is connected to the upper cushion block through the stick frame connection cushion block. The cushion block is provided with several blocks, and each cushion block is connected by pins. It is connected with the frame of the main frame through the backing plate of the small courtyard.

Preferably, the ultrasonic imaging subsystem includes a plurality of ultrasonic probes and a sound wave controller, the ultrasonic probes are installed on the side plates on both sides of the upper shear box and the lower shear box and the middle of the connecting plate, and the ultrasonic probe and the sound wave The sensors in the controller are connected, and the acoustic wave controller can receive the ultrasonic signal and realize the ultrasonic imaging of the internal structure of the rock mass in the computer through the calculation software.

Preferably, the acoustic emission positioning subsystem includes an acoustic emission probe and an acoustic emission controller, the acoustic emission probe is located on the side panels on both sides of the upper shear box and the lower shear box, and the acoustic emission probe is connected to the acoustic emission probe. The sensors in the emission controller are connected, and the acoustic emission controller can receive the acoustic emission signal and realize the acoustic emission localization imaging of the internal structure of the rock mass in the computer through calculation software.

Preferably, the data control acquisition computing imaging subsystem includes a loading oil source controller and a computer, and the sensors in the loading oil source controller, the acoustic wave controller and the acoustic emission controller are all connected to the computer, which can realize loading and unloading. The automatic control of the system and the reading of data, and after processing by the analysis software, can realize ultrasonic imaging and acoustic emission localization imaging.

Preferably, the displacement measurement subsystem includes a horizontal shear displacement measurement mechanism and a vertical vertical compression displacement measurement mechanism, and both the horizontal shear displacement measurement mechanism and the vertical vertical compression displacement measurement mechanism include a grating ruler, a sensor bracket , bracket, adjusting rod and contact piece, the bracket of the vertical vertical compression displacement measuring mechanism is connected with the upper pressure plate through the connecting bolt, and the bracket of the horizontal shear displacement measuring mechanism is connected with the connecting plate of the lower shear box through the connecting bolt, so The adjusting rod is threadedly connected with the bracket, and a knob is provided at the end of the adjusting rod, the contact piece is arranged on the adjusting rod, and the grating ruler of the vertical vertical compression displacement measuring mechanism is connected to the roller through the sensor bracket and the connecting bolt. It is connected to the frame and used in conjunction with the contact piece of the corresponding vertical and vertical compression displacement measuring mechanism. It is used in conjunction with the contact piece of the shear displacement measuring mechanism.

Test method for low temperature rock mass variable frequency variable amplitude dynamic shear acoustic physics test system, including steps

S1. Put the rock mass sample into the shear box, adjust the knob to make the grating scale contact with the contact piece and give the grating scale appropriate pressure, and then close the environmental chamber door;

S2. Connect the acoustic emission probe and the ultrasonic probe, and stick to the rock sample, start the acoustic wave controller, the acoustic emission controller and the computer, and test the patency and effective signal of the line;

S3. Start the temperature control collection box, set a certain low temperature in the environmental box and start the refrigeration cycle; realize the real-time freezing and thawing, freezing and thawing of the rock, and the temperature and the number of freezing and thawing in the environmental box can be automatically controlled;

S4. Start the dynamic shear testing machine, load the oil source controller, and test the disturbance force signal;

S5. Set the loading frequency, the loading amplitude and the number of cycles for the testing machine through the loading control software of the computer, and clear the displacement data measured by the grating ruler to zero. After the temperature in the environmental box reaches the set value, the ultrasonic wave is emitted to start loading;

S6. During the loading process, the measurement and control system is used to collect data on the load, displacement, ultrasonic signal, and acoustic emission signal, and observe the change of the shear stress and strain curve during the loading process;

S7. When the rock mass sample is damaged, stop loading;

S8. Close the temperature control collection box, open the door of the environmental box, take out the damaged rock mass sample after the temperature in the environmental box reaches room temperature, and close the low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physics test system.

The beneficial effects of the present invention are as follows: the present invention discloses a low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical testing machine and a test method. Compared with the prior art, the improvements of the present invention are:

(1) The present invention designs a low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical testing machine and test method. Through the design of the frame system and the environmental box, the testing machine realizes the complex disturbance stress waveform under the condition of variable frequency and variable amplitude. Power loading, servo control and response, can carry out precise servo control and high-speed servo response to the two servo valves of the main oil cylinder and the shearing oil cylinder during the fatigue shearing process;

(2) At the same time, the low temperature control system can realize the simulation of complex environments such as low temperature and freeze-thaw cycles of rock mass, and truly restore the dynamic shear mechanical properties of rock mass under the actual engineering situation. The transparent and high-strength environmental box door can not only Keeping the closed state of the environmental box can also observe the shape of the rock mass sample in real time and safely during the shearing process;

(3) The design of the acoustic physics test system can realize ultrasonic imaging and acoustic emission localization imaging, and can reveal the internal structure change characteristics of the rock mass during the dynamic shear fracture process;

(4) The testing machine adopts the grating scale displacement sensor to solve the problem of high-resolution dynamic measurement of rock sample deformation during dynamic loading. At the same time, the grating scale displacement sensor has the advantages of greater range than high precision, which can realize dynamic measurement, and is easy to realize measurement and data processing. During the experiment, it has adjustable frequency and amplitude, and can perform acoustic emission and ultrasonic tests at the same time. The degradation of the advantages of sonic imaging.

Description of drawings

FIG. 1 is a schematic structural diagram of the entire system of the low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical test system of the present invention.

FIG. 2 is a front view of the whole system structure of the low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physics test system of the present invention.

3 is a front view of the structure of the dynamic shear testing machine of the present invention.

Figure 4 is a cross-sectional view of the structure of the dynamic shear testing machine of the present invention.

FIG. 5 is a schematic structural diagram of the shear box of the present invention.

FIG. 6 is a schematic structural diagram of the acoustic physics test subsystem of the present invention.

FIG. 7 is a schematic structural diagram of the sliding mechanism of the present invention.

FIG. 8 is a front view of the displacement measurement subsystem of the present invention.

Figure 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.

Among them: 1. Oil source; 2. Oil source control line; 3. Oil pipe; 4. Main frame; 5. Vertical cylinder head; 6. Vertical cylinder support ring; 7. Vertical pressure plate; 8. Vertical connection 9. Vertical indenter; 10. Upper platen; 11. Upper shear box; 12. Lower shear box; 13. Environmental box; 14. Upper stick; ; 17. Small courtyard backing plate; 18. Grating ruler; 19. Horizontal pressure head; 20. Horizontal connection plate; 21. Horizontal pressure plate; 22. Refrigeration pipe; 23. Horizontal quilt; 24. Temperature control box; ; 26. Loading oil source controller; 27. Sound wave controller; 28. Sound emission controller; 29. Sound wave control line; 30. Sound emission control line; Knob; 34. Contact sheet; 35. Adjusting rod; 36. Bracket; 37. Acoustic emission probe; 38. Ultrasonic probe; 39. Bottom plate; 40. Guide strip; 41. Sensor bracket; 42. Horizontal cylinder cover; 43. Horizontal cylinder support ring; 44. Piston; 45. Stick; 46. Roller frame; 47. Horizontal connecting column; 48. Cylinder barrel; 49. Vertical connecting column; 50. Cutting jaw; 51. Main push plate; 52. Rock mass sample; 53. Side plate; 54. Connecting plate.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention are further described below with reference to the accompanying drawings and embodiments.

Referring to the low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physics test system shown in Figures 1-10, it includes a low temperature control subsystem, a dynamic shear subsystem, an acoustic physics test subsystem and a measurement and control subsystem;

The low temperature control subsystem includes an environmental box 13, a refrigeration pipe 22 and a temperature control acquisition box 24. The environmental box 13 is arranged in the main frame 4 and is connected to the temperature control acquisition box 24 through the refrigeration pipe 22. Control the collection box 24 to transmit cold airflow through the refrigeration pipe 22, thereby controlling the temperature in the environmental box 13;

The dynamic shearing subsystem is arranged in the environmental box 13, and includes an oil source 1, a vertical loading mechanism, a transverse shearing mechanism, a shear box and a rock mass sample 52. It is connected to the loading mechanism and the transverse shearing mechanism, and provides loading pressure to the vertical loading mechanism and the transverse shearing mechanism. The shear box is arranged between the vertical loading mechanism and the transverse shearing mechanism, and is used for rock mass samples. 52 to be fixed;

The acoustic physics testing subsystem includes an ultrasonic imaging system and an acoustic emission positioning system arranged on the shear box;

The measurement and control subsystem includes a displacement measurement system and a data control acquisition computing imaging system.

Preferably, as shown in Figures 3 to 4, the dynamic testing machine adopts the combination of the vertical loading subsystem and the transverse shearing subsystem to realize the complex disturbance of the rock mass sample 52 in the shear box under the condition of variable frequency and amplitude. Dynamic loading of stress waveform; wherein the vertical loading mechanism includes a vertical connecting plate 8, a vertical pressure head 9, a piston 44 and a cylinder 48, and the cylinder 48 is mounted on the main frame 4 through the vertical oil cylinder support ring 6 and connected with the oil pipe 3, the piston 44 is movably installed in the inner cavity of the cylinder 48 through the vertical oil cylinder cover 5, and the vertical pressure plate 7 installed on the lower end of the piston 44 passes through the vertical connecting plate 8, the vertical The connecting column 49 and the hexagonal bolts are connected to the vertical indenter 9, and the lower end of the vertical indenter 9 is provided with an upper pressure plate 10, which is used in cooperation with the rock mass sample 52, that is, when the rock mass sample is subjected to 52 during the axial pressurization process, the oil source 1 pumps hydraulic oil into the cylinder 48 through the oil pipe 3, and with the increase of the oil pressure in the cylinder 48, the piston 44 is pushed down to transmit the axial pressure, and the axial load passes through the cylinder 48. The vertical pressure plate 7 is conducted to the vertical pressure head 9 and then conducted downward on the lower pressure plate 10, and the lower pressure plate 10 is used to apply axial pressure to the rock mass sample 52;

The transverse shearing mechanism includes a horizontal oil cylinder support ring 43, a horizontal oil cylinder head 42, a horizontal connecting column 47, a horizontal pressure head 49 and a horizontal reaction force assembly, and the cylinder barrel 48 is installed on the main frame 4 through the horizontal oil cylinder support ring 43. and connected with the oil pipe 3, the piston 44 is movably installed in the inner cavity of the cylinder 48 through the horizontal oil cylinder cover 42, and the horizontal pressure plate 21 installed at the end of the piston 44 passes through the horizontal connecting plate 20 and the horizontal connecting column 47. The hexagonal bolt is connected with the horizontal pressure head 19, and the horizontal pressure head 19 is used in conjunction with the shear box, that is, when in use, the oil source 1 pumps the hydraulic oil into the cylinder barrel 48 through the oil pipe 3, and the hydraulic oil is pumped into the cylinder barrel 48 through the oil pipe 3. The increase of oil pressure pushes the piston 44 to apply shear load in the horizontal direction, the horizontal load is transmitted to the horizontal indenter 19 through the horizontal platen 21, and the horizontal indenter 19 is used to apply the shear load in the horizontal direction to the lower box body 12 of the shear box; The horizontal reaction force assembly includes a horizontal rod 23, a rod press head 31 and a reaction rod 32, the horizontal rod 23 is connected to the main frame 4 through a circular nut, and the reaction rod 32 is connected to the horizontal rod 23. Connection, the rod pressing head 31 is arranged at the end of the reaction force rod 32, and is used in cooperation with the upper box body 11 of the shear box to exert a reverse force on the upper box body 11.

Preferably, as shown in FIG. 5 , the shearing box includes an upper shearing box 11 and a lower shearing box 12 that are used in cooperation with each other, and a guide is provided between the upper shearing box 11 and the lower shearing box 12 Strip 40, the upper shearing box 11 and the lower shearing box 12 each include a connecting plate 54, a side plate 53, a cutting jaw 50 and a main push plate 51, the side plates 53 are symmetrically arranged on the connecting plate 54 and the main push plate 51 on both sides, and are connected with the connecting plate 54 and the main push plate 51 by connecting bolts to form a square box structure. The cavity for placing the rock mass sample 52, the main push plate 51 is used in conjunction with the transverse shearing mechanism, that is, when in use, the horizontal indenter 19 applies a horizontal shear load to the lower box body 12, and is The rod pressing head 31 exerts a reverse force on the upper box body 11; and when the external force is applied, the frictional resistance between the upper box body 11 and the lower box body 12 is reduced, and the guide bar 40 is arranged in the guide groove on the side plate 53 Inside, the rock mass sample 52 is sheared by the horizontal shearing force and reaction force acting on the lower shearing box 12 and the upper shearing box 11 during use, in order to avoid the influence of the frictional force at the lower part of the lower shearing box 12 The shearing precision during the shearing process is further provided with a sliding mechanism on the lower side of the lower shearing box 12 .

Preferably, the sliding mechanism includes a bottom plate 39 , a roller frame 46 , a roller frame connecting pad 15 and a plurality of pad blocks 16 , the bottom plate 39 is arranged on the lower side of the lower shear box 12 , and is inserted through the sliding rail slot. The roller frame 46 is movably engaged with the upper side of the roller frame 46. The roller frame 46 is equipped with a stick 45 through the rotation of the upper stick 14. The lower side of the bottom plate 39 is also in close contact with the stick 45. Under the action of shearing force, Sliding left and right along the stick 45 , the roller frame 46 is connected with the upper pad 16 through the stick frame connecting pad 15 to fix the roller frame 46 , the pad 16 is provided with several pieces, and each pad 16 is between They are all connected by pins, and the bottom block 16 is connected to the main frame 4 through a small backing plate 17 to support the upper loading mechanism.

Preferably, the connecting plate 54 , the side plate 53 , the cutting jaw 50 and the main push plate 51 are all provided with installation round openings of a fixed size, which is conducive to realizing ultrasonic imaging and harmonic emission of rock mass rupture during the dynamic shearing process. Positioning; the ultrasonic imaging subsystem includes six ultrasonic probes 38 and a sound wave controller 27, and the six ultrasonic probes 38 are installed in the middle of the side plate 53 and the connecting plate 54 on both sides of the upper shear box 11 and the lower shear box 13 , and the ultrasonic probe 38 is connected to the sensor in the acoustic wave controller 27, and the acoustic wave controller 27 can receive the ultrasonic signal and realize the ultrasonic imaging of the internal structure of the rock mass in the computer through the calculation software.

Preferably, the acoustic emission positioning subsystem includes twelve acoustic emission probes 37 and an acoustic emission controller 28 , and the acoustic emission probes 37 are located on the side panels on both sides of the upper shearing box 11 and the lower shearing box 12 53, and the acoustic emission probe 37 is connected to the sensor in the acoustic emission controller 28, the acoustic emission controller 28 can receive the acoustic emission signal and realize the acoustic emission localization imaging of the internal structure of the rock mass in the computer through the calculation software.

Preferably, the data control acquisition computing imaging subsystem includes a loading oil source controller 26 and a computer 25, and the sensors in the loading oil source controller 26, the acoustic wave controller 27 and the acoustic emission controller 28 are all connected to the computer 25 is connected, and the automatic control of the loading system and the reading of data can be realized through the control of the computer 25, and ultrasonic imaging and acoustic emission localization imaging can be realized after being processed by the analysis software.

Preferably, the displacement measurement subsystem includes a horizontal shear displacement measurement mechanism and a vertical vertical compression displacement measurement mechanism, and both the horizontal shear displacement measurement mechanism and the vertical vertical compression displacement measurement mechanism include a grating ruler 18, a sensor support The frame 41, the support 36, the adjusting rod 35, the knob 33 and the contact piece 34, the support 36 of the vertical vertical compression displacement measuring mechanism is connected with the upper pressure plate 10 through the connecting bolt, and the support 36 of the horizontal shear displacement measuring mechanism is connected with the connecting bolt Connected with the connecting plate 54 of the lower shear box 12, the adjusting rod 35 is threadedly connected to the bracket 36, and a knob 33 is provided at the end of the adjusting rod 35 for adjusting the relative distance between the adjusting rod 35 and the bracket 36, The contact piece 34 is arranged on the adjusting rod 35, and the grating ruler 18 of the vertical vertical compression displacement measuring mechanism is connected with the roller frame 46 through the sensor bracket 41 and the connecting bolt, and is measured with the corresponding vertical vertical compression displacement. The contact piece 34 of the mechanism is used in conjunction, and the grating ruler 18 of the horizontal shear displacement measuring mechanism is connected with the rod indenter 31 through the sensor bracket 41 and the connecting bolt, and is connected with the corresponding contact piece 34 of the horizontal shear displacement measuring mechanism. Used together; that is, during use, when measuring the vertical vertical compression displacement of the rock mass sample 52, the grating ruler 18 on the sensor bracket 41 of the vertical vertical compression displacement measuring mechanism first contacts the contact piece 34 and is under pressure In the state, the bracket 36 is fixed on the upper pressing plate 10. When the rock mass sample 52 is compressed, the upper pressing plate 10 drives the adjusting rod 35 and the contact piece 34 to move downward, so that the reading head of the grating ruler 18 relaxes and measures the vertical displacement; When measuring the horizontal shear displacement, the grating ruler 18 on the sensor bracket 41 of the horizontal shear displacement measuring mechanism is first in contact with the contact piece 34 and is in a compressed state. When the rock mass sample 52 produces shear slip, the lower shear The cutting box 12 drives the adjusting rod 35 and the contact piece 34 to displace in the direction of the reaction rod 32 , and the reading head of the grating ruler 18 relaxes with the movement of the contact piece 34 to measure the horizontal shear displacement.

Preferably, in the technical solution provided by the embodiment of the present invention, in order to facilitate observation, the environmental box door is made of a transparent material with a certain strength, which can realize the sealing of the cooling cycle of the environmental box 13 and at the same time, it can also protect the interior of the dynamic shear testing machine. Observing the test process, selecting a suitable coolant can ensure that the minimum temperature inside the environmental box 13 reaches minus 65°C when the test machine is working normally.

Preferably, the rock mass sample 52 may be a complete rock mass, a non-penetrating fractured rock mass, or a penetrating fractured rock mass.

Preferably, the loading frequency range of the dynamic shear testing machine is 0-10 Hz, and the loading range of vertical load and horizontal load is 0-1000t.

Preferably, the size of the shear box can be 100mm×100mm×100mm or 100mm×100mm×200mm; when switching shear boxes of different sizes, the loading height of the rock mass sample 52 can be adjusted by adjusting the number of spacers 15 .

The test method of the low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical test system of the present invention comprises the following steps:

S1. Put the rock mass sample 52 into the shearing box, adjust the knob 33 to make the grating ruler 18 contact the contact piece 34 and give the grating ruler 18 proper pressure, and then close the environmental chamber door;

S2. Connect the acoustic emission probe and the ultrasonic probe, and stick it close to the rock sample, start the acoustic wave controller 27, the acoustic emission controller 28 and the computer 25, and test the patency and effective signal of the line;

S3. Start the temperature control collection box 24, set a certain low temperature in the environmental box and start the refrigeration cycle; realize the real-time freezing and thawing, freezing and thawing of the rock, and the temperature and the number of freezing and thawing in the environmental box can be automatically controlled;

S4. Start the dynamic shear testing machine, load the oil source controller 26, and test the disturbance force signal;

S5. Set the loading frequency, the loading amplitude and the number of cycles for the testing machine through the loading control software of the computer 25, and clear the displacement data measured by the grating ruler 18 until the temperature in the environmental box 13 reaches the set value. Send ultrasonic waves and start loading;

S6. During the loading process, the measurement and control system is used to collect data on the load, displacement, ultrasonic signal, and acoustic emission signal, and observe the change of the shear stress-strain curve during the loading process;

S7. When the rock mass sample 52 is damaged, stop loading;

S8. Close the temperature control collection box 24, open the environmental box door, take out the damaged rock mass sample 52 after the temperature in the environmental box 13 reaches room temperature, and close the low temperature rock mass variable frequency variable amplitude dynamic shear acoustic physics test system.

The above-mentioned low-temperature rock mass variable frequency variable amplitude dynamic shear acoustic physical test system according to the present invention has the following advantages:

(1) The test system of the present invention can not only meet the requirements of most test scales, but also can realize variable frequency and variable amplitude loading through dynamic shear system, low temperature control system, acoustic physical test system, measurement and control system, and can consider low temperature Influence on the shear failure characteristics of rock mass and the use of acoustic physical means to achieve acoustic physical imaging in the process of rock mass shear failure, it can simulate and test the dynamic shear characteristics of jointed rocks under various working conditions in engineering practice and reveal the rock mass. The internal crack propagation mechanism in the process of damage and rupture enriches the data obtained from the test and improves the test quality;

2. The test system of the present invention uses the ultrasonic imaging technology and the acoustic emission positioning imaging technology in the acoustic physical test system, which can locate the initiation of cracks in the rock mass sample during the loading process, and can reveal the rock mass in the process of dynamic shear fracture. Changes in the internal structure of the body;

3. According to the above-mentioned specific embodiments, the testing machine of the test system of the present invention adopts strain gauges and strain gauges to measure the deformation of the sample under dynamic disturbance, and the methods for measuring the deformation of the strain gauges are on the rock sample point or on the surface. On the average of the upper deformation, the measurement results are closely related to the strain measurement position, and the volume strain calculated in turn is also local. Our invention uses a grating scale displacement sensor to measure the deformation of the rock sample during the dynamic shearing process, which solves the problem of high-resolution dynamic measurement of rock sample deformation during dynamic loading. The advantage is that it can realize dynamic measurement, and it is easy to realize the automation of measurement and data processing.

The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above-mentioned embodiments, and the descriptions in the above-mentioned embodiments and the description are only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have Various changes and modifications fall within the scope of the claimed invention. The claimed scope of the present invention is defined by the appended claims and their equivalents.

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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