Coal rock three-axis ultrasonic measuring device capable of adjusting prestress

Abstract

The utility model discloses a coal rock triaxial ultrasonic measuring device capable of adjusting prestress. A test piece fixing mechanism is used for fixing a coal rock sample; the prestress adjusting device comprises two prestress applying mechanisms which are coaxial and symmetrically arranged on the two sides of the coal rock sample, an air cylinder of one prestress applying mechanism is provided with a three-way air pressure valve used for pressurizing pressure applying cavities of the two air cylinders, and pistons of the two air cylinders drive ultrasonic transducers to synchronously apply prestress to the two coaxial sides of the coal rock sample. The ultrasonic transceiver is used for sending an ultrasonic excitation signal to one ultrasonic transducer which is coaxial with the ultrasonic transceiver, and the other ultrasonic transducer receives the ultrasonic signal and feeds back the ultrasonic signal to the ultrasonic transceiver so as to obtain ultrasonic data of the coal rock sample; therefore, prestress in different directions can be applied to the coal and rock mass and can be adjusted, ultrasonic data of the coal and rock mass under different conditions can be obtained, and data support is provided for subsequent determination of ultrasonic signal rules in the coal and rock.

Description

Technical Field

[0001] This utility model belongs to the field of coal and rock mass detection technology, specifically a coal and rock triaxial ultrasonic measuring device with adjustable prestress. Background Technology

[0002] Currently, ultrasonic measurement is widely used in mining engineering for geological exploration, rock mechanics, underground space monitoring, and non-destructive testing. By measuring parameters such as the propagation speed and attenuation of ultrasonic waves in underground rock strata, geologists can infer the properties of underground rocks, such as density, porosity, and toughness. This helps determine the type and reserves of mineral deposits. Ultrasonic waves are used to study the mechanical properties of rocks, including their elastic modulus, Poisson's ratio, and the presence of cracks and fissures. This information is crucial for understanding the stability, tensile strength, and behavior of rocks in mining or tunnel engineering. Underground space monitoring: In underground mines or tunnels, ultrasonic waves can be used to monitor the stability of geological bodies and potential geological hazards, such as rock slippage and rock mass collapse. Regular ultrasonic measurements can help detect potential problems early and implement appropriate safety measures. Non-destructive testing: Ultrasonic waves are also used in mining for non-destructive testing. For example, ultrasonic measurements can be used to detect cracks, pores, or other defects in ore, helping to assess the integrity and mineability of the rock.

[0003] The key to analyzing the internal stress of coal and rock using ultrasonic signals lies in understanding the internal ultrasonic signals of coal and rock under different prestresses. By analyzing the measured ultrasonic signals, the internal stress of the coal and rock can be deduced. However, the patterns of ultrasonic signals inside coal and rock under prestress in different directions are currently unknown. The biggest hardware bottleneck in obtaining these patterns is the lack of a dedicated device for ultrasonic measurement of coal and rock that can adjust the prestress in different directions. Although some devices exist that can perform triaxial loading of coal and rock stress, they are not suitable for ultrasonic testing of coal and rock masses, and their implementation is complex and not convenient for rapid operation.

[0004] Therefore, the research direction required by this invention is to provide a new device that can apply prestress to coal and rock mass in different directions with adjustable magnitude, thereby obtaining ultrasonic data of coal and rock mass under different conditions, and providing data support for subsequent determination of the ultrasonic signal law inside coal and rock mass. Utility Model Content

[0005] To address the problems existing in the prior art, this utility model provides a triaxial ultrasonic measuring device for coal and rock with adjustable prestress. It can apply prestress to the coal and rock mass in different directions and the magnitude can be adjusted, thereby obtaining ultrasonic data of the coal and rock mass under different conditions, providing data support for subsequent determination of the ultrasonic signal patterns inside the coal and rock. Moreover, it is quick to install, easy to operate, and convenient to promote and use.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is: a triaxial ultrasonic measuring device for coal and rock with adjustable prestress, comprising a fixed frame, a specimen fixing mechanism, a prestress adjustment device, and an ultrasonic transceiver.

[0007] The specimen fixing mechanism includes multiple specimen fixers and multiple telescopic rods. Each specimen fixer is connected to one end of a telescopic rod, and the other end of each telescopic rod is hinged to the fixing frame. By adjusting the length of each telescopic rod, the specimen fixers are made to contact each other to form a specimen placement space, which is used to fix the coal and rock specimens.

[0008] The prestress adjustment device includes two coaxial and symmetrically arranged prestress application mechanisms on both sides of the coal and rock sample. Each prestress application mechanism includes an air cylinder, a piston, a sliding connecting rod, an ultrasonic transducer, and an air pipe. The air cylinder is fixed on a fixed frame, and the piston is installed inside the air cylinder and slides and seals against the inner wall of the air cylinder. The piston divides the inside of the air cylinder into a pressure chamber and a reset chamber. One end of the sliding connecting rod extends into the reset chamber and is connected to the piston, and the other end is connected to the ultrasonic transducer. The pressure chambers of the two prestress application mechanism air cylinders are connected through the air pipe. A three-way air pressure valve is opened on the outside of the pressure chamber of one of the prestress application mechanism air cylinders, which is connected to an external air pump for pressurizing the pressure chambers of the two air cylinders, so that the pistons of each air cylinder drive the ultrasonic transducers to apply prestress synchronously to both sides of the coal and rock sample on the same axis.

[0009] The ultrasonic transceiver is connected to each ultrasonic transducer via signal connection lines. It is used to send ultrasonic excitation signals to one ultrasonic transducer that is coaxial, and the other ultrasonic transducer receives the ultrasonic signals and feeds them back to the ultrasonic transceiver, so as to acquire ultrasonic data of coal and rock samples.

[0010] Furthermore, the fixed frame is a steel frame support structure composed of multiple steel rods. This structure ensures the stability of the entire device when pressure is applied.

[0011] Furthermore, the number of specimen holders and telescopic rods is four, and the coal and rock specimen is cylindrical. Each specimen holder includes two quarter-circle arc plates, fixedly connected by a connecting plate. One end of each telescopic rod is hinged to the connecting plate, and the other end is hinged to the fixed frame. When the four telescopic rods reach their maximum extension, the four specimen holders contact each other to form two parallel rings for holding the cylindrical coal and rock specimen. This structure satisfies the need for fixing the cylindrical coal and rock specimen, facilitating subsequent prestressing and ultrasonic testing.

[0012] Furthermore, there are three prestress adjustment devices, and the axes of the three prestress adjustment devices are perpendicular to each other.

[0013] Furthermore, the prestress adjustment device also includes a barometer, which is mounted on one of the air cylinders and connected to its pressure chamber, for monitoring the real-time air pressure during pressure application.

[0014] Furthermore, one end of the air cylinder is equipped with a detachable air cylinder cap, which is sealed to the air cylinder. This design facilitates the inspection or replacement of the internal piston, thereby improving the overall service life of the device.

[0015] Furthermore, a guide ring is installed where the sliding connecting rod passes through the air cylinder. Adding a guide ring at this location guides the movement direction of the sliding connecting rod while minimizing friction between them, ensuring that the sliding connecting rod extends or retracts as the piston moves.

[0016] Furthermore, a rubber sealing ring is installed on the outer edge of the piston. The addition of the rubber sealing ring can further ensure the sealing effect of the piston during sliding, ensure the gas isolation effect between the pressure chamber and the reset chamber, and thus ensure the accuracy of subsequent prestressing application to the coal and rock samples.

[0017] Compared with existing technologies, this invention employs a combination of a fixed frame, a specimen fixing mechanism, a prestress adjustment device, and an ultrasonic transceiver. The specimen fixing mechanism is used to fix the cylindrical coal and rock specimen. The three prestress adjustment devices can apply prestress to the coal and rock specimen from three mutually perpendicular directions, and each can be independently controlled to achieve pressure control of different prestresses in different directions. The ultrasonic transceiver can acquire ultrasonic data of the coal and rock specimen in different directions when it receives prestresses of different magnitudes. By adjusting the magnitude of the prestress in each direction, ultrasonic data can be continuously and repeatedly acquired, thereby studying the relationship between the changes in ultrasonic signals of coal and rock under different directions and magnitudes of prestress, providing data support for subsequent determination of the ultrasonic signal patterns inside the coal and rock. In addition, the entire device is quick to install, easy to operate, and convenient for widespread use. Attached Figure Description

[0018] Figure 1 This is the front view of this utility model;

[0019] Figure 2 yes Figure 1 The left view;

[0020] Figure 3 yes Figure 1 Top view;

[0021] Figure 4 This is a three-dimensional structural diagram of the present invention;

[0022] Figure 5 This is a schematic diagram of the disassembled parts of this utility model;

[0023] Figure 6 This is a schematic diagram of the working state of this utility model.

[0024] In the diagram: 1. Three-way pressure valve, 2. Pressure gauge, 3. Air cylinder cover, 4. Air cylinder, 5. Guide ring, 6. Rubber sealing ring, 7. Piston, 8. Sliding connecting rod, 9. Ultrasonic transducer, 10. Air pipe, 11. Fixing frame, 12. Specimen holder, 13. Telescopic rod, 14. Air pump, 15. Signal connection line, 16. Ultrasonic transceiver, 17. Coal and rock sample. Detailed Implementation

[0025] The present invention will be further described below.

[0026] like Figures 1 to 4 As shown, this utility model includes a fixed frame 11, a specimen fixing mechanism, a prestress adjustment device, and an ultrasonic transceiver 16.

[0027] The specimen fixing mechanism includes multiple specimen holders 12 and multiple telescopic rods 13. Each specimen holder 12 is connected to one end of a telescopic rod 13, and the other end of each telescopic rod 13 is hinged to a fixing frame 11. By adjusting the length of each telescopic rod 13, the specimen holders 12 are brought into contact with each other to form a specimen placement space. This space is used to fix the coal and rock specimen 17. Figure 1 and 3As shown, the fixed frame 11 is a steel frame support structure composed of multiple steel rods. This structure ensures the stability of the entire device under pressure. There are four specimen holders 12 and four telescopic rods 13. The coal and rock sample 17 is cylindrical. The specimen holder 12 includes two quarter-circle arc plates, which are fixedly connected by a connecting plate. One end of the telescopic rod 13 is hinged to the connecting plate, and the other end is hinged to the fixed frame 11. When the four telescopic rods 13 reach their maximum extension, the four specimen holders 12 contact each other to form two parallel rings for placing the cylindrical coal and rock sample 17. This structure satisfies the need for fixing the cylindrical coal and rock sample 17, facilitating subsequent prestressing and ultrasonic testing of the sample.

[0028] The prestress adjustment device includes two coaxial and symmetrically arranged prestress application mechanisms on both sides of the coal and rock sample. Each prestress application mechanism includes an air cylinder 4, a piston 7, a sliding connecting rod 8, an ultrasonic transducer 9, and an air pipe 10. The air cylinder 4 is fixed on a fixed frame 11. The piston 7 is installed inside the air cylinder 4 and slides and seals against the inner wall of the air cylinder 4. The piston 7 divides the interior of the air cylinder 4 into a pressure chamber and a reset chamber. One end of the sliding connecting rod 8 extends into the reset chamber and connects to the piston 7, and the other end connects to the ultrasonic transducer 9. The air cylinders of the two prestress application mechanisms... The pressure chambers are connected via air pipes. A three-way pressure valve 1 is installed outside the pressure chamber of one of the prestressing mechanism air cylinders, connected to an external air pump 14. This valve pressurizes the pressure chambers of the two air cylinders 4, causing their respective pistons 7 to drive the ultrasonic transducers 9 to synchronously apply prestress to both coaxial sides of the coal and rock sample 17. The three-way pressure valve 1 has three ports, one of which is connected to the pressure chamber, and the other two ports are equipped with valves, one of which is connected to the air pump. There are three prestressing adjustment devices, each with its axis perpendicular to the others. Each prestressing adjustment device also includes a barometer 2, mounted on one of the air cylinders 4 and connected to its pressure chamber, used to monitor the real-time air pressure during pressure application.

[0029] The ultrasonic transceiver 16 is connected to each ultrasonic transducer 9 via signal connection lines. It is used to send ultrasonic excitation signals to one ultrasonic transducer 9 that is coaxial, and the other ultrasonic transducer 9 receives the ultrasonic signals and feeds them back to the ultrasonic transceiver 16, so as to acquire ultrasonic data of the coal and rock sample 17.

[0030] like Figure 5 As shown, as an improvement of this utility model, one end of the air cylinder 4 is equipped with a detachable air cylinder cover 3, which is sealed to the air cylinder 4. This arrangement facilitates the inspection or replacement of the internal piston 7, thereby improving the overall service life of the device.

[0031] As another improvement to this utility model, such as Figure 5As shown, a guide ring 5 is installed where the sliding connecting rod 8 passes through the air cylinder 4. The addition of the guide ring 5 at this position guides the movement direction of the sliding connecting rod 8 and reduces the friction between them, ensuring that the sliding connecting rod 8 extends or retracts with the piston 7. A rubber sealing ring 6 is installed on the outer edge of the piston 7. The addition of the rubber sealing ring 6 further ensures the sealing effect of the piston during sliding, ensuring the gas isolation effect between the pressure chamber and the reset chamber, thereby ensuring the accuracy of subsequent prestress application to the coal and rock sample 17.

[0032] The aforementioned three-way pressure valve 1, pressure gauge 2, air pump 14, ultrasonic transceiver 16, and ultrasonic transducer 9 are all existing components that can be directly purchased from the market. This utility model only utilizes their existing functions without modifying their structure. The telescopic rod 13 is a mechanical telescopic rod, consisting of an inner cylinder and an outer cylinder. The inner cylinder is placed inside the outer cylinder and can slide along it. The two are positioned by limit bolts. The overall length of the telescopic rod is adjusted by regulating the extension distance of the inner cylinder relative to the outer cylinder.

[0033] like Figure 6 As shown, the working process of this utility model is as follows:

[0034] Fixing stage: Loosen the limiting bolts of at least two telescopic rods 13, then pull up the corresponding specimen holder 12 and retract the corresponding telescopic rod 13, so that the cylindrical coal and rock specimen 17 is placed in the remaining unpulled specimen holder 12. Then, the pulled-up specimen holder 12 is reset by extending the telescopic rod 13, so that all four specimen holders 12 are in contact with the circumferential surface of the coal and rock specimen 17. Then, tighten the corresponding limiting bolts to fix the length of the telescopic rod 13, thereby ensuring that the coal and rock specimen 17 is fixed in the specimen placement space composed of the four specimen holders 12.

[0035] Pressurization Stage: Three ultrasonic transceivers 16 are deployed, each corresponding to a prestress adjustment device. The ultrasonic transceivers 16 are connected to two ultrasonic transducers 9 via signal connection lines. Then, three air pumps 14 are connected to the three-way air pressure valves 1 of the three prestress adjustment devices respectively. The prestress magnitudes in the three directions are set. At this time, each air pump 14 injects pressurized gas into the pressurizing chamber of the air cylinder of each prestress adjustment device. The piston 7 is then pressed and moves towards the reset chamber, thereby driving the ultrasonic transducer 9 to move towards the coal sample 17 and apply prestress pressure to the coal sample 17. The pressure gauge 2 is observed, and the pressurization is stopped when the required pressure is reached. The three-way air pressure valves 1 are then closed. At this time, the set prestress is applied to the coal sample 17 in the three directions respectively.

[0036] Ultrasonic measurement stage: Start the ultrasonic transceiver 16 to collect ultrasonic data in different directions under the stress condition. Subsequently, by changing the magnitude of the prestress in different directions, the ultrasonic data in different directions are repeatedly acquired to obtain the relationship between the changes in prestress in different directions and the changes in ultrasonic data inside the coal and rock sample 17, providing data support for determining the ultrasonic signal law inside the coal and rock. Finally, when it is necessary to stop the prestress loading, turn off the air pump 14 and open the remaining unconnected port valve of the three-way air pressure valve 1. The air pressure inside the pressure chamber is discharged to the outside through the three-way air pressure valve 1, thereby stopping the prestress loading.

[0037] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A coal rock triaxial ultrasonic measuring device with adjustable pre-stress, characterized in that, Includes a fixed frame, a specimen fixing mechanism, a prestress adjustment device, and an ultrasonic transceiver; The specimen fixing mechanism includes multiple specimen fixers and multiple telescopic rods. Each specimen fixer is connected to one end of a telescopic rod, and the other end of each telescopic rod is hinged to the fixing frame. By adjusting the length of each telescopic rod, the specimen fixers are made to contact each other to form a specimen placement space, which is used to fix the coal and rock specimens. The prestress adjustment device includes two coaxial and symmetrically arranged prestress application mechanisms on both sides of the coal and rock sample. Each prestress application mechanism includes an air cylinder, a piston, a sliding connecting rod, an ultrasonic transducer, and an air pipe. The air cylinder is fixed on a fixed frame, and the piston is installed inside the air cylinder and slides and seals against the inner wall of the air cylinder. The piston divides the inside of the air cylinder into a pressure chamber and a reset chamber. One end of the sliding connecting rod extends into the reset chamber and is connected to the piston, and the other end is connected to the ultrasonic transducer. The pressure chambers of the two prestress application mechanism air cylinders are connected through the air pipe. A three-way air pressure valve is opened on the outside of the pressure chamber of one of the prestress application mechanism air cylinders, which is connected to an external air pump for pressurizing the pressure chambers of the two air cylinders, so that the pistons of each air cylinder drive the ultrasonic transducers to apply prestress synchronously to both sides of the coal and rock sample on the same axis. The ultrasonic transceiver is connected to each ultrasonic transducer via signal connection lines. It is used to send ultrasonic excitation signals to one ultrasonic transducer that is coaxial, and the other ultrasonic transducer receives the ultrasonic signals and feeds them back to the ultrasonic transceiver, so as to acquire ultrasonic data of coal and rock samples.

2. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, The fixed frame is a steel frame support structure composed of multiple steel rods.

3. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, The number of specimen holders and telescopic rods is four. The coal and rock specimen is cylindrical. The specimen holder includes two quarter-circular arc plates, which are fixedly connected by a connecting plate. One end of the telescopic rod is hinged to the connecting plate and the other end is hinged to the fixed frame. When the four telescopic rods reach their maximum extension distance, the four specimen holders contact each other to form two parallel rings for placing the cylindrical coal and rock specimen.

4. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, There are three prestress adjustment devices, and the axes of the three prestress adjustment devices are perpendicular to each other.

5. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, The prestress adjustment device also includes a barometer, which is mounted on one of the air cylinders and connected to its pressure chamber, for monitoring the real-time air pressure during pressure application.

6. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, One end of the air cylinder is equipped with a detachable air cylinder cap, which is sealed to the air cylinder.

7. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, The sliding connecting rod is fitted with a guide ring where it passes through the air cylinder.

8. The coal rock triaxial ultrasonic wave measuring device with adjustable pre-stress according to claim 1, characterized in that, The piston is fitted with a rubber sealing ring on its outer edge.

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