Testing device and method for rock dynamic I-type fracture test

Abstract

The invention discloses a testing device and method for a rock dynamic I-type fracture test, and belongs to the technical field of detection of rocks and rock materials under dynamic loading in rock engineering, the testing device comprises a shell, and the inner wall of the shell is provided with a plurality of wire grooves; the sample is arranged in the shell; the end part of the incident rod penetrates through the shell and extends into the shell; the end part of the transmission rod penetrates through the shell and is matched with the incident rod to clamp a sample, and stress waves are transmitted to the sample; the telescopic assembly is arranged in the shell and corresponds to the sample so as to adjust the position of the sample; the plurality of acoustic emission sensor assemblies are arranged in the shell and are connected with the test sample so as to detect the test sample; the plurality of acoustic emission sensor assemblies are arranged in one-to-one correspondence with the plurality of wire slots; the acoustic emission sensor assembly is connected with the data acquisition line; and the data acquisition wire is arranged in the wire slot.

Description

Technical Field

[0001] The present invention belongs to the technical field of testing of rocks and rock-like materials under dynamic loading in rock engineering, and particularly relates to a testing device and method for dynamic mode I fracture tests of rocks. Background Art

[0002] Currently, the main method for testing the dynamic mode I fracture toughness of rock-like materials is to conduct dynamic loading tests on specimens using a split Hopkinson pressure bar, and to be equipped with corresponding detection devices. As a non-destructive testing technology, acoustic emission testing systems have been widely used in dynamic loading tests of rock-like materials.

[0003] During the test, acoustic emission probes are closely attached to the surface of the specimen through adhesives. In order to more accurately locate the positions where cracks and damages occur, multiple acoustic emission probes are usually pasted on the surface of the specimen. However, this practice increases the overall weight of the specimen, and the specimen may become unstable or tilt during the test, thus affecting the test results.

[0004] In addition, in dynamic mode I fracture tests, an acoustic emission system is usually used in combination with a crack extension meter. Since there are many connecting wires for both, the wires may come into contact with each other or be pulled off during the loading process, thereby causing the test to fail.

[0005] When using a traditional split Hopkinson pressure bar for dynamic mode I fracture tests, the acoustic emission probes pasted on the specimen are easily damaged by the impact of the pressure bar; as precision instruments, acoustic emission probes are expensive and complex to operate, so it is necessary to ensure their safety and reliability to extend their service life and maintain their stability in a normal working environment; the traditional fixing method may interfere with the signals of the acoustic emission sensors, thereby affecting the accuracy of the test data.

[0006] Based on the above technical problems, it is necessary to develop a testing device and method that can not only facilitate the use of the acoustic emission system, but also effectively protect the acoustic emission sensors and at the same time do not affect the test results, so as to provide a reliable test basis for theoretical analysis and numerical calculation. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a testing device and method for dynamic mode I fracture tests of rocks, and adopts the following technical solutions:

[0008] A testing device for dynamic mode I fracture tests of rocks, comprising:

[0009] A housing, the inner wall of the housing is provided with a plurality of wire grooves;

[0010] A specimen, the specimen is arranged inside the housing;

[0011] An incident rod, the end of which passes through the housing and extends into the housing;

[0012] A transmission rod, the end of which passes through the housing and cooperates with the incident rod to clamp the specimen and transmit stress waves to the specimen;

[0013] A telescopic assembly, which is arranged in the housing and corresponds to the specimen to adjust the position of the specimen;

[0014] A plurality of acoustic emission sensor assemblies, which are arranged in the housing and connected to the specimen to detect the specimen; the plurality of acoustic emission sensor assemblies are arranged in one-to-one correspondence with the plurality of wire grooves; the acoustic emission sensor assemblies are connected to data acquisition lines; the data acquisition lines are arranged in the wire grooves.

[0015] Further, the acoustic emission sensor assembly includes an acoustic emission sensor and an acoustic emission protective sleeve; the acoustic emission sensor is arranged in the housing and connected to the curved surface of the specimen; one end of the acoustic emission protective sleeve is connected to the inner wall of the housing, and the other end is fixedly sleeved on the end of the acoustic emission sensor away from the specimen.

[0016] Further, it further includes a crack growth gauge; the crack growth gauge is connected to one end of the specimen close to the incident rod and cooperates with the acoustic emission sensor to detect the specimen.

[0017] Further, there are 4 acoustic emission sensors, which are respectively set as the first acoustic emission sensor, the second acoustic emission sensor, the third acoustic emission sensor and the fourth acoustic emission sensor; the first acoustic emission sensor and the second acoustic emission sensor are arranged up and down and both extend along the radial direction of the specimen; the first acoustic emission sensor is inclined upward, and the second acoustic emission sensor is inclined downward; the third acoustic emission sensor and the fourth acoustic emission sensor are arranged up and down and both extend along the diameter direction of the specimen.

[0018] Further, the axis of symmetry of the specimen, the central axis of the incident rod and the central axis of the transmission rod are arranged on the same horizontal line.

[0019] Further, the telescopic assembly includes a telescopic bracket; the telescopic bracket is arranged in the housing; one end of the telescopic bracket is connected to the bottom of the housing, and the other end abuts against the specimen to adjust the height of the specimen.

[0020] Further, a test method for a test device for a rock dynamic type I fracture test is the test method for the test device for a rock dynamic type I fracture test as described in any one of the above, and the method includes the following steps:

[0021] S1. Fabricate a specimen: First, cut the original rock sample and drill a core. Process the rock into a straight-cut groove semi-circular disk bending specimen.

[0022] S2. Clamp the specimen between the incident bar and the transmission bar: Place the outer shell between the incident bar and the transmission bar. The incident bar passes through the prefabricated incident bar hole on the outer shell, and the transmission bar passes through the prefabricated transmission bar hole on the outer shell. Initially adjust the position of the specimen according to the position of the acoustic emission protective sleeve. Subsequently, clamp the specimen between the incident bar and the transmission bar, and apply an appropriate amount of lubricant to both end faces of the specimen to reduce the friction effect caused by the specimen and the end faces of the test bars.

[0023] S3. Paste acoustic emission sensors on the specimen and place them in the outer shell: Install the acoustic emission sensors into the acoustic emission protective sleeves. Use the positioning function of the acoustic emission protective sleeves to paste the acoustic emission sensors on the curved surface of the specimen, ensuring that the pasting position of the acoustic emission sensors remains consistent for each test. Constrain the data acquisition lines connected to the acoustic emission sensors through the wire grooves inside the outer shell. Place one data acquisition line in each wire groove, and then connect the data acquisition lines to the acoustic emission host for data acquisition and processing.

[0024] S4. Adjust the position of the specimen through the telescopic support: Place the specimen on the platform at the top of the telescopic support. Then adjust the height of the telescopic support to align the symmetry axis of the specimen with the central axes of the incident bar and the transmission bar, so that the central axis of the incident bar, the symmetry axis of the specimen, and the central axis of the transmission bar are on the same horizontal line.

[0025] S5. Apply an incident wave to the incident bar: After the safety warning to the tester, start the emission device. The tester records the first incident strain pulse received by the strain gauge on the incident bar and the reflected strain pulse after the stress wave reflection, records the transmitted strain pulse received by the strain gauge on the transmission bar, and records the acoustic emission signal received by the acoustic emission sensors to complete the test.

[0026] Beneficial effects:

[0027] (1) A testing device for rock dynamic type I fracture tests provided by the present invention can utilize acoustic emission sensors to protect the acoustic emission sensors during the dynamic loading process, solving the problem that the instrument is easily damaged by impact when using acoustic emission probes for measurement. The acoustic emission protective sleeves can achieve a better positioning effect for the acoustic emission sensors. Due to the presence of the protective sleeves in the sensor loading device, the pasting position of the acoustic emission sensors remains consistent for each test, achieving a better fixing effect for the specimen and solving the problem that the specimen becomes unstable and tilts due to the excessive weight caused by the current acoustic emission sensors.

[0028] (2) By setting the wire grooves on the inner wall of the outer shell, the data acquisition line connected to the acoustic emission sensor is constrained to prevent the data acquisition line from affecting the test and ensure the accuracy of the test.

[0029] (3) Through the pre-design of the test device for the dynamic type I fracture test of rock, the force on the specimen and the detection signal of the acoustic emission sensor will not be affected during the test. Therefore, the deformation and stress response of the rock under dynamic loading obtained are more in line with the actual situation, which helps to better study the deformation characteristics of rocks and rock-like materials in the natural environment. Brief Description of the Drawings

[0030] Figure 1 The front view of the test device for the dynamic type I fracture test of rock according to the present invention;

[0031] Figure 2 The side view of the test device for the dynamic type I fracture test of rock according to the present invention;

[0032] Figure 3 The top view of the test device for the dynamic type I fracture test of rock according to the present invention;

[0033] Figure 4 The flowchart of the test method for the dynamic type I fracture test of rock according to the present invention;

[0034] Wherein, 1. Outer shell; 2. Specimen; 3. Acoustic emission sensor; 301. First acoustic emission sensor; 302. Second acoustic emission sensor; 303. Third acoustic emission sensor; 304. Fourth acoustic emission sensor; 4. Data acquisition line; 5. Crack growth gauge; 6. Telescopic bracket; 7. Wire groove; 8. Acoustic emission protective sleeve; 9. Incident bar; 10. Transmission bar. Detailed Description of the Invention

[0035] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically illustrates the specific embodiments of the present invention.

[0036] Embodiment 1

[0037] A test device for the dynamic type I fracture test of rock, comprising:

[0038] An outer shell 1, and a plurality of wire grooves 7 are arranged on the inner wall of the outer shell 1;

[0039] A specimen 2, and the specimen 2 is arranged in the outer shell 1;

[0040] An incident bar 9, and the end of the incident bar 9 passes through the outer shell 1 and extends into the outer shell 1;

[0041] The transmission rod 10, the end of the transmission rod 10 passes through the outer shell 1 to cooperate with the incident rod 9 to clamp the specimen 2, and transmit the stress wave to the specimen 2;

[0042] The telescopic assembly is arranged inside the outer shell 1 and is correspondingly arranged with the specimen 2 to adjust the position of the specimen 2;

[0043] Multiple acoustic emission sensor 3 assemblies are arranged inside the outer shell 1 and are connected to the specimen 2 to detect the specimen 2; the multiple acoustic emission sensor 3 assemblies are correspondingly arranged with multiple wire grooves 7 one by one; the acoustic emission sensor 3 assemblies are connected to the data acquisition line 4; the data acquisition line 4 is arranged inside the wire groove 7.

[0044] Among them, the outer shell 1 is made of high-rigidity material, which not only has the characteristics of being firm and durable, can resist certain external force impacts and environmental interferences, and extends the service life of the device.

[0045] Through the above technical solution, the data acquisition line 4 of the acoustic emission sensor 3 is routed according to the prefabricated wire groove 7, effectively avoiding the stress generated by the twisting of the data acquisition line 4 from affecting the stability of the specimen 2, and further improving the reliability of the test.

[0046] In this embodiment, the acoustic emission sensor 3 assembly includes an acoustic emission sensor 3 and an acoustic emission protective sleeve 8; the acoustic emission sensor 3 is arranged inside the outer shell 1 and is connected to the curved surface of the specimen 2; one end of the acoustic emission protective sleeve 8 is connected to the inner wall of the outer shell 1, and the other end is fixedly sleeved on the end of the acoustic emission sensor 3 away from the specimen 2.

[0047] Through the above technical solution, the acoustic emission protective sleeve 8 can ensure the accuracy of the installation and positioning of the specimen 2. In each test operation, it can ensure that the pasting position of the acoustic emission sensor 3 always remains consistent, thus ensuring the consistency and accuracy of the test data measurement; when the specimen 2 is impacted by the rod, the presence of the acoustic emission protective sleeve 8 makes the acoustic emission sensor 3 not in direct contact with the rod, thus achieving full protection of the expensive and precise acoustic emission sensor 3, laying a solid foundation for the accuracy of the test results and the long-term stable operation of the instrument.

[0048] In this embodiment, it further includes a crack growth gauge 5; the crack growth gauge 5 is connected to one end of the specimen 2 close to the incident rod 9 and cooperates with the acoustic emission sensor 3 to detect the specimen 2.

[0049] In this embodiment, four acoustic emission sensors 3 are provided, which are respectively set as the first acoustic emission sensor 301, the second acoustic emission sensor 302, the third acoustic emission sensor 303, and the fourth acoustic emission sensor 304; the first acoustic emission sensor 301 and the second acoustic emission sensor 302 are arranged vertically and both extend along the radial direction of the specimen 2; the first acoustic emission sensor 301 is inclined upward, and the second acoustic emission sensor 302 is inclined downward; the third acoustic emission sensor 303 and the fourth acoustic emission sensor 304 are arranged vertically and both extend along the diameter direction of the specimen 2.

[0050] Among them, the transmission bar 10 is arranged between the first acoustic emission sensor 301 and the second acoustic emission sensor 302 and abuts against the specimen 2.

[0051] In this embodiment, the axis of symmetry of the specimen 2, the central axis of the incident bar 9, and the central axis of the transmission bar 10 are arranged on the same horizontal line.

[0052] Through the above technical solution, the incident bar 9 and the transmission bar 10 are made of the same material and have the same manufacturing process. Strain gauges are pasted on both the incident bar 9 and the transmission bar 10. The strain pulses of the incident bar 9 and the transmission bar 10 are detected by the data processing system, and then the strain is calculated. A launching device is arranged in front of the incident bar 9, and stress waves are applied to the incident bar 9 by launching a bullet through applying air pressure, thereby being transmitted to the specimen 2. At the same time, a pulse shaper is pasted on the front end face of the incident bar 9 for waveform shaping.

[0053] In this embodiment, the telescopic assembly includes a telescopic bracket 6; the telescopic bracket 6 is arranged in the housing 1; one end of the telescopic bracket 6 is connected to the bottom of the housing 1, and the other end abuts against the specimen 2 to adjust the height of the specimen 2.

[0054] Through the above technical solution, the specimen 2 is placed on the platform at the top of the telescopic bracket 6. This design can prevent the instability or inclination problems caused by the overweight of the specimen 2, and can adjust the specimen 2 to a suitable position through the telescopic bracket 6 according to the specific needs of the experimenter.

[0055] The testing device for rock dynamic type-I fracture testing provided by the present invention can ensure the stability of the specimen during the dynamic fracture test, protect the acoustic emission sensors, and will not affect the damage characteristics and strain distribution of the rock detected by the acoustic emission sensors.

[0056] Embodiment 2

[0057] A testing method for a testing device for rock dynamic type-I fracture testing is the testing method for the testing device for rock dynamic type-I fracture testing provided in Embodiment 1. The method includes the following steps:

[0058] S1. Fabricate specimen 2: First, cut the original rock sample and drill cores, and then process the rock into a straight-cut groove semi-circular disk bending specimen 2;

[0059] S2. Clamp specimen 2 between the incident bar 9 and the transmission bar 10: Place the outer shell 1 between the incident bar 9 and the transmission bar 10. The incident bar 9 passes through the prefabricated incident bar hole on the outer shell 1, and the transmission bar 10 passes through the prefabricated transmission bar hole on the outer shell 1. Initially adjust the position of specimen 2 according to the position of the acoustic emission protective sleeve 8, and then clamp specimen 2 between the incident bar 9 and the transmission bar 10. Apply an appropriate amount of lubricant to both end faces of specimen 2 to reduce the frictional effect caused by the end faces of specimen 2 and the test bars;

[0060] S3. Paste the acoustic emission sensor 3 on specimen 2 and place it in the outer shell 1: Install the acoustic emission sensor 3 into the acoustic emission protective sleeve 8, and use the positioning function of the acoustic emission protective sleeve 8 to paste the acoustic emission sensor 3 on the curved surface of specimen 2 to ensure that the pasting position of the acoustic emission sensor 3 remains consistent for each test; Constrain the data acquisition line 4 connected to the acoustic emission sensor 3 through the wire groove 7 inside the outer shell 1, place one data acquisition line 4 in each wire groove 7, and then connect the data acquisition line 4 to the acoustic emission host for data acquisition and processing;

[0061] S4. Adjust the position of specimen 2 through the telescopic support 6: Place specimen 2 on the platform at the top of the telescopic support 6, and then adjust the height of the telescopic support 6 to align the axis of symmetry of specimen 2 with the central axes of the incident bar 9 and the transmission bar 10, so that the central axis of the incident bar 9, the axis of symmetry of specimen 2, and the central axis of the transmission bar 10 are on the same horizontal line;

[0062] S5. Apply an incident wave to the incident bar 9: After the safety warning to the tester, start the launching device. The tester records the first incident strain pulse received by the strain gauge on the incident bar 9 and the reflected strain pulse after the stress wave reflection, records the transmitted strain pulse received by the strain gauge on the transmission bar 10, and records the acoustic emission signal received by the acoustic emission sensor 3 to complete the test.

[0063] Example 3

[0064] Based on Example 2, in this example, taking the rock processed into a straight-cut groove semi-circular disk bending specimen with a diameter of 50 mm and a thickness of 25 mm as an example, the specific test method is as follows:

[0065] S1. Fabricate specimen 2: First, cut the original rock sample and drill cores, and then process the rock into a straight-cut groove semi-circular disk bending specimen 2 with a diameter of 50 mm and a thickness of 25 mm;

[0066] S2. Clamp the specimen 2 between the incident bar 9 and the transmission bar 10: Place the outer shell 1 between the incident bar 9 and the transmission bar 10. The incident bar 9 passes through the prefabricated incident bar hole on the outer shell 1, and the transmission bar 10 passes through the prefabricated transmission bar hole on the outer shell 1. Initially adjust the position of the specimen 2 according to the position of the acoustic emission protective sleeve 8, and then clamp the specimen 2 between the incident bar 9 and the transmission bar 10. Apply an appropriate amount of lubricant to both end faces of the specimen 2 to reduce the friction effect caused by the specimen 2 and the end faces of the test bars;

[0067] S3. Paste the acoustic emission sensor 3 on the specimen 2 and place it in the outer shell 1: Install the acoustic emission sensor 3 into the acoustic emission protective sleeve 8, and use the positioning function of the acoustic emission protective sleeve 8 to paste the acoustic emission sensor 3 on the curved surface of the specimen 2 to ensure that the pasting position of the acoustic emission sensor 3 remains consistent for each test; Constrain the data acquisition line 4 connected to the acoustic emission sensor 3 through the wire groove 7 inside the test device. Place one data acquisition line 4 in each wire groove 7, and then connect the data acquisition line 4 to the acoustic emission host for data acquisition and processing;

[0068] S4. Adjust the position of the specimen 2 through the telescopic support 6: Place the specimen 2 on the platform at the top of the telescopic support 6, and then adjust the height of the telescopic support 6 to align the central axis of the specimen 2 with the central axes of the incident bar 9 and the transmission bar 10, so that the incident bar 9, the specimen 2, and the transmission bar 10 are on the same axis;

[0069] S5. Apply the incident wave to the incident bar 9: After the tester's safety warning, start the emission device. The tester records the first incident strain pulse received by the strain gauge on the incident bar 9 and the reflected strain pulse after the stress wave reflection, records the transmitted strain pulse received by the strain gauge on the transmission bar 10, and records the acoustic emission signal received by the acoustic emission sensor 3 to complete the test.

[0070] The above is only a preferred embodiment of the present invention, and does not impose any limitation on the technical scope of the present invention. Therefore, any minor modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A test device for dynamic type I fracture test of rock, characterized in that: include: A shell, wherein the inner wall of the shell is provided with a plurality of wire grooves; a sample, the sample being disposed in the housing; An incident rod, an end of which passes through the housing and extends into the housing; A transmission rod, an end of which passes through the housing and cooperates with the incident rod to clamp the sample and transmit the stress wave to the sample; A telescopic component, the telescopic component is disposed in the housing and is disposed corresponding to the sample to adjust the position of the sample; A plurality of acoustic emission sensor assemblies, wherein the plurality of acoustic emission sensor assemblies are arranged in the housing and connected to the sample to detect the sample; The plurality of acoustic emission sensor assemblies are arranged in one-to-one correspondence with the plurality of wire slots; the acoustic emission sensor assemblies are connected to a data acquisition line; and the data acquisition line is arranged in the wire slot.

2. The testing device for rock dynamic type I fracture test according to claim 1, characterized in that: The acoustic emission sensor assembly includes an acoustic emission sensor and an acoustic emission protective cover; the acoustic emission sensor is arranged in the shell and connected to the curved surface of the sample; one end of the acoustic emission protective cover is connected to the inner wall of the shell, and the other end is fixedly sleeved on the end of the acoustic emission sensor away from the sample.

3. The testing device for rock dynamic type I fracture test according to claim 2, characterized in that: It also includes a crack extension meter; the crack extension meter is connected to one end of the sample close to the incident rod and cooperates with the acoustic emission sensor to detect the sample.

4. The testing device for rock dynamic type I fracture test according to claim 3, characterized in that: There are four acoustic emission sensors, which are respectively set as a first acoustic emission sensor, a second acoustic emission sensor, a third acoustic emission sensor and a fourth acoustic emission sensor; the first acoustic emission sensor and the second acoustic emission sensor are arranged up and down, and both extend along the radial direction of the sample; the first acoustic emission sensor is inclined upward, and the second acoustic emission sensor is inclined downward; the third acoustic emission sensor and the fourth acoustic emission sensor are arranged up and down, and both extend along the diameter direction of the sample.

5. The testing device for rock dynamic type I fracture test according to claim 1, characterized in that: The symmetry axis of the sample, the central axis of the incident rod and the central axis of the transmission rod are arranged on the same horizontal line.

6. The testing device for rock dynamic type I fracture test according to claim 1, characterized in that: The telescopic assembly comprises a telescopic bracket; the telescopic bracket is arranged in the shell; one end of the telescopic bracket is connected to the bottom of the shell, and the other end abuts against the sample to adjust the height of the sample.

7. A testing method for a testing device for a rock dynamic type I fracture test, characterized in that: A testing method for a testing device for a dynamic type I fracture test of rock according to any one of claims 1 to 6, the method comprising the following steps: S1. Sample preparation: First, cut the original rock sample and drill the core, and process the rock into a straight-cut groove semi-disc bending sample; S2. Clamp the sample between the incident rod and the transmission rod: Place the housing between the incident rod and the transmission rod, and let the incident rod pass through the incident rod hole prefabricated on the housing. Let the transmission rod pass through the transmission rod hole prefabricated on the housing. Preliminarily adjust the position of the sample according to the position of the acoustic emission protective cover. Then clamp the sample between the incident rod and the transmission rod, and apply a proper amount of lubricant on both end faces of the sample to reduce the friction effect caused by the sample and the end face of the test rod. S3. Paste the acoustic emission sensor on the sample and place it in the shell: install the acoustic emission sensor into the acoustic emission protective cover, and use the positioning function of the acoustic emission protective cover to paste the acoustic emission sensor on the curved surface of the sample to ensure that the pasting position of the acoustic emission sensor remains consistent for each test; constrain the data acquisition line connected to the acoustic emission sensor through the wire groove inside the shell, place a data acquisition line in each wire groove, and then connect the data acquisition line to the acoustic emission host for data acquisition and processing; S4. Adjust the position of the sample by telescopic bracket: place the sample on the platform at the top of the telescopic bracket, then adjust the height of the telescopic bracket to place the sample, align the symmetry axis of the sample with the central axis of the incident rod and the central axis of the transmission rod, so that the central axis of the incident rod, the symmetry axis of the sample, and the central axis of the transmission rod are on the same horizontal line; S5. Apply incident wave to the incident rod: The tester starts the transmitting device after giving a safety warning. The tester records the first incident strain pulse received by the strain gauge of the incident rod and the reflected strain pulse after the stress wave is reflected, records the transmitted strain pulse received by the strain gauge on the transmission rod, and records the acoustic emission signal received by the acoustic emission sensor to complete the test.

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