A dynamic drop-hammer type acoustic emission testing device and method for liquid-filled jointed rock specimens

Abstract

The present invention provides a dynamic drop-hammer type acoustic emission test device for liquid-filled jointed rock samples, comprising a filling liquid applying device for simulating a liquid-filled jointed rock mass, a dynamic drop-hammer device for applying an impact load to the liquid-filled jointed rock sample of the filling liquid applying device, and an acoustic emission monitoring device connected to the filling liquid applying device for synchronously collecting acoustic emission signal characteristics during the local fracture evolution of the liquid-filled jointed rock sample under the action of the impact load. The present invention also provides a method for using the dynamic drop-hammer type acoustic emission test device for liquid-filled jointed rock samples. The dynamic drop-hammer type acoustic emission test device and method for liquid-filled jointed rock samples provided by the present invention can realize the application of quantitative and controllable dynamic loads, can enrich the test types of filling liquids, and the device is easy to disassemble and assemble, which is conducive to the collection of multiple information in the same process, and is convenient for better completing rock dynamics related test tasks.

Description

Technical Field

[0001] The invention relates to the technical field of rock dynamics testing, and in particular to a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device and a use method thereof. Background Art

[0002] In water conservancy projects and underground projects, dynamic loads such as blasting or earthquakes can trigger the generation and propagation of stress waves, affecting the projects. Natural rock masses often contain joints, and filled joints are more common. The fillings can be clay, gravel, water, oil, etc. It is particularly important to study the propagation laws of stress waves in filled joints and the characteristics of acoustic emission information caused by the rupture of jointed rock masses under dynamic impact loads, etc., for predicting and evaluating the safety of rock mass engineering. At present, the analysis of solids and solid-liquid mixed materials as filling materials is relatively sufficient, but there are few tests involving filling liquids. Therefore, the dynamic analysis and acoustic emission testing of liquid-filled jointed rock masses are particularly important.

[0003] In current material dynamics tests, drop hammer impact equipment is widely used. However, this type of equipment is often used for dynamic testing of various pipes and plates, and is rarely used in rock material testing. It is even less used to study the conditions of applying liquid to the joints of rock specimens, and cannot meet the actual needs of rock dynamics test research and engineering problems.

[0004] During the liquid filling test, the poor sealing of the device often leads to liquid leakage. In addition, when the drop hammer impact equipment is used for testing rock samples, it is rarely considered to be combined with the acoustic emission test device, which cannot conveniently explore the fracture acoustic emission characteristics of rock samples under dynamic impact loads. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device and a method of using the device, which can provide controllable dynamic load, facilitate simulation of liquid-filled jointed rock mass, and synchronously monitor the acoustic emission information of the fracture of the jointed rock mass sample, so as to better complete the rock dynamics related testing tasks.

[0006] In order to solve the above technical problems, the present invention provides a dynamic drop hammer type liquid-filled jointed rock sample acoustic emission testing device, comprising a dynamic drop hammer device, a filling liquid application device and an acoustic emission monitoring device;

[0007] The power drop hammer device comprises a metal drop hammer suspended on a pulley, and the pulley is arranged on a fixed bracket through a rotating bearing; a brake rod is fixedly arranged on the fixed bracket, and a hole matching a brake rubber block is arranged at the other end of the brake rod, and the brake rubber block is inserted into the hole, and the pulley is braked by friction damping generated by the contact between the brake rubber block and the side of the pulley;

[0008] The filling liquid application device comprises a rock sample assembly consisting of two rock samples, an upper rock sample and an auxiliary liquid application sleeve, the inner diameter of which matches the outer diameter of the two rock samples. The two rock samples are placed in the auxiliary liquid application sleeve from the upper part and the lower part respectively, and a filling space for filling the filling liquid is formed between the end surfaces of the two rock samples placed in the auxiliary liquid application sleeve.

[0009] The acoustic emission monitoring device comprises an acoustic emission sensor and an acoustic emission signal receiving and processing device. The acoustic emission sensors are respectively arranged on the surfaces of the two rock samples and the liquid-assisted application sleeve, and are connected to the acoustic emission signal receiving and processing device through wires.

[0010] Furthermore, the metal drop weight, the two rock samples and the liquid-assisted application sleeve are all cylindrical, the metal drop weight and the two rock samples have the same bottom surface, and the length of the metal drop weight can be set according to the weight required for the impact test.

[0011] Furthermore, annular rubber sealing rings are arranged on the upper and lower annular end faces of the liquid-assisted application sleeve, and the two rock samples are respectively passed through the annular rubber sealing rings and arranged in the liquid-assisted application sleeve. By adjusting the relative position of the rock sample and the annular rubber sealing ring, the liquid filling space between the end faces of the two rock samples can be adjusted.

[0012] Furthermore, the inner ring diameter of the annular rubber sealing ring is slightly smaller than the outer diameters of the two rock samples, and the annular rubber sealing ring can be elastically deformed, thereby ensuring that the filling liquid is always in the liquid filling space under the action of the impact load.

[0013] Furthermore, the fixed bracket includes an integral bracket fixed on the base, and a vertical connecting bracket laterally fixed on the integral bracket, the vertical connecting bracket is fixed on the integral bracket, the pulley is fixed to the lower part of the vertical connecting bracket through a rotating bearing, the metal drop weight is wound on the pulley through a steel wire, and the lifting height of the steel wire can be changed by adjusting the rotation angle of the pulley, thereby adjusting the falling height of the metal drop weight.

[0014] Furthermore, scale lines are marked on the side of the pulley, and a fixed pointer is arranged on the rotating bearing. The scale lines and the fixed pointer are used in conjunction to accurately adjust the rotation angle of the pulley, thereby accurately adjusting the falling height of the metal drop weight.

[0015] Furthermore, a metal limiting ring is arranged on the base, and the lower rock sample of the rock sample combination is fixed on the base through the metal limiting ring.

[0016] Furthermore, a plurality of acoustic emission sensors are respectively arranged on the surfaces of the two rock samples and the liquid-assisted application sleeve, and the arrangement manner on the surfaces of the two rock samples and the liquid-assisted application sleeve is a layered annular arrangement.

[0017] The present invention also provides a method for using a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device, comprising the following steps:

[0018] Fixing the lower rock sample in the rock sample assembly in a metal limiting ring located on the base;

[0019] Put the lower half of the liquid-assisted application sleeve on the lower rock sample in the placed rock sample combination, and adjust the relative position of the annular rubber sealing ring and the lower rock sample;

[0020] Injecting the filling liquid into the reserved liquid filling space, placing the upper rock sample in the rock sample combination into the upper half of the liquid auxiliary application sleeve, and adjusting the relative position of the annular rubber sealing ring and the upper rock sample to form a liquid filling space between the upper rock sample and the lower rock sample of the rock sample combination;

[0021] The acoustic emission sensor is arranged on the surface of the rock sample in the rock sample assembly and the surface of the liquid-assisted application sleeve, and is connected to the acoustic emission signal receiving and processing equipment by means of a wire;

[0022] Select a metal drop weight of the required weight, rotate the pulley to the predetermined position, insert the brake rubber block into the hole of the brake rod, and put the pulley in the braking state;

[0023] The brake rubber block is removed, and the metal drop weight falls to impact the liquid-filled rock sample. The acoustic emission sensor collects the acoustic emission signal of the dynamic process and transmits it to the acoustic emission signal receiving and processing equipment. The data monitored by the acoustic emission signal receiving and processing equipment is processed to complete the test.

[0024] The present invention provides a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission test device and a method of using the device. Based on the existing rock dynamics test research, the dynamic drop-hammer device is used to provide dynamic impact loads of different magnitudes for the sample to be tested. The filling liquid application device can realize effective simulation of the liquid-filled jointed rock sample. The acoustic emission monitoring device can synchronously record the fracture acoustic emission characteristics of the rock sample under the dynamic impact load. Moreover, the use of an annular rubber sealing ring effectively avoids the leakage problem of the filling liquid under the action of the dynamic load, and ensures the rationality of the results during the test. The introduction of the device can realize the application of quantitative and controllable dynamic loads, enrich the test types of the filling liquid, and the device is easy to disassemble and assemble, which is conducive to the collection of multiple information in the same process, and is convenient for better completion of rock dynamics related test tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 An overall schematic diagram of a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of a pulley structure of a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device provided by an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the structure of a brake rubber block of a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device provided by an embodiment of the present invention;

[0028] Figure 4 A schematic structural diagram of a filling liquid applying device of a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device provided by an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the structure of an annular rubber sealing ring of a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] See also Figure 1, an embodiment of the present invention provides a dynamic drop-hammer type acoustic emission testing device for liquid-filled jointed rock samples, comprising a filling liquid applying device for simulating a liquid-filled jointed rock mass, a dynamic drop-hammer device for applying an impact load to the liquid-filled jointed rock sample of the filling liquid applying device, and an acoustic emission monitoring device connected to the filling liquid applying device for synchronously collecting the acoustic emission signal characteristics during the local fracture evolution of the liquid-filled jointed rock sample under the action of the impact load. The dynamic drop-hammer device can quantitatively control the impact load value of the liquid-filled jointed rock sample of the filling liquid applying device, and is convenient for braking and starting the acoustic emission test of the liquid-filled jointed rock sample. The filling liquid applying device can apply liquid to the joint surface of the rock sample, and can conveniently adjust the filling liquid type and liquid volume.

[0031] The power drop hammer device includes a metal drop hammer 1, a steel wire 2, a pulley 3, a rotating bearing 4, a vertical connection bracket 7, an integral bracket 8, and a base 9. The metal drop hammer 1 is suspended on the pulley 3 through the steel wire 2, the pulley 3 is fixed to the vertical connection bracket 7 through the rotating bearing 4, the vertical connection bracket 7 is welded to the integral bracket 8, and the integral bracket 8 is fixed to the base 9. The metal drop hammer 1 is cylindrical and can be replaced with a metal drop hammer 1 of the same bottom area and different heights according to actual needs to obtain different drop hammer weights, thereby providing dynamic impact loads of different values. The steel wire 2 is coiled on the pulley 3, and the lifting height of the steel wire 2 can be changed by adjusting the rotation angle of the pulley 3, so that when the metal drop hammer 1 of the same weight model is selected, the metal drop hammer 1 can fall to different heights, thereby also providing dynamic impact loads of different values.

[0032] See also Figure 2 In order to accurately adjust the rotation angle of the pulley 3, a scale line 16 is marked on the side of the pulley 3, and a fixed pointer 17 is set on the rotating bearing 4. The scale line 16 and the fixed pointer 17 are used in conjunction with each other to achieve accurate adjustment of the rotation angle of the pulley 3. When in use, as long as the rotation angle corresponding to the scale line 16 and the lifting height corresponding to the steel wire 2 are pre-calibrated, the metal drop weight 1 falls at a specific height position to provide a dynamic impact load of a specific value.

[0033] See also Figure 3, the pulley 3 is braked before the impact test by the brake rod 6 and the brake rubber block 5. One end of the brake rod 6 is fixed on the vertical connection bracket 7, and the other end is provided with a hole, from which the brake rubber block 5 can be inserted or withdrawn. The brake rubber block 5 inserted into the hole can directly contact the side surface of the pulley 3. The side surface of the pulley 3 is surface-polished, so that there is a large friction damping between the brake rubber block 5 and the side surface of the pulley 3. The brake of the pulley 3 can be achieved by the friction damping between the brake rubber block 5 and the side surface of the pulley 3. By controlling the braking position of the brake rubber block 5 on the side surface of the pulley 3, the rotation angle of the pulley 3 can be adjusted, so that the lifting height of the steel wire 2 can be changed, so that when the metal drop weight 1 of the same weight model is selected, different falling heights can be achieved, thereby providing dynamic impact loads of different values.

[0034] See also Figure 4 The filling liquid application device includes a rock sample combination 10, a liquid-assisted application sleeve 11, and a metal limit ring 12. The rock sample combination 10 is composed of two cylindrical rock samples of the same size, the two rock samples are respectively inserted into the liquid-assisted application sleeve 11 from the upper and lower parts of the liquid-assisted application sleeve 11. By adjusting the positions of the two rock samples, the required space for the injection of the filling liquid 18 can be reserved. The filling liquid 18 can be water, such as tap water, etc., or oil, such as petroleum, etc., or other types of liquids that may be involved in actual engineering. In addition, the bottom area of ​​the cylindrical metal drop hammer 1 is the same as the top area of ​​the upper rock sample of the rock sample combination 10, which facilitates the uniform application of the impact load at the impact contact surface position, and is conducive to the establishment and analysis of the subsequent mechanical model.

[0035] The metal limiting ring 12 is movably fixed on the base 9, and the lower rock sample in the rock sample assembly 10 is fixed on the metal limiting ring 12, so that the rock sample assembly 10 can be fixed at a specific position on the base 9, ensuring that the metal drop hammer 1 and the rock sample assembly 10 can achieve center loading during the impact process.

[0036] See also Figure 5 , an annular rubber seal ring 19 is arranged on the upper and lower annular end faces of the liquid-assisted application sleeve 11, so that the upper and lower rock samples in the rock sample assembly 10 can be respectively penetrated axially from the upper and lower parts of the liquid-assisted application sleeve 11 to an appropriate depth, and then by adjusting the relative position of the rock sample and the annular rubber seal ring 19, a specific volume of filling space can be reserved between the upper and lower rock samples, which is convenient for injecting different amounts of filling liquid. In addition, the annular rubber seal ring 19 can achieve a certain amount of elastic deformation, so that the filling liquid 18 can always be in the filling space during the test process, effectively avoiding liquid leakage.

[0037] The acoustic emission monitoring device includes an acoustic emission sensor 13, a wire 14, and an acoustic emission signal receiving and processing device 15. There are multiple acoustic emission sensors 13, which are respectively arranged in layers and rings on the upper and lower rock sample surfaces in the rock sample combination 10 and the surface of the liquid-assisted application sleeve 11, and are connected to the acoustic emission signal receiving and processing device 15 through the wire 14. When in use, the rock sample combination 10 to be tested is assembled in the liquid-assisted application sleeve 11, and multiple acoustic emission sensors 13 are arranged in layers and rings on the upper and lower rock sample surfaces in the rock sample combination 10 and the surface of the liquid-assisted application sleeve 11, and are connected to the acoustic emission signal receiving and processing device 15; the pulley 3 is adjusted to rotate to a specific position, the brake rubber block 5 is removed, and the metal drop hammer 1 falls to impact the rock sample, and the process information collected by the acoustic emission sensor 13 is synchronously collected to complete the rock dynamics related test.

[0038] Taking tap water as the filling liquid 18 as an example, the working principle and working process of a dynamic drop hammer type liquid-filled jointed rock sample acoustic emission testing device provided by an embodiment of the present invention are specifically described below:

[0039] First, according to the needs of the test samples, a rock sample combination 10 of a specific material is selected, and the lower rock sample of the rock sample combination 10 is placed in the metal limit ring 12 on the base 9; the lower half of the liquid auxiliary application sleeve 11 is placed on the lower rock sample, and the relative position of the lower annular rubber seal 19 and the lower rock sample is adjusted according to the preset filling liquid thickness; the filling liquid tap water is injected into the liquid auxiliary application sleeve 11 with the rock set at the bottom, and the injection process can adopt the quantitative auxiliary addition of the syringe. The upper rock sample of the rock sample combination 10 is inserted into the upper position of the liquid auxiliary application sleeve 11, and the relative position of the upper annular rubber seal 19 and the upper rock sample is adjusted to ensure that the filling liquid in the liquid-filled jointed rock sample is at a specific thickness, so as to realize the simulation of the liquid-filled jointed rock sample. Next, arrange the acoustic emission sensor 13 at the preset position on the surface of the rock sample combination 10 to be tested and the liquid-assisted application sleeve 11, and use the wire 14 to connect the acoustic emission sensor 13 with the acoustic emission signal receiving and processing device 15. Then, in combination with the test load requirements, select a metal drop weight 1 of a specific weight, rotate the pulley 3 to a specific angle, and use the fixed pointer 17 and the scale line 16 to indicate the specific angle value to ensure that the steel wire 2 is at a specific lifting height; insert the brake rubber block 5 into the preset hole of the brake rod 6, so that the device is in a state to be triggered. Finally, remove the brake rubber block 5 from the brake rod 6, and the metal drop weight 1 falls, and the liquid-filled jointed rock sample is dynamically impacted. The acoustic emission sensor 13 synchronously collects the impact response acoustic emission signal, and the data monitored by the acoustic emission signal receiving and processing device 15 are subsequently processed to complete the dynamic test.

[0040] The invention provides a dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device and method, which can not only realize the application of quantitative and controllable dynamic load, but also enrich the test types of filling liquid, and facilitate the disassembly and assembly of the device. In addition, it is conducive to the collection of multiple information in the same process, so as to better complete the rock dynamics related test tasks.

[0041] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device, characterized in that: It includes a power drop hammer device, a filling liquid application device and an acoustic emission monitoring device; The power drop hammer device comprises a metal drop hammer (1) suspended on a pulley (3); the pulley (3) is arranged on a fixed bracket via a rotating bearing (4); a brake rod (6) is fixedly arranged on the fixed bracket; a hole matching a brake rubber block (5) is arranged at the other end of the brake rod (6); the brake rubber block (5) is inserted into the hole, and the pulley (3) is braked by friction damping generated by the contact between the brake rubber block (5) and the side of the pulley (3); the metal drop hammer (1) is wound around the pulley (3) via a steel wire (2); and the lifting height of the steel wire (2) can be changed by adjusting the rotation angle of the pulley (3), thereby adjusting the falling height of the metal drop hammer (1); The filling liquid application device comprises a rock sample assembly (10) consisting of two upper and lower rock samples and a liquid auxiliary application sleeve (11) whose inner diameter matches the outer diameter of the two rock samples; the two rock samples are placed in the liquid auxiliary application sleeve (11) from the upper part and the lower part respectively; a liquid filling space for filling the filling liquid (18) is formed between the end surfaces of the two rock samples placed in the liquid auxiliary application sleeve (11); The acoustic emission monitoring device comprises an acoustic emission sensor (13) and an acoustic emission signal receiving and processing device (15); the acoustic emission sensor (13) is respectively arranged on the surface of the two rock samples and the liquid-assisted application sleeve (11), and is connected to the acoustic emission signal receiving and processing device (15) via a wire (14); The metal drop weight (1) has the same bottom surface as the two rock samples, and the length of the metal drop weight (1) can be set according to the weight required for the impact test; An annular rubber sealing ring (19) is arranged on the upper and lower annular end surfaces of the liquid-assisted application sleeve (11); the two rock samples are respectively passed through the annular rubber sealing rings (19) and arranged in the liquid-assisted application sleeve (11); and the liquid-filled space between the end surfaces of the two rock samples can be adjusted by adjusting the relative position of the rock sample and the annular rubber sealing ring (19).

2. The dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to claim 1 is characterized in that: The metal drop weight (1), the two rock samples and the liquid auxiliary application sleeve (11) are all cylindrical.

3. The dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to claim 1 is characterized in that: The inner ring diameter of the annular rubber sealing ring (19) is slightly smaller than the outer diameter of the two rock samples, and the annular rubber sealing ring (19) is elastically deformable, thereby ensuring that the filling liquid (18) is always in the liquid filling space under the action of the impact load.

4. The dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to claim 1 is characterized in that: The fixed bracket comprises an integral bracket (8) fixed on a base (9), and a vertical connection bracket (7) laterally fixed on the integral bracket (8), the vertical connection bracket (7) being fixed on the integral bracket (8), and the pulley (3) being fixed on the lower part of the vertical connection bracket (7) via a rotating bearing (4).

5. The dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to claim 4 is characterized in that: The side of the pulley (3) is marked with a scale line (16), and a fixed pointer (17) is arranged on the rotating bearing (4). The scale line (16) and the fixed pointer (17) are used in combination to accurately adjust the rotation angle of the pulley (3), thereby accurately adjusting the falling height of the metal drop weight (1).

6. The dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to claim 4 is characterized in that: A metal limiting ring (12) is provided on the base (9), and the lower rock sample of the rock sample assembly (10) is fixed on the base (9) via the metal limiting ring (12).

7. The dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to claim 1 is characterized in that: A plurality of acoustic emission sensors (13) are respectively arranged on the surfaces of the two rock samples and the liquid-assisted application sleeve (11), and the arrangement manner on the surfaces of the two rock samples and the liquid-assisted application sleeve (11) is a layered annular arrangement.

8. A method for using the dynamic drop-hammer type liquid-filled jointed rock sample acoustic emission testing device according to any one of claims 1 to 7, characterized in that: The steps include: The lower rock sample in the rock sample assembly (10) is fixed in a metal limiting ring (12) located on the base (9); The lower half of the liquid-assisted application sleeve (11) is placed on the lower rock sample in the placed rock sample assembly (10), and the relative position of the annular rubber sealing ring (19) and the lower rock sample is adjusted; Injecting a filling liquid (18) into the reserved liquid filling space, placing the upper rock sample in the rock sample assembly (10) into the upper half of the liquid auxiliary application sleeve (11), and adjusting the relative position of the annular rubber sealing ring (19) and the upper rock sample to form a liquid filling space between the upper rock sample and the lower rock sample of the rock sample assembly (10); The acoustic emission sensor (13) is arranged on the surface of the rock sample in the rock sample assembly (10) and the surface of the liquid auxiliary application sleeve (11), and is connected to the acoustic emission signal receiving and processing device (15) by means of a wire (14); Select a metal drop weight (1) of a desired weight, rotate the pulley (3) to a predetermined position, insert the brake rubber block (5) into the hole of the brake rod (6), and put the pulley (3) into a braking state; The brake rubber block (5) is removed, and the metal drop weight (1) falls to impact the liquid-filled rock sample. The acoustic emission sensor (13) collects the acoustic emission signal of the dynamic process and transmits it to the acoustic emission signal receiving and processing device (15). The data monitored by the acoustic emission signal receiving and processing device (15) is processed to complete the test.

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