Device and method for testing influence of cyclic dynamic load on bearing characteristics of coal pillar dam body

Abstract

The invention discloses a device and a method for testing influence of cyclic dynamic load on bearing characteristics of a coal pillar dam body, mainly through a water injection system and a loading box body, soaking of a coal pillar sample can be realized, an underground reservoir environment of a goaf can be simulated, an impact block is moved through a moving assembly, and simulation of various different types of impact loads can be realized. And the impact condition of the coal pillar dam body in an actual goaf can be simulated more truly. According to the main technical scheme, according to the device for testing the influence of the cyclic dynamic load on the bearing characteristics of the coal pillar dam body, a loading box body comprises a containing space, and the containing space is used for containing a coal pillar sample; the water injection system is at least used for providing fluid for the loading box body; the detection piece is connected with a coal pillar sample; an impact block of the impact loading system is located above the loading box body, a moving assembly is connected with the impact block, and the moving assembly is used for driving the impact block to move and releasing the impact block, so that the impact block falls to impact the coal pillar sample.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, and in particular to a device and method for testing the bearing characteristics of a coal pillar dam body affected by cyclic dynamic loads. Background Art

[0002] Coal is my country's dominant energy source and an important industrial raw material. However, with the development of coal resources, the water storage structure of the aquifer will inevitably be destroyed. The large number of cracks formed will lead to groundwater leakage and seepage, accompanied by the generation of a large amount of mine water. However, the utilization rate of mine water is low and it cannot be effectively stored and utilized. my country's western region is short of water resources but rich in coal resources. More than 70% of the country's coal production comes from western mining areas, showing an inverse distribution trend.

[0003] Emerging green coal mine underground reservoir technologies have emerged. The dam body occupies a high proportion of the underground reservoir dam body length and is the main part of the underground reservoir dam body. Its stability is a prerequisite for the safe operation of the underground reservoir. The stress on the underground reservoir coal pillar dam body is relatively complex. It is not only affected by the pressure of the overlying rock strata and water pressure, but also by water intrusion, which has a strong weakening effect on the coal pillar dam body. As a typical coal mine dynamic disaster, rock burst will trigger impact loads, which will directly act on the underground reservoir coal pillar dam body, affecting the bearing deformation and stability of the coal pillar dam body. Therefore, it is concluded that the bearing deformation of the underground reservoir coal pillar dam body under the action of impact load will show more complex mechanical behavior and failure characteristics.

[0004] Therefore, there is an urgent need for an experimental device and method that can effectively simulate the reservoir environment and rock burst in the goaf area and fully ensure accuracy, reliability and simplicity. Summary of the Invention

[0005] In view of this, in order to solve at least one of the aforementioned technical problems, an embodiment of the present invention provides a device and method for testing the bearing characteristics of a coal pillar dam under the influence of cyclic dynamic loads.

[0006] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0007] On the one hand, the present invention provides a device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads.

[0008] A loading box (15), a water injection system, a detection member (19) and an impact loading system;

[0009] The loading box (15) includes a receiving space for receiving a coal pillar sample;

[0010] The water injection system is connected to the loading box (15) and communicates with the accommodating space, and the water injection system is at least used to provide fluid to the loading box (15);

[0011] The detection member (19) is used for connecting the coal pillar sample;

[0012] The impact loading system comprises a moving assembly and an impact block (11), wherein the moving assembly is connected to the impact block (11), the impact block (11) is located above a loading box (15), and the moving assembly is used to adjust the position of the impact block (11) and to release the impact block (11) so that the impact block (11) falls and provides an impact.

[0013] The loading box (15) includes a main body and a top plate (21), the main body and the top plate (21) enclose a receiving space, the top plate (21) is opposite to the impact block (11), the top plate (21) is used to contact the top of the coal pillar sample, and the impact block (11) is used to indirectly impact the coal pillar sample by impacting the top plate (21);

[0014] Alternatively, the loading box (15) includes a main body and a top plate (21), and the loading box (15) includes an immersion state and an impact state. In the immersion state, the main body and the top plate (21) enclose a receiving space, and the top plate (21) is opposite to the impact block (11). In the impact state, the top plate (21) opens the upper end opening of the main body, and the impact block (11) is used to impact the coal pillar sample through the upper end opening.

[0015] The moving assembly includes a lifting assembly, and the lifting assembly is used to drive the impact block (11) to move up and down relative to the loading box (15);

[0016] And / or, the moving assembly further comprises a translation assembly, and the translation assembly is used to drive the impact block (11) to move in a horizontal direction relative to the loading box (15).

[0017] The moving assembly includes a lifting assembly, the lifting assembly includes a first lifting device (27), a lifting platform (7) and a lifting rod (9), the first lifting device (27) is connected to the lifting platform (7), the lifting rod (9) is connected to the lifting platform (7), the lifting rod (9) is connected to the impact block (11), and the first lifting device (27) is used to drive the lifting platform (7) to move up and down;

[0018] The lifting assembly further comprises a second lifting device (8), the lifting rod (9) is connected to the lifting platform (7) via the second lifting device (8), and the second lifting device (8) is used to drive the lifting rod (9) to move up and down.

[0019] The moving assembly includes a lifting platform (7) and a lifting rod (9), and the lifting rod (9) is connected to the impact block (11);

[0020] The moving assembly includes a translation assembly, the translation assembly includes a translation drive member, the translation drive member is connected to the lifting platform (7) and the lifting rod (9), and the translation drive member is used to drive the lifting rod (9) to move horizontally relative to the lifting platform (7);

[0021] And / or, a slide groove is provided on the lifting platform (7), and the lifting rod (9) is slidably connected to the slide groove.

[0022] Wherein, the impact loading system further includes a magnetic member (10);

[0023] The moving assembly is connected to the impact block (11) via a magnetic piece (10). The magnetic piece (10) is used to connect the impact block (11) by powering on, and the magnetic piece (10) is used to release the impact block (11) by powering off, so that the impact block (11) falls and provides impact.

[0024] There are multiple impact blocks (11), and different impact blocks (11) have different bottom surface areas and / or different weights.

[0025] The device further comprises:

[0026] A transition pad (12) is laid on at least the upper surface of the loading box (15), or the transition pad (12) is used to be laid on the coal pillar sample, and the impact block (11) falls and impacts the coal pillar sample by impacting the transition pad (12).

[0027] On the other hand, the present invention also provides a method for testing the bearing characteristics of a coal pillar dam body under cyclic dynamic load, which is implemented using a device for testing the bearing characteristics of a coal pillar dam body under cyclic dynamic load. The method includes:

[0028] Place the coal pillar sample into the loading box;

[0029] The water injection system injects fluid into the loading box until the liquid level reaches the set height. After the preset maintenance time, the water in the loading box is discharged;

[0030] Adjust the position of the impact block by moving the assembly;

[0031] releasing the impact block so that the impact block falls and impacts the coal pillar sample;

[0032] Obtain test results through test pieces.

[0033] Before adjusting the position of the impact block by moving the assembly, the method further includes:

[0034] The top plate of the loading box is removed to open the upper end opening of the main body of the loading box, and the impact block falls to impact the coal pillar sample so that the impact block passes through the upper end opening to impact the coal pillar sample;

[0035] And / or, a transition pad is laid on at least the upper surface of the loading box, and the impact block falls to impact the coal pillar sample by impacting the transition pad.

[0036] The embodiment of the present invention proposes a device and method for testing the bearing characteristics of coal pillar dams affected by cyclic dynamic loads. Through the water injection system and the loading box, the coal pillar sample can be immersed before the impact test, and the underground water reservoir environment in the goaf can be simulated. By moving the impact block by the moving component, the simulation of various types of impact loads can be realized. It can more realistically simulate the impact conditions of the coal pillar dam in the actual goaf, greatly improve the accuracy and diversity of the test data, provide theoretical support for the design of goaf reservoirs and the optimization of the bearing performance of coal pillar dams, better guide the design of underground reservoirs in goafs, and has wide practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic structural diagram of a device for testing the bearing characteristics of a coal pillar dam affected by cyclic dynamic loads provided by an embodiment of the present invention;

[0038] Figure 2 A schematic structural diagram of another device for testing the bearing characteristics of a coal pillar dam under cyclic dynamic loads provided by an embodiment of the present invention;

[0039] Figure 3 A schematic structural diagram of a loading box in a device for testing the bearing characteristics of a coal pillar dam under cyclic dynamic load provided by an embodiment of the present invention, viewed from a first perspective;

[0040] Figure 4 A schematic structural diagram of a loading box in a second viewing angle in a device for testing the bearing characteristics of a coal pillar dam under cyclic dynamic load provided by an embodiment of the present invention;

[0041] Figure 5 A schematic structural diagram of a loading box in a device for testing the bearing characteristics of a coal pillar dam under cyclic dynamic load provided by an embodiment of the present invention from a third perspective;

[0042] Figure 6 A flow chart of a method for testing the bearing characteristics of a coal pillar dam affected by cyclic dynamic loads provided by an embodiment of the present invention;

[0043] Among them, there are control components 1, power device 2, transmission device 3, control circuit 4, drive mechanism 5, lifting mechanism 6, lifting platform 7, second lifting device 8, lifting rod 9, magnetic component 10, impact block 11, transition pad 12, fixture 13, test platform base 14, loading box 15, water tank 16, water injection hole 17, drainage hole 18, detection component 19, bottom plate 20, top plate 21, bolt 22, front side plate 23, rear side plate 24, left side plate 25, right side plate 26, and first lifting device 27. DETAILED DESCRIPTION

[0044] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation method, structure, characteristics and effects of the test device for the bearing characteristics of the coal pillar dam affected by cyclic dynamic load proposed by the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0045] On the one hand, if Figure 1-2 As shown, the present invention provides a device for testing the bearing characteristics of a coal pillar dam under cyclic dynamic load, comprising:

[0046] Loading box 15, water injection system, detection piece 19 and impact loading system;

[0047] The loading box 15 includes a receiving space for receiving the coal pillar sample;

[0048] The water injection system is connected to the loading box 15 and communicates with the accommodating space. The water injection system is at least used to provide fluid to the loading box 15.

[0049] The detection part 19 is used to connect the coal pillar sample;

[0050] The impact loading system includes a moving assembly and an impact block 11. The impact block 11 is located above the loading box 15. The moving assembly is connected to the impact block 11. The moving assembly is used to drive the impact block 11 to move and to release the impact block 11 so that the impact block 11 falls to provide impact.

[0051] The shape of the loading box 15 can be various, such as a main body, a cube, etc. The loading box 15 is a cavity structure, and the loading box 15 is a metal box, or at least partially made of metal. For example, in the embodiment described below, at least the top plate 21 for contacting the impact block 11 is made of metal. In one embodiment, Figure 3-5 As shown, the loading box 15 includes a bottom plate 20 and a top plate 21 that are arranged in parallel and spaced apart in the vertical direction, and limiting grooves are provided on the bottom plate 20 and the top plate 21. The front side plate 23, the rear side plate 24, the left side plate 25 and the right side plate 26 are fixed between the bottom plate 20 and the top plate 21 through the limiting grooves and a plurality of bolts 22. The front side plate 23, the rear side plate 24, the left side plate 25, the right side plate 26, the bottom plate 20 and the top plate 21 form a rectangular box with a hollow structure. Among them, a water injection hole 17 and a drainage hole 18 are provided on the front side plate 23. The height of the water injection hole 17 can be higher than the drainage hole 18. In some embodiments, the drainage hole 18 can extend to the bottom plate 20, thereby ensuring that the water in the loading box 15 is fully drained.

[0052] The water injection system is used to inject or drain fluid into the loading box 15. The fluid can be water, that is, to realize water injection and drainage into the loading box 15. Alternatively, the fluid can be other required liquids, such as a mixture of mud and water, corrosive fluid, etc. The water injection system can specifically include a water tank 16 and a water transport component. The water tank 16 is connected to the water injection hole 17 and the drainage hole 18 through the water transport component. The water tank 16 can be two, such as Figure 1-2 As shown, the water transport component may include a water pump and an on-off valve. One of the water tanks 16 is connected to the water injection hole 17 via the water pump, and the drainage hole 18 is connected to the other of the water tanks 16 via the on-off valve. The device also includes a control component 1, which is connected to the water pump and the on-off valve. The control component 1 controls the water pump to inject water into the loading box 15. After the coal pillar sample is soaked, the on-off valve is opened and the water is discharged by gravity.

[0053] The detection member 19 can be a variety of components capable of detecting stress changes in the coal pillar sample, such as a dynamic stress monitoring device, a displacement sensor, an ultrasonic sensor, etc. The detection member 19 directly passes through the side wall of the loading box 15 and is connected to the coal pillar sample.

[0054] To ensure the tightness of the loading box 15, O-rings can be provided between the front side panel 23, the rear side panel 24, the left side panel 25, the right side panel 26, the bottom panel 20, and the top panel 21. The connection point between the electrical connection line of the detection element 19 and the loading box 15 is sealed.

[0055] In some embodiments, the apparatus for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads may further include a test platform base 14 and a fixture 13. The test platform base 14 provides support and fixation. A loading box 15 is secured to the test platform base 14 via the fixture 13. The fixture 13 secures the loading box 15 horizontally and vertically to prevent movement of the loading box 15, which could affect the accuracy of the test. As shown in the figure, the leads of the detection element 19 can pass through the test platform base 14 and the base plate 20.

[0056] The moving assembly is used to move the position of the impact block 11 to simulate different impacts and provide more diverse experimental scenarios. The impact block 11 is an impact object with a certain weight and can be made of metal. The moving assembly is connected to the impact block 11 so that the impact block 11 is suspended above the loading box 15 and corresponds to the coal pillar sample. When loading impact is required, the moving assembly automatically releases the impact block 11 through the control part 1. Alternatively, the moving assembly can also be manually adjusted to achieve the release of the impact block 11.

[0057] An embodiment of the present invention proposes a testing device for the bearing characteristics of coal pillar dams affected by cyclic dynamic loads. Through the water injection system and the loading box, the coal pillar sample can be immersed before the impact test, and the underground water reservoir environment in the goaf can be simulated. By moving the impact block by the moving component, the simulation of various types of impact loads can be realized. It can more realistically simulate the impact conditions of the coal pillar dam in the actual goaf, greatly improve the accuracy and diversity of the test data, provide theoretical support for the design of goaf reservoirs and the optimization of the bearing performance of coal pillar dams, better guide the design of underground reservoirs in goafs, and has wide practicality.

[0058] When the impact block 11 impacts the coal pillar sample, the impact loading can be achieved by directly contacting the impact coal pillar sample, or the impact loading can be achieved by indirectly impacting the coal pillar sample through the top plate 21 of the loading box 15. In this case, the height of the coal pillar sample is required to be able to contact the top plate 21.

[0059] In one embodiment, the loading box 15 includes a main body and a top plate 21. The main body includes the aforementioned front side plate 23, rear side plate 24, left side plate 25, right side plate 26, and bottom plate 20. The main body and top plate 21 enclose a storage space. The top plate 21 is located at the top and opposite the impact block 11. The top plate 21 is used to contact the top of the coal pillar sample. The impact block 11 is used to indirectly impact the coal pillar sample by impacting the top plate 21. The impact force of the impact block 11 is transmitted to the coal pillar sample through the top plate 21.

[0060] In another embodiment, the loading box 15 includes a main body and a top plate 21. The loading box 15 has a soaking state and an impact state. In the soaking state, the main body and the top plate 21 enclose a storage space, and the top plate 21 is opposite the impact block 11. At this time, water can be injected into the loading box 15, and the top plate 21 is used to set up a simulated closed environment and prevent the intrusion of debris or water evaporation. When loading and impact are required, the top plate 21 is manually removed, and the loading box 15 is switched to the impact state. The top plate 21 opens the upper end opening of the main body, and the impact block 11 is used to pass through the upper end opening to directly impact the coal pillar sample.

[0061] In one embodiment, the moving assembly includes a lifting assembly for driving the impact block 11 to move up and down relative to the loading box 15. In some embodiments, the moving assembly also includes a translation assembly for driving the impact block 11 to move horizontally relative to the loading box 15.

[0062] The moving assembly can only realize the lifting and lowering drive of the impact block 11, or only realize the horizontal drive of the impact block 11, or can realize both the horizontal drive and the lifting and lowering drive of the impact block 11. The drive can be manual or automatic through the control unit 1.

[0063] In one embodiment, the moving assembly includes a lifting assembly, which includes a first lifting device 27, a lifting platform 7, and a lifting rod 9. The first lifting device 27 is connected to the lifting platform 7, the lifting rod 9 is connected to the lifting platform 7, and the lifting rod 9 is connected to the impact block 11. The first lifting device 27 is used to drive the lifting platform 7 to move up and down. The lifting assembly also includes a second lifting device 8. The lifting rod 9 is connected to the lifting platform 7 via the second lifting device 8, and the second lifting device 8 is used to drive the lifting rod 9 to move up and down.

[0064] The first lifting device 27 can be implemented in a variety of ways, such as a hydraulic cylinder, a screw motor, etc. In one embodiment, the first lifting device 27 further includes a lifting mechanism 6, a power unit 2, a transmission device 3, and a drive mechanism 5. The lifting mechanism 6 is connected to the drive mechanism 5, the transmission device 3 is connected to the drive mechanism 5, and the power unit 2 is connected to the transmission device 3 and the control unit 1. The control unit 1 controls the power unit 2 to provide driving power, which is transmitted to the drive mechanism 5 through the transmission device 3. The drive mechanism 5 then drives the lifting mechanism 6 to move, thereby raising and lowering the lifting platform 7.

[0065] The lifting assembly further includes a control circuit 4. The control circuit 4 of the control member 1 is at least connected to the second lifting device 8, which then controls the second lifting device 8 to drive the lifting rod 9 to move up and down. The second lifting device 8 can be a screw stepping motor.

[0066] The dual lifting and adjustment of the first lifting device 27 and the second lifting device 8 can provide a larger adjustment space, and the different structures of the first lifting device 27 and the second lifting device 8 can achieve both rapid and fine adjustment. For example, if both the first lifting device 27 and the second lifting device 8 use a screw and nut for lifting, but the pitch of the thread in the first lifting device 27 is greater than that of the second lifting device 8, the first lifting device 27 can achieve rapid adjustment, saving time, while the second lifting device 8 can achieve fine adjustment, ensuring the accuracy of height adjustment.

[0067] In one embodiment, the moving assembly includes a lifting platform 7 and a lifting rod 9, which is connected to an impact block 11. The moving assembly includes a translation assembly, which includes a translation driver connected to the lifting platform 7 and the lifting rod 9, and the translation driver is used to drive the lifting rod 9 to move horizontally relative to the lifting platform 7.

[0068] The second lifting device 8 and the lifting rod 9 are connected to the translation drive as a whole. The translation drive can be a telescopic motor, which is used to drive the lifting rod 9 to drive the impact block 11 to move horizontally to provide impact at different positions of the coal pillar sample.

[0069] In some other embodiments, the position of the impact block 11 can be adjusted manually. For example, a slide groove is provided on the lifting platform 7, and the second lifting device 8 and the lifting rod 9 are slidably connected to the slide groove as a whole. The lifting rod 9 can be manually pushed relative to the slide groove to achieve horizontal position adjustment. In addition, in embodiments including a translation drive member, a slide groove can also be provided on the lifting platform 7 to ensure the accuracy and stability of the horizontal movement of the second lifting device 8 and the lifting rod 9.

[0070] In one embodiment, the impact loading system further includes a magnetic member 10. In the aforementioned embodiment including the control circuit 4, the control circuit 4 is further connected to the magnetic member 10. The moving assembly is connected to the impact block 11 via the magnetic member 10. The magnetic member 10 is an electromagnetic device that generates magnetism when powered, causing the impact block 11 to be attracted. When the power is turned off, the magnetism disappears, releasing the impact block 11, causing it to fall and impact the coal pillar sample. The control member 1 controls the timing of the impact block 11's fall by controlling the electrical on and off of the magnetic member 10.

[0071] In some embodiments, the impact block 11 and the magnetic member 10 can be connected by a groove, that is, a groove is set on the impact block 11, and the magnetic member 10 is inserted into the groove to achieve connection, thereby making the impact block 11 and the magnetic member 10 accurately aligned, ensuring the impact position of the impact block 11 is accurate.

[0072] The magnetic member 10 is provided to enable quick connection and release of the impact block 11. The impact block 11 and the magnetic member 10 are connected by a groove, making the test operation simple and safe, allowing for easy multiple tests and reducing test errors. This avoids the problem of manual release of the impact block 11, which may cause the impact block 11 to have a horizontal initial velocity due to manual force, resulting in impact offset, and accurately testing the bearing characteristics of the coal pillar dam under the influence of cyclic dynamic loads.

[0073] In one embodiment, there are multiple impact blocks 11 , and different impact blocks 11 have different bottom surface areas and / or different weights.

[0074] Different impact blocks 11 can be impact blocks 11 of different volumes or impact blocks 11 of different weights. By using multiple models of impact blocks 11, it is possible to simulate a variety of different types of impact loads, and can more realistically simulate the impact conditions of the coal pillar dam in the actual goaf, greatly improving the accuracy and diversity of the test data, and providing effective data support for the study of underground reservoirs in goaf areas.

[0075] In one embodiment, the device further includes: a transition pad 12 , which is laid on at least the upper surface of the loading box 15 , and the impact block 11 falls and impacts the transition pad 12 to impact the coal pillar sample.

[0076] The transition pad 12 is laid on the top plate 21 of the loading box 15. It can increase the dispersion area of ​​the cyclic dynamic load loaded by the impact block 11 on the surface of the loading box 15 without changing the volume of the impact block 11, thereby simulating the cyclic dynamic load under different stress conditions.

[0077] In some embodiments, when applying the impact, the top plate 21 may be removed and the transition pad 12 may be laid on the top surface of the coal pillar sample, thereby simulating the cyclic dynamic load conditions under different stress conditions in the experiment of directly impacting the coal pillar sample.

[0078] It can be understood that there are multiple transition pads 12 , and different transition pads 12 have different extension areas.

[0079] On the other hand, Figure 6 As shown, the present invention also provides a method for testing the bearing characteristics of a coal pillar dam body affected by cyclic dynamic loads, which is implemented using the device for testing the bearing characteristics of a coal pillar dam body affected by cyclic dynamic loads according to any of the above embodiments. The method includes:

[0080] S1. Place a coal pillar sample into the loading box 15.

[0081] Prior to this step, the bottom plate 20, front side plate 23, rear side plate 24, left side plate 25, and right side plate 26 are assembled into the loading box 15 using bolts 22. O-rings are inserted into the gaps between the side plates. A coal pillar sample with a diameter of 50 mm and a height of 100 mm is prepared. The coal pillar sample is placed in the loading box 15 and the top plate 21 is installed.

[0082] S2. The water injection system injects fluid into the loading box 15 until the liquid level reaches a set height. After the preset curing time, the water in the loading box 15 is drained.

[0083] The height of the liquid level can be detected by setting a liquid level sensor in the loading box 15, or the height of the liquid level after the fluid is injected can be controlled by calculating the volume of the injected fluid. The height of the fluid can be set as needed. For example, when it is necessary to submerge the coal pillar sample, water can be added to the loading box 15 to the height of the coal pillar sample, such as injecting water to a height of 100 mm through the water injection hole 17. Alternatively, water may not be added to submerge the coal pillar sample. During the impact loading process, if it is necessary to load through the top plate 21, that is, the coal pillar sample contacts the top plate 21, and it is necessary to submerge the entire coal pillar sample, in order to ensure that enough water is added, a sensor can be set on the top plate 21. When the water level reaches the top plate 21 and triggers the sensor, the water addition is stopped. Alternatively, when it is not necessary to submerge the coal pillar sample, the water level can be controlled to be 0.3 to 0.7 times the height of the loading box.

[0084] The preset time can be 1 day to 30 days. For example, after adding water and soaking for 1 day, the water in the loading box 15 can be drained through the drain hole 18.

[0085] In some embodiments, an experiment can be conducted in which the impact block 11 directly impacts a coal pillar sample. For example, after step S2 , the method further includes removing the top plate 21 of the loading box 15 to open the upper end opening of the main body of the loading box 15 .

[0086] Alternatively, an experiment can be conducted in which the impact block 11 impacts the coal pillar sample through the roof 21 , that is, the roof 21 does not need to be removed.

[0087] In the embodiment including the transition pad 12 , if the top plate 21 is removed, the transition pad 12 can be laid on the upper surface of the coal pillar sample. If the top plate 21 is not removed, the transition pad 12 can be laid on the top plate 21 of the loading box 15.

[0088] S3. Adjust the position of the impact block 11 by moving the assembly.

[0089] This step specifically includes fixing the loading box 15 to the corresponding position of the test platform base 14 through the clamp 13, selecting the impact position and impact area, and selecting impact blocks 11 of different shapes and weights according to the test requirements, such as selecting an impact block 11 weighing 20kg.

[0090] The impact height is determined by adjusting the position of the lifting rod 9 on the lifting platform 7. For example, the control unit 1, through the first lifting device 27 and the second lifting device 8, drives the impact block 11 to the desired position. If the free fall height is controlled to 0.5m to 1.0m, the impact force can be controlled to 500-700N. For example, the distance between the impact block 11 and the top plate 21 of the loading box 15, or between the impact block 11 and the coal pillar sample, is adjusted to 1m.

[0091] S4. Release the impact block 11 to make it fall and impact the coal pillar sample.

[0092] In an embodiment including the magnetic member 10, the control member 1 cuts off the power supply to the magnetic member 10, thereby releasing the magnetic attraction and releasing the impact block 11. In an embodiment where the top plate 21 is removed, the impact block 11 drops to impact the coal pillar sample by passing through the upper opening. In an embodiment where the top plate 21 is not removed, the impact block 11 drops to impact the coal pillar sample by passing through the top plate 21.

[0093] In the embodiment including the transition pad 12 , the impact block 11 falls to impact the coal pillar sample by the impact block 11 falling through the impact transition pad 12 to impact the coal pillar sample.

[0094] S5. Obtain the test results through the detection component 19.

[0095] The results are obtained using dynamic stress monitoring equipment.

[0096] In one embodiment, three groups of 16 impact tests were performed. The specific test plan and results are shown in the following table.

[0097] Table 1 Experiment on the bearing characteristics of coal pillar dam under impact load at different water injection heights

[0098] Test number Water injection height / mm Soaking time / d Module falling height / m Compressive strength / MPa Deformation / mm 1# test 20 28 1 6.41 6.13 Test 2# 40 28 1 5.84 6.91 3# test 60 28 1 5.14 7.56 4# test 80 28 1 4.56 8.54 5# test 100 28 1 4.13 9.13

[0099] Table 2 Experiment on the bearing characteristics of coal pillar dam under impact load at different immersion times

[0100]

[0101]

[0102] Table 3 Experiment on the bearing characteristics of coal pillar dam under impact load at different module drop heights

[0103] Test number Water injection height / mm Soaking time / d Module falling height / m Compressive strength / MPa Deformation / mm 11# test 100 28 0.5 6.23 6.89 12# test 100 28 0.6 5.94 7.23 13# test 100 28 0.7 5.56 7.74 14# test 100 28 0.8 5.13 8.23 15# test 100 28 0.9 4.65 8.84 16# test 100 28 1.0 4.13 9.13

[0104] The module drop height refers to the distance from the impact block 11 to the top plate 21 of the loading box 15 or the distance from the impact block 11 to the coal pillar sample.

[0105] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A test device for the bearing characteristics of coal pillar dams under cyclic dynamic loads, characterized in that: include: A loading box (15), a water injection system, a detection member (19) and an impact loading system; The loading box (15) comprises a receiving space, and the receiving space is used to receive the coal pillar sample; The water injection system is connected to the loading box (15) and communicates with the accommodating space, and the water injection system is at least used to provide fluid to the loading box (15); The detection member (19) is used to connect the coal pillar sample; The impact loading system comprises a moving assembly and an impact block (11), wherein the moving assembly is connected to the impact block (11), and the impact block (11) is located above the loading box (15). The moving assembly is used to adjust the relative position of the impact block (11) and the loading box (15), and to release the impact block (11) so that the impact block (11) falls and provides an impact.

2. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: The loading box (15) comprises a main body and a top plate (21), wherein the main body and the top plate (21) enclose the accommodating space, the top plate (21) is opposite to the impact block (11), the top plate (21) is used to contact the top of the coal pillar sample, and the impact block (11) is used to indirectly impact the coal pillar sample by impacting the top plate (21); Alternatively, the loading box (15) includes a main body and a top plate (21), and the loading box (15) includes an immersion state and an impact state. In the immersion state, the main body and the top plate (21) enclose the accommodating space, and the top plate (21) is opposite to the impact block (11). In the impact state, the top plate (21) opens the upper end opening of the main body, and the impact block (11) is used to impact the coal pillar sample through the upper end opening.

3. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: The moving assembly includes a lifting assembly, and the lifting assembly is used to drive the impact block (11) to rise and fall relative to the loading box (15); And / or, the moving assembly includes a translation assembly, and the translation assembly is used to drive the impact block (11) to move in a horizontal direction relative to the loading box (15).

4. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: The moving assembly includes a lifting assembly, and the lifting assembly includes a first lifting device (27), a lifting platform (7) and a lifting rod (9), wherein the first lifting device (27) is connected to the lifting platform (7), the lifting rod (9) is connected to the lifting platform (7), and the lifting rod (9) is connected to the impact block (11), and the first lifting device (27) is used to drive the lifting platform (7) to move up and down; The lifting assembly further comprises a second lifting device (8), the lifting rod (9) is connected to the lifting platform (7) via the second lifting device (8), and the second lifting device (8) is used to drive the lifting rod (9) to move up and down.

5. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: The moving assembly comprises a lifting platform (7) and a lifting rod (9), wherein the lifting rod (9) is connected to the impact block (11); The moving assembly includes a translation assembly, the translation assembly includes a translation drive, the translation drive is connected to the lifting platform (7) and the lifting rod (9), and the translation drive is used to drive the lifting rod (9) to move horizontally relative to the lifting platform (7); And / or, a slide groove is provided on the lifting platform (7), and the lifting rod (9) is slidably connected to the slide groove.

6. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: The impact loading system further includes a magnetic member (10); The moving assembly is connected to the impact block (11) via the magnetic member (10), the magnetic member (10) is used to be energized to connect the impact block (11), and the magnetic member (10) is used to release the impact block (11) by being de-energized, so that the impact block (11) falls and provides an impact.

7. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: There are multiple impact blocks (11), and different impact blocks (11) have different bottom surface areas and / or different weights.

8. The device for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 1, characterized in that: The device further comprises: A transition pad (12) is laid on at least the upper surface of the loading box (15), or the transition pad (12) is used to be laid on the coal pillar sample, and the impact block (11) falls and impacts the coal pillar sample by impacting the transition pad (12).

9. A method for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads, characterized in that: The method is implemented using the device for testing the bearing characteristics of a coal pillar dam under cyclic dynamic loads as described in any one of claims 1 to 8, and includes: Place the coal pillar sample into the loading box; The water injection system injects fluid into the loading box until the liquid level reaches a set height, and drains the water in the loading box after a preset curing time; Adjust the position of the impact block by moving the assembly; releasing the impact block so that the impact block falls and impacts the coal pillar sample; Obtain test results through test pieces.

10. The method for testing the bearing characteristics of coal pillar dams under cyclic dynamic loads according to claim 9, characterized in that: Before adjusting the position of the impact block by moving the assembly, the method further includes: The top plate of the loading box is removed to open the upper end opening of the main body of the loading box, and the impact block falls to impact the coal pillar sample so that the impact block passes through the upper end opening to impact the coal pillar sample; And / or, a transition pad is laid on at least the upper surface of the loading box, and the impact block falls to impact the coal pillar sample, and the impact block falls and impacts the coal pillar sample by impacting the transition pad.

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