Device for testing roof-contacted air leakage performance of closed filling material in coal mine goaf

Abstract

The invention relates to the technical field of simulated goaf air leakage performance testing, and discloses a coal mine goaf closed filling material roof-contacted air leakage performance testing device, which comprises a simulation cabin, an air leakage performance testing device and an air leakage performance testing device, the first top plate covers the opening and is used for covering part of the opening; the second top plate covers the opening and is spaced from the first top plate, and an injection port is defined between the first top plate and the second top plate; the object placing net is arranged at the injection port and is used for bearing coal briquettes of the simulated coal seam roof; one end of the grouting pipe is located outside the simulation bin, and the other end extends to the injection port and is used for injecting a filling material; the vacuum system comprises a vacuum pump and a connecting pipeline and is used for vacuumizing the simulation bin; the monitoring system comprises a pressure sensor and a flow sensor and is used for monitoring air leakage parameters. The contact condition of the filling material and the top of the coal seam can be fully simulated, and the test accuracy is improved.

Description

Technical Field

[0001] The present application relates to the technical field of simulated goaf area air leakage performance testing, for example, to a top connection and air leakage blocking performance test of a filling material. Background Art

[0002] At present, air leakage in the goaf of underground coal mines is one of the important causes of accidents such as gas accumulation and fire. As the core means to prevent and control coal spontaneous combustion fire accidents, air leakage plugging technology (including tunnel sealing technology, high-performance filling and plugging materials and real-time detection, etc.) has undergone important changes in the material system.

[0003] In traditional methods, the consolidation strength of yellow mud grouting materials is only 0.3-0.5MPa, and there is a shrinkage rate of 28%; although ammonium salt gel has instantaneous plugging characteristics, the concentration of NH3 released is as high as 200ppm, far exceeding the safety threshold; the new plugging material breaks through the organic / inorganic compounding technology, and the tensile strength is increased to

[0004] 1.8MPa, flame retardant grade reaches UL94V-0 standard, but the sealing and durability of the roof under complex geological conditions are still to be verified. Statistics show that about 65% of airtight leakage cases are caused by roof joints. Because the top sealing construction requires scaffolding, the operating space is limited, and it is easy to have incomplete filling or later settlement. Therefore, the main air leakage location is usually concentrated at the top of the coal seam roof, which has a higher risk than the coal seam area. It is the key part of the goaf area leakage and the focus of the goaf sealing.

[0005] The related technology discloses an experimental platform for simulating air leakage and plugging in goaf, which includes a support, a simulated coal mining face and a simulated goaf arranged on the support, wherein simulated tunnels are arranged on the left and right sides of the simulated coal mining face, and a working tunnel connected to the simulated tunnel is arranged between the simulated coal mining face and the simulated goaf, wherein the simulated air enters from the air inlet through the upper corner of the working tunnel, passes through the working tunnel, and flows out from the air outlet through the lower corner, wherein a comprehensive mining support model is arranged in the working tunnel, a coal cutting machine model is arranged in front of the comprehensive mining support model, and a plurality of air flow sensors for detecting air flow loss are arranged in the working tunnel from the upper corner to the lower corner; a plurality of push boxes containing simulated goaf filling materials are arranged side by side on the simulated goaf, and an air seepage net communicating with the working tunnel is arranged at the lower part of the push boxes near the end face of the working tunnel.

[0006] In the process of implementing the embodiments of the present disclosure, it is found that there are at least the following problems in the related art:

[0007] The experimental platform for simulating air leakage and plugging in goaf in related technologies has serious deficiencies in simulating actual working conditions. It is unable to accurately simulate the complex and changeable environmental factors underground in coal mines, and is unable to detect the sealing function of the top connection of the plugging air leakage material.

[0008] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present application, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0009] To provide a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. The summary is not a comprehensive review, nor is it intended to identify key / important elements or delineate the scope of protection of these embodiments, but rather serves as a preamble to the detailed description that follows.

[0010] Embodiments of the present disclosure provide a testing device for the air leakage performance of the gob sealing and filling material in coal mines at the roof contact, to solve the problem that the existing testing devices are difficult to simulate the actual environment at the top of coal mines and thus difficult to test the actual situation at the roof contact.

[0011] An embodiment of the first aspect of the present application provides a testing device for the air leakage performance of the gob sealing and filling material in coal mines at the roof contact. The testing device for the air leakage performance of the gob sealing and filling material in coal mines includes: a simulation chamber defining a receiving cavity with an opening at the top; a first top plate covering the opening, the first top plate being used to cover a part of the opening; a second top plate covering the opening and spaced apart from the first top plate, an injection port being defined between the first top plate and the second top plate; a placement mesh disposed at the injection port for carrying coal blocks simulating the coal seam roof; one end of a grouting pipe is located outside the simulation chamber, and the other end of the grouting pipe extends to the injection port for injecting filling material; a vacuum system includes a vacuum pump and a connecting pipeline for evacuating the simulation chamber; a monitoring system includes a pressure sensor and a flow sensor for monitoring air leakage parameters.

[0012] The testing device for the air leakage performance of the gob sealing and filling material in coal mines provided by the embodiments of the present disclosure can achieve the following technical effects:

[0013] By providing the first top plate, the second top plate and the placement mesh, the actual situation at the top of the coal mine can be simulated. By spacing the first top plate and the second top plate apart, an injection port can be formed to facilitate injecting the filling material into the simulation chamber. By providing the placement mesh, coal, rocks, etc. can be placed on the placement mesh to construct the actual conditions simulating the top of the coal mine, fully testing the sealing performance of the filling material at the roof contact with the coal mine top layer, and being able to reasonably and accurately simulate the working conditions in the coal mine underground, so as to solve the defect that the traditional device is difficult to simulate the actual environment at the top of the coal mine and thus difficult to test the actual situation at the roof contact, and fully improve the testing accuracy. By providing the vacuum system, the vacuum system can change the pressure in the simulation chamber, and the sealing performance of the filling material under dynamic negative pressure can be verified.

[0014] The above general description and the following description are only exemplary and explanatory and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by corresponding drawings, which do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements, and the drawings do not constitute a scale limitation, and wherein:

[0016] Figure 1 It is a cross-sectional structural schematic diagram of a device for testing the air leakage performance of a sealed filling material connected to the top of a coal mine goaf provided by an embodiment of the present disclosure;

[0017] Figure 2 It is a cross-sectional structural schematic diagram of another device for testing the air leakage performance of a sealed filling material roof connection in a coal mine goaf provided by an embodiment of the present disclosure;

[0018] Figure 3 It is a partial structural schematic diagram of another device for testing the air leakage performance of a closed filling material joint in a coal mine goaf provided by an embodiment of the present disclosure.

[0019] Reference numerals:

[0020] 1: vacuum pump; 2: first negative pressure sensor; 3: first flow sensor; 4: first valve (three-way valve); 5: first pipeline; 6: second baffle; 7: storage net; 8: coal block; 9: slot; 10: grouting pipe; 11: second valve; 12: second pipeline; 13: second flow sensor; 14: second negative pressure sensor; 15: vacuum chamber; 16: second top plate; 17: third valve; 18: exhaust pipe; 19: fourth valve; 20: drain pipe; 21: fifth valve; 22: controller; 23: injection chamber; 24: filter; 25: first top plate; 26: injection port: 27: first baffle. DETAILED DESCRIPTION

[0021] In order to be able to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0022] In the description, claims, and above-mentioned drawings of the embodiments of the present disclosure, terms such as "first" and "second" are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances to describe the embodiments of the present disclosure here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0023] In the embodiments of the present disclosure, the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "middle", "outer", "front", and "back" is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the embodiments of the present disclosure and their embodiments, and are not used to limit that the indicated device, element, or component must have a specific orientation or be constructed and operated in a specific orientation. And, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0024] In addition, the terms "arranged", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there is internal communication between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0025] Unless otherwise specified, the term "plurality" means two or more.

[0026] In the embodiments of the present disclosure, the character " / " indicates that the front and rear objects are in an "or" relationship. For example, A / B means: A or B.

[0027] The term "and / or" is an associative relationship describing an object, indicating that there can be three relationships. For example, A and / or B means: A or B, or, A and B these three relationships.

[0028] It should be noted that, without conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0029] Combined with Figures 1 to 3As shown in the figure, an apparatus for testing the air leakage performance of a gob sealing and filling material in a coal mine according to an embodiment of the present disclosure includes: a simulation chamber defining a receiving cavity with an opening at the top; a first roof plate 25 covering the opening, the first roof plate 25 being used to cover a part of the opening; a second roof plate 16 covering the opening and spaced apart from the first roof plate 25, an injection port 26 being defined between the first roof plate 25 and the second roof plate 16; a placement mesh 7 disposed at the injection port 26 for carrying coal blocks 8 simulating the coal seam roof; one end of a grouting pipe 10 being located outside the simulation chamber, and the other end of the grouting pipe 10 extending to the injection port 26 for injecting the filling material; a vacuum system including a vacuum pump 1 and a connecting pipeline for generating negative pressure in the simulation chamber; and a monitoring system disposed in the simulation chamber for detecting the pressure change and air leakage flow rate in the simulation chamber.

[0030] By adopting the embodiment of the present disclosure, by providing the first roof plate 25, the second roof plate 16 and the placement mesh 7, the real situation of the coal mine top can be simulated. By spacing the first roof plate 25 and the second roof plate 16 apart, an injection port 26 can be formed, which is convenient for injecting the filling material into the simulation chamber. By providing the placement mesh 7, coal mines, rocks, etc. can be placed on the placement mesh 7 to construct the real conditions simulating the coal mine top, fully testing the sealing performance of the interface between the filling material and the coal mine top layer, and being able to reasonably and accurately simulate the working conditions in the coal mine underground, so as to solve the defect that the traditional device cannot simulate the environment of the actual coal mine top and is difficult to test the actual interface situation. By providing the grouting pipe 10 and extending the grouting pipe 10 to the injection port 26, the filling material can be injected onto the placement mesh 7, and the contact process between the filling material and the placement mesh 7 can reflect the penetration and filling behavior of the material under the real roof conditions. By providing the vacuum system, the vacuum system can change the negative pressure in the simulation chamber, and the sealing performance of the filling material under dynamic negative pressure can be verified. By providing the monitoring system, the monitoring system can timely detect the pressure change and air leakage flow rate in the simulation chamber. This embodiment can test the air leakage performance of the interface of the filling material in a safe experimental environment. This simulation test method avoids the potential safety risks that may be brought by directly testing in the coal mine underground, such as gas leakage, roof collapse and other dangerous situations, and ensures the safety of the test personnel.

[0031] Specifically, the mesh size of the placement mesh 7 is 10 mm × 10 mm.

[0032] In this way, the coal blocks 8 can be effectively supported, while avoiding the coal blocks 8 from falling from the placement mesh 7 and reducing the obstruction of the placement mesh 7 to the filling material, ensuring the filling speed.

[0033] Optionally, the testing device for the air leakage performance of the gob closed filling material in coal mines further includes: an injection bin 23, which is arranged on the top of the simulation bin, and the injection bin 23 defines an injection cavity with an opening at the bottom, and the bottom opening of the injection cavity corresponds to the injection port 26; wherein, the other end of the grouting pipe 10 is arranged in the injection cavity and extends obliquely upward, and the pipe orifice at the other end of the grouting pipe 10 is higher than the upper end surface of the first roof 25.

[0034] In this way, by setting the injection bin 23, the injection bin 23 can play a role in guiding the filling material, avoiding the random flow of the filling material everywhere, and improving the filling effect. By setting the pipe orifice of the grouting pipe 10 higher than the upper end surface of the first roof 25, it can ensure that the filling material can fully cover the coal seam and ensure the filling effect of the filling material.

[0035] Specifically, the elevation angle of the grouting pipe 10 extending obliquely upward is greater than or equal to 15 degrees and less than or equal to 45 degrees, and the pipe orifice is 50 mm to 100 mm higher than the upper end surface of the first roof 25.

[0036] In this way, the combined action of gravity and negative pressure can be utilized to inject the filling material into the simulation bin in a spiral diffusion flow state.

[0037] Optionally, the pipe orifice of the grouting pipe 10 is arranged corresponding to the center of the injection port 26.

[0038] In this way, the filling material can flow more uniformly, avoiding the phenomenon of uneven flow, and ensuring the uniformity of the filling of the filling material.

[0039] Optionally, the volume of the injection bin 23 can be adjusted. In this way, the volume of the injection bin 23 can be increased or decreased for different filling materials, so as to adjust the volume according to the grouting volume and ensure the filling effect.

[0040] Specifically, the injection bin 23 is composed of multiple layers of concentric cylinders nested together, and the layers are connected by slide rails or ball bearings. A hydraulic cylinder or an electric push rod is arranged at the top of the injection bin 23 to drive the upper cylinder to lift, realizing stepless adjustment of the volume.

[0041] Optionally, the testing device for the air leakage performance of the gob closed filling material in coal mines further includes: an exhaust pipe 18, one end of the exhaust pipe 18 is located in the injection bin 23, and the other end of the exhaust pipe 18 extends outside the simulation bin for discharging the gas in the injection bin 23.

[0042] In this way, by providing the exhaust pipe 18, the exhaust pipe 18 can discharge the gas generated during the injection process of the filling material in real time, eliminate the air resistance phenomenon, ensure the sufficient flow of the filling material to fill the voids, and thus avoid the situation where gas accumulation affects the roof contact compactness. Secondly, the exhaust pipe 18 can connect the injection chamber 23 with the outside world, maintain the air pressure balance between the injection chamber 23 and the external environment, prevent the increase in the injection resistance of the filling material caused by the increase in air pressure, and enable the filling material to achieve a more realistic settlement process under the action of natural gravity.

[0043] Optionally, the testing device for the air leakage performance of the closed filling material for roof contact in a coal mine goaf further includes: a third valve 17 provided on the grouting pipe 10, and the third valve 17 is used to control the on-off of the grouting pipe 10; a fourth valve 19 provided on the exhaust pipe 18, and the fourth valve 19 is used to control the on-off of the exhaust pipe 18.

[0044] In this way, by providing the third valve 17, the third valve 17 can accurately control the start and end of grouting by controlling the on-off of the grouting pipe 10, avoid waste and over-injection of the filling material, and avoid the backflow of the filling material. By providing the fourth valve 19, when the fourth valve 19 controls the on-off of the exhaust pipe 18, closing the exhaust pipe 18 can prevent external air from entering the injection chamber 23 through the exhaust pipe 18, thus avoiding affecting the pressure environment in the cavity and the accuracy of the test results.

[0045] Optionally, the third valve 17 is an electric valve, and the fourth valve 19 is an electric valve.

[0046] In this way, automatic control can be achieved, the automation degree of the testing device can be improved, and the rapidity of opening and closing can be improved.

[0047] Optionally, the testing device for the air leakage performance of the closed filling material for roof contact in a coal mine goaf further includes: a first baffle 27 vertically provided in the accommodating cavity; a second baffle 6 vertically provided in the accommodating cavity, and the second baffle 6 in the accommodating cavity is spaced apart from the first baffle 27. The second baffle 6 and the first baffle 27 are used to divide the accommodating cavity into a filling space and a vacuum chamber 15, and the vacuum chamber 15 includes at least one sub-chamber; the first baffle 27, the second baffle 6 and the inner wall of the simulation chamber jointly enclose a filling cavity with an open top, and the opening of the filling cavity corresponds to the injection port 26.

[0048] In this way, by setting the first baffle 27 and the second baffle 6, the space inside the simulation chamber can be divided. A filling cavity is formed between the two baffles, and by setting the filling cavity corresponding to the injection port 26, the filling material can automatically flow into the filling cavity under the action of gravity, forcing the filling material to flow along the preset path (filling cavity), simulating the actual diffusion behavior of the underground filling material in a confined space. The two baffles can limit the lateral diffusion of the filling material, forcing the material to preferentially fill upward to the top of the simulation chamber, more realistically reflecting the roof contact performance of the material at the goaf roof. By setting the first baffle 27 and the second baffle 6, the vacuum chamber 15 can be defined, ensuring the sealing effect of the vacuum chamber 15.

[0049] Specifically, before grouting the grouting pipe 10, a vacuum pumping operation can be performed on the vacuum chamber 15 to judge the sealing effect of the vacuum chamber 15, facilitating subsequent tests on the filling material.

[0050] Optionally, the first baffle 27 abuts against the storage net 7 for supporting the storage net 7.

[0051] In this way, the first baffle 27 can serve as a fixed base for the storage net 7, providing stable mechanical support to prevent the storage net 7 from deforming, collapsing or displacing due to the flow pressure or gravity during the injection of the filling material.

[0052] Optionally, the second baffle 6 abuts against the storage net 7 for supporting the storage net 7.

[0053] In this way, the second baffle 6 can serve as a fixed base for the storage net 7, providing stable mechanical support to prevent the storage net 7 from deforming, collapsing or displacing due to the flow pressure or gravity during the injection of the filling material.

[0054] Optionally, a plurality of card slots 9 are provided on the bottom wall of the simulation chamber, and the plurality of card slots 9 are arranged side by side at intervals for fixing the first baffle 27 and the second baffle 6.

[0055] In this way, by setting the card slots 9, the card slots 9 provide a standardized plug-in interface for the first baffle 27 and the second baffle 6, ensuring that the first baffle 27 and the second baffle 6 are always installed perpendicular to the bottom wall, eliminating experimental errors caused by artificial installation angle deviations. Secondly, after the card slots 9 are inserted with the baffles, a sealing interface is formed to prevent gas leakage between the filling cavity and the vacuum chamber 15 through the bottom wall gap. By setting a plurality of card slots 9, the distance between the first baffle 27 and the second baffle 6 can be flexibly adjusted, and thus the thickness of the filling cavity can be flexibly adjusted to test filling materials of different thicknesses, improving the test flexibility.

[0056] Optionally, the card slot 9 can be a T-shaped slot or a dovetail slot. It can be understood that the specific structural form of the card slot 9 is not unique.

[0057] Exemplarily, such asFigure 1 As shown, the card slot 9 is a square groove.

[0058] Optionally, the side wall of the simulation chamber is made of a transparent material.

[0059] In this way, the tester can directly observe the situation of the filling material reaching the top in the injection chamber 23.

[0060] Specifically, the simulation chamber can be made of transparent acrylic material.

[0061] Optionally, one end of the storage net 7 is detachably connected to the first top plate 25.

[0062] In this way, when the storage net 7 is connected to the first top plate 25, the storage net 7 can be fixed. When the storage net 7 is disassembled, different materials (metal net / fiber net), pore sizes or pre-set damaged storage nets 7 can be quickly replaced to simulate the fracture characteristics of different roof lithologies such as sandstone and shale, expanding the coverage of test conditions.

[0063] Optionally, the other end of the storage net 7 is detachably connected to the second top plate 16.

[0064] In this way, when the storage net 7 is connected to the second top plate 16, the storage net 7 can be fixed. When the storage net 7 is disassembled, different materials (metal net / fiber net), pore sizes or pre-set damaged storage nets 7 can be quickly replaced to simulate the fracture characteristics of different roof lithologies such as sandstone and shale, expanding the coverage of test conditions.

[0065] Optionally, both the first top plate 25 and the second top plate 16 are detachably connected to the simulation chamber.

[0066] In this way, by replacing the first top plate 25 and the second top plate 16 with different sizes, the size of the injection port 26 can be adjusted according to the rheological properties (such as viscosity and particle size) of the filling material. Secondly, the sizes of the first top plate 25 and the second top plate 16 can be flexibly adjusted according to the positions of the first baffle 27 and the second baffle 6 to ensure the seal between the baffle and the edge of the injection port 26, and ensure that the baffle can form a leak-free contact with the inner wall of the simulation chamber after being installed at any position.

[0067] Optionally, the vacuum pump 1 is arranged outside the simulation chamber, and the vacuum pump 1 is used to evacuate the vacuum chamber 15; one end of the first pipeline 5 is communicated with the vacuum pump 1, and the other end of the first pipeline 5 extends into the vacuum chamber 15.

[0068] In this way, by arranging the vacuum pump 1 outside the simulation chamber, the deviation of test data caused by the possible additional air flow or temperature change due to placing the vacuum pump 1 inside the chamber is avoided, and the test accuracy is improved. Secondly, the internal space of the simulation chamber can be more focused on accommodating the components and materials required for the test, improving the space utilization rate.

[0069] Optionally, the monitoring system includes: a first flow sensor 3 disposed in the first pipeline 5 for detecting the flow rate of the first pipeline 5; a first negative pressure sensor 2 disposed in the first pipeline 5 for detecting the pressure of the first pipeline 5; and a first valve disposed in the first pipeline 5 for controlling the on / off of the first pipeline 5.

[0070] In this way, the first flow sensor 3 can detect the flow rate in the first pipeline 5 in real time, accurately measure the gas flow rate, and provide key data support for subsequent data analysis and evaluation of the filling effect. The first negative pressure sensor 2 can monitor the pressure change in the first pipeline 5 in real time and capture the pressure fluctuations in the pipeline in a timely manner. During the vacuum pumping or grouting process, by monitoring the pressure change, the sealing performance of the system can be understood. By adjusting the on / off of the first pipeline 5 through the first valve and combining the monitoring data of the negative pressure sensor, precise control of the pressure in the first pipeline 5 can be achieved. During the vacuum pumping stage, it can ensure that the required vacuum degree is reached in the first pipeline 5, creating good conditions for subsequent grouting and sealing effect testing.

[0071] Optionally, when the vacuum chamber 15 includes a first sub-chamber and a second sub-chamber, the first pipeline 5 extends into the first sub-chamber, and the monitoring system further includes: a second pipeline 12, one end of which is connected to the second sub-chamber, the other end extends outside the simulation chamber and is connected to the vacuum pump 1; a second negative pressure sensor 14 disposed in the second pipeline 12 for detecting the pressure change in the vacuum chamber 15; a second flow sensor 13 disposed in the second pipeline 12 for detecting the air flow rate in the second pipeline 12; and a second valve 11 disposed in the second pipeline 12 for controlling the on / off of the second pipeline 12.

[0072] In this way, the second negative pressure sensor 14 and the second flow sensor 13 respectively detect the pressure change and air flow rate in the second sub-chamber, providing independent monitoring data for each sub-chamber, which helps to analyze the sealing performance and air leakage situation of the filling material in different sub-chambers. The second valve 11 controls the on / off of the second pipeline 12. Combining the data of the second negative pressure sensor 14, the pressure in the second sub-chamber can be precisely adjusted to meet the requirements under different test conditions.

[0073] Optionally, the simulation chamber further includes: a drain pipe 20, one end of the drain pipe 20 is disposed at the bottom of the accommodating chamber, the other end of the drain pipe 20 extends outside the simulation chamber, and the drain pipe 20 is used to drain the water in the accommodating chamber.

[0074] In this way, by setting the drain pipe 20, the drain pipe 20 can timely drain the free water or uncured slurry oozing out during the injection of the filling material when the grouting pipe 10 is grouting, avoiding the interference of water accumulation on the test of the compactness of the material contacting the roof. Secondly, the drain pipe 20 directs the liquid water out, reducing the interference of the moisture formed by water evaporation, ensuring that the detection data of the negative pressure sensor and the flow sensor only reflect the gas leakage rate, and improving the test accuracy.

[0075] Optionally, the testing device for the air leakage performance of the gob filling material in coal mines when contacting the roof further includes: a filter screen 24, which is arranged at the port of the drain pipe 20 located in the accommodating cavity to prevent the filling material from blocking the drain pipe 20.

[0076] In this way, by arranging the filter screen 24, the filter screen 24 can block the aggregate particles in the filling material from entering the drain pipe 20, and prevent the drain pipe 20 from being blocked due to solid deposition.

[0077] Specifically, the aperture of the filter screen 24 is less than or equal to 2 mm.

[0078] Optionally, the first valve is a three-way valve 4, the inlet end is connected to the vacuum pump 1, the first outlet end is connected to the first pipeline 5, and the second outlet end is connected to the second pipeline 12.

[0079] In this way, the negative pressures of the first sub-cavity and the second sub-cavity can be adjusted respectively to achieve a control test. In this way, tests under various conditions can be carried out simultaneously in the same simulation chamber, improving the test efficiency. Secondly, by adjusting the negative pressures of each sub-cavity through the three-way valve 4, the situation where different pressure distributions may exist in different areas of the gob in coal mines can be simulated more realistically.

[0080] Optionally, the testing device for the air leakage performance of the gob filling material in coal mines when contacting the roof further includes: a fifth valve 21, which is arranged on the drain pipe 20, and the fifth valve 21 is used to control the on-off of the drain pipe 20.

[0081] In this way, by arranging the fifth valve, during the experiment, when it is necessary to drain the water in the filling cavity, the fifth valve 21 can be opened to allow the water to drain through the drain pipe 20. By controlling the opening and closing of the fifth valve 21, the drainage time and amount can be accurately controlled to ensure the accuracy and consistency of the experimental conditions.

[0082] Prevent backflow: When drainage is not required, closing the fifth valve 21 can prevent external air or moisture from flowing back into the vacuum cavity 15 through the drain pipe 20, thereby avoiding affecting the pressure environment in the cavity and the accuracy of the test results.

[0083] Optionally, the testing device for the air leakage performance of the gob filling material in coal mines when contacting the roof further includes: a controller 22, which is electrically connected to the third valve 17, the fourth valve 19, and the fifth valve 21, and is used to control the opening and closing of the first valve, the second valve 11, the third valve 17, the fourth valve 19, and the fifth valve 21.

[0084] In this way, the automation level of the test device can be improved, the operation convenience can be enhanced, and the precise on-off control of the electric control valve can be realized. The automatic detection function of this device not only greatly improves the detection efficiency, but also significantly reduces the human operation error, achieving high-precision, high-reliability and fully automatic operation of the detection process. In addition, the operator can view the operation status of the device on the controller 22 in real time, further improving the convenience and practicality of the system.

[0085] Specifically, the controller 22 can be a terminal device such as a computer or a remote control, which can realize remote control, improving the automation level and operation convenience of the test.

[0086] In one embodiment, the specific test operation steps are as follows:

[0087] Assembly of the experimental device: A plurality of card slots 9 are provided inside the vacuum chamber 15, and the card slots 9 are used to fix the first baffle 27 and the second baffle 6. The first baffle 27 and the second baffle 6 are fixed at a preset interval, and a suitable-sized storage net 7, a first top plate 25 and a second top plate 16 are selected for fixing and sealing. The coal block 8 is placed on the storage net 7 to simulate the condition of the real coal seam roof and the grouting filling material contacting the roof. The computer receives the data of all sensors and controls all electric control valves.

[0088] Check the airtightness of the device: Close the third valve 17, the fourth valve 19 and the fifth valve 21 through the computer, open the first valve, the second valve 11 and the vacuum pump 1, and use the vacuum pump 1 to evacuate the inside of the vacuum chamber 15 until the readings of the first negative pressure sensor 2 and the second negative pressure sensor 14 are p0, then close the vacuum pump 1; after one hour, the readings of the first negative pressure sensor 2 and the second negative pressure sensor 14 are p1. If the negative pressure rise rate is less than 0.5% per minute, it means that the airtightness of the device is good. If the negative pressure rise rate is greater than 0.5% per minute, the test device needs to be sealed with sealant and evacuated again for inspection.

[0089]

[0090] Grouting: Open the third valve 17, the fourth valve 19 and the fifth valve 21 through the computer, inject the filling material from the grouting pipe 10 until water comes out of the exhaust pipe 18, then stop grouting and close the third valve 17, the fourth valve 19 and the fifth valve 21.

[0091] Inspect the sealing effect of the material: After the filling material solidifies, turn on the vacuum pump 1, the first valve 4 and the second valve 11. After stabilizing for 1 hour, if the negative pressure rise rates of the first negative pressure sensor 2 and the second negative pressure sensor 14 are both less than 0.5% per minute, it means that the sealing performance of the filling material to be tested is better. At the same time, observe whether there are readings on the second flow sensor 13 and the first flow sensor 3. If there are readings, it means that the filling material to be tested leaks air.

[0092] Inspect the contact of the filling material with the roof: The tester directly observes whether the filling material contacts the roof.

[0093] The above description and the accompanying drawings fully illustrate the embodiments of the present disclosure so that those skilled in the art can practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Unless explicitly required, the individual components and functions are optional, and the order of operations may vary. Parts and features of some embodiments may be included in or substituted for parts and features of other embodiments. The embodiments of the present disclosure are not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A device for testing the air leakage performance of the sealed filling material connected to the roof of a coal mine goaf, characterized in that: include: A simulation chamber defines a receiving cavity with an opening at the top; A first top plate (25) is arranged on the opening, and the first top plate (25) is used to cover part of the opening; A second top plate (16) is arranged to cover the opening and is spaced apart from the first top plate (25), and an injection port (26) is defined between the first top plate (25) and the second top plate (16); A storage net (7) is provided at the injection port (26) and is used to carry coal blocks (8) simulating the top plate of a coal seam; A grouting pipe (10), one end of which is located outside the simulation chamber and the other end of which extends to the injection port (26) for injecting filling material; A vacuum system, comprising a vacuum pump (1) and connecting pipelines, for evacuating the simulation chamber; The monitoring system, including pressure sensors and flow sensors, is used to monitor air leakage parameters.

2. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 1 is characterized in that: Also includes: An injection chamber (23) is disposed on the top of the simulation chamber and defines an injection cavity with a bottom opening, wherein the bottom opening corresponds to the injection port (26); The other end of the grouting pipe (10) is arranged in the injection cavity and extends upwardly in an inclined manner, and the pipe opening of the other end of the grouting pipe (10) is higher than the upper end surface of the first top plate (25).

3. The device for testing the air leakage performance of the sealed filling material in the coal mine goaf according to claim 2 is characterized in that: Also includes: An exhaust pipe (18) has one end located in the injection chamber (23) and the other end extending outside the simulation chamber, and is used to exhaust the gas in the injection chamber (23).

4. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 3 is characterized in that: Also includes: A third valve (17), provided on the grouting pipe (10), for controlling the on and off of the grouting pipe (10); The fourth valve (19) is arranged on the exhaust pipe (18) and is used to control the opening and closing of the exhaust pipe (18).

5. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 1 is characterized in that: Also includes: A first baffle (27) is vertically arranged in the accommodating cavity; The second baffle (6) is vertically arranged in the accommodating chamber, and the second baffle (6) and the first baffle (27) are spaced apart from each other. The second baffle (6) and the first baffle (27) are used to separate the accommodating chamber into a filling chamber and a vacuum chamber (15), wherein the vacuum chamber (15) comprises at least one sub-chamber; the first baffle (27), the second baffle (6) and the inner wall of the simulation chamber jointly enclose a filling chamber with a top opening, and the opening of the filling chamber corresponds to the injection port (26).

6. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 5, characterized in that: The bottom wall of the simulation chamber is provided with a plurality of card slots (9), which are arranged side by side and spaced apart and are used to fix the first baffle plate (27) and the second baffle plate (6).

7. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 5, characterized in that: The vacuum pump (1) is arranged outside the simulation chamber and is used to evacuate the vacuum chamber (15); The connecting pipeline comprises a first pipeline (5), one end of the first pipeline (5) is connected to the vacuum pump (1), and the other end of the first pipeline (5) extends into the vacuum chamber (15).

8. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 7, characterized in that: The monitoring system includes: A first flow sensor (3), arranged in the first pipeline (5), and used for detecting the flow of the first pipeline (5); A first negative pressure sensor (2) is provided in the first pipeline (5) and is used to detect the pressure of the first pipeline (5); The first valve (4) is arranged on the first pipeline (5) and is used to control the opening and closing of the first pipeline (5).

9. The device for testing the air leakage performance of the sealed filling material connected to the top of the coal mine goaf according to claim 7, characterized in that: When the vacuum chamber (15) includes a first sub-chamber and a second sub-chamber, the first pipeline (5) extends into the first sub-chamber, and the monitoring system further includes: A second pipeline (12), one end of which is in communication with the second sub-chamber, and the other end of which extends outside the simulation chamber and is connected to the vacuum pump (1); A second negative pressure sensor (14), disposed in the second pipeline (12), for detecting pressure changes in the vacuum chamber (15); A second flow sensor (13), disposed in the second pipeline (12), and used to detect the air flow in the second pipeline (12); The second valve (11) is arranged on the second pipeline (12) and is used to control the opening and closing of the second pipeline (12).

10. The device for testing the air leakage performance of the sealed filling material top connection in coal mine goaf according to any one of claims 1 to 9, characterized in that: The simulation warehouse also includes: A drainage pipe (20) has one end disposed at the bottom of the accommodating chamber and the other end extending outside the simulation chamber, and is used to drain water in the accommodating chamber.

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