Underground sealing walls in coal mines and their construction methods

Abstract

This invention relates to the field of coal mining, providing a sealed underground wall in a coal mine and its construction method. It includes: a flexible formwork bag suspended from the roof of a roadway, with a composite material injection port on the flexible formwork bag; and a support structure disposed on both sides of the flexible formwork bag facing the roadway, the support structure comprising a first constraint structure, a second constraint structure, and a support assembly arranged sequentially away from the flexible formwork bag. This invention provides support force during the filling of the flexible formwork bag by suspending it from the roadway roof and arranging a support structure around it. The first constraint structure provides a first layer of support force during the filling of the flexible formwork bag, the second constraint structure provides a second layer of support force, and the support assembly ensures sufficient strength for the flexible formwork bag during filling.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to an underground sealed wall in a coal mine and its construction method. Background Technology

[0002] The goaf after mining underground contains various hazards such as gas and spontaneous combustion of coal. When mining activities are carried out in the next working face, the underground often adopts the method of constructing a closed wall to isolate the goaf from the potential hazards to coal mine safety production.

[0003] Currently, the existing underground sealing walls are mainly constructed using traditional methods of manually building brick and stone walls and filling with bagged yellow mud. This process has many drawbacks during construction, such as numerous construction procedures, high labor intensity, low work efficiency, poor overall integrity and airtightness of the sealing wall, and the problem of pressure cracking of the sealing wall, which leads to the failure of the sealing wall and cannot effectively seal the goaf completely.

[0004] Many mines have attempted to use new materials to construct sealed walls and have achieved good results, but many problems still exist: wood, natural stone, and polymer colloids are prone to water loss and air leakage, and have low pressure resistance; Marisan foam has low flame retardancy, decomposes at high temperatures and releases harmful gases, and is also relatively expensive; Rockwell foam overcomes the disadvantages of high temperature and low flame retardancy, but its use is limited due to the difficulty in controlling the curing time; Agroni foam overcomes the curing time problem and can quickly fill the sealed area, but it is not impact resistant, and with the increase in mechanization and mining depth, the ground pressure increases, the force between the sealing material and rock fissures and the interior of the sealed wall weakens, the sealing effect deteriorates, and it is more prone to air leakage, posing a great threat to safe production in the mine. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in related technologies. To this end, this invention proposes a sealed wall for underground coal mines, which involves suspending flexible formwork bags on the roof of the roadway and setting up supporting structures around the flexible formwork bags to provide support during filling. A first constraint structure near the flexible formwork bag is fixed to the roadway walls on both sides of the roadway, providing the first layer of support during filling. A second constraint structure is set on the first constraint structure or supporting components, providing the second layer of support during filling. The supporting components are located on the outer side away from the flexible formwork bag, ensuring sufficient strength support during filling. Furthermore, after the composite material solidifies, the supporting components on both sides of the flexible formwork bag can be removed, making full use of the existing mine support structure without wasting it. Moreover, the flexible formwork bag used in this example has large elastic deformation, ensuring the sealed wall is not prone to air leakage. Compared with rigid formwork, the flexible formwork formed in this example has advantages such as high strength, water permeability but no grout permeability, light weight, one-time molding, and convenient construction.

[0006] This invention also proposes a method for constructing sealed walls in underground coal mines.

[0007] According to a first aspect of the present invention, a coal mine underground sealing wall is disposed within a roadway for isolating a goaf; the sealing wall comprises:

[0008] A flexible molded bag is suspended from the roof of the tunnel, and the flexible molded bag is provided with a composite material injection port.

[0009] A support structure is respectively disposed on both sides of the flexible molded bag facing the tunnel. The support structure includes a first constraint structure, a second constraint structure and a support component disposed sequentially away from the flexible molded bag. The first constraint structure is disposed on the sidewall of the tunnel. The second constraint structure is fixed on the first constraint structure and / or the support component. The support component is disposed between the top plate and the bottom plate of the tunnel.

[0010] According to one embodiment of the present invention, the first constraint structure includes a plurality of steel strips, which are disposed between opposite roadway walls within the roadway, and the two ends of the steel strips are fixed to the roadway walls.

[0011] According to one embodiment of the present invention, the plurality of steel strips are arranged alternately.

[0012] According to one embodiment of the present invention, the steel strip is provided with a plurality of clamping components, the plurality of clamping components being adapted to clamp the second constraint structure.

[0013] According to one embodiment of the present invention, the second constraint structure is composed of a steel mesh cage.

[0014] According to one embodiment of the present invention, the steel mesh cage is formed by stacking and / or overlapping individual steel mesh sheets.

[0015] According to one embodiment of the present invention, the support assembly includes a plurality of individual support columns, which are spaced apart along the width direction of the tunnel.

[0016] According to one embodiment of the present invention, the composite material is a slurry formed by mixing two composite materials and adding water. The first composite material is made by grinding sulfoaluminate cement clinker as the base material, a suspending agent and a small amount of super retarder. The second composite material is made by grinding lime, gypsum, a suspending agent and a composite quick-setting early-strength agent. The water-solid ratio of the slurry is 1.0-4.0.

[0017] A method for constructing an underground sealed wall in a coal mine according to a second aspect of the present invention includes:

[0018] The flexible plastic bags are suspended from the ceiling of the tunnel.

[0019] The first constraint structure is set between the opposing sides of the tunnel in order to pre-fix the surrounding area of ​​the flexible mold bag.

[0020] A second constraint structure is provided on the first constraint structure and / or support component;

[0021] The support component is placed on the outside of the first constraint structure to provide secondary fixation around the flexible mold bag;

[0022] Connect the composite material pumping port to fill the flexible mold bag with the composite material.

[0023] According to one embodiment of the present invention, the step of suspending the flexible molded bag onto the roof of the tunnel includes:

[0024] The sides of the tunnel are excavated.

[0025] Transport the grouting pump, mixing tank, and filling materials to the designated location;

[0026] The filling slurry of the composite material is prepared according to a preset ratio.

[0027] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0028] Flexible formwork bags are suspended from the tunnel roof, and supporting structures are installed around them to provide support during filling. The first constraint structure, closest to the flexible formwork bag, is fixed to the tunnel walls on both sides, providing initial support during filling. A second constraint structure, located on the first constraint structure or supporting components, provides secondary support. The supporting components are positioned on the outer side, away from the flexible formwork bag, ensuring sufficient strength for filling. Furthermore, after the composite material solidifies, the supporting components on both sides of the flexible formwork bag can be removed, fully utilizing and avoiding waste of the existing mine support structure. Moreover, the flexible formwork bag used in this example has significant elastic deformation, ensuring the sealed wall is not prone to air leakage. Compared to rigid formwork, the flexible formwork formed in this example has advantages such as high strength, water permeability but grout impermeability, light weight, one-time molding, and convenient construction.

[0029] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of the underground sealed wall in a coal mine provided by the present invention;

[0032] Figure 2 This invention provides Figure 1 Schematic diagram of the structure of section AA in the middle;

[0033] Figure 3 This invention provides Figure 1 Schematic diagram of the structure of the middle BB section;

[0034] Figure 4 This is a schematic flowchart of the method for constructing underground sealed walls in coal mines provided by the present invention.

[0035] Figure 5 This invention describes the deformation of the roadway at measuring point #1 in a sealed underground coal mine wall.

[0036] Figure 6 This invention describes the deformation of the roadway at measuring point #2 in a sealed underground coal mine wall.

[0037] Figure 7 This invention describes the deformation of the roadway at measuring point #3 in a sealed underground coal mine wall.

[0038] Figure 8 This invention describes the stress condition of the filling body in the sealed wall of a coal mine.

[0039] Figure 9 The present invention provides the concentration of methane gas in front of the sealed wall in underground coal mines.

[0040] Figure 10 This invention relates to the pressure difference change inside and outside the sealed wall in an underground coal mine.

[0041] Figure label:

[0042] 100. Flexible molded bag; 200. Support structure; 201. First constraint structure; 202. Support component; 300. Gas pipeline. Detailed Implementation

[0043] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0044] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0045] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0046] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0047] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0048] This exemplary implementation first provides an underground sealing wall in a coal mine, which is installed in a roadway to isolate the goaf. For example... Figure 1As shown, the sealed wall includes a flexible mold bag 100 and a support structure 200.

[0049] A flexible molded bag 100 is suspended from the top plate of the tunnel, and a composite material injection port is provided on the flexible molded bag 100. Support structures 200 are respectively provided on both sides of the flexible molded bag 100 facing the tunnel. The support structure 200 includes a first constraint structure 201, a second constraint structure, and a support component 202 arranged sequentially away from the flexible molded bag 100. The first constraint structure 201 is provided on the tunnel wall, and the second constraint structure is fixed on the first constraint structure 201 and / or the support component 202. The support component 202 is provided between the top plate and the bottom plate of the tunnel.

[0050] In this example, the flexible formwork bag 100 is suspended from the tunnel roof to form a flexible filling template. The flexible formwork bag 100 is generally made of high-strength fiber cloth, possessing advantages such as high strength, water permeability but no grout permeability, light weight, one-time molding, and convenient construction. The flexible formwork bag 100 is typically suspended from the tunnel roof using φ22mm×2400mm hanging anchor rods, with an 800mm spacing between the anchor rods. Filling material is directly poured into the flexible formwork bag 100, and the filling material solidifies to form a sealed wall. Because the flexible formwork bag 100 is elastic, it is prone to tilting during filling material pouring; therefore, a support structure 200 is required on the outside of the flexible formwork bag 100 to provide lateral support.

[0051] The support structure 200 is positioned on the front and rear sides of the flexible molded bag 100 in the tunnel passage. Furthermore, the support structure 200 includes a first constraint structure 201, a second constraint structure, and a support assembly 202, sequentially located away from the flexible molded bag 100. The first constraint structure 201 can be configured as a constraint band, with both ends fixed to the tunnel walls on either side. The constraint band can be horizontally positioned or inclined at a certain angle; no restrictions are imposed here. The constraint band provides the first layer of constraint for the flexible molded bag 100.

[0052] The second constraint structure can be a steel mesh, which can be placed on the constraint band or on the support component 202. There are no restrictions on this. The steel mesh can provide a second layer of constraint for the flexible formwork 100.

[0053] The support component 202 can be set as a single hydraulic prop, steel column or wooden column. The support component 202 is set between the top plate and the bottom plate of the tunnel. On the one hand, it fixes the second constraint structure, and on the other hand, it provides a third layer of constraint for the flexible mold bag 100 to ensure the stability of the flexible mold bag 100 when filling material is injected.

[0054] It should be noted that gas pipelines need to pass through the sealed wall in this example. Therefore, before pouring, through holes need to be made in the flexible formwork 100 to pre-embed the gas pipelines.

[0055] In this embodiment, a flexible formwork bag 100 is suspended from the roof of the roadway, and a support structure 200 is provided around the flexible formwork bag 100 to provide support during filling. A first constraint structure 201, located near the flexible formwork bag 100, is fixed to the roadway walls on both sides of the roadway, providing a first layer of support during filling. A second constraint structure is located on the first constraint structure 201 or a support component 202, providing a second layer of support during filling. The support component 202 is located on the outer side away from the flexible formwork bag 100, ensuring sufficient strength support during filling. Furthermore, after the composite material solidifies, the support components 202 on both sides of the flexible formwork bag 100 can be removed, making full use of the existing mine support structure without wasting it. Moreover, the flexible formwork 100 used in this example has a large elastic deformation, ensuring that the sealed wall is not prone to air leakage. Compared with rigid formwork, the flexible formwork formed in this example has the advantages of high strength, water permeability but no grout permeability, light weight, one-time molding and convenient construction.

[0056] The following will refer to Figures 1 to 3 The structure of each part of the underground sealed wall in the coal mine described in this example embodiment will be explained in more detail.

[0057] like Figure 2 As shown, in one embodiment, the first constraint structure 201 includes multiple steel strips, which are disposed between opposite roadway walls within the roadway, and the two ends of the steel strips are fixed to the roadway walls.

[0058] Specifically, the first constraint structure 201 mainly provides the first layer of support during flexible formwork filling. Multiple steel strips in the first constraint structure 201 are positioned between the two sides of the tunnel, and the ends of the steel strips can be connected to rivets to fix them to the tunnel sides. The multiple steel strips can be arranged horizontally or at a certain angle to each other; there are no restrictions. The horizontally arranged steel strips can form a network with the support components 202 arranged vertically on the outer side, thereby further improving the support force during flexible formwork filling.

[0059] In one embodiment, the multiple steel strips are arranged in an alternating pattern. Specifically, the alternating steel strips can restrain each other to provide support force during the filling of the flexible plastic bag 100.

[0060] In one embodiment, the steel strip is provided with a plurality of clamping assemblies, the plurality of clamping assemblies being adapted to clamp the second constraint structure.

[0061] Specifically, the clamping component can be a gripper, with one end threaded onto the steel strip and the other end clamped by two clamping plates. After the steel strip is fixed in the tunnel wall, the second constraint structure can be manually clamped and fixed using the clamping component. Alternatively, the second constraint mechanism can be tied to the steel strip with wire; the specific fixing method is not limited here.

[0062] In one embodiment, the second constraint structure consists of a steel mesh cage.

[0063] In one embodiment, the steel mesh cage is formed by stacking and / or overlapping individual steel mesh sheets.

[0064] When stacking individual steel mesh sheets, two sets of steel mesh sheets are first set vertically relative to each other. Multiple steel mesh sheets are then stacked between these two sets, with the spacing between the stacked sheets less than a certain distance to improve structural strength. When overlapping individual steel mesh sheets, two sheets are set vertically and overlapped horizontally and vertically. The overlap can be connected using wire binding. To ensure the steel mesh sheets are securely bound, the mesh openings must be connected at intervals.

[0065] like Figure 2 and Figure 3 As shown, in one embodiment, the support component 202 includes a plurality of individual support pillars, which are spaced apart along the width direction of the tunnel.

[0066] For example, a single prop can be a hydraulic prop, a steel prop, or a wooden prop; there are no restrictions. To ensure support strength, the spacing between two adjacent single props can be set to 800mm. The specific number of single props on one side can be set according to the actual width of the roadway; there are no restrictions.

[0067] In one embodiment, the composite material is a slurry made by mixing two composite materials and adding water. The first composite material is made by grinding sulfoaluminate cement clinker as the base material, a suspending agent and a small amount of super retarder. The second composite material is made by grinding lime, gypsum, a suspending agent and a composite quick-setting and early-strength agent. The water-solid ratio of the slurry is 1.0-4.0.

[0068] The composite material used is a high-water-cement-rate material, and different water-cement ratios can be selected according to different filling strength requirements. During construction, the two composite materials are mixed separately to form a slurry with a water-to-solid ratio of 1.0-4.0, and then transported to the filling area through pipelines. When the two composite materials come together, they solidify rapidly.

[0069] The high-water-rate, rapid-setting, quick-fill sealing material used in this example combines the advantages of organic and inorganic polymer fillers while overcoming their respective shortcomings. It exhibits characteristics such as early strength and rapid hardening, and can be configured in appropriate proportions to meet different needs. The material shows minimal volumetric strain after solidification, is incompressible under stress, and possesses excellent load-bearing capacity, water retention, and resistance to explosive impacts. The material allows for the extensive use of mine water, significantly reducing drainage costs and resulting in substantial economic, environmental, and social benefits.

[0070] The practical application effect of the underground sealing wall in this example is as follows:

[0071] To observe the deformation of the sealed wall in the goaf, measuring points 1#, 2#, and 3# were set up in front of the sealed wall in the connecting roadway using a "cross" layout method. For ease of setting up and measuring, measuring points were placed 50mm in front of the sealed wall. The amount of roadway approach was used as the deformation of the sealed wall for measurement and recording. The coal wall closer to the opening cut in the connecting roadway was designated as the left side, and the coal wall closer to the stop line was designated as the right side. The amount and velocity of approach of the two sides, roof, and floor of the roadway were observed. The measurement results are as follows: Figure 5 , Figure 6 , Figure 7 As shown.

[0072] from Figure 5 , Figure 6 , Figure 7 It can be seen that: the total approach distance of the two sides of the roadway at measuring point #1 is 148mm, of which the approach distance of the left coal side is 77mm, accounting for 47.3% of the total approach distance of the two sides, and the approach distance of the right coal side is 78mm, accounting for 52.7% of the total approach distance of the two sides; the total approach distance of the roof and floor is 223mm, of which the approach distance of the roof is 100mm, accounting for 44.84% of the total approach distance of the roof and floor, and the approach distance of the floor is 123mm, accounting for 55.16% of the total approach distance of the roof and floor. The maximum approach velocity of the left side is 15mm / d, the maximum approach velocity of the right side is 15mm / d, the maximum approach velocity of the roof is 24mm / d, and the maximum approach velocity of the floor is 35mm / d.

[0073] The total approach distance of the two sidewalls in the No. 2 measuring point roadway is 150 mm, of which the left sidewall approached by 70 mm (46.67% of the total approach distance) and the right sidewall approached by 80 mm (53.33% of the total approach distance). The total approach distance of the roof and floor is 217 mm, of which the roof approached by 95 mm (43.78% of the total approach distance) and the floor approached by 122 mm (56.22% of the total approach distance). The maximum approach velocity of the left sidewall is 15 mm / d, and the maximum approach velocity of the right sidewall is 18 mm / d. The maximum approach velocity of the roof is 25 mm / d, and the maximum approach velocity of the floor is 30 mm / d.

[0074] The total approach distance of the two sidewalls of the No. 3 measuring point roadway was 188 mm, of which the left sidewall approached by 84 mm, accounting for 45.52% of the total approach distance, and the right sidewall approached by 79 mm, accounting for 54.48% of the total approach distance. The total approach distance of the roof and floor was 212 mm, of which the roof approached by 96 mm, accounting for 45.28% of the total approach distance, and the floor approached by 116 mm, accounting for 54.72% of the total approach distance. The maximum approach velocity of the left sidewall was 10 mm / d, and the maximum approach velocity of the right sidewall was 12 mm / d. The maximum approach velocity of the roof was 18 mm / d, and the maximum approach velocity of the floor was 20 mm / d.

[0075] Measurements from measuring points 1, 2, and 3 show that the roadway deformation exhibits a similar pattern. In terms of approach distance, the roadway floor moves the largest distance, followed by the roof, then the right coal face, with the left coal face moving the smallest. Regarding approach velocity, while there are fluctuations, the overall approach velocity shows a decreasing trend.

[0076] After the sealed wall lags behind the working face by 150m, the movement of the top and bottom plates and the two sidewalls basically stops increasing, and the movement speed is less than 1mm / d. At this time, the deformation of the roadway near the sealed wall is very small, the roadway basically tends to be stable, and the sealed wall will no longer experience large compressive deformation.

[0077] The stress and deformation of the sealed wall are as follows: In order to observe the stress and deformation of the sealed wall during the mining process, a stress gauge for the filling body is installed inside the filling body to monitor the stress changes of the filling body.

[0078] When suspending the flexible manhole cover 100, place the filling stress sensor 500mm below the center of the flexible manhole cover 100. The sensor must be fixed firmly and stably, with the pressure-bearing surface facing upwards. The sensor data transmission line passes through the hole in the tie rod and exits the flexible manhole cover 100 to connect to the storage device. After the filling material solidifies, the filling sensor is fixed inside the filling material. Data is collected using a handheld data acquisition device. The measurement results are as follows: Figure 8 As shown.

[0079] The stress conditions of the filling material are shown in Table 1 below:

[0080] Table 1. Stress conditions of the filling material

[0081]

[0082] from Figure 8As shown in Table 1, the stress increase in the filling material was most significant from the completion of the sealed wall (50m behind the working face) to 84m behind the working face, increasing from 0.1MPa to 5.4MPa, with an average growth rate of 0.221MPa / m. At this time, the filling material had only been established for a short time, and the roof quickly compacted the filling material, causing a sharp increase in internal stress. From 84m behind the working face to 138m behind the working face, the stress increase in the filling material slowed down, reaching 6.3MPa, with an average growth rate of only 0.0141MPa / m. From 138m behind the working face to 182m behind the working face, the stress in the filling material increased by only 0.1MPa, indicating that the internal stress of the filling material had basically reached equilibrium and the filling material was under stable stress.

[0083] The stress monitoring results of the sealed wall show that the stress on the wall has basically stabilized after 140m behind the working face. At this time, there is no large deformation of the wall, indicating that the sealed wall is effective.

[0084] The wall sealing performance test results are as follows: After the sealing wall in the goaf is constructed, the sealing performance of the sealing wall should be observed regularly. The sealing performance test is divided into gas content test and pressure difference test inside and outside the sealing wall test.

[0085] The methane concentration in front of the sealed wall is shown in Table 2 below:

[0086] Table 2 Gas Concentration in Front of the Sealed Wall

[0087]

[0088] The gas concentration detection results are as follows:

[0089] After the sealed wall was constructed, the methane concentration in front of the sealed wall was monitored daily. The methane content measurement results in front of the sealed wall 60 days after its completion are shown below. Figure 9 .

[0090] from Figure 9 As can be seen, after the sealing wall was constructed, the gas content in front of the wall varied between 0.2% and 0.4%, which was basically consistent with the gas content in Table 2. There was no phenomenon of gas leakage from the goaf through the sealing wall.

[0091] The pressure difference test results inside and outside the sealed wall are as follows:

[0092] A stainless steel pipe was installed on the sealed wall, and a U-shaped differential pressure gauge was connected externally to measure the pressure difference between the inside and outside of the sealed wall. The measurement results are shown below. Figure 10 .

[0093] from Figure 10 It can be seen that after the airtight wall was built, the pressure difference between the inside and outside of the wall was basically maintained between 10-20 Pa, and there was no significant decrease in the pressure difference, indicating that the wall had good airtightness and there was no air leakage.

[0094] The comprehensive monitoring and analysis from these three aspects show that the sealed wall in the goaf constructed using new materials, equipment, and processes has a good sealing effect and has achieved the expected results. See Table 3 below:

[0095] Table 3 Pressure difference between inside and outside the sealed wall

[0096]

[0097]

[0098] This example implementation also provides a method for constructing an underground sealed wall in a coal mine, such as... Figure 4 As shown, this method is used to construct a sealed wall in the underground coal mine, and the method includes:

[0099] Step S101: Suspend the flexible mold bag 100 onto the roof of the tunnel;

[0100] Step S102: The first constraint structure 201 is set between the opposite sides of the tunnel in the tunnel to pre-fix the surrounding area of ​​the flexible mold bag 100.

[0101] Step S103: Set a second constraint structure on the first constraint structure 201 and / or support component 202;

[0102] Step S104: The support component 202 is placed on the outside of the first constraint structure 201 to provide secondary fixation around the flexible mold bag 100.

[0103] Step S105: Connect the composite material pumping port to fill the flexible mold bag 100 with the composite material.

[0104] The position of the flexible molded bag 100 in this embodiment, as well as the positions of the first constraint structure 201, the second constraint structure and the support component 202, can be understood with reference to the above embodiments, and will not be repeated here.

[0105] However, it should be understood that step S101 also includes step S1011, grooving the sides of the roadway; step S1012, transporting the grouting pump, mixing tank and filling material to the designated location; and step S1013, configuring the filling slurry of the composite material according to the preset ratio.

[0106] The construction process for the sealed wall can be as follows: First, the grouting pump station is set up. One dual-liquid grouting pump with a flow rate of 30L / min is used. One mixing tank is provided for each of the first and second composite materials, each with a volume of 1.0m³. A material yard is located near the mixing tanks. To facilitate material transportation, the pump station should be located in a roadway accessible to auxiliary transport vehicles, with a width of not less than 3.5m.

[0107] The second step is trenching and formwork erection. Before construction, the loose coal and debris near the sealed wall are cleaned up. Trenching is carried out on both sides for 300mm, ensuring the hard sides and bottom are exposed. Considering the tunnel cross-section width × height = 3000mm × 2600mm at the location of the flexible formwork sealed wall in the example coal mine, and taking into account the 300mm trench depth and the required thickness of the sealed wall (1500mm), the actual dimensions of the required flexible formwork are determined to be width × height × thickness = 4000mm × 2900mm × 1700mm, with any excess material left in the trench around the tunnel. After trenching, the walls are reinforced with single hydraulic supports (7 supports per side, spaced 800mm apart) and reinforced with steel mesh. Flexible formwork bags 100 are then placed and suspended. The upper part of the flexible formwork bags 100 is suspended from the tunnel roof using φ22mm × 2400mm formwork anchors, with an 800mm spacing between the anchors.

[0108] The third step is to test the system. After setting up the flexible formwork bag 100, first use clean water to test whether the mixing tank, grouting pump, filling pipeline, and the connection between the filling point and the pump station are normal. Only after everything is normal can the grout be filled.

[0109] The fourth step is feeding and mixing. Add water and materials according to the designed water volume, and mix for at least 5 minutes. The slurry can only be pumped after it is thoroughly mixed.

[0110] Step 5: Pumping and Cleaning Equipment. Place the suction head of the grouting pump into the well-mixed grout and start the pump. During pumping, ensure the amounts of the first and second composite material grouts are equal. If they are not equal, clean the equipment promptly and investigate the cause. After pumping the grout, promptly pump clean water to clean the grouting pump, mixing tank, and pipelines.

[0111] The flexible formwork pumping technology used in this example fully utilizes on-site conditions to improve construction speed and reduce labor intensity. This solves the problems of poor sealing effect and low construction efficiency in constructing sealing walls to isolate goaf areas in coal mines. The flexible formwork sealing wall for isolating goaf areas constructed using this method has a simple construction process, fast construction speed, low labor intensity, and good sealing effect. Due to its ease of on-site operation and low support cost, it has broad application prospects.

[0112] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A sealed wall for underground coal mines, characterized in that, The sealed wall is installed inside the roadway to isolate the goaf; the sealed wall includes: A flexible molded bag is suspended from the roof of the tunnel, and the flexible molded bag is provided with a composite material injection port. A support structure is respectively disposed on both sides of the flexible molded bag facing the tunnel. The support structure includes a first constraint structure, a second constraint structure and a support component disposed sequentially away from the flexible molded bag. The first constraint structure is disposed on the sidewall of the tunnel. The second constraint structure is fixed on the first constraint structure and / or the support component. The support component is disposed between the top plate and the bottom plate of the tunnel. The first constraint structure includes multiple steel strips, which are arranged between opposite roadway walls within the roadway, and the two ends of the steel strips are fixed to the roadway walls. A stress sensor for the filling material is installed inside the flexible mold bag to monitor changes in the stress on the filling material. The second constraint structure consists of a steel mesh cage; The support assembly includes multiple individual support pillars, which are spaced apart along the width direction of the tunnel.

2. The underground sealed wall in a coal mine according to claim 1, characterized in that, The multiple steel strips are arranged alternately.

3. The underground sealed wall in a coal mine according to claim 1, characterized in that, The steel strip is provided with a plurality of clamping components, which are adapted to clamp the second constraint structure.

4. The underground sealed wall in a coal mine according to claim 1, characterized in that, The steel mesh cage is formed by stacking and / or overlapping individual steel mesh sheets.

5. The underground sealing wall in a coal mine according to any one of claims 1 to 4, characterized in that, The composite material is a slurry made by mixing two composite materials and adding water. The first composite material is made by grinding sulfoaluminate cement clinker as the base material, a suspending agent and a small amount of super retarder. The second composite material is made by grinding lime, gypsum, a suspending agent and a composite quick-setting and early-strength agent. The water-solid ratio of the slurry is 1.0-4.

0.

6. A method for constructing an underground sealed wall in a coal mine, applicable to the underground sealed wall in a coal mine as described in any one of claims 1 to 5, characterized in that, include: The flexible plastic bags are suspended from the ceiling of the tunnel. The first constraint structure is set between the opposing sides of the tunnel in order to pre-fix the surrounding area of ​​the flexible mold bag. A second constraint structure is provided on the first constraint structure and / or support assembly; the first constraint structure includes multiple steel strips, which are arranged between opposite roadway walls within the roadway, and the two ends of the steel strips are fixed to the roadway walls; the second constraint structure is composed of a steel mesh cage; the support assembly includes multiple individual support columns, which are spaced apart along the width direction of the roadway. The support component is placed on the outside of the first constraint structure to provide secondary fixation around the flexible mold bag; Connect the composite material pumping port to fill the flexible mold bag with the composite material; Regularly monitor the airtightness of the sealed wall. The airtightness test is divided into gas content test and pressure difference test inside and outside the sealed wall.

7. The method for constructing an underground sealed wall in a coal mine according to claim 6, characterized in that, The step of suspending the flexible plastic bag onto the roof of the tunnel includes: The sides of the tunnel are excavated. Transport the grouting pump, mixing tank, and filling materials to the designated location; The filling slurry of the composite material is prepared according to a preset ratio.

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