A method for filling and connecting the top of a mine goaf

Abstract

The present invention relates to the technical field of filling goaf, and specifically to a method for filling and connecting the top of a goaf in a mine. The filling and connecting method uses a three-dimensional flexible geotextile as the skeleton of the filling body, and the two opposite sides of the three-dimensional flexible geotextile are respectively provided with floats and sinkers, and one end of the three-dimensional flexible geotextile is provided with a cloth surface; the specific filling and connecting method includes the following steps: fixing one end of the three-dimensional flexible geotextile to the wall surface of the filling and connecting area, injecting slurry into the filling and connecting area, and pushing the cloth surface of the three-dimensional flexible geotextile to move along the moving direction of the slurry; as the slurry liquid level rises, the three-dimensional flexible geotextile is unfolded under the action of the float and sinker to form a three-dimensional frame structure in the filling and connecting area; a foaming agent is added to the slurry to make the slurry foam and expand to the top plate of the goaf to achieve self-connection. The method of the present invention enhances the stability of the connecting area and solves the problems of low filling and connecting rate of ordinary filling materials and difficulty in secondary connecting and filling.

Description

Technical Field

[0001] The invention belongs to the technical field of goaf filling, and in particular relates to a method for filling and connecting the top of a goaf in a mine. Background Art

[0002] When the ore is mined from underground, the space originally supported by the ore becomes a goaf, and the surrounding rocks may shift or collapse due to the loss of support. Therefore, filling the goaf with backfill is used to manage ground pressure, control surrounding rock collapse and surface movement, which has the advantages of high ore recovery rate, low depletion rate, safer operation, utilization of industrial waste, and protection of the surface.

[0003] Backfill mining has become a major trend in the development of mineral resources. However, during the backfilling process, the backfill is often difficult to fully connect to the top due to many factors, such as the water seepage of the backfill slurry, the gravity slope of the backfill slurry, the irregular shape of the mine roof, and the natural settlement of the backfill.

[0004] At present, two approaches are often used: improving engineering measures to force the roof connection and developing self-joining with expandable filling materials. Most of the forced roof connection processes are relatively complicated, with a long construction period, certain safety risks, and great difficulty in actual operation. When using expandable filling materials for roof connection, a certain amount of foaming agent is added to make the slurry foam to achieve the expansion effect. However, since the foam filling body is a foam structure with low strength, it is easy to cause a major safety hazard of filling body collapse in the later stage.

[0005] In order to solve the problem that the filling body is difficult to fully connect to the top, it is necessary to provide a method for filling and connecting the top of mine goaf using expandable filling materials, to reinforce the strength of the expandable filling body, and to eliminate the major safety hazard of filling body collapse on the basis of solving the problem that the filling body is often difficult to fully connect to the top. Summary of the invention

[0006] In order to solve the problems of low filling and top connection rate of common filling materials and difficulty in secondary filling and top connection, the purpose of the present invention is to provide a mine goaf filling and top connection method using expandable filling materials.

[0007] The present invention aims to utilize a mixture of cement mortar and additives as slurry, fill the goaf by injecting the slurry, and utilize the thrust of the slurry to drive the three-dimensional flexible geotextile to move forward and upward, so that the three-dimensional flexible geotextile forms a three-dimensional frame structure in the filling and top connection area after the three-dimensional flexible geotextile is unfolded; then, a certain amount of foaming agent is added to allow the slurry to foam and expand until the top plate of the goaf is self-connected, thereby effectively improving the top connection rate of the filling and top connection area of ​​the goaf, and at the same time reinforcing the strength of the expandable filling body.

[0008] Moreover, the three-dimensional frame structure formed after the three-dimensional flexible geotextile is unfolded plays a frame support role for the filling body, enhances the overall strength of the top filling body, eliminates the major safety hazard of filling body collapse, improves the filling and top connection process of the goaf area, and reduces the safety risks of personnel in the work process.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows.

[0010] The present invention provides a method for filling and connecting a mine goaf, which is performed by using a three-dimensional flexible geotextile. Two opposite sides of the three-dimensional flexible geotextile are respectively provided with a float and a sinker, and one end of the three-dimensional flexible geotextile is provided with a cloth surface. The specific filling and connecting method comprises the following steps:

[0011] Placing a three-dimensional flexible geotextile in the filling and top-joining area, and fixing one end of the three-dimensional flexible geotextile away from the fabric surface to the wall surface of the filling and top-joining area;

[0012] Mix cement mortar and additives as slurry, inject the slurry into the filling and top-joining area, and push the surface of the three-dimensional flexible geotextile to move along the moving direction of the slurry; as the slurry liquid level rises, the three-dimensional flexible geotextile is unfolded under the action of floats and sinkers to form a three-dimensional frame structure in the filling and top-joining area;

[0013] A foaming agent is added into the slurry to make the slurry foam and expand until the top plate of the goaf is self-connected.

[0014] In a preferred embodiment, the float is a hollow floating ball, and the sinker is a solid sinker. The float is distributed on the top surface of the three-dimensional flexible geonet, and the sinker is distributed on the bottom surface of the three-dimensional flexible geonet. The float is arranged on the side of the three-dimensional flexible geonet close to the top plate of the goaf, and the sinker is arranged on the side of the three-dimensional flexible geonet away from the top plate of the goaf. As a result, as the slurry is injected into the filling and top area, the float moves upward under the action of buoyancy, and the sinker remains on the bottom surface of the filling and top area under the action of gravity; as the slurry liquid level rises, the three-dimensional flexible geonet unfolds under the action of the float and the sinker, and forms a three-dimensional frame structure in the filling and top area.

[0015] In a preferred embodiment, the calculation formula for the number of floats is:

[0016]

[0017] Where n is an integer, m 网 is the mass of the three-dimensional flexible geotextile, ρ 浆 is the density of the slurry, r is the radius of the float. By selecting the appropriate number of floats, the three-dimensional flexible geotextile can be expanded in the vertical direction.

[0018] In a preferred embodiment, the number of floats is

[0019] In a preferred embodiment, the number of floats with a radius of 5 cm is 3 to 4 per cubic volume of slurry.

[0020] In a preferred embodiment, the sinker has a density of 7 g / cm 3 , a solid metal sphere with a radius of 3cm. By selecting the appropriate sinker and the number of sinkers, and coordinating with the floater, the three-dimensional flexible geotextile can be unfolded as the slurry level rises.

[0021] In a preferred embodiment, a sinker is arranged at intervals of 1 meter on the bottom surface of the three-dimensional flexible geotextile along the length and width directions to keep the bottom surface of the three-dimensional flexible geotextile at the bottom surface of the filling and top area.

[0022] In a preferred embodiment, the fabric material is a lightweight fabric material with a fabric density of (0.6-0.7)ρ 浆 .

[0023] In a preferred embodiment, the filling height of the slurry is 2 / 3 to 3 / 4 of the filling top area.

[0024] In a preferred embodiment, the foaming agent and the slurry are mixed to form an expandable filling material;

[0025] The mass percentage of the foaming agent in the expandable filling material is determined according to the volume expansion rate of the slurry; the calculation formula of the volume expansion rate of the slurry is:

[0026]

[0027] Wherein, η is the volume expansion rate of the slurry, h0 is the initial height of the top connection area, and h1 is the remaining height of the top connection area after filling with slurry.

[0028] In a preferred embodiment, when the volume expansion rate of the slurry is 60%, the amount of the foaming agent is 22% to 26%;

[0029] When the volume expansion rate of the slurry is 40%, the amount of foaming agent is 17% to 20%;

[0030] When the volume expansion rate of the slurry is 20%, the amount of the foaming agent is 12% to 15%.

[0031] The mass percentage of the foaming agent in the expandable filling material is determined by the volume expansion rate of the slurry to ensure that the slurry foams and expands to the top of the goaf area.

[0032] In a preferred embodiment, the three-dimensional flexible geonet is a three-dimensional mesh structure formed by horizontally and vertically twisting a flat mesh; the material of the flat mesh is a flexible mesh material.

[0033] In a preferred embodiment, the spacing distance of the planar woven meshes in the transverse direction is 0.1-0.4 m, and the spacing distance of the planar woven meshes in the longitudinal direction is 0.1-0.4 m.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention utilizes the thrust of the slurry to drive the three-dimensional flexible geotextile to move forward and upward, so that the three-dimensional flexible geotextile forms a three-dimensional frame structure in the filling and top connection area after the three-dimensional flexible geotextile is unfolded; then a certain amount of foaming agent is added to allow the slurry to foam and expand to the top of the goaf area, effectively improving the top connection rate of the filling and top connection area of ​​the goaf, while improving the strength of the expandable filling body; it has the advantages of high filling and top connection rate, simple top connection process, small top connection engineering workload, and good safety.

[0036] 2. The present invention also uses a three-dimensional frame structure formed by unfolding the three-dimensional flexible geotextile to provide frame support for the filling body, thereby enhancing the overall strength of the top-connected filling body, eliminating the major safety hazard of filling body collapse, improving the filling and top-connecting process of the goaf area, and reducing safety risks for personnel during work. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 (A) is the layout diagram of the three-dimensional flexible geotextile in the filling and top-connecting area of ​​the goaf; Figure 1 (B) is the development diagram of the three-dimensional flexible geotextile as the slurry is injected; Figure 1 (C) is the state diagram of slurry injection completion; Figure 1 (D) is a diagram showing the foaming effect of the slurry after the foaming agent is injected into the slurry.

[0038] Figure 2 A schematic structural diagram of a three-dimensional flexible geonet provided in one embodiment of the present invention.

[0039] In the figure, 1. filling top area; 2. slurry filling pipe; 21. slurry injection port; 3. three-dimensional flexible geotextile; 31. flat mesh; 4. traction rope; 5. cloth surface; 6. float; 7. sinker. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0042] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0043] Unless otherwise specified, the methods described in the following examples are all conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0044] In the following embodiments, the goaf connecting area is the area above the void formed after the ore body is mined during mining activities and in contact with the top rock. Specifically, when the minerals are mined from underground, the space originally supported by the minerals becomes hollow, and the surrounding rocks may shift or collapse due to the loss of support; these collapsed rocks will eventually contact the rock layer above the mine hole, forming a relatively stable structure. This area composed of collapsed rocks and the upper rock layer is called the "connecting area". Figure 1 The bottom of the goaf connecting the top area is the lower filling body, and the top of the goaf connecting the top area is the mining field roof. There are multiple pillars erected vertically on both sides. One end of the pillar is fixed by the lower filling body, and the other end of the pillar is abutted against and fixed on the mining field roof to support the mining field roof.

[0045] In the following embodiments, Figure 1 The filling and top connection area 1 is the top connection area of ​​the mine goaf to be filled. A slurry filling pipe 2 is penetrated through one end of the wall of the filling and top connection area 1. One end of the slurry filling pipe 2 penetrates the filling and top connection area 1 and is provided with a slurry injection port 21.

[0046] In the following embodiments, the method for filling the mine goaf and the top area is carried out using a three-dimensional flexible geotextile. Figure 1 and 2The three-dimensional flexible geonet 3 is a three-dimensional mesh structure composed of a plane mesh 31 twisted horizontally and vertically. A traction rope 4 is connected to one end of the top of the three-dimensional flexible geonet 3, and one end of the traction rope is fixedly connected to a side wall of the filling top area close to the slurry injection port 21. A cloth surface 5 is fixed to the plane mesh 31 of the three-dimensional flexible geonet 3 away from one end of the traction rope. The material of the cloth surface can be canvas. Of course, cloth surfaces made of other materials can also be used according to actual needs, such as nylon cloth, cotton cloth, etc. The function of the cloth surface is to reduce the permeability of the slurry, so that as the slurry is injected, the driving force of the slurry can push the cloth surface forward. Therefore, the cloth surface is a lightweight woven material with a density of (0.6~0.7)ρ 浆 The material of the planar mesh is a flexible mesh material, such as a planar mesh woven from PET fiber ropes, such as Figure 2 .

[0047] The three-dimensional flexible geotextile 3 is made of soft material. It can be expanded upward and forward in the slurry under the fixation of the sinker 7 and the buoyancy of the floater 6 and the fabric 5. The expanded three-dimensional mesh structure strengthens the strength of the filling body after foaming. In the following embodiments, the dimensions of the three-dimensional flexible geotextile are 10m long, 8m wide and 5m high. Of course, the three-dimensional flexible geotextile of appropriate size can also be selected according to actual needs.

[0048] A plurality of floats 6 are fixed on the upper surface of the three-dimensional flexible geotextile 3. The floats 6 are hollow plastic floats with a radius of 5 cm, which are distributed at the nodes on the top surface of the three-dimensional flexible geotextile 3. The mass of the weighing net is used to calculate the number of floats 6 required. The calculation formula (1) for the number of floats 6 is: Where n is an integer, m 网 is the mass of the three-dimensional flexible geotextile, ρ 浆 is the density of the slurry, and r is the radius of the float. The function of the float 6 is to have an upward buoyancy in the expandable filling material, and to drive the mesh forward and upward under the thrust of the slurry injection. Therefore, the density of the float is less than the density of the expandable filling material. The present invention does not limit the shape of the float 6 to a sphere, but can also be other shapes, such as a regular polyhedron, such as a cube, a cuboid, a regular tetrahedron, a regular pentahedron, etc.; for example, an irregular polyhedron, such as an irregular hexahedron, an irregular octahedron, an irregular sphere-like body, etc., and a suitable shape can be selected according to actual needs.

[0049] A plurality of sinkers 7 are fixed to the lower surface of the three-dimensional flexible geotextile 3. The sinkers 7 are used to fix the bottom surface of the three-dimensional flexible geotextile 3. The sinkers 7 can be selected to have a density of 7 g / cm 3Tin balls with a radius of 3 cm are distributed at the nodes of the bottom surface of the three-dimensional flexible geotextile 3. A sinker 7 is set every one meter of the length and width of the bottom surface of the three-dimensional flexible geotextile 3 to fix the bottom surface of the three-dimensional flexible geotextile 3. Of course, in other embodiments, other counterweight spheres can also be used as sinkers 7, such as other metal balls, such as steel balls, iron balls, etc.; such as stone balls, cement balls, etc. The selection of the sphere is mainly to facilitate the rolling of the sinker and drive the mesh forward under the thrust of the slurry injection.

[0050] In the following embodiments, the tailings include tailings products of various ore dressing plants, for example, iron ore tailings of iron ore dressing. The expansion agent is a calcium oxide expansion agent. The foaming agent is a 20% hydrogen peroxide solution. The quick setting agent is alumina clinker. The foam stabilizer is an alkyl alcohol amide (Jiangsu Hai'an, model CDEA). The lime-sand ratio is the mass ratio of cement to sand.

[0051] In the following embodiments of the present invention, the method for filling the top area of ​​the mine goaf mainly utilizes the injection thrust of the slurry to push the cloth surface to move, while driving the sinker to remain in translation on the bottom surface, and the float floats upward and moves with the movement of the cloth surface. As a result, the cloth surface on one side of the three-dimensional flexible geotextile drives the vertical mesh forward under the action of the buoyancy of the float and the thrust of the slurry injection. As the slurry liquid level rises, the upper float of the three-dimensional flexible geotextile drives the lower mesh to expand upward and forward, forming a three-dimensional frame structure in the filling and top area. The initial height of the top area is set to h0, the remaining height of the top area after filling the slurry is h1, and the height of the filled slurry is h0-h1. The calculation formula (2) for calculating the volume expansion rate η of the slurry is: The remaining filling height and the proportion of the foaming agent in the expandable filling material are determined according to the volume expansion rate.

[0052] Example 1

[0053] A method for filling and connecting a mine goaf, comprising the following steps:

[0054] (1) Determine the spatial dimensions of the area to be filled and connected to the top; based on the spatial dimensions of the area to be filled and connected to the top, select a three-dimensional flexible geotextile with dimensions of 10 m in length, 8 m in width, and 5 m in height.

[0055] Determine the proportion of the expansive filling material, which is a mixture of cement mortar, additives and foaming agents. In terms of mass percentage, the proportion of the expansive filling material is: 60-70% cement mortar, 5%-8% expansive agent, 3%-5% accelerator, 1%-3% foam stabilizer, and 16%-20% foaming agent. The cement mortar is a mixture of cement, sand and water, the cement is silicate cement, the sand is tailings, the cement mortar has a lime-sand ratio of 1 / 4-1 / 10, and the slurry concentration is 60%-75%. Evenly mix the cement mortar and additives to form the slurry.

[0056] The density of the slurry is obtained according to the ratio of the expansion filling material, which is recorded as ρ 浆 ; The weight of the three-dimensional flexible geotextile is obtained by weighing, recorded as m 网 ; Calculate the number of floats n required according to the calculation formula (I) for the number of floats, and n is an integer. It is thus determined that the number of floats on the top surface of the three-dimensional flexible geotextile is 400 to 480, and the sinkers on the bottom surface of the three-dimensional flexible geotextile are arranged one sinker every 1 meter along the length and width directions, and the total number is calculated to be 80 to 96.

[0057] like Figure 2 , a certain number of floats are fixed on each node of the top surface of the three-dimensional flexible geotextile, a certain number of sinkers are fixed on each node of the bottom surface of the three-dimensional flexible geotextile, one end of the traction rope is fixed on one end of the top surface of the three-dimensional flexible geotextile, and the canvas is fixed on the other end of the three-dimensional flexible geotextile. The area of ​​the canvas matches the area of ​​the plane mesh at the other end of the three-dimensional flexible geotextile.

[0058] (2) Place the three-dimensional flexible geotextile mesh configured according to step (1) into the top-joining area to be filled, and fix the other end of the traction rope to a side wall of the top-joining area to be filled close to the slurry injection port.

[0059] (3) Mix cement mortar and additives evenly as slurry, and inject the slurry into the area to be filled and connected along the slurry injection port through the slurry filling pipe. The high-concentration slurry gradually accumulates, and the high-position slurry slides to the left, pushing the left canvas of the three-dimensional flexible geotextile. Under the thrust of the slurry, the left sinker is driven forward, and the three-dimensional flexible geotextile is unfolded forward. At the same time, the float drives the three-dimensional flexible geotextile to unfold upward under the buoyancy. At this time, the left canvas of the three-dimensional flexible geotextile drives the net forward under the buoyancy of the float and the thrust of the slurry injection. As the slurry liquid level rises, the upper float of the three-dimensional flexible geotextile drives the lower net to unfold upward and forward, forming a three-dimensional frame structure in the filling and connection area, such as Figure 1 (A)~ Figure 1 (C) shown.

[0060] (4) The slurry is filled to 2 / 3 to 3 / 4 of the top area of ​​the goaf, and a foaming agent is added to the filling top area. With the action of the foaming agent, the foaming volume of the slurry gradually increases. After the top is connected, it is squeezed upward and outward. The external rock mass constraint causes the internal porosity of the expansive filling body to decrease, thereby improving its mechanical strength. At the same time, the three-dimensional flexible geotextile plays a role in reinforcement after the slurry solidifies. Figure 1 (D) as shown.

[0061] Example 2

[0062] A method for filling a mine goaf and a top area, comprising the following steps:

[0063] (1) Determine the spatial dimensions of the area to be filled and connected to the top; based on the spatial dimensions of the area to be filled and connected to the top, select a three-dimensional flexible geotextile with dimensions of 12 m in length, 10 m in width, and 3 m in height.

[0064] Determine the proportion of the expansive filling material, which is a mixture of cement mortar, additives and foaming agents. In terms of mass percentage, the proportion of the expansive filling material is: 60-70% cement mortar, 5%-8% expansive agent, 3%-5% accelerator, 1%-3% foam stabilizer, and 16%-20% foaming agent. The cement mortar is a mixture of cement, sand and water, the cement is silicate cement, the sand is tailings, the cement mortar has a lime-sand ratio of 1 / 4-1 / 10, and the slurry concentration is 60%-75%. Evenly mix the cement mortar and additives to form the slurry.

[0065] The density of the slurry is obtained according to the ratio of the expansion filling material, which is recorded as ρ 浆 ; The weight of the three-dimensional flexible geotextile is obtained by weighing, recorded as m 网 ; Calculate the number of floats n required according to the calculation formula (I) for the number of floats, and n is an integer. It is thus determined that the number of floats on the top surface of the three-dimensional flexible geotextile is 360 to 430, and the sinkers on the bottom surface of the three-dimensional flexible geotextile are arranged one sinker every 1 meter along the length and width directions, and the total number is calculated to be 120 to 140.

[0066] like Figure 2 , a certain number of floats are fixed on each node of the top surface of the three-dimensional flexible geotextile, a certain number of sinkers are fixed on each node of the bottom surface of the three-dimensional flexible geotextile, one end of the traction rope is fixed on one end of the top surface of the three-dimensional flexible geotextile, and the canvas is fixed on the other end of the three-dimensional flexible geotextile. The area of ​​the canvas matches the area of ​​the plane mesh at the other end of the three-dimensional flexible geotextile.

[0067] (2) Place the three-dimensional flexible geotextile mesh configured according to step (1) into the top-joining area to be filled, and fix the other end of the traction rope to a side wall of the top-joining area to be filled close to the slurry injection port.

[0068] (3) Mix cement mortar and additives evenly as slurry, and inject the slurry into the area to be filled and connected along the slurry injection port through the slurry filling pipe. The high-concentration slurry gradually accumulates, and the high-position slurry slides to the left, pushing the left canvas of the three-dimensional flexible geotextile. Under the action of the slurry, the left sinker is driven forward, and the three-dimensional flexible geotextile is unfolded forward. At the same time, the float drives the three-dimensional flexible geotextile upward under the action of buoyancy. At this time, the left canvas of the three-dimensional flexible geotextile drives the net forward under the action of the buoyancy of the float and the thrust of the slurry injection. As the slurry liquid level rises, the upper float of the three-dimensional flexible geotextile drives the lower net to unfold upward and forward, forming a three-dimensional frame structure in the filling and connection area, such as Figure 1 (A)~ Figure 1 (C) shown.

[0069] (4) The slurry is filled to 2 / 3 to 3 / 4 of the top area of ​​the goaf, and a foaming agent is added to the filling top area. With the action of the foaming agent, the foaming volume of the slurry gradually increases. After the top is connected, it is squeezed upward and outward. The external rock mass constraint causes the internal porosity of the expansive filling body to decrease, thereby improving its mechanical strength. At the same time, the three-dimensional flexible geotextile plays a role in reinforcement after the slurry solidifies. Figure 1 (D) as shown.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for filling and connecting the top of a mine goaf, characterized in that: A three-dimensional flexible geotextile is used, wherein two opposite sides of the three-dimensional flexible geotextile are respectively provided with a float and a sinker, and one end of the three-dimensional flexible geotextile is provided with a cloth surface; the specific filling and top connection method comprises the following steps: Placing a three-dimensional flexible geotextile in the filling and top-joining area, and fixing one end of the three-dimensional flexible geotextile away from the fabric surface to the wall surface of the filling and top-joining area; Mix cement mortar and additives as slurry, inject the slurry into the filling and top-joining area, and push the surface of the three-dimensional flexible geotextile to move along the moving direction of the slurry; as the slurry liquid level rises, the three-dimensional flexible geotextile is unfolded under the action of floats and sinkers to form a three-dimensional frame structure in the filling and top-joining area; A foaming agent is added into the slurry to make the slurry foam and expand until the top plate of the goaf is self-connected.

2. The method for filling and connecting the mine goaf according to claim 1, characterized in that: The float is a hollow floating ball, and the sinker is a solid sinker.

3. The method for filling and connecting the mine goaf according to claim 1, characterized in that: The calculation formula for the number of floats is: Where n is an integer, m 网 is the mass of the three-dimensional flexible geotextile, ρ 浆 is the density of the slurry, and r is the radius of the float.

4. The method for filling and connecting the mine goaf according to claim 3 is characterized in that: The number of floats is 5. The method for filling and connecting the mine goaf according to claim 3 is characterized in that: The fabric is made of lightweight fabric with a density of (0.6-0.7)ρ 浆 .

6. The method for filling and connecting the mine goaf according to claim 1, characterized in that: The filling height of the slurry is 2 / 3 to 3 / 4 of the filling top area.

7. The method for filling and connecting the mine goaf according to claim 6, characterized in that: The foaming agent and the slurry are mixed to form an expandable filling material; The mass percentage of the foaming agent in the expandable filling material is determined according to the volume expansion rate of the slurry; the calculation formula of the volume expansion rate of the slurry is: Wherein, η is the volume expansion rate of the slurry, h0 is the initial height of the filling and top area; h1 is the remaining height of the top area after filling with slurry.

8. The method for filling and connecting the mine goaf according to claim 7, characterized in that: When the volume expansion rate of the slurry is 60%, the amount of foaming agent is 22% to 26%; When the volume expansion rate of the slurry is 40%, the amount of foaming agent is 17% to 20%; When the volume expansion rate of the slurry is 20%, the amount of the foaming agent is 12% to 15%.

9. The method for filling and connecting the mine goaf according to claim 1, characterized in that: The three-dimensional flexible geotextile mesh is a three-dimensional mesh structure formed by horizontally and vertically twisting a plane mesh; the material of the plane mesh is a flexible mesh material.

10. The method for filling and connecting the mine goaf according to claim 9, characterized in that: The interval distance of the planar woven nets along the transverse direction is 0.1 to 0.4 m, and the interval distance of the planar woven nets along the longitudinal direction is 0.1 to 0.4 m.

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