Non-pillar overlying strata separation layer grouting filling subsidence reduction method

Abstract

The invention discloses a coal-pillar-free overlying strata separation layer grouting filling subsidence reduction method. The method comprises the steps that the positions of all key layers in a panel range, grouting key layers in overlying strata, the breaking distance of the grouting key layers and the mining width of a first mining face are determined; determining equivalent mining width according to the allowable mining width of a grouting key layer by utilizing the fulcrum effect of a caving zone compaction area, calculating the maximum face length of a replacement working face, and determining the length of the replacement working face within the range of the face length to obtain an overlying strata separation layer filling mining system; no coal pillar is reserved between the working faces of the overlying strata separation layer filling mining system; stoping the first mining surface, and grouting the lower part of the key layer following the stoping; when the replacement working face is mined, grouting is conducted on the lower portion of the key layer of the replacement working face; the remaining working faces are subjected to separation layer grouting and filling mining in sequence until mining of the whole panel is completed; wherein no coal pillar is reserved between all the working faces. The grouting filling subsidence reduction effect is improved, the mine coal resource recovery rate is further increased, and the mining cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam mining, and in particular relates to a method for reducing subsidence by grouting and filling overburden separation layer without coal pillars. Background Art

[0002] With the increase in annual coal mining, the problem of surface structures compressing coal is becoming increasingly prominent. Existing overburden stratum grouting technology, which uses coal pillars to isolate the working face interval, is increasingly favored by coal mines due to its low cost, relatively independent mining and filling, and effective surface subsidence reduction. At the same time, to reduce resource waste, pillarless coal mining is becoming increasingly common in coal mining, which brings challenges to overburden stratum grouting subsidence reduction.

[0003] Grouting to reduce subsidence in overburden delamination without coal pillars breaks the theoretical basis for this approach, namely, the grouting support system with fixed-end beams. The mining technology of the working face has undergone significant changes. Since the adjacent goaf has lost its support pillars, the fundamental requirement for the fixed-end beam key stratum theory has been lost, leading to a rapid increase in the width of the grouting working face. According to the key stratum theory, the breaking distance of the grouting key stratum is often insufficient to support the mining width of both working faces. The formation of a cantilever beam is inevitable, resulting in poor subsidence reduction and the occurrence of secondary geological hazards such as surface slurry leakage. Summary of the Invention

[0004] To address the above technical issues, the present invention proposes a method for reducing subsidence by grouting the overburden separation layer without coal pillars at an equivalent mining width. This method creates a discontinuous separation layer structure, meeting the breaking distance requirements of the simply supported beams of the separation layer grouting, and thus achieving the goal of reducing subsidence by grouting the overburden separation layer without coal pillars. This method addresses the resource waste caused by the presence of coal pillars in existing overburden separation layer grouting technology and improves the recovery rate of the working face.

[0005] To achieve the above-mentioned object, the present invention provides a method for reducing subsidence by grouting and filling the overburden separation layer without coal pillars, comprising:

[0006] Determine the positions of all key layers within the panel area, the key grouting layers in the overburden, the breaking distance of the key grouting layers, and the width of the first mining face;

[0007] Based on the allowable mining width of the grouting key layer and the principle of the fulcrum effect of the compaction zone of the caving zone, the equivalent mining width is determined, the length of the successive working face is calculated, and the overburden stratum separation filling mining system is obtained; no coal pillars are left between the working faces of the overburden stratum separation filling mining system;

[0008] The first mining face is mined, and grouting is carried out on the lower part of the key layer immediately after mining;

[0009] When the replacement working face is mined, grouting is carried out on the lower part of the key layer of the replacement working face;

[0010] The remaining working faces are mined in sequence by grouting and filling until the entire panel area is mined; no coal pillars are left between all working faces.

[0011] Preferably, the tunnel arrangement mode of the coal pillar-free overburden separation grouting mining method is a gob-side tunneling arrangement mode.

[0012] Preferably, the height of the grouting key layer from the coal seam is greater than the sum of the height of the water-conducting fracture zone and the height of the safety isolation zone, and the key layer with the deepest burial depth of all key layers is selected as the grouting key layer.

[0013] Preferably, the formula for calculating the breaking distance of the grouting key layer is:

[0014]

[0015] Where: L1 is the critical layer fracture under grouting; δ1 is the tensile strength of the subcritical layer; h1 is the thickness of the subcritical layer; and q1 is the upper formation pressure that the critical layer withstands when not grouting.

[0016] Preferably, the formula for the width of the first mining surface is:

[0017] W k =L k +2H k / tanθ

[0018] Where: W k L is the maximum mining width allowed for the working face during grouting filling of the Kth key layer; K is the breaking distance of the key layer; H k is the distance between the key layer and the working face coal seam; θ is the fracture angle of the overlying rock stratum of the coal seam.

[0019] Preferably, the formula for determining the equivalent mining width based on the allowable mining width of the key grouting layer is:

[0020]

[0021] Where: ε is the injection-production ratio; L 等效 L is the equivalent cutting length of the working surface; 首采 The length of the cut at the first mining face; d sc The width of the air inlet chute between the first mining face and the successor working face is m; L 接替 The length of the eye cut to replace the working face.

[0022] Preferably, the formula for calculating the length of the replacement working surface is:

[0023]

[0024] Among them, the equivalent mining width value is the maximum mining width value allowed by the grouting key layer, dsc Layout dimensions of the pillar-free tunnel in the mine.

[0025] Preferably, the process of obtaining the overburden separation layer filling mining system includes:

[0026] The width of the successor working face is obtained by calculation, and the return air lane is arranged according to the width of the successor working face to obtain the first mining face mining system and the "Y" type ventilation system that enable the working face to meet the conditions for filling mining.

[0027] Preferably, the process of mining the first mining face and then grouting the lower part of the key layer includes:

[0028] Immediately after the working face mining grouting, when the working face mining just begins to form a separation layer, the separation layer grouting work is carried out and the first row of grouting drilling positions are arranged;

[0029] During construction, the timing of the initial grouting is determined based on the amount of water loss in the borehole. When the amount of water loss in the borehole suddenly increases to exceed the preset threshold, the initial grouting is performed.

[0030] The first row of grouting holes is arranged according to the following formula:

[0031] S=H / tanθ

[0032] Where: S is the plane distance from the cut hole and the drift; H is the distance between the grouting layer and the coal seam roof; θ is the fracture angle of the overlying rock layer of the coal seam.

[0033] Preferably, when the replacement working face is mined, when grouting is performed on the lower part of the key layer of the replacement working face, the grouting drill holes are arranged according to the equivalent mining width, and the drill holes are arranged with the center line of the equivalent mining width as the reference line, and offset to the side of the first mining face.

[0034] Compared with the prior art, the present invention has the following advantages and technical effects:

[0035] The present invention eliminates the supporting coal pillars between the overburden separation grouting working faces, and adopts the equivalent mining width method to carry out overburden separation grouting mining without coal pillars on the working face, forming a discontinuous separation structure. The successor working face is always in a non-fully mined state, which improves the grouting filling and subsidence reduction effect, further improves the coal resource recovery rate of the mine, and reduces mining costs.

[0036] The present invention limits the layout width of the successive working face in the form of equivalent mining width, forms a discontinuous separation structure, meets the requirements of the separation grouting simply supported beam on the breaking distance, and thus realizes the purpose of reducing settlement by grouting the separation layer without coal pillars and overburden.

[0037] By adopting the method of the present invention, no coal pillars are left between the working faces, which greatly improves the recovery rate of the panel area.

[0038] The present invention increases the service life of the auxiliary air inlet tunnel and saves tunnel excavation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0040] Figure 1 This is a plan view of a coal pillar-free working face according to an embodiment of the present invention;

[0041] Figure 2 This is a diagram of a method for reducing subsidence by grouting in overburden separation layer without coal pillars according to an embodiment of the present invention;

[0042] Figure 3 This is a structural diagram of the post-mining compaction area of ​​the working face according to an embodiment of the present invention;

[0043] Figure 4 This is a diagram of a grouting drilling arrangement for a non-pillar overburden separation layer according to an embodiment of the present invention;

[0044] Among them, 1. Return air lane in the panel area; 2. Main transport lane in the panel area; 3. Auxiliary transport lane in the panel area; 4. First mining face; 5. First replacement working face; 6. Transport chute; 7. Auxiliary air inlet chute; 8. Return air chute; 9. Equivalent mining width; 10. Boundary line of compaction area in the first mining working face; 11. Second replacement working face; 12. Compacted area; 13. Uncompacted area; 14. Delamination space; 15. Grouting sub-critical layer; 16. Sub-critical layer; 17. Main critical layer; 18. Grouting borehole; 19. Boundary line between weak layer and bedrock; 20. Ground surface; 21. Center line of the first mining face; 22. Center line of equivalent mining width of replacement working face; 23. First row of boreholes in the first mining face; 24. Drill holes in the replacement face. DETAILED DESCRIPTION

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0047] like Figure 1-4 As shown, this embodiment provides a method for reducing subsidence by grouting and filling in overburden separation layer without coal pillars, comprising:

[0048] Determine the positions of all key layers within the panel area, the key grouting layers in the overburden, the breaking distance of the key grouting layers, and the width of the first mining face; the panel area includes the panel return air tunnel 1, the panel main transport tunnel 2, and the panel auxiliary transport tunnel 3.

[0049] Based on the allowable mining width of the key grouting layer and the principle of the fulcrum effect in the compacted zone of the caving zone, the equivalent mining width is determined, the length of the successive working face is calculated, and the overburden stratum backfill mining system is obtained; no coal pillars are left between the working faces of the overburden stratum backfill mining system;

[0050] The first mining face 4 was mined, and grouting was carried out on the lower part of the key layer immediately after the mining;

[0051] When the replacement working face is mined, grouting is performed on the lower part of the key layer of the replacement working face; the replacement working face includes a first replacement working face 5 and a second replacement working face 11.

[0052] The remaining working faces are mined in sequence by grouting and filling until the entire panel area is mined; no coal pillars are left between all working faces.

[0053] This embodiment determines the key grouting layer based on geology, determines the width of the initial mining face based on the allowable mining width of the key layer, and determines the width of the successor working face based on the principle of equivalent mining width to form a mining system. A pillar-free layout is adopted between the working faces; grouting is performed through grouting holes into the separation layer below the target key layer as mining progresses. As the new subsequent working face is mined and the separation layer is grouted, a discontinuous separation layer structure is formed, meeting the breaking distance requirements of the separation layer grouting simply supported beam, thereby achieving pillar-free overburden separation layer grouting and subsidence reduction.

[0054] Furthermore, the tunnel arrangement mode of the method for non-pillar overburden separation grouting mining is a goaf-side tunneling arrangement mode.

[0055] Furthermore, based on geological exploration data, all key layer positions in the strata within the panel area are determined.

[0056] Usually, before coal seam mining, the geological conditions above the coal seam will be analyzed, and the positions of all key layers above the coal seam will be determined based on the obtained geological exploration data.

[0057] like Figure 2 As shown in Figure 1, it is assumed that based on geological data, there are three key layers within the panel area: the grouting sub-key layer 15, the sub-key layer 16, and the main key layer 17. The layers also include the abscission space 14, the boundary between the weak layer and the bedrock 19, the ground surface 20, the centerline of the initial mining face 21, the centerline of the equivalent mining width of the replacement working face 22, and the replacement face borehole 24. The characteristics of these key layers are shown in Table 1 below.

[0058] Table 1

[0059]

[0060] Furthermore, the height of the key grouting layer from the coal seam is greater than the sum of the height of the water-conducting fracture zone and the safety isolation zone. Selecting the deepest key layer as the key grouting layer can improve the grouting effect. Assuming the sum of the heights of the water-conducting fracture zone and the safety isolation zone is 150m, the key grouting layer is selected as the grouting sub-key layer 15.

[0061] Furthermore, the selection of key grouting layers for the successor working face should be consistent with that for the initial mining working face to achieve the best grouting effect.

[0062] like Figure 1 As shown, it includes the compaction area boundary line 10 of the first mining working face, the compaction area 12, and the uncompacted area 13.

[0063] Furthermore, the formula for calculating the breaking distance of the key grouting layer is:

[0064]

[0065] Where: L1 is the critical layer fracture under grouting; δ1 is the tensile strength of the subcritical layer; h1 is the thickness of the subcritical layer; and q1 is the upper formation pressure that the critical layer withstands when not grouting.

[0066] According to the data in Table 1, the calculated breaking distance of the key grouting layer is 47.67m.

[0067] Furthermore, the formula for the first mining width is:

[0068] W k =L k +2H k / tanθ is calculated

[0069] Where: W k L is the maximum mining width allowed for the working face during grouting filling of the Kth key layer; K is the breaking distance of the key layer; H k is the distance between the key layer and the working face coal seam; θ is the fracture angle of the overlying rock stratum of the coal seam.

[0070] According to the data in Table 1, the maximum width allowed for the grouting filling working face is 209.72m, and 209 is taken as Figure 1 The width of the first mining surface 4.

[0071] Furthermore, the formula for determining the equivalent mining width based on the allowable mining width of the key grouting layer is:

[0072]

[0073] Where: ε is the injection-production ratio; L 等效 L is the equivalent cutting length of the working surface;首采 The length of the cut at the first mining face; d sc The width of the air inlet chute between the first mining face and the successor working face; L 接替 The length of the eye cut to replace the working face.

[0074] like Figure 1 As shown, it includes a transport chute 6, an auxiliary air inlet chute 7, and a return air chute 8.

[0075] Furthermore, the formula for calculating the length of the replacement working surface is:

[0076]

[0077] Among them, the equivalent mining width value is the maximum mining width value allowed by the grouting key layer, d sc Layout dimensions of the pillar-free tunnel in the mine.

[0078] Furthermore, the process of obtaining the overburden separation layer filling mining system includes:

[0079] The width of the successor working face is calculated, and the return air lane is arranged according to the width of the successor working face to obtain the first mining face mining system and "Y" type ventilation system that enable the working face to meet the conditions for filling mining.

[0080] Specifically, the calculation shows that the width of the replacement working face is 151m. Figure 2 In the process, since the initial mining face 4 and the first replacement working face 5 adopt pillarless mining and share a common roadway, the roadway location is determined based on the calculated working face width. This forms the initial mining face mining system and a "Y"-shaped ventilation system, enabling the working face to meet the requirements for backfill mining.

[0081] Furthermore, the first mining face 4 is mined, and the process of grouting the lower part of the key layer immediately after the mining includes:

[0082] Immediately after the working face mining grouting, when the working face mining just begins to form a separation layer, the separation layer grouting work is carried out and the first row of grouting drilling positions are arranged;

[0083] During construction, the timing of the initial grouting is determined based on the amount of water loss in the borehole. When the amount of water loss in the borehole suddenly increases to exceed the preset threshold, the initial grouting is performed.

[0084] The first row of grouting holes is arranged according to the following formula: Figure 4 The first row of boreholes 23 in the first mining face:

[0085] S=H / tanθ

[0086] Where: S is the plane distance from the cut hole and the drift; H is the distance between the grouting layer and the coal seam roof; θ is the fracture angle of the overlying rock layer of the coal seam.

[0087] According to the parameters in Table 1, the calculated distance S from the cut-eye, drift and other planes is 77m.

[0088] like Figure 4 As shown, the remaining boreholes in the first mining face 4 are arranged in sequence according to the center line 21 of the first mining face. The arrangement principle can be to control the spacing according to the slurry diffusion radius.

[0089] Furthermore, when the replacement working face is mined, when grouting is carried out on the lower part of the key layer of the replacement working face, the grouting drill holes are arranged according to the equivalent mining width, rather than the replacement working face width. The drill holes are arranged with the center line of the equivalent mining width as the reference line and offset to the side of the first mining face.

[0090] Specifically, when the replacement working face is mined, grouting is carried out on the lower part of the key layer of the replacement working face. Figure 4 The grouting drilling holes 18 of the first replacement working face 5 should be arranged according to the equivalent mining width 9, rather than the replacement working face width. The drilling arrangement should be arranged with the equivalent mining width center line 22 of the replacement working face as the reference line, and offset to the side of the first mining face 4.

[0091] Furthermore, the remaining working faces are mined by grouting and filling in the separation layer in sequence, and the width of the i+1th working face is calculated according to the following formula:

[0092] L (i+1) =L d(i+1) -1 / 2L d(i) (1-ε)-d sc(i+1)

[0093] Where: ε is the injection-production ratio; L (i+1) L is the equivalent cutting length of the i+1th working surface; (i) is the cutting length of the i-th working surface;

[0094] d sc(i+1) L is the width of the air inlet chute between the i-th working surface and the i+1-th working surface; (i+1) is the cutting length of the i+1th working surface.

[0095] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for reducing subsidence by grouting and filling in overburden separation layer without coal pillars, characterized in that: include: Determine the positions of all key layers within the panel area, the key grouting layers in the overburden, the breaking distance of the key grouting layers, and the width of the first mining face; Based on the allowable mining width of the grouting key layer and the principle of the fulcrum effect of the compaction zone of the caving zone, the equivalent mining width is determined, the length of the successive working face is calculated, and the overburden stratum separation filling mining system is obtained; no coal pillars are left between the working faces of the overburden stratum separation filling mining system; The first mining face is mined, and grouting is carried out on the lower part of the key layer immediately after mining; When the replacement working face is mined, grouting is carried out on the lower part of the key layer of the replacement working face; The remaining working faces are mined in sequence by grouting and filling until the entire panel area is mined; no coal pillars are left between all working faces.

2. The method according to claim 1, characterized in that The tunnel arrangement mode of the coal pillar-free overburden separation grouting mining method is a gob-side tunneling arrangement mode.

3. The method according to claim 1, characterized in that The height of the grouting key layer from the coal seam is greater than the sum of the height of the water-conducting fracture zone and the height of the safety isolation zone, and the key layer with the deepest burial depth of all key layers is selected as the grouting key layer.

4. The method according to claim 1, wherein The formula for calculating the breaking distance of the grouting key layer is: Where: L1 is the breaking distance of the key layer under grouting in m; δ1 is the tensile strength of the sub-key layer in kPa; h1 is the thickness of the sub-key layer in m; q1 is the upper formation pressure that the key layer bears when not grouting.

5. The method according to claim 1, characterized in that The formula for the first mining width is: <h2 style=";text-align:left;direction:ltr">W<h2 style=";text-align:left;direction:ltr"> k <h2 style=";text-align:left;direction:ltr"> =L<h2 style=";text-align:left;direction:ltr"> k <h2 style=";text-align:left;direction:ltr"> +2H<h2 style=";text-align:left;direction:ltr"> k <h2 style=";text-align:left;direction:ltr"> / tanθ; Where: W k L is the maximum mining width allowed for the working face during grouting filling of the Kth key layer; K is the breaking distance of the key layer; H k is the distance between the key layer and the working face coal seam; θ is the fracture angle of the overlying rock stratum of the coal seam.

6. The method according to claim 1, characterized in that The formula for determining the equivalent mining width based on the allowable mining width of the key grouting layer is: Where: ε is the injection-production ratio; L 等效 L is the equivalent cutting length of the working surface; 首采 The length of the cut at the first mining face; d sc The width of the air inlet chute between the first mining face and the successor working face is m; L 接替 The length of the eye cut to replace the working face.

7. The method according to claim 1, characterized in that The formula for calculating the length of the replacement working surface is: Among them, the equivalent mining width value is the maximum mining width value allowed by the grouting key layer, d sc Layout dimensions of the pillar-free tunnel in the mine.

8. The method according to claim 1, characterized in that The process of obtaining an overburden separation and backfill mining system includes: The width of the replacement working face is calculated, and the return air lane is arranged according to the replacement working face width to obtain the first mining face mining system and "Y" type ventilation system that enable the working face to meet the conditions for filling mining.

9. The method according to claim 1, characterized in that The process of grouting the lower part of the key layer after the first mining face is recovered includes: Immediately after the working face mining grouting, when the working face mining just begins to form a separation layer, the separation layer grouting work is carried out and the first row of grouting drilling positions are arranged; During construction, the timing of the initial grouting is determined based on the amount of water loss in the borehole. When the amount of water loss in the borehole suddenly increases to exceed the preset threshold, the initial grouting is performed. The first row of grouting holes is arranged according to the following formula: S=H / tanθ Where: S is the plane distance from the cut hole and the drift; H is the distance between the grouting layer and the coal seam roof; θ is the fracture angle of the overlying rock layer of the coal seam.

10. The method according to claim 1, characterized in that When the replacement working face is mined, when grouting is carried out on the lower part of the key layer of the replacement working face, the grouting drill holes are arranged according to the equivalent mining width, and the drill holes are arranged with the center line of the equivalent mining width as the reference line, and offset to the side of the first mining face.

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