Dynamic-Regulation-Based Coal-Pillar-Free Separation Grouting and Backfilling Mining Method for Multiple Working Faces

Abstract

The invention discloses a multi - working - face pillar - free gob - injection filling mining method based on dynamic regulation, belonging to the technical field of coal - mine filling mining. The specific method is as follows: determining the position and scope of the dynamic regulation area, constructing dynamic regulation boreholes, carrying out dynamic regulation, constructing a support body, detecting the dynamic regulation effect and taking supplementary injection measures, and continuously mining gob - injection in multiple working faces. Under the condition of gob - side entry retaining with flexible formwork walls, the invention injects a paste filling slurry prepared from gangue, fly ash, cement and water - reducing agent into the grouting separation layer through a main borehole near two adjacent working faces, and at the same time injects a quick - setting agent through an auxiliary borehole to construct a support body to support the overlying strata and prevent the key grouting layer from breaking due to excessive span after multi - working - face mining.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine filling mining, and particularly relates to a multi - working - face pillar - free separated - seam grouting filling mining method based on dynamic regulation. Background Technique

[0002] The overburden isolation grouting filling method can effectively control the movement of the overlying strata, block the upward transmission of the separated - seam space, and reduce the ground subsidence, and is widely used in the mining of coal under the "three - under" (buildings, railways, water bodies). However, when applying this method, it is generally necessary to leave coal pillars with a width of 30 - 40 m on both sides of the working face to isolate the grouting separated seams of adjacent two working faces, which results in a large amount of coal resource loss.

[0003] The pillar - free mining method is to cut the overlying strata by pre - splitting blasting on the side of the reserved roadway close to working face A, and combine bolt - cable support and lateral gangue - retaining support (such as constructing a flexible - form concrete wall) to retain this roadway and use it as the roadway of the next working face B. This method can effectively overcome the problem of excessive remaining coal resources in the overburden isolation grouting filling method. However, in the case of pillar - free separated - seam grouting filling mining, the span in the dip direction increases after the mining of working face B. Once it exceeds the maximum deflection of the grouting key stratum, it will break, losing the condition for grouting and filling under the grouting key stratum. Therefore, it is necessary to solve the problem of the breakage of the grouting key stratum due to excessive deflection during the multi - working - face pillar - free separated - seam grouting filling mining process.

[0004] Dynamic regulation means constructing a support body by performing high - pressure grouting through a dynamic regulation borehole drilled from the surface on the side of the already - mined working face A close to working face B to the separated - seam layer position, increasing the separated - seam opening, accelerating the compaction of the caving zone outside the gob - side entry in a short time to form a stable support, achieving dynamic balance in the vertical direction. On the one hand, compacting the caving rock mass in the non - compacted area below, and on the other hand, supporting the grouting key stratum through the constructed support body to control the strata movement and reduce the ground subsidence.

[0005] Among the existing patents, CN202210318141.2 - Overlying Rock Compaction Grouting Filling Continuous Mining Method arranges grouting boreholes in the side fracture thickness change area near the next working face. When the next working face is mined, simultaneous separation layer grouting filling is carried out using the grouting boreholes of the current working face and the previous working face, realizing continuous mining of the coal mining face under the condition of pillarless separation layer grouting. CN202211677467.0 - Pillarless Continuous Mining Overlying Rock Separation Layer Grouting Filling Coal Mining Method extends the grouting boreholes of the last working face in a group to below the water - conducting fracture zone, and injects reinforcement slurry into the water - conducting fracture zone and the caving zone through the grouting drill pipe, forming a reinforcement area in the water - conducting fracture zone and the caving zone to support the overlying strata, thereby realizing continuous mining of the working face under the condition of no coal pillar. CN202410628029.8 - A Separation Layer Grouting Filling Method under the Condition of Flexible Mold Wall Gob - Side Entry Retaining determines the size of the grouting support column through theoretical calculation, constructs grouting filling artificial support columns by constructing grouting boreholes at different angles in the roof - cutting reserved roadway towards the mined - out working face side, and controls the movement of the overlying strata. CN202410718098.8 - A Mining Method for Preventing Surface Subsidence in Pillarless Mining of Underground Resources controls the time and position of the collapse of the roof strata of the mining face by artificially controlling the blasting of the roof - cutting pressure - relief holes, and then constructs grouting boreholes to the caving zone, and grouts and fills the overlying strata and the space above in the caving zone, realizing surface subsidence control under the condition of pillarless mining. The above - mentioned existing technologies realize continuous mining of the working face under the condition of no coal pillar by optimizing the grouting steps, constructing support columns in the goaf or grouting and reinforcing part of the goaf, etc., but do not specifically involve the use of dynamic regulation methods to realize continuous mining of multiple working faces under the condition of no coal pillar. When carrying out continuous mining of multiple working faces under the condition of no coal pillar, when the mining length in the dip direction exceeds the maximum breaking distance of the grouting key stratum, the grouting key stratum will break, affecting the separation layer grouting filling effect. In view of this, the present invention is proposed. Summary of the Invention

[0006] In order to solve the technical problems existing in the above - mentioned existing technologies, the present invention provides a multi - working - face pillarless separation layer grouting filling mining method based on dynamic regulation, which realizes continuous separation layer grouting filling mining of multiple working faces through dynamic regulation under the condition that there is a flexible mold wall between the working faces and gob - side entry retaining.

[0007] To achieve the above object, the present invention provides the following technical solution: A multi - working - face pillarless separation layer grouting filling mining method based on dynamic regulation, characterized by comprising the following steps:

[0008] S1. Determine the position and scope of the dynamic regulation area;

[0009] S2. Construct dynamic regulation boreholes;

[0010] S3. Carry out dynamic regulation to construct a support body;

[0011] S4. Detect the dynamic regulation effect and take supplementary injection measures;

[0012] S5. Continuous mining with separated seam grouting in multiple working faces.

[0013] Preferably, the specific steps in S1 are as follows:

[0014] S11. Determine the grouting separated seam horizon according to relevant geological data;

[0015] S12. Determine the width of the non-compacted area by combining the working face parameters and the injection-production ratio;

[0016] S13. Determine the position and scope of the dynamic regulation area by combining the width of the non-compacted area, the flexible mold wall and the gob-side entry position.

[0017] Preferably, in S11, the distance from the grouting separated seam horizon to the coal seam should be greater than the sum of the height of the water-conducting fracture zone and the height of the isolation and maintenance zone. The calculation formula is:

[0018] H 离 ≥H 导 +(6 - 10)M

[0019] In the formula, H 离 is the height of the separated seam horizon, m; H 导 is the height of the water-conducting fracture zone, m; H 隔 is the height of the isolation and maintenance zone, m; M is the coal seam height, m.

[0020] Preferably, in S12, the calculation formula for the non-compacted area is:

[0021]

[0022] In the formula, L 非 is the width of the non-compacted area, m; L 压 is the width of the compacted area, m; W is the working face width, m; a is the injection-production ratio, taking 0.5 - 0.7.

[0023] Preferably, in S13, the right non-compacted area near the flexible mold wall in working face A is the dynamic regulation area. The length of the dynamic regulation area is the same as the working face length, the width is determined by the spacing between the main and auxiliary boreholes in the dynamic regulation area, and the height is the same as the maximum development height of the separated seam space in working face A.

[0024] Preferably, S2 specifically includes: constructing multiple groups of dynamic regulation boreholes at intervals of distance L along the working face advancing direction on the surface of the dynamic regulation area. Each group of dynamic regulation boreholes includes the main borehole Z in the middle A and the auxiliary boreholes Z on the left and right sides A1 and Z A2 , and determine the main borehole Z by combining the flow law of the filling paste slurry Aand auxiliary borehole Z A1 and Z A2 spacing F between the main borehole Z A and the auxiliary borehole Z A1 and Z A2 are all constructed to the grouting separation layer position. The auxiliary borehole Z A2 is located above the gob-side entry between the working faces A and B.

[0025] Preferably, step S3 is as follows:

[0026] S31. After the gob-side grouting filling of the working face A is completed, high-pressure grouting is carried out in the dynamic regulation area. Through the main borehole Z A high-pressure injection of paste filling slurry, and at the same time through the main borehole Z in the working face A A auxiliary boreholes Z on the left and right sides A1 and Z A2 inject accelerator to accelerate the formation of the support body of the paste filling slurry, and compact the caved gangue below, so that the non-compacted area is transformed into a compacted area;

[0027] S32. Inject the slurry prepared from quick-setting cement, fly ash, coal gangue, and coal slime through the auxiliary boreholes Z A1 and Z A2 to fill the remaining separated layer expansion space on both sides of the support body after dynamic regulation.

[0028] Preferably, in S4, survey lines are arranged on the surface of the dynamic regulation area and in the gob-side entry area underground. Geophysical exploration methods are used to detect the distribution pattern of the support body in the separated layer. At the same time, inspection boreholes are constructed at an angle α in the gob-side entry to the support body. According to the core length of the support body obtained from the inspection boreholes, it is judged whether the height and strength of the support body meet the design requirements. If not, supplementary injection measures are taken.

[0029] Preferably, when the distribution pattern of the support body does not meet the design requirements, the supplementary injection measures are as follows: increase the proportion of water reducer, reduce the fluidity of the paste filling slurry, and the proportion of each component of the paste filling material is: 72% coal gangue, 10% fly ash, 15% cement, 3% water reducer;

[0030] When the height of the support body does not reach the maximum separated layer height, the supplementary injection measures are as follows: increase the grouting pressure and continue high-pressure grouting;

[0031] When the strength of the support body does not meet the design requirements, the supplementary injection measures are as follows: increase the proportion of cement in the paste filling material to increase the strength of the support body, and the proportion of each component of the paste filling material is: 63.5% coal gangue, 10% fly ash, 25% cement, 1.5% water reducer.

[0032] Preferably, in S5, after the working face B is mined, through the auxiliary borehole Z on the right side of the main borehole Z in the working face A A the auxiliary borehole ZA2 Inject the slurry prepared from fly ash, gangue, and slime into the separated seam grouting borehole Z2 in the working face B simultaneously, filling the separated seam development space above the working face B and the separated seam expansion space on the right side of the support body until the separated seam grouting filling work of the working face B is completed. Repeat steps S1 - S5 to achieve the separated seam grouting filling mining without coal pillars for multiple working faces based on dynamic regulation.

[0033] Compared with the prior art, the present invention provides a method for separated seam grouting filling mining without coal pillars for multiple working faces based on dynamic regulation, having the following beneficial effects:

[0034] (1) The present invention proposes a method for separated seam grouting filling mining without coal pillars for multiple working faces based on dynamic regulation. Under the condition that there is a flexible mold wall between the working faces and along - the - go roadway retaining, continuous mining of separated seam grouting filling for multiple working faces is achieved through dynamic regulation.

[0035] (2) The present invention injects a paste filling slurry prepared from gangue, fly ash, cement, and water - reducing agent into the grouting separated seam through the main borehole near two adjacent working faces under the condition of flexible mold wall along - the - go roadway retaining. At the same time, a quick - setting agent is injected through the auxiliary borehole to construct a support body to support the overlying strata, which can ensure that the key grouting strata do not break during the separated seam grouting filling mining without coal pillars for multiple working faces.

[0036] (3) After the implementation of the present invention, no coal pillars are left between the working faces, improving the recovery rate of coal resources and having significant economic benefits.

[0037] (4) The present invention can dispose of a large amount of coal - based solid wastes such as gangue, realizing the resource - based disposal of coal - based solid wastes, protecting the mining area environment, and being able to effectively control the movement of the overlying strata and reduce the surface subsidence, having significant social benefits. Description of the Drawings

[0038] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0039] Figure 1 is a flow chart of the method for separated seam grouting filling mining without coal pillars for multiple working faces based on dynamic regulation proposed in the embodiment of the present invention;

[0040] Figure 2 is a schematic diagram of the distribution of the grouting separated seam layer position in the embodiment of the present invention;

[0041] Figure 3 is a schematic diagram of the position of the dynamically regulated area determined in the embodiment of the present invention;

[0042] Figure 4 is a sectional view of the borehole layout in the dynamically regulated area in the embodiment of the present invention;

[0043] Figure 5 Top view of the drilling layout in the dynamic regulation area in the embodiment of the present invention;

[0044] Figures 6 to 7 Schematic diagram of the dynamic regulation process in the embodiment of the present invention;

[0045] Figure 8 Schematic diagram of the inspection drilling construction in the embodiment of the present invention;

[0046] Figure 9 Schematic diagram of continuous mining with gob-side grouting filling without coal pillars in multiple working faces in the embodiment of the present invention. Specific implementation manner

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but only represents the selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0048] This embodiment proposes a method for gob-side grouting filling mining without coal pillars in multiple working faces based on dynamic regulation. The detailed steps are as Figures 1 to 9 shown:

[0049] (1) Determine the position and scope of the dynamic regulation area

[0050] First, determine the grouting separation layer position according to relevant geological data. The distance from the grouting separation layer to the coal seam should be greater than the sum of the height of the water-conducting fracture zone and the height of the isolation maintenance zone (taking 6 - 10 times the mining height). The calculation formula is:

[0051] H 离 ≥H 导 +H 隔 (1)

[0052] H 隔 =(6~10) M (2)

[0053] In the formula, H 离 is the height of the separation layer, m; H 导 is the height of the water-conducting fracture zone, m; H 隔 is the height of the isolation maintenance zone, m; M is the coal seam height, m.

[0054] Then, determine the width of the non-compacted area. Combine the working face parameters and the injection-production ratio to determine the width of the compacted area, and calculate the width of the non-compacted area based on the width of the compacted area. The calculation formula for the compacted area is:

[0055] L 压 = W × a (3)

[0056] In the formula, L 压 is the width of the compacted area, m; W is the width of the working face, m; a is the injection-production ratio, taking 0.5 - 0.7.

[0057] The calculation formula for the width of the non-compacted area is:

[0058]

[0059] In the formula, L 非 is the width of the non-compacted area, m; L 压 is the width of the compacted area, m; W is the width of the working face, m; a is the injection-production ratio, taking 0.5 - 0.7.

[0060] Finally, determine the position of the dynamic regulation area. Combine the width of the non-compacted area, the flexible mold wall, and the gob-side entry position to select the side of the non-compacted area on the right side inside the working face A near the flexible mold wall as the dynamic regulation area. The length of the dynamic regulation area is the same as the length of the working face, the width is determined by the spacing between the main and auxiliary boreholes in the dynamic regulation area, and the height is the same as the maximum development height of the separated layer space in the working face A.

[0061] (2) Construction of dynamic regulation boreholes

[0062] The spacing between the separated layer grouting boreholes is determined by the diffusion radius of the slurry prepared from fly ash, gangue, and coal slime. The calculation formula for the spacing between adjacent separated layer grouting boreholes is:

[0063] L a = 2tl 粉 (5)

[0064] In the formula, L a is the spacing between adjacent separated layer grouting boreholes, m; t is the safety factor, taking 0.6; l 粉 is the diffusion radius of the slurry prepared from fly ash, gangue, and coal slime, m.

[0065] The spacing between the dynamic regulation boreholes is determined by the diffusion radius of the paste filling slurry prepared from gangue, fly ash, cement, and water reducer. The calculation formula for the spacing between adjacent dynamic regulation boreholes is:

[0066] L = 2tl 膏 (6)

[0067] In the formula, L is the spacing between adjacent dynamic regulation boreholes, m; t is the safety factor, taking 0.6; l 膏It is the diffusion radius of paste filling slurry, in m.

[0068] Construct multiple groups of dynamic control boreholes at intervals of distance L along the advancing direction of the working face on the surface of the dynamic control area. Each group of dynamic control boreholes includes the main borehole Z in the middle A and the auxiliary boreholes Z on the left and right sides A1 and Z A2 . The main borehole Z A and the auxiliary borehole Z A1 and Z A2 are all constructed to the grouting separation layer position. The auxiliary borehole Z A2 is located above the gob-side entry between working faces A and B. Regarding the flow law of the paste filling slurry as a standard normal distribution, determine the spacing F of the main borehole Z A and the auxiliary boreholes Z A1 and Z A2 in combination with the flow law of the paste filling slurry.

[0069] The calculation formula for the standard normal distribution is:

[0070]

[0071] The calculation formula for the spacing F of the main borehole Z A and the auxiliary boreholes Z A1 and Z A2 is:

[0072] F = b × H × Φ(x) (8)

[0073] In the formula, F is the spacing of the main borehole Z A and the auxiliary boreholes Z A1 and Z A2 , in m; b is the safety factor, taking 4 - 6; H is the maximum height of the separation space, in m; Φ(x) is the standard normal distribution value, taking 0.7.

[0074] (3) Carry out dynamic control and construct a support body

[0075] Inject the slurry prepared from fly ash, coal gangue, and coal slime into the separation layer through the separation layer grouting boreholes on the surface of working face A. The proportion of each component of the slurry is: fly ash 20%, coal gangue 60%, and coal slime 20%. After the separation layer grouting and filling of working face A is completed, inject the paste filling slurry prepared from coal gangue, fly ash, cement, and water reducer into the determined dynamic control area at high pressure through the main borehole Z A . The proportion of each component of the paste filling material is: coal gangue 73.5%, fly ash 10%, cement 15%, and water reducer 1.5%. At the same time, through the main borehole Z A on the left and right sides of the auxiliary boreholes Z A1 and Z A2Inject a quick-setting agent to accelerate the formation of a support body from the paste filling slurry, and compact the fallen gangue below, converting the uncompacted area into a compacted area. The proportion of the quick-setting agent accounts for 5% of the volume of the injected paste filling slurry. Under the action of the grouting pressure, the opening of the bedding separation in the dynamic regulation area further increases, and the paste filling slurry forms a support body in the bedding separation space to support the key strata and prevent it from breaking. After the support body is constructed, through the auxiliary boreholes Z A1 and Z A2 inject the slurry prepared from quick-setting cement, fly ash, coal gangue, and coal slime to fill the bedding separation expansion space on both sides of the support body after dynamic regulation, and the proportion of each component is: quick-setting cement 10%, fly ash 40%, coal gangue 30%, and coal slime 20%.

[0076] The calculation formula for the grouting pressure is as follows:

[0077] P 孔 >H m (γ - γ1) + C (9)

[0078] In the formula, P 孔 is the orifice grouting pressure, MPa; H m is the coal seam burial depth, m; γ is the comprehensive specific gravity of the strata above the grouting filling layer, kN / m 3 ; γ1 is the specific gravity of the paste filling slurry, kN / m 3 ; C is the dynamic adjustment coefficient, MPa, with a value range of 0 - 3 MPa, and the value is 0 during normal grouting.

[0079] (4) Detection of dynamic regulation effect and supplementary grouting measures

[0080] After completing steps (1) - (3), lay survey lines on the surface of the dynamic regulation area and along the gob-side entry in the underground. Use geophysical exploration methods such as magnetotelluric sounding to detect the distribution pattern of the support body in the bedding separation. At the same time, construct inspection boreholes at an angle α in the gob-side roadway to the support body. On the one hand, detect whether the height of the support body reaches the maximum height of the gob-side grouting filling in working face A, and on the other hand, conduct mechanical tests on the core of the support body to detect whether the strength of the support body meets the requirements.

[0081] When the distribution pattern of the support body does not meet the requirements, increase the proportion of the water reducer and reduce the fluidity of the paste filling slurry. At this time, the proportion of each component of the paste filling material is: coal gangue 72%, fly ash 10%, cement 15%, and water reducer 3%.

[0082] When the height of the support body does not reach the maximum bedding separation height, increase the grouting pressure and continue high-pressure grouting. At this time, the value of C in formula (9) is 2 - 3 MPa. The calculation formula for the height of the support body is:

[0083] H c =S×sinα (10)

[0084] In the formula, H c is the height of the support body, in m; S is the length of the support body drilled by the inspection borehole, in m; α is the angle between the inspection borehole and the horizontal plane, in °.

[0085] When the strength of the support body does not meet the requirements, increase the proportion of cement in the paste filling material to increase the strength of the support body. At this time, the proportion of each component of the paste filling material is: gangue 63.5%, fly ash 10%, cement 25%, water reducing agent 1.5%. Through the above measures, until the distribution form, height and strength of the support body meet the requirements.

[0086] (5) Continuous mining by off - layer grouting in multiple working faces

[0087] After the working face B is mined, through the main borehole Z A on the right side of the auxiliary borehole Z A2 in the working face A and the off - layer grouting borehole Z2 in the working face B, inject the slurry prepared from fly ash, gangue and coal slime at the same time to fill the off - layer development space above the working face B and the off - layer expansion space on the right side of the support body until the off - layer grouting filling work of the working face B is completed. Repeating the above steps (1) - (5) can realize the off - layer grouting filling mining without coal pillars in multiple working faces based on dynamic regulation.

[0088] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. In addition, in the description of the present invention, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0089] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A multi-working face non-pillar separation grouting filling mining method based on dynamic control, characterized in that: The following steps are involved: S1. Determine the location and scope of the dynamic control area; S2, dynamic control of drilling construction; S3. Carry out dynamic regulation and build a support system; S4. Detect the effect of dynamic regulation and take supplementary measures; S5, continuous mining by grouting of multiple working faces; S2 specifically includes: constructing multiple groups of dynamic control boreholes at intervals of L along the advancing direction of the working face on the surface of the dynamic control area, each group of dynamic control boreholes includes the middle main borehole Z A And the auxiliary drilling holes Z on the left and right sides A1 and Z A2 , combined with the flow law of the filling paste slurry, determine the main drilling hole Z A And auxiliary drilling Z A1 and Z A2 Distance F, main drilling hole Z A And auxiliary drilling Z A1 and Z A2 The construction was completed to the grouting separation layer, and the auxiliary borehole Z A2 Located above the gob-side tunnel between working faces A and B; The S3 steps are: S31, after the grouting filling of the separation layer of working face A is completed, high-pressure grouting is carried out in the dynamic control area through the main borehole Z A High pressure injection of paste filling slurry, while through the main drilling hole Z in the working face A A Auxiliary drilling holes Z on both sides A1 and Z A2 Inject quick-setting agent to accelerate the formation of supporting body by paste filling slurry, and compact the collapsed gangue below to transform the non-compacted area into the compacted area; S32, through the auxiliary drilling hole Z A1 and Z A2 Inject slurry made of quick-setting cement, fly ash, coal gangue and coal slime to fill the remaining separation expansion space on both sides of the support body after dynamic control; In S5, after the mining of working face B, the main borehole Z in working face A is used to A Secondary drilling hole Z on the right A2 At the same time as the stratum grouting borehole Z2 in working face B, slurry prepared from fly ash, coal gangue and coal slime is injected to fill the stratum development space above working face B and the stratum expansion space on the right side of the support body until the stratum grouting filling work of working face B is completed. Steps S1 to S5 are repeated to realize multi-working face coal pillar-free stratum grouting filling mining based on dynamic control.

2. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 1 is characterized in that: The specific steps in S1 are: S11. Determine the grouting separation layer position according to relevant geological data; S12, determine the width of the non-compacted zone in combination with the working face parameters and the injection-production ratio; S13. Determine the position and scope of the dynamic control area based on the width of the non-compacted area, the flexible formwork wall and the position of the tunnel along the goaf.

3. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 2 is characterized in that: In S11, the distance from the grouting layer to the coal seam should be greater than the sum of the height of the water-conducting fracture zone and the height of the isolation maintenance zone. The calculation formula is: H 离 ≥H 导 +H 隔 H 隔 =(6~10)M In the formula, H 离 is the detachment layer height, m; H 导 is the height of the water-conducting fracture zone, m; H 隔 is the height of the isolation maintenance zone, m; M is the height of the coal seam, m.

4. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 3 is characterized in that: In S12, the calculation formula for the non-compacted area is: Where, L 非 is the width of the non-compacted area, m; L 压 is the width of the compaction zone, m; W is the width of the working face, m; a is the injection-production ratio, which is 0.5 to 0.

7.

5. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 4 is characterized in that: In S13, the non-compacted area on the right side of working face A close to the flexible mold wall is the dynamic control area. The length of the dynamic control area is the same as the length of the working face, the width is determined by the spacing between the main and auxiliary drill holes in the dynamic control area, and the height is the same as the maximum development height of the delamination space in working face A.

6. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 1 is characterized in that: In S4, survey lines are laid out on the surface of the dynamic control area and in the underground gob-retained tunnel area, and geophysical exploration methods are used to detect the distribution pattern of the support body in the detached layer. At the same time, inspection holes are constructed at an angle α to the support body in the gob-retained tunnel. The core length of the support body obtained by the inspection drilling is used to determine whether the height and strength of the support body meet the design requirements. If not, supplementary injection measures are taken.

7. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 6 is characterized in that: When the distribution of the support body does not meet the design requirements, the injection measures are as follows: increase the proportion of water reducing agent and reduce the fluidity of the paste filling slurry. The proportions of the paste filling materials are as follows: 72% coal gangue, 10% fly ash, 15% cement, and 3% water reducing agent; When the support body height does not reach the maximum separation height, the supplementary injection measures are: increase the grouting pressure and continue high-pressure grouting; When the strength of the support body does not meet the design requirements, the supplementary measures taken are: increase the proportion of cement in the paste filling material to increase the strength of the support body. The proportions of the various components of the paste filling material are: coal gangue 63.5%, fly ash 10%, cement 25%, and water reducer 1.5%.

Images