Multi-working-face coal-pillar-free separation layer grouting and filling mining method based on dynamic regulation and control

Abstract

The invention discloses a multi-working-face coal-pillar-free separation layer grouting and filling mining method based on dynamic regulation and control, and belongs to the technical field of coal mine filling mining. The specific method comprises the steps that the position and range of a dynamic regulation and control area are determined, dynamic regulation and control drilling construction is carried out, and dynamic regulation and control are carried out. And constructing a supporting body, dynamically regulating and controlling effect detection and reinjection measures, and performing multi-working-face separation layer grouting continuous mining. According to the method, paste filling slurry prepared from coal gangue, fly ash, cement and a water reducing agent is injected into a grouting separation layer through a main drill hole near two adjacent working faces under the condition of flexible formwork wall gob-side entry retaining, and meanwhile, an accelerator is injected through an auxiliary drill hole to be used for constructing a supporting body to support an overlying rock layer; and a grouting key layer is prevented from being broken due to overlarge span after multiple working faces are mined.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine filling mining, and in particular to a multi-working face coal pillar-free separation grouting filling mining method based on dynamic regulation. Background Art

[0002] The overburden isolation grouting filling method can effectively control the movement of the overburden strata, prevent the upward transmission of the isolation layer space, and reduce ground subsidence. It is widely used in "three-down" coal mining. However, when this method is applied, it is generally necessary to leave 30-40m wide coal pillars on both sides of the working face to isolate the grouting separation layer of the two adjacent working faces, which causes a large amount of coal resource loss.

[0003] The coal-pillar-free mining method is to cut off the overburden by pre-splitting blasting on the side of the reserved tunnel close to the working face A, and combine the anchor bolt and cable support and lateral gangue support (such as building a flexible concrete wall) to retain the tunnel and use it as the tunnel of the next working face B. This method can effectively overcome the problem of too much coal resources left in the overburden isolation grouting filling method, but when the separation grouting filling mining is carried out under the coal-pillar-free condition, the span in the inclination direction increases after the mining of the working face B. Once the maximum deflection of the grouting key layer is exceeded, it will break, and the conditions for grouting filling below the grouting key layer will be lost. Therefore, it is necessary to solve the problem of breakage caused by excessive deflection of the grouting key layer during the coal-pillar-free separation grouting filling mining of multiple working faces.

[0004] Dynamic control refers to the dynamic control of drilling holes on the surface of the mined working face A near the working face B to the grouting detachment layer, conducting high-pressure grouting, increasing the detachment opening, and constructing a support body. In a short period of time, the compaction of the caving zone along the outer side of the empty tunnel is accelerated to form a stable support, thereby achieving dynamic balance in the vertical direction. On the one hand, the collapsed rock mass in the non-compacted area below is compacted, and on the other hand, the key grouting layer is supported by the constructed support body, thereby controlling the movement of the rock layer and reducing surface subsidence.

[0005] Among the existing patents, CN202210318141.2-continuous mining method by grouting and filling with overburden compaction, arranges the grouting boreholes in the lateral fissure thickness variation zone close to the next working face, and simultaneously uses the grouting boreholes of the current working face and the grouting boreholes of the previous working face for grouting and filling in the separation layer when the next working face is mined, so as to realize continuous mining of the coal mining working face under the condition of grouting without coal pillar separation layer. CN202211677467.0-continuous mining method by grouting and filling with overburden separation layer without coal pillar, extends the grouting borehole of the last working face in a group to the bottom of the water-conducting fracture zone, and injects reinforcing slurry into the water-conducting fracture zone and the caving zone through the grouting drill rod, so that the water-conducting fracture zone and the caving zone form a reinforcement zone to support the overburden stratum, thereby realizing continuous mining of the working face under the condition of coal pillar-free separation layer. CN202410628029.8-A method for grouting and filling the separation layer under the condition of leaving a lane along the goaf with a flexible formwork wall, the size of the grouting support column is determined by theoretical calculation, and grouting holes of different angles are constructed on the side of the mined working face in the reserved lane of the top cut to construct artificial support columns for grouting and filling, so as to control the movement of the overlying rock strata. CN202410718098.8-A method for mining underground resources without coal pillars to prevent surface subsidence, which controls the time and position of the collapse of the top rock strata of the mining working face by artificially controlling the blasting of the top cut pressure relief hole, and then constructs a grouting borehole to the collapse zone, and grouting and filling the overburden in the collapse zone and the space above, so as to realize the control of surface subsidence under the condition of mining without coal pillars. The above-mentioned prior art realizes the continuous mining of the working face under the condition of coal pillars without by optimizing the grouting steps, constructing support columns in the goaf, or reinforcing part of the goaf with grouting, but does not specifically involve the use of dynamic control methods to realize the continuous mining of multiple working faces under the condition of coal pillars without. When continuous mining of multiple working faces is carried out without coal pillars, when the mining length in the inclination direction exceeds the maximum breaking distance of the key grouting layer, the key grouting layer will break, affecting the grouting filling effect of the separation layer. 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 prior art, the present invention provides a multi-working face coal pillar-free stratum grouting filling mining method based on dynamic control. Under the condition that there is a flexible mold wall between the working faces and a tunnel is left along the goaf, dynamic control is carried out to achieve continuous mining of multi-working face stratum grouting filling.

[0007] To achieve the above object, the present invention provides the following technical solution: a multi-working face non-pillar separation grouting filling mining method based on dynamic regulation, characterized in that it comprises the following steps:

[0008] S1. Determine the location and scope of the dynamic control area;

[0009] S2, dynamic control of drilling construction;

[0010] S3. Carry out dynamic regulation and build a support system;

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

[0012] S5. Continuous mining by grouting on multiple working faces.

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

[0014] S11. Determine the grouting separation layer position according to relevant geological data;

[0015] S12, determine the width of the non-compacted zone in combination with the working face parameters and the injection-production ratio;

[0016] 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.

[0017] Preferably, in S11, 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, and the calculation formula is:

[0018] H 离 ≥H 导 +(6~10)M

[0019] 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.

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

[0021]

[0022] 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.

[0023] Preferably, in S13, the non-compacted area on the right side of the working face A close to the flexible mold wall is a 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 the working face A.

[0024] Preferably, 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 including 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 AAnd 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 empty tunnel between working faces A and B.

[0025] Preferably, step S3 is:

[0026] 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;

[0027] S32, through the auxiliary drilling hole Z A1 and Z A2 Slurry made of quick-setting cement, fly ash, coal gangue and coal slime is injected to fill the remaining separation expansion space on both sides of the support body after dynamic control.

[0028] Preferably, in S4, survey lines are arranged 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 height and strength of the support body are judged based on the core length of the support body obtained by the inspection drilling to determine whether they meet the design requirements. If they do not meet the requirements, supplementary injection measures are taken.

[0029] Preferably, when the distribution form of the support body does not meet the design requirements, the injection measures taken are: increasing the proportion of water reducing agent, reducing the fluidity of the paste filling slurry, and the proportions of the various components of the paste filling material are: coal gangue 72%, fly ash 10%, cement 15%, and water reducing agent 3%;

[0030] 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;

[0031] 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%.

[0032] Preferably, in S5, after the working face B is mined, the main borehole Z in the working face A is used to A Secondary drilling hole Z on the rightA2 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.

[0033] Compared with the prior art, the present invention provides a multi-working face non-pillar separation grouting filling mining method based on dynamic regulation, which has the following beneficial effects:

[0034] (1) The present invention proposes a multi-working face coal pillar-free stratum grouting filling mining method based on dynamic control. Under the condition that there is a flexible mold wall between the working faces and a roadway is left along the goaf, dynamic control is carried out to achieve continuous mining of multi-working face stratum grouting filling.

[0035] (2) The present invention injects a paste filling slurry made of coal gangue, fly ash, cement and water reducing agent into the grouting separation layer through the main borehole near two adjacent working faces under the condition of flexible formwork wall along the goaf, and at the same time injects a quick-setting agent through the auxiliary borehole to construct a support body to support the overlying rock layer, thereby ensuring that the key grouting layer will not be broken during the grouting filling and mining of the coal pillar-free separation layer of multiple working faces.

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

[0037] (4) The present invention can dispose of a large amount of coal-based solid waste such as coal gangue, realize the resource disposal of coal-based solid waste, protect the mining environment, and effectively control the movement of overlying rock strata and reduce surface subsidence, with significant social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying 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 of the present invention. In the accompanying drawings:

[0039] Figure 1 A flow chart of a multi-working face non-pillar separation grouting filling mining method based on dynamic control proposed in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the distribution of grouting separation layers in an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the position of the dynamic control area determined in an embodiment of the present invention;

[0042] Figure 4 A cross-sectional view of the arrangement of drilling holes in the dynamic control area according to an embodiment of the present invention;

[0043] Figure 5 A top view of the dynamic control area drilling arrangement in an embodiment of the present invention;

[0044] Figure 6-7 A schematic diagram of a dynamic control process in an embodiment of the present invention;

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

[0046] Fig. 9 It is a schematic diagram of continuous mining by grouting without coal pillars on multiple working faces in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the 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. The components of the embodiments of the present invention generally described and shown in the 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 drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0048] This embodiment proposes a multi-working face non-pillar separation grouting filling mining method based on dynamic control. The detailed steps are as follows: Figures 1 to 9 As shown:

[0049] (1) Determine the location and scope of the dynamic control area

[0050] First, determine the grouting separation layer 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 (6 to 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 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.

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

[0055] L 压 =W×a (3)

[0056] Where, 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.

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

[0058]

[0059] 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.

[0060] Finally, determine the location of the dynamic control area. Combined with the width of the non-compacted area, the flexible mold wall, and the location of the gob-side tunnel, the non-compacted area on the right side of the working face A near the flexible mold wall is selected as 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 boreholes in the dynamic control area, and the height is the same as the maximum development height of the delamination space in the working face A.

[0061] (2) Dynamically control drilling construction

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

[0063] L a =2tl 粉 (5)

[0064] Where, L a is the spacing between adjacent separation layer grouting holes, m; t is the safety factor, which is 0.6; l 粉 is the diffusion radius of the slurry prepared from fly ash, coal gangue and coal slime, m.

[0065] The dynamic control drilling hole spacing is determined by the diffusion radius of the paste filling slurry prepared from coal gangue, fly ash, cement and water reducing agent. The calculation formula for the spacing between adjacent dynamic control drilling holes is:

[0066] L = 2tl 膏 (6)

[0067] Where, L is the distance between adjacent dynamically controlled drilling holes, m; t is the safety factor, which is 0.6; l 膏is the diffusion radius of paste filling slurry, m.

[0068] Multiple groups of dynamic control boreholes are constructed at intervals of L along the working face advancement direction 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 drilling holes Z on the left and right sides A1 and Z A2 , 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 flow law of the paste filling slurry is regarded as a standard normal distribution, and the main borehole Z is determined based on the flow law of the paste filling slurry. A And auxiliary drilling Z A1 and Z A2 The spacing F.

[0069] The standard normal distribution calculation formula is:

[0070]

[0071] Main drilling hole Z A And auxiliary drilling Z A1 and Z A2 The calculation formula for the spacing F is:

[0072] F=b×H×Φ(x) (8)

[0073] Where F is the main drilling hole Z A And auxiliary drilling Z A1 and Z A2 The spacing is m; b is the safety factor, which is 4 to 6; H is the maximum height of the separation space, m; Φ(x) is the standard normal distribution value, which is 0.7.

[0074] (3) Carry out dynamic regulation and build a support system

[0075] Through the surface grouting drilling hole of the working face A, a slurry made of fly ash, coal gangue and coal slime is injected into the stratum. The proportion of each component of the slurry is: 20% fly ash, 60% coal gangue and 20% coal slime. When the grouting filling of the stratum of the working face A is completed, the main drilling hole Z is used to inject the slurry into the stratum. A A paste filling slurry made of gangue, fly ash, cement and water reducing agent is injected into the determined dynamic control area under high pressure. The proportion of each component of the paste filling material is: 73.5% gangue, 10% fly ash, 15% cement and 1.5% water reducing agent. At the same time, the main drilling hole Z in the working face A is used to inject the paste filling slurry into the working face A. A Auxiliary drilling holes Z on both sides A1 and Z A2Inject quick-setting agent to accelerate the paste filling slurry to form a support body, and compact the collapsed gangue below to transform the non-compacted area into a compacted area. The quick-setting agent accounts for 5% of the volume of the injected paste filling slurry. Under the action of grouting pressure, the separation degree of the dynamic control area is further increased, and the paste filling slurry forms a key layer of support body support in the separation space to prevent it from breaking. After the support body is constructed, the auxiliary drilling hole Z A1 and Z A2 A slurry made of quick-setting cement, fly ash, coal gangue and coal slime is injected to fill the delamination expansion space on both sides of the support body after dynamic control, in which the proportion of each component is: quick-setting cement 10%, fly ash 40%, coal gangue 30% and coal slime 20%.

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

[0077] P 孔 >H m (γ-γ1)+C (9)

[0078] Where P 孔 is the grouting pressure at the orifice, MPa; H m is the buried depth of coal seam, 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 to 3MPa, and a value of 0 during normal grouting.

[0079] (4) Dynamic control effect detection and supplementary measures

[0080] After completing steps (1) to (3), survey lines are laid out on the surface of the dynamic control area and in the underground gob-side tunnels, and geophysical exploration methods such as magnetotelluric are used to detect the distribution of the support body in the stratum. At the same time, a check borehole is constructed at an angle α to the support body in the gob-side tunnels to detect whether the height of the support body reaches the maximum height of the stratum grouting filling of the working face A. On the other hand, a mechanical test is performed on the support body core to detect whether the strength of the support body meets the requirements.

[0081] When the distribution morphology of the support body does not meet the requirements, increase the proportion of water reducing agent and reduce the fluidity of the paste filling slurry. At this time, the proportions of the various components of the paste filling material are: coal gangue 72%, fly ash 10%, cement 15%, and water reducing agent 3%.

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

[0083] H c =S×sinα (10)

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

[0085] When the support strength does not meet the requirements, increase the proportion of cement in the paste filling material to increase the support strength. At this time, the proportions of the paste filling materials are: 63.5% coal gangue, 10% fly ash, 25% cement, and 1.5% water reducer. Through the above measures, the distribution shape, height and strength of the support meet the requirements.

[0086] (5) Continuous mining by grouting of multiple working faces

[0087] After the mining of working face B, the main drilling hole Z in working face A is used to A Right auxiliary drilling hole Z A2 At the same time as the grouting hole Z2 in the separation layer of the working face B, a slurry made of fly ash, coal gangue and coal mud is injected to fill the separation layer development space above the working face B and the separation layer expansion space on the right side of the support until the separation layer grouting filling work of the working face B is completed. Repeating the above steps (1) to (5) can realize the multi-working face coal pillar-free separation layer grouting filling mining based on dynamic control.

[0088] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" 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 ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0089] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that 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 on multiple working faces.

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 +(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 5 is characterized in that: 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 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 empty tunnel between working faces A and B.

7. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 6 is characterized in that: 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 support 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 Slurry made of quick-setting cement, fly ash, coal gangue and coal slime is injected to fill the remaining separation expansion space on both sides of the support body after dynamic control.

8. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 7 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.

9. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 8 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%.

10. The multi-working face non-pillar separation grouting filling mining method based on dynamic control according to claim 6, characterized in that: 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.

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