Roof grouting reinforcement method

Abstract

The invention relates to the technical field of coal seam mining, and provides a roof grouting reinforcement method. The roof grouting reinforcement method comprises the following steps that the grouting layer position is determined; directional grouting drill holes are formed in the extending direction of the grouting layer; and grouting is conducted in the directional grouting drill holes so as to reinforce the cracks. By arranging the directional grouting drill holes in the extending direction of the grouting layer, grouting blind areas can be reduced, and therefore the grouting reinforcement effect can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal seam mining, and particularly to a method for grouting and reinforcing the roof. Background Art

[0002] During the process of coal seam mining, when the fault structure affects some rock layers of the coal seam roof, the roof rock layers are prone to fragmentation, which may induce problems such as rib spalling and roof caving in the working face, increasing the safety production of the mine. In the prior art, grouting and reinforcement are mostly carried out by means of ordinary drilling, that is, mainly drilling roof holes from the return airway of the working face into the working face for grouting and reinforcement. The blind area between the grouting holes is relatively large, and the reinforcement effect is poor. Summary of the Invention

[0003] In view of the above technical problems, the present invention provides a method for grouting and reinforcing the roof.

[0004] A method for grouting and reinforcing the roof provided by the present invention includes the following steps: determining the grouting horizon; arranging directional grouting holes along the extension direction of the grouting horizon; and injecting grout into the directional grouting holes to reinforce the fissures.

[0005] According to the method for grouting and reinforcing the roof provided by the present invention, the step of determining the grouting horizon specifically includes: determining the caving ratio data based on the measured development height of the caving zone and the coal seam thickness. The caving ratio data K is calculated by the following formula (1).

[0006] K = H k ÷M (1).

[0007] Wherein, K is the caving ratio data; H k is the measured development height of the caving zone, and M is the coal seam thickness.

[0008] Based on the caving ratio data and the coal seam mining thickness of the treatment working face, determine the expected development height of the caving zone. The expected development height of the caving zone is calculated by the following formula (2).

[0009] H k1 = K × M2 (2).

[0010] Wherein, H k1 is the expected development height of the caving zone; M2 is the coal seam mining thickness of the treatment working face.

[0011] Based on the expected development height of the caving zone, determine the observation depth of the peephole. The observation depth of the peephole is calculated by the following formula (3).

[0012] L = H k1 (3).

[0013] Wherein, L is the observation depth of the peephole.

[0014] A roof grouting reinforcement method provided by the present invention, after the step of determining the observation depth of the peephole borehole based on the predicted development height of the caving zone, further includes: arranging a plurality of peephole boreholes with an observation depth of L at intervals in the working face return airway; counting the development characteristics of the borehole fissures through the peephole boreholes, and determining the fissure development horizon based on the borehole fissure development characteristics; determining the fissure development horizon as the grouting horizon.

[0015] A roof grouting reinforcement method provided by the present invention, the step of determining the fissure development horizon based on the borehole fissure development characteristics specifically includes: determining the fissure development horizon based on the fissure density and fissure aperture in the peephole borehole.

[0016] A roof grouting reinforcement method provided by the present invention, the step of arranging the directional grouting boreholes along the extension direction of the grouting horizon specifically includes: determining the grouting slurry concentration based on the rock permeability; determining the slurry diffusion radius based on the grouting slurry concentration and the preset grouting pressure; determining the arrangement interval of the directional grouting boreholes based on the slurry diffusion radius.

[0017] A roof grouting reinforcement method provided by the present invention, drilling in the peephole borehole and injecting water under pressure with the preset grouting pressure to obtain the rock permeability.

[0018] The step of determining the slurry diffusion radius based on the grouting slurry concentration and the preset grouting pressure specifically includes: determining the slurry diffusion radius through simulation based on the grouting slurry concentration and the preset grouting pressure.

[0019] The step of determining the arrangement interval of the directional grouting boreholes based on the slurry diffusion radius specifically includes: arranging the first directional grouting borehole at the middle position in the thickness direction of the working face, and arranging the remaining directional grouting boreholes at intervals with twice the slurry diffusion radius as the arrangement interval, and the distance between the edge of the directional grouting borehole and the roadway side is greater than the slurry diffusion radius.

[0020] A roof grouting reinforcement method provided by the present invention, the step of determining the arrangement interval of the directional grouting boreholes based on the slurry diffusion radius further includes: In the area between the directional grouting borehole closest to the roadway side and the roadway side, arranging a plurality of enhanced grouting boreholes at intervals, each enhanced grouting borehole is arranged along the direction perpendicular to the roadway, and the interval between adjacent enhanced grouting boreholes is less than the slurry diffusion radius.

[0021] A roof grouting reinforcement method provided by the present invention, the step of injecting grout into the directional grouting borehole to reinforce the fissures specifically includes: adopting the segmented progressive grouting method for full-hole grouting reinforcement, and the length of each grouting section is 3 - 5 times the slurry diffusion radius.

[0022] The steps of full-hole grouting reinforcement by adopting the segmented progressive grouting method specifically include: after the grouting reinforcement of each section is completed and the slurry starts to set, it is necessary to first carry out hole cleaning drilling construction, and then carry out the grouting reinforcement operation of the next section until the full-hole grouting reinforcement is completed.

[0023] According to a roof grouting reinforcement method provided by the present invention, after the step of grouting into the directional grouting borehole to reinforce the fissures, it further includes: grouting and reinforcing into each enhanced grouting borehole.

[0024] After the step of grouting and reinforcing into each enhanced grouting borehole, it further includes: Carrying out plugging grouting on the directional grouting borehole and the enhanced grouting borehole.

[0025] According to a roof grouting reinforcement method provided by the present invention, the roof grouting reinforcement method further includes: inspecting the grouting reinforcement effect.

[0026] In the roof grouting reinforcement method provided by the present invention, the following steps are included: determining the grouting horizon; arranging directional grouting boreholes along the extension direction of the grouting horizon; grouting into the directional grouting boreholes to reinforce the fissures. By arranging the directional grouting boreholes along the extension direction of the grouting horizon, the grouting blind area can be reduced, and thus, the grouting reinforcement effect can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a partial process schematic diagram of the roof grouting reinforcement method provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will further describe in detail the embodiments of the present invention in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0030] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the embodiments of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0031] In the description of the embodiments 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 embodiments of the present invention can be understood according to specific circumstances.

[0032] In the embodiments of the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher horizontal level than the second feature. The first feature being "under", "below" and "beneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower horizontal level than the second feature.

[0033] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0034] The following will describe Figure 1 a roof grouting reinforcement method provided by an embodiment of the present invention. It should be understood that the following is only a schematic embodiment of the present invention and does not constitute any special limitation to the present invention.

[0035] An embodiment of the present invention, as Figure 1 shown, provides a roof grouting reinforcement method, including the following steps: determining the grouting horizon; arranging directional grouting boreholes along the extension direction of the grouting horizon; injecting grout into the directional grouting boreholes to reinforce the fissures. By arranging the directional grouting boreholes along the extension direction of the grouting horizon, the grouting blind area can be reduced, and thus, the effect of grouting reinforcement can be greatly improved.

[0036] In one embodiment of the present invention, the step of determining the grouting horizon specifically includes: determining the caving ratio data based on the measured development height of the caving zone and the coal seam thickness, and the caving ratio data K is calculated by the following formula (1).

[0037] K = H k ÷ M (1).

[0038] Wherein, K is the caving ratio data; H k is the measured development height of the caving zone, and M is the coal seam thickness.

[0039] Based on the caving ratio data and the coal seam mining thickness of the treatment working face, the expected development height of the caving zone is determined, and the expected development height of the caving zone is calculated by the following formula (2).

[0040] H k1=K×M2 (2).

[0041] Wherein, H k1 is the predicted development height of the caving zone; M2 is the coal seam mining thickness of the treatment working face.

[0042] Based on the predicted development height of the caving zone, the observation depth of the peephole is determined, and the observation depth of the peephole is calculated by the following formula (3).

[0043] L = H k1 (3).

[0044] Wherein, L is the observation depth of the peephole.

[0045] In an embodiment of the present invention, after the step of determining the observation depth of the peephole based on the predicted development height of the caving zone, it further includes: arranging a plurality of peepholes with an observation depth of L at intervals in the working face return airway; counting the development characteristics of the borehole fissures through the peepholes, and determining the fissure development horizon based on the development characteristics of the borehole fissures; determining the fissure development horizon as the grouting horizon.

[0046] Further, in an embodiment of the present invention, the step of determining the fissure development horizon based on the development characteristics of the borehole fissures specifically includes: determining the fissure development horizon based on the fissure density and fissure aperture in the peephole.

[0047] Specifically, in the process of determining the grouting horizon, first, the caving ratio K is determined by combining the measured development height H of the caving zone around the working face k and the coal seam thickness M. Then, the predicted development height H of the caving zone is determined by combining the caving ratio K and the coal seam mining thickness M2 of the treatment working face k1 . Through the predicted development height H of the caving zone k1 the observation depth of the peephole can be determined. The observation depth of the peephole can be set as the borehole depth of the peephole. A plurality of peepholes are arranged at intervals in the working face return airway. For example, a peephole is arranged every 50 m. Each peephole is arranged along the direction perpendicular to the roadway roof. The development characteristics of the borehole fissures are counted through the peepholes. For example, the development characteristics of the borehole fissures include the fissure density and fissure aperture in the borehole. The position where the fissures are relatively developed can be determined through the fissure density and fissure aperture in the borehole. For example, when the fissure density and fissure aperture in each borehole reach a certain preset value, this horizon is determined as the fissure development horizon, and then, this fissure development horizon is determined as the grouting horizon.

[0048] In an embodiment of the present invention, the step of arranging the directional grouting boreholes along the extension direction of the grouting horizon specifically includes: determining the grouting slurry concentration based on the rock permeability; determining the slurry diffusion radius based on the grouting slurry concentration and the preset grouting pressure; determining the arrangement interval of the directional grouting boreholes based on the slurry diffusion radius.

[0049] In one embodiment of the present invention, drilling is carried out in the peephole, and water is injected under pressure with a preset grouting pressure to obtain the water permeability of the rock formation.

[0050] The step of determining the slurry diffusion radius based on the grouting slurry concentration and the preset grouting pressure specifically includes: determining the slurry diffusion radius through simulation based on the grouting slurry concentration and the preset grouting pressure. For example, the COMSOL numerical simulation software can be used to simulate and determine the slurry diffusion radius.

[0051] The step of determining the layout interval of the directional grouting holes based on the slurry diffusion radius specifically includes: arranging the first directional grouting hole at the middle position in the thickness direction of the working face, and arranging the remaining directional grouting holes at intervals with twice the slurry diffusion radius as the layout interval, and the distance between the edge of the directional grouting hole and the roadway side is greater than the slurry diffusion radius.

[0052] Specifically, for example, the preset grouting pressure is set to 12 MPa. Drilling is carried out into the peephole with a drilling diameter of 120 mm, and the water injection pressure is set to 12 MPa for water injection under pressure to obtain the water permeability of the rock formation. The appropriate slurry concentration is determined according to the water permeability of the rock formation. For example, the grouting slurry is a single-fluid cement slurry. The appropriate concentration of the single-fluid cement slurry is determined according to the water permeability of the rock formation. For example, the higher the water permeability of the rock formation, the greater the applicable concentration of the single-fluid cement slurry.

[0053] Based on the preset grouting pressure and the determined slurry concentration, the COMSOL numerical simulation software is used for simulation to obtain the slurry diffusion radius.

[0054] After obtaining the slurry diffusion radius, the layout of the directional grouting holes is started. Specifically, first, the first directional grouting hole is arranged at the middle position in the thickness direction of the grouting layer. Then, the remaining directional grouting holes are arranged at intervals with twice the slurry diffusion radius as the layout interval. The distance between the edge of each directional grouting hole and the roadway side is greater than the slurry diffusion radius.

[0055] After the layout of the above-mentioned directional grouting holes is completed, there is a certain blind area between the roadway side and the nearest directional grouting hole. In order to further improve the grouting reinforcement effect, in one embodiment of the present invention, the step of determining the layout interval of the directional grouting holes based on the slurry diffusion radius further includes: arranging a plurality of strengthening grouting holes at intervals in the area between the nearest directional grouting hole to the roadway side and the roadway side. Each strengthening grouting hole is arranged along the direction perpendicular to the roadway, and the interval between adjacent strengthening grouting holes is less than the slurry diffusion radius.

[0056] In an embodiment of the present invention, the step of grouting into the directional grouting borehole to reinforce the fissures specifically includes: performing full-hole grouting reinforcement by means of segmented progressive grouting, and the length of each grouting section is 3 to 5 times the slurry diffusion radius.

[0057] The step of performing full-hole grouting reinforcement by means of segmented progressive grouting specifically includes: after each section of grouting reinforcement is completed and the slurry begins to set, it is necessary to first perform hole cleaning drilling construction, and then perform the next section of grouting reinforcement operation until the full-hole grouting reinforcement is completed.

[0058] Further, in an embodiment of the present invention, after the step of grouting into the directional grouting borehole to reinforce the fissures, it further includes: grouting and reinforcing into each enhanced grouting borehole.

[0059] After the step of grouting and reinforcing into each enhanced grouting borehole, it further includes: performing plugging grouting on the directional grouting borehole and the enhanced grouting borehole.

[0060] Specifically, according to the geological conditions, drilling conditions and grouting conditions, determine the grouting length for each time during the segmented progressive grouting process. For example, the grouting length Lg for each time is 3 times the slurry diffusion radius. After drilling a length of 3 times the diffusion radius, perform grouting reinforcement. After the slurry begins to set, perform hole cleaning drilling construction, that is, clean out the solidified slurry in the drilling hole. Then perform the next section of drilling and grouting operation. Repeat this process until the full-hole grouting reinforcement is completed. After that, perform grouting reinforcement on the enhanced grouting borehole in the same way. For example, use a casing with a diameter of 108 mm, and its pressure resistance test should reach the preset pressure of 12 MPa, and the length of the grouting pipe should not be less than 10 m to extend the drilling construction, and the diameter of the open hole is 75 mm. Finally, it is necessary to perform plugging grouting on the directional grouting borehole and the enhanced grouting borehole.

[0061] In an embodiment of the present invention, the roof grouting reinforcement method further includes: inspecting the grouting reinforcement effect.

[0062] After completing the grouting reinforcement operations of the directional grouting borehole and the enhanced grouting borehole, it is necessary to inspect the grouting reinforcement effect. For example, methods such as using tracers and the proportion of cement components in the rock powder returned by the cement slurry during the construction of branch holes can be used to inspect the grouting effect.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A roof grouting reinforcement method, characterized in that: The following steps are involved: Determine the grouting layer; Directional grouting drill holes are arranged along the extension direction of the grouting layer; Grout is injected into the directional grouting borehole to reinforce the cracks.

2. The roof grouting reinforcement method according to claim 1, characterized in that: The step of determining the grouting layer position specifically includes: The collapse ratio data is determined based on the measured collapse zone development height and coal seam thickness. The collapse ratio data K is calculated using the following formula (1): K=H k ÷M (1); Among them, K is the collapse ratio data; H k is the measured development height of the collapse zone, M is the thickness of the coal seam; The expected development height of the collapse zone is determined based on the collapse ratio data and the mining thickness of the coal seam at the management working face. The expected development height of the collapse zone is calculated using the following formula (2): H k1 =K×M2 (2); Among them, H k1 is the expected height of the collapse zone; M2 is the mining thickness of the coal seam at the governance working face; The observation depth of the peep hole is determined based on the expected height of the collapse zone, and the observation depth of the peep hole is calculated using the following formula (3): L=H k1 (3) Wherein, L is the observation depth of the peephole.

3. The roof grouting reinforcement method according to claim 2, characterized in that: After the step of determining the observation depth of the peep borehole based on the expected height of the collapse zone, the method also includes: Multiple peep holes with an observation depth of L are arranged at intervals in the mining tunnel of the working face; By observing the boreholes, the characteristics of borehole fracture development are counted, and the fracture development layer is determined based on the characteristics of borehole fracture development; Determine the layer where fractures develop as the grouting layer.

4. The roof grouting reinforcement method according to claim 3, characterized in that: The step of determining the fracture development layer based on the borehole fracture development characteristics specifically includes: The fracture development layer is determined based on the fracture density and fracture aperture in the peep borehole.

5. The roof grouting reinforcement method according to claim 4, characterized in that: The step of arranging directional grouting holes along the extension direction of the grouting layer specifically includes: Determine the concentration of grouting slurry based on the rock formation permeability; Determine the slurry diffusion radius based on the grouting slurry concentration and the preset grouting pressure; Based on the slurry diffusion radius, the layout interval of directional grouting drilling holes is determined.

6. The roof grouting reinforcement method according to claim 5, characterized in that: Drill in the peep hole and perform pressure injection with a preset grouting pressure to obtain the permeability of the rock formation; The step of determining the slurry diffusion radius based on the grouting slurry concentration and the preset grouting pressure specifically includes: Based on the grouting slurry concentration and the preset grouting pressure, the slurry diffusion radius is determined through simulation; The step of determining the layout interval of directional grouting drilling holes based on the slurry diffusion radius specifically includes: The first directional grouting borehole is arranged in the middle of the working face in the thickness direction, and the remaining directional grouting boreholes are arranged at intervals of twice the slurry diffusion radius. The distance between the edge of the directional grouting borehole and the side of the tunnel is greater than the slurry diffusion radius.

7. The roof grouting reinforcement method according to claim 6, characterized in that: The step of determining the layout interval of the directional grouting boreholes based on the slurry diffusion radius also includes: In the area between the directional grouting borehole closest to the tunnel wall and the tunnel wall, multiple reinforced grouting boreholes are arranged at intervals. Each reinforced grouting borehole is arranged in a direction perpendicular to the tunnel, and the interval between adjacent reinforced grouting boreholes is smaller than the slurry diffusion radius.

8. The roof grouting reinforcement method according to claim 7, characterized in that: The step of injecting grout into the directional grouting borehole to reinforce the cracks specifically includes: The whole hole grouting reinforcement is carried out by means of segmented progressive grouting, and the length of each grouting section is 3 to 5 times the slurry diffusion radius; The step of performing full-hole grouting reinforcement by means of segmented progressive grouting specifically includes: After each section of grouting reinforcement is completed and the slurry has initially set, it is necessary to carry out the hole sweeping drilling construction first, and then carry out the next section of grouting reinforcement operation until the full hole grouting reinforcement is completed.

9. The roof grouting reinforcement method according to claim 8, characterized in that: After the step of injecting grout into the directional grouting borehole to reinforce the cracks, the method further comprises: Grouting reinforcement is carried out into each reinforced grouting borehole; After the step of grouting and reinforcing each reinforced grouting borehole, the method further comprises: Seal grouting is carried out on directional grouting boreholes and enhanced grouting boreholes.

10. The roof grouting reinforcement method according to any one of claims 1 to 9, characterized in that: The top plate grouting reinforcement method also includes: Check the grouting reinforcement effect.

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