Method for preventing and treating roof water in working face by horizontal long borehole directional blasting and grouting

Abstract

The application provides a method for preventing and treating roof water of a working face by horizontal long borehole directional blasting and grouting, comprising the following steps: step 1, determining the fine layer of the roof water-rich sandstone; step 2, determining the horizontal position of the closed curtain relative to the working face; step 3, vertically constructing a roof large-diameter horizontal long borehole group in the fine layer of the roof water-rich sandstone; step 4, loading a shaped tube and explosives into the roof large-diameter horizontal long borehole group to generate vertical cracks; and step 5, grouting into each roof large-diameter horizontal long borehole, and the grout expands along the vertical cracks generated in step 4 and waits for solidification to form a closed curtain. The method of the application uses the roof large-diameter horizontal long borehole to cooperate with the directional blasting cutting seam technology, effectively grouts to reconstruct the waterproof curtain, and pre-reforms the high-permeable water-bearing layer to reduce the water inflow of the working face and achieve the purpose of water conservation coal mining.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety technology, and relates to water on the roof of the working face, specifically to a method for preventing water on the roof of the working face by directional blasting grouting in horizontal long boreholes. Background Technology

[0002] Current mine water hazard prevention technologies typically employ pre-mining drainage and increased drainage capacity. However, these methods have drawbacks: they fail to achieve in-situ water resource protection. After the strong water-rich rock strata are broken during mining, water continuously flows into the goaf along water-conducting fissures, becoming the main source of mine water inflow. Coal mines need continuous drainage to maintain the safety of underground working spaces, resulting in significant water waste. Therefore, achieving in-situ water resource protection is of great significance for coal mine water control. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preventing water from the roof of the working face by horizontal long borehole directional blasting grouting, and to solve the technical problem that the existing methods are prone to water waste.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A method for preventing water in the roof of a working face by directional blasting grouting with horizontal long boreholes, the method comprising the following steps:

[0006] Step 1: Based on the geological data of the minefield, the mining subsidence data of the surrounding mining areas, and the exploration data of the height of water-conducting fractures, determine the fine stratigraphic position of the water-rich sandstone in the roof.

[0007] Step 2: Determine the horizontal position of the closed curtain relative to the working surface based on the working surface location.

[0008] Step 3: Vertically construct a group of large-diameter horizontal long boreholes in the fine strata of the water-rich sandstone in the top plate.

[0009] Step 4: Insert shaped charge tubes and explosives into the large-diameter horizontal long borehole group in the top plate, and blast to create vertical cracks.

[0010] Step 5: Inject grout into the large-diameter horizontal long boreholes in each top plate. The grout will bond and expand along the vertical cracks generated in Step 4, and wait for it to solidify to form a closed curtain on all sides.

[0011] Step 6: The working face is back-mined until the stop line is reached.

[0012] Compared with the prior art, the present invention has the following technical effects:

[0013] (I) The method of the present invention utilizes large-diameter horizontal long boreholes in the roof combined with directional blasting and cutting technology to effectively grout and recreate the water-resistant curtain, advance the transformation of high-permeability aquifers, reduce the water inflow at the working face, and achieve the purpose of water-conserving coal mining.

[0014] (II) The method of this invention precisely constructs a water-blocking curtain before mining by combining large-diameter directional horizontal long boreholes with shaped charge blasting and grouting techniques, significantly reducing the permeability of the main aquifer before mining. Constructing a closed curtain around the mining face effectively blocks the lateral water-guiding channels of the aquifer, enabling regional modification of the permeability of the thick aquifer, thus achieving in-situ protection of water resources, significantly reducing mine water inflow, and saving substantial drainage costs.

[0015] (III) The method of the present invention is simple to operate, highly adaptable, and has low construction cost. It is conducive to the construction of ecological civilization in coal mining areas and has strong promotion and application value. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the working surface closed curtain layout of the present invention.

[0017] Figure 2 This is a cross-sectional schematic diagram of the arrangement of a group of large-diameter horizontal long boreholes on the top plate on the side of the working face of the present invention.

[0018] Figure 3 This is a schematic diagram of vertical cracks created by blasting.

[0019] Figure 4 This is a schematic cross-sectional view of the closed curtain of the working surface of the present invention.

[0020] The meanings of the labels in the diagram are as follows: 1-working face, 2-closed curtain, 3-main roadway, 4-large diameter horizontal long borehole in the roof, 5-vertical fissure.

[0021] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, all devices in this invention are devices known in the prior art.

[0023] In this invention, a horizontal long drill hole refers to a large-diameter horizontal long drill hole in the top plate. The diameter range of the large-diameter horizontal long drill hole in the top plate is 100mm to 400mm, preferably 100mm to 300mm, and more preferably 100mm to 200mm.

[0024] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0025] Example 1:

[0026] This embodiment provides a method for preventing water in the roof of a working face by horizontal long-hole directional blasting grouting, which is carried out according to the following steps:

[0027] Step 1: Obtain geological data of the mining area, mining subsidence data of the surrounding mining area, and water-conducting fracture height exploration data. Use fiber optic gratings to monitor the fine stratigraphic positions H0 to H1 of the water-rich sandstone in the roof. The fine stratigraphic positions of the water-rich sandstone in the roof are the locations of the vertical stratigraphic positions that need to be modified.

[0028] in:

[0029] H0 is the upper limit of the burial depth of the fine strata of the water-rich sandstone in the top plate;

[0030] H1 represents the lower limit of the burial depth of the fine-grained strata of the water-rich sandstone in the top plate.

[0031] Step 2: Determine the horizontal position of the closed curtain relative to the working surface based on the planar position of the working surface.

[0032] In this embodiment, the schematic diagram of the closed curtain layout on the working surface is as follows: Figure 1 As shown.

[0033] The planar position of the working surface includes the orientation length W of the working surface. s and the dip length W of the working face t .

[0034] The horizontal position of the closed curtain setup includes the horizontal distance R between the projections of the closed curtain boundary and the working surface boundary on the same plane, and the length L of the horizontal long borehole. s And the slant length L of the horizontal long borehole t .

[0035] In step 2, the horizontal distance R between the projections of the boundary of the closed curtain and the boundary of the working surface onto the same plane is determined by the following formula:

[0036] R = H / tanδ

[0037] In the formula,

[0038] R is the horizontal distance between the projections of the boundary of the closed curtain and the boundary of the working surface onto the same plane, in meters.

[0039] H is the vertical distance between the water-rich sandstone roof and the coal seam roof, in meters.

[0040] δ is the rock fracture angle, in degrees.

[0041] In step 2, the direction length L of the horizontal long borehole s And the slant length L of the horizontal long borehole t Determined by the following formula:

[0042] L S =W s +2R

[0043] L t =W t +2R

[0044] In the formula,

[0045] W S The length of the working face, in meters;

[0046] L S The length of the horizontal borehole is expressed in meters (m).

[0047] W t The dip length of the working face, in meters;

[0048] L t The slant length of a horizontal long borehole is expressed in meters (m).

[0049] Step 3: Determine the spacing S of the large-diameter boreholes in the roof based on the diameter D of the large-diameter boreholes, the diameter of the explosive, the density of the explosive, the charge radius of the explosive, and the tensile strength of the rock. Combine this with the direction length L of the horizontal long boreholes in the roof obtained in Step 2. s The inclined length L of the horizontal long borehole in the top plate t A group of large-diameter horizontal long boreholes was drilled into the roof slab during construction.

[0050] In this embodiment, a cross-sectional schematic diagram of the arrangement of large-diameter horizontal long boreholes on the side of the working face is shown below. Figure 2 As shown.

[0051] In step 3, the spacing S between the large-diameter drill holes in the top plate satisfies the following condition:

[0052]

[0053] In the formula:

[0054] ρ0 is the density of the explosive;

[0055] λ is the focusing coefficient;

[0056] n is the pressure increase coefficient of the explosive gas;

[0057] d c The diameter of the explosive;

[0058] D is the diameter of the blast hole;

[0059] V max This is the maximum detonation velocity of the explosive;

[0060] μ is the Poisson's ratio of the rock;

[0061] σ T The tensile strength of the blasted rock;

[0062] r0 is the charge radius;

[0063] α is the attenuation coefficient.

[0064] Step 4: Insert shaped charge tubes and explosives into the large-diameter horizontal long borehole group in the top plate, and blast to create vertical cracks.

[0065] A schematic diagram of the vertical cracks generated by the blasting in this embodiment is shown below. Figure 3 As shown,

[0066] Step 5: Grout is injected into the large-diameter horizontal long boreholes in each top plate. The grout adheres and expands along the vertical cracks generated in Step 4, and waits for solidification to form a closed curtain around the perimeter.

[0067] In this embodiment, the inclined cross-sectional schematic diagram of the closed curtain at the working surface is as follows: Figure 4 As shown.

[0068] Step 6: The working face is back-mined until the stop line is reached.

Claims

1. A method for preventing water in the roof of a working face by directional blasting grouting with horizontal long boreholes, characterized in that, This method is performed according to the following steps: Step 1: Obtain geological data of the mining area, mining subsidence data of the surrounding mining area, and water-conducting fracture height exploration data. Use fiber optic gratings to monitor the fine stratigraphic position H0 to H1 of the water-rich sandstone on the roof. The fine stratigraphic position of the water-rich sandstone on the roof is the location of the vertical stratigraphic position that needs to be modified. in: H0 is the upper limit of the burial depth of the fine strata of the water-rich sandstone in the top plate; H1 represents the lower limit of the burial depth of the fine-grained strata of the water-rich sandstone in the top plate; Step 2: Determine the horizontal position of the closed curtain relative to the working surface based on the planar position of the working surface; The planar position of the working surface includes the orientation length W of the working surface. s and the dip length W of the working face t , The horizontal position of the closed curtain setup includes the horizontal distance R between the projections of the closed curtain boundary and the working surface boundary on the same plane, and the length L of the horizontal long borehole. s And the slant length L of the horizontal long borehole t ; In step 2, the horizontal distance R between the projections of the boundary of the closed curtain and the boundary of the working surface onto the same plane is determined by the following formula: R = H / tanδ; In the formula, R is the horizontal distance between the projections of the boundary of the closed curtain and the boundary of the working surface onto the same plane, in meters. H is the vertical distance between the water-rich sandstone roof and the coal seam roof, in meters. δ is the rock fracture angle, in degrees. Step 3: Determine the spacing S of the large-diameter boreholes in the roof based on the diameter D of the large-diameter boreholes, the diameter of the explosive, the density of the explosive, the charge radius of the explosive, and the tensile strength of the rock. Combine this with the direction length L of the horizontal long boreholes in the roof obtained in Step 2. s The inclined length L of the horizontal long borehole in the top plate t Large-diameter horizontal long borehole group for construction of the roof slab; In step 3, the spacing S between the large-diameter drill holes in the top plate satisfies the following condition: ； In the formula: ρ 0 represents the density of the explosive; λ The energy concentration factor; n This is the pressure increase coefficient of the explosive gas; d c The diameter of the explosive; D The diameter of the blast hole; V max This is the maximum detonation velocity of the explosive; μ is the Poisson's ratio of the rock; σ T The tensile strength of the blasted rock; r 0 represents the charge radius; α The attenuation coefficient; Step 4: Insert shaped charge tubes and explosives into the large-diameter horizontal long borehole group in the top plate, and blast to create vertical cracks; Step 5: Grout is injected into the large-diameter horizontal long boreholes in each top plate. The grout adheres and expands along the vertical cracks generated in Step 4, and waits for solidification to form a closed curtain around the perimeter.

2. The method for preventing water in the roof of a working face by horizontal long-hole directional blasting grouting as described in claim 1, characterized in that, In step 2, the direction length L of the horizontal long borehole s And the slant length L of the horizontal long borehole t Determined by the following formula: L S =W s +2R; L t =W t +2R; In the formula, W S The length of the working face, in meters; L S The length of the horizontal borehole is expressed in meters (m). W t The dip length of the working face, in meters; L t The slant length of a horizontal long borehole is expressed in meters (m).

3. The method for preventing water in the roof of a working face by horizontal long-hole directional blasting grouting as described in claim 1, characterized in that, It also includes step 6, where the working face is back-mined until the stop line is reached.

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