Ground exploration and treatment method for local permeable skylight of coal seam roof

Abstract

The invention discloses a ground exploration and treatment method for a local permeable skylight of a coal seam roof, which realizes fine positioning of a line-to-plane area of a missing area of a water-proof soil layer of the coal seam roof by means of construction of a directional main hole and a plurality of branch holes. In this way, the problems that in the prior art, ground vertical drilling is adopted to conduct core drilling and positioning on the specific range of the soil layer missing area through point location and hole alignment, the blindness of drilling hole location arrangement is large, the drilling work amount is large, the core drilling work amount is large, invalid footage is large, and efficiency is not high are solved. Meanwhile, grouting transformation is conducted on a soil layer missing area of the enclosure by means of a constructed directional main hole and a plurality of branch holes, it is guaranteed that no missing area exists, advanced grouting treatment of a concentrated permeable skylight in the coal seam mining process is achieved, and water gushing and sand inrush of an earth surface loose aquifer and underground water resource leakage source control are achieved; the method is suitable for large-scale industrial use and popularization.

Description

Technical Field

[0001] The present invention belongs to the field of mine water prevention and control and groundwater resource protection, and particularly relates to a ground exploration and treatment method for a local water-permeable skylight on a coal seam roof. Background Art

[0002] The Shaanxi Coal Base, a core region for coal resource development in my country, is home to numerous areas of soil loss within its mining areas. Detailed exploration of these areas is essential for effectively preventing and controlling coal seam roof flooding and protecting the source of groundwater resources in the near-surface, water-rich, loose layers. Because these areas are often concealed, their planar boundaries are irregularly distributed. Traditionally, vertical surface drilling has been used to locate the specific extent of these areas through "point" and "dual-hole" coring. Coring the entire borehole section is then used to analyze whether soil loss exists. Only when adjacent boreholes, one with soil and one without, are drilled together to gradually approximate and confirm the boundaries of the missing areas. This often results in blind drill hole placement, extensive drilling and coring work, high inefficiency, and the need for all boreholes to penetrate various upper soil strata. Furthermore, these areas often lack the necessary exploration resources to provide a foundation for preventing and controlling water damage from permeable skylights and protecting groundwater resources in these areas. Summary of the Invention

[0003] The purpose of the present invention is to provide a ground exploration and treatment method for local water-permeable skylights in coal seam roofs, so as to solve the problems of low exploration efficiency and missed areas in the prior art.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A method for ground exploration and treatment of local water-permeable skylights in coal seam roofs comprises the following steps:

[0006] Step 1: Collect geological and hydrogeological drilling data of the area to be treated and preliminarily identify the area with missing soil layers as the study area;

[0007] Step 2: Draw a contour map of the top elevation of the soil layer in the study area and identify a set of long axes of potential soil layer missing areas;

[0008] Step 3: Draw a contour map of the thickness of the roof soil layer of the coal seam in the study area, and then identify a set of long axes of potential soil missing areas;

[0009] Step 4: Obtain the long axes of two sets of potential soil layer missing areas according to Steps 2 and 3, draw an equidistant line between the long axes of the two sets of potential soil layer missing areas, and determine the actual long axes of the potential soil layer missing areas based on the equidistant line;

[0010] Step 5: Design a ground directional drilling main hole upstream of the top boundary elevation of the soil layer in the soil layer coverage area of ​​the study area along the actual long axis direction of the potential soil layer missing area determined in step 4;

[0011] Step 6: directional drilling is carried out according to the designed ground directional drilling main hole, and rock cuttings are continuously fished out during the directional drilling process. The provenance type of the rock cuttings is determined each time the rock cuttings are fished out.

[0012] If the provenance type of the recovered cuttings changes from soil to loose rock, the position of the main directional drilling hole is adjusted and drilling is continued while the cuttings are continuously recovered. The provenance type of the cuttings is determined each time the cuttings are recovered until the main directional drilling hole is formed.

[0013] During the directional drilling process, if the provenance type of the rock cuttings retrieved changes from loose rock to soil, the drilling is stopped and the drill hole formed is designated as the main hole for ground directional drilling.

[0014] Step 7: Directional branch holes are designed and constructed in sequence from the center of the main ground directional drill hole to the periphery. The trap area formed by all the sequentially constructed directional branch holes is the actual soil layer missing area;

[0015] Step 8: Drill directional branch holes in sequence according to the design, and carry out grouting transformation during the drilling process to achieve the treatment of centralized permeable skylights on the coal seam roof and control the source of water gushing from the roof.

[0016] The present invention also has the following features:

[0017] Furthermore, in step 2, when drawing the soil layer top boundary elevation contour map of the study area, the elevation contour map is drawn by interpolation method with an elevation contour interval of 1 to 10 m, and a group of potential soil layer missing area long axes are identified by connecting the maximum curvature points of each contour line.

[0018] Furthermore, in step 3, when drawing the thickness contour map of the coal seam roof soil layer in the research area, the thickness contour map of the coal seam roof soil layer in the research area is drawn by interpolation method with a thickness contour line interval of 1 to 10 m;

[0019] The contour line with the smallest value in the contour map of the thickness of the coal seam roof is identified as the long axis of the potential soil layer missing area.

[0020] Furthermore, in step 6, during the directional drilling of the designed ground directional drilling main hole, rock removal is performed every 1 m of footage.

[0021] Furthermore, step 6 includes the following sub-steps:

[0022] Step 61: Conduct a directional drilling along the designed ground directional drilling main hole and perform rock removal to determine whether the ground directional drilling main hole has been formed.

[0023] If it has already formed, stop drilling;

[0024] If not formed, proceed to step 62;

[0025] Step 62, determining the provenance type of the rock cutting retrieved this time;

[0026] If the rock cuttings retrieved this time are of loose rock strata provenance, proceed to step 63;

[0027] If the rock cuttings retrieved this time are of soil origin, then proceed to step 64;

[0028] Step 63: suspend directional drilling, design a vertical core drilling hole at the corresponding ground position, and perform vertical core drilling to the bedrock layer; and determine whether there is a soil layer based on the core drilling results;

[0029] If there is a soil layer, proceed to step 65;

[0030] If there is no soil layer, the ground position corresponding to the position when the directional drilling was paused is used as the upstream boundary of the soil layer missing area, and the process returns to step 61;

[0031] Step 64: Stop drilling, set the drill hole that has been formed as the main ground directional drilling hole, and use the ground position corresponding to the rock cutting where the soil material was salvaged as the downstream boundary of the soil missing area;

[0032] Step 65, redesigning the near-horizontal section of the ground directional drilling main hole according to the thickness of the soil layer and then returning to step 61.

[0033] Furthermore, in step 61, the footage of each directional drilling is 1 m;

[0034] In step 65, when redesigning the near-horizontal section of the main hole of the ground directional drilling, the near-horizontal section of the directional drilling is readjusted based on the soil layer thickness confirmed by vertical drilling coring and the middle position of the soil layer.

[0035] Furthermore, in step 7, directional branch holes are sequentially constructed from the center of the directional drill main hole to the periphery with a hole spacing of 40-60m in the near-horizontal section, and the drilling is performed using the methods of steps 5 and 6;

[0036] The range of the trap formed by connecting the starting points of the unremoved soil layer rock cutting and the starting points of the removed soil layer rock cutting within the range of each directional branch hole is the actual soil layer missing area.

[0037] Furthermore, in step 8, starting from a directional branch hole where the rock cutting starting point is not fished out, cement single liquid slurry or mixed slurry is used to carry out segmented grouting at a depth of 20-50 m while continuing the directional drilling process until the grouting end standard is reached;

[0038] After the previous grouting is completed, multiple grouting sections are continued at intervals of 20 to 50 m. Each grouting section is terminated after the grouting completion criteria are met. Drilling and grouting are stopped until the directional branch hole reaches the soil layer and rock cutting.

[0039] The above method is used to traverse each directional branch hole, complete the grouting transformation, and realize the treatment of the centralized permeable skylights in the coal seam roof and the control of the water gushing source of the roof.

[0040] Furthermore, the mixed slurry in step 8 is cement fly ash mixed slurry or cement clay mixed slurry;

[0041] Among them, the water-solid ratio is 0.8-1.1.

[0042] Furthermore, the grouting end standard in step 8 is: after reaching the maximum grouting pressure standard, reduce the pump volume to 60L / min and maintain it for 30min;

[0043] The maximum grouting pressure P is determined using the following formula:

[0044] P=(1.5-2)*H / 100

[0045] Wherein, H represents the burial depth of the grouting section, in meters.

[0046] Compared with the prior art, the present invention has the following technical effects:

[0047] The method for ground exploration and treatment of local permeable windows in the coal seam roof of the present invention relies on the construction of a directional main hole and several branch holes to achieve precise positioning of the "line to surface" area of ​​the missing water-proof soil layer in the coal seam roof. This overcomes the many problems of the traditional method of using ground vertical drilling to locate the specific range of the missing soil layer area through "point" and "paired hole" drilling and coring, such as large blindness in the arrangement of drilling holes, large drilling workload, large coring workload, many invalid footages, and low efficiency. At the same time, the constructed directional main hole and several branch holes are used to carry out grouting transformation of the enclosed missing soil layer area, ensuring that there are no missed areas, realizing the advanced grouting treatment of concentrated permeable windows in the coal seam mining process, and controlling the source of water gushing and sand bursting in the loose surface aquifer and groundwater resource loss, which is suitable for large-scale use and promotion in industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a distribution map of the missing area of ​​the water-repellent soil layer in a certain mining area in a certain place in the prior art;

[0049] Figure 2This is the distribution map of the coring exploration project in the soil layer missing area in the existing technology;

[0050] Figure 3 and 4 This is a schematic diagram of preliminarily delineating the spatial extent of a soil layer missing area based on the actual spatial distribution of drill holes in the soil layer in one embodiment of the present invention;

[0051] Figure 5 is a schematic diagram of the long axis of a soil layer missing area determined using equidistant lines in one embodiment of the present invention;

[0052] Figure 6 Schematic diagram of directional drilling rock cutting identification and vertical drilling coring confirmation in a soil layer missing area in one embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram of directional exploration and positioning of a soil layer missing area in one embodiment of the present invention;

[0054] Figure 8 This is a schematic diagram of directional exploration and grouting treatment of soil layer missing areas in one embodiment of the present invention;

[0055] Figure 9 It is a schematic diagram of directional exploration and grouting treatment of permeable skylights in a soil layer missing area in one embodiment of the present invention. DETAILED DESCRIPTION

[0056] It should be noted that, unless otherwise specified, all methods in the present invention adopt methods known in the prior art.

[0057] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0058] like Figure 1 As shown in the figure, the northern Shaanxi coal base, a core region for coal resource development in my country, has numerous areas of soil loss within the mining area. Detailed exploration of these areas is essential for effectively preventing and controlling coal seam roof flooding and protecting the source of groundwater resources in the near-surface, water-rich, loose layers. Because these areas of soil loss are often concealed (covered by loose layers at the surface), their planar boundaries are irregularly distributed (skylights eroded by rainwater gullies generally follow a nearly ellipsoidal, strip-like pattern).

[0059] like Figure 2As shown in the figure, the traditional method uses ground vertical drilling to locate the specific range of the soil missing area through "point" and "paired hole" drilling and coring (by coring the entire hole section to analyze whether there is a soil missing area, and when one of the adjacent holes has a soil layer and the other does not have a soil layer, the paired holes can gradually approach and confirm the boundary of the missing area). There are often problems such as large blindness in the arrangement of drilling holes, large drilling and coring projects, many invalid footages (all boreholes need to pass through various strata above the soil layer), low efficiency, and the existence of missed areas. It is difficult to provide a basic basis for the prevention and control of water hazards of permeable skylights and the protection of groundwater resources in soil missing areas.

[0060] In view of the above situation, a specific embodiment of the present invention is given:

[0061] A method for ground exploration and treatment of local water-permeable skylights in coal seam roofs comprises the following steps:

[0062] Step 1: Collect geological and hydrogeological drilling data of the area to be treated, and preliminarily identify the soil loss area as the study area, such as Figure 3 and 4 As shown;

[0063] Step 2: Draw a contour map of the top elevation of the soil layer in the study area and identify a set of long axes of potential soil layer missing areas;

[0064] Step 3: Draw a contour map of the thickness of the coal seam roof in the study area, take the contour line with the minimum value as the standard, and then identify a set of long axes of potential soil layer missing areas;

[0065] Step 4: Obtain the long axes of two sets of potential soil layer missing areas according to Steps 2 and 3, draw an equidistant line between the long axes of the two sets of potential soil layer missing areas, and determine the actual long axes of the potential soil layer missing areas based on the equidistant line;

[0066] The soil strata in coal mining areas are generally lake-facies sedimentary strata, similar to a calm lake surface. Under uneroded geological conditions, their thickness and elevation distribution are relatively flat and stable. When locally subjected to geological erosion, the strata will become locally thinner, accompanied by a significant decrease in elevation. Therefore, with sufficient geological drilling information, the scope of the skylight area can be preliminarily delineated based on the lowering of elevation or the thinning of thickness. However, geological drilling in general mining areas is limited, and the top surface of the soil layer is unstable under the action of geological weathering, wind erosion, and scouring, making it difficult to delineate it using only one indicator, elevation or thickness. Therefore, this case makes full use of the relatively scarce geological drilling information to comprehensively identify the main axis of the skylight area based on the two factors of elevation and thickness, which has a higher scientific basis and accuracy.

[0067] Step 5: Design a ground directional drilling main hole upstream of the top boundary elevation of the soil layer in the soil layer coverage area of ​​the study area along the actual long axis direction of the potential soil layer missing area determined in step 4;

[0068] Upstream of the top boundary elevation of the soil layer in the soil coverage area, the main ground directional drilling hole is designed along the long axis direction of the potential soil layer missing area determined by analysis. According to the distribution of soil layer thickness contour lines, the ground opening position is located in the confirmed coverage area, and the nearly horizontal directional section below the surface is designed to drill the geological borehole that originally exposed the soil layer outside the initially delineated soil layer missing area, and then continue directional drilling along the potential long axis direction.

[0069] Step 6: directional drilling is carried out according to the designed ground directional drilling main hole, and rock cuttings are continuously fished out during the directional drilling process. The provenance type of the rock cuttings is determined each time the rock cuttings are fished out.

[0070] If the provenance type of the recovered cuttings changes from soil to loose rock, the position of the main directional drilling hole is adjusted and drilling is continued while the cuttings are continuously recovered. The provenance type of the cuttings is determined each time the cuttings are recovered until the main directional drilling hole is formed.

[0071] During the directional drilling process, if the provenance type of the rock cuttings retrieved changes from loose rock to soil, the drilling is stopped and the drill hole formed is designated as the main hole for ground directional drilling.

[0072] Step 7: Directional branch holes are designed and constructed in sequence from the center of the main ground directional drill hole to the periphery. The trap area formed by all the sequentially constructed directional branch holes is the actual soil layer missing area;

[0073] Step 8: Drill directional branch holes in sequence according to the design, and carry out grouting transformation during the drilling process to achieve the treatment of centralized permeable skylights on the coal seam roof and control the source of water gushing from the roof.

[0074] Furthermore, in step 2, based on the actual drilled stratum interface elevation information of the soil layer revealed in the geological and hydrogeological drilling data of the area to be treated, a contour map of the top boundary elevation of the soil layer in the soil layer missing area is drawn by interpolation with a contour interval of 1 to 10 meters;

[0075] According to the concave and convex state of the soil layer top interface elevation contour line, according to the convex increasing trend or concave decreasing trend, the long axis of the potential soil layer missing area is identified based on the line connecting the maximum curvature points of each contour line.

[0076] Since the top surface of the soil layer that has not been geologically eroded is relatively gentle, while the elevation of the soil layer interface in the area affected by geological erosion tends to be lower or even absent, the top surface elevation of the soil layer can be determined based on the convexity of the elevation contour line, with a convex increasing trend or a concave decreasing trend (e.g. Figure 5 The long axis of the potential soil missing area is identified based on the line connecting the maximum curvature points of each contour line.

[0077] Furthermore, in step 3, based on the actual drilled soil layer thickness information revealed in the geological and hydrogeological drilling data of the area to be treated, a contour map of the soil layer thickness of the coal seam roof in the soil layer missing area is drawn by interpolation with a contour interval of 1 to 10 meters;

[0078] The smallest contour line in the contour map of the thickness of the coal seam roof is identified as the major axis of the potential soil layer missing area;

[0079] like Figure 5 As shown, an equidistant line is drawn between the major axis of the potential soil layer missing area obtained in step 3 and the major axis of the potential soil layer missing area obtained in step 3, and the actual major axis of the soil layer missing area is determined according to the position of the equidistant line.

[0080] It should be noted that the soil layer in the coal mining area is generally a lake-phase sedimentary stratum, similar to a calm lake surface. Under uneroded geological conditions, its thickness and elevation distribution are relatively flat and stable. When the local area is subjected to geological erosion, the stratum will become strongly thinner locally, accompanied by a significant decrease in its elevation.

[0081] Therefore, if there is sufficient geological drilling information, the scope of the skylight area can be preliminarily delineated based on the lowering of the elevation or the thinning of the thickness. However, geological drilling in general mining areas is limited, and the top surface of the soil layer is unstable due to geological weathering, wind erosion, and scouring, making it difficult to delineate it using only one indicator, elevation or thickness. Therefore, this embodiment makes full use of the relatively scarce geological drilling information and comprehensively identifies the main axis of the skylight area from the two factors of elevation and thickness, which has a higher scientific basis and accuracy.

[0082] Specifically, in step 6, during the directional drilling process according to the designed ground directional drilling main hole, rock bailing is performed every 1 m of footage.

[0083] Furthermore, in step 6, each time a rock cutting is fished out, the formation in which the drilling is located is determined by the rock cutting;

[0084] If the rock cutting is of loose rock origin, suspend directional drilling, design a vertical core hole at the corresponding ground location, and drill vertically to the bedrock layer;

[0085] If there is no soil layer during vertical core drilling to the bedrock layer, the corresponding ground position is confirmed to be the boundary of the soil missing zone, and directional drilling is continued until the main directional drilling hole is formed;

[0086] If there is a soil layer during vertical drilling and coring to the bedrock layer, the near-horizontal section of directional drilling should be readjusted according to the thickness of the soil layer and the directional drilling should be continued until the main directional drilling hole is formed;

[0087] If the rock cutting is the source of the soil layer, use the corresponding ground position as the boundary of the soil missing area on the other side and stop drilling.

[0088] During the directional main hole drilling process, the rock cuttings are continuously fished out at intervals of 1m. The rock cuttings are used to determine whether the drilled stratum is a soil layer. When the rock cuttings are found to be loose rock source, the directional drilling is suspended. With the ground position at that location as the hole position, a vertical core drilling is designed to confirm the lack of ground soil layer. The vertical core drilling is carried out to the bedrock layer. If there is no soil layer from the loose layer to the bedrock layer, it is confirmed that the location is the boundary of the soil layer missing area. Then continue the directional drilling. When the rock cuttings are found to be a soil layer source from a loose rock layer source, the location can be confirmed as the boundary of the soil layer missing area on the other side, and the drilling can be stopped. Figure 6 shown.

[0089] If the above content is expressed in the form of a process, then step 6 specifically includes the following sub-steps:

[0090] Step 61: Conduct a directional drilling along the designed ground directional drilling main hole and perform rock removal to determine whether the ground directional drilling main hole has been formed.

[0091] If it has already formed, stop drilling;

[0092] If not formed, proceed to step 62;

[0093] Step 62, determining the provenance type of the rock cutting retrieved this time;

[0094] If the rock cuttings retrieved this time are of loose rock strata provenance, proceed to step 63;

[0095] If the rock cuttings retrieved this time are of soil origin, then proceed to step 64;

[0096] Step 63: suspend directional drilling, design a vertical core drilling hole at the corresponding ground position, and perform vertical core drilling to the bedrock layer; and determine whether there is a soil layer based on the core drilling results;

[0097] If there is a soil layer, proceed to step 65;

[0098] If there is no soil layer, the ground position corresponding to the position when the directional drilling was paused is used as the upstream boundary of the soil layer missing area, and the process returns to step 61;

[0099] Step 64: Stop drilling, set the drilled hole as the main directional drilling hole, and use the ground position corresponding to the rock cutting where the soil material was retrieved as the downstream boundary of the soil missing area;

[0100] Step 65, redesigning the near-horizontal section of the ground directional drilling main hole according to the thickness of the soil layer and then returning to step 61.

[0101] Furthermore, in step 6, after the near-horizontal section of the directional drilling is readjusted according to the soil thickness, when the directional drilling is continued, rock fishing is performed every 1 m of footage;

[0102] When the rock cuttings are converted from the original soil layer to the loose rock layer, directional drilling is suspended; the ground position at that location is used as the hole location, and a vertical core drilling hole is designed to confirm the missing ground soil layer, and the core is drilled vertically to the bedrock layer;

[0103] Among them, if there is no soil layer from the loose layer to the bedrock layer, it is confirmed that this place is the boundary of the soil layer missing area, and directional drilling is continued until the directional drilling main hole is formed;

[0104] If the rock cutting is the source of the soil layer, use the corresponding ground position as the boundary of the soil missing area on the other side and stop drilling.

[0105] Furthermore, in step 7, directional branch holes are sequentially constructed from the center of the directional drill main hole to the periphery with a hole spacing of 40-60m in the near-horizontal section, and the drilling is performed using the methods of steps 5 and 6;

[0106] The range of the trap formed by connecting the starting points of the unremoved soil layer rock cutting and the starting points of the removed soil layer rock cutting within the range of each directional branch hole is the actual soil layer missing area.

[0107] After the construction of the directional main hole, the directional branch holes are designed and constructed in sequence from the center to the periphery with a hole spacing of 40 to 60 m in the near horizontal section (according to the measured directional grouting radius in the loose layer is 20 to 30 m) until the branch holes on both sides are drilled into the soil layer (that is, no loose layer rock cutting is retrieved). By sequentially connecting the starting points of the unretrieved soil layer rock cutting and the starting points of the retrieved soil layer rock cutting within the range surrounded by the outermost branch holes on both sides, the trap range is the specific range of the soil layer missing area, such as Figure 7 shown.

[0108] Furthermore, in step 8, starting from a directional branch hole where the rock cutting starting point is not fished out, cement single liquid slurry or mixed slurry is used to carry out segmented grouting at a depth of 20-50 m while continuing the directional drilling process until the grouting end standard is reached;

[0109] After the previous section of grouting is completed, multiple sections of grouting are continued at intervals of 20 to 50 m. Each section of grouting is terminated after reaching the grouting completion standard. Drilling and grouting are stopped until the directional branch hole reaches the soil layer and rock cutting.

[0110] Use the above method to traverse each directional branch hole, complete the grouting transformation, and realize the treatment of the centralized permeable skylight on the coal seam roof and the control of the water source on the roof. Figure 8 and 9 shown.

[0111] Furthermore, the mixed slurry in step 8 is cement fly ash mixed slurry or cement clay mixed slurry;

[0112] Among them, the water-solid ratio is 0.8-1.1.

[0113] Furthermore, the grouting end standard in step 8 is: after reaching the maximum grouting pressure standard, reduce the pump volume to 60L / min and maintain it for 30min;

[0114] The maximum grouting pressure P is determined using the following formula:

[0115] P=(1.5-2)*H / 100

[0116] Wherein, H represents the burial depth of the grouting section, in meters.

[0117] In order to ensure the grouting treatment effect of the skylight area, first, it is necessary to overcome the hydrostatic pressure in the stratum to ensure that the slurry can diffuse in the stratum (generally, the hydrostatic pressure is equal to the burial depth of the layer section, hydrostatic pressure = H / 100), that is, the grouting pressure P needs to be greater than the hydrostatic pressure; second, the grouting pressure cannot be too high, which will cause the slurry to diffuse to the surface and cause certain pollution to the environment. Therefore, based on the above two factors, combined with the generally measured successful experience of grouting pressure of 1.5 to 2 times the hydrostatic pressure when the radius of directional grouting in the loose layer is 20 to 30m, the end grouting pressure standard is given.

[0118] In this embodiment, a method for exploring and treating the missing area of ​​the water-proof soil layer in the roof of the coal seam is used in an underground coal mine by using the ground directional drilling and grouting transformation technology. It only relies on the construction of one directional main hole and several branch holes to achieve the precise positioning of the "line to surface" area of ​​the missing area of ​​the water-proof soil layer in the roof of the coal seam. This overcomes the many problems of the traditional use of ground vertical drilling to locate the specific range of the missing area of ​​the soil layer through "point" and "hole" type drilling and coring, such as the blindness of the arrangement of drilling holes, the large amount of drilling engineering, the large amount of coring engineering, the large amount of invalid footage, and the low efficiency. At the same time, by using a directional main hole and several branch holes to construct, the grouting transformation of the enclosed missing area of ​​the soil layer is carried out, which realizes the advanced grouting treatment of the concentrated permeable skylight during the coal seam mining process and the control of the source of water gushing and sand bursting of the loose surface aquifer and the loss of groundwater resources.

Claims

1. A method for ground exploration and treatment of local water-permeable skylights in coal seam roof, characterized in that: The following steps are involved: Step 1: Collect geological and hydrogeological drilling data of the area to be treated and preliminarily identify the area with missing soil layers as the study area; Step 2: Draw a contour map of the top elevation of the soil layer in the study area and identify a set of long axes of potential soil layer missing areas; Step 3: Draw a contour map of the thickness of the roof soil layer of the coal seam in the study area, and then identify a set of long axes of potential soil missing areas; Step 4: Obtain the long axes of two sets of potential soil layer missing areas according to Steps 2 and 3, draw an equidistant line between the long axes of the two sets of potential soil layer missing areas, and determine the actual long axes of the potential soil layer missing areas based on the equidistant line; Step 5: Design a ground directional drilling main hole upstream of the top boundary elevation of the soil layer in the soil layer coverage area of ​​the study area along the actual long axis direction of the potential soil layer missing area determined in step 4; Step 6: directional drilling is carried out according to the designed ground directional drilling main hole, and rock cuttings are continuously fished out during the directional drilling process. The provenance type of the rock cuttings is determined each time the rock cuttings are fished out. If the provenance type of the recovered cuttings changes from soil to loose rock, the layer position of the main hole of the directional drill should be adjusted and drilling should be continued while recovering the cuttings. The provenance type of the cuttings should be determined each time the cuttings are recovered. Until the main hole of ground directional drilling is formed; During the directional drilling process, if the provenance type of the rock cuttings retrieved changes from loose rock to soil, the drilling is stopped and the drill hole formed is designated as the main hole for ground directional drilling. Step 7: Design and construct directional branch holes in sequence from the center of the ground directional drill main hole to the periphery. The trap range formed by all the directional branch holes constructed in sequence is the actual soil layer missing area; Step 8: Drill directional branch holes in sequence according to the design, and carry out grouting transformation during the drilling process to achieve the treatment of centralized permeable skylights on the coal seam roof and control the source of water gushing from the roof.

2. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 1, characterized in that: In step 2, when drawing the elevation contour map of the top boundary of the soil layer in the study area, the elevation contour map is drawn with an interval of 1 to 10 m by the interpolation method, and a group of potential long axes of soil layer missing areas are identified by connecting the maximum curvature points of each contour line.

3. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 1, characterized in that: Step 3: When drawing the thickness contour map of the coal seam roof soil layer in the research area, the thickness contour map is drawn by interpolation method with a thickness contour interval of 1 to 10 m; The contour line with the smallest value in the contour map of the thickness of the coal seam roof is identified as the long axis of the potential soil layer missing area.

4. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 1, characterized in that: Step 6: During the directional drilling process according to the designed ground directional drilling main hole, the footage of each directional drilling is 1m.

5. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 4, characterized in that: Step 6 includes the following sub-steps: Step 61: Conduct a directional drilling along the designed ground directional drilling main hole and perform rock removal to determine whether the ground directional drilling main hole has been formed. If it has already formed, stop drilling; If not formed, proceed to step 62; Step 62, determining the provenance type of the rock cutting retrieved this time; If the rock cuttings retrieved this time are of loose rock strata provenance, proceed to step 63; If the rock cuttings retrieved this time are of soil origin, then proceed to step 64; Step 63: suspend directional drilling, design a vertical core drilling hole at the corresponding ground position, and perform vertical core drilling to the bedrock layer; and determine whether there is a soil layer based on the core drilling results; If there is a soil layer, proceed to step 65; If there is no soil layer, the ground position corresponding to the position when the directional drilling was paused is used as the upstream boundary of the soil layer missing area, and the process returns to step 61; Step 64: Stop drilling, set the drill hole that has been formed as the main ground directional drilling hole, and use the ground position corresponding to the rock cutting where the soil material was salvaged as the downstream boundary of the soil missing area; Step 65, redesigning the near-horizontal section of the ground directional drilling main hole according to the thickness of the soil layer and then returning to step 61.

6. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 5, characterized in that: In step 65, when redesigning the near-horizontal section of the main hole of the ground directional drilling, the near-horizontal section of the directional drilling is readjusted based on the soil layer thickness confirmed by vertical drilling coring and the middle position of the soil layer.

7. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 6, characterized in that: In step 7, directional branch holes are sequentially constructed from the center of the directional drill main hole to the periphery with a hole spacing of 40-60m in the near-horizontal section, and the methods of steps 5 and 6 are used for drilling; The range of the trap formed by connecting the starting points of the unremoved soil layer rock cutting and the starting points of the removed soil layer rock cutting within the range of each directional branch hole is the actual soil layer missing area.

8. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 7, characterized in that: In step 8, when the rock cutting starting point is not reached in a directional branch hole, cement single liquid slurry or mixed slurry is used to carry out segmented grouting at a depth of 20-50 m while continuing directional drilling until the grouting end standard is reached; After the previous grouting is completed, multiple grouting sections are continued at intervals of 20 to 50 m. Each grouting section is terminated after the grouting completion criteria are met. Drilling and grouting are stopped until the directional branch hole reaches the soil layer and rock cutting. The above method is used to traverse each directional branch hole, complete the grouting transformation, and realize the treatment of the centralized permeable skylights in the coal seam roof and the control of the water gushing source of the roof.

9. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 8, characterized in that: The mixed slurry in step 8 is cement fly ash mixed slurry or cement clay mixed slurry; Among them, the water-solid ratio is 0.8-1.

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10. The method for ground exploration and treatment of local water-permeable skylights in coal seam roof according to claim 9, characterized in that: The grouting end standard in step 8 is: after reaching the maximum grouting pressure standard, reduce the pump volume to 60L / min and maintain it for 30 minutes; The maximum grouting pressure P is determined using the following formula: P=(1.5-2)*H / 100 Wherein, H represents the burial depth of the grouting section, in meters.

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