A large-dip-angle coal seam goaf multi-layer step grouting drilling arrangement method

Abstract

The application provides a large-dip-angle coal seam goaf multi-layer step grouting drilling arrangement method, and belongs to the technical field of coal mine goaf, and comprises the following steps: S1: collecting mine basic data; S2: according to the collected mine basic data, carrying out 3DEC discrete element numerical simulation, determining the space distribution law of separation and the shape of the goaf, and determining the grouting target area; S3: arranging the surface measuring line, observing the surface subsidence value by using the total station, and calibrating the numerical simulation result; S4: based on the calibrated model result, determining the key parameters of drilling construction, carrying out multi-layer step grouting drilling design and construction, and the application designs a special drilling structure and trajectory calculation method suitable for large-dip-angle coal seam overburden structure, and the optimal path sequentially passes through the upper part of each target separation, realizes efficient penetration and grouting of a single hole to multi-layer separation, and solves the limitation that the original drilling arrangement method is difficult to be applied to large-dip-angle multi-layer goaf space grouting.

Description

Technical Field

[0001] This invention belongs to the technical field of coal mine goaf, specifically relating to a method for arranging multi-level stepped grouting boreholes in a steeply inclined coal seam goaf. Background Technology

[0002] In the coal mining industry, especially in the mining of steeply inclined coal seams, surface subsidence control is a key technical challenge to ensure the ecological safety of the mining area and the stability of surface facilities. Currently, the commonly used subsidence reduction technologies in the industry mainly include goaf filling and overburden separation grouting. Gangue grouting boreholes typically employ a combination of vertical shafts and horizontal directional shafts to fill the goaf. Based on a clear understanding of the grouting layer, methods for arranging filling boreholes, such as "cluster boreholes" and "feather boreholes," have been proposed. These construction methods are generally suitable for grouting filling of coal gangue in horizontal coal seam goafs. Grouting is achieved by completing drilling, cementing, and production well processes.

[0003] Although existing overburden separation grouting technology has achieved some results, it has revealed significant limitations when dealing with the special geological and mining conditions of steeply inclined coal seams. Overburden migration in steeply inclined coal seam mining is asymmetrical, and the location of the separation space often leans towards the area below the working face. Blindly selecting borehole layout can easily lead to problems such as difficulty in grout injection and borehole blockage.

[0004] Current technologies typically separate overburden separation grouting from goaf grouting, using a single borehole for each purpose. This results in a limited range of borehole trajectories and makes it difficult to achieve multi-level, tiered, spatially coordinated grouting in steeply inclined coal seams. Furthermore, existing technologies do not adequately consider the grout flow characteristics under steeply inclined conditions. At such conditions, grout flow in separations and fractures is significantly influenced by gravity and exhibits a clear directionality. How to achieve multi-level, tiered grouting in steeply inclined coal seams using a single borehole remains a research gap. Moreover, how to utilize the development patterns of steeply inclined coal seams and geological conditions such as dip angle to facilitate grout diffusion and thus reduce construction costs is a pressing issue that needs to be addressed on-site. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam, comprising the following steps: S1: Collect basic mine data; S2: Based on the collected basic mine data, conduct 3DEC discrete element numerical simulation to determine the spatial distribution law of delamination and the morphology of goaf, and determine the grouting target area; S3: Set up surface survey lines, use a total station to observe surface subsidence values, and calibrate numerical simulation results; S4: Based on the calibrated model results, determine the key parameters for borehole construction and carry out the design and construction of multi-level stepped grouting boreholes.

[0006] Furthermore, the basic mine data in step S1 includes the geological overview of the mining area, engineering background information, overlying strata and coal seam occurrence characteristics, working face mining parameters, and coal and rock mass mechanical parameters.

[0007] Furthermore, step S2 involves conducting 3DEC discrete element numerical simulations based on the collected mine basic data, specifically including the following: S201: Through numerical simulation, calculate the location of the maximum surface subsidence in the dip direction and the location and number of layers of the separation space after the mining face has been fully mined; S202: Determine the timing of grouting; S203: Establishment xoy Cartesian coordinate system; S204: Pass xoy A rectangular coordinate system can be used to obtain numerical simulation results.

[0008] Furthermore, in step S4, multi-level stepped grouting drilling is carried out to generate a first vertical well, a second inclined well, and a third directional well. The first vertical well and the second directional well are both located in the bending and subsidence zone of the rock strata, while the third directional well is drilled in the overlying delamination zone and the water-conducting fracture zone.

[0009] The advantages of this invention are as follows: This invention provides a method for arranging boreholes for multi-level grouting in steeply inclined coal seams, which solves the limitation of the original borehole arrangement method being difficult to apply to spatial grouting in steeply inclined multi-level goaf areas. It designs a special borehole structure and trajectory calculation method adapted to the overburden structure of steeply inclined coal seams, and sequentially passes through the upper part of each target delamination layer with the optimal path, realizing efficient penetration and grouting of multi-level delamination layers with a single borehole. In addition, this invention realizes the correlation between the grouting process and the working face advance. By establishing a coordinate system to correlate the borehole coordinates with the working face advance, it ensures that the grouting target area can be aligned with the most effective delamination development area at each grouting stage.

[0010] Simultaneously, the grout diffusion path was optimized to improve filling efficiency. By shifting the grouting point to the upper part of the delamination and using directional well trajectory control, the grout is actively guided to preferentially fill the upper delamination under gravity, and then naturally seep down to fill the lower fracture zone and collapse zone, achieving "one hole, multiple layers" tiered grouting. This significantly improves the utilization rate of grouting materials and the overall settlement reduction effect.

[0011] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0013] Figure 2 This is a schematic diagram of the drilling structure of the present invention.

[0014] Figure 3 This is a schematic diagram of the drilling layout of the present invention. Detailed Implementation

[0015] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the specific implementation methods, structural features and effects of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "aligned", "overlapping", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0018] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0019] Example 1

[0020] This embodiment provides, for example Figures 1-3 The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam, as shown, includes the following steps: S1: Collect basic mine data, which includes geological overview of the mining area, engineering background information, overlying strata and coal seam occurrence characteristics, working face mining parameters, coal and rock mass mechanical parameters, etc. S2: Based on the collected basic mine data, conduct 3DEC discrete element numerical simulation to determine the spatial distribution law of delamination and the morphology of goaf, and determine the grouting target area; S3: Set up surface survey lines, use a total station to observe surface subsidence values, and calibrate numerical simulation results. Based on the analysis of the post-mining overlying rock strata structure, the implementation details of the surface subsidence monitoring scheme are proposed. Two survey lines are set up on the surface. The strike survey line is set up along the centerline of the working face advance direction. The spacing between measuring points is generally 30m. The survey line needs to extend 30m beyond the working face opening boundary and 30m beyond the working face stop mining line boundary. Dip survey lines are laid out on the ground along the dip direction of the working face. The length of the survey lines is greater than the dip length of the working face. The survey lines need to extend 60m beyond the lower boundary of the working face and 30m beyond the upper boundary of the working face. The 3DEC numerical simulation results are calibrated based on the field measurement data. S4: Based on the calibrated model results, determine the key parameters for borehole construction and carry out the design and construction of multi-level stepped grouting boreholes.

[0021] Furthermore, step S2 involves conducting 3DEC discrete element numerical simulations based on the collected mine basic data, specifically including the following: S201: Through numerical simulation, the location of the maximum surface subsidence and the spatial distribution of delamination in the dip direction after the longwall face has been fully mined, as well as the number of layers, are calculated to determine the spatial distribution law of multiple delamination layers in the overlying strata of the steeply dipping coal seam and the morphological characteristics of the water-conducting fracture zone in the goaf. S202: Determine the timing of grouting. The initial grouting should be carried out when the working face has advanced one square meter, that is, when the working face has advanced to a position one working face length away from the working cut, taking into account the grout diffusion range. w The subsequent grouting will be carried out when the working face advances by 2 meters. w Location; S203: Establishment xoy Cartesian coordinate system, origin o Located on the surface, x The axial direction points towards the dip direction of the large-angle working face. x The axis is located at the ground surface position corresponding to the dip line of the working face at each grouting location. y The axial direction is along the vertical line, passing through the midpoint of the inclined working face at the large angle to be grouted. Based on the above process, it can be determined that... xoy The specific location of the rectangular coordinate system at each grouting timing; S204: Pass xoy A rectangular coordinate system can be used to obtain numerical simulation results, which mainly include: obtaining the coordinates of the maximum subsidence point on the ground surface (…). x , y max ),Right now y max Position correspondence x Coordinates were used to obtain the stratigraphic position and location information of the layer. The distances of the stratigraphic positions from the working surface, from closest to farthest, were: i Layer separation,i The values ​​are 1, 2, ... n ,in, n Refers to shared n Layer separation. By xoy The coordinates of the center points of each layer can be obtained using a rectangular coordinate system. x i , y i ),in i The values ​​are 1, 2, ... n The development lengths of each abscission layer are as follows: l i ,in i The values ​​are 1, 2, ... n .

[0022] Furthermore, in step S4, multi-level tiered grouting drilling is carried out to generate a first-section vertical shaft, a second-section inclined shaft, and a third-section directional shaft. The grouting drilling location is at the maximum subsidence position on the dip profile of the surface subsidence basin, and the drilling structure is as follows: Figure 2 As shown, the borehole arrangement is as follows Figure 3 As shown; The first vertical shaft and the second directional shaft were both located within the bending and subsidence zone of the rock strata, while the third directional shaft was drilled within the overlying delamination zone and the water-conducting fracture zone. The first vertical shaft drilling begins, and the borehole is drilled to a distance above the separation point. h At a distance of 30-50m, the spacing h This refers to the vertical distance between the delamination layer and the target rock layer being drilled, in order to reduce the impact of delamination deformation on the vertical wellbore. The borehole diameter is 200cm, and cementing is carried out after drilling to the designated position; In the second phase of drilling, the drilling position is from the end of the vertical shaft hole to the position of the uppermost separation hole. The development height and dip length of the highest separation can be obtained through numerical simulation results. Define the grouting offset point, which is the location where the borehole is intended to traverse the separation spaces of each layer in a steeply dipping coal seam. Considering the downward influence of grout gravity flow, the borehole location is situated in the upper-middle part of the separation layer. Offset coefficient. k To measure the degree to which the borehole position deviates from the center point of the layer in the upward direction along the groove, a value of 0 to 1 is generally used; The inclined well has been drilled to the position of the uppermost separation borehole. x kn , y kn It can be calculated using the following formula: ( x kn , y kn )= In the formula, k nThis is the offset coefficient between the location of the topmost separation borehole and the center point of the separation layer. l n The length of the uppermost delamination development; θ The angle of dip of the coal seam; x n , y n () represents the coordinates of the center point of the uppermost layer, in meters.

[0023] The inclined shaft is constructed in the direction of the roadway on the working face, perpendicular to the working face's advancing direction, and arranged along the dip of the working face; that is, the azimuth angle of the inclined shaft is... β +180°, β The azimuth angle of the coal seam dip. A perforated casing is used for drilling inclined holes; The three-stage directional well drilling process begins at the uppermost separation borehole and extends into the goaf caving zone. The casing uses a perforated design, traversing multiple separation spaces and fracture zones within the steeply inclined coal seam. Grouting fluid can flow into the separation spaces within the grouting boreholes, with priority given to injecting into the upper multiple separation spaces to ensure effective grouting and subsidence reduction. The directional wells are vertical, passing sequentially from farthest to near the upper grouting offset points in each separation space. like Figure 3 As shown, directional wells and y Axis angle α The results can be obtained through numerical simulation. First, obtain the coordinates of the center point of each delamination, and then select the offset coefficient of each borehole's position from the centerline of the working face to the delamination. k i ; The directional well traverses the upper region of each delamination space. The sum of the squares of the distances from the directional well to each grouting offset point is minimized. The slope of the directional well in the rectangular coordinate system is... a It can be calculated using the following formula: ,in, , , , x i , y i This refers to the coordinates of the center points of each layer. Furthermore, directional wells and y Angle of the axis δ It can be calculated using the following formula: ; The azimuth angle of the directional well is β +180°; The grouting section is a three-section directional drilling project to construct production holes. The holes are filled with perforated pipes. After the three sections of drilling are completed, multi-level tiered grouting of steeply inclined coal seams can be achieved. The grout in the directional borehole can flow into the fracture zone and caving zone of the working face along the overlying rock fissures, and the grout fills the goaf space in the lower roadway under its own weight.

[0024] This invention not only proposes a "one-hole-multi-layer" stepped grouting borehole structure, which significantly improves grouting efficiency, but also, through the innovative design of a three-section borehole structure consisting of "vertical borehole + inclined shaft + directional shaft," enables a single borehole to sequentially penetrate multiple layers of dislocation space from top to bottom with an optimized spatial trajectory, and ultimately extend to the goaf. This design achieves coordinated grouting of multiple layers of dislocation and the goaf, overcoming the shortcomings of traditional vertical borehole grouting with its single grouting layer and incomplete coverage, and greatly improving the utilization rate of a single borehole and the overall grouting efficiency.

[0025] Meanwhile, the flow path of the grout in the goaf of steeply inclined coal seams was optimized, significantly improving material utilization and filling effect. By setting "grouting offset points" and designing the directional well trajectory to pass through the upper part of each delamination layer, the flow characteristics of the grout under gravity under steeply inclined conditions were fully utilized, avoiding disordered diffusion and local siltation of the grout, so that the grouting material is used most effectively, which will significantly improve the subsidence reduction effect.

[0026] Furthermore, this invention possesses significant technical and economic advantages and engineering applicability. By employing precise borehole layout and efficient grouting, it reduces the number of unnecessary boreholes and grout consumption, thereby lowering engineering costs. Its core lies in a profound understanding of the laws governing overburden movement, making it particularly suitable for surface subsidence control in complex mining conditions such as steeply dipped coal seams. It has excellent potential for widespread application and industrial application prospects.

[0027] In summary, this invention provides a method for arranging multi-level cascade grouting boreholes in a goaf of a steeply inclined coal seam. The main methods include: collecting geological information and mining parameters of the mining area, conducting 3DEC discrete element numerical simulation experiments, determining the distribution characteristics of multi-level separation layers and the morphological characteristics of water-conducting fracture zones in the steeply inclined coal seam, and using surface subsidence data to calibrate the numerical simulation results. Based on this, the coordinates of the layout of the multi-level grouting boreholes were determined according to the calibrated overburden migration results. A three-section drilling structure was proposed: first, a vertical shaft was drilled to the stable rock layer above the separation layer; second, an inclined shaft was drilled in the direction of the trench on the working face to accurately drill to the preset grouting offset point of the uppermost separation layer; and third, a directional shaft was drilled to pass through the upper part of each separation space in sequence with the optimal path and finally enter the goaf collapse zone. The grouting offset point and directional well trajectory are precisely calculated using an established coordinate system and mathematical model. This invention employs a top-down, stepped grouting method, prioritizing the filling of the upper overburden separation layer before diffusing downwards into fracture zones and collapse zones. This method overcomes the limitations of traditional borehole layout methods, which are unsuitable for grouting in multi-level, steeply inclined goaf areas. It achieves efficient and precise filling of overburden separation and goaf spaces in steeply inclined coal seams after mining, significantly improving grouting settlement reduction and material utilization.

[0028] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam, characterized in that: Includes the following steps: S1: Collect basic mine data; S2: Based on the collected basic mine data, conduct 3DEC discrete element numerical simulation to determine the spatial distribution law of delamination and the morphology of goaf, and determine the grouting target area; S3: Set up surface survey lines, use a total station to observe surface subsidence values, and calibrate numerical simulation results; S4: Based on the calibrated model results, determine the key parameters for borehole construction and carry out the design and construction of multi-level stepped grouting boreholes.

2. The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam as described in claim 1, characterized in that: The basic mine data in step S1 includes the geological overview of the mining area, engineering background information, characteristics of overlying strata and coal seams, mining parameters of the working face, and mechanical parameters of coal and rock mass.

3. The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam as described in claim 1, characterized in that: Step S2, which involves conducting 3DEC discrete element numerical simulations based on the collected mine basic data, specifically includes the following: S201: Through numerical simulation, calculate the location of the maximum surface subsidence in the dip direction and the location and number of layers of the separation space after the mining face has been fully mined; S202: Determine the timing of grouting; S203: Establishment xoy Cartesian coordinate system; details of the coordinate system layout are as follows, with the origin at... o Located on the surface, x The axial direction points towards the dip direction of the large-angle working face. x The axis is located at the ground surface position corresponding to the dip line of the working face at each grouting location. y The axial direction is along the vertical line, passing through the midpoint of the inclined working face at the large angle of the proposed grouting; S204: Pass xoy A rectangular coordinate system can be used to obtain numerical simulation results.

4. The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam as described in claim 1, characterized in that: In step S4, multi-level stepped grouting drilling is carried out to generate a first vertical shaft, a second inclined shaft, and a third directional shaft. Both the first vertical shaft and the second directional shaft were located within the bent and subsided zone of the rock strata, while the third directional shaft was drilled within the overlying delamination zone and the water-conducting fracture zone.

5. The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam as described in claim 4, characterized in that: The first vertical shaft drilling begins, and the borehole is drilled to a distance above the separation point. h At a distance of 30~50m, the spacing h The vertical distance between the delamination layer and the target rock layer is set to reduce the impact of delamination deformation on the vertical wellbore. The borehole diameter is 200cm, and cement cementing is carried out after drilling to the designated position. In the second phase of drilling, the drilling position is from the end of the vertical shaft hole to the position of the uppermost separation hole. The development height and dip length of the highest separation can be obtained through numerical simulation results. The three-stage directional well drilling process begins at the uppermost separation borehole and proceeds into the goaf caving zone. The casing uses perforated tubing and passes through multiple separation spaces and fracture zones in the steeply inclined coal seam. The directional well is a vertical well, and it passes through the grouting offset points in the upper part of each separation space from far to near.

6. The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam as described in claim 5, characterized in that: The second phase of the inclined shaft drilling has reached the position of the uppermost separation borehole. x kn , y kn It can be calculated using the following formula: （ x kn ， y kn ）= 。 7. The method for arranging multi-level stepped grouting boreholes in a goaf of a steeply inclined coal seam as described in claim 5, characterized in that: Directional wells and y Axis angle α The results can be obtained through numerical simulation. First, obtain the coordinates of the center point of each delamination, and then select the offset coefficient of each borehole's position from the centerline of the working face to the delamination. k i ; Slope of a directional well in a rectangular coordinate system a It can be calculated using the following formula: , Directional wells and y Angle of the axis δ It can be calculated using the following formula: .

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