Method for constructing artificial pillar by cutting groove through controlled blasting in large goaf

Abstract

A method for constructing artificial pillars in large goaf areas using controlled blasting and slotting includes the following steps: S1. Based on three-dimensional laser scanning and ground pressure monitoring data, a three-dimensional digital model is generated using data processing software to identify potential high ground pressure instability risk areas and determine the location, shape, and size parameters of the artificial pillars; S2. Main blasting holes, cutting holes, and auxiliary holes are arranged in the corresponding area of ​​the goaf roof to form a controlled blasting slotting design; S3. A reinforcing cage is installed at the bottom of the goaf, and the pillar mold is installed and assembled; S4. Using a micro-delay detonation method, the cutting holes, auxiliary holes, and main blasting holes are detonated sequentially, causing the roof rock to directionally collapse and fall into the reinforcing cage directly below, filling and compacting to form a composite artificial pillar; then, the outer mold is removed, completing the construction of the artificial pillar. This invention achieves an integrated and coordinated process of blasting pressure relief, crushed stone utilization, and pillar construction, with advantages of simplified procedures, minimal disturbance, and high stability.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology, specifically to a method for constructing artificial pillars by controlled blasting and slotting in large goaf areas. Background Technology

[0002] In underground mining operations, the safety management of extra-thick and hard roofs is the core factor determining the stability of goaf areas. Such roof rock masses have high mechanical strength and strong integrity, and accumulate a large amount of deformation energy over a long period of time. If the stress cannot be effectively released, it is easy to cause sudden collapse accidents. At the same time, artificial pillars need to be constructed to support the roof. The coordinated handling of the two is directly related to the safety and production efficiency of the mine.

[0003] Currently, there are significant shortcomings in the treatment of extra-thick roofs in mining areas: First, decompression and pillar construction are carried out in a "disjointed" manner, resulting in low efficiency and high risk. Most mining areas first decompress the roof separately through methods such as shallow-hole blasting and hydraulic fracturing. However, these methods can only act on the shallow layer of the roof and are difficult to completely release the stress accumulated in the deep layers, resulting in limited decompression effects. Moreover, after decompression, additional aggregate transportation, casting, or separate blasting of pillars is required, with long intervals between processes. During this period, the roof is in a suspended state for a long time, and the risk of collapse continues to accumulate. Second, the stability of the pillars is poorly adapted to the roof. Conventional pillars either rely on external aggregate casting, which is costly and does not bond tightly with the original roof rock mass, resulting in insufficient support strength; or they are formed by separate blasting, but the blasting energy is difficult to control, which can easily lead to irregular pillar outlines and dense internal fissures. This not only weakens its own bearing capacity but also aggravates the damage to the roof rock mass, creating new safety hazards. In addition, existing solutions have always failed to meet the dual requirements of "efficient pressure relief" and "stable column construction", often resulting in one being neglected and the other being unsuitable for the complex working conditions of extra-thick roof slabs. Summary of the Invention

[0004] To overcome the above technical problems, the present invention aims to provide a method for constructing artificial pillars by controlled blasting in large goaf areas. This method has the ability to efficiently, accurately, and with low disturbance form the required groove structure for artificial pillars under conditions of extra-thick roof. Furthermore, the controlled blasting method causes minimal damage to the surrounding pillars and rock, ensuring long-term stability.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for constructing artificial pillars by controlled blasting and slotting in large goaf areas includes the following steps; S1. Identification of key high-pressure areas and design of artificial pillars: Based on three-dimensional laser scanning and ground pressure monitoring data, a three-dimensional digital model is generated through data processing software to identify potential instability risk areas under high ground pressure and determine the location, shape, and size parameters of artificial pillars. S2. Design and construction of controlled blasting trenches in key areas: According to the design parameters of the pillar mold 3, the main blasting hole 5, the cutting hole 6 and the auxiliary hole 7 are arranged in the corresponding area of ​​the top plate 1 of the goaf, and a controlled blasting cutting groove design matching the artificial pillar is formed. S3. Design and construction of the reinforcing cage: A reinforcing steel cage 4 is installed at the position corresponding to the pillar mold 3 at the bottom of the goaf, and the installation and assembly of the pillar mold 3 are completed. S4. Implement controlled blasting and slotting, and construct artificial pillars: Using a micro-differential detonation method, the cutting hole 6, auxiliary hole 7 and main blasting hole 5 are detonated in sequence, causing the roof rock to collapse in a directional manner and fall into the steel cage 4 directly below. Under the constraint of the steel cage 4, it is filled and compacted to form a composite artificial pillar. After the artificial pillar is formed and stabilized, the outer mold is removed to complete the construction of the artificial pillar, wherein the artificial pillar is directly formed by blasted rock under constrained conditions.

[0006] In S1, the three-dimensional digital model includes information on rock mass fissures, faults, and stress concentration zones; The geometric characteristics of the curvature and subsidence of the goaf roof 1 are calculated based on the three-dimensional digital model. The precise location, shape and size of the artificial pillars are planned in areas that are flat, have the largest span or show obvious signs of subsidence, so as to ensure that the arrangement of the pillars matches the stress distribution of the goaf roof 1.

[0007] Specifically, point cloud data of goaf 13 and goaf roof 1 are obtained by 3D laser scanning. After data cleaning, registration and splicing and triangular mesh modeling, a 3D mesh model is formed. Combined with ground pressure monitoring data, the roof subsidence and its distribution characteristics are calculated to identify stress concentration areas and determine the location of the pillars.

[0008] In S2, Based on the data of the goaf roof 1 detected by the 3D laser scanner, a geological drilling rig was used to carry out pretreatment work on the goaf roof 1 and its surrounding area, drilling the main blasting hole 5, cutting hole 6, and auxiliary hole 7. Cutting holes 6 are arranged in the center of the working face. Auxiliary holes 7 are arranged between cutting holes 6 and main blasting holes 5. Main blasting holes 5 are arranged in the outermost ring of the working face. The hole diameter is determined in combination with the required explosive rolls and the decoupling coefficient. A slag bucket is set at each hole opening to ensure the hole formation rate.

[0009] The main blast hole 5, the cutting hole 6 and the auxiliary hole 7 all use emulsion explosives, and the charging method is decoupled charging. A combination of radial and axial decoupling is used to select a smaller diameter propellant cartridge and place it into a larger borehole, so that an annular air gap is formed between the outer wall of the propellant cartridge and the borehole; a centering device is used to ensure the uniformity of this gap; Secondly, axial decoupling is achieved by dividing the explosive into several independent charge segments along the borehole axis and setting an air gap of a certain length 12 between each segment. Charges are loaded at the front of the cutting hole 6, at the middle of the auxiliary hole 7, and at the bottom of the main blasting hole 5; the remaining parts between each blasting hole are separated by backfill material 8 or air gap 12 to form a blasting groove structure for inducing directional collapse of the roof.

[0010] Among them, at the corresponding main blast hole 5, backfill material 8, air gap 12, explosive column 11 and air gap 12 are set from top to bottom; a detonating detonator 9 is installed through the backfill material 8, the detonating detonator 9 is connected to the detonating bomb 10, and the detonating bomb 10 is located at the air gap 12 below. At the corresponding cutting hole 6, backfill material 8, explosive column 11, backfill material 8 and air gap 12 are arranged sequentially from top to bottom. Detonating detonator 9 is installed through backfill material 8. Detonating detonator 9 is connected to detonating bomb 10. Detonating bomb 10 is located at air gap 12. At the corresponding auxiliary hole 7, backfill material 8, explosive charge 11, and air gap 12 are arranged sequentially from top to bottom. Detonating detonator 9 is connected to detonating bomb 10, which is located at air gap 12.

[0011] In S3, a pretreatment is carried out at a selected location on the roof of the goaf 1 to form a groove 14. The steel cage 4 is placed into the groove 14 to restrain the collapsed rock and promote its shaping and compaction. A pillar mold 3 is set up around the steel cage 4.

[0012] The steel cage in S3 is shaped and sized to match the designed artificial mine pillar. Its function is to constrain the falling rocks, concentrate them in a space of a predetermined shape, and form a composite support structure with the rocks.

[0013] In S3, the steel cage is assembled on site from precast steel components by welding or fastening.

[0014] The release and transfer of ground pressure in S4 and the construction of artificial rock pillars are achieved synchronously within the same natural process. The roof rock releases energy through controlled blasting and collapse, while the collapsed body itself becomes a supporting structure.

[0015] The composite artificial rock pillar formed in S4 is an integral load-bearing structure composed of a steel cage and compacted, collapsed rock constrained within it.

[0016] Specifically: Select the cutting hole 6 in the middle position as the detonation hole; After the detonation of the detonation hole 6, the auxiliary hole 7 and the main detonation hole are selected with a time delay, and the auxiliary hole detonates before the main detonation hole 5. Venting holes 15 are evenly spaced on the pillar mold 3 to achieve the gradual collapse of the rock mass from the center outward.

[0017] The beneficial effects of this invention are: This invention utilizes the crushed rock generated by controlled blasting as coarse aggregate for mine pillars in situ, realizing the resource utilization of blasting waste rock during the roof pressure relief process. This method has the advantages of simple structure, convenient construction and low cost, effectively solving the problem of blasting pressure relief waste rock disposal and significantly improving the safety and stability of the goaf.

[0018] This invention, through its design for blasting the roof of a goaf, effectively overcomes the aforementioned shortcomings: a single controlled blast achieves a dual effect—precisely fracturing the roof rock to form a pressure relief zone, thoroughly absorbing and releasing the deformation energy accumulated in the original rock mass, thus resolving stress concentration issues; simultaneously, the blasted debris falls directly into a pre-designed mold as aggregate for pillar filling, eliminating the need for separate pressure relief and pillar construction processes, significantly shortening the construction cycle. Furthermore, the pillars, composed of the original roof rock, bond more tightly to the roof, significantly improving support stability, fundamentally solving the problems of incomplete pressure relief, low pillar construction efficiency, and poor stability inherent in existing solutions. Attached Figure Description

[0019] Figure 1 A flowchart for constructing artificial pillars.

[0020] Figure 2 This is a schematic diagram of an artificial pillar.

[0021] Figure 3 A top view of the layout of the pillar mold.

[0022] Figure 4 This is a schematic diagram of the detonation sequence for the blast holes.

[0023] Figure 5 This is a schematic diagram of an artificial pillar.

[0024] Figure 6 This is a schematic diagram of an artificial pillar mold.

[0025] Figure 7 This is a schematic diagram of the pillar mold 3.

[0026] In the diagram: 1. Roof; 2. Artificial pillar; 3. Pillar mold; 4. Reinforcing cage; 5. Main blast hole; 6. Cutting hole; 7. Auxiliary hole; 8. Backfill material; 9. Detonating detonator; 10. Detonating bomb; 11. Explosive column; 12. Air gap; 13. Goaf; 14. Groove; 15. Vent hole. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] like Figure 1 As shown, a method for constructing artificial pillars by controlled blasting and slotting in large goaf areas is implemented through the following steps: S1. Identification of key high-pressure areas and design of artificial pillars: (1) Selection of the location of the ore pillar: a): Stability analysis of the roof slab: First, a mining-specific 3D laser scanner was used to collect point cloud data of goaf 13 and roof 1 to ensure that the monitoring stations were reasonable, the density was uniform and there were no blind spots, and to focus on covering flat areas, large-span areas and suspected subsidence areas. The original data was then cleaned to remove noise and redundant points, and the data from multiple stations were registered and stitched together to be unified into the mine geological coordinate system to obtain a high-precision roof point cloud dataset. Secondly, the point cloud was transformed into a three-dimensional mesh model using the triangular mesh modeling method, accurately reproducing the undulating shape of the roof, and the coordinates and displacement data of the ground pressure monitoring points were linked to the model. The accuracy of the model was verified by comparing geological drawings with measured cross sections, ensuring that the deviation was ≤0.1m, laying the foundation for subsequent calculations.

[0029] The calculation of subsidence is divided into two categories: single-point absolute subsidence and regional relative subsidence. Single-point subsidence is obtained by the difference between the initial and current vertical coordinates of the monitoring point. A positive value indicates subsidence, and the subsidence rate can be calculated. Regional subsidence is calculated by extracting the coordinates of the grid nodes, calculating the average subsidence and standard deviation, in order to assess the overall degree and non-uniformity. The larger the standard deviation of subsidence, the more likely it is to be a stress concentration area. Finally, the core area of ​​the sinking is visually marked using color rendering.

[0030] The curvature calculation uses average curvature as the evaluation index. The principal curvatures k1 and k2 of the grid nodes are extracted using specialized software, and the average curvature is calculated according to the formula H=(k1+k2) / 2. A positive value indicates that the roof 1 is concave; the larger the value, the more significant the curvature, reflecting stress concentration and instability risk. Finally, a curvature cloud map is generated, and the mean and maximum values ​​of the target area are extracted to complete the quantitative analysis. Based on the three-dimensional digital model, the geometric characteristics of the roof curvature and subsidence are calculated. Areas that are flat, have the largest span, or show obvious signs of subsidence are selected to plan the precise location, shape, and size of artificial pillars. b): Avoiding unfavorable geological bodies: The 3D laser scanning model is compared and analyzed with existing geological exploration data (such as faults, fracture zones, and weak interlayers). For example... Figure 2 When determining the final location of the pillar, we actively avoid these adverse geological structures to ensure that the pillar mold 3 is situated on a complete and solid rock layer, thereby improving its foundation bearing capacity.

[0031] S2. Design and construction of controlled blasting trenches in key areas: (2) Drilling in goaf like Figure 4 As shown, based on the data of the goaf roof 1 detected by the 3D laser scanner, a geological drilling rig was used to carry out pretreatment work on the goaf roof 1 and its surrounding area, drilling the main blasting hole 5, cutting hole 6, and auxiliary hole 7. A cutting hole 6 is arranged at the center of the working face, and an auxiliary hole 7 is arranged between the cutting hole 6 and the main blasting hole 5. The main blasting hole 5 is arranged on the outermost ring of the working face. The hole diameter is determined in combination with the required explosive cartridge and the decoupling coefficient, and a slag bucket is set at each hole opening to ensure the hole formation rate.

[0032] (3) Loading method like Figure 4 , Figure 5 As shown, the main blast hole 5, the cutting hole 6, and the auxiliary hole 7 all use emulsion explosives, and the charging method is decoupled charging.

[0033] a) High-precision decoupled charge: This is a key technology for controlling charge size. A combination of radial and axial decoupling is used, selecting a smaller diameter charge cartridge and placing it into a larger borehole, creating an annular air gap between the cartridge's outer wall and the borehole. To ensure the uniformity of this gap, a centering device, such as a plastic support, is used to prevent the charge cartridge from sticking to the borehole wall under gravity, thus avoiding excessive pulverization of the borehole wall due to localized coupled blasting.

[0034] Secondly, axial decoupling is achieved by dividing the explosive into several independent charge segments along the borehole axis and setting air gaps of a certain length 12 between each segment. This combination of radial and axial decoupling ensures the formation of a uniform and interconnected fracture network in the rock strata, thereby achieving uniform rock fragmentation.

[0035] b): Radial decoupling: Smaller diameter explosive charges (e.g., Φ25 mm or Φ32 mm) are loaded into larger boreholes (e.g., Φ45 mm) to maintain the decoupling coefficient (borehole diameter / charge charge diameter) between 1.4 and 2.0. The fundamental purpose is to utilize the buffering and regulating effect of air gaps to transform the explosive energy from instantaneous, concentrated impact damage into continuous, uniform fracture propagation. This suppresses ineffective energy consumption while maximizing the development of tensile fractures in the target rock layer, thereby achieving the engineering goal of roof pressure relief with the highest energy utilization efficiency.

[0036] c) Axial decoupling: Charges are placed at the front of the cutting hole 6, in the middle of the auxiliary hole 7, and at the bottom of the main blast hole 5. The remaining portions between each hole are separated by backfill material 8 or air gaps 12. The front charge creates the initial fracture core, the middle charge evenly expands the fracture in all directions, and the bottom charge forms a cut surface at the bottom of the critical layer. The three work together to construct a three-dimensional stress-relief fracture network within the critical layer that has both lateral continuity and longitudinal cutting. By precisely placing the explosive charge in the target section and filling the non-target sections with air gaps 12 or backfill material 8, precise energy transfer can be achieved, avoiding ineffective dissipation of explosive energy in non-target rock layers, and maximizing the protection of the integrity of the rock mass to be preserved.

[0037] d): Selection of low-velocity explosives: Prioritize the use of low-velocity, low-density specialized rock emulsion explosives or ammonium nitrate fuel oil explosives. These explosives produce a gentler pressure pulse with a longer duration, which is more effective in causing rock to fracture and form a regular network of cracks, rather than creating a pulverized zone.

[0038] e): Optimal resistance line design: Ensure that the ratio (a / W) of the borehole spacing (a) to the minimum resistance line (W) is between 1.1 and 1.3.

[0039] At the corresponding main blast hole 5, backfill material 8, air gap 12, explosive charge 11 and air gap 12 are set from top to bottom; a detonating detonator 9 is installed through the backfill material 8, and the detonating detonator 9 is connected to the detonating bomb 10, which is located at the air gap 12 below. At the corresponding cutting hole 6, backfill material 8, explosive column 11, backfill material 8 and air gap 12 are arranged sequentially from top to bottom. Detonating detonator 9 is installed through backfill material 8. Detonating detonator 9 is connected to detonating bomb 10. Detonating bomb 10 is located at air gap 12. At the corresponding auxiliary hole 7, backfill material 8, explosive charge 11, and air gap 12 are arranged sequentially from top to bottom. Detonating detonator 9 is connected to detonating bomb 10, which is located at air gap 12.

[0040] S3. Design and construction of the reinforcing cage: (4) Layout of pillar molds like Figure 3 , 6 As shown, a pretreatment is performed at a selected location on the top plate 1 to form a groove 14. The reinforcing cage 4 is then placed into the groove 14 to apply confining pressure and to shape the blasted rocks so that they do not fall loosely. Furthermore, a pillar mold 3 is arranged around the reinforcing cage 4.

[0041] like Figure 7 As shown, vent holes 15 are provided at equal intervals on the pillar mold 3.

[0042] S4. Implement controlled blasting and slotting, and construct artificial pillars: (5) Controlled blasting a) Select the detonation hole: Select the cutting hole 6 in the middle position as the detonation hole; b): Detonation sequence: Select micro-delay blasting, with the central detonation spreading outwards. After detonation hole 6, if the inner tube of auxiliary hole 7 is delayed by 25ms and the main detonation hole is delayed by 50ms, the auxiliary hole will detonate 25ms ahead of the main detonation hole, which can effectively improve the degree of fragmentation of the roof in the void area.

[0043] The specific delay can be adjusted according to the actual situation of the mine and the geological conditions of the rock strata in the goaf.

[0044] After the pillar has stabilized, the outer pillar mold 3 can be removed according to the site conditions for use in the next pillar. Controlled blasting is used to cut grooves, breaking up the collapsed rock and filling it with a reinforcing cage 4, thus constructing a reinforced cage-rock composite reinforced artificial pillar capable of supporting the overlying strata of the goaf. This method not only effectively releases and transfers the high ground pressure of the overlying strata in the goaf, but also fully utilizes the rock's fracturing ability and the restraining power of the reinforcing cage, achieving a dual effect of "pressure relief" and "support" in dealing with large goafs.

[0045] Example: Taking a certain mine as an example, the rock type is medium-hard rock (limestone or sandstone). After selecting the location, drilling is carried out, with 1 cutting hole (Φ50 mm), 8 auxiliary holes (Φ30 mm), and 16 main blasting holes (Φ30 mm). To ensure blasting effectiveness and prevent flyrock, all blasting holes retain a plugging length of no less than 1.5 m. The pillar size is 4m × 4m × 3m, and the rock loosening coefficient is taken as K = 1.5. In the formula, V 柱 V is the volume of the artificial pillar mold. 顶 V is the volume of top plate rock required to fill the mold. 实 To fill the mold and the volume of rock on the top plate after blasting.

[0046] The required L is obtained by reverse calculation using the above formula. 钻 ≥2m, to fill the space of the mold and the top plate after the explosion, take L. 钻 =5.3m 1. Calculation of explosive charge amount for each borehole (1) Cutting hole Function: Creates the initial free surface, requiring a high concentration of energy.

[0047] Charge length: 65% of the hole depth, i.e. 5.3 m × 0.65 = 3.445 m (can be rounded to 3.4 m or 3.5 m on site).

[0048] Density of linearly packed explosives: using Φ32mm explosive rolls, q1 = 1.0 kg / m.

[0049] Single-hole charge: Q1 = 3.445 m × 1.0 kg / m ≈3.45 kg.

[0050] (2) Auxiliary hole Function: Increase the volume of the blast.

[0051] Charge length: 55% of the hole depth, i.e. 5.3 m × 0.55 m = 2.915 m (can be rounded to 2.9 m on site).

[0052] Density of linearly packed explosives: using Φ22mm explosive coils, q2 = 0.4 kg / m Single-hole charge: Q2 = 2.915 m × 0.4 kg / m ≈ 1.17 kg Total charge: 1.17 kg × 8 = 9.36 kg (3) Main blast hole Function: To achieve uniform crushing of the main rock.

[0053] Charge length: consistent with the auxiliary hole, take 2.915 m (can be rounded to 2.9 m on site).

[0054] Density of linearly packed explosive: q3 = 0.4 kg / m³ Single-hole charge: Q3 = 2.915 m × 0.4 kg / m ≈1.17 kg.

[0055] Total charge: 1.17 kg × 16 = 18.72 kg.

[0056] The main blast hole, cutting hole, and auxiliary holes all use emulsion explosives, with continuous uncoupled charging. The charging height for the cutting hole is 3.4 m, and the backfill height is 1.9 m. The charging height for the auxiliary hole is 2.9 m, and the backfill height is 2.4 m. The charging height for the main blast hole is 2.9 m, and the backfill height is 2.4 m.

[0057] V 落 Q represents the volume of rock filling the mold and the top slab after the blast; 总 q represents the total charge weight in kg; q represents the explosive consumption per unit volume in kg / m³. 3 .

[0058] According to the formula, the collapse was exactly 78.8 m.3 The crushed rock meets the requirements. This embodiment only describes the controlled blasting charging steps in detail; the specific implementation steps for the remaining steps have been explained in detail and can be completed by following the above steps, so they will not be repeated here. In the preferred embodiment with a hole depth of 5.3 m, by setting the charging coefficient of the cutting hole to 65% and the charging coefficients of the auxiliary holes and the main blasting hole to 55%, and coordinating with a specific micro-delay detonation sequence, efficient and controllable blasting of large-volume rock masses was successfully achieved, and the produced rock blocks were of uniform size and could be directly used as aggregate for casting artificial pillars.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing artificial pillars by controlled blasting and slotting in large goaf areas, characterized in that, Includes the following steps; S1. Based on three-dimensional laser scanning and ground pressure monitoring data, a three-dimensional digital model is generated through data processing software to identify potential high ground pressure instability risk areas and determine the location, shape, and size parameters of artificial pillars; S2. Based on the design parameters of the pillar mold (3), main blasting holes (5), cutting holes (6) and auxiliary holes (7) are arranged in the corresponding area of ​​the top plate (1) of the goaf, and a controlled blasting cutting groove design matching the artificial pillar is formed. S3. Set up a reinforcing steel cage (4) at the position corresponding to the pillar mold (3) at the bottom of the goaf, and complete the installation and assembly of the pillar mold (3); S4. Using a micro-differential detonation method, the cutting hole (6), auxiliary hole (7) and main detonation hole (5) are detonated in sequence, causing the roof rock to collapse in a directional manner and fall into the steel cage (4) directly below. Under the constraint of the steel cage (4), it is filled and compacted to form a composite artificial pillar. After the artificial pillar is formed and stabilized, the outer mold is removed to complete the construction of the artificial pillar, wherein the artificial pillar is directly formed by blasted rock under constrained conditions.

2. The method for constructing artificial pillars by controlled blasting and slotting in large goaf areas according to claim 1, characterized in that, In S1, the three-dimensional digital model includes information on rock mass fissures, faults, and stress concentration zones; The geometric characteristics of the curvature and subsidence of the goaf roof (1) were calculated based on a three-dimensional digital model. Select flat areas with the largest span or obvious signs of subsidence, and plan the precise location, shape and size of artificial pillars to ensure that the pillar arrangement matches the stress distribution of the goaf roof (1).

3. The method for constructing artificial pillars by controlled blasting and slotting in large goaf areas according to claim 2, characterized in that, In S1, point cloud data of the goaf (13) and the goaf roof (1) are obtained by three-dimensional laser scanning. After data cleaning, registration and splicing and triangular mesh modeling, a three-dimensional mesh model is formed. The roof subsidence and its distribution characteristics are calculated in combination with ground pressure monitoring data to identify stress concentration areas and determine the location of the pillars.

4. The method for constructing artificial pillars by controlled blasting and slotting in large goaf areas according to claim 1, characterized in that, In S2, Based on the data of the goaf roof (1) detected by the three-dimensional laser scanner, the pretreatment work of drilling the main blast hole (5), cutting hole (6) and auxiliary hole (7) was carried out on the goaf roof (1) and its surrounding area using a geological drilling rig. Cutting holes (6) are arranged in the center of the working face. Auxiliary holes (7) are arranged between the cutting holes (6) and the main blasting holes (5). The main blasting holes (5) are arranged in the outermost ring of the working face. The hole diameter is determined in combination with the required explosive rolls and the decoupling coefficient. A slag bucket is set at each hole opening to ensure the hole formation rate. The main blast hole (5), the cutting hole (6) and the auxiliary hole (7) all use emulsion explosives, and the charging method is decoupled charging; A combination of radial and axial decoupling is used to select a smaller diameter propellant cartridge and place it into a larger borehole, so that an annular air gap is formed between the outer wall of the propellant cartridge and the borehole; a centering device is used to ensure the uniformity of this gap; Secondly, axial decoupling is achieved by dividing the explosive into several independent charge segments along the borehole axis and setting an air gap of a certain length between each segment (12). Charges are loaded in front of the cutting hole (6), in the middle of the auxiliary hole (7), and at the bottom of the main blast hole (5); the remaining parts between each blast hole are separated by backfill material (8) or air gaps (12) to form a blasting groove structure for inducing directional collapse of the roof.

5. The method for constructing artificial pillars by controlled blasting and slotting in large goaf areas according to claim 4, characterized in that, in, At the corresponding main blast hole (5), backfill material (8), air gap (12), explosive column (11) and air gap (12) are arranged from top to bottom; a detonating detonator (9) is installed through the backfill material (8), the detonating detonator (9) is connected to the detonating bomb (10), and the detonating bomb (10) is located at the air gap (12) below; At the corresponding cutting hole (6), backfill material (8), explosive column (11), backfill material (8) and air gap (12) are arranged sequentially from top to bottom. A detonating detonator (9) is installed through the backfill material (8). The detonating detonator (9) is connected to the detonating bomb (10). The detonating bomb (10) is located at the air gap (12). At the corresponding auxiliary hole (7) position, backfill material (8), explosive column (11) and air gap (12) are arranged sequentially from top to bottom. The detonating detonator (9) is connected to the detonating bomb (10), and the detonating bomb (10) is located at the air gap (12).

6. The method for constructing artificial pillars by controlled blasting and slotting in large goaf areas according to claim 1, characterized in that, In S3, a pretreatment is carried out at a selected location on the top plate (1) of the goaf to form a groove (14). The steel cage (4) is placed into the groove (14) to restrain the collapsed rock and promote its molding and compaction. A pillar mold (3) is set up around the steel cage (4).

7. The method for constructing artificial pillars by controlled blasting and slotting in large goaf areas according to claim 1, characterized in that, In step S4, the cutting hole (6) at the middle position is selected as the detonation hole; After the detonation hole (6) is detonated, the auxiliary hole (7) and the main detonation hole (5) are selected to delay, and the auxiliary hole detonates ahead of the main detonation hole. Venting holes (15) are set at equal intervals on the pillar mold (3) to realize the rock mass falling from the center outward in stages.

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