A flexible stress barrier curtain construction method of mining area in situ cutting grouting

Abstract

The application discloses a kind of in situ cutting grouting mining area flexible stress barrier screen construction methods, it is related to mining protection technical field, the method is first in the transition zone between mined-out area and building plans vertical ground downward U-shaped construction path, and along this track drills out through guide hole, subsequently flexible cutting component is passed through guide hole and drives it to carry out underground cutting operation, cutting simultaneously continues to inject isolation medium into gap, and it is carried to deep place by cutting component, finally control cutting track is moved from deep to surface, form a continuous cutting gap filled with medium, that is, constitute flexible stress barrier screen.The application establishes flexible stress barrier screen between mined-out area and to be protected building, strictly locks surface subsidence and tensile deformation inside flexible stress barrier screen, so that building and subsidence area outside flexible stress barrier screen are decoupled in mechanics, realize in situ isolation protection to external building.

Description

Technical Field

[0001] This invention relates to the field of mine protection technology, specifically to a method for constructing a flexible stress barrier curtain in the mining area using in-situ cutting and grouting. Background Technology

[0002] In the field of coal mining, especially in the deep and loose coal seams that are widely distributed in my country, the extraction of underground coal seams inevitably leads to the movement and deformation of the overlying rock and soil, eventually forming a vast subsidence basin on the surface.

[0003] In the central region of a subsidence basin, the surface mainly exhibits uniform subsidence. However, in the peripheral regions of the basin (i.e., the "slope zone" or "stretch deformation zone" of the moving basin), due to the unevenness of surface movement, the soil is subjected to strong horizontal stretching directed towards the center of the goaf. Under the influence of mining, the movement of deep soil towards the goaf generates strong horizontal shear drag forces through interlayer friction and cohesion. This deep drag effect drives the overlying soil and surface towards the goaf, causing the surface subsidence area to continuously expand outward. Buildings and structures located in this expanding edge zone (slope zone), although originally located directly above the goaf, will experience severe tensile tearing and shear displacement due to the deep drag effect, leading to wall cracking, foundation fracture, and even collapse. Figure 1 The diagram shows a vertical cross-sectional structure of a subsidence basin, where 101 represents the goaf, 102 represents the bedrock layer at the bottom, 103 represents the loose layer at the top, 104 represents the coal seam in the middle, and 105 represents the surface subsidence area.

[0004] To protect structures located at the edge of a subsidence basin, the following technical measures are currently being primarily adopted:

[0005] (1) Retain protective coal pillars: This means leaving a large amount of coal under and around the building and not mining it. This is the most traditional method, but it will result in a large amount of high-quality coal resources being permanently suppressed, reducing the resource recovery rate of the mine and shortening the service life of the mine.

[0006] (2) Deformation-resistant reinforcement of buildings: Reinforce the building's own structure (such as adding ring beams, structural columns, or using deformation-resistant structures). However, this passive defense measure can only resist minor deformations. When faced with large-scale surface cracking caused by deep loose layers (for example, cracks with a width of tens of centimeters), the protective effect is minimal. Summary of the Invention

[0007] The purpose of this invention is to solve the problems in the prior art by proposing a method for constructing a flexible stress barrier curtain in the mining area through in-situ cutting and grouting. This method abandons conventional protection methods and instead cuts off the stress transmission between the goaf and the building by constructing a flexible stress barrier curtain, thereby avoiding the interference of goaf subsidence on the building.

[0008] To address the above problems, the present invention provides the following technical solution:

[0009] A method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting includes the following steps:

[0010] Step 1: Plan a construction path for generating a flexible stress barrier curtain in the transition zone between the goaf and the building to be protected. The construction path is set as a U-shaped through-track on the vertical section of the transition zone, consisting of a descending section, a deep horizontal section, and an ascending section connected end to end.

[0011] Step 2: Using the output end of the first drive source, drill from the surface entry point of the soil entry section and move the output end along the U-shaped penetration trajectory until the output end passes through the soil entry section, the deep horizontal section and the soil exit and rise section of the U-shaped penetration trajectory in sequence, and finally emerges from the surface exit point of the soil exit and rise section to form a through underground guide hole.

[0012] Step 3: At the point where soil emerges on the ground, connect one end of the flexible cutting component to the output end, and guide the flexible cutting component into the ground through the pullback output end to cover the entire length of the underground guide hole.

[0013] Step 4: Connect both ends of the flexible cutting component to the second drive source, and use the second drive source to drive the flexible cutting component to perform cutting motion underground;

[0014] Step 5: During the cutting operation, an isolation medium is continuously injected into the cut through the opening of the underground guide hole, while the movement of the flexible cutting component carries the isolation medium to the depth of the cut.

[0015] Step Six: Control the trajectory of the flexible cutting component to move gradually upward from the deep horizontal section until it cuts through to the ground surface, so as to form a continuous cut filled with an isolation medium in the soil of the transition zone between the goaf and the building to be protected. The isolation medium constitutes the flexible stress barrier curtain.

[0016] As a further aspect of the present invention: the projection trajectory of the construction path on the surface of the transition zone is parallel to the surface subsidence contour lines of the mining subsidence area.

[0017] As a further aspect of the present invention: the burial depth of the deep horizontal section is greater than the depth of the interface between the loose layer and the bedrock layer, so that the deep horizontal section cuts into the bedrock layer to a predetermined depth.

[0018] As a further aspect of the present invention: the isolation medium is a drag-reducing isolation slurry containing aggregate, the drag-reducing isolation slurry containing aggregate includes a base liquid and additives, the base liquid is bentonite slurry, and the additives include a lubricating component for reducing cutting friction resistance and an inert aggregate component for forming a physical support layer in the cut.

[0019] As a further aspect of the present invention: the inert aggregate component is selected from one or more of fly ash, fine sand, and tailings sand; the lubricating component comprises hydrolyzed polyacrylamide.

[0020] As a further aspect of the present invention: the flexible cutting assembly includes a flexible cable core and cutting modules spaced apart on the cable core.

[0021] As a further aspect of the present invention: the cutting module has a spindle-shaped or streamlined structure with pointed ends and a thick middle, and its surface is inlaid with carbide cutting teeth.

[0022] As a further aspect of the present invention: the length of the flexible stress barrier curtain is greater than the projected length of the building to be protected in the direction parallel to the mining boundary, and both ends extend out of the predetermined protection area.

[0023] As a further aspect of the present invention: the first driving source is a horizontal directional drilling rig.

[0024] As a further aspect of the present invention: the second drive source is a variable frequency hydraulic winch.

[0025] As a further aspect of the present invention, the cutting method of the flexible cutting component is a reciprocating tightening type.

[0026] As a further aspect of the present invention, the cutting method of the flexible cutting component is a ring-shaped tightening type.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention does not attempt to counteract the inevitable subsidence above the goaf, but instead constructs a continuous artificial discontinuous weak surface to cut off the shear drag force of the deep soil. This method establishes a flexible stress barrier curtain between the goaf and the building to be protected, strictly locking the surface subsidence and tensile deformation inside the flexible stress barrier curtain. This mechanically decouples the building outside the flexible stress barrier curtain from the subsidence area, thereby achieving in-situ isolation and protection of the external building without changing the subsidence trend of the goaf, resulting in good protection effect.

[0029] Of course, the path cutting method based on the above idea can also be considered as direct trenching operation supplemented by grouting, but it is obviously difficult to be practical in the context of this application. The biggest problem is that the cutting measures for excavating stress relief trenches, because the construction path is from top to bottom, require the construction process to be equipped with support baffles in sync with the excavation progress to deal with possible soil collapse on both sides of the relief trench, resulting in a long construction period. Moreover, due to the limited stability of the goaf slope and the capacity of construction machinery, the depth of the excavated relief trench is limited. Often, the relief trench formed only cuts off the connection of the loose surface soil, while the deep soil tens of meters thick below the relief trench remains continuous. That is, the goaf will still exert a drag force on the building area.

[0030] In comparison, the construction path of this invention is from bottom to top, cutting upwards from the deep soil of the loose layer (partially, the bedrock layer) through the surface soil to the ground surface. The resulting cutting depth is sufficient to completely isolate the drag force transmission between the mining area and the building area. Furthermore, the bottom-up construction path, combined with the isolation medium injected during the cutting process, can form a continuous flexible stress barrier curtain from bottom to top, which can cope with easily collapsible geological conditions and ensure construction safety.

[0031] 2. The present invention adopts a trajectory design for the deep horizontal section, which ensures that the cutting depth remains consistent and at the deepest position throughout the entire blocking length. This full-section cutting eliminates the possibility of deep stress being transmitted through bottom flow.

[0032] 3. The design of the barrier trajectory being parallel to the sinking contour line ensures that the artificial weak surface is perpendicular to the direction of the maximum horizontal tensile stress, thereby achieving the highest stress interception efficiency with minimal engineering work.

[0033] 4. By setting two cutting methods, reciprocating and annular, for the flexible cutting component, the appropriate cutting method can be selected according to the actual situation when carrying out corresponding isolation and protection operations in different areas, which greatly expands the application scenarios of this method.

[0034] 5. Utilizing a construction technique that combines in-situ cutting with grouting replacement, an inert isolation medium containing aggregate is filled into the cut. Firstly, the isolation medium acts as a lubricant during the cutting process; secondly, the isolation medium mixes with the soil in the cut to prevent the soil from solidifying during the cutting process, thus avoiding the healing of the cut; thirdly, the isolation medium not only has a tensile strength close to zero but also is incompressible, forming a permanent geological isolation zone. Attached Figure Description

[0035] The invention will now be further described with reference to the accompanying drawings.

[0036] Figure 1This is a schematic diagram of the vertical cross-sectional structure of a subsidence basin in existing technology.

[0037] Figure 2 This is a top view schematic diagram of the subsidence basin and the building to be protected according to the present invention;

[0038] Figure 3 This is a three-dimensional structural diagram of the construction path of the present invention;

[0039] Figure 4 This is a schematic diagram of the construction path cross-sectional structure of the present invention. Figure 1 ;

[0040] Figure 5 This is a schematic diagram of the construction path cross-sectional structure of the present invention. Figure 2 ;

[0041] Figure 6 This is a schematic diagram of the cross-sectional structure of the U-shaped through trajectory of the present invention;

[0042] Figure 7 This is a schematic cross-sectional view of the flexible stress barrier curtain formed after cutting and grouting according to the present invention.

[0043] In the diagram: 101, goaf; 102, bedrock layer; 103, loose layer; 104, coal seam; 105, surface subsidence area; 1, surface subsidence contour line; 2, horizontal tension extension direction; 3, flexible stress barrier curtain; 4, building to be protected; 5, first drive source; 6, flexible cutting component; 7, second drive source; 8, grouting pump; 9, soil entry and descent section; 10, deep horizontal section; 11, soil exit and ascent section. Detailed Implementation

[0044] 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.

[0045] like Figures 2-7 As shown, a method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting includes the following steps:

[0046] Step 1: Spatial planning for blocking paths

[0047] Based on the advancement parameters of goaf 101, geological exploration data, and surface subsidence prediction results, a construction path for a flexible stress barrier curtain 3 is planned between goaf 101 and the building to be protected 4. Specifically, the trajectory of the flexible stress barrier curtain 3 is designed to be parallel to the surface subsidence contour lines (or deformation contour lines) 1 of goaf 101;Figure 2 It can be seen that the trajectory of the flexible stress barrier curtain 3 is almost parallel to the outermost surface subsidence contour line 1 of the goaf 101. This parallel layout ensures that the normal direction of the flexible stress barrier curtain 3 is consistent with the direction of the main horizontal tensile stress of the soil, so as to maximize the stress interception efficiency.

[0048] For the design of the construction path, the trajectory of the underground pilot hole that penetrates the loose layer 103 can be planned, such as... Figure 4 and Figure 6 As shown, the trajectory exhibits a "bathtub-shaped" or "U-shaped" structure in vertical cross-section, specifically composed of three segments connected end-to-end:

[0049] ① Soil entry and descent section 9: Drill downwards from the soil entry point at a predetermined angle until it passes through the full thickness of the loose layer 103 and reaches the predetermined barrier depth;

[0050] ② Deep horizontal section 10: Located at the bottom of loose layer 103, its trajectory extends horizontally or nearly horizontally. This section accounts for the main length of the flexible stress barrier curtain 3 and is used to cut through the bottom interface of loose layer 103 to eliminate the bottom flow path;

[0051] ③ Excavation and Ascent Section 11: Starting from the end of the deep horizontal section 10, drill upward at a predetermined angle until the soil emerges from the ground.

[0052] Step 2: Construction of Horizontal Directional Drilling Pilot Hole

[0053] Using the first drive source (such as a large-tonnage horizontal directional drilling rig) 5, a hole is opened from the ground entry point. With the help of the magnetic guidance system, the drill bit is controlled to drill along the trajectory planned in step one. The drill bit strictly follows the path of "descending - horizontal - ascending". After passing through the loose layer 103, it finally forms an underground guide hole with open ends and a horizontal middle.

[0054] Step 3: Insert the cutting component and connect it to the system.

[0055] At the exit point, one end of the flexible cutting component (e.g., a flexible cutting chain, preferably a diamond beaded rope or a toothed chain) 6 is connected to the drill rod that has penetrated the guide hole; the drilling rig is then operated to pull back the drill rod, introducing the flexible cutting component 6 and completely covering the entire underground guide hole trajectory. After removing the drill rod, the two ends of the flexible cutting component 6 exposed above ground are connected to a second drive source (e.g., a variable frequency hydraulic winch) 7 located near the entry and exit points, respectively.

[0056] Step 4: Prioritize cutting and grouting of deep horizontal sections.

[0057] The second drive source 7 is activated to control the flexible cutting component 6 to perform a reciprocating sawing motion underground. Simultaneously, a ground grouting system (e.g., several additional grouting pumps 8 on the ground) continuously injects drag-reducing and isolating grout containing aggregate into the cut through the orifice. In the initial stage of the cutting operation, by controlling the tension of the second drive sources 7 at both ends, the flexible cutting component 6 preferentially performs transverse reciprocating cuts in the deep horizontal section 10. This process severs the shear connection between the loose layer 103 and the bedrock layer 102, and uses the grout to fill the bottom cut immediately, forming a horizontal lubricating and isolating layer at the bottom.

[0058] Step 5: Construct artificial discontinuities from bottom to top

[0059] As the cutting operation continues, the second drive source 7 applies upward tension while maintaining reciprocating pulling, causing the trajectory of the flexible cutting component 6 to gradually move upward parallel to the ground from the deep horizontal section 10 (i.e., from the bottom of the U-shape upwards). The cutting process continues until the flexible cutting component 6 cuts through to the ground surface. At this point, a vertical or near-vertical continuous gap filled with slurry solidification is formed on the barrier trajectory surface. The slurry within this continuous gap is the aforementioned flexible stress barrier curtain 3, constituting an artificial discontinuous weak surface that blocks stress transmission, thus confining the subsidence deformation caused by mining to the inside of the flexible stress barrier curtain 3 (within the range of...). Figure 2 From the perspective shown (i.e., the left side), ensure the protection of the object side (with... Figure 2 From the perspective shown (i.e., the right side), the soil is in a relatively stable state.

[0060] Furthermore, the location of the deep horizontal section 10 can be set not only at the bottom of the aforementioned loose layer 103, but also at a predetermined depth of the bedrock layer 102. That is, the flexible cutting component 6 needs to cut into the bedrock layer 102 to a certain depth (e.g., 3-5 meters). This design can ensure that the locking section at the bottom of the loose layer 103 is completely cut off.

[0061] Meanwhile, this application also improves the grout, specifically: the drag-reducing and isolating grout comprises a thixotropic mud matrix (such as bentonite), a lubricant (such as PHPA), and inert aggregates (such as fly ash and fine sand). During cutting, the grout lubricates and reduces drag, and supports the borehole wall; after solidification, the inert aggregates provide physical support, preventing the cut from failing to close under ground stress. It should be noted that the grout's function here is to fill the cut, aiming to create a discontinuous weak surface, thereby decoupling the goaf 101 from the protected building 4 area, rather than connecting the two; therefore, the grout can be formulated according to the above proportions or other specific conditions, which will not be elaborated upon here to avoid unnecessary detail.

[0062] Regarding the cutting action of the aforementioned flexible cutting component 6, this application is not limited to the reciprocating cutting in step four, such as... Figure 5 As shown, it can also be set up as a ring-shaped cutter. Specifically, the second drive source (which can still be set as a variable frequency hydraulic winch or other existing technology components) 7 is set up only on the ground surface. During the cutting process, the cutting path is moved upward by synchronously tightening the flexible cutting component 6 until the cutting reaches the ground surface.

[0063] The following is an example of a powerhouse protection project in a deep, loose strata mining area of ​​a certain mine:

[0064] (1) Project Background

[0065] The surface of the 101 working face in a coal mine goaf is covered by a very thick loose layer (mainly loess and quicksand) 103, with an average thickness of 80 meters, and the bedrock layer 102 is sandstone. After the 101 working face is advanced, surface subsidence prediction shows that an industrial plant located at the edge of the subsidence basin (slope zone) will be subjected to strong horizontal tensile stress, with the maximum horizontal deformation expected to reach 6.0 mm / m, far exceeding the building's bearing capacity. Due to the excessive thickness of the loose layer 103 and the significant shear drag effect, traditional methods of reinforcing the building's own structure are ineffective. Therefore, the method described in this application is used to construct a deep artificial discontinuous weak surface to eliminate shear drag force and limit the subsidence range.

[0066] (2) Construction parameters and steps

[0067] Step 1: Spatial planning for blocking paths

[0068] Based on the predicted surface movement and deformation, a planar layout is established to determine the distribution of the surface subsidence contour line 1. Between the industrial plant and the goaf 101, a projection line of a flexible stress-barrier curtain 3 is planned. This projection line is designed to be nearly parallel to the estimated -30mm surface subsidence contour line 1, ensuring that the flexible stress-barrier curtain 3 vertically interrupts the horizontal tensile stress flow pointing towards the industrial plant. The barrier line is designed to be 500 meters long, extending 30 meters beyond the plant boundary at each end.

[0069] Profile trajectory design: To ensure full-section cutting through the 80-meter-thick loose layer 103 and eliminate bottom flow bypass, the vertical profile of the underground guide hole is designed as a U-shaped trajectory, with specific parameters as follows:

[0070] ① Section 9 of the descent into the ground: Inclination rate 12° / 30m, drilling to a vertical depth of 90 meters;

[0071] ② Deep horizontal section 10: The design depth is maintained at 90 meters (i.e., cutting through 80 meters of loose layer 103 and penetrating 10 meters into the interface of bedrock layer 102). The length of deep horizontal section 10 is about 450 meters, covering the main protected area.

[0072] ③ Excavation and Ascent Section 11: Drilling at an angle from the deep part towards the excavation point.

[0073] Step 2: Construction of Horizontal Directional Drilling Pilot Hole

[0074] A large horizontal directional drilling rig with a thrust-pull force of 2000kN (200 tons) was selected for drilling, in conjunction with a magnetic guidance system. The drill bit strictly followed the designed U-shaped trajectory. When drilling to the deep horizontal section 10, the inclination angle deviation was strictly controlled within ±0.5° to ensure that the borehole remained within the bedrock weathering zone, forming a continuous Φ300mm underground guide hole.

[0075] Step 3: Insert the cutting component

[0076] ① Chain Selection: A specially designed flexible cutting cable is used. The core of the cable is a Φ32mm high-strength aviation steel wire rope; a shuttle-shaped (streamlined) cutting bead is installed every 0.5 meters along the cable, and the surface of the bead is inlaid with YG8 tungsten cobalt alloy cutting teeth. The shuttle-shaped design is intended to reduce soil resistance during deep pullback and cutting.

[0077] ② Insertion operation: Connect the flexible cutting cable to the drill rod at the soil exit point, and use the drill rig's pullback function to pull the approximately 800-meter-long flexible cutting cable into the hole so that it completely covers the U-shaped trajectory.

[0078] Step 4: Prioritize cutting and grouting of deep horizontal sections.

[0079] (1) Power connection

[0080] Two variable frequency hydraulic winches with a pulling force of 50 tons are installed at each end of the ground.

[0081] (2) Slurry preparation

[0082] A drag-reducing and isolation grout containing aggregate was prepared with the following proportions (by weight): 100 parts water, 10 parts sodium bentonite (for wall protection), 0.3 parts PHPA polymer (for lubrication and drag reduction), and 40 parts fly ash (for inert aggregate). It should be noted that this grout is incompressible after solidification.

[0083] (3) Cutting operation

[0084] The winches were started, and the flexible cutting cable was controlled to perform a reciprocating sawing motion at a speed of 0.5 m / s, moving from deep to shallow depths. Initially, the tension of both winches was controlled to ensure the flexible cutting cable made lateral cuts at the bedrock interface at a depth of 90 meters. This process lasted approximately 20 hours, completely severing the shear-locked connections at the bottom of loose layer 103, and filling the bottom cut with grout.

[0085] (4) Accompanying grouting

[0086] Throughout the process, grout is pumped into the orifice at a flow rate of 60 L / min. The grout can displace the soil debris as the flexible cutting cable moves. When the flexible cutting cable cannot displace the soil debris, the grout can be directly mixed with the soil debris. Ultimately, the grout will form an artificial discontinuous weak surface in the cut.

[0087] Step 5: Creating Artificial Discontinuous Weak Surfaces and Verifying the Effect

[0088] As the artificial discontinuous weak surface gradually increases, the trajectory of the flexible cutting cable moves upward in parallel, cutting through to the ground surface in about 5 days. The cut is filled with grout, which, after solidification, forms a continuous physical isolation zone about 80mm wide, 90m deep, and 500m long, which is the flexible stress barrier curtain 3.

[0089] Subsequent field measurements showed that, inside the flexible stress barrier curtain 3 (on the goaf 101 side): the surface subsidence reached 480 mm, with a horizontal deformation of 4.5 mm / m (indicating normal subsidence); outside the flexible stress barrier curtain 3 (on the plant side): the surface subsidence suddenly dropped to 30 mm, with a horizontal deformation of only 0.2 mm / m (in a safe state of slight deformation). Monitoring data indicates that the surface deformation experienced a precipitous change at the flexible stress barrier curtain 3, proving that this method successfully cut off the deep drag force, strictly limiting the subsidence and damage range within the cutting line, and achieving in-situ protection of the plant.

[0090] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting, characterized in that, Includes the following steps: Step 1: Plan a construction path for generating a flexible stress barrier curtain in the transition zone between the goaf and the building to be protected. The construction path is set as a U-shaped through-track on the vertical section of the transition zone, consisting of a descending section, a deep horizontal section, and an ascending section connected end to end. The deep horizontal section is located at the bottom of the loose layer or at a predetermined depth in the bedrock layer; The projection trajectory of the construction path on the surface of the transition zone is parallel to the surface subsidence contour lines of the goaf. The length of the flexible stress barrier curtain is greater than the projected length of the building to be protected in the direction parallel to the mining boundary, and both ends extend out of the predetermined protection area. Step 2: Using the output end of the first drive source, drill from the surface entry point of the soil entry section and move the output end along the U-shaped penetration trajectory until the output end passes through the soil entry section, the deep horizontal section and the soil exit and rise section of the U-shaped penetration trajectory in sequence, and finally emerges from the surface exit point of the soil exit and rise section to form a through underground guide hole. Step 3: At the point where soil emerges on the ground, connect one end of the flexible cutting component to the output end, and guide the flexible cutting component into the ground through the pullback output end to cover the entire length of the underground guide hole. Step 4: Connect both ends of the flexible cutting component to the second drive source, and use the second drive source to drive the flexible cutting component to perform cutting motion underground; Step 5: During the cutting operation, an isolation medium is continuously injected into the cut through the opening of the underground guide hole, while the movement of the flexible cutting component carries the isolation medium to the depth of the cut. Step Six: Control the trajectory of the flexible cutting component to move gradually upward from the deep horizontal section until it cuts through to the ground surface, so as to form a continuous cut filled with an isolation medium in the soil of the transition zone between the goaf and the building to be protected. The isolation medium constitutes the flexible stress barrier curtain.

2. The method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting as described in claim 1, characterized in that, The burial depth of the deep horizontal section is greater than the depth of the interface between the loose layer and the bedrock layer, so that the deep horizontal section can cut into the bedrock layer to a predetermined depth.

3. A method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting, as described in claim 1 or 2, characterized in that... The isolation medium is a drag-reducing isolation slurry containing aggregate, which includes a base liquid and additives. The base liquid is bentonite slurry, and the additives include a lubricating component for reducing cutting friction resistance and an inert aggregate component for forming a physical support layer in the cut.

4. The method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting as described in claim 3, characterized in that, The inert aggregate component is selected from one or more of fly ash, fine sand, and tailings sand; the lubricating component includes hydrolyzed polyacrylamide.

5. A method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting, as described in claim 1 or 2, characterized in that... The flexible cutting assembly includes a flexible cable core and cutting modules spaced apart on the cable core.

6. The method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting as described in claim 5, characterized in that, The cutting module has a spindle-shaped or streamlined structure with pointed ends and a thicker middle, and its surface is inlaid with carbide cutting teeth.

7. A method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting, as described in claim 1 or 2, characterized in that... The flexible cutting component uses a reciprocating tightening method for cutting.

8. A method for constructing a flexible stress barrier curtain in a mining area using in-situ cutting and grouting, as described in claim 1 or 2, characterized in that, The flexible cutting component uses a ring-shaped tightening cutting method.

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