Grouting reinforcement method for broken roof and tectonic area of three-soft coal seam

Abstract

The invention relates to the technical field of grouting reinforcement, in particular to a three-soft coal seam broken roof and tectonic area grouting reinforcement method which comprises the following steps that coal seam and roof drilling peeping is conducted through a directional drill, and fracture distribution characteristic information is obtained; making a drill hole arrangement scheme according to the fracture distribution characteristic information, the coal seam thickness and the working face propulsion parameters; drilling holes in a coal seam roof construction layer based on the drilling hole arrangement scheme, and performing grouting reinforcement; reinforcing drill holes are constructed in the advanced position of the working face, and grouting is conducted; according to the grouting reinforcement method for the broken roof and the tectonic area of the three-soft coal seam, through organic connection of all links, reliable reinforcement of the broken roof and the tectonic area of the three-soft coal seam is achieved, and safe advancing of the coal face is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of grouting reinforcement, and in particular to a grouting reinforcement method for a broken roof and a structural area of a three-soft coal seam. Background Art

[0002] In coal mining, "three-soft" coal seams refer to special geological structures where the roof, coal seam, and floor are all soft rock. During mining, the softness of the coal seam and the fragmentation of the roof and floor make it very easy for disasters such as roof falls, floor heaves, and rock spalling to occur, seriously threatening mine safety and production. Currently, grouting reinforcement is the primary technical means of addressing the fractured roof and structural areas of "three-soft" coal seams. However, in practical application, there is a prominent technical problem: Existing grouting reinforcement technology for soft coal seams lacks a systematic process. Specifically, in the early stages of reinforcement, geological information is primarily acquired through single-point drilling, making it difficult to accurately assess fracture development characteristics. During the design phase, drill hole placement is often determined empirically, lacking a comprehensive understanding of geological conditions. During construction, a single reinforcement method is employed, failing to effectively address complex geological conditions. This fragmented technical approach results in poor reinforcement effectiveness and short-term sustainability, making it difficult to meet the requirements for safe mining of soft coal seams. Summary of the Invention

[0003] The present invention provides a grouting reinforcement method for the broken roof and structural area of the three-soft coal seam. The grouting reinforcement method for the broken roof and structural area of the three-soft coal seam achieves reliable reinforcement of the broken roof and structural area of the three-soft coal seam through the organic connection of various links, ensuring the safe advancement of the coal mining working face.

[0004] An embodiment of the present invention provides a grouting reinforcement method for the broken roof and structural area of three-soft coal seams, comprising the following steps: drilling holes in the coal seam and the roof through directional drilling to obtain crack distribution characteristic information; formulating a drilling arrangement plan according to the crack distribution characteristic information, coal seam thickness and working face advancement parameters; drilling holes in the coal seam roof construction layer based on the drilling arrangement plan, and performing grouting reinforcement; constructing reinforcement holes and grouting at the advanced position of the working face; constructing oblique holes in the middle of the coal seam, and using quick-setting materials to grout and reinforce the coal wall of the working face.

[0005] In one possible implementation, the fracture distribution characteristic information includes: fracture azimuth, fracture aperture and fracture connectivity; the grouting area range is determined based on the fracture distribution characteristic information; and the drilling arrangement plan includes drilling spacing, drilling depth and drilling angle.

[0006] In one possible implementation, the layer-wise drilling is carried out using a staged drilling method, including: a first stage using a large-diameter hole and inserting a casing; a second stage using a drill bit smaller than the inner diameter of the casing to continue drilling to a designed depth.

[0007] In one possible implementation, the arrangement of reinforcement boreholes is determined based on the following parameters: geological structure parameters, including fault strike and fold axis distribution; grouting target layer parameters, including layer position and dip; working face parameters, including advancement speed, advancement direction and mining height.

[0008] In one possible implementation, the reinforcement boreholes are arranged in a fan-shaped manner, including: determining a starting angle and an ending angle; determining the borehole spacing according to geological conditions; and extending the end hole position to the rear of the fault plane.

[0009] In a possible implementation, the oblique borehole is substantially perpendicular to the coal wall spalling fissure and extends to the coal seam roof.

[0010] In one possible implementation, the method further includes grouting quality control steps: constructing inspection holes at preset intervals between directional drilling holes; collecting core samples for compressive strength testing; and evaluating the grouting filling effect through sonic testing.

[0011] In one possible implementation, directional drilling adopts a "belt, feather, and net" arrangement to form a net-like reinforcement structure on the coal seam roof.

[0012] In one possible implementation, the arrangement characteristics of the reinforcement boreholes are: intersecting with the fault and fold axis traces at a large horizontal angle in the plane; making the nearly horizontal boreholes in the layer contact the interlayer structural surface; and intersecting with the direction of the maximum horizontal principal stress.

[0013] In a possible implementation, the end hole position of the reinforcement drilling extends horizontally to 3-5 meters from the fault surface.

[0014] The grouting reinforcement method for the broken roof and structural areas of three-soft coal seams provided by the present invention solves the technical problem of the lack of systematicity in grouting reinforcement of three-soft coal seams by establishing a complete "detection-design-construction" system process. First, directional drilling peek technology is used to systematically detect regional fracture characteristics. By comprehensively acquiring key parameters such as fracture inclination angle, fracture aperture, and connectivity, the regional geological conditions can be accurately assessed. Based on the detection data, a quantitative evaluation system for the degree of fracture development is established, and the scope of the area requiring reinforcement is scientifically delineated, providing a reliable basis for the design of subsequent reinforcement schemes. In the reinforcement design phase, the regional fracture distribution characteristic information, coal seam parameters, and working face parameters are organically combined, and a three-dimensional reinforcement model combining layer-by-layer drilling roof grouting and advanced reinforcement drilling is adopted. This three-dimensional layout ensures a good match between the reinforcement project and the geological conditions and can target different types of weak and broken zones. During the construction process, a graded drilling process and quick-setting material grouting technology are adopted, which not only ensures the quality of the drilling construction, but also achieves the rapid solidification of the grouting material and the timely implementation of the support effect. By seamlessly integrating these various steps, we achieved full control over the entire process, from geological information collection to reinforcement results, significantly improving the overall effectiveness of the reinforcement project. This method demonstrates excellent adaptability, particularly in complex geological conditions such as fault fracture zones, effectively ensuring the safe advancement of coal mining operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a flow chart of a grouting reinforcement method for a broken roof and structural area of a three-soft coal seam provided by the present invention.

[0017] Figure 2 This is a flow chart of the “surface, line, and point” reinforcement method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0018] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0019] The following combination Figure 1-2Description: The embodiment of the present invention provides a grouting reinforcement method for the broken roof and structural area of three-soft coal seams, including the following steps: S1. Drill holes in the coal seam and roof through directional drilling to obtain information on fracture distribution characteristics; S2. Develop a drilling arrangement plan based on fracture distribution characteristics, coal seam thickness, and working face advancement parameters; S3. Drill holes in the coal seam roof construction layer based on the drilling arrangement plan and perform grouting reinforcement; S4. Drill and grout reinforcement holes at the leading position of the working face; S5. Drill oblique holes in the middle of the coal seam and use quick-setting material grouting to reinforce the coal wall of the working face.

[0020] In this invention, the problem of strengthening the three soft coal seams is solved by establishing a systematic process system of "detection-design-construction". First, directional drilling peek technology is introduced into the field of fracture feature detection, breaking through the limitation of incomplete information acquisition of traditional single-point exploration; a drilling layout plan is established based on fracture distribution feature information, coal seam parameters and working face parameters, changing the traditional empirical drilling method; a three-dimensional reinforcement mode combining layer-wise drilling roof grouting with advanced reinforcement drilling is adopted to overcome the problems of poor effect and short sustainability of single reinforcement methods; and the coal wall is reinforced by grouting with quick-setting materials, solving the problem of delayed support effect caused by the long curing time of traditional materials.

[0021] This solution also enhances the scientific nature of engineering design, allowing grouting parameters to be optimized and adjusted based on actual geological conditions. It also enhances the controllability of the construction process, creating an organic connection between each link. It also ensures the durability of the reinforcement effect through a multi-layered reinforcement system that supports each other. This systematic technical solution demonstrates strong adaptability and reliability, especially in complex geological conditions.

[0022] In actual engineering applications, directional drilling holes with a diameter of at least 89 mm were used for crack detection. These holes were systematically spaced every 10 meters horizontally and every 50 meters horizontally, forming a comprehensive geological information collection network. The areas requiring reinforcement were precisely defined based on the criteria of at least two cracks per 10 meters and a crack aperture of at least 5 mm. This quantitative approach significantly improved the scientific nature and reliability of the reinforcement plan.

[0023] When addressing fault fracture zones, traditional single reinforcement methods often suffer from issues such as incomplete exploration information, weakly targeted reinforcement plans, and difficulty ensuring construction quality. However, this solution, through directional drilling, obtains detailed geological information, develops a targeted reinforcement plan, and employs staged drilling to ensure construction quality, ultimately achieving a comprehensive reinforcement effect.

[0024] In some embodiments, the fracture distribution characteristic information includes: fracture azimuth, fracture aperture and fracture connectivity; the grouting area range is determined based on the fracture distribution characteristic information; the drilling arrangement plan includes drilling spacing, drilling depth and drilling angle.

[0025] This invention utilizes a directional drilling peek system to not only capture basic parameters such as fracture azimuth, aperture, and connectivity, but also introduces quantitative evaluation of fracture development into the field of three-soft coal seam reinforcement. The system collects parameters including fracture inclination and dip, fracture aperture, filling properties, connectivity, and development density, forming a comprehensive fracture characteristic database.

[0026] In addition, the clarity of the crack images obtained by high-precision peeping equipment reaches 0.1mm, which can accurately identify micro-cracks; based on digital image processing technology, the automatic extraction of crack parameters is realized, which significantly improves the data collection efficiency; the established crack evaluation index system covers geometric, mechanical and hydrological characteristics, providing a comprehensive basis for the design of subsequent reinforcement schemes.

[0027] Specifically, the plan systematically arranges exploration boreholes to form a complete exploration network. Vertical intervals of 10 meters ensure continuity of fracture information at varying depths, while horizontal intervals of 50 meters guarantee complete lateral coverage. At least 30 sets of fracture data were collected at each exploration point, and statistical analysis was performed to establish a regional fracture development model. This model enables scientific delineation of reinforcement areas and optimization of grouting parameters.

[0028] Engineering practice has shown that, when used in a certain mining area, the system discovered cracks that were difficult to identify using traditional drilling, allowing for timely adjustments to the reinforcement plan and avoiding potential safety hazards. Furthermore, based on accurate crack data, the selection and proportioning of grouting materials are more targeted, and the control of grouting pressure and injection volume is more precise, ultimately improving the reinforcement effect by over 30%.

[0029] In some embodiments, the construction of the layer-wise drilling adopts a staged drilling method, including: the first stage uses a large-diameter drilling and inserting a casing; the second stage uses a drill bit with an inner diameter smaller than the casing to continue drilling to the designed depth.

[0030] The embodiments provided by this invention address the challenges of drilling in soft rock. The first stage utilizes a large-diameter hole and casing, effectively preventing borehole collapse. The second stage utilizes a drill bit smaller than the inner diameter of the casing, ensuring continued drilling efficiency and facilitating grouting pipe installation. This multi-stage drilling approach overcomes the technical bottleneck of traditional single-stage drilling, which is prone to collapse and poor hole quality in soft rock formations.

[0031] Specifically, the first-stage drilling uses a 190mm large-diameter drill bit, which can effectively reduce stress concentration during the drilling process and reduce damage to the hole wall; at least 20m of φ146mm casing is lowered to form a stable wall protection system to prevent formation collapse; the second-stage drilling continues with a 120mm drill bit, forming a reasonable gap with the inner diameter of the casing to facilitate the discharge of drill cuttings and improve drilling efficiency.

[0032] Furthermore, in terms of process control, the drilling speed is controlled at 0.5-1.0 m / min to ensure hole quality. The flushing fluid ratio is optimized to ensure chip removal without damaging the soft rock structure. The drill tool selection is highly targeted to adapt to the characteristics of the soft rock. These refined process control measures ensure the quality of drilling construction.

[0033] In the construction of a soft rock tunnel, the drilling success rate using this technology reached over 95%, a 30% increase over the traditional technology; the drilling axis deviation was controlled within 3%, meeting the grouting accuracy requirements; the construction efficiency was increased by 40%, significantly reducing the project cost.

[0034] In some embodiments, the arrangement of the reinforcement boreholes is determined based on the following parameters: geological structure parameters, including fault strike and fold axis distribution; grouting target layer parameters, including layer position and dip; working face parameters, including advancement speed, advancement direction and mining height.

[0035] This invention establishes a three-dimensional design system based on "geological structural characteristics, target layer properties, and working face parameters." This incorporates tectonic elements such as fault strikes and fold axis traces into the design, while also combining coal seam occurrence characteristics and mining process parameters to achieve precise placement of reinforcement projects.

[0036] Specifically, by maintaining an angle of 60-90° with the fault and fold axis traces, the intersection probability of the borehole and the fracture surface is maximized, thereby increasing the penetration range of the grouting material. The drilling trajectory is optimized based on the changes in the inclination and thickness of the coal seam to ensure the uniform distribution of the grouting material in the target layer. Dynamic factors such as the working face advancement speed and direction are incorporated into the design to achieve optimal coordination between the reinforcement project and the mining operation.

[0037] In treating a fault fracture zone in a mining area, the drill holes arranged using this solution achieved an 85% intersection rate with the main fracture groups, increasing grouting material utilization by 40%. By placing reinforcement holes 50 meters ahead of the working face, a "dynamic advancement, continuous reinforcement" operation model was established, effectively preventing support failure caused by mining disturbances.

[0038] In some embodiments, the reinforcement drill holes are arranged in a fan shape, including: determining a starting angle and an ending angle; determining the drill hole spacing according to geological conditions; and extending the end hole position to the rear of the fault plane.

[0039] This invention solves the spatial coverage problem in complex geological conditions by scientifically determining the starting and ending angles. A differentiated spacing control system based on geological conditions is established, achieving an optimal balance between reinforcement effectiveness and engineering investment. The design concept of extending the final hole position behind the fault plane is proposed, forming a reliable protection system.

[0040] Specifically, the fan-shaped arrangement achieves progressive coverage from near to far, and the distribution of grouting materials is more reasonable; the differentiated spacing design (3-5m in dense sections and 5-8m in sparse sections) not only ensures the reinforcement effect but also optimizes the project cost; the design of the final hole extending 3-5m forms a "safety barrier" behind the fault.

[0041] Among them, the drilling angle interval is 10-15° to ensure uniform coverage; the fan-shaped expansion angle is dynamically adjusted according to geological conditions, usually in the range of 60-90°; the drilling depth is coordinated with the width of the fault influence zone to form overall protection.

[0042] In a specific embodiment, the fault fracture zone treated by this scheme has a reinforced body strength of more than 80% of the original rock strength; the infiltration and diffusion radius is increased by 45% compared with the traditional arrangement; and the project cost is reduced by 30%, which has significant technical and economic advantages.

[0043] In some embodiments, the oblique borehole is substantially perpendicular to the coal wall spalling fissure and extends to the coal seam roof.

[0044] The coal wall reinforcement solution proposed in this embodiment solves the problem of coal wall spalling and instability. By drilling holes in the middle of the coal seam and extending perpendicularly to the spalling fissures, the coal body and roof are integrally reinforced. This three-dimensional reinforcement concept of "center hole, oblique extension, and top-to-bottom penetration" overcomes the limitations of traditional parallel arrangements.

[0045] Specifically, the middle opening is located at 1 / 2 of the height from the bottom plate to effectively control the deviation of the drilling trajectory; the design intersects with the spalling cracks at 75-90° and extends to the top plate to form a continuous support structure.

[0046] Among them, the opening angle is controlled at 30-45° to ensure the best intersection with the main cracks; the drilling parameters are adjusted in real time to ensure trajectory accuracy; the grouting pressure and flow are dynamically optimized to improve the filling effect.

[0047] In some embodiments, the grouting quality control step is also included: constructing inspection holes at preset intervals between directional drilling holes; collecting core samples for compressive strength testing; and evaluating the grouting filling effect through sonic testing.

[0048] The present invention implements dynamic grouting pressure control based on formation characteristics. By correlating grouting pressure with fracture characteristics, formation stress state, and rock mass strength, it overcomes the limitations of traditional fixed-pressure grouting. A graded pressure system based on fracture aperture is established, a dynamic pressure regulation mechanism is proposed, and a mapping relationship between grouting pressure and diffusion radius is created.

[0049] Specifically, the initial grouting pressure was set at 2-3 MPa to avoid formation damage caused by excessive pressure; the intermediate pressure was stabilized at 4-6 MPa to ensure sufficient material penetration; and the final pressure was controlled at 8-10 MPa to form a stable reinforcement. By real-time monitoring of grouting pressure and flow rate, a "pressure-flow" coupled control model was established, achieving precise regulation of the grouting process.

[0050] In engineering applications, this solution significantly improved grouting quality: the grouting filling rate was increased to over 95%, the strength uniformity of the reinforced body was improved by 50%, and the grouting material utilization rate was increased by 40% compared to traditional processes. Especially when treating complex fault zones, precise pressure control prevented grouting and channeling, significantly improving the reinforcement effect.

[0051] In some embodiments, directional drilling adopts a "belt, feather, and net" arrangement to form a net-like reinforcement structure on the coal seam roof.

[0052] The grouting material grading solution proposed in this embodiment addresses the problem of differentiated treatment of different types of fractures. This solution establishes a matching relationship between fracture characteristics, material properties, and grouting parameters, achieving optimal grouting material configuration. It also establishes a material grading system based on fracture aperture, proposes a synergistic mechanism for composite materials, and creates an evaluation system for the adaptability of material properties to formation conditions.

[0053] Specifically, for fine cracks (≤2mm), ultrafine cement-based materials are used, and their optimized particle size distribution design ensures good permeability; for medium cracks (2-5mm), modified cement-based materials are used, and ideal rheological properties are achieved through additive regulation; for large cracks (>5mm), a composite material system is used, which not only ensures economy but also achieves good mechanical properties.

[0054] In engineering applications, the tiered application of materials has increased grouting integrity by 40%, increased reinforcement strength by 55% compared to single-material applications, and reduced construction costs by 35%. Especially when addressing complex fault zones, the synergistic effect of different materials forms a complete protection system, significantly improving reinforcement effectiveness.

[0055] In some embodiments, the arrangement characteristics of the reinforcement drill holes are: intersecting with the fault and fold axis traces at a large horizontal angle on the plane; making the nearly horizontal drill holes along the layer contact the interlayer structural surface; and intersecting with the direction of the maximum horizontal principal stress.

[0056] This invention achieves a three-dimensional evaluation of reinforcement effectiveness through a combination of geophysical exploration, drilling, and field testing. Innovations include establishing a multi-parameter comprehensive evaluation index system, proposing a dynamic monitoring and feedback mechanism, and creating a reinforcement effectiveness early warning system.

[0057] Specifically, high-density electrical geophysical prospecting accurately delineated the grouting diffusion range, improving evaluation accuracy by 60%. Acoustic testing technology enabled quantitative evaluation of reinforcement integrity. On-site coring tests provided intuitive quality verification data. This evaluation system not only enables timely identification of construction quality issues but also guides subsequent optimization of construction parameters.

[0058] In terms of construction process control, a complete inspection standard has been established: the distance between geophysical detection lines is no more than 5m to ensure coverage integrity; an acoustic test point is located every 20m to ensure continuous monitoring; and core extraction verification is implemented at a ratio of 3%, providing reliable quality data.

[0059] In some embodiments, the final hole position of the reinforcement drilling extends horizontally to 3-5 meters from the fault surface.

[0060] This embodiment of the present invention enables automated management of the entire grouting reinforcement process. It incorporates Internet of Things (IoT) technology, big data analysis, and intelligent control algorithms into the field of grouting reinforcement for three soft coal seams, establishing a closed-loop management system of "collection-analysis-control-optimization." A multi-source data real-time acquisition system has been established; an intelligent analysis and decision-making model has been developed; and a remote monitoring and early warning platform has been constructed.

[0061] In terms of data acquisition and monitoring: the pressure sensor has an accuracy of 0.01MPa, which enables precise monitoring of grouting pressure; the flow metering accuracy reaches 0.1L / min, ensuring accurate control of grouting volume; the displacement monitoring accuracy reaches 0.1mm, allowing timely detection of formation deformation; the data acquisition frequency can reach 10Hz, ensuring the continuity of monitoring.

[0062] In terms of intelligent analysis and control: a parameter optimization model based on machine learning was established, and the accuracy of grouting parameter adjustment was improved by 65%; an abnormal working condition identification algorithm was developed, with an early warning accuracy of over 90%; and remote and precise control of grouting equipment was achieved, with a response time of less than 100ms.

[0063] Improved management efficiency: paperless management of the construction process has increased data processing efficiency by 80%; the time to trace quality issues has been shortened by 70%; and the construction parameter optimization cycle has been reduced by 50%.

[0064] In engineering practice, the system has significantly improved construction quality and efficiency: after application in one mining area, grouting efficiency increased by 45%, material utilization increased by 35%, and the reinforcement quality pass rate reached 98%. Especially when dealing with complex geological conditions, the system can automatically adjust construction parameters based on real-time monitoring data, greatly reducing human judgment errors.

[0065] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units. That is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A grouting reinforcement method for the broken roof and structural area of three-soft coal seams, characterized in that: The following steps are involved: Directional drilling is used to drill holes in the coal seam and roof to obtain information on the distribution characteristics of fractures; Formulate a drilling arrangement plan based on the fracture distribution characteristic information, coal seam thickness and working face advancement parameters; Drilling holes in the coal seam roof construction layer based on the drilling arrangement plan and performing grouting reinforcement; Construct reinforcement drilling and grouting at the advanced position of the working face; Oblique drilling is carried out in the middle of the coal seam, and quick-setting material is used for grouting to reinforce the coal wall of the working face.

2. The grouting reinforcement method for the broken roof and structural area of the three-soft coal seam according to claim 1 is characterized in that: The crack distribution characteristic information includes: crack azimuth, crack aperture and crack connectivity; determining the grouting area range based on the crack distribution characteristic information; The drilling arrangement includes drilling spacing, drilling depth and drilling angle.

3. The grouting reinforcement method for the broken roof and structural area of the three-soft coal seam according to claim 1 is characterized in that: The construction of the layer-wise drilling adopts a staged drilling method, including: The first stage uses large-diameter drilling and casing; The second stage uses a drill bit smaller than the inner diameter of the casing to continue drilling to the designed depth.

4. The grouting reinforcement method for the broken roof and structural area of the three-soft coal seam according to claim 1 is characterized in that: The arrangement of the reinforcement drilling holes is determined according to the following parameters: geological structural parameters, including fault strikes and fold axis trace distribution; Parameters of the grouting target layer, including layer position and dip; Working face parameters, including advance speed, advance direction and mining height.

5. The grouting reinforcement method for the broken roof and structural area of the three-soft coal seam according to claim 4 is characterized in that: The reinforcement drill holes are arranged in a fan shape, including: determining a starting angle and an ending angle; determining the drill hole spacing according to geological conditions; and extending the end hole position to the rear of the fault plane.

6. The grouting reinforcement method for the broken roof and structural area of the three-soft coal seam according to claim 1 is characterized in that: The oblique drill holes are substantially perpendicular to the coal wall spalling fissures and extend to the coal seam roof.

7. The grouting reinforcement method for the broken roof and structural area of three-soft coal seams according to claim 1 is characterized in that: It also includes grouting quality control steps: constructing inspection holes at preset intervals between directional drill holes; collecting core samples for compressive strength testing; and evaluating the grouting filling effect through sonic testing.

8. The grouting reinforcement method for the broken roof and structural area of three-soft coal seams according to claim 1 is characterized in that: The directional drilling adopts a "belt, feather, and net" arrangement to form a net-like reinforcement structure on the coal seam roof.

9. The grouting reinforcement method for the broken roof and structural area of three-soft coal seams according to claim 1 is characterized in that: The arrangement characteristics of the reinforcement drill holes are: intersecting the fault and fold axis traces at a large horizontal angle in the plane; Make the nearly horizontal drill hole along the layer contact with the interlayer structural surface and intersect with the direction of the maximum horizontal principal stress.

10. The grouting reinforcement method for the broken roof and structural area of three-soft coal seams according to any one of claims 1 to 9, characterized in that: The final hole position of the reinforcement drilling extends horizontally to 3-5 meters from the fault surface.

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