Directional mining separation layer targeted filling construction method suitable for southwest mountainous region

Abstract

The invention discloses a directional mining separation layer targeted filling construction method suitable for southwest mountainous regions, and relates to the technical field of coal mine mining separation layer grouting filling. The method comprises the steps that the spatial position, stratum lithology and geological parameters of a mining separation layer are obtained through exploration, a drilling starting point is determined in a mountain bottom smooth area based on the exploration parameters, and a horizontal directional hole is constructed to a preset area above the mining separation layer; directional steering is carried out at the tail end of the horizontal directional hole, a vertical grouting hole is constructed to the mining separation layer core filling position, and a vertical grouting hole channel composed of a horizontal section and a vertical section is formed; and targeted grouting filling is conducted on the mining separation layer through the vertical grouting hole channels, and the hole channels are blocked after grouting is completed. The vertical grouting hole channel structure is adopted to adapt to the southwest mountain terrain, accurate targeted filling of the mining separation layer is achieved, the high slope operation risk is avoided, the pore-forming rate and efficiency are improved, coal gangue-fly ash composite slurry is utilized, solid waste is recycled, and the coal resource recovery rate is increased.

Description

Technical Field

[0001] This invention relates to the field of coal mine mining delamination grouting and filling technology, specifically a directional mining delamination targeted filling construction method suitable for mountainous areas in Southwest China. Background Technology

[0002] Southwest my country is rich in coal resources, but most mining areas are located in mountainous regions with steep terrain and complex geological conditions. To achieve safe and green coal mining, effectively control surface subsidence caused by coal mining, protect surface buildings and the ecological environment, and release coal resources buried under structures, railways, and water bodies, mining-induced delamination grouting and filling technology has become a key method. This technology involves injecting filling grout into the delamination space created in the overlying strata after coal seam mining to support the overlying rock, thereby slowing down or preventing subsidence from reaching the surface.

[0003] Currently, the mainstream mining-induced delamination grouting and filling technology originated and matured primarily in the flat plain mining areas of North and East China. The conventional approach involves drilling a vertical borehole at the designed location on the surface, penetrating the overlying rock to the target delamination, and then grouting through this borehole. However, directly applying this traditional technology to the mountainous mining areas of Southwest China faces a series of severe challenges and exhibits significant technical incompatibility, mainly manifested in the following ways: Significant terrain limitations: The mining area is mostly steep mountains with slopes generally exceeding 35°. There are no flat working areas on the ground. Traditional vertical grouting drilling on the ground requires the construction of high slope working platforms, which is difficult to carry out and has high safety risks (slope collapse and equipment falling are likely to occur). Moreover, the cost of site leveling accounts for more than 40% of the total construction cost.

[0004] Complex geological conditions: Mining areas in the southwestern mountainous region are often accompanied by the coexistence of fractured water-rich strata, red clay layers, and sand and gravel layers. Mining delamination is irregularly developed (with large differences in delamination thickness and scattered spatial distribution). Conventional straight or inclined hole grouting is difficult to accurately reach the core area of ​​the delamination, which easily leads to "grouting blind spots" or "grout waste".

[0005] Low construction efficiency: Mountainous terrain makes transportation difficult, large drilling equipment is hard to transport, traditional drilling techniques require multiple points of dispersed construction, the flexibility of hole position adjustment is low, and broken strata are prone to hole collapse and drill jamming, resulting in a hole completion rate of less than 60%, which seriously affects the construction progress.

[0006] Therefore, this invention proposes a directional mining-induced delamination targeted filling construction method suitable for the mountainous areas of Southwest China. Summary of the Invention

[0007] The purpose of this invention is to provide a directional mining delamination targeted filling construction method suitable for the mountainous areas of Southwest China. It adopts a vertical grouting channel structure of "horizontal section at the bottom of the mountain + vertical grouting section". The horizontal section avoids the steep terrain of the mountainous area, and the vertical section precisely targets the delamination, thus solving the dual adaptation problem of terrain and geology in the mountainous areas of Southwest China.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for targeted backfilling of delamination caused by directional mining in the mountainous areas of Southwest China, comprising the following steps: The spatial location, lithology, and geological parameters of the mining-induced delamination layer are obtained through surveying. Based on the surveyed parameters, the starting point for drilling is determined in a gentle area at the bottom of the mountain. Horizontal directional holes are drilled to a predetermined area above the mining-induced delamination layer, with the end of the horizontal directional holes located 50-500m directly above the mining-induced delamination layer. Directional turning is performed at the end of the horizontal directional hole, and vertical grouting holes are constructed to the core filling position of the mining-induced delamination layer, forming a vertical grouting channel composed of horizontal and vertical sections; Targeted grouting is performed into the mining-induced separation layer through the vertical grouting channels, and the channels are sealed after grouting is completed. The drilling process of the horizontal directional hole and the vertical grouting hole is monitored in real time by a drilling measurement system, and the horizontal to vertical steering control is achieved by a directional steering device.

[0009] Furthermore, the gently sloping area at the bottom of the mountain has a slope of ≤15° and is 100-500m away from the horizontal projection distance of the mining-induced absorptive layer.

[0010] Furthermore, the spatial location of the mining-induced delamination layer includes the burial depth, horizontal distribution range, and core filling area; The geological lithology includes the distribution of fracture zones and the location of aquifers; The geological parameters include rock compressive strength, porosity, and permeability coefficient.

[0011] Furthermore, the length of the horizontal directional hole is 100-500m, the trajectory slope is 0-3°, and the construction steps of the horizontal directional hole are as follows: (41) The two-step method of “guided drilling + hole reaming” is adopted. The PDC directional drill bit is selected. The drilling trajectory is monitored in real time through the drilling measurement system and corrected every 5m to ensure that the end of the horizontal section accurately reaches the predetermined elevation above the mining separation layer, and the trajectory deviation is ≤±1m. (42) During drilling, mud is injected synchronously, and casing is installed in the broken strata section. The casing joint is sealed by welding to prevent mud leakage. After drilling is completed, the hole is washed with high pressure water to remove rock cuttings.

[0012] Furthermore, the length of the vertical grouting hole is 50-500m, and the verticality deviation is ≤±2°. The specific construction steps for the vertical grouting hole are as follows: (51) Directional steering treatment: Install a directional steering device at the end of the horizontal directional hole, and adjust the drilling torque to change the drilling direction from horizontal to vertical downward; (52) Vertical section drilling: Use roller cone or PDC drill bit for vertical drilling. During the drilling process, the verticality is monitored in real time by the drilling measurement system and corrected every 3m to ensure that the end of the vertical section accurately penetrates the core area of ​​the mining separation layer. Drilling is stopped after reaching the predetermined depth.

[0013] Furthermore, the grout used for grouting is a coal gangue-fly ash composite grout or a fly ash grout, wherein the proportion of the coal gangue-fly ash composite grout is: The composition consists of 40%-60% coal gangue powder, 20%-40% fly ash, 65%-85% water, and 1%-3% activator.

[0014] Furthermore, when performing targeted grouting and filling into the mining-induced detachment, grouting pipes with a diameter of 73-108mm are installed into vertical grouting channels, with the end of the grouting pipe placed inside the mining-induced detachment.

[0015] Furthermore, the grout mix ratio is adjusted according to geological parameters during grouting: For fractured, water-rich formations: the slurry water-cement ratio is 1:0.8-1:1, with 5%-10% expansion agent added; For conventional formations: the water-cement ratio of the slurry is 1:1 to 1:1.2.

[0016] Furthermore, after grouting is completed, high-strength cement grout is used to seal the entire duct section, and multiple ground settlement observation points are set up in the construction area to monitor settlement and verify the filling effect.

[0017] Furthermore, the hole wall stabilization treatment of the horizontal directional hole adopts a combination of "casing + chemical slurry wall stabilization", wherein the chemical slurry is a cement-water glass two-liquid slurry with a setting time of 30-60s; 5%-8% bentonite is added to the mud of water-rich formations.

[0018] This invention has at least the following beneficial effects: 1. Regarding adaptability to complex terrain, this invention adopts an inverted vertical grouting channel structure of "bottom-mountain drilling, horizontal directional extension, and vertical targeted puncture," avoiding the problem of traditional vertical drilling requiring the construction of high-slope operation platforms on steep mountains. By setting up the drilling site in a gentle area at the bottom of the mountain, the difficulties of transporting and positioning large equipment in mountainous terrain with slopes exceeding 35 degrees are completely solved, significantly reducing major safety risks such as slope collapse and equipment overturning. At the same time, it avoids large-scale site leveling and support engineering, greatly reducing auxiliary engineering investment and ecological disturbance, and achieving a deep adaptation of construction technology to the terrain of southwestern mountains.

[0019] 2. Regarding the accuracy of filling the excavated layer, this invention accurately reaches the predetermined area above the excavated layer through a horizontal directional section, and then uses a vertical section to pierce to the core position of the excavated layer, forming a precise grouting channel that directly reaches the target area. This effectively overcomes the technical difficulties of irregular development and scattered spatial distribution of the excavated layer caused by the complex geological structure in the southwestern mountainous areas, and solves the problems of grouting blind spots and ineffective diffusion of grout that are common in traditional straight hole or inclined hole processes.

[0020] 3. Regarding applicability to complex geological conditions, this invention addresses the common characteristics of fractured water-rich strata, red clay layers, and alternating layers of sand and gravel in the mountainous regions of Southwest China. It employs a combined borehole wall stabilization technology of "casing + chemical slurry wall stabilization," which rapidly consolidates the fractured surrounding rock using a cement-water glass dual-liquid slurry. Furthermore, it optimizes the properties of bentonite slurry in water-rich strata, effectively solving construction problems such as borehole collapse, stuck drill bit, and slurry leakage, and significantly improving the borehole success rate and borehole integrity.

[0021] 4. In terms of construction efficiency and economy, this invention integrates traditional scattered multi-point grouting operations into single-hole targeted construction through integrated directional construction technology, reducing the total number of boreholes and the number of equipment relocations. The flexible layout of horizontal directional holes makes hole position adjustment more convenient, significantly shortening the exploration and construction preparation cycle. At the same time, the overall construction process, from drilling, wall stabilization, and turning to grouting and sealing, is seamlessly connected, reducing intermediate links and time losses, and greatly improving construction efficiency.

[0022] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the method described in this invention; Figure 2 This is a schematic diagram of the vertical grouting channel of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0025] The objective of this invention is: Overcoming the limitations of the mountainous terrain in Southwest China: By designing a vertical grouting channel with "hole opening at the bottom of the mountain + horizontal directional extension + vertical targeted puncture", the design avoids the difficulties of ground operations on steep mountains, eliminates the need to build high slope operation platforms, and reduces construction safety risks and site costs.

[0026] Achieve precise targeted filling of the exfoliated layer during mining: By using horizontal directional holes to accurately reach the predetermined area above the exfoliated layer, and then vertically piercing downwards to the core position of the exfoliated layer, the problem of filling blind spots caused by irregular exfoliated layer development is solved, and the slurry utilization rate is improved.

[0027] Adapted to complex geological conditions in Southwest China: For fractured and water-rich strata, the borehole wall stabilization technology and slurry ratio are optimized to improve the borehole formation rate and filling effect, and reduce the risk of borehole collapse and slurry leakage.

[0028] Improve construction efficiency and economy: reduce equipment transportation and site leveling work, reduce the number of boreholes through integrated directional construction, shorten the construction period, and reduce overall construction costs.

[0029] Please see Figures 1-2 This invention provides a technical solution: a method for targeted filling of delamination caused by directional mining in the mountainous areas of Southwest China, comprising the following steps: Step 1: Pre-construction survey and scheme design 1.1 Topographic and Geological Survey: Determine the gently sloping area at the bottom of the mountain as the starting point for drilling through topographic mapping, at a distance of 100-500m from the horizontal projection of the mining-induced delamination; ascertain the spatial location (depth, horizontal distribution range, core filling area), lithology (distribution of fractured zones, location of aquifers), and geological parameters (rock compressive strength, porosity, permeability coefficient) of the mining-induced delamination. Specifically, the key parameters that need to be obtained in the preliminary survey include: Spatial location of mining-induced delamination: Through numerical simulation, borehole exploration and microseismic monitoring, the burial depth of the delamination, its distribution range in the horizontal direction, and the "core filling area" with the largest voids and the greatest need for filling are determined. Stratigraphy and lithology: Investigate in detail the distribution of weak interlayers, faults, fracture zones and other "fracture zones" in the rock strata above and below the delamination, as well as the location, thickness and water-bearing capacity of aquifers (such as sandstone aquifers); Geological parameters: By using core experiments or well logging data, the uniaxial compressive strength, porosity, permeability coefficient, etc. of key rock strata are obtained. These parameters are the basis for designing drilling technology, selecting drill bits, and determining grout mix ratio and injection pressure. Based on the survey data, the starting point for drilling is determined in the gentle terraces or valleys with a slope of ≤15° at the bottom of the mountain. This point must meet the following requirements: ① The horizontal projection distance from the mining-induced delamination layer is 100-500m, ensuring that the length of the horizontal section is within the capacity of the directional drilling rig; ② It avoids fault fracture zones and karst development areas; ③ It has the conditions for equipment transportation and drilling site construction. 1.2 Grouting Channel Design: Based on the survey results, the parameters for the vertical grouting channel are designed as follows: Horizontal directional section: 216mm in diameter, 100-500m in length, 0-3° in slope, with the end located 50-500m directly above the mining delamination layer, and the trajectory avoids large fracture zones and aquifers; Vertical grouting section: 152mm in diameter, 50-500m in length, vertical deviation ≤±2°, end reaching the grouting area involved in the mining separation; 1.3 Material and Equipment Selection: Drilling equipment: A fully hydraulic horizontal directional drilling rig (torque ≥300kN・m, guiding accuracy ±0.5°) is selected to meet the needs of mountain transportation; Borehole wall stabilizing materials: For fractured, fissure-prone borehole sections, a "casing + chemical grout wall stabilization" scheme is adopted. First, the casing is installed for mechanical support. Then, cement-water glass dual-liquid grout is injected into the annular gap between the casing and the borehole wall, or into the fractured zone below the casing shoe. The setting time of this dual-liquid grout can be controlled within 30-60 seconds. It can quickly cement the fractured rock blocks to form a solid artificial borehole wall. For water-rich strata, bentonite (5%-8% admixture) is added to optimize the mud performance. Grouting materials: fly ash slurry or coal gangue-fly ash composite slurry (coal gangue particle size 100-200 mesh, fly ash content 30%-40%) can be selected to meet the needs of solid waste resource utilization in Southwest China.

[0030] Step 2: Construction and trajectory control of horizontal directional holes at the bottom of the mountain 2.1 Pre-treatment of the starting point: Excavate the drilling site (6m long × 6m wide × 1.5m deep) in a flat area at the bottom of the mountain, and pour a C30 concrete foundation (30cm thick) to ensure the stability of the drilling rig operation; 2.2 Horizontal directional drilling: The two-step method of "guided drilling + hole reaming" is adopted. The drill bit is a PDC directional drill bit (diameter 216mm). The drilling trajectory is monitored in real time by the measurement while drilling (MWD) system and corrected every 5m to ensure that the end of the horizontal section accurately reaches the predetermined elevation above the mining separation layer, with a trajectory deviation of ≤±1m. 2.3 Hole wall stabilization treatment: During drilling, mud (viscosity 25-30s) is injected simultaneously. Casing (material is geological casing, wall thickness 8-10mm) is installed in the fractured strata section. The casing joints are sealed by welding to prevent mud leakage. After drilling is completed, the hole is flushed with high-pressure clean water to remove rock cuttings. In this embodiment, a 216mm diameter geological casing is installed in the fractured strata. The casing is made of J55 grade steel with a wall thickness of 8-10mm and a single length of 3m. The joints are bevel-welded, and the welds are subjected to ultrasonic testing to ensure sealing. After the casing is installed, the borehole is flushed with high-pressure clean water (5-8MPa) for 30 minutes until the sand content of the returned fluid is <0.5%. Step 3: Directional Construction of Vertical Grouting Holes 3.1 Directional Steering: A mechanical directional steering device is installed at the end of the horizontal borehole. This device consists of a 2° bend joint, a directional key, and a locking mechanism. During steering, the drill string directional key is inserted into the keyway of the steering device. The tool face angle is adjusted to the designed orientation using the drilling rig's high-side positioning function. Then, 10-15 kN of pressure is applied to deflect the drill bit along the bend direction, achieving steering. The length of the steering section is controlled at 3-5 m. After steering is completed, MWD measurements confirm that the well inclination angle is >85°, and then vertical drilling begins. 3.2 Vertical Section Drilling: Use a 152mm diameter PDC drill bit or a tricone drill bit (tooth type TCI), with a drilling pressure of 30-50kN, a rotation speed of 80-120rpm, and a mud discharge rate of 800-1200L / min. Upload well inclination data every 3m using the MWD (Mean Down Difference) tool. If the well inclination angle deviation is >2°, use a pendulum drill string assembly for correction. The final position of the vertical section must meet the following requirements: ① Enter the core area of ​​the abscission zone (the thickest part of the abscission); ② Be at least 2m from the top of the formation to ensure effective mud diffusion; ③ Ensure the bottom of the borehole is intact to prevent mud leakage to deeper parts. Step 4: Targeted grouting and filling construction 4.1 Grouting pipe installation: The grouting pipe (73-108mm in diameter) is lowered into the vertical grouting channel, with the end placed inside the mining separation layer. For the technical solution of this embodiment, the grouting pipe adopts a geological drill rod with a diameter of 89mm, steel grade DZ50, wall thickness of 6.5mm, single length of 3m, threaded connection, and pressure sensor and flow sensor installed on the upper part of the grouting pipe column to monitor the grouting parameters in real time; 4.2 Slurry preparation: For fractured and water-rich formations: the water-cement ratio of the slurry is 1:0.8-1:1, which is the weight ratio of water to dry material (coal gangue powder + fly ash), with 10% expansion agent (UEA) added to improve impermeability; for conventional formations: the water-cement ratio of the slurry is 1:1-1:1.2, and the amount of expansion agent is reduced to 5%.

[0031] The proportion of the coal gangue-fly ash composite slurry is as follows: Coal gangue powder 40%-60%, fly ash 20%-40%, water 65%-85%, activator 1%-3%; 4.3 Staged Grouting Control: The "low-pressure start-up - gradual pressure increase - stable pressure filling" mode is adopted. Grouting pressure control: The grouting pressure should not be less than the natural ground pressure of the strata above the grouting filling layer, nor greater than the water-tightening pressure of the rock strata from the grouting filling layer to the mining face. In actual construction, surface settlement can be controlled by controlling the grouting pressure p_hole at the top of the grouting filling borehole. P 孔 =P 注 -H 1γ1g ≥P 地 -H 1γ1g = H 1（γ-γ1） g In the formula: P 孔 —Grouting orifice pressure, MPa; H1—Depth of the borehole from the surface to the grouting layer, in meters; taken as 100 meters. γ—Comprehensive specific gravity of the strata above the grouting filling layer, kg / m³ 3 ; γ1—Specific gravity of the filling grout, kg / m³ 3 ; The initial pressure is 0-1 MPa, and then the pressure is gradually increased; grouting ends when the grouting pressure reaches the design value and stabilizes.

[0032] 4.4 Hole Sealing: After grouting is completed, the grouting pipe is raised to the borehole opening, and the entire borehole section is sealed using the full-section grouting method. The sealing grout is PO 42.5 pure cement grout with a water-cement ratio of 1:0.8, with 2% early-strength agent added. The grouting pressure is 2MPa, and the grouting volume is calculated to fill the entire borehole section. After grouting, the grout is cured for 7 days until the strength reaches more than 20MPa.

[0033] Step 5: Construction effect inspection Settlement observation points were set up in a 50m×50m grid in the grouting affected area. Second-order leveling was used, and the monitoring period was 3 months before grouting and 6 months after grouting. The monitoring data showed that the daily settlement rate of the ground surface after grouting was <0.01mm / d and the cumulative settlement was <30mm, which met the qualified standard.

[0034] In summary, this invention sets up a drilling starting point in a gentle area at the bottom of a mountain in southwestern China. First, a horizontal directional hole is constructed to a predetermined elevation above the mining-induced delamination layer. Then, a vertically downward grouting hole is constructed from the end of the horizontal directional hole to the core filling position of the mining-induced delamination layer, forming an inverted L-shaped directional channel with a "horizontal section + vertical section". Finally, targeted grouting and filling are carried out through this channel.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on," "mounted on," "fixed to," or "set on" another element, it may be directly on the other element or there may be an intermediate element present. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible embodiments.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0038] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A method for targeted filling of delamination caused by directional mining in the mountainous areas of Southwest China, characterized in that, Includes the following steps: The spatial location, lithology, and geological parameters of the mining-induced delamination layer are obtained through surveying. Based on the surveyed parameters, the starting point for drilling is determined in a gentle area at the bottom of the mountain. Horizontal directional holes are drilled to a predetermined area above the mining-induced delamination layer, with the end of the horizontal directional holes located 50-500m directly above the mining-induced delamination layer. Directional turning is performed at the end of the horizontal directional hole, and vertical grouting holes are constructed to the core filling position of the mining-induced delamination layer, forming a vertical grouting channel composed of horizontal and vertical sections; Targeted grouting is performed into the mining-induced separation layer through the vertical grouting channels, and the channels are sealed after grouting is completed. The drilling process of the horizontal directional hole and the vertical grouting hole is monitored in real time by a drilling measurement system, and the horizontal to vertical steering control is achieved by a directional steering device.

2. The method for targeted filling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 1, is characterized in that: The gently sloping area at the bottom of the mountain has a slope of ≤15° and is 100-500m away from the horizontal projection of the mining-induced absorptive layer.

3. The method for targeted filling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 2, is characterized in that: The spatial location of the mining-induced delamination layer includes the burial depth, horizontal distribution range, and core filling area; The geological lithology includes the distribution of fracture zones and the location of aquifers; The geological parameters include rock compressive strength, porosity, and permeability coefficient.

4. A method for targeted backfilling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 2, is characterized in that: The horizontal directional borehole has a length of 100-500m and a trajectory slope of 0-3°. The specific construction steps for the horizontal directional borehole are as follows: (41) The two-step method of "guided drilling + hole reaming" is adopted. The PDC directional drill bit is selected. The drilling trajectory is monitored in real time through the drilling measurement system and corrected every 5m to ensure that the end of the horizontal section accurately reaches the predetermined elevation above the mining separation layer, and the trajectory deviation is ≤±1m. (42) During drilling, mud is injected synchronously, and casing is installed in the broken strata section. The casing joint is sealed by welding to prevent mud leakage. After drilling is completed, the hole is washed with high pressure water to remove rock cuttings.

5. A method for targeted filling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 4, is characterized in that: The length of the vertical grouting hole is 50-500m, and the verticality deviation is ≤±2°. The specific construction steps for the vertical grouting hole are as follows: (51) Directional steering treatment: Install a directional steering device at the end of the horizontal directional hole, and adjust the drilling torque to change the drilling direction from horizontal to vertical downward; (52) Vertical section drilling: Use roller cone or PDC drill bit for vertical drilling. During the drilling process, the verticality is monitored in real time by the drilling measurement system and corrected every 3m to ensure that the end of the vertical section accurately penetrates the core area of ​​the mining separation layer. Drilling is stopped after reaching the predetermined depth.

6. A method for targeted backfilling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 5, is characterized in that: The grout used for grouting is either a coal gangue-fly ash composite grout or a fly ash grout, wherein the proportion of the coal gangue-fly ash composite grout is as follows: 40%-60% coal gangue powder, 20%-40% fly ash, 65%-85% water, and 1%-3% activator.

7. A method for targeted filling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 6, is characterized in that: When performing targeted grouting and filling into the mining-induced detachment, grouting pipes with a diameter of 73-108mm are installed into vertical grouting channels, with the end of the grouting pipe placed inside the mining-induced detachment.

8. A method for targeted filling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 7, is characterized in that: Adjust the grout mix ratio according to geological parameters during grouting: For fractured, water-rich formations: the slurry water-cement ratio is 1:0.8-1:1, with 5%-10% expansion agent added; For conventional formations: the water-cement ratio of the slurry is 1:1 to 1:1.

2.

9. A method for targeted backfilling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 8, is characterized in that: After grouting, high-strength cement grout was used to seal the entire duct section, and multiple ground settlement observation points were set up in the construction area to monitor settlement and verify the filling effect.

10. A method for targeted filling of delamination caused by directional mining in mountainous areas of Southwest China, as described in claim 4, characterized in that: The hole wall stabilization treatment of the horizontal directional hole adopts a combination of "casing + chemical grout wall stabilization", wherein the chemical grout is a cement-water glass two-liquid grout with a setting time of 30-60s; 5%-8% bentonite is added to the mud of water-rich formations.

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