Drilling pressure relief method capable of preventing hole collapse and continuously discharging coal dust
By installing sleeves and fiber optic gratings for stress monitoring inside the borehole, combined with multi-stage treatment measures, the problems of borehole collapse and inability to remove coal dust were solved, achieving continuous pressure relief of the borehole and stability of the roadway.
Patent Information
- Application Number
- CN202511762448.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-27
- Publication Date
- 2026-02-24
AI Technical Summary
Existing borehole pressure relief methods are prone to borehole collapse after construction and coal dust cannot be continuously discharged, resulting in the failure of pressure relief and affecting the stability of the roadway.
Sleeves are installed inside the borehole. The sleeves in the plastic zone provide support and pressure relief, while the sleeves in the elastic zone have a hollow structure. Combined with fiber optic stress monitoring and multi-stage treatment measures, this ensures continuous discharge of coal dust and effective pressure relief.
It effectively prevents the collapse of pressure relief boreholes, maintains the stability of the borehole shape, enables the continuous discharge of coal dust, and ensures the stability of roadways during coal mining.
Smart Images
Figure CN121556854A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rockburst prevention technology, specifically a drilling pressure relief method for continuously discharging coal dust from anti-collapse boreholes. Background Technology
[0002] Drilling for stress relief is the most common method for preventing rockbursts in coal mine production. It is typically arranged perpendicular to the axial direction of the roadway in high-stress areas. After drilling into the coal seam on both sides of the roadway, a destructive zone forms around the borehole. During drilling into the high-stress area, coal dust is discharged from the borehole, thus relieving stress. However, after drilling is completed, subsequent mining damage to the coal seam and the continuous entry of coal dust into the borehole due to surrounding stress often cause the stress-relieving borehole to collapse. It may also become blocked by coal dust, leading to recompaction of the coal seam in the borehole area, loss of its stress-relieving effect, and reduced roadway stability due to the collapse.
[0003] Therefore, the research direction of this invention is to provide a new drilling pressure relief method that can prevent the collapse of the pressure relief borehole and the inability to discharge coal dust after drilling is completed, and to achieve a continuous pressure relief effect on the required pressure relief area by maintaining the shape stability of the pressure relief borehole and the continuous discharge of coal dust. This will ultimately ensure the stability of the roadway during coal mining. Summary of the Invention
[0004] To address the problems existing in the prior art, the present invention provides a drilling pressure relief method for continuously discharging coal dust from anti-collapse holes, which can effectively solve the problems existing in the prior art.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a drilling pressure relief method for continuously discharging coal dust from anti-collapse holes, comprising the following steps: Step 1: Drilling: Determine the location of the roadway borehole based on the impact hazard zone and its classification in front of the coal seam working face, and drill pressure relief boreholes at the locations. After completion, leave the boreholes to stand for a period of time to allow the coal dust in the current period to be discharged.
[0006] Step 2: Installing Sleeves: First, determine the range of the plastic and elastic zones of the coal and rock mass surrounding the roadway, and identify the corresponding borehole sections in the plastic and elastic zones for the pressure relief boreholes. Then, install sleeves into the pressure relief boreholes. The sleeves in the plastic zone borehole sections have no openings on their sides to support the pressure relief boreholes. The sleeves in the elastic zone borehole sections have perforated structures on their sides to allow coal and rock mass in that area to continuously transport coal dust into the pressure relief boreholes through the perforated structures and discharge it through the pressure relief boreholes to achieve continuous pressure relief.
[0007] Step 3: Monitor Sleeve Pressure: The sleeve surface within the elastic zone in Step 2 is equipped with a fiber optic grating stress monitoring system to monitor the circumferential and axial stresses of the sleeve, thereby determining the stress relief effect of the pressure relief borehole on the surrounding coal and rock mass. A warning indicator is set. If the monitored circumferential and axial stresses do not reach the warning indicator after calculation, stress monitoring continues and the process proceeds to Step 5. If the monitored circumferential and axial stresses reach the warning indicator after calculation, the process proceeds to Step 4.
[0008] Step 4: Coal dust discharge and pressure relief treatment: Take measures to promote the rapid discharge of coal dust from the borehole until the monitored stress value is reduced to below the warning index, thus completing the pressure relief treatment process.
[0009] Step 5: Continuous mining of the coal seam: Mining of the coal seam continues until the working face advances to the position of the pressure relief borehole. At this time, the inner sleeve of the borehole is removed, and steps one to four are repeated to carry out pressure relief work in the borehole in front of the current working face.
[0010] Furthermore, after the coal dust is discharged into the roadway in step one, a dust suction system is used to collect and clean the coal dust discharged from the borehole; this ensures that the coal dust will not affect the roadway.
[0011] Furthermore, in step two, the length of a single sleeve section is determined based on the site conditions, and it must ensure that the total length of all sleeves within the pressure relief borehole is the same as the length of the pressure relief borehole. This guarantees that the sleeves provide support for the entire length of the pressure relief borehole.
[0012] Furthermore, in step two, the sleeve with the hollow structure is a sleeve with evenly distributed through holes on its side surface. This structure facilitates the discharge of coal and rock debris from the elastic zone into the borehole, improving the pressure relief effect.
[0013] Furthermore, in step two, the sleeves within the pressure relief borehole are sequentially connected end-to-end with threads. This makes the sleeves form a single unit, facilitating vibration and rotation of the sleeves during subsequent processing.
[0014] Furthermore, in step three, the fiber optic stress monitoring system is a fiber optic grating. The sleeve surface has a groove, and the fiber optic grating is installed in the groove. One part of the fiber optic grating segment is used to monitor the circumferential stress of the sleeve, and another part of the fiber optic grating segment is used to monitor the axial stress of the sleeve. The fiber optic gratings between the sleeves are connected by pluggable fiber optic connectors to realize synchronous stress monitoring of different sleeves and the recycling of sleeves and fiber optic gratings.
[0015] Furthermore, the warning indicators in step three are specifically as follows: In the formula: The circumferential stress of the sleeve; The Poisson's ratio of the sleeve; This refers to the axial stress of the sleeve; It represents the uniaxial compressive strength of the coal and rock mass surrounding the roadway.
[0016] If the circumferential stress and axial stress of the monitoring sleeve are calculated using the above formula, and if they are less than 2.5, then it is determined that the warning indicator has not been met; if they are greater than or equal to 2.5, then it is determined that the warning indicator has been met.
[0017] Furthermore, in step four, treatment measures are adopted to promote the rapid removal of coal dust from the borehole. These measures are divided into four levels, which are performed sequentially, as follows: First stage: Use a dust extraction system to extract and clean the coal dust discharged into the borehole; if the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and proceed to step five; otherwise, proceed to the second stage.
[0018] Second stage: Use a steel chisel to clear the sleeve inside the pressure relief borehole to prevent coal dust from solidifying and clogging in areas with a large amount of coal dust discharge, so that the coal dust can be discharged from the pressure relief borehole quickly; if the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and then proceed to step five; otherwise, proceed to the third stage.
[0019] The third stage involves connecting the sleeve closest to the roadway to the vibration system within the roadway. The vibration system vibrates the sleeve, further weakening the coal body in the high-stress area through the vibration waves. This allows coal dust to enter the pressure relief borehole through the hollow structure and be continuously discharged from the pressure relief borehole under vibration, thus achieving continuous pressure relief. If the monitored stress value drops below the warning indicator after completion, it indicates that the pressure relief effect is good, and the process proceeds to the fifth stage; otherwise, the process proceeds to the fourth stage.
[0020] Level 4: Connect the sleeve closest to the roadway to the rotary machine. The rotary machine drives the sleeve to rotate inside the pressure relief borehole. The friction generated by the rotation between the sleeve and the pressure relief borehole weakens and relieves pressure on the coal and rock mass around the borehole. It also makes the contact between the sleeve and the coal and rock mass around the borehole more uniform and the stress distribution more uniform. This promotes the entry of coal dust into the pressure relief borehole from the hollow structure and its rapid discharge, achieving continuous pressure relief in the pressure relief borehole. If the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and then proceed to step 5; otherwise, proceed to level 1.
[0021] Compared with existing technologies, this invention first constructs pressure-relief boreholes and determines the borehole sections corresponding to the plastic and elastic zones. Then, sleeves are installed into the pressure-relief boreholes. The sleeves in the plastic zone sections have no openings on their sides to support the pressure-relief boreholes, which helps maintain the stability of the surrounding rock in the roadway and prevents further damage to the surrounding rock in the plastic zone, thus avoiding large deformations in the roadway. The sleeves in the elastic zone sections have perforated structures on their sides to allow coal and rock mass in that area to continuously transport coal dust into the pressure-relief boreholes and discharge it through the boreholes, achieving continuous pressure relief. This pressure-relief construction method... Subsequently, to prevent the collapse of the pressure relief borehole and the inability to discharge coal dust, the shape of the pressure relief borehole is kept stable and coal dust is continuously discharged, thereby achieving a continuous pressure relief effect on the required pressure relief area. In order to maintain the pressure relief effect, the stress on the surface of the sleeve is continuously monitored to determine the pressure relief effect of the pressure relief borehole on the surrounding coal and rock mass. By formulating early warning indicators, if the monitored stress data exceeds the early warning indicators after calculation, four-level treatment measures are adopted in sequence to promote the rapid discharge of coal dust from the borehole, thereby achieving the goal of continuously maintaining the pressure relief effect and ultimately ensuring the stability of the roadway during coal mining. Attached Figure Description
[0022] Figure 1 This is the overall flowchart of the present invention.
[0023] Figure 2 This is a schematic diagram of the plastic region and the elastic region in this invention.
[0024] Figure 3 This is a schematic diagram of the hollowed-out sleeve in this invention.
[0025] Figure 4 This is a schematic diagram of the reflection wavelengths of different numbered grating measurement points in this invention. Detailed Implementation
[0026] The present invention will be further described below.
[0027] like Figure 1 As shown, the present invention includes the following steps: Step 1: Drilling: Determine the location of the roadway borehole based on the impact hazard zone and level classification results in front of the coal seam working face, and construct a pressure relief borehole at the location. In this embodiment, the length of the pressure relief borehole is 20m. After completion, let the borehole stand still for a period of time to allow the coal dust in the current period to be discharged into the roadway. Then, use a dust suction system to collect and clean the coal dust discharged from the borehole. This ensures that the coal dust will not affect the roadway.
[0028] Step 2: Install the sleeves: such as Figure 2As shown, first, the range of the plastic zone and the range of the elastic zone of the coal and rock mass surrounding the roadway are obtained, and the borehole sections corresponding to the plastic zone and the elastic zone are determined respectively; then, sleeves are installed in the pressure relief boreholes, wherein the sleeves in the borehole sections in the plastic zone are not perforated on the side, and are used to support the pressure relief boreholes; as shown... Figure 3 As shown, the sleeve in the elastic zone of the borehole has a perforated structure on its side. This allows coal and rock mass in the area to continuously transport coal cuttings into the pressure relief borehole through the perforated structure, and then discharge them through the pressure relief borehole to achieve continuous pressure relief. The length of a single sleeve section is determined based on site conditions, and the total length of all sleeves within the pressure relief borehole must be the same as the length of the borehole itself. This ensures that the sleeves support the entire length of the pressure relief borehole. Each sleeve is connected end-to-end with threads. This makes the sleeves a single unit, facilitating vibration and rotation of the sleeves during subsequent treatment.
[0029] In this embodiment, the range of the plastic zone of the roadway is calculated using the following formula: Where: R is the radius of the plastic zone; a is the radius of the tunnel; p0 is the original rock stress; p i φ is the support resistance; φ is the internal friction angle of the coal body; c is the cohesion of the coal body.
[0030] Step 3: Monitor sleeve pressure: such as Figure 3 As shown, in step two, the sleeve surface within the elastic zone is equipped with a fiber optic grating stress monitoring system to monitor the circumferential and axial stresses of the sleeve, thereby determining the stress relief effect of the pressure-relieving borehole on the surrounding coal and rock mass. The fiber optic grating stress monitoring system is a fiber optic grating. The sleeve surface has grooves, and the fiber optic grating is installed within these grooves. One portion of the fiber optic grating segment is used to monitor the circumferential stress of the sleeve, and another portion is used to monitor the axial stress. The fiber optic gratings between sleeves are connected via pluggable fiber optic connectors, enabling synchronous stress monitoring of different sleeves and the cyclic use of sleeves and fiber optic gratings. The fiber optic grating measurement points at each sleeve are numbered, and the reflection center wavelengths of different numbered grating measurement points are different, thus enabling a quasi-distributed measurement method of multiple fiber optic gratings connected in series for strain measurement. Figure 4 As shown.
[0031] Set early warning indicators, specifically: In the formula: The circumferential stress of the sleeve; The Poisson's ratio of the sleeve; This refers to the axial stress of the sleeve; It represents the uniaxial compressive strength of the coal and rock mass surrounding the roadway.
[0032] If the circumferential stress and axial stress of the monitored sleeve are calculated using the above formula, and if they are less than 2.5, it is determined that the warning indicator has not been reached, and stress monitoring continues and the process proceeds to step five; if they are greater than or equal to 2.5, it is determined that the warning indicator has been reached, and the process proceeds to step four.
[0033] Step 4: Coal Dust Removal and Pressure Relief Treatment: Treatment measures are adopted to promote rapid removal of coal dust from the borehole. These measures are divided into four levels, and are implemented sequentially. Specifically: First stage: Use a dust extraction system to extract and clean the coal dust discharged into the borehole; if the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and proceed to step five; otherwise, proceed to the second stage.
[0034] Second stage: Use a steel chisel to clear the sleeve inside the pressure relief borehole to prevent coal dust from solidifying and clogging in areas with a large amount of coal dust discharge, so that the coal dust can be discharged from the pressure relief borehole quickly; if the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and then proceed to step five; otherwise, proceed to the third stage.
[0035] The third stage involves connecting the sleeve closest to the roadway to the vibration system within the roadway. The vibration system vibrates the sleeve, further weakening the coal body in the high-stress area through the vibration waves. This allows coal dust to enter the pressure relief borehole through the hollow structure and be continuously discharged from the pressure relief borehole under vibration, thus achieving continuous pressure relief. If the monitored stress value drops below the warning indicator after completion, it indicates that the pressure relief effect is good, and the process proceeds to the fifth stage; otherwise, the process proceeds to the fourth stage.
[0036] Level 4: Connect the sleeve closest to the roadway to the rotary machine. The rotary machine drives the sleeve to rotate inside the pressure relief borehole. The friction generated by the rotation between the sleeve and the pressure relief borehole weakens and relieves pressure on the coal and rock mass around the borehole. It also makes the contact between the sleeve and the coal and rock mass around the borehole more uniform and the stress distribution more uniform. This promotes the entry of coal dust into the pressure relief borehole from the hollow structure and its rapid discharge, achieving continuous pressure relief in the pressure relief borehole. If the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and then proceed to step 5; otherwise, proceed to level 1.
[0037] Step 5: Continuous mining of the coal seam: Mining of the coal seam continues until the working face advances to the position of the pressure relief borehole. At this time, the inner sleeve of the borehole is removed, and steps one to four are repeated to carry out pressure relief work in the borehole in front of the current working face.
[0038] As an improvement to this invention, the sleeve with a hollow structure in step two is a sleeve with uniformly distributed through holes on its side surface. This structure facilitates the discharge of coal and rock debris from the elastic zone into the borehole, improving the pressure relief effect. The stress monitoring device is a fiber optic sensor used to monitor the real-time stress at different locations on the sleeve surface. Using a fiber optic sensor not only ensures stable performance but also provides more accurate stress data.
[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A drilling pressure relief method for continuously discharging coal dust from anti-collapse boreholes, characterized in that, Includes the following steps: Step 1: Construction drilling: Determine the drilling location in the roadway based on the impact hazard zone and level classification results in front of the coal seam working face, and construct pressure relief drilling at the drilling location. After completion, let the drilling stand still for a period of time to allow the coal dust in the current period to be discharged. Step 2: Installing Sleeves: First, determine the range of the plastic and elastic zones of the coal and rock mass surrounding the roadway, and identify the corresponding borehole sections for the pressure relief boreholes in the plastic and elastic zones, respectively. Then, install sleeves into the pressure relief boreholes. The sleeves in the plastic zone borehole sections have no openings on their sides to support the pressure relief boreholes. The sleeves in the elastic zone borehole sections have perforated structures on their sides to allow the coal and rock mass in that area to continuously transport coal dust into the pressure relief boreholes through the perforated structures and discharge it through the pressure relief boreholes to achieve continuous pressure relief. Step 3: Monitor Sleeve Pressure: The sleeve surface within the elastic zone in Step 2 is equipped with a fiber optic grating stress monitoring system to monitor the circumferential and axial stresses of the sleeve, thereby determining the stress relief effect of the pressure relief borehole on the surrounding coal and rock mass. A warning indicator is set. If the monitored circumferential and axial stresses do not reach the warning indicator after calculation, stress monitoring continues and the process proceeds to Step 5. If the monitored circumferential and axial stresses reach the warning indicator after calculation, the process proceeds to Step 4. Step 4: Coal dust discharge and pressure relief treatment: Take measures to promote the rapid discharge of coal dust from the borehole until the monitored stress value is reduced to below the warning index, thus completing the pressure relief treatment process; Step 5: Continuous mining of the coal seam: Mining of the coal seam continues until the working face advances to the position of the pressure relief borehole. At this time, the inner sleeve of the borehole is removed, and steps one to four are repeated to carry out pressure relief work in the borehole in front of the current working face.
2. The drilling pressure relief method for continuously discharging coal dust from the anti-collapse hole according to claim 1, characterized in that, In step one, after the coal dust is discharged into the roadway, a dust suction system is used to collect and clean the coal dust discharged from the borehole.
3. The drilling pressure relief method for continuously discharging coal cuttings from the anti-collapse hole according to claim 1, characterized in that, In step two, the length of a single sleeve is determined based on the site conditions, and the total length of all sleeves within the pressure relief borehole must be the same as the length of the pressure relief borehole.
4. The drilling pressure relief method for continuously discharging coal dust from the anti-collapse hole according to claim 1, characterized in that, The sleeve with a hollow structure in step two is a sleeve with evenly distributed through holes on its side surface.
5. The drilling pressure relief method for continuously discharging coal dust from the anti-collapse hole according to claim 1, characterized in that, In step two, the sleeves inside the pressure relief borehole are connected end to end by threads.
6. The drilling pressure relief method for continuously discharging coal dust from the anti-collapse hole according to claim 1, characterized in that, In step three, the fiber optic stress monitoring system is a fiber optic grating. The sleeve surface has a groove, and the fiber optic grating is installed in the groove. One part of the fiber optic grating segment is used to monitor the circumferential stress of the sleeve, and another part of the fiber optic grating segment is used to monitor the axial stress of the sleeve. The fiber optic gratings between the sleeves are connected by pluggable fiber optic connectors to realize synchronous stress monitoring of different sleeves and the recycling of sleeves and fiber optic gratings.
7. The drilling pressure relief method for continuously discharging coal dust from the anti-collapse hole according to claim 1, characterized in that, The warning indicators in step three are specifically as follows: In the formula: The circumferential stress of the sleeve; The Poisson's ratio of the sleeve; This refers to the axial stress of the sleeve; The uniaxial compressive strength of the coal and rock mass surrounding the roadway; If the circumferential stress and axial stress of the monitoring sleeve are calculated using the above formula, and if they are less than 2.5, then it is determined that the warning indicator has not been met; if they are greater than or equal to 2.5, then it is determined that the warning indicator has been met.
8. The drilling pressure relief method for continuously discharging coal dust from the anti-collapse hole according to claim 1, characterized in that, In step four, treatment measures are adopted to promote the rapid removal of coal dust from the borehole. These measures are divided into four levels, which are performed sequentially: First stage: Use a dust extraction system to extract and clean the coal dust discharged into the borehole; if the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and proceed to step five; otherwise, proceed to the second stage. Second stage: Use steel chisels to clear the sleeve inside the pressure relief drill hole to prevent coal dust from solidifying and blocking in areas with a large amount of coal dust discharge, so that the coal dust can be discharged from the pressure relief drill hole quickly. If the monitored stress value drops below the warning level after completion, it indicates that the pressure relief effect is good, and proceed to step five; otherwise, proceed to level three. The third stage: Connect the sleeve closest to the roadway to the vibration system in the roadway. Vibrate the sleeve through the vibration system. Through the action of vibration waves, the coal body in the high stress area of the roadway is further weakened, so that coal dust enters the pressure relief borehole from the hollow structure and is continuously discharged from the pressure relief borehole by vibration, so as to achieve continuous pressure relief of the pressure relief borehole. If the monitored stress value drops below the warning level after completion, it indicates that the pressure relief effect is good, and proceed to step five; otherwise, proceed to level four. Level 4: Connect the sleeve closest to the roadway to the rotary machine. The rotary machine drives the sleeve to rotate inside the pressure relief borehole. The friction generated by the rotation between the sleeve and the pressure relief borehole weakens and relieves pressure on the coal and rock mass around the borehole. It also makes the contact between the sleeve and the coal and rock mass around the borehole more uniform and the stress distribution more uniform. This promotes the entry of coal dust into the pressure relief borehole from the hollow structure and its rapid discharge, achieving continuous pressure relief in the pressure relief borehole. If the monitored stress value drops below the warning index after completion, it indicates that the pressure relief effect is good, and then proceed to step 5; otherwise, proceed to level 1.