Floor roadway gas control method for replacing directional rock hole with extraction pipeline

Abstract

A floor roadway gas control method of directional rock hole replacing extraction pipeline, designs and constructs floor roadway directional rock hole extraction pipeline extraction system to carry out floor roadway gas control and extraction, and is carried out according to the following steps: (1) directional rock hole construction track parameter design and construction; (2) secondary correction of directional rock hole construction track parameters; (3) construction inclination angle calculation and construction adjustment of extraction branch hole; (4) extraction branch hole blocking and connection of extraction branch hole and single hole; (5) installation and monitoring of unit metering monitoring device; (6) design and construction of extraction pipeline water drainage device; (7) connection of the whole extraction system, and synchronous extraction is carried out along with working face recovery. The present application can realize "no pipeline, low cost and full cycle extraction" in the floor roadway, and reduce the engineering quantity of mine in aspects of extraction system installation, maintenance and removal, and improve the safety of mine gas extraction control effect and working face recovery.

Description

Technical Field

[0001] This invention relates to the field of gas extraction and control technology, specifically to a method for controlling gas in the bottom roadway using directional rock boreholes instead of extraction pipelines. Background Technology

[0002] Currently, laying PVC extraction pipelines remains the main method for gas extraction and control systems in my country. However, this technology often suffers from problems such as large-scale pipeline hanging work in the bottom roadway, excessive space and materials required for pipeline installation, time-consuming and labor-intensive installation and recovery of pipelines leading to high material recovery loss (recovery rate of screws, flange gaskets is less than 20%), and premature recovery of extraction pipelines (recovery when the working face begins mining) resulting in the inability to extract gas in the bottom roadway during the working face mining period, leading to high gas outflow in the return airflow. These are the problems that exist in the current gas extraction system using PVC pipelines in the bottom roadway.

[0003] However, when selecting floor roadway strata, mines currently consider factors such as "floor roadway deformation and instability" extensively. Therefore, methods such as selecting strata (by increasing rock pillars and choosing strata with stable lithology) and strengthening support (using a composite support system of anchor wire mesh and shotcrete) extend the service life of floor roadways and reduce deformation, especially on the roadway sidewalls where deformation is negligible. Meanwhile, mature directional drilling and borehole trajectory measurement technologies provide technical support for the possibility of using directional boreholes in floor roadways to replace extraction pipelines. Furthermore, the need for simultaneous gas control and power generation in floor roadways during mine face mining provides a broad market for this technology. Summary of the Invention

[0004] The purpose of this invention is to provide a method for gas control in the bottom roadway by replacing the extraction pipeline with directional rock boreholes. This invention mainly solves the problems of "large space occupation, low efficiency, high laying cost, difficult operation and maintenance, and inability to extract gas synchronously with the working face" that exist in the use of PVC extraction pipeline systems in the bottom roadway.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for gas control in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines is proposed. The method involves designing and constructing a directional rock borehole extraction system for the bottom roadway to control and extract gas. The steps are as follows: (1) Design and construction of the directional rock borehole trajectory parameters → (2) Secondary correction of the directional rock borehole trajectory parameters → (3) Calculation and adjustment of the inclination angle of the extraction branch holes → (4) Sealing of the extraction branch holes and connection of the extraction branch holes and single holes → (5) Installation and monitoring of the unit metering and monitoring devices → (6) Design and construction of the water discharge device for the extraction pipeline → (7) Completion of the connection of the entire extraction system and synchronous extraction during the working face recovery.

[0007] Step (1) is as follows:

[0008] (1.1) Design of construction trajectory parameters for directional rock boreholes:

[0009] The center of the roadway roof at the location of the first extraction support hole in the bottom roadway is taken as the starting point, and the starting point coordinates are marked as T1(X). T1 Y T1 Z T1 ), where X T1 =0、Y T1 =0、Z T1 =0, the direction along the centerline of the bottom roadway is Y, the left and right width of the bottom roadway is X, and the up and down direction is Z. Then, the coordinates of the center of the roadway roof are measured every 5m (assuming the spacing between boreholes in the bottom roadway is 5m). The coordinates of the nth measuring point are marked as Tn(X Tn Y Tn Z Tn Assuming the nth measuring point is located a meters to the left and b meters above the starting point, the coordinates of the nth measuring point are calculated as: X Tn =-a、Y Tn =5*n、Z Tn =b;

[0010] By shifting the coordinates Tn 8m to the left and right respectively (tunnel width + rock pillar thickness, the rock pillar thickness to be adjusted according to mine conditions or simulation), the construction trajectory coordinates D of the two directional rock boreholes on the left and right sides of the floor tunnel can be obtained. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En Construction trajectory coordinates D n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En The specific assignment details are as follows:

[0011] Coordinates D of the construction trajectory of the left directional rock borehole n :X Dn = X Tn -8、Y Dn = Y Tn Z Dn = Z Tn , that is, X Dn = -a-8、Y Dn =5*n、Z Dn = b;

[0012] Construction trajectory coordinates of the right-side directional rock borehole: En:X En = X Tn +8、Y En = Y Tn Z En = Z Tn , that is, X En = -a+8、Y En =5*n、Z En = b;

[0013] (1.2) Construction of directional rock boreholes:

[0014] Based on the trajectory settings of the directional drilling rig, the construction trajectory coordinates D of the two directional rock boreholes on the left and right sides of the bottom tunnel, as designed in (1.1), are determined. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En The directional drilling site is used as the construction trajectory parameter for the directional drilling rig. Since the first 30m of the directional drilling rig is the section for changing direction, the directional drilling site is set outward, 20m to 30m away from the first extraction branch hole, so that the directional drilling rig can reach the designed construction trajectory coordinates in the section for changing direction. One directional drilling site is constructed on each side of the bottom roadway. Then, the directional drilling site is constructed parallel to the excavation direction of the bottom roadway and at the top of the bottom roadway. The directional drilling site is constructed using a ϕ193mm drill bit.

[0015] After the directional rock borehole construction is completed and the working face meets the standards, the outer end of the directional rock borehole is connected to the extraction pipeline at the dedicated tunnel.

[0016] Step (2) is as follows: Since the construction of directional drilling is constantly being fine-tuned, the test data of the borehole trajectory measuring instrument is closer to the real situation. Therefore, the construction trajectory parameters of the directional rock hole in directional drilling are based on the test data of the borehole trajectory measuring instrument.

[0017] The drilling trajectory of two directional rock boreholes was measured using a borehole trajectory measuring instrument. The construction trajectory parameters of the directional rock boreholes were then calibrated twice, and the calibrated construction trajectory coordinate data were assigned to coordinate D. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En This completes the secondary correction of the construction trajectory parameters for directional rock boreholes.

[0018] Step (3) is as follows:

[0019] (3.1) Calculation of the construction inclination angle of the extraction support hole: Based on the construction trajectory parameters of the directional rock hole after secondary correction in step (2), and combined with the construction position marked on the site of the extraction support hole, the construction inclination angle of the extraction support hole is calculated by using the trigonometric function method.

[0020] The distances from the left and right extraction support holes to the top of the floor roadway are Lh and Rh, respectively. The width of the floor roadway is K. Then, the opening coordinates of the nth extraction support hole on the left are Ln(X). Ln Y Ln Z Ln ) and the opening coordinates Rn(X) of the nth extraction branch hole on the right. Rn Y Rn Z Rn The values ​​assigned to ) are as follows:

[0021] The opening coordinates Ln of the nth extraction support hole on the left: X Ln =X Tn -0.5*K, Y Ln =Y Tn Z Ln =Z Tn -Lh, then the construction inclination angle A of the nth extraction support hole on the left. Ln For: A Ln =arctan[Lh / (X Dn -X Ln )];

[0022] The opening coordinates Rn of the nth extraction support hole on the right: X Rn =X Tn +0.5*K, Y Rn =Y Tn Z Rn =Z Tn -Rh, then the construction inclination angle A of the nth extraction support hole on the right. Rn For: A Rn =arctan[Rh / (X Dn -X Rn )];

[0023] (3.2) Construction adjustment of the extraction support hole:

[0024] After marking the opening position and construction inclination of the extraction branch hole, a small-diameter exploratory hole (ϕ32mm) is first drilled at the opening position of the extraction branch hole in the bottom roadway using an anchor cable drilling rig. An end-of-hole inspection instrument is then inserted into the small-diameter exploratory hole to check the connection position with the directional rock hole. If the connection is not established, cement is injected to seal it tightly, and the opening position and construction inclination are finely adjusted. The small-diameter exploratory hole is then re-drilled until it connects with the directional rock hole. Based on the inspection results of the end-of-hole inspection instrument, the construction inclination is finely adjusted to place the connection position in the lower middle part of the directional rock hole wall to facilitate the drainage of drill cuttings and accumulated water in the directional rock hole. Then, a large-diameter (ϕ155mm) drill bit is used to expand the small-diameter extraction branch hole according to the final finely adjusted construction inclination until it connects with the directional rock hole.

[0025] Step (4) is as follows:

[0026] (4.1) Sealing of the extraction support hole:

[0027] The extraction branch pipe is used to seal the extraction branch hole. The extraction branch pipe is 7m long and is made of plastic hose with bags at both ends. The outer diameter of the extraction branch pipe is ϕ120mm~ϕ150mm. The inner bag is 1m~2m away from the directional rock hole with a diameter of Ϲ190mm. The outer bag is located 1m inward from the opening of the extraction branch hole. The extraction branch hole is sealed by "sealing at both ends + grouting in the middle". The grouting depth is not less than 5m to ensure the sealing of the grouting section of the extraction branch pipe.

[0028] (4.2) Connection between the extraction support hole and the single hole:

[0029] The outer end of the extraction branch pipe is connected to an extraction continuous tap, which is connected to at least 14 short connectors with an outer diameter of ϕ50mm. Each short connector is connected to the outer end of a single-hole sealing hose at the extraction branch hole location in the bottom tunnel for continuous extraction.

[0030] Step (5) is as follows: Taking the sub-unit metering and monitoring at the left side of the bottom plate roadway as an example, at every 200m (lower than the industry standard distance), construct two monitoring branches with appropriate spacing (meeting the requirements of the pipeline smooth section length before and after the sub-unit metering and monitoring device) to connect with the directional rock borehole. The construction method of the monitoring branches is the same as that of the extraction branches, and plastic hoses are used for sealing. Then, the sub-unit metering and monitoring device is installed in the bottom plate roadway. The two ends of the sub-unit metering and monitoring device are connected to the outer ports of the sealing pipes of the two monitoring branches respectively. Then, the directional rock borehole in the middle section of the two monitoring branches is blocked, so that the gas flow direction of the directional rock borehole is changed to "U-shaped" flow at the blocking point, and flows back into the directional rock borehole after passing through the sub-unit metering and monitoring device.

[0031] After the working face meets the standards, the sub-unit metering and monitoring device will be removed and recycled, and a plastic hose will be used to replace the sub-unit metering device to connect the blockage point of the directional rock borehole.

[0032] Step (6) is as follows: The extraction pipeline adopts the principle of "automatic negative pressure water release" to design the water release device. That is, the upward-angled water release branch hole is constructed at the U-shaped or V-shaped slope change low point and the unit metering and monitoring device of the directional rock hole. The construction method of the water release branch hole is the same as that of the extraction branch hole. The water release branch hole is connected to the directional rock hole. The water release branch hole is sealed with the extraction branch pipe. The outer end of the extraction branch pipe is connected to a water release hose through a connector. Then, a pump pit with a depth of not less than 1m is constructed in the bottom slab tunnel below the water release branch hole. A water bucket is placed in the pump pit. The height of the water bucket is not less than 1.5m. The water bucket is filled with water. The inner diameter of the water bucket is larger than the outer diameter of the water release hose. The lower end of the water release hose is placed in the water bucket. It can ensure a negative pressure of 20KPa in the directional rock hole. If the negative pressure in the directional rock hole is 30KPa or higher, the negative pressure is converted into the height of the water column and replaced with a water bucket of the corresponding height to realize automatic water release using the U-shaped pipe principle.

[0033] After the working face meets the standards and the evaluation is completed, the water discharge device will remain in the bottom tunnel and will not need to be retrieved.

[0034] Step (7) is as follows: After the above steps are completed, the directional rock borehole replacement extraction pipeline is completed, the connection of the entire extraction system is completed, and synchronous extraction can be carried out with the working face extraction.

[0035] The specific operation for sealing and blocking the directional rock borehole in step (5) is as follows: construct a through sealing branch hole at the location where the directional rock borehole needs to be sealed and blocked. The construction method of the sealing branch hole is the same as that of the extraction branch hole. Then, insert a bag into the sealing branch hole to the location where the directional rock borehole needs to be sealed and blocked. Then, inject grout or glue into the bag to seal and block the directional rock borehole at that location.

[0036] When rock column fissures caused by anchor bolts on the roadway sidewalls during the excavation of the bottom roadway penetrate directional rock boreholes, or when fissures formed by compression deformation at the shoulder of the bottom roadway later penetrate directional rock boreholes, it can lead to gas leakage in the rock column. A rock column refers to the rock mass between the roadway sidewalls and the directional rock boreholes. The method for handling gas leakage in the rock column is as follows:

[0037] (I) Proactive prevention: Increase the thickness of the rock pillar between the directional rock borehole and the sidewall of the bottom roadway. According to the borehole inspection and surrounding rock delamination deformation simulation, the rock pillar thickness of 8m can isolate the penetration of the crack, which is far beyond the length of the anchor bolt. The length of the anchor bolt is 3m to 5m.

[0038] (II) Passive treatment: When serious gas leakage occurs in the rock column, grouting holes are drilled behind the wall in the leakage area. The depth of the grouting holes behind the wall is 3m. With the leakage point as the center, high-pressure grouting is carried out at a distance of 1.5m above, below and to the left and right of the leakage point to seal and fill the surrounding rock fissures.

[0039] This invention possesses significant substantive features and remarkable progress compared to existing technologies. Specifically, it achieves a "pipeless design" for the gas extraction system in the bottom roadway through the construction of directional rock boreholes. It provides technical methods such as parameter design for extraction branch boreholes, detection methods for the connection between extraction branch boreholes and directional rock boreholes, installation of unit-based metering and monitoring devices for directional rock boreholes, continuous extraction of extraction branch boreholes and single boreholes, and water discharge configuration for the extraction system. These methods can ensure reduced extraction system costs, improved extraction system efficiency and lifespan, and enhanced gas control effects at the working face. Specific beneficial effects include: ① Directional rock boreholes completely replace extraction pipelines and can achieve the extraction concentration and flow rate required under current mine conditions. ① It meets various parameter measurement and water release requirements; ② It can extend the service life and efficiency of the bottom roadway drainage system, meet the goal of synchronous three-dimensional drainage during the working face mining, and reduce the gas concentration in the return airflow and the gas emission from the working face; ③ It greatly reduces the installation, dismantling costs and labor costs, as well as material losses and resource occupation of the mine using PVC drainage pipelines; ④ It reduces the maintenance cost of the bottom roadway drainage system, improves the sealing performance and gas extraction concentration of the drainage system, and provides a guarantee for mine gas power generation; ⑤ It greatly improves the standardization quality of the mine bottom roadway drainage system, reduces the space occupancy rate of the bottom roadway drainage system, and reduces the high cost and high investment of the bottom roadway due to "large cross-section construction required for drainage". Attached Figure Description

[0040] Figure 1 This is a top view of the connection of the bottom-slab tunnel directional rock borehole replacement extraction pipeline extraction system of the present invention.

[0041] Figure 2 This is a cross-sectional view of the bottom-slab tunnel directional rock borehole replacement extraction pipeline extraction system of the present invention.

[0042] Figure 3 This is a cross-sectional schematic diagram of the bottom-slab tunnel directional rock borehole replacement extraction pipeline extraction system of the present invention.

[0043] Figure 4 This is a schematic diagram of the sealing of the extraction support hole according to the present invention.

[0044] Figure 5 This is a schematic diagram of the installation of the unit metering and monitoring device of the present invention and the directional rock hole sealing and blocking.

[0045] Figure 6 This is a flowchart illustrating the design and construction process of this invention. Detailed Implementation

[0046] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0047] like Figure 1-6 As shown, a method for gas control in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines is proposed. The directional rock borehole extraction system is designed and constructed to control and extract gas in the bottom roadway. The steps are as follows: (1) Design and construction of the construction trajectory parameters of directional rock borehole 1 → (2) Secondary correction of the construction trajectory parameters of directional rock borehole 1 → (3) Calculation and adjustment of the construction inclination angle of extraction branch hole 2 → (4) Sealing of extraction branch hole 2 and connection of extraction branch hole 2 and single hole → (5) Installation and monitoring of unit metering and monitoring device 3 → (6) Design and construction of water discharge device for extraction pipeline → (7) Completion of connection of the entire extraction system and synchronous extraction with the working face.

[0048] Step (1) is as follows:

[0049] (1.1) Design of construction trajectory parameters for directional rock borehole 1:

[0050] Taking the center of the roadway roof at the location of the first extraction support hole 2 in the bottom roadway 4 as the starting point, the starting point coordinates are marked as T1(X). T1 Y T1 Z T1 ), where X T1 =0、Y T1 =0、Z T1 =0, the direction along the centerline of bottom roadway 4 is Y, the left and right width direction of bottom roadway 4 is X, and the up and down direction is Z. Then, the coordinates of the center of the roadway roof are measured every 5m (assuming the spacing between boreholes in the bottom roadway is 5m). The coordinates of the nth measuring point are marked as Tn(X Tn Y Tn Z Tn Assuming the nth measuring point is located a meters to the left and b meters above the starting point, the coordinates of the nth measuring point are calculated as: X Tn =-a、Y Tn =5*n、Z Tn =b;

[0051] By shifting the coordinates Tn 8m to the left and right respectively (tunnel width + rock pillar thickness, the rock pillar thickness to be adjusted according to mine conditions or simulation), the construction trajectory coordinates D of the two directional rock boreholes 1 on the left and right sides of the bottom tunnel 4 can be obtained. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En Construction trajectory coordinates D n (X)Dn Y Dn Z Dn ) and En(X En Y En Z En The specific assignment details are as follows:

[0052] Coordinates D of the construction trajectory of directional rock borehole 1 on the left n :X Dn = X Tn -8、Y Dn = Y Tn Z Dn = Z Tn , that is, X Dn = -a-8、Y Dn =5*n、Z Dn = b;

[0053] The construction trajectory coordinates of right-side directional rock borehole 1: En:X En = X Tn +8、Y En = Y Tn Z En = Z Tn , that is, X En = -a+8、Y En = 5*n、Z En = b;

[0054] (1.2) Construction of directional rock borehole 1:

[0055] Based on the trajectory settings of the directional drilling rig, the construction trajectory coordinates D of the two directional rock boreholes 1 on the left and right sides of the bottom slab tunnel 4, as designed in (1.1), are determined. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En The directional drilling site 5 (conventional design) is used as the construction trajectory parameter for directional drilling hole 1. Since the first 30m of the directional drilling rig is the change-direction construction section, the directional drilling site 5 is arranged outward, 20m to 30m away from the first extraction support hole, so that the change-direction section of the directional drilling rig can be constructed to the designed construction trajectory coordinates. One directional drilling site 5 is constructed on each side of the bottom roadway 4. Then, directional drilling hole 1 is constructed in the directional drilling site 5, parallel to the excavation direction of the bottom roadway 4, and at the position of the top plate of the bottom roadway 4. Directional drilling hole 1 is constructed using a ϕ193mm drill bit.

[0056] After the construction of directional rock borehole 1 was completed and the working face passed the standard evaluation, the outer end of directional rock borehole 1 was connected to the extraction pipeline at the dedicated tunnel.

[0057] Step (2) is as follows: Since the construction of directional drilling is constantly being fine-tuned, the test data of the borehole trajectory measuring instrument is closer to the real situation. Therefore, the construction trajectory parameters of directional rock hole 1 of directional drilling are based on the test data of the borehole trajectory measuring instrument.

[0058] The drilling trajectory of two directional rock boreholes 1 was measured using a borehole trajectory measuring instrument. The construction trajectory parameters of directional rock borehole 1 were then calibrated twice, and the calibrated construction trajectory coordinate data were assigned to coordinate D. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En ), and complete the secondary correction of the construction trajectory parameters of directional rock borehole 1.

[0059] Step (3) is as follows:

[0060] (3.1) Calculation of the construction inclination angle of the extraction support hole 2: Based on the construction trajectory parameters of the directional rock hole 1 after secondary correction in step (2), and combined with the construction position marked on site of the extraction support hole 2, the construction inclination angle of the extraction support hole 2 is calculated by using the trigonometric function method.

[0061] The distances from the left and right extraction support holes 2 to the roof of the bottom roadway 4 are Lh and Rh, respectively. The width of the bottom roadway 4 is K. Then the opening coordinates of the nth extraction support hole 2 on the left are Ln(X). Ln Y Ln Z Ln ) and the opening coordinates Rn(X) of the nth extraction branch hole 2 on the right. Rn Y Rn Z Rn The values ​​assigned to ) are as follows:

[0062] The opening coordinates Ln of the nth extraction support hole 2 on the left: Ln =X Tn -0.5*K, Y Ln =Y Tn Z Ln =Z Tn -Lh, then the construction inclination angle A of the nth extraction support hole 2 on the left. Ln For: A Ln =arctan[Lh / (X Dn -X Ln )];

[0063] The opening coordinates Rn of the nth extraction support hole 2 on the right side: X Rn =X Tn +0.5*K, Y Rn =YTn Z Rn =Z Tn -Rh, then the construction inclination angle A of the nth extraction support hole 2 on the right side. Rn For: A Rn =arctan[Rh / (X Dn -X Rn )];

[0064] (3.2) Construction adjustment of extraction support hole 2:

[0065] After marking the opening position and construction inclination angle of the extraction branch hole 2, a small-diameter exploratory hole (ϕ32mm) is first drilled at the opening position of the extraction branch hole 2 in the bottom roadway 4 using an anchor cable drilling rig. The exploratory hole is then inspected with an endoscope to check the connection position with the directional rock hole 1. If the connection is not established, cement is injected to seal it tightly, and the opening position and construction inclination angle are slightly adjusted. The small-diameter exploratory hole is then re-drilled until it is connected to the directional rock hole 1. Based on the inspection with the endoscope, the construction inclination angle is slightly adjusted so that the connection position is located in the lower middle part of the directional rock hole 1 wall, so as to facilitate the drainage of drill cuttings and accumulated water in the directional rock hole 1. Then, a large-diameter (ϕ155mm) drill bit is used to expand and swirl the small-diameter extraction branch hole 2 according to the final slightly adjusted construction inclination angle until it is connected to the directional rock hole 1.

[0066] Step (4) is as follows:

[0067] (4.1) Sealing of extraction support hole 2:

[0068] The extraction branch pipe 6 is used to seal the extraction branch hole 2. The extraction branch pipe 6 is 7m long and is made of plastic hose with bags 12 at both ends. The outer diameter of the extraction branch pipe 6 is ϕ120mm~ϕ150mm. The inner bag 12 is 11m~2m away from the directional rock hole with a distance of ϕ190mm. The outer bag 12 is located 1m inward from the opening of the extraction branch hole 2. The extraction branch hole 2 is sealed by the method of "sealing at both ends + grouting in the middle" (a conventional method in this field). The grouting depth is not less than 5m to ensure the sealing of the grouting section of the extraction branch pipe 6.

[0069] (4.2) Connection between extraction branch hole 2 and single hole:

[0070] The outer end of the extraction branch pipe 6 is connected to an extraction connecting head 7. At least 14 short connectors 8 with an outer diameter of ϕ50mm are connected to the extraction connecting head 7. Each short connector 8 is connected to the outer end of the single-hole sealing hose at the location of the extraction branch hole 2 in the bottom tunnel 4 for continuous extraction. A single hole refers to a single gas extraction borehole. One extraction branch hole 2 connects to multiple single holes, and one directional rock borehole 1 connects to multiple extraction branch holes 2. In this way, the entire system is connected to form an extraction system similar to a tree trunk and branches.

[0071] Step (5) is as follows: Taking the sub-unit metering and monitoring at the left side of the bottom plate roadway 4 as an example, at every 200m (lower than the industry standard distance), two monitoring branch holes 9 with appropriate spacing (meeting the requirements of the pipeline smooth section length before and after the sub-unit metering and monitoring device 3) are constructed and connected to the directional rock hole 1. The construction method of the monitoring branch hole 9 is the same as that of the extraction branch hole 2, and the plastic hose is used for sealing. Then, the sub-unit metering and monitoring device 3 is installed in the bottom plate roadway 4. The two ends of the sub-unit metering and monitoring device 3 are connected to the outer ports of the sealing pipes of the two monitoring branch holes 9 respectively. Then, the directional rock hole 1 in the middle section of the two monitoring branch holes 9 is blocked, so that the gas flow direction of the directional rock hole 1 is changed to "U-shaped" flow at the blocking point, and flows back into the directional rock hole 1 after passing through the sub-unit metering and monitoring device 3.

[0072] After the working face meets the standards, the sub-unit metering and monitoring device 3 will be removed and recycled. Then, a plastic hose will be used to replace the sub-unit metering device to connect the blockage point of the directional rock hole 1.

[0073] Step (6) specifically involves designing a water discharge device for the extraction pipeline based on the principle of "negative pressure automatic water discharge." Specifically, water discharge branch holes with an upward angle are constructed at the U-shaped or V-shaped slope change low point of the directional rock borehole 1 and at the unit metering and monitoring device 3. The construction method of the water discharge branch holes is the same as that of the extraction branch holes 2. The water discharge branch holes are connected to the directional rock borehole 1. The water discharge branch holes are sealed using the extraction branch pipe 6. The outer end of the extraction branch pipe 6 is connected to a water discharge hose 10 through a connector. Then, the bottom plate is placed below the water discharge branch hole. In tunnel 4, a pump pit 11 with a depth of not less than 1m is constructed. A water bucket with a height of not less than 1.5m is placed in the pump pit 11 and filled with water. The inner diameter of the water bucket is larger than the outer diameter of the water discharge hose 10. The lower end of the water discharge hose 10 is inserted into the water bucket to ensure a negative pressure of 20KPa in the directional rock borehole 1. If the negative pressure in the directional rock borehole 1 is 30KPa or higher, the negative pressure is converted into the height of the water column and replaced with a water bucket of the corresponding height to achieve automatic water discharge using the U-tube principle.

[0074] After the working face meets the standards, the water discharge device will remain in the bottom slab tunnel 4 and will not need to be retrieved.

[0075] Step (7) is as follows: After the above steps are completed, the replacement of the extraction pipeline with the directional rock borehole 1 is completed, the connection of the entire extraction system is completed, and synchronous extraction can be carried out with the working face.

[0076] The specific operation for sealing and blocking the directional rock borehole 1 in step (5) is as follows: construct a through sealing branch hole at the location where the directional rock borehole 1 needs to be sealed and blocked. The construction method of the sealing branch hole is the same as that of the extraction branch hole 2. Then, insert a bag 12 into the sealing branch hole to the location where the directional rock borehole 1 needs to be sealed and blocked. Then, inject grout or glue into the bag 12 to seal and block the directional rock borehole 1 at that location.

[0077] If, during the excavation of the bottom roadway 4, the rock pillar fissure caused by the roadway side anchor bolts penetrates the directional rock borehole 1, or if the fissure formed by the compression deformation at the shoulder of the bottom roadway 4 later penetrates the directional rock borehole 1, it will lead to air leakage in the rock pillar. The rock pillar refers to the rock mass from the side of the bottom roadway 4 to the directional rock borehole 1. The method for dealing with air leakage in the rock pillar is as follows:

[0078] (I) Proactive prevention: Increase the thickness of the rock pillar between the directional rock borehole 1 and the bottom roadway 4. According to the borehole inspection and the simulation of the surrounding rock delamination deformation, the rock pillar thickness of 8m can isolate the penetration of the crack, which is far beyond the length of the anchor bolt. The length of the anchor bolt is 3m to 5m.

[0079] (II) Passive treatment: When serious gas leakage occurs in the rock column, grouting holes are drilled behind the wall in the leakage area. The depth of the grouting holes behind the wall is 3m. With the leakage point as the center, high-pressure grouting is carried out at a distance of 1.5m above, below and to the left and right of the leakage point to seal and fill the surrounding rock fissures.

[0080] The directional drilling rig, borehole trajectory measuring instrument, anchor cable drilling rig, extraction continuous tap 7 and sub-unit metering and monitoring device 3 are all conventional technologies, and their specific structures and working principles will not be described in detail.

[0081] This invention achieves a "pipeless design" for the gas extraction system in the bottom roadway 4 by constructing directional rock borehole 1. It also provides technical methods such as parameter design for extraction branch borehole 2, detection method for the connection between extraction branch borehole 2 and directional rock borehole 1, installation of unit metering and monitoring device 3 for directional rock borehole 1, continuous extraction of extraction branch borehole 2 and single borehole, and water discharge configuration of extraction system. It can provide a guarantee for reducing the cost of extraction system in mine, improving the efficiency and life of extraction system, and ensuring the gas control effect of working face. The specific beneficial effects are: ① Directional rock borehole 1 completely replaces extraction pipeline and can meet the extraction concentration and flow rate under the current conditions of the mine, as well as the requirements for various parameter metering and water discharge. ② It can extend the service life and efficiency of the bottom roadway 4 drainage system, meet the goal of synchronous three-dimensional drainage during the working face mining, and reduce the gas concentration in the return airflow and the gas emission from the working face; ③ It greatly reduces the installation, dismantling costs and labor costs, as well as material losses and resource occupation of the mine using PVC drainage pipelines; ④ It reduces the maintenance cost of the bottom roadway 4 drainage system, improves the sealing performance and gas drainage concentration of the drainage system, and provides a guarantee for mine gas power generation; ⑤ It greatly improves the standardization quality of the mine bottom roadway 4 drainage system, reduces the space occupancy rate of the bottom roadway 4 drainage system, and reduces the high cost and high investment of the bottom roadway 4 due to the "large cross-section construction required for drainage".

[0082] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for controlling gas in the floor roadway by replacing extraction pipelines with directional rock boreholes, characterized in that: Design and construct a directional rock borehole replacement extraction pipeline extraction system for gas control and extraction in the bottom roadway. Specifically, follow these steps: (1) Design and construction of the directional rock borehole construction trajectory parameters → (2) Secondary correction of the directional rock borehole construction trajectory parameters → (3) Calculation and adjustment of the construction inclination angle of the extraction branch holes → (4) Sealing of the extraction branch holes and connection of the extraction branch holes and single holes → (5) Installation and monitoring of the unit metering and monitoring devices → (6) Design and construction of the extraction pipeline water discharge device → (7) Complete the connection of the entire extraction system and carry out synchronous extraction with the working face extraction. Step (1) is as follows: (1.1) Design of construction trajectory parameters for directional rock boreholes: The center of the roadway roof at the location of the first extraction support hole in the bottom roadway is taken as the starting point, and the starting point coordinates are marked as T1(X). T1 Y T1 Z T1 ), where X T1 =0、Y T1 =0、Z T1 =0, the direction along the centerline of the bottom roadway is Y, the left and right width of the bottom roadway is X, and the up and down direction is Z. Then, the coordinates of the center of the roadway roof are measured every 5m (assuming the spacing between boreholes in the bottom roadway is 5m). The coordinates of the nth measuring point are marked as Tn(X Tn Y Tn Z Tn ); By shifting the coordinates Tn 8m to the left and right respectively, we can obtain the construction trajectory coordinates D of the two directional rock boreholes on the left and right sides of the bottom tunnel. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En ); (1.2) Construction of directional rock boreholes: Based on the trajectory settings of the directional drilling rig, the construction trajectory coordinates D of the two directional rock boreholes on the left and right sides of the bottom tunnel, as designed in (1.1), are determined. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En The directional drilling site is used as the construction trajectory parameter for the directional drilling rig. Since the first 30m of the directional drilling rig is the section for changing direction, the directional drilling site is set outward, 20m to 30m away from the first extraction branch hole, so that the directional drilling rig can reach the designed construction trajectory coordinates in the section for changing direction. One directional drilling site is constructed on each side of the bottom roadway. Then, the directional drilling site is constructed parallel to the excavation direction of the bottom roadway and at the top of the bottom roadway. The directional drilling site is constructed using a ϕ193mm drill bit. After the directional rock borehole construction is completed and the working face meets the standards, the outer end of the directional rock borehole is connected to the extraction pipeline at the dedicated tunnel.

2. The method for controlling gas in the bottom roadway by replacing extraction pipelines with directional rock boreholes according to claim 1, characterized in that: Step (2) is as follows: Since the construction of directional drilling is constantly being fine-tuned, the test data of the borehole trajectory measuring instrument is closer to the real situation. Therefore, the construction trajectory parameters of the directional rock hole in directional drilling are based on the test data of the borehole trajectory measuring instrument. The drilling trajectory of two directional rock boreholes was measured using a borehole trajectory measuring instrument. The construction trajectory parameters of the directional rock boreholes were then calibrated twice, and the calibrated construction trajectory coordinate data were assigned to coordinate D. n (X) Dn Y Dn Z Dn ) and En(X En Y En Z En This completes the secondary correction of the construction trajectory parameters for directional rock boreholes.

3. The method for controlling gas in the bottom roadway by replacing extraction pipelines with directional rock boreholes according to claim 2, characterized in that: Step (3) is as follows: (3.1) Calculation of the construction inclination angle of the extraction support hole: Based on the construction trajectory parameters of the directional rock hole after secondary correction in step (2), and combined with the construction position marked on the site of the extraction support hole, the construction inclination angle of the extraction support hole is calculated by using the trigonometric function method. The distances from the left and right extraction support holes to the top of the floor roadway are Lh and Rh, respectively. The width of the floor roadway is K. Then, the opening coordinates of the nth extraction support hole on the left are Ln(X). Ln Y Ln Z Ln ) and the opening coordinates Rn(X) of the nth extraction branch hole on the right. Rn Y Rn Z Rn The values ​​assigned to ) are as follows: The opening coordinates Ln of the nth extraction support hole on the left: X Ln =X Tn -0.5*K, Y Ln =Y Tn Z Ln =Z Tn -Lh, then the construction inclination angle A of the nth extraction support hole on the left. Ln For: A Ln =arctan[Lh / (X Dn -X Ln )]; The opening coordinates Rn of the nth extraction support hole on the right: X Rn =X Tn +0.5*K, Y Rn =Y Tn Z Rn =Z Tn -Rh, then the construction inclination angle A of the nth extraction support hole on the right. Rn For: A Rn =arctan[Rh / (X Dn -X Rn )]; (3.2) Construction adjustment of the extraction support hole: After marking the opening position and construction inclination of the extraction branch hole, a small-diameter exploratory hole (ϕ32mm) is first drilled at the opening position of the extraction branch hole in the bottom roadway using an anchor cable drilling rig. An end-of-hole inspection instrument is then inserted into the small-diameter exploratory hole to check the connection position with the directional rock hole. If the connection is not established, cement is injected to seal it tightly, and the opening position and construction inclination are finely adjusted. The small-diameter exploratory hole is then re-drilled until it connects with the directional rock hole. Based on the inspection results of the end-of-hole inspection instrument, the construction inclination is finely adjusted to place the connection position in the lower middle part of the directional rock hole wall to facilitate the drainage of drill cuttings and accumulated water in the directional rock hole. Then, a large-diameter (ϕ155mm) drill bit is used to expand the small-diameter extraction branch hole according to the final finely adjusted construction inclination until it connects with the directional rock hole.

4. The method for controlling gas in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines according to claim 3, characterized in that: Step (4) is as follows: (4.1) Sealing of the extraction support hole: The extraction branch pipe is used to seal the extraction branch hole. The extraction branch pipe is 7m long and is made of plastic hose with bags at both ends. The outer diameter of the extraction branch pipe is ϕ120mm~ϕ150mm. The inner bag is 1m~2m away from the directional rock hole with a diameter of ϕ190mm. The outer bag is located 1m inward from the opening of the extraction branch hole. The extraction branch hole is sealed by "sealing at both ends + grouting in the middle". The grouting depth is not less than 5m to ensure the sealing of the grouting section of the extraction branch pipe. (4.2) Connection between the extraction support hole and the single hole: The outer end of the extraction branch pipe is connected to an extraction continuous tap, which is connected to at least 14 short connectors with an outer diameter of ϕ50mm. Each short connector is connected to the outer end of a single-hole sealing hose at the extraction branch hole location in the bottom tunnel for continuous extraction.

5. The method for controlling gas in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines according to claim 4, characterized in that: Step (5) is as follows: Taking the sub-unit metering and monitoring at the left side of the bottom roadway as an example, at every 200m position, two monitoring support holes with appropriate spacing are constructed and connected to the directional rock holes. The construction method of the monitoring support holes is the same as that of the extraction support holes, and plastic hoses are used to seal the holes. Then, the sub-unit metering and monitoring device is installed in the bottom roadway. The two ends of the sub-unit metering and monitoring device are connected to the outer ports of the sealing pipes of the two monitoring support holes respectively. Then, the directional rock holes in the middle section of the two monitoring support holes are blocked, so that the gas flow direction of the directional rock holes is changed to "U-shaped" flow at the blocking point, and flows back into the directional rock holes after passing through the sub-unit metering and monitoring device. After the working face meets the standards, the sub-unit metering and monitoring device will be removed and recycled, and a plastic hose will be used to replace the sub-unit metering device to connect the blockage point of the directional rock borehole.

6. The method for controlling gas in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines according to claim 5, characterized in that: Step (6) is as follows: The extraction pipeline adopts the principle of "automatic negative pressure water release" to design the water release device. That is, the upward-angled water release branch hole is constructed at the U-shaped or V-shaped slope change low point and the unit metering and monitoring device of the directional rock hole. The construction method of the water release branch hole is the same as the construction method of the extraction branch hole. The water release branch hole is connected to the directional rock hole. The water release branch hole is sealed with the extraction branch pipe. The outer end of the extraction branch pipe is connected to a water release hose through a connector. Then, a pump pit with a depth of not less than 1m is constructed in the bottom slab tunnel below the water release branch hole. A water bucket is placed in the pump pit. The height of the water bucket is not less than 1.5m. The water bucket is filled with water. The inner diameter of the water bucket is larger than the outer diameter of the water release hose. The lower end of the water release hose is placed in the water bucket. It can ensure a negative pressure of 20KPa in the directional rock hole. If the negative pressure in the directional rock hole is 30KPa or higher, the negative pressure is converted into the height of the water column and replaced with a water bucket of the corresponding height to realize automatic water release using the U-shaped pipe principle. After the working face meets the standards and the evaluation is completed, the water discharge device will remain in the bottom tunnel and will not need to be retrieved.

7. The method for controlling gas in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines according to claim 6, characterized in that: Step (7) is as follows: After the above steps are completed, the directional rock borehole replacement extraction pipeline is completed, and the connection of the entire extraction system is completed, so that it can be extracted synchronously with the working face.

8. The method for controlling gas in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines according to claim 7, characterized in that: The specific operation for sealing and blocking the directional rock borehole in step (5) is as follows: construct a through sealing branch hole at the location where the directional rock borehole needs to be sealed and blocked. The construction method of the sealing branch hole is the same as that of the extraction branch hole. Then, insert a bag into the sealing branch hole to the location where the directional rock borehole needs to be sealed and blocked. Then, inject grout or glue into the bag to seal and block the directional rock borehole at that location.

9. The method for controlling gas in the bottom roadway using directional rock boreholes as an alternative to extraction pipelines according to claim 7, characterized in that: When rock column fissures caused by anchor bolts on the roadway sidewalls during the excavation of the bottom roadway penetrate directional rock boreholes, or when fissures formed by compression deformation at the shoulder of the bottom roadway later penetrate directional rock boreholes, it can lead to gas leakage in the rock column. A rock column refers to the rock mass between the roadway sidewalls and the directional rock boreholes. The method for handling gas leakage in the rock column is as follows: (I) Proactive prevention: Increase the thickness of the rock pillar between the directional rock borehole and the sidewall of the bottom roadway. According to the borehole inspection and surrounding rock delamination deformation simulation, the rock pillar thickness of 8m can isolate the penetration of the crack, which is far beyond the length of the anchor bolt. The length of the anchor bolt is 3m to 5m. (II) Passive treatment: When serious gas leakage occurs in the rock column, grouting holes are drilled behind the wall in the leakage area. The depth of the grouting holes behind the wall is 3m. With the leakage point as the center, high-pressure grouting is carried out at a distance of 1.5m above, below and to the left and right of the leakage point to seal and fill the surrounding rock fissures.

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