Flexible pressure maintaining and recoverable intelligent hole sealing method for multiple groups of drill holes in same roadway

Abstract

The same lane multiple groups of drill hole flexible pressure maintaining and recoverable intelligent hole sealing method comprises the following steps: arranging a ground slurry preparation and storage system and a main control PLC controller on the ground, arranging a grouting pump station, a back slurry pump station and a plurality of tire bag type recoverable hole sealers in a roadway underground, and connecting pipelines; the ground slurry preparation and storage system prepares slurry for hole sealing; grouting hole sealing operation is carried out; a gas extraction pipeline is connected to carry out gas extraction operation on the drill hole; dynamic pressure maintaining is carried out on the tire bag type recoverable hole sealer, and alarm and disposal are carried out on pressure loss of the tire bag and the middle section; the tire bag type recoverable hole sealer and the slurry are recovered. The present application realizes intelligent grouting hole sealing by using a control system, realizes accurate and free control of hole sealing pressure, automatic pressure maintaining of the drill hole during hole sealing, automatic recovery of sealing materials after extraction, and the hole sealer can also be recovered and reused, and has the advantages of simple operation, high automation, low labor intensity of workers, cost saving and the like.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas extraction technology, specifically relating to a flexible pressure-maintaining and recyclable intelligent sealing method for multiple sets of boreholes in the same roadway. Background Technology

[0002] Traditional gas extraction and sealing processes typically involve drilling a borehole, inserting a sealing device, and then mixing sealing material and water in a mixing tank to form a slurry. The slurry is then injected into the sealing device using a grouting pump. After the slurry solidifies, the extraction pipe is connected to the extraction pipeline for gas extraction. Furthermore, within the same roadway, it's common practice to drill one hole and then seal it, then drill the next hole and seal it again. This operation and sealing process suffers from high costs associated with transporting sealing materials, high labor intensity, complex operation, low success rate, and significant dependence on worker skill levels. If the borehole deforms due to mining activity after the slurry solidifies in the sealing device, gas leakage can easily occur, affecting the gas extraction concentration. Additionally, the sealing device and sealing material cannot be recycled, resulting in high costs. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a flexible pressure-maintaining and recyclable intelligent sealing method for multiple boreholes in the same roadway that is easy to operate, easy to transport sealing slurry, and can ensure good sealing performance during the sealing process.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a flexible pressure-maintaining and recyclable intelligent sealing method for multiple sets of boreholes in the same roadway, comprising the following steps:

[0005] (1) A surface slurry preparation and storage system and a main control PLC controller are arranged on the surface of the mine. A grouting pump station and a return slurry pump station are arranged in the underground roadway. A bladder-type reusable sealing device is installed in several sets of boreholes in the underground roadway. The outlet of the surface slurry preparation and storage system is connected to the inlet of the grouting pump station through the main slurry conveying pipe. The outlet of the grouting pump station is connected to the inlet of each set of bladder-type reusable sealing devices through the underground grouting main pipe. The return slurry port of each set of bladder-type reusable sealing devices is connected to the inlet of the return slurry pump station through the underground return slurry main pipe. The outlet of the return slurry pump station is connected to the return slurry port of the surface slurry preparation and storage system through the main return slurry pipe.

[0006] (2) Preparation of sealing slurry using a ground-based slurry preparation and storage system;

[0007] (3) Grouting and sealing operations are performed into the bladder-type recyclable sealing device;

[0008] (4) Connect the gas extraction pipeline to the borehole for gas extraction operations;

[0009] (5) During the gas extraction operation, the borehole of the underground slurry storage and transportation system dynamically maintains the pressure of the bladder-type retrievable sealing device and monitors the sealing section in real time. When the sealing section loses pressure, an alarm is triggered and measures are taken.

[0010] (6) After the gas extraction is completed, the bladder-type recyclable sealing device and slurry are recovered.

[0011] The ground pulping and storage system includes a silo, a mixing tank, and a belt conveyor. The feed end of the belt conveyor is located below the discharge port of the silo. The top of the mixing tank has a feed inlet. The discharge end of the belt conveyor is connected to the feed inlet via a transfer guide plate. The top of the mixing tank is equipped with a mixing motor. The main shaft of the mixing motor is driven to a stirrer located inside the mixing tank. A water supply pipe is connected to the upper side of the mixing tank. The water supply pipe is equipped with a water supply solenoid valve and a first flow sensor. A density sensor and a viscosity sensor are located on the lower part of the inner wall of the mixing tank. Liquid level sensors are located on both the upper and lower parts of the inner wall of the mixing tank.

[0012] Several boreholes are drilled in the underground roadway. Boreholes that are evenly spaced along the length of the roadway are grouped together. Each group of boreholes is equipped with a bladder-type retrievable sealing device. Each bladder-type retrievable sealing device includes a first bladder, a second bladder, a first grouting pipe, and a second grouting pipe. A extraction pipe is inserted into the central hole of the first and second bladders. The first bladder is located below the second bladder. The first grouting pipe passes through the first and second bladders from bottom to top. The upper end of the first grouting pipe is sealed. The first grouting pipe has a first grouting hole located in the first bladder and a second grouting hole located in the second bladder. The upper end of the second grouting pipe passes through the first bladder from bottom to top and extends between the first and second bladders.

[0013] The lower end of the first grouting pipe is connected to a first tee pipe. The lower part of the first grouting pipe is equipped with a first pressure sensor and a second flow sensor. The second port of the first tee pipe is connected to the downhole grouting main pipe through a first grouting hose. The third port of the first tee pipe is connected to the downhole grouting main pipe through a first return grouting hose. The second port of the first tee pipe is equipped with a first solenoid valve, and the third port of the first tee pipe is equipped with a second solenoid valve.

[0014] The lower end of the second grouting pipe is connected to a second tee pipe. The lower part of the second grouting pipe is equipped with a second pressure sensor and a third flow sensor. The second interface of the second tee pipe is connected to the downhole grouting main pipe through a second grouting hose. The third interface of the second tee pipe is connected to the downhole grouting main pipe through a second return grouting hose. The second interface of the second tee pipe is equipped with a third solenoid valve, and the third interface of the second tee pipe is equipped with a fourth solenoid valve.

[0015] The downhole grouting main pipe is equipped with a fifth solenoid valve, a fourth flow sensor, and a third pressure sensor in sequence along the grout flow direction, and a sixth solenoid valve is installed on the main grout delivery pipe.

[0016] The main slurry return pipe is equipped with a fourth pressure sensor, a seventh solenoid valve, and a fifth flow sensor in sequence along the slurry flow direction, and an eighth solenoid valve is installed on the main slurry return pipe.

[0017] The specific process of step (2) is as follows: According to the predetermined pulping amount, the main control PLC controller sends an instruction to the water supply pump connected to the water supply pipe inlet. At the same time, the belt conveyor, the mixing motor, and the screw feeder at the bottom of the silo are all started and the water supply solenoid valve is opened to inject a certain amount of water into the mixing tank. According to the information of the first flow sensor, the predetermined water volume is reached and the water injection is stopped. The screw feeder quantitatively transports the solid material to the belt conveyor. The belt conveyor transports the solid material to the mixing tank. The mixing motor drives the agitator to start mixing, so that the material and water are fully mixed and stirred evenly until the predetermined ratio is reached. The sealing material has good fluidity and a certain viscosity. The density sensor and viscosity sensor are used to measure the viscosity and density information of the slurry in real time and transmit it to the main control PLC controller. After the slurry is qualified, the mixing motor stops working.

[0018] The specific process of step (3) is as follows: According to the number of borehole groups, the pre-reserved reusable sealing devices with corresponding interfaces are fixed side by side on one side of the roadway, and connected to the underground grouting main pipe and the underground grouting main pipe respectively through the grouting hose and the return grout hose. The reusable sealing device is inserted into the predetermined sealing depth of the borehole. The main control PLC controller instructs the fifth and sixth solenoid valves to open, the grouting pump station is started, and the grout is transported to the reusable sealing device of each sealing location through the main grouting pipe and the underground grouting main pipe. The main control PLC controller sends a pressure signal value through the third pressure sensor to control the fifth solenoid valve on the underground grouting main pipe to realize the pipeline opening and closing, so that the underground grouting main pipe starts to open. Maintain a certain grouting pressure. Then, the main control PLC controller issues a sealing command, the first solenoid valve on the first three-way pipe opens, and the first grouting pipe begins to inject grout into the two first and second burrs. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes, stopping the grouting. Then, the third solenoid valve on the second three-way pipe opens, and the grout begins to be injected into the middle section between the first and second burrs through the second grouting pipe until the second pressure sensor detects that the preset grouting pressure value has been reached. The main control PLC controller issues a command to close the third solenoid valve, stopping the grouting. One borehole is then sealed. The same operation process is used to complete the grouting and sealing operation of the other boreholes in the same group.

[0019] The specific process of dynamically maintaining pressure for the bladder-type recyclable borehole sealer in step (5) is as follows: When the borehole deforms and the cross-section increases, causing the pressure in the first and / or second bladders to decrease and fall below the predetermined constant pressure, the first pressure sensor transmits the pressure monitoring data to the main control PLC controller. The main control PLC controller instructs the first solenoid valve to open, and the first grouting pipe begins to inject grout into the two first and second bladders. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and the grouting stops. Similarly, when the pressure drops in the middle section between the first and second bladders due to the appearance of cracks around the borehole and the continuous seepage of grout into the cracks, the third solenoid valve connected to the second grouting pipe opens, and the grout begins to be injected into the middle section between the first and second bladders through the second grouting pipe until the second pressure sensor detects that the preset grouting pressure value has been reached. The main control PLC controller then issues a command to close the third solenoid valve and stop the grouting.

[0020] When the borehole deforms and its effective diameter decreases due to mining activities, the pressure on the sump and intermediate section increases. When the pressure exceeds the set value, the first and second pressure sensors send pressure change information to the main control PLC controller. The main control PLC controller first sends opening instructions to the fourth, seventh, and eighth solenoid valves. The slurry in the intermediate section of the borehole will first enter the second return slurry hose through the third interface (return slurry port) of the second injection pipe and the second three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, the slurry flows back to the mixing tank through the main return slurry pipe. When the value detected by the second pressure sensor reaches the set value, the fourth, seventh, and eighth solenoid valves close. Then, the main control PLC controller first sends an opening command to the second, seventh, and eighth solenoid valves. The slurry in the first and second sacs will first enter the first return slurry hose through the third interface (return slurry port) of the first injection pipe and the first three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, the slurry flows back to the mixing tank through the main return slurry pipe. When the value detected by the first pressure sensor reaches the set value, the second, seventh, and eighth solenoid valves close.

[0021] The specific process of real-time monitoring of the sealing section and alarm and handling when the sealing section loses pressure in step (5) is as follows:

[0022] A) Pressure Loss Alarm and Handling: When the burr ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor, and the grout injection cannot maintain the pressure of the burr, or when the pressure rises and then drops shortly, the system will stop injecting grout into the burr to prevent a large amount of grout from flowing into the borehole or tunnel. An audible and visual alarm will be issued to indicate that the burr in the borehole has ruptured due to pressure loss. At this time, the burr in the borehole can be recovered first, the ruptured burr replaced, and then the borehole can be sealed to ensure that the borehole can continue to pump normally.

[0023] B) Mid-section Pressure Loss Alarm and Handling: When numerous through-type fractures appear in the mid-section of the borehole due to mining activities, causing severe slurry loss and a sharp drop in pressure monitored by the second pressure sensor, and slurry replenishment fails to maintain pressure in the mid-section, or pressure loss occurs shortly after a pressure rise, the system will stop injecting slurry into the mid-section to prevent a large influx of slurry into the borehole or roadway, and issue an audible and visual alarm indicating pressure loss in the mid-section. At this point, the gas concentration in a single borehole should be measured first. If the gas concentration in a single borehole does not show a significant decrease, no action is necessary. If the gas concentration in the borehole has decreased significantly compared to before, the borehole sealer can be retrieved, and the sealing position or the density and viscosity of the sealing slurry in the mid-section adjusted before resealing. If pressure maintenance is still difficult, it indicates that there are serious and large fractures around the borehole that are difficult to seal. In this case, the borehole should be closed to prevent gas leakage from causing an overall decrease in the gas concentration of the extraction pipeline.

[0024] Step (6) The specific process of recovering the bladder-type recyclable sealing device and slurry is as follows: When the drilling and extraction at a certain point meets the standard and the sealing device needs to be recovered, the main control PLC controller first sends an opening command to the fourth, seventh and eighth solenoid valves. The slurry in the middle section of the borehole will first enter the second return slurry hose through the third interface (return slurry port) of the second injection pipe and the second three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, it finally flows into the mixing tank on the ground through the main return slurry pipe. When the value monitored by the second pressure sensor reaches the set value, the fourth, seventh and eighth solenoid valves are closed. Then, the main control PLC controller first sends opening command information to the second solenoid valve, the seventh solenoid valve and the eighth solenoid valve. The slurry in the first and second sacs will first enter the first return slurry hose through the third interface (return slurry port) of the first injection pipe and the first three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, the slurry flows back to the mixing tank through the main return slurry pipe. When the value monitored by the first pressure sensor reaches the set value, the second solenoid valve, the seventh solenoid valve and the eighth solenoid valve close.

[0025] By adopting the above technical solution, the present invention has the following technical effects:

[0026] 1. The main control PLC controller in this invention is mainly responsible for controlling the stirring motor, grouting pump station, return grouting pump station and solenoid valve to perform corresponding actions according to the requirements of grouting, grouting storage and delivery and the information fed back by the flow sensor, density sensor, viscosity sensor and liquid level sensor. It also displays the relevant information on the display screen of the host computer and can adjust key data such as grouting volume, grouting delivery volume and grouting storage volume as needed. The main control PLC controller is used to control the opening and closing of the solenoid valve, flow sensor and pressure sensor connected below the downhole grouting main pipe, downhole return grouting main pipe and the bladder-type retrievable sealing device.

[0027] 2. When recovering slurry, recover the slurry in the middle section first, and then recover the slurry inside the first and second slurry sacs. This sequential order avoids the situation where the pressure in the middle section is high and the pressure in the sac decreases, which can cause slurry leakage. It also ensures that the sac will not rupture due to increased pressure caused by borehole deformation.

[0028] 3. The flexible sealing and dynamic pressure-holding sealing of the borehole ensures that the entire borehole is always in a stable pressure-holding extraction state, eliminating the air leakage caused by the increase in borehole volume after the traditional sealing material solidifies, and the failure of extraction borehole caused by the compression and breakage of the extraction tube due to the decrease in borehole volume. This ensures the safety and efficiency of extraction.

[0029] In summary, this invention involves preparing the slurry on the ground and directly delivering it to a recyclable slurry packer in each borehole within the underground tunnel. The control system enables highly intelligent grouting and sealing, allowing for precise and free control of the sealing pressure, automatic pressure maintenance throughout the borehole sealing process, automatic recovery of the sealing material after extraction, and recyclable slurry packers. It offers advantages such as small footprint, simple operation, high automation, low labor intensity for workers, and cost savings. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the connection structure between the ground pulping and storage system and the pipelines in this invention;

[0031] Figure 2 This is a schematic diagram of the structure of the bladder-type recyclable sealing device in this invention;

[0032] Figure 3 yes Figure 2 Axial sectional view of the two fetal sacs;

[0033] Figure 4 This is a schematic diagram of the arrangement of the bladder-type recyclable sealing device in the cross-layer borehole along the length of the roadway in this invention.

[0034] Figure 5 This is a schematic diagram of the bladder-type recyclable sealing device of the present invention arranged along the width direction of the tunnel in the cross-layer borehole;

[0035] Figure 6This is a schematic diagram of the recyclable bladder-type sealing device of the present invention arranged along the width of the roadway in the in-seam borehole. Detailed Implementation

[0036] like Figures 1-6 As shown, the present invention provides a flexible pressure-maintaining and recyclable intelligent sealing method for multiple boreholes in the same roadway, comprising the following steps:

[0037] (1) A surface slurry preparation and storage system and a main control PLC controller (not shown) are arranged on the surface of the mine. A grouting pump station 18 and a return slurry pump station 19 are arranged in the underground roadway. A bladder-type recyclable sealing device 5 is installed in several sets of boreholes in the underground roadway 28. The boreholes include cross-layer boreholes and in-layer boreholes. The outlet of the surface slurry preparation and storage system is connected to the inlet of the grouting pump station 18 through the main slurry conveying pipe 1. The outlet of the grouting pump station 18 is connected to the inlet of each set of bladder-type recyclable sealing devices 5 through the underground grouting main pipe 3. The return port of each set of bladder-type recyclable sealing devices 5 is connected to the inlet of the return slurry pump station 19 through the underground return slurry main pipe 4. The outlet of the return slurry pump station 19 is connected to the return port of the surface slurry preparation and storage system through the main return slurry pipe 2.

[0038] (2) Preparation of sealing slurry using a ground-based slurry preparation and storage system;

[0039] (3) Grouting and sealing operation is carried out into the bladder-type recyclable sealing device 5;

[0040] (4) Connect the gas extraction pipeline to the borehole for gas extraction operations;

[0041] (5) During the gas extraction operation, the borehole of the underground slurry storage and transportation system dynamically maintains the pressure of the bladder-type retrievable sealing device 5, and monitors the sealing section in real time. When the sealing section loses pressure, an alarm is triggered and measures are taken.

[0042] (6) After the gas extraction is completed, the bladder-type recyclable sealing device 5 and the slurry are recovered.

[0043] The ground pulping and storage system includes a silo 6, a mixing tank 7, and a belt conveyor 8. The feed end of the belt conveyor 8 is located below the discharge port of the silo 6. The top of the mixing tank 7 has a feed port. The discharge end of the belt conveyor 8 is connected to the feed port through a transfer guide plate 9. The top of the mixing tank 7 is equipped with a mixing motor 10. The main shaft of the mixing motor 10 is driven to connect to an agitator 11 (including a mixing shaft and mixing blades) located inside the mixing tank 7. A water supply pipe 12 is connected to the upper side of the mixing tank 7. A water supply solenoid valve 13 and a first flow sensor 14 are installed on the water supply pipe 12. A density sensor 15 and a viscosity sensor 16 are installed on the lower part of the inner wall of the mixing tank 7. Liquid level sensors 17 are installed on both the upper and lower parts of the inner wall of the mixing tank 7.

[0044] Several boreholes 29 are drilled in the underground roadway 28. Among them, the boreholes 29 that are evenly spaced along the length of the roadway 28 are grouped together. Each group of boreholes 29 is equipped with a bladder-type retrievable sealing device 5. Each bladder-type retrievable sealing device 5 includes a first bladder 30, a second bladder 31, a first grouting pipe 32, and a second grouting pipe 33. A extraction pipe 34 is inserted into the central hole of the first bladder 30 and the second bladder 31. The first bladder 30 is located below the second bladder 31. The first grouting pipe 32 passes through the first bladder 30 and the second bladder 31 from bottom to top. The upper end of the first grouting pipe 32 is sealed. The first grouting pipe 32 is provided with a first grouting hole 35 located in the first bladder 30 and a second grouting hole 36 located in the second bladder 31. The upper end of the second grouting pipe 33 passes through the first bladder 30 from bottom to top and extends between the first bladder 30 and the second bladder 31.

[0045] The lower end of the first grouting pipe 32 is connected to the first tee pipe 64. The lower part of the first grouting pipe 32 is provided with a first pressure sensor 37 and a second flow sensor 38. The second interface of the first tee pipe 64 is connected to the downhole grouting main pipe 3 through the first grouting hose 39. The third interface of the first tee pipe 64 is connected to the downhole grouting main pipe 4 through the first return grouting hose 40. The second interface of the first tee pipe 64 is provided with a first solenoid valve 41, and the third interface of the first tee pipe 64 is provided with a second solenoid valve 42.

[0046] The lower end of the second grouting pipe 33 is connected to a second tee pipe 43. The lower part of the second grouting pipe 33 is equipped with a second pressure sensor 44 and a third flow sensor 45. The second interface of the second tee pipe 43 is connected to the downhole grouting main pipe 3 through a second grouting hose 46. The third interface of the second tee pipe 43 is connected to the downhole grouting main pipe 4 through a second return grouting hose 47. The second interface of the second tee pipe 43 is equipped with a third solenoid valve 48, and the third interface of the second tee pipe 43 is equipped with a fourth solenoid valve 49.

[0047] The downhole grouting main pipe 3 is equipped with a fifth solenoid valve 20, a fourth flow sensor 21 and a third pressure sensor 22 in sequence along the grout flow direction, and a sixth solenoid valve 23 is provided on the main grout delivery pipe 1.

[0048] The downhole slurry return main pipe 4 is equipped with a fourth pressure sensor 24, a seventh solenoid valve 25 and a fifth flow sensor 26 in sequence along the slurry flow direction, and the main slurry return pipe 2 is equipped with an eighth solenoid valve 27.

[0049] The specific process of step (2) is as follows: According to the predetermined pulping amount, the main control PLC controller sends an instruction to the water supply pump connected to the inlet of the water supply pipe 12. At the same time, the belt conveyor 8, the stirring motor 10, and the screw feeder at the bottom of the silo 6 are all started, and the water supply solenoid valve 13 is opened to inject a certain amount of water into the mixing tank 7. According to the information of the first flow sensor 14, the predetermined water volume is determined and the water injection is stopped. The screw feeder quantitatively transports the solid material to the belt conveyor 8. The belt conveyor 8 transports the solid material into the mixing tank 7. The stirring motor 10 drives the stirrer 11 to start stirring, so that the material and water are fully mixed and stirred evenly until the predetermined ratio is reached. The sealing material has good fluidity and a certain viscosity. The density sensor 15 and the viscosity sensor 16 are used to measure the viscosity and density information of the slurry in real time and transmit it to the main control PLC controller. After the slurry is qualified, the stirring motor 10 stops working.

[0050] The specific process of step (3) is as follows: According to the number of boreholes 29, the pre-reserved reusable sealing devices 5 with corresponding interfaces are fixed side by side on one side of the roadway 28, and connected to the underground grouting main pipe 3 and the underground grouting main pipe 4 respectively through the grouting hose and the return grout hose. The reusable sealing devices 5 are inserted into the borehole 29 to the predetermined sealing depth. The main control PLC controller commands the fifth solenoid valve 20 and the sixth solenoid valve 23 to open, the grouting pump station 18 is started, and the grout is transported to the reusable sealing device 5 at each sealing location through the main grouting pipe 1 and the underground grouting main pipe 3. The main control PLC controller sends a pressure signal value through the third pressure sensor 22 to control the fifth solenoid valve 20 on the underground grouting main pipe 3 to realize the pipeline opening and closing, so that the underground grouting main pipe 3 always maintains a certain grouting pressure. Subsequently, a sealing command is issued via the main PLC controller. At this time, the first solenoid valve 41 on the first three-way pipe 64 opens, and the first grouting pipe 32 begins to inject grout into the two first bladders 30 and the second bladder 31. When the first pressure sensor 37 detects that the set pressure value has been reached, the first solenoid valve 41 closes, stopping the grouting. Then, the third solenoid valve 48 on the second three-way pipe 43 opens, and grout begins to be injected into the middle section between the first bladder 30 and the second bladder 31 through the second grouting pipe 33 until the second pressure sensor 44 detects that the preset grouting pressure value has been reached. At this point, the main PLC controller issues a command to close the third solenoid valve 48, stopping the grouting. One borehole 29 is then sealed. The same operation process is used to complete the sealing operation of the other boreholes 29 in the same group.

[0051] The specific process of dynamically maintaining pressure for the bladder-type recyclable sealing device in step (5) is as follows: Taking a single extraction borehole 29 as an example, when the cross-section of the borehole 29 deforms and becomes larger, causing the pressure in the first bladder 30 and / or the second bladder 31 to decrease and be less than the predetermined constant pressure, the first pressure sensor 37 transmits the pressure monitoring data to the main control PLC controller. The main control PLC controller instructs the first solenoid valve 41 to open, and the first grouting pipe 32 begins to inject grout into the two first bladders 30 and the second bladder 31. When the first pressure sensor 37 detects that the set pressure value has been reached, the first solenoid valve 41 closes and stops grouting. Similarly, when the pressure drops in the middle section between the first sac 30 and the second sac 31 due to the appearance of cracks around the borehole 29 and the continuous seepage of grout into the cracks, the third solenoid valve 48 connected to the second grouting pipe 33 opens, and the grout begins to be injected into the middle section between the first sac 30 and the second sac 31 through the second grouting pipe 33 until the second pressure sensor 44 detects that the preset grouting pressure value has been reached. The main control PLC controller then issues a command to close the third solenoid valve 48 to stop the grouting.

[0052] When borehole 29 deforms and its effective diameter decreases due to mining activities, the pressure on the sump and intermediate section increases. When this pressure exceeds the set value, the first pressure sensor 37 and the second pressure sensor send pressure change information to the main control PLC controller. The main control PLC controller then sends opening commands to the fourth solenoid valve 49, the seventh solenoid valve 25, and the eighth solenoid valve 27. The slurry in the intermediate section of borehole 29 then enters the second return slurry hose 47 through the third interface (return port) of the second injection pipe 33 and the second three-way pipe 43, flowing into the downhole return slurry main pipe 4. Under the action of the return slurry pump station 19, the slurry flows back to the mixing tank 7 through the main return slurry pipe 2. When the value monitored by the second pressure sensor 44 reaches the set value, the fourth solenoid valve 49, the seventh solenoid valve 25, and the eighth solenoid valve 27 close. Then, the main control PLC controller first sends an opening command to the second solenoid valve 42, the seventh solenoid valve 25, and the eighth solenoid valve 27. The slurry in the first sac 30 and the second sac 31 will first enter the first return slurry hose 40 through the third interface (return slurry port) of the first injection pipe 32 and the first three-way pipe 64, and flow into the downhole return slurry main pipe 4. Under the action of the return slurry pump station 19, the slurry flows back to the mixing tank 7 through the main return slurry pipe 2. When the value monitored by the first pressure sensor 37 reaches the set value, the second solenoid valve 42, the seventh solenoid valve 25, and the eighth solenoid valve 27 are closed.

[0053] First, the slurry in the middle section is recovered, and then the slurry inside the first sac 30 and the second sac 31 is recovered. This sequential order avoids the situation where the pressure in the middle section is high and the pressure in the sac decreases, which can cause slurry leakage. It also ensures that the sac will not rupture due to the increased pressure caused by the deformation of the borehole 29.

[0054] The specific process of real-time monitoring of the sealing section and alarm and handling when the sealing section loses pressure in step (5) is as follows:

[0055] A) Pressure Loss Alarm and Handling: When the burr ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor 37, and the grout injection cannot maintain the pressure of the burr, or when the pressure rises and then drops shortly, the system will stop injecting grout into the burr to prevent a large amount of grout from flowing into borehole 29 or tunnel 28, and will issue an audible and visual alarm to indicate that the burr in borehole 29 has ruptured due to pressure loss. At this time, the burr in borehole 29 can be recovered first, the ruptured burr replaced, and then the borehole can be sealed to ensure that the borehole 29 can continue to be pumped normally.

[0056] B) Alarm and Handling of Pressure Loss in the Intermediate Section: When a large number of through-type fractures appear in the intermediate section of borehole 29 due to mining, resulting in severe slurry loss in the intermediate section of borehole 29, the pressure monitored by the second pressure sensor 44 drops sharply, and the injection of slurry cannot maintain the pressure in the intermediate section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the intermediate section of borehole 29 to prevent a large amount of slurry from flowing into borehole 29 or roadway 28, and issue an audible and visual alarm to indicate that the intermediate section of borehole 29 is under pressure. At this time, the gas concentration in a single hole of borehole 29 can be measured first. If the gas concentration in a single hole does not decrease significantly, no action is required. If the gas concentration in borehole 29 decreases too much compared to before, the sealing device of borehole 29 can be retrieved, the sealing position of the sealing device or the density and viscosity of the sealing slurry in the intermediate section can be adjusted, and the hole can be sealed again. If it is still difficult to maintain pressure, it proves that there are serious and large cracks around the borehole 29 that are difficult to seal. The borehole 29 can be closed to prevent the overall gas concentration of the extraction pipeline from decreasing due to gas leakage from the borehole 29.

[0057] Step (6) The specific process of recovering the bladder-type recyclable sealing device and slurry is as follows: When the drilling 29 reaches the standard and the sealing device needs to be recovered, the main control PLC controller first sends an opening command to the fourth solenoid valve 49, the seventh solenoid valve 25 and the eighth solenoid valve 27. The slurry in the middle section of the drilling 29 will first enter the second return slurry hose 47 through the third interface (return slurry port) of the second injection pipe 33 and the second three-way pipe 43, and flow into the downhole return slurry main pipe 4. Under the action of the return slurry pump station 19, it finally flows into the mixing tank 7 on the ground through the main return slurry pipe 2. When the value monitored by the second pressure sensor 44 reaches the set value, the fourth solenoid valve 49, the seventh solenoid valve 25 and the eighth solenoid valve 27 are closed. Then, the main control PLC controller first sends an opening command to the second solenoid valve 42, the seventh solenoid valve 25 and the eighth solenoid valve 27. The slurry in the first sac 30 and the second sac 31 will first enter the first return slurry hose 40 through the third interface (return slurry port) of the first injection pipe 32 and the first three-way pipe 64, and flow into the downhole return slurry main pipe 4. Under the action of the return slurry pump station 19, the slurry flows back to the mixing tank 7 through the main return slurry pipe 2. When the value monitored by the first pressure sensor 37 reaches the set value, the second solenoid valve 42, the seventh solenoid valve 25 and the eighth solenoid valve 27 are closed.

[0058] This embodiment does not impose any limitation on the shape, material, structure, etc. of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A flexible, pressure-maintaining, recyclable, and intelligent sealing method for multiple sets of boreholes in the same roadway, characterized in that: Includes the following steps: (1) A surface slurry preparation and storage system and a main control PLC controller are arranged on the surface of the mine. A grouting pump station and a return slurry pump station are arranged in the underground roadway. A bladder-type reusable sealing device is installed in several sets of boreholes in the underground roadway. The outlet of the surface slurry preparation and storage system is connected to the inlet of the grouting pump station through the main slurry conveying pipe. The outlet of the grouting pump station is connected to the inlet of each set of bladder-type reusable sealing devices through the underground grouting main pipe. The return slurry port of each set of bladder-type reusable sealing devices is connected to the inlet of the return slurry pump station through the underground return slurry main pipe. The outlet of the return slurry pump station is connected to the return slurry port of the surface slurry preparation and storage system through the main return slurry pipe. Several boreholes are drilled in the underground roadway. Boreholes that are evenly spaced along the length of the roadway are grouped together. Each group of boreholes is equipped with a bladder-type retrievable sealing device. Each bladder-type retrievable sealing device includes a first bladder, a second bladder, a first grouting pipe, and a second grouting pipe. A extraction pipe is inserted into the central hole of the first and second bladders. The first bladder is located below the second bladder. The first grouting pipe passes through the first and second bladders from bottom to top. The upper end of the first grouting pipe is sealed. The first grouting pipe has a first grouting hole located in the first bladder and a second grouting hole located in the second bladder. The upper end of the second grouting pipe passes through the first bladder from bottom to top and extends between the first and second bladders. The lower end of the first grouting pipe is connected to a first tee pipe. The lower part of the first grouting pipe is equipped with a first pressure sensor and a second flow sensor. The second port of the first tee pipe is connected to the downhole grouting main pipe through a first grouting hose. The third port of the first tee pipe is connected to the downhole grouting main pipe through a first return grouting hose. The second port of the first tee pipe is equipped with a first solenoid valve, and the third port of the first tee pipe is equipped with a second solenoid valve. The lower end of the second grouting pipe is connected to a second tee pipe. The lower part of the second grouting pipe is equipped with a second pressure sensor and a third flow sensor. The second interface of the second tee pipe is connected to the downhole grouting main pipe through the second grouting hose. The third interface of the second tee pipe is connected to the downhole grouting main pipe through the second return grouting hose. The second interface of the second tee pipe is equipped with a third solenoid valve. The third interface of the second tee pipe is equipped with a fourth solenoid valve. (2) Preparation of sealing slurry using a ground-based slurry preparation and storage system; (3) Grouting and sealing operations are performed into the bladder-type recyclable sealing device; (4) Connect the gas extraction pipeline to the borehole for gas extraction operations; (5) During the gas extraction operation, the bladder-type retrievable sealing device is dynamically pressure maintained and the sealing section is monitored in real time. When the sealing section loses pressure, an alarm is triggered and measures are taken. The alarm and measures taken when the sealing section loses pressure include: A) bladder pressure loss alarm and measures, B) borehole intermediate section pressure loss alarm and measures. (6) After the gas extraction is completed, the slurry and the bladder-type recyclable sealing device are recycled. When recycling the slurry, the slurry in the middle section of the borehole is recycled first, and then the slurry inside the first and second bladders is recycled.

2. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 1, characterized in that: The ground pulping and storage system includes a silo, a mixing tank, and a belt conveyor. The feed end of the belt conveyor is located below the discharge port of the silo. The top of the mixing tank has a feed inlet. The discharge end of the belt conveyor is connected to the feed inlet via a transfer guide plate. The top of the mixing tank is equipped with a mixing motor. The main shaft of the mixing motor is driven to a stirrer located inside the mixing tank. A water supply pipe is connected to the upper side of the mixing tank. The water supply pipe is equipped with a water supply solenoid valve and a first flow sensor. A density sensor and a viscosity sensor are located on the lower part of the inner wall of the mixing tank. Liquid level sensors are located on both the upper and lower parts of the inner wall of the mixing tank.

3. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 2, characterized in that: The downhole grouting main pipe is equipped with a fifth solenoid valve, a fourth flow sensor, and a third pressure sensor in sequence along the grout flow direction, and a sixth solenoid valve is installed on the main grout delivery pipe.

4. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 3, characterized in that: The main slurry return pipe is equipped with a fourth pressure sensor, a seventh solenoid valve, and a fifth flow sensor in sequence along the slurry flow direction, and an eighth solenoid valve is installed on the main slurry return pipe.

5. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 4, characterized in that: The specific process of step (2) is as follows: According to the predetermined pulping volume, the main control PLC controller sends an instruction to the water supply pump connected to the water supply pipe inlet. At the same time, the belt conveyor, the mixing motor, and the screw feeder at the bottom of the silo are all started, and the water supply solenoid valve is opened to inject a certain amount of water into the mixing tank. According to the information of the first flow sensor, the predetermined water volume is reached and the water injection is stopped. The screw feeder quantitatively transports the solid material to the belt conveyor, and the belt conveyor transports the solid material into the mixing tank. The mixing motor drives the agitator to start mixing, so that the material and water are fully mixed and stirred evenly until the predetermined ratio is reached. The density sensor and viscosity sensor are used to measure the density information and viscosity of the slurry in real time and transmit them to the main control PLC controller. After the slurry is qualified, the mixing motor stops working.

6. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 5, characterized in that: The specific process of step (3) is as follows: According to the number of borehole groups, the pre-reserved reusable sealing devices with corresponding interfaces are fixed side by side on one side of the roadway, and connected to the underground grouting main pipe and the underground grouting main pipe respectively through the grouting hose and the return grout hose. The reusable sealing device is inserted into the predetermined sealing depth of the borehole. The main control PLC controller instructs the fifth and sixth solenoid valves to open, the grouting pump station is started, and the grout is transported to the reusable sealing device of each sealing location through the main grouting pipe and the underground grouting main pipe. The main control PLC controller sends a pressure signal value through the third pressure sensor to control the fifth solenoid valve on the underground grouting main pipe to realize the pipeline opening and closing, so that the underground grouting main pipe starts to open. Maintain a certain grouting pressure. Then, the main control PLC controller issues a sealing command, the first solenoid valve on the first three-way pipe opens, and the first grouting pipe begins to inject grout into the two first and second burrs. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes, stopping the grouting. Then, the third solenoid valve on the second three-way pipe opens, and the grout begins to be injected into the middle section between the first and second burrs through the second grouting pipe until the second pressure sensor detects that the preset grouting pressure value has been reached. The main control PLC controller issues a command to close the third solenoid valve, stopping the grouting. One borehole is then sealed. The same operation process is used to complete the grouting and sealing operation of the other boreholes in the same group.

7. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 6, characterized in that: The specific process of dynamically maintaining pressure for the bladder-type recyclable sealing device in step (5) is as follows: When the borehole deforms and the cross section becomes larger, causing the pressure in the first bladder and / or the second bladder to decrease and be less than the predetermined constant pressure, the first pressure sensor transmits the pressure monitoring data to the main control PLC controller. The main control PLC controller instructs the first solenoid valve to open, and the first grouting pipe begins to inject grout into the two first bladders and the second bladder. When the first pressure sensor detects that the set pressure value has been reached, the first solenoid valve closes and the grouting stops. Similarly, when the pressure drops in the middle section between the first and second grouting bladders due to the continuous seepage of grout into the fissures around the borehole, the third solenoid valve connected to the second grouting pipe opens, and grout begins to be injected into the middle section between the first and second grouting bladders through the second grouting pipe until the second pressure sensor detects that the preset grouting pressure value has been reached. At this point, the main control PLC controller issues a command to close the third solenoid valve and stop the grouting. When the borehole deforms and its effective diameter decreases due to mining, the pressure on the sump and intermediate section increases. When the pressure exceeds the set value, the first and second pressure sensors send pressure change information to the main control PLC controller. The main control PLC controller first sends opening instructions to the fourth, seventh, and eighth solenoid valves. The slurry in the intermediate section of the borehole will first enter the second return slurry hose through the third interface of the second injection pipe and the second three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, the slurry flows back to the mixing tank through the main return slurry pipe. When the value detected by the second pressure sensor reaches the set value, the fourth, seventh, and eighth solenoid valves close. Then, the main control PLC controller first sends an opening command to the second, seventh, and eighth solenoid valves. The slurry in the first and second sacs will first enter the first return slurry hose through the third interface of the first injection pipe and the first three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, the slurry flows back to the mixing tank through the main return slurry pipe. When the value detected by the first pressure sensor reaches the set value, the second, seventh, and eighth solenoid valves close.

8. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 7, characterized in that: The specific process of real-time monitoring of the sealing section and alarm and handling when the sealing section loses pressure in step (5) is as follows: A) Pressure Loss Alarm and Handling: When the burr ruptures and causes instantaneous grout leakage, resulting in a sharp drop in pressure monitored by the first pressure sensor, and the grout injection cannot maintain the pressure of the burr, or when the pressure rises and then drops shortly, the system will stop injecting grout into the burr to prevent a large amount of grout from flowing into the borehole or tunnel, and will issue an audible and visual alarm to indicate that the burr in the borehole has ruptured due to pressure loss. At this time, the burr in the borehole should be recovered first, the ruptured burr replaced, and then the borehole sealed to ensure that the borehole can continue to be pumped normally. B) Alarm and Handling of Pressure Loss in the Middle Section of the Borehole: When a large number of through-type fractures appear in the middle section of the borehole due to mining, resulting in severe slurry loss and a sharp drop in pressure monitored by the second pressure sensor, and the injection of slurry cannot maintain pressure in the middle section, or pressure loss occurs shortly after the pressure rises, the system will stop injecting slurry into the middle section of the borehole to prevent a large amount of slurry from flowing into the borehole or roadway, and issue an audible and visual alarm to indicate that the middle section of the borehole is under pressure. At this time, the gas concentration in a single borehole is measured first. If the gas concentration in a single borehole does not decrease significantly, no action is taken. If the gas concentration in the borehole decreases significantly compared to before, the borehole sealer is retrieved, and the sealing position of the sealer or the density and viscosity of the sealing slurry in the middle section is adjusted. The borehole is then sealed again. If it is still difficult to maintain pressure, it proves that there are serious and large fractures around the borehole that are difficult to seal. The borehole is then closed to prevent the overall gas concentration in the extraction pipeline from decreasing due to gas leakage in the borehole.

9. The method for flexible pressure-maintaining and recyclable intelligent sealing of multiple boreholes in the same roadway according to claim 8, characterized in that: Step (6) The specific process of recovering the bladder-type recyclable sealing device and slurry is as follows: When the drilling and extraction at a certain point meets the standard and the sealing device needs to be recovered, the main control PLC controller first sends an opening command to the fourth, seventh and eighth solenoid valves. The slurry in the middle section of the borehole will first enter the second return slurry hose through the third interface of the second injection pipe and the second three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, it finally flows into the mixing tank on the ground through the main return slurry pipe. When the value monitored by the second pressure sensor reaches the set value, the fourth, seventh and eighth solenoid valves close. Then, the main control PLC controller first sends opening command information to the second solenoid valve, the seventh solenoid valve and the eighth solenoid valve. The slurry in the first and second sacs will first enter the first return slurry hose through the third interface of the first injection pipe and the first three-way pipe, and flow into the downhole return slurry main pipe. Under the action of the return slurry pump station, the slurry flows back to the mixing tank through the main return slurry pipe. When the value monitored by the first pressure sensor reaches the set value, the second solenoid valve, the seventh solenoid valve and the eighth solenoid valve close.

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