A method for draining karst fissure water in an underground mine

Abstract

The application discloses a kind of karst fissure water drainage methods of underground mine, it is related to underground mine construction technical field.In the water outlet of roadway surrounding rock, drill several water guide holes along section radial, the end of water guide hose of water guide hole is located in the drainage ditch of roadway side;The chamber of roadway side is used as water storage pool, and the water in drainage ditch is drained or flows to water storage pool and temporarily stored;Water injection hole is drilled downward in the roadway floor around water storage pool, and water injection hole penetrates aquiclude until target aquifer;High-pressure water injection parameters are set, and water pump in high-pressure water injection device pressurizes water in water storage pool to lower target aquifer, until target aquifer reaches saturation or nearby gushing water is finished, and water pump is stopped after drainage, and control valve is used to close water injection pipe.The way of shallow drainage and deep injection is used to pressurize and drain mine karst fissure water to deep aquifer, so that mine water discharge is not out of well, and mine drainage system is simplified, and a large amount of drainage cost is saved.

Description

Technical Field

[0001] This invention relates to the field of underground mine construction technology, specifically to a method for draining karst fissure water in underground mines. Background Technology

[0002] Rock masses are heterogeneous, discontinuous, and anisotropic bodies. Besides various mineral particles, they contain numerous pores and fissures, which naturally become storage sites for media such as oil, gas, and water. Groundwater is water found in the pores, fissures, and solution fissures of underground rocks and soil. While groundwater is a vital resource for human production and daily life, excessive groundwater can become a significant hazard to underground rock mechanics. For example, during mine construction and production, numerous shafts and tunnels need to be excavated to reach the ore body and form development, preparation, and recovery systems. Consequently, many shafts and tunnels need to traverse various aquifers. Mine water inrush is the process by which aquifers, or atmospheric precipitation, surface water, and goaf water that are recharged by them, under their own static or dynamic pressure, flow into the mining spaces such as shafts and stopes through water-filling channels (fault zones, karst collapse columns, and mining-induced fissures). When a large amount of groundwater flows into the mining area and exceeds the mine's normal drainage capacity, it will cause mine water hazards. If the tunneling project suddenly exposes water-rich structures such as faults, karst formations, fractured zones, aquifers, goaf water, and surface water bodies, it may also trigger mine water inrush accidents. Furthermore, long-term seepage and accumulation of water in mine tunnels and stopes significantly weakens rock strength and reduces its stability, leading to frequent roof falls, spalling, and other deformation and damage to the surrounding rock. Conventional operating methods and technologies become ineffective, posing serious challenges to the safety, cost, and efficiency of tunneling construction. In addition, the presence of large amounts of water underground will deteriorate the working environment, corrode mechanical and electrical equipment, and cause difficulties in resource recovery, resulting in a sharp increase in ore loss and dilution. Currently, water hazards have become one of the five major hazards in mines. Because water sources are difficult to identify and water channels are difficult to detect, the prevention and control of mine water hazards is a primary problem that mines urgently need to solve.

[0003] Given the difficulty in detecting and sealing groundwater sources and water-filling channels, forced drainage is a commonly used method for mine water treatment in underground mining. For mines with small water inflows, forced drainage is acceptable in terms of drainage costs and water control effectiveness. However, for large mines with daily water inflows exceeding 10,000 cubic meters, forced drainage undoubtedly increases production costs. Furthermore, the rock strata in southwestern my country are mostly carbonate rocks, containing abundant karst fissure water. The water outlets are scattered and widely distributed, resulting in large mine water inflows. Mine drainage faces challenges of insufficient drainage capacity and high costs. In addition, current methods of sealing the surrounding rock of mining projects with multiple water inflow points using various grouting techniques are not economically or effectively satisfactory, stemming from the lack of clear water sources and hydraulic channels. The presence of water inflow further complicates on-site construction, creating extremely poor working conditions for personnel. Therefore, how to prevent and control underground karst fissure water has become a critical bottleneck for safe and efficient production in underground mines in southwestern China, necessitating the development of a method for preventing and draining underground mine karst fissure water. Summary of the Invention

[0004] The purpose of this invention is to provide a method for draining karst fissure water in underground mines, solving the problems of insufficient drainage capacity and high cost caused by large water inflow in existing mines.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for draining karst fissure water in underground mines, characterized by the following steps:

[0006] S1. Drainage through water guide holes: Several water guide holes are drilled radially along the cross-section at the water outlet of the surrounding rock of the roadway. Water guide hoses are installed in the water guide holes, and the ends of the water guide hoses are located in the drainage ditch on one side of the roadway.

[0007] S2. Water storage tank: The chambers at the side of the roadway are used as water storage tanks, and the water in the drainage ditch is diverted or flows by gravity to the water storage tank for collection and temporary storage;

[0008] S3. Water injection hole construction: Determine the impermeable layer and the target aquifer located below the stratum where the water outlet of the roadway is located in sequence. Drill water injection holes downwards in the roadway floor around the water storage tank. The water injection holes penetrate the impermeable layer until they reach the target aquifer.

[0009] S4. Installation of high-pressure water injection device: Connect and install the prepared water pump, rubber hose, control valve, water injection pipe, perforated pipe and sealing device in sequence. Insert the water injection pipe and the perforated pipe at the end and the sealing device into the water injection hole, and grout the gap between the water injection pipe and the wall of the water injection hole to prevent high-pressure water backflow.

[0010] S5. Mine water deep layer forced drainage: Set high-pressure water injection parameters, the water pump in the high-pressure water injection device will discharge the water pressure in the water storage tank to the lower target aquifer until the target aquifer reaches saturation or the nearby water inflow is discharged. After the drainage is completed, stop the water pump and use the control valve to close the water injection pipe.

[0011] A further technical solution is that the water guide holes in step S1 are evenly distributed and cover the water inflow area of ​​the surrounding rock of the roadway, with a hole diameter of 34-42mm, a depth of 3-5m, a spacing of 1.0-1.5m, and a row spacing of 2.0-2.5m.

[0012] A further technical solution is that in step S2, the water storage tank is a tunnel side chamber with a length of 5-10m, a width of 5-8m, and a height of 4-5m. The slope of the bottom plate of the water storage tank is designed to be 15-18°, and the surrounding rock is supported by anchor mesh spraying.

[0013] A further technical solution is that the thickness of both the target aquifer and the overlying waterproof layer in step S3 is not less than 1.0m.

[0014] A further technical solution is that in step S3, the water injection holes are arranged within a 10m radius around the water storage tank, with a hole diameter of 90-150mm and an inclination angle of 60-90°.

[0015] A further technical solution is that in step S6, the water pump in the high-pressure water injection device pressurizes and delivers water from the reservoir to the injection pipe using a rubber hose. The water is then pressurized by a sealing device and ejected from the nozzle of the perforated pipe to form a jet. This jet creates a water storage space by hydraulically creating cracks and enlarging existing pores / cracks / solution fissures, thereby pressurizing the water into the target aquifer.

[0016] A further technical solution is that the water injection pipe is made of 2-3m long high-pressure resistant seamless steel pipe connected by threads, with the diameter adapted to the water injection hole. The head of the water injection pipe is connected to a perforated pipe of the same diameter through a sealing device, and a control valve is provided at the tail of the water injection pipe.

[0017] A further technical solution is that the flower tube is located in the water injection hole of the target aquifer, with a length of 1 to 2 m, and the nozzles are arranged in uniform rows along the radial direction of the tube, with 3 to 6 nozzles arranged in each row, a row spacing of 20 to 30 cm, and a nozzle diameter of 1 to 3 cm.

[0018] A further technical solution is that the sealing device is located in the water injection hole of the waterproof layer, threadedly connected between the water injection pipe and the perforated pipe, made of rubber, with a length of 1.0 to 1.5 m, a diameter 1 to 3 cm larger than the water injection pipe, a radial expansion of 2 to 3 cm, and a high pressure resistance of 25 MPa or higher.

[0019] A further technical solution is that in step S5, the water pump injection pressure P ≥ σ max +P w(Formula (1)), where σ max P represents the maximum in-situ stress of the target aquifer. w This indicates the pore water pressure of the target aquifer.

[0020] A further technical solution is that the water pump is equipped with a pressure gauge and a flow meter, with a pressure range of not less than 30 MPa and a flow range of not less than 300 m³ / h. 3 / h, the standard for the aquifer to reach saturation is a sharp increase in pump pressure and a sharp decrease in the flow rate displayed by the flow meter.

[0021] Compared with existing technologies, the beneficial effects of this invention are as follows: It employs a shallow-drainage, deep-injection groundwater treatment method, using water guide holes and flexible hoses to introduce karst fissure water from the surrounding rock of the roadway into drainage ditches, avoiding large-scale water seepage at the mining face and improving the working environment for underground construction. The water is then diverted to a reservoir for subsequent high-pressure injection by water pumps. The use of a sealing device allows the mine water in the perforated pipe to be ejected in jet form, creating a water storage space through hydraulic fracturing and enlarging of fissures, thereby pressurizing the mine water into the target aquifer. This method expands the flow range of the mine water within the target aquifer and improves its water storage capacity. After being pressurized by the high-pressure injection device, the water diffuses farther and over a larger range than traditional methods that use static pressure to guide water into underground fissures. This method achieves mine water discharge without leaving the well, simplifying the mine drainage system and saving significant drainage costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the engineering layout and equipment structure of the present invention;

[0023] Figure 2 A schematic diagram of drainage holes in the water-bearing area of ​​the surrounding rock in the tunnel.

[0024] Figure 3 This is a schematic diagram of the flower tube structure;

[0025] In the diagram: 1-Water-bearing surrounding rock layer, 2-Karst fissure water, 3-Aquitard, 4-Target aquifer, 5-Tunnel, 6-Drainage ditch, 7-Water guide hole, 8-Water intake hose, 9-Water storage tank, 10-Water pump, 11-Rubber hose, 12-Control valve, 13-Water injection hole, 14-Sealing slurry, 15-Water injection pipe, 16-Sealing device, 17-Perforated pipe, 18-Nozzle. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] Figure 1 , Figure 2 This diagram illustrates the engineering layout, high-pressure water injection device, and shallow-deep water drainage of the mine. During the construction of the tunnel 5 in the water-bearing surrounding rock layer 1, a large amount of karst fissure water 2, hidden within the stratum 1, floods the working space, worsening the working environment and the stability of the surrounding rock. This invention addresses this by drilling a certain number of water guide holes 7, with a diameter of 34–42 mm, a depth of 3–5 m, a spacing of 1.0–1.5 m, and a row spacing of 2.0–2.5 m, covering the area where the water flows out. The karst fissure water 2 drained through the water guide holes 7 on the roof of the tunnel 5 is guided by a water-draining hose 8 laid on the tunnel wall to a drainage ditch 6 at the tunnel side. The karst fissure water 2 drained through the water guide holes 7 on the tunnel side flows by gravity into the drainage ditch 6.

[0028] The existing chamber or a newly built chamber is used as a water storage tank 9, and the surrounding rock support is strengthened by anchor mesh spraying technology. The dimensions of the water storage tank 9 are 5-10m long, 5-8m wide, 4-5m high, and the bottom slope is 15-18°. The water in the drainage ditch 6 eventually flows into the water storage tank 9 for storage.

[0029] Based on the mine's hydrogeological and engineering geological conditions, an aquifer 3 with a thickness of not less than 1m below the surrounding rock layer 1, capable of isolating and storing water, and a target aquifer 4 were identified. A water injection hole 13 with an angle of 60-90° was drilled within a 10m radius of the reservoir 9 using a geological drilling rig. The water injection hole 13 penetrated the aquifer 3 and reached the target aquifer 4. After drilling was completed, pneumatic cleaning of the hole was carried out promptly.

[0030] A high-pressure water injection device is installed inside the water injection hole 13, including a water pump 10, a rubber hose 11, a control valve 12, a water injection pipe 15, a sealing device 16, and a perforated pipe 17; the water pump 10 is equipped with a pressure gauge and a flow meter, with a maximum pressure and flow rate of not less than 30 MPa and 300 m³ / h, respectively. 3 / h. The water injection pipe 15 is made of 2-3m long seamless steel pipes with high pressure resistance, connected by threads, with a diameter of 60-120mm; the head of the water injection pipe 15 is connected to the equal diameter perforated pipe 17 through a sealing device 16. The sealing device 16 and the perforated pipe 17 are located in the water injection holes 13 at the 3rd layer of the aquitard and the 4th layer of the target aquifer, respectively; the sealing device 16 is 1.0-1.5m long, 1-3cm larger in diameter than the water injection pipe, has a radial expansion of 2-3cm, and can withstand a high pressure of 25MPa or more.

[0031] After installation, sealing grout 14 is injected between the water injection pipe 15 and the water injection hole 13 for sealing. Finally, the water injection pressure and flow rate are set according to the maximum ground stress and pore water pressure of the target aquifer 4. The control valve is opened and the mine water in the reservoir 9 is injected deeply and forcefully discharged. The mine water in the reservoir 9 is pumped through the rubber hose 11 to the water pump 10 for pressurization and then transported to the water injection pipe 15. Finally, it is injected into the target aquifer 4 through the sealing device 16 and the nozzle 18 of the perforated pipe 17. During the high-pressure water injection process, the sealing device 16 seals the water injection hole of the perforated pipe section through its own expansion, so that the mine water sprayed from the nozzle 18 of the perforated pipe 17 is pressurized into high-pressure water. Through hydraulic cracking and enlarging the pores / fractures / solutions, a water storage space is formed, which expands the diffusion range of the mine water in the target aquifer 4 and increases the water storage capacity of the target aquifer. After the water injection is completed, the water pump 10 is turned off first, and then the control valve 12 is closed.

[0032] Figure 3 The diagram shows the structure of the perforated pipe. The perforated pipe 17 is installed in the water injection hole 13 at the fourth level of the target aquifer. The length of the perforated pipe is 1 to 2 m. The nozzles are arranged in rows evenly along the radial direction of the pipe, with 3 to 6 nozzles in each row and a row spacing of 20 to 30 cm. The nozzle diameter is 1 to 3 cm.

[0033] The steps of the present invention are described below with reference to an embodiment:

[0034] The tunneling project in a phosphate mine is mainly located in the upper (∈1z+∈1y) carbonate karst fissure aquifer of the Lower Cambrian Zhongyicun Formation and Yuhucun Formation. The tunnel is buried at a depth of 240m, with a net width of 4.5m, wall heights of 2.0m and 2.2m, and an arch height of 1.5m. The surrounding rock lithology is mainly dolomite and phosphorite. The project revealed well-developed karst fissure water in the surrounding rock, with large-scale water seepage occurring throughout the entire tunnel cross-section, and a maximum inflow of 200m³. 3 The tunnel construction and drainage are difficult, and the working environment is extremely harsh. The aquifer is approximately 153m thick, with a unit yield of 0.002–0.141 L / s·m and a permeability coefficient of 0.004–0.15 m / d, classifying it as a moderately water-bearing aquifer. Below this aquifer is the lower part of the Lower Cambrian Yuhucun Formation (∈1y1), an impermeable layer 10m thick, composed of shale, siltstone, and argillaceous dolomite. Below the impermeable layer is the Upper Sinian Dengying Formation (Z2dn), a carbonate karst fissure aquifer with dolomite lithology, greater than 200m thick. This aquifer has a maximum in-situ stress of 16 MPa and a pore water pressure of 0.6 MPa.

[0035] (S1) Drainage through water guide holes: Using a YT28 rock drill, water guide holes 7 with a diameter of 40mm, a depth of 3.0m, a spacing of 1.5m, and a drainage spacing of 2.0m are drilled throughout the entire cross-section of tunnel 5 to centrally drain the karst fissure water 2 in the surrounding rock 1. The water drained through the water guide holes 7 at the top of the tunnel is guided along the tunnel wall by a water-guiding hose 8 to the drainage ditch 6 on the right side of tunnel 5, and the water drained through the water guide holes 7 at the tunnel side flows by gravity to the drainage ditch 6 on the right side of tunnel 5;

[0036] (S2) Water collection in the reservoir: A new arched chamber with a length of 10m, a width of 5m, a height of 4m, and a bottom slope of 18° is excavated on the right side of the tunnel to be used as a water storage tank 9. Water discharged from the surrounding water outlets is diverted to the water storage tank 9 through the drainage ditch 6 and collected and temporarily stored.

[0037] (S3) Water Injection Hole Construction: The lower part of the Yuhucun Formation (∈1y1) of the Lower Cambrian System and the carbonate rock karst fissure aquifer of the Dengying Formation (Z2dn) of the Upper Sinian System were selected as the aquifer 3 and the target aquifer 4. A vertical water injection hole 13 with a depth of 145m and a diameter of 100mm was drilled downward at the bottom of the tunnel at the entrance of the reservoir using a ZDY3500L(A) hydraulic geological drilling rig. The water injection hole penetrates its own aquifer section of 130m, the aquifer section of 10m and the target aquifer section of 5m. The hole was cleaned in time after the drilling was completed.

[0038] (S4) Installation of high-pressure water injection device: Assemble and install the water pump 10 of model BZW200 / 31.5, 90mm rubber hose 11, control valve 12, water injection pipe 15 with continuous extension of 2m sections, 2m long perforated pipe 17 (nozzle 18 with diameter of 1cm, 6 in each row radially, row spacing of 20-30cm) and 1.5m long sealing device 16 of model ZF-A30 on site. Then seal the gap between the water injection pipe 15 and the wall of the water injection hole 13 with cement grout 14.

[0039] (S5) Forced drainage of deep mine water: Adjust the pressure gauge and flow meter of water pump 10, and set the injection pressure and injection flow rate to 25MPa and 200m based on formula (1) and the maximum inflow rate, respectively. 3 / h, the water pressure in the reservoir 9 is discharged to the carbonate rock karst fissure aquifer 4 of the Dengying Formation (Z2dn) of the Upper Sinian System using a high-pressure water injection device until the water absorption of the aquifer in the discharge area reaches saturation or the nearby gushing water is discharged. After the water injection is completed, the water pump 10 is stopped and the water injection pipe 15 is closed by the control valve 12.

[0040] If a sharp increase in pressure gauge readings and a low flow count are observed during water injection, it indicates that the water absorption in the karst fissure aquifer area of ​​the Upper Sinian Dengying Formation (Z2dn) carbonate rock is close to saturation. At this point, a new reservoir should be built at an interval of 200-500m from the original water injection site, and the above steps (S1) to (S5) should be repeated to carry out shallow diversion and deep injection of mine water.

[0041] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope of this disclosure. More specifically, various modifications and improvements can be made to the components or layouts within the scope of this disclosure, the drawings, and the claims. Besides modifications and improvements to the components or layouts, other uses will be apparent to those skilled in the art.

Claims

1. A method for draining karst fissure water in underground mines, characterized in that... The steps are as follows: S1. Drainage through water guide holes: Several water guide holes are drilled radially along the cross-section at the water outlet of the surrounding rock of the roadway. Water guide hoses are installed in the water guide holes, and the ends of the water guide hoses are located in the drainage ditch on one side of the roadway. S2. Water storage tank: The chambers at the side of the roadway are used as water storage tanks, and the water in the drainage ditch is diverted or flows by gravity to the water storage tank for collection and temporary storage; S3. Water injection hole construction: Determine the impermeable layer and the target aquifer located below the stratum where the water outlet of the roadway is located in sequence. Drill water injection holes downwards in the roadway floor around the water storage tank. The water injection holes penetrate the impermeable layer until they reach the target aquifer. S4. Installation of high-pressure water injection device: Connect and install the prepared water pump, rubber hose, control valve, water injection pipe, perforated pipe and sealing device in sequence. Insert the water injection pipe and the perforated pipe at the end and the sealing device into the water injection hole, and grout the gap between the water injection pipe and the wall of the water injection hole to prevent high-pressure water backflow. S5. Mine water deep layer forced drainage: Set high pressure water injection parameters, the water pump in the high pressure water injection device will discharge the water pressure in the water storage tank to the lower target aquifer until the target aquifer water absorption reaches saturation or the nearby water inflow is discharged. After the drainage is completed, stop the water pump and use the control valve to close the water injection pipe. In step S5, the high-pressure water injection device uses a rubber hose to pressurize and transport water from the reservoir to the injection pipe. The water is then pressurized by a sealing device and sprayed out from the nozzle of the perforated pipe to form a jet. This jet creates a water storage space by hydraulically creating cracks and enlarging existing holes / cracks / solutions, thereby pressurizing the water into the target aquifer. The water injection pipe is made of 2-3m long high-pressure resistant seamless steel pipe connected by threads. The diameter is adapted to the water injection hole. The head of the water injection pipe is connected to a perforated pipe of the same diameter through a sealing device. The tail of the water injection pipe is equipped with a control valve. In step S5, the water pump injection pressure P ≥ σmax + Pw, where σmax represents the maximum ground stress of the target aquifer and Pw represents the pore water pressure of the target aquifer.

2. The method for draining karst fissure water in underground mines according to claim 1, characterized in that: In step S1, the water guide holes are evenly distributed and cover the water inflow area of ​​the surrounding rock in the roadway. The diameter of the water guide holes is 34-42mm, the depth is 3-5m, the spacing is 1.0-1.5m, and the row spacing is 2.0-2.5m.

3. The method for draining karst fissure water in underground mines according to claim 1, characterized in that: In step S2, the water storage tank is a tunnel chamber with a length of 5-10m, a width of 5-8m, and a height of 4-5m. The slope of the bottom plate of the water storage tank is designed to be 15-18°, and the surrounding rock is supported by anchor mesh spraying.

4. The method for draining karst fissure water in underground mines according to claim 1, characterized in that: In step S3, the thickness of both the target aquifer and the overlying aquitard layer is not less than 1.0m.

5. A method for draining karst fissure water in underground mines according to claim 1, characterized in that: In step S3, the water injection holes are arranged within a 10m radius around the water storage tank, with a hole diameter of 90-150mm and an inclination angle of 60-90°.

6. A method for draining karst fissure water in underground mines according to claim 1, characterized in that: The perforated tube is located in the water injection hole of the target aquifer, with a length of 1 to 2 m. The nozzles are arranged in rows evenly along the radial direction of the tube, with 3 to 6 nozzles in each row, a row spacing of 20 to 30 cm, and a nozzle diameter of 1 to 3 cm.

7. A method for draining karst fissure water in underground mines according to claim 1, characterized in that: The sealing device is located in the water injection hole of the waterproof layer, and is threaded between the water injection pipe and the perforated pipe. It is made of rubber, with a length of 1.0 to 1.5 m, a diameter 1 to 3 cm larger than the water injection pipe, a radial expansion of 2 to 3 cm, and a high pressure resistance of 25 MPa or higher.

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