Ground negative pressure feeding system for water inrush interception and sealing in deep buried tunnels

Abstract

This invention discloses a ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels. The system includes a pipeline, an adjustable-speed jet pump, a directional tunneling borehole casing, and a hopper. A directional tunneling borehole communicating with the water-bearing tunnel is drilled on the ground. The second end of the directional tunneling borehole casing is inserted into the borehole and communicates with the fluid in the water-bearing tunnel. The adjustable-speed jet pump is positioned on the ground, with its outlet connected to the first end of the pipeline, and the second end of the pipeline connected to the first end of the directional tunneling borehole casing. The system provided in this invention optimizes the flow velocity and mixing ratio of water carrying sand and gravel aggregate, effectively avoiding common problems in traditional feeding methods such as borehole blockage and air column formation, achieving the goals of high efficiency, safety, and economy in emergency treatment of water inrush in deeply buried tunnels.

Description

Technical Field

[0001] This invention relates to the field of water inrush sealing and control technology for deep-buried tunnels and roadways. Specifically, it relates to a ground negative pressure material feeding system for water inrush interception and sealing in deep-buried tunnels. Background Technology

[0002] With the continuous expansion of underground space development and utilization, projects such as traffic tunnels, mine roadways, and water conservancy tunnels are increasing. Some regions have abundant groundwater systems, and the strata may contain water-conducting channels such as faults, fissures, and karst caves. When these underground projects traverse areas with complex geological structures, they face a high risk of sudden water inrush, meaning that when construction disturbs these areas, groundwater may surge into the tunnels or roadways under pressure. From an engineering construction perspective, due to the limitations of preliminary geological surveys, technicians may not be able to fully and accurately grasp the underground geological and hydrological conditions, resulting in insufficient preventative measures against sudden water inrush during construction.

[0003] Sudden water inrushes can cause casualties, equipment damage, and project shutdowns, resulting in significant losses for construction companies and society. Economically, sudden water inrushes not only increase the direct costs of project mitigation but also lead to delays, indirectly increasing the overall project cost. Furthermore, the outflow of large amounts of untreated groundwater can adversely affect the surrounding ecological environment and water resource balance. To ensure the safety and smooth progress of underground engineering projects, protect the environment, and save costs, intercepting and sealing sudden water inrushes in tunnels and roadways has become a necessary option.

[0004] Surface-directed borehole drilling and material feeding for interception and sealing is the primary task in controlling water inrushes and gushing water in deep-buried tunnels and roadways. It is also one of the key tasks in forming an accumulation body within the water-gushing tunnel to reduce the cross-sectional area of ​​the water. Water inrush and gushing water control in deep-buried tunnels and roadways is usually an emergency rescue project, and the efficiency of surface material feeding directly affects the efficiency of emergency rescue. Traditional feeding methods, such as dry feeding of aggregate or simultaneous injection of aggregate and water at the borehole opening, cannot efficiently form an accumulation body within the water-gushing tunnel or roadway. This often leads to aggregate blockage of the borehole, requiring time and resources for repeated borehole cleaning. In more serious cases, air columns can form within the borehole, causing aggregate to spray out of the opening under pressure, severely hindering the smooth progress of emergency water sealing work in deep-buried tunnels and roadways. Therefore, developing a surface negative pressure material feeding system for water inrush interception and sealing in deep-buried tunnels is of great significance for ensuring rapid, efficient, and safe control of water inrushes and gushing water in deep-buried tunnels and roadways. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this invention is to provide a ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels. This system effectively avoids common problems in traditional feeding methods, such as hole blockage and air column formation, by optimizing the flow velocity and mixing ratio of water carrying sand and gravel aggregates, thus achieving the goals of high efficiency, safety, and economy in emergency treatment of water inrush in deeply buried tunnels.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels includes a pipeline, an adjustable-speed jet pump, a directional tunneling borehole casing, and a hopper. A directional tunneling borehole communicating with the water-bearing tunnel is drilled on the ground. The second end of the directional tunneling borehole casing is inserted into the borehole and communicates with the fluid in the water-bearing tunnel. The adjustable-speed jet pump is located on the ground, with its outlet connected to the first end of the pipeline, and the second end of the pipeline connected to the first end of the directional tunneling borehole casing. The outlet of the hopper is connected to and communicates with the pipeline, and the hopper contains graded sand and gravel aggregate. The adjustable-speed jet pump supplies high-speed water into the pipeline. The graded sand and gravel aggregate in the hopper enters the pipeline through the outlet and mixes with the high-speed water before entering the directional tunneling borehole casing. The high-speed water carries the graded sand and gravel aggregate into the water-bearing tunnel, forming an aggregate accumulation. The adjustable-speed jet pump is used to control the speed of water flow in the pipeline, so that the water carries the graded sand and gravel aggregate at a uniform speed in the water delivery pipeline. The pipeline is the water delivery channel on the ground, and is made of national standard 16Mn seamless steel pipe with wear-resistant material lining. Its wall thickness and pipe diameter are calculated and determined based on the aggregate particle size and flow velocity.

[0008] The aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels comprises a pipeline divided into a horizontal section parallel to the ground, a curved section, and a straight section perpendicular to the ground. Along the direction from the first end to the second end of the pipeline, the horizontal, curved, and straight sections are sequentially connected and fluid-conducting. The outlet of the hopper is fluid-conducting with the middle section of the horizontal section. When the adjustable-speed jet pump drives water to flow in the pipeline, a negative pressure is formed at the connection between the outlet of the hopper and the pipeline. Simultaneously, the graded sand and gravel aggregate in the hopper falls under its own weight, making it easier for the aggregate to be drawn into the pipeline and flow forward with the water.

[0009] The aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels also includes a pressure relief valve arranged on the straight section of the pipeline.

[0010] The aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels further includes a baffle, a baffle support, a connecting rod, and a first connecting valve. The first connecting valve is a gate valve, comprising a valve stem and a gate connected to the second end of the valve stem. The first end of the baffle extends into the cavity of the pipeline, with the baffle surface perpendicular to the direction of water flow within the pipeline. The second end of the baffle passes through the pipe wall of the pipeline and is hinged to the first end of the connecting rod outside the cavity of the pipeline. The second end of the connecting rod is hinged to the first end of the valve stem; the baffle bracket is fixedly installed on the outside of the pipe wall of the pipeline, and the baffle bracket is hinged to the middle of the baffle, the hinge axis of the baffle bracket and the baffle is perpendicular to the extension direction of the pipeline; the first connecting valve is installed on the passage between the outlet of the hopper and the pipeline, and the gate of the first connecting valve directly controls the opening and closing of the passage; when the water flow in the pipeline pushes the baffle, the passage between the outlet of the hopper and the pipeline is connected.

[0011] In the aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deep buried tunnels, the directional tunnel borehole is drilled to a depth of 1m below the bottom plate of the water-bearing tunnel during drilling.

[0012] The aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels comprises a directional tunneling borehole casing consisting of a first directional tunneling borehole casing and a second directional tunneling borehole casing. The upper end of the first directional tunneling borehole casing is connected to the pipeline, and the lower end of the first directional tunneling borehole casing is connected to the upper end of the second directional tunneling borehole casing. The inner diameter of the first directional tunneling borehole casing is larger than that of the second directional tunneling borehole casing. The first directional tunneling borehole casing extends vertically downwards from the ground to a depth of 5-15m below the bedrock in the strata, and the lower end of the second directional tunneling borehole casing is flush with the top plate of the water-bearing tunnel. During drilling, the directional tunneling borehole is drilled in two stages. The first stage drills to a depth of 5-15m below the bedrock in the bottom layer, at which point the first directional tunneling borehole casing is lowered. The second stage drills to a depth of 1m below the bottom plate of the water-bearing tunnel, at which point the second directional tunneling borehole casing is lowered. Two-stage drilling can accelerate the drilling rate and improve the quality of the borehole. In addition, directional drilling to a depth of 1m below the floor of the water-bearing tunnel allows construction personnel to easily check the solidity of the floor and increases the contact area between the injected graded sand and gravel aggregate and the floor. This creates a pile-like structure at the bottom of the aggregate accumulation, which, when inserted into the floor of the water-bearing tunnel, improves the aggregate accumulation's resistance to water flow impact.

[0013] The aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels involves the following steps: During operation, the graded sand and gravel aggregate contained in the hopper enters the pipeline and mixes with water in the pipeline to form a sand-carrying water flow. The flow velocity of the sand-carrying water flow in the pipeline is greater than or equal to the free descent rate of the graded sand and gravel aggregate in still water. After entering the water-bearing tunnel, the graded sand and gravel aggregate in the sand-carrying water flow accumulates on the bottom slab of the tunnel to form an aggregate deposit.

[0014] The aforementioned ground negative pressure material feeding system for intercepting and sealing water inrush in deeply buried tunnels requires that the velocity of the sand-carrying water flow entering the inrush tunnel be 1.3 to 2.0 times the velocity of the water inrush within the tunnel. There is a significant difference in velocity between the water flow without graded aggregate and the sand-carrying water flow in the pipeline. If the velocity of the sand-carrying water flow is too high, the graded aggregate may not be able to form an aggregate mass in the inrush tunnel; if the velocity is too low, pipe blockage and other problems may easily occur. Therefore, the velocity of the sand-carrying water flow entering the inrush tunnel should be 1.3 to 2.0 times the velocity of the water inrush within the tunnel. This is because when the flow velocity of the sand-carrying water entering the water-bearing tunnel is too low, the water in the tunnel may wash away the graded sand and gravel aggregates, making it difficult to form aggregate deposits on the tunnel floor; while when the flow velocity of the sand-carrying water entering the water-bearing tunnel is too high, the sand-carrying water will impact the tunnel floor with a greater force, easily dispersing the already formed aggregate deposits.

[0015] The aforementioned ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels further includes flow velocity monitoring meters and pressure monitoring meters arranged sequentially from the first end to the second end of the pipeline, with the flow velocity monitoring meters located on the pipeline downstream of the hopper. The pressure monitoring meters have a range of -1 MPa to 10 MPa. A negative value indicates normal operation, while a positive value indicates abnormal operation, suggesting a risk of blockage or that blockage has already occurred. The pressure monitoring gauge is also equipped with an alarm flashing light. When the pressure monitoring gauge measures a pressure in the pipeline greater than 1 MPa, the alarm flashing light will flash, indicating that the borehole is blocked or has been blocked. At this time, the hopper discharge port, water storage pump, and adjustable speed jet pump can be shut down, and the pressure relief valve can be opened to prevent pipeline and borehole pressure buildup accidents. At the same time, it can quickly handle pipe and borehole blockage accidents, ensuring that the graded sand and gravel aggregate is smoothly transported through the surface directional tunnel borehole to the water inflow tunnel, forming an aggregate accumulation body and reducing the water flow cross-section. The function of the flow velocity monitoring gauge is to monitor the flow velocity of the water carrying the graded sand and gravel aggregate in the pipeline in real time, ensuring that the flow velocity of the water carrying the graded sand and gravel aggregate is not lower than the free fall velocity of the graded sand and gravel aggregate in still water. When the flow velocity of the sand-carrying water is low, the flow velocity of the sand-carrying water can be increased by the adjustable speed jet pump.

[0016] The aforementioned ground negative pressure material feeding system for intercepting and sealing water inrush in deeply buried tunnels uses graded sand and gravel aggregates that are mixtures of sand and gravel with particle sizes ranging from 1mm to 50mm and containing various particle sizes, and whose porosity is 10% to 20%. The graded sand and gravel aggregates are composed of sand and gravel of different particle sizes from 1mm to 50mm mixed with a certain solid-liquid ratio, which is determined based on the porosity of the graded sand and gravel aggregates. When the porosity of the graded sand and gravel aggregates exceeds this range, its physical and mechanical properties and impermeability are poor, failing to meet the requirements for intercepting and sealing water inrush in deeply buried tunnels.

[0017] The technical solution of the present invention achieves the following beneficial technical effects:

[0018] 1. The ground negative pressure feeding system provided in this invention, by adjusting the water flow velocity and the mixing ratio of sand and gravel aggregates, ensures that the flow velocity of the sand-carrying water is not lower than the free settling velocity of the aggregates, greatly reducing the risk of hole blockage and air column formation. This significantly improves the success rate and efficiency of surface directional drilling for the feeding of graded sand and gravel aggregates. Simultaneously, it can quickly form aggregate accumulation bodies in water-bearing tunnels and roadways, reducing the water flow cross-section and laying the foundation for subsequent grouting and reinforcement work. In the event of pipe or hole blockage, the pressure relief valve of the ground negative pressure feeding system can quickly depressurize the pipeline, saving time in handling blockage accidents and ensuring the smooth progress of emergency water plugging operations.

[0019] 2. The ground negative pressure feeding system of this invention is simple in design and easy to operate, facilitating rapid deployment and use under various complex geological conditions. Through automated monitoring and adjustment functions, users can control the feeding process in real time, ensuring optimal feeding results. Simultaneously, the positive pressure monitoring and early warning function ensures the safety of the feeding operation.

[0020] 3. The ground negative pressure feeding system provided in this invention significantly reduces the cost of downtime and rework caused by sudden water inrush during construction, while reducing reliance on manpower and material resources, improving feeding efficiency, and reducing the total project cost. Attached Figure Description

[0021] Figure 1 A cross-sectional view of the layout of the ground negative pressure feeding system of the present invention;

[0022] Figure 2 A schematic diagram of the automatic feeding device of the ground negative pressure feeding system in this invention.

[0023] The reference numerals in the diagram are as follows: 1-Water storage pump; 2-Adjustable speed jet pump; 3-Pipeline; 31-Horizontal section; 32-Bend section; 33-Straight section; 4-First connecting valve; 41-Valve stem; 5-Graded sand and gravel aggregate; 6-Hopper; 7-Flow velocity monitoring gauge; 8-Pressure monitoring gauge; 9-Pressure relief valve; 10-Directional tunnel borehole casing; 101-First directional tunnel borehole casing; 102-Second directional tunnel borehole casing; 11-Directional tunnel borehole; 12-Water inrush tunnel; 13-Aggregate accumulation; 14-Second connecting valve; 15-Baffle; 16-Baffle support; 17-Connecting rod. Detailed Implementation

[0024] In this embodiment, graded sand and gravel aggregate is used to intercept and seal the water inrush tunnel. Based on field measurements, graded sand and gravel aggregate with a porosity of 14% is selected. The solid-liquid ratio of the graded sand and gravel aggregate is: fine sand (1-3mm): small stones (5-10mm): medium stones (10-30mm): large stones (30-50mm) = 1:1:2:1. In other embodiments, other aggregates with different particle sizes from 1mm to 50mm can also be used, mixed with a certain solid-liquid ratio, which is determined based on the porosity of the graded sand and gravel aggregate.

[0025] like Figure 1This is a cross-sectional view of the ground negative pressure feeding system in this embodiment. As shown in the figure, the ground negative pressure feeding system in this embodiment includes a water storage pump 1, a pipeline 3, and a directional tunneling borehole casing 10, which are connected in sequence and have fluid conduction. The first end of the pipeline 3 is connected to the drain outlet of the water storage pump 1, and the pipeline 3 is connected to the first end of the directional tunneling borehole casing 10 through a second connecting valve 14 located at the second end of the pipeline 3. The pipeline 3 is divided into a horizontal section 31 parallel to the ground, a bend section 32, and a straight section 33 perpendicular to the ground. Along the direction from the first end to the second end of the pipeline 3, the horizontal section 31, bend section 32, and straight section 33 are sequentially connected and allow fluid flow. The pressure relief valve 9 is arranged on the straight section 33 of the pipeline 3. The outlet of the hopper 6 is fluidly connected to the middle of the horizontal section 31. The distance between the outlet of the hopper 6 and the adjustable-speed jet pump 2 is less than the distance between the outlet of the hopper 6 and the water outlet of the horizontal section 31. This smaller distance facilitates rapid water contact and... The downstream horizontal section 31 of the impact-graded sand and gravel aggregate 5 is relatively long, which is conducive to the thorough mixing of water flow and graded sand and gravel aggregate 5. In actual use, the horizontal section 31 can be set horizontally or gradually rise along the direction of water flow. The angle between the horizontal section 31 and the horizontal plane is 0° to 5°. When the flow fluctuation of the adjustable speed jet pump 2 is insufficient to push the graded sand and gravel aggregate 5, the graded sand and gravel aggregate 5 can slide along the pipeline to the pump port of the adjustable speed jet pump 2. When the flow recovers, it can quickly push the graded sand and gravel aggregate 5 to remix with the water flow, avoiding the accumulation of graded sand and gravel aggregate 5. The second end of the directional tunneling borehole casing 10 passes through the directional tunneling borehole 11 that connects the ground and the water inflow tunnel 12 and extends to the top plate of the water inflow tunnel 12. The inner cavity of the directional tunneling borehole casing 10 is connected to the water inflow tunnel 12.

[0026] Along the direction from the first end to the second end of the pipeline 3, the pipeline 3 is sequentially equipped with an adjustable speed jet pump 2, a hopper 6, a flow rate monitoring meter 7 for measuring the fluid flow rate in the pipeline 3, a pressure monitoring meter 8 for measuring the pressure in the pipeline 3, and a pressure relief valve 9. The discharge port at the lower end of the hopper 6 is connected to the middle of the horizontal section 31 of the pipeline 3 through a first connecting valve 4.

[0027] In pipeline 3, the graded sand and gravel aggregate 5 will mix with water to form a sand-carrying water flow. The adjustable-speed jet pump 2 is used to control the speed of the water flow in pipeline 3, so that the water carrying the sand and gravel aggregate flows at a uniform speed in the water delivery pipeline. That is, the flow velocity of the sand-carrying water flow in pipeline 3 can be adjusted by the adjustable-speed jet pump 2. However, no matter how it is adjusted, the minimum velocity of the sand-carrying water flow must be greater than or equal to the descent velocity of the sand and gravel aggregate in still water.

[0028] In this embodiment, when using the above-mentioned graded sand and gravel aggregate with the aforementioned solid-liquid ratio, the flow velocity of the sand-carrying water is controlled at 165 m / s. 3 / h~175m 3 The implementation effect is ideal when the pipe is / h, and pipe blockage is less likely to occur in pipeline 3.

[0029] When the adjustable speed jet pump 2 drives the water flow in the pipeline 3, a negative pressure is formed at the connection between the discharge port of the hopper 6 and the pipeline. At the same time, under the action of the weight of the graded sand and gravel aggregate, the graded sand and gravel aggregate is more easily sucked into the pipeline and flows forward with the water flow.

[0030] Furthermore, in order to enable the discharge amount of hopper 6 to be automatically controlled, an automatic feeding control device is used in the ground negative pressure feeding system in this embodiment. The automatic feeding control device includes baffle 15, baffle bracket 16, connecting rod 17 and first connecting valve 4. In this embodiment, the first connecting valve 4 is a gate valve, which includes a valve stem 41 and a gate connected to the second end of the valve stem 41. The first end of the baffle 15 extends into the cavity of the pipe 3, and the surface of the baffle is perpendicular to the direction of water flow in the pipe 3. The second end of the baffle 15 passes through the pipe wall of the pipe 3 and is hinged to the first end of the connecting rod 17 outside the cavity of the pipe 3. The second end of the connecting rod 17 is hinged to the first end of the valve stem 41. The baffle bracket 16 is fixedly installed outside the pipe wall of the pipe 3, and the baffle bracket 16 is hinged to the middle of the baffle 15. The hinge axis of the baffle bracket 16 and the baffle 15 is perpendicular to the extension direction of the pipe 3. The first connecting valve 4 is installed in the passage between the outlet of the hopper 6 and the pipe 3, and the gate of the first connecting valve 4 directly controls the opening and closing of the passage.

[0031] A sealing ring is provided at the location where the baffle 15 passes through the pipe wall of the pipeline 3. The sealing ring is fitted around the baffle 15 to prevent water in the pipeline 3 from leaking from the location where the baffle 15 passes through.

[0032] like Figure 2As shown, when the water flow in the pipeline 3 pushes the baffle 15, the baffle 15 rotates around the hinge axis between itself and the baffle support 16. Through the transmission action of the connecting rod 17, the first end of the valve stem 41 of the first connecting valve 4 moves away from the hopper 6. At this time, the valve stem 41 "pulls" the gate plate out of the passage between the outlet of the hopper 6 and the pipeline 3, opening the outlet of the hopper 6 and connecting it to the pipeline 3. When there is no water flow in the pipeline 3 pushing the baffle 15, the passage between the outlet of the hopper 6 and the pipeline 3 is closed. In this way, the feeding of graded sand and gravel aggregate can be automated. That is, when the adjustable speed jet pump 2 is turned on and there is water flow in the pipeline 3, the outlet of the hopper 6 automatically opens. The greater the water flow velocity, the greater the opening degree of the first connecting valve, and the greater the amount of graded sand and gravel aggregate 5 fed.

[0033] The installation and operation of the ground negative pressure feeding system mainly include the following steps:

[0034] Step 1: Construct Surface Directional Through-Drilling Hole 11. Surface directional through-drilling hole 11 penetrates all strata between the surface and the water inrush tunnel. During construction, the surface directional through-drilling hole starts from the surface and drills downwards, ending 1m into the floor of the water inrush tunnel.

[0035] In this embodiment, the water-bearing tunnel has a burial depth of 300m. The surface directional tunneling borehole structure is constructed in two stages. The first stage uses a 311mm drill bit, drilling from the surface to a depth of 70-80m underground (5-15m below bedrock). After the first stage is completed, a first directional tunneling casing 101 with an outer diameter of 244.5mm is lowered into the borehole. The second stage uses a 216mm drill bit for direct tunneling, drilling to a depth of 1m below the bottom slab of the water-bearing tunnel 12. After the second stage is completed, a second directional tunneling casing 102 with an outer diameter of 177.8mm is lowered into the second stage. The inner diameter of the first directional tunneling casing 101 is larger than the inner diameter of the second directional tunneling casing 102. In some other embodiments, the drilling depth of the first borehole varies depending on the depth of bedrock distribution in the strata, but in general, the first borehole should be drilled to a depth of 5 to 15 meters below the bedrock.

[0036] Step 2: Lay the ground pipeline 3. Lay an overhead 16Mn wear-resistant seamless steel pipe with a wall thickness of t = 8mm and an inner diameter of r = 152mm at the ground material feeding site. The overhead height of pipeline 3 is 0.5m (meaning the vertical distance between the horizontal section of pipeline 3 and the ground is 0.5m).

[0037] Step 3: Install the water storage pump 1 and the adjustable speed jet pump 2. Connect the drain outlet of the water storage pump 1 to the first end of the pipeline 3. Install the adjustable speed jet pump 2, the hopper 6, the flow rate monitoring gauge 7, the pressure monitoring gauge 8, and the pressure relief valve 9 onto the pipeline 3. The discharge port of the hopper 6 is connected to the pipeline 3 via the first connecting valve 4. The flow rate monitoring gauge 7 and the pressure monitoring gauge are installed on the pipeline 3 downstream of the hopper 6. The pressure relief valve 9 is installed on the straight section of the pipeline 3 at the second end.

[0038] Step 4: Close the discharge port of the hopper 6 and load the graded sand and gravel aggregate 5 into the hopper 6;

[0039] Step 5: Initial commissioning. Turn on the water storage pump 1, the adjustable speed jet pump 2, and the discharge port of the hopper 6. At this time, the water storage pump 1 draws water from the water source through the suction port and pumps water into the pipeline 3 through the discharge port. The graded sand and gravel aggregate 5 contained in the hopper 6 enters the pipeline 3 and mixes with the water in the pipeline 3 to form a sand-carrying water flow. Since the end of the pipeline 3 is not yet connected to the directional tunneling borehole casing 10, the aggregate discharge with the water flow can be observed at the outlet of the pipeline end on the ground. At the same time, observe whether the flow velocity monitoring meter 7 and the pressure monitoring meter 8 are working properly. If any abnormalities occur, adjustments can be made before the end of the pipeline 3 is connected to the directional tunneling borehole casing 10. After the initial commissioning, the flow velocity of the sand-carrying water flow is relatively uniform, and the flow velocity monitoring meter 7 and the pressure monitoring meter 8 are working properly.

[0040] Step 6: Connect pipeline 3 to the directional drilling casing 10. Under normal initial commissioning conditions, use the second connecting valve 14 to bolt pipeline 3 tightly to the directional drilling casing 10.

[0041] Step 7: Conduct mid-term commissioning. Turn on the water storage pump 1, the adjustable speed jet pump 2, and the discharge port of the hopper 6. Observe whether the flow rate monitoring gauge 7 and the pressure monitoring gauge 8 are working properly. After the flow rate of the sand-carrying water in the pipeline 3 and the directional tunnel borehole casing 10 stabilizes, open the pressure relief valve 9 and observe whether it plays a pressure relief role. If any abnormalities occur, further adjustments can be made.

[0042] Step 8: Turn on the water storage pump 1, the adjustable speed jet pump 2, and the discharge port of the hopper 6. Close the pressure relief valve 9. Dynamically adjust the water flow speed of the adjustable speed jet pump 2 according to the values ​​of the flow rate monitoring table 7 and the pressure monitoring table 8, and implement negative pressure feeding of ground directional tunnel drilling.

[0043] Step 9: After the feeding amount reaches the designed feeding amount and the pressure in the pipeline 3 rises to greater than 0 MPa, stop the negative pressure feeding of the surface directional tunnel borehole. The designed feeding amount is approximately equal to the volume of the aggregate accumulation 13, which is estimated based on the cross-sectional size of the water-bearing tunnel. In practical applications, the feeding progress is judged based on the consumption of graded sand and gravel aggregate 5 in the hopper 6. When the feeding amount reaches the designed feeding amount and the reading of the pressure monitoring gauge 8 rises from a negative value to a positive value, the water storage pump 1, the adjustable speed jet pump 2, and the discharge port of the hopper 6 can be shut off, the pressure relief valve 9 can be opened, and the feeding operation can be stopped.

[0044] During the feeding process, when the value of pressure monitoring gauge 8 is 0 or positive, it indicates that there are signs of blockage in pipeline 3 and directional tunnel borehole 11. When the value of pressure monitoring gauge 8 exceeds 1MPa, pressure monitoring gauge 8 will issue an alarm flashing light. At this time, water storage pump 1, adjustable speed jet pump 2, and hopper 6 outlet should be shut down, pressure relief valve 9 should be opened, and pipe or borehole blockage treatment should be carried out.

[0045] When the depth of the water-bearing tunnel varies, the sand-carrying water flow will experience varying degrees of acceleration after entering the straight section 33 of pipeline 3, and will enter the water-bearing tunnel at a velocity greater than that in pipeline 3. Engineering tests show that the velocity of the sand-carrying water flow entering the water-bearing tunnel should ideally be 1.3 to 2.0 times the velocity of the water flowing into the tunnel. This is because if the velocity of the sand-carrying water flow entering the water-bearing tunnel is too low, the water flowing into the tunnel may wash away the graded sand and gravel aggregate, making it difficult to form aggregate deposits on the tunnel floor; while if the velocity of the sand-carrying water flow entering the water-bearing tunnel is too high, the sand-carrying water flow will impact the tunnel floor with greater force, easily dispersing the already formed aggregate deposits.

[0046] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A ground negative pressure feeding system for water inrush interception and plugging of deep buried tunnels, characterized in that, The system includes a pipeline (3), an adjustable-speed jet pump (2), a directional tunneling borehole casing (10), and a hopper (6). A directional tunneling borehole (11) communicating with a water-bearing tunnel (12) is drilled on the ground. The second end of the directional tunneling borehole casing (10) is inserted into the directional tunneling borehole (11) and communicates with the fluid in the water-bearing tunnel (12). The adjustable-speed jet pump (2) is located on the ground. The outlet end of the adjustable-speed jet pump (2) is connected to the first end of the pipeline (3), and the second end of the pipeline (3) is connected to the directional tunneling borehole casing (10). The first end of the hopper (6) is connected; the outlet of the hopper (6) is connected to the pipeline (3) and is conductive; the hopper (6) is filled with graded sand and gravel aggregate (5); the adjustable speed jet pump (2) supplies high-speed water flow into the pipeline (3); the graded sand and gravel aggregate (5) in the hopper (6) enters the pipeline (3) through the outlet and mixes with the high-speed water flow before entering the directional tunnel borehole casing (10); the high-speed water flow drives the graded sand and gravel aggregate (5) into the water inflow tunnel (12) to form an aggregate accumulation body (13). The ground negative pressure feeding system also includes a baffle (15), a baffle support (16), a connecting rod (17), and a first connecting valve (4). The first connecting valve (4) is a gate valve, which includes a valve stem (41) and a gate connected to the second end of the valve stem (41). The first end of the baffle (15) extends into the cavity of the pipe (3), and the surface of the baffle is perpendicular to the direction of water flow in the pipe (3). The second end of the baffle (15) passes through the pipe wall of the pipe (3) and is hinged to the first end of the connecting rod (17) outside the cavity of the pipe (3). The second end of the connecting rod (17) is connected to the valve stem. (41) The first end is hinged; the baffle bracket (16) is fixedly installed on the outside of the pipe wall of the pipeline (3), and the baffle bracket (16) is hinged to the middle of the baffle (15). The hinge axis of the baffle bracket (16) and the baffle (15) is perpendicular to the extension direction of the pipeline (3); the first connecting valve (4) is installed on the passage between the outlet of the hopper (6) and the pipeline (3). The gate of the first connecting valve (4) directly controls the opening and closing of the passage; when the water flow in the pipeline (3) pushes the baffle (15), the passage between the outlet of the hopper (6) and the pipeline (3) is connected. The directional tunneling borehole casing (10) is divided into a first directional tunneling borehole casing (101) and a second directional tunneling borehole casing (102). The upper end of the first directional tunneling borehole casing (101) is connected to the pipeline (3), and the lower end of the first directional tunneling borehole casing (101) is connected to the upper end of the second directional tunneling borehole casing (102). The inner diameter of the first directional tunneling borehole casing (101) is larger than the inner diameter of the second directional tunneling borehole casing (102). The first directional tunneling borehole casing (101) extends vertically downward from the ground to a depth of 5-15m below the bedrock in the stratum. The lower end of the second directional tunneling borehole casing (102) is flush with the top plate of the water-bearing tunnel (12). When the sand-carrying water flows into the water-bearing tunnel, the flow velocity of the sand-carrying water is 1.3 to 2.0 times that of the water flow velocity in the water-bearing tunnel (12); When the ground negative pressure feeding system is working, the graded sand and gravel aggregate (5) contained in the hopper (6) enters the pipeline (3) and mixes with the water in the pipeline (3) to form a sand-carrying water flow; the flow velocity of the sand-carrying water flow in the pipeline (3) is greater than or equal to the free descent rate of the graded sand and gravel aggregate (5) in still water.

2. The ground negative pressure feeding system for intercepting and sealing water inrush in deep-buried tunnels according to claim 1, characterized in that, The pipeline (3) is divided into a horizontal section (31) parallel to the ground, a bend section (32) and a straight section (33) perpendicular to the ground. Along the direction from the first end to the second end of the pipeline (3): the horizontal section (31), the bend section (32) and the straight section (33) are connected in sequence and fluid is connected; the outlet of the hopper (6) is fluid connected to the middle part of the horizontal section (31).

3. The ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels according to claim 2, characterized in that, The ground negative pressure feeding system also includes a pressure relief valve (9) arranged on the straight pipe section (33) of the pipeline (3).

4. The ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels according to claim 1, characterized in that, During the drilling process, the directional tunnel borehole (11) extends 1m below the bottom plate of the water-bearing tunnel (12) at one end away from the ground.

5. The ground negative pressure feeding system for intercepting and sealing water inrush in deeply buried tunnels according to claim 1, characterized in that, The ground negative pressure feeding system also includes a flow rate monitoring meter (7) and a pressure monitoring meter (8) arranged sequentially from the first end of the pipeline (3) to the second end of the pipeline (3), and the flow rate monitoring meter (7) is arranged on the pipeline on the downstream side of the hopper (6).

6. The ground negative pressure feeding system for intercepting and sealing water inrush in deep-buried tunnels according to claim 1, characterized in that, The graded sand and gravel aggregate (5) is a mixture of sand and gravel with a particle size distribution between 1 mm and 50 mm and containing a variety of different particle sizes, and the porosity of the graded sand and gravel aggregate (5) is 10% to 20%.

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