Underground water system of shield tunnel and installation method thereof

Abstract

This invention discloses an underground water supply system for a shield tunnel and its installation method. The tunnel is composed of segments, including a pipeline module for connecting groundwater on both sides of the tunnel and an intelligent control module for enabling self-adjustment and self-adaptation of the water supply equipment. The intelligent control module controls the pipeline module. Within each segment ring, a water collection pipe is installed on the side of the segment ring that contacts the higher water level, and a drainage pipe is installed on the side of the segment ring that contacts the lower water level. A guide pipe connects the water collection pipe and the drainage pipe, ultimately forming an interconnected water supply system. Groundwater flows from the side with the higher water level through the water collection pipe, guide pipe, and drainage pipe to the side with the lower water level, thereby maintaining the original water level around the tunnel, protecting the groundwater environment before tunnel construction, and avoiding adverse effects such as ground subsidence and ecological damage caused by groundwater obstruction and changes in groundwater level.

Description

Technical Field

[0001] This invention belongs to the field of shield tunnels, specifically relating to an underground water supply system for shield tunnels and its installation method. Background Technology

[0002] As my country's underground development and tunnel construction mileage continue to increase, the original groundwater environment is affected to varying degrees. Obstruction of groundwater seepage will lead to an increase in upstream water level and a decrease in downstream water level. Long-term obstruction of groundwater will cause upstream water level rise, which can easily lead to leakage of upstream pipe segments, deterioration of groundwater quality, and ground uplift. Meanwhile, the decrease in downstream groundwater level will lead to stratum subsidence and destruction of the original vegetation ecosystem.

[0003] Currently, the impact of shield tunnel construction on groundwater has not received sufficient attention in China, and corresponding measures are generally not adopted to reduce the impact of underground facilities on groundwater. As the country emphasizes environmental protection and promotes high-quality development, the impact of underground facilities on groundwater will receive increasing attention, especially since numerous urban underground transportation facilities severely affect groundwater flow and damage the groundwater environment. Therefore, it is necessary to consider water diversion measures during construction or remedial measures after completion and operation. Currently, the main method for controlling water flow is mechanical drilling and pumping. This method is not only large-scale but also damages the geological structure around the tunnel, affects soil stability, and disrupts the water environment.

[0004] Therefore, for water-blocking tunnels, this invention provides a water circulation system consisting of water collection, drainage, and conduits that can be installed inside the tunnel. Summary of the Invention

[0005] The purpose of this invention is to provide an underground water supply system for shield tunnels and a new method for resolving water blockage problems after construction. This method connects the groundwater on both sides of the tunnel to maintain the original water level around the tunnel, protect the groundwater environment before tunnel construction, and avoid adverse effects such as ground subsidence and ecological damage caused by groundwater blockage and changes in groundwater level.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An underground water supply system for a shield tunnel, the tunnel being composed of segments, includes a pipeline module for connecting groundwater on both sides of the tunnel and an intelligent control module for enabling self-adjustment and self-adaptation of the water supply equipment. The pipeline module includes a collection pipe and a drainage pipe. A collection pipe is located on the side of the tunnel with a higher water level, and a drainage pipe is located on the side with a lower water level. The collection pipe and the drainage pipe are connected by a guide pipe. The collection pipe and the guide pipe are connected by a first electric three-way ball valve. The drainage pipe is connected to the guide pipe by a second electric three-way ball valve and an electric regulating valve. A high-pressure water pump is connected to the guide pipe by a third electric three-way ball valve.

[0008] Within each tunnel segment ring, a collection pipe is installed on the side of the segment ring that contacts the higher water level, and a drainage pipe is installed on the side that contacts the lower water level. A guide pipe connects the collection and drainage pipes, ultimately forming an interconnected water system. Groundwater flows from the higher water level side through the collection, guide, and drainage pipes to the lower water level side, thus maintaining the original water level around the tunnel, protecting the groundwater environment before tunnel construction, and avoiding adverse effects such as ground subsidence and ecological damage caused by groundwater obstruction and changes in groundwater level. An electric three-way ball valve is used to control the opening and closing of the pipeline, and an electric regulating valve is used to adjust the water flow from the guide pipe to different drainage pipes. An external water source uses a high-pressure water pump to clean the silt from the guide pipe and discharge it through the cleaning pipe. The high-pressure water pump has a built-in electric three-way ball valve, which can adjust the direction of water flow through the pump, achieving water pressure supply in any of the three directions.

[0009] Furthermore, the water collection pipe and drainage pipe are the same double-layered pipe. The outer layer is composed of a rigid permeable pipe and a non-woven geotextile composite, while the inner layer is a rigid pipe with the same length as the pipe segment thickness. The end of the rigid pipe is equipped with an annular baffle, which, together with the outer layer and the pipe segment, forms a closed grouting space, achieving a sealing effect after grouting. This double-layered pipe system can collect groundwater in soil and rock conditions or discharge water from the pipes, while ensuring that silt does not form and cause blockages.

[0010] Furthermore, the rigid permeable pipe is made of high-density polyethylene filament melt-laid mesh, filled internally with small-particle gravel, and the non-woven geotextile is made of synthetic fibers through needle punching or weaving. The permeable pipe features high pressure resistance, high pore density, and the functions of water collection and drainage. The non-woven geotextile has stable performance, good permeability, and high durability. The non-woven geotextile also has a reverse filtration function; when water flows from the rock strata to the collection pipe, the excellent air and water permeability of the non-woven geotextile allows water to pass through while effectively trapping soil particles, reducing the possibility of silt blockage inside the pipe.

[0011] Furthermore, the upper half of the rigid permeable pipe has permeable holes, while the lower half does not. The permeable holes have a diameter of 3-5 mm and an opening rate of 65-75%. The absence of permeable holes in the lower part of the pipe prevents secondary leakage of groundwater under gravity. The diameter of the rigid pipe is determined by the specific grouting hole size of the pipe segments, and the length is determined by the required water flow rate based on hydrogeological conditions.

[0012] Furthermore, the outer diameter of the annular baffle is the same as the outer diameter of the outer layer pipe, and the inner diameter of the annular baffle is the same as the outer diameter of the inner layer pipe. The annular baffle, the outer layer, and the pipe segments form a closed grouting space. The annular baffle has grouting holes, and grouting is used to form a seal between the pipe segment lining and the outside world.

[0013] The dimensions of the water collection pipe and the drain pipe are obtained using the following formula:

[0014] Hydraulic gradient around the tunnel: i

[0015] Upstream groundwater flow rate of the tunnel: Q = DBki;

[0016] Water flow rate of the water circulation system: Q * =n(1-m)ΠdLki *

[0017] Keeping the groundwater flow constant: kiDB=n(1-m)ΠdLki *

[0018] Maintain equal water head on both sides of the tunnel: i = i *

[0019] Then (1-m)L=DB / nΠd

[0020] B – Width of the segment;

[0021] D—Tunnel cross-sectional diameter;

[0022] K—Permeability coefficient of the soil layer surrounding the tunnel;

[0023] Q—Tunnel cross-sectional flow rate per unit time;

[0024] i—Difference in water head between upstream and downstream sides of the tunnel;

[0025] d—The inner diameter of the outer layer of the water collection pipe or drainage pipe must be smaller than the diameter of the grouting hole;

[0026] n — the number of water collection pipes or drainage pipes;

[0027] m — the opening ratio of the water collection pipe or drainage pipe;

[0028] L – Length of the water collection or drainage pipe in the soil layer.

[0029] The values ​​of L and m on the left side of the equation need to be given, while the right side of the equation consists of known engineering parameters. Each project has corresponding parameters, and it is only necessary to ensure that the left and right sides of the equation are equal. The specific design can be adjusted according to actual needs and for ease of operation, by increasing or decreasing a certain parameter.

[0030] Furthermore, by setting up multiple water supply systems through multiple ring segments, and using ball valves to connect the water pipes between the segments to form a water supply network, a multi-dimensional water level regulation network is established around the tunnel to achieve three-dimensional regulation of the groundwater level.

[0031] Furthermore, the intelligent control module includes a distance sensor, a water flow velocity sensor, a data acquisition instrument, and a microcontroller. The distance sensor is attached to the outer surface of the water pipe and located at the lowest point of the tunnel to monitor the silt thickness h of the water pipe. The water flow velocity sensor is installed at the bottom of the upstream end of the water collection pipe and the bottom of the downstream end of the drainage pipe to monitor the water flow velocity of the drainage pipe.

[0032] Furthermore, the sensor transmits the signal to the single-chip microcomputer through the data acquisition instrument, and the single-chip microcomputer makes the following program judgments:

[0033] a. The ranging sensor collects the data of the silt thickness h of the water conduit, sets the value of x, and judges whether h is less than x;

[0034] b. If h≥x, the cleaning work is carried out, the first electric three-way ball valve, the second electric three-way ball valve and the third electric three-way ball valve are opened, and the high-pressure water pump starts to work; if h<x, the water passing work is carried out, the first electric three-way ball valve and the second electric three-way ball valve are opened, the third electric three-way ball valve is closed, the water conduit is connected, and the water flow velocity sensors collect the water flow velocity v1 of the drain pipe 1, the water flow velocity v2 of the drain pipe 2 and the water flow velocity v0 of the water collecting pipe. k is the soil permeability coefficient, and i is the hydraulic gradient. Among them, the position of the drain pipe 1 in the vertical direction is higher than that of the drain pipe 2;

[0035] c. When v1 = v2 = ki, keep the power of the high-pressure water pump and return to step a; when v1≠ki or v2≠ki, compare the magnitudes of v1, v2 and ki:

[0036] 1) When v1<ki and v2<ki, increase the power of the high-pressure water pump and increase the valve openings of the drain pipe 1 and the drain pipe 2;

[0037] 2) When v1<ki and v2 = ki, increase the power of the high-pressure water pump, increase the valve opening of the drain pipe 1, and decrease the valve opening of the drain pipe 2;

[0038] 3) When v1<ki and v2>ki, increase the valve opening of the drain pipe 1 and decrease the valve opening of the drain pipe 2;

[0039] 4) Return to step b.

[0040] An installation method for an underground water passing system of a shield tunnel includes the following steps:

[0041] (1) At the port of a relatively long section of the water conduit, stick the laser ranging sensor inside the pipe and mark it on the outside of the pipe;

[0042] (2) At the bottom of the upstream end of the water collecting pipe and the bottom of the downstream end of the drain pipe, stick the water flow velocity sensors and mark them on the outside of the pipe;

[0043] (3) Arrange each device in the designed order, penetrate the sensor data cable inside the pipe, and connect it outside the pipe through the three-way valve of the water conduit;

[0044] (4) Use a drill to drill holes at the positions of the secondary grouting holes of the segment according to the designed size, then take out the drill and clean the holes;

[0045] (5) Place the water collection pipe and drainage pipe into the borehole, and finally grout the grouting hole of the annular baffle. Control the grouting rate, grout slowly, and observe whether the grout leaks out around the annular baffle. If the grout leaks out, stop grouting. Finally, wait for the concrete to solidify and harden to achieve the sealing effect.

[0046] (6) Connect the inner layer of the water collection pipe and the water drain pipe to the water guide pipe. The water collection pipe and the water guide pipe are connected through the first electric three-way ball valve. The inner layer of the drain pipe and the water guide pipe are connected through the electric regulating valve and the second electric three-way ball valve.

[0047] (7) Connect the three-way valve to the high-pressure water pump, connect the other end of the three-way valve to the longer section of the water pipe, and connect the high-pressure water pump to the shorter section of the water pipe.

[0048] (8) Seal the interface between the three-way valve and the outside with sealant;

[0049] (9) Connect the data lines of each sensor, the data line of the electric regulating valve and the data line of the electric three-way ball valve to the data acquisition instrument, and connect the data acquisition instrument to the microcontroller;

[0050] (10) Connect the power supply to each device and start working.

[0051] By adopting the above technical solution, the present invention has the following beneficial effects:

[0052] 1. This invention is practical. It can connect the groundwater on both sides of the tunnel and maintain the in-situ water pressure around the tunnel, effectively solving the problems caused by shield tunnels obstructing groundwater flow, and alleviating engineering problems such as upstream segment leakage and damage to the groundwater environment caused by groundwater.

[0053] 2. This invention is economical. Existing drainage methods, such as machine pumping and well drilling, are costly and require periodic pumping operations based on changes in groundwater levels. In contrast, the system of this invention can operate automatically and continuously after a single installation, reducing the need for periodic manual labor.

[0054] 3. This invention is environmentally friendly. Compared with existing machine pumping and well pumping methods, this invention does not require drilling to excavate soil and rock, thus avoiding impact on the geological environment. At the same time, it can restore the groundwater level before tunnel construction, reducing the impact of tunnel engineering on the rock strata.

[0055] 4. This invention is intelligent. It collects on-site data through sensors, transmits it to a microcontroller control center, and then controls valves and water pumps to achieve self-regulation of groundwater on both sides of the tunnel. Attached Figure Description

[0056] The invention will now be further described with reference to the accompanying drawings.

[0057] Figure 1 This is a cross-sectional view of an underground water supply system for a shield tunnel.

[0058] Figure 2 A flowchart for program judgment in a microcontroller.

[0059] Figure 3 This is a cross-sectional view of the underground water supply system of the shield tunnel during water conveyance.

[0060] Figure 4 This is a cross-sectional view of the underground water supply system of the shield tunnel during cleaning.

[0061] Figure 5 Cross-sectional view of a rigid permeable pipe.

[0062] Figure 6 This is a schematic diagram of the tunnel segment structure.

[0063] Figure 7 This is a partial structural diagram of a water supply system deployed in a multi-ring segment. Detailed Implementation

[0064] Taking a single-ring segment as an example, such as Figure 1 The above-described underground water supply system for a shield tunnel is installed inside the tunnel, which is assembled from tunnel segments 1. It includes a pipeline module and an intelligent control module. The pipeline module is used to connect the groundwater on both sides of the tunnel, and the intelligent control module is used to realize the self-adjustment and self-adaptation of the water supply equipment.

[0065] The piping module includes a water collection pipe 2, a drain pipe 31, a drain pipe 32, a guide pipe 4, a first electric three-way ball valve 5, a second electric three-way ball valve 6, a third electric three-way ball valve 7, an electric regulating valve 8, and a high-pressure water pump 9. The water collection pipe 2 is connected to the guide pipe 4 via the first electric three-way ball valve 5, and the drain pipes 31 and 32 are connected to the guide pipe 4 via the second electric three-way ball valve 6 and the electric regulating valve 8. The guide pipe 4 is equipped with a T-type three-way valve 17 for leading the data cable of the sensor inside the pipe to the outside. The joint between the three-way valve and the outside of the pipe is sealed with sealant. The high-pressure water pump 9 has a built-in electric three-way ball valve.

[0066] The intelligent control module includes a distance sensor 10, a water flow velocity sensor 11, a data acquisition instrument (not shown in the figure), and a microcontroller (not shown in the figure). The distance sensor 10 is attached to the surface of the water pipe 4 and is located at the lowest point of the tunnel to monitor the silt thickness h of the water pipe 4. The water flow velocity sensor 11 is installed at the bottom of the upstream end of the water collection pipe 2 and the bottom of the downstream end of the drainage pipes 31 and 32 to monitor the water flow velocity of the drainage pipes 31 and 32.

[0067] like Figure 2As shown, the ranging sensor 10 and the water flow velocity sensor 11 transmit signals to the single-chip microcomputer through the data acquisition instrument, and the single-chip microcomputer makes the following program judgments:

[0068] a. The ranging sensor 10 collects the data of the silt thickness h of the water conduit 4, sets the value of x, and judges whether h is less than x;

[0069] b. If h≥x, cleaning work is carried out, the first electric three-way ball valve 5, the second electric three-way ball valve 6 and the third electric three-way ball valve 7 are opened, and the high-pressure water pump 9 starts to work; if h<x, water passing work is carried out, the first electric three-way ball valve 5 and the second electric three-way ball valve 6 are opened, the third electric three-way ball valve 7 is closed, the water conduit 4 is connected, and the water flow velocity sensor 11 collects the water flow velocity v1 of the drain pipe 31, the water flow velocity v2 of the drain pipe 32 and the water flow velocity v0 of the water collecting pipe 2. k is the soil permeability coefficient and i is the hydraulic gradient. Among them, the drain pipe 31 is higher than the drain pipe 32 in the vertical direction;

[0070] c. When v1 = v2 = ki, keep the power of the high-pressure water pump 9 and return to step a; when v1≠ki or v2≠ki, compare the sizes of v1, v2 and ki:

[0071] 1) When v1<ki and v2<ki, increase the power of the high-pressure water pump 9 and increase the valve openings of the drain pipe 31 and the drain pipe 32;

[0072] 2) When v1<ki and v2 = ki, increase the power of the high-pressure water pump 9, increase the valve opening of the drain pipe 31, and decrease the valve opening of the drain pipe 32;

[0073] 3) When v1<ki and v2>ki, increase the valve opening of the drain pipe 31 and decrease the valve opening of the drain pipe 32;

[0074] 4) Return to step b.

[0075] As Figure 3 shown, when the single-chip microcomputer judges that water passing is required, the first electric three-way ball valve 5 and the second electric three-way ball valve 6 are opened, and the third electric three-way ball valve 7 is closed. The water on the side with a high tunnel water level passes through the water collecting pipe 2, the water flow velocity sensor 11, the first electric three-way ball valve 5, the water conduit 4, the second electric three-way ball valve 6, the water flow velocity sensor 11, the drain pipe 31 or the drain pipe 32 in sequence, and is thus discharged to the side with a low water level. The water flow is as shown by the arrow. <00,water conduit 4, the second electric three-way ball valve 6, the water flow velocity sensor 11, the drain pipe 31 or the drain pipe 32 in sequence, and is thus discharged to the side with a low water level. The water flow is as shown by the arrow.

[0076] As Figure 4 shown, when the single-chip microcomputer judges that cleaning is required, the first electric three-way ball valve 5 and the second electric three-way ball valve 6 are closed, and the third electric three-way ball valve 7 is opened. The water from the external water source is discharged from both sides of the water conduit 4 through the high-pressure water pump 9. The water flow is as shown by the arrow.

[0077] The water collection pipe 2, drainage pipe 31, and drainage pipe 32 are the same double-layer pipe. The outer layer is composed of a rigid permeable pipe 12 and a non-woven geotextile 13, and the inner layer is a rigid pipe 14 with the same length as the thickness of the pipe segment 1. The end of the rigid pipe 14 is provided with an annular baffle 15. The annular baffle 15, the outer layer, and the pipe segment 1 form a closed grouting space 21, which achieves a sealing effect after grouting.

[0078] like Figure 5 As shown, the upper two-thirds of the rigid permeable pipe 12 has permeable holes 19, while the lower one-third of the rigid permeable pipe 12 does not have permeable holes 19. The pore diameter of the permeable holes 19 is 3-5 mm, and the porosity is 65-75%. The rigid permeable pipe 12 is a new type of geosynthetic material made of high-density polyethylene (HDPE) filaments melt-laid into a mesh, which has the characteristics of high pressure resistance and high porosity. The non-woven geotextile 13 is a permeable geosynthetic material made of synthetic fibers through needle punching or weaving, which has stable performance, good permeability, and high durability.

[0079] like Figure 6 As shown, the outer diameter of the annular baffle 15 is the same as the outer diameter of the outer layer pipe, and the inner diameter of the annular baffle 15 is the same as the outer diameter of the inner layer pipe. The annular baffle 15 has grouting holes 16.

[0080] The dimensions of the water collection pipe 2 and the drain pipe 31 (the dimensions of the drain pipe 32 are the same as those of the drain pipe 31) are obtained by the following formula:

[0081] Hydraulic gradient around the tunnel: i (1)

[0082] Groundwater flow rate upstream of the tunnel: Q = DBki (2)

[0083] Water flow rate of the water circulation system: Q * =n(1-m)ΠdLki * (3)

[0084] Keeping the groundwater flow constant: kiDB=n(1-m)ΠdLki * (4)

[0085] Maintain equal water head on both sides of the tunnel: i = i * (5)

[0086] Then (1-m)L=DB / nΠd (6)

[0087] B—Width of segment 1;

[0088] D—Tunnel cross-sectional diameter;

[0089] K—Permeability coefficient of the soil layer surrounding the tunnel;

[0090] Q—Tunnel cross-sectional flow rate per unit time;

[0091] i—Difference in water head between upstream and downstream sides of the tunnel;

[0092] d—The inner diameter of the outer layer of the water collection pipe 2 or the drainage pipe 31 must be smaller than the diameter of the grouting hole 16;

[0093] n — the number of water collection pipes 2 or drainage pipes 31 (drainage pipes 32);

[0094] m — Opening ratio of water collection pipe 2 or drainage pipe 31;

[0095] L – Length of the water collection pipe 2 or drainage pipe 31 in the soil layer.

[0096] The coordination and adjustment that the design parameters m and L need to meet can be obtained by formula (6).

[0097] An installation method for an underground water supply system in a shield tunnel segment 1 includes the following steps:

[0098] (1) At the port of a longer section of the water pipe 4, attach the laser range sensor 10 to the inside of the pipe and mark the number on the outside of the pipe.

[0099] (2) Attach water flow velocity sensor 11 to the bottom of the upstream end of water collection pipe 2 and the bottom of the downstream end of drainage pipe 31 and drainage pipe 32, and mark the number on the outside of the pipe.

[0100] (3) Arrange the equipment in the design order, run the sensor data cable through the inside of the pipe, and connect it to the outside of the pipe through the water pipe 4;

[0101] (4) Drill holes at the grouting hole 16 position of segment 1 according to the design dimensions using a drilling rig, then remove the drilling rig and clean the drill holes;

[0102] (5) Place the water collection pipe 2, drainage pipe 31 and drainage pipe 32 into the borehole, and finally grout in the grouting hole 16 of the annular baffle 15. Control the grouting rate and grout slowly. Observe whether the grout leaks out around the annular baffle 15. If the grout leaks out, stop grouting. Finally, wait for the concrete to solidify and harden to achieve the sealing effect.

[0103] (6) Connect the inner layers of the water collection pipe 2 and the drain pipe 31 (drain pipe 32) to the water guide pipe 4. Specifically, the water collection pipe 2 and the water guide pipe 4 are connected through the first electric three-way ball valve 5, and the inner layer of the drain pipe 31 (drain pipe 32) and the water guide pipe 4 are connected through the electric regulating valve 8 and the second electric three-way ball valve 6.

[0104] (7) Connect the water pipe 4, the third electric three-way ball valve 7 to the high-pressure water pump 9;

[0105] (8) Seal the interface between the T-type three-way valve 17 and the outside with sealant;

[0106] (9) Connect the data lines of each sensor, the data line of the electric regulating valve 8 and the data line of the electric three-way ball valve to the data acquisition instrument, and connect the data acquisition instrument to the microcontroller.

[0107] (10) Connect the power supply to each device and start working.

[0108] like Figure 7 As shown, when the water supply system is installed in the multi-ring segment 20, the water supply method is similar to that installed in the single-ring segment 1. The difference is that a four-way valve 18 is used instead of a T-type three-way valve 17, and water pipes 4 are used to connect the segments 1. The sensor data line can be led out at a certain point in the water pipe 4 using a T-type three-way valve 17, and then the interface is sealed with a seal.

[0109] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. An underground water supply system for a shield tunnel, the tunnel being composed of segments, characterized in that: The system includes a pipeline module for connecting groundwater on both sides of the tunnel and an intelligent control module for enabling self-adjustment and self-adaptation of the water supply equipment. The intelligent control module controls the pipeline module, which includes a collection pipe and a drainage pipe. The collection pipe is located on the side of the tunnel with a higher water level, and the drainage pipe is located on the side with a lower water level. The collection pipe and the drainage pipe are connected by a guide pipe. The collection pipe and the guide pipe are connected via a reducing joint and a first electric three-way ball valve. The drainage pipe is connected to the guide pipe via a reducing joint, a second electric three-way ball valve, and an electric regulating valve. The guide pipe is connected to a high-pressure water pump via a third electric three-way ball valve. The dimensions of the collection pipe and the drainage pipe are obtained using the following formula: hydraulic gradient around the tunnel: Upstream groundwater flow rate of the tunnel: Water flow rate of the water circulation system: Maintain a constant groundwater flow rate: Maintain equal water head on both sides of the tunnel: but B – Width of the tunnel segment; D – Diameter of the tunnel cross section; K – Permeability coefficient of the soil layer surrounding the tunnel; Q – Flow rate of the tunnel cross section per unit time; i – Difference in water head between the upstream and downstream sides of the tunnel; d – Inner diameter of the outer layer of the water collection pipe or drainage pipe, which must be smaller than the diameter of the grouting hole; n – Number of water collection pipes or drainage pipes; m – Aperture ratio of the water collection pipes or drainage pipes; L – Length of the water collection pipes or drainage pipes in the soil layer.

2. The underground water supply system for a shield tunnel according to claim 1, characterized in that: The water collecting pipe and the drain pipe are the same double-layer pipe. Among them, the outer layer is composed of a rigid permeable pipe and a non-woven geotextile, and the inner layer is a rigid pipe with the same length as the thickness of the segment. An annular baffle is provided at the end of the rigid pipe, and the annular baffle, the outer layer and the segment form a closed grouting space.

3. The underground water supply system for a shield tunnel according to claim 2, characterized in that: The permeable pipe is formed by melting and laying a net of high-density polyethylene filaments and filled with small particle gravel inside. The non-woven geotextile is made by needle punching or weaving synthetic fibers.

4. The underground water supply system for a shield tunnel according to claim 2, characterized in that: The upper half of the rigid permeable pipe is provided with permeable small holes, and the lower half of the rigid permeable pipe has no permeable small holes. The aperture of the permeable small holes is 3-5 mm, and the hole opening rate is 65-75%.

5. The underground water supply system for a shield tunnel according to claim 2, characterized in that: The outer diameter of the annular baffle is the same as the outer pipe diameter of the outer layer, and the inner diameter of the annular baffle is the same as the outer pipe diameter of the inner layer. The annular baffle is provided with grouting holes.

6. The underground water supply system for a shield tunnel according to claim 1, characterized in that: By arranging multiple ring segments to set up multiple water conduction systems, the water conduction pipes between the segments are connected to each other by ball valves to form a water conduction network, and a multi-dimensional three-dimensional water level regulation network is established around the tunnel to realize the three-dimensional regulation of the underground water level.

7. The underground water supply system for a shield tunnel according to claim 1, characterized in that: The intelligent control module includes a ranging sensor, a water flow velocity sensor, a data acquisition instrument, and a single-chip microcomputer. The ranging sensor is attached to the top of the water conduction pipe at the lowest point of the tunnel to monitor the silt thickness h of the water conduction pipe; the water flow velocity sensor is installed at the bottom of the upstream end of the water collecting pipe and the bottom of the downstream end of the drain pipe to monitor the water flow velocity of the drain pipe.

8. The underground water supply system for a shield tunnel according to claim 7, characterized in that: The sensor transmits the signal to the single-chip microcomputer through the data acquisition instrument, and the single-chip microcomputer makes the following program judgments: a. The ranging sensor collects the data of the silt thickness h of the water conduction pipe, sets the value of x, and judges whether h is less than x; b. If h≥x, cleaning work is carried out, the first electric three-way ball valve, the second electric three-way ball valve and the third electric three-way ball valve are opened, and the high-pressure water pump starts to work; if h<x, water conduction work is carried out, the first electric three-way ball valve and the second electric three-way ball valve are opened, the third electric three-way ball valve is closed, the water conduction pipe is connected, and the water flow velocity sensor collects the water flow velocities v1, v2 of the drain pipe 1 and the drain pipe 2 and the water flow velocity v0 of the water collecting pipe. k is the soil permeability coefficient, and i is the hydraulic gradient. Among them, the drain pipe 1 is higher than the drain pipe 2 in the vertical direction; c. When v1 = v2 = ki, keep the power of the high-pressure water pump and return to step a; when v1≠ki or v2≠ki, compare the sizes of v1, v2 and ki: 1) When v1<ki and v2<ki, increase the power of the high-pressure water pump and increase the valve openings of the drain pipe 1 and the drain pipe 2; 2) When v1<ki and v2 = ki, increase the power of the high-pressure water pump, increase the valve opening of the drain pipe 1, and reduce the valve opening of the drain pipe 2; 3) When v1<ki and v2>ki, increase the valve opening of the drain pipe 1 and reduce the valve opening of the drain pipe 2; 4) Return to step b.

9. A method for installing an underground water supply system for a shield tunnel as described in any one of claims 1-8, characterized in that, The steps include: (1) attaching a laser rangefinder sensor to the inside of the pipe at the end of a longer section of the water pipe and marking it on the outside of the pipe; (2) attaching a water flow velocity sensor to the outside of the water collection pipe and the outside of the drainage pipe and marking it on the outside of the pipe; (3) arranging the equipment in the design order, passing the sensor data cable through the inside of the pipe and connecting it to the outside of the pipe through the T-type three-way valve of the water collection pipe; (4) drilling holes at the secondary grouting hole positions of the pipe segment according to the design dimensions using a drilling rig, then removing the drilling rig and cleaning the drill hole; (5) placing the water collection pipe and the drainage pipe into the drill hole, and finally grouting the grouting hole of the annular baffle, controlling the grouting rate, grouting slowly, and observing whether grout leaks out around the annular baffle. Grouting can be stopped when grout leaks out. Finally, wait for the concrete to harden and achieve a sealing effect; (6) Connect the inner layer of the water collection pipe and the drainage pipe to the water guide pipe. The water collection pipe and the water guide pipe are connected through the first electric three-way ball valve. The inner layer of the drainage pipe and the water guide pipe are connected through the electric regulating valve and the second electric three-way ball valve; (7) Connect the water guide pipe and the third electric three-way ball valve to the high-pressure water pump; (8) Seal the T-type three-way valve with sealant at the interface with the outside; (9) Connect the data lines of each sensor, the data lines of the electric regulating valve, the data lines of the first electric three-way ball valve, the data lines of the second electric three-way ball valve, and the data lines of the second electric three-way ball valve to the data acquisition instrument. Connect the data acquisition instrument to the microcontroller; (10) Turn on the power of each device and start working.

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