TBM (Tunnel Boring Machine) anti-scaling drainage pressure reduction structure based on blockage removal combination concept and construction method

Abstract

The invention discloses a TBM (Tunnel Boring Machine) tunnel anti-scaling drainage pressure reduction structure based on a blockage removal combination concept and a construction method, and belongs to the technical field of TBM tunnel engineering. The structure comprises an inclined drainage pipe, a vertical drainage pipe, a horizontal drainage pipe, a Y-shaped three-way flow divider, a pressure valve and geotechnical cloth, the inclined drainage pipe is of an S-shaped structure made of PVC materials, the geotechnical cloth is wrapped outside the inclined drainage pipe, and the inclined drainage pipe penetrates through a gap grouting layer behind a segmental lining and extends into a surrounding stratum; a buckle is arranged in the diverter, waterproof adhesive tape is wrapped outside the diverter, a rotatable sealing cover with a water inlet is arranged at the top end of the vertical drainage pipe, and a pressure valve is arranged at the tail end of the horizontal drainage pipe and connected into a tunnel longitudinal drainage system. The construction method comprises the steps that the inclined drainage pipe is installed through the segmental lining grouting hole, the vertical drainage pipe and the horizontal drainage pipe are sequentially connected, the drainage amount is controlled through the pressure valve, the pressure valve is closed when back flushing is needed, and the scale inhibitor is injected through the vertical drainage pipe and pressurized flushing is conducted. The method is mainly used for drainage, pressure reduction and scaling prevention of the TBM tunnel in the high underground water pressure area.

Description

Technical Field

[0001] This invention belongs to the field of tunnel engineering technology, specifically relating to the field of drainage and pressure reduction and pipe scaling prevention technology in TBM tunnels in areas with high groundwater pressure. Background Technology

[0002] When TBM tunnels traverse areas with high groundwater pressure, the tunnel lining and waterproofing structure must withstand significant groundwater pressure. If the pressure exceeds their tolerance range, it will affect tunnel safety, thus requiring drainage and pressure reduction measures. However, a full drainage model may lead to excessive groundwater discharge, causing ecological and environmental problems such as ground subsidence and vegetation destruction. To address this, a drainage and pressure reduction technology has been developed, which uses pressure valves to control the drainage volume. This technology can reduce the pressure on the tunnel lining while minimizing the impact on the surrounding groundwater environment.

[0003] During the operation of tunnel drainage systems, groundwater rich in specific ions, upon contact with air or reaction with cement-based building materials, easily produces calcium deposits, leading to scaling and causing deterioration and blockage of the drainage system. Existing measures to address scaling are divided into two categories: post-deposition treatment and preventative treatment. Post-deposition treatment often employs hydraulic cleaning or mechanical removal, while preventative treatment includes optimizing drainage system design and adding scale inhibitors. However, these measures are often applied individually and fail to achieve a synergistic effect.

[0004] Existing drainage systems often focus solely on drainage, lacking effective measures to prevent scaling. Furthermore, independent pressure-reducing devices or backwashing equipment fail to integrate with the main tunnel drainage system and discharge control system, resulting in overall system inefficiency and high maintenance costs. Post-deposition treatment methods are not only labor-intensive but may also damage pipes due to the application of mechanical force. While preventative measures have some effect, their integration with drainage and pressure-reducing requirements is insufficient, making it difficult to simultaneously meet the pressure-reducing, discharge control, and scaling prevention needs of tunnels in high groundwater pressure areas, thus failing to guarantee the long-term stable operation of the drainage system. Summary of the Invention

[0005] The purpose of this invention is to provide a TBM tunnel anti-scaling drainage pressure reduction structure and construction method based on the concept of combining drainage and blockage, in order to solve the problem that high groundwater pressure threatens the safety of TBM tunnels and that the drainage system is prone to scaling and blockage leading to operational failure.

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

[0007] In a first aspect, the present invention provides a TBM tunnel anti-scaling drainage and pressure-reducing structure, comprising: an inclined drainage pipe, a vertical drainage pipe, a horizontal drainage pipe, a Y-type tee diverter, and a pressure valve. The inclined drainage pipe extends through the gap grouting layer behind the tunnel lining segments into the surrounding strata. The inclined drainage pipe, the vertical drainage pipe, and the horizontal drainage pipe are interconnected through the Y-type tee diverter. The end of the horizontal drainage pipe is connected to the tunnel's longitudinal drainage system. The pressure valve is located at the end of the horizontal drainage pipe. The top of the vertical drainage pipe is provided with a rotatable sealing cap.

[0008] In one possible implementation, the inclined drainage pipe is composed of S-shaped drainage units, the inclined drainage pipe is made of PVC material, the outside of the inclined drainage pipe is wrapped with geotextile, the geotextile is tightly attached to the inclined drainage pipe, one end of the inclined drainage pipe extends into the surrounding strata, and the other end is fixedly connected to the Y-shaped tee diverter.

[0009] In one possible implementation, the Y-shaped tee diverter has a built-in buckle, and the ends of the inclined drainage pipe, vertical drainage pipe, and horizontal drainage pipe are all inserted into the buckle to achieve a tight connection. The Y-shaped tee diverter is wrapped with waterproof tape. The rotatable sealing cap at the top of the vertical drainage pipe has a water inlet, which can be connected to an external pressure pump. The horizontal drainage pipe receives the groundwater introduced by the inclined drainage pipe through the Y-shaped tee diverter and transports it to the tunnel's longitudinal drainage system.

[0010] In one possible implementation, the structure further includes a T-shaped tee diverter connected to the vertical and horizontal drainage pipes. The T-shaped tee diverter has a built-in buckle and is wrapped with waterproof tape. The tunnel longitudinal drainage system includes longitudinal drainage ditches on both sides and a longitudinal central drainage pipe. The horizontal drainage pipe can be selectively connected to the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe. When the pressure valve is closed, it can cooperate with the vertical drainage pipe to perform a backwashing operation.

[0011] Secondly, the present invention provides a construction method for preventing scaling, draining and reducing pressure in TBM tunnels, comprising the following steps: installing inclined drainage pipes, laying horizontal drainage pipes and setting pressure valves, installing vertical drainage pipes, connecting the inclined drainage pipes, horizontal drainage pipes and vertical drainage pipes to each other through a Y-type tee diverter, controlling the pressure valves to regulate the groundwater discharge, and performing backwashing operations through the vertical drainage pipes.

[0012] In one possible implementation, the inclined drainage pipe is driven into the grouting holes of the segment lining. The inclined drainage pipe is composed of S-shaped drainage units and wrapped with geotextile. The inclined drainage pipe is made of PVC material. One end of the inclined drainage pipe extends into the surrounding strata, and the other end is connected to the Y-shaped tee diverter.

[0013] In one possible implementation, the Y-type tee diverter has a built-in buckle, into which the ends of the oblique drain pipe, horizontal drain pipe and vertical drain pipe are inserted to achieve a tight connection. Waterproof tape is wrapped around the outside of the Y-type tee diverter. The end of the horizontal drain pipe is connected to the tunnel longitudinal drainage system. A rotatable sealing cap with an inlet is installed at the top of the vertical drain pipe.

[0014] In one possible implementation, when backflushing is required, the pressure valve is closed, and a booster pump is connected to the inlet at the top of the vertical drain pipe to inject scale inhibitor into the drainage system. The booster pump is then started to pressurize and backflush the inclined and horizontal drain pipes to remove the deposits and scale inside the pipes.

[0015] In one possible implementation, the connection method is selected according to the location of the tunnel's longitudinal drainage system. When connected to the central main drainage pipe of the invert arch, a T-shaped tee diverter is added to connect the T-shaped tee diverter to the vertical and horizontal drainage pipes. Waterproof tape is wrapped around the outside of the T-shaped tee diverter so that the horizontal drainage pipe can selectively connect to the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe.

[0016] Compared with the prior art, the advantages of this invention are as follows:

[0017] The slanted drainage pipe features an S-shaped structure made of PVC material and wrapped with geotextile. The S-shaped structure ensures water flow velocity and reduces calcium carbonate crystal deposition. PVC material itself does not readily react with groundwater, and the geotextile, combined with the barrier of soil particles, effectively prevents pipe blockage. Furthermore, the S-shaped structure has strong compressive strength, capable of withstanding the pressure impact during backwashing, extending the pipe's service life. Compared to existing ordinary straight pipes, this structure offers significant advantages in preventing blockage and resisting impacts, eliminating the need for frequent pipe replacements and reducing maintenance frequency.

[0018] The Y-type tee diverter has a built-in snap-fit ​​mechanism and is externally wrapped with waterproof tape. Once the drain pipe is inserted into the snap-fit, the connection is tight. The waterproof tape further prevents air from entering the drainage system. A rotatable sealing cap at the top of the vertical drain pipe isolates the system from the atmosphere, reducing air exchange and carbon dioxide escape, thus inhibiting the formation of calcium carbonate deposits and scale at the source. This closed structure solves the problem of frequent scaling caused by insufficient sealing in existing drainage systems, reduces the risk of pipe blockage, and ensures the long-term stable operation of the drainage system.

[0019] The pressure valve at the end of the horizontal drainage pipe can flexibly adjust the groundwater discharge volume, controlling the groundwater pressure on the tunnel lining within a safe range to prevent structural damage, while also preventing excessive groundwater discharge, reducing ecological and environmental problems such as ground subsidence and vegetation destruction, fully embodying the concept of combined drainage and clogging. Compared with existing full drainage or single pressure reduction technologies, this invention achieves a balance between pressure reduction and environmental protection, improving the ecological compatibility of tunnel engineering.

[0020] The inlet at the top of the vertical drain pipe can be connected to an external pressure pump to inject scale inhibitor. When backflushing is required, the pressure valve is closed, and the pressurized water flow carries the scale inhibitor to flush the inclined and horizontal drain pipes. This not only dissolves existing scale but also inhibits the formation of new scale. This active anti-scaling and cleaning function replaces traditional hydraulic cleaning or mechanical removal methods, eliminating the need for extensive manual labor and avoiding mechanical damage to the pipes, thus reducing maintenance costs and complexity.

[0021] The system can be flexibly connected to the longitudinal drainage ditches on both sides or the main drainage pipe in the center of the invert arch by adding a T-shaped tee diverter, adapting to the drainage system design requirements of different tunnels. This adaptability allows the structure and construction method to be applied to a variety of tunnel engineering scenarios, making it more widely applicable and of greater value for promotion compared to existing single-function drainage and pressure reduction systems.

[0022] The entire structure integrates drainage, pressure reduction, scale prevention, and backwashing functions through the synergistic effect of its components. During construction, the connections between components are convenient, and the operation process is simple, requiring no complex specialized equipment or skills. Compared to existing decentralized drainage, pressure reduction, and scale prevention measures, this integrated design simplifies construction procedures, shortens the construction cycle, and reduces the overall system cost and operation and maintenance costs, making it more suitable for large-scale engineering applications. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the oblique S-shaped drainage pressure reducing pipe structure according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the Y-type three-way diverter structure of the tunnel drainage system according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of a TBM tunnel drainage and pressure reduction structure with longitudinal drainage provided in the side ditches on both sides, according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of a TBM tunnel drainage and pressure reduction structure with the longitudinal drainage system located in the center of the invert arch, according to an embodiment of the present invention.

[0028] In the diagram: 101, outer geotextile; 102, S-shaped drainage; 201, vertical drainage pipe; 202, horizontal drainage pipe; 203, oblique drainage pipe; 204, Y-type tee diverter; 1, oblique S-shaped drainage pressure reducing pipe; 3, monitoring flushing and maintenance hole; 4, vertical flushable drainage pipe; 5, pressure valve; 2, Y-type tee diverter; 6, longitudinal drainage ditches on both sides; 7, segment lining. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0030] Example:

[0031] It should be noted that the terms "comprising" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0032] This embodiment provides a TBM tunnel anti-scaling drainage and pressure-reducing structure, including: an inclined drainage pipe, a vertical drainage pipe, a horizontal drainage pipe, a Y-type tee diverter, and a pressure valve. The inclined drainage pipe extends through the gap grouting layer behind the tunnel lining segments and into the surrounding strata. The inclined drainage pipe, vertical drainage pipe, and horizontal drainage pipe are interconnected through the Y-type tee diverter. The end of the horizontal drainage pipe is connected to the tunnel's longitudinal drainage system. The pressure valve is located at the end of the horizontal drainage pipe. The top of the vertical drainage pipe is provided with a rotatable sealing cap.

[0033] Specifically, the inclined drainage pipe is a pipe that guides the discharge of groundwater from the formation, and can be a 45° inclined pipe with a diameter of 100mm and a length of 100cm; the vertical drainage pipe is a vertical pipe used for backwashing and adding scale inhibitors, and can be a PVC pipe with a diameter of 100mm; the horizontal drainage pipe is a transverse pipe that transports groundwater to the longitudinal drainage system, and can be a rigid pipe with a diameter of 100mm; the Y-type tee diverter is a diverter component that connects three drainage pipes, and can be a plastic diverter with built-in buckles; the pressure valve is a valve that controls the amount of groundwater discharged, and can be a manually adjustable shut-off valve; the rotatable sealing cap is a component that seals the top of the vertical drainage pipe, and can be a threaded sealing cap with an inlet; the tunnel longitudinal drainage system is the main system for collecting and discharging groundwater in the tunnel, and can be longitudinal drainage ditches on both sides or a longitudinal central drainage pipe.

[0034] The inclined drainage pipe passes through the gap grouting layer behind the tunnel lining at a 45° angle, with its distal end extending into the surrounding strata and its proximal end inserted into one interface of a Y-type tee diverter; the lower end of the vertical drainage pipe is inserted into the second interface of the Y-type tee diverter, and the top end is fitted with a rotatable sealing cap via threads; one end of the horizontal drainage pipe is inserted into the third interface of the Y-type tee diverter, and the other end extends laterally along the tunnel, with its end connected to the tunnel's longitudinal drainage system. A pressure valve is connected in series on the end pipe of the horizontal drainage pipe, located between the horizontal drainage pipe and the longitudinal drainage system.

[0035] Under water pressure, groundwater in the strata surrounding the tunnel passes through the grouting layer and enters the inclined drainage pipe. Because the inclined drainage pipe is tilted at 45° and adopts an optimized flow channel design, the groundwater forms a stable flow velocity inside the pipe. The groundwater flows into the Y-type three-way diverter through the inclined drainage pipe and then merges into the horizontal drainage pipe. The pressure valve adjusts its opening according to the preset drainage threshold to control the flow of groundwater into the longitudinal drainage system, which reduces the groundwater pressure on the tunnel lining and avoids excessive groundwater discharge. The rotatable sealing cap at the top of the vertical drainage pipe is kept closed to isolate the drainage system from the atmosphere and reduce air entry and CO2 escape. When backwashing is required, the inlet of the sealing cap is opened for subsequent pressurization and scale inhibitor addition.

[0036] In one embodiment, the inclined drainage pipe is composed of S-shaped drainage units. The inclined drainage pipe is made of PVC material and is wrapped with geotextile. The geotextile is tightly fitted to the inclined drainage pipe. One end of the inclined drainage pipe extends into the surrounding strata, and the other end is fixedly connected to the Y-shaped tee diverter.

[0037] Specifically, an S-shaped drainage unit is a pipe section that bends in an S-shape, which can be a continuously bent PVC pipe section; PVC material is polyvinyl chloride, which has the characteristics of corrosion resistance, smoothness and no scaling; geotextile is a filter material that prevents soil particles from entering the pipe, and can be needle-punched non-woven geotextile; tight fit means that the geotextile is completely wrapped around the outside of the inclined drainage pipe by binding or bonding, without looseness or wrinkles.

[0038] The inclined drainage pipe is composed of multiple S-shaped drainage units spliced ​​together, with the whole structure inclined at 45°. It is uniformly wrapped with a layer of geotextile on the outside, and the edges of the geotextile are fixed with waterproof binding tape to ensure a tight fit with the pipe surface without gaps. The far end of the inclined drainage pipe is sharpened and extends into the surrounding strata, and the near end is equipped with an interface adapted to the Y-type tee diverter. The connection is achieved by inserting the built-in buckle of the Y-type tee, and the interface is sealed with waterproof tape.

[0039] Groundwater seeps from the surrounding strata to the area around the inclined drainage pipe. Geotextile first filters out soil particles and impurities to prevent blockage inside the pipe. The filtered groundwater enters the S-shaped drainage unit. The S-shaped structure extends the water flow path while ensuring that the water flow velocity inside the pipe is maintained at 0.8-1.2 m / s, reducing water retention time. The smooth inner wall of the PVC material reduces water flow resistance and also reduces the adsorption and crystallization of calcium carbonate ions on the pipe wall. After being collected by the S-shaped drainage unit, the groundwater flows into the Y-shaped tee diverter through the near-end interface.

[0040] In one embodiment, the Y-type tee diverter has a built-in buckle, and the ends of the inclined drainage pipe, vertical drainage pipe and horizontal drainage pipe are all inserted into the buckle to achieve a tight connection. The Y-type tee diverter is wrapped with waterproof tape. The rotatable sealing cap at the top of the vertical drainage pipe is provided with a water inlet. The water inlet can be connected to an external pressure pump. The horizontal drainage pipe receives the groundwater introduced by the inclined drainage pipe through the Y-type tee diverter and transports it to the tunnel longitudinal drainage system.

[0041] Specifically, the built-in buckle is a pre-set elastic snap-fit ​​structure inside the Y-type three-way diverter, which can be a ring-shaped rubber buckle; the waterproof tape is tape used to seal the interface gaps, which can be butyl waterproof tape; the inlet is a threaded interface reserved on the rotatable sealing cover, which can be a DN25 interface; the external pressure pump is a device that provides backwash pressure, which can be a portable electric pressure pump with a maximum output pressure of 2MPa.

[0042] The Y-type tee diverter has built-in buckles at all three internal interfaces. The ends of the oblique, vertical, and horizontal drain pipes are all machined with annular grooves to fit the buckles. After insertion, the buckles elastically lock into the annular grooves to achieve a tight connection. After connection, three layers of waterproof tape are wrapped around the external interface of the Y-type tee diverter, with the tape overlap width being 1 / 2 of the tape width, to ensure a complete seal at the interface gaps. The rotatable sealing cap at the top of the vertical drain pipe has a water inlet in the center, which has internal threads and can be threaded to connect with the outlet pipe connector of the booster pump. The end of the horizontal drain pipe away from the Y-type tee diverter is fixedly connected to the interface flange of the tunnel longitudinal drainage system.

[0043] Groundwater introduced by the inclined drainage pipe flows into the Y-type tee diverter and, under the pressure of the water flow, naturally merges into the horizontal drainage pipe. The horizontal drainage pipe smoothly transports the groundwater to the tunnel's longitudinal drainage system. The Y-type tee diverter's built-in buckle and external waterproof tape work together to prevent air from entering the drainage system through the interface gaps, maintaining a relatively closed environment inside the system. When backwashing is required, the outlet pipe connector of the pressure pump is screwed into the inlet of the vertical sealing cap to complete the connection preparation. At this time, the pressure valve can remain closed, thus providing pressure conditions for backwashing.

[0044] In one embodiment, the structure further includes a T-shaped tee diverter connected to the vertical and horizontal drainage pipes. The T-shaped tee diverter has a built-in buckle and is wrapped with waterproof tape. The tunnel longitudinal drainage system includes longitudinal drainage ditches on both sides and a longitudinal central drainage pipe. The horizontal drainage pipe can be selectively connected to the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe. When the pressure valve is closed, it can cooperate with the vertical drainage pipe to perform backwashing.

[0045] Specifically, the T-type tee diverter is a diverting component used to additionally expand the vertical drainage pipe interface, and can be a plastic diverter of the same material as the Y-type tee; the longitudinal drainage ditches on both sides are drainage channels set in the side ditches on both sides of the tunnel, and can be U-shaped ditches made of concrete; the longitudinal central drainage pipe is the main water collection and drainage pipe set in the center of the tunnel invert arch, and can be a 300mm diameter HDPE pipe; selective connection refers to connecting the horizontal drainage pipe to the preset longitudinal drainage facilities according to the tunnel drainage system design scheme.

[0046] The main interface of the T-type tee diverter connects to the middle section of the horizontal drainage pipe, and the side interface connects to the lower end of the newly added vertical drainage pipe. The T-type tee diverter also has built-in buckles. After each interface is inserted, the buckles are tightened, and the outside is sealed with waterproof tape. When the tunnel's longitudinal drainage system consists of longitudinal drainage ditches on both sides, the end of the horizontal drainage pipe is directly connected to the inlet of the drainage ditch. When it is a longitudinal central drainage pipe, the horizontal drainage pipe is connected to the branch interface of the longitudinal central drainage pipe through a diverter. The pressure valve is connected in series at the end of the horizontal drainage pipe. When closed, it can block the drainage path, so that the backwash water flow only circulates between the inclined drainage pipe, the Y-type tee, the vertical drainage pipe, and the horizontal drainage pipe (to the pressure valve).

[0047] During normal drainage, the T-type tee diverter remains open, and groundwater flows through the horizontal drainage pipe into the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe according to the preset path. When backwashing of the inclined and horizontal drainage pipes is required, the pressure valve is closed, and a booster pump is connected to the inlet of the vertical drainage pipe (including the vertical pipe connected by the Y-type tee and the vertical pipe connected by the T-type tee). After injecting scale inhibitor, the booster pump is started. When the pressure reaches 1.5-2MPa, the water flows in reverse through the Y-type tee and the inclined drainage pipe, and at the same time through the T-type tee and the front section of the horizontal drainage pipe, flushing the inner wall of the pipe. After flushing, the pressure valve is opened, and the water containing scale and impurities is discharged into the longitudinal drainage system.

[0048] This embodiment also provides a TBM tunnel anti-scaling drainage and pressure reduction construction method, including the following steps: installing inclined drainage pipes, laying horizontal drainage pipes and setting pressure valves, installing vertical drainage pipes, connecting the inclined drainage pipes, horizontal drainage pipes and vertical drainage pipes to each other through Y-type tee diverters, controlling the pressure valves to adjust the groundwater discharge volume, and performing backwashing operations through the vertical drainage pipes.

[0049] Specifically, installing inclined drainage pipes involves fixing them and extending them into the ground; laying horizontal drainage pipes involves arranging them transversely along the tunnel; installing pressure valves involves connecting them in series at the end of the horizontal drainage pipes; and backflushing is a maintenance step that removes scale buildup in the pipes by pressurizing and adding scale inhibitors.

[0050] First, the inclined drainage pipe is driven into the surrounding strata at a 45° angle through the pre-set grouting holes in the tunnel lining, completing the installation of the inclined drainage pipe. Next, a horizontal drainage pipe is laid transversely along the tunnel, with a pressure valve connected in series at its end, and the pressure valve is connected to the tunnel's longitudinal drainage system. Then, the vertical drainage pipe is installed vertically in the pre-set position, with its lower end aligned with the corresponding interface of the Y-type tee diverter. Subsequently, the ends of the inclined, horizontal, and vertical drainage pipes are sequentially inserted into the built-in clips of the Y-type tee diverter, and the outside is sealed with waterproof tape. During the drainage stage, the opening of the pressure valve is adjusted according to the water pressure borne by the tunnel lining to control the groundwater discharge within the pre-set range. When signs of scaling appear in the pipes, a backflushing operation is performed to remove the scale and impurities.

[0051] In one embodiment, the inclined drainage pipe is driven into the grouting hole of the segment lining. The inclined drainage pipe is composed of S-shaped drainage units and wrapped with geotextile. The inclined drainage pipe is made of PVC material. One end of the inclined drainage pipe extends into the surrounding strata, and the other end is connected to the Y-shaped tee diverter.

[0052] Specifically, the grouting holes in the segment lining are pre-designed holes on the segment lining for installing drainage pipes, which can be circular holes with a diameter of 110mm; driving in is the operation of pushing the inclined drainage pipe into the stratum using a small hydraulic hammer; docking is the operation of matching and connecting the near end of the inclined drainage pipe with the interface of the Y-type tee diverter.

[0053] Before construction, clean the debris in the grouting holes of the pipe lining to ensure that the ducts are unobstructed; splice the S-shaped drainage units of PVC material into a complete inclined drainage pipe, and evenly wrap the outside with geotextile, and fix the edge of the geotextile with binding tape; use a small hydraulic hammer to drive the far end of the inclined drainage pipe into the grouting hole until it extends into the surrounding stratum to a predetermined depth (not less than 100cm); adjust the angle of the inclined drainage pipe to ensure that it is inclined at 45°; align the near end interface of the inclined drainage pipe with the corresponding interface of the Y-type tee diverter, slowly insert it until the buckle is tight, and wrap three layers of waterproof tape around the outside of the interface to complete the seal.

[0054] In one embodiment, the Y-type tee diverter has a built-in buckle, into which the ends of the oblique drain pipe, horizontal drain pipe and vertical drain pipe are inserted to achieve a tight connection. Waterproof tape is wrapped around the outside of the Y-type tee diverter, and the end of the horizontal drain pipe is connected to the tunnel longitudinal drainage system. A rotatable sealing cap with a water inlet is installed at the top of the vertical drain pipe.

[0055] Specifically, tight connection refers to fixing the drain pipe and the diverter interface without gaps through the elastic force of the buckle; wrapping with waterproof tape is a sealing operation of evenly wrapping the tape around the outside of the interface; connecting to the tunnel longitudinal drainage system is an operation of fixing the interface of the horizontal drain pipe and the longitudinal drainage facility.

[0056] First, fix the Y-type tee diverter in the preset installation position, ensuring that the three interfaces face the diagonal, horizontal, and vertical directions respectively. Then, insert the ends of the diagonal, horizontal, and vertical drain pipes into the corresponding interfaces in sequence, ensuring the insertion depth is such that the clips are fully engaged in the annular groove, and you can feel a clear tightening feedback. Wipe the outside of the interfaces with a clean cloth to ensure there is no dust or moisture, and then wrap waterproof tape, extending from the diverter body towards the drain pipe, with an overlap width of 1 / 2 of the tape width, and wrapping at least three layers. Align the flange at the end of the horizontal drain pipe with the interface of the tunnel's longitudinal drainage system and secure it with bolts to ensure a tight connection. Finally, screw the rotatable sealing cap with the inlet into the top of the vertical drain pipe and tighten it until there is no looseness, keeping the inlet closed.

[0057] In one embodiment, when backflushing is required, the pressure valve is closed, and a booster pump is connected to the inlet at the top of the vertical drain pipe to inject scale inhibitor into the drainage system. The booster pump is then started to pressurize and backflush the inclined and horizontal drain pipes to remove the deposits and scale inside the pipes.

[0058] Specifically, scale inhibitors are chemical agents that inhibit or remove calcium carbonate scale, and can be polyaspartic acid scale inhibitors; pressurization refers to the operation of increasing the pressure of backwash water flow through a pressurization pump; backwashing refers to the operation of water flowing in the opposite direction through the pipe to flush away scale on the pipe wall.

[0059] When flow monitoring reveals a decrease in drainage efficiency (more than 20%), it indicates scale buildup in the pipes, and a backflushing operation is initiated. First, close the pressure valve at the end of the horizontal drain pipe to block the drainage path. Screw the outlet pipe connector of the booster pump into the inlet at the top of the vertical drain pipe, ensuring a tight, leak-free connection. Add a pre-set dose of polyaspartic acid scale inhibitor through the booster pump's injection port, maintaining a concentration of 500-800 mg / L. Start the booster pump and gradually increase the pressure to 1.5-2 MPa, maintaining this pressure for continuous flushing for 30 minutes. During flushing, the water flows in reverse through the vertical drain pipe and the Y-shaped tee diverter; part of the water enters the inclined drain pipe to flush scale from the pipe wall, while the other part enters the horizontal drain pipe to flush the horizontal section of the pipe wall. After backflushing, turn off the booster pump, disassemble the booster pump connector, open the pressure valve, and discharge the water containing scale impurities and remaining scale inhibitor into the tunnel's longitudinal drainage system. Finally, tighten the rotatable sealing cap.

[0060] In one embodiment, the connection method is selected according to the setting location of the tunnel longitudinal drainage system. When connected to the central main drainage pipe of the invert arch, a T-shaped tee diverter is added to connect the T-shaped tee diverter to the vertical drainage pipe and the horizontal drainage pipe. Waterproof tape is wrapped around the outside of the T-shaped tee diverter so that the horizontal drainage pipe can selectively connect to the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe.

[0061] Specifically, the central main drainage pipe of the invert arch is the main drainage pipe set in the center of the bottom of the tunnel invert arch, which can be a 300mm diameter HDPE double-wall corrugated pipe; the addition of a T-type tee diverter refers to an additional diverting component added in the middle section of the horizontal drainage pipe to expand the vertical backwashing interface.

[0062] Before construction, the location of the tunnel's longitudinal drainage system should be clearly defined. If it is a longitudinal drainage ditch on both sides, the end of the horizontal drainage pipe should be connected to the drainage ditch in the conventional way. If it is a central main drainage pipe in the invert, the pipe should be cut off at a predetermined position in the middle of the horizontal drainage pipe. Connect the two ends of the main channel of the T-shaped tee diverter to the cut end of the horizontal drainage pipe respectively. After insertion, ensure that the buckle is tight and seal the outside with waterproof tape. Connect the newly added vertical drainage pipe to the side channel of the T-shaped tee diverter. Insert the buckle at the lower end for fixation and wrap it with waterproof tape. Install a rotatable sealing cap with a water inlet at the top. Connect the end of the horizontal drainage pipe away from the Y-shaped tee diverter to the branch interface of the central main drainage pipe in the invert through a turning joint, ensuring that the connection is tight and leak-free. During normal drainage, the water flows into the longitudinal central drainage pipe through the horizontal drainage pipe. During backwashing, scale inhibitor and pressurized water can be injected simultaneously from the vertical drainage pipes connected by the Y-shaped tee and the T-shaped tee to flush the entire length of the oblique drainage pipe and the horizontal drainage pipe respectively.

[0063] As an example, the longitudinal drainage of a TBM tunnel is set up in the side ditches on both sides.

[0064] Step 1: Construction of the 45° inclined drainage pipe. Through the pre-drilled drainage holes in the pipe lining, the inclined drainage pipe is driven into the surrounding soil at a 45° angle. The inclined drainage pipe is S-shaped and wrapped with geotextile to prevent clogging. The length of the inclined drainage pipe is greater than 100cm and can be extended as needed. The diameter of the inclined drainage pipe is 100mm. The spacing between the inclined drainage pipes is determined based on hydraulic calculations. After the 45° inclined drainage pipe construction is completed, the end of the drainage pipe is clamped into a Y-type tee for a tight connection and wrapped with transparent tape to prevent air from entering the drainage system.

[0065] Step 2: Vertical drainage pipe construction. Securely connect the end of the vertical drainage pipe to the Y-type tee diverter and wrap it with transparent tape to prevent air from entering the drainage system. A screw-on sealing cap with an inlet is installed at the top of the vertical drainage pipe. This cap isolates the tunnel drainage system from the atmosphere, preventing air entry, reducing CO2 emissions, and inhibiting the deposition of minerals such as calcium carbonate (scaling). A portable booster pump can be connected to the inlet at the top of the vertical drainage pipe for backflushing, pressurizing, and injecting PASP-type scale inhibitors. When backflushing and removing groundwater deposits and scale are required, open the inlet, connect the booster pump, inject the scale inhibitor, and perform pressurized backflushing to remove groundwater deposits and scale.

[0066] Step 3 involves the construction of a 100mm diameter transverse drainage pipe equipped with a pressure valve. This pipe connects to both the inclined and vertical drainage pipes via a Y-shaped tee. The end of the transverse drainage pipe connects to the tunnel's longitudinal side ditch drainage system, directing groundwater into the system for external discharge. A pressure valve at the end of the transverse drainage pipe controls the groundwater discharge rate. When backwashing is required, the pressure valve is closed to efficiently backwash the inclined drainage pipe, allowing for the removal of groundwater deposits and scale. This pressure valve controls the groundwater discharge rate, eliminating groundwater pressure on the tunnel lining and minimizing the impact of groundwater discharge on the surrounding groundwater environment, embodying a combined approach of drainage and containment for groundwater control.

[0067] As an example two, in the case where the longitudinal drainage of the TBM tunnel is located in the main water collection and drainage pipe in the center of the invert arch, steps 1 and 2 are the same as in example one.

[0068] Step 3: Construction of the horizontal drainage pipe with pressure valve. The horizontal drainage pipe has a diameter of 100mm and is connected to the inclined and vertical drainage pipes via a Y-type tee diverter. A pressure valve is installed at the end of the horizontal drainage pipe to control the groundwater discharge. A T-type tee diverter is added to connect the vertical and horizontal drainage pipes. The construction of the vertical drainage pipe is the same as in Step 2 of Example 1, and the construction of the T-type tee diverter is the same as that of the Y-type tee diverter. After the drainage pipe is inserted into the opening, it is wrapped with transparent tape to isolate the drainage system from the outside air exchange. The horizontal drainage pipe is set below the invert arch floor and connected to the main water collection drainage pipe in the center of the tunnel. When descaling of the 45° inclined drainage pipe is required, the pressure valve is closed, and an inhibitor is injected into the vertical drainage pipe 1 for backflushing. When descaling of the horizontal drainage pipe below the floor is required, the pressure valve is closed, and an inhibitor is injected into the vertical drainage pipe 2 for backflushing.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0070] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A TBM tunnel anti-scaling, drainage, and pressure-reducing structure, characterized in that, include: The system includes an inclined drainage pipe, a vertical drainage pipe, a horizontal drainage pipe, a Y-type tee diverter, and a pressure valve. The inclined drainage pipe extends through the gap grouting layer behind the tunnel lining into the surrounding strata. The inclined, vertical, and horizontal drainage pipes are interconnected via the Y-type tee diverter. The end of the horizontal drainage pipe is connected to the tunnel's longitudinal drainage system. The pressure valve is located at the end of the horizontal drainage pipe. The top of the vertical drainage pipe is equipped with a rotatable sealing cap.

2. The structure according to claim 1, characterized in that, The inclined drainage pipe is composed of S-shaped drainage units. The inclined drainage pipe is made of PVC material and is wrapped with geotextile. The geotextile is tightly attached to the inclined drainage pipe. One end of the inclined drainage pipe extends into the surrounding strata, and the other end is fixedly connected to the Y-shaped tee diverter.

3. The structure according to claim 1, characterized in that, The Y-type tee diverter has built-in buckles, and the ends of the inclined drainage pipe, vertical drainage pipe and horizontal drainage pipe are all inserted into the buckles to achieve a tight connection. The Y-type tee diverter is wrapped with waterproof tape. The rotatable sealing cap at the top of the vertical drainage pipe has a water inlet, which can be connected to an external pressure pump. The horizontal drainage pipe receives the groundwater introduced by the inclined drainage pipe through the Y-type tee diverter and transports it to the tunnel's longitudinal drainage system.

4. The structure according to claim 1, characterized in that, The structure also includes a T-shaped tee diverter, which is connected to the vertical and horizontal drainage pipes. The T-shaped tee diverter has a built-in buckle and is wrapped with waterproof tape. The tunnel longitudinal drainage system includes longitudinal drainage ditches on both sides and a longitudinal central drainage pipe. The horizontal drainage pipe can be selectively connected to the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe. When the pressure valve is closed, it can cooperate with the vertical drainage pipe to perform backwashing.

5. A construction method for preventing scaling, draining, and reducing pressure in TBM tunnels, characterized in that, The steps include: installing inclined drainage pipes, laying horizontal drainage pipes and setting pressure valves, installing vertical drainage pipes, connecting the inclined drainage pipes, horizontal drainage pipes and vertical drainage pipes to each other through Y-type tee diverters, controlling the pressure valves to regulate the groundwater discharge, and performing backwashing operations through the vertical drainage pipes.

6. The method according to claim 5, characterized in that, The inclined drainage pipe is driven into the grouting hole of the segment lining. The inclined drainage pipe is composed of S-shaped drainage units and wrapped with geotextile. The inclined drainage pipe is made of PVC material. One end of the inclined drainage pipe extends into the surrounding stratum, and the other end is connected to the Y-type tee diverter.

7. The method according to claim 5, characterized in that, The Y-type tee diverter has a built-in buckle. The ends of the oblique drain pipe, horizontal drain pipe and vertical drain pipe are inserted into the buckle to achieve a tight connection. Waterproof tape is wrapped around the outside of the Y-type tee diverter. The end of the horizontal drain pipe is connected to the tunnel longitudinal drainage system. A rotatable sealing cap with a water inlet is installed at the top of the vertical drain pipe.

8. The method according to claim 5, characterized in that, When backflushing is required, the pressure valve is closed, and a booster pump is connected to the inlet at the top of the vertical drain pipe to inject scale inhibitor into the drainage system. The booster pump is then started to pressurize and backflush the inclined and horizontal drain pipes to remove sediment and scale buildup inside the pipes.

9. The method according to claim 5, characterized in that, The connection method is selected according to the setting location of the tunnel longitudinal drainage system. When connected to the central main water collection and drainage pipe of the invert arch, a T-shaped tee diverter is added. The T-shaped tee diverter is connected to the vertical drainage pipe and the horizontal drainage pipe. Waterproof tape is wrapped around the outside of the T-shaped tee diverter so that the horizontal drainage pipe can selectively connect to the longitudinal drainage ditches on both sides or the longitudinal central drainage pipe.

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