Cold region tunnel drainage pipe anti-crystallization system based on alternating electric field

Abstract

The invention discloses a cold region tunnel drainage pipe anti-crystallization system based on an alternating electric field. The cold region tunnel drainage pipe anti-crystallization system comprises a tunnel body, an annular blind pipe, a radial water guide pipe, a transverse drainage pipe, a conical sediment sedimentation tank and an electric field generation device. The outer walls of the annular blind pipe and the radial water guide pipe are wrapped with titanium alloy net-shaped partition electrodes, alternating voltage with the phase difference of 90 degrees is output through the phase controller to form an alternating electric field, and salt ions are disturbed to inhibit crystal nucleus generation. The electrodes have a heating function, so that positive temperature in the pipe can be realized; auxiliary electrodes are arranged at connecting ports of the annular blind pipe, the radial water guide pipe and the transverse drainage pipe to fill the electric field blind area; the conical sediment sedimentation tank reduces sediment deposition through vibration desilting and an anti-crystallization coating. The system is linked with the temperature and conductivity sensors through the master controller, dynamically adjusts the electric field frequency and the heating power, and adapts to the high-salt and low-temperature working conditions in the cold region. The complex problems of whole-area crystallization prevention and low-temperature icing prevention of the tunnel drainage system in the cold region can be solved.

Description

Technical Field

[0001] The present invention relates to the field of low-temperature anti-crystallization and anti-blocking technology for tunnel drainage systems in cold regions. It uses alternating electric fields as a core method and covers interdisciplinary subjects such as electricity, seepage mechanics, crystallization dynamics and thermodynamics. Background Art

[0002] Tunnel drainage systems in cold regions are a core component for ensuring tunnel structural safety, particularly in the northwest region, where seepage water is salt-rich and winters are harsh. If seepage water is trapped due to a failed drainage channel, it will freeze and expand in the cold. The resulting tremendous frost heave force directly impacts the tunnel lining and supporting structure, causing severe structural damage such as concrete cracking, joint deformation, and even lining spalling. Furthermore, drainage systems in such regions have long been subject to a vicious cycle of salt crystallization and low-temperature freezing. As salt-laden seepage water freezes within the pipes, it displaces salt, causing it to become highly concentrated in the residual liquid phase. When the ice melts, the supersaturated, concentrated salt solution rapidly crystallizes, forming dense obstructions in key locations such as annular blind pipes and longitudinal ditches. This salt-ice synergistic effect significantly accelerates pipe obstruction. Under extreme conditions, a single freeze-thaw cycle can result in visible scale thickening. Blockage leads to a loss of drainage function, further exacerbating the risk of water accumulation and freezing, creating a continuous, destructive cycle of "water accumulation-freezing-salt precipitation-further blockage." This not only threatens the stability of the tunnel structure but also creates a significant maintenance burden.

[0003] Existing methods for cleaning crystallization in drainage pipes mainly include mechanical cleaning and chemical cleaning. The former requires interrupting operations and is difficult to clean pre-buried annular blind pipes and radial water pipes, and the equipment is prone to freezing and failure in severe cold weather. The latter has high scale prevention costs and great environmental risks, and low temperatures can significantly reduce the activity of scale inhibitors. Drain pipe interfaces are prone to forming water accumulation areas due to slow water flow, which is a serious blockage area. Existing technologies generally ignore targeted protection for them. Moreover, ice formation accelerates salt concentration, and high salt levels exacerbate the tendency to crystallize. However, existing solutions treat ice blockage and crystallization in isolation, lacking a comprehensive method that can continuously inhibit crystallization, maintain pipe temperature, and strengthen interface protection at low temperatures. This patent proposes an anti-crystallization system for cold-region tunnel drainage pipes based on an alternating electric field. Indoor experiments have verified that the alternating electric field has a better inhibitory effect on salt crystallization than the static electric field. While satisfying the requirement of AC power supply to inhibit salt crystallization, the system can also use DC power supply to generate Joule heat to heat the drainage pipe to solve the problem of the synergistic deterioration of freezing and crystallization, ensuring the long-term reliable operation of the drainage system in severe cold weather. Summary of the Invention

[0004] To effectively address the aforementioned issues of salt crystallization, low-temperature icing, and blockage in weak areas, the present invention provides a cold-region tunnel drainage pipe anti-crystallization system based on an alternating electric field. By periodically varying the electric field's direction, this system disrupts the directional migration of scale-forming ions, causing them to oscillate repeatedly under the force of the electric field and prevent them from stably concentrating near the pipe wall. Combined with a heating and temperature control design, this system can address the complex challenges of preventing crystallization and low-temperature icing across the entire cold-region tunnel drainage system.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: A cold-region tunnel drainage pipe anti-crystallization system based on an alternating electric field comprises a tunnel body, annular blind pipes, radial aqueducts, transverse drain pipes, a central drain ditch, a conical sedimentation tank, an electric field generator, and a matching temperature control module. The tunnel body is an arched structure. The annular blind pipes embedded in the tunnel lining connect to the radial aqueducts to collect groundwater. Both are equipped with electric field generators to inhibit salt crystallization. The lower end of the annular blind pipes connects to the transverse drain pipes. The conical sedimentation tank is connected to the transverse drain pipes at one end and to the central drain ditch at the other. A vibrating desilter is installed on the tank wall.

[0006] As a feasible solution, metal mesh electrodes are used as the electrode material in the electric field generating devices on the annular blind pipe and radial water pipe, and metal arc electrodes are used as the electrode material in the electric field generating devices on the transverse drainage pipe and the central drainage pipe. The electrodes are divided into four independent partitions along the annular direction, and the adjacent partition electrodes are isolated by insulating rubber strips to form a circumferential alternating electric field. The metal electrodes also serve as heating elements, which can maintain the pipe wall temperature above the freezing temperature of the flowing water in a low-temperature environment, ensuring smooth water flow in the pipe.

[0007] As a feasible implementation plan, the inner layer of the above-mentioned electrode is insulated with a thick silicone rubber insulation pad and fitted to the surface of the pipeline. This can not only ensure the safety of the circuit, but the low-temperature elastic properties of the silicone rubber can also buffer the frost heave stress. The outer layer is insulated with a micro-arc oxidation ceramic layer, which has the advantages of being resistant to low temperatures and corrosion, and has a smooth surface that is not easily adhered to ice crystals and salt crystals.

[0008] As an implementable solution, silicone rubber spacers are used to insulate and separate the four independent electrodes.

[0009] As a feasible solution, water guide holes are evenly opened on the surface of the radial water guide pipe to enhance the water flow capacity of the drainage system. The diameter of the water guide hole is 8-10mm, and an arc-shaped auxiliary electrode is set at the connection between the water guide hole and the annular blind pipe.

[0010] As a feasible solution, an auxiliary electrode is provided at the connection between the annular blind pipe and the transverse drainage pipe.

[0011] As a feasible implementation plan, the bottom of the conical sedimentation tank is an inverted cone with a cone angle set to 50-70 degrees, which accelerates the sediment and water to slide to the bottom. The inner wall of the tank is provided with an anti-crystallization coating to reduce the adhesion of the sediment to the tank wall. A piezoelectric vibrator is installed on the tank wall, which is electrically connected to the main controller to vibrate the sediment on the tank wall to loosen it and facilitate cleaning by the staff. The input interface of the vibration sedimentation tank is higher than the output interface to discharge seepage water.

[0012] As an implementable solution, the current monitoring unit is provided with a DC Hall sensor and four AC Hall sensors; the DC Hall sensor is connected in series between the AC / DC switching power supply and the metal mesh electrode to detect the heating circuit current, and the AC Hall sensor is connected in series between the phase controller and the four partitions to detect the electric field current of each phase to ensure normal power supply.

[0013] As an implementable embodiment, the AC / DC switching power supply of the power supply device of all electrical facilities of the present invention is set in the tunnel maintenance channel and connected to the main controller. The main controller is connected to the phase controller, temperature sensor, and conductivity sensor to adjust the electric field parameters and heating power according to the temperature and conductivity values.

[0014] As an implementable solution, the temperature sensor uses a PT100 platinum resistor, which is installed between the metal electrode and the pipe wall to directly detect the pipe wall temperature and avoid environmental interference.

[0015] As an implementable solution, the conductivity sensor adopts an inductive conductivity sensor, which performs non-contact measurement and avoids structural influence.

[0016] As a feasible solution, all the above electrical equipment are connected by waterproof cables.

[0017] The beneficial effects of the present invention are: The alternating electric field generated on each pipe in the drainage system drives the dynamic migration of ions, disrupting the directional growth conditions of crystal nuclei. Four independent zones, divided by metal electrodes, are controlled by a phase controller, applying alternating voltages with a 90° phase difference. This prevents salt ion accumulation near a single electrode, solving the electrode scaling problem associated with traditional DC electric fields. By utilizing the electrical resistance of the metal electrodes and heating them with DC power, the pipe wall temperature is maintained above the freezing point of the flowing water, preventing ice from forming. Simultaneously, the alternating electric field inhibits salt ion crystallization, achieving electrothermal coupling to prevent ice crystallization. A conical sediment settling tank rapidly separates sediment from seepage water collected by radial aqueducts and annular blind pipes, preventing it from flowing into the central drain and reducing the difficulty of sediment removal. The system integrates temperature and conductivity sensors, and the main controller adjusts the electric field frequency, heating power, and piezoelectric vibrator desilting cycle in real time, realizing an intelligent operation and maintenance system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a schematic cross-sectional view of the present invention;

[0019] Figure 2 It is a schematic diagram of radial aqueduct and metal mesh electrode;

[0020] Figure 3 This is a schematic diagram of the installation of metal arc electrodes on the horizontal drain pipe and the central drain pipe;

[0021] Figure 4 This is a schematic diagram of the auxiliary electrode at the pipeline connection;

[0022] Figure 5 This is the connection diagram of the AC power supply circuit for suppressing salt crystallization;

[0023] Figure 6 This is the connection diagram of the DC powered Joule heating circuit. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described in detail below with reference to specific embodiments. It should be noted that the embodiments described in the accompanying drawings are only exemplary and intended to explain the present invention, rather than to limit the scope of protection of the present invention.

[0025] In the description of the present invention, directional terms (such as "up, down, left, right, inside, outside") are defined based on the relative position relationship of the drawings in the specification. In actual engineering applications, the absolute layout positions of each component can be reasonably adjusted according to the tunnel structure, geological conditions and construction requirements. Regarding the unified explanation of practical terms: "seepage" and "flowing water" characterize the existence form and movement state of water in the drainage system. The two are used equivalently in the present invention. "Anti-crystallization", "anti-scaling" and "scale inhibition" all refer to the core function of inhibiting the growth of salt crystals. The three have the same meaning in the present invention.

[0026] Those skilled in the art should understand that the specific meanings of the above terms in the embodiments can be adaptively interpreted according to the tunnel engineering environment, water quality composition and anti-clogging goals.

[0027] The main body of the tunnel (1) adopts a composite lining structure, including an initial support (11) and a secondary lining (12). An annular blind pipe installation groove is reserved between the initial support (11) and the secondary lining (12).

[0028] The annular blind pipe (2) uses a HDPE permeable pipe with a polyester fiber filter cloth wrapped around the outer wall to filter water and reduce the ingress of sediment. The outer side of the annular blind pipe (2) is wrapped with a titanium alloy mesh electrode. The electrodes are evenly provided with 8mm permeable holes to match the permeable holes of the annular blind pipe filter cloth to prevent the permeable holes from being too small and causing sediment to clog the mesh. The electrodes are evenly divided into four independent partitions along the annular direction. The partitions are separated by 2mm thick silicone rubber insulation strips (11d). The electrodes are fixed with nylon clamps and are 1mm apart from the filter cloth to prevent squeezing the filter cloth and affecting water permeability.

[0029] When installing the annular blind pipe, first clean the initial support surface to avoid uneven force on the electrode; the metal mesh electrode is fixed with a clamp, and the waterproof cable is laid along the direction of the blind pipe.

[0030] The surface of the metal electrode is coated with a 5-10 μm ruthenium-iridium coating. If the coating is too thin, the metal electrode will wear out in a high-salt environment. If the coating is too thick, the electrode resistance will increase and the electric field efficiency will be reduced. The inner layer of the metal electrode is made of a silicone rubber insulation thick pad (11c), which fits the outer surface of the blind pipe. The outer layer is sprayed with a 20 μm micro-arc oxidation ceramic layer. The ceramic layer can accelerate transverse heating and improve heating efficiency. At the same time, the breakdown voltage of the coating reaches thousands of volts, which can ensure the insulation effect. The outermost layer is a polyurethane foam layer (11b) to reduce heat loss. A temperature sensor (91) is embedded between the annular blind pipe (2) and the silicone rubber insulation thick pad (11c) to monitor the wall temperature of the annular blind pipe (2) and transmit the monitoring data to the main controller. When the temperature drops to 1°C, the DC power supply Joule heating is started to maintain the temperature inside the pipe above the freezing temperature of the flowing water.

[0031] The surface spraying process and insulation measures of the auxiliary electrode are the same as those of the metal electrode; the auxiliary electrode has only two electrodes and only needs to input a single-phase alternating voltage. It is installed at the interface of the drainage pipe in the form of a clamp.

[0032] The radial water conduit (3) is an ABS straight pipe with a diameter of 100 mm. Water conduit holes with a diameter of 8 mm are evenly opened on the pipe wall. One end of the radial water conduit (3) is connected to the annular blind pipe (2) through an auxiliary electrode, and the other end is inserted into the surrounding rock structure to collect tunnel seepage. The auxiliary electrode is connected in parallel with other electrodes through a waterproof cable (10) to cover the electric field blind area of ​​the connection port. The auxiliary electrode is rounded at the edge to avoid scratching the sealing rubber ring.

[0033] The horizontal drainage pipe (6) is made of HDPE pipe with a diameter of 100 mm. One end is connected to the annular blind pipe (2) through an auxiliary electrode (34 / 65), and the other end is connected to the conical sedimentation tank (5). The outer surface is wrapped with a titanium alloy arc electrode. The electrode is evenly divided into four independent zones along the annular direction. The zones are separated by 2 mm thick silicone rubber insulation strips (11d). The electrodes are fixed with nylon clamps. The insulation treatment is the same as that of the annular blind pipe (2).

[0034] The conical sedimentation tank (5) is cast with C30 reinforced concrete, with a cone angle of 60°. The surface of the tank wall is sprayed with a polytetrafluoroethylene nano-coating to reduce the friction between the sediment particles and the tank wall, quickly separating the sediment from the seepage water. Piezoelectric vibrators are installed on the tank wall and bottom, electrically connected to the main controller, to break up the deposited sediment and facilitate personnel to collect and clean the sediment. The output end of the sedimentation tank is connected to the horizontal drainage pipe (6), and the input end interface is higher than the output end interface, which is used to discharge the sediment seepage water.

[0035] The AC / DC switching power supply (9) is powered by the tunnel grid via a transformer, with a diesel generator and solar photovoltaic panels as backup power sources. The power supply is connected to other electrical appliances via a waterproof cable (10). The metal electrodes can generate an alternating electric field and also perform Joule heating via DC power supply. The phase controller (95) outputs an alternating voltage with a phase difference of slightly 90° and adjustable frequency, which is connected to the four electrode partitions to form an alternating electric field to inhibit salt crystallization. When the temperature is detected to be too low, the AC / DC switching power supply (9) outputs DC power, which is connected to the DC Hall sensor (93) for Joule heating.

[0036] The temperature sensor is embedded between the silicone rubber insulation pad (11c) and the drain pipe. A PT100 platinum resistance temperature sensor is used to monitor the closing temperature. The conductivity sensor uses an inductive conductivity sensor. The surface of the conductivity sensor is sprayed with a 20μm micro-arc oxidation ceramic layer to prevent salt corrosion and provide insulation protection, and is glued to the bottom of the pipe.

[0037] Water seeping from the tunnel surrounding rock penetrates through the radial water pipe (3) into the annular blind pipe (2), where it is filtered by the filter cloth and then enters the pipe. The alternating electric field generated by the metal mesh electrode (4a) disturbs the salt ions and inhibits the formation of crystal nuclei. The seeping water flows through the annular blind pipe (2) into the transverse drainage pipe (6). After entering the conical sedimentation tank, the flow rate decreases and the sediment settles under the action of gravity. The piezoelectric vibrator is activated regularly to clean the sediment attached to the tank wall. The supernatant is discharged through the output end drainage port into the transverse drainage pipe (6) and discharged out of the tunnel through the central drainage ditch (7).

[0038] The control logic of the main controller is as follows: when the temperature detector detects that the tube wall temperature is lower than 1°C, DC power supply heating is started, and the heating power is reduced as the temperature rises; when the conductivity value is greater than 4000μS / cm, the alternating electric field frequency is increased to enhance ion movement, and the alternating electric field frequency is reduced as the conductivity value decreases; when the temperature is greater than 5°C and the conductivity value is less than 500μS / cm, DC power supply and AC power supply are operated intermittently; when the temperature is greater than 10°C, heating is stopped.

Claims

1. A cold region tunnel drainage pipe anti-crystallization system based on an alternating electric field, characterized by: The invention comprises a tunnel body (1), an annular blind pipe (2), a radial water pipe (3), a conical sedimentation tank (5), a transverse drainage pipe (6), a central drainage ditch (7) and an electric field generating device. The tunnel body (1) is an arched tunnel; the annular blind pipe (2) is arranged at the bottom of the lining along the annular direction of the tunnel, and collects lining seepage water through the radial water pipe (3); the radial water pipe (3) has water guide holes evenly opened on its surface, one end of which is connected to the annular blind pipe (2), and the other end is inserted into the surrounding rock outside the initial support (11); the transverse drainage pipe (6) has an input end connected to the annular blind pipe (2) and an output end connected to the conical sedimentation tank (5), and is used to transport the seepage water to the sedimentation tank to separate water and sediment; the electric field generating device comprises an AC / DC switching power supply (9), a metal mesh electrode (4a), a metal arc electrode (11a), a phase controller (95) and a current monitoring unit; the temperature control module comprises a temperature sensor (91) and a main controller.

2. The system according to claim 1, wherein: The electric field generating device comprises a metal mesh electrode (4a), a metal arc electrode (11a), a phase controller (95), an AC / DC switching power supply (9) and a current monitoring unit; the metal mesh electrode (4a) is tightly wrapped around the outer wall of the annular blind pipe (2) and the radial water conduit (3); the metal arc electrode (11a) is wrapped around the outer wall of the transverse drainage pipe (6) and the central drainage pipe; the two electrodes are divided into four independent partitions along the annular direction, and the partitions are isolated by silicone rubber insulating strips (11d); the phase controller (95) outputs an alternating voltage with a phase difference of 90°, which is connected to the four partitions to form an alternating electric field for inhibiting salt crystallization.

3. The system according to claim 1, wherein: The metal mesh electrode (4a) is a metal sheet with water-conducting holes evenly provided thereon; the surfaces of the metal mesh electrode (4a) and the metal arc electrode (11a) are plated with a ruthenium-iridium coating.

4. The system according to claim 2, wherein: The metal mesh electrode (4a) and the metal arc electrode (11a) are provided with an insulating layer and a heat preservation layer; the inner layer of the insulating layer is insulated with a thick silicone rubber insulating pad (11c), and the outer layer is sprayed with a micro-arc oxidation ceramic layer for insulation; the heat preservation layer is a polyurethane foam layer (11b).

5. The system according to claim 1, wherein: An auxiliary electrode (41) and an auxiliary electrode (42) are sleeved on the outside of the connection between the annular blind pipe (2) and the radial water pipe (3) and the transverse drainage pipe (6); both auxiliary electrodes are metal annular sheets, the shape of which fits the pipe interface, and are electrically connected in parallel with the metal mesh electrode (4a).

6. The system according to claim 1, wherein: The current monitoring unit comprises a DC Hall sensor (93) and four AC Hall sensors (94); the DC Hall sensor (93) is connected in series between the AC / DC switching power supply (9) and the metal electrode; and the AC Hall sensors (94) are connected in series between the phase controller (95) and the four partitions.

7. The system according to claim 1, wherein: The temperature control module comprises a main controller, a metal electrode and a temperature sensor (91); the temperature sensor (91) is placed on the outer surface of the pipeline; the main controller is respectively connected to the phase controller (95), the AC / DC switching power supply (9), the conductivity sensor (92), and the temperature sensor (91).

8. The system according to claim 7, characterized in that The temperature control logic of the temperature control module is as follows: when the temperature sensor (91) detects that the surface temperature of the annular blind pipe (2) is lower than 1°C, the main controller controls the AC / DC switching power supply (9) to control the DC power supply to start heating; when the temperature is greater than 10°C, the DC power supply heating is automatically cut off.

9. The system according to claim 7, characterized in that: The conductivity sensor (92) is placed on the inner surface of each pipe.

10. The system according to claim 1, wherein: The inner wall of the conical sediment sedimentation tank (5) is provided with an anti-crystallization coating, and the tank wall is provided with a vibration mud removal device; the anti-crystallization coating is a polytetrafluoroethylene nano-coating, which is used to reduce the adhesion between the sediment and the tank wall; the vibration mud removal device is a piezoelectric vibrator, which is electrically connected to the main controller, and the height of the sedimentation tank input end interface is higher than the output end interface.

11. The system according to claim 1, wherein: The power supply system of the electric field generating device and the temperature control module is an AC / DC switching power supply (9); the AC / DC switching power supply (9) is placed in the tunnel maintenance passage.

Images