A mud cake preventing structure for a slurry shield for high viscosity strata

Abstract

A mud cake preventing structure for a slurry shield in a high viscosity stratum, comprising a slurry bin main slurry discharge pipe, a stone box, a clean water tank, a stone box slurry taking pipe, a first pressure pump, a second pressure pump, a slurry bin center flushing port and a cutter head center water jet port; the slurry bin main slurry discharge pipe is communicated with the stone box, the stone box is internally provided with a stone box filter screen barrel, the slurry outlet end of the stone box filter screen barrel is communicated with the stone box slurry taking pipe; the clean water tank is provided with a dilution pipeline and a water delivery pipeline; the dilution pipeline and the stone box slurry taking pipe are communicated in sequence after confluencing, the first pressure pump, the slurry bin center flushing port; the water delivery pipeline is communicated in sequence with the second pressure pump, the cutter head center water jet port. The structure is suitable for complex tunneling conditions in a high viscosity stratum, realizes low viscosity flushing and stratum face viscosity reduction on the basis of not affecting the stable operation of the original slurry circulation residue carrying system, so as to inhibit the formation of cutter head mud cake.

Description

Technical Field

[0001] This invention relates to the field of shield tunneling technology in high-viscosity strata, and particularly to a structure for preventing mud cake formation during tunneling in such strata using the slurry shield method. Background Technology

[0002] Currently, the industry generally adopts conventional comprehensive prevention and control methods to address the problem of mud cake formation in high-viscosity strata during slurry shield tunneling. These methods mainly include three categories: mud flushing, chemical modification, and optimization of tunneling parameters. The specific technical solutions are as follows: 1. Increase the speed of the ground mud conveying pump and increase the flow rate of the main inlet pipe to flush the mud and water tank; at the same time, take mud from the main inlet and flush the center of the mud and water tank directly through the P0.1 pump to remove the mud cake on the back of the cutter head.

[0003] Second, by quantitatively injecting a dispersant into the mud-water chamber, the cutter head and the formed mud cake in the chamber are continuously soaked, softened, and dissociated, thereby weakening and removing the mud cake.

[0004] Third, optimize tunneling parameters such as tunneling speed, cutterhead rotation speed, and total thrust to suppress the formation of mud cake at the source.

[0005] While the aforementioned existing technologies can alleviate the problem of cutterhead cake formation to some extent, they all have significant technical defects and application limitations in practical applications under complex conditions of high-viscosity formations, and cannot fundamentally cure the cake problem. The specific defects are as follows: Firstly, taking slurry from the main inlet pipe reduces its flow rate, thus weakening the unloading and flushing effect on the mud-water circulation system. Secondly, the conventional mud transported through the main inlet pipe has a relatively high viscosity, which is not conducive to the effective flushing of high-viscosity formations. If the viscosity of the main inlet pipe is reduced to improve the flushing effect, the slag-carrying capacity of the mud circulation system will be significantly weakened. Furthermore, after the mud is prepared in the surface mixing tank, it needs to be transported to the mud-water storage tank via long-distance pipelines. Due to the large diameter of the pipelines, old slurry may remain inside. Even if the viscosity of the mud in the main inlet pipe is adjusted to the required value on the surface, after long-distance transport and mixing with the residual slurry in the pipes, the actual viscosity of the mud entering the mud-water storage tank is difficult to control accurately, ultimately affecting the flushing effect and slag-carrying capacity.

[0006] Secondly, the method of modifying the dispersant has construction safety hazards. Although soaking the mud cake and surrounding strata with dispersant for a long time can soften and separate the mud cake, it will simultaneously soften the original high-viscosity soil structure around the shield tunnel, significantly reduce its strength, and destroy the original stability of the strata. This can easily cause uneven settlement of the ground above the tunnel, and in severe cases, it can cause ground collapse, greatly increasing the construction risk and limiting the applicability of the working conditions.

[0007] Furthermore, simply relying on optimizing tunneling parameters is insufficient to fundamentally solve the mud cake problem.

[0008] In summary, existing anti-mud cake technologies generally suffer from numerous drawbacks, including limited mud removal efficiency, susceptibility to ground instability, and inability to address the root cause of mud cake formation. These limitations make it difficult to meet the demands of safe, efficient, and stable tunneling operations using slurry shield tunneling in highly viscous formations. Therefore, the core technical problem this invention aims to solve is to provide a technical solution that effectively prevents mud cake formation, mitigates construction safety risks, and adapts to the complex conditions of highly viscous formations. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a structure to prevent mud cake formation during tunneling in this type of stratum using the slurry shield tunneling method. This structure is suitable for complex tunneling conditions in high-viscosity strata and achieves low-viscosity scouring and face viscosity reduction without affecting the stable operation of the original slurry circulation and muck-carrying system, thereby suppressing the formation of cutterhead mud cake.

[0010] To achieve the above objectives, the present invention provides a slurry shield tunneling anti-mud cake structure for high-viscosity strata, comprising a slurry chamber main discharge pipe, a quarry box, a clean water tank, a quarry box slurry intake pipe, a first pressurizing pump, a second pressurizing pump, a slurry chamber central flushing port, and a cutterhead central spray nozzle. The main discharge pipe of the mud and water tank is connected to the quarry box. The quarry box is equipped with a quarry box filter screen barrel inside. The discharge end of the quarry box filter screen barrel is connected to the quarry box slurry intake pipe. The clean water tank is equipped with dilution pipelines and water delivery pipelines; The dilution pipeline is connected to the slurry intake pipe of the quarry box for convergence, and the pipeline section after convergence is connected in sequence to the first pressurization pump and the central flushing port of the mud and water tank. The water supply pipeline is connected in sequence to the second booster pump and the central spray nozzle of the cutter head.

[0011] As a further improvement of the present invention, a ground mud-water screening station is also provided. The main discharge pipe of the mud-water silo is provided with a first bypass pipe and a second bypass pipe. The first bypass pipe is connected to the quarry box, and the second bypass pipe is connected to the ground mud-water screening station.

[0012] As a further improvement of the present invention, a quarry gate valve is provided on the first bypass pipeline; a bypass filter and a bypass slurry discharge gate valve are provided on the second bypass pipeline.

[0013] As a further improvement of the present invention, a ground mud and water screening station is also provided. A quarry filter screen is provided on the side wall of the quarry box. The quarry box filter screen is connected to the main slurry discharge pipe of the quarry box, and the main slurry discharge pipe of the quarry box is connected to the ground mud and water screening station.

[0014] As a further improvement of the present invention, a quarry slurry discharge gate valve is provided on the main slurry discharge pipe of the quarry box.

[0015] As a further improvement of the present invention, a one-way valve is provided on the dilution pipeline, and the conduction direction of the one-way valve is limited to flow from the clean water tank to the slurry extraction pipe of the quarry tank.

[0016] As a further improvement of the present invention, a slurry sampling test box is connected to the pipe section after the dilution pipeline and the slurry sampling pipe of the quarry box converge. A slurry sampling test gate valve is provided between the slurry sampling test box and the pipe section. The slurry sampling test box is used to detect the viscosity and density parameters of the mud in the pipeline in real time.

[0017] As a further improvement of the present invention, it also includes a flow detection device, a linkage control device, and a shield tunneling drive system. The flow detection device is installed on the central water jet of the cutterhead. The linkage control device is electrically connected to the flow detection device and the shield tunneling drive system respectively. The linkage control device is configured to collect the flow signal of the central water jet of the cutterhead in real time, and control the tunneling of the shield by linkage with the shield tunneling drive system according to the flow signal.

[0018] As a further improvement of the present invention, the linkage control device has a built-in flow threshold logic module, which sets the minimum protection flow rate to 250L / min. When the flow rate at the center nozzle of the cutterhead is detected to be <250L / min, the linkage control device outputs a lock signal to lock the shield tunneling drive system, prohibiting the shield from advancing. When the detected flow rate recovers to ≥250L / min, the linkage control device releases the lock on the shield tunneling drive system, allowing the shield to resume tunneling.

[0019] The beneficial effects of this invention are as follows: This invention abandons the traditional flushing mode of diverting slurry from the main slurry inlet pipe, and innovatively adopts an independent slurry extraction method from the quarry slurry extraction pipe. This method does not occupy the main slurry inlet flow throughout the process and is only used for local flushing. Therefore, it does not change the overall viscosity of the slurry inside the slurry chamber, and does not interfere with the high-flow-rate mud circulation of the shield tunneling machine's slag-carrying and slag-discharging functions. This completely solves the technical contradiction between flushing effect and slag-carrying capacity in traditional technologies. Simultaneously, this invention adds a clean water pipeline to the quarry slurry extraction pipe to reduce the viscosity of the central flushing slurry, achieving low-viscosity mud flushing in the center, thereby significantly improving the flushing and stripping effect on sticky slag.

[0020] Meanwhile, the present invention features an independent cutterhead center water spray structure that continuously sprays water onto the tunnel face during the tunneling process. This, combined with the low-viscosity scouring at the center of the slurry chamber, forms a dual mud-suppressing structure. Under the dual effects of "low-viscosity center scouring" and "center water spraying," the viscous slag after cutting can smoothly enter the slurry chamber through the cutterhead panel opening and be carried out with the large circulation of slurry, thereby effectively inhibiting the adhesion and accumulation of slag on the cutterhead and preventing the formation of mud cakes on the cutterhead.

[0021] This invention enables the secondary recycling of slurry, has strong adaptability to working conditions, and does not require major modifications to the original shield tunneling circulation system. It avoids the risks of ground softening, ground subsidence and collapse caused by traditional dispersant soaking, and overcomes the drawback of simply optimizing parameters not being able to completely eliminate mud cake. It fundamentally solves the industry technical problem of mud cake formation on the cutterhead of slurry shield tunneling machines in high-viscosity strata, effectively improves shield tunneling efficiency, and ensures the safety and quality of tunnel construction in high-viscosity strata. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; Labeling descriptions: 1. Main slurry discharge pipe of slurry chamber; 2. Quarry box; 3. Clean water tank; 4. Slurry sampling pipe of quarry box; 5. First pressurization pump; 6. Second pressurization pump; 7. Central flushing port of slurry chamber; 8. Central spray nozzle of cutterhead; 9. Ground slurry screening station; 10. Slurry sampling test box; 11. First bypass pipeline; 12. Second bypass pipeline; 13. Quarry box gate valve; 14. Filter screen; 15. Bypass slurry discharge gate valve; 16. Quarry box filter screen bucket; 17. Quarry box filter screen; 18. Quarry box main slurry discharge pipe; 19. Quarry box slurry discharge gate valve; 20. Dilution pipeline; 21. Water supply pipeline; 22. Check valve; 23. Flow detection device; 24. Linkage control device; 25. Shield tunneling drive system. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0024] like Figure 1 As shown, a mud cake prevention structure for slurry shield tunneling in high-viscosity strata is applicable to slurry shield tunneling in strata prone to mud cake formation, such as high-viscosity clay and silty clay. It can achieve low-viscosity scouring at the center of the slurry chamber, continuous flushing of the cutterhead face, and linkage safety protection during tunneling without interfering with the original slurry circulation and muck-carrying system, effectively suppressing the formation of cutterhead mud cake.

[0025] This structure includes a main slurry discharge pipe 1 for the mud and water silo, a quarry box 2, a clean water tank 3, a slurry extraction pipe 4 for the quarry box, a first pressurizing pump 5, a second pressurizing pump 6, a central flushing port 7 for the mud and water silo, a central spray nozzle 8 for the cutter head, a ground mud and water screening station 9, a pipeline control valve group, a slurry extraction test box 10, and a linkage control system.

[0026] During normal tunneling of a slurry shield tunnel, the slurry carrying excavated soil in the slurry chamber is transported outward through the main slurry discharge pipe 1 of the slurry chamber. In this invention, a first bypass pipe 11 and a second bypass pipe 12 are respectively installed on the main slurry discharge pipe 1 of the slurry chamber. The first bypass pipe 11 is connected to the quarry box 2 and is equipped with a quarry box gate valve 13. The second bypass pipe 12 is connected to the ground slurry screening station 9, and a bypass filter screen 14 and a bypass slurry discharge gate valve 15 are installed on the second bypass pipe 12 in sequence. During construction, slurry diversion can be achieved through two bypass pipelines: opening the quarry gate valve 13 and closing the quarry slurry discharge gate valve 19 allows some slurry to be stored inside the quarry 2 as a source of slurry for central flushing; the other part of the slurry is directly transported to the ground mud and water screening station 9 for conventional screening after being filtered through the second bypass pipeline 12 and the bypass filter screen 14 to remove large particles of impurities, thus ensuring the stable operation of the shield tunnel's overall slurry circulation system.

[0027] The quarry box 2 is equipped with a quarry box filter screen barrel 16, and the slurry outlet of the quarry box filter screen barrel 16 is connected to the quarry box slurry extraction pipe 4. The slurry stored in the quarry box 2 is filtered by the quarry box filter screen barrel 16, intercepting large particles of impurities such as mud clumps and gravel in the slurry. The filtered clean slurry flows from the slurry outlet of the quarry box filter screen barrel 16 into the quarry box slurry extraction pipe 4, effectively preventing blockage of the subsequent flushing pipeline and pump body. At the same time, a quarry box filter screen 17 is installed on the side wall of the quarry box 2. The quarry box filter screen 17 is connected to the quarry box main slurry discharge pipe 18 and connected to the ground mud and water screening station 9. A quarry box slurry discharge gate valve 19 is installed on the quarry box main slurry discharge pipe 18. When the slurry stored in the quarry box 2 is too large or when slurry extraction and flushing are not required, the quarry box slurry discharge gate valve 19 can be opened to filter the excess slurry and discharge it into the ground mud and water screening station 9, ensuring a stable liquid level inside the quarry box 2 and providing stable operating conditions for continuous slurry extraction. The main slurry discharge pipe 18 of the quarry box and the second bypass pipe 12 are connected and merged to the ground mud and water screening station 9. The quarry box 2 serves as a container for storing mud and is also used to intercept large stones carried in the mud. It needs to be manually cleaned regularly.

[0028] The clean water tank 3 is equipped with a dilution pipeline 20 and a water supply pipeline 21. The dilution pipeline 20 connects to the slurry extraction pipe 4 of the quarry to achieve pipeline convergence. A one-way valve 22 is installed on the dilution pipeline 20, which strictly limits the flow direction to flow from the clean water tank 3 to the slurry extraction pipe 4 of the quarry, effectively preventing the backflow of mud from the quarry 2 into the clean water tank 3 and ensuring the cleanliness of the clean water pipeline. A slurry sampling test box 10 is connected to the section of the pipeline after the convergence of the dilution pipeline 20 and the slurry extraction pipe 4 of the quarry. A slurry sampling test gate valve is installed between the slurry sampling test box 10 and the slurry extraction pipe 4 of the quarry. During construction, the slurry sampling test gate valve can be opened periodically, and the viscosity and density of the mud in the flushing pipeline can be detected in real time through the slurry sampling test box 10, so as to achieve dynamic monitoring and precise control of the flushing medium performance. Specifically, during the tunnel boring machine (TBM) excavation, a slurry sample is manually taken from the slurry testing box 10 every 500mm of advance, and tested using a mud hydrometer and a Marsh funnel. The slurry viscosity is controlled at 17-19 seconds, and the density is controlled at 1.05-1.08 g / cm³. 3 This maximizes the softening, stripping, and flushing effects of high-viscosity formation mud cake. If the measured viscosity or density exceeds the above parameter range, dilution pipeline 20 is opened to inject clean water into the slurry intake pipe 4 of the quarry box for dilution. The diluted mud is then transported to the first pressurization pump 5 via the slurry intake pipe, and then the first pressurization pump 5 sends the diluted low-viscosity mud to the central flushing port 7 of the mud-water tank, thereby reducing the mud cake.

[0029] The flushing pipeline after the confluence is sequentially connected to the first pressurizing pump 5 and the central flushing port 7 of the slurry tank. The first pressurizing pump 5 provides pressure to the diluted low-viscosity slurry, pressurizing and delivering it to the central flushing port 7 of the slurry tank, achieving fixed-point high-pressure flushing. This invention, by independently drawing slurry from the main discharge pipe 1 of the slurry tank and diluting and adjusting the viscosity online with clean water, is completely different from the traditional main slurry feed diversion flushing mode. It does not change the slurry parameters of the main feed slurry throughout the process, nor weakens the large-flow circulation and slag-carrying capacity of the slurry tank, thus completely solving the contradiction between the flushing effect and slag-carrying performance of traditional technologies.

[0030] The water supply pipeline 21 of the clean water tank 3 is independently set up, and is sequentially connected to the second pressurizing pump 6 and the central water spray nozzle 8 of the cutterhead, forming an independent face flushing and spraying structure. During the tunneling process, the clean water is pressurized by the second pressurizing pump 6 and continuously sprayed out from the central water spray nozzle 8 of the cutterhead, directly acting on the tunnel face to flush, reduce viscosity, and dissociate the high-viscosity strata to be cut, greatly reducing the soil's adsorption and agglomeration capacity. Under the dual action of "low-viscosity central flushing" and "central water spraying", the cut cohesive soil can smoothly enter the slurry chamber through the cutterhead panel opening and be carried out with the large circulation of slurry, thereby effectively inhibiting the adhesion and accumulation of soil on the cutterhead and preventing the formation of mud cakes on the cutterhead.

[0031] The linkage control system comprises a flow detection device 23, a linkage control device 24, and a tunnel boring machine (TBM) drive system 25, forming an intelligent linkage protection system. The flow detection device 23 is installed at the central water nozzle 8 of the cutterhead to collect the water flow signal in real time. The linkage control device 24 is electrically connected to both the flow detection device 23 and the TBM drive system 25, and has a built-in flow threshold logic module, preset to a minimum protection flow of 250 L / min. During construction, the linkage control device 24 monitors the central water flow of the cutterhead in real time: when the detected flow is less than 250 L / min, it determines that the tunnel face is short of water and there is a risk of dry cutting and mud formation, immediately outputting a lock signal to lock the TBM drive system 25, prohibiting the TBM from advancing, and strengthening the central water spray to continuously act on the tunnel face; when the water flow recovers to 250 L / min or above, the system automatically releases the lock, allowing the TBM to resume normal tunneling operations.

[0032] The overall construction process of this invention is as follows: When the tunnel boring machine (TBM) is excavating in high-viscosity strata, the slurry from the slurry chamber is diverted through the main slurry discharge pipe 1. One stream is stored in the quarry box 2, filtered, and then connected to the quarry box slurry intake pipe 4. The viscosity is adjusted online through the dilution pipe 20 in the clean water tank 3 to prepare a low-viscosity, high-pressure flushing medium, which continuously flushes the center of the slurry chamber and the back of the cutterhead. The other stream directly enters the ground screening system for processing, ensuring the stability of the main circulation system. Simultaneously, an independent cutterhead center water spray system continuously flushes the working face, forming a double mud-suppressing structure in conjunction with the slurry chamber center flushing. This allows the high-viscosity slag generated during cutting to smoothly enter the slurry chamber through the cutterhead panel opening and be quickly discharged with the high-flow circulation slurry. Combined with a flow-linked self-locking protection mechanism, the risk of dry cutting and mud formation is completely eliminated. No dispersant needs to be added throughout the process, preventing strata softening and ground subsidence problems. This enables long-term stable shield tunneling in high-viscosity strata without mud cake.

[0033] In summary, this invention features a simple structure, convenient construction, low cost, and strong adaptability to various working conditions. Through multiple technical means, including secondary recycling of slurry, online viscosity adjustment and flushing, continuous flushing of the tunnel face, and intelligent linkage protection of tunneling flow, it fundamentally solves the technical problem of easy mud cake formation on the cutterhead during the tunneling of existing slurry shield tunnels in high-viscosity strata. This effectively improves the tunneling efficiency of shield tunneling and ensures the safety and quality of tunnel construction.

[0034] The above-described embodiments are merely illustrative of the present invention. Any equivalent embodiments made by those skilled in the art, without departing from the scope of the technical features disclosed in the present invention, using partial modifications or alterations to the technical content disclosed in the present invention, shall still fall within the scope of the technical features of the present invention.

Claims

1. A mud anti-balling structure for use in a slurry shield for high viscosity ground formations, characterized by: It includes the main slurry discharge pipe of the mud and water tank, the quarry box, the clean water tank, the slurry intake pipe of the quarry box, the first pressure pump, the second pressure pump, the central flushing port of the mud and water tank, and the central spray nozzle of the cutter head; The main discharge pipe of the mud and water tank is connected to the quarry box. The quarry box is equipped with a quarry box filter screen barrel inside. The discharge end of the quarry box filter screen barrel is connected to the quarry box slurry intake pipe. The clean water tank is equipped with dilution pipelines and water delivery pipelines; The dilution pipeline is connected to the slurry intake pipe of the quarry box for convergence, and the pipeline section after convergence is connected in sequence to the first pressurization pump and the central flushing port of the mud and water tank. The water supply pipeline is connected in sequence to the second booster pump and the central spray nozzle of the cutter head.

2. The anti-mud balling structure of slurry shield for high viscosity stratum according to claim 1, characterized in that: It is also equipped with a ground mud and water screening station. The main discharge pipe of the mud and water silo is equipped with a first bypass pipe and a second bypass pipe. The first bypass pipe is connected to the quarry box, and the second bypass pipe is connected to the ground mud and water screening station.

3. The anti-mud cake structure for slurry shield tunneling in high-viscosity formations according to claim 2, characterized in that: The first bypass pipeline is equipped with a quarry gate valve; the second bypass pipeline is equipped with a bypass filter and a bypass slurry discharge gate valve.

4. The anti-mud cake structure for slurry shield tunneling in high-viscosity formations according to claim 1, characterized in that: It is also equipped with a ground mud and water screening station. A quarry filter screen is installed on the side wall of the quarry box. The quarry box filter screen is connected to the main slurry discharge pipe of the quarry box, which is connected to the ground mud and water screening station.

5. A slurry shield tunneling anti-mud cake structure for high-viscosity formations according to claim 4, characterized in that: The quarry box is equipped with a quarry box slurry discharge gate valve on the main slurry discharge pipe.

6. The anti-mud cake structure for slurry shield tunneling in high-viscosity formations according to claim 1, characterized in that: The dilution pipeline is equipped with a one-way valve, and the direction of conduction of the one-way valve is limited to flow from the clean water tank to the slurry extraction pipe of the quarry tank.

7. A slurry shield tunneling anti-mud cake structure for high-viscosity formations according to claim 1, characterized in that: A slurry sampling test box is connected to the section of the pipe where the dilution pipeline and the slurry sampling pipe of the quarry converge. A slurry sampling test gate valve is provided between the slurry sampling test box and the pipe section. The slurry sampling test box is used to detect the viscosity and density parameters of the mud in the pipeline in real time.

8. A slurry shield tunneling anti-mud cake structure for high-viscosity formations according to claim 1, characterized in that: It also includes a flow detection device, a linkage control device, and a shield tunneling drive system. The flow detection device is installed on the central water nozzle of the cutterhead. The linkage control device is electrically connected to the flow detection device and the shield tunneling drive system respectively. The linkage control device is configured to collect the flow signal of the central water nozzle of the cutterhead in real time and control the tunneling of the shield by linkage with the shield tunneling drive system according to the flow signal.

9. A slurry shield tunneling anti-mud cake structure for high-viscosity formations according to claim 8, characterized in that: The linkage control device has a built-in flow threshold logic module, which sets the minimum protection flow rate to 250L / min. When the flow rate at the center nozzle of the cutterhead is detected to be <250L / min, the linkage control device outputs a lock signal to lock the shield tunneling drive system, prohibiting the shield from advancing. When the detected flow rate recovers to ≥250L / min, the linkage control device releases the lock on the shield tunneling drive system, allowing the shield to resume tunneling.

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