Water-rich karst stratum earth pressure balance shield tail sealing system protection method and device

Abstract

The invention discloses a water-rich karst stratum earth pressure balance shield tail sealing system protection method, which is characterized in that a metal fender (7) tool is designed below a connecting bridge (4) to form a movable slag collecting pit (8), pumped foreign matters are prevented from flowing to a shield tail along with sewage, and the water-rich karst stratum earth pressure balance shield tail sealing system is protected. The trolley (5) synchronously moves forwards when the track extends, a vacuum slag suction tank (9) is arranged on the trolley (5), sludge in the area of the trolley (5) is sucked into the sludge tank through negative pressure, and then the sludge is conveyed to a belt conveyor (6) from the other end to be conveyed out of a tunnel; a metal and rubber combined fender (7) is designed in a shield tail area to prevent shield tail sludge from entering a shield tail brush, the metal and rubber combined fender (7) is installed on the end face of a duct piece (3) and fixed through a main jacking oil cylinder, cleaning is conducted through a sludge pump and manual work before assembly, after the shield tail area is cleaned up, a retraction oil cylinder is used for synchronously removing the fender (7), and after the duct piece (3) is assembled, reinstallation is conducted to enter the next cycle operation.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology. Specifically, this invention relates to a method for protecting the tail sealing system of a shield tunneling machine in water-rich karst strata with earth pressure balance. Background Technology

[0002] The shield tunneling method involves excavating the strata with a cutterhead at the front and assembling segments at the rear to form the main tunnel body. This method avoids direct exposure of construction workers to the strata and offers higher safety compared to the mining method. Therefore, it is widely used in densely populated urban areas.

[0003] Although the presence of the tunnel boring machine (TBM) avoids direct contact between personnel and the ground, as an excavation device, the TBM still needs to continuously contact groundwater, soil, and injected grout. In order to ensure that the assembled tunnel segments can be smoothly removed from the TBM, the inner diameter of the shield is designed to be slightly larger than the outer diameter of the tunnel segments. This results in a leakage channel around the outer perimeter of the tail tunnel segments. Usually, several rings of tail brushes are set at intervals in the area behind the TBM. A tail sealing system is formed by injecting grease into the cavity between the tail brushes. When the tail sealing system is damaged, groundwater and soil will leak into the tunnel under pressure, seriously affecting the safety of TBM tunnel construction.

[0004] A significant cause of damage to the shield tail sealing system is the entry of hard foreign objects. Excessive local stress on the shield tail brush leads to breakage and detachment. Due to the presence of tunnel segments, a water collection pit forms in the unassembled area of ​​the shield tail segments, making it easy for sewage and foreign objects from inside the tunnel to accumulate in the shield tail area. In water-rich karst strata, the bedrock strength is high, and the hardness distribution at the tunnel face is uneven, easily producing hard slag. Affected by karst, groundwater is highly developed, and violent gushing can easily occur during the tunneling process, causing a large amount of slag to accumulate in the shield tail area with the gushing groundwater. As the shield tunnels, these hard slag can easily intrude into the shield tail sealing system, causing leakage. Compared to general strata, karst areas have a high degree of water abundance and a wide range of hydraulic connections, making it difficult to seal shield tail leakage and seriously affecting the safety of tunnel construction and surrounding buildings.

[0005] A specification published on May 27, 2025, with application number 202422076225.7, discloses a device for cleaning mud and slag from the tail of a tunnel boring machine (TBM). The device includes a scoop-shaped inlet, a connecting shaft at one end, and a pipe joint welded to the side of the other end. A flexible hose is fitted onto the pipe joint, and the hose is connected to a steel pipe fixed to the side of the TBM's auger. An outlet is located at the upper end of the steel pipe, directly above the TBM's belt conveyor. A reducer and motor are installed at the upper end of the outlet. The lower end of a shaftless auger blade is fixed to the connecting shaft inside the inlet, and the upper end of the shaftless auger blade is fixed to the output shaft of the reducer. This invention has a simple structure, does not affect the normal operation of the TBM, and transports the mud and slag to the TBM's belt conveyor through the rotation of the shaftless auger blade. During use, only manual shoveling of the mud and slag to the inlet is required, significantly improving efficiency compared to traditional manual bagging and removal of mud and slag.

[0006] In current technology, when a severe gushing occurs on-site, personnel are generally arranged to use high-pressure water guns to flush the area inside the tunnel. Sewage pumps are used to pump out the water in the shield tail area, and then the water is cleaned up and bagged for transport out using shovels and other tools. However, the working space in the shield tail cleaning area is small, and the gushing in the water-rich karst area is severe, resulting in a huge amount of cleaning work. In order to ensure the progress of tunneling, it is often impossible to clean up in time. The damage frequency of the shield tail sealing system is much higher than that of conventional strata. Therefore, it is necessary to study a sealing system protection method and device for the shield tail sealing area. Summary of the Invention

[0007] This invention aims to provide a method for protecting the tail seal system of a shield tunneling machine in water-rich karst formations with earth pressure balance, which can effectively clean up mud and sludge.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a method for protecting the tail sealing system of a shield tunneling machine in water-rich karst strata with earth pressure balance, comprising the following steps: S1: Install a movable slag collection pit inside the tunnel wall for slag collection, and install mudguards on the tunnel segments to block mud and slag. S2: When installing the tunnel segments, the mudguard is fixed to the end face of the tunnel segment by the main jacking cylinder. Before assembly, the mud at the tail of the shield is cleaned by a mud pump and manual labor. S3: After the tail area is cleaned, the mudguard is removed by retracting the hydraulic cylinder. Then the lower segments are assembled. After the lower area is assembled, the mudguard is reinstalled and tightened with the hydraulic cylinder. S4: The mud pump draws mud and fine particles into the slag collection pit. A small amount of dry slag from Shengyu is manually cleaned and transported to the slag collection pit. S5: Install a vacuum slag suction tank on the trolley, put the suction cup of the slag suction hose into the slag suction pit, open the inlet valve of the slag suction tank, turn on the vacuum pump to suck the slag into the slag tank, and discharge the slag to the belt conveyor through the slag discharge pipe to be transported to the outside of the tunnel. S6: The slag collection pit is moved as a whole by the double beams of the assembly machine during the tunneling interval, according to the progress of the shield tunneling.

[0009] The slag trap is a movable frame structure, and the bottom end of the mudguard is in close contact with the lower surface of the inner wall of the shield tail of the tunnel boring machine.

[0010] A protective device for the tail sealing system of a water-rich karst earth pressure balance shield tunneling machine is disclosed, which is used to realize the protection method of the tail sealing system of the water-rich karst earth pressure balance shield tunneling machine. The device includes a shield machine, a tunnel wall with pre-attached segments, segments located at the tail of the shield, a connecting bridge connected to the shield machine, and a trolley. The tail of the shield machine is provided with a blocking structure to prevent sludge from entering between the tail of the shield and the segments. The tunnel wall is provided with a sludge collection pit for storing sludge.

[0011] The blocking structure is located at the tail of the tunnel boring machine. The blocking structure is a mudguard that is closely attached to the tunnel lining segments, and the bottom end of the mudguard is attached to the surface of the tail of the tunnel boring machine.

[0012] The mudguard is fixed to the end of the tunnel segment by the main top cylinder of the tunnel boring machine, and the mudguard is removed from the end of the tunnel segment by the retraction cylinder of the tunnel boring machine.

[0013] The mudguard consists of a steel plate and a rubber plate fixed together by rivets. The rubber plate is located on the side closer to the tunnel segment. The length of the rubber plate is greater than the length of the steel plate. The bottom end of the rubber plate drags on the inner surface of the shield tail of the tunnel boring machine. The bottom end of the steel plate does not contact the shield tail surface of the tunnel boring machine.

[0014] The slag collection pit is a frame-plate structure set at the bottom of the tunnel wall. The slag collection pit stores mud and slag. The trolley is equipped with a vacuum slag suction tank. The vacuum slag suction tank is equipped with a suction hose with its end located in the slag collection pit. The vacuum slag suction tank is equipped with a slag discharge pipe with its end located above the belt conveyor inside the trolley.

[0015] The cross-section of the slag collection pit is arc-shaped, and the lower surface of the slag collection pit is attached to the surface of the tunnel wall. The slag collection pit is a spliced ​​structure, and the slag collection pit is moved by the double beams of the shield machine's assembly machine.

[0016] The slag collection pit is divided into a bottom plate, a baffle plate, and splicing plates. The baffle plate is placed on the bottom plate, and the splicing plates are placed on both sides of the baffle plate. The splicing plates of adjacent baffle plates are tightly attached together and are fixed together by bolts.

[0017] A support plate is provided between the base plate and the baffle. The baffle is located at the front and rear ends of the base plate. The cross-section of the base plate is arc-shaped. The base plate is spliced ​​together along the surface of the tunnel wall. Adjacent baffles are tightly attached to each other. The upper surfaces of the baffles are located on the same horizontal plane.

[0018] The technical advantages of this invention are as follows: Utilizing this earth pressure balance shield tail sealing system protection method in water-rich karst strata, a dual-layer protection system can be formed. Compared to conventional shield tunnels without protection measures, this significantly extends the lifespan of the tail brush, resulting in higher construction safety. Furthermore, the first layer of equipment blocks the main mud and foreign objects generated during tunnel operations, allowing workers to clean the mud under the connecting bridge. This provides a larger working space and higher efficiency, reducing the amount of mud entering the tail area, decreasing the tail cleaning workload, and shortening the preparation time required before assembling tunnel segments. This improves construction efficiency, ensures continuous tunneling, and, when the tail sealing system is damaged and the tail is severely affected, it can be used for tail sealing, extending the leakage channel and allowing time for the sealing material to solidify, effectively improving tail safety. It also makes full use of the waste steel wire rubber generated from on-site conveyor belt maintenance, resulting in good economic efficiency. Attached Figure Description

[0019] This manual includes the following figures, which illustrate the following: Figure 1 This is a schematic diagram of the protective device for the shield tail sealing system of a water-rich karst stratum earth pressure balance shield tunneling machine according to the present invention. Figure 2 for Figure 1 A schematic diagram of the mudguard plate of the protective device for the tail sealing system of a water-rich karst shield tunneling machine. Figure 3 for Figure 1 A schematic diagram of the slag collection pit for a protective device of the earth pressure balance shield tail sealing system in a water-rich karst strata shield tunneling machine. Figure 4 for Figure 1 A schematic diagram of the slag collection pit splicing unit of the earth pressure balance shield tunnel tail sealing system protection device in a water-rich karst stratum.

[0020] The following are marked in the diagram: 1. Tunnel boring machine; 2. Tunnel wall; 3. Segment; 4. Connecting bridge; 5. Trolley; 6. Belt conveyor; 7. Mudguard; 71. Steel plate; 72. Rubber plate; 8. Slag collection pit; 81. Baffle; 82. Bottom plate; 83. Splicing plate; 84. Support plate; 9. Vacuum slag suction tank; 10. Slag suction hose; 11. Slag discharge pipe. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention, and to facilitate its implementation.

[0022] A method for protecting the tail sealing system of a shield tunneling machine in water-rich karst strata using earth pressure balance, comprising the following steps: S1: Install a movable slag collection pit 8 inside the tunnel wall 2 for slag collection, and install a mudguard 7 on the tunnel segment 3 to block mud and slag. S2: When installing segment 3, the mudguard 7 is fixed to the end face of segment 3 by the main top hydraulic cylinder. Before assembly, the mud at the tail of the shield is cleaned by a mud pump and manual labor. S3: After the tail area is cleaned, the mudguard 7 is removed by retracting the hydraulic cylinder. Then the lower segment 3 is assembled. After the lower area is assembled, the mudguard 7 is reinstalled and tightened with the hydraulic cylinder. S4: The mud pump draws mud and fine particles into the slag collection pit 8. A small amount of dry slag from Shengyu is manually cleaned and transported into the slag collection pit 8. S5: Install the vacuum suction tank 9 on the trolley 5, put the suction cup of the suction hose 10 into the suction pit, open the inlet valve of the suction tank, turn on the vacuum pump to suck the mud into the mud tank, and discharge the mud to the belt conveyor 6 through the discharge pipe 11 to be transported to the outside of the tunnel. S6: The slag collection pit 8 is moved as a whole by the double beams of the assembly machine during the tunneling interval, according to the progress of the shield tunneling.

[0023] The slag trap is a movable frame structure, with the bottom end of the mudguard 7 tightly attached to the lower surface of the inner wall of the shield tail of the tunnel boring machine 1. The movable slag collection pit 8 can move with the tunnel boring machine 1 to collect the cleaned slag. Since it can move with the tunnel boring machine 1, the distance of transporting slag back and forth can be reduced, improving the cleaning efficiency. At the same time, the bottom end of the mudguard 7 is tightly attached to the surface of the shield tail of the tunnel boring machine 1, which can effectively prevent slag from entering between the shield tail and the segment 3, prevent slag from contaminating the tail brush, effectively extend the life of the tail brush, and improve construction safety.

[0024] Please see Figure 1-4A protective device for the tail sealing system of a water-rich karst earth pressure balance shield tunneling machine, used to achieve protection of the tail sealing system in this water-rich karst strata, includes a shield machine 1, a tunnel wall 2 with pre-attached segments 3, segments 3 located at the tail, a connecting bridge 4 connected to the shield machine 1, and a trolley 5. The tail section of the shield machine 1 is equipped with a blocking structure to prevent sludge from entering between the tail and the segments 3. A sludge collection pit 8 is provided inside the tunnel wall 2 for storing sludge. This forms a double-layer protection, significantly extending the life of the tail shield compared to conventional shield tunneling without protection measures, resulting in higher construction safety, and mainly protecting the sludge... The slag and foreign objects generated during tunnel operations are blocked by the first piece of equipment, namely the mudguard 7. Workers can clean up the slag under the connecting bridge 4, which provides a larger working space and higher efficiency. This results in less slag entering the shield tail area, reduces the workload of shield tail cleaning, and reduces the preparation time required before assembling the tunnel segments 3. This can improve construction efficiency, ensure continuous tunneling, and when the shield tail sealing system is damaged and the shield tail is severely damaged, it can be used to seal the shield tail, extend the leakage channel, and buy time for the sealing material to solidify. This can effectively improve the safety of the shield tail and make full use of the waste steel wire rubber generated from the maintenance of the on-site belt conveyor 6, which is economical.

[0025] The blocking structure is located at the tail of the tunnel boring machine 1. The blocking structure is a mudguard 7 that is closely attached to the segment 3. The bottom end of the mudguard 7 is attached to the surface of the tail of the tunnel boring machine 1. The mudguard 7 is fixed to the end of the segment 3. The mudguard 7 is used to block the mud and prevent it from entering between the tail and the segment 3, preventing the mud and mud from contaminating the tail brush, effectively extending the life of the tail brush, and making construction safer.

[0026] The mudguard 7 is fixed to the end of the tunnel segment 3 by the main top hydraulic cylinder of the tunnel boring machine 1, and the mudguard 7 is removed from the end of the tunnel segment 3 by the retraction hydraulic cylinder of the tunnel boring machine 1. The installation and removal of the mudguard 7 are realized by using the assembly machine equipment for installing the tunnel segment 3, which simplifies the equipment required for installation and reduces the material cost.

[0027] The mudguard 7 consists of a steel plate 71 and a rubber plate 72, which are fixed together by rivets. The rubber plate 72 is located on the side closer to the tunnel segment 3. The length of the rubber plate 72 is greater than that of the steel plate 71. The bottom end of the rubber plate 72 drags on the inner surface of the shield tail of the tunnel boring machine 1, while the bottom end of the steel plate 71 does not contact the shield tail surface of the tunnel boring machine 1. Utilizing the elasticity of the rubber, the end of the rubber plate 72 can effectively fit against the surface of the shield tail, thereby achieving a sealing effect. Furthermore, the steel wire rubber produced during the maintenance of the on-site conveyor belt 6 can be processed, which is economical. The steel plate 71 is used to block the hard parts in the mud and prevent hard debris from impacting and damaging the rubber plate 72, thus protecting the rubber plate 72.

[0028] The slag collection pit 8 is a frame-plate structure set at the bottom of the tunnel wall 2. The slag collection pit 8 stores slag. The trolley 5 is equipped with a vacuum slag suction tank 9. The vacuum slag suction tank 9 is equipped with a suction hose 10 with its end located inside the slag collection pit 8. The vacuum slag suction tank 9 is equipped with a discharge pipe 11 with its end located above the belt conveyor 6 inside the trolley 5. The vacuum slag suction tank 9 is installed on the trolley 5. During cleaning, the suction cup of the suction hose 10 is placed into the slag collection pit 8 formed by the slag collection pit 8. The slag inlet valve of the suction tank is opened, and the vacuum pump is turned on to suck the slag into the slag tank. The slag is discharged through the discharge pipe 11 onto the belt conveyor 6 and transported to the outside of the tunnel. The belt conveyor 6 of the shield machine 1 is used to transport the waste material out of the tunnel, preventing the slag from accumulating in the tunnel and affecting the normal walking and work of the construction personnel, improving construction efficiency, and ensuring continuous tunneling.

[0029] The cross-section of the slag collection pit 8 is arc-shaped, and the lower surface of the slag collection pit 8 is attached to the surface of the tunnel wall 2. The slag collection pit 8 is a spliced ​​structure, and it is moved by the double beam of the assembly machine of the shield machine 1. The bottom end of the slag collection pit 8 can be similar to the surface structure shape of the tunnel wall 2. While minimizing the height of the slag collection pit 8, the storage capacity of the slag collection pit 8 is increased. The spliced ​​slag collection pit 8 is convenient for installation and transportation, making it easy for construction personnel to transport it into the tunnel. It is also convenient for construction personnel to manually install it in the narrow tunnel, eliminating the need to transport additional machinery into the tunnel for installation, thus simplifying construction and facilitating installation. At the same time, the slag collection pit 8 is moved by the double beam of the assembly machine of the shield machine 1, keeping the distance between the slag collection pit 8 and the shield tail at a short distance, reducing the distance required to transport slag.

[0030] The slag collection pit 8 is divided into a bottom plate 82, a baffle 81, and a splicing plate 83. The baffle 81 is set on the bottom plate 82, and the splicing plate 83 is set on both sides of the baffle 81. The splicing plates 83 of adjacent baffles 81 are tightly attached together, and adjacent splicing plates 83 are fixed together by bolts. The use of multiple plates spliced ​​together facilitates construction and transportation. The bolts are easy and quick to install and can ensure a certain strength.

[0031] A support plate 84 is provided between the base plate 82 and the baffle 81. The baffle 81 is located at the front and rear ends of the base plate 82. The cross-section of the base plate 82 is arc-shaped. The base plate 82 is spliced ​​together along the surface of the tunnel wall 2. Adjacent baffles 81 are tightly attached to each other, and the upper surfaces of the baffles 81 are on the same horizontal plane. The base plate 82 can be tightly attached to the surface of the tunnel wall 2, and the support plate 84 can provide effective support to prevent the baffles 81 from breaking under the pressure of sludge.

[0032] Working principle: A metal mudguard 7 is designed under the connecting bridge 4 to form a movable slag collection pit 8, preventing extracted foreign objects from flowing to the shield tail with sewage. The trolley 5 moves forward synchronously when the track extends. A vacuum slag suction tank 9 is set on the trolley 5. The slag in the area of ​​the trolley 5 is sucked into the slag tank by negative pressure, and then transported from the other end to the conveyor belt 6 to be transported out of the tunnel. A metal + rubber combination mudguard 7 is designed in the shield tail area to prevent the shield tail slag from entering the shield tail brush. It is installed on the end face of the segment 3 and fixed by the main top hydraulic cylinder. Before assembly, the slag pump and manual cleaning are used. After the shield tail area is cleaned, the mudguard 7 is removed synchronously by the retraction hydraulic cylinder. After the segment 3 is assembled, it is reinstalled to enter the next cycle of operation.

[0033] The technical advantages of this invention are as follows: Utilizing the earth pressure balance shield tail sealing system protection method in water-rich karst strata, a dual-layer protection system can be formed. Compared to conventional shields without protection measures, this significantly extends the lifespan of the tail brush, resulting in higher construction safety. Furthermore, the first layer of equipment blocks the main mud and foreign objects generated during tunnel operations, allowing workers to clean mud under the connecting bridge 4. This provides a larger working space and higher efficiency, reducing the amount of mud entering the tail area and decreasing the workload of tail cleaning. It also reduces the preparation time required before assembling the tunnel segments 3, improving construction efficiency and ensuring continuous tunneling. Moreover, when the tail sealing system is damaged and the tail is severely affected, it can be used for tail sealing, extending the leakage channel and allowing time for the sealing material to solidify, effectively improving tail safety. It also makes full use of the waste steel wire rubber generated during the maintenance of the on-site conveyor belt 6, resulting in good economic efficiency.

[0034] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A method for protecting a water-rich karst stratum earth pressure balance shield tail seal system, characterized in that, The steps are as follows: S1: install the movable slag collecting pit (8) for slag collection in the tunnel wall (2), and install the mud baffle (7) for blocking mud on the segment (3); S2: when installing the segment (3), the mud baffle (7) is fixed on the end face of the segment (3) by the main jacking oil cylinder, and the mud baffle (7) is removed from the end face of the segment (3) by the retraction oil cylinder after the shield tail area is cleaned; S3: after the shield tail area is cleaned, the mud baffle (7) is removed by the retraction oil cylinder, and then the lower segment (3) is assembled, and the mud baffle (7) is reinstalled and tightly jacked by the oil cylinder after the lower area is assembled; S4: the mud pump pumps the mud and fine particles into the slag collecting pit (8), and a small amount of dry slag is transported into the slag collecting pit (8) by manual cleaning; S5: install the vacuum slag suction tank (9) on the trolley (5), put the suction disc of the slag suction hose (10) into the slag suction pit, open the inlet valve of the slag suction tank, start the vacuum pump to pump the mud into the mud tank, and then discharge the mud through the discharge pipe (11) to the belt conveyor (6) for transportation outside the tunnel; S6: the slag collecting pit (8) is moved as a whole by the double beam of the assembling machine according to the progress of shield tunneling.

2. The method of claim 1, wherein the method further comprises: The slag collecting pit is a movable frame structure, and the bottom end of the mud baffle (7) is tightly attached to the inner wall of the shield tail of the shield tunneling machine (1).

3. A protection device for a water-rich karst stratum earth pressure balance shield tail sealing system, used to implement the water-rich karst stratum earth pressure balance shield tail sealing system protection method of any one of claims 1-2, comprising a shield machine (1), a tunnel wall (2) to which segments (3) have been attached, a segment (3) located at a tail of the shield machine (1), a connecting bridge (4) connected to the shield machine (1), and a trolley (5), characterized in that: The shield tail part of the shield tunneling machine (1) is provided with a blocking structure for blocking the mud from entering between the shield tail and the segment (3), and the tunnel wall (2) is provided with a slag collecting pit (8) for storing mud.

4. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 3, characterized in that: The blocking structure is located at the shield tail of the shield tunneling machine (1), and the blocking structure is a mud baffle (7) tightly attached to the segment (3), and the bottom end of the mud baffle (7) is attached to the surface of the shield tail of the shield tunneling machine (1).

5. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 4, characterized in that: The mud baffle (7) is fixed on the end of the segment (3) by the main jacking oil cylinder of the shield tunneling machine (1), and the mud baffle (7) is removed from the end of the segment (3) by the retraction oil cylinder of the shield tunneling machine (1).

6. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 4 or 5, characterized in that: The mud baffle (7) is divided into a steel plate (71) and a rubber plate (72) fixed together by rivets, the rubber plate (72) is located on the side close to the segment (3), the length of the rubber plate (72) is greater than the length of the steel plate (71), the bottom end of the rubber plate (72) is dragged on the inner surface of the shield tail of the shield tunneling machine (1), and the bottom end of the steel plate (71) does not contact the surface of the shield tail of the shield tunneling machine (1).

7. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 3, characterized in that: The slag collecting pit (8) is a frame plate structure arranged at the bottom end of the tunnel wall (2), the slag collecting pit (8) stores mud, the trolley (5) is provided with a vacuum slag suction tank (9), the vacuum slag suction tank (9) is provided with a slag suction hose (10) with an end located in the slag collecting pit (8), and the vacuum slag suction tank (9) is provided with a discharge pipe (11) with an end located above the belt conveyor (6) in the trolley (5).

8. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 7, characterized in that: The cross section of the slag collecting pit (8) is arc-shaped, the lower surface of the slag collecting pit (8) is attached to the surface of the tunnel wall (2), the slag collecting pit (8) is a spliced structure, and the slag collecting pit (8) is moved by the double beam of the assembling machine of the shield tunneling machine (1).

9. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 8, characterized in that: The slag collecting pit (8) is divided into a bottom plate (82), a baffle (81) and a splicing plate (83), the baffle (81) is arranged on the bottom plate (82), the splicing plate (83) is arranged on both sides of the baffle (81), the splicing plates (83) of adjacent baffles (81) are tightly attached together, and the adjacent splicing plates (83) are fixed together through bolts.

10. The water-rich karst stratum earth pressure balance shield tail seal system protection device according to claim 9, characterized in that: Support plates (84) are arranged between the bottom plate (82) and the baffle (81), the baffle (81) is arranged at the front end and the rear end of the bottom plate (82), the cross section of the bottom plate (82) is arc-shaped, the bottom plate (82) is spliced together along the surface of the tunnel wall (2), the adjacent baffles (81) are tightly attached to each other, and the upper surfaces of the baffles (81) are located on the same horizontal plane.

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