A shield machine slag discharge system with variable grouting density

Abstract

The present application provides a shield machine slag discharge system with variable grouting density. Through two categories of four working modes and four circulation modes, the shield system can adapt to various strata more finely, ensuring the safe operation of the shield machine during the excavation process.

Description

Technical Field

[0001] The present application relates to the technical field of shield machine excavation, and in particular to a shield machine slag discharge system with variable grouting density. Background Art

[0002] The shield machine's mucking system is used to discharge the excavated soil generated during excavation to maintain pressure balance on the excavation surface. Traditional shield machine mucking systems have two modes: earth pressure balance and slurry balance. The earth pressure balance mode relies on a screw conveyor to discharge the soil, balancing the ground pressure through the "soil plug" formed by the soil. The earth pressure balance mode is suitable for clay formations, but is not suitable for sandy soils and gravel formations because it may cause eruptions. The slurry balance mode uses mud to entrain the soil to balance the water and soil pressure in the formation. The slurry balance mode is suitable for permeable formations, but is less efficient and more expensive in clay formations. However, the slurry balance mode cannot meet the high support requirements of large-grained formations such as pebble formations.

[0003] As excavation scenarios continue to increase, shield machine modes should be improved towards precision and efficiency. The slag removal system should not only consider applicability, but also flexibly adjust the operating mode according to the project characteristics to improve slag removal efficiency. The slag removal system's mode switching is achieved by opening and closing valves. The valve switching process requires monitoring pipeline flow and pressure fluctuations. More modes means more complex pipelines and more frequent interactions between pipelines. This also means that the flow and pressure of each channel need to be more coordinated, otherwise it is easy to cause stagnation and mud cake formation. Summary of the Invention

[0004] The present application provides a shield machine slag discharge system with variable grouting density and an abnormal condition processing method, which solves the problem that the slag discharge mode of the traditional shield machine slag discharge system is insufficiently matched with the stratum.

[0005] The technical solution of this application is as follows:

[0006] A shield machine slag discharge system with variable grouting density includes a spiral crusher, a grouting pipe network, and a bentonite pipe. The spiral crusher includes, from the excavation end to the slag discharge end, a front spiral that is connected to the excavation chamber and passes through an air cushion chamber, a hatch, a rear spiral, a crushed stone box, and a mud conditioning box. The crushed stone box is also equipped with a crusher and a grille. A belt conveyor is provided under the hatch.

[0007] The grouting pipe network starts from the mud pool, and after the grouting pipe is divided into the first branch, it is further divided into the first and second sub-branches and respectively lead to the excavation chamber, and after it is divided into the second branch, it is further divided into the third and fourth sub-branches and respectively lead to the air cushion chamber and the excavation chamber, and after it is divided into the third branch, it is further divided into the fifth and sixth sub-branches and respectively lead to the rear spiral and the gravel box, and after it is divided into the fourth branch, it is connected to the return slurry pipe;

[0008] The return slurry pipeline starts from the air cushion bin, passes through the gravel box, connects to the fourth branch, and then connects to the mud-water separation station;

[0009] The bentonite pipeline includes a bentonite tank and a slurry inlet pipeline leading to the excavation chamber;

[0010] The grouting pipeline and the return slurry pipeline are respectively provided with a slurry feed pump located at the outlet of the mud pool and a slurry discharge pump located at the entrance of the mud-water separation station; the slurry feed pump is provided with a first valve at the rear of the pipeline flow direction, and the slurry discharge pump is provided with a second valve at the front of the pipeline flow direction; the fourth branch is provided with a third valve, and the slurry feed pipeline includes a fourth valve; the first sub-branch is provided with a fifth valve, the second sub-branch is provided with a third pump body and a sixth valve is provided at the rear of the third pump body along the pipeline flow direction; the second branch is provided with a fourth pump body before the differentiation point, and the third and fourth sub-branches are provided with a seventh valve and an eighth valve respectively; the fifth sub-branch is provided with a ninth valve, and the sixth sub-branch is provided with a tenth valve;

[0011] The return slurry pipeline is provided with an eleventh valve, a fifth pump body and a twelfth valve in sequence in front of the gravel box according to the flow direction of the pipeline; the return slurry pipeline leads out a circulation branch between the fifth pump body and the twelfth valve to the front of the seventh valve of the third auxiliary branch.

[0012] Furthermore, the first auxiliary branch flows into the upper part of the excavation chamber, and the second auxiliary branch slurry flushes the center of the excavation chamber.

[0013] Furthermore, the fourth auxiliary branch passes into the excavation chamber through the air cushion chamber.

[0014] Furthermore, the mud pool includes a low-density mud pool and a high-density mud pool. The mud density of the low-density mud pool ranges from 1.05t / m³ to 1.20t / m³, and the mud density of the high-density mud pool ranges from 1.21t / m³ to 1.50t / m³.

[0015] Furthermore, the slag discharge system includes a conventional earth pressure balance mode and a mud-water balance mode, wherein the mud-water balance mode further includes a mud-added earth pressure balance mode, a low-density mud-water balance mode and a high-density mud-water balance mode;

[0016] The conventional earth pressure balance mode is implemented by closing all valves and opening only the front screw, hatch and belt conveyor;

[0017] The method for implementing the mud-adding earth pressure balance mode is as follows: opening the fourth valve, the front screw, the hatch and the belt conveyor;

[0018] The method for implementing the low-density mud balance mode is as follows: closing the fourth valve and the hatch, opening other valves and pumps according to the specific circulation mode, and opening the front spiral, rear spiral, and rock crusher;

[0019] The high-density mud balance mode is achieved by closing the fourth valve and the hatch, opening other valves and pumps according to the specific circulation mode, and opening the front spiral, rear spiral, crusher, and mud regulating box.

[0020] In the mud balance mode, compressed air is filled into the air cushion chamber to balance the pressure on the tunnel face through the atmospheric pressure and mud pressure.

[0021] Furthermore, each sub-mode of the slurry balance mode can realize four circulation modes of the grouting pipe network, including the standard bypass mode, the gravel box bypass mode, the excavation circulation mode, and the working chamber circulation mode; the circulation mode defaults to turning on the slurry pump and the slurry pump;

[0022] The standard bypass is achieved by opening the first valve, the second valve, and the third valve;

[0023] The method for implementing the gravel box bypass mode is as follows: opening the first valve, the second valve, the tenth valve, and the gravel box, the gravel crusher, and the grille;

[0024] The excavation circulation mode is implemented by starting the third pump body and the fourth pump body, opening the first valve, the second valve, the sixth valve, the seventh valve, and the tenth valve, and starting the front spiral, the rear spiral, and the stone crusher after the mud enters the excavation chamber;

[0025] The working cabin circulation mode includes an air cushion chamber internal circulation mode and an air cushion chamber external circulation mode. The working cabin circulation mode is turned on by default in the fifth pump body;

[0026] The method for implementing the circulation mode in the air cushion chamber is as follows: opening the eleventh valve, the twelfth valve, and the seventh valve;

[0027] The method for realizing the external circulation mode of the air cushion chamber is: opening the first valve, the seventh valve, the eleventh valve, and the thirteenth valve.

[0028] Furthermore, the slurry discharge pipeline, grouting pipeline, first sub-branch, second sub-branch, second branch and third branch are provided with flow meters, and the slurry discharge pipeline and grouting pipeline are also provided with density meters at the flow meter setting positions, and the slurry discharge pipeline is provided with a pressure gauge between the mud regulating box and the gravel box.

[0029] Furthermore, the mud-water separation station is provided with a mud pipeline connected to the mud pool.

[0030] Due to the adoption of the above technical solution, the beneficial effects of this application are as follows:

[0031] 1. This application refines the operating modes of the shield machine's mucking system. Building on the conventional earth pressure balance (EPB) and slurry balance (S&B) operating modes, the S&B system expands to include a mud-added EPB mode, a low-density S&B mode, and a high-density S&B mode to accommodate more complex and variable tunneling environments and avoid the manpower and material losses associated with frequent equipment replacements. This application utilizes a multi-branch design, allowing the flow and pressure of each pipeline to be independently controlled via valves, reducing cross-pipeline interference. Combined with monitoring by flowmeters, density meters, and pressure gauges, slurry parameters in each branch can be adjusted in real time to ensure flow and pressure coordination under different modes, avoiding problems such as stagnant drainage and mud cake formation. The multi-branch and multi-sub-branch design embodied in this application is the core of achieving "variable density" and "refined modes." By precisely controlling the slurry injection location, flow rate, and path, the shield machine can safely and efficiently navigate complex and changing geological environments.

[0032] 2. This application meticulously implements multiple branch circuits for the slag discharge system. Some of these branches are further branched, allowing for comprehensive flushing of the top and bottom layers in conjunction with the branch that feeds the air cushion chamber. This application incorporates a spiral crusher as part of the overall pipeline, with one branch feeding into the crushed stone tank. Furthermore, this application derives four circulation patterns under slurry balance.

[0033] 3. This application implements four circulation modes in the slurry balance mode through valve control within the grouting network. These modes ensure the normal operation of the mucking system and improve tunneling efficiency. This application implements four circulation modes through various branches, each with the following benefits: Standard Bypass Mode: Controlled by the first, second, and third valves, rapid mud bypass is achieved, suitable for pipeline cleaning or temporary pressure regulation. Gravel Box Bypass Mode: Opening the tenth valve, combined with the crusher and screen, allows for processing large-sized debris and prevents clogging of the main pipeline with gravel. Excavation Circulation Mode: Interconnecting the third and fourth pumps and multiple valves ensures stable circulation of mud between the excavation chamber, air cushion chamber, and gravel box, maintaining pressure balance at the tunnel face. Working Chamber Circulation Mode (Internal / External): Circulation branches allow for independent circulation of mud within the air cushion chamber or interconnection with the main pipeline, facilitating fine-tuning of pressure or localized cleaning. The four circulation modes can be quickly switched by opening and closing valves and components, adapting to complex strata. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0035] Figure 1Schematic diagram of the structure of the spiral crusher, grouting pipe network and bentonite pipeline provided for this application.

[0036] In the attached figure:

[0037] 1. Excavation chamber; 2. Air cushion chamber; 3. Screw crusher; 301. Front screw; 302. Rear screw; 303. Crushing box; 304. Crusher; 305. Grille; 306. Hatch door; 4. Conveyor belt; 5. Mud regulating box; 6. Slurry inlet pipeline; 7. Bentonite pool; P1. Slurry inlet pump; P2. Slurry discharge pump; P3. Third pump body; P4. Fourth pump body; P5. Fifth pump body; V1. First valve; V2. Second valve; V3. Third valve; V4. Fourth valve; V5. Fifth valve; V6. Sixth valve; V7. Seventh valve; V8. Eighth valve; V9. Ninth valve; V10. Tenth valve; V11. Eleventh valve; V12. Twelfth valve; V13. Thirteenth valve. DETAILED DESCRIPTION

[0038] Based on the background technology, as shown in the attached Figure 1 As shown, the present application provides a shield machine slag discharge system with variable grouting density, including a spiral crusher 3, a grouting pipe network, and a bentonite pipe; the spiral crusher 3 includes a front spiral 301 connected to the excavation chamber 1 and passing through the air cushion chamber 2, a hatch 306, a rear spiral 302, a crushed stone box 303, and a mud regulating box 5 from the excavation end to the slag discharge end, the crushed stone box 303 is also provided with a crusher 304 and a grille 305, and a hatch 306 is provided below the crushed stone box 303. A belt conveyor 4 is provided, and the grouting network starts from the mud pool, and after the grouting pipeline is divided into the first branch, it is further divided into the first sub-branch and the second sub-branch and respectively enters the excavation chamber 1, and after it is divided into the second branch, it is further divided into the third sub-branch and the fourth sub-branch and respectively enters the air cushion chamber 2 and the excavation chamber 1, and after it is divided into the third branch, it is further divided into the fifth sub-branch and the sixth sub-branch and respectively enters the rear spiral 302 and the gravel box 303, and is connected to the return slurry pipeline after it is divided into the fourth branch.

[0039] The return slurry pipeline starts from the air cushion chamber 2, passes through the gravel box 303, connects to the fourth branch, and then connects to the mud-water separation station;

[0040] The bentonite pipeline includes a bentonite tank 7 and a slurry inlet pipeline 6 leading to the excavation chamber 1;

[0041] The grouting pipeline and the return slurry pipeline are respectively provided with a slurry feed pump P1 located at the outlet of the mud pool and a slurry discharge pump P2 located at the entrance of the mud-water separation station. The slurry feed pump P1 is provided with a first valve V1 at the rear of the pipeline flow direction, and the slurry discharge pump P2 is provided with a second valve V2 at the front of the pipeline flow direction; the fourth branch is provided with a third valve V3, and the slurry feed pipeline 6 includes a fourth valve V4; the first sub-branch is provided with a fifth valve V5, the second sub-branch is provided with a third pump body P3 and a sixth valve V6 is provided behind the third pump body P3 along the pipeline flow direction; the second branch is provided with a fourth pump body P4 before the differentiation point, and the third and fourth sub-branches are provided with a seventh valve V7 and an eighth valve V8 respectively; the fifth sub-branch is provided with a ninth valve V9, and the sixth sub-branch is provided with a tenth valve V10;

[0042] The return slurry pipeline is provided with an eleventh valve V11, a fifth pump body P5 and a twelfth valve V12 in sequence in front of the gravel box 303 according to the flow direction of the pipeline; the return slurry pipeline leads to a circulation branch between the fifth pump body P5 and the twelfth valve V12 to the front of the seventh valve V7 of the third auxiliary branch.

[0043] In this embodiment, the four differentiation points are the fourth branch, the third branch, the second branch, and the first branch in the order of flow through the grouting pipeline. It should be noted that the four differentiation points have no order, that is, each branch is an independent branch and is not affected by other branches.

[0044] In this embodiment, the first auxiliary branch of slurry is introduced into the upper portion of the excavation chamber 1 for slurry feeding. The second auxiliary branch of slurry flushes the center of the excavation chamber 1. Since the cutterhead's centerline speed is relatively low, mud cakes are easily formed, so timely flushing is required. The fourth auxiliary branch of slurry is introduced into the excavation chamber 1 through the air cushion chamber 2.

[0045] In this embodiment, the mud pool includes a low-density mud pool and a high-density mud pool. The mud density of the low-density mud pool ranges from 1.05t / m³ to 1.20t / m³, and the mud density of the high-density mud pool ranges from 1.21t / m³ to 1.50t / m³. In clay and silt layers, the soil itself has a certain cohesion, which is easy to form an earth pressure balance state and switch to the conventional earth pressure balance working state; in sandy soil, gravel layer or composite layer of upper clay and lower sand layer, due to loose particles and low cohesion, it is easy to cause gushing or pressure fluctuations, so it switches to the mud-added earth pressure balance working state. On the basis of conventional earth pressure balance, bentonite slurry is injected into the soil compartment to improve the flow plasticity, water-stopping and impermeability of the slag. The improved slag forms a uniform "plastic fluid", which effectively transmits earth pressure, prevents gushing and improves the stability of the excavation face; in medium-coarse sand and gravel sand layers, due to the large particle size, the soil self-stability is poor, and mud penetration is required to form a mud film, relying on mud pressure to balance the water and soil pressure, and switch to the low-density mud-water balance working state; in pebble layer and boulder layer, the particle size is greater than 20 If the proportion of particles larger than 0.5 mm exceeds 50%, or there are isolated boulders or bedrock protrusions, switch to high-density mud-water balance working mode and use high-density mud (density 1.2-1.5 g / cm³, with added barite, clay, etc.). Through high-pressure and high-concentration mud, a thick mud film is formed on the excavation surface to enhance impermeability and support.

[0046] Based on the above structure, the slag discharge system can achieve four operating modes, including one earth pressure balance mode and three slurry balance modes. Depending on the stratum, the slag discharge system includes a conventional earth pressure balance mode and a slurry balance mode. The slurry balance mode also includes a mud-added earth pressure balance mode, a low-density slurry balance mode, and a high-density slurry balance mode.

[0047] In clay and silt layers, the soil itself has a certain cohesion, which is easy to form an earth pressure balance state, and switch to the conventional earth pressure balance working state; in sandy soil, gravel layer or composite layer of upper clay and lower sand layer, due to loose particles and low cohesion, it is easy to cause gushing or pressure fluctuation, so it switches to the mud-added earth pressure balance working state; on the basis of conventional earth pressure balance, bentonite slurry is injected into the excavation chamber 1 to improve the flow plasticity, water-stopping and impermeability of the slag, and the improved slag forms a uniform "plastic fluid", which effectively transmits earth pressure, prevents gushing and improves the stability of the excavation surface; in medium-coarse sand and gravel sand layers, due to the large particle size, the soil self-stability is poor, and mud penetration is required to form a mud film, relying on the mud pressure to balance the water and soil pressure, and switch to the low-density mud-water balance working state; in the pebble layer and boulder layer, the particle size is greater than 20 If the proportion of particles larger than 0.5 mm exceeds 50%, or there are isolated boulders or bedrock protrusions, switch to high-density mud-water balance working mode and use high-density mud (density 1.2-1.5 g / cm³, with added barite, clay, etc.). Through high-pressure and high-concentration mud, a thick mud film is formed on the excavation surface to enhance impermeability and support.

[0048] The conventional earth pressure balance mode is achieved by closing all valves and only opening the front spiral 301, the hatch 306 and the belt conveyor 4.

[0049] The method for implementing the mud-adding earth pressure balance mode is: opening the fourth valve V4, the front screw 301, the hatch 306 and the belt conveyor 4.

[0050] The method for implementing the low-density mud balance mode is as follows: closing the fourth valve V4 and the hatch 306, opening other valves and pumps according to the specific circulation mode, and opening the front spiral 301, the rear spiral 302, and the rock crusher 304;

[0051] The high-density mud balance mode is achieved by closing the fourth valve V4 and the hatch 306, opening other valves and pumps according to the specific circulation mode, and opening the front spiral 301, the rear spiral 302, the crusher 304, and the mud regulating box 5.

[0052] In the mud-water balance mode, compressed air is filled into the air cushion chamber 2 to balance the pressure received by the tunnel face through the atmospheric pressure and the mud pressure.

[0053] Each sub-mode of the slurry balance mode can realize four circulation modes of the grouting pipe network, including the standard bypass mode, the gravel box 303 bypass mode, the excavation circulation mode and the working chamber circulation mode; the circulation mode defaults to turning on the slurry pump P1 and the slurry pump P2;

[0054] The standard bypass is achieved by opening the first valve V1, the second valve V2, and the third valve V3;

[0055] The bypass mode of the gravel box 303 is achieved by opening the first valve V1, the second valve V2, the tenth valve V10, and the gravel box 303, the stone crusher 304, and the grille 305;

[0056] The excavation circulation mode is implemented by starting the third pump body P3 and the fourth pump body P4, opening the first valve V1, the second valve V2, the sixth valve V6, the seventh valve V7, and the tenth valve V10, and starting the front spiral 301, the rear spiral 302, and the stone crusher 304 after the mud enters the excavation chamber 1;

[0057] The working chamber circulation mode includes the air cushion chamber 2 internal circulation mode and the air cushion chamber 2 external circulation mode. The working chamber circulation mode is turned on by default in the fifth pump body P5;

[0058] The method for implementing the internal circulation mode of the air cushion chamber 2 is as follows: opening the eleventh valve V11, the twelfth valve V12, and the seventh valve V7;

[0059] The method for realizing the external circulation mode of the air cushion chamber 2 is: opening the first valve V1, the seventh valve V7, the eleventh valve V11, and the thirteenth valve V13.

[0060] The above description only shows open valves and pumps. Pumps and valves not described are closed. It should be noted that the mud balance mode is implemented based on the working mode. Valves and pumps opened in the working mode will also remain open in the corresponding circulation mode.

[0061] The slurry discharge pipeline, grouting pipeline, first branch, second branch, second branch, and third branch are equipped with flow meters. Density meters are also installed at the flow meter locations on the slurry discharge pipeline and the grouting pipeline. Pressure gauges are installed between the mud conditioning box 5 and the gravel tank 303. Flow sensors monitor flow rate changes; density sensors monitor slurry density changes; and pressure sensors monitor pressure changes in the outflow pipeline. In this embodiment, flow meters for the second and third branches are installed before the differentiation point to monitor branch flow changes. The operating status of the circulating slag system is determined based on changes in these monitored parameters.

[0062] In specific implementation, the mud-water separation station is provided with a mud pipeline connected to the mud pool. After the mixture of mud and slag enters the mud-water separation station through the slurry discharge pipe, the separated mud re-enters the mud pool for recycling.

[0063] For specific implementation, please refer to the attached Figure 1The yellow filling parts of the excavation chamber 1 and the air cushion chamber 2 represent the mud distribution range. The yellow filling below the air cushion chamber 2 represents mud, and the white filling above it represents compressed air. During the actual construction process, the injection amount of compressed air is calculated by monitoring the pressure on the tunnel face. The calculation method is a mature existing technology.

[0064] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0065] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A shield machine slag discharge system with variable grouting density, comprising a spiral crusher, a grouting network, and a bentonite pipeline; the spiral crusher comprises, from the excavation end to the slag discharge end, a front spiral connected to the excavation chamber and passing through an air cushion chamber, a hatch, a rear spiral, a crushed stone box, and a mud conditioning box; the crushed stone box is further provided with a crusher and a grille, and a belt conveyor is provided below the hatch, characterized in that: The grouting pipe network starts from the mud pool, and after the grouting pipe is divided into the first branch, it is further divided into the first and second sub-branches and respectively lead to the excavation chamber, and after it is divided into the second branch, it is further divided into the third and fourth sub-branches and respectively lead to the air cushion chamber and the excavation chamber, and after it is divided into the third branch, it is further divided into the fifth and sixth sub-branches and respectively lead to the rear spiral and the gravel box, and after it is divided into the fourth branch, it is connected to the return slurry pipe; The return slurry pipeline starts from the air cushion bin, is connected to the fourth branch through the gravel box, and is then connected to the mud-water separation station; The bentonite pipeline includes a bentonite tank and a slurry inlet pipeline leading to the excavation chamber; The grouting pipeline and the return slurry pipeline are respectively provided with a slurry feed pump located at the outlet of the mud pool and a slurry discharge pump located at the entrance of the mud-water separation station; the slurry feed pump is provided with a first valve at the rear of the pipeline flow direction, and the slurry discharge pump is provided with a second valve at the front of the pipeline flow direction; the fourth branch is provided with a third valve, and the slurry feed pipeline is provided with a fourth valve; the first sub-branch is provided with a fifth valve, the second sub-branch is provided with a third pump body and a sixth valve is provided at the rear of the third pump body along the pipeline flow direction; the second branch is provided with a fourth pump body before the differentiation point, and the third and fourth sub-branches are provided with a seventh valve and an eighth valve respectively; the fifth sub-branch is provided with a ninth valve, and the sixth sub-branch is provided with a tenth valve; The return slurry pipeline is provided with an eleventh valve, a fifth pump body and a twelfth valve in sequence in front of the gravel box according to the flow direction of the pipeline; the return slurry pipeline leads out a circulation branch between the fifth pump body and the twelfth valve to the front of the seventh valve of the third auxiliary branch.

2. A shield machine slag discharge system with variable grouting density according to claim 1, characterized in that: The first auxiliary branch flows into the upper part of the excavation chamber, and the second auxiliary branch slurry flushes the center of the excavation chamber.

3. A shield machine slag discharge system with variable grouting density according to claim 2, characterized in that: The fourth auxiliary branch passes into the excavation chamber through the air cushion chamber.

4. A shield machine slag discharge system with variable grouting density according to claim 3, characterized in that: The mud pool includes a low-density mud pool and a high-density mud pool. The mud density of the low-density mud pool ranges from 1.05t / m³ to 1.20t / m³, and the mud density of the high-density mud pool ranges from 1.21t / m³ to 1.50t / m³.

5. A shield machine slag discharge system with variable grouting density according to claim 4, characterized in that: The slag discharge system includes a conventional earth pressure balance mode and a mud water balance mode, wherein the mud water balance mode further includes a mud-added earth pressure balance mode, a low-density mud water balance mode and a high-density mud water balance mode; The conventional earth pressure balance mode is implemented by closing all valves and opening only the front screw, hatch and belt conveyor; The method for implementing the mud-adding earth pressure balance mode is as follows: opening the fourth valve, the front screw, the hatch and the belt conveyor; The method for implementing the low-density mud balance mode is as follows: closing the fourth valve and the hatch, and opening the front spiral, the rear spiral, and the rock crusher; The high-density mud-water balance mode is achieved by closing the fourth valve and the hatch, and opening the front spiral, the rear spiral, the stone crusher, and the mud regulating box.

6. A shield machine slag discharge system with variable grouting density according to claim 5, characterized in that: Each sub-mode of the slurry balance mode can realize four circulation modes of the grouting pipe network, including standard bypass mode, gravel box bypass mode, excavation circulation mode and working chamber circulation mode; the circulation mode defaults to turning on the slurry pump and discharge pump; The standard bypass is achieved by opening the first valve, the second valve, and the third valve; The method for implementing the gravel box bypass mode is as follows: opening the first valve, the second valve, the tenth valve, and the gravel box, the gravel crusher, and the grille; The excavation circulation mode is implemented by starting the third pump body and the fourth pump body, opening the first valve, the second valve, the sixth valve, the seventh valve, and the tenth valve, and starting the front spiral, the rear spiral, and the stone crusher after the mud enters the excavation chamber; The working cabin circulation mode includes an air cushion chamber internal circulation mode and an air cushion chamber external circulation mode. The working cabin circulation mode is turned on by default in the fifth pump body; The method for implementing the circulation mode in the air cushion chamber is as follows: opening the eleventh valve, the twelfth valve, and the seventh valve; The method for realizing the external circulation mode of the air cushion chamber is: opening the first valve, the seventh valve, the eleventh valve, and the thirteenth valve.

7. A shield machine slag discharge system with variable grouting density according to claim 6, characterized in that: The return slurry pipeline, grouting pipeline, first auxiliary branch, second auxiliary branch, second branch and third branch are equipped with flow meters. The return slurry pipeline and grouting pipeline are also equipped with density meters at the flow meter setting positions. The return slurry pipeline is equipped with a pressure gauge between the mud regulating box and the gravel box.

8. The shield machine slag discharge system with variable grouting density according to claim 1, characterized in that: The mud-water separation station is provided with a mud pipeline connected to the mud pool.

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