A method, system, storage medium and slurry shield machine for analyzing the flow velocity to prevent the formation of mud cakes on the excavation face of a slurry shield

Abstract

The present invention discloses a flow velocity analysis method, system, storage medium, and slurry shield machine for preventing mud cake formation on the excavation face of a slurry shield. The method includes the following steps: obtaining the soil physical properties, mud parameters, and stratum parameters of the current shield excavation; obtaining the soil viscosity index, undrained shear strength, and interfacial shear strength; obtaining the soil adhesion, soil cohesion, and fluid forces acting on soil particles; establishing a mathematical model of the critical flow velocity for different starting methods under different working conditions; obtaining the critical slurry flow velocity for different starting methods under different working conditions; and obtaining the critical flow velocity for preventing mud cake formation. The present invention can adapt to different working conditions and different starting methods, quickly determine the critical flow velocity for preventing mud cake formation, avoid the tedious process of frequently adjusting the mud flow velocity in traditional construction, and significantly improve construction efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of slurry shield machines, and in particular to a flow velocity analysis method, system, storage medium and slurry shield machine for preventing mud cake formation on an excavation face of a slurry shield. Background Art

[0002] During slurry shield construction, especially when tunneling in cohesive strata, the highly viscous nature of the slurry makes it highly susceptible to self-agglomeration or adhesion to the cutterhead and tool surfaces. These two phenomena are the primary mechanisms for mud cake formation. Once mud cake forms, it not only reduces the cutting efficiency of the cutterhead, but also increases tool wear and can even lead to construction safety issues. Therefore, preventing mud cake formation is crucial to ensuring the smooth progress of shield construction.

[0003] If the excavation face has good slurry flow, the fluid dynamics provided by the slurry movement can carry the debris and free it from the cutterhead, thus preventing the debris from forming a mud cake. However, in actual construction, due to the wide variation in geological conditions in different viscous strata and the varying requirements for slurry flow, it is difficult to set a fixed flow rate parameter to meet the complex scenarios influenced by multiple factors. The slurry flow rate is often adjusted continuously during construction to adapt to different situations, but this undoubtedly consumes a lot of time and effort, seriously affecting construction efficiency. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield comprises the following steps: S1, obtaining the soil physical properties, mud parameters and stratum parameters of the current shield tunneling; S2, obtaining the viscosity index, undrained shear strength and interface shear strength of the soil; S3, obtaining the soil adhesion, soil cohesion and the fluid force on the soil particles; S4, establishing different starting modes under different working conditions according to the force balance of the soil particles at the critical start. The critical flow velocity mathematical model of the formula is as follows; the working conditions include the slag adhesion working condition and the slag cohesion working condition, and the starting methods include lifting starting, sliding starting and rolling starting; S5, obtaining the mud critical flow velocity of different starting methods under different working conditions based on the critical flow velocity mathematical model of different starting methods under different working conditions; S6, obtaining the minimum mud critical flow velocity for slag starting under different working conditions; and the maximum value of the minimum mud critical flow velocity for slag starting under different working conditions is used as the critical flow velocity for preventing mud cake formation.

[0007] Furthermore, the soil physical properties include soil density, particle size, Poisson's ratio, plasticity index, moisture content, and liquid limit of soil; the mud parameters include mud density, viscosity, and Reynolds number; and the formation parameters include water and soil pressure.

[0008] Furthermore, the viscosity index of the slag is , undrained shear strength , the interface shear strength a is obtained according to the following formula: ; ; ; Indicates the viscosity index of the slag. represents the liquid limit of the soil, Indicates the soil moisture content, represents the plasticity index of the soil. Indicates the undrained shear strength of the soil. represents the actual normal pressure, and a represents the interfacial shear strength of the soil; 、 、 are the first, second and third correlation coefficients of undrained shear strength, respectively; 、 、 They are the fourth, fifth and sixth correlation coefficients of interface shear strength, respectively.

[0009] Furthermore, the soil cohesion and soil adhesion Obtained by the following formula: ; ; A It indicates the contact area when the slag undergoes shear failure.

[0010] Furthermore, step S4 includes:

[0011] Establish a mathematical model of the critical flow velocity for lifting start-up under soil cohesion conditions:

[0012] ;

[0013] Establish a mathematical model of the critical velocity of sliding start in soil cohesion conditions:

[0014] ;

[0015] Establish a mathematical model of the critical flow velocity of rolling start under soil cohesion conditions:

[0016] ;

[0017] Establish a mathematical model of the critical flow velocity for lifting start-up under soil adhesion conditions:

[0018] ;

[0019] Establish a mathematical model of the critical flow velocity of sliding start under soil adhesion conditions:

[0020] ;

[0021] Establish a mathematical model of the critical flow velocity for rolling start under soil adhesion conditions:

[0022] ;

[0023] The critical slurry velocity for lifting start in the condition of soil cohesion; Critical slurry velocity during sliding start-up under soil cohesion conditions; The critical velocity of the slurry during rolling start-up under the condition of soil cohesion; The critical slurry velocity for lifting start in the condition of soil adhesion; The critical velocity of the slurry during sliding start under the condition of soil adhesion; The critical velocity of the slurry for rolling start in the condition of soil adhesion; It represents the angle between the mud flow direction and the gravity direction. Indicates the angle between the movement direction of the soil particles and the direction of gravity; is the density of soil, is the normal water and soil pressure; represents the lift coefficient, It means that the soil is dragged by the fluid. Indicates that the soil is lifted by the fluid; represents the mud density, D represents the diameter of soil particles, represents the drag coefficient; The gravity of the soil, is the buoyancy of the soil.

[0024] Furthermore, step S6 specifically includes:

[0025] The minimum starting flow rate under the soil cohesion condition is obtained according to the following formula :

[0026] ;

[0027] The minimum starting flow rate under soil adhesion conditions is obtained according to the following formula: :

[0028] ;

[0029] The critical flow rate to prevent mud cake formation is obtained according to the following formula:

[0030] .

[0031] Furthermore, the fluid force acting on the soil particles is obtained by the following formula: ; Re Reynolds number.

[0032] The present invention also provides a flow rate analysis system for preventing mud cake formation on the excavation face of a slurry shield, comprising: a parameter acquisition module for acquiring the soil physical property parameters, mud parameters and stratum parameters of the current shield excavation; an intermediate parameter acquisition module for acquiring the viscosity index, undrained shear strength and interface shear strength of the soil; a force acquisition module for acquiring the soil adhesion, soil cohesion and the fluid force on the soil particles; a model establishment module for establishing different starting modes under different working conditions according to the force balance at the critical start of the soil particles under different working conditions. The invention provides a multi-operating condition critical flow rate mathematical model for different starting modes; the operating conditions include slag adhesion operating conditions and slag cohesion operating conditions, and the starting modes include lifting start, sliding start and rolling start; a multi-operating condition critical flow rate acquisition module is used to obtain the mud critical flow rate of different starting modes under different operating conditions based on the critical flow rate mathematical models of different starting modes under different operating conditions; a critical flow rate acquisition module for preventing mud cake formation is used to obtain the minimum mud critical flow rate for slag starting under different operating conditions; the maximum value of the minimum mud critical flow rate for slag starting under different operating conditions is used as the critical flow rate for preventing mud cake formation.

[0033] The present invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the steps of the flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield are implemented.

[0034] The present invention also provides a slurry shield machine, comprising a flow rate analysis system for preventing mud cake formation on the excavation surface of the slurry shield.

[0035] The present invention has the following beneficial effects:

[0036] By determining the soil's viscosity index, undrained shear strength, interfacial shear strength, as well as its adhesion, cohesion, and the fluid forces acting on soil particles, the authors were able to accurately analyze the soil's mechanical properties under different operating conditions. This provided key data support for the development of a mathematical model for critical flow velocity, enhancing the model's scientificity and practicality. By establishing mathematical models for different starting methods under different operating conditions, the authors were able to comprehensively consider the various possible scenarios of soil in actual construction. The establishment of models for multiple operating conditions and starting methods resulted in analysis results that were more closely aligned with actual construction conditions, adapting to the varying starting methods under different operating conditions and improving the specificity and effectiveness of preventing mud cake formation. By using mathematical models for different starting methods under different operating conditions to determine the critical slurry flow velocity for each starting method under different operating conditions, and further determining the minimum critical slurry flow velocity for soil starting under different operating conditions, the authors were able to scientifically determine the critical slurry flow velocity required to prevent mud cake formation. This eliminates the tedious process of frequently adjusting slurry flow rates in traditional construction, significantly improving construction efficiency and reducing construction risks. It effectively prevents the formation of mud cakes, minimizing the reduced cutterhead cutting efficiency, increased tool wear, and potential safety hazards associated with mud cakes, ensuring smooth shield construction. It provides construction personnel with a scientific basis for decision-making, reduces the uncertainty associated with human experience, and improves the controllability and stability of the construction process.

[0037] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0040] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0043] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0044] Please refer to Figure 1 In a preferred embodiment of the present invention, a flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield is provided, comprising steps S1, S2, S3, S4, S5 and S6.

[0045] S1, obtain the soil physical parameters, mud parameters and formation parameters of the current shield tunneling.

[0046] S2, obtain the viscosity index, undrained shear strength and interface shear strength of the soil.

[0047] S3, obtain the soil adhesion force, soil cohesion force and fluid force acting on soil particles. The fluid is mud.

[0048] S4. Based on the force balance at critical starting of different starting methods under different working conditions, a mathematical model of the critical flow rate for different starting methods under different working conditions is established. The working conditions include the sticking and agglomerating working conditions, and the starting methods include lifting, sliding, and rolling starting. Critical starting means that the slag is in a state of force balance, and if the slurry force decreases at this time, the slag cannot start, i.e., it is in the critical state between starting and not starting.

[0049] S5. Obtain the critical flow velocity of the mud under different starting modes under different working conditions according to the critical flow velocity mathematical model of the mud under different starting modes under different working conditions.

[0050] S6, obtain the minimum critical mud flow rate for slag starting under different working conditions; the minimum critical mud flow rate is the minimum value of the critical mud flow rates of multiple starting methods under the same working condition, that is, under this working condition, only one method of slag starting is needed, and the slag will not adhere to the cutter disc surface to form a mud cake, thereby preventing mud cake. Therefore, it is only necessary to take the minimum value of the critical mud flow rates of multiple starting methods under the same working condition as the critical mud flow rate for preventing mud cake under this working condition, avoiding excessive flow rate determination and resulting in increased energy consumption. The maximum value of the minimum critical mud flow rate for slag starting under different working conditions is used as the critical flow rate for preventing mud cake formation, that is, this flow rate meets the critical flow rate for preventing mud formation under different working conditions, can adapt to different working conditions, and ensure the effect of preventing mud.

[0051] A preferred embodiment of the present invention provides a flow velocity analysis method for preventing mud cake formation at the excavation face of a slurry shield. By obtaining the soil's viscosity index, undrained shear strength, interfacial shear strength, as well as soil adhesion, soil cohesion, and the fluid forces acting on soil particles, this method accurately analyzes the mechanical properties of soil under different operating conditions. This provides key data support for establishing a critical flow velocity mathematical model, improving the model's scientificity and practicality. By establishing a critical flow velocity mathematical model for different starting methods under different operating conditions, the various possible conditions of soil in actual construction can be comprehensively considered. The establishment of a model for multiple operating conditions and starting methods makes the analysis results more closely aligned with actual construction conditions, adapting to different starting methods under different operating conditions, and improving the targetedness and effectiveness of preventing mud cake formation. By using the critical flow velocity mathematical model for different starting methods under different operating conditions to obtain the slurry critical flow velocity for different starting methods under different operating conditions, and further obtaining the minimum critical slurry flow velocity for soil starting under different operating conditions, the critical slurry flow velocity for preventing mud cake formation can be scientifically determined. This eliminates the tedious process of frequently adjusting slurry flow rates in traditional construction, significantly improving construction efficiency and reducing construction risks. It effectively prevents the formation of mud cakes, minimizing the reduced cutterhead cutting efficiency, increased tool wear, and potential safety hazards associated with mud cakes, ensuring smooth shield construction. It provides construction personnel with a scientific basis for decision-making, reduces the uncertainty associated with human experience, and improves the controllability and stability of the construction process.

[0052] In a specific embodiment of the present invention, the soil physical properties include: soil density, particle size, Poisson's ratio, plasticity index, moisture content, and liquid limit of soil; the mud parameters include: mud density, viscosity, and Reynolds number; and the formation parameters include: water and soil pressure.

[0053] The viscosity index of the slag , undrained shear strength , the interface shear strength a is obtained according to the following formula:

[0054] ;

[0055] ;

[0056] ;

[0057] Indicates the viscosity index of the slag. represents the liquid limit of the soil, Indicates the soil moisture content, represents the plasticity index of the soil. Indicates the undrained shear strength of the soil. represents the actual normal pressure, and a represents the interfacial shear strength of the soil; 、 、 are the first correlation coefficient, the second correlation coefficient and the third correlation coefficient of undrained shear strength, which can be obtained by fitting based on experiments; 、 、 are the fourth, fifth and sixth correlation coefficients of the interface shear strength, respectively, and can be obtained by fitting according to experiments. Specifically, in one embodiment, ; .in, .

[0058] Specifically, the soil cohesion and soil adhesion Obtained by the following formula:

[0059] ;

[0060] ;

[0061] A It represents the contact area when the soil is sheared. It represents the cohesive force between soil particles. Represents the adhesion force between soil particles and metal interface.

[0062] Contact area when the slag fails in shear A canThe results were obtained through numerical simulation. The specific steps are as follows: Based on the Hertz elastic contact theory, a calculation model of slag particles was established, assuming that the slag material is uniform, isotropic, and completely elastic. Using ANSYS software, parameters such as the elastic modulus, Poisson's ratio, and density of the slag were set. Full displacement constraints were applied to the contact nodes, with a zero displacement constraint in the X direction applied to all nodes with an X coordinate of 0, and a zero displacement constraint in the Y direction applied to all nodes with a Y coordinate of 0. A load was applied to the top node of the particle, and the load value was set according to the normal pressure and the size of the slag. In the ANSYS post-processing, a command flow was written to calculate the particle contact radius, and then the particle contact area was calculated.

[0063] In some embodiments of the present invention, the fluid force acting on the soil particles is obtained by the following formula:

[0064] ;

[0065] ;

[0066] ;

[0067] represents the mud density, D represents the diameter of soil particles, represents the drag coefficient, represents the flow rate of the mud fluid, Re represents the Reynolds number, represents the lift coefficient, It means that the soil is dragged by the fluid. Indicates that the soil is lifted by the fluid. and The formula can be used as the basis for the force balance calculation in the subsequent step S4.

[0068] In some embodiments of the present invention, step S4 includes:

[0069] Establish a mathematical model of the critical flow velocity for lifting start-up under soil cohesion conditions:

[0070] ; and The excavation surface is perpendicular to the cutterhead. At this time, the slag is in a force balance, and this balance is fragile. The mud flow rate only needs to be maintained at this time or greater than this time, and the slag will start to separate the cutterhead in a lifting manner.

[0071] Establish a mathematical model of the critical velocity of sliding start in soil cohesion conditions:

[0072] ;

[0073] That is, the component of the difference between gravity and buoyancy in the sliding direction of the slag particles plus the component of the drag force of the fluid on the slag in the sliding direction of the slag particles is equal to the cohesive force of the slag. At this time, the slag is in force balance, and the mud flow rate only needs to be maintained at this time or greater than this time, and the slag will start to separate in a sliding manner.

[0074] Establish a mathematical model of the critical flow velocity of rolling start under soil cohesion conditions:

[0075] .

[0076] When the slag rolling starts at the critical state, the resultant torque for:

[0077] =0.

[0078] That is, the sum of the drag force on the soil from the fluid in the rolling direction, the difference between gravity and buoyancy in the rolling direction, and the moment of the fluid's lifting force on the soil equals the sum of the normal water-soil pressure on the soil and the moment of the soil's cohesive force. At this point, the slurry flow rate only needs to be maintained at or above this level for the soil to begin rolling and separating.

[0079] Establish a mathematical model of the critical flow velocity for lifting start-up under soil adhesion conditions:

[0080] ; The critical flow velocity of the mud for lifting start-up in adhesion condition and cohesion condition is the same.

[0081] Establish a mathematical model of the critical flow velocity of sliding start under soil adhesion conditions:

[0082] ;

[0083] Establish a mathematical model of the critical flow velocity for rolling start under soil adhesion conditions:

[0084] ;

[0085] The critical slurry velocity for lifting start in the condition of soil cohesion; Critical slurry velocity during sliding start-up under soil cohesion conditions;

[0086] The critical velocity of the slurry during rolling start-up under the condition of soil cohesion; The critical slurry velocity for lifting start in the condition of soil adhesion;

[0087] The critical velocity of the slurry during sliding start under the condition of soil adhesion; The critical velocity of the slurry for rolling start in the condition of soil adhesion;

[0088] It represents the angle between the mud flow direction and the gravity direction. Indicates the angle between the movement direction of the soil particles and the direction of gravity; is the density of soil, is the normal water and soil pressure; represents the lifting force coefficient, which can be obtained through experimental fitting. It means that the soil is dragged by the fluid. Indicates that the soil is lifted by the fluid; represents the density of mud, D represents the diameter of soil particles, represents the drag coefficient; The gravity of the soil, is the buoyancy of the soil. ; In the above formula, except 、 、 、 、 and These six quantities are unknown, and the rest are known or measurable. 、 、 、 、 and These six quantities.

[0089] In some embodiments of the present invention, step S6 specifically includes:

[0090] The minimum starting flow rate under the soil cohesion condition is obtained according to the following formula :

[0091] ;

[0092] The minimum starting flow rate under soil adhesion conditions is obtained according to the following formula: :

[0093] ;

[0094] The critical flow rate to prevent mud cake formation is obtained according to the following formula :

[0095] .

[0096] When the difference between gravity and buoyancy is greater than cohesion or adhesion, it means that the debris can fall off automatically. When the difference between gravity and buoyancy is less than cohesion or adhesion, mud fluid is needed to drive the debris to fall off and reduce the formation of mud cake. and This means that taking the minimum value of the critical mud flow rate of the three starting methods under the same working conditions can meet the requirements of at least one starting method, thus achieving slag starting and reducing mud cake formation.

[0097] The present invention also provides a flow rate analysis system for preventing mud cake formation on the excavation face of a slurry shield, which includes a parameter acquisition module, a force acquisition module, a model building module, a multi-working condition critical flow rate acquisition module and a critical flow rate acquisition module for preventing mud cake formation.

[0098] The parameter acquisition module is used to obtain the physical parameters of the slag, mud parameters and formation parameters of the current shield tunneling; the intermediate parameter acquisition module is used to obtain the viscosity index, undrained shear strength and interface shear strength of the slag; the force acquisition module is used to obtain the adhesion force, cohesion force and fluid force on the slag particles; the model establishment module is used to establish the critical flow rate mathematical model of different starting methods under different working conditions based on the force balance of the slag particles at the critical start of different starting methods under different working conditions; the working The conditions include slag adhesion conditions and slag cohesion conditions, and the starting methods include lifting start, sliding start and rolling start; a multi-condition critical flow rate acquisition module is used to obtain the mud critical flow rate of different starting methods under different working conditions based on the critical flow rate mathematical model of different starting methods under different working conditions; a critical flow rate acquisition module for preventing mud cake formation is used to obtain the minimum mud critical flow rate for slag starting under different working conditions; the maximum value of the minimum mud critical flow rate for slag starting under different working conditions is used as the critical flow rate for preventing mud cake formation.

[0099] The present invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the steps of the flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield are implemented.

[0100] The present invention also provides a slurry shield machine, comprising a flow rate analysis system for preventing mud cake formation on the excavation surface of the slurry shield.

[0101] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield, characterized in that: The steps include: S1, obtaining the soil physical parameters, mud parameters and stratum parameters of the current shield tunneling; S2, obtain the viscosity index, undrained shear strength, and interfacial shear strength of the soil; S3, obtaining the soil adhesion force, soil cohesion force and fluid force acting on soil particles; S4, establishing a mathematical model of critical flow rates for different starting modes under different working conditions based on the force balance during critical starting of different starting modes under different working conditions of slag particles; the working conditions include slag adhesion conditions and slag cohesion conditions, and the starting modes include lifting start, sliding start, and rolling start; S5, obtaining the critical flow velocity of the mud for different starting modes under different working conditions according to the critical flow velocity mathematical model for different starting modes under different working conditions; S6, obtaining the minimum critical mud flow rate for starting the slag under different working conditions; taking the maximum value of the minimum critical mud flow rate for starting the slag under different working conditions as the critical flow rate for preventing mud cake formation; Step S4 includes: Establish a mathematical model of the critical flow velocity for lifting start-up under soil cohesion conditions: ； Establish a mathematical model of the critical velocity of sliding start in soil cohesion conditions: ； Establish a mathematical model of the critical flow velocity of rolling start under soil cohesion conditions: ； Establish a mathematical model of the critical flow velocity for lifting start-up under soil adhesion conditions: ； Establish a mathematical model of the critical flow velocity of sliding start under soil adhesion conditions: ； Establish a mathematical model of the critical flow velocity for rolling start under soil adhesion conditions: ； The critical slurry velocity for lifting start in the condition of soil cohesion; Critical slurry velocity during sliding start-up under soil cohesion conditions; The critical velocity of the slurry during rolling start-up under the condition of soil cohesion; The critical slurry velocity for lifting start in the condition of soil adhesion; The critical velocity of the slurry during sliding start in the condition of soil adhesion; The critical velocity of the slurry for rolling start in the condition of soil adhesion; It represents the angle between the mud flow direction and the gravity direction. Indicates the angle between the movement direction of the soil particles and the direction of gravity; is the density of soil, is the normal water and soil pressure; represents the lift coefficient, It means that the soil is dragged by the fluid. Indicates that the soil is lifted by the fluid; represents the mud density, D represents the diameter of soil particles, represents the drag coefficient; The gravity of the soil, is the buoyancy of the soil; Indicates the viscosity index of the slag; Indicates the undrained shear strength of the soil. represents the actual normal pressure, and a represents the interfacial shear strength of the soil; 、 、 are the first, second and third correlation coefficients of undrained shear strength, respectively; 、 、 are the fourth, fifth and sixth correlation coefficients of the interface shear strength, respectively; A Indicates the contact area when the soil undergoes shear failure; is the cohesion of the slag soil, It is the adhesion force of slag.

2. The flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield according to claim 1 is characterized in that: The slag physical property parameters include: slag density, particle size, Poisson's ratio, plasticity index, water content, and liquid limit of slag; the mud parameters include: mud density, viscosity, and Reynolds number; and the formation parameters include: water and soil pressure.

3. The flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield according to claim 2 is characterized in that: The viscosity index of the slag , undrained shear strength , the interface shear strength a is obtained according to the following formula: ； ； ； represents the liquid limit of the soil, Indicates the soil moisture content, Indicates the plasticity index of the soil.

4. The flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield according to claim 3 is characterized in that: The soil cohesion and soil adhesion Obtained by the following formula: ; 。 5. The flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield according to claim 1 is characterized in that: Step S6 specifically includes: The minimum starting flow rate under the soil cohesion condition is obtained according to the following formula : ； The minimum starting flow rate under soil adhesion conditions is obtained according to the following formula: : ； The critical flow rate to prevent mud cake formation is obtained according to the following formula: 。 6. The flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield according to claim 1 is characterized in that: The fluid force on the soil particles is obtained by the following formula: ； Re Reynolds number.

7. A flow velocity analysis system for preventing mud cake formation on the excavation face of a slurry shield, used to implement the flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield according to any one of claims 1 to 6, characterized in that: include: Parameter acquisition module, used to obtain the soil physical parameters, mud parameters and formation parameters of the current shield tunneling; The intermediate parameter acquisition module is used to obtain the viscosity index, undrained shear strength, and interface shear strength of the soil; The force acquisition module is used to obtain the adhesion force of the slag soil, the cohesion force of the slag soil and the fluid force acting on the slag soil particles; A model building module is used to establish a mathematical model of critical flow rates for different starting modes under different working conditions based on the force balance during critical starting of different starting modes under different working conditions of slag particles; the working conditions include slag adhesion conditions and slag cohesion conditions, and the starting modes include lifting start, sliding start, and rolling start; The multi-working condition critical flow velocity acquisition module is used to obtain the critical flow velocity of mud under different working conditions and different starting modes according to the critical flow velocity mathematical model of different starting modes under different working conditions; The critical flow rate acquisition module for preventing mud cake formation is used to obtain the minimum mud critical flow rate for starting slag under different working conditions; the maximum value of the minimum mud critical flow rate for starting slag under different working conditions is used as the critical flow rate for preventing mud cake formation.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the flow velocity analysis method for preventing mud cake formation on the excavation face of a slurry shield are implemented as described in any one of claims 1 to 6.

9. A slurry shield machine, characterized in that: It includes the flow rate analysis system for preventing mud cake formation on the excavation face of a slurry shield as described in claim 7.

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