Method and system for matching rotation speed of short screw conveyor of super-large-diameter slurry shield and storage medium

Abstract

The application provides a large-diameter slurry shield short screw conveyor rotating speed matching method and system and a storage medium, and belongs to the technical field of slurry shield construction residue discharge. In view of the problem that the short screw rotating speed in the prior art depends on experience setting and lacks systematic matching logic, the application is based on the cutter head rotating speed and the advancing speed, a CFD-DEM coupling simulation model of the slurry fluid and the rock residue particles is constructed, and the residue discharge process under different short screw rotating speeds is simulated; the residue accumulation and the conveying efficiency indicators are defined, the response models are respectively established, and the comprehensive evaluation model is constructed; under a given working condition, the short screw rotating speed is taken as an optimization variable, and the matching rotating speed that makes the comprehensive performance optimal is solved in the allowable interval. The method can realize effective balance of the residue discharge efficiency and the equipment wear, and improve the tunneling stability and the construction efficiency of the large-diameter slurry shield under complex geological conditions.

Description

Technical Field

[0001] This application relates to the field of slag removal technology in tunnel boring machine (TBM) construction, specifically to a method, system, and storage medium for matching the rotational speed of a short spiral conveyor for an ultra-large diameter slurry shield. Background Technology

[0002] Ultra-large diameter slurry shield tunneling machines are widely used in cross-sea and cross-river tunnels and urban underground engineering projects. They are highly adaptable to high water pressure and complex geological conditions, and exhibit high tunneling stability. During the slurry shield tunneling process, the rock debris generated by the cutterhead is continuously discharged through the muck removal system after being carried by circulating slurry.

[0003] As the diameter of the tunnel boring machine (TBM) increases and the complexity of the working conditions rises, the traditional method of removing slag by relying entirely on mud can easily lead to rock accumulation and local blockage at the bottom of the excavation chamber, which in turn can cause malfunctions such as increased cutterhead torque, pressure fluctuations, and secondary wear of the cutters.

[0004] To address the aforementioned issues, a short screw conveyor can be installed at the bottom of the excavation chamber, enabling efficient slag removal through a combination of agitation and mechanical conveying. However, the operating parameters of the short screw conveyor—especially its rotational speed—are currently largely based on empirical settings, lacking a logically explainable determination principle. Furthermore, the cutterhead rotational speed and propulsion speed (both predetermined parameters) are constrained by geological conditions and construction organization. To achieve a rapid and quantitative match between the short screw rotational speed and slag removal efficiency while minimizing equipment wear, the short screw rotational speed should not be an empirical value. In other words, the existing matching principles between the short screw rotational speed and predetermined parameters lack a systematic and logically sound determination process. Summary of the Invention

[0005] This application provides a method for matching the rotational speed of a short spiral conveyor in an ultra-large diameter slurry shield tunnel, which can provide a systematic short spiral rotational speed based on the cutterhead rotational speed and the propulsion speed, so as to coordinate the slag removal efficiency and the equipment wear rate.

[0006] The technical solution of this application is as follows:

[0007] A method for matching the rotational speed of a short screw conveyor in an ultra-large diameter slurry shield tunnel includes the following steps:

[0008] Step 1: Based on DEM, establish a three-dimensional solid model of the cutterhead, excavation chamber, slurry inlet pipeline and short screw conveyor, and extract the computational domain of mud fluid and rock debris particles in the three-dimensional solid model based on CFD.

[0009] Step 2: Construct a coupled motion simulation model of mud fluid and rock debris particles in the computational domain, as follows:

[0010] Based on CFD, the instantaneous velocity and pressure fields of each grid are output as a continuous phase of mud fluid;

[0011] Based on DEM, the position, velocity, and stress state of each rock slag particle are output as a discrete particle group, and the weight of the rock slag particles discharged from the slag discharge port of the short screw conveyor is calculated.

[0012] Perform grid-particle space mapping and time step synchronization, and interpolate the instantaneous velocity field and pressure field in the CFD computational domain to the current position of each rock fragment particle under the synchronized time step;

[0013] Step 3: Using the cutter head rotation speed, propulsion speed, and short helix rotation speed as design variables, generate several sets of design variable combinations and run the coupled motion simulation model group by group to obtain the flow field results and particle migration results of the short helix conveyor during the conveying stage.

[0014] Step 4: Define the slag accumulation index to characterize the amount of rock debris particles in the excavation chamber, and define the conveying efficiency index to characterize the slag discharge capacity of the short screw conveyor; based on the coupled motion simulation results of Step 3, calculate the slag accumulation and conveying efficiency corresponding to each combination of design variables; based on the calculation results of slag accumulation and conveying efficiency, fit the slag accumulation response model and the conveying efficiency response model respectively, and after standardization, construct a comprehensive evaluation model;

[0015] Step 5: Given the cutter head speed and the feed speed, with the short helix speed as the optimization variable, within the allowable range of the short helix speed, calculate the optimal short helix speed based on the comprehensive evaluation model and use it as the matching speed of the short helix conveyor.

[0016] Furthermore, in the solid model, the cutterhead and short spiral conveyor are configured as rotating bodies, and the short spiral conveyor is configured with a short spiral boundary; the slurry inlet pipe is configured as a velocity inlet or a mass inlet; the slag discharge port of the short spiral conveyor is configured as a pressure outlet; and the excavation chamber and the equipment wall are configured with a non-slip boundary.

[0017] Furthermore, in CFD, the mud fluid, which is a continuous phase, is solved based on the mass conservation equation and the momentum conservation equation.

[0018] In the DEM, the position, velocity, and stress state of each particle are solved based on the translational and rotational control equations of the rock debris particles.

[0019] Furthermore, in step three, the design variables also include mud density, rheological parameters, and rock cutting particle size distribution.

[0020] Furthermore, in step four, the slag accumulation index is defined as the time average of the rock debris mass in the excavation chamber during the stable phase; the stable phase is defined based on the simulation time.

[0021] The conveying efficiency index is defined as the ratio of the actual slag discharge mass flow rate to the theoretical maximum conveying capacity.

[0022] Furthermore, in step four, a wear index is defined as a constraint on the working time of the short screw conveyor;

[0023] The wear index is defined as the time average of the erosion energy, contact work, or wear rate on the blade surface of the short screw conveyor.

[0024] Secondly, this application provides a speed matching system for a short spiral conveyor for an ultra-large diameter slurry shield tunnel, including a processor and a memory storing program instructions. The processor is configured to execute the speed matching method for the short spiral conveyor for an ultra-large diameter slurry shield tunnel as described above when running the program instructions.

[0025] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the speed matching method for a short spiral conveyor for an ultra-large diameter slurry shield tunnel as described above.

[0026] Due to the adoption of the above technical solution, the beneficial effects of this application are as follows:

[0027] 1. This application uses a CFD-DEM coupled simulation model to accurately simulate the complex interaction and migration patterns of mud fluid and large rock debris particles within the excavation chamber. Based on this, the established debris accumulation response model can quantitatively predict the rock debris accumulation at the bottom of the excavation chamber under different screw rotation speeds. Under given cutterhead rotation speed and propulsion speed, the system can match the optimal screw rotation speed. This matching result can suppress the retention and local blockage of rock debris at its source, avoiding chain failures such as abnormal increase in cutterhead torque and pressure fluctuations at the excavation face caused by poor debris discharge. This ensures continuous and efficient tunneling of the tunnel boring machine under high water pressure and highly complex geological conditions, significantly reducing unplanned downtime.

[0028] 2. A one-sided pursuit of high rotational speeds to ensure smooth slag discharge can lead to severe erosion and wear on the short spiral blades and casing walls caused by intense particle impact and friction. This application innovatively introduces a dual-objective synergistic optimization mechanism for conveying efficiency and slag accumulation, and uses a comprehensive evaluation model to quantitatively balance these two factors. The final optimal matching speed is not simply "highest" or "lowest," but rather ensures that the slag discharge capacity meets the tunneling requirements (high conveying efficiency) while keeping the equipment wear risk within a reasonable threshold. This strategy provides a global perspective on slag discharge, reducing the frequency of expensive spiral conveyor maintenance and replacement from the perspective of the entire shield tunnel's lifespan, and also reducing project delays and cost overruns caused by equipment damage.

[0029] 3. This application abandons the traditional fuzzy judgment based on experience and establishes a reusable logic based on core tunneling parameters (cutterhead speed and propulsion speed). This forms a systematic and logically clear judgment principle. The final output of the optimal screw speed has a clear physical meaning and a traceable simulation verification basis, making the control process of the slag removal system transparent and reliable. Attached Figure Description

[0030] The accompanying drawings, which are provided to further understand this application and constitute a part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0031] Figure 1 Flowchart of the method for matching the speed of a short screw conveyor for an ultra-large diameter slurry shield tunnel provided in this application;

[0032] Figure 2 This is a diagram showing the coupling relationship between the DEM model and the CFD model in this application;

[0033] Figure 3 This is a schematic diagram of the two-phase coupling (CFD-DEM) simulation and data interaction in this application;

[0034] Figure 4 The recommended rotational speed for the short helix in this embodiment is obtained by referring to a table. Detailed Implementation

[0035] Based on the background technology, both the cutterhead and the short spiral conveyor of a tunnel boring machine (TBM) are rotating mechanisms. The short spiral conveyor is equipped with a slag discharge port for discharging rock debris particles. The cutterhead, excavation chamber, slurry inlet pipeline, and short spiral conveyor are the main functional components, and the equipment walls constitute the inner surface of other metal structures at the boundary of the excavation chamber. The short spiral conveyor is installed at the bottom of the excavation chamber and efficiently discharges slag by mixing slurry and mechanically conveying it. Addressing the problem that existing matching principles between the speed of the short spiral conveyor and predetermined parameters lack a systematic judgment logic, this application proposes a speed matching method for a short spiral conveyor in an ultra-large diameter slurry shield TBM, including the following steps:

[0036] Step 1: Based on DEM, establish a three-dimensional solid model of the cutterhead, excavation chamber, slurry inlet pipeline and short screw conveyor. Based on CFD, extract the computational domain of mud fluid and rock debris particles in the three-dimensional solid model.

[0037] As attached Figure 1 and attached Figure 2As shown, in the solid model, the cutterhead and short spiral conveyor are set as rotating bodies, and the short spiral conveyor has a boundary defined by a short spiral. The slurry inlet pipe is set as a velocity inlet or a mass inlet. The slag discharge port of the short spiral conveyor is set as a pressure outlet. The excavation chamber and the equipment wall have a non-slip boundary. It should be explained that during the modeling process, the DEM is used to simulate the solid model, with the cutterhead and short spiral both set as rotating bodies. In the CFD, the fluid region is simulated; the fluid region is the area through which the fluid flows after subtracting the three-dimensional solid, such as the opening area of ​​the cutterhead and the internal flow domain of the short spiral conveyor. The fluid region is a rotating region, and the rotational speed is consistent with the three-dimensional solid model. It should be noted that the slurry inlet pipe solid model corresponds to the mud inlet, and the slag discharge port is the rock debris outlet, which is designed as a pressure outlet in the actual implementation.

[0038] Step 2: Construct a coupled motion simulation model of mud fluid and rock debris particles in the computational domain, as follows:

[0039] Based on CFD, the instantaneous velocity and pressure fields of each grid are output as a continuous phase of mud fluid;

[0040] Based on DEM, the position, velocity, and stress state of each rock slag particle are output as a discrete particle group, and the weight of the rock slag particles discharged from the slag discharge port of the short screw conveyor is calculated.

[0041] In CFD, the solution for mud fluid as a continuous phase is obtained based on the mass conservation equation and the momentum conservation equation:

[0042] ;

[0043] ;

[0044] In the formula, Indicates the volume fraction of mud fluid. t Indicates time, Indicates fluid velocity. Indicates mud pressure, Indicates the density of the mud. Represents the shear stress tensor. This represents the interaction force between two phases. It represents the acceleration due to gravity.

[0045] In the DEM, the position, velocity, and stress state of each particle are solved based on the translational and rotational control equations of the rock debris particles:

[0046] ;

[0047] ;

[0048] In the formula, , , They represent rock slag particles i With rock slag particles j Contact force, damping force, and torque between them , and They represent rock slag particles i Contact force, damping force, and torque between the device and the wall. This indicates that the mud was applied to the rock debris particles. i The force on top, , , , They represent slag particles respectively i Mass, velocity, moment of inertia, and angular velocity.

[0049] In practical implementation, the Bingham model, a non-Newtonian model, is adopted for the mud fluid phase, and the relationship between mud shear stress and shear rate is as follows:

[0050] ;

[0051] In the formula, Represents shear stress. Indicates yield stress. Indicates the viscosity of the mud. This represents the shear rate.

[0052] Perform grid-particle space mapping and time step synchronization, and interpolate the instantaneous velocity field and pressure field in the CFD computation domain to the current position of each rock fragment particle under the synchronized time step.

[0053] As attached Figure 3 As shown, energy and momentum transfer between CFD and DEM are achieved through an Application Programming Interface (API). The application is configured such that at the start of the calculation, the CFD software calls the API to read particle velocity and position information from the DEM software. Based on the particle state at the current time point, the mesh porosity and flow state in the CFD software are calculated. After iterative convergence, the slurry flow state is transformed into fluid-structure interaction forces using a drag model and transmitted to the DEM software via the API. The DEM software then begins a calculation for one time step, calculating and updating the particle velocity and position. Finally, the particle information is sent back to the CFD software, and a new loop begins, completing the bidirectional coupled calculation.

[0054] Step 3: Using the cutter head rotation speed, propulsion speed, and short helix rotation speed as design variables, generate several sets of design variable combinations and run the coupled motion simulation model group by group to obtain the flow field results and particle migration results of the short helix conveyor during the conveying stage.

[0055] In practice, Box-Behnken design, central composite design, or orthogonal experimental design are used to generate multiple combinations of design variables to obtain the flow field and particle migration results during the steady-state phase. It should be noted that the simulation steady-state phase is defined based on the simulation time; for example, a simulation time of 400-500 seconds can be considered a steady-state phase.

[0056] Preferably, in step three, the design variables also include mud density, rheological parameters, and rock cutting particle size distribution. In practice, mud density is obtained using a densitometer, rheological parameters are obtained using a six-speed viscometer, and rock cutting particle size distribution is obtained through on-site sampling and sieving. The newly added design variables are still combined using the above experimental design, and the flow field results and particle migration results in the steady-state phase are used in subsequent steps.

[0057] Step 4: Define the slag accumulation index to characterize the amount of rock debris particles in the excavation chamber, and define the conveying efficiency index to characterize the slag discharge capacity of the short screw conveyor; based on the coupled motion simulation results of Step 3, calculate the slag accumulation and conveying efficiency corresponding to each combination of design variables; based on the calculation results of slag accumulation and conveying efficiency, respectively fit the slag accumulation response model and the conveying efficiency response model, and after standardization, construct a comprehensive evaluation model.

[0058] The slag accumulation index is defined as the time average of the rock slag mass in the excavation chamber during the stable phase; the conveying efficiency index is defined as the ratio of the actual slag discharge mass flow rate to the theoretical maximum conveying capacity.

[0059] In practical implementation, the actual slag discharge mass flow rate of the conveying efficiency index can be approximated by the slag production mass flow rate:

[0060] ;

[0061] In the formula, q This indicates the actual slag discharge mass flow rate of the short screw conveyor. Indicates the density of rock slag. S Indicates the excavation area. B Indicates the speed of advancement.

[0062] Maximum conveying capacity is calculated from the short screw geometry and rotational speed:

[0063] ;

[0064] In the formula, Q This represents the theoretical mass flow rate of the short screw conveyor. l Indicates short helix pitch. D s Indicates the diameter of the short helical blade. d s Indicates the diameter of the short helix's axis of rotation. CThis indicates the rotational speed of the short helix.

[0065] Preferably, in step four, a wear index is defined as a constraint on the operating time of the short screw conveyor; the wear index is defined as the time average of the erosion energy, contact work, or wear rate on the blade surface of the short screw conveyor. The wear rate can be obtained from the DEM, and when the wear rate is too fast, it is considered that there may be a risk of wear-through to the short screw conveyor.

[0066] Let R1 be the slag accumulation index and R2 be the conveying efficiency index;

[0067] For R1, a smaller calculated value is better; for R2, a larger calculated value is better. Standardizing R1 and R2 separately yields... and ,based on and Construct a comprehensive evaluation model:

[0068] ;

[0069] In the formula, w 1 and w 2 represents the weights of the standardized slag accumulation index and the standardized conveying efficiency index, respectively. w 1 +w 2 = 1.

[0070] In the above steps, when the wear index R3 is introduced, R3 is added to the comprehensive evaluation model as a constraint or penalty term.

[0071] Step 5: Given the cutterhead rotation speed and feed speed, using the short helix rotation speed as the optimization variable, within the allowable range of the short helix rotation speed, calculate the optimal short helix rotation speed based on the comprehensive evaluation model as the matching speed of the short helix conveyor. The design variable combination and index response values ​​of this embodiment are shown in Table 1.

[0072] Table 1. Design Variable Combinations and Index Response Values

[0073]

[0074] In practical implementation, both the cutterhead rotation speed and the feed speed are controllable variables. In multiple design variable combinations, each set of controllable variables outputs a comprehensive evaluation result, and each comprehensive evaluation result corresponds to a short helix rotation speed. By limiting the short helix rotation speed within an allowable range, the controllable variables such as the cutterhead rotation speed and feed speed can be obtained in reverse from the comprehensive evaluation results. Based on the above, after simulation of multiple sets of design variable combinations, a database can be established. The database is stored in tabular form, and the elements in the table represent recommended values ​​for the short helix rotation speed, as detailed in the attached figure. Figure 4 As shown.

[0075] This application also provides a speed matching system for a short spiral conveyor in a large-diameter slurry shield tunnel, comprising a processor and a memory. Optionally, the device may further include a communication interface and a bus. The processor, communication interface, and memory can communicate with each other via the bus. The communication interface can be used for information transmission. The processor can call logical instructions in the memory to execute the speed matching method for the short spiral conveyor in a large-diameter slurry shield tunnel as described in the above embodiments.

[0076] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0077] Memory, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as the program instructions / modules corresponding to the methods in the embodiments of this disclosure. The processor executes functional applications and data processing by running the program instructions / modules stored in the memory, thereby realizing the speed matching method for the ultra-large diameter slurry shield tunneling short spiral conveyor in the above embodiments.

[0078] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory may include high-speed random access memory and may also include non-volatile memory.

[0079] This disclosure provides a computer-readable storage medium storing computer-executable instructions configured to perform the above-described method for matching the rotational speed of a short spiral conveyor in an ultra-large diameter slurry shield tunnel.

[0080] The aforementioned computer-readable storage medium may be a transient computer-readable storage medium or a non-transitory computer-readable storage medium.

[0081] The technical solutions of this disclosure can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes one or more instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in this disclosure. The aforementioned storage medium can be a non-transitory storage medium, including: a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and other media capable of storing program code; it can also be a transient storage medium.

[0082] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0083] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for matching the rotational speed of a short screw conveyor in an ultra-large diameter slurry shield tunnel, characterized in that, Includes the following steps: Step 1: Based on DEM, establish a three-dimensional solid model of the cutterhead, excavation chamber, slurry inlet pipeline and short screw conveyor, and extract the computational domain of mud fluid and rock debris particles in the three-dimensional solid model based on CFD. Step 2: Construct a coupled motion simulation model of mud fluid and rock debris particles in the computational domain, as follows: Based on CFD, the instantaneous velocity and pressure fields of each grid are output as a continuous phase of mud fluid; Based on DEM, the position, velocity, and stress state of each rock slag particle are output as a discrete particle group, and the weight of the rock slag particles discharged from the slag discharge port of the short screw conveyor is calculated. Perform grid-particle space mapping and time step synchronization, and interpolate the instantaneous velocity field and pressure field in the CFD computational domain to the current position of each rock fragment particle under the synchronized time step; Step 3: Using the cutter head rotation speed, propulsion speed, and short helix rotation speed as design variables, generate several sets of design variable combinations and run the coupled motion simulation model group by group to obtain the flow field results and particle migration results of the short helix conveyor during the conveying stage. Step 4: Define the slag accumulation index to characterize the amount of rock debris particles in the excavation chamber, and define the conveying efficiency index to characterize the slag discharge capacity of the short screw conveyor; based on the coupled motion simulation results of Step 3, calculate the slag accumulation and conveying efficiency corresponding to each combination of design variables; based on the calculation results of slag accumulation and conveying efficiency, fit the slag accumulation response model and the conveying efficiency response model respectively, and after standardization, construct a comprehensive evaluation model; Step 5: Given the cutter head speed and the feed speed, with the short helix speed as the optimization variable, within the allowable range of the short helix speed, calculate the optimal short helix speed based on the comprehensive evaluation model and use it as the matching speed of the short helix conveyor.

2. The method for matching the rotational speed of a short spiral conveyor in a large-diameter slurry shield tunnel as described in claim 1, characterized in that, In the solid model, the cutterhead and short spiral conveyor are set as rotating bodies, and the short spiral conveyor is set with a short spiral boundary; the slurry inlet pipe is set as a velocity inlet or a mass inlet; the slag discharge port of the short spiral conveyor is set as a pressure outlet; and the excavation chamber and the equipment wall are set with a non-slip boundary.

3. The method for matching the rotational speed of a short spiral conveyor in a large-diameter slurry shield tunnel as described in claim 2, characterized in that, In CFD, the mud fluid, which is a continuous phase, is solved based on the mass conservation equation and the momentum conservation equation. In the DEM, the position, velocity, and stress state of each particle are solved based on the translational and rotational control equations of the rock debris particles.

4. The method for matching the rotational speed of a short spiral conveyor in a large-diameter slurry shield tunnel as described in claim 3, characterized in that, In step three, the design variables also include mud density, rheological parameters, and rock cutting particle size distribution.

5. The method for matching the rotational speed of a short spiral conveyor in a large-diameter slurry shield tunnel as described in claim 4, characterized in that, In step four, the slag accumulation index is defined as the time average of the rock debris mass in the excavation chamber during the stabilization phase; the stabilization phase is defined based on the simulation time. The conveying efficiency index is defined as the ratio of the actual slag discharge mass flow rate to the theoretical maximum conveying capacity.

6. The method for matching the rotational speed of a short spiral conveyor in a large-diameter slurry shield tunnel as described in claim 4, characterized in that, In step four, a wear index is defined as a constraint on the working time of the short screw conveyor; The wear index is defined as the time average of the erosion energy, contact work, or wear rate on the blade surface of the short screw conveyor.

7. A speed matching system for a short spiral conveyor in an ultra-large diameter slurry shield tunnel, comprising a processor and a memory storing program instructions, characterized in that, The processor is configured to execute, when running the program instructions, the speed matching method for a short spiral conveyor for an ultra-large diameter slurry shield tunnel as described in any one of claims 1-6.

8. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the method as described in any one of claims 1-6 above.

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