A method for optimizing the design of a multi-stage tail brush structure for tunnel boring machines

Abstract

This invention discloses a method for optimizing the design of a multi-stage tail brush structure in shield tunneling, relating to the field of shield tunneling engineering technology. The method includes: calculating the target number of tail brush rings in the shield tail sealing system based on the highest water pressure experienced by the shield machine during construction and the pressure-bearing capacity of the shield tail sealing unit; classifying all tail brush functions based on the actual working environment, boundary conditions, and target effects of the shield tail sealing system to obtain different types of functional tail brushes; introducing differentiated tail brush structure design strategies based on the different types of functional tail brushes, and adjusting the composition and structural dimensional parameters of each type of functional tail brush accordingly; and calculating the target interval between adjacent ring tail brushes based on the preset shield tail gap and the structural dimensional parameters of each ring of functional tail brushes. This invention, by combining functional hierarchical division and differentiated structural design, breaks through the limitations of traditional homogeneous tail brush design, allowing each ring of tail brushes to form a collaborative and efficient multi-level protection system according to its functional positioning.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel engineering technology, and in particular to an optimized design method for a multi-stage tail brush structure of a shield tunnel. Background Technology

[0002] The assembly of the shield tunnel lining is carried out under the protection of the shield machine shell. There is a gap between the shield machine shell and the shield tunnel. In order to prevent soil water and synchronous grouting slurry from entering the shield machine, a shield tail sealing system consisting of multi-ring tail brushes and tail grease chambers is set between the shield machine shell and the shield tunnel lining.

[0003] The existing tail brush structure in shield tail sealing systems is basically uniform, generally consisting of 2-4 rings of wire brushes + 1 ring of steel plate brush. The wire brushes in different rings are essentially the same, lacking differentiated design and failing to maximize the water pressure resistance of the tail sealing system. Furthermore, during actual shield tunneling, the tail brush inevitably suffers damage due to friction with the tunnel segments, repeated compression, adhesion of grout from behind the tunnel wall, and pressure differences in the tail sealing grease. This leads to a decline in tail sealing performance, requiring timely replacement to prevent disasters such as soil and water inflow into the tunnel. Replacing the tail brush during shield construction often requires stopping tunneling and thoroughly reinforcing the surrounding strata before replacement. If the strata reinforcement is ineffective, it can easily cause external soil and water to inflow into the tunnel, resulting in catastrophic consequences. Moreover, strata reinforcement and tail brush replacement also delay the overall tunnel construction schedule and incur high construction costs.

[0004] Therefore, the tail brush structure should be optimized by taking into account the functional differences of the tail brush at different locations. This will improve the overall ability of the tail brush system to resist external soil and water pressure, enhance its durability, extend the service life of the tail brush, reduce the need for tail brush replacement, save construction costs, and reduce construction risks. Summary of the Invention

[0005] Therefore, it is necessary to provide an optimized design method for the multi-stage tail brush structure of a tunnel boring machine to address the aforementioned technical problems.

[0006] In a first aspect, the present invention provides a method for optimizing the design of a multi-stage tail brush structure for a tunnel boring machine, comprising:

[0007] Based on the highest water pressure and the pressure bearing capacity of the tail seal unit during tunnel boring machine construction, the target tail brush ring number of the tail seal system is calculated, and the corresponding number of tail brushes are arranged longitudinally in sequence according to the target tail brush ring number to form a closed ring structure arranged along the circumferential direction.

[0008] Based on the actual working environment, boundary conditions, and target effects of the tail seal system, all tail brush functions are divided to obtain different types of functional tail brushes.

[0009] Based on different types of functional tail brushes, a differentiated tail brush structure design strategy is introduced, and the composition structure and structural size parameters of various functional tail brushes are adjusted accordingly.

[0010] Based on the preset shield tail gap and the structural dimension parameters of each ring functional tail brush, the target interval of adjacent ring tail brushes is calculated, and the closed ring structure is adjusted accordingly to achieve adaptive optimization of the multi-tail brush structure within the shield tail sealing system.

[0011] Furthermore, based on the highest water pressure experienced by the tunnel boring machine during construction and the pressure-bearing capacity of the tail seal unit, the calculation expression for the target number of tail brush rings of the tail seal system is as follows:

[0012] ;

[0013] In the formula, n is the target tail brush ring number of the shield tail sealing system; P max η is the maximum water pressure that the tunnel boring machine can withstand during construction; η is the pressure amplification factor; p0 is the pressure bearing capacity of the tail seal unit; [] is the rounding symbol.

[0014] Furthermore, based on the actual working environment, boundary conditions, and target effects of the tail seal system, all tail brush functions are categorized, resulting in different types of functional tail brushes, including:

[0015] The tail brush of the shield tail sealing system, which is in direct contact with the soil and water outside the tunnel and the synchronous grouting, is set as the first-level barrier tail brush to prevent the sealing grease cavity from exchanging substances with the soil and water outside the tunnel, the synchronous grouting body and the mud.

[0016] The first tail brush adjacent to the inner side of the primary blocking tail brush is set as a redundant blocking pressure regulating tail brush to help block the intrusion of solid and liquid substances into the sealed grease cavity.

[0017] All tail brushes between the innermost tail brush and the redundant blocking pressure regulating tail brush in the shield tail sealing system are set as pressure transmission tail brushes to achieve stepwise adjustment of the pressure in the multi-ring sealing grease chamber.

[0018] The innermost tail brush of the shield tail sealing system is set as the final anti-overflow tail brush, serving as the final boundary of the shield tail sealing system that bears the external pressure transmission of the tunnel, in order to prevent the sealant from seeping into the tunnel and causing loss.

[0019] Furthermore, based on different types of functional tail brushes, differentiated tail brush structural design strategies are introduced, and the composition and structural dimensional parameters of various functional tail brushes are adjusted accordingly, including:

[0020] For the first-stage barrier tail brush, a wire brush structure that reduces slurry adhesion is adopted, and a test on the slurry adhesion and sealing performance of the tail brush is designed to optimize the wire parameters of the first-stage barrier tail brush.

[0021] For redundant blocking pressure regulating tail brushes, an inner and outer layered steel wire brush structure is adopted to form the ability to resist caking and restrict the flow of grease in the direction of soil and water pressure.

[0022] For the pressure transmission tail brush, galvanized steel wire with bending treatment is used as the wire brush structure to play the role of the medium for the gradation transmission of grease and to restrict the flow of sealing grease.

[0023] For the end anti-overflow tail brush, the structural dimensions of the front outer protection plate, the middle protection plate and the rear clamping plate were optimized to improve the rigidity of the end anti-overflow tail brush.

[0024] Furthermore, for the primary barrier tail brush, a wire brush structure that reduces slurry adhesion is adopted, and a slurry adhesion and sealing test of the tail brush is designed. The wire parameters of the primary barrier tail brush are optimized, including:

[0025] Straight steel wires that have not undergone bending are used as wire brushes and form a tail brush ring to reduce the adhesion of slurry to the first-stage barrier tail brush.

[0026] Design an adhesion test between the tail brush and the grout behind the wall, and measure the mass increase of multiple tail brushes after the grout adheres to them in order to compare the adhesion ability of the grout.

[0027] Design a sealing test for the tail brush after slurry adhesion, compare the water pressure resistance of different tail brush parameters after slurry adhesion, and compare the water pressure resistance loss ratio with the initial state.

[0028] Based on the test results of the adhesion test between the tail brush and the grout behind the wall, and the sealing test of the tail brush after grout adhesion, the wire parameters of the primary barrier tail brush were optimized.

[0029] Furthermore, an adhesion test was designed between the tail brush and the grout behind the wall. Multiple sets of tail brushes were measured sequentially after the grout adhered to them to compare the grout adhesion capabilities.

[0030] The mass of a single primary barrier tail brush in the initial state was measured, and the primary barrier tail brush was immersed in the cement slurry after mixing. The root of the primary barrier tail brush was placed in the air, and the slurry level was located at the structural corner of the primary barrier tail brush.

[0031] After soaking, remove the primary barrier tail brush and let it air dry. Repeat this process several times and measure the mass increase of the primary barrier tail brush with the adhering slurry.

[0032] Furthermore, the steel wire brush structure inside the redundant blocking voltage regulating tail brush includes an outer layer made of straight steel wire and an inner layer made of bent steel wire, with the outer layer and the inner layer separated by a steel wire mesh.

[0033] Furthermore, the wire brush structure inside the pressure transmission tail brush uses bent galvanized steel wire.

[0034] Furthermore, for the end spill prevention brush, the structural dimensions of the front outer protection plate, middle protection plate, and rear clamping plate are optimized to improve the rigidity of the end spill prevention brush, including:

[0035] Double-layer steel plate material is used as the front protection plate of the end anti-overflow brush; the steel plate material is 65 manganese spring steel;

[0036] A steel plate of preset thickness is used as the middle protection plate of the end anti-overflow tail brush; the length of the middle protection plate is the average of the lengths of the front protection plate and the rear clamping plate.

[0037] Furthermore, based on the preset shield tail gap and the structural dimension parameters of each ring's functional tail brush, the calculation expression for the target interval of adjacent ring tail brushes is as follows:

[0038] ;

[0039] In the formula, L c L1 is the target spacing between adjacent ring tail brushes; L2 is the length of the rear clamping plate; H is the structural thickness of the tail brush mounting end; L0 is the distance from the end of the tail brush mounting end to the end of the rear clamping plate; ΔL is the length of the shield tail brush bristles extending beyond the rear clamping plate; l f The redundant value of the spacing length is set to account for the flow of grease in the grease chamber.

[0040] Secondly, the present invention also provides a shield tunneling multi-stage tail brush structure optimization design system, the system comprising:

[0041] The preparation module is used to calculate the target number of tail brush rings of the tail sealing system based on the highest water pressure and the pressure bearing capacity of the tail sealing unit during the tunnel boring machine construction, and to arrange the corresponding number of tail brushes longitudinally in sequence according to the target number of tail brush rings to form a closed ring structure arranged along the circumferential direction.

[0042] The tail brush classification module is used to classify all tail brush functions based on the actual working environment, boundary conditions and target effects of the shield tail sealing system, resulting in different types of functional tail brushes.

[0043] The differential optimization module is used to introduce differentiated tail brush structure design strategies based on different types of functional tail brushes, and adjust the composition structure and structural size parameters of various functional tail brushes accordingly.

[0044] The adaptive adjustment module is used to calculate the target interval of adjacent ring tail brushes based on the preset shield tail gap and the structural size parameters of each ring functional tail brush, and to make corresponding adjustments to the closed ring structure to achieve adaptive optimization of the multi-tail brush structure in the shield tail sealing system.

[0045] The beneficial effects of this invention are as follows: By quantitatively calculating and precisely matching the number of tail brush rings with the pressure requirements of construction, and combining functional layering and differentiated structural design, it breaks through the limitations of traditional homogeneous tail brush design, allowing each tail brush ring to form a collaborative and efficient multi-level protection system based on its functional positioning of blocking, pressure regulation, conduction, and overflow prevention; at the same time, it optimizes the tail brush steel wire structure and protective plate configuration to effectively improve the tail brush's resistance to slurry adhesion, anti-caking, wear resistance, and structural rigidity; and by checking and adjusting the spacing between tail brush rings, it ensures smooth flow of sealing grease and stable pressure transmission, ultimately significantly extending the overall service life of the tail brush, reducing the frequency of tail brush replacement, avoiding construction safety risks related to brush replacement, saving construction time and costs, and comprehensively improving the sealing reliability and service stability of the shield tail sealing system. Attached Figure Description

[0046] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0047] Figure 1 This is a flowchart of a shield tunneling multi-stage tail brush structure optimization design method according to an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the shield tail brush structure according to an embodiment of the present invention;

[0049] Figure 3 The theoretical spacing L between adjacent shield tail brushes according to an embodiment of the present invention c Schematic diagram;

[0050] Figure 4 This is a schematic diagram of the shield tail sealing system structure according to an embodiment of the present invention (5-ring tail brush, i.e., n=5).

[0051] Figure 5 This is a schematic diagram of tail brush immersion in a tail brush slurry adhesion test according to an embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram illustrating the functional division and optimization approach of the tail brush according to an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0054] Please see Figure 1 This paper provides an optimized design method for a multi-stage tail brush structure of a tunnel boring machine, including:

[0055] S1. Based on the highest water pressure borne by the tunnel boring machine during construction and the pressure bearing capacity of the tail sealing unit, calculate the target number of tail brush rings of the tail sealing system, and arrange the corresponding number of tail brushes longitudinally in sequence according to the target number of tail brush rings to form a closed ring structure arranged along the circumferential direction.

[0056] In the description of this invention, based on the highest water pressure borne by the tunnel boring machine during construction and the pressure-bearing capacity of the tail seal unit, the calculation expression for the target number of tail brush rings of the tail seal system is as follows:

[0057] ;

[0058] In the formula, n is the target tail brush ring number of the shield tail sealing system; P max η is the maximum water pressure that the tunnel boring machine can withstand during construction; η is the pressure amplification factor, with a value range of 1 to 1.1; p0 is the pressure bearing capacity of the tail seal unit; [] is the rounding symbol.

[0059] Calculating the target tail brush ring number can provide effective guidance for the structural design of the tail sealing system during the production and remanufacturing stages of tunnel boring machines. This can avoid the risk of soil and water flowing into the tunnel due to insufficient pressure bearing capacity caused by insufficient tail brush ring number due to blind design of the tail sealing system structure, or the waste of tail brush and tail grease material resources due to excessive tail brush ring number.

[0060] S2. Based on the actual working environment, boundary conditions and target effects of the tail seal system, all tail brush functions are divided to obtain different types of functional tail brushes.

[0061] Among them, such as Figure 4 and Figure 6 As shown, the present invention first defines and divides the functions of the multi-ring tail brush of the shield tail sealing system. Specifically, the shield tail sealing system is composed of n ring tail brushes arranged longitudinally. Each single ring tail brush is a closed ring structure composed of a group of tail brushes arranged closely in the circumferential direction. The n ring tail brushes form an n-1 ring sealing cavity at the shield tail. During the tunneling of the shield machine, the sealing cavity is filled with pressurized grease. The sealing grease cavity (or grease cavity) and the multi-ring tail brushes together constitute the shield tail sealing system.

[0062] Based on the actual working environment, boundary conditions, and desired effects of the shield tail sealing system, the functions of all n-ring tail brushes in the shield tail sealing system are divided. The first ring tail brush refers to the tail brush ring closest to the shield machine cutterhead, and the nth ring tail brush refers to the tail brush ring that directly contacts the soil and water outside the tunnel or the synchronous grouting body.

[0063] In the description of this invention, based on the actual working environment, boundary conditions, and target effects of the tail seal system, all tail brush functions are divided, resulting in different types of functional tail brushes including:

[0064] S21. The tail brush of the shield tail sealing system, which is in direct contact with the soil and water outside the tunnel and the synchronous grouting, is set as the first-level barrier tail brush to prevent the sealing grease cavity from exchanging substances with the soil and water outside the tunnel, the synchronous grouting body and the mud.

[0065] Specifically, the main function of the nth ring tail brush (first-level barrier tail brush) is to act as a tail brush ring that is in direct contact with the soil and water outside the tunnel and the synchronous grouting body, and to block the material exchange between the sealing grease cavity and the soil, water outside the tunnel, the synchronous grouting body and the mud.

[0066] S22. Set the first tail brush adjacent to the inner side of the primary blocking tail brush as a redundant blocking pressure regulating tail brush to assist in blocking the intrusion of solid and liquid substances into the sealed grease cavity.

[0067] Specifically, the main function of the (n-1)th ring tail brush (redundant blocking and pressure regulating tail brush) is to assist in blocking the continued intrusion of solid and liquid substances into the grease cavity when the nth ring tail brush fails to completely block the material exchange between the sealing grease cavity and the external soil, water, grout, and mud. At the same time, due to the grease pressure on both sides, it works together with the 2nd to (n-2)th ring tail brushes to perform the function of tiered distribution of grease pressure in the sealing cavity, that is, to a certain extent restricting the flow of grease between different grease cavities, thereby serving as a medium for the tiered transmission of grease pressure.

[0068] S23. Set all tail brushes between the innermost tail brush and the redundant blocking pressure regulating tail brush in the shield tail sealing system as pressure transmission tail brushes to achieve stepwise adjustment of pressure in the multi-ring sealing grease chamber.

[0069] Specifically, the tail brushes (pressure transmission tail brushes) of the 2nd to n-2nd rings constitute the dividing boundary of the multi-ring grease sealing cavity. Their main function is to realize the stepwise distribution of grease pressure in the multi-ring sealing cavity, play the role of the medium for stepwise transmission of grease pressure, and at the same time, they can serve as a backup material exchange barrier in dangerous working conditions.

[0070] S24. Set the innermost tail brush of the shield tail sealing system as the end anti-overflow tail brush, which serves as the final bearing boundary of the shield tail sealing system for transmitting external pressure to the tunnel, so as to prevent the sealant from seeping into the tunnel and being lost.

[0071] Specifically, the first ring tail brush (end anti-overflow tail brush) needs to withstand the pressure of sealing grease on one side and atmospheric pressure on the other side. That is, the first ring tail brush is the final boundary for the transmission of external pressure in the tunnel and needs to effectively prevent the sealing grease from seeping into the tunnel and causing loss.

[0072] S3. Based on different types of functional tail brushes, a differentiated tail brush structure design strategy is introduced, and the composition structure and structural size parameters of various functional tail brushes are adjusted accordingly.

[0073] In the description of this invention, based on different types of functional tail brushes, a differentiated tail brush structure design strategy is introduced, and the composition structure and structural dimensional parameters of various functional tail brushes are adjusted accordingly, including:

[0074] S31. For the first-stage barrier tail brush, a wire brush structure with reduced slurry adhesion is adopted, and a test on the slurry adhesion and sealing performance of the tail brush is designed to optimize the wire parameters of the first-stage barrier tail brush.

[0075] Among them, the tail brush structure functional optimization design method. Based on the above-mentioned clear division of the main functions of each ring tail brush, this invention proposes a corresponding tail brush structure design method.

[0076] For the tail brush of the nth ring shield, the focus is on its ability to prevent the exchange of substances between the grease cavity and the external soil, water, grout and mud, as well as its ability to resist the adhesion of cement slurry and prevent the tail brush from hardening and deteriorating.

[0077] Therefore, the optimization design idea of ​​the nth ring shield tail brush is as follows: (1) Change the currently commonly used steel plate brush scheme and use steel wire brush to form the tail brush ring to improve the ability to block material exchange; (2) Increase the diameter of the steel wire of the steel wire brush. It is recommended to use straight steel wire and not to use bending treatment to reduce the specific surface area of ​​the steel wire, thereby reducing the adhesion of slurry to the shield tail brush wire (currently, galvanized steel wire with a wire diameter of φ0.3mm and special bending treatment is often used in actual projects); (3) Design and carry out the shield tail brush-wall back grout adhesion test and the tail brush sealing performance test after slurry adhesion, and optimize the tail brush wire parameters.

[0078] In the description of this invention, for the first-stage barrier tail brush, a wire brush structure that reduces slurry adhesion is adopted, and a slurry adhesion and sealing test of the tail brush is designed. The optimization of the wire parameters of the first-stage barrier tail brush includes:

[0079] S311. Straight steel wires that have not undergone bending treatment are used as wire brushes and form a tail brush ring to reduce the adhesion of slurry to the first-stage barrier tail brush.

[0080] S312. Design an adhesion test between the tail brush and the grout behind the wall, and measure the mass increase of multiple tail brushes after the grout adheres to them in sequence to compare the adhesion ability of the grout.

[0081] In the description of this invention, an adhesion test was designed between the tail brush and the grout behind the wall. Multiple sets of tail brushes were sequentially measured for mass increase after grout adhesion to compare the grout adhesion ability. This included:

[0082] S3121. Measure the mass of a single primary barrier tail brush in the initial state, and immerse the primary barrier tail brush in cement slurry within 3 minutes of mixing, with each immersion lasting 3 minutes. The root of the primary barrier tail brush should be exposed to air, and the slurry level should be located at the structural corner of the primary barrier tail brush. The positional relationship between the slurry level and the primary barrier tail brush is as follows: Figure 5 As shown.

[0083] S3122. After soaking, remove the primary barrier tail brush and let it air dry for 1 minute. Repeat this process three times and measure the mass increase of the primary barrier tail brush with the adhered slurry. S313. Design a sealing test for the tail brush after slurry adhesion, compare the water pressure resistance of different tail brush parameters after slurry adhesion, and compare the water pressure resistance loss ratio with the initial state.

[0084] S314. Based on the test results of the adhesion test between the tail brush and the grout behind the wall, and the sealing test of the tail brush after grout adhesion, the wire parameters of the primary barrier tail brush are optimized.

[0085] Specifically, the tail brush with less increase in adhesion mass and less loss in sealing performance is selected as the optimized first-level barrier tail brush (nth ring tail brush) to reduce the tail brush caking effect caused by slurry adhesion during actual construction, thereby reducing the occurrence of situations that reduce the sealing performance of the tail brush structure, such as loss of tail brush elasticity and brush bristle breakage and detachment caused by the caking effect.

[0086] S32. For redundant blocking pressure regulating tail brushes, an inner and outer layered steel wire brush structure is adopted to form the ability to resist caking and restrict the flow of grease in the direction of soil and water pressure.

[0087] In the description of this invention, the steel wire brush structure inside the redundant blocking voltage regulating tail brush includes an outer layer made of straight steel wire and an inner layer made of bent steel wire, and the outer layer and the inner layer are separated by a steel wire mesh.

[0088] Specifically, for the (n-1)th ring tail brush, since it needs to both help prevent further intrusion of external substances and function as a tiered regulator of grease pressure in the sealing cavity, it must possess both the ability to resist caking and the ability to restrict the flow of grease towards the direction of soil-water pressure. Therefore, a wire brush structure is adopted, with the wire divided into two layers. The outer layer uses straight wire to prevent intruding slurry from further caking the tail brush, while the inner layer uses bent wire, mainly to restrict the flow of grease between different grease cavities and to act as a medium for grease pressure transmission. The inner and outer layers are separated by a 40-mesh, non-woven wire mesh.

[0089] S33. For the pressure transmission tail brush, galvanized steel wire that has been bent is used as the wire brush structure to enable the grease to play a tiered transmission medium and to restrict the flow of sealing grease.

[0090] In the description of this invention, the wire brush structure inside the pressure transmission tail brush is made of bent galvanized steel wire, and the wire diameter of the galvanized steel wire is 0.3 mm.

[0091] Specifically, for the tail brushes of rings 2 to 1-n, their main function is to achieve tiered distribution of grease pressure in the multi-ring sealing cavity, act as a medium for tiered grease pressure transmission, and restrict the flow of sealing grease. Therefore, they still adopt the traditional wire brush tail brush structure, with brush bristles made of galvanized steel wire with a diameter of φ0.3mm that has undergone special bending treatment.

[0092] S34. For the end anti-overflow tail brush, the structural dimension parameters of the front outer protection plate, the middle protection plate and the rear clamping plate are optimized respectively to improve the rigidity of the end anti-overflow tail brush.

[0093] In the description of this invention, for the end anti-overflow tail brush, the structural dimensional parameters of the outer front protection plate, the middle protection plate, and the rear clamping plate are optimized respectively to improve the rigidity of the end anti-overflow tail brush, including:

[0094] S341. A double-layer steel plate is used as the front protection plate for the end anti-overflow tail brush; the steel plate material is 65 manganese spring steel.

[0095] S342. A steel plate of preset thickness is used as the middle protection plate of the end anti-overflow tail brush; wherein, the length of the middle protection plate is the average of the lengths of the front protection plate and the rear clamping plate.

[0096] Specifically, the first ring tail brush serves as the final boundary for external pressure transmission within the tunnel. It bears the pressure of sealing grease on one side and atmospheric pressure on the other, often experiencing the largest pressure difference among all tail brush rings. Under the significant pressure difference and the combined effects of segment compression and friction, the first ring tail brush suffers severe wear and deterioration in actual engineering projects. The wear and deterioration process primarily involves the initial breakage and detachment of the front protective plate. Subsequently, the brush bristles, lacking the protection and restraint of the front protective plate, undergo accelerated wear and curling deformation, leading to a severe decline in the tail brush's sealing performance. Grease continuously flows into the tunnel through the first ring tail brush, causing grease pressure loss and reducing the overall sealing performance of the sealing system.

[0097] To address the stress and wear degradation characteristics of the first ring tail brush, the following design optimizations are made: Since the front protective plate of the first ring tail brush often wears off first, further inducing continuous deterioration of sealing performance, the durability and fatigue resistance of the front protective plate are enhanced. In existing designs, the outer front protective plate is often made of a single layer of 0.6mm 65Mn steel plate (65 manganese spring steel), which is optimized to a double layer of 1.0mm 65Mn steel plate. In existing designs, the length of the middle protective plate is not clearly defined and is often short, only serving an auxiliary clamping function. This is optimized to use a 0.6mm thick 65Mn steel plate, with a length equal to the average length of the front protective plate and the rear clamping plate, improving the tail brush rigidity and enabling it to function as a backup protector for the tail brush bristles.

[0098] This design scheme can guarantee the theoretical pressure bearing capacity of the tail shield sealing system, and ensure that the tail shield brush can still play a sealing role during the shield tunneling process, and can also ensure that the grease chamber can still have the ability to transmit oil pressure even under the most unfavorable gap.

[0099] S4. Based on the preset shield tail gap and the structural dimension parameters of each ring functional tail brush, calculate the target interval of adjacent ring tail brushes, and make corresponding adjustments to the closed ring structure to achieve adaptive optimization of the multi-tail brush structure in the shield tail sealing system.

[0100] In the description of this invention, as Figure 3 As shown, based on the preset shield tail gap and the structural dimension parameters of each ring's functional tail brush, the calculation expression for the target interval between adjacent ring tail brushes is as follows:

[0101] ;

[0102] This formula ensures that, under the condition of minimum shield tail clearance, the bristles of the preceding ring tail brush, even under pressure deformation, will not come into contact with the following ring tail brush; furthermore, it ensures that, under the condition of minimum shield tail clearance, the grease chamber can still allow for internal flow and fluid pressure transmission despite the confined space and boundary adhesion, thus guaranteeing sealing. In the formula, L... cL1 represents the theoretical interval between adjacent shield tail brushes, i.e., the distance from the end point of the previous shield tail brush to the corresponding end point of the next shield tail brush; L2 represents the length of the rear clamping plate; H represents the structural thickness of the shield tail brush mounting end; L0 represents the distance from the end of the shield tail brush mounting end to the end of the rear clamping plate; ΔL represents the length of the shield tail brush bristles extending beyond the rear clamping plate, typically taken as 15~25mm; f The redundant value of the spacing length set to account for the flow of grease in the grease chamber can be 50~100mm.

[0103] Among them, the tail brush structure is as follows Figure 2 As shown, the formula for determining the length L2 of the shield tail brush clamping plate is as follows:

[0104] ;

[0105] This formula primarily serves to ensure that the tail brush undergoes plastic loss during shield tunneling and that the rear clamping plate can still maintain its function of keeping the brush bristles close to the tunnel lining segments after fluctuations in the tail clearance caused by tunneling posture adjustment. In the formula, L2 is the length of the rear clamping plate; α0 is the initial angle of the rear clamping plate, typically taken as 50°±5°; Δα is the amount of plastic loss of the angle of the tail brush protection plate under repeated compression by the tail tunnel lining segments, a value taken empirically, with a maximum of 0.6α0; δ0 is the initial tail clearance, which must meet the requirements of shield tunneling posture adjustment during design. For large-diameter shields (diameter over 12m), this value is generally (85~105mm), while for general subway shields it is (55~75mm); Δδ is the tail clearance fluctuation value during construction, which can generally reach 0.5δ0 for large-diameter shields.

[0106] Furthermore, the values ​​of the limiting parameters in the formula for the length L2 of the rear clamping plate are the same on a single tunnel boring machine, so the length of the rear clamping plate for each ring tail brush is the same.

[0107] In another embodiment, the present invention also provides a shield tunneling multi-stage tail brush structure optimization design system, the system comprising:

[0108] The preparation module is used to calculate the target number of tail brush rings of the tail sealing system based on the highest water pressure and the pressure bearing capacity of the tail sealing unit during the tunnel boring machine construction, and to arrange the corresponding number of tail brushes longitudinally in sequence according to the target number of tail brush rings to form a closed ring structure arranged along the circumferential direction.

[0109] The tail brush classification module is used to classify all tail brush functions based on the actual working environment, boundary conditions and target effects of the shield tail sealing system, resulting in different types of functional tail brushes.

[0110] The differential optimization module is used to introduce differentiated tail brush structure design strategies based on different types of functional tail brushes, and adjust the composition structure and structural size parameters of various functional tail brushes accordingly.

[0111] The adaptive adjustment module is used to calculate the target interval of adjacent ring tail brushes based on the preset shield tail gap and the structural size parameters of each ring functional tail brush, and to make corresponding adjustments to the closed ring structure to achieve adaptive optimization of the multi-tail brush structure in the shield tail sealing system.

[0112] In summary, by utilizing the technical solution described above, quantitative calculations precisely match the number of tail brush rings with the pressure requirements of construction. Combined with functional layering and differentiated structural design, this breaks through the limitations of traditional homogeneous tail brush design, allowing each tail brush ring to form a collaborative and efficient multi-level protection system based on its functional positioning of blocking, pressure regulation, conduction, and overflow prevention. Simultaneously, the tail brush wire structure and protective plate configuration are specifically optimized to effectively improve the tail brush's resistance to slurry adhesion, caking, wear, and structural rigidity. Furthermore, the adjustment of the spacing between tail brush rings ensures smooth flow of sealing grease and stable pressure transmission, ultimately significantly extending the overall service life of the tail brush, reducing the frequency of tail brush replacement, avoiding construction safety risks associated with brush replacement, saving construction time and costs, and comprehensively improving the sealing reliability and service stability of the shield tail sealing system.

[0113] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

Claims

1. A method for optimizing the design of a multi-stage tail brush structure for a tunnel boring machine, characterized in that, include: Based on the highest water pressure and the pressure bearing capacity of the tail seal unit during tunnel boring machine construction, the target tail brush ring number of the tail seal system is calculated, and the corresponding number of tail brushes are arranged longitudinally in sequence according to the target tail brush ring number to form a closed ring structure arranged along the circumferential direction. Based on the actual working environment, boundary conditions, and target effects of the tail seal system, all tail brush functions are divided to obtain different types of functional tail brushes. Based on different types of functional tail brushes, a differentiated tail brush structure design strategy is introduced, and the composition structure and structural size parameters of various functional tail brushes are adjusted accordingly. Based on the preset shield tail gap and the structural dimension parameters of each ring functional tail brush, the target interval of adjacent ring tail brushes is calculated, and the closed ring structure is adjusted accordingly to achieve adaptive optimization of the multi-tail brush structure within the shield tail sealing system.

2. The shield tunneling multi-stage tail brush structure optimization design method according to claim 1, characterized in that, The calculation expression for the target number of tail brush rings of the shield tail sealing system, based on the highest water pressure borne by the tunnel boring machine during construction and the pressure-bearing capacity of the tail sealing unit, is as follows: ； In the formula, n is the target tail brush ring number of the shield tail sealing system; P max η is the maximum water pressure that the tunnel boring machine can withstand during construction; η is the pressure amplification factor; p0 is the pressure bearing capacity of the tail seal unit; [] is the rounding symbol.

3. The shield tunneling multi-stage tail brush structure optimization design method according to claim 1, characterized in that, Based on the actual working environment, boundary conditions, and target effects of the tail seal system, all tail brush functions are categorized, resulting in different types of functional tail brushes, including: The tail brush of the shield tail sealing system, which is in direct contact with the soil and water outside the tunnel and the synchronous grouting, is set as the first-level barrier tail brush to prevent the sealing grease cavity from exchanging substances with the soil and water outside the tunnel, the synchronous grouting body and the mud. The first tail brush adjacent to the inner side of the primary blocking tail brush is set as a redundant blocking pressure regulating tail brush to help block the intrusion of solid and liquid substances into the sealed grease cavity. All tail brushes between the innermost tail brush and the redundant blocking pressure regulating tail brush in the shield tail sealing system are set as pressure transmission tail brushes to achieve stepwise adjustment of the pressure in the multi-ring sealing grease chamber. The innermost tail brush of the shield tail sealing system is set as the final anti-overflow tail brush, serving as the final boundary of the shield tail sealing system that bears the external pressure transmission of the tunnel, in order to prevent the sealant from seeping into the tunnel and causing loss.

4. The shield tunneling multi-stage tail brush structure optimization design method according to claim 3, characterized in that, The aforementioned differentiated tail brush structural design strategy, based on different types of functional tail brushes, involves adjusting the composition and dimensional parameters of various functional tail brushes accordingly, including: For the first-stage barrier tail brush, a wire brush structure that reduces slurry adhesion is adopted, and a test on the slurry adhesion and sealing performance of the tail brush is designed to optimize the wire parameters of the first-stage barrier tail brush. For redundant blocking pressure regulating tail brushes, an inner and outer layered steel wire brush structure is adopted to form the ability to resist caking and restrict the flow of grease in the direction of soil and water pressure. For the pressure transmission tail brush, galvanized steel wire with bending treatment is used as the wire brush structure to play the role of the medium for the gradation transmission of grease and to restrict the flow of sealing grease. For the end anti-overflow tail brush, the structural dimensions of the front outer protection plate, the middle protection plate and the rear clamping plate were optimized to improve the rigidity of the end anti-overflow tail brush.

5. The shield tunneling multi-stage tail brush structure optimization design method according to claim 4, characterized in that, For the primary barrier tail brush, a wire brush structure that reduces slurry adhesion is adopted, and a slurry adhesion and sealing test of the tail brush is designed. The optimization of the wire parameters of the primary barrier tail brush includes: Straight steel wires that have not undergone bending are used as wire brushes and form a tail brush ring to reduce the adhesion of slurry to the first-stage barrier tail brush. Design an adhesion test between the tail brush and the grout behind the wall, and measure the mass increase of multiple tail brushes after the grout adheres to them in order to compare the adhesion ability of the grout. Design a sealing test for the tail brush after slurry adhesion, compare the water pressure resistance of different tail brush parameters after slurry adhesion, and compare the water pressure resistance loss ratio with the initial state. Based on the test results of the adhesion test between the tail brush and the grout behind the wall, and the sealing test of the tail brush after grout adhesion, the wire parameters of the primary barrier tail brush were optimized.

6. The shield tunneling multi-stage tail brush structure optimization design method according to claim 5, characterized in that, The designed tail brush and the adhesion test of the grout behind the wall were conducted by sequentially measuring the mass increase of multiple tail brushes after the grout adhered, in order to compare the grout adhesion ability. The mass of a single primary barrier tail brush in the initial state was measured, and the primary barrier tail brush was immersed in the cement slurry after mixing. The root of the primary barrier tail brush was placed in the air, and the slurry level was located at the structural corner of the primary barrier tail brush. After soaking, the primary barrier tail brush was removed and allowed to air dry. This process was repeated several times, and the mass increase of the primary barrier tail brush with the adhering slurry was measured.

7. The shield tunneling multi-stage tail brush structure optimization design method according to claim 4, characterized in that, The redundant blocking voltage regulating tail brush internal wire brush structure includes an outer layer made of straight steel wire and an inner layer made of bent steel wire, with the outer layer and inner layer separated by a wire mesh.

8. The shield tunneling multi-stage tail brush structure optimization design method according to claim 4, characterized in that, The wire brush structure inside the pressure transmission tail brush is made of bent galvanized steel wire.

9. The shield tunneling multi-stage tail brush structure optimization design method according to claim 4, characterized in that, The optimization of the structural dimensions of the front outer protective plate, middle protective plate, and rear clamping plate for the end anti-overflow brush to improve its rigidity includes: Double-layer steel plate material is used as the front protection plate of the end anti-overflow brush; the steel plate material is 65 manganese spring steel; A steel plate of preset thickness is used as the middle protective plate of the end anti-overflow tail brush; wherein, the length of the middle protective plate is the average of the lengths of the front protective plate and the rear clamping plate.

10. The method for optimizing the design of a multi-stage tail brush structure for a tunnel boring machine according to claim 1, characterized in that, The calculation expression for calculating the target interval between adjacent ring tail brushes based on the preset shield tail gap and the structural dimension parameters of each ring functional tail brush is as follows: ； In the formula, L c L1 is the target spacing between adjacent ring tail brushes; L2 is the length of the rear clamping plate; H is the structural thickness of the tail brush mounting end; L0 is the distance from the end of the tail brush mounting end to the end of the rear clamping plate; ΔL is the length of the shield tail brush bristles extending beyond the rear clamping plate; l f The redundant value of the spacing length is set to account for the flow of grease in the grease chamber.

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