CN113361039B - Section optimization method and system for sealing gasket of shield tunnel segment joint - Google Patents
Section optimization method and system for sealing gasket of shield tunnel segment joint Download PDFInfo
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Abstract
A method and a system for optimizing the section of a sealing gasket of a shield tunnel segment joint are disclosed, wherein the method comprises the following steps: establishing a 2.5D section model and a finite element model of the sealing gasket and the groove by analyzing the actual working condition; applying load to a finite element model of the sealing gasket to complete compression simulation, extracting the contact stress distribution of the surface of the sealing gasket, establishing a microscopic sealing gasket surface leakage model by adopting a conical plane contact model and a Roth model, deducing a leakage rate formula based on the leakage model, and calculating the leakage rate; and optimizing the section of the sealing gasket by taking the leakage rate and the contact stress as indexes to obtain an optimized interface model. The cross section optimization method analyzes the leakage rate of the surface of the sealing gasket from a microcosmic view, adopts a simple and practical model, and can provide cross section optimization guidance for the shield tunnel segment joint sealing gasket and other rubber sealing gaskets of the same type.
Description
Technical Field
The invention belongs to the field of shield tunnel construction, and particularly relates to a method and a system for optimizing the section of a sealing gasket of a segment joint of a shield tunnel.
Background
The shield method is a safe and rapid tunnel construction method, is widely used due to high mechanization degree and relatively small influence on the environment, and is rapidly developed in China for large-scale construction of underwater tunnels and urban subways in the 21 st century. The tunnel water proofing is a major difficulty in the tunnel construction and operation process, the seam of the shield segment is a waterproof key part, and if water seeps for a long time in the tunnel, the service function and the structural durability of the tunnel are affected, and even more, the ground surface can be settled or collapsed.
The waterproof method of the shield tunnel comprises structural self-waterproofing and other auxiliary measures, such as waterproof coating outside the segment, segment joint waterproofing, secondary lining waterproofing and the like, wherein the segment joint waterproofing is taken as a key point. Usually, the waterproof countermeasure of section of jurisdiction seam is to use sealing material, mainly sets up cyclic annular sealed pad in the sealed slot all around the section of jurisdiction, treats that the sealed pad on two sections of jurisdiction after the section of jurisdiction is assembled extrudees each other to the contact surface compressive stress comes the stagnant water.
Therefore, the sealing gasket is an important part for preventing the tunnel from being waterproofed, and the design of the cross section shape of the sealing gasket is also important. In the prior design, the waterproof performance of the sealing gasket is evaluated by only adopting the single index of the maximum pressure stress of the contact surface of the sealing gasket. Since the surface of the gasket is uneven at the microscopic level, there is always a leakage at the microscopic level, and when the leakage rate reaches a level that can be recognized by the naked eye, the gasket is considered to be out of order. The leakage rate of the sealing gasket is related to both the average contact compressive stress and the distribution of the compressive stress besides the maximum compressive stress, so that the method only adopts the maximum compressive stress as an evaluation index, is incomplete and unscientific, and needs to increase the leakage rate as the evaluation index.
Disclosure of Invention
In view of the technical defects and technical drawbacks in the prior art, embodiments of the present invention provide a method and a system for optimizing a section of a sealing gasket for a segment joint of a shield tunnel segment, which overcome the above problems or at least partially solve the above problems, and the specific scheme is as follows:
as a first aspect of the present invention, there is provided a method for optimizing a section of a shield tunnel segment joint gasket, the method comprising:
s1, establishing a 2.5D section model and a finite element model of the sealing gasket and the groove by analyzing actual working conditions;
s2, applying load to the finite element model of the sealing gasket to complete compression simulation, extracting the contact stress distribution of the surface of the sealing gasket, and calculating the maximum value, the average value and the compression force of the contact stress;
s3, establishing a microscopic lower sealing gasket surface leakage model by adopting a conical plane contact model and a Roth model, deducing a leakage rate formula based on the leakage model, and calculating the leakage rate;
and S4, optimizing the section of the sealing gasket by taking the leakage rate and the contact stress as indexes to obtain an optimized interface model.
Further, S2 specifically includes: fixing and constraining the lower groove, moving the upper hook groove up and down, applying different compressive forces to the sealing gasket to construct a compressive simulation of the sealing gasket under the finite element model, extracting the surface contact stress distribution of the sealing gasket, and acquiring the maximum value, the average value and the compressive force of the contact stress based on the surface contact stress distribution of the sealing gasket
Further, S3 specifically includes:
s31: firstly, selecting a microcosmic contact model, selecting a conical plane contact model which is more in line with the actual situation according to the observation of a surface profiler, and then selecting a Roth model as a leakage channel model, wherein the Roth model is a leakage channel model which is formed by simplifying random rough peaks by continuous identical isosceles triangles, and the model has a simple and direct structure and is convenient for calculating and analyzing the leakage situation of fluid between contact surfaces;
s32, deducing a calculation formula of the leakage rate, assuming that the liquid between the sealing gaskets is uniform Newtonian fluid, judging that the flow state is laminar flow according to the Reynolds number, and the Navier-Stoks equation of the liquid flow is as follows:
equation one:
where ρ is the fluid density; v is the velocity vector, u, v, w is the velocity component of the fluid at time t, at point (x, y, z); p is pressure; f is an external force applied to the unit volume of fluid, and if only gravity is considered, f is rho g; the constant μ is the viscosity coefficient.
The flow is simplified into one-dimensional flow, and the inertia force and the mass force in the liquid flowing process are neglected, so that the equation meets the following conditions:
v＝w＝0
fx＝fy＝fz＝0
wherein, the density rho of the fluid is constant, the fluid viscosity coefficient mu is also constant, and the Navier-Stoks equation can be simplified as follows:
equation two:
wherein u is the liquid layer flow velocity;
two successive integrations of equation two can be found:
equation three:
setting the boundary condition y to be 0 and u to be 0; substituting y as h and u as 0 into equation three can obtain velocity distribution function
Taking a infinitesimal element from the leakage channel to make its cross-sectional area be
The volumetric leak rate integrated for a single leak channel is:
equation four:
assuming that the contact length of the gasket is L, the width of the bottom side of each leakage path is
The number of leakage paths is then
The total leak rate is therefore:
equation five:
wherein h is the gap height, theta is the cone angle, and delta p is the pressure difference between the inner side and the outer side of the sealing interface; l is the length of the sealing surface; b is the seal width; μ is the viscosity coefficient of the fluid, i.e., the viscosity coefficient of water.
Further, the S4 specifically includes:
s41, evaluating the quality of the section shape of the current sealing gasket according to the leakage rate value, the average value and the maximum value of the contact stress and the compression force, observing the form change of the sealing gasket in the compression process according to the contact stress distribution rule of the groove and the surface of the sealing gasket, and obtaining a multi-parameter controlled sealing gasket section shape optimization strategy;
s42, under the constraint conditions of the maximum compression force, the maximum compression amount and the constraint range of the ratio of the section area of the sealing gasket to the area of the groove, the final section shape of the sealing gasket is selected by taking the small leakage rate, the large contact stress and the uniform form change of the sealing gasket in the compression process as the targets
Further, S41 specifically includes: according to the compression simulation result of the finite element model of S2, the average value of the contact stress is used as the load of the microscopic conical peak, the microscopic conical peak is loaded on the top surface of the conical peak in the form of uniform load, the height of the conical peak is recorded after the load is completed, the height is substituted into the leakage rate formula of S3, the leakage rate is calculated, the average value, the maximum value and the compression force of the contact stress of S2 are recorded, the deformation condition of the gasket in the compression process is observed, the displacement of each point on the contact surface of the gasket in the direction perpendicular to the contact surface is extracted, and the form change of the gasket in the compression process is quantified.
Further, S42 specifically includes: for the initial design of the section shape of the sealing gasket, the rule that the ratio A0/A1 of the section area A0 of the sealing gasket to the groove area A1 is 1-1.15 is followed, for the evaluation of the section shape of the sealing gasket, the numerical value of the compression force is considered firstly, for the section shape of which the compression force exceeds the assembling force of the pipe piece, other evaluation indexes are not considered, namely, the section shape is judged to be unqualified, and for the section shape of which the compression force is in the range of the assembling force of the pipe piece, the leakage rate, the average contact stress of the surface of the sealing gasket and the maximum stress are comprehensively considered, so that the optimal section shape of the sealing gasket is selected.
As a second aspect of the invention, a shield tunnel segment joint sealing gasket section optimization system is provided, which is characterized by comprising a model construction module, a stress calculation module, a leakage rate calculation module, a deformation variation module and an optimization module;
the model building module is used for building a 2.5D section model and a finite element model of the sealing gasket and the groove by analyzing actual working conditions;
the stress calculation module is used for applying load to the finite element model of the sealing gasket to complete compression simulation, extracting contact stress distribution on the surface of the sealing gasket and calculating the maximum value, the average value and the compression force of the contact stress;
the leakage rate calculation module is used for establishing a microscopic lower sealing gasket surface leakage model by adopting a conical plane contact model and a Roth model, deducing a leakage rate formula based on the leakage model and calculating the leakage rate;
the optimization module is used for optimizing the section of the sealing gasket by taking the leakage rate and the contact stress as indexes to obtain an optimized interface model.
Further, the leakage rate calculation module adopts a conical plane contact model and a Roth model to establish a microscopic lower sealing gasket surface leakage model, deduces a leakage rate formula based on the leakage model, and calculates the leakage rate specifically including:
firstly, selecting a microcosmic contact model, selecting a conical plane contact model which is more in line with the actual situation according to the observation of a surface profiler, and then selecting a Roth model as a leakage channel model, wherein the Roth model is a leakage channel model which is formed by simplifying random rough peaks by continuous identical isosceles triangles, and the model has a simple and direct structure and is convenient for calculating and analyzing the leakage situation of fluid between contact surfaces;
deducing a calculation formula of the leakage rate, assuming that liquid between the sealing gaskets is uniform Newtonian fluid, judging that the flow state of the liquid is laminar flow according to the Reynolds number, wherein a Navier-Stoks equation of the liquid flow is as follows:
equation one:
where ρ is the fluid density; v is the velocity vector, u, v, w is the velocity component of the fluid at time t, at point (x, y, z); p is pressure; f is an external force applied to the unit volume of fluid, and if only gravity is considered, f is rho g; the constant μ is the viscosity coefficient.
The flow is simplified into one-dimensional flow, and the inertia force and the mass force in the liquid flowing process are neglected, so that the equation meets the following conditions:
v＝w＝0
fx＝fy＝fz＝0
wherein, the density rho of the fluid is constant, the fluid viscosity coefficient mu is also constant, and the Navier-Stoks equation can be simplified as follows:
equation two:
wherein u is the liquid layer flow velocity;
two successive integrations of equation two can be found:
equation three:
setting the boundary condition y to be 0 and u to be 0; substituting y as h and u as 0 into equation three can obtain velocity distribution function
Taking a infinitesimal element with a cross-sectional area of
The volumetric leak rate integrated for a single leak channel is:
equation four:
assuming that the contact length of the gasket is L, the width of the bottom side of each leakage path is
The number of leakage paths is then
The total leak rate is therefore:
equation five:
wherein h is the gap height, theta is the cone angle, and delta p is the pressure difference between the inner side and the outer side of the sealing interface; l is the length of the sealing surface; b is the seal width; μ is the viscosity coefficient of the fluid, i.e., the viscosity coefficient of water.
Further, the optimization module specifically optimizes the sealing gasket section by using the leakage rate and the contact stress as indexes, and comprises the following steps:
evaluating the shape of the section of the current sealing gasket according to the leakage rate value, the average value and the maximum value of the contact stress and the compression force, and observing the form change of the sealing gasket in the compression process according to the contact stress distribution rule of the groove and the surface of the sealing gasket to obtain a multi-parameter controlled sealing gasket section shape optimization strategy;
under the constraint conditions of the maximum compression force, the maximum compression amount and the constraint range of the ratio of the section area of the sealing gasket to the area of the groove, the final section shape of the sealing gasket is selected by taking the small leakage rate, the large contact stress and the uniform form change of the sealing gasket in the compression process as targets.
The invention provides an optimization method and a system for the section shape of a sealing gasket of a shield tunnel segment joint, which establish a 2.5D model and a finite element model of the sealing gasket by analyzing the working condition characteristics of the sealing gasket, model a sealing gasket surface leakage channel by adopting a conical plane contact model and a Roth model, perform compression simulation on the sealing gasket finite element model according to the actual working condition, calculate the leakage rate value, the average value and the maximum value of contact stress and the compression force, make good and bad evaluation on the current sealing gasket section shape, provide a sealing gasket section shape optimization strategy controlled by multiple parameters, and select the final sealing gasket section shape by taking the small leakage rate, the large contact stress and the uniform form change of the sealing gasket in the compression process as targets under the constraint conditions of the maximum compression force, the maximum compression amount, the ratio constraint range of the sealing gasket section area to the groove area, compared with the prior art, the method has the following advantages:
1. most of the existing sealing gasket section design and optimization methods are based on engineering experience, the evaluation index is single and is generally contact stress, the invention researches the micro-morphology of the sealing gasket, establishes a micro-leakage channel model, evaluates the shape of the sealing gasket section by applying the important index of the leakage rate and provides a more scientific optimization strategy;
2. the invention provides a complete evaluation system for the section shape of a sealing gasket, which comprises constraint conditions such as compression force and the like which are fit with actual working conditions, and complete evaluation indexes such as leakage rate, average contact stress, maximum contact stress and the like, and avoids adverse consequences caused by neglecting a certain aspect in the section shape optimization process of the sealing gasket.
Drawings
Fig. 1 is a general flowchart of a method for optimizing a section of a sealing gasket of a segment joint of a shield tunnel according to an embodiment of the present invention;
FIG. 2 is a 2.5D model of a gasket and groove provided in accordance with an embodiment of the present invention;
FIG. 3 is a finite element model of a gasket and groove according to an embodiment of the present invention;
FIG. 4 is a conical plane contact model provided by an embodiment of the present invention;
FIG. 5 is a Roth model provided by an embodiment of the present invention;
FIG. 6 is a schematic diagram of a Roth model after equivalent transformation provided by an embodiment of the present invention;
FIG. 7 is a schematic view of the microscopic cone peak loading provided by an embodiment of the present invention;
FIG. 8 is a graph illustrating a gasket surface stress distribution according to an embodiment of the present invention;
FIG. 9 illustrates an optimized gasket cross-sectional shape according to an embodiment of the present invention;
fig. 10 is a graph illustrating an optimized gasket surface stress distribution according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a general flow chart of a method for optimizing a section of a shield tunnel segment joint sealing gasket according to an embodiment of the present invention includes:
s1, establishing a 2.5D section model and a finite element model of the sealing gasket and the groove by analyzing actual working conditions;
s2, fixedly restraining the lower groove, moving the upper hook groove left and right to construct compression simulation of the lower sealing gasket of the finite element model, extracting the contact stress distribution of the surface of the sealing gasket, and calculating the maximum value, the average value and the compression force of the contact stress;
s3, establishing a microscopic lower sealing gasket surface leakage model by adopting a conical plane contact model and a Roth model, deducing a leakage rate formula based on the leakage model, and calculating the leakage rate;
and S4, optimizing the section of the sealing gasket by taking the leakage rate and the contact stress as indexes to obtain an optimized interface model.
As shown in fig. 2 and 3, a 2.5D model and a finite element model of a gasket and a groove are established, wherein the model comprises an upper gasket, a lower gasket, an upper groove, a lower groove and the like, the invention aims at optimizing the sectional shape of the gasket, and mainly optimizes the shape of holes, the size of the holes and the arrangement mode of the holes of the gasket due to the limitation of the size of the groove.
As shown in fig. 4, according to the measurement result of the profiler, it is more practical and accurate to use the conical plane contact model to represent the microscopic contact condition of the rubber gasket surface, and because the gasket contact surface is a random rough surface satisfying Gauss distribution, which is more complex and inconvenient to calculate and analyze, a widely used Roth model is adopted, which uses continuous identical isosceles triangles to simplify the random rough peak, and the Roth model has a simple structure, can intuitively reflect the contact condition of the microscopic surface, and is convenient to calculate and analyze the fluid leakage condition between the contact surfaces, and the Roth model in which the two gaskets are in contact with each other is shown in fig. 5.
Since the two gaskets in contact with each other have the same roughness, the Roth model can be transformed into a smooth rigid surface and another roughness of
As shown in fig. 6. And deducing the leakage rate based on a Roth model, assuming that the liquid between the sealing gaskets is uniform Newtonian fluid, judging that the flow state is laminar flow according to the Reynolds number, wherein the Navier-Stoks (Navier-Stokes) equation of the liquid flow is as follows:
where ρ is the fluid density; v is the velocity vector, u, v, w is the velocity component of the fluid at time t, at point (x, y, z); p is pressure; f is an external force applied to the unit volume of fluid, and if only gravity is considered, f is rho g; the constant μ is the viscosity coefficient.
The flow is simplified into one-dimensional flow, and the inertia force and the mass force in the liquid flowing process are neglected, so that the equation meets the following conditions:
v＝w＝0；
fx＝fy＝fz＝0；
wherein, the density rho of the fluid is a constant, and the viscosity coefficient mu of the fluid is also a constant;
the equation can be simplified as:
where u is the liquid layer flow velocity, twice successive integrations give:
setting the boundary condition y to be 0 and u to be 0; substituting y-h, u-0 into (3) can obtain the velocity profile function:
as shown in FIG. 4, a infinitesimal element is obtained from the leakage channel, and the cross-sectional area is set to be
The volumetric leak rate integrated for a single leak channel is:
assuming that the contact length of the gasket is L, the width of the bottom side of each leakage path is L as can be seen from FIG. 4
The number of leakage paths is then
The total leak rate is therefore:
in the formula (6), h is the gap height, and Δ p is the pressure difference between the inner side and the outer side of the sealing interface; l is the length of the sealing surface; b is the seal width; μ is the viscosity coefficient of the fluid, i.e., the viscosity coefficient of water.
In the leakage rate formula (6), the pressure difference Δ p between the inside and outside of the sealing interface does not occurThe leakage is the external water pressure; seal face length L, which is generally a known parameter; the sealing width B is the width of the sealing gasket under the condition of no dislocation; the viscosity coefficient μ of the fluid, i.e. the viscosity coefficient of water, is generally set to 0.8949 × 10-3pa · s. The clearance height h is indirectly obtained by finite element simulation, the rough surface randomly generated by a computer is discretized, and then sampling statistics is carried out to obtain the average value of the peak height of the conical peak and the cone angle as the initial peak height
And a taper angle theta. For the finite element model established by the formula (4), the fixed constraint is applied to the lower groove, the displacement simulation actual compression process is applied to the upper groove, the average positive pressure is calculated after the compression simulation is completed and is applied to the top surface of the conical peak as the load, and the final height of the conical peak is recorded, as shown in fig. 7.
Substituting all parameter values into formula (6), calculating the leakage rate of the current sealing gasket, and extracting the contact surface contact stress distribution of the contact surface method after the finite element model compression simulation is completed as shown in figure 8, it can be seen that the situation of stress concentration at two ends occurs in the original model, the height of the middle stress wave crest is insufficient, only one peak height exceeds 1MPa, the section shape of the original model is optimized, and the evaluation results of a plurality of groups of models are shown in the table:
it can be seen from the table that five groups of new cross-sectional shapes do not all have performance improvement compared with the initial cross-section, and the optimization of the cross-sectional shape is a process requiring multiple groups of tests, and it is obvious from the table that the new cross-section 5 has obvious performance improvement compared with the initial cross-section, wherein the leakage rate and the average contact stress index are both better than those of the initial cross-section, and the improvement amplitude is close to 20%, although the normal maximum stress is smaller than that of the initial cross-section, the data distortion phenomenon occurs in consideration of the normal maximum stress of the initial cross-section appearing at two ends of stress concentration, so that the new cross-section 5 is successfully optimized based on the method of the present invention. The finite element model of the new section 5 is shown in fig. 9, the finite element compression simulation is performed on the new section 5, the stress distribution of the extracted contact surface is shown in fig. 10, it can be seen that the stress concentration phenomenon is relieved compared with the initial section, 3 stress peaks except for two ends of the contact surface exceed 1MPa, and the new section 5 has better waterproof capability than the initial section.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. A method for optimizing the section of a sealing gasket of a shield tunnel segment joint is characterized by comprising the following steps:
s1, establishing a 2.5D section model and a finite element model of the sealing gasket and the groove by analyzing actual working conditions;
s2, applying load to the finite element model of the sealing gasket to complete compression simulation, extracting the contact stress distribution of the surface of the sealing gasket, and calculating the maximum value, the average value and the compression force of the contact stress;
s3, establishing a microscopic lower sealing gasket surface leakage model by adopting a conical plane contact model and a Roth model, deducing a leakage rate formula based on the leakage model, and calculating the leakage rate;
and S4, optimizing the section of the sealing gasket by taking the leakage rate and the contact stress as indexes to obtain an optimized interface model.
2. The shield tunnel segment joint sealing gasket section optimization method according to claim 1, wherein the step S2 specifically comprises the steps of: and fixedly constraining the lower groove, moving the upper hook groove up and down, applying different compressive forces to the sealing gasket to construct a compressive simulation of the sealing gasket under the finite element model, extracting the surface contact stress distribution of the sealing gasket, and acquiring the maximum value, the average value and the compressive force of the contact stress based on the surface contact stress distribution of the sealing gasket.
3. The shield tunnel segment joint sealing gasket section optimization method according to claim 1, wherein the step S3 specifically comprises the steps of:
s31: firstly, selecting a microcosmic contact model, selecting a conical plane contact model which is more in line with the actual situation according to the observation of a surface profiler, and then selecting a Roth model as a leakage channel model, wherein the Roth model is a leakage channel model which is formed by simplifying random rough peaks by continuous identical isosceles triangles, and the model has a simple and direct structure and is convenient for calculating and analyzing the leakage situation of fluid between contact surfaces;
s32, deducing a calculation formula of the leakage rate, assuming that the liquid between the sealing gaskets is uniform Newtonian fluid, judging that the flow state is laminar flow according to the Reynolds number, and the Navier-Stoks equation of the liquid flow is as follows:
equation one:
where ρ is the fluid density; v is the velocity vector, u, v, w is the velocity component of the fluid at time t, at point (x, y, z); p is pressure; f is an external force applied to the unit volume of fluid, and if only gravity is considered, f is rho g; the constant μ is the viscosity coefficient;
the flow is simplified into one-dimensional flow, and the inertia force and the mass force in the liquid flowing process are neglected, so that the equation meets the following conditions:
v＝w＝0
fx＝fy＝fz＝0
wherein, the density rho of the fluid is constant, the fluid viscosity coefficient mu is also constant, and the Navier-Stoks equation can be simplified as follows:
equation two:
wherein u is the liquid layer flow velocity;
two successive integrations of equation two can be found:
equation three:
setting the boundary condition y to be 0 and u to be 0; substituting y as h and u as 0 into equation three can obtain velocity distribution function
Taking a infinitesimal element from the leakage channel to make its cross-sectional area be
The volumetric leak rate integrated for a single leak channel is:
equation four:
assuming that the contact length of the gasket is L, the width of the bottom side of each leakage path is
The number of leakage paths is then
The total leak rate is therefore:
equation five:
wherein h is the height of the gap,
is a cone angleDelta p is the pressure difference between the inner side and the outer side of the sealing interface; l is the length of the sealing surface; b is the seal width; μ is the viscosity coefficient of the fluid, i.e., the viscosity coefficient of water.
4. The shield tunnel segment joint sealing gasket section optimization method according to claim 1, wherein the step S4 specifically comprises the steps of:
s41, evaluating the quality of the section shape of the current sealing gasket according to the leakage rate value, the average value and the maximum value of the contact stress and the compression force, observing the form change of the sealing gasket in the compression process according to the contact stress distribution rule of the groove and the surface of the sealing gasket, and obtaining a multi-parameter controlled sealing gasket section shape optimization strategy;
and S42, under the constraint conditions of the maximum compression force, the maximum compression amount and the constraint range of the ratio of the section area of the sealing gasket to the area of the groove, selecting the final section shape of the sealing gasket by taking the small leakage rate, the large contact stress and the uniform form change of the sealing gasket in the compression process as targets.
5. The shield tunnel segment joint sealing gasket section optimization method according to claim 3, wherein S41 specifically comprises: according to the compression simulation result of the finite element model of S2, the average value of the contact stress is used as the load of the microscopic conical peak, the microscopic conical peak is loaded on the top surface of the conical peak in the form of uniform load, the height of the conical peak is recorded after the load is completed, the height is substituted into the leakage rate formula of S3, the leakage rate is calculated, the average value, the maximum value and the compression force of the contact stress of S2 are recorded, the deformation condition of the gasket in the compression process is observed, the displacement of each point on the contact surface of the gasket in the direction perpendicular to the contact surface is extracted, and the form change of the gasket in the compression process is quantified.
6. The shield tunnel segment joint sealing gasket section optimization method according to claim 3, wherein S42 specifically comprises: for the initial design of the section shape of the sealing gasket, the rule that the ratio A0/A1 of the section area A0 of the sealing gasket to the groove area A1 is 1-1.15 is followed, for the evaluation of the section shape of the sealing gasket, the numerical value of the compression force is considered firstly, for the section shape of which the compression force exceeds the assembling force of the pipe piece, other evaluation indexes are not considered, namely, the section shape is judged to be unqualified, and for the section shape of which the compression force is in the range of the assembling force of the pipe piece, the leakage rate, the average contact stress of the surface of the sealing gasket and the maximum stress are comprehensively considered, so that the optimal section shape of the sealing gasket is selected.
7. A shield tunnel segment joint sealing gasket section optimization system is characterized by comprising a model building module, a stress calculation module, a leakage rate calculation module, a deformation variation module and an optimization module;
the model building module is used for building a 2.5D section model and a finite element model of the sealing gasket and the groove by analyzing actual working conditions;
the stress calculation module is used for applying load to the finite element model of the sealing gasket to complete compression simulation, extracting contact stress distribution on the surface of the sealing gasket and calculating the maximum value, the average value and the compression force of the contact stress;
the leakage rate calculation module is used for establishing a microscopic lower sealing gasket surface leakage model by adopting a conical plane contact model and a Roth model, deducing a leakage rate formula based on the leakage model and calculating the leakage rate;
the optimization module is used for optimizing the section of the sealing gasket by taking the leakage rate and the contact stress as indexes to obtain an optimized interface model.
8. The shield tunnel segment joint sealing gasket section optimization system of claim 7, wherein the leakage rate calculation module adopts a conical plane contact model and a Roth model to establish a microscopic sealing gasket surface leakage model, derives a leakage rate formula based on the leakage model, and calculates the leakage rate specifically including:
firstly, selecting a microcosmic contact model, selecting a conical plane contact model which is more in line with the actual situation according to the observation of a surface profiler, and then selecting a Roth model as a leakage channel model, wherein the Roth model is a leakage channel model which is formed by simplifying random rough peaks by continuous identical isosceles triangles, and the model has a simple and direct structure and is convenient for calculating and analyzing the leakage situation of fluid between contact surfaces;
deducing a calculation formula of the leakage rate, assuming that liquid between the sealing gaskets is uniform Newtonian fluid, judging that the flow state of the liquid is laminar flow according to the Reynolds number, wherein a Navier-Stoks equation of the liquid flow is as follows:
equation one:
where ρ is the fluid density; v is the velocity vector, u, v, w is the velocity component of the fluid at time t, at point (x, y, z); p is pressure; f is an external force applied to the unit volume of fluid, and if only gravity is considered, f is rho g; the constant μ is the viscosity coefficient;
the flow is simplified into one-dimensional flow, and the inertia force and the mass force in the liquid flowing process are neglected, so that the equation meets the following conditions:
v＝w＝0
fx＝fy＝fz＝0
wherein, the density rho of the fluid is constant, the fluid viscosity coefficient mu is also constant, and the Navier-Stoks equation can be simplified as follows:
equation two:
wherein u is the liquid layer flow velocity;
two successive integrations of equation two can be found:
equation three:
setting the boundary condition y to be 0 and u to be 0; substituting y as h and u as 0 into equation three can obtain velocity distribution function
Taking a infinitesimal element with a cross-sectional area of
The volumetric leak rate integrated for a single leak channel is:
equation four:
assuming that the contact length of the gasket is L, the width of the bottom side of each leakage path is
The number of leakage paths is then
The total leak rate is therefore:
equation five:
wherein h is the height of the gap,
is the cone angle, and delta p is the pressure difference between the inner side and the outer side of the sealing interface; l is the length of the sealing surface; b is the seal width; μ is the viscosity coefficient of the fluid, i.e., the viscosity coefficient of water.
9. The shield tunnel segment joint sealing gasket section optimization system of claim 7, wherein the optimization module specifically optimizes the sealing gasket section by using the leakage rate and the contact stress as indexes, and comprises:
evaluating the shape of the section of the current sealing gasket according to the leakage rate value, the average value and the maximum value of the contact stress and the compression force, and observing the form change of the sealing gasket in the compression process according to the contact stress distribution rule of the groove and the surface of the sealing gasket to obtain a multi-parameter controlled sealing gasket section shape optimization strategy;
under the constraint conditions of the maximum compression force, the maximum compression amount and the constraint range of the ratio of the section area of the sealing gasket to the area of the groove, the final section shape of the sealing gasket is selected by taking the small leakage rate, the large contact stress and the uniform form change of the sealing gasket in the compression process as targets.
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