Method for identifying weak position in advance of immersed tube tunnel structure and related equipment

Abstract

The application discloses a method for identifying weak positions of immersed tube tunnel structures in advance and related equipment, and comprises the following steps: S1, carrying out a load plate test on site to determine the stiffness of the foundation of the immersed tube tunnel; S2, analyzing the load borne by the immersed tube tunnel, including the gravity of the immersed tube tunnel and external water and soil load borne by the immersed tube tunnel; analyzing the ion composition of the water body in the water environment of the immersed tube tunnel to identify the erosive ions causing the deterioration of the immersed tube tunnel; S3, based on the identified load type, establishing a mathematical model for describing the mechanical behavior of the immersed tube tunnel under the load; based on the identified erosive ions, establishing a mathematical model for describing the chemical behavior of the immersed tube tunnel under the erosive ions; S4, establishing a three-dimensional finite element model of the immersed tube tunnel; the application can identify the weak positions of the immersed tube tunnel at the construction stage of the immersed tube tunnel, and can indicate the positions of the local anti-seepage reinforcement of the weak positions, thereby preventing a passive situation of remedying after the structure seeps water.

Description

Technical Field

[0001] The present application relates to the technical field of service performance evaluation of water-related infrastructure-concrete structures, and in particular to a method for advanced identification of weak positions in immersed tube tunnel structures and related equipment. Background Art

[0002] With the acceleration of urbanization and the continuous increase in transportation demand, immersed tube tunnels have been widely used as an important transportation infrastructure. Immersed tube tunnels are usually laid on the bottom of rivers, lakes or oceans. Their construction process involves complex engineering technology and high costs. However, due to the special construction environment of immersed tube tunnels and their long-term exposure to water erosion, their structural stability and service life face many challenges. In immersed tube tunnels, the identification of weak points is crucial for the safe operation and maintenance of the tunnel. Weak points usually refer to areas in the tunnel structure that are prone to stress concentration or material degradation. Under the combined effects of external loads and environmental conditions, these weak points are prone to cracks, deformation, and even failure, seriously affecting the overall safety of the tunnel. Therefore, accurately identifying and promptly reinforcing these weak points has become an important issue in the current engineering community.

[0003] Existing methods for identifying weak spots primarily rely on on-site inspection and monitoring technologies, including traditional visual inspection, acoustic testing, radar detection, and fiber optic sensing. However, these methods are often hindsight: they can only be used to identify and locate weak spots in immersed tube tunnels after cracks or water leaks have occurred, allowing remedial measures to be taken. Therefore, a method for proactively identifying weak spots in immersed tube tunnels is urgently needed. Summary of the Invention

[0004] To address the above-mentioned issues, the present application provides a method and related equipment for advanced identification of weak locations in immersed tube tunnel structures. These methods can be used to locally strengthen weak locations during the construction phase of immersed tube tunnels, thereby preventing the need for remedial measures after water seepage. The technical solution is as follows:

[0005] The present application provides a method for advanced identification of weak locations in an immersed tube tunnel structure, comprising the following steps:

[0006] S1 conducted load plate tests on site to determine the stiffness of the immersed tube tunnel foundation and drew a foundation stiffness distribution map;

[0007] S2 analyzes the loads on the immersed tunnel, including the tunnel's own gravity and external water and soil loads. It also analyzes the ion composition of the water in the immersed tunnel's water environment and identifies corrosive ions that cause tunnel degradation.

[0008] S3: Based on the load type identified in S2, a mathematical model is established to describe the mechanical behavior of the immersed tube tunnel under the load; based on the corrosive ions identified in S2, a mathematical model is established to describe the chemical behavior of the immersed tube tunnel under the corrosive ions;

[0009] S4: establishing a three-dimensional finite element model of the immersed tube tunnel in finite element numerical simulation software based on the actual size of the immersed tube tunnel on site, and inputting basic parameters of the three-dimensional finite element model of the immersed tube tunnel and the mechanical behavior mathematical model and chemical behavior mathematical model of the immersed tube tunnel established in S3 into the finite element numerical simulation software;

[0010] S5: Determine the boundary conditions of the immersed tube tunnel's three-dimensional finite element model using finite element numerical simulation software based on the actual on-site manufacturing and installation conditions.

[0011] S6 conducts finite element numerical simulations of immersed tube tunnels under overlying water and soil loads and corrosive ion effects, and calculates the stress, deformation, and damage of immersed tube tunnels;

[0012] S7 calculates the stress, deformation and damage of the immersed tube tunnel using finite element numerical simulation software, and identifies the weak locations of the immersed tube tunnel.

[0013] For example, in the method for advanced identification of weak positions of the immersed tube tunnel structure provided in one embodiment, in S1, load plate tests are carried out at different positions at the immersed tube tunnel construction site to obtain the load-deformation curve of the immersed tube tunnel foundation; the stiffness of the foundation is calculated based on the load-deformation curve, and then the stiffness distribution of the immersed tube tunnel foundation is obtained, and a stiffness distribution map of the immersed tube tunnel foundation is drawn.

[0014] For example, in the method for advance identification of weak positions of the immersed tube tunnel structure provided in one embodiment, the analysis of the load borne by the immersed tube tunnel in S2 includes the following steps: according to the design data of the immersed tube tunnel, the proportion of concrete used in the immersed tube tunnel is clarified, thereby calculating the deadweight of the immersed tube tunnel; according to the design data of the immersed tube tunnel, the density of the water environment in which the immersed tube tunnel is located and the underwater depth of the immersed tube tunnel are clarified, thereby calculating the external water pressure borne by the immersed tube tunnel, including: overlying water pressure, side wall water pressure and bottom water pressure; according to the design data of the immersed tube tunnel, the backfill plan of the immersed tube tunnel and the density of the backfill material used are clarified, thereby calculating the external soil pressure borne by the immersed tube tunnel, including: overlying soil pressure and side wall soil pressure.

[0015] For example, in the method for advanced identification of weak locations in an immersed tube tunnel structure provided in one embodiment, in S3, establishing a mathematical model of mechanical behavior of the immersed tube tunnel includes the following steps:

[0016] An elastic-plastic damage mechanics model considering mechanical damage caused by stress loading is used to describe the mechanical behavior of immersed tube tunnels under load, including stress, deformation and damage.

[0017]

[0018] wherein:

[0019] ε = ε e + ε p Equation (2).

[0020] d m = d mc [1-exp(-b d γ p )] Equation (3).

[0021] In Equations (1)-(3), σ is the stress tensor of concrete is the elastic stiffness tensor of concrete; ε is the total strain tensor of concrete, which is composed of elastic strain tensor ε e and plastic strain tensor ε p ; d mc is the maximum mechanical damage variable, which can be determined by indoor triaxial test; b d is the rate parameter controlling the evolution of mechanical damage variable.

[0022] For example, in the method for identifying weak positions of the immersed tube tunnel structure in advance provided in an embodiment, the step of establishing a mathematical model of chemical behavior of the immersed tube tunnel in S3 includes the following steps:

[0023] A convection-diffusion-reaction damage model that comprehensively considers damage effects, ion convection, ion diffusion and the influence of chemical reaction is used:

[0024]

[0025] In Equation (4), c is the concentration of sulfate ions in concrete, mol / m 3 ; D(d c , d m ) is the diffusion coefficient considering chemical damage and mechanical damage effects, m 2 / s; ▽ is the Laplace operator; u is the convection velocity of the solution of the water body in which the immersed tube tunnel is located in the pores of concrete, m / s; C d is the concentration of sulfate ions and chloride ions consumed due to chemical reaction, mol / m 3 .

[0026] wherein:

[0027]

[0028] In Equation (5), kv Indicates the chemical reaction rate between corrosive ions in concrete and concrete hydrates, s -1 ; Indicates the concentration of calcium ions in the concrete pore solution, mol / m 3 ;

[0029] Chemical damage based on the definition of concrete volume expansion strain is used to describe the degradation of mechanical properties caused by sulfate attack:

[0030]

[0031] In formula (6), k and m are model parameters related to concrete materials and erosion conditions; ε ep0 is the critical expansion strain for chemical damage to concrete; ep It is the volume expansion strain caused by products such as ettringite.

[0032] For example, in the method for advance identification of weak positions of the immersed tube tunnel structure provided in one embodiment, in S4, a three-dimensional finite element model of the immersed tube tunnel is drawn in the finite element numerical simulation software based on the actual size of the immersed tube tunnel on site, the established three-dimensional finite element model of the immersed tube tunnel is meshed, and the mesh quality evaluation function of the finite element software is used to evaluate the quality of the mesh division until the mesh division quality meets the numerical simulation requirements.

[0033] For example, in the method for advance identification of weak positions of the immersed tube tunnel structure provided in one embodiment, in S4, the method for obtaining the basic parameters of the three-dimensional finite element model of the immersed tube tunnel is: making concrete specimens based on the concrete materials used in the on-site immersed tube tunnel, carrying out triaxial compression tests, density tests, porosity tests and mineral composition analysis tests, and obtaining the strength, elastic modulus, Poisson's ratio, density, porosity of the immersed tube tunnel and the content of hydrates in the immersed tube tunnel concrete.

[0034] For example, in the method for advanced identification of weak locations in an immersed tube tunnel structure provided in one embodiment, in S5, determining the boundary conditions of the immersed tube tunnel three-dimensional finite element model in finite element numerical simulation software includes the following steps:

[0035] Apply force boundary conditions to the top and side walls of the immersed tunnel based on the water and soil loads calculated in S2;

[0036] Apply force boundary conditions or displacement boundary conditions at both ends of the immersed tube tunnel according to the actual installation conditions on site;

[0037] According to the foundation stiffness determined by S1, an elastic foundation boundary condition is applied to the bottom of the immersed tunnel.

[0038] A second aspect of the present application provides an electronic device comprising: a memory and a processor, wherein the processor is configured to implement the above-mentioned method for advanced identification of weak positions of immersed tube tunnel structures when executing a computer management program stored in the memory.

[0039] A third aspect of the present application provides a computer-readable storage medium having a computer management program stored thereon. When the computer management program is executed by a processor, the method for advanced identification of weak positions of an immersed tube tunnel structure is implemented.

[0040] The beneficial effects brought about by a method for advance identification of weak positions in an immersed tube tunnel structure provided by some embodiments of the present application and related equipment are as follows: the present application provides a method for identifying weak positions in ultra-wide immersed tube tunnels in a water-related environment, which can identify the weak positions of an immersed tube tunnel during the construction phase of the immersed tube tunnel, indicate the locations for local anti-seepage reinforcement of the weak positions, and prevent the passive situation of having to remediate the situation after structural water seepage occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 This is a flow chart of the method for advanced identification of weak locations in immersed tube tunnel structures of this application;

[0043] Figure 2 This is a schematic diagram of the distribution of a certain immersed tube tunnel used in this application case;

[0044] Figure 3 This is the foundation stiffness distribution diagram of a certain immersed tube tunnel used in this application case;

[0045] Figure 4 This is a stress analysis diagram of an immersed tube tunnel used in this application case;

[0046] Figure 5 This is a three-dimensional finite element model diagram of an immersed tube tunnel used in this application case;

[0047] Figure 6 This is the main view of the stress distribution of a certain immersed tube tunnel used in this application case;

[0048] Figure 7 This is a bottom view of the stress distribution of a certain immersed tube tunnel used in this application case;

[0049] Figure 8 This is the main view of the maximum tensile strain distribution of a certain immersed tube tunnel in the application case of this application;

[0050] Figure 9 This is a bottom view of the maximum tensile strain distribution of a certain immersed tube tunnel used in this application case;

[0051] Figure 10 This is the main view of the damage distribution of a certain immersed tube tunnel used in this application case;

[0052] Figure 11 This is a bottom view of the damage distribution of a certain immersed tube tunnel used in this application case. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0054] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0055] This application provides a method for advanced identification of weak locations in immersed tube tunnel structures, such as Figure 1 As shown, the following steps are included:

[0056] S1 conducted load plate tests on site to determine the stiffness of the immersed tube tunnel foundation and drew a foundation stiffness distribution map;

[0057] Specifically, load plate tests were carried out at different locations on the immersed tube tunnel construction site to obtain the load-deformation curve of the immersed tube tunnel foundation. The stiffness of the foundation was calculated based on the load-deformation curve, and the stiffness distribution of the immersed tube tunnel foundation was then obtained. A stiffness distribution map of the immersed tube tunnel foundation was then drawn.

[0058] S2 analyzes the loads on the immersed tunnel, including the tunnel's own gravity and external water and soil loads. It also analyzes the ion composition of the water in the immersed tunnel's water environment and identifies corrosive ions that cause tunnel degradation, including sulfate and chloride ions.

[0059] The analysis of the load borne by the immersed tube tunnel includes the following steps:

[0060] Based on the immersed tunnel design data, determine the concrete mix ratio used in the immersed tunnel and calculate the self-weight of the immersed tunnel;

[0061] Based on the immersed tunnel design data, determine the density of the water environment in which the immersed tunnel is located and the underwater depth of the immersed tunnel, so as to calculate the external water pressure on the immersed tunnel, including: overlying water pressure, side wall water pressure, and bottom water pressure;

[0062] Based on the immersed tunnel design data, the immersed tunnel backfill plan and the density of the backfill material to be used are determined, so as to calculate the external earth pressure on the immersed tunnel, including the overburden pressure and the sidewall earth pressure;

[0063] The specific method for analyzing the ion composition of water in the immersed tube tunnel environment is to collect water samples from the construction site where the immersed tube tunnel is located, and then perform ion composition analysis in the laboratory to determine the content of sulfate ions and chloride ions in the water.

[0064] S3: Based on the load type identified in S2, a mathematical model is established to describe the mechanical behavior (including stress, deformation, and damage) of the immersed tube tunnel under the load; based on the corrosive ions identified in S2, a mathematical model is established to describe the chemical behavior (including ion migration, chemical reaction, and damage) of the immersed tube tunnel under the corrosive ions;

[0065] Specifically, establishing a mathematical model of the mechanical behavior of an immersed tube tunnel includes the following steps:

[0066] An elastoplastic damage mechanics model that considers mechanical damage caused by stress loading is used to describe the mechanical behavior of the immersed tube tunnel under load, including stress, deformation and damage.

[0067]

[0068] in:

[0069] ε=ε e +ε p Formula (2);

[0070] d m =d mc [1-exp(-b d γp )] Formula (3);

[0071] In formulas (1)-(3), σ is the concrete stress tensor, is the concrete elastic stiffness tensor; ε is the total strain tensor of concrete, which is obtained from the elastic strain tensor ε e and the plastic strain tensor ε p Composition; d mc is the maximum mechanical damage variable, which can be determined by indoor triaxial test; b d is the rate parameter that controls the evolution of mechanical damage variables;

[0072] The development of a mathematical model of chemical behavior in an immersed tunnel involves the following steps:

[0073] A convection-diffusion-reaction damage model is used that comprehensively considers the damage effect, ion convection, ion diffusion, and chemical reaction:

[0074]

[0075] In formula (4), c is the concentration of sulfate ions in concrete, mol / m 3 ; D(d c ,d m ) is the diffusion coefficient considering the effects of chemical damage and mechanical damage, m 2 / s; ▽ is the Laplace operator; u is the convection velocity of the water solution in the immersed tube tunnel in the concrete pores, m / s; C d is the concentration of sulfate ions and chloride ions consumed by chemical reactions, mol / m 3 ;

[0076] in:

[0077]

[0078] In formula (5), k v Indicates the chemical reaction rate between corrosive ions in concrete and concrete hydrates, s -1 ; Indicates the concentration of calcium ions in the concrete pore solution, mol / m 3 ;

[0079] Chemical damage based on the definition of concrete volume expansion strain is used to describe the degradation of mechanical properties caused by sulfate attack:

[0080]

[0081] In formula (6), k and m are model parameters related to concrete materials and erosion conditions; ε ep0 is the critical expansion strain for chemical damage to concrete;ep It is the volume expansion strain caused by products such as ettringite;

[0082] S4: establishing a three-dimensional finite element model of the immersed tube tunnel in finite element numerical simulation software based on the actual size of the immersed tube tunnel on site, and inputting basic parameters of the three-dimensional finite element model of the immersed tube tunnel and the mechanical behavior mathematical model and chemical behavior mathematical model of the immersed tube tunnel established in S3 into the finite element numerical simulation software;

[0083] The specific method for establishing a three-dimensional finite element model of the immersed tube tunnel in finite element numerical simulation software is as follows: based on the actual dimensions of the immersed tube tunnel on site, a three-dimensional finite element model of the immersed tube tunnel is drawn in the finite element numerical simulation software, the established three-dimensional finite element model of the immersed tube tunnel is meshed, and the mesh quality is evaluated using the mesh quality assessment function of the finite element software until the mesh quality meets the numerical simulation requirements;

[0084] The basic parameters of the immersed tunnel's three-dimensional finite element model were obtained by preparing concrete specimens of standard dimensions (50 mm diameter x 100 mm height) based on the concrete material used in the on-site immersed tunnel. Triaxial compression tests, density tests, porosity tests, and mineral composition analysis tests were conducted to determine the tunnel's strength, elastic modulus, Poisson's ratio, density, porosity, and hydrate content. These basic parameters were then input into the finite element software.

[0085] S5: Determine the boundary conditions of the immersed tube tunnel's three-dimensional finite element model using finite element numerical simulation software based on the actual on-site manufacturing and installation conditions.

[0086] Specifically, force boundary conditions are applied to the top and two side walls of the immersed tube tunnel according to the water and soil loads calculated in S2;

[0087] Apply force boundary conditions or displacement boundary conditions at both ends of the immersed tube tunnel according to the actual installation conditions on site;

[0088] Applying elastic foundation boundary conditions to the bottom of the immersed tunnel according to the foundation stiffness determined by S1;

[0089] S6 conducts finite element numerical simulations of immersed tube tunnels under overlying water and soil loads and corrosive ion effects, and calculates the stress, deformation, and damage of immersed tube tunnels;

[0090] Based on the above steps S1-S5, finite element numerical simulation software is used to conduct finite element numerical simulation of the immersed tube tunnel under the action of water and soil loads and corrosive ions, calculate the stress, deformation, and damage of the immersed tube tunnel, and obtain a three-dimensional distribution map of the stress, deformation, and damage of the immersed tube tunnel;

[0091] S7 uses finite element numerical simulation software to calculate the stress, deformation, and damage of the immersed tube tunnel, and identifies the weak points of the immersed tube tunnel;

[0092] Specifically, based on the obtained three-dimensional distribution map of stress, deformation and damage of the immersed tube tunnel, locations with greater stress, deformation and damage are identified and used as weak locations of the immersed tube tunnel.

[0093] Application Cases

[0094] The method for advanced identification of weak locations in immersed tube tunnel structure of the present application is used to identify weak locations in a certain immersed tube tunnel. The tunnel consists of 4 immersed tubes with a total length of 316m. The schematic diagram of its structure is shown in FIG. Figure 2 As shown in the figure, the identification process of the weak position of the immersed tube tunnel is as follows:

[0095] (1) Based on the load plate test carried out on site, the distribution of foundation stiffness of the immersed tube tunnel was determined, such as Figure 3 As shown;

[0096] (2) Actual load distribution on site: along the 316m long immersed tube tunnel, 10 sections were selected for external water and soil load analysis. The stress conditions at the remaining locations were obtained by difference. The 10 sections were located at the leftmost section of the E1 pipe segment. The detailed positions and values ​​are shown in Table 1. The stress diagram is shown in Figure 4 .

[0097] Table 1 Force table of immersed tube tunnel (unit kN / m 2 )

[0098] Section number Position / m P s1 ]]> <![CDATA[P s2 ]]> <![CDATA[P V ]]> <![CDATA[P t1 ]]> <![CDATA[P t2 ]]> <![CDATA[P w ]]> 1 11 69.68 177.68 182.88 38.489 71.537 44.94 2 41 78.80 186.80 165.51 29.47 62.52 44.94 3 56 83.35 191.35 136.36 18.02 51.07 44.94 4 89 93.38 201.38 121.25 9.48 42.53 44.94 5 132 98.43 206.43 135.60 12.64 45.69 44.94 6 169 97.31 205.31 140.26 14.60 47.65 44.94 7 209 96.11 204.11 143.37 16.07 49.12 44.94 8 248 86.08 194.08 135.45 16.78 49.83 44.94 9 286 75.65 183.65 128.29 17.90 50.95 44.94 10 306 70.15 178.15 124.51 18.48 51.53 44.94

[0099] Among them, the water head pressure at the top of the immersed tube is expressed as P s1 , the head pressure at the bottom is expressed as P s2 The vertical water and soil pressure at the top of the immersed tube is expressed as P V , the lateral earth pressure is expressed as P t1 The lateral earth pressure at the bottom of the immersed tube is expressed as P t2 , the internal ballast load is expressed as P w The anti-floating safety factor of the submerged tube after backfilling is K f =1.2, so P w =44938.68Pa.

[0100] (3) The concentrations of corrosive ions, sulfate and chloride, in the water environment of the immersed tunnel were tested. The sulfate concentration was 250 mg / L and the chloride concentration was 865.05 mg / L.

[0101] (4) According to the actual size of the immersed tunnel, a three-dimensional finite element model of the immersed tunnel is established in the finite element numerical simulation software, as shown in Figure 5 ;

[0102] (5) In the finite element numerical simulation software, the basic parameters of the three-dimensional finite element model of the immersed tunnel are input, as shown in Table 2;

[0103] Table 2 Basic parameter table of certain immersed tunnel

[0104]

[0105] (6) In the finite element numerical simulation software, the mechanical behavior mathematical model of the immersed tunnel established in step (3) and the chemical behavior mathematical model of the immersed tunnel established in step (5) are input;

[0106] (7) According to the actual installation situation of the immersed tunnel site, the boundary conditions of the three-dimensional finite element model are determined, wherein:

[0107] 1) According to the water and soil load given in step (2), force boundary conditions are applied to the top and two side walls of the immersed tunnel;

[0108] 2) Displacement boundary conditions of roller support are applied to both ends of the immersed tunnel;

[0109] 3) According to the stiffness distribution given in step (1), elastic foundation boundary conditions are applied to the bottom of the immersed tunnel;

[0110] (8) The finite element numerical simulation of the immersed tunnel under the action of water and soil load and erosive ions is carried out by using the finite element numerical simulation software, and the stress, deformation and damage of the immersed tunnel are calculated. The three-dimensional distribution diagram of the stress, deformation and damage of the immersed tunnel is shown in Figure 6-11 ;

[0111] (9) Based on the three-dimensional distribution diagram of the stress, deformation and damage of the immersed tunnel, it can be known that the weak positions of the immersed tunnel are: 1) the middle of the roof; 2) the bottom of the two side walls; 3) the middle of the bottom plate; 4) the middle of the bottom plate of the two channels.

[0112] The weak position of the immersed tunnel structure in the method is identified, which points out the direction for the subsequent anti-seepage reinforcement of the weak position, so as to prevent the passive situation of remedying after seepage.

[0113] The second aspect of the present application provides an electronic device, comprising a memory and a processor, wherein the processor is used to execute the computer management program stored in the memory to realize the method for identifying the weak position of the immersed tunnel structure in advance.

[0114] A third aspect of the present application provides a computer-readable storage medium having a computer management program stored thereon. When the computer management program is executed by a processor, the method for advanced identification of weak positions of an immersed tube tunnel structure is implemented.

[0115] Although the implementation scheme of the present application has been disclosed as above, it is not limited to the applications listed in the description and implementation mode. It can be fully applied to various fields suitable for the present application. For those familiar with this field, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for advanced identification of weak locations in immersed tunnel structures, characterized in that: The following steps are involved: S1 conducted load plate tests on site to determine the stiffness of the immersed tube tunnel foundation and drew a foundation stiffness distribution map; S2 analyzes the loads on the immersed tunnel, including the tunnel's own gravity and the external water and soil loads. It also analyzes the ion composition of the water in the immersed tunnel's water environment and identifies the corrosive ions that cause tunnel degradation. S3: Based on the load type identified in S2, a mathematical model is established to describe the mechanical behavior of the immersed tube tunnel under the load; based on the corrosive ions identified in S2, a mathematical model is established to describe the chemical behavior of the immersed tube tunnel under the corrosive ions; S4: establishing a three-dimensional finite element model of the immersed tube tunnel in finite element numerical simulation software based on the actual size of the immersed tube tunnel on site, and inputting basic parameters of the three-dimensional finite element model of the immersed tube tunnel and the mechanical behavior mathematical model and chemical behavior mathematical model of the immersed tube tunnel established in S3 into the finite element numerical simulation software; S5: Determine the boundary conditions of the immersed tube tunnel's three-dimensional finite element model using finite element numerical simulation software based on the actual on-site manufacturing and installation conditions. S6 conducts finite element numerical simulations of immersed tube tunnels under overlying water and soil loads and corrosive ion effects, and calculates the stress, deformation, and damage of immersed tube tunnels; S7 calculates the stress, deformation and damage of the immersed tube tunnel using finite element numerical simulation software, and identifies the weak locations of the immersed tube tunnel.

2. The method for advanced identification of weak locations in immersed tunnel structures according to claim 1, characterized in that: In S1, load plate tests are carried out at different locations on the immersed tube tunnel construction site to obtain a load-deformation curve of the immersed tube tunnel foundation; the stiffness of the foundation is calculated based on the load-deformation curve, and then the stiffness distribution of the immersed tube tunnel foundation is obtained, and a stiffness distribution map of the immersed tube tunnel foundation is drawn.

3. The method for advanced identification of weak locations in immersed tunnel structures according to claim 2, characterized in that: The analysis of the load borne by the immersed tube tunnel in S2 includes the following steps: Based on the immersed tunnel design data, determine the concrete mix ratio used in the immersed tunnel and calculate the self-weight of the immersed tunnel; Based on the immersed tunnel design data, determine the density of the water environment in which the immersed tunnel is located and the underwater depth of the immersed tunnel, so as to calculate the external water pressure on the immersed tunnel, including: overlying water pressure, side wall water pressure, and bottom water pressure; Based on the immersed tube tunnel design data, the immersed tube tunnel backfill plan and the density of the backfill material used are clarified, so as to calculate the external earth pressure on the immersed tube tunnel, including: overburden pressure and side wall earth pressure.

4. The method for advanced identification of weak locations in immersed tunnel structures according to claim 3 is characterized in that: In S3, establishing a mathematical model of mechanical behavior of the immersed tube tunnel includes the following steps: An elastoplastic damage mechanics model that considers mechanical damage caused by stress loading is used to describe the mechanical behavior of the immersed tube tunnel under load, including stress, deformation and damage. in: e=e e +e p expression(2); d m =d mc [1-exp(-b d γ p )] Formula (3); In formulas (1)-(3), σ is the concrete stress tensor, is the concrete elastic stiffness tensor; ε is the total strain tensor of concrete, which is obtained from the elastic strain tensor ε e and the plastic strain tensor ε p Composition; d mc is the maximum mechanical damage variable, which can be determined by indoor triaxial test; b d It is the rate parameter that controls the evolution of mechanical damage variables.

5. The method for advanced identification of weak locations in immersed tunnel structures according to claim 4, characterized in that: In S3, establishing a mathematical model of chemical behavior of an immersed tube tunnel includes the following steps: A convection-diffusion-reaction damage model is used that comprehensively considers the damage effect, ion convection, ion diffusion, and chemical reaction: In formula (4), c is the concentration of sulfate ions in concrete, mol / m 3 ; D(d c ,d m ) is the diffusion coefficient considering the effects of chemical damage and mechanical damage, m 2 / s; ▽ is the Laplace operator; u is the convection velocity of the water solution in the immersed tube tunnel in the concrete pores, m / s; C d is the concentration of sulfate ions and chloride ions consumed by chemical reactions, mol / m 3 ; in: In formula (5), k v Indicates the chemical reaction rate between corrosive ions in concrete and concrete hydrates, s -1 ; Indicates the concentration of calcium ions in the concrete pore solution, mol / m 3 ; Chemical damage based on the definition of concrete volume expansion strain is used to describe the degradation of mechanical properties caused by sulfate attack: In formula (6), k and m are model parameters related to concrete materials and erosion conditions; ε ep0 is the critical expansion strain for chemical damage to concrete; ep It is the volume expansion strain caused by products such as ettringite.

6. The method for advanced identification of weak locations in immersed tunnel structures according to claim 5, characterized in that: In S4, based on the actual size of the immersed tube tunnel on site, a three-dimensional finite element model of the immersed tube tunnel is drawn in the finite element numerical simulation software, the established three-dimensional finite element model of the immersed tube tunnel is meshed, and the mesh quality assessment function of the finite element software is used to assess the quality of the meshing until the meshing quality meets the numerical simulation requirements.

7. The method for advanced identification of weak locations in immersed tunnel structures according to claim 6, characterized in that: In said S4, the method for obtaining the basic parameters of the three-dimensional finite element model of the immersed tube tunnel is: making concrete specimens based on the concrete materials used in the on-site immersed tube tunnel, carrying out triaxial compression tests, density tests, porosity tests and mineral composition analysis tests, and obtaining the strength, elastic modulus, Poisson's ratio, density, porosity and hydrate content of the immersed tube tunnel concrete.

8. The method for advanced identification of weak locations in immersed tunnel structures according to claim 7, characterized in that: In S5, determining the boundary conditions of the immersed tube tunnel three-dimensional finite element model in the finite element numerical simulation software includes the following steps: Apply force boundary conditions to the top and side walls of the immersed tunnel based on the water and soil loads calculated in S2; Apply force boundary conditions or displacement boundary conditions at both ends of the immersed tube tunnel according to the actual installation conditions on site; According to the foundation stiffness determined by S1, an elastic foundation boundary condition is applied to the bottom of the immersed tunnel.

9. An electronic device, characterized in that: include: A memory and a processor, wherein the processor is configured to implement the method for advanced identification of weak positions of immersed tube tunnel structures as described in any one of claims 1 to 8 when executing a computer management program stored in the memory.

10. A computer-readable storage medium storing a computer management program, characterized in that: When the computer management program is executed by the processor, the method for advanced identification of weak positions in the immersed tube tunnel structure according to any one of claims 1 to 5 is implemented.

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