A method, computer storage medium, and device for predicting chloride ion content.

Abstract

This invention provides a method, computer storage medium, and device for predicting chloride ion content, relating to the field of tunnel and underground structure durability life prediction technology. The prediction method includes establishing a chloride ion erosion model in the unsaturated concrete of tunnels and underground structures; substituting the pore water pressure distribution h(x), the unsaturated permeability coefficient k(h), and the unsaturated diffusion coefficient D(s) into the chloride ion erosion model to solve for the chloride ion content distribution curve; and predicting the change in chloride ion content in the concrete of tunnels and underground structures from the chloride ion content distribution curve. The computer storage medium stores computer program instructions, which are executed by a processor to implement the prediction method. The device is used to implement the prediction method. The prediction results of this invention are closer to actual engineering conditions.

Description

Technical Field

[0001] This invention relates to the field of tunnel and underground structure durability life prediction technology, specifically to a method, computer storage medium and device for predicting chloride ion content. Background Technology

[0002] With the increasing demand for convenient transportation, numerous cross-sea and cross-river tunnels have been built. However, in addition to being subjected to geological pressure, these tunnels also face threats from environmental factors such as high water pressure and strong erosion. The combined effect of these factors seriously affects the durability of the concrete lining structure of these tunnels.

[0003] Chloride ion intrusion into concrete leading to steel reinforcement corrosion is the primary cause of durability failure in concrete lining structures of cross-sea tunnels. However, existing research on chloride ion intrusion into concrete causing steel reinforcement corrosion is largely based on the assumption of a saturated state within the concrete, utilizing convection-diffusion equations. This fails to reflect the real-world environment where saturated and unsaturated states coexist within the concrete. Furthermore, most existing studies approximate the total chloride ion content within the concrete as a substitute for the free chloride ion content in analyzing structural durability, neglecting the actual coexistence of free and bound chloride ions. Moreover, research indicates that bound chloride ions do not affect structural durability.

[0004] In summary, existing methods that rely on the assumption of a saturated state and substitute total chloride ion content for free chloride ion content in predicting structural durability are not accurate enough. Therefore, a method, computer storage medium, and device for predicting chloride ion content in tunnel and underground structure concrete that considers unsaturation effects are needed to address the problems in existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a method, computer storage medium, and device for predicting chloride ion content. The specific technical solution is as follows:

[0006] In a first aspect, the present invention provides a method for predicting chloride ion content, comprising:

[0007] Step S1: Collect the total chloride ion content, free chloride ion content, bound chloride ion content and pore water pressure in the tunnel and underground structure concrete; collect the chloride ion content, water-facing pressure and thickness of the tunnel and underground structure concrete on the water-facing side; and establish a chloride ion erosion model in the tunnel and underground structure concrete under unsaturated conditions.

[0008] Step S2: Calculate the seepage field distribution in the concrete of the tunnel and underground structure to obtain the pore water pressure distribution h(x); determine the unsaturated permeability coefficient k(h) and unsaturated diffusion coefficient D(s) at each location in the concrete of the tunnel and underground structure.

[0009] Substituting the pore water pressure distribution h(x), unsaturated permeability coefficient k(h), and unsaturated diffusion coefficient D(s) into the chloride ion erosion model, the chloride ion content distribution curve is solved, and the chloride ion content distribution curve is used to predict the change of chloride ion content in the concrete of tunnels and underground structures.

[0010] Optionally, in step S1, the chloride ion erosion model is Equation (1):

[0011]

[0012] In equation (1), C t C represents the total chloride ion content in the concrete of tunnels and underground structures. t =C f +C b C f Indicates the content of free chloride ions in the concrete of tunnels and underground structures; C b This indicates the content of bound chloride ions in the concrete of tunnels and underground structures. The reciprocal of the chloride ion binding affinity. Where α and β are model parameters related to the tunnel and underground structure concrete, determined by conducting Langmuir isothermal adsorption tests; t represents time; x represents the distance from the water-facing side of the tunnel and underground structure concrete; and h represents the pore water pressure inside the tunnel and underground structure concrete.

[0013] Optionally, in step S2, the seepage field distribution is represented by equation (2):

[0014]

[0015] In equation (2), S e =1 / [1+|ah(x)| n ] m C m S represents the unit volumetric water content of concrete in tunnels and underground structures. e The effective saturation degree of concrete in tunnels and underground structures is represented, with a value ranging from 0 to 1; S represents the water storage coefficient; θ s Indicates saturated water content; θ r This represents the residual moisture content; parameters a, l, m, and n are model parameters related to the type of concrete used in tunnels and underground structures. Parameters a and m are determined by measuring the moisture characteristic curves of concrete used in tunnels and underground structures.

[0016] Alternatively, the parameters m and l may satisfy the following equation (3):

[0017]

[0018] Optionally, in step S2, the process of obtaining the pore water pressure distribution h(x) at the target time using the seepage field distribution includes:

[0019] The solution domain {0≤x≤L;0≤t≤T′} is determined, and the solution domain is discretized into discrete points denoted by subscripts (i,j).

[0020]

[0021] Where x represents the distance from the water-facing side of the tunnel and underground structure concrete; L represents the thickness of the tunnel and underground structure concrete; x i The coordinates of the discretized concrete nodes are represented by Δx; the distance discretization step size is represented by t; the time interval between the initial time and the target time is represented by T′; and t' represents the target time. j The coordinates of the time nodes are discretized; Δt represents the time discretization step length; I represents the number of discretized distance segments; J represents the number of discretized time segments.

[0022] When the target time is the initial time, i.e., j=1, η1 is the water-facing pressure p0 of the tunnel and underground structure concrete; η1, η2 to All values ​​are taken as the initial pore pressure h0;

[0023] The matrix expression A1X1=B1 is constructed using the finite difference method, and p0 and h0 are substituted into the matrix expression A1X1=B1 to obtain the pore water pressure distribution h(x) at the target time.

[0024] set up:

[0025]

[0026]

[0027]

[0028] In vectors A1, X1, and B1, the indices of each element are respectively related to x. i The subscripts in the vectors correspond one-to-one; the superscripts of each element in vectors A1, X1, and B1 correspond to t respectively. j The subscripts in the vector correspond one-to-one; in vector A1, α i Represents the discretized concrete node coordinates x i The corresponding internal values ​​α, β of the matrix i Represents the discretized concrete node coordinates xi The corresponding internal values ​​β, γ of the matrix i Represents the discretized concrete node coordinates x i The corresponding internal value γ of the matrix; the vector X1 represents the coordinates of h(x) at the discretized concrete nodes x1, x2, ..., x3. I-1 x I x I+1 The pore water pressure at the location, where h1 represents h(x1), h2 represents h(x2), ..., h i h(x) represents I ), h I+1 h(x) represents I+1 In vector B1, η i Represents the discretized concrete node coordinates x i The corresponding internal value η of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value α of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value β of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value γ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value η of the matrix; Let x represent the discretized coordinates of the concrete node at time j. i The corresponding pore water pressure h; This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value A(h) inside the matrix corresponding to the middle position; This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value A(h) inside the matrix corresponding to the middle position; Let x represent the discretized coordinates of the concrete node at time j. i The corresponding internal value of the matrix is ​​A(h); Let x represent the discretized coordinates of the concrete node at time j. i-1 The corresponding internal value of the matrix is ​​A(h); Let x represent the discretized coordinates of the concrete node at time j. i+1 The value A(h) inside the matrix corresponding to the position; This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1The value k(h) inside the matrix corresponding to the middle position; This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value k(h) inside the matrix corresponding to the middle position; Let x represent the discrete coordinates of the concrete node at time j. i The corresponding internal value of the matrix is ​​k(h); Let x represent the discretized coordinates of the concrete node at time j. i-1 The corresponding internal value of the matrix is ​​k(h); This represents the discretized coordinates of the concrete node x at time j+1. i+1 The value k(h) inside the matrix corresponding to the position.

[0029] Optionally, the initial pore pressure h0 in the concrete of the tunnel and underground structure can be calculated using equation (4):

[0030]

[0031] In equation (4), S e0 This indicates the initial saturation of concrete in tunnels and underground structures.

[0032] Optionally, in step S2, the unsaturated permeability coefficient k(h) and the unsaturated diffusion coefficient D(s) are calculated using equation (5):

[0033]

[0034] In equation (5), D s The saturated diffusion coefficient of concrete in tunnels and underground structures is represented by ψ; the diffusion equation coefficient is k. r Represents the relative permeability coefficient; k s This represents the saturated permeability coefficient of concrete in tunnels and underground structures.

[0035] Optionally, in step S2, the process of solving the chloride ion content distribution curve includes:

[0036] Determine the initial chloride ion content C0 and the chloride ion content C on the water-facing side of the concrete in the tunnel and underground structure. i ;

[0037] The matrix expression A2X2=B2 is constructed using the finite difference method, and C0 and C... i Substituting into the matrix expression A2X2=B2, we obtain the chloride ion content distribution curve V(C) at the target time. f );

[0038] set up:

[0039]

[0040]

[0041]

[0042] In vectors A2, X2, and B2, the indices of each element are respectively related to x. i The subscripts in the vectors correspond one-to-one, and the superscripts of each element in vectors A2, X2, and B2 correspond to t respectively. j The subscripts in the vector A2 correspond one-to-one; in vector A2, σ i Represents the discretized concrete node coordinates x i The corresponding internal value σ of the matrix, Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix τ i Represents the discretized concrete node coordinates x i The corresponding internal value τ of the matrix; the vector X2 represents the coordinates of the discrete concrete nodes x1, x2, ..., x3. I-1 x I x I+1 The chloride ion content at point B; in vector B2, ξ i Represents the discretized concrete node coordinates x i The corresponding internal value ξ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value σ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal values ​​of the matrix This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value τ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value ξ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value B(C) inside the matrix corresponding to the middle position f ); This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value B(C) inside the matrix corresponding to the middle position f ); Let x represent the discretized coordinates of the concrete node at time j.i-1 The value B(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i+1 The value B(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i The value B(C) inside the matrix corresponding to the position f ); This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value V(C) inside the matrix corresponding to the middle position f ); This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value V(C) inside the matrix corresponding to the middle position f ); Let x represent the discretized coordinates of the concrete node at time j. i-1 The value V(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i+1 The value V(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i The value V(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i The content of free chloride ions corresponding to the location; This represents the discretized coordinates of the concrete node x at time j+1. i The content of free chloride ions corresponding to the location.

[0043] In a second aspect, the present invention provides a computer storage medium storing computer program instructions, which, when executed by a processor, implement the method for predicting chloride ion content.

[0044] In a third aspect, the present invention provides an apparatus comprising: at least one processor, at least one memory, and computer program instructions stored in the memory, wherein the computer program instructions are executed by the processor to perform the method for predicting chloride ion content.

[0045] The application of the technical solution of the present invention has at least the following beneficial effects:

[0046] (1) This invention provides a method for predicting chloride ion content. Starting from the chloride ion transport mechanism in tunnel and underground structure concrete, it comprehensively considers the influence of chloride ion binding effect, diffusion, and convection effect on chloride ion transport, establishing a nonlinear convection-diffusion erosion model of chloride ions in unsaturated tunnel and underground structure concrete, i.e., a chloride ion erosion model. This chloride ion erosion model has higher accuracy and considers a wider range of chloride transport mechanisms, providing a theoretical basis for future durability design research of submarine concrete tunnels and guiding the durability design of similar related projects. Furthermore, this invention considers the real environment where saturated and unsaturated states coexist in tunnel and underground structure concrete, distinguishing between free chloride ions and bound chloride ions in the concrete, and provides an efficient numerical solution method for the chloride ion erosion model. Compared with other calculation methods, the chloride ion erosion model of tunnel and underground structure concrete provided by this invention is closer to actual engineering conditions.

[0047] (2) The present invention provides a computer storage medium for storing computer program instructions, which, when executed by a processor, implement the method for predicting chloride ion content.

[0048] (3) The present invention provides a device for implementing the method for predicting chloride ion content.

[0049] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0050] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0051] Figure 1 This is a flowchart illustrating a method for predicting chloride ion content in concrete for tunnels and underground structures, as described in an embodiment of the present invention.

[0052] Figure 2 This is a diagram of the pore water pressure distribution h(x) in an embodiment of the present invention;

[0053] Figure 3 The effective saturation S of the tunnel and underground structure concrete in the embodiments of the present invention is... e Line graph;

[0054] Figure 4 This is a graph of the unsaturated permeability coefficient k(h) in an embodiment of the present invention;

[0055] Figure 5This is a graph of the unsaturated diffusion coefficient D(s) in an embodiment of the present invention;

[0056] Figure 6 This is a graph showing the change in chloride ion content in an embodiment of the present invention;

[0057] Among them, Figures 2-6 The terms "10a", "50a", and "100a" appearing in the text represent 10 years, 50 years, and 100 years, respectively; Figures 2-6 The term "inner side" in this context refers to the side of the tunnel and underground structure concrete that is furthest from the water-facing side. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0059] Example:

[0060] See Figure 1 A method for predicting chloride ion content in concrete for tunnels and underground structures, comprising:

[0061] Step S1: Collect the total chloride ion content, free chloride ion content, bound chloride ion content and pore water pressure in the concrete of the tunnel and underground structure; collect the chloride ion content, water-facing pressure and thickness of the concrete on the water-facing side of the tunnel and underground structure; and establish a chloride ion erosion model in the concrete of the tunnel and underground structure (specifically a cross-sea tunnel) under unsaturated conditions.

[0062] Step S2: Calculate the seepage field distribution in the concrete of the tunnel and underground structure to obtain the pore water pressure distribution h(x); determine the unsaturated permeability coefficient k(h) and unsaturated diffusion coefficient D(s) at each location in the concrete of the tunnel and underground structure.

[0063] Substituting the pore water pressure distribution h(x), unsaturated permeability coefficient k(h), and unsaturated diffusion coefficient D(s) into the chloride ion erosion model, the chloride ion content distribution curve is solved, and the chloride ion content distribution curve is used to predict the change of chloride ion content in the concrete of tunnels and underground structures.

[0064] In step S1, the chloride ion erosion model is Equation (1):

[0065]

[0066] In equation (1), C t C represents the total chloride ion content in the concrete of tunnels and underground structures.t =C f +C b C f Indicates the content of free chloride ions in the concrete of tunnels and underground structures; C b This indicates the content of bound chloride ions in the concrete of tunnels and underground structures. The value represents the reciprocal of the chloride ion binding capacity; t represents time; x represents the distance from the water-facing side of the tunnel and underground structure concrete; and h represents the pore water pressure within the tunnel and underground structure concrete.

[0067] Here, α and β are model parameters related to the concrete of the tunnel and underground structure, which are routinely determined through Langmuir isothermal adsorption tests. Specifically, α = 0.02 and β = 468.1.

[0068] In step S2, the seepage field distribution is represented by equation (2):

[0069]

[0070] In equation (2), S e =1 / [1+|ah(x)| n ] m C m S represents the unit volumetric water content of concrete in tunnels and underground structures. e The effective saturation degree of concrete in tunnels and underground structures is represented, with a value ranging from 0 to 1; S represents the water storage coefficient; θ s This represents the saturated water content, specifically a value of 0.04; θ r The value represents the residual moisture content, specifically 0. Parameters a, l, m, and n are model parameters related to the type of concrete used in tunnels and underground structures. Parameters a and m are determined conventionally by measuring the moisture characteristic curves of concrete used in tunnels and underground structures.

[0071] The parameters m and l satisfy the following equation (3):

[0072]

[0073] Specifically, a = 5.37 × 10 -4 ; l=0.646; m=0.44; n=1.78.

[0074] In step S2, the process of obtaining the pore water pressure distribution h(x) at the target time using the seepage field distribution includes:

[0075] The solution domain {0≤x≤L;0≤t≤T′} is determined, and the solution domain is discretized into discrete points denoted by subscripts (i,j).

[0076]

[0077] Where x represents the distance from the water-facing side of the tunnel and underground structure concrete; L represents the thickness of the tunnel and underground structure concrete, specifically 0.5m; x i The coordinates of the discretized concrete nodes are represented; Δx represents the distance discretization step size, specifically 0.005m; t represents the time between the initial time and the target time; T′ represents the target time, specifically 100 years; t j Δt represents the time node coordinates after discretization; Δt represents the time discretization step length, specifically 1 year; I represents the number of discretized distance segments, specifically 100 distance segments; J represents the number of discretized time segments, specifically 100 time segments.

[0078] When the target time is the initial time, i.e., j=1, η1 is the water-facing pressure p0 of the tunnel and underground structure concrete; η1, η2 to All values ​​are taken as the initial pore pressure h0;

[0079] The matrix expression A1X1=B1 is constructed using the finite difference method, and p0 and h0 are substituted into the matrix expression A1X1=B1 to obtain the pore water pressure distribution h(x) at the target time.

[0080] set up:

[0081]

[0082]

[0083]

[0084] In vectors A1, X1, and B1, the indices of each element are respectively related to x. i The subscripts in the vectors correspond one-to-one; the superscripts of each element in vectors A1, X1, and B1 correspond to t respectively. j The subscripts in the vector correspond one-to-one; in vector A1, α i Represents the discretized concrete node coordinates x i The corresponding internal values ​​α, β of the matrix i Represents the discretized concrete node coordinates x i The corresponding internal values ​​β, γ of the matrix i Represents the discretized concrete node coordinates x i The corresponding internal value γ of the matrix; the vector X1 represents the coordinates of h(x) at the discretized concrete nodes x1, x2, ..., x3. I-1 x I x I+1The pore water pressure at the location, where h1 represents h(x1), h2 represents h(x2), ..., h i h(x) represents I ), h I+1 h(x) represents I+1 In vector B1, η i Represents the discretized concrete node coordinates x i The corresponding internal value η of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value α of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value β of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value γ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value η of the matrix; Let x represent the discretized coordinates of the concrete node at time j. i The corresponding pore water pressure h; This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value A(h) inside the matrix corresponding to the middle position; This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value A(h) inside the matrix corresponding to the middle position; Let x represent the discretized coordinates of the concrete node at time j. i The corresponding internal value of the matrix is ​​A(h); Let x represent the discretized coordinates of the concrete node at time j. i-1 The corresponding internal value of the matrix is ​​A(h); Let x represent the discretized coordinates of the concrete node at time j. i+1 The value A(h) inside the matrix corresponding to the position; This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value k(h) inside the matrix corresponding to the middle position; This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value k(h) inside the matrix corresponding to the middle position; Let x represent the discrete coordinates of the concrete node at time j. i The corresponding internal value of the matrix is ​​k(h); Let x represent the discretized coordinates of the concrete node at time j. i-1 The corresponding internal value of the matrix is ​​k(h); This represents the discretized coordinates of the concrete node x at time j+1. i+1 The value k(h) inside the matrix corresponding to the position.

[0085] In this embodiment, the following is calculated during the first iteration of the matrix expression A1X1=B1:

[0086]

[0087]

[0088] The pore water pressure distribution h(x) within the concrete of the tunnel and underground structure over 10, 50, and 100 years was calculated by applying the matrix expression A1X1=B1 to 10, 50, and 100 iterations, respectively. (See [reference]). Figure 2 When the distance x from the water-facing side of the tunnel and underground structure concrete remains constant, the pore water pressure increases with the extension of time t; when time t remains constant, the pore water pressure decreases with the increase of distance x from the water-facing side of the tunnel and underground structure concrete. This indicates that the pore water pressure distribution in the tunnel and underground structure concrete is related to time t and distance x from the water-facing side of the tunnel and underground structure concrete. Specifically, the longer the time t, the higher the pore water pressure; the closer to the water-facing side, the higher the pore water pressure.

[0089] Substitute h(x) into S e =1 / [1+|ah(x)| n ] m Calculate S e For details of the changes, please refer to [link / reference]. Figure 3 With a constant distance *x* from the water-facing side of the tunnel and underground structure concrete, the effective saturation of the concrete increases with increasing time *t*. Conversely, with a constant time *t*, the effective saturation of the concrete decreases with increasing distance *x* from the water-facing side. This indicates that the distribution of effective saturation within the tunnel and underground structure concrete is related to both time *t* and the distance *x* from the water-facing side. Specifically, the longer the time *t*, the higher the effective saturation; and the closer to the water-facing side, the higher the effective saturation. Furthermore, from S... e The relationship between h(x) and the calculation results shows that the higher the pore water pressure, the lower the effective saturation.

[0090] The initial pore pressure h0 in the concrete of the tunnel and underground structure is calculated using equation (4):

[0091]

[0092] In equation (4), S e0 This indicates the initial saturation of the concrete in the tunnel and underground structure, specifically a value of 0.8.

[0093] The initial pore pressure h0 in the concrete of the tunnel and underground structure is calculated to be -14.76 MPa by equation (4).

[0094] In step S2, the unsaturated permeability coefficient k(h) and the unsaturated diffusion coefficient D(s) are calculated using equation (5):

[0095]

[0096] In equation (5), D s This represents the saturated diffusion coefficient of concrete in tunnels and underground structures, specifically taken as 3.0 ×

[0097] 10 -12 m 2 / s; ψ is the coefficient of the diffusion equation, specifically taking a value of 1; k r Represents the relative permeability coefficient; k s This represents the saturated permeability coefficient of concrete in tunnels and underground structures, specifically taken as 7.2 × 10⁻⁶. -15 m / s.

[0098] For details on the unsaturated permeability coefficient k(h) and unsaturated diffusion coefficient D(s) calculated using equation (5), please refer to [reference needed]. Figure 4 and Figure 5 .

[0099] exist Figure 4 In the study, with the distance *x* from the water-facing side of the tunnel and underground structure concrete remaining constant, the unsaturated permeability coefficient *k(h)* increases with increasing time *t*; conversely, with time *t* remaining constant, the unsaturated permeability coefficient *k(h)* decreases with increasing distance *x* from the water-facing side of the tunnel and underground structure concrete. This indicates that the distribution of the unsaturated permeability coefficient within the tunnel and underground structure concrete is related to both time *t* and the distance *x* from the water-facing side. Specifically, the longer the time *t*, the higher the unsaturated permeability coefficient *k(h)*; and the closer to the water-facing side, the higher the unsaturated permeability coefficient *k(h)*. Furthermore, from *k(h)*, *k*... r S e The relationship between k(h) and h(x) shows that k(h) is related to the pore water pressure.

[0100] exist Figure 5In the study, with the distance *x* from the water-facing side of the tunnel and underground structure concrete remaining constant, the unsaturated diffusion coefficient *D(s)* increases with increasing time *t*; conversely, with time *t* remaining constant, the unsaturated diffusion coefficient *D(s)* decreases with increasing distance *x* from the water-facing side of the tunnel and underground structure concrete. This indicates that the distribution of the unsaturated diffusion coefficient within the tunnel and underground structure concrete is related to both time *t* and the distance *x* from the water-facing side. Specifically, the longer the time *t*, the higher the unsaturated diffusion coefficient *D(s)*; and the closer to the water-facing side, the higher the unsaturated diffusion coefficient *D(s)*. Furthermore, from *D(s)*, *S*... e The relationship between h(x) and the calculation results show that the higher the pore water pressure, the lower the effective saturation and the lower the unsaturated diffusion coefficient.

[0101] In step S2, the process of solving the chloride ion content distribution curve includes:

[0102] Determine the initial chloride ion content C0 in the concrete of the tunnel and underground structure (specifically, the value is 0) and the chloride ion content C on the water-facing side of the concrete of the tunnel and underground structure. i (The specific value is 0.5wt%);

[0103] The matrix expression A2X2=B2 is constructed using the finite difference method, and C0 and C... i Substituting into the matrix expression A2X2=B2, we obtain the chloride ion content distribution curve V(C) at the target time. f );

[0104] set up:

[0105]

[0106]

[0107]

[0108] In vectors A2, X2, and B2, the indices of each element are respectively related to x. i The subscripts in the vectors correspond one-to-one, and the superscripts of each element in vectors A2, X2, and B2 correspond to t respectively. j The subscripts in the vector A2 correspond one-to-one; in vector A2, σ i Represents the discretized concrete node coordinates x i The corresponding internal value σ of the matrix, Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix τ i Represents the discretized concrete node coordinates x iThe corresponding internal value τ of the matrix; the vector X2 represents the coordinates of the discrete concrete nodes x1, x2, ..., x3. I-1 x I x I+1 The chloride ion content at point B; in vector B2, ξ i Represents the discretized concrete node coordinates x i The corresponding internal value ξ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value σ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal values ​​of the matrix This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value τ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i The corresponding internal value ξ of the matrix; This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value B(C) inside the matrix corresponding to the middle position f ); This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value B(C) inside the matrix corresponding to the middle position f ); Let x represent the discretized coordinates of the concrete node at time j. i-1 The value B(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i+1 The value B(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i The value B(C) inside the matrix corresponding to the position f ); This represents the discretized coordinates of the concrete node x at time j+1. i and x i-1 The value V(C) inside the matrix corresponding to the middle position f ); This represents the discretized coordinates of the concrete node x at time j+1. i and x i+1 The value V(C) inside the matrix corresponding to the middle position f ); Let x represent the discretized coordinates of the concrete node at time j. i-1 The value V(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i+1 The value V(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i The value V(C) inside the matrix corresponding to the position f ); Let x represent the discretized coordinates of the concrete node at time j. i The content of free chloride ions corresponding to the location; This represents the discretized coordinates of the concrete node x at time j+1. i The content of free chloride ions corresponding to the location.

[0109] In this embodiment, the following is calculated during the first iteration of the matrix expression A2X2=B2:

[0110]

[0111]

[0112] After the matrix expression A2X2=B2 is iterated 10, 50, and 100 times respectively, the chloride ion content distribution curves in the lining concrete over 10, 50, and 100 years are obtained. See [link / reference]. Figure 6 .

[0113] exist Figure 6 In the study, with the distance x from the water-facing side of the tunnel and underground structure concrete remaining constant, the chloride ion content increased with the extension of time t; conversely, with time t remaining constant, the chloride ion content decreased with the increase of the distance x from the water-facing side of the tunnel and underground structure concrete. This indicates that the chloride ion distribution in the tunnel and underground structure concrete is related to both time t and the distance x from the water-facing side of the tunnel and underground structure concrete. Specifically, the longer the time t, the higher the chloride ion content; and the closer to the water-facing side, the higher the chloride ion content.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for predicting chloride ion content, characterized in that, include: Step S1: Establish a chloride ion erosion model in tunnel and underground structure concrete under unsaturated conditions; Step S2: Calculate the seepage field distribution within the concrete of the tunnel and underground structure to obtain the pore water pressure distribution. h ( x Determine the unsaturated permeability coefficient at various locations within the concrete of the tunnel and underground structures. k ( h ) and unsaturated diffusion coefficient D ( s ); Pore ​​water pressure distribution h ( x Unsaturated permeability coefficient k ( h ) and unsaturated diffusion coefficient D ( s Substitute the chloride ion erosion model into the chloride ion content distribution curve and predict the chloride ion content changes in the concrete of tunnels and underground structures from the chloride ion content distribution curve; In step S1, the chloride ion erosion model is Equation (1): Equation (1); In equation (1), C t This indicates the total chloride ion content within the concrete of tunnels and underground structures. = + ; This indicates the content of free chloride ions in the concrete of tunnels and underground structures. This indicates the content of bound chloride ions in the concrete of tunnels and underground structures. The reciprocal of the chloride ion binding affinity. ,in, α , β Model parameters related to tunnel and underground structure concrete were determined by conducting Langmuir isothermal adsorption tests. Indicates time; This indicates the distance from the water-facing side of the tunnel and underground structure concrete. h This indicates the pore water pressure within the concrete of tunnels and underground structures. In step S2, the seepage field distribution is represented by equation (2): Equation (2); In equation (2), ; ; C m This indicates the unit volumetric water content of concrete in tunnels and underground structures. S e This represents the effective saturation degree of concrete in tunnels and underground structures, with a value ranging from 0 to 1. S Indicates the water storage coefficient; θ s Indicates saturated moisture content; θ r Indicates residual moisture content; parameter a , l , m and n For model parameters related to the concrete category of tunnels and underground structures, the parameters are... a and m The moisture content was determined by measuring the moisture characteristic curves of the concrete in the tunnel and underground structure, respectively.

2. The method for predicting chloride ion content according to claim 1, characterized in that, parameter m and l Satisfy the following equation (3): Equation (3).

3. The method for predicting chloride ion content according to claim 2, characterized in that, In step S2, the pore water pressure distribution at the target time is obtained using the seepage field distribution. h ( x The process includes: Determine the solution domain {0≤ x ≤ L ;0≤ t ≤ Tʹ }, and discretize the solution domain using subscripts Representing discrete points ; in, This indicates the distance from the water-facing side of the tunnel and underground structure concrete. L Indicates the thickness of the concrete in tunnels and underground structures; Represents the coordinates of the discretized concrete nodes; Indicates the distance from the walk; This represents the time between the initial moment and the target moment. Tʹ Indicates the target time; Represents the coordinates of the discrete time nodes; This indicates that the time is long since the walk; This represents the number of discrete distance segments; Indicates the number of discrete time segments; When the target time is the initial time, that is j =1, η 1 represents the water-facing pressure of the concrete in tunnels and underground structures. p 0; η 1. η 2 to η i+1 All values ​​are taken as initial pore pressure. h 0; Constructing matrix expressions using the finite difference method A 1 X 1= B 1, and will p 0 and h Substituting 0 into the matrix expression A 1 X 1= B 1. Obtain the pore water pressure distribution at the target time. h ( x ); set up: ; ； ； ； Among them, in vector A 1. Vector X 1 and vector B The subscripts of each element in 1 are respectively... The indices in the vector correspond one-to-one. A 1. Vector X 1 and vector B The superscripts of each element in 1 are respectively... The subscripts in the vector correspond one-to-one; A In 1, α i Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix α , β i Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix β , γ i Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix γ ;vector X 1 represents h ( x Coordinates of the discretized concrete nodes x 1. x 2、...、 x I-1 , x I , x I+1 The pore water pressure at that location, h 1 represents h ( x 1) h 2 indicates h ( x 2) ... h i express h ( x I ), h I+1 express h ( x I+1 ); in vector B In 1, η i Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix η ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix α ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix β ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time, the discretized coordinates of the concrete nodes x i Corresponding pore water pressure h ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i-1 The value inside the matrix corresponding to the middle position ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i+1 The value inside the matrix corresponding to the middle position ; express j At time, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time, the discretized coordinates of the concrete nodes x i-1 The corresponding internal values ​​of the matrix ; express j At time, the discretized coordinates of the concrete nodes x i+1 The value inside the matrix corresponding to the position ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i-1 The value inside the matrix corresponding to the middle position ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i+1 The value inside the matrix corresponding to the middle position ; Indicate j At time, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time, the discretized coordinates of the concrete nodes x i-1 The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i+1 The value inside the matrix corresponding to the position .

4. The method for predicting chloride ion content according to claim 3, characterized in that, The initial pore pressure in the concrete of tunnels and underground structures is calculated using equation (4). h 0: Equation (4); In equation (4), This indicates the initial saturation of concrete in tunnels and underground structures.

5. The method for predicting chloride ion content according to claim 4, characterized in that, In step S2, the unsaturated permeability coefficient k ( h ) and unsaturated diffusion coefficient D ( s )Calculate using formula (5): Equation (5); In equation (5), D s This represents the saturated diffusion coefficient of concrete in tunnels and underground structures. These are the coefficients of the diffusion equation; Represents the relative permeability coefficient; ; k s This represents the saturated permeability coefficient of concrete in tunnels and underground structures.

6. The method for predicting chloride ion content according to claim 5, characterized in that, In step S2, the process of solving the chloride ion content distribution curve includes: Determine the initial chloride ion content in the concrete of tunnels and underground structures. C 0 and chloride ion content on the water-facing side C i ; Constructing matrix expressions using the finite difference method A 2 X 2= B 2, and will C 0 and C i Substitute into matrix expression A 2 X 2= B 2. Obtain the chloride ion content distribution curve at the target time. V ( C f ); set up: ; ； ； ； Among them, in vector A 2. Vector X 2 and vector B The subscripts of each element in 2 are respectively... The subscripts in the vector correspond one-to-one. A 2. Vector X 2 and vector B The superscripts of each element in 2 are respectively... The subscripts in the vector correspond one-to-one; A In 2, Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix , Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix , Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix ;vector X 2 represents the coordinates of the discretized concrete nodes. x 1. x 2、...、 x I-1 , x I , x I+1 Chloride ion content at the location; in the vector B In 2, Represents the discretized concrete node coordinates x i The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i The corresponding internal values ​​of the matrix ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i-1 The value inside the matrix corresponding to the middle position ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i+1 The value inside the matrix corresponding to the middle position ; express j At time, the discretized coordinates of the concrete nodes x i-1 The value inside the matrix corresponding to the position ; express j At time, the discretized coordinates of the concrete nodes x i+1 The value inside the matrix corresponding to the position ; express j At time, the discretized coordinates of the concrete nodes x i The value inside the matrix corresponding to the position ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i-1 The value inside the matrix corresponding to the middle position ; express j At time +1, the discretized coordinates of the concrete nodes x i and x i+1 The value inside the matrix corresponding to the middle position ; express j At time, the discretized coordinates of the concrete nodes x i-1 The value inside the matrix corresponding to the position ; express j At time, the discretized coordinates of the concrete nodes x i+1 The value inside the matrix corresponding to the position ; express j At time, the discretized coordinates of the concrete nodes x i The value inside the matrix corresponding to the position ; express j At time, the discretized coordinates of the concrete nodes x i The content of free chloride ions corresponding to the location; express j+ Coordinates of the discretized concrete nodes at time 1 x i The content of free chloride ions corresponding to the location.

7. A computer storage medium, characterized in that, It stores computer program instructions that, when executed by a processor, implement the method for predicting chloride ion content as described in any one of claims 1 to 6.

8. A device, characterized in that, include: At least one processor, at least one memory, and computer program instructions stored in the memory, wherein the computer program instructions are executed by the processor using the method for predicting chloride ion content as described in any one of claims 1 to 6.

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