Method for predicting shear strength of cut-off wall slot section seam based on interface porosity

Abstract

The invention relates to a method for predicting shear strength of a cut-off wall slot section seam based on interface porosity, which belongs to the technical field of geotechnical engineering and comprises the following steps: 1) acquiring three-dimensional shape data of an upper interface and a lower interface of the seam through a high-precision three-dimensional scanning technology and performing coordinate correction; 2) determining the thickness zeta of the interface according to the deepest datum lines on the two sides of the interface to obtain the initial porosity n0 and the initial contact area A0 of the interface; 3) according to the distribution function of the vertical spacing s of the infinitesimal elements, obtaining a relational expression of the axial pressure and the void ratio n; (4) calculating the average weighted height # imgabs0 # of contact units of the upper interface and the lower interface of the joint; and (5) predicting the shear strength of the structural surface according to the interface porosity n and the average weighted height # imgabs1 #. According to the invention, based on the evolution process of the interface porosity, the shear strength of the cut-off wall slot section seam at two sides of the interface under different roughness can be effectively predicted, and a theoretical basis is provided for the anti-permeability performance evaluation of the cut-off wall.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a method for predicting shear strength of anti-seepage wall groove segments based on interface porosity. Background Art

[0002] As the core structure for improving the anti-seepage performance of earth-rock dams, the shear mechanical properties of the slot joints of the cut-off wall have a decisive influence on the overall anti-seepage effect. Compared with the main part of the cut-off wall, the mechanical properties of the slot joints are weak. In the later operation process, under the action of dam body load, high hydraulic gradient and dynamic hydraulic force, shear-induced leakage and deformation are very likely to occur, resulting in the deterioration of the long-term anti-seepage performance of the cut-off wall.

[0003] There are many factors that affect the shear mechanical properties of the interface, such as bulk strength, surface roughness, and normal stress. Among them, surface roughness is the key factor affecting the shear mechanical properties. It not only determines the size of the interface contact area, but is also directly related to the distribution and transmission of shear stress on the contact interface. The structural surface roughness coefficient (JRC) proposed by Barton is usually used to describe the roughness of the structural surface. The JRC value is generally determined by visual comparison with the 10 standard structural surface profile curves defined by Barton, and the famous JRC-JCS peak shear strength model is proposed. Later, a variety of statistical parameters were proposed to describe the roughness coefficient (JRC) of the structural surface, such as the undulation characteristic parameter (RMS), the first-order derivative of the root mean square of the slope (Z2), the structural function (SF), and the line roughness index (Rp). However, the interface of the cut-off wall slot is usually a complex three-dimensional morphology, composed of multiple section lines and forming various irregular shapes. JRC only describes the average characteristics of the cut-off wall joint surface from one direction (usually perpendicular to the main shear direction), which cannot fully reflect the three-dimensional characteristics of the cut-off wall joint surface morphology, which may lead to inaccurate prediction of the shear mechanical behavior of the cut-off wall. Grasselli et al. first defined the three-dimensional roughness parameter of the structural surface by quantifying the potential contact area of ​​the structural surface. A peak shear strength model of the structural surface was established. This model describes the roughness characteristics of the structural surface based on the fitting parameters, but the geometric meaning of the fitting parameters cannot be clearly defined. Later scholars defined a series of improved models based on the Grasselli model, such as the Chen Xi model, the Xia model, and the Yang model.

[0004] Prior to the present invention, a Chinese patent (CN115935460B) disclosed a peak shear strength model based on the microscopic changes in the three-dimensional roughness of the actual contact joint and the shear rate conditions. The existing shear model has obvious disadvantages: first, it assumes that the interfaces on both sides are perfectly fitted, and uses the roughness characteristics of the single-side interface to predict the shear strength, which cannot characterize the shear performance of the entire interface; second, it does not consider the distribution of micro-convex bodies in the actual contact part of the interface, and the evolution process of the contact micro-convex bodies under the action of normal stress. Summary of the invention

[0005] In view of this, the present invention aims at the problems and limitations in the evaluation of mechanical properties of anti-seepage wall slot segments in earth-rock dams, and provides a method for predicting the shear strength of anti-seepage wall slot segments based on interface porosity, which overcomes the problems of using single-sided interface roughness parameters to evaluate shear strength and ignoring the evolution of roughness under normal stress in traditional research.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for predicting the shear strength of a section seam of an anti-seepage wall groove based on interface porosity, a method for predicting the shear strength of a section seam of an anti-seepage wall groove based on interface porosity, characterized in that the method for predicting the shear strength of a section seam of an anti-seepage wall groove comprises:

[0008] (1) Establish a three-dimensional geometric model of the upper and lower interfaces of the anti-seepage wall groove segment, perform coordinate correction, and mesh the interface;

[0009] (2) Define the interface thickness ζ and calculate the spacing s of the mesh elements corresponding to the upper and lower interfaces i,j And the area of ​​the grid microelement, the initial porosity n0 and initial contact area A0 of the interface are obtained;

[0010] (3) Among all the interface micro-elements, determine the micro-elements whose vertical spacing s is greater than 0, and calculate the ratio of the total area of ​​these micro-elements to the total area of ​​the interface; then add the area fractions of the micro-elements whose vertical spacing is greater than a certain threshold s to obtain the normalized area fraction; determine the distribution fitting parameters of the vertical spacing according to the expression of the threshold s and the normalized area formula;

[0011] (4) The expression of interface contact area ratio and normal stress is modified, and the relationship between interface porosity and normal stress is obtained by combining the relationship between vertical spacing and normalized area in (3) and the calculation method of initial interface porosity;

[0012] (5) Among all the microelements in contact with the upper and lower interfaces, determine the height difference h of the microelements relative to the interface baseline, establish a relationship between the area ratio of the microelements with a height difference greater than a certain threshold h, and obtain the average weighted height difference

[0013] (6) According to the normal stress σ n , basic friction angle of interface Body compressive strengthσ c , interface porosity n and average weighted height difference The expression of the interface shear strength model of the cut-off wall joint is as follows:

[0014]

[0015] In the formula, Indicates that n, as well as The relevant fitting function is in the following form:

[0016]

[0017] In the formula, a, b, c are fitting parameters, n is the interface porosity, It is the weighted average height difference of the interface contact unit.

[0018] Furthermore, in step (1), the coordinates of the upper and lower interfaces of the joint are corrected and then meshed. Based on the high-precision 3D laser scanning point cloud data with a scanning accuracy of less than 0.02 mm, the interface is divided into quadrilateral mesh elements with equal spacing on the x and y axes to ensure that the area of ​​each element is equal. For the coordinate point (x, y) in each mesh element, the "cubic" interpolation method of the "griddata" function in Python is used to obtain the elevation z corresponding to the interface mesh element (i, j). i,j .

[0019] Furthermore, in the coordinate correction process of the slot segment interface scanning data, the three-dimensional point cloud data of the upper and lower interfaces are first preprocessed by denoising, removing isolated points, and filling holes in the data to ensure the integrity and reliability of the data set; then, the point cloud data are finely aligned through the closest point (ICP) algorithm to ensure that the upper and lower interface data are accurately matched in a unified reference coordinate system to eliminate deviations caused by equipment errors, environmental factors or changes in sample position; finally, the least squares method is used to quantify the residuals generated in the alignment process, optimize the alignment accuracy of the point cloud data, and ensure the accurate expression of the structural surface features.

[0020] Furthermore, the interface thickness ζ in step (2) is determined by the deepest reference lines of the upper and lower interfaces using the formula Calculate, where is the height difference of the contact element in the i-th row and j-th column of the upper interface relative to the upper interface reference line; is the height difference of the microelement corresponding to the lower interface relative to the lower interface reference line.

[0021] Furthermore, the spacing s between the upper and lower interfaces corresponding to the grid elements in step (2) is i,j The calculation formula is Store the calculation results in an array, where s i,j >0 is a non-contact mesh element, s i,j =0 is the contact mesh element; the calculation formula of the initial porosity n0 and the initial contact area A0 of the interface is:

[0022]

[0023] Where S0 is the area of ​​a single microelement, N I ,N J are the number of grids in each row and column, V V is the void volume, V total is the total volume of the interface; an is an auxiliary judgment parameter, which is 1 when the spacing between the corresponding grid elements is 0, and 0 in other cases.

[0024] Furthermore, the normalized area fraction greater than a certain threshold s in step (3) The calculation formula is

[0025]

[0026] In the formula, is the ratio of the total area of ​​the interface uncontacted microelement to the total area of ​​the interface; s max is the maximum vertical spacing of the micro-elements that are not in contact with the interface; C is the vertical spacing distribution parameter.

[0027] Furthermore, in step (4), it is assumed that the surface contact area of ​​the rock joint during shearing can be approximated by the ratio of the normal stress to the uniaxial compressive strength of the joint surface material: To determine, where A c is the contact area under the corresponding normal stress, σ n is the normal stress, σ c is the uniaxial compressive strength of the material, A is the total area; according to the initial contact area A0, the above formula is modified to

[0028]

[0029] Furthermore, the modified interface contact area A c The normalized area fraction of interfacial pores There is a corresponding quantitative relationship, which can be expressed by the formula Assume that the interface displaces s during normal stress loading. * , substituting into the above formula, we can get the relationship between the interface porosity and normal stress during normal loading as follows:

[0030]

[0031] In the formula, s * is the normal displacement during normal loading, C is the vertical spacing s distribution parameter; bn is the auxiliary judgment parameter, when the displacement spacing s between the corresponding grid microelements * When it is greater than the vertical spacing, its value is 0, indicating that contact has occurred at this time; otherwise, its value is the original value.

[0032] Furthermore, the interface axial displacement s after the normal stress loading process * , the interface thickness after loading is ζ-s * , the contact microelement of the upper and lower interfaces changes relative to the interface baseline height difference h, according to the corresponding upper and lower interface height difference The weight is used to distribute the length of the microelement being compressed or broken, calculated according to the following formula:

[0033]

[0034] In the formula, They are the height differences of the upper and lower interfaces after the normal stress loading process, corresponding to the corrected micro-elements.

[0035] Furthermore, after normal stress loading in step (5), s i,j -s * The microelement with a value of ≤0 is determined as the contact element, and the height difference distribution of the upper and lower interface contact microelement is expressed as Indicates that is the maximum value of the height difference after correction, is the total number of upper and lower interface contact elements after correction, is greater than a threshold h * The number of committee members, D is the distribution parameter; the weighted average height difference of the upper and lower interface contact micro-elements By formula Calculated as

[0036] The beneficial effects of the present invention are:

[0037] The present invention takes the roughness of the upper and lower contact surfaces of the anti-seepage wall groove section joint as the research object, defines the relationship between the porosity of the joint interface and the normal stress, comprehensively considers the contribution of the interface porosity to the interface shear behavior and the evolution process of the upper and lower interface micro-convexities under the action of normal stress, and establishes a calculation formula for the peak shear strength of the anti-seepage wall groove section interface, which can more comprehensively evaluate the anti-seepage performance of the anti-seepage wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of the method for predicting the shear strength of the anti-seepage wall groove segment seam of the present invention;

[0039] Figure 2 A three-dimensional scanning model diagram of the upper and lower sample interfaces of the present invention;

[0040] Figure 3 This is a model diagram of the slot segment interface coordinate correction result of the present invention;

[0041] Figure 4 A 100 mm×100 mm interface three-dimensional grid topographic map according to the embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the interface thickness of the present invention;

[0043] Figure 6 It is a fitting curve diagram of the interface vertical spacing s and normalized area described in the present invention.

[0044] Figure 7 This is a diagram of the initial failure morphology of the interface under different normal stress conditions of the example described in the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0048] In the above description of the present invention, it should be noted that the terms "one side", "the other side", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0049] In addition, the term "same" does not mean that the parts must be absolutely the same, but slight differences are allowed. The term "vertical" only means that the positional relationship between the parts is more vertical than "parallel", and does not mean that the structure must be completely vertical, but can be slightly tilted.

[0050] like Figure 1-6 As shown, the present invention provides a method for predicting the shear strength of the anti-seepage wall groove segment based on the interface porosity, comprising the following steps:

[0051] (1) Three test cut-off walls were built downstream of Shiziping Dam, including concrete cut-off wall and clay concrete cut-off wall. Large specimens were cut along the groove of the cut-off wall on site, and the specimens were processed into standard cubic specimens of 100 mm × 100 mm × 100 mm indoors to ensure that the groove was located in the middle of the specimen to meet the requirements of the structural surface shear test. In this example, six groups of original cut-off wall groove specimens HNT-0.5, HNT-0.6, HNT-1.2, NT-0.5, NT-0.6, and NT-1.2 were subjected to direct shear tests. Three axial pressures of 0.3, 0.6, and 1.2 MPa were determined. After obtaining the surface morphology point cloud data of the specimens, indoor direct shear tests were carried out. The results of the direct shear tests are shown in Table 1. At the same time, standard cubic compressive specimens of 150 mm × 150 mm × 150 mm were cut to measure the compressive strength σ of the concrete cut-off wall and the clay concrete cut-off wall. c They are 35.85 and 10.69MPa respectively.

[0052] The RigelScan intelligent handheld laser 3D scanner is used to perform three-dimensional scanning on the joint interface to obtain the three-dimensional point cloud data of the upper and lower interface samples. The scanning accuracy is 0.01mm and the point cloud spacing is 0.05-0.1mm. After obtaining the scanning point data, the interface model is post-processed using Cyclone 3DR software to establish a three-dimensional digital model of the interface, such as Figure 2 shown.

[0053] This embodiment implements the calculation of interface geometry model, slot interface porosity and contact microelement height difference based on Python programming, and obtains the elevation of each point corresponding to the grid coordinates according to the point cloud data interpolation, thereby establishing the structural surface geometry model;

[0054] The coordinates of the scanning data of the upper and lower interfaces of the slot segment are corrected. First, the 3D point cloud data of the upper and lower interfaces are preprocessed by reducing noise, removing isolated points, and filling holes in the data to ensure the integrity and reliability of the data set; then, the point cloud data is finely aligned through the closest point (ICP) algorithm to ensure that the upper and lower interface data are accurately matched in a unified reference coordinate system, thereby eliminating deviations caused by equipment errors, environmental factors or sample position changes; finally, the least squares method is used to quantify the residuals generated during the alignment process, optimize the alignment accuracy of the point cloud data, and ensure the accurate expression of the structural surface features, such as Figure 3 .

[0055] According to the interface size, a grid cloud map with a length and width of 100 mm is established, and the interface is divided into quadrilateral grid micro-elements with equal spacing on the x and y axes to ensure that the area of ​​each micro-element is equal. In this example, the size of each grid micro-element is 0.1 mm (see Figure 4 ), a total of 1 million grids; for the elevation z of each grid element, the “cubic” interpolation method of the “griddata” function in Python is used to perform cubic polynomial interpolation, and the elevation of each grid element is stored in an array.

[0056] (2) Define the interface thickness ζ, which is determined by the deepest reference line of the upper and lower interfaces. The formula can be used Calculate, where is the height difference of the contact element in the i-th row and j-th column of the upper interface relative to the upper interface reference line; is the height difference of the microelement corresponding to the lower interface relative to the lower interface reference line (see Figure 5 ); the elevation of each grid element is z i,j , expressed as the elevation coordinate of the grid in row i and column j, and the spacing s between the upper and lower interfaces corresponding to the grid elements i,j The calculation formula is Store the calculation results in an array, where s i,j >0 is a non-contact mesh element, s i,j = 0 is the contact mesh element; the initial porosity n0 and initial contact area A0 of the interface can be obtained according to the calculation formula:

[0057]

[0058] Where S0 is the area of ​​a single microelement, N I ,N J are the number of grids in each row and column, V V is the void volume, V total is the total volume of the interface; an is an auxiliary judgment parameter, which is 1 when the spacing between the corresponding grid elements is 0, and 0 in other cases; the calculation results of the samples are shown in Table 1.

[0059] (3) Figure 6 is a fitting curve diagram of the vertical spacing s and normalized area of ​​the interface according to the present invention, according to the formula The vertical spacing distribution parameter C can be obtained; then according to the improvement of the interface shear friction theory, the vertical displacement of the interface during normal stress loading can be obtained, and further the calculation formula of the interface porosity can be obtained:

[0060]

[0061] In the formula, s * is the normal displacement during normal loading, C is the vertical spacing s distribution parameter; bn is the auxiliary judgment parameter, when the displacement spacing s between the corresponding grid microelements * When it is greater than the vertical spacing, its value is 0, indicating that contact has occurred at this time, otherwise its value is the original value. After the normal stress loading process, the interface axially displaced s * , then the interface thickness after loading is ζ-s * The height difference h of the contact microelement of the upper and lower interfaces relative to the interface baseline has changed (see Figure 7 ), according to the height difference between the upper and lower interfaces The weight used to distribute the length of the microelement being compressed or broken can be calculated according to the following formula:

[0062]

[0063] In the formula, They are the height differences of the upper and lower interfaces after the normal stress loading process, corresponding to the micro-element correction.

[0064] (4) After normal stress loading, s i,j -s * The microelement with a value of ≤0 is determined as the contact element, and the height difference distribution of the upper and lower interface contact microelement is expressed as To indicate that is the maximum value of the height difference after correction, is the total number of upper and lower interface contact elements after correction, is greater than a threshold h * The number of committee members, D is the distribution parameter; the weighted average height difference of the upper and lower interface contact micro-elements By formula Calculated as

[0065] (5) Select complete cubic specimens of concrete anti-seepage wall and clay concrete anti-seepage wall, and use an indoor cutting machine to cut straight joint specimens along the middle. According to the direct shear test, it can be determined that the basic friction angle of the concrete specimen is 30°, and the basic friction angle of the clay concrete specimen is 25°. The weighted average height difference of each specimen interface is calculated. The peak shear strength of each sample interface can be calculated by substituting the porosity n into the following formula. The calculation results are shown in Table 1.

[0066]

[0067] Where n is the interfacial porosity, is the weighted average height difference of the interface contact unit, is the basic friction angle.

[0068] Table 1 Shear test data and model calculation results

[0069]

[0070] The average relative error δ is selected to quantify the accuracy of each model. The smaller the average relative error, the more reliable the model. The average relative error δ is calculated by the following formula

[0071]

[0072] In the formula, n is the number of experiments, τ pt,i is the shear strength measured in the test, τ pe,i The results show that the average error of the estimated value of the interface shear strength model derived by the present invention is 5%, which verifies the correctness and superiority of the present invention.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for predicting shear strength of anti-seepage wall slots based on interface porosity. It is characterized in that The method for predicting the shear strength of the anti-seepage wall groove segment seam comprises: (1) Establish a three-dimensional geometric model of the upper and lower interfaces of the anti-seepage wall groove segment, perform coordinate correction, and mesh the interface; (2) Define the interface thickness ζ and calculate the spacing s of the mesh elements corresponding to the upper and lower interfaces i,j And the area of ​​the grid microelement, the initial porosity n of the interface is obtained 0 and initial contact area A 0 ; (3) Among all the interface micro-elements, determine the micro-elements whose vertical spacing s is greater than 0, and calculate the ratio of the total area of ​​these micro-elements to the total area of ​​the interface; then add the area fractions of the micro-elements whose vertical spacing is greater than a certain threshold s to obtain the normalized area fraction; determine the distribution fitting parameters of the vertical spacing according to the expression of the threshold s and the normalized area formula; (4) The expression of interface contact area ratio and normal stress is modified, and the relationship between interface porosity and normal stress is obtained by combining the relationship between vertical spacing and normalized area in (3) and the calculation method of initial interface porosity; (5) Among all the microelements in contact with the upper and lower interfaces, determine the height difference h of the microelements relative to the interface baseline, establish a relationship between the area ratio of the microelements with a height difference greater than a certain threshold h, and obtain the average weighted height difference H h* ; (6) According to the normal stress σ n , basic friction angle of interface Body compressive strengthσ c , interface porosity n and average weighted height difference H h* , the expression of the interface shear strength model of the cut-off wall joint is as follows: In the formula, Indicates that n, as well as The relevant fitting function is in the following form: In the formula, a, b, c are fitting parameters, n is the interface porosity, H h* It is the weighted average height difference of the interface contact unit.

2. The method for predicting the shear strength of the anti-seepage wall groove segment based on the interface porosity according to claim 1, Features: In step (1), the coordinates of the upper and lower interfaces of the joint are corrected and then meshed. Based on high-precision 3D laser scanning point cloud data with a scanning accuracy of less than 0.02 mm, the interface is divided into quadrilateral mesh elements with equal spacing on the x and y axes to ensure that the area of ​​each element is equal. For the coordinate point (x, y) in each mesh element, the "cubic" interpolation method of the "griddata" function in Python is used to obtain the elevation z corresponding to the interface mesh element (i, j). i,j .

3. The method for predicting the shear strength of the anti-seepage wall groove segment based on interface porosity according to claim 2, Features: In the process of coordinate correction of the scanning data of the slot interface, the 3D point cloud data of the upper and lower interfaces are firstly preprocessed by noise reduction, removal of isolated points and filling of holes in the data to ensure the integrity and reliability of the data set; Subsequently, the point cloud data is finely aligned using the closest point (ICP) algorithm to ensure that the upper and lower interface data are accurately matched in a unified reference coordinate system, eliminating deviations caused by equipment errors, environmental factors, or changes in sample position. Finally, the least squares method is used to quantitatively analyze the residuals generated during the registration process to optimize the alignment accuracy of the point cloud data and ensure accurate expression of the structural surface features.

4. The method for predicting shear strength of anti-seepage wall groove segment seams based on interface porosity according to claim 1, Features: In step (2), the interface thickness ζ is determined by the deepest reference line of the upper and lower interfaces using the formula Calculate, where is the height difference of the contact element in the i-th row and j-th column of the upper interface relative to the upper interface reference line; is the height difference of the microelement corresponding to the lower interface relative to the lower interface reference line.

5. The method for predicting shear strength of anti-seepage wall groove segment seams based on interface porosity according to claim 1, Features: The spacing s between the upper and lower interfaces corresponding to the grid elements in step (2) i,j The calculation formula is Store the calculation results in an array, where s i,j >0 is a non-contact mesh element, s i,j = 0 is the contact mesh element; initial porosity of the interface n 0 and initial contact area A 0 The calculation formula is: In the formula, S 0 is the area of ​​a single infinitesimal element, N I ,N J are the number of grids in each row and column, V V is the void volume, V total is the total volume of the interface; an is an auxiliary judgment parameter, which is 1 when the spacing between the corresponding grid elements is 0, and 0 in other cases.

6. The method for predicting shear strength of anti-seepage wall groove segment seams based on interface porosity according to claim 1, Features: The normalized area fraction greater than a certain threshold s in step (3) The calculation formula is In the formula, is the ratio of the total area of ​​the interface uncontacted microelement to the total area of ​​the interface; s max is the maximum vertical spacing of the micro-elements that are not in contact with the interface; C is the vertical spacing distribution parameter.

7. The method for predicting shear strength of anti-seepage wall groove segment seams based on interface porosity according to claim 1, Features: In step (4), it is assumed that the surface contact area of ​​rock joints during shearing can be approximated by the ratio of normal stress to the uniaxial compressive strength of the joint surface material: To determine, where A c is the contact area under normal stress, σ n is the normal stress, σ c is the uniaxial compressive strength of the material, A is the total area; according to the initial contact area A 0 , modify the above formula to 8. The method for predicting the shear strength of the anti-seepage wall groove segment based on the interface porosity according to claim 7, Features: Modified interface contact area A c The normalized area fraction of interfacial pores There is a corresponding quantitative relationship, which can be expressed by the formula Assume that the interface displaces s during normal stress loading. * , substituting into the above formula, we can get the relationship between the interface porosity and normal stress during normal loading as follows: In the formula, s * is the normal displacement during normal loading, C is the vertical spacing s distribution parameter; bn is the auxiliary judgment parameter, when the displacement spacing s between the corresponding grid microelements * When it is greater than the vertical spacing, its value is 0, indicating that contact has occurred at this time; otherwise, its value is the original value.

9. The method for predicting shear strength of anti-seepage wall groove segment seams based on interface porosity according to claim 8, Features: Axial displacement of the interface after normal stress loading process s * , the interface thickness after loading is ζ-s * , the contact microelement of the upper and lower interfaces changes relative to the interface baseline height difference h, according to the corresponding upper and lower interface height difference The weight is used to distribute the length of the microelement being compressed or broken, calculated according to the following formula: In the formula, They are the height differences of the upper and lower interfaces after the normal stress loading process, corresponding to the corrected micro-elements.

10. The method for predicting shear strength of anti-seepage wall groove segment seams based on interface porosity according to claim 1, Features: Step (5) After normal stress loading, s i,j -s * The microelement with a value of ≤0 is determined as the contact element, and the height difference distribution of the upper and lower interface contact microelement is expressed as Indicates that is the maximum value of the height difference after correction, is the total number of upper and lower interface contact elements after correction, is greater than a threshold h * The number of committee members, D is the distribution parameter; the weighted average height difference of the upper and lower interface contact micro-elements By formula Calculated as

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