A method and system for modifying a grasselli shear strength model

Abstract

The application relates to the technical field of digital data processing, and provides a correction method and system of a Grasselli shear strength model. The method comprises the following steps: using rock samples obtained in advance to prepare a plurality of structural surface samples; reconstructing the structural surface of each structural surface sample according to the result of a three-dimensional laser scanning test, so as to record the topographic features of each structural surface sample before and after shearing, and lay a data foundation for studying the peak shear strength of the structural surface. According to the topographic features of each structural surface sample before and after shearing, in combination with the test data provided by the existing research, the relationship between each topographic parameter in the Grasselli topographic characterization method and the roughness of the structural surface is analyzed. According to the analysis result, the Grasselli topographic characterization method is simplified, and a new topographic index C' is determined, and on this basis, the Grasselli shear strength model is corrected by using the new topographic index C', so that a corrected peak shear strength model of the structural surface is obtained. The method can ensure the prediction accuracy of the shear strength and simplify the model.

Description

Technical Field

[0001] This application relates to the field of digital data processing technology, and in particular to a method, system, computer-readable storage medium, and electronic device for correcting the Grasselli shear strength model. Background Technology

[0002] The shear mechanical properties of structural surfaces are a key factor affecting the stability of engineering rock masses. Among the many indicators influencing the shear mechanical properties of structural surfaces, surface roughness has become a research hotspot due to its complexity and difficulty in quantification. Domestic and international scholars have conducted in-depth research on the roughness of structural surfaces and, based on this, have established a series of peak shear strength models that consider surface roughness. Among them, Grasselli et al., by quantifying the potential damage area of ​​structural surfaces, established a relationship between three-dimensional morphological parameters and peak shear strength to predict the peak shear strength during shear failure, known as the Grasselli shear strength model (or simply Grasselli model). The morphological parameters used in this model can be directly calculated from three-dimensional scanning data without any averaging processing, and these morphological parameters possess certain physical meanings, attracting considerable attention from scholars.

[0003] However, the applicant's analysis revealed that the Grasselli shear strength model suffers from shortcomings such as complex function forms and a lack of theoretical basis for parameter combinations. Therefore, an improved technical solution is needed to address the aforementioned deficiencies of the existing technology. Summary of the Invention

[0004] The purpose of this application is to provide a method, system, computer-readable storage medium, and electronic device for correcting the Grasselli shear strength model, so as to solve or alleviate the problems existing in the prior art.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] This application provides a method for modifying the Grasselli shear strength model, including:

[0007] Step S101: Prepare multiple structural surface specimens using pre-acquired rock specimens;

[0008] Step S102: Conduct three-dimensional laser scanning tests on each structural surface sample, and reconstruct the surface image of each structural surface sample based on the results of the three-dimensional laser scanning tests to record the morphological characteristics of each structural surface sample before and after shearing.

[0009] Step S103: Based on the morphological characteristics of the specimens on each structural surface before and after shearing, and combined with the experimental data provided by existing studies, analyze the relationship between various morphological parameters and surface roughness in the Grasselli morphological characterization method. Based on the analysis results, simplify the Grasselli morphological characterization method. The simplified Grasselli morphological characterization method is as follows:

[0010]

[0011] In the formula, C′ represents the new morphological index; Indicates the contact area ratio; A0 represents the maximum contact area ratio; θ * Indicates the apparent tilt angle;

[0012] Step S104: Based on the new morphological index C′, the Grasselli shear strength model is modified. The expression for the modified peak shear strength model of the structural surface is as follows:

[0013]

[0014] In the formula, τ represents the peak shear strength of the structural surface; σ n Indicates normal stress; σ t denoted by , f(C′) and g(C′) represent fitting functions related to the morphological index C′.

[0015] This application provides a correction system for the Grasselli shear strength model, including:

[0016] The acquisition unit is configured to prepare multiple structural surface specimens using pre-acquired rock specimens;

[0017] The test unit is configured to conduct three-dimensional laser scanning tests on each structural surface specimen, and to reconstruct the surface image of each structural surface specimen based on the results of the three-dimensional laser scanning tests, so as to record the morphological characteristics of each structural surface specimen before and after shearing.

[0018] The simplified unit is configured to analyze the relationship between various morphological parameters and surface roughness in the Grasselli morphology characterization method based on the morphological characteristics of the specimens before and after shearing, combined with experimental data provided by existing studies. Based on the analysis results, the Grasselli morphology characterization method is simplified as follows:

[0019]

[0020] In the formula, C′ represents the new morphological index; Indicates the contact area ratio; A0 represents the maximum contact area ratio; θ *Indicates the apparent tilt angle;

[0021] The correction unit is configured to correct the Grasselli shear strength model based on the new morphological index C′. The expression for the peak shear strength model of the corrected structural surface is as follows:

[0022]

[0023] In the formula, τ represents the peak shear strength of the structural surface; σ n Indicates normal stress; σ t denoted by , f(C′) and g(C′) represent fitting functions related to the morphological index C′.

[0024] This application also provides a computer-readable storage medium having a computer program stored thereon, the program being the method described in any of the above embodiments.

[0025] This application also provides an electronic device, including: a memory, a processor, and a program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method described in any of the above embodiments.

[0026] The technical solution provided in this application has the following advantages:

[0027] Multiple structural surface specimens were prepared using pre-acquired rock samples. Three-dimensional laser scanning experiments were conducted on each specimen, and the surface images of each specimen were reconstructed based on the results to record the morphological characteristics of each specimen before and after shearing, laying a data foundation for studying the peak shear strength of the structural surfaces. Based on the morphological characteristics of each specimen before and after shearing, and combined with experimental data from existing studies, the relationship between various morphological parameters and surface roughness in the Grasselli morphological characterization method was analyzed to gain a deeper understanding of the limitations of these parameters. Based on the analysis results, the Grasselli morphological characterization method was simplified, and a new morphological index C′ was determined. Based on this, the Grasselli shear strength model was modified using the new index C′, resulting in a modified peak shear strength model for the structural surfaces. Compared to the Grasselli morphological characterization method which uses the maximum contact area ratio A0 and the maximum apparent tilt angle... The roughness of the structural surface is determined by three morphological parameters, namely the distribution parameter C. The solution provided in this application only requires a single morphological index C′ to determine the roughness of the structural surface, and this simplification does not cause significant error.

[0028] For the Grasselli morphology characterization method, the maximum contact area ratio A0 and the maximum apparent tilt angle are... The distribution parameter C and the three morphological parameters lack theoretical basis and are used... Using it to express the roughness of the structural surface also lacks a reasonable explanation. In this application, 90° / (C′+1) has a clear geometric meaning, that is, it represents the contact area ratio. ~View tilt angle θ * The area covered by the relationship curve and the coordinate axis, and the new morphological index C′ can directly reflect the contact area ratio. ~View tilt angle θ * The shape of the relationship curve makes it more reasonable to use the new morphology index C′ to characterize the roughness of the structural surface than the traditional expression of the roughness of the structural surface. Attached Figure Description

[0029] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0030] Figure 1 This is a flowchart illustrating a method for correcting the Grasselli shear strength model according to some embodiments of this application.

[0031] Figure 2 This is a schematic diagram of the shear failure process of an unfilled structural surface according to some embodiments of this application.

[0032] Figure 3 This is a partially enlarged schematic diagram of a triangular unit provided according to some embodiments of this application.

[0033] Figure 4 This is a schematic diagram of a shear geometry model of a single micro-protrusion provided according to some embodiments of this application.

[0034] Figure 5 To analyze the maximum apparent tilt angle under different sampling intervals based on experimental data provided by Tatone et al. A diagram illustrating the possible values ​​of .

[0035] Figure 6 Provided according to some embodiments of this application and A schematic diagram of the calculation results. Detailed Implementation

[0036] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0037] In the following description, the terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to limit this disclosure.

[0039] Example 1:

[0040] This application provides a method for correcting the Grasselli shear strength model, such as... Figure 1 As shown, the method includes:

[0041] Step S101: Prepare multiple structural surface specimens using pre-acquired rock specimens.

[0042] To quantitatively study the three-dimensional morphological characteristics of structural surfaces, a batch of rock structural surfaces needs to be fabricated.

[0043] In this embodiment, a series of sandstone samples with dimensions of 150mm × 150mm × 150mm are collected in advance. Then, an artificial structural surface is created by conducting a Brazilian splitting test using a mechanical testing system, resulting in structural surface samples with dimensions of 150mm × 150mm. After the Brazilian splitting test, the sample surface is cleaned, and qualified samples (a total of 39 pieces) are selected and numbered J1 to J39. The shear direction of each group of structural surface samples is preset for further testing.

[0044] Step S102: Conduct three-dimensional laser scanning tests on each structural surface sample, and reconstruct images of the structural surface of each structural surface sample based on the results of the three-dimensional laser scanning tests to record the morphological characteristics of each structural surface sample before and after shearing.

[0045] In this embodiment, the three-dimensional laser scanning experiment can be completed by an optical three-dimensional scanning system. This system can scan the external structure of the structural surface sample to obtain a three-dimensional data point cloud that reflects the morphological characteristics of the structural surface sample. The external structure can be reproduced by deep processing of the three-dimensional data point cloud. The higher the density of the three-dimensional data point cloud, the more accurate the result.

[0046] For example, three-dimensional laser scanning tests can be carried out on structural surface specimens J1 to J39 respectively to obtain three-dimensional data point clouds. These data points are then input into a computer, and the spatial coordinates (X, Y, Z) of each point on the surface of the structural surface specimen can be accurately calculated using three-dimensional image inverse calculation software (such as MATLAB software) and methods such as phase method and triangulation method. The measurement accuracy is 0.025 mm, so as to reproduce the surface morphology of the structural surface.

[0047] Step S103: Based on the morphological characteristics of the specimens on each structural surface before and after shearing, and combined with the experimental data provided by existing studies, analyze the relationship between various morphological parameters and surface roughness in the Grasselli morphological characterization method. Based on the analysis results, simplify the Grasselli morphological characterization method. The simplified Grasselli morphological characterization method is as follows:

[0048]

[0049] In the formula, C′ represents the new morphological index; Indicates the contact area ratio; A0 represents the maximum contact area ratio; θ * Indicates the apparent tilt angle.

[0050] To facilitate the analysis of the relationship between various morphological parameters and surface roughness in the Grasselli morphological characterization method, the existing Grasselli morphological characterization method is first explained.

[0051] Existing research indicates that when the normal stress is low, the shear-side micro-protrusions undergo shear slip along the structural surface; when the normal stress is high, the shear-side micro-protrusions may even be sheared off and crushed. Simultaneously, the back-shear-side micro-protrusions on the upper and lower structural surfaces gradually separate, forming void regions that cannot withstand shear loads. Some scholars have pointed out that the actual contact area during the shear process only accounts for a small portion of the total area of ​​the structural surface, and the area of ​​this region is related to σ. n / σ c The relationship is close, here, σ n σ represents the normal stress. c This indicates the strength of the structural rock face. Other scholars believe that the size, shape, and spatial distribution of the damaged area depend on the stress level, shear direction, and shear displacement, and that the damaged area should be located in the steepest region parallel to the shear direction.

[0052] To investigate the effect of the geometric tilt angle of micro-protrusions on shear strength, some researchers fabricated a composite sawtooth structure with two micro-protrusions, with tilt angles of 15° and 30° respectively. Figure 2 This is a schematic diagram of the shear failure process of an unfilled structural surface according to some embodiments of this application, with reference to... Figure 2 In part (a), the structural surface specimen is in an unshorn state, where D1 and D2 represent the shear-facing micro-protrusion and the back-shear-facing micro-protrusion, respectively. Figure 2 Shear tests were conducted on the composite sawtooth structure surface of (a). Figure 2 In part (b), when the normal stress is small, the micro-protrusions on the shear side undergo shear slip along the surface of the structural plane. Figure 2 In part (c), when the normal stress is large enough, the micro-protrusions on the shear side may even be sheared and crushed. Figure 2 In part (d), as shearing proceeds, the micro-protrusions at smaller angles (i.e., 15°) are damaged. Based on the experimental results, a shear stress-strain curve was plotted. The results show that the curve exhibits two peaks. Analysis revealed that the largest peak shear strength corresponds to the shear failure of the micro-protrusion at a 30° inclination angle, indicating that a larger inclination angle plays a major role in resisting shearing.

[0053] Grasselli further points out that: ① Only the micro-protrusions on the shear-facing side resist shear action, while the influence of the micro-protrusions on the back-shear side is negligible; ② The damage area during shearing is located in the steepest region on the shear-facing side. This is the theoretical basis for Grasselli's morphology characterization method and the establishment of the shear strength model.

[0054] Furthermore, in order to quantitatively analyze the morphological characteristics of the structural surface, the structural surface is discretized into a series of triangular units, which are used to represent the micro-convexity of the structural surface. Figure 3 This is a partially enlarged schematic diagram of a triangular unit provided according to some embodiments of this application, such as... Figure 3 As shown, for any triangular element, S represents the shear direction, n0 represents the outward normal vector of the shear plane, n represents the outward normal vector of the triangular element, n1 represents the projection vector of n onto the shear plane, α represents the angle between n1 and S, and θ represents the geometric tilt angle. * Indicates the apparent tilt angle.

[0055] Since there is a close relationship between the steepness and roughness of the triangular element, the contact area during the shearing process is the steeper area on the shear side. At the same time, the peak shear strength and the distribution of the damage zone are closely related to the potential contact area during the shearing process. Therefore, the potential contact area becomes a bridge to establish the relationship between the surface roughness and the peak shear strength of the structure.

[0056] Grasselli used the tilt angle θ* To represent the steepness of a triangular unit, the ratio of contact area... Let θ represent the potential contact area. Where the apparent tilt angle θ... * That is, the component of the geometric tilt angle θ in the shear direction, and the contact area ratio. That is, the potential contact area during the shearing process (A) contact ) and total area of ​​structural surfaces (A total The ratio of ).

[0057] in accordance with Figure 3 The geometric relationships shown above, and the parameters mentioned above, can be calculated using the following expression:

[0058]

[0059]

[0060] θ * =tan -1 (-tan(θ)·cos(α)),

[0061]

[0062] Based on the analysis of numerous rock structural surface morphological features, Grasselli proposed the following formula to describe the relationship between the apparent dip angle and the contact area ratio:

[0063]

[0064] In the formula, The maximum apparent tilt angle is represented by A0, which represents the maximum contact area ratio. This formula is the Grasselli morphology characterization method.

[0065] As can be seen from formula (3), the existing Grasselli morphology characterization method includes three morphology parameters: maximum contact area ratio A0, maximum apparent tilt angle, etc. And the distribution parameter C. Among them, the maximum contact area ratio A0 and the maximum apparent tilt angle The distribution parameter C is positively correlated with the potential contact area ratio, while it is negatively correlated with the potential contact area ratio. Grasselli recommends using... To quantify the roughness of the structural surface.

[0066] Although the Grasselli morphology characterization method described above is currently the most reasonable three-dimensional quantization method, it still has some shortcomings. Below, based on the morphological characteristics of the specimens before and after shearing, and combined with experimental data provided by existing research, we analyze the relationship between various morphological parameters and surface roughness in the Grasselli morphology characterization method. We specifically explain the defects of the Grasselli morphology characterization method and the improvement measures taken in this application to address these defects.

[0067] First, the Grasselli morphology characterization method includes three parameters: maximum contact area ratio A0, maximum apparent tilt angle, and maximum apparent tilt angle. And the distribution parameter C, but it is still unclear how these three parameters should be reasonably combined to represent the surface roughness of the structure and the influence of surface roughness on the peak shear strength. Although Grasselli recommends using This method quantifies the roughness of structural surfaces, but the combination of parameters lacks a reasonable explanation. For example, typically, after shearing a structural surface, micro-protrusions are crushed or sheared away, and larger protrusions are ground down, making the surface of the structural surface tend to be flat and reducing roughness. However, according to Grasselli (2001), the roughness of four sets of structural surface samples before and after shearing (i.e., The test results show that after the shear test, using The roughness (i.e. the roughness of the structural surface) expressed by this parameter becomes larger, which is inconsistent with the actual situation and also shows that this combination of parameters is imperfect.

[0068] Secondly, a specific analysis was conducted on the morphological parameter, the maximum contact area ratio A0, including: the relationship between the maximum contact area ratio A0 and the peak shear strength of specimens with different structural surfaces, the range of variation of the maximum contact area ratio A0, the relationship between the maximum contact area ratio A0 and the surface roughness, and the change of the maximum contact area ratio A0 before and after shearing of specimens with the same structural surface. It was determined that the maximum contact area ratio A0 is not suitable for describing the three-dimensional morphological characteristics of the structural surface, so that the maximum contact area ratio A0 is removed from the peak shear strength model of the structural surface.

[0069] In this embodiment, the necessity of the maximum contact area ratio A0 for predicting the peak shear strength is first analyzed, and then the relationship between the maximum contact area ratio A0 and the surface morphology and peak shear strength of different structural surface specimens is analyzed. The analysis results show that the relationship between the maximum contact area ratio A0 and the peak shear strength is not close, and it is determined that the maximum contact area ratio A0 is not suitable for describing the three-dimensional morphological characteristics of the structural surface.

[0070] (1) The maximum contact area ratio A0 is not a necessary parameter for predicting peak shear strength.

[0071] Specifically, the indoor test results provided by scholars such as Grasselli, Liu, and Zhang Xiaobo, as well as the numerical simulation results provided by scholars such as Sun Futing, all indicate that during the shear test, the structural surface on the shear-facing side gradually undergoes shear slip and is even sheared and crushed, while the structural surface on the back-shear side gradually separates and no longer resists the shear load. To simplify the problem, Grasselli (2001) believes that only the steeper region on the shear-facing side bears the shear load, while the effect of the back-shear side is almost negligible. Figure 4 This is a schematic diagram of the shear geometry model of a single micro-protrusion provided according to some embodiments of this application, based on Grasselli's views described above, referring to... Figure 4 Taking a single structural plane model as an example for analysis, it is assumed that the structural plane consists of only a single micro-protrusion, and the upper and lower structural planes are completely coupled. The inclination angle ∠OA1B5 of the micro-protrusion on the shear side is kept constant, while the inclination angle of the micro-protrusion on the back shear side is continuously varied, such as... Figure 4 As shown in the diagram, ∠OB1A1~∠OB5A1.

[0072] Analysis shows that in the shear geometry model of a single micro-protrusion with different back-shear side inclination angles (∠OB1A1~∠OB5A1), since the inclination angle ∠OA1B5 of the micro-protrusion on the shear side remains constant, the shear resistance of the micro-protrusion on the shear side is unaffected, and all normal stresses are borne by the micro-protrusion on the shear side. Therefore, according to this theory, the final peak shear strength does not change significantly. However, as the inclination angle of the back-shear side micro-protrusion changes continuously, the area of ​​the micro-protrusion on the shear side remains constant, while the total area of ​​the micro-protrusions changes. Therefore, the maximum contact area ratio A0 will also change significantly. This indicates that there is no close relationship between the maximum contact area ratio A0 and the peak shear strength. Given that the shear side structural surface is the focus of the study, the potential contact area ratio should be defined as the ratio of the actual contact area to the total area of ​​the shear side. In this case, the maximum contact area ratio A0 becomes a constant of 1.

[0073] (2) The relationship between the maximum contact area ratio A0 and the surface roughness is unclear.

[0074] Currently, the industry lacks sufficient information regarding the relationship between the maximum contact area ratio A0 and the surface roughness of the structure. If such a relationship exists, is it positive or negative? What is the functional formula characterizing this relationship? These questions remain unanswered and lack reasonable research. Under these circumstances, it is clearly inappropriate to include the maximum contact area ratio A0 in the calculation formulas for surface roughness and peak shear strength, making it a parameter characterizing the surface morphology of the structure and a factor influencing the prediction of the peak shear strength of the structure.

[0075] (3) Analyze the range of variation of the maximum contact area ratio A0.

[0076] In order to analyze the range of variation of the maximum contact area ratio A0, this embodiment calculates the value of the maximum contact area ratio A0 in different shear directions for the same structural surface sample.

[0077] For example, taking the structural surface specimen numbered J1 as an example, combined with the three-dimensional laser scanning test results of the structural surface specimen J1, the center point of the structural surface specimen J1 is taken as the origin of the coordinate axis, the horizontal leftward direction is 0° and the polar coordinate is constructed along the counterclockwise direction. The sampling is taken with 0° as the starting value and 10° as the angle interval to obtain multiple different shear directions. Then, the morphological data of the structural surface specimen J1 under different shear directions are calculated, a total of 35 groups, denoted as J1(10)~J1(350).

[0078] To analyze the variation range of the maximum contact area ratio A0, this embodiment also calculates the maximum contact area ratio A0 for different structural surface specimens, such as structural surface specimens J1 to J39, and calculates the maximum contact area ratio A0 of 10 standard JRC profile lines (numbered j1 to j10) at sampling intervals of 0.25 mm and 0.5 mm. In addition, this embodiment also compiles the values ​​of the maximum contact area ratio A0 measured by some scholars, such as the values ​​measured by Grasselli (2001), Tatone (2009), and Xia (2014). Detailed data are shown in Table 1 below:

[0079] Table 1. Values ​​of the maximum contact area ratio A0 for specimens with different structural surfaces.

[0080]

[0081]

[0082] In Table 1, the calculation results of the maximum contact area ratio A0 in rows J1 to j10 (0.5) are from the experimental data of this embodiment; the calculation results of the maximum contact area ratio A0 in S10 (0-180) to H10 (270-90) are from the experimental data provided by Yang et al. (2011); the calculation results of the maximum contact area ratio A0 in GroupⅠ to GroupⅢ are from the experimental data provided by Xia et al. (2014); the calculation results of the maximum contact area ratio A0 in 1a (0.5) to 1f (0.044) are from the experimental data provided by Tatone et al. (2009); the calculation results of the maximum contact area ratio A0 in G1 to S12 are from the experimental data provided by Yang et al. (2016b); and the calculation results of the maximum contact area ratio A0 in c1 to s2 are from the experimental data provided by Grasselli et al. (2001).

[0083] As can be seen from Table 1, although the data in the table include different rock types, sample sizes, sampling intervals, shear directions, and some data are also from two-dimensional structural profiles, the maximum contact area ratio A0 is basically concentrated between 0.45 and 0.55, with an average value of 0.5036 and a variance of 0.0012. The variation range is very small, indicating that the maximum contact area ratio A0 is a relatively fixed indicator.

[0084] In some cases, the maximum contact area ratio A0 may vary significantly with the shear direction; however, in most cases, the maximum contact area ratio A0 can be considered a constant of 0.5.

[0085] (4) Analyze the change in the maximum contact area ratio A0 of the same structural surface specimen before and after shearing.

[0086] According to the experimental data of morphological parameters of the structural surfaces before and after shearing provided by Grasselli (2001), the change rates of the maximum contact area ratio A0 after shearing relative to before shearing are 0%, 2.95%, 5.59%, and 3.12%, respectively. This indicates that the change in A0 before and after shearing is very small, and A0 cannot reflect the change in morphological characteristics before and after shearing.

[0087] Furthermore, replacing A0 with 0.5 does not significantly affect the calculation results of the Grasselli shear strength model.

[0088] In conclusion, the maximum contact area ratio A0 is not suitable for describing the three-dimensional morphological features of structural surfaces, and this indicator should be eliminated.

[0089] After a comprehensive analysis of the maximum contact area ratio A0, the maximum apparent tilt angle is analyzed in detail below.

[0090] In some embodiments, step S103, analyzing the relationship between various morphological parameters and surface roughness in the Grasselli morphology characterization method, further includes: creating multiple sets of structural surface replicas using the same structural surface as a template, and extracting the maximum apparent tilt angle of each structural surface replica at different sampling intervals. The value of is determined; a structural surface sample with good upper and lower fit is selected, and the maximum apparent tilt angle of the upper and lower structural surfaces of the coupled structural surface is extracted. The value of is analyzed; the maximum apparent tilt angle is obtained by analysis. The value of is used to determine the maximum apparent tilt angle. The value of is unstable.

[0091] First, multiple sets of structural plane replicas are created using the same structural plane as a template. The maximum apparent tilt angle of each structural plane replica is then extracted at different sampling intervals. The value of the maximum apparent tilt angle was found. The values ​​of are significantly different.

[0092] This embodiment analyzes the above-mentioned problems based on experimental data provided by Tatone et al. (2009). In their experiment, Tatone et al. created six sets of structural plane replicas using the same structural plane as a template, labeled 1a to 1f, and calculated the maximum apparent tilt angle of each structural plane replica at sampling intervals of 0.5 mm, 0.25 mm, and 0.044 mm. Maximum viewing tilt angle of structural surface replicas under different sampling intervals The values ​​are as follows Figure 5 As shown, from Figure 5 It can be seen that when the sampling interval is 0.044 mm, the maximum viewing tilt angle of replicas with different structural surfaces is... The values ​​are relatively consistent, all close to 90°. However, when the sampling interval is 0.5 mm and 0.25 mm, the maximum viewing angle of the replicas with different structural surfaces varies. The values ​​of these values ​​show significant differences, which indicates that the maximum apparent tilt angle The value of is unstable, and simply using the maximum apparent tilt angle is not feasible. It is unreasonable to use this to judge the roughness of the structural surface.

[0093] Secondly, analysis of the three-dimensional laser scanning test results of this embodiment revealed that, for the coupled structural surface, the upper and lower structural surfaces have different maximum viewing angles. The value of .

[0094] As explained above, the structural surface samples used in the three-dimensional laser scanning experiment of this embodiment are all fresh sandstone structural surfaces generated through the Brazilian splitting test. Furthermore, they underwent further selection after splitting before becoming test specimens. Therefore, the upper and lower structural surfaces have a good degree of agreement, and the morphological characteristics of the two sides are almost completely identical. Taking structural surface samples J1 to J3 as examples, the upper and lower structural surfaces were calculated respectively. The values ​​were selected, and the calculation results showed that the upper and lower structural surfaces of each group of structural surface specimens... The values ​​show significant differences, specifically in the upper structural surfaces of structural surface specimens J1 to J3. The value is relative to the lower structural surface. The errors in the values ​​were 9.95%, 20.54%, and 3.38%, respectively, further illustrating the maximum apparent tilt angle. The value of is unstable.

[0095] Secondly, maximum apparent tilt angle Variations within the specified range will not affect the structural surface morphology.

[0096] In this embodiment, in order to further investigate the maximum apparent tilt angle In addition to the features mentioned above, step S103 may also include: reducing the maximum apparent tilt angle of the structural surface specimen. The roughness and peak shear strength were calculated using the Grasselli morphology characterization method and the Grasselli shear strength model, respectively, and compared with the actual surface roughness and peak shear strength obtained from experiments to determine the maximum apparent tilt angle. Variations within the specified range do not affect the structural surface morphology, and the peak shear strength predicted by the Grasselli shear strength model varies greatly.

[0097] For example, taking structural surface specimens J1 to J3 as examples, the apparent tilt angles θ are listed respectively. * Distributed in Right now The number of triangular units within this range is shown in Table 2, which is as follows:

[0098] Table 2 Apparent tilt angle θ * exist Number of nearby triangular units

[0099]

[0100]

[0101] As can be seen from Table 2, the apparent tilt angles θ of structural surface specimens J1 to J3 are... * lie in The number of triangular elements within this range is 2, 4, and 4 respectively. Compared to the total number of triangular elements in each structural surface specimen, their number is very small and almost negligible, meaning the actual surface morphology of the structural surface remains almost unchanged. However, if these triangular elements are removed, the maximum apparent tilt angle... The value will decrease by 10°. Based on the Grasselli topography method and the Grasselli shear strength model, the calculated roughness and peak shear strength will change significantly due to the large change in peak shear strength. This is clearly inconsistent with reality, indicating that the maximum apparent tilt angle... It cannot be used alone to determine the roughness of a structural surface.

[0102] Furthermore, research indicates that although the maximum apparent tilt angle It cannot be used alone to judge the roughness of a structural surface; however, the maximum apparent tilt angle... There is a mutual influence and interdependence between the structure and the distribution parameter C. Therefore, in order to accurately represent the morphological characteristics of the structural surface, that is, to accurately determine the roughness of the structural surface, further research is needed on the maximum apparent tilt angle. The relationship between the distribution parameter C and the distribution parameter C.

[0103] In some embodiments, the maximum viewing tilt angle The relationship with the distributed parameter C is analyzed by examining the contact area ratio. ~View tilt angle θ * The relationship is realized in step S103, which involves analyzing the relationship between various morphology parameters and surface roughness in the Grasselli morphology characterization method. This also includes calculating the contact area ratio. ~View tilt angle θ * The area covered by the relationship curve and the coordinate axes is used to determine the use of To quantify the roughness of the structural surface, where C represents the distribution parameter in the Grasselli morphology characterization method.

[0104] Specifically, taking structural surface specimen J1 as an example, the morphological parameters of this specimen are as follows: A0 = 0.4911, C = 7.007, draw the contact area ratio based on the above parameters. ~View tilt angle θ * The area covered by the relationship curve and the coordinate axis can be obtained by the following integration method:

[0105]

[0106] Therefore, The physical meaning is equal to The area covered by the relationship curve and the coordinate axis is closely related to the roughness of the structural surface.

[0107] Based on the aforementioned analysis of the maximum contact area ratio A0, it is clear that the maximum contact area ratio A0 is not suitable for describing the three-dimensional morphological features of the structural surface and is no longer used as a morphological indicator. Therefore, it can be used... To quantify the roughness of the structural surface.

[0108] In some embodiments, after step S103 and before step S104, the method further includes: verifying the simplified Grasselli morphology characterization method using preset criteria to ensure accurate representation of structural surface morphology features. These criteria include at least: and The error between the two methods is less than a preset first error threshold; the error between the peak shear strength prediction result based on the simplified Grasselli morphology characterization method and the peak shear strength prediction result based on the Grasselli morphology characterization method is less than a preset second error threshold.

[0109] The steps provided in this embodiment are intended to further simplify the Grasselli morphology characterization method.

[0110] Based on the maximum apparent tilt angle Analysis shows that the maximum apparent tilt angle The value of is unstable. Further research revealed that for the same structural surface specimen, as the distribution parameter C is continuously adjusted, On the contrary, it is relatively stable.

[0111] Specifically, taking structural surface specimens J1 to J10 as examples, when the maximum apparent tilt angle As the angle is decreased sequentially by 0°, 5°, 10°, 15°, and 20°, the parameters of each structural surface specimen are calculated. The values ​​of are determined, and the results show that the maximum apparent tilt angle is... The larger the value of , the better the calculated result. The larger the value, the better, but different maximum tilt angles Values The differences in values ​​are very small and can almost be ignored. Furthermore, at different maximum apparent tilt angles... When the value is reduced by 0°, 5°, 10°, 15°, and 20° respectively, the corresponding structural surface specimen J1 is fitted. The relationship curves show that different maximum apparent tilt angles Under the given value, The relationship curves almost completely overlap, which means that even at the maximum apparent tilt angle... The value of has a certain margin of error, but by adjusting the distribution parameter C, the morphological characteristics of the structural surface can still be perfectly and accurately expressed. Therefore, it is assumed that there exists a suitable apparent tilt angle value. To replace the maximum apparent tilt angle of all structural surfaces The Grasselli morphological characterization method can then be further simplified to:

[0112]

[0113] In the formula, C′ represents the new morphological index, which is also The new fitting parameters for the relationship curve. At this point, The relationship curve will be uniquely determined by the fitting parameter C′.

[0114] To ensure that the morphological characteristics of the structural surface can be accurately expressed using formula (5), a suitable apparent tilt angle value must be determined. When the specific value is taken, The following pre-set criteria must be met: ① Applicable to all structural surface specimens; ② and The error between the two is less than the preset first error threshold, that is, the error between the two is small enough; ③ The error between the peak shear strength prediction result based on the simplified Grasselli morphology characterization method and the peak shear strength prediction result based on the unsimplified Grasselli morphology characterization method is less than the preset second error threshold, that is, the simplified Grasselli morphology characterization method will not significantly change the peak shear strength prediction result.

[0115] Since the maximum apparent tilt angle of all structural surfaces does not exceed 90°, 90° is a potentially suitable angle. Values, detailed below. It can meet the above-mentioned preset criteria.

[0116] First, verify the first criterion: it applies to all structural surface specimens.

[0117] Since the maximum apparent tilt angle of all structural surfaces does not exceed 90°, when At this point, all morphological features are manifested, exhibiting the widest applicability and satisfying the first condition. Therefore, formula (5) can be modified as follows:

[0118]

[0119] Then, verify the second criterion: and The error between them is less than the preset first error threshold.

[0120] For ease of analysis, a relative error δ is introduced, which is calculated as follows: y 计算 With y 试验 The difference between y and 试验 The ratio of y to y, where y 计算 express The calculation result, y 试验 This refers to the results of a three-dimensional laser scanning experiment.

[0121] Based on the results of the three-dimensional laser scanning test, the calculation results of each structural surface specimen (including J1 to J39 and J1(10) to J1(350)) were determined using formulas (5) and (6), respectively. and test results The values ​​and detailed morphological data are shown in Table 3, and a comparison diagram between the calculated results and the experimental results is drawn, as shown in Table 3. Figure 6 As shown.

[0122] Table 3 and Comparison

[0123]

[0124] From Table 3 and Figure 6 It can be seen that, ① and The errors between them are very small; the maximum error, minimum error, and average error among all data are 1.76%, 0.01%, and 0.37%, respectively. Generally greater than

[0125] Finally, the third criterion was verified: the simplified Grasselli morphology characterization method does not significantly change the peak shear strength prediction results.

[0126] The second criterion only explains and The results are very close, but the peak shear strength may show a large error due to accumulated errors. Therefore, verification is required. and The impact of errors between them on the prediction results of peak shear strength of structural surfaces.

[0127] To verify the third criterion, calculations were performed using the existing Grasselli shear strength model. and The peak shear strength is determined, and the error between the two values ​​is compared to see if it exceeds a preset second error threshold. Because... Generally greater than Moreover, the maximum error between the two is 1.76%, therefore using to replace This can reflect the maximum degree of error, and therefore the expression for the existing Grasselli shear strength model is:

[0128]

[0129] In the formula, τ p σ represents the peak shear strength of the Grasselli shear strength model. t Indicates tensile strength; σ n Indicates normal stress; The value represents the basic friction angle; l represents the sampling interval.

[0130] To further clarify that the simplified Grasselli morphology characterization method provided in this embodiment does not significantly alter the peak shear strength prediction results, in calculating the peak shear strength, in addition to the experimental data obtained from the aforementioned three-dimensional laser scanning experiment, a large amount of experimental data provided by existing studies was also collected. The peak shear strength of each structural surface specimen was calculated under normal stress conditions ranging from 1.0 MPa to 10 MPa. The calculation results show that, under different experimental data, the maximum error in the peak shear strength predicted by the Grasselli morphology characterization method before and after simplification is 2.73%, the minimum error is 0.12%, and the average error is 1.04%. These errors are all within acceptable ranges and do not exceed the preset second error threshold.

[0131] In summary, the simplified Grasselli morphology characterization method can express the contact area ratio using formula (6). ~View tilt angle θ * The relationship curve, and the appropriate use of C′ to describe the roughness of the structural surface, the simplified Grasselli morphology characterization method has the following advantages:

[0132] (1) The Grasselli morphological characterization method before simplification consists of three morphological parameters A0, Together with C, it determines the roughness of the structural surface, while the new roughness index only requires a single parameter C′ for judgment, and this simplification does not cause obvious errors.

[0133] (2) For the Grasselli morphology characterization method, A0, There is a lack of a reasonable combination of these three indicators (C, D, and E). Although Grasselli recommends using... This is used to represent the roughness of the structural surface, but no necessary proof is provided. Tatone et al. (2009) used... To represent the roughness of the structural surface, this formula is equal to the ratio of the contact area. ~View tilt angle θ * The area covered by the relationship curve and the coordinate axis. The expression provided in this application, 90° / (C′+1), can also quantify the contact area ratio. ~View tilt angle θ * The area covered by the relationship curve and the coordinate axes has geometric meaning; at the same time, C′ can directly reflect the shape of the fitted curve, therefore using C′ to represent the roughness of the structural surface is more accurate than... More meaningful. The simplified new morphology characterization method can perfectly describe the contact area ratio. ~View tilt angle θ * The relationship curve is such that the morphological parameter C′ becomes the characteristic index that determines the fitted curve.

[0134] To calculate the value of the new morphological index C′, a large amount of surface morphology data provided by existing research can be used to calculate the new morphological index C′. Alternatively, the new morphological index C′ can be obtained by fitting using the least squares method. Therefore, in some embodiments, after step S103 and before step S104, the method further includes: calculating the new morphological index C′ using the following formula based on experimental data provided by existing research:

[0135]

[0136] In the formula, C′ represents the new morphological index; denoted by , where represents the maximum apparent tilt angle; C represents the distribution parameter in the Grasselli topography characterization method.

[0137] or,

[0138] Based on experimental data provided by existing research, the contact area ratio under different viewing angles was calculated, and then the new morphology index C′ was solved by the least squares fitting method.

[0139] Among them, the method of directly calculating the new morphological index C′ using formula (9) is the simplest, but it may cause significant errors.

[0140] Utilizing experimental data provided in existing research literature, which includes a large amount of surface morphology data (A0, ... And C), calculate the contact area ratio under different viewing angles. Then, the new morphological index C′ is solved by the least squares fitting method. In this method, the new morphological index C′ can perfectly connect all the data points, resulting in a smaller error.

[0141] For example, the morphological data obtained from structural surface specimens J1~J39 and J1(10)~J1(350) were used to solve for new morphological index C′ using formula (9) and least squares fitting method, respectively. The new morphological index C′ calculated by the two methods was compared with the true C′. The results showed that the least squares fitting method had a significant advantage in solving the new morphological index C′ with the relative error between the new morphological index C′ calculated by the two methods and the true C′. The maximum error, minimum error and average error were 0.29%, 0 and 0.07%, respectively. Therefore, it is preferable to solve for the new morphological index C′ by least squares fitting method to obtain the new morphological index C′ and direct shear test results from a large number of literatures.

[0142] In the prediction of shear strength, the influence of normal stress and surface morphology on peak shear strength can be expressed by formulas (11) and (12), which are as follows:

[0143]

[0144]

[0145] Where i0 represents the initial expansion angle, i p The peak expansion angle is denoted as .

[0146] Formulas (11) and (12) show that when the normal stress approaches 0, the peak expansion angle is equal to the initial expansion angle, and its value is completely determined by the initial surface morphology. When the normal stress approaches infinity, the peak expansion angle approaches 0, and the influence of the surface morphology is basically ignored.

[0147] As can be seen from formula (6), the new morphological index C′ is related to the contact area ratio. The new morphological index C′ is negatively correlated with the potential contact area. Since the potential contact area is directly related to the peak shear strength and the distribution of the damage zone, the new morphological index C′ is also negatively correlated with the roughness of the structural surface and the peak shear strength of the structural surface. The above correlations are expressed by f(C′) and g(C′), respectively. Based on the above analysis, the Grasselli shear strength model is modified.

[0148] Step S104: Based on the new morphological index C′, the Grasselli shear strength model is modified. The expression for the modified peak shear strength model of the structural surface is as follows:

[0149]

[0150] In the formula, τ represents the peak shear strength of the structural surface; σ n Indicates normal stress; σ t denoted by , f(C′) and g(C′) represent fitting functions related to the morphological index C′. This represents the basic friction angle.

[0151] To ensure the broad applicability of the modified structural surface peak shear strength model, the following steps are also included: obtaining the functional expression of the modified structural surface peak shear strength model using the direct shear test results provided by Grasselli (2001), and verifying the modified structural surface peak shear strength model using experimental data from other scholars. Combining the direct shear test results provided by Grasselli (2001), the least squares fitting method is used to obtain f(C′) and g(C′), resulting in the following expression:

[0152]

[0153] To prevent the accumulation of errors that could lead to a high error in the peak shear strength, this embodiment also includes predicting the peak shear strength even when the maximum error between the new morphological index C′ and the true C′ is 0.29%, based on the premise that the maximum error exists. The expression is as follows:

[0154]

[0155]

[0156] The predicted values ​​of the peak shear strength of the structural surface were calculated using formulas (11) to (13) respectively, and compared with the experimental results. The results show that the error between the predicted values ​​of the peak shear strength of the structural surface calculated by formulas (11) to (13) meets the preset requirements. Taking formulas (12) and (13) as examples, the maximum error, minimum error and average error of the peak shear strength of the structural surface predicted by these two formulas are 0.3%, 0.03% and 0.13% respectively. This phenomenon once again proves that it is feasible to calculate the contact area ratio under different apparent tilt angles based on the experimental data provided by existing research, and then solve the new morphological index C′ by the least squares fitting method. In addition, the average error between the peak shear strength calculated by formula (11) and the experimental results is 9.86%, which further illustrates that the modified peak shear strength model of the structural surface provided by this embodiment has high accuracy.

[0157] To demonstrate the rationality of the modified peak shear strength model for structural surfaces, it is necessary to compare it with some classic peak shear strength models. Furthermore, to illustrate the broad applicability of the modified model, it is necessary to use it to predict the peak shear strength of specimens with other structural surfaces.

[0158] Among them, the classic peak shear strength model can include the shear strength model proposed by Grasselli (2001) and the shear strength model proposed by Tatone et al. (2009); in addition, Xia et al. (2014) and Yang et al. (2016b) have also optimized the Grasselli shear strength model and provided relevant experimental data.

[0159] In this embodiment, Grasselli's experimental data and the experimental data of other scholars are analyzed separately according to the different sources of experimental data, and the test results and calculation results of the peak shear strength of the structural surface are summarized.

[0160] (1) The experimental data provided by Grasselli (2001) were substituted into the shear strength model, Tatone model, Xia model, Yang model and the model provided in this embodiment proposed by Grasselli for calculation, and the calculation results were compared with the experimental results for error analysis. The results showed that the average relative errors of the above models were 10.34%, 10.14%, 14.69%, 11.03% and 9.86%, respectively. It can be seen that the model provided in this embodiment has the smallest error and is most suitable for predicting the peak shear strength of the structural surface.

[0161] (2) Based on experimental data from other scholars, the above models were compared and analyzed. The results show that the average relative errors between the calculation results and the experimental results of the shear strength model proposed by Grasseelli, the Tatone model, the Xia model, the Yang model, and the model provided in this embodiment are 17.84%, 12.75%, 23.95%, 18.62%, and 14.69%, respectively. Among them, the model provided in this embodiment and the Tatone model have higher accuracy.

[0162] (3) After removing the experimental data from Grasselli (2001) and Tatone (2009), the remaining experimental data were used to compare and analyze the model provided in this embodiment with the Tatone model. The results show that the average relative errors between the calculation results of the model provided in this embodiment and the experimental results of the Tatone model are 15.9097% and 16.2854%, respectively. It can be seen that the model provided in this embodiment has better prediction accuracy.

[0163] It should be noted that the model provided in this embodiment not only has advantages in prediction accuracy compared with the Tatone model, but also, the modified peak shear strength model of the structural surface provided in this embodiment simplifies the Grasselli morphology characterization method, making the modified peak shear strength model of the structural surface very simple in form. Moreover, the physical morphology features are characterized by a single morphology parameter, namely the new morphology index C′, which has a clear physical meaning. In addition, the new morphology index C′ can be directly determined from the results of three-dimensional scanning experiments, and the acquisition process is very simple, which is convenient for engineering applications.

[0164] In summary, this application conducted three-dimensional laser scanning experiments on multiple groups of rock structural surfaces. By analyzing the scanning data and the results of other three-dimensional scanning experiments and direct shear tests in existing literature, the Grasselli shear strength model was modified. The modified peak shear strength model of the structural surface is simple in form and has high prediction accuracy, showing significant advantages compared with previous models.

[0165] This application simplifies the Grasselli morphology characterization method and proposes a unique morphology parameter C′ to describe the roughness of the structural surface. This parameter has a clear physical meaning and is negatively correlated with the roughness of the structural surface. It can describe the three-dimensional morphological features and anisotropy of the structural surface without needing to be combined with other indicators.

[0166] Example 2:

[0167] This application provides a correction system for the Grasselli shear strength model, the system comprising:

[0168] The acquisition unit is configured to prepare multiple structural surface specimens using pre-acquired rock specimens.

[0169] The test unit is configured to conduct three-dimensional laser scanning tests on each structural surface specimen, and to reconstruct images of the structural surface of each structural surface specimen based on the results of the three-dimensional laser scanning tests, so as to record the morphological characteristics of each structural surface specimen before and after shearing.

[0170] The simplified unit is configured to analyze the relationship between various morphological parameters and surface roughness in the Grasselli morphology characterization method based on the morphological characteristics of the specimens before and after shearing, combined with experimental data provided by existing studies. Based on the analysis results, the Grasselli morphology characterization method is simplified as follows:

[0171]

[0172] In the formula, C′ represents the new morphological index; A θ* Indicates the contact area ratio; A0 represents the maximum contact area ratio; θ * Indicates the apparent tilt angle;

[0173] The correction unit is configured to correct the Grasselli shear strength model based on the new morphological index C′. The expression for the peak shear strength model of the corrected structural surface is as follows:

[0174]

[0175] In the formula, τ represents the peak shear strength of the structural surface; σ n Indicates normal stress; σ t denoted by , f(C′) and g(C′) represent fitting functions related to the morphological index C′. This represents the basic friction angle.

[0176] The Grasselli shear strength model correction system provided in this application embodiment can implement the steps and processes of the Grasselli shear strength model correction method provided in any of the above embodiments, and achieve the same technical effect, which will not be described in detail here.

[0177] Example 3:

[0178] Some embodiments of this application also provide an electronic device, the electronic device comprising:

[0179] One or more processors;

[0180] A computer-readable storage medium, configurable to store one or more programs, wherein when one or more processors execute one or more programs, the following steps are implemented: Step S101: Prepare multiple structural surface specimens using pre-acquired rock samples; Step S102: Conduct three-dimensional laser scanning tests on each structural surface specimen, and reconstruct images of the structural surface surfaces of each structural surface specimen based on the results of the three-dimensional laser scanning tests to record the morphological characteristics of each structural surface specimen before and after shearing; Step S103: Based on the morphological characteristics of each structural surface specimen before and after shearing, and combined with experimental data provided by existing research, analyze the relationship between various morphological parameters and structural surface roughness in the Grasselli morphological characterization method, and simplify the Grasselli morphological characterization method based on the analysis results. The simplified Grasselli morphological characterization method is as follows:

[0181]

[0182] In the formula, C′ represents the new morphological index; θ* represents the contact area ratio; A0 represents the maximum contact area ratio; θ* represents the apparent tilt angle; Step S104: Based on the new morphology index C′, the Grasselli shear strength model is modified. The expression for the modified peak shear strength model of the structural surface is as follows:

[0183]

[0184] In the formula, τ represents the peak shear strength of the structural surface; σ n Indicates normal stress; σ t denoted by , f(C′) and g(C′) represent fitting functions related to the morphological index C′. This represents the basic friction angle.

[0185] Some embodiments of this application also provide a hardware structure for an electronic device; the hardware structure of the electronic device may include: a processor, a communication interface, a computer-readable storage medium (also referred to as a memory), and a communication bus.

[0186] The processor, communication interface, and computer-readable storage medium communicate with each other via a communication bus.

[0187] A computer-readable storage medium that can be configured to store one or more programs.

[0188] Optionally, the communication interface can be the interface of a communication module, such as the interface of a GSM module.

[0189] The processor executes one or more programs that perform the following steps:

[0190] Step S101: Prepare multiple structural surface specimens using pre-acquired rock samples; Step S102: Conduct three-dimensional laser scanning tests on each structural surface specimen, and reconstruct images of the structural surface surfaces of each specimen based on the results of the three-dimensional laser scanning tests to record the morphological characteristics of each structural surface specimen before and after shearing; Step S103: Based on the morphological characteristics of each structural surface specimen before and after shearing, and combined with experimental data provided by existing studies, analyze the relationship between various morphological parameters and structural surface roughness in the Grasselli morphological characterization method, and simplify the Grasselli morphological characterization method based on the analysis results. The simplified Grasselli morphological characterization method is as follows:

[0191]

[0192] In the formula, C′ represents the new morphological index; Indicates the contact area ratio; A0 represents the maximum contact area ratio; θ * Indicates the apparent tilt angle; Step S104: Based on the new morphological index C′, the Grasselli shear strength model is modified. The expression for the modified peak shear strength model of the structural surface is as follows:

[0193]

[0194] In the formula, τ represents the peak shear strength of the structural surface; σ n Indicates normal stress; σ t denoted by , f(C′) and g(C′) represent fitting functions related to the morphological index C′. This represents the basic friction angle.

[0195] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of modifying a Grasselli shear strength model, characterized by, Comprising: Step S101, using a rock sample obtained in advance to make a plurality of structural plane samples; Step S102, respectively carrying out three-dimensional laser scanning tests on each structural plane sample, and reconstructing the image of the structural plane surface of each structural plane sample according to the results of the three-dimensional laser scanning tests, so as to record the topographic features of each structural plane sample before and after shearing; Step S103, according to the topographic features of each structural plane sample before and after shearing, combining the test data provided by the existing research, analyzing the relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness, and simplifying the Grasselli topographic characterization method according to the analysis results, the simplified Grasselli topographic characterization method is as follows: ， In the formula, represents a new topography index; represents a contact area ratio; represents a maximum contact area ratio; represents a view inclination angle; Step S104, based on the new topographic index The Grasselli shear strength model is modified, and the expression of the modified peak shear strength model of the structural plane is as follows: ， wherein denotes the peak shear strength of the structural plane; denotes the normal stress; denotes the tensile strength; , denotes a fitting function related to the topographic index ; denotes the basic friction angle; Using only one topographic indicator to judge the roughness of the structure surface; using to quantify the contact area ratio the angle of inclination the area covered by the relationship curve and the coordinate axis; In step S103, the relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness is analyzed, including: Maximum contact area ratio of different structural plane specimens Relationship with peak shear strength, range of maximum contact area ratio Range of maximum contact area ratio Relationship with structural plane roughness, maximum contact area ratio before and after shearing of the same structural plane specimen Analysis of the change of maximum contact area ratio to eliminate it from the peak shear strength model of structural plane .

2. The method of claim 1, wherein, In step S103, the relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness is analyzed, including: With the same structural plane sample as template, several groups of structural plane replicas are made, and the maximum apparent dip angles of each structural plane replica are extracted at different sampling intervals ; the structural plane sample with better upper and lower structural plane matching is selected, and the maximum apparent dip angles of the upper and lower structural planes of the coupled structural plane are extracted ; The maximum view inclination angle is extracted from the image, and the value of the maximum view inclination angle is analyzed to determine whether the value of the maximum view inclination angle has instability. The maximum view inclination angle is extracted from the image, and the value of the maximum view inclination angle is analyzed to determine whether the value of the maximum view inclination angle has instability. The maximum view inclination 3. The method of claim 2, wherein, In step S103, the relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness is analyzed, including: Reducing the maximum visual inclination angle of structural plane sample The maximum visual inclination angle of structural plane sample is reduced The roughness and peak shear strength of the structural plane sample after the reduction are calculated according to the Grasselli topography characterization method and the Grasselli shear strength model, respectively, and compared with the actual roughness and peak shear strength of the structural plane obtained by experiment to determine the maximum visual inclination angle The variation within the specified range does not affect the topography of the structural plane, and the variation of the peak shear strength predicted by the Grasselli shear strength model is large.

4. The method of claim 3, wherein, In step S103, the relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness is analyzed, including: Computing the contact area ratio The angle of view The area of the region covered by the curve of relationship and the coordinate axis, in order to determine the use To quantify the roughness of the structure surface, wherein, Indicates the distribution parameter in the Grasselli topography characterization method.

5. The method of claim 4, wherein, After step S103 and before step S104, further comprising: verifying the simplified Grasselli topographic characterization method using a predetermined criterion to ensure accurate expression of the structural plane topographic features, the criterion including: and an error between the first value and the second value is less than a preset first error threshold; The error between the prediction result of the peak shear strength based on the simplified Grasselli topographic characterization method and the prediction result of the peak shear strength based on the Grasselli topographic characterization method is less than a predetermined second error threshold.

6. The method of claim 1, wherein, After step S103 and before step S104, further comprising: Based on the experimental data provided by the existing research, the new topography index is calculated using the following formula : ， wherein denotes the new morphology index; denotes the maximum view inclination angle; denotes the distribution parameter in the Grasselli morphology characterization method; Or, According to the experimental data provided by the existing research, the contact area ratio under different visual inclination angles is calculated, and then a new topography index is solved by the least square fitting method .

7. A system for modifying a Grasselli shear strength model, characterized by, Comprising: An acquisition unit configured to use a rock sample obtained in advance to make a plurality of structural plane samples; A test unit configured to respectively carry out three-dimensional laser scanning tests on each structural plane sample, and reconstruct the image of the structural plane surface of each structural plane sample according to the results of the three-dimensional laser scanning tests, so as to record the topographic features of each structural plane sample before and after shearing; A simplification unit configured to, according to the topographic features of each structural plane sample before and after shearing, combining the test data provided by the existing research, analyze the relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness, and simplify the Grasselli topographic characterization method according to the analysis results, the simplified Grasselli topographic characterization method is as follows: ， In the formula, represents a new morphology index; represents a contact area ratio; represents a maximum contact area ratio; represents a view inclination angle; The correction unit is configured to correct the new topographic index The Grasselli shear strength model is corrected, and the expression of the peak shear strength model of the corrected structural plane is as follows: ， wherein denotes the peak shear strength of the structural plane; denotes the normal stress; denotes the tensile strength; , denotes a fitting function related to the topographic index ; denotes the basic friction angle; Using only one topographic indicator to judge the roughness of the structure surface; using to quantify the contact area ratio the angle of view the area covered by the relationship curve and the coordinate axis; The relationship between each topographic parameter in the Grasselli topographic characterization method and the structural plane roughness is analyzed, including: Maximum contact area ratio of different structural plane specimens Relationship with peak shear strength, range of maximum contact area ratio Range of maximum contact area ratio Relationship with structural plane roughness, maximum contact area ratio before and after shearing of the same structural plane specimen Analysis of the change of maximum contact area ratio to eliminate it from the peak shear strength model of structural plane .

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is the method of any one of claims 1-6.

9. An electronic device, comprising: Comprising: A memory, a processor, and a program stored in the memory and executable on the processor, when the processor executes the program, the method of any one of claims 1-6 is implemented.

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