A method for back analysis of shear strength parameters of sliding zone soil of homogeneous slope in a sliding state

Abstract

This invention discloses a method for back-analysis of shear strength parameters of soil in a homogeneous slope under sliding conditions, comprising: collecting crack information of the slope body under sliding conditions and determining the slope safety factor; determining the value range of the shear strength parameters to be inverted; determining the direction and location of cracks and selecting multiple two-dimensional calculation sections of the slope body under sliding conditions; using the geometric coordinate position of the two-dimensional calculation sections at the cracks and the slope safety factor as search constraints, and using the circular arc slip surface search to obtain the potential most dangerous slip surface and the combination of shear strength parameters; and using statistical methods to analyze the combination of shear strength parameters of the potential most dangerous slip surface to obtain the equivalent shear strength parameter combination that satisfies the slope body. This invention can improve the accuracy and reliability of slip surface construction, making the shear strength parameters closer to the actual slope condition, and can also objectively determine the unique or most reasonable equivalent shear strength parameter combination, solving the problem that the solution of shear strength parameters is not unique in the traditional limit equilibrium method back analysis.

Description

Technical Field

[0001] This invention relates to the field of landslide control analysis and anti-slide engineering design technology, specifically to a method for back analysis of shear strength parameters of soil in the sliding zone of a homogeneous slope in a state of imminent sliding. Background Technology

[0002] The shear strength parameters of the slip zone soil are the most basic and important parameters required for landslide stability analysis, calculation and treatment engineering design. They directly affect the effectiveness of the selected treatment scheme and determine the scheme formulation and project cost of anti-slide engineering.

[0003] To obtain shear strength parameters that conform to engineering practice, there are generally three methods: experimental method, engineering analogy method, and back analysis method. Among them, the experimental method uses small sample sizes, which cannot reflect the contribution of large particles to shear strength parameters, so the experimental results are not representative. The engineering analogy method is highly subjective due to the differences in soil properties, boundary conditions, causes, and researchers' experience in landslides, and therefore cannot objectively and accurately reflect the actual shear strength parameters of the soil.

[0004] Therefore, a more reasonable approach is to use the limit equilibrium method to perform back analysis based on the actual state and development trend of the landslide to determine the shear strength parameters of the slip zone soil. This method has good reliability and is simple and feasible.

[0005] However, using traditional inverse analysis methods to analyze the stability of landslides often presents the following problems: Problem 1: The actual position of the sliding surface cannot be determined in advance, so it is necessary to make reasonable assumptions about the position of the sliding surface. However, the assumed position of the sliding surface often differs greatly from the actual position of the sliding surface, resulting in a large error in the calculation results. Question 2: The shear strength parameters c and φ are not unique, so it is generally necessary to reasonably assume one of the parameters and then back-calculate the other parameter.

[0006] In addition, when a slope is about to become unstable, multiple cracks usually appear at the top and bottom of the slope. These cracks not only reflect the evolution of the landslide, but also fix the position of the sliding surface at the top and bottom of the slope.

[0007] To address this issue, this application proposes a method for back-analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition. By using multiple cracks on the slope as constraints on the location of the slip surface, the method can effectively solve the problem of the difficulty in determining the slip surface. Combined with the limitation of the slope safety factor, the method calculates the combination of shear strength parameters corresponding to the most potentially dangerous slip surface that meets the requirements, thereby solving the aforementioned technical problems. Summary of the Invention

[0008] The main objective of this invention is to provide a method for back-analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition, in order to solve the technical problems of difficulty in determining the slip surface location and the non-uniqueness of shear strength parameters c and φ in traditional back-analysis methods proposed in the background art.

[0009] The present invention solves the above-mentioned technical problems by adopting the following technical solutions: A method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition, performed by computer equipment, includes the following steps: Step S1. Collect crack information of the slope body at the risk of landslide; Step S2. Obtain the crack deformation state based on the collected crack information to determine the slope safety factor; Step S3. Determine the range of values ​​for the inversion parameters of the shear strength of the slope near the landslide based on the engineering geological characteristics of the existing slope soil; Step S4. Based on the collected crack information, determine the direction and location of the cracks, which are used to select multiple two-dimensional calculation sections for the slope body of the landslide. The number of two-dimensional calculation sections selected shall not be less than three, and each section shall contain cracks. Step S5. Using the geometric coordinates of the two-dimensional calculation section at the crack and the slope safety factor as constraints when searching for the most dangerous slip surface, the most dangerous slip surface and the combination of shear strength parameters that meet the specified requirements are obtained within the preset range of values ​​for the shear strength inversion parameters. For each two-dimensional calculation section, the location of the crack is used as a constraint that must be passed when determining the most dangerous potential slip surface. Within the preset range of values ​​for the shear strength inversion parameters, all possible most dangerous potential slip surfaces and their corresponding shear strength parameter combinations that satisfy the slope safety factor are searched and obtained. Step S6. Utilizing the uniqueness of the shear strength parameter combination of the same stratum, statistical methods are used to analyze multiple possible combinations of shear strength parameters of the most dangerous sliding surface to obtain a suitable combination of equivalent shear strength parameters of the slope that meets the preset conditions, which is used to characterize the state of the slope at the risk of sliding. Specifically, all the shear strength parameters obtained from each two-dimensional calculation section are plotted on the cohesion-internal friction angle relationship curve (c-φ curve). The intersection and distribution relationship of these c-φ relationship curves are analyzed by statistical methods to obtain an equivalent shear strength parameter combination that characterizes the state of the entire near-slip slope. The cracks mentioned above include cracks at the top of the slope and cracks at the bottom of the slope, and in some specific cases, they may only include cracks at the top of the slope.

[0010] Preferably, in the above-mentioned inverse analysis method, the location coordinates of the crack and the slope safety factor are used as constraints that must be satisfied in the search for the most dangerous slip surface. During the inverse analysis, the combination of shear strength parameters of the most dangerous slip surface that meets the requirements must be obtained under the conditions of satisfying the geometric constraints of the crack and the slope safety factor.

[0011] Preferably, by using the results of multiple cross sections for mutual verification and uniqueness solution, each cross section obtains a cohesion-internal friction angle relationship curve (c-φ curve) that meets the above two constraints. For multiple cross sections, multiple cohesion-internal friction angle relationship curves (c-φ curves) are plotted in the same coordinate system, and a unique combination of equivalent shear strength parameters is obtained by using statistical methods.

[0012] Preferably, the constraints of the inverse analysis method are set as follows: geometric constraints on crack location and slope safety factor constraints; For each two-dimensional calculation section, only the combination of shear strength parameters that satisfies the above two constraints is the most dangerous combination of shear strength parameters for the slip surface.

[0013] Preferably, since the combination of shear strength parameters in the same stratum is unique, each cross section is independently back-analyzed to obtain the combination of shear strength parameters that meets the constraints of that cross section, and the cohesion-internal friction angle relationship curve (c-φ curve) is plotted. For multi-section applications, statistical methods are used to analyze the cohesion-internal friction angle relationship curve (c-φ curve) that meets the conditions, and a unique combination of equivalent shear strength parameters is obtained.

[0014] Preferably, the specific operation process of step S2 includes: Based on the deformation state of the cracks, the slope is divided into three development stages to determine the safety factor value for the slope in each stage, as shown below: (1) Basically stable: take the safety factor F s The range of values ​​for F is: s >1.05; Rear edge of landslide: One or more tensile cracks appear on the ground surface or buildings at the rear edge, roughly parallel to the topographic contour lines, and the cracks are discontinuously distributed; Front edge of landslide: No obvious changes at the front edge; Sides of landslide: No obvious cracks on both sides, and the boundaries are not obvious; (2) Understability: Take the safety factor F s The range of values ​​for is: 1.00 ≤ F s ≤1.05; Rear edge of landslide: There are many wide and continuous tensile cracks on the ground surface or buildings at the rear edge, and the outer side is offset downward; Front edge of landslide: There is a bulge at the front edge, with radial cracks or compressive tensile cracks that are roughly perpendicular to the contour lines; Both sides of landslide: Equestrian feather-shaped shear cracks appear on both sides. (3) Unstable: Take a safety factor F s The range of values ​​for F is: s <1.00; Rear edge of landslide: Tension cracks at the rear edge often show multiple step-like or graben-like subsidence zones, and the landslide wall is often quite obvious; Front edge of landslide: Obvious shear exits appear at the front edge and shear out frequently; Both sides of landslide: Feather-like cracks and tension cracks at the rear edge of the landslide, and the landslide boundary is obvious.

[0015] Preferably, in the process of calculating and determining the safety factor, the limit equilibrium method is selected as the calculation method for the safety factor to further determine the range of values ​​for the parameters to be inverted for the shear strength of the slope near the landslide. At this time, according to the actual engineering situation, appropriate ranges of values ​​for c and φ are selected, and multiple value intervals are divided within the range of values ​​for the parameters to be inverted for the shear strength. Preferably, if the cracks in the two-dimensional calculation section include cracks at the top and bottom of the slope, then the operation process for obtaining the geometric coordinate positions of the two-dimensional calculation section at the top and bottom of the slope cracks in step S5 includes: Using the location coordinates of the cracks at the top and bottom of the slope as known geometric parameters controlling the slip surface, the search radius parameter R determines the center (x) of the circle. c y c ) parameters; Let the coordinates of the crack at the top of the slope be (x1, y1), and the coordinates of the crack at the bottom of the slope be (x2, y2). Then the coordinates of the center of the circle are calculated as follows:

[0016]

[0017]

[0018] Where, x c y c Here, x1, y1, x2, and y2 are the coordinate parameters of the center of the circle, x1, y1, x2, and y2 are the coordinate parameters of the crack location, R is the radius of the arc, and L is the straight-line distance between the crack at the bottom of the slope and the crack at the top of the slope.

[0019] Preferably, if the cracks in the two-dimensional calculation section only include cracks at the top of the slope, then the operation process for obtaining the geometric coordinate position of the two-dimensional calculation section at the crack in step S5 includes: Using the location coordinates of the crack at the top of the slope as the known geometric parameters controlling the slip surface, the search center (x) is determined. c y c The parameters determine the radius parameter R; Let the coordinates of the crack location at the top of a cross section be (x0, y0), then the radius R is calculated as follows:

[0020] Where, x c y c Here, x0 and y0 are the coordinate parameters of the center of the circle, and R is the radius of the arc.

[0021] Preferably, in step S5, during the process of obtaining the potential most dangerous slip surface and shear strength parameter combination using the circular arc slip surface search method, all possible potential most dangerous slip surfaces and their corresponding shear strength parameter combinations that satisfy the slope safety factor are searched and obtained. Specifically, the circular arc slip surface search is used to search the range of values ​​of the shear strength parameters to be inverted divided in step S3, and the shear strength parameter combinations that meet the requirements in each range are searched, as well as the most dangerous slip surface corresponding to each set of shear strength parameter combinations.

[0022] Preferably, the specific operation process for searching the circular arc surface in step S5 includes: The cohesion c, internal friction angle φ, and unknown parameters of the circular arc on the slip surface are searched until an optimal combination of parameters is found that makes the calculated safety factor equal to the slope safety factor, and the corresponding most dangerous slip surface is identified. The unknown parameter of the circular arc is R when both the slope crest and slope bottom cracks are known; and x when only the slope crest crack is known. c y c ; Establish with An adaptive function is defined as the objective function, such that the safety factor calculated from the searched parameter combination is equal to the slope safety factor, where, The safety factor is calculated for different combinations of parameters during the search process. This is the slope safety factor.

[0023] Preferably, the search for the circular arc surface employs a differential evolution algorithm, and its specific search steps are as follows: Establish an adaptive function with G as the objective and set the search range for the unknown parameters of the arc; Input the crack location coordinates, the range of values ​​for the shear strength parameters to be inverted, the crossover rate, the range of the variation rate, and the termination iteration condition, where the crack location coordinates are used as a constraint condition; Perform a circular arc surface search operation to find the optimal combination of parameters that makes G less than 0.001; Construct the most dangerous slip surface with the optimal parameter combination and output the optimal parameter combination; Furthermore, the search for circular smooth surfaces is not limited to using only the differential evolution algorithm; other methods with similar effects can also be used as equivalent alternatives.

[0024] Preferably, the specific operation process in step S6 includes: Based on the combination of shear strength parameters obtained in step S5, outliers are sequentially filtered and removed. A plane coordinate system is established with cohesion c as the abscissa and internal friction angle φ as the ordinate. Multiple shear strength parameter combinations for each two-dimensional calculation section are fitted by function, and the cohesion-internal friction angle relationship curve (c-φ curve) of each section is plotted. By plotting the cohesion-internal friction angle relationship curves of each cross section on the same coordinate system for comparative analysis, it can be found that multiple curves converge at a point or intersect in a region. If multiple relationship curves intersect at a single point, then the combination of shear strength parameters corresponding to this point is set as the equivalent combination of shear strength parameters for the landslide body. If multiple relationship curves intersect in a region, the geometric center method is used to process the intersection points of multiple different curves in that region, and finally the equivalent shear strength parameter combination of the slope is obtained.

[0025] Preferably, the processing formula for the geometric center method is as follows:

[0026] in The desired combination of equivalent shear strength parameters is obtained. The intersection point of the cohesion-internal friction angle relationship curves for different cross sections.

[0027] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0028] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0029] As can be seen from the above technical solution, the present invention provides a method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-sliding state. Compared with the prior art, the present invention has the following advantages: 1. This invention introduces slope cracks as constraints on the location of the slip surface, and directly integrates crack information into the back analysis process, which can significantly improve the accuracy and reliability of slip surface construction. At this time, combined with the slope safety factor for limitation, it can also eliminate inversion results that do not conform to the actual situation, so that the shear strength parameters obtained by inversion are closer to the actual state of the slope.

[0030] 2. This invention utilizes multiple cross-sections to perform independent back analysis, thereby obtaining the shear strength parameter combination for each cross-section. At this point, the cohesion-internal friction angle relationship curve for each cross-section is plotted. Through the independent inversion results of multiple cross-sections, and by utilizing the convergence distribution relationship of the cohesion-internal friction angle relationship curves, a unique equivalent shear strength parameter combination can be output. Ultimately, a unique or most reasonable equivalent shear strength parameter combination is objectively determined, effectively solving the technical problem of non-unique shear strength parameter solutions in the traditional limit equilibrium method during back analysis.

[0031] It should be understood that the descriptions in this section are not intended to identify key or essential features of embodiments of the invention, nor are they intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Of course, implementing any product of the invention does not necessarily require achieving all of the advantages described above simultaneously. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall process of the present invention; Figure 2 This is a schematic diagram of the three-dimensional cross-sectional distribution of the landslide-prone slope according to the present invention; Figure 3 This is a top view of the slippery slope of the present invention; Figure 4 This is a calculated cross-sectional view of section i of the present invention; Figure 5 This is the most dangerous slip surface diagram for the possible combination of shear strength parameters of section i in this invention; Figure 6 This is a schematic diagram of the circular arc surface search process of the present invention; Figure 7 This is a three-dimensional slope structure diagram for the present invention. Figure 8 This is a top view of the slope in the three-dimensional calculation example of the present invention; Figure 9 The cross-sectional view for cross-section calculation of the present invention is shown in (1), (2), and (3), which are respectively the cross-sectional view for cross-section ①, the cross-sectional view for cross-section ②, and the cross-sectional view for cross-section ③. Figure 10 This is the most dangerous slip surface diagram of the possible combination of shear strength parameters for section ① of the present invention; Figure 11 This is the most dangerous slip surface diagram of the possible combination of shear strength parameters for section ② of the present invention; Figure 12This is the most dangerous slip surface diagram of the possible combination of shear strength parameters for section ③ of the present invention; Figure 13 This is a graph showing the relationship between cohesion and internal friction angle at section ① of the present invention. Figure 14 This is a graph showing the relationship between cohesion and internal friction angle at section ② of the present invention. Figure 15 This is a graph showing the relationship between cohesion and internal friction angle at section ③ of the present invention. Figure 16 This is a comparison diagram of the cohesion-internal friction angle relationship curves for each cross section of the present invention; Figure 17 This is a diagram showing the center point of the geometric center method of this invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] For details in the embodiments, please refer to Figures 1 to 17 .

[0035] like Figure 1 As shown in the embodiment of the present invention, a method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition includes the following steps: Step S1. Collect crack information of the landslide slope, including: location coordinates, width and length of the landslide cracks, etc.; Step S2. Calculate the crack deformation state based on the collected crack information to determine the slope safety factor; Based on the deformation state of the cracks, the slope is divided into three development stages to determine the safety factor value for the slope in each stage: (1) Basically stable: take the safety factor F s The range of values ​​for F is: s >1.05; Rear edge of landslide: One or more tensile cracks appear on the ground surface or buildings at the rear edge, roughly parallel to the topographic contour lines, and the cracks are discontinuously distributed; Front edge of landslide: No obvious changes at the front edge; Sides of landslide: No obvious cracks on both sides, and the boundaries are not obvious; (2) Understability: Take the safety factor F s The range of values ​​for is: 1.00 ≤ F s ≤1.05; Rear edge of landslide: There are many wide and continuous tensile cracks on the ground surface or buildings at the rear edge, and the outer side is offset downward; Front edge of landslide: There is a bulge at the front edge, with radial cracks or compressive tensile cracks that are roughly perpendicular to the contour lines; Both sides of landslide: Equestrian feather-shaped shear cracks appear on both sides. (3) Unstable: Take a safety factor F s The range of values ​​for F is: s <1.00; Rear edge of landslide: Tension cracks at the rear edge often show multiple step-like or graben-like subsidence zones, and the landslide wall is often quite obvious; Front edge of landslide: Obvious shear exits appear at the front edge and shear out frequently; Both sides of landslide: Feather-like cracks and tension cracks at the rear edge of the landslide, and the landslide boundary is obvious.

[0036] Step S3. Determine the range of values ​​for the inversion parameters of the shear strength of the slope near the landslide based on the engineering geological characteristics of the existing slope soil; At this time, in the process of calculating and determining the safety factor, the range of values ​​for the inverted parameters of the shear strength of the slope under potential sliding is determined by selecting the limit equilibrium method. At this time, according to the actual situation of the project, a suitable range of values ​​for c and φ is selected, and multiple value intervals are divided within the range of values ​​for the inverted parameters of shear strength. Step S4. Based on the collected crack information, determine the direction and location of the cracks, and select no less than three representative two-dimensional calculation sections for the slope body of the landslide-prone slope. Each section should contain cracks, and these sections are used to determine the crack location coordinates, slope height and slope ratio of each section. Step S5. Using the geometric coordinates of the two-dimensional calculation section at the crack and the slope safety factor as constraints when searching for the most dangerous slip surface, the most dangerous slip surface and the combination of shear strength parameters that meet the specified requirements are obtained within the preset range of values ​​for the shear strength inversion parameters. For each two-dimensional calculation section, the location of the crack is used as a constraint that must be passed when determining the most dangerous potential slip surface. Within the preset range of values ​​for the shear strength inversion parameters, all possible most dangerous potential slip surfaces and their corresponding shear strength parameter combinations that satisfy the slope safety factor are searched and obtained. The process for obtaining the geometric coordinates of the crack in the two-dimensional calculation section includes: Using the location coordinates of the cracks at the top and bottom of the slope as known geometric parameters controlling the slip surface, the search radius parameter R determines the center (x) of the circle. c y c The parameters of ).

[0037] Let the coordinates of the crack at the top of the slope be (x1, y1), and the coordinates of the crack at the bottom of the slope be (x2, y2). Then the coordinates of the center of the circle are calculated as follows:

[0038]

[0039]

[0040] Where, x c y c Here, x1, y1, x2, and y2 are the coordinate parameters of the center of the circle, x1, y1, x2, and y2 are the coordinate parameters of the crack location, R is the radius of the arc, and L is the straight-line distance between the crack at the bottom of the slope and the crack at the top of the slope.

[0041] Preferably, if the cracks in the two-dimensional calculation section only include cracks at the top of the slope, then the operation process for obtaining the geometric coordinate position of the two-dimensional calculation section at the crack in step S5 includes: Using the location coordinates of the crack at the top of the slope as the known geometric parameters controlling the slip surface, the search center (x) is determined. c y c The parameters determine the radius parameter R.

[0042] Let the coordinates of the crack location at the top of a cross section be (x0, y0), then the radius R is calculated as follows:

[0043] Where, x c y c Here, x0 and y0 are the coordinate parameters of the center of the circle, and R is the radius of the arc.

[0044] Furthermore, in the process of obtaining the most dangerous slip surface and shear strength parameter combination by using the circular arc slip surface search method, all possible most dangerous slip surfaces and their corresponding shear strength parameter combinations that satisfy the geometric constraints of crack location and slope safety factor constraints are searched and obtained. Specifically, the circular arc slip surface search is used to search the range of values ​​of the shear strength parameters to be inverted divided in step S3, and the shear strength parameter combinations that meet the requirements in each range are searched, as well as the most dangerous slip surface corresponding to each set of shear strength parameter combinations. exist: A differential evolution algorithm is used to search for the unknown parameters of the sliding surface, including cohesion c, internal friction angle φ, and circular arc, until an optimal combination of parameters is found that makes the calculated safety factor equal to the slope safety factor, and the corresponding most dangerous sliding surface is identified. The unknown parameter of the circular arc is R when both the slope crest and slope bottom cracks are known; and x when only the slope crest crack is known. c y c ; Establish with Let be an adaptive function with objective , such that the safety factor calculated from the searched parameter combination equals the slope safety factor, where The safety factor is calculated for different combinations of parameters during the search process. The slope safety factor; Set the search range for unknown parameters of the arc; Input the crack location coordinates, the range of values ​​for the shear strength parameters to be inverted, the crossover rate, the range of the variation rate, and the termination iteration condition, where the crack location coordinates are used as a constraint condition; Perform a circular arc surface search operation to find the optimal combination of parameters that makes G less than 0.001; Construct the most dangerous slip surface with the optimal parameter combination and output the optimal parameter combination; Step S6. Utilizing the uniqueness of the shear strength parameter combination of the same stratum, statistical methods are used to analyze multiple possible combinations of shear strength parameters of the most dangerous sliding surface to obtain a suitable combination of equivalent shear strength parameters of the slope that meets the preset conditions, which is used to characterize the state of the slope at the risk of sliding. Specifically, all shear strength parameters obtained from each two-dimensional calculation section are plotted on the cohesion-internal friction angle relationship curve (c-φ curve). The intersection and distribution relationships of these c-φ curves are analyzed using statistical methods to obtain an equivalent shear strength parameter combination characterizing the entire near-slip slope state. The specific operational procedure includes: Based on the combination of shear strength parameters obtained in step S5, outliers are sequentially filtered and removed. A plane coordinate system is established with cohesion c as the abscissa and internal friction angle φ as the ordinate. Multiple shear strength parameter combinations for each two-dimensional calculation section are fitted by function, and the cohesion-internal friction angle relationship curve (c-φ curve) of each section is plotted. By plotting the cohesion-internal friction angle relationship curves of each cross section on the same coordinate system for comparative analysis, it can be found that multiple curves converge at a point or intersect in a region. If multiple relationship curves intersect at a single point, then the combination of shear strength parameters corresponding to this point is set as the equivalent combination of shear strength parameters for the landslide body. If multiple relationship curves intersect in a region, the geometric center method is used to process the intersection points of the multiple different curves within that region, ultimately yielding the equivalent shear strength parameter combination for the slippery slope. The formula for the geometric center method is as follows:

[0045] in The desired combination of equivalent shear strength parameters is obtained. The intersection point of the cohesion-internal friction angle relationship curves for different cross sections.

[0046] In summary, this method, by introducing slope cracks as constraints on the location of the slip surface and directly integrating crack information into the back analysis process, can significantly improve the accuracy and reliability of slip surface construction. By combining this with the slope safety factor for constraint, it can also eliminate inversion results that do not conform to the actual situation, making the shear strength parameters obtained from the inversion closer to the actual state of the slope. Furthermore, the process is clear and easy to implement, making it suitable for the needs of slope stability assessment and treatment design in practical engineering, and it has good prospects for engineering application.

[0047] In practical engineering, the slope height and slope ratio of a three-dimensional slope are not equal at any location and often change with the position. Analyzing cross-sections 1, 2, 3…n… of the three-dimensional slope based on the crack morphology can accurately reflect the changes in slope height, slope ratio, and crack location. For any three-dimensional slope at risk of slippage, the following processing can be performed. In step S1 above, the location of the cracks and the deformation state of the cracks in the landslide-prone slope are determined. In step S2 above, the slope safety factor is determined based on the crack deformation state of the slope body at the risk of landslide. In step S3 above, the limit equilibrium method is selected as the method for calculating the safety factor. Cohesion c and internal friction angle φ are selected as the parameters to be inverted, and the range of values ​​for c and φ is determined. Multiple value intervals are then divided within the range of c(φ). In step S4 above, sections 1, 2, 3...n... can be taken from the slope body near the landslide, and each section should contain cracks, such as... Figure 2 , Figure 3 As shown, the coordinates of the crack location, slope height, and slope ratio of each cross section are used to determine the crack location coordinates, slope height, and slope ratio respectively. In steps S5 and S6 above, section i is further analyzed, and the two-dimensional calculated cross-section diagram of section i is shown below. Figure 4 As shown.

[0048] In the aforementioned inverse analysis method, the location coordinates of the cracks at the top and bottom of the slope and the slope safety factor are used as constraints that must be satisfied in the search for the most dangerous slip surface. During the inverse analysis, the combination of shear strength parameters of the most dangerous slip surface that meets the requirements must be obtained under the conditions of satisfying the crack geometric constraints and the slope safety factor constraints.

[0049] Therefore, specifically in step S5 above, the geometric coordinates of the crack in section i and the slope safety factor are used as constraints. A circular arc slip surface search is used to find the required shear strength parameter combinations within each value interval, resulting in multiple sets of required shear strength parameter combinations for section i. For example... Figure 5As shown, the most dangerous slip surface corresponding to each combination of shear strength parameters of section i is through the cracks at the top and bottom of the slope, and the calculated safety factors all meet the requirements of the slope safety factor.

[0050] At this point, the circular arc surface search is used to find the required shear strength parameter combinations within each value interval. Specifically, the differential evolution algorithm is used to search for the shear strength parameters (c, φ) to be inverted and the radius parameter (R) of the circular arc, finding the required shear strength parameter combinations and the most dangerous sliding surface within each value interval. The specific process is as follows: Figure 6 As shown.

[0051] When the relative error between the minimum safety factor calculated by the searched combination of shear strength parameters and the determined slope safety factor is less than 0.01 (G < 0.001), it is considered that the minimum safety factor calculated by the combination of shear strength parameters meets the requirements of the slope safety factor.

[0052] Then, data processing was performed on multiple sets of shear strength parameter combinations that met the requirements for section i, and outliers were removed. A function was fitted to the shear strength parameter combinations for this section, and the cohesion-internal friction angle relationship curve (c-φ curve) for section i was plotted.

[0053] All sections of the slope near the landslide are processed according to step S5 above. By using the results of multiple sections to cross-check and uniquely solve the problem, the combination of shear strength parameters for all sections is found. Function fitting is performed on the combination of shear strength parameters for each section, and the cohesion-internal friction angle relationship curve (c-φ curve) of different sections is plotted. That is, each section obtains a cohesion-internal friction angle relationship curve (c-φ curve) that meets the above two constraints.

[0054] After finding the intersection points or intersection areas of these c-φ curves, the equivalent shear strength parameter combination of the landslide can be obtained by following the steps in S6 above.

[0055] In a more specific example, a three-dimensional slope is selected as the case study. The slope crest has an uneven height, and γ = 18 kN / m. 3 Furthermore, obvious cracks have appeared on the surface of the slope.

[0056] At this point, the slope safety factor is determined based on the crack deformation state of the slope body. The slope top has many wide and continuous tension cracks, which are offset downwards on the outside and have bulges at the leading edge. There are radial cracks or compression tension cracks that are roughly perpendicular to the contour lines. Equestrian feather-shaped shear cracks appear on both sides. The slope is in an unstable stage, and the slope safety factor is determined to be 1.02.

[0057] The safety factor is determined by the limit equilibrium method, and the range of cohesion c is determined to be 0-40 kPa, and the range of internal friction angle φ is determined to be 0-40°. Multiple ranges are divided within the range of cohesion c.

[0058] Furthermore, three cross-sections are selected for illustrative purposes: cross-sections ①, ②, and ③ are analyzed. Figure 7 , Figure 8 As shown, the slope height, slope ratio, and the locations of the cracks at the top and bottom of the slope are not the same for each cross section.

[0059] At this point, the location information, slope height, and slope ratio of the cracks in each section are determined. Taking the slope toe as the origin, the coordinates of the crack at the top of the slope in section ① are (23.61, 9.8), and the coordinates of the crack at the bottom of the slope are (0.3, 0.15), with a slope height of 9.8 and a slope ratio of 2.04; the coordinates of the crack at the top of the slope in section ② are (24.19, 10), and the coordinates of the crack at the bottom of the slope are (0, 0), with a slope height of 10 and a slope ratio of 2; the coordinates of the crack at the top of the slope in section ③ are (23.32, 10.5), and the coordinates of the crack at the bottom of the slope are (0.52, 0.27), with a slope height of 10.5 and a slope ratio of 1.91. The calculated profile diagrams of each section are shown below. Figure 9 As shown.

[0060] Furthermore, section ② is used as a calculation demonstration, as follows: Set the main parameters of the differential evolution algorithm: set the search range of variable R to 0-150; set the crossover rate to 0.7 and the mutation rate range to 0.5-1; set the tolerance to 0.001 (stop iteration when the change between two adjacent generations is less than 0.001). Substituting the value range of cohesion c into the circular arc slip surface search, the search finds the shear strength parameter combination that meets the requirements within each value range, generating the most dangerous slip surface for each shear strength parameter combination. Taking the shear strength parameter combination c=12.91kPa; φ=8.73° as an example, the center of the most dangerous slip surface corresponding to this shear strength parameter combination is (4.93, 22.33), and the radius is 22.86m. The minimum safety factor is calculated to be 1.0192, which is only 0.0008 different from the assumed slope safety factor of 1.02, meeting the error requirement.

[0061] Then repeat the above steps to obtain multiple combinations of shear strength parameters for section ② and the most dangerous slip surface for each combination of shear strength parameters.

[0062] After the shear strength parameters of the three sections were obtained through a search, as shown in Tables 1 to 3 below, the most dangerous slip surface for each combination of shear strength parameters for each section is as follows: Figures 10 to 12 As shown.

[0063] Table 1: Shear strength parameter combination table for section ①

[0064] Table 2: Shear strength parameter combination table for section ②

[0065] Table 3: Shear Strength Parameter Combination Table for Section ③

[0066] Furthermore, the cohesion-internal friction angle relationship curve (c-φ curve) of the two-dimensional calculation section is plotted. Taking section ② as an example, under a certain slope safety factor constraint, the shear strength parameters c and φ are inversely proportional, showing a linear function trend. A linear function is used to fit different combinations of shear strength parameters. The fitting formula is: y = -0.814x + 19.717 (where x and y correspond to cohesion c and internal friction φ, respectively). The corresponding c-φ fitting curves for each section are plotted, as shown in the figure. Figures 13 to 15 As shown.

[0067] Then, the cohesion-internal friction angle relationship curves of the three cross-sections were plotted on the same coordinate system for comparative analysis, such as... Figure 16 As shown.

[0068] The equivalent shear strength parameter combination of the slope is obtained by finding the intersection of the cohesion-internal friction angle relationship curves for different cross sections.

[0069] like Figure 17 As shown, in this example, the c-φ curves of the three sections intersect in one region, with intersection points of (9.30, 12.14), (11.98, 9.96), and (14.37, 7.44), respectively. Using the geometric center method to process the intersection points, the center point is obtained as (11.89, 9.85), that is, the shear strength parameter combination c=11.89kPa; φ=9.85° is the equivalent shear strength parameter combination of this slope.

[0070] In summary, this method utilizes multiple cross-sections for independent inverse analysis to obtain the combination of shear strength parameters for each cross-section. Then, by plotting the c-φ cohesion-internal friction angle relationship curves for each cross-section, and through the independent inverse results of multiple cross-sections, the unique equivalent shear strength parameter combination can be output using the intersection distribution relationship of the c-φ cohesion-internal friction angle relationship curves. Ultimately, the unique or most reasonable equivalent shear strength parameter combination is objectively determined, effectively solving the technical problem of non-unique shear strength parameter solutions in the traditional limit equilibrium method during inverse analysis.

[0071] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0072] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0073] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to perform the method for back-analysis of shear strength parameters of homogeneous slope slip zone soil in any of the above embodiments under the condition of slipping.

[0074] It is understood that the system provided in the embodiments of the present invention corresponds to the method provided in the embodiments of the present invention, and the explanation, examples and beneficial effects of the relevant content can be referred to the corresponding parts of the above methods.

[0075] This application also provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, communication interface, and memory communicate with each other via the communication bus. Memory, used to store computer programs; The processor, when executing the program stored in memory, implements the method for inverse analysis of the shear strength parameters of the slip zone soil in the aforementioned homogeneous slope under slip conditions.

[0076] The communication bus mentioned in the above-mentioned electronic devices can be a standard bus for interconnecting peripheral components or an extended industrial standard structure bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc.

[0077] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0078] The memory may include random access memory or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0079] The processors mentioned above can be general-purpose processors, including central processing units, network processors, etc.; they can also be digital signal processors, application-specific integrated circuits, field-programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0080] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, an optical medium, or a semiconductor medium, etc.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0082] Furthermore, it should be noted that if any directional indication (such as up, down, left, right, front, back, etc.) is involved in the embodiments of the present invention, the directional indication is only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0083] Furthermore, those skilled in the art should understand that in the actual use of the embodiments of this application, there may be preset thresholds used as the basis for judging the corresponding technical solutions. These thresholds are conventional technical means commonly used in the field to implement functions such as state judgment, condition recognition, and control logic switching. The specific values, setting basis, value selection methods, determination methods, and adjustment rules of the thresholds involved in this technical solution are all conventional technical choices that can be reasonably determined by those skilled in the art based on conventional technical factors such as actual application scenarios, system working states, characteristics of the detection object, hardware performance parameters, and functional requirements, through conventional experiments, calibrations, and debugging. The specific setting and adjustment of the aforementioned thresholds will not cause this technical solution to be unimplementable as a whole, nor will it affect the realization of the core concept and the achievement of the technical effects of this technical solution.

[0084] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, in the embodiments of this invention, "multiple" refers to two or more. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

Claims

1. A method for back analysis of shear strength parameters of soil in the slip zone of a homogeneous slope under sliding conditions, characterized in that, include: Step S1. Collect crack information of the slope body at the risk of landslide; Step S2. Obtain the crack deformation state based on the collected crack information to determine the slope safety factor; Step S3. Determine the range of values ​​for the inversion parameters of the shear strength of the slope near the landslide based on the engineering geological characteristics of the existing slope soil; Step S4. Based on the collected crack information, determine the direction and location of the cracks, which are used to select multiple two-dimensional calculation sections for the slope body of the landslide. The number of two-dimensional calculation sections selected shall not be less than three, and each section shall contain cracks. Step S5. Using the geometric coordinates of the two-dimensional calculation section at the crack and the slope safety factor as constraints when searching for the most dangerous slip surface, the most dangerous slip surface and the combination of shear strength parameters that meet the specified requirements are obtained within the preset range of values ​​for the shear strength inversion parameters. Step S6. Utilizing the uniqueness of the shear strength parameter combination of the same stratum, statistical methods are used to analyze multiple possible combinations of shear strength parameters of the most dangerous sliding surface to obtain a suitable equivalent shear strength parameter combination of the slope that meets the preset conditions, which is used to characterize the state of the slope at the risk of sliding.

2. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in the pre-slip state as described in claim 1, characterized in that, The specific operation process of step S2 includes: Based on the deformation state of the cracks, the slope is divided into three development stages to determine the safety factor value for the slope in each stage: (1) Basically stable: take the safety factor F s The range of values ​​for F is: s >1.05; Rear edge of landslide: One or more tensile cracks appear on the ground surface or buildings at the rear edge, roughly parallel to the topographic contour lines, and the cracks are discontinuously distributed; Front edge of landslide: No obvious changes at the front edge; Sides of landslide: No obvious cracks on both sides, and the boundaries are not obvious; (2) Understability: Take the safety factor F s The range of values ​​for is: 1.00 ≤ F s ≤1.05; Rear edge of landslide: There are many wide and continuous tension cracks on the ground or buildings at the rear edge, and the outer side is offset downward; Front edge of landslide: There is a bulge at the front edge, with radial cracks or compressive tension cracks that are roughly perpendicular to the contour lines; Both sides of landslide: Equestrian feather-shaped shear cracks appear on both sides. (3) Unstable: Take a safety factor F s The range of values ​​for F is: s <1.00; Rear edge of landslide: Tension cracks at the rear edge often show multiple step-like or graben-like subsidence zones, and the landslide wall is often quite obvious; Front edge of landslide: Obvious shear exits appear at the front edge and shear out frequently; Both sides of landslide: Feather-like cracks and tension cracks at the rear edge of the landslide, and the landslide boundary is obvious.

3. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in the pre-slip state as described in claim 1, characterized in that, If the cracks in the two-dimensional calculation section include cracks at the top and bottom of the slope, then the operation process for obtaining the geometric coordinate position of the cracks in step S5 includes: Using the location coordinates of the cracks at the top and bottom of the slope as known geometric parameters controlling the slip surface, the search radius parameter R determines the center (x) of the circle. c y c The parameters of ). Let the coordinates of the crack at the top of the slope be (x1, y1), and the coordinates of the crack at the bottom of the slope be (x2, y2). Then the coordinates of the center of the circle are calculated as follows: Where, x c y c Here, x1, y1, x2, and y2 are the coordinate parameters of the center of the circle, x1, y1, x2, and y2 are the coordinate parameters of the crack location, R is the radius of the arc, and L is the straight-line distance between the crack at the bottom of the slope and the crack at the top of the slope.

4. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition as described in claim 1, characterized in that, If the cracks in the two-dimensional calculation section only include cracks at the top of the slope, then the operation process for obtaining the geometric coordinate position of the cracks in the two-dimensional calculation section in step S5 includes: Using the location coordinates of the crack at the top of the slope as the known geometric parameters controlling the slip surface, the search center (x) is determined. c y c The parameters determine the radius parameter R; Let the coordinates of the crack location at the top of a cross section be (x0, y0), then the radius R is calculated as follows: Where, x c y c Here, x0 and y0 are the coordinate parameters of the center of the circle, and R is the radius of the arc.

5. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition as described in any one of claims 3-4, characterized in that, The specific operation process for searching the circular arc surface in step S5 includes: The cohesion c, internal friction angle φ, and unknown parameters of the circular arc on the slip surface are searched until an optimal combination of parameters is found that makes the calculated safety factor equal to the slope safety factor, and the corresponding most dangerous slip surface is identified. The unknown parameter of the circular arc is R when both the slope crest and slope bottom cracks are known; and x when only the slope crest crack is known. c y c ; Establish with An adaptive function is defined as the objective function, such that the safety factor calculated from the searched parameter combination is equal to the slope safety factor, where, The safety factor is calculated for different combinations of parameters during the search process. This is the slope safety factor.

6. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in the pre-slip state as described in claim 5, characterized in that, The search for the circular arc surface employs a differential evolution algorithm, and its specific search steps are as follows: Establish an adaptive function with G as the objective and set the search range for the unknown parameters of the arc; Input the crack location coordinates, the range of values ​​for the shear strength parameters to be inverted, the crossover rate, the range of the variation rate, and the termination iteration condition, where the crack location coordinates are used as a constraint condition; Perform a circular arc surface search operation to find the optimal combination of parameters that makes G less than 0.001; Construct the most dangerous slip surface with the optimal parameter combination and output the optimal parameter combination.

7. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition as described in claim 6, characterized in that, The specific operation process in step S6 includes: Based on the combination of shear strength parameters obtained in step S5, outliers are sequentially filtered and removed. A plane coordinate system is established with cohesion c as the abscissa and internal friction angle φ as the ordinate. Multiple shear strength parameter combinations for each two-dimensional calculation section are fitted by function, and the cohesion-internal friction angle relationship curves of each section are plotted. The cohesion-internal friction angle relationship curves of each section are plotted on the same coordinate system for comparative analysis; If multiple relationship curves intersect at a single point, then the combination of shear strength parameters corresponding to this point is set as the equivalent combination of shear strength parameters for the landslide body. If multiple relationship curves intersect in a region, the geometric center method is used to process the intersection points of multiple different curves in that region, and finally the equivalent shear strength parameter combination of the slope is obtained.

8. The method for back analysis of shear strength parameters of homogeneous slope slip zone soil in a near-slip condition as described in claim 7, characterized in that, The processing formula for the geometric center method is as follows: in The desired combination of equivalent shear strength parameters is obtained. The intersection point of the cohesion-internal friction angle relationship curves for different cross sections.

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