Slope stability evaluation method and device under complex conditions and computer equipment

Abstract

The invention provides a slope stability evaluation method under complex conditions, and belongs to the field of engineering disaster prevention and reduction and computer aided design. On the basis of proposing a function relation between a large principal stress and a small principal stress of a general nonlinear strength criterion in a principal stress form, a sliding surface tangential direction of any point on a potential sliding surface is equivalent to a most unfavorable shearing direction, and a correlation calculation formula of the sliding surface stress and the large principal stress and the small principal stress of the sliding surface stress is deduced; then, according to the spatial position relation between the Moore stress circle and the shear strength envelope line, a mathematical equation of a sliding surface shear strength parameter associated with a general nonlinear strength criterion in a principal stress form is obtained, and then a loop iteration solving strategy is adopted; and the mutual nesting relation among the sliding surface acting force, the sliding surface stress and the sliding surface shear strength parameters in the evaluation method is broken. Scientific basis is provided for reliably preventing slope collapse and implementing reinforcement measures, and the method has the advantages of being high in calculation efficiency, wide in application range, high in practicability and the like.

Description

Technical Field

[0001] The invention belongs to the field of engineering disaster prevention and reduction and computer-aided design, and specifically relates to a slope stability evaluation method, device and computer equipment under complex conditions. Background Art

[0002] Landslide is a common geological disaster, which often causes casualties and property losses, and sometimes the casualties and losses are very huge, so landslide prevention is very important. In order to reduce the frequency of landslides and reduce the losses caused by landslide disasters, the slope stability theory analysis is carried out to predict the slope stability state and its development trend, which has become a key link in preventing and controlling landslides.

[0003] The limit equilibrium method is a slope stability analysis method currently recommended by engineering design and industry specifications. When using the limit equilibrium method for slope stability analysis, the slope sliding body needs to be divided into multiple vertical strips, and reasonable assumptions are made about the forces between the strips. Then, the mechanical equilibrium conditions of the strips are used to establish the slope safety factor solution to evaluate the slope stability. In this process, the strength criterion is used as a known function to calculate the shear force of the sliding surface and is embedded in the limit equilibrium mechanical equation. Therefore, whether the strength criterion can truly reflect the shear failure characteristics and destruction behavior of the slope rock and soil body will affect the accuracy of the slope stability analysis results and the reliability of the engineering design guidance.

[0004] Experimental data show that the shear strength of rock and soil materials exhibits nonlinear characteristics when they fail, so the nonlinear strength criterion can better reflect the true mechanical behavior of materials when they fail. At the same time, the establishment of nonlinear strength criteria is usually based on triaxial test data of rock and soil bodies. Therefore, the general nonlinear strength criterion is mainly expressed in the form of principal stresses. However, in the limit equilibrium method of slope stability, the principal stress of the rock and soil body in the slope cannot be solved, making it difficult to embed the general nonlinear strength criterion in the form of principal stresses. This limitation of the current limit equilibrium method of slope stability limits its significance in revealing the true instability characteristics and failure behavior of slopes under complex conditions, and reduces its expectations for reliably preventing slope collapse and implementing reinforcement measures.

[0005] That is to say, in actual engineering, the shear failure behavior of slope rock and soil is very complex, and the use of general nonlinear strength criterion in the form of principal stress is an effective way to effectively describe this complex behavior. However, it is difficult to embed the general nonlinear strength criterion in the form of principal stress in the current limit equilibrium analysis of slope stability, which makes it unable to reveal the real slope instability characteristics and failure behavior under complex conditions, and affects its reliability in preventing slope collapse and implementing reinforcement measures.

[0006] Patent CN201910908421.7 provides a method for evaluating the stability of a spherical crown slope under group tension based on a plane sliding method. The implementation process is as follows: obtain the radius r of the annular sliding body; select a fan-shaped sliding body with an angle of Δψ, and obtain the height h, bottom length l, and inclination angle θ between the bottom and the horizontal plane of the fan-shaped sliding body; iteratively calculate the slope safety factor F through the following formula s The simple plane sliding method is improved by introducing new assumptions considering the arch effect of the spherical crown slope and adding group tension into the formula. The improved simple plane sliding method can be used to evaluate the stability of the spherical crown slope under the action of group tension, and the calculation process is simple, which provides a method with more reasonable calculation results for the stability evaluation of the spherical crown slope under the action of group tension.

[0007] However, the patent does not solve the limitations of the current limit equilibrium method for slope stability, and the patent method is also unable to evaluate the stability of slopes under complex conditions. Therefore, the art needs a new method, device and computer equipment for evaluating slope stability under complex conditions. Summary of the invention

[0008] To this end, the present invention proposes a slope stability evaluation method that embeds a general nonlinear strength criterion in the principal stress form into the slope stability limit equilibrium method, which is used to solve the problem of slope stability limit equilibrium analysis under complex strength criteria, thereby ensuring the reliability and effectiveness of engineering slope stability evaluation.

[0009] The present invention first provides a slope stability evaluation method under complex conditions. In the method, based on the functional relationship between the major principal stress and the minor principal stress of the general nonlinear strength criterion in the principal stress form, the sliding surface tangent direction of any point on the potential sliding surface is equivalent to its most unfavorable shear direction, and the correlation calculation formula between the sliding surface stress and its major principal stress and minor principal stress is derived. Then, according to the spatial position relationship between the Moore stress circle and the shear strength envelope, the mathematical equation of the sliding surface shear strength parameter associated with the general nonlinear strength criterion in the principal stress form is obtained. Then, a cyclic iterative solution strategy is adopted to break the mutually nested relationship between the sliding surface force, the sliding surface stress and the sliding surface shear strength parameter in the evaluation method, that is, the slope stability evaluation method under complex conditions.

[0010] In a specific implementation, the method is based on the general nonlinear strength criterion in the principal stress form, introduces the intermediate principal stress action coefficient, constructs a simple relationship between the intermediate principal stress and the major principal stress and the minor principal stress, and thus proposes a functional relationship between the major principal stress and the minor principal stress of the general nonlinear strength criterion in the principal stress form suitable for slope stability analysis.

[0011] In a specific embodiment, the method includes the sliding surface strength parameter c Pand The iterative calculation steps are as follows: P and shear stress τ P Under the condition of P and The solution of ; which specifically includes the following steps:

[0012] Step S3-1: Obtain the normal stress σ of the sliding surface P and sliding surface shear stress τ P ;

[0013] Step S3-2: Let the minor principal stress σ at any point P on the sliding surface be 3_P The initial value of σ 3_P (0) , and in the first calculation, take σ 3_P (0) =0;

[0014] Step S3-3: Calculate the internal friction angle of the sliding surface at point P using equation (8):

[0015]

[0016] Among them, d is the differential symbol, g is the function;

[0017] Step S3-4: Calculate the sliding surface cohesion c at point P using equation (9): P ;

[0018]

[0019] Step S3-5: Calculate the new σ using equation (5) 3_P ;

[0020]

[0021] Among them, σ P is the normal stress of the sliding surface at point P, τ P is the shear stress on the sliding surface at point P;

[0022] Step S3-6: If |σ 3_P -σ 3_P (0) |≤ε, the loop calculation is stopped and the sliding surface strength parameter c is output P and The final result; otherwise, let σ 3_P (0) =σ 3_P , and repeat steps S3-3 to S3-5; preferably ε=0.001;

[0023] Thus, the minor principal stress σ at any point P on the sliding surface is established 3_P , normal stress of sliding surface σ P and sliding surface shear stress τ P And the sliding surface strength parameter c P and The nested relationship between .

[0024] In a specific embodiment, the method comprises the following steps:

[0025] Step S1: Ignore the unknown inter-strip forces dividing the vertical strips, and use the known forces on the vertical strips to calculate the initial strip sliding surface normal force N P (0) and the initial strip sliding surface shear force T P (0) ;

[0026] Step S2: Calculate σ using equations (1) and (2) respectively P and τ P ;

[0027] σ P =N P / l P (1)

[0028] τ P =T P / l P (2) Where N P is the normal force on the strip sliding surface, T P is the shear force on the sliding surface of the strip, l P is the corresponding length of the sliding surface of the strip;

[0029] Step S3: Implement the above steps S3-1 to S3-6, that is, use the minor principal stress σ at any point P on the sliding surface 3_P , normal stress of sliding surface σ P and sliding surface shear stress τ P And the sliding surface strength parameter c P and The nested relationship between them is used to calculate the sliding surface strength parameter c P and

[0030] Step S4: Introduce the inter-strip force assumption and use the strip-block mechanical equilibrium condition to carry out the limit equilibrium solution of slope stability, so as to obtain the limit equilibrium solution of slope stability and the normal force N of the strip-block sliding surface. P and the shear force T P ;

[0031] Step S5: If the slope stability limit equilibrium solution tends to be stable, that is, the relative difference between the slope stability results calculated twice before and after is controlled within the allowable error range, then stop the iteration cycle and output the slope stability result; otherwise, let N P (0) =N P and T P (0) =T P , and repeat steps S2 to S4.

[0032] The present invention also provides a device for evaluating slope stability under complex conditions. The device is a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, each step of the method described above is implemented.

[0033] The present invention also provides a computer device, including a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, the various steps of the slope stability evaluation method under complex conditions as described above are implemented.

[0034] The advantages of the present invention are: combining the general nonlinear strength criterion under the principal stress form to carry out the limit equilibrium analysis of slope stability, realizing the revelation of the instability characteristics and destructive behavior of the real slope under complex conditions, providing a scientific basis for reliably preventing slope collapse and implementing reinforcement measures, at the same time, introducing the intermediate principal stress action coefficient, and using the characteristic that the tangent direction of the sliding surface at any point on the potential sliding surface is the most unfavorable shear direction of the rock and soil body here, realizing the nested calculation between the small principal stress, the sliding surface normal stress and the shear stress and the sliding surface strength parameters at any point on the sliding surface, providing an effective way to solve the problem of embedding the general nonlinear strength criterion under the principal stress form into the limit equilibrium method of slope stability, in addition, adopting the iterative cycle solution strategy, realizing the successive approximation solution and calculation accuracy control of the nested calculation in the limit equilibrium analysis of slope stability, having the advantages of high calculation efficiency, wide application range, strong practicality, etc.

[0035] In general, the present invention realizes the revelation of the real slope instability characteristics and destructive behaviors under complex conditions, provides a scientific basis for the reliable prevention of slope landslides and the implementation of reinforcement measures, and has the advantages of high calculation efficiency, wide application range, and strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the general nonlinear strength criterion under the principal stress form of the present invention.

[0037] Figure 2 It is a schematic diagram for calculating the normal stress and shear stress of the sliding surface at any point on the potential sliding surface in the limit equilibrium method of the present invention, and the lower left corner is an enlarged view of the sliding surface at point P, and the lower right corner is a stress state diagram at point P.

[0038] Figure 3 It is a schematic diagram of the spatial position relationship between the mohr stress circle at any point on the potential sliding surface of the present invention and its sliding surface shear strength envelope.

[0039] Figure 4 It is a schematic diagram of the spatial position relationship between the sliding surface strength envelope and the universal nonlinear strength criterion of any point on the potential sliding surface in the principal stress space of the present invention.

[0040] Figure 5 It is a schematic diagram of the cyclic iterative calculation process of the sliding surface strength parameters of the present invention.

[0041] Figure 6 It is a schematic diagram of the cyclic iterative calculation process of embedding the universal nonlinear strength criterion in the limit equilibrium method of slope stability under the principal stress form of the present invention.

[0042] In the figure: 1. General nonlinear shear strength criterion under principal stress form, 2. Potential sliding surface, 3. Slope sliding body, 4. Vertical strips, 5. Inter-strip force, 6. Any point on the potential sliding surface, 7. Tangent direction of sliding surface, 8. Most unfavorable shear direction, 9. Normal force on strip sliding surface, 10. Shear force on strip sliding surface, 11. Length of strip sliding surface, 12. Major principal stress, 13. Minor principal stress, 14. Normal stress on sliding surface, 15. Shear stress on sliding surface, 16. Cohesion of sliding surface, 17. Internal friction angle of sliding surface, 18. Shear strength envelope of sliding surface at any point, 19. Moore stress circle, 20. Sliding surface strength envelope at any point in principal stress space. DETAILED DESCRIPTION

[0043] In order to solve the above technical method problems, the present invention provides an implementation approach and implementation process of embedding a general nonlinear strength criterion in the form of principal stress into the limit equilibrium method of slope stability. Based on the general nonlinear strength criterion in the form of principal stress, the present invention introduces the intermediate principal stress action coefficient, constructs a simple relationship between the intermediate principal stress and the major and minor principal stresses, and proposes a functional relationship between the major and minor principal stresses of the general nonlinear strength criterion in the form of principal stress suitable for slope stability analysis. Then, the sliding surface tangent direction of any point on the potential sliding surface is equivalent to its most unfavorable shear direction, and the calculation formula associated with the sliding surface stress and its major and minor principal stresses is derived. According to the spatial position relationship between the Moore stress circle reflecting the sliding surface stress state information and the shear strength envelope reflecting the sliding surface shear characteristics, the mathematical equation of the sliding surface strength parameter associated with the general nonlinear strength criterion in the form of principal stress is obtained, and then the mutual feedback channel between the sliding surface stress and the sliding surface strength parameter in the limit equilibrium method of slope stability embedded in the general nonlinear strength criterion in the form of principal stress is established. At the same time, in the limit equilibrium method of slope stability, the slope sliding body is divided into multiple vertical strips, and the sliding surface stress can be calculated by the ratio of the strip sliding surface force to the strip sliding surface length. However, the strip sliding surface force needs to be solved by applying the strip mechanical equilibrium condition under the known sliding surface strength parameters. To this end, the present invention adopts a cyclic iterative solution strategy to crack the mutual nested relationship between the strip sliding surface force, sliding surface stress and sliding surface strength parameters embedded in the slope stability limit equilibrium method of the general nonlinear strength criterion in the form of principal stress, so as to achieve the purpose of slope stability evaluation under complex conditions.

[0044] The specific implementation approach and implementation process of the present invention are as follows:

[0045] (1) The functional expression of the general nonlinear strength criterion in the principal stress form is σ 1 =f(σ 2 , σ 3 ), where σ 1 , σ 2 and σ 3 are the major, medium and minor principal stresses respectively.

[0046] (2) Let the simple relationship between the intermediate principal stress and the major and minor principal stresses be σ 2 =σ 3 +λ(σ 1 -σ 3 ), where λ is the intermediate principal stress coefficient, and its value range is [0, 1]. Then, substituting it into the general nonlinear strength criterion under the principal stress form, the functional relationship between the major and minor principal stresses of the general nonlinear strength criterion under the principal stress form can be established as σ 1 =g(σ 3 ).

[0047] (3) Figure 1 As shown in the figure, for the general nonlinear strength criterion under the principal stress form, the functional relationship between the major and minor principal stresses is σ 1 =g(σ 3 ) is expressed as a curve in the principal stress space. At the same time, the linear strength criterion is only a special case of the general nonlinear strength criterion.

[0048] (4) Figure 2 As shown in the figure, when the limit equilibrium method is used to carry out slope stability analysis, the slope sliding body is required to be divided into multiple vertical strips, and reasonable assumptions need to be made on the forces between the strips. Then, the mechanical equilibrium conditions of the strips are used to establish the limit equilibrium solution of the slope stability. In this process, the strength criterion is used as a known function to calculate the shear force of the strip sliding surface. However, the limit equilibrium method of slope stability cannot solve the principal stress of the rock and soil in the slope, making it difficult to embed the general nonlinear strength criterion in the form of principal stress. For this reason, the tangent direction of the sliding surface at any point on the potential sliding surface is used as the most unfavorable shear direction of the rock and soil at this point, and then the relationship between the sliding surface stress and its corresponding principal stress is established.

[0049] (5) Figure 2 As shown in the figure, the vertical blocks divided by numbers, for any point P on the potential sliding surface, analyze its stress state, the major and minor principal stresses acting on it are σ 1_P and σ 3_P , the normal stress and shear stress of the sliding surface at point P are σ P and τ P The horizontal inclination angle of the tangent line of the sliding surface at point P is α P , where σ P and τ P The normal force N on the sliding surface of the strip at point P can be solved by the limit equilibrium method. P and the shear force T P The corresponding strip sliding surface length l P The specific mathematical calculation formula is:

[0050] σ P =N P / l P (1)

[0051] τ P =T P / l P (2)

[0052] (6) In the limit equilibrium method, if the shear strength parameter of the sliding surface at a given point P is c P and Among them, c P and are the cohesion and internal friction angle of the sliding surface at point P, respectively. The existing calculation method or means can be directly used to carry out slope stability analysis. However, c P and The parameters involved in the general nonlinear shear strength criterion under non-principal stress form are established based on the spatial position relationship between the Mohr stress circle reflecting the stress state at point P and the shear strength envelope of the sliding surface at point P. P and The general nonlinear strength criterion σ in the principal stress form 1 =g(σ 3 ) between them.

[0053] (7) Figure 3 As shown, the rectangular coordinate system of normal stress σ and shear stress τ is established with c P is the shear stress axis intercept, and is the horizontal inclination angle, and the shear strength envelope of the sliding surface at point P is constructed as a straight line. At the same time, the principal stress σ at point P is 1_P and minor principal stress σ 3_P Based on this, a Mohr stress circle reflecting the stress state at point P is established. The center O of this Mohr stress circle is on the normal stress axis. The two intersection points of the Mohr stress circle and the normal stress axis are A and B, respectively. Point A and point B correspond to the minor principal stress σ 3_P and major principal stress σ 1_P According to the definition of Moore's stress circle, OA can represent the direction of the surface of the minor principal stress at point P, and OB can represent the direction of the surface of the major principal stress at point P. Furthermore, a perpendicular line OE is drawn through the center point O to the shear strength envelope. Since OE is the shortest path from the center point O to the shear strength envelope of the sliding surface at point P, it indicates that the rock mass at point P is most likely to undergo shear failure along the direction of OE. Therefore, OE represents the most unfavorable shear direction of the rock mass at point P.

[0054] (8) Figure 3 As shown, on the Moore stress circle at point P, the angle between OE and OA is OE represents the most unfavorable shear direction of the rock and soil at point P, OA represents the direction of the minor principal stress action surface at point P, and at the same time, the tangent direction of the sliding surface at point P is the most unfavorable shear direction of the rock and soil here. Therefore, the angle between the tangent direction of the sliding surface at point P and the direction of its minor principal stress action surface is the angle between OE and OA. Due to the 2-fold angle relationship between the Moore stress circle model and the actual physical model, in the actual mechanical model, the angle between the tangent direction of the sliding surface at point P and the direction of its minor principal stress action surface is

[0055] (9) Figure 3As shown, on the Moore stress circle at point P, the intersection of OE and the Moore stress circle is F. Since the Moore stress circle reflects the spatial stress state information of any point P on the sliding surface and OE represents the tangent direction of the sliding surface at point P, it can be known that point F corresponds to the stress state of the sliding surface at point P. Then, according to the spatial relationship of the triangle, the normal stress σ of the sliding surface at point P is derived. P and shear stress τ P Its major principal stress σ 1_P and minor principal stress σ 3_P The mathematical relationship between them is:

[0056]

[0057] Combining equations (3) and (4), we can get the minor principal stress σ at point P: 3_P and the normal stress σ P and sliding surface shear stress τ P The mathematical relationship is:

[0058]

[0059] (10) Figure 4 As shown in Figure 2, the shear strength envelope of the sliding surface at point P is converted into the strength envelope of the sliding surface at point P in the principal stress space, which is also a straight line, and the mathematical expression is:

[0060]

[0061] In the formula, σ 1 ' _P For 3_P The maximum principal stress required when the sliding surface stress at the lower point P reaches the shear failure state.

[0062] The strength envelope in this principal stress space and the general nonlinear strength criterion σ in the principal stress form 1 =g(σ 3 ) is equivalent at point P, and it is the tangent of the strength curve expressed by the general nonlinear strength criterion in the form of principal stress at point P. Therefore, according to the same slope of the two at point P, it can be obtained:

[0063]

[0064] Further simplifying formula (7), we can get:

[0065]

[0066] In addition, using the equivalence of the two at point P, the general nonlinear strength criterion σ in the principal stress form is 1 =g(σ 3 ) into formula (6), we can get c P The calculation formula is:

[0067]

[0068] (11) Combining equations (5), (8) and (9), we can establish the minor principal stress σ at any point P on the sliding surface: 3_P , normal stress of sliding surface σ P and shear stress τ P And the sliding surface strength parameter c P and The nested relationship between them is that when the normal stress σ of the sliding surface is known P and shear stress τ P In the case of P and To solve , a loop iterative calculation strategy is required, such as Figure 5 As shown, the execution steps are as follows: 3.1. Obtain the normal stress σ of the sliding surface P and shear stress τ P ; 3.2, let σ 3_P The initial value of σ 3_P (0) , and in the first calculation, take σ 3_P (0) =0; 3.3, using formula (8) to calculate 3.4. Calculate c using formula (9) P ; 3.5 Use formula (5) to calculate the new σ 3_P ; 3.6 If |σ 3_P -σ 3_P (0) |≤ε (ε=0.001 is acceptable), the calculation cycle is stopped and the sliding surface strength parameter c is output. P and The final result, otherwise, let σ 3_P (0) =σ 3_P , and repeat steps 3.3 to 3.5.

[0069] (12) Solve for the sliding surface strength parameter c P and When the sliding surface stress σ is known P and τ P , however, to obtain the sliding surface stress σ P and τ P , the corresponding normal force N of the sliding surface of the strip needs to be obtained P and shear force T P In the limit equilibrium method of slope stability, the normal force N P and shear force T P The calculation requires the sliding surface strength parameter c P and is given, and thus, the general nonlinear strength criterion in the principal stress form is embedded in the limit equilibrium method of slope stability. It is also necessary to adopt a cyclic iterative solution strategy between the sliding surface strength parameter and the sliding surface normal force and shear force, such as Figure 6 As shown, the execution steps are as follows: ① Ignore the unknown inter-strip forces of the vertical strips, and use the known forces on the vertical strips to calculate the initial strip sliding surface normal force N P (0) and shear force T P (0) ; ② Use equation (1) and equation (2) to calculate σ P and τ P ; ③ Use the minor principal stress σ at any point P on the sliding surface described in steps 3.1 to 3.6 above 3_P , normal stress of sliding surface σ P and shear stress τ P And the sliding surface strength parameter c P and The nested relationship between them is used to calculate the sliding surface strength parameter c P and ④ Introduce the inter-strip force assumption and use the strip-block mechanical equilibrium condition to carry out the limit equilibrium solution of slope stability, thereby obtaining the limit equilibrium solution of slope stability and the normal force N of the strip-block sliding surface P and shear force T P ⑤ If the slope stability limit equilibrium solution tends to be stable, that is, the relative difference between the slope stability results calculated twice before and after is controlled within the allowable error range, then stop the iteration cycle and output the slope stability result. Otherwise, let N P (0) =N P and T P (0) =T P , and repeat steps ② to ④.

[0070] The characteristics of the general nonlinear strength criterion under the principal stress form of the present invention are: based on the general nonlinear strength criterion under the principal stress form, the intermediate principal stress action coefficient is introduced, and a simple relationship between the intermediate principal stress and the major and minor principal stresses is constructed, thereby proposing a functional relationship between the major and minor principal stresses of the general nonlinear strength criterion under the principal stress form suitable for slope stability analysis.

[0071] The characteristics of the above-mentioned sliding surface stress of the present invention are: the sliding surface tangent direction of any point on the potential sliding surface is equivalent to its most unfavorable shear direction, and the calculation formula related to the sliding surface stress and its major and minor principal stresses is derived. At the same time, in the limit equilibrium method of slope stability, combined with the vertical strip division, the sliding surface stress is equivalent to the ratio of the strip sliding surface force to the strip sliding surface length.

[0072] The characteristics of the above-mentioned sliding surface strength parameters of the present invention are: based on the spatial position relationship between the Moore stress circle reflecting the sliding surface stress state information and the shear strength envelope reflecting the shear characteristics of the sliding surface, the sliding surface strength parameters are obtained in association with the mathematical equation of the general nonlinear strength criterion under the principal stress form. At the same time, in the limit equilibrium method of slope stability, the given sliding surface strength parameters are a prerequisite for solving the sliding surface force using the strip and block mechanical equilibrium conditions.

[0073] The above-mentioned embedding implementation approach of the present invention is characterized in that: by utilizing the mutually nested relationship between the constructed strip-block sliding surface force, sliding surface stress and sliding surface strength parameters, a cyclic iterative solution strategy is adopted in the limit equilibrium method, and combined with the initial value assignment and iterative approximation calculation method, the strip-block sliding surface force is first solved, and then the sliding surface stress and sliding surface strength parameters are solved in turn until the allowable calculation accuracy is reached, thereby realizing the embedding of the general nonlinear strength criterion under the principal stress form.

[0074] The present invention proposes an implementation approach and implementation process for solving the problem of embedding a general nonlinear strength criterion in the form of principal stresses into a limit equilibrium method for slope stability. On the basis of proposing a functional relationship between large and small principal stresses of the general nonlinear strength criterion in the form of principal stresses, the sliding surface tangent direction of any point on the potential sliding surface is used as equivalent to its most unfavorable shear direction, and a correlation calculation formula between the sliding surface stress and its large and small principal stresses is derived. Then, according to the spatial position relationship between the Moore stress circle and the shear strength envelope, a mathematical equation of the sliding surface shear strength parameter associated with the general nonlinear strength criterion in the form of principal stresses is obtained. Subsequently, a cyclic iterative solution strategy is adopted to crack the mutually nested relationship between the sliding surface force, the sliding surface stress and the sliding surface shear strength parameter in the limit equilibrium method for slope stability embedded with the general nonlinear strength criterion in the form of principal stresses, so as to achieve the purpose of slope stability evaluation under complex conditions.

[0075] Example

[0076] A kind of Figure 1 to Figure 6 The evaluation method of slope stability is embedded in the general nonlinear strength criterion under the principal stress form shown in the figure. The slope project is a supporting project of a construction project in the northwest region. The geological conditions of the slope are complex. The rock and soil structure on the upper part of the slope belongs to recent plain fill, containing only a small amount of silty clay, and the underlying bedrock. Special exploration and field investigation of the slope in this area were carried out, and the slope occurrence and physical and mechanical parameters of the rock and soil were obtained as follows: the slope height is 48m, the average slope angle is 22°, and the average rock and soil weight is 17.8kN / m 3 , average uniaxial compressive strength of rock and soil σ c is 10MPa and the average uniaxial tensile strength of rock and soil σ tBased on the present invention, combined with the slope stability limit equilibrium analysis method, the slope stability analysis is carried out to accurately evaluate the slope stability, thereby providing a scientific basis for effectively preventing the slope from sliding and reliably implementing reinforcement measures.

[0077] The specific operations are as follows:

[0078] (1) According to the Code for Geotechnical Engineering Investigation (GB50021-2001) and the Standard for Geotechnical Test Methods (GB / T50123-2019), drilling sampling was carried out on the slope of the analysis object, and indoor triaxial tests were carried out on the sampled samples. The test data showed that the shear failure of the rock and soil in the slope of the analysis object obeys the double shear unified strength criterion. The principal stress expression of this strength criterion is:

[0079]

[0080] In the formula, parameter K is the ratio of soil tensile and compressive strength, and K = σ t / σ c =2.5; b is a parameter reflecting the influence of the intermediate principal shear stress and the normal stress on the corresponding surface on the material failure, and b=0.24 is obtained by the curve fitting method.

[0081] (2) Based on the existing geological data and in-situ stress test experiments on the slope of the analysis object, the influence coefficient of the intermediate principal stress λ = 0 is determined, and then the calculation of the intermediate principal stress is simplified to σ 2 =σ 3 At the same time, the simplified calculation formula of the intermediate principal stress, K = 2.5 and b = 0.24 are substituted into the double shear unified strength criterion to obtain the functional relationship between the major and minor principal stresses under the double shear unified strength criterion in the slope of the analysis object as σ 1 =25+2.5σ 3 .

[0082] (3) According to the Technical Code for Construction Slope Engineering (GB 50330-2013), the slope of the analysis object is assumed to have an arc-shaped failure mode, and then the arc is taken as its potential sliding surface. At the same time, a reasonable range of values ​​of the arc sliding surface parameters is given, and a search is carried out for the potential critical arc sliding surface, so as to achieve the purpose of slope stability analysis.

[0083] (4) For a specific sliding surface among the many arc sliding surfaces generated by the reasonable value range of the given arc sliding surface parameters, the slope sliding body constructed by the arc sliding surface and the slope surface is divided into multiple vertical strips, and the unbalanced thrust method is used to make a reasonable assumption on the force between the strips. At the same time, combined with the implementation process of the patent of the present invention, a cyclic iterative solution between the sliding surface strength parameter and the sliding surface normal force and shear force is carried out to obtain the slope stability result corresponding to the specific sliding surface, that is, the slope safety factor. In combination with the implementation steps S3-1 to S3-6, the sliding surface strength parameter c is obtained. P and They are 7.906 kPa and 25.377° respectively.

[0084] (5) Embedded mathematical optimization method, within the reasonable range of values ​​given by the arc sliding surface parameters, with the minimum value of the slope safety factor as the optimization purpose, search and find the arc sliding surface corresponding to the minimum value of the slope safety factor, and call it the critical arc sliding surface, and the corresponding minimum value of the slope safety factor is called the minimum slope safety factor.

[0085] (6) According to the stability evaluation standard of the Technical Code for Building Slope Engineering (GB 50330-2013), combined with the calculated minimum slope safety factor of the analysis object (whose value is 1.399), which is greater than the requirement of the code that the slope safety factor of the first-level safety grade slope under general working conditions should not be less than 1.35, the evaluation result shows that the slope is in a stable state. At the same time, the critical arc sliding surface range is predicted, providing boundary conditions for the subsequent further reinforcement measures.

[0086] It will be easily understood by those skilled in the art that 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A slope stability evaluation method under complex conditions, characterized in that: In the method, based on the functional relationship between the major principal stress and the minor principal stress of the general nonlinear strength criterion in the principal stress form, the sliding surface tangent direction of any point on the potential sliding surface is equivalent to its most unfavorable shear direction, and the correlation calculation formula between the sliding surface stress and its major principal stress and minor principal stress is derived. Then, according to the spatial position relationship between the Moore stress circle and the shear strength envelope, the mathematical equation of the sliding surface shear strength parameter associated with the general nonlinear strength criterion in the principal stress form is obtained. Subsequently, a cyclic iterative solution strategy is adopted to crack the mutually nested relationship between the sliding surface force, sliding surface stress and sliding surface shear strength parameters in the evaluation method, that is, the slope stability evaluation method under complex conditions.

2. The evaluation method according to claim 1, characterized in that: The method is based on the general nonlinear strength criterion in the principal stress form, introduces the intermediate principal stress action coefficient, and constructs a simple relationship between the intermediate principal stress and the major principal stress and the minor principal stress, thereby proposing a functional relationship between the major principal stress and the minor principal stress of the general nonlinear strength criterion in the principal stress form suitable for slope stability analysis.

3. The evaluation method according to claim 1, characterized in that: The method includes a sliding surface strength parameter c P and The iterative calculation steps are as follows: P and shear stress τ P Under the condition of P and The solution of ; which specifically includes the following steps: Step S3-1: Obtain the normal stress σ of the sliding surface P and sliding surface shear stress τ P ; Step S3-2: Let the minor principal stress σ at any point P on the sliding surface be 3_P The initial value of σ 3_P (0) , and in the first calculation, take σ 3_P (0) =0; Step S3-3: Calculate the internal friction angle of the sliding surface at point P using equation (8): Among them, d is the differential symbol, g is the function; Step S3-4: Calculate the sliding surface cohesion c at point P using equation (9): P ; Step S3-5: Calculate the new σ using equation (5) 3_P ; Among them, σ P is the normal stress of the sliding surface at point P, τ P is the shear stress on the sliding surface at point P; Step S3-6: If |σ 3_P -σ 3_P (0) |≤ε, the loop calculation is stopped and the sliding surface strength parameter c is output P and The final result; otherwise, let σ 3_P (0) =σ 3_P , and repeat steps S3-3 to S3-5; preferably ε=0.001; Thus, the minor principal stress σ at any point P on the sliding surface is established 3_P , normal stress of sliding surface σ P and sliding surface shear stress τ P And the sliding surface strength parameter c P and The nested relationship between .

4. The evaluation method according to claim 3, characterized in that: The method comprises the following steps: Step S1: Ignore the unknown inter-strip forces dividing the vertical strips, and use the known forces on the vertical strips to calculate the initial strip sliding surface normal force N P (0) and the initial strip sliding surface shear force T P (0) ; Step S2: Calculate σ using equations (1) and (2) respectively P and τ P ; σ P =N P / l P (1)τ P =T P / l P (2) Where N P is the normal force on the strip sliding surface, T P is the shear force on the sliding surface of the strip, l P is the corresponding length of the sliding surface of the strip; Step S3: Implement the above steps S3-1 to S3-6, that is, use the minor principal stress σ at any point P on the sliding surface 3_P , normal stress of sliding surface σ P and sliding surface shear stress τ P And the sliding surface strength parameter c P and The nested relationship between them is used to calculate the sliding surface strength parameter c P and Step S4: Introduce the inter-strip force assumption and use the strip-block mechanical equilibrium condition to carry out the limit equilibrium solution of slope stability, so as to obtain the limit equilibrium solution of slope stability and the normal force N of the strip-block sliding surface. P and the shear force T P ; Step S5: If the slope stability limit equilibrium solution tends to be stable, that is, the relative difference between the slope stability results calculated twice before and after is controlled within the allowable error range, then stop the iteration cycle and output the slope stability result; otherwise, let N P (0) =N P and T P (0) =T P , and repeat steps S2 to S4.

5. A slope stability evaluation device under complex conditions, characterized in that: The device is a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, each step of the method according to any one of claims 1 to 4 is implemented.

6. A computer device, characterized in that: The method comprises a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, each step of the slope stability evaluation method under complex conditions as described in any one of claims 1 to 4 is implemented.

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