Calculation method of dynamic safety factor of slope based on shear displacement of large rock mass

Abstract

The present invention discloses a method for calculating the dynamic safety factor of a slope based on the shear displacement of a large rock mass, comprising the following steps: establishing a relationship between shear stress τ and the total area S of the rock interface; constructing a shear constitutive model of a small-scale rock sample by combining the classic structural plane shear stress-displacement curve and the Weibull distribution; converting the parameters in the shear constitutive model of the small-scale rock sample into corresponding large-scale rock mass parameters to construct a shear constitutive model of the large-scale rock mass; and bringing the real-time shear displacement of the sliding body into the shear constitutive model of the large-scale rock mass to obtain the dynamic safety factor of the slope. The present invention constructs a new shear constitutive model of a large-scale rock mass, and based on the expression of the shear constitutive model of the large-scale rock mass, brings the shear displacement of the sliding body into the shear constitutive model of the large-scale rock mass, so that the shear displacement of the rock mass can be used to calculate the dynamic safety factor of the slope.

Description

Technical Field

[0001] The invention relates to the technical field of rock structural surface constitutive models, in particular to a method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass. Background Art

[0002] Landslide disaster is a geological disaster that occurs frequently in human society and can cause great damage to people's lives and social economy. Under the influence of long-term gravity and external factors such as rainfall and earthquakes,

[0003] A sliding body in a slope can undergo shear failure along the potential sliding surface, leading to large-scale landslide hazards such as mountain debris flows and high-speed debris flow landslides. Currently, there are many methods for studying slope stability, such as the limit equilibrium method, the minimum potential energy method, and numerical simulation. The role of these methods in slope stability research has been widely recognized by engineers and has achieved some significant research results. However, the slope stability calculated by these theories is static. As the shear displacement of the sliding body on the sliding surface increases, the rock on the sliding surface undergoes shear deformation and failure. In other words, the shear strength of the rock changes nonlinearly with the increase in shear displacement. Existing theories ignore the impact of the shear characteristics of the sliding body on slope stability.

[0004] As the sliding body continues to slowly shear and slide along the sliding surface, the previously intact rock interface on the sliding surface will be damaged, and the anti-sliding force acting on the sliding body will decrease. Therefore, the stability of the slope will change dynamically with the increase of the shear displacement of the landslide. Existing theoretical methods such as the limit equilibrium method mostly ignore this point, which is not conducive to monitoring the dynamic safety factor of the slope. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a method for calculating the dynamic safety factor of the slope based on the shear displacement of large rock masses, bringing the shear displacement of the sliding body into the shear constitutive model of the large rock mass, so that the shear displacement of the rock mass can be used to calculate the dynamic safety factor of the slope.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass, which comprises the following steps:

[0008] Step S1, establishing a relationship between shear stress τ and the total area S of the rock interface;

[0009]

[0010] Where τ represents the shear stress, that is, the average shear strength per unit area on the rock interface, S represents the total area of ​​the rock interface, and τ u and τ d They represent the shear strength of the undamaged unit and the damaged unit, S u and S d represent the total area of ​​undamaged cells and damaged cells respectively;

[0011] Step S2, constructing a shear constitutive model of a small-sized rock specimen by combining the classical structural plane shear stress-displacement curve and Weibull distribution;

[0012] Step S3: converting the parameters in the shear constitutive model of the small-sized rock sample into corresponding large-scale rock mass parameters to construct a shear constitutive model of the large-scale rock mass;

[0013] Step S4: Divide the sliding body on the slope into multiple strips and blocks, and obtain the dynamic safety factor of the slope based on the safety factor calculation formula of the slope.

[0014] In one embodiment, the steps of step S2 include:

[0015] Step S21: Introduce the damage concept D, which represents the damage generated on the rock interface during the shearing process and is the area of ​​the damaged unit S. d The ratio of the total rock interface area S is:

[0016] D=S d / S (2);

[0017] Step S22: Combine formula (1) and formula (2) and divide both sides of formula (1) by S to obtain shear stress τ = τ u (1-D)+τ d D(3);

[0018] Step S23: Analyze the shear stress-displacement curve of the classical structural surface, and do not destroy the unit shear strength τ u Satisfy τ u =ku(4), combining formula (3) and formula (4), we can get τ=ku(1-D)+Dτ d (5); where k represents the slope of the elastic phase of the shear stress-displacement curve of the classic structural surface, and u represents the shear displacement;

[0019] Step S24: Use Weibull distribution to describe the number of damaged units. The function expression of Weibull distribution is: u k The displacement value corresponding to the dividing point between the elastic stage and the plastic yield stage in the shear stress-displacement curve is represented by the damage D, which is the integral of the Weibull distribution function with the shear displacement as the upper and lower limits:

[0020]

[0021] Step S25: Substitute formula (7) into formula (5) to obtain the shear constitutive model of the small-sized rock specimen:

[0022]

[0023] In one embodiment, after step S25, the method further includes:

[0024] Step S26: Determine the parameters F1 and F2 in the shear constitutive model of the small-sized rock sample.

[0025] In one embodiment, the specific steps of step S26 are as follows:

[0026] Based on the peak point of the shear stress-displacement curve (u f , τ f ), and the derivative of the peak point is 0, we can get:

[0027] The peak point (u f , τ f ) also satisfies formula (8). Combining formulas (8) and (9), we can obtain the calculation formulas for parameters F1 and F2 in the shear constitutive model of small-sized rock specimens:

[0028]

[0029] In one embodiment, the steps of step S3 include:

[0030] Step S31: The slope k is expressed by the shear modulus G of the rock mass. The relationship between the slope k and the shear modulus G of the rock mass satisfies:

[0031] Among them, A represents the reduction coefficient, and the value range of A is 0 to 1. interface represents the length of the shear surface, ε τ represents shear strain;

[0032] Step S32: The shear modulus G can be expressed by the elastic modulus E. The relationship between the shear modulus G and the elastic modulus E satisfies:

[0033] Where E represents the elastic modulus of the rock mass, and μ represents the Poisson's ratio of the rock mass;

[0034] Step S33: Substitute formula (12) and formula (11) into formula (8) to obtain the shear constitutive model of large rock mass:

[0035]

[0036] In one embodiment, after step S33, the method further includes:

[0037] Step S34: Determine the parameters F1 and F2 in the shear constitutive model of the large rock mass.

[0038] In one embodiment, the specific steps of step S34 are as follows:

[0039] Based on the Mohr-Coulomb criterion, the maximum shear resistance of large rock mass satisfies:

[0040] Where σ represents the normal pressure on the sliding surface, represents the internal friction angle of the rock mass, and c represents the cohesion of the rock mass;

[0041] Substituting formula (11), formula (12) and formula (13) into formula (10), we can obtain the calculation formulas for parameters F1 and F2 in the shear constitutive model of large rock mass:

[0042]

[0043] In one embodiment, the specific steps of step S4 are as follows:

[0044] Divide the sliding mass on the slope into a plurality of cuboid blocks with approximately rectangular cross-sections;

[0045] The weight of block i is known to be W i , the angle between bar i and the horizontal is α i , then the sliding force generated by block i is

[0046] F slide-force =W i sinα i (16),

[0047] The sliding force on block i is

[0048] F antislide-force =τ i L i (17),

[0049] Among them, L i Indicates the bottom length of bar i;

[0050] The safety factor calculation formula of the slope is the sum of the anti-sliding forces on all strips divided by the sum of the sliding forces. Combining formulas (15), (16) and (17) we can get the dynamic safety factor F of the slope: s The calculation expression is

[0051]

[0052] ; Among them, the subscript i of each parameter represents the parameter value corresponding to the i-th block.

[0053] In one embodiment, after step S4, the following steps are also included:

[0054] Step S5: determine whether the dynamic safety factor of the slope is greater than 1. When the dynamic safety factor of the slope is greater than 1, the slope is in a stable state; when the dynamic safety factor of the slope is not greater than 1, the slope is in an unstable state.

[0055] In summary, the present invention constructs a new shear constitutive model of large rock mass. Based on the expression of the shear constitutive model of large rock mass, the shear displacement of the sliding body is introduced into the shear constitutive model of large rock mass, so that the shear displacement of the rock mass can be used to calculate the dynamic safety factor of the slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of the structure of a rock interface unit in a damaged state provided by an embodiment of the present invention;

[0057] Figure 2 A schematic diagram of a curve showing damage accumulation during shearing provided by an embodiment of the present invention;

[0058] Figure 3 A schematic diagram of a curve showing the rock unit failure process during shearing provided by an embodiment of the present invention;

[0059] Figure 4 A schematic diagram showing a data comparison between the shear constitutive model of a small-sized rock sample and experimental data provided by an embodiment of the present invention;

[0060] Figure 5 A schematic flow chart of a method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass provided by an embodiment of the present invention;

[0061] Figure 6 A schematic structural diagram of an irregular sliding body provided in an embodiment of the present invention being divided into a plurality of strips with approximately rectangular cross-sectional shapes;

[0062] Figure 7 A schematic diagram of the structure of the angle between the strip and the horizontal provided in an embodiment of the present invention;

[0063] Figure 8 A schematic diagram of the parameters and dimensions of an assumed slope model provided by an embodiment of the present invention;

[0064] Figure 9 A schematic diagram of the structure of the slope safety factor obtained based on the limit equilibrium method provided in an embodiment of the present invention;

[0065] Figure 10 A schematic diagram of a structure in which a sliding body provided in an embodiment of the present invention is divided into a plurality of strips;

[0066] Figure 11 A schematic diagram showing different shear curves for different strips provided in an embodiment of the present invention;

[0067] Figure 12 A schematic diagram of a curve showing the change in slope safety factor with shear displacement provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0068] In order to further understand the features, technical means, specific objectives and functions achieved by the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0069] Figure 5 FIG. 1 is a flow chart of a method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass provided by an embodiment of the present invention. Figure 5 As shown in FIG, the method for calculating the dynamic safety factor of a slope based on the shear displacement of a large rock mass specifically includes the following steps:

[0070] Step S1: Establish the relationship between shear stress τ and the total area S of the rock interface:

[0071]

[0072] Where τ represents the shear stress, that is, the average shear strength per unit area on the rock interface, S represents the total area of ​​the rock interface, and τ u and τ d They represent the shear strength of the undamaged unit and the damaged unit, S u and S d Represent the total area of ​​undamaged units and damaged units respectively; the rock interface includes undamaged units and damaged units.

[0073] The damage of rock units on the shear interface is the main reason for the deterioration of rock materials during the shear process. Therefore, the rock units on the shear interface can be divided into two parts according to the damaged and undamaged parts, such as Figure 1 As the shearing behavior continues, more and more elements on the rock interface change from undamaged to damaged.

[0074] Step S2: Construct a shear constitutive model of a small-sized rock specimen by combining the classical structural plane shear stress-displacement curve and the Weibull distribution.

[0075] The specific steps of step S2 include:

[0076] Step S21: Introduce the damage concept D, where D represents the damage generated on the rock interface during shearing. Figure 2 As shown, the damage D is specifically the damaged unit area S d The ratio of the total rock interface area S is

[0077] D=S d / S (2);

[0078] Step S22: Combine formula (1) and formula (2) and divide both sides of formula (1) by S to obtain shear stress τ = τ u (1-D)+τ d D(3);

[0079] Step S23: Analyze the shear stress-displacement curve of the classical structural surface. The curve includes the elastic stage (OA), the plastic yield stage (AB), the strain softening stage (BC) and the residual stage (CD). The intersection of the elastic stage and the plastic yield stage is the yield point. The shear stress in the elastic stage is The shear displacement curve shows a linear or approximately linear change, that is, damage has not occurred yet. In the plastic yield stage, the relationship between shear stress and shear displacement has obviously deviated from the straight line, indicating that the rock material has been damaged at this stage. The starting point of the damage is defined at the yield point; therefore, the unit shear strength τ is not destroyed. u satisfy

[0080] τ u =ku (4),

[0081] Combining formula (3) and formula (4), we can get τ=ku(1-D)+Dτ d (5);

[0082] Where k represents the slope of the elastic stage of the shear stress-displacement curve of the classic structural surface, u represents the shear displacement; damage D represents the ratio of the damaged unit area to the total area of ​​the rock interface. When D = 1, the rock interface is in a completely damaged state, at this time τ = τ d , corresponding to the residual stage of the shear stress-displacement curve, such as Figure 2 and Figure 3 shown.

[0083] Step S24: Use Weibull distribution to describe the number of damaged units. The function expression of Weibull distribution is: u k The displacement value corresponding to the boundary between the elastic stage and the plastic yield stage in the shear stress-displacement curve is represented by the damage D, which is the integral of the Weibull distribution function with the shear displacement as the upper and lower limits.

[0084]

[0085] Step S25: Substitute formula (7) into formula (5) to obtain the shear constitutive model of the small-sized rock specimen:

[0086]

[0087] Furthermore, after step S25, the method further includes:

[0088] Step S26: Determine the parameters F1 and F2 in the shear constitutive model of the small-sized rock sample.

[0089] The specific steps of step S26 are as follows:

[0090] Based on the peak point of the shear stress-displacement curve (u f , τ f ), and the derivative of the peak point is 0, we can get:

[0091] The peak point (u f , τ f ) also satisfies formula (8). Combining formulas (8) and (9), we can obtain the calculation formulas for parameters F1 and F2 in the shear constitutive model of small-sized rock specimens:

[0092]

[0093] The shear constitutive model of the small-sized rock sample constructed in this invention is compared with the actual shear test data, and the correlation coefficient R 2 As an indicator for evaluating model accuracy, R 2 The value range is between 0 and 1, R 2 The closer it is to 1, the higher the accuracy of the model.

[0094] Please refer to Figure 4 , Figure 4 The diagram shows the comparison between the shear deformation curve calculated by the shear constitutive model of small-scale rock specimens and the actual shear deformation results. The actual shear constitutive relationship is in good agreement with the predicted curve of the shear constitutive model of small-scale rock specimens. The results show that the two are quite consistent, among which the correlation coefficient R 2 Both are greater than 0.95, which is quite significant. The shear constitutive model of small-sized rock specimens can fully simulate the linear and nonlinear behaviors in the shear deformation of the structural surface.

[0095] Step S3: Convert the parameters in the shear constitutive model of the small-scale rock specimen into the corresponding parameters of the large rock mass to construct a shear constitutive model of the large rock mass. The shear constitutive model of the small-scale rock specimen constructed in step S2 is based on the corresponding shear stress-displacement curve. Due to the size effect, the shear constitutive model of the small-scale rock specimen cannot be applied to the large rock mass model. It is necessary to convert the parameters in the shear constitutive model of the small-scale rock specimen into the parameters of a large rock mass, such as a slope, to construct the shear constitutive model of the large rock mass.

[0096] The specific steps of step S3 include:

[0097] Step S31: In the shear stress-displacement curve, k represents the shear stress increase rate per unit distance, in Pa / m. In actual rock mass, the shear modulus G represents the shear stress increase rate per unit strain.

[0098] Therefore, the slope k is expressed with the shear modulus G of the rock mass. The relationship between the slope k and the shear modulus G of the rock mass satisfies:

[0099]

[0100] Among them, A represents the reduction coefficient, and the value range of A is 0 to 1. Due to the initial voids and microcracks inside the rock sample, the k obtained in the test curve will be smaller than the shear modulus G of the ideal elastic body. Therefore, the parameter A is introduced to reduce the shear modulus G. interface represents the length of the shear surface, ε τ represents shear strain.

[0101] Step S32: The shear modulus G can be expressed by the elastic modulus E. The relationship between the shear modulus G and the elastic modulus E satisfies:

[0102]

[0103] Where E represents the elastic modulus of the rock mass, and μ represents the Poisson's ratio of the rock mass.

[0104] Step S33: Substitute formula (12) and formula (11) into formula (8) to obtain the shear constitutive model of large rock mass:

[0105]

[0106] Furthermore, after step S33, the method further includes:

[0107] Step S34: Determine the parameters F1 and F2 in the shear constitutive model of the large rock mass.

[0108] The specific steps of step S34 are as follows:

[0109] Based on the Mohr-Coulomb criterion, the maximum shear resistance of large rock mass τ f satisfy:

[0110] Where σ represents the normal pressure on the sliding surface, represents the internal friction angle of the rock mass, and c represents the cohesion of the rock mass;

[0111] In the shear constitutive model of small-scale rock specimens, the parameters F1 and F2 can be solved using the shear stress-displacement curve. However, large rock masses, such as slopes, cannot be directly subjected to shear tests. In the shear constitutive model of large rock masses, the maximum shear resistance of the large rock mass can be calculated using the Mohr-Coulomb criterion.

[0112] Substituting formula (11), formula (13) and formula (14) into formula (10), the calculation formulas for parameters F1 and F2 in the shear constitutive model of large rock mass can be obtained:

[0113]

[0114] Step S4: Bring the shear displacement of the sliding body into the large rock mass shear constitutive model to obtain the dynamic safety factor F of the slope s .

[0115] In step S3, the shear constitutive model of the large rock mass has been obtained. In this model, as the shear displacement of the sliding body increases, the anti-sliding force provided by the sliding surface to the sliding body will also change. However, the shear constitutive model of the large rock mass is derived based on the shear constitutive model of the indoor test, and the samples used in the indoor shear test are all regular rectangular specimens, such as Figure 1 shown.

[0116] However, if Figure 6 As shown in the figure, the sliding body is a large rock mass with an irregular shape compared to a small rectangular rock sample. This results in different normal loads at different positions on the sliding surface of the large rock mass. Therefore, it is necessary to divide the irregular sliding body into multiple rectangular parallelepiped blocks. The shear displacement of the sliding body is introduced into the shear constitutive model of the large rock mass. In combination with dividing the sliding body on the slope into multiple blocks, the dynamic safety factor of the slope F is obtained based on the slope safety factor calculation formula. s .

[0117] The specific steps of step S4 include:

[0118] Step S41: dividing the sliding body on the slope into a plurality of cuboid blocks with approximately rectangular cross-sectional shapes;

[0119] Step S42: The weight of the known bar i is W i , the angle between bar i and the horizontal is αi ,like Figure 7 As shown, the sliding force generated by block i is

[0120] F slide-force =W i sinα i (16),

[0121] The sliding force on block i is

[0122] F antislide-force =τ i L i (17),

[0123] Among them, L i Indicates the bottom length of bar i;

[0124] Step S43: Bring the shear displacement of the sliding body into the shear constitutive model of the large rock mass. The safety factor of the slope is calculated based on the formula of the sum of the anti-sliding forces on all blocks divided by the sum of the sliding forces. Combining formulas (15), (16) and (17), the dynamic safety factor of the slope F can be obtained. s The calculation expression is

[0125] ; Among them, the subscript i of each parameter represents the parameter value corresponding to the i-th block.

[0126] Furthermore, after step S4, the method further includes:

[0127] Step S5: determine whether the dynamic safety factor of the slope is greater than 1. When the dynamic safety factor of the slope is greater than 1, the slope is in a stable state; when the dynamic safety factor of the slope is not greater than 1, the slope is in an unstable state and a landslide warning signal is issued.

[0128] The shear displacement of a rock mass is the sliding displacement of the rock mass. As the shear displacement changes, the shear force will also change. Formula u represents the shear displacement, which is also the sliding displacement. The shear constitutive model of large rock masses includes shear displacement, which is also the sliding displacement. When the safety factor of the slope is greater than 1, that is, the sliding force of the sliding body is less than the anti-sliding force, the slope is in a stable state. When the safety factor of the slope is equal to 1, that is, the sliding force of the sliding body is equal to the anti-sliding force, the slope is in a critically stable state. When the safety factor is less than 1, it means that the sliding force of the sliding body is greater than the anti-sliding force, and the slope is in an unstable state. The shear displacement generated by the sliding body can be captured by external displacement monitoring equipment, and the shear displacement can be brought into the dynamic safety factor calculation expression of the slope. If it is found that the slope safety factor decreases to 1 or less than 1 as the shear displacement increases, a landslide warning can be issued.

[0129] In summary, the present invention constructs a new large-scale rock mass shear constitutive model. Based on the expression of the large-scale rock mass shear constitutive model, the shear displacement of the sliding body is brought into the large-scale rock mass shear constitutive model, so that the shear displacement of the rock mass can be used to calculate the dynamic safety factor of the slope. In actual engineering, the shear displacement of the rock mass can be determined by the displacement monitoring equipment installed inside the rock mass, and the slope safety factor can be calculated based on the displacement to determine whether the slope is in a stable state. The method of calculating the dynamic safety factor of the slope of the invention effectively improves the early warning efficiency of the slope and has important engineering significance.

[0130] Compared with existing shear constitutive models, this method has strong repeatability and can be applied to various geological rock masses such as field slopes, open-pit mines, and large dams. It has a wide range of applications and can serve as a reference for the sliding shear characteristics of various engineering rock and soil.

[0131] For example, for a large slope, engineers can use installed displacement monitors to obtain the slope's landslide displacement and landslide rate. By incorporating this data into the proposed dynamic slope safety factor calculation formula based on large rock mass shear displacement, engineers can better determine whether the slope is on the verge of collapse. This, combined with landslide warnings, allows engineers to effectively improve slope stability through grouting, anchoring, and other methods, or organize evacuations.

[0132] In order to intuitively and conveniently verify the adaptability and rationality of the proposed calculation method of dynamic safety factor of slope based on large rock mass shear displacement, as shown in the following example: Figure 6 and Figure 8 As shown in the figure, it is assumed that there is a large slope with a slope angle of 45° and a rock mass force γ = 26Kn / m 3 , slope height H = 300m, adhesion c = 4.14MPa, internal friction angle The Poisson's ratio μ is 0.21. The calculation method of the dynamic safety factor of this large slope is used as an example for verification.

[0133] like Figure 9 As shown in the figure, the static safety factor of the slope calculated using the traditional limit equilibrium method is 5.42.

[0134] The calculation method of the dynamic safety factor of the slope of the present invention is to first divide the potential sliding body into multiple blocks, such as Figure 10 As shown in , each bar has different sizes and the pressure acting on the sliding surface is also different. By combining formulas (13), (14) and (15), the shear constitutive curve of each bar can be obtained respectively, as shown in Figure 11 shown.

[0135] Substitute formula (13), formula (14) and formula (15) into the dynamic safety factor F of the slope s After calculating the expression, we can get the curve of slope safety factor changing with sliding body shear displacement, such as Figure 12 shown.

[0136] The slope safety factor changes with the shear displacement of the sliding body as shown in Figure 12 As shown. Figure 12 In the figure, when the shear displacement of the slope reaches a peak value of 0.595m, the safety factor reaches a maximum value of 4.98. The slope safety factor calculated based on the limit equilibrium method is 5.42. The difference between the calculation method of the present invention and the calculation result of the limit equilibrium method is (5.42-4.98) / 5.42=8.12%. The main reason for this phenomenon is that the slope safety factor calculated by the limit equilibrium method is a static safety factor. The limit equilibrium method ideally assumes that the shear strength at every point on the sliding surface reaches the maximum value. Figure 11 As can be seen from the figure, when the shear displacement reaches its maximum value of 0.595 m, many of the 59 shear constitutive curves have not yet reached their peak or have entered the residual strength stage. Therefore, the slope safety factor calculated based on shear displacement is lower than that calculated using the limit equilibrium method, providing higher early warning efficiency and enabling timely avoidance of unknown risks, thereby providing effective support and organizing personnel evacuation.

[0137] The above-described embodiments merely illustrate several embodiments of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass, characterized in that: The steps include: Step S1, establishing a relationship between shear stress τ and the total area S of the rock interface; Where τ represents the shear stress, that is, the average shear strength per unit area on the rock interface, S represents the total area of ​​the rock interface, and τ u and τ d They represent the shear strength of the undamaged unit and the damaged unit, S u and S d represent the total area of ​​undamaged cells and damaged cells respectively; Step S2, constructing a shear constitutive model of a small-sized rock specimen by combining the classical structural plane shear stress-displacement curve and Weibull distribution; Step S3: converting the parameters in the shear constitutive model of the small-sized rock sample into corresponding large-scale rock mass parameters to construct a shear constitutive model of the large-scale rock mass; Step S4: The shear displacement of the sliding body is brought into the shear constitutive model of the large rock mass to obtain the dynamic safety factor of the slope.

2. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 1, characterized in that: The steps of step S2 include: Step S21: Introduce the damage concept D, which represents the damage generated on the rock interface during the shearing process and is the area of ​​the damaged unit S. d The ratio of the total rock interface area S is: D=S d / S (2); Step S22: Combine formula (1) and formula (2) and divide both sides of formula (1) by S to obtain shear stress τ = τ u (1-D)+τ d D(3); Step S23: Analyze the shear stress-displacement curve of the classical structural surface, and do not destroy the unit shear strength τ u Satisfy τ u =ku(4), combining formula (3) and formula (4), we can get τ=ku(1-D)+Dτ d (5); where k represents the slope of the elastic phase of the shear stress-displacement curve of the classic structural surface, and u represents the shear displacement; Step S24: Use Weibull distribution to describe the number of damaged units. The function expression of Weibull distribution is: u k The displacement value corresponding to the dividing point between the elastic stage and the plastic yield stage in the shear stress-displacement curve is represented by the damage D, which is the integral of the Weibull distribution function with the shear displacement as the upper and lower limits: Step S25: Substitute formula (7) into formula (5) to obtain the shear constitutive model of the small-sized rock specimen:

3. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 2, characterized in that: After step S25, the method further includes: Step S26: Determine the parameters F1 and F2 in the shear constitutive model of the small-sized rock sample.

4. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 3, characterized in that: The specific steps of step S26 are as follows: Based on the peak point of the shear stress-displacement curve (u f , τ f ), and the derivative of the peak point is 0, we can get: The peak point (u f , τ f ) also satisfies formula (8). Combining formulas (8) and (9), we can obtain the calculation formulas for parameters F1 and F2 in the shear constitutive model of small-sized rock specimens:

5. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 4, characterized in that: The steps of step S3 include: Step S31: The slope k is expressed by the shear modulus G of the rock mass. The relationship between the slope k and the shear modulus G of the rock mass satisfies: Among them, A represents the reduction coefficient, and the value range of A is 0 to 1. interface represents the length of the shear surface, ε τ represents shear strain; Step S32: The shear modulus G can be expressed by the elastic modulus E. The relationship between the shear modulus G and the elastic modulus E satisfies: Where E represents the elastic modulus of the rock mass, and μ represents the Poisson's ratio of the rock mass; Step S33: Substitute formula (12) and formula (11) into formula (8) to obtain the shear constitutive model of large rock mass:

6. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 5, characterized in that: After step S33, the method further includes: Step S34: Determine the parameters F1 and F2 in the shear constitutive model of the large rock mass.

7. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 6, characterized in that: The specific steps of step S34 are as follows: Based on the Mohr-Coulomb criterion, the maximum shear resistance of large rock mass satisfies: Where σ represents the normal pressure on the sliding surface, represents the internal friction angle of the rock mass, and c represents the cohesion of the rock mass; Substituting formula (11), formula (12) and formula (13) into formula (10), we can obtain the calculation formulas for parameters F1 and F2 in the shear constitutive model of large rock mass:

8. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 7, characterized in that: The specific steps of step S4 are as follows: Divide the sliding mass on the slope into a plurality of cuboid blocks with approximately rectangular cross-sections; The weight of block i is known to be W i , the angle between bar i and the horizontal is α i , then the sliding force generated by block i is F slide-force =W i sinα i (16), The sliding force on block i is F antislide-force =t i L i (17), Among them, L i Indicates the bottom length of bar i; The shear displacement of the sliding body is brought into the shear constitutive model of the large rock mass. The safety factor of the slope is calculated based on the formula of the sum of the anti-sliding forces on all blocks divided by the sum of the sliding forces. The dynamic safety factor F of the slope can be obtained by combining formulas (15), (16) and (17): s The calculation expression is The subscript i of each parameter represents the parameter value corresponding to the i-th block.

9. The method for calculating the dynamic safety factor of a slope based on shear displacement of a large rock mass according to claim 1, wherein: After step S4, the following steps are also included: Step S5: determine whether the dynamic safety factor of the slope is greater than 1. When the dynamic safety factor of the slope is greater than 1, the slope is in a stable state; when the dynamic safety factor of the slope is not greater than 1, the slope is in an unstable state.

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