A landslide risk assessment method based on slope surface deformation

Abstract

This invention discloses a landslide risk assessment method based on slope surface deformation, belonging to the field of geological disaster engineering. The method includes: constructing a landslide cross-section model; dividing the landslide area into different landslide types; determining tensile and compressive failure zones; dividing the area into several soil strips; and constructing a formula for calculating the safety factor. The calculation formula is used to iteratively correct the internal friction angle of the sliding body and the residual friction angle on the sliding surface. The actual soil strip safety factor is calculated under the conditions of proportionality coefficients R=1 / 2 and R=1 / 3, and then corrected. Based on the final soil strip safety factor, a landslide risk coefficient is calculated to assess the stability of the landslide area. This invention utilizes surface deformation velocity and sliding surface location to determine the landslide failure mode, proposes a local Janbu method considering the properties of the failure zone to determine the residual shear strength of the sliding surface, and combines the proportion of the failure zone to assess the potential risk of the landslide—a high-precision stability assessment method.

Description

Technical Field

[0001] This invention relates to the field of geological disaster engineering, specifically to a landslide risk assessment method based on slope surface deformation. Background Technology

[0002] Landslide deformation is a time-dependent process of creep deformation and failure. It reflects the internal state of the landslide and can provide a basis for estimating landslide strength parameters and determining its stability. Using landslide deformation measurement data to deduce landslide strength for risk assessment is simple, efficient, and has a certain scientific basis; however, current assessment methods are relatively crude and urgently need improvement.

[0003] Currently, most scholars set the safety factor to 1 in the derivation of landslide strength parameters, roughly estimating the strength parameters based on the location of the sliding surface. A segmented method for calculating the safety factor has also been proposed, which analyzes the progressive failure process and failure area of ​​different types of landslides. Existing technology indicates that the maximum load that can be transmitted between soil masses can be calculated based on passive earth pressure, and an improved segmented method for calculating landslide thrust has been given. However, this method does not consider traction-type landslides, and in some cases may overestimate the horizontal thrust that the soil strips can withstand. Studies have found that the contribution of soil masses in different locations to overall stability varies, and directly assuming a safety factor of 1 for landslides in a creep state may have a significant error compared to reality. Furthermore, this method cannot be directly used for parameter inversion of landslide strength; the safety factor can only be solved when the landslide strength parameters and their evolution laws are known. Overall, current methods for inverting the strength parameters of landslides with arbitrary sliding surface shapes are still primitive and crude, lacking methods that consider the influence of different landslide deformation modes on the inversion of strength parameters. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a landslide risk assessment method based on slope surface deformation, and proposes a high-precision landslide stability assessment method for creep-type landslides, which are common in landslide disasters.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0006] A landslide risk assessment method based on slope surface deformation is provided, which includes:

[0007] S1: Collect geological parameters of the landslide area, construct a landslide cross-section model, set up a two-dimensional coordinate system on the landslide cross-section model, calculate the average deformation rate based on the surface displacement data of different slope points on the landslide cross-section, divide the landslide area into different landslide types, and determine the tensile failure zone and compression failure zone within different landslide types.

[0008] S2: Divide the tensile failure zone and the compressive failure zone into several soil strips, construct the expression for the bottom tangential force of the soil strips and the calculation formula for the safety factor of the tensile failure zone and the compressive failure zone;

[0009] S3: Based on the bottom edge inclination angle of the soil strip and the water content of the sliding body, set the assumed value of the internal friction angle of the sliding body and the assumed value of the residual friction angle on the sliding surface. Then, based on the expression of the bottom edge tangential force and the calculation formula of the safety factor, correct the internal friction angle of the sliding body and the residual friction angle on the sliding surface, and output the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface.

[0010] S4: Based on the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface, calculate the actual soil strip safety factor under the conditions of proportionality coefficients R=1 / 2 and R=1 / 3, correct the soil strip safety factor, and output the final soil strip safety factor. Earth strip safety factor ;

[0011] S5: Based on the final soil strip safety factor Earth strip safety factor Calculate the landslide risk coefficient and assess the stability of the landslide area.

[0012] Further, step S1 includes:

[0013] S11: Collect data on surface deformation, sliding surface location, water content of sliding body and weight of sliding body in the landslide area, determine the rear edge point A and front edge point C of the landslide, and draw a model of landslide section I-I based on the rear edge point A and front edge point C;

[0014] S12: Set up a two-dimensional coordinate system on the model of landslide section I-I. The positive x-axis of the two-dimensional coordinate system is along the sliding direction of the landslide body, and the positive y-axis is vertically upward.

[0015] S13: Collect surface displacement data at different slope points on landslide section I-I, and calculate the average deformation rate v from the rear edge point A to the front edge point C. 平均 Plot the relationship between the deformation rate curve and the average deformation rate line;

[0016] S14: Based on the number of intersections between the deformation rate curve and the average deformation rate line, the landslide area is divided into traction landslides, shove landslides, and composite landslides; and the stable zone and failure zone of different types of landslides are determined, including the compression failure zone and the tensile failure zone.

[0017] Further, step S2 includes:

[0018] S21: Starting from the critical point in the tensile failure zone and the compressive failure zone, draw a vertical line upwards and intersect the landslide surface at point T. Then, draw several vertical lines evenly in sequence in the tensile failure zone and the compressive failure zone. These vertical lines intersect the landslide surface, dividing the tensile failure zone and the compressive failure zone into several uniform soil strips.

[0019] S22: Construct a calculation model for the horizontal thrust P1 on the upper side of the first soil strip near the boundary within the tensile failure zone and the compressive failure zone;

[0020] , ;

[0021] in, The weight of the sliding body. The length of the boundary line closest to the first soil strip. The active earth pressure coefficient, The surface slope of the first soil strip;

[0022] When calculating the horizontal thrust P1 on the upper side of the first soil strip within the tensile failure zone, the active earth pressure coefficient... In the calculation formula Pick When calculating the horizontal thrust P1 on the upper side of the first soil strip within the compression failure zone, the active earth pressure coefficient is... In the calculation formula Pick ;

[0023] S23: Perform stress analysis on the i-th soil strip in the tensile failure zone and the compression failure zone. Based on the horizontal thrust P1 calculation model, construct the vertical force balance equation, the horizontal force balance equation and the moment balance equation to obtain the set of force balance equations.

[0024] ;

[0025] in, Let be the weight of the i-th soil strip. Let the normal force at the bottom edge of the i-th soil strip be . Let be the tangential force at the bottom edge of the i-th soil strip. The horizontal thrust on the upper side of the i-th soil strip. Let be the tangential force on the upper side of the i-th soil strip. , Let be 1 / 3 of the height and width of the i-th soil strip, respectively. Let be the inclination angle of the base of the i-th soil strip. Let be the change in tangential force on the upper side of the i-th soil strip. This represents the change in horizontal thrust on the upper side of the i-th soil strip;

[0026] S24: For the tensile failure zone, the horizontal thrust P on the lower side of the last soil strip n is known. n+1 Given that the horizontal thrust P1 on the upper side of the first soil strip is greater than 0, we obtain the following relationship:

[0027] ;

[0028] For the compression failure zone, the horizontal thrust P1 = 0 on the upper side of the first soil mass and the horizontal thrust P on the lower side of the nth soil mass are known. n+1 >0, yielding the relation:

[0029] ;

[0030] S25: Substitute the horizontal force equilibrium equation into the relation in step S24 to obtain the following relation:

[0031] ;

[0032] S26: Based on the Mohr-Coulomb strength theory, the transformed form of the relation in step S25 is obtained:

[0033] ;

[0034] in, For the cohesive force of the slip surface, F s For the safety factor of the tensile failure zone and the compressive failure zone, The residual friction angle on the sliding surface;

[0035] S27: Define the initial safety factor F for the soil strip. s =1.0, cohesion =0, and the bottom tangential force of the i-th soil strip is obtained according to the force equilibrium equations and the modified form of step S26. The expression;

[0036] , ;

[0037] in, For angular relationship variables;

[0038] S28: Based on the relationship in step S25 and the bottom tangential force The expression is used to obtain the safety factor F for the tensile failure zone and the compressive failure zone. s The calculation formula;

[0039] .

[0040] Further, step S3 includes:

[0041] S31: Based on the inclination angle of the base of the first soil strip The assumed value of the internal friction angle of the sliding body is calculated using the proportionality coefficient R based on the water content of the sliding body. Assumed value of the residual friction angle on the sliding surface ;

[0042] , ;

[0043] S32: The assumed value of the internal friction angle and the assumed value of the residual friction angle Input the tangential force at the bottom edge In the expression, the assumed values ​​of the angular relationship variables are calculated. ;

[0044] S33: The assumed value of the residual friction angle Input the tangential force at the bottom edge In the expression, calculate the trial-calculated tangential force at the base. And based on the relationship between the internal friction angle of the sliding body and the residual friction angle on the sliding surface. Calculate the assumed value based on the residual friction angle. Correction value of the internal friction angle And the corrected horizontal thrust is calculated based on the horizontal thrust calculation model. ;

[0045] S34: Based on the corrected horizontal thrust Calculate the change in thrust on the upper side and input it into the horizontal force equilibrium equation to calculate the change in tangential force on the upper side. Then, based on the safety factor F s The calculation formula is used to derive the corrected residual friction angle on the sliding surface. ;

[0046] ;

[0047] S35: Compare the corrected residual friction angle Compared with the assumed value If the error is less than or equal to 5%, then the assumed value of the internal friction angle is... and the assumed value of the residual friction angle As the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface; otherwise, proceed to step S36;

[0048] S36: Based on the corrected residual friction angle Re-divide soil strips in the tensile and compressive failure zones, and use the corrected residual friction angle. Correction value for internal friction angle Using these as the assumed values ​​for the internal friction angle and the residual friction angle respectively, return to step S31 and repeat steps S31-S35 until the error between the corrected residual friction angle and the assumed value of the residual friction angle is less than or equal to 5%; output the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface. ;

[0049] S37: Obtain the final residual friction angle on the sliding surface corresponding to the tensile failure zone on traction-type and composite landslides. The final residual friction angle on the sliding surface of the corresponding compression failure zone on shoal-type and composite landslides. ; and the final residual friction angle , Unified definition ;

[0050] .

[0051] Further, step S4 includes:

[0052] S41: Based on the current division of the soil strips into tensile and compressive failure zones, define the initial safety factor for the soil strips. =1.0, Change in tangential force on the upper side =0; Calculate the angular relationship variable of the current soil strip under the condition of proportional coefficient R=1 / 2. and the tangential force at the bottom edge ;

[0053] , ;

[0054] S42: Based on the current angle relationship variable of the soil strip and the tangential force at the bottom edge Calculate the actual safety factor of soil strips under the condition of proportionality factor R=1 / 2. ;

[0055] ;

[0056] S43: Compare the actual safety factor of the soil strip. With initial safety factor If the error is less than or equal to 5%, the actual soil strip safety factor will be output. As the final soil strip safety factor; otherwise, proceed to step S44;

[0057] S44: Utilizing the actual soil strip safety factor Replace the initial safety factor Execute step S41 to calculate the new angular relationship variable. and the tangential force at the bottom edge ; and based on new perspective relationship variables and the tangential force at the bottom edge Calculate the difference in horizontal thrust on the upper side between soil strips. ;

[0058] ;

[0059] S45: Based on the difference Calculate the horizontal thrust on the upper side of each soil strip. ;

[0060] ;

[0061] in, Let i be the set of soil strips above the i-th soil strip;

[0062] S46: Based on horizontal thrust Calculate the tangential force for each soil strip. Difference between tangential forces ;

[0063] , ;

[0064] in, Let be the tangential force of the (i+1)th soil strip;

[0065] S47: The difference in tangential force Substitute this information into step S42 to calculate the new soil strip safety factor. And compare the safety factors of the new soil strips. Compared with the actual soil strip safety factor If the error is less than or equal to 5%, then output a new soil strip safety factor. As the final earthen strip safety factor Otherwise, return to step S44 and adjust the new soil strip safety factor. Replace the initial safety factor Repeat steps 44-S47 until the final soil strip safety factor is output. ;

[0066] S48: Repeat steps S41-S47 to output the final soil strip safety factor under the condition of proportionality coefficient R=1 / 3. .

[0067] Further, step S5 includes:

[0068] S51: Based on the final soil strip safety factor and the final soil strip safety factor Calculate landslide risk score ;

[0069] ;

[0070] in, Based on the soil strip safety factor Earth strip safety factor Landslide safety score;

[0071] S52: Set landslide risk score threshold ,like If the stability of the landslide area is good, then the stability of the landslide area is determined to be good; otherwise, the stability of the landslide area is determined to be poor.

[0072] The beneficial effects of this invention are as follows: This invention uses the surface deformation rate and the location of the slip surface to determine the landslide failure mode, and divides the failure area and the stable area. Taking the failure area as the main research object, it proposes a local Janbu method that considers the properties of the failure area to determine the residual shear strength of the slip surface. The safety factor is calculated based on the residual strength determined according to different water contents. Combined with the proportion of the failure area, a high-precision stability assessment method is used to evaluate the potential risk of the landslide. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of a landslide risk assessment method based on slope surface deformation.

[0074] Figure 2 This is a schematic diagram illustrating the collection of surface displacement data in the landslide area.

[0075] Figure 3 This is a schematic diagram of the landslide section I-I model.

[0076] Figure 4 This is a graph showing the relationship between the deformation rate curve and the average deformation rate line of a traction landslide.

[0077] Figure 5 This is a graph showing the relationship between the deformation rate curve and the average deformation rate line of a shoal landslide.

[0078] Figure 6 This is a graph showing the relationship between the deformation rate curve and the average deformation rate line of a complex landslide.

[0079] Figure 7 This is a diagram showing the division between the stable zone and the tensile failure zone of a traction landslide.

[0080] Figure 8 This is a diagram showing the division between the stable zone and the tensile failure zone of a shoal landslide.

[0081] Figure 9 This is a diagram showing the division between the stable zone and the tensile failure zone of a complex landslide.

[0082] Figure 10 This is a schematic diagram showing the soil strip division and boundary conditions of the tensile failure zone.

[0083] Figure 11 This is a schematic diagram showing the soil strip division and boundary conditions of the compression failure zone.

[0084] Figure 12 This is a schematic diagram of the stress analysis of the soil strip.

[0085] Figure 13 This is a flowchart of the intensity inversion process for the damaged area.

[0086] Figure 14 This is a flowchart for calculating the safety factor under residual strength.

[0087] Figure 15 A schematic diagram of soil strip division for calculating the safety factor using the Janbu method. Detailed Implementation

[0088] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0089] like Figure 1 As shown, a landslide risk assessment method based on slope surface deformation includes the following steps:

[0090] S1: Collect geological parameters of the landslide area, construct a model of the landslide cross-section, and set up a two-dimensional coordinate system on the landslide cross-section model. Based on the surface displacement data of different slope points on the landslide cross-section, calculate the average deformation rate, divide the landslide area into different landslide types, and determine the tensile failure zone and compressive failure zone within each landslide type. Step S1 specifically includes:

[0091] S11: Collect data on surface deformation, sliding surface location, water content of the sliding mass, and weight of the sliding mass in the landslide area; determine the rear edge point A and the front edge point C of the landslide; and draw a model of landslide section I-I based on the rear edge point A and the front edge point C, such as... Figure 2 As shown;

[0092] S12: Set up a two-dimensional coordinate system on the model of landslide section I-I. The positive x-axis of the two-dimensional coordinate system is along the sliding direction of the landslide body, and the positive y-axis is vertically upward.

[0093] S13: Collect surface displacement data at different slope points on landslide section I-I, such as Figure 3 As shown, the average deformation rate v from trailing edge point A to leading edge point C is calculated.平均 Plot the relationship between the deformation rate curve and the average deformation rate line;

[0094] S14: Based on the number of intersections between the deformation rate curve and the average deformation rate line, the landslide area is divided into traction landslides, shove landslides, and composite landslides; and the stable zone and failure zone of different types of landslides are determined, including the compression failure zone and the tensile failure zone.

[0095] Specifically, the classification method for different types of landslides is as follows:

[0096] like Figure 4 As shown, the landslide deformation rate curve intersects the average deformation rate line at only one point. And the intersection point The deformation rate from the leading edge point C to the average deformation rate is greater than that from the trailing edge point A to the intersection point. The deformation rate is less than the average deformation rate, and the landslide with this deformation mode is called a traction landslide.

[0097] like Figure 5 As shown, the landslide deformation rate curve intersects the average deformation rate line at only one point. And the intersection point The deformation rate to the leading edge point C is less than the average deformation rate, while the deformation rate from the trailing edge point A to the intersection point is less. When the deformation rate is greater than the average deformation rate, the landslide with this deformation mode is called a burial landslide.

[0098] like Figure 6 As shown, the landslide deformation rate curve intersects the average deformation rate line at two points. , Intersection The deformation rate from the leading edge point C to the average deformation rate is greater than that from the trailing edge point A to the intersection point. The deformation rate is greater than the average deformation rate, at the intersection point To the intersection When the deformation rate at a point is less than the average deformation rate, the landslide with this deformation mode is a composite landslide.

[0099] Specifically, the methods for dividing the stable zone and the failure zone for different landslide types are as follows:

[0100] like Figure 7 As shown, the delineation of the failure zone and the stable zone in a traction landslide is as follows:

[0101] The intersection of the deformation rate curve and the average deformation rate line of a traction landslide is point B on the slope surface; the landslide mass below point B is the failure zone, which is defined as the tensile failure zone of a traction landslide; the upper boundary of the tensile failure zone is the section corresponding to line BD, and the critical point D is located on the landslide surface, with the angle between line BD and the landslide surface being 45°.o + / 2, the intersection of line BD and the sliding surface is the critical point D. The internal friction angle of the sliding body is currently unknown and needs to be determined in subsequent steps. Therefore, the tensile failure zone of the traction landslide is the area enclosed by BDC, and the stable zone is the area enclosed by BDA. For example... Figure 8 As shown, the delineation of the failure zone and the stable zone in a shoal landslide is as follows:

[0102] The intersection of the deformation rate curve and the average deformation rate line of a shoal landslide is also point B on the slope surface. The landslide mass above point B is the failure zone, which is defined as the compression failure zone of a shoal landslide. The lower boundary of the compression failure zone is the section corresponding to line BD. The critical point D is located on the sliding surface, and the angle between line BD and the landslide surface is 45 degrees. o - / 2, the intersection of line BD and the slip surface is the critical point D. Therefore, the compression failure zone of a shoal landslide is the area enclosed by BDA, and the stable zone is the area enclosed by BDC.

[0103] like Figure 9 As shown, the delineation of the failure zone and the stable zone in a complex landslide is as follows:

[0104] The intersection points of the deformation rate curve and the average deformation rate line of the composite landslide are slope surface points B1 and B2. The landslide mass above slope surface point B1 is the compression failure zone, and the landslide mass below slope surface point B2 is the tensile failure zone. The lower boundary of the compression failure zone is the section corresponding to line B1D1. The critical point D1 is located on the sliding surface, and the angle between line B1D1 and the landslide surface is 45 degrees. o - / 2, the intersection of line B1D1 and the slip surface is the critical point D1, and the compressive failure zone is the area enclosed by B1D1A. In the composite landslide, the upper boundary of the tensile failure zone is the section corresponding to line B2D2, and the critical point D2 is located on the slip surface. The angle between line B2D2 and the landslide surface is 45°. o + / 2, the intersection of line B2D2 and the sliding surface is the critical point D2, and the tensile failure zone is the area enclosed by B2D2C. Therefore, the stable region is the area enclosed by B1D1D2B2.

[0105] S2: Divide the tensile failure zone and the compressive failure zone into several soil strips, construct the expression for the bottom tangential force of the soil strips, and the calculation formula for the safety factor of the tensile failure zone and the compressive failure zone.

[0106] This embodiment proposes a simplified local Janbu method for inverting sliding surface strength parameters. The basic assumptions for the inversion calculation are as follows:

[0107] 1. The soil and rock mass in the failure zone (tensile failure zone and compressive failure zone) is homogeneous, has a known unit weight, is in a state of failure, and obeys the Mohr-Colomb strength criterion.

[0108] 2. The location of the sliding surface is known. The sliding surface and the sliding body in the failure zone obey the Colomb strength criterion. The sliding body in the entire failure zone is uniform and has the same properties. The strength parameters on the sliding surface in the failure zone are the same.

[0109] 3. The cohesion of the sliding body and the cohesion of the sliding surface are both assumed to be 0, and the strength parameters mainly consider the influence of the friction angle;

[0110] 4. The strength characteristics of the sliding body and its water content determine the strength characteristics of the sliding surface. Assume the internal friction angle of the sliding body is... The residual friction angle on the sliding surface is And satisfy: R is the proportionality coefficient, which is set to 1 / 3 to 1 / 2. It is recommended to take 1 / 3 when the sliding body is saturated and 1 / 2 when the water content of the sliding body is low. The local safety factor Fs of the failure zone is 1.0.

[0111] Step S2 specifically includes:

[0112] S21: As Figure 10 and Figure 11 As shown, vertical lines are drawn upwards from the critical points D2 and D in the tensile failure zone and the compressive failure zone, intersecting the landslide surface at point T. Several vertical lines are drawn uniformly in sequence in the tensile failure zone and the compressive failure zone, and these lines intersect the landslide surface, dividing the tensile failure zone and the compressive failure zone into several uniform soil strips.

[0113] S22: Construct a calculation model for the horizontal thrust P1 on the upper side of the first soil strip near the boundary within the tensile failure zone and the compressive failure zone;

[0114] , ;

[0115] in, The weight of the sliding body. The length of the boundary line DT, D2T, or D1T closest to the boundary of the first soil strip. The active earth pressure coefficient, The surface slope of the first soil strip; when calculating the horizontal thrust P1 on the upper side of the first soil strip within the tensile failure zone, the active earth pressure coefficient is... In the calculation formula Pick When calculating the horizontal thrust P1 on the upper side of the first soil strip within the compression failure zone, the active earth pressure coefficient is... In the calculation formula Pick ;

[0116] S23: As Figure 12 As shown, the stress analysis of the i-th soil strip in the tensile failure zone and the compression failure zone is carried out. Based on the horizontal thrust P1 calculation model, the vertical force balance equation, the horizontal force balance equation and the moment balance equation are constructed to obtain the force balance equation set.

[0117] ;

[0118] in, Let be the weight of the i-th soil strip. Let the normal force at the bottom edge of the i-th soil strip be . Let be the tangential force at the bottom edge of the i-th soil strip. The horizontal thrust on the upper side of the i-th soil strip. Let be the tangential force on the upper side of the i-th soil strip. , These represent 1 / 3 of the height and width of the i-th soil strip, respectively. The point of application of the force is generally 1 / 3 of the height above the bottom edge of the soil strip. Let be the inclination angle of the base of the i-th soil strip. Let be the change in tangential force on the upper side of the i-th soil strip. This represents the change in horizontal thrust on the upper side of the i-th soil strip;

[0119] S24: For the tensile failure zone, the horizontal thrust P on the lower side of the last soil strip n is known. n+1 Given that the horizontal thrust P1 on the upper side of the first soil strip is greater than 0, we obtain the following relationship:

[0120] ;

[0121] For the compression failure zone, the horizontal thrust P1 = 0 on the upper side of the first soil mass and the horizontal thrust P on the lower side of the nth soil mass are known. n+1 >0, yielding the relation:

[0122] ;

[0123] S25: Substitute the horizontal force equilibrium equation into the relation in step S24 to obtain the following relation:

[0124] ;

[0125] S26: Based on the Mohr-Coulomb strength theory, the transformed form of the relation in step S25 is obtained:

[0126] ;

[0127] in, For the cohesive force of the slip surface, F s For the safety factor of the tensile failure zone and the compressive failure zone, The residual friction angle on the sliding surface;

[0128] S27: Define the initial safety factor F for the soil strip. s =1.0, cohesion =0, and the bottom tangential force of the i-th soil strip is obtained according to the force equilibrium equations and the modified form of step S26. The expression;

[0129] , ;

[0130] in, For angular relationship variables;

[0131] S28: Based on the relationship in step S25 and the bottom tangential force The expression is used to obtain the safety factor F for the tensile failure zone and the compressive failure zone. s The calculation formula;

[0132] .

[0133] S3: Based on the bottom inclination angle of the soil strip and the water content of the sliding body, set the assumed values ​​for the internal friction angle of the sliding body and the residual friction angle on the sliding surface. Then, based on the expression for the bottom tangential force and the calculation formula for the safety factor, correct the internal friction angle of the sliding body and the residual friction angle on the sliding surface, and output the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface. Step S3 specifically includes:

[0134] S31: As Figure 13 As shown, based on the inclination angle of the base of the first soil strip... The assumed value for calculating the internal friction angle of the sliding body is the proportionality coefficient R of the water content of the sliding body. Assumed value of the residual friction angle on the sliding surface ;

[0135] , ;

[0136] S32: The assumed value of the internal friction angle and the assumed value of the residual friction angle Input the tangential force at the bottom edge In the expression, the assumed values ​​of the angular relationship variables are calculated. ;

[0137] S33: The assumed value of the residual friction angle Input the tangential force at the bottom edge In the expression, calculate the trial-calculated tangential force at the base. And based on the relationship between the internal friction angle of the sliding body and the residual friction angle on the sliding surface. Calculate the assumed value based on the residual friction angle. Correction value of the internal friction angle And the corrected horizontal thrust is calculated based on the horizontal thrust calculation model. ;

[0138] S34: Based on the corrected horizontal thrust Calculate the change in thrust on the upper side and input it into the horizontal force equilibrium equation to calculate the change in tangential force on the upper side. Then, based on the safety factor F s The calculation formula is used to derive the corrected residual friction angle on the sliding surface. ;

[0139] ;

[0140] S35: Compare the corrected residual friction angle Compared with the assumed value If the error is less than or equal to 5%, then the assumed value of the internal friction angle is... and the assumed value of the residual friction angle As the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface; otherwise, proceed to step S36;

[0141] S36: Based on the corrected residual friction angle Re-divide soil strips in the tensile and compressive failure zones, and use the corrected residual friction angle. Correction value for internal friction angle Using these as the assumed values ​​for the internal friction angle and the residual friction angle respectively, return to step S31 and repeat steps S31-S35 until the error between the corrected residual friction angle and the assumed value of the residual friction angle is less than or equal to 5%; output the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface. ;

[0142] S37: Obtain the final residual friction angle on the sliding surface corresponding to the tensile failure zone on traction-type and composite landslides. The final residual friction angle on the sliding surface of the corresponding compression failure zone on shoal-type and composite landslides. ; and the final residual friction angle , Unified definition ;

[0143] .

[0144] S4: Based on the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface, calculate the actual soil strip safety factor under the conditions of proportionality coefficients R=1 / 2 and R=1 / 3, correct the soil strip safety factor, and output the final soil strip safety factor. Earth strip safety factor Step S4 specifically includes:

[0145] S41: As Figure 14 and Figure 15 As shown, based on the current division of the soil strips into tensile and compressive failure zones, the initial safety factor of the soil strips is defined. =1.0, Change in tangential force on the upper side =0; Calculate the angular relationship variable of the current soil strip under the condition of proportional coefficient R=1 / 2. and the tangential force at the bottom edge ;

[0146] , ;

[0147] S42: Based on the current angle relationship variable of the soil strip and the tangential force at the bottom edge Calculate the actual safety factor of soil strips under the condition of proportionality factor R=1 / 2. ;

[0148] ;

[0149] S43: Compare the actual safety factor of the soil strip. With initial safety factor If the error is less than or equal to 5%, the actual soil strip safety factor will be output. As the final earthen strip safety factor Otherwise, proceed to step S44;

[0150] S44: Utilizing the actual soil strip safety factor Replace the initial safety factor Execute step S41 to calculate the new angular relationship variable. and the tangential force at the bottom edge ; and based on new perspective relationship variables and the tangential force at the bottom edge Calculate the difference in horizontal thrust on the upper side between soil strips. ;

[0151] ;

[0152] S45: Based on the difference Calculate the horizontal thrust on the upper side of each soil strip. ;

[0153] ;

[0154] in, Let i be the set of soil strips above the i-th soil strip;

[0155] S46: Based on horizontal thrust Calculate the tangential force for each soil strip. Difference between tangential forces ;

[0156] , ;

[0157] in, Let be the tangential force of the (i+1)th soil strip;

[0158] S47: The difference in tangential force Substitute this information into step S42 to calculate the new soil strip safety factor. And compare the safety factors of the new soil strips. Compared with the actual soil strip safety factor If the error is less than or equal to 5%, then output a new soil strip safety factor. As the final earthen strip safety factor Otherwise, return to step S44 and adjust the new soil strip safety factor. Replace the initial safety factor Repeat steps 44-S47 until the final soil strip safety factor is output. ;

[0159] S48: Repeat steps S41-S47 to output the final soil strip safety factor under the condition of proportionality coefficient R=1 / 3. .

[0160] S5: Based on the final soil strip safety factor Earth strip safety factor Calculate the landslide risk coefficient and assess the stability of the landslide area. Step S5 specifically includes:

[0161] This embodiment uses a weighted scoring-grading rapid risk assessment method to determine the stability risk level of a landslide. The four indicators are: the safety factor corresponding to the residual strength under different water contents, the proportion of the landslide failure zone, the proportion of the sliding surface failure zone, and the current rainfall situation.

[0162] S51: Based on the final soil strip safety factor and the final soil strip safety factor Calculate landslide risk score ;

[0163] ;

[0164] in, Based on the soil strip safety factor Earth strip safety factor Landslide safety score;

[0165] In this embodiment, the standardized scoring table for the relevant evaluation indicators is shown in Table 1 below:

[0166] Table 1 Standardized scoring table for evaluation indicators

[0167]

[0168] S52: Set landslide risk score threshold ,like If the stability of the landslide area is good, then the stability of the landslide area is determined to be good; otherwise, the stability of the landslide area is determined to be poor.

[0169] This embodiment is based on the landslide risk score threshold. A stability risk assessment was conducted on the landslide, and the stability risk rating is as follows:

[0170] 0–30 points: Low risk (green), the slope is in a relatively stable state and can be monitored at the regular frequency.

[0171] 30–60 points: Medium risk (yellow), local signs of initial deterioration of the slope are emerging, and monitoring frequency needs to be increased.

[0172] 60–80 points: High risk (orange), the landslide has entered the accelerated deformation stage, an orange alert is activated, the monitoring frequency is increased, and local reinforcement is carried out in a timely manner.

[0173] 80–100 points: Extremely high risk (red). The slope is in a critical state of instability and may slide completely at any time. Emergency evacuation of personnel and closure of roads are required, and emergency response plans must be activated.

Claims

1. A landslide risk assessment method based on slope surface deformation, characterized in that, include: S1: Collect geological parameters of the landslide area, construct a landslide cross-section model, set up a two-dimensional coordinate system on the landslide cross-section model, calculate the average deformation rate based on the surface displacement data of different slope points on the landslide cross-section, divide the landslide area into different landslide types, and determine the tensile failure zone and compression failure zone within different landslide types. S2: Divide the tensile failure zone and the compressive failure zone into several soil strips, construct the expression for the bottom tangential force of the soil strips and the calculation formula for the safety factor of the tensile failure zone and the compressive failure zone; S3: Based on the bottom edge inclination angle of the soil strip and the water content of the sliding body, set the assumed values ​​of the internal friction angle of the sliding body and the residual friction angle on the sliding surface, and correct the internal friction angle of the sliding body and the residual friction angle on the sliding surface based on the expression of the bottom edge tangential force and the calculation formula of the safety factor, and output the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface. S4: Based on the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface, calculate the actual soil strip safety factor under the conditions of proportionality coefficients R=1 / 2 and R=1 / 3, correct the soil strip safety factor, and output the final soil strip safety factor. Earth strip safety factor ; S5: Based on the final earthen strip safety factor Earth strip safety factor Calculate the landslide risk coefficient and assess the stability of the landslide area.

2. The landslide risk assessment method based on slope surface deformation according to claim 1, characterized in that, Step S1 includes: S11: Collect data on surface deformation, sliding surface location, water content of sliding body and weight of sliding body in the landslide area, determine the rear edge point A and front edge point C of the landslide, and draw a model of landslide section I-I based on the rear edge point A and front edge point C; S12: Set up a two-dimensional coordinate system on the model of landslide section I-I. The positive x-axis of the two-dimensional coordinate system is along the sliding direction of the landslide body, and the positive y-axis is vertically upward. S13: Collect surface displacement data at different slope points on landslide section I-I, and calculate the average deformation rate v from the rear edge point A to the front edge point C. 平均 Plot the relationship between the deformation rate curve and the average deformation rate line; S14: Based on the number of intersections between the deformation rate curve and the average deformation rate line, the landslide area is divided into traction landslides, shove landslides, and composite landslides; and the stable zone and failure zone of different types of landslides are determined, including the compression failure zone and the tensile failure zone.

3. The landslide risk assessment method based on slope surface deformation according to claim 2, characterized in that, Step S2 includes: S21: Starting from the critical point in the tensile failure zone and the compressive failure zone, draw a vertical line upwards and intersect the landslide surface at point T. Then, draw several vertical lines evenly in sequence in the tensile failure zone and the compressive failure zone. These vertical lines intersect the landslide surface, dividing the tensile failure zone and the compressive failure zone into several uniform soil strips. S22: Construct a calculation model for the horizontal thrust P1 on the upper side of the first soil strip near the boundary within the tensile failure zone and the compressive failure zone; ， ； in, The weight of the sliding body. The length of the boundary line closest to the boundary on the first soil strip. The active earth pressure coefficient, The surface slope of the first soil strip; When calculating the horizontal thrust P1 on the upper side of the first soil strip within the tensile failure zone, the active earth pressure coefficient... In the calculation formula Pick When calculating the horizontal thrust P1 on the upper side of the first soil strip within the compression failure zone, the active earth pressure coefficient is... In the calculation formula Pick ; S23: Perform stress analysis on the i-th soil strip in the tensile failure zone and the compression failure zone. Based on the horizontal thrust P1 calculation model, construct the vertical force balance equation, the horizontal force balance equation and the moment balance equation to obtain the set of force balance equations. ； in, Let be the weight of the i-th soil strip. Let the normal force at the bottom edge of the i-th soil strip be . Let be the tangential force at the bottom edge of the i-th soil strip. The horizontal thrust on the upper side of the i-th soil strip. Let be the tangential force on the upper side of the i-th soil strip. , Let be 1 / 3 of the height and width of the i-th soil strip, respectively. Let be the inclination angle of the base of the i-th soil strip. Let be the change in tangential force on the upper side of the i-th soil strip. This represents the change in horizontal thrust on the upper side of the i-th soil strip; S24: For the tensile failure zone, the horizontal thrust P on the lower side of the last soil strip n is known. n+1 Given that the horizontal thrust P1 on the upper side of the first soil strip is greater than 0, we obtain the following relationship: ； For the compression failure zone, the horizontal thrust P1 = 0 on the upper side of the first soil mass and the horizontal thrust P on the lower side of the nth soil mass are known. n+1 >0, yielding the relation: ； S25: Substitute the horizontal force equilibrium equation into the relation in step S24 to obtain the following relation: ； S26: Based on the Mohr-Coulomb strength theory, the transformed form of the relation in step S25 is obtained: ； in, For the cohesive force of the slip surface, F s For the safety factor of the tensile failure zone and the compressive failure zone, The residual friction angle on the sliding surface; S27: Define the initial safety factor F for the soil strip. s =1.0, cohesion =0, and the bottom tangential force of the i-th soil strip is obtained according to the force equilibrium equations and the modified form of step S26. The expression; ， ； in, For angular relationship variables; S28: Based on the relationship in step S25 and the bottom tangential force The expression is used to obtain the safety factor F for the tensile failure zone and the compressive failure zone. s The calculation formula; 。 4. The landslide risk assessment method based on slope surface deformation according to claim 3, characterized in that, Step S3 includes: S31: Based on the inclination angle of the base of the first soil strip The assumed value of the internal friction angle of the sliding body is calculated using the proportionality coefficient R based on the water content of the sliding body. Assumed value of the residual friction angle on the sliding surface ; ， ； S32: The assumed value of the internal friction angle and the assumed value of the residual friction angle Input the tangential force at the bottom edge In the expression, the assumed values ​​of the angular relationship variables are calculated. ; S33: The assumed value of the residual friction angle Input the tangential force at the bottom edge In the expression, calculate the trial tangential force at the base. And based on the relationship between the internal friction angle of the sliding body and the residual friction angle on the sliding surface. Calculate the assumed value based on the residual friction angle. Correction value of the internal friction angle And the corrected horizontal thrust is calculated based on the horizontal thrust calculation model. ; S34: Based on the corrected horizontal thrust Calculate the change in thrust on the upper side and input it into the horizontal force equilibrium equation to calculate the change in tangential force on the upper side. Then, based on the safety factor F s The calculation formula is used to derive the corrected residual friction angle on the sliding surface. ; ； S35: Compare the corrected residual friction angle Compared with the assumed value If the error is less than or equal to 5%, then the assumed value of the internal friction angle is... and the assumed value of the residual friction angle As the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface; otherwise, proceed to step S36; S36: Based on the corrected residual friction angle Re-divide soil strips in the tensile and compressive failure zones, and use the corrected residual friction angle. Correction value for internal friction angle Using these as the assumed values ​​for the internal friction angle and the residual friction angle, respectively, return to step S31 and repeat steps S31-S35 until the error between the corrected residual friction angle and the assumed value of the residual friction angle is less than or equal to 5%; output the final internal friction angle of the sliding body and the final residual friction angle on the sliding surface. ; S37: Obtain the final residual friction angle on the sliding surface corresponding to the tensile failure zone on traction-type and composite landslides. The final residual friction angle on the sliding surface of the corresponding compression failure zone on shoal-type and composite landslides. ; and the final residual friction angle , Unified definition ; 。 5. The landslide risk assessment method based on slope surface deformation according to claim 4, characterized in that, Step S4 includes: S41: Based on the current division of the soil strips into tensile and compressive failure zones, define the initial safety factor for the soil strips. =1.0, Change in tangential force on the upper side =0; Calculate the angular relationship variable of the current soil strip under the condition of proportional coefficient R=1 / 2. and the tangential force at the bottom edge ; ， ； S42: Based on the current angle relationship variable of the soil strip and the tangential force at the bottom edge Calculate the actual safety factor of soil strips under the condition of proportionality factor R=1 / 2. ; ； S43: Compare the actual safety factor of the soil strip. With initial safety factor If the error is less than or equal to 5%, the actual soil strip safety factor will be output. As the final soil strip safety factor; otherwise, proceed to step S44; S44: Utilizing the actual soil strip safety factor Replace the initial safety factor Execute step S41 to calculate the new angular relationship variable. and the tangential force at the bottom edge ; and based on new perspective relationship variables and the tangential force at the bottom edge Calculate the difference in horizontal thrust on the upper side between soil strips. ; ； S45: Based on the difference Calculate the horizontal thrust on the upper side of each soil strip. ; ； in, Let i be the set of soil strips above the i-th soil strip; S46: Based on horizontal thrust Calculate the tangential force for each soil strip. Difference between tangential forces ; ， ； in, Let be the tangential force of the (i+1)th soil strip; S47: The difference in tangential force Substitute this information into step S42 to calculate the new soil strip safety factor. And compare the safety factors of the new soil strips. Compared with the actual soil strip safety factor If the error is less than or equal to 5%, then output a new soil strip safety factor. As the final earthen strip safety factor Otherwise, return to step S44 and adjust the new soil strip safety factor. Replace the initial safety factor Repeat steps 44-S47 until the final soil strip safety factor is output. ; S48: Repeat steps S41-S47 to output the final soil strip safety factor under the condition of proportionality coefficient R=1 / 3. .

6. The landslide risk assessment method based on slope surface deformation according to claim 5, characterized in that, Step S5 includes: S51: Based on the final soil strip safety factor and the final soil strip safety factor Calculate landslide risk score ; ； in, Based on the soil strip safety factor Earth strip safety factor Landslide safety score; S52: Set landslide risk score threshold ,like If the stability of the landslide area is good, then the stability of the landslide area is determined to be good; otherwise, the stability of the landslide area is determined to be poor.

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