A slope deformation early warning and slope state determination method

Abstract

The present application belongs to the field of highway slope engineering risk assessment and early warning, and particularly relates to a slope deformation early warning and slope state determination method, wherein the early warning method comprises the following steps: S1, constructing a damage factor; S2, drawing a t-D(t) curve; S3, defining an expression of the time change rate of the damage factor, obtaining a curve mutation point, and identifying each stage of slope deformation; S4, establishing a regression relationship between relative time T and the change rate of the damage factor per unit time, and using regression to predict the change trend; S5, determining an expression of the prediction time of slope landslide. The slope state determination method combines the shear strength parameters of the slope with the damage factor on the basis of the curve to evaluate the current state stability of the slope. The present application is based on the principle of damage mechanics, has clear physical and mechanical significance, is intuitive and easy to understand, has strong scientificity, advancement and practical value, and provides a new approach for the development of slope landslide early warning and prediction as well as state determination.

Description

Technical Field

[0001] This invention relates to the field of risk assessment and early warning for highway slope engineering, specifically to a method for early warning of slope deformation and determination of slope status. Background Technology

[0002] Landslide early warning and current condition assessment of slopes are among the most challenging issues in geotechnical engineering and engineering geology. Accurately assessing slope condition and predicting slope instability and landslide geological disasters is of great significance for protecting people's lives and property and maintaining the safe operation of infrastructure such as highways and railways.

[0003] For landslide early warning of slope deformation, the deformation process is usually divided into three stages: initial deformation, isotropic deformation, and accelerated deformation. Based on this, existing technologies have proposed the "tangent angle" theory based on slope displacement. This theory identifies the deformation stages of creep slopes by the magnitude and variation of the tangent angle on the entire slope deformation curve and uses it for early warning of landslide occurrence. However, this theory has significant shortcomings: the value of the tangent angle is affected by the time unit on the horizontal axis, and its expression suffers from dimensional inconsistencies, making it difficult to quantitatively determine the slope deformation state and accurately predict landslide timing. Although some scholars have improved the tangent angle theory by transforming the dimensionality of the vertical axis, solving its dependence on the time unit, relying solely on the tangent angle to analyze slope deformation is still not intuitive enough, and the physical meaning of the tangent angle for early warning and forecasting remains unclear.

[0004] Furthermore, existing displacement-based slope and landslide early warning methods still have limitations: it is difficult to solve for the equivalent safety factor of the slope; if finite element inversion is used, the workload is large, the operation is complex, and the accuracy of stress path is low, often making it difficult to obtain ideal results. Currently, the assessment of slope stability mainly relies on field investigations and empirical classification, which has limited accuracy and also affects the success rate of early warning. On the other hand, some scholars have attempted to define the safety factor as the ratio of the current damage factor to the ultimate damage factor, trying to establish a theoretical relationship between displacement and the safety factor. However, this definition is not actually the mechanical equilibrium ratio of the sliding surface resistance force and the sliding force, and it is inconsistent with the commonly used and widely accepted concept of the safety factor in the code, making its physical meaning ambiguous. More importantly, this method implicitly assumes that the slope will only fail when the damage accumulates to the ultimate state. For engineering slopes that have been artificially cut, the slope is often steep, and its failure mode often manifests as sliding before the damage reaches the limit, which does not hold true. Therefore, this method is actually only applicable to natural slopes where deformation failure is closer to the ultimate damage mode, and it is difficult to extend it to the stability assessment and early warning of engineering slopes. In addition, this method has two significant limitations: first, it is only applicable to the stage after the slope enters the constant rate deformation stage, and cannot cover the entire life cycle of the slope; second, the safety factor directly depends on the displacement monitoring data and is extremely sensitive to data noise. Even slight disturbances may cause the safety factor to fluctuate drastically, seriously affecting the judgment of technicians. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a slope deformation early warning method. This method is based on the principles of damage mechanics, has clear physical and mechanical significance, is intuitive and easy to understand, and has strong scientific, advanced and practical value, providing a new approach for the development of slope landslide early warning and forecasting.

[0006] The objective of this invention is achieved through the following technical solution: A slope deformation early warning method includes the following steps: S1. By acquiring monitoring data on the slope type, slope ratio, stratum distribution, and slope displacement along the depth of the monitoring borehole of the existing highway slope, the location of the potential sliding surface of the slope is determined, and a damage factor is constructed based on the shear stiffness of the potential sliding surface of the slope: (1) In the formula, Let be the damage factor of the potential sliding surface of the slope at time t. For the initial deformation of the potential slip surface, Let be the displacement of the potential sliding surface at time t; S2. Obtain the displacement data of the potential sliding surface of the slope and plot the tD(t) curve according to equation (1). ; S3. The expression for the rate of change of the damage factor over time is defined as follows: (2) Use equation (2) to analyze the tD(t) curve. The curve abrupt change point is obtained to determine the initial deformation stage, constant-rate deformation stage, and accelerated deformation stage of the slope. S4. Establish a relative time coordinate system T at the starting time point of the accelerated deformation stage, and obtain the rate of change of damage factor per unit time between two points before and after multiple sampling points using formula (1). Establish relative time T and rate of change of damage factor per unit time. Regression relationships, using regression to predict trends: (3) In the formula, ; S5. Determine the expression for the predicted time of landslides on the slope; Based on equation (3), the time required for slope deformation to progress from the accelerated deformation stage to the eventual landslide is expressed as follows: (4) In the formula, The damage factor corresponds to the accelerated deformation stage of the slope; Equation (4) is an implicit equation, which is solved by exhaustive search. ; right The predicted time of landslide can be obtained by summing the time of entering the accelerated deformation stage and the time of landslide. : (5) In the formula, The time to enter the accelerated deformation stage is denoted as , and the curve abrupt change point is denoted as in step S3.

[0007] In a preferred embodiment of the present invention, the process of constructing the damage factor in step S1 is as follows: S101, Define the potential slip surface shear stress of the slope. The expression is: (6) In the formula K For the secant shear stiffness of the potential slip surface, u For the shear displacement of the potential sliding surface; S102. Define the damage factor of the potential slip surface as follows: (7) In the formula, The initial secant stiffness at the start of monitoring the potential sliding surface of the slope. The secant stiffness of the potential sliding surface of the slope at a certain moment; damage factor. The value can be between 0 and 1. When it indicates that the potential slip surface is undamaged, This indicates potential complete damage to the slip surface; S103. According to Lemaitre's assumption, the shear deformation response of the potential sliding surface after damage is the same as that of the potential sliding surface under the undamaged condition. Therefore, we have: (8) S104. Combining equations (7) and (8), the damage factor of the potential sliding surface of the slope at time t is obtained as equation (1).

[0008] Another objective of this invention is to provide a slope condition determination method based on the aforementioned early warning method.

[0009] A method for determining slope condition includes the following steps: A1. Obtain monitoring data on slope type, slope ratio, stratum distribution, and slope displacement along the depth of monitoring boreholes to determine the location of potential slip surfaces; Obtain the unit weight and initial shear strength parameters of the formation, including cohesion and internal friction angle; A2. By simplifying the Bishop method, the expression for the safety factor of the potential sliding surface in the initial state of the slope is determined as follows: (9) In the formula, Assuming a safety factor for the current potential slip surface, For the first i The weight of a single earthen strip, For the first i The angle between the tangent at the midpoint of the bottom sliding surface of the soil strip and the horizontal line. For the first i The width of each soil strip; , where is the Bishop coefficient, an intermediate variable for convenient calculation; A3. According to the Mohr-Coulomb strength criterion, the principal stress forms of the potential sliding surface shear strength of the slope are as follows: (10) In the formula, It is the internal friction angle. For cohesion, For the principal stresses of the potential slip surface, For the small principal stress of the potential slip surface; Based on Lemaitre's assumption, the relationship between the shear strength of the potential sliding surface and the damage factor is given by equation (11), which represents the effective stress of the potential sliding surface under damage conditions: (11) In the formula, The effective principal stress after damage occurs. The effective minor principal stress after damage occurs; According to the Mohr-Coulomb strength criterion, the stress relationship of the potential slip surface at this time is expressed as: (12) After simplification, the expression for the shear strength after damage to the potential slip surface can be obtained: (13) Combining the damage factor expression (1) and the curve The expressions for the principal stress shear strength of the sliding surface under different damage factors are obtained as follows: (14) The shear strength of the slip surface after damage still obeys the Mohr-Coulomb criterion. Therefore, according to the expression of equation (10), the damage factor and the cohesion term can be combined. Thus, the damage evolution state can be equivalent to the process of cohesion reduction. Therefore, the equivalent cohesion can be defined as: (15); A4. When the potential sliding surface is damaged, its shear strength degrades as the damage evolves, and the safety factor of the potential sliding surface changes. Combining equations (9) and (15), the expression for the safety factor of the slope's potential sliding surface at different monitoring times t is obtained as follows: (16); A5. Based on the safety factor of the potential sliding surface of the slope in the initial state obtained in step A2 and the safety factor of the potential sliding surface of the slope at time t obtained in step A4, evaluate the stability of the slope in the current state.

[0010] Preferably, if multiple inclinometers are installed on the slope, the initial displacement at different locations is... Displacement in the plastic state at different times In cases where there are inconsistencies, the average value of data from different inclinometers on the same cross section is used for the potential slip surface.

[0011] Compared with the prior art, the present invention has the following advantages: This invention overcomes the shortcomings of traditional tangent angle theory, which is affected by time units and has inconsistent dimensions. The provided early warning indicators have clear physical meanings and unique results, enabling more intuitive and accurate judgment of slope deformation stages and early warning of landslide timing. This invention simplifies the calculation of the equivalent safety factor of slopes without requiring complex finite element inversion, significantly reducing workload and operational difficulty. Furthermore, the stress path is more realistic, resulting in more reliable calculation results. The safety factor defined in this invention strictly adheres to the mechanical equilibrium essence of the ratio of anti-slip force to sliding force, has a clear physical meaning, and is completely consistent with the commonly used safety factor concept in standards, facilitating understanding by technical personnel. Engineering Applications: This invention fully considers the characteristics of engineering slopes, such as steep slopes after artificial trimming, and the potential for landslide failure before damage accumulates to its limit. This makes early warning assessment truly applicable to engineering slopes, filling the gap that existing methods are only applicable to natural slopes. The method of this invention can cover the entire life cycle of a slope, from initial deformation, isotropic deformation to accelerated deformation, without waiting for the slope to enter the isotropic deformation stage, realizing dynamic assessment and landslide early warning throughout the entire process. This invention has strong robustness to noise in displacement monitoring data, effectively suppressing drastic fluctuations in the safety factor caused by data disturbances, ensuring stable and reliable assessment results, and significantly reducing the risk of misjudgment. Attached Figure Description

[0012] Figure 1 This is a curve showing the entire process of slope deformation.

[0013] Figure 2 This is a cumulative displacement curve showing the entire deformation process of a landslide on the back mountain of a certain area.

[0014] Figure 3 This is a diagram showing the changes in damage factors throughout the deformation process of a landslide on a hillside in a certain area (the red dots in the diagram represent the starting points of the accelerated deformation stage of the slope).

[0015] Figure 4 This is a deformation rate curve of a landslide in a certain area, showing the entire deformation process (red dots in the figure represent points where the deformation rate increases abruptly).

[0016] Figure 5 This is a regression trend curve of the rate of change of damage factors in a landslide on the back mountain of a certain area during the accelerated deformation stage.

[0017] Figure 6 This is a displacement-time curve for automated monitoring of deep inclinometer data of a slope in a certain area.

[0018] Figure 7 Based on Figure 6 The cumulative displacement-time curves obtained by synthesizing the displacements in the x and y directions (red dots in the figure are inflection points).

[0019] Figure 8 The graph shows the deformation rate-time and damage factor-time curves (green dots in the graph represent inflection points).

[0020] Figure 9 This is a diagram showing the safety factor analysis results of a slope in a certain area when the damage factor D=0.

[0021] Figure 10 The figure shows the safety factor analysis results of a slope in a certain area when the damage factor D=0.58.

[0022] Figure 11 This is a flowchart of the slope deformation early warning method and slope state determination method of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0024] Example 1 See Figure 11 This embodiment discloses a slope deformation early warning method, including the following steps: S1. By acquiring the geometric elements of the existing highway slope and the monitoring data from the inclinometer, the location of the potential slip surface of the slope is determined. Geometric elements include slope ratios at various levels, slope height, topographic morphology at the slope crest, and the distribution of soil strata within the slope. The monitoring data from the inclinometer includes the distribution of displacement along the depth of the monitoring borehole.

[0025] A damage factor was constructed based on the shear stiffness of the potential sliding surface of the slope; the construction process of the damage factor is as follows: S101, Define the potential slip surface shear stress of the slope. The expression is: (6) In the formula K For the secant shear stiffness of the potential slip surface, u This represents the shear displacement of the potential sliding surface.

[0026] The full-process curve of slope deformation can be found in [reference needed]. Figure 1 When the sliding surface undergoes plastic deformation, reducing the interfacial strength to a certain level, the upper sliding body will slide along the sliding surface, causing slope failure. However, due to the installation time of the monitoring equipment, data from the initial deformation stage is easily lost.

[0027] S102. When a potential sliding surface undergoes plastic deformation, the shear stiffness of the interface decreases over time, and the interface strength decreases with increasing plastic deformation, until the interface strength decreases to the critical sliding strength due to the failure of the interface micro-elements, ultimately leading to a landslide geological hazard. Based on this analysis, the damage factor of the potential sliding surface can be defined as: (7) In the formula, The initial secant stiffness at the start of monitoring the potential sliding surface of the slope. The secant stiffness of the potential sliding surface of the slope at a certain moment; damage factor. The value can be between 0 and 1. When it indicates that the potential slip surface is undamaged, This indicates that the potential slip surface is completely damaged, which can be understood as "material" failure.

[0028] S103, According to Lemaitre's assumption, we know that Therefore, by extension, it can be seen that the shear deformation response of the potential sliding surface after damage is the same as that of the potential sliding surface under the undamaged condition. Therefore, we have: (8) In the formula, u For the shear displacement of the potential sliding surface, This represents the shear stress on the potential slip surface.

[0029] S104. Creep surfaces typically exhibit good ductility, thus their shear stress and stress remain essentially constant during deformation. Furthermore, as shown in equations (7) and (8), the damage factor of the potential slip surface at time t can be represented by equation (1), i.e.: (1) In the formula, Let be the damage factor of the potential sliding surface of the slope at time t. For the initial deformation of the potential slip surface, Let be the displacement of the potential sliding surface at time t.

[0030] S2. Obtain the displacement data of the potential sliding surface of the slope and plot the tD(t) curve according to equation (1). .

[0031] A tD(t) curve can be plotted using a certain amount of monitoring data. Since the damage factor is a dimensionless parameter in the form of a ratio, its variation range is relatively small, which can play a certain role in filtering and reducing noise in monitoring data, and its entire process curve is relatively easy to keep smooth and flat.

[0032] S3. As the creep damage intensifies, the interface strength decreases significantly compared to the initial state, and most of the micro-elements on the interface bearing surface are destroyed. The slope exhibits an abrupt change in deformation rate, reaching the accelerated deformation stage. To accurately capture the abrupt change point in the deformation stage, the expression for the damage factor's time-varying rate is defined as (damage tangent angle): (2) Use equation (2) to analyze the tD(t) curve. By observing and obtaining the abrupt change points of the curve, the initial deformation stage, the constant-rate deformation stage, and the accelerated deformation stage of the slope deformation can be determined.

[0033] S4. During the accelerated deformation stage of the slope, the deformation rate increases with time, which means that the time change rate of the damage factor also exhibits time-varying characteristics. At this time, the damage factor of multiple sampling points can be obtained by combining high-frequency multiple sampling over a period of time with formula (1).

[0034] Furthermore, a relative time coordinate system T is established at the starting time point of the accelerated deformation stage, and the rate of change of damage factor per unit time between two points before and after multiple sampling points is obtained by combining formula (1). Establish relative time T and rate of change of damage factor per unit time. Regression relationships, using regression to predict trends: (3) In the formula, ; S5. Determine the expression for the predicted time of landslide occurrence on the slope.

[0035] Specifically, based on equation (3), the time required for slope deformation to progress from the accelerated deformation stage to the final landslide (complete damage state) is expressed as follows: (4) In the formula, The damage factor corresponds to the accelerated deformation stage of the slope; Equation (4) is an implicit equation, which is solved by exhaustive search. ; right The predicted time of landslide can be obtained by summing the time of entering the accelerated deformation stage and the time of entering the accelerated deformation stage. : (5) In the formula, The time to enter the accelerated deformation stage is denoted as , and the curve abrupt change point is denoted as in step S3.

[0036] This embodiment can provide early warning of landslide occurrence time, and offers a new approach to depicting the entire process of slope deformation curves by combining damage mechanics theory. The early warning expression has a clear physical and mechanical meaning, is intuitive and easy to understand, and can calculate the final time of the slope's imminent landslide state by combining regression analysis and smoothing techniques. It is simple, practical, and easy for engineering technicians to operate and use. Moreover, the early warning method in this embodiment has built-in monitoring data filtering and noise reduction functions, and monitoring data with small oscillations can be directly used for analysis without the need for noise reduction analysis as in traditional methods.

[0037] The following analysis and verification will be based on a case study of a landslide in a certain area.

[0038] The deformation curve of the entire monitoring process of a landslide on the back mountain of a certain area can be found in [reference]. Figure 2 Through observation Figure 2 The deformation curve shows that the landslide mainly consists of constant-rate deformation and accelerated deformation. Due to reasons such as the installation of monitoring equipment, data from the initial deformation stage was not monitored. Substituting the monitoring data into equation (1) yields the damage factor value for each monitoring point, such as... Figure 3 As shown, the tD(t) curve .

[0039] Combination Figure 3 It can be seen that when a landslide occurs, the damage factor approaches 1 (complete damage) infinitely. This analysis result indirectly confirms the assumption of complete damage in this embodiment. Simultaneously, through observation... Figure 3 It can be assumed that the slope deformation changed from the isotropic deformation stage to the accelerated deformation stage on the 5th day after the start of monitoring.

[0040] Furthermore, such as Figure 4 As shown, the tv (slope deformation rate) curve and the tD(t) curve are plotted. A comparison was conducted. The comparative analysis revealed a sudden increase in the slope deformation rate starting on day 5, indicating the entry into an accelerated deformation stage. This conclusion aligns with the findings of the method proposed in this invention, verifying the rationality of the proposed method and demonstrating that this invention can accurately identify the stages of slope deformation. Furthermore, it can be found that… Figure 4 The curves shown have large fluctuations and a lot of noise, far inferior to... Figure 3 The tD(t) curve shown The curve is smooth and flat, which indicates that the early warning method proposed in this invention has a certain noise reduction and filtering effect.

[0041] Furthermore, the first five sampling points of the accelerated deformation stage of the slope were selected, and a trend prediction regression equation was constructed. Through regression analysis, equation (17) and Figure 5 : (17) Substituting the data from day 5 and equation (17) into equation (5), the time when the slope fails (landslide) occurs can be calculated as day 5 plus day 30 after the start of monitoring, i.e., day 35. This prediction result is close to the actual monitoring data, indicating that the result has a certain degree of rationality, but it is slightly less than the actual number of days. This is because the analysis ignores the stress self-adjustment ability of the sliding surface soil and rock mass in the later stage and overestimates the rate of change of damage time during the acceleration period. However, the result of this analysis method has a certain safety margin and has engineering guiding significance.

[0042] Example 2 See Figure 11This embodiment discloses a method for determining the state of a slope, including the following steps: A1. Obtain monitoring data on slope type, slope ratio, stratum distribution, and slope displacement along the depth of monitoring boreholes to determine the location of potential slip surfaces; Obtain the shear strength parameters of the formation in its unit weight and initial state, including cohesion and internal friction angle.

[0043] A2. By simplifying the Bishop method, the expression for the safety factor of the potential sliding surface in the initial state of the slope is determined as follows: (9) In the formula, Assuming a safety factor for the current potential slip surface, For the first i The weight of a single earthen strip, For the first i The angle between the tangent at the midpoint of the bottom sliding surface of the soil strip and the horizontal line. For the first i The width of each soil strip; The Bishop coefficient is an intermediate variable used for convenient calculation. In addition to the simplified Bishop method, this embodiment can also use the limit equilibrium method and the limit equilibrium slice method to obtain the safety factor expression.

[0044] A3. During slip surface creep, as the plastic creep displacement increases, the shear strength of the slip zone interface decreases with damage evolution. The shear strength of the soil and rock mass conforms to the Mohr-Coulomb strength criterion; therefore, the principal stress forms of the potential slip surface shear strength of the slope are as follows: (10) In the formula, It is the internal friction angle. For cohesion, For the principal stresses of the potential slip surface, This represents the small principal stress of the potential slip surface.

[0045] Plastic displacement occurs during creep and deformation, and damage occurs on the sliding surface. Based on the Lemaitre assumption, the relationship between the shear strength of the potential sliding surface and the damage factor is given by equation (11), which is the effective stress of the potential sliding surface under the damaged state: (11) In the formula, The effective principal stress after damage occurs. This represents the effective minor principal stress after damage occurs.

[0046] The actual stress state under equation (11) also conforms to the Mohr-Coulomb strength criterion, and the stress relationship expression of the potential slip surface is as follows: (12) After simplification, the expression for the shear strength after damage to the potential slip surface can be obtained: (13) The shear displacement of the slip surface at different times can be obtained using deep-hole inclinometer equipment. and initial deformation The damage factor expression (1) and curve in combined embodiment 1 The expressions for the principal stress shear strength of the sliding surface under different damage factors are obtained as follows: (14) The shear strength of the slip surface after damage still obeys the Mohr-Coulomb criterion. Therefore, according to the expression of equation (10), the damage factor in equation (14) can be combined with the cohesion term. Thus, the damage evolution state can be equivalent to a process of decreasing cohesion. Therefore, the equivalent cohesion can be defined as: (15); A4. After obtaining the initial displacement and cohesion, the degree and magnitude of cohesion degradation under damage conditions can be calculated after a certain degree of plastic deformation occurs on the sliding surface at the deep-hole monitoring point. Combined with the cohesion, internal friction angle, and unit weight parameters of the strata determined by the original engineering survey of the slope, the safety factor of the sliding surface and slope body under different degrees of deformation can be determined, thereby quantitatively assessing the current state of the slope body.

[0047] Therefore, when the potential sliding surface is damaged, its shear strength degrades as the damage evolves, and the safety factor of the potential sliding surface changes. Combining equations (9) and (15), the expression for the safety factor of the slope's potential sliding surface at different monitoring times t is obtained as follows: (16); A5. Based on the safety factor of the potential sliding surface of the slope in the initial state obtained in step A2 and the safety factor of the potential sliding surface of the slope at time t obtained in step A4, evaluate the stability of the slope in the current state.

[0048] Furthermore, if multiple inclinometers are installed on the slope, the initial displacement at different locations can be measured. Displacement in the plastic state at different times In cases where there are different situations, the average value of the data from different inclinometers on the same cross section is used for the potential sliding surface. If there is only one potential sliding surface on the slope, the current state assessment of the potential sliding surface can be completed simply by performing an assessment according to equation (16).

[0049] The following analysis and verification will be based on an example of deep inclinometer data from a slope in a certain area.

[0050] like Figure 6The image shows inclinometer data for a deep slope at a certain location. For example, a sudden change in displacement at a position 9m in the x-direction indicates a potential slip surface. The cumulative displacement-time curve obtained by synthesizing the displacements in the x and y directions is shown below. Figure 7 As shown. By Figure 7 As can be seen, the curve is currently in the "constant rate deformation" stage, and data from the initial deformation stage has been monitored. The deformation rate-time (tangent angle) and damage factor-time curves are plotted as follows: Figure 8 Over the course of a year, the slope deformation increased by a total of 1.2 mm, with an average daily deformation rate of 0.0032 mm / d. During intermittent rainfall and minor flood seasons, the deformation rate reached 0.02 mm / d. None of these rates met the early warning standards for highway landslides. However, relying solely on the deformation rate index is insufficient for comprehensive assessment (see...). Figure 7 and Figure 8 The slope is already in the constant-velocity deformation stage of the blue alert level. The embankment slope remains in a basically stable state. In the later stage, as the deformation increases, macroscopic tension cracks and shear exits may appear. Pre-reinforcement measures can be set up according to the actual situation.

[0051] At this work site, the conclusions drawn from comparing the existing tangent angle method with the method of this invention are consistent with the conclusions of the previous case. This invention can play a certain role in data noise reduction and uses absolute damage factors to reflect the state of slope and landslide deformation. The inflection point of its damage evolution curve can reflect the changes in the slope deformation stage. By accumulating the absolute value of damage, the time of slope sliding can be predicted, guiding the arrangement of engineering nodes.

[0052] To further provide reference and guidance for engineering management, slope stability calculations are also performed for this example. Based on relevant data, and combining the simplified Bishop method, slope stability calculations are performed for D=0 and D=0.58, respectively. (See attached figures.) Figure 9 and Figure 10 The unit weight of the slope rock strata is 18.5 kN / m3, the initial cohesion is 20 kPa, and the internal friction angle is 22°.

[0053] Depend on Figure 10 It can be seen that the current state of the slope is D=0.58, with a safety factor of 1.146, indicating that it is in a basically stable state overall. In recent years, the slope surface has experienced erosion and landslides, resulting in poor local stability. The shoulder concrete shows cracking and deformation, longitudinal and transverse cracks appear on the road surface, and the inner wall of the ditch shows tilting deformation. Based on these observations, it can be determined that the slope is not completely stable, but rather in a basically stable state. The displacement data from the deep-hole inclinometer over 100 days also indicates that the slope underwent some deformation within that period. The determination method in this embodiment converts the displacement changes before and after 100 days into a safety factor calculation and displays its... Figure 10The results show the deterioration trend of slope stability over the past 100 days. Before monitoring, the safety factor of the slope slip surface was 1.42, indicating a stable state (a stable state is >1.20). After more than 100 days of monitoring, the slope safety factor was 1.164, a decrease of 0.256 compared to before monitoring, indicating that it has moved from a stable state to the range of a basically stable state (generally considered to be 1.10~1.20 in engineering). This calculation result is in good agreement with the on-site slope deformation, which well demonstrates the effectiveness of the equivalent assessment method proposed in this embodiment.

[0054] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for early warning of slope deformation, characterized in that, Includes the following steps: S1. By acquiring monitoring data on the slope type, slope ratio, stratum distribution, and slope displacement along the depth of the monitoring borehole, the location of the potential sliding surface of the slope is determined, and a damage factor is constructed based on the shear stiffness of the potential sliding surface. （1） In the formula, Let be the damage factor of the potential sliding surface of the slope at time t. For the initial deformation of the potential slip surface, Let be the displacement of the potential sliding surface at time t; S2. Obtain the displacement data of the potential sliding surface of the slope and plot the tD(t) curve according to equation (1). ; S3. The expression for the rate of change of the damage factor over time is defined as follows: （2） Use equation (2) to analyze the tD(t) curve. The curve abrupt change point is obtained to determine the initial deformation stage, constant-rate deformation stage, and accelerated deformation stage of the slope. S4. Establish a relative time coordinate system T at the starting time point of the accelerated deformation stage, and obtain the rate of change of damage factor per unit time between two points before and after multiple sampling points using formula (1). Establish relative time T and rate of change of damage factor per unit time. Regression relationships, using regression to predict trends: （3） In the formula, ; S5. Determine the expression for the predicted time of landslides on the slope; Based on equation (3), the time required for slope deformation to progress from the accelerated deformation stage to the eventual landslide is expressed as follows: （4） In the formula, The damage factor corresponds to the accelerated deformation stage of the slope; Equation (4) is an implicit equation, which is solved by exhaustive search. ; right The predicted time of landslide can be obtained by summing the time of entering the accelerated deformation stage and the time of landslide. : （5） In the formula, The time to enter the accelerated deformation stage is denoted as , and the curve abrupt change point is denoted as in step S3.

2. The slope deformation early warning method according to claim 1, characterized in that, In step S1, the process of constructing the damage factor is as follows: S101, Define the potential slip surface shear stress of the slope. The expression is: （6） In the formula K For the secant shear stiffness of the potential slip surface, u For the potential shear displacement of the sliding surface; S102. Define the damage factor of the potential slip surface as follows: （7） In the formula, The initial secant stiffness at the start of monitoring the potential sliding surface of the slope. The secant stiffness of the potential sliding surface of the slope at a certain moment; damage factor. The value can be between 0 and 1. When it indicates that the potential slip surface is undamaged, This indicates potential complete damage to the slip surface; S103. According to Lemaitre's assumption, the shear deformation response of the potential sliding surface after damage is the same as that of the potential sliding surface under the undamaged condition. Therefore, we have: （8） S104. Combining equations (7) and (8), the damage factor of the potential sliding surface of the slope at time t is obtained as equation (1).

3. A method for determining slope condition, characterized in that, Includes the following steps: A1. Obtain monitoring data on slope type, slope ratio, stratum distribution, and slope displacement along the depth of monitoring boreholes to determine the location of potential slip surfaces; Obtain the unit weight and initial shear strength parameters of the formation, including cohesion and internal friction angle; A2. By simplifying the Bishop method, the expression for the safety factor of the potential sliding surface in the initial state of the slope is determined as follows: （9） In the formula, Assuming a safety factor for the current potential slip surface, For the first i The weight of a single earthen strip, For the first i The angle between the tangent at the midpoint of the bottom sliding surface of the soil strip and the horizontal line. For the first i The width of each soil strip; , where is the Bishop coefficient, an intermediate variable for ease of calculation; A3. According to the Mohr-Coulomb strength criterion, the principal stress forms of the potential sliding surface shear strength of the slope are as follows: （10） In the formula, It is the internal friction angle. For cohesion, For the principal stresses of the potential slip surface, For the small principal stress of the potential slip surface; Based on Lemaitre's assumption, the relationship between the shear strength of the potential sliding surface and the damage factor is given by equation (11), which represents the effective stress of the potential sliding surface under damage conditions: （11） In the formula, The effective principal stress after damage occurs. The effective minor principal stress after damage occurs; According to the Mohr-Coulomb strength criterion, the stress relationship of the potential slip surface at this time is expressed as: （12） After simplification, the expression for the shear strength after damage to the potential slip surface can be obtained: （13） The damage factor expression (1) and curve described in claim 1 The expressions for the principal stress shear strength of the sliding surface under different damage factors are obtained as follows: （14） Based on equation (10), combining the damage factor and the cohesion term, we obtain that the damage evolution state can be equivalent to the process of decreasing cohesion. Therefore, the equivalent cohesion is defined as: （15）； A4. When the potential sliding surface is damaged, its shear strength degrades as the damage evolves, and the safety factor of the potential sliding surface changes. Combining equations (9) and (15), the expression for the safety factor of the slope's potential sliding surface at different monitoring times t is obtained as follows: （16） Let be the safety factor of the potential sliding surface of the slope at time t; A5. Based on the safety factor of the potential sliding surface of the slope in the initial state obtained in step A2 and the safety factor of the potential sliding surface of the slope at time t obtained in step A4, evaluate the stability of the slope in the current state.

4. The slope condition determination method according to claim 3, characterized in that, If multiple monitoring instruments are installed on the slope, the initial displacement at different locations... Displacement in the plastic state at different times In cases where there are different scenarios, the average value of different monitoring data from the same cross section is used to calculate the safety factor for the potential slip surface.

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