Anchoring slope risk assessment method considering combined action of time-varying deterioration and dynamic load of anchor rod

Abstract

The invention belongs to the technical field of geotechnical engineering and geological disaster prevention and control, and discloses an anchoring slope risk assessment method considering the combined action of time-varying deterioration and dynamic load of an anchor rod. Constructing an anchoring slope stability coefficient formula by combining with a time-varying attenuation rule of free section rod body yield resistance caused by anchor rod time-varying deterioration and bonding of an anchor rod-mortar interface and a mortar-rock mass interface and considering a dynamic load effect at the same time; based on a Monte Carlo probability framework, introducing a reliability index and a failure probability, and constructing a coupling reliability evaluation model; a rock-soil body, an anchoring system, an environment and dynamic load parameters are defined as random variable sampling calculation, a quantitative coupling effect and a failure mode control conversion mechanism; carrying out risk dynamic early warning based on a sensitivity analysis result and proposing a maintenance suggestion; according to the method, the problem that the combined action of anchor rod time-varying degradation and dynamic load cannot be comprehensively considered in anchoring slope risk assessment in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering and geological disaster prevention technology, and in particular to a method for risk assessment of anchored slopes that considers the combined effects of time-varying deterioration of anchor bolts and dynamic loads. Background Technology

[0002] Currently, in the field of geotechnical engineering, the stability assessment of anchored slopes mostly adopts the fixed safety factor method or static reliability analysis, mainly including the following methods: (1) Deterministic analysis method: This is the most commonly used analysis method in engineering. Its core idea is to evaluate the stability of the slope by calculating the safety factor through the safety factor method or the limit equilibrium method. This method is usually based on the static load assumption and regards material parameters, loads, etc. as fixed values, without considering their inherent randomness and time-varying nature. (2) Static reliability assessment method: In order to consider the uncertainty of soil and rock parameters, some studies have introduced reliability theory and used methods such as the first second moment method and Monte Carlo simulation to calculate the failure probability or reliability index of the slope. However, these methods are still based on the assumption of "time invariance", that is, it is believed that the resistance and probability distribution of the structure do not change throughout the entire life cycle of the structure, and can only perform a static snapshot evaluation of the reliability of the slope at a specific moment. (3) Single factor analysis: When analyzing the influence of the environment on the performance of anchor bolts, existing studies often isolate the time-varying deterioration of anchor bolts and dynamic loads. On the other hand, many studies focus on the dynamic response of slopes under dynamic loads, analyzing the impact of dynamic load propagation on slope stress distribution through numerical simulations. However, these studies assume that the mechanical parameters of the anchor bolts remain unchanged and ignore the decrease in the seismic resistance of the anchor bolts caused by corrosion. Neither type of research considers the synergistic effect of "time-varying degradation - dynamic load," and thus fails to reveal the true failure mechanism of anchored slopes under complex working conditions.

[0003] These methods have limitations in dealing with time-varying deterioration of anchor bolts and the randomness of dynamic loads. Their shortcomings and deficiencies are as follows: (1) Existing technologies do not fully consider the time-varying deterioration of anchor bolts, and the assessment results deviate from reality: Traditional methods do not include the time-varying deterioration of anchor bolts due to corrosion, which reduces the cross-sectional area and tensile strength during service, and cannot accurately predict the long-term stability of the slope; (2) The expansion effect of corrosion products will destroy the bond between the anchor bolt and the grouting body, further weakening the anchoring force. Since such performance degradation is not included in the model, existing methods will overestimate the actual resistance of the slope in the later stages of service, making the assessment results too optimistic; (3) Existing technologies treat corrosion and dynamic load as independent effects, without analyzing their synergistic effect, and cannot reveal the slope instability mechanism: Corrosion damage will reduce the ductility and fatigue life of anchor bolts, making them more prone to brittle fracture under dynamic loads, and fails to integrate the two types of randomness, environmental and load. Even if the reliability method is used, only one type of randomness is considered, and there is a lack of a comprehensive probability analysis model that integrates both. (4) Existing technologies are difficult to quantitatively assess the long-term benefits of anchor bolt design parameters, and cannot scientifically determine the best time for maintenance and reinforcement. In engineering practice, decision-making often relies on experience judgment or "passive response". Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a risk assessment method for anchored slopes that considers the combined effects of time-varying deterioration of anchor bolts and dynamic loads. This method solves the problem that existing technologies fail to comprehensively consider the combined effects of time-varying deterioration of anchor bolts and dynamic loads in the risk assessment of anchored slopes. It improves the accuracy of the assessment by adopting a reliability evaluation method and provides quantitative basis for design optimization and maintenance decisions through sensitivity analysis.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration of anchor bolts and dynamic loads, which includes the following steps: S1. Data Acquisition and Processing: Conduct engineering geological and environmental surveys to obtain slope soil and rock parameters, anchoring system design parameters, and environmental corrosivity data. Clean, standardize, and fit the probability distribution of the multi-source data. S2. Establishment of Time-Varying Deterioration Model for Anchoring System: Based on environmental parameters, a prediction model for the deterioration rate of anchor bolts is established, and then the bonding resistance of the mortar-rock interface is constructed. Time-varying function, time-varying function of resistance at the anchor-mortar interface and the time-varying function of the yield resistance of the free section of the anchor bolt reinforcement The overall time-varying resistance of the system is taken as the minimum value among the three: This characterizes the nature of the anchoring system's degradation over service time and the possible transformation of its failure mode control mechanisms. S3. Construction of the limit state equation for the combined action of time-varying anchor bolt deterioration and dynamic load: The time-varying resistance... By combining the load effects caused by dynamic loads, a limit state equation considering coupling effects is established; S4. Time-varying reliability calculation and analysis: Solve the limit state equation using the reliability method to calculate the failure probability of the slope at different service ages. P f (t), and plot the time-varying curve of failure probability to analyze its evolution law; S5. Sensitivity Analysis and Parameter Optimization: Analyze which parameters affect the slope failure probability. P f (t) has the greatest impact, and with the goal of "reducing the probability of slope failure throughout its entire life cycle", the design parameters are adjusted in a targeted manner in combination with key parameters to ensure safety while taking into account economy.

[0006] Preferably, step S1 specifically includes the following steps: S1.1: Geotechnical Parameter Survey: Using a combination of drilling, geophysical exploration, and in-situ testing, the lithology, geological structure, rock mass structural features, and potential slip surface locations of the slope were determined. Key physical and mechanical parameters of the geotechnical mass, such as unit weight, cohesion, internal friction angle, and elastic modulus, were obtained through in-situ field tests and laboratory geotechnical tests, and their spatial variability was assessed. S1.2: Current status survey of anchoring system: Review the original design drawings to verify the arrangement spacing, length, inclination angle, length of free section and anchoring section, material and specifications of the rod, and design parameters of grout strength grade of the prestressed anchors; use partial excavation sampling or non-destructive testing technology to assess the current status of the anchors in service, including the prestress loss and the integrity of the protective layer; S1.3: Environmental erosivity survey: Deploy miniature weather stations and groundwater monitoring points in the slope area and conduct continuous monitoring for at least one full year; take samples at anchor bolt holes and different depths to test the pH and Cl values ​​of the groundwater. - Ion concentration, SO4² - Chemical indicators such as ion concentration and resistivity were measured. The pH of groundwater was tested using a pH meter to determine the environmental corrosion level. Grout core samples were collected, and their density, permeability, and chloride ion diffusion coefficient were measured in the laboratory to evaluate their ability to protect steel bars. S1.4: Data cleaning and standardization: Clean all collected data and remove outliers and invalid records; S1.5: Dimensional unification: Convert data from different sources and with different dimensions into a unified format and standard, and use the "range standardization method" to eliminate the influence of dimensions; S1.6: Probability distribution fitting: Fitting the probability distribution of random variables such as soil and rock parameters to determine their statistical characteristics; S1.7: 3D geological modeling: Using GIS or professional geological modeling software, integrate geological survey data to construct a 3D geological model that can accurately reflect the distribution of slope strata, structural planes, and potential slip surfaces, providing a geometric basis for subsequent numerical analysis.

[0007] Preferably, step S2 specifically includes the following steps: S2.1: Constructing a predictive model for uniform corrosion rate of anchor bolts: Based on indoor accelerated corrosion test data and environmental survey data, the annual corrosion rate of the anchor bolt body is calculated using empirical or theoretical models. i cor Assuming uniform corrosion of the anchor cable, the expression for calculating its corrosion rate is as follows: ; kcr The anchor cable position correction factor is set to 1.0. kce This is an environmental condition correction factor, taken as 4.0; T Ambient temperature; RH The relative humidity of the environment; DC The thickness of the anchor cable bonding layer; σc The compressive strength of the grouting body; S2.2: This further affects the corrosion rate. i cor Integral prediction service t Corrosion of anchor rod reinforcement after service years: ; In the formula, This represents the time period. τ The instantaneous nominal corrosion rate at this specific moment; S2.3: Constructing the time-varying function of mortar-rock interface bond resistance: ; In the formula, This represents the average initial shear strength of the grouting mortar and the surrounding soil layer. D The diameter of the anchor bolt borehole; L m The effective anchorage length at the mortar-rock interface; S2.4: Constructing the time-varying resistance function of the anchor bolt-mortar interface: ; In the formula, This represents the initial shear strength between the grout and the anchor bolt. d b The diameter of the anchor bolt borehole; L n This refers to the effective anchorage length at the anchor bolt-mortar interface; R ( t) represents the time-varying attenuation coefficient of the bond strength between the anchor bolt and mortar interface under corrosion. Its time-varying decay coefficient function expression R ( t )for: ; In the formula, X p ( t ) for the first time in service of the anchor bolt t The annual mass corrosion ratio is defined as the percentage of mass lost due to corrosion to the original mass. S2.5: Constructing the time-varying function of the yield resistance of the reinforcement in the free section of the anchor bolt: ; In the formula: d The diameter of the anchor rod. f k0 The initial yield strength of the anchor rod reinforcement before corrosion. η s ( t )for t Corrosion rate of anchor bolt cross section at any given time. α st ( t )for t The time-varying reduction factor of the yield strength of anchor reinforcement under constant corrosion.

[0008] Preferably, step S3 specifically includes the following steps: S3.1. Establish the limit state equation of the anchored slope under time-varying deterioration based on the "time-varying resistance-dynamic load effect": ; S3.2 Establish the limit state equation for the anchored slope under dynamic load: According to the Mohr-Coulomb failure criterion, horizontal stripe unit i The shear strength of the sliding surface can be expressed as: ; In the formula, For cohesion, It is the internal friction angle. This refers to the normal stress; for the slope to achieve long-term stability, a certain safety reserve is required, namely the shear strength on the slope slip surface. It only partially functions, and is related to the tangential force of the slip surface. Achieving balance; Assuming the dynamic safety factor of the slope is Then we have: ; In the formula, For the first i The length of the bottom arc of each strip; Normal force; According to the force equilibrium condition of the horizontal block, the expression for the normal force is: ; In the formula, α i The angle of inclination of the slip surface. T' mi This represents the tensile force component of the anchor bolt. E i and X i These are the inter-strip normal force and shear force, respectively. For the first i The weight of each strip; This represents the difference in normal inter-strip force between adjacent strips; According to the principle of force equilibrium, the shear forces interacting between the blocks cancel each other out as a whole, and the total resultant force is zero, as expressed below: ; In the formula, Q hi This refers to the horizontal inertial force during an earthquake. The angle between the anchor bolt axis and the tangent to the bottom surface of the block; The formula for calculating the safety factor of anchored slopes under seismic loading is as follows: ; Considering the horizontal inertial force caused by the earthquake and the elevation amplification effect, a quasi-static method is used for calculation. ; Acceleration amplification factor Defined in sections according to the "Code for Seismic Design of Hydraulic Structures"; When H≤40m, the dynamic amplification factor follows a trapezoidal distribution, with the largest dynamic amplification factor at the top of the slope. The amplification factor at the bottom of the slope is taken as 1, and the amplification factor at the top of the slope is 2~3. ; When H≥40m: ; In the formula, H This represents the total height of the slope; h i The height from the center of the strip to the bottom of the slope. S a This represents the peak ground acceleration due to horizontal seismic action. S3.3 Establish the limit state equation for the anchored slope under the combined action of time-varying deterioration and dynamic load of the anchor bolt: ; As can be seen from the above equation, the limit state equation of the anchored slope under the combined action of time-varying deterioration of the anchor bolt and dynamic load is a function of service time, horizontal acceleration of dynamic load, and soil parameters.

[0009] Preferably, step 4 specifically includes the following process: S4.1: Calculate the slope reliability index using the verification point method. β and failure probability P f Write genetic algorithm code to determine the limit state equation. Z The parameters in the text are random variables; S4.2: By executing the time-varying reliability calculation process, the failure probability of the anchored slope at different service time points is obtained, and its evolution law is analyzed in depth to reveal the long-term performance degradation mechanism of the slope under the time-varying deterioration-dynamic load coupling effect.

[0010] Preferably, the specific implementation steps of S4.1 are as follows: (1) Clarify the random uncertainty of soil and rock parameters, ground motion parameters, anchor corrosion environment parameters and material resistance parameters, ensure the scientificity and accuracy of probability assessment results, and clarify the distribution type and statistical parameters of each variable; (2) The limit state function Z ( t Convert to standard normal space; (3) Solve for the verification points x* ,make Z ( x* The point whose value is 0 and which is closest to the origin; (4) Calculate the reliability index β and according to β Calculate the probability of failure P f =Φ(- β ); (5) Set service life calculation nodes. For each node: 1) Substitute the anchor corrosion amount Δd(t) at that moment to calculate the time-varying anchoring force T( t 2) Generate peak ground acceleration (PGA) S a 3) Calculate the random sample for each group using the checkpoint method. S a corresponding β and P f The average value is taken as the failure probability for that service life.

[0011] Preferably, the specific steps of S4.2 are as follows: (1) Nonlinear accelerated growth characteristics; (2) Determine the failure mode control mechanism conversion analysis method.

[0012] Preferably, the nonlinear accelerated growth characteristics include: 1) setting service life calculation nodes, and for each node, combining the time-varying deterioration parameters of the anchor bolts and the dynamic load parameters, using a reliability calculation method to obtain the slope failure probability of each node. P f (t); 2) Based on each node P f (t) Data, with "service age" as the horizontal axis and "failure probability" as the vertical axis, plot the "service age - failure probability" curve; 3) Observe the characteristics of the curve slope change: distinguish the curve shape of the early service period and the middle and late service period that lead to a significant decline in mechanical performance and the deterioration process caused by dynamic load, identify the characteristics of the curve transitioning from "slow growth" to "steep growth", and clarify the stage division basis of the nonlinear accelerated growth of failure probability.

[0013] Preferably, the failure mode control mechanism conversion analysis method includes: 1) Dominant Failure Mode Identification: Identify the potential dominant failure modes of the anchoring system, including grout-rock interface bond failure, rod-grout interface bond failure, and free section rod tensile strength failure; calculate the anchoring resistance corresponding to different failure modes at each service age node, and determine the dominant failure mode controlling the overall resistance of the anchoring system at each node; 2) Failure Mode Conversion and P f ( t Correlation analysis of curves: plotting P f ( t The curve is analyzed and the acceleration inflection point is identified; the dominant failure mode of the anchoring system is recorded from the grout-rock interface. / Bond failure at the rod-grout interface "Transformed into "Tensile strength failure of free segment bar" "The critical time point; will P f ( t The acceleration inflection point of the curve is compared with the critical time point of the dominant failure mode transition to analyze the temporal correlation between the two and verify the impact of failure mode transition on the critical time point of the dominant failure mode transition. P f ( t 3) Compare the magnitude of anchoring resistance corresponding to each failure mode and determine the dominant failure mode controlling the overall resistance of the anchoring system at each age node.

[0014] Preferably, step S5 specifically includes: S5.1 Sensitivity Analysis: Using the first-order second-moment method or Monte Carlo simulation, the sensitivity coefficients of each random variable are calculated to identify the key parameters that have the greatest impact on the failure probability; the effects of changes in environmental temperature and humidity on the anchor bolt corrosion rate and final... P f The amplification effect; S5.2 Parameter Optimization: With the goal of reducing the probability of failure throughout the entire life cycle, key design parameters are optimized based on the results of sensitivity analysis.

[0015] Beneficial effects of this invention: 1. This invention establishes a predictive model for the uniform corrosion rate of anchor rods based on actual environmental parameters, accurately quantifying the temporal influence of multiple factors on the corrosion amount of anchor rods; it constructs a limit state equation for slopes under the combined action of "time-varying deterioration of anchor rods and dynamic loads", integrating the dynamic characteristics of time-varying anchoring force and dynamic loads; this invention proposes a conversion criterion for the interface failure mechanism of the anchoring system, revealing the nonlinear evolution law of slope risk with service age; this invention optimizes key protection parameters through sensitivity analysis, providing quantitative risk decision support for the design and maintenance of anchored slopes.

[0016] 2. This invention accurately quantifies the long-term performance degradation of anchor bolts: In view of the shortcomings of existing technologies that "fail to reflect the long-term performance degradation of anchor bolts, resulting in overly optimistic assessment results and misjudgments of safety", this invention achieves accurate prediction of anchoring force throughout its entire life cycle by constructing a "time-varying degradation model of anchor bolts coupled with multiple environmental parameters".

[0017] 3. This invention quantifies the failure mechanism of the synergistic effect of "time-varying degradation-dynamic load": Through the correlation analysis of failure probability curves and failure mode transformation, it reveals the failure mechanism transformation law of "interface control → rod control"; it integrates dual randomness to achieve quantitative assessment of full life cycle risk: In view of the shortcomings of existing technologies that "do not integrate environmental randomness and load randomness, and cannot quantify full life cycle risk", this invention constructs a time-varying model of anchor free section cross-sectional loss and interface bond strength decay, combined with the probability distribution of dynamic load parameters, to achieve dynamic tracking of the full life cycle risk of anchored slopes from "initial completion" to "100-year service life", and outputs failure probability curves for different service ages.

[0018] 4. This invention provides a quantitative basis for design and maintenance: In view of the shortcomings of existing technologies that "design optimization and maintenance decisions lack quantitative basis and rely on experience judgment", this invention uses "sensitivity analysis and parameter optimization". Through sensitivity analysis, the impact of key design parameters and environmental parameters on long-term reliability can be quantitatively assessed, providing a direct and quantitative scientific basis for the optimized design of new projects and the preventive maintenance of in-service projects. Attached Figure Description

[0019] Figure 1This is a flowchart illustrating a risk assessment method for anchored slopes that considers the combined effects of time-varying deterioration of anchor bolts and dynamic loads. Figure 2 This is a diagram of a slope stability analysis model based on the horizontal slice method provided by the present invention. Figure 3 This is a force analysis diagram of the horizontal strip i provided by the present invention; Figure 4 This invention provides a dynamic amplification factor diagram of the horizontal inertial force of an earthquake along the slope elevation. Figure 5 This is a cross-sectional view of a slope anchorage design provided by the present invention; Figure 6 This is a diagram showing the instability probability and reliability index of a slope anchor bolt after time-varying deterioration and encountering dynamic load, provided by the present invention. (a) represents the instability probability of the slope under earthquake action at different service ages in the embodiment of the present invention, and (b) represents the reliability index of the slope under earthquake action at different service ages in the embodiment of the present invention. Figure 7 This is a graph showing the change in failure probability of slope systems with different anchor bolt bonding layer thicknesses over time, as provided by the present invention. Figure 8 This is a graph showing the change in failure probability of a slope system at different temperatures over service time, provided by the present invention. Figure 9 This is a graph showing the change in the failure probability of a slope system with different humidity levels over service time, provided by the present invention. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Example 1: The core of this embodiment lies in constructing a risk assessment method for anchored slopes that considers the combined effects of time-varying anchor deterioration and dynamic loads. It improves assessment accuracy through a time-varying reliability analysis framework and quantifies the risk level of the slope at different service stages through sensitivity analysis. To achieve this goal, the key technical approach of this invention is to improve the traditional static reliability analysis framework and construct a completely new time-varying reliability analysis system.

[0022] To achieve the above objectives, the technical solution of this invention is summarized as follows: A method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, comprising the following steps: S1. Data Acquisition and Processing: Conduct engineering geological and environmental surveys to obtain slope soil and rock parameters, anchoring system design parameters, and environmental corrosivity data. Clean, standardize, and fit the probability distribution of the multi-source data.

[0023] S2. Establishment of Time-Varying Deterioration Model for Anchoring System: Based on environmental parameters, a prediction model for the deterioration rate of anchor bolts is established, and then time-varying functions of mortar-rock interface bonding resistance are constructed. Time-varying function of resistance at the anchor bolt-mortar interface and the time-varying function of the yield resistance of the free section of the anchor bolt reinforcement The overall time-varying resistance of the system is taken as the minimum value among the three: This characterizes the nature of the anchoring system's degradation over service time and the possible transformation of its failure mode control mechanisms. S3. Construction of the limit state equation for the combined action of time-varying anchor bolt deterioration and dynamic load: The time-varying resistance... By combining the load effects caused by dynamic loads, a limit state equation considering coupling effects is established.

[0024] S4. Time-varying reliability calculation and analysis: Solve the limit state equation using the reliability method to calculate the failure probability of the slope at different service ages. P f (t), and plot the time-varying curve of failure probability to analyze its evolution law.

[0025] S5. Sensitivity Analysis and Parameter Optimization: Analyze which parameters affect the slope failure probability. P f (t) has the greatest impact, and with the goal of "reducing the probability of slope failure throughout its entire life cycle", the design parameters are adjusted in a targeted manner in combination with key parameters to ensure safety while taking into account economy.

[0026] Step S1 requires a detailed engineering geological survey and service environment investigation of the target anchoring slope, and data preprocessing. The specific steps are as follows: S1.1: Geotechnical Parameter Survey: A combination of drilling, geophysical exploration, and in-situ testing was employed to determine the lithology, geological structure, rock mass structural features, and potential slip surface locations of the slope. Key physical and mechanical parameters of the geotechnical mass, such as unit weight, cohesion, internal friction angle, and elastic modulus, were obtained through in-situ field tests and laboratory geotechnical tests, and their spatial variability was assessed. S1.2: Current Status Survey of Anchoring System: Review the original design drawings to verify the design parameters such as the spacing, length, inclination angle, length of the free section and anchorage section, material and specifications of the anchor rods, and strength grade of the grout. Use partial excavation sampling or non-destructive testing techniques to assess the current condition of the anchor rods in service, including prestress loss and the integrity of the protective layer. S1.3: Environmental erosivity survey: Deploy miniature weather stations and groundwater monitoring points in the slope area and conduct continuous monitoring for at least one full year; take samples at anchor bolt holes and different depths to test the pH and Cl values ​​of the groundwater. -Ion concentration, SO4² - Chemical indicators such as ion concentration and resistivity were measured. The pH of the groundwater was tested using a pH meter to determine the environmental corrosion level. Core samples of the grouting body were collected, and its density, permeability, and chloride ion diffusion coefficient were measured in the laboratory to evaluate its ability to protect the reinforcing steel. S1.4: Data cleaning and standardization: Clean all collected data and remove outliers and invalid records; S1.5: Dimensional unification: Convert data from different sources and with different dimensions into a unified format and standard, and use the "range standardization method" to eliminate the influence of dimensions; S1.6: Probability distribution fitting: Fitting the probability distribution of random variables such as soil and rock parameters to determine their statistical characteristics; S1.7: 3D geological modeling: Using GIS or professional geological modeling software, integrate geological survey data to construct a 3D geological model that can accurately reflect the distribution of slope strata, structural planes, and potential slip surfaces, providing a geometric basis for subsequent numerical analysis.

[0027] Step S2 establishes a multi-interface resistance time-series model of environmental parameters, constructs a full-life-cycle performance degradation model of the anchoring system, quantifies the failure mode control mechanism conversion, and establishes a time-varying deterioration model of the anchored slope. The specific steps are as follows: S2.1: Anchor Bolt Uniform Corrosion Rate Prediction Model: Based on indoor accelerated corrosion test data and environmental survey data, the annual corrosion rate of the anchor bolt body is calculated using empirical or theoretical models. i cor Assuming uniform corrosion of the anchor cable, the corrosion rate can be calculated using the following expression: (1) S2.2: This further affects the corrosion rate. i cor Integral prediction service t Corrosion of anchor rod reinforcement after service years: (2) S2.3: (1) Time-varying function of mortar-rock interface bond resistance (3) This represents the average initial shear strength (kPa) of the grouting mortar and the surrounding soil. D The diameter of the anchor bolt borehole (m); L m The effective anchorage length (m) is the mortar-rock interface.

[0028] S2.4: (2) Time-varying function of resistance at the anchor-mortar interface (4) This represents the initial shear strength (kPa) between the grout and the anchor. d b The diameter of the anchor bolt borehole (m); L n The effective anchorage length (m) at the anchor bolt-mortar interface; R ( t ) represents the time-varying attenuation coefficient of the bond strength between the anchor bolt and the mortar interface under corrosion.

[0029] Its time-varying decay coefficient function expression R(t) is: (5) S2.5: (3) Time-varying function of yield resistance of the free section reinforcement of the anchor bolt (6) In the formula: d The diameter of the anchor rod (m) is... f k0 The initial yield strength (kPa) of the anchor rod reinforcement before corrosion. η s ( t )for t Corrosion rate of anchor bolt cross section at any given time. α st ( t )for t The time-varying reduction factor of the yield strength of anchor reinforcement under constant corrosion.

[0030] S3. Based on the "time-varying degradation - dynamic load" analysis logic, establish the limit state equation for the anchor bolt under the combined action of time-varying degradation and dynamic load. The specific steps are as follows: S3.1: Establishing the limit state equation for anchored slopes under time-varying deterioration based on "time-varying resistance - dynamic load effect": Considering the time-varying deterioration of the anchor, three failure modes of the anchor are obtained, and the established time-varying function of mortar-rock interface bonding is established respectively. Time-varying function of anchor bolt-mortar interface Time-varying function of yield resistance of free section reinforcement However, any failure mode can cause anchor bolt failure, therefore the maximum time-varying anchoring force that prestressed anchor cables can provide for slope reinforcement is... The minimum value among the three was obtained, and a time-varying degradation model of the dynamic performance of prestressed anchor bolts as a function of service life was established, taking into account the deterioration caused by accidents. (7) S3.2: Establishment of the Limit State Equation for Anchored Slopes under Dynamic Load: For the stability analysis of uniform rock slopes under dynamic load, this study adopts the assumption of a circular arc-shaped critical slip surface and constructs a simplified mechanical model based on plane strain conditions. For example... Figure 1 As shown, in the slope model, a unit length of soil and rock mass is cut out laterally as the research object of the horizontal slice method, where the isolated body... i The stress state is as follows Figure 2 As shown. To quantitatively assess the impact mechanism on the stability of anchored slopes under dynamic loads, the following basic assumptions are established: 1) Based on linear elastic theory, the back slope soil and rock mass and anchor system are simplified as elastic media, and the influence of plastic deformation on the energy dissipation of the system is ignored; 2) Regarding the assumption of slip surface morphology, it is stipulated that the critical slip surface must pass through the toe of the slope; 3) To simplify the calculation, it is assumed that only one type of soil layer exists in the model, and that in each horizontal block... i Above, all have the effect of, such as Figure 4 The force shown; 4) The ultimate tensile strength of the mortar-rock interface is regarded as the maximum tensile strength that the anchor can provide, and it is assumed that the tensile strength is uniformly distributed along the slip surface.

[0031] According to the Mohr-Coulomb failure criterion, horizontal stripe unit i The shear strength of the sliding surface can be expressed as: (8) In the formula, For cohesion, It is the internal friction angle. This refers to the normal stress. For a slope to achieve long-term stability, a certain safety reserve is required, namely the shear strength on the slope slip surface. It only partially functions, and is related to the tangential force of the slip surface. A balance is formed.

[0032] Assuming the dynamic safety factor of the slope is Then we have: (9) According to the force equilibrium condition of the horizontal block, the expression for the normal force is: (10) In the formula, α i The angle of inclination of the slip surface. Q hi For the horizontal inertial force of an earthquake, T' mi This represents the tensile force component of the anchor bolt. E i and X i These are the inter-strip normal force and shear force, respectively.

[0033] According to the principle of force equilibrium, the shear forces interacting between the blocks cancel each other out as a whole, and the total resultant force is zero, as expressed below: (11) Substituting equation (9) into equation (10), we obtain the formula for calculating the safety factor of anchored slopes under seismic action: (12) Considering the horizontal inertial force caused by the earthquake and the elevation amplification effect, a quasi-static method is used for calculation. (13) Acceleration amplification factor According to the segmented definition in the "Code for Seismic Design of Hydraulic Structures", Figure 3 The dynamic amplification factor of the horizontal inertial force during earthquakes along the slope elevation is: When H≤40m, the dynamic amplification factor follows a trapezoidal distribution, with the largest dynamic amplification factor at the top of the slope. The amplification factor at the bottom of the slope is taken as 1, and the amplification factor at the top of the slope is 2~3. (14) When H≥40m: (15) In the formula, h i The height from the center of the strip to the bottom of the slope. S a This represents the peak ground acceleration due to the horizontal force of the earthquake.

[0034] S3.2: Establishment of the limit state equation for the anchored slope under the combined action of time-varying anchor deterioration and dynamic load: By introducing a time-varying deterioration model of the dynamic performance of the anchor as it changes with its service life, the limit state equation for the anchored slope under the combined action of time-varying anchor deterioration and dynamic load can be obtained as follows: (16) As can be seen from the above equation, the limit state equation of the anchored slope under the combined action of time-varying deterioration of the anchor bolt and dynamic load is a function of service time, horizontal acceleration of dynamic load, and soil parameters.

[0035] S4. Based on reliability theory, calculate the reliability of anchored slopes under the combined action of time-varying deterioration and dynamic loads of anchor bolts, and realize the dynamic quantification of the failure probability of the slope throughout its entire life cycle. The specific steps are as follows: S4.1: Calculate the slope reliability index using the verification point method. β and failure probability P f Write genetic algorithm code to determine the limit state equation. Z The parameters in the code are random variables, and the implementation steps are as follows: (1) Clearly define the parameters of the soil and rock mass ( c , φ , γ ), seismic motion parameters ( S a ), Anchor bolt corrosion environmental parameters (Δ d To ensure the scientific validity and accuracy of the probability assessment results, the random uncertainty of (t) and material resistance parameters should be considered, and the distribution type and statistical parameters of each variable should be clearly defined. μ , σ (correlation coefficient) (2) The limit state function Z ( t Convert to standard normal space; (3) Solve for the verification points x* (make Z ( x* () = 0 and the point closest to the origin); (4) Calculate the reliability index β and according to β Calculate the probability of failure P f =Φ(- β ); (5) Set service life calculation nodes (e.g., 10 years, 20 years, 30 years, 50 years and 100 years). For each node: 1) Substitute the anchor corrosion amount Δd(t) at that time to calculate the time-varying anchoring force T(t). t 2) Generate peak ground acceleration (PGA) S a 3) Calculate the random sample for each group using the checkpoint method. S a corresponding β and P f The average value is taken as the failure probability for that service life. S4.2: By executing the time-varying reliability calculation process, the failure probability of the anchored slope at different service time points is obtained, and its evolution law is analyzed in depth to reveal the long-term performance degradation mechanism of the slope under the time-varying deterioration-dynamic load coupling effect. The specific steps are as follows: (1) Nonlinear accelerated growth characteristics: 1) Set service age calculation nodes (such as 0 years, 10 years, 20 years, 30 years, 50 years, 80 years, 100 years). For each node, combine the time-varying deterioration parameters of the anchor bolts and the dynamic load parameters, and use the reliability calculation method to obtain the slope failure probability of each node. P f (t); 2) Based on each node P f(t) Data, with "service age" as the horizontal axis and "failure probability" as the vertical axis, plot the "service age-failure probability" curve; 3) Observe the curve slope change characteristics: distinguish the curve shape of the early service period and the middle and late service period (which lead to a significant decline in mechanical performance and the deterioration process caused by dynamic load), identify the characteristics of the curve transitioning from "slow growth" to "steep growth", and clarify the stage division basis for the nonlinear accelerated growth of failure probability.

[0036] (2) Failure Mode Control Mechanism Conversion Analysis Method: 1) Dominant Failure Mode Identification: Identify the potential dominant failure modes of the anchoring system, including grout-rock interface bond failure, rod-grout interface bond failure, and free section rod tensile strength failure; calculate the anchoring resistance corresponding to different failure modes at each service age node, and determine the dominant failure mode controlling the overall resistance of the anchoring system at each node; 2) Failure Mode Conversion and P f ( t Correlation analysis of curves: plotting P f ( t The curve is analyzed and the acceleration inflection point is identified; the dominant failure mode of the anchoring system is recorded from the grout-rock interface. / Bond failure at the rod-grout interface "Transformed into "Tensile strength failure of free segment bar" "The critical time point; will P f ( t The acceleration inflection point of the curve is compared with the critical time point of the dominant failure mode transition to analyze the temporal correlation between the two and verify the impact of failure mode transition on the critical time point of the dominant failure mode transition. P f ( t 3) Compare the magnitude of anchoring resistance corresponding to each failure mode and determine the dominant failure mode controlling the overall resistance of the anchoring system at each age node.

[0037] S5. Sensitivity analysis and parameter optimization based on the reliability model, the specific steps are as follows: S5.1 Sensitivity Analysis: Using the first-order second-moment method or Monte Carlo simulation, the sensitivity coefficients of each random variable are calculated to identify the key parameters that have the greatest impact on the failure probability. The effects of environmental temperature and humidity changes on the anchor bolt corrosion rate and final... P f The amplification effect.

[0038] S5.2 Parameter Optimization: With the goal of reducing the probability of failure throughout the entire life cycle, key design parameters are optimized based on the results of sensitivity analysis.

[0039] Example 2: This scheme aims to elaborate on a risk assessment method for in-service anchored slopes, comprehensively considering the combined effects of time-varying anchor deterioration and dynamic loads. The system systematically introduces the entire implementation process from data acquisition, model building, coupled analysis to engineering decision-making, providing a clear guide for the engineering application of core technologies.

[0040] Figure 1 This is a schematic diagram of the risk assessment process for anchored slopes considering the combined effects of time-varying anchor deterioration and dynamic loads provided by this invention. The method for risk assessment of anchored slopes considering the combined effects of time-varying anchor deterioration and dynamic loads is explained in detail with reference to embodiments. This embodiment uses "data acquisition and processing → establishment of a time-varying anchor system deterioration model → construction of the limit state equation for the combined effects of time-varying anchor deterioration and dynamic loads → time-varying reliability calculation and analysis → sensitivity analysis and parameter optimization → risk assessment and decision support" as its core process. It achieves full life-cycle reliability assessment and risk management for anchored slopes under the combined effects of time-varying anchor deterioration and dynamic loads. This embodiment selects a rock-anchored slope in a temperate monsoon marine climate zone; the slope is a uniform slate slope.

[0041] Engineering geological investigation and environmental survey: (1) Geotechnical parameters survey: The slope is a single slate layer with no weak interlayers and a potential sliding surface depth of 5-8m; the mechanical parameters and statistical characteristics of the geotechnical mass were obtained through indoor triaxial tests, as shown in Table 1; (2) Current status survey of the anchoring system: Review the design drawings (refer to) Figure 5 Table 7) shows the anchor bolt arrangement (spacing 4m×4m, inclination angle 15°) and grout parameters (water-cement ratio 0.45, grade 42.5 cement, compressive strength). σ c =42.5MPa); Local excavation and sampling were used to measure the initial prestress loss rate and the thickness deviation of the bond layer; (3) Environmental erosivity survey: Miniature weather stations were set up at the top, middle and bottom of the slope to monitor temperature and humidity for 12 consecutive months; samples were taken at the anchor bolt holes and groundwater level, and Cl was measured using an ion chromatograph. - / SO4² - Concentration, results are as follows: annual average temperature 8-12℃, annual average relative humidity 65%-70%, groundwater Cl - With a concentration of 0.05 mg / L, the environmental corrosion level is determined to be "weak corrosion".

[0042] Data acquisition and preprocessing: (1) Outlier data were removed using the 3σ criterion; quantitative parameters were made dimensionless; and parameter distribution was verified using the KS test: soil and rock mass c, φ Fitting a log-normal distribution, fitting a normal distribution to ambient temperature and humidity, earthquake. S aFitting an extreme value type I distribution, the earthquake parameters are as follows: peak horizontal acceleration. S a After following a type I extreme value distribution and being converted to a normal distribution, the mean μ Sa =1.4825m / s², standard deviation σ Sa =1.6076m / s² (taking 0.2g as an example), independent of the soil and rock parameters.

[0043] (2) Using finite element software, integrate geological survey data to construct a three-dimensional geological model that can accurately reflect the distribution of strata, structural planes and potential slip surfaces of the slope, providing a geometric basis for numerical analysis.

[0044] Table 1 Slope geometry and soil parameters

[0045] The slope is supported by seven rows of tension-type prestressed anchor bolts, and the specific parameters are shown in Table 2. Table 2 Anchor Bolt Working Condition Parameter Table

[0046] Anchor bolt time-varying deterioration calculation and analysis: Parameter values ​​are taken from formulas (1) and (2): k cr =1.0 (anchor bolts are arranged in the center). k ce =4.0 (weakly corrosive environment) T =10℃ (annual average temperature). RH =67% (annual average humidity) d c =30mm, σ c =42500 kPa; Calculation results: i cor =0.0008mm / year, that is, the corrosion amount of the anchor bolt section Δd (t) = 0.08mm after 100 years of service.

[0047] Construction of time-varying resistance function: Using formulas (3)-(5), we can calculate T1(t)=204.2kN (12m anchorage section) and 153.1kN (9m anchorage section). Since the rock mass creep is ignored, it is temporarily regarded as a constant value; we can calculate T2(0)=2714kN and T2(100)=291kN; we can calculate T3(0)=1316kN and T3(100)=1033kN.

[0048] Construction of the limit state equation under the combined action of time-varying anchor bolt deterioration and dynamic load: Based on the "time-varying anchoring force + dynamic characteristics of dynamic load", the limit state equation of the slope is established in three steps.

[0049] (1) Establish the limit state equation of the anchored slope under the action of time-varying deterioration of anchor bolts; (2) Establish the limit state equation of the anchored slope under the action of dynamic load; (3) Establish the limit state equation of the anchored slope under the combined action of time-varying deterioration of anchor bolts and dynamic load.

[0050] The slope reliability index is calculated using the Form of Measure (FORM) method. β and failure probability P f .

[0051] Verification point solution and result calculation: (1) Equivalent normalization: converting non-normal variables ( c , φ (1) Transform to standard normal space; (2) Iteratively solve for the verification points: solve for the verification points x* (3) Multi-age period calculation: Set 7 nodes for 0, 10, 20, 30, 50, 80 and 100 years, and substitute each node T ( t ), generating 1000 sets of earthquakes for each node. S a The sample is used, and the mean is taken as the average for that age group. P f .

[0052] Table 3 Random variables of soil parameters

[0053] Verification point solution and result calculation: Plotting "Service Age - P f "Curve (Figure 6)."

[0054] Table 4 P f and β Changes with service age

[0055] 1) Substitute the anchor corrosion amount Δd(t) at that moment to calculate the time-varying anchoring force T(t). t 2) Generate peak ground acceleration (PGA) S a 3) Calculate the random sample for each group using the checkpoint method. S a corresponding β and P f The average value is taken as the failure probability for that service life; as shown in Table 4, after 50 years, the failure mode changes (mainly due to the anchor-mortar interface). P f It exhibits non-linear accelerating growth.

[0056] Analyzing the impact of core parameters such as "coating thickness, temperature and humidity" on the 100-year lifespan. P f The impact provides a basis for design optimization. Figures 7-9 ).

[0057] Influence of coating thickness: control T =10℃ RH =67%, S a =0.2g, analyze the time-varying failure probability of anchored slopes under different anchor bond layer thicknesses (e.g., Figure 7 The results show that the thickness curves of different bonding layers exhibit a "thin layer, early failure; thick layer, gradual failure" characteristic. Thin bonding layers show an accelerated failure probability around 30 years; thick bonding layers show an accelerated failure probability delayed until around 50 years, with a 42% reduction in the 100-year failure probability compared to 20mm. When the thickness exceeds 40mm, a critical thickness effect is observed. The time-varying failure probability of anchored slopes decreases with increasing bonding layer thickness.

[0058] The effects of temperature and humidity: Figure 8 and Figure 9 The time-varying relationships between temperature, humidity and slope system failure probability are presented respectively. For every 10°C increase in temperature, the failure probability rate increases by 15%-25%; for every 20% increase in humidity, the failure probability rate increases by 15%-25%.

[0059] Synergistic effect modeling technology: For the first time, a risk assessment model under the synergistic effect of "anchor rod time-varying deterioration-dynamic load" is established, quantifying the "1+1>2" amplification effect of the two, breaking through the limitations of existing single-factor analysis; A precise quantitative method for time-varying degradation: Based on multiple environmental parameters, a uniform corrosion rate model for anchor rods is constructed. Combined with time-series functions of interfacial bond strength and free segment yield strength, the full-cycle accurate prediction of anchor force decay is achieved. Failure mechanism transition criteria: revealing the transition law of anchor bolt failure modes with service time, and establishing a calculation method for the critical transition time point; Risk-economic balance optimization technology: By identifying key parameters through sensitivity analysis, a genetic algorithm is used to achieve a "safety-economic" balance optimization, providing a quantitative basis for engineering design and maintenance; The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration of anchor bolts and dynamic loads, characterized in that: It includes the following steps: S1. Data Acquisition and Processing: Conduct engineering geological and environmental surveys to obtain slope soil and rock parameters, anchoring system design parameters, and environmental corrosivity data. Clean, standardize, and fit the probability distribution of the multi-source data. S2. Establishment of Time-Varying Deterioration Model for Anchoring System: Based on environmental parameters, a prediction model for the deterioration rate of anchor bolts is established, and then the bonding resistance of the mortar-rock interface is constructed. Time-varying function, time-varying function of resistance at the anchor-mortar interface and the time-varying function of the yield resistance of the free section of the anchor bolt reinforcement The overall time-varying resistance of the system is taken as the minimum value among the three: This characterizes the nature of the anchoring system's degradation over service time and the possible transformation of its failure mode control mechanisms. S3. Construction of the limit state equation for the combined action of time-varying anchor bolt deterioration and dynamic load: The time-varying resistance... By combining the load effects caused by dynamic loads, a limit state equation considering coupling effects is established; S4. Time-varying reliability calculation and analysis: Solve the limit state equation using the reliability method to calculate the failure probability of the slope at different service ages. P f (t), and plot the time-varying curve of failure probability to analyze its evolution law; S5. Sensitivity Analysis and Parameter Optimization: Analyze which parameters affect the slope failure probability. P f (t) has the greatest impact, and with the goal of "reducing the probability of slope failure throughout its entire life cycle", the design parameters are adjusted in a targeted manner in combination with key parameters to ensure safety while taking into account economy.

2. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 1, is characterized in that: S1 specifically includes the following steps: S1.1: Geotechnical Parameter Survey: Using a combination of drilling, geophysical exploration, and in-situ testing, the lithology, geological structure, rock mass structural features, and potential slip surface locations of the slope were determined. Key physical and mechanical parameters of the geotechnical mass, such as unit weight, cohesion, internal friction angle, and elastic modulus, were obtained through in-situ field tests and laboratory geotechnical tests, and their spatial variability was assessed. S1.2: Current status survey of anchoring system: Review the original design drawings to verify the arrangement spacing, length, inclination angle, length of free section and anchoring section, material and specifications of the rod, and design parameters of grout strength grade of the prestressed anchors; use partial excavation sampling or non-destructive testing technology to assess the current status of the anchors in service, including the prestress loss and the integrity of the protective layer; S1.3: Environmental erosivity survey: Deploy miniature weather stations and groundwater monitoring points in the slope area and conduct continuous monitoring for at least one full year; take samples at anchor bolt holes and different depths to test the pH and Cl values ​​of the groundwater. - Ion concentration, SO4² - Chemical indicators such as ion concentration and resistivity were measured. The pH of groundwater was tested using a pH meter to determine the environmental corrosion level. Grout core samples were collected, and their density, permeability, and chloride ion diffusion coefficient were measured in the laboratory to evaluate their ability to protect steel bars. S1.4: Data cleaning and standardization: Clean all collected data and remove outliers and invalid records; S1.5: Dimensional unification: Convert data from different sources and with different dimensions into a unified format and standard, and use the "range standardization method" to eliminate the influence of dimensions; S1.6: Probability distribution fitting: Fitting the probability distribution of random variables such as soil and rock parameters to determine their statistical characteristics; S1.7: 3D geological modeling: Using GIS or professional geological modeling software, integrate geological survey data to construct a 3D geological model that can accurately reflect the distribution of slope strata, structural planes, and potential slip surfaces, providing a geometric basis for subsequent numerical analysis.

3. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 1, is characterized in that: The specific steps of step S2 are as follows: S2.1: Constructing a prediction model for the uniform corrosion rate of anchor bolts: Based on indoor accelerated corrosion test data and environmental survey data, the annual corrosion rate of the anchor bolt body is calculated using empirical or theoretical models. i cor Assuming uniform corrosion of the anchor cable, the expression for calculating its corrosion rate is as follows: ； kcr The anchor cable position correction factor is set to 1.

0. kce This is an environmental condition correction factor, taken as 4.0; T Ambient temperature; RH The relative humidity of the environment; DC The thickness of the anchor cable bonding layer; σc The compressive strength of the grouting body; S2.2: This further affects the corrosion rate. i cor Integral prediction service t Corrosion of anchor bolt reinforcement bars after service years: ； In the formula, This represents the time period. τ The instantaneous nominal corrosion rate at this specific moment; S2.3: Constructing the time-varying function of mortar-rock interface bond resistance: ； In the formula, This represents the average initial shear strength of the grouting mortar and the surrounding soil layer. D The diameter of the anchor bolt borehole; L m The effective anchorage length at the mortar-rock interface; S2.4: Constructing the time-varying resistance function of the anchor bolt-mortar interface: ； In the formula, This represents the initial shear strength between the grout and the anchor bolt. d b The diameter of the anchor bolt borehole; L n The effective anchorage length at the anchor bolt-mortar interface; R ( t ) represents the time-varying attenuation coefficient of the bond strength between the anchor bolt and mortar interface under corrosion. Its time-varying decay coefficient function expression R ( t )for: ； In the formula, X p ( t ) for the first time in service of the anchor bolt t The annual mass corrosion ratio is defined as the percentage of mass lost due to corrosion to the original mass. S2.5: Constructing the time-varying function of the yield resistance of the reinforcement in the free section of the anchor bolt: ； In the formula: d The diameter of the anchor rod. f k0 The initial yield strength of the anchor rod reinforcement before corrosion. η s ( t )for t Corrosion rate of anchor bolt cross section at any given time. α st ( t )for t The time-varying reduction factor of the yield strength of anchor reinforcement under constant corrosion.

4. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 1, is characterized in that: Step S3 specifically includes the following steps: S3.

1. Establish the limit state equation of the anchored slope under time-varying deterioration based on the "time-varying resistance-dynamic load effect": ； S3.2 Establish the limit state equation for the anchored slope under dynamic load: According to the Mohr-Coulomb failure criterion, horizontal stripe unit i The shear strength of the sliding surface can be expressed as: ； In the formula, For cohesion, It is the internal friction angle. This refers to the normal stress; for the slope to achieve long-term stability, a certain safety reserve is required, namely the shear strength on the slope slip surface. It only partially functions, and is related to the tangential force of the slip surface. Achieving balance; Assuming the dynamic safety factor of the slope is Then we have: ； In the formula, For the first i The length of the bottom arc of each strip; Normal force; According to the force equilibrium condition of the horizontal block, the expression for the normal force is: ； In the formula, α i The angle of inclination of the slip surface. T' mi This represents the tensile force component of the anchor bolt. E i and X i These are the inter-strip normal force and shear force, respectively. For the first i The weight of each strip; This represents the difference in normal inter-strip force between adjacent strips; According to the principle of force equilibrium, the shear forces interacting between the blocks cancel each other out as a whole, and the total resultant force is zero, as expressed below: ； In the formula, Q hi This refers to the horizontal inertial force during an earthquake. The angle between the anchor bolt axis and the tangent to the bottom surface of the block; The formula for calculating the safety factor of anchored slopes under seismic loading is as follows: ； Considering the horizontal inertial force caused by the earthquake and the elevation amplification effect, a quasi-static method is used for calculation. ； Acceleration amplification factor Defined in sections according to the "Code for Seismic Design of Hydraulic Structures"; When H≤40m, the dynamic amplification factor follows a trapezoidal distribution, with the largest dynamic amplification factor at the top of the slope. The amplification factor at the bottom of the slope is taken as 1, and the amplification factor at the top of the slope is 2~3. ； When H≥40m: ; In the formula, H This represents the total height of the slope; h i The height from the center of the strip to the bottom of the slope. S a This represents the peak ground acceleration due to horizontal seismic action. S3.3 Establish the limit state equation for the anchored slope under the combined action of time-varying deterioration and dynamic load of the anchor bolt: ； As can be seen from the above equation, the limit state equation of the anchored slope under the combined action of time-varying deterioration of the anchor bolt and dynamic load is a function of service time, horizontal acceleration of dynamic load, and soil parameters.

5. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts as described in claim 1, characterized in that: Step 4 is specifically... Includes the following processes: S4.1: Calculate the slope reliability index using the verification point method. β and failure probability P f Write genetic algorithm code to determine the limit state equation. Z The parameters in the text are random variables; S4.2: By executing the time-varying reliability calculation process, the failure probability of the anchored slope at different service time points is obtained, and its evolution law is analyzed in depth to reveal the long-term performance degradation mechanism of the slope under the time-varying deterioration-dynamic load coupling effect.

6. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 5, is characterized in that: The specific implementation steps of S4.1 are as follows: (1) Clarify the random uncertainty of soil and rock parameters, ground motion parameters, anchor corrosion environment parameters and material resistance parameters, ensure the scientificity and accuracy of probability assessment results, and clarify the distribution type and statistical parameters of each variable; (2) The limit state function Z ( t Convert to standard normal space; (3) Solve for the verification points x* ,make Z ( x* The point whose value is 0 and which is closest to the origin; (4) Calculate the reliability index β and according to β Calculate the probability of failure P f =Φ(- β ); (5) Set service life calculation nodes. For each node: 1) Substitute the anchor corrosion amount Δd(t) at that moment to calculate the time-varying anchoring force T( t 2) Generate peak ground acceleration (PGA) S a 3) Calculate the random sample for each group using the checkpoint method. S a corresponding β and P f The average value is taken as the failure probability for that service life.

7. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 5, is characterized in that: The specific steps of S4.2 are as follows: (1) Nonlinear accelerated growth characteristics; (2) Determine the failure mode control mechanism conversion analysis method.

8. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 7, is characterized in that: The nonlinear accelerated growth characteristics include: 1) setting service life calculation nodes, and for each node, combining the time-varying degradation parameters of the anchor bolts and the dynamic load parameters, using the reliability calculation method to obtain the slope failure probability of each node. P f (t); 2) Based on each node P f (t) Data, with "service age" as the horizontal axis and "failure probability" as the vertical axis, plot the "service age-failure probability" curve; 3) Observe the curve slope change characteristics: distinguish the curve shape of the early service period and the middle and late service period that lead to a significant decline in mechanical performance and the deterioration process caused by dynamic load, identify the characteristics of the curve transitioning from "slow growth" to "steep growth", and clarify the stage division basis of the nonlinear accelerated growth of failure probability.

9. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 7, is characterized in that: Failure Mode and Control Mechanism (FMCM) conversion analysis methods include: 1) Dominant Failure Mode Identification: Identify the potential dominant failure modes of the anchoring system, including grout-rock interface bond failure, rod-grout interface bond failure, and free section rod tensile strength failure; calculate the anchoring resistance corresponding to different failure modes at each service age node, and determine the dominant failure mode controlling the overall resistance of the anchoring system at each node; 2) Failure Mode Conversion and P f ( t Correlation analysis of curves: plotting P f ( t The curve is analyzed and the acceleration inflection point is identified; the dominant failure mode of the anchoring system is recorded from the grout-rock interface. / Bond failure at the rod-grout interface "Converted to "Tensile strength failure of free segment bar" "The critical time point; will P f ( t The acceleration inflection point of the curve is compared with the critical time point of the dominant failure mode transition to analyze the temporal correlation between the two and verify the impact of failure mode transition on the critical time point of the dominant failure mode transition. P f ( t 3) Compare the magnitude of anchoring resistance corresponding to each failure mode and determine the dominant failure mode controlling the overall resistance of the anchoring system at each age node.

10. The method for risk assessment of anchored slopes considering the combined effects of time-varying deterioration and dynamic loads of anchor bolts, as described in claim 1, is characterized in that: Step S5 specifically includes: S5.1 Sensitivity Analysis: Using the first-order second-moment method or Monte Carlo simulation, the sensitivity coefficients of each random variable are calculated to identify the key parameters that have the greatest impact on the failure probability; the effects of changes in environmental temperature and humidity on the anchor bolt corrosion rate and final... P f The amplification effect; S5.2 Parameter Optimization: With the goal of reducing the probability of failure throughout the entire life cycle, key design parameters are optimized based on the results of sensitivity analysis.

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