A method for evaluating the toughness of gravity retaining walls based on performance degradation

Abstract

A method for evaluating the toughness of gravity retaining walls based on performance degradation is proposed. Addressing the shortcomings of existing toughness assessments for gravity retaining walls, which often focus on static performance, struggle to quantify the dynamic impact of performance degradation during service life, and suffer from insufficient accuracy, this method comprises the following steps: 1. Constructing performance characterization indicators for gravity retaining walls; 2. Establishing a correlation model between the toughness and performance degradation of gravity retaining walls, classifying performance levels and determining the corresponding performance thresholds for each level, and fitting a performance degradation function; 3. Calculating the comprehensive toughness index within the assessment period based on the performance degradation function; 4. Establishing a weighted calculation model to determine the proportion of the toughness index for each performance characterization indicator; 5. Calculating the weighted comprehensive toughness index and outputting the toughness level, achieving a precise quantitative assessment of the toughness of gravity retaining walls. This invention provides a practical quantitative method for retaining wall design optimization, operational safety monitoring, and post-disaster recovery effect evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of retaining wall toughness evaluation in water conservancy engineering, and particularly relates to a gravity retaining wall toughness evaluation method based on performance attenuation, which can realize the toughness evaluation of gravity retaining wall in water conservancy engineering service period or after disaster damage. BACKGROUND

[0002] The gravity retaining wall resists the lateral pressure by its own gravity. Due to the advantages of simple structure, convenient construction, easy material selection and good economy, the gravity retaining wall has been widely used in the field of water conservancy engineering, and plays an important role in key projects such as river revetment, reservoir slope protection, dike reinforcement and the like. However, the traditional stability analysis of gravity retaining wall mainly focuses on static stability analysis, and uses safety factor as the evaluation standard, which cannot quantify the parameter uncertainty and comprehensively consider the resistance and recovery capacity of the gravity retaining wall. A large number of gravity retaining walls without protection or designed according to the conventional standard are prone to failure under extreme working conditions. The toughness evaluation and treatment method can integrate the whole chain ability of resistance-absorption-recovery of the structure under external disturbance, break through the traditional failure judgment logic, and has been well applied in the fields of water conservancy hub engineering, dike engineering, river and lake management engineering and the like. However, the toughness evaluation system for gravity retaining wall in the water conservancy engineering has not been established yet. Therefore, how to provide an adaptive gravity retaining wall toughness evaluation method to provide scientific support for structure design optimization, reinforcement decision and anti-disturbance capacity improvement is a technical problem to be solved in the field. SUMMARY

[0003] In view of the fact that the stability analysis method of gravity retaining wall cannot consider the resistance and recovery capacity of the gravity retaining wall structure, the present application aims to provide a gravity retaining wall toughness evaluation method based on performance attenuation to provide technical support for structure design optimization, reinforcement decision and anti-disturbance capacity improvement.

[0004] To achieve the above-mentioned purpose, the present application provides a gravity retaining wall toughness evaluation method based on performance attenuation, comprising the following steps:

[0005] S1. According to the stability analysis method of gravity retaining wall, the control indexes affecting the safety performance of gravity retaining wall are selected from the five safety dimensions of anti-overturning stability, anti-sliding stability, foundation bearing capacity, shear capacity and crack control, and the performance characterization indexes of gravity retaining wall are constructed;

[0006] S2. Based on the performance characterization indexes in S1, the toughness and performance attenuation correlation model of gravity retaining wall under each index is established, and the performance of gravity retaining wall is divided into four levels of "intact", "slight attenuation", "serious attenuation" and "failure", the performance threshold values corresponding to each level are determined, and the performance attenuation function is fitted.

[0007] S3, calculating the resilience indexes of normal stage and disaster stage in the evaluation period and the comprehensive resilience index of the coupling of the two under each performance characterization index based on the performance attenuation function in S2;

[0008] S4, constructing a judgment matrix of the performance characterization index based on each performance characterization index in S1 and the corresponding comprehensive resilience index in S3, establishing a weight calculation model of each index, and obtaining the resilience index proportion of each index;

[0009] S5, calculating the weighted comprehensive resilience index of the gravity retaining wall according to the resilience indexes of each performance characterization index in the evaluation period in S3 and the resilience index proportion of each index in S4, outputting the resilience grade, and realizing the precise quantitative evaluation of the resilience of the gravity retaining wall.

[0010] Compared with the prior art, the gravity retaining wall resilience evaluation method based on performance attenuation provided by the present application comprehensively considers the resistance, absorption and recovery ability of the structure to external water force and other disaster disturbances, constructs the performance characterization index and the corresponding weight calculation model of the gravity retaining wall, proposes a resilience evaluation method which can effectively calculate the resilience of the gravity retaining wall in the normal service period and after disaster damage in the water-involved scene from the perspective of performance attenuation, and has the following beneficial effects:

[0011] (1) The gravity retaining wall resilience evaluation method based on performance attenuation provided by the present application fuses five performance characterization indexes of anti-overturning stability, anti-sliding stability, bearing capacity attenuation degree, strength attenuation degree and crack evolution degree, and calculates the proportion of each performance characterization index through the weight calculation model, and then comprehensively reflects the influence between different indexes; since the data types collected by various sensors are inconsistent, the values and dimensions of the safety performance control indexes of the gravity retaining wall calculated are not unified, and comprehensive calculation cannot be performed, therefore, the calculation of the performance characterization index adopts a normalized representation method, which is simple and intuitive, and compared with the existing stability analysis method, the evaluation method is more reasonable and comprehensive.

[0012] (2) The gravity retaining wall resilience evaluation method based on performance attenuation provided by the present application analyzes the performance evolution law of the gravity retaining wall in the water conservancy project with time, combines the actual factors such as the resistance, absorption and recovery ability when it is disturbed by the outside world, comprehensively considers the resilience of the service period and the disaster stage, and has significant water conservancy engineering application value.

[0013] Compared with the prior art, the present application fuses multi-source monitoring data and theoretical analysis models, establishes a complete evaluation system from performance characterization to resilience quantification, can realize high-precision dynamic prediction of the weighted comprehensive resilience index, and is helpful for providing more scientific and intelligent decision support and calculation methods for the construction safety control of the gravity retaining wall in the water conservancy project. Attached Figure Description

[0014] Figure 1 This is a flowchart of the gravity retaining wall toughness assessment method based on performance degradation of the present invention.

[0015] Figure 2 This is a schematic diagram illustrating the performance levels and threshold classifications of the gravity retaining wall in the embodiment;

[0016] Figure 3 This is a schematic diagram illustrating the calculation of the toughness index in the embodiment;

[0017] Figure 4 This is a schematic diagram illustrating the toughness level determination in the embodiment;

[0018] Figure 5 This is a schematic diagram of the application scenario and sensor arrangement of gravity retaining wall in water conservancy engineering in the embodiment. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0020] Example

[0021] Example scenarios for risk control and safety assessment of gravity retaining walls in water conservancy projects during service life and under catastrophic disturbances such as hydraulic forces ( Figure 5 As shown in the figure, a toughness assessment framework is proposed that comprehensively considers multiple dimensions such as overturning stability, sliding stability, bearing capacity decay, strength decay, and crack evolution. Based on the geometric parameters and soil-water physical and mechanical parameters collected by various sensors on site, a function characterization of performance decay is established. A quantitative mechanism for the importance of indicators is constructed by combining subjective and objective weights, realizing dynamic analysis of the toughness index of water-related gravity retaining wall structures. This also provides a new approach for the toughness assessment of gravity retaining walls and other hydraulic retaining structures. This invention can calculate the evolution of gravity retaining wall performance over time. Compared with traditional stability analysis methods, it can provide more accurate real-time toughness state feedback, which has important theoretical reference significance for the design optimization and construction control of gravity retaining walls in hydraulic engineering.

[0022] The details are as follows:

[0023] like Figure 1 As shown, the gravity retaining wall toughness assessment method based on performance degradation involved in this embodiment includes the following steps:

[0024] S1: According to the stability analysis method of gravity retaining wall, the control index affecting the safety performance of gravity retaining wall is selected, and the performance characterization index of gravity retaining wall is constructed; wherein part of the control index affecting the safety performance of gravity retaining wall can be determined by formula (1)-(3); the performance characterization index of gravity retaining wall, including anti-overturning stability, anti-sliding stability, bearing capacity attenuation degree, strength attenuation degree, crack evolution degree, can be determined by formula (4)-(8).

[0025] (1)

[0026] In the formula, K t The anti-overturning stability coefficient of gravity retaining wall; G and x 0 Respectively, the self-weight of the retaining wall and the distance from the wall toe; E az and x f Respectively, the vertical component of the wall lateral pressure and the distance from the wall toe; E ax and z f Respectively, the horizontal component of the wall lateral pressure and the distance from the wall toe.

[0027] (2)

[0028] In the formula, K c The anti-sliding stability coefficient of gravity retaining wall; μ The friction coefficient of the retaining wall base; G The self-weight of the retaining wall; E az and E ax Respectively, the vertical component of the wall lateral pressure and the horizontal component.

[0029] (3)

[0030] In the formula, f a and f ak Respectively, the bearing capacity of the retaining wall bottom foundation and its characteristic value; η b and η d Correction coefficient; γ and γ m Respectively, the specific weight of the retaining wall bottom soil and the weighted specific weight of the soil above it; b and d Respectively, the width and buried depth of the retaining wall.

[0031] (4)

[0032] wherein, Q 1( t ) is a performance degradation function of gravity retaining wall characterized by the anti-overturning stability; K t ( t ) is t the anti-overturning stability coefficient of the retaining wall at the moment; K t the allowable anti-overturning stability coefficient.

[0033] (5)

[0034] wherein, Q 2( t ) is a performance degradation function of gravity retaining wall characterized by the anti-sliding stability; K c ( t ) is t the anti-sliding stability coefficient of the retaining wall at the moment; K c the allowable anti-sliding stability coefficient.

[0035] (6)

[0036] wherein, K p is the bearing capacity stability coefficient of the retaining wall; f a is the bearing capacity of the foundation of the bottom of the retaining wall; p k is the pressure of the bottom of the retaining wall;

[0037] wherein, Q 3( t ) is a performance degradation function of gravity retaining wall characterized by the bearing capacity degradation degree; K p ( t ) is t the bearing capacity stability coefficient of the retaining wall at the moment.

[0038] (7)

[0039] wherein, Q 4( t ) is a performance degradation function of gravity retaining wall characterized by the strength degradation degree; V ( t ) is t the maximum shear force received by the retaining wall at the moment; VThe allowable value of the retaining wall for bearing shear force.

[0040] (8)

[0041] In the formula, Q 5( t ) is a performance degradation function of the gravity retaining wall characterized by the crack evolution degree; w t ) is the maximum crack width of the retaining wall at the moment; t w The allowable crack width of the retaining wall.

[0042] S2: Based on the performance characterization index described in S1, a model of the correlation between the toughness and performance degradation of the gravity retaining wall under each index is established, and the performance of the gravity retaining wall is divided into four performance levels of “intact”, “slight degradation”, “serious degradation” and “failure” (as shown in the figure), the performance threshold corresponding to each level is determined, and the performance degradation function is fitted to establish the correlation model between the toughness and performance degradation. Figure 2

[0043] Specifically,

[0044] S2.1: Taking the performance natural degradation amplitude caused by material aging and environmental effects during the service period as the benchmark, if the performance of the gravity retaining wall is higher than the benchmark value, it is determined to be in the “intact” state. In addition, the gravity retaining wall usually has a certain safety redundancy in the design stage. When the performance is reduced due to disaster disturbance, if it can still maintain the basic function and can rely on the toughness of the structure to gradually recover, it is considered to be in the state of “slight degradation”, that is, the performance critical point that can recover autonomously after the disaster is defined as the “slight degradation” threshold. If the structural performance is lower than the “slight degradation” threshold but has not completely lost the function, it is in the state of “serious degradation”. In this state, it is difficult for the structure itself to effectively recover the basic performance, and it must rely on external intervention and repair measures to continue to function. When the performance further decreases to zero or below, the structure is considered to be in the “failure” state, at which time the retaining wall has completely lost its function and cannot be restored to its basic role through conventional repair measures.

[0045] S2.2: On the basis of the performance level division in S2.1, the time series information of the performance characterization index is obtained and calculated through sensor monitoring for the geometric parameters and wall-side hydrological and mechanical conditions of the gravity retaining wall to be evaluated, and the least squares method is used to realize the fitting of the performance degradation function of the gravity retaining wall in the evaluation period, and then the specific performance level of the gravity retaining wall to be evaluated is determined, and the correlation model between the toughness and performance degradation is established.

[0046] ​​​S3: Based on the performance degradation function obtained in S2, calculate the toughness index of the gravity retaining wall in the normal stage and disaster damage stage within the evaluation cycle under each performance characterization index, as well as the comprehensive toughness index coupled with the two.

[0047] like Figure 3 As shown, the meaning and calculation of each toughness index are explained below:

[0048] The resilience index is divided into a normal resilience index and a disaster resilience index. The calculation formula for the normal resilience index is as follows:

[0049] (9)

[0050] In the formula, R Ni For the first i The normal resilience index is represented by a performance characterization index. Q i ( t ) is the first i A performance degradation function represented by a performance characterization index; T For the evaluation period;

[0051] The formula for calculating the disaster resilience index is as follows:

[0052] (10)

[0053] In the formula, R Di For the first i A disaster resilience index represented by a performance characterization index; Q i ( t ), Q Di ( t ), Q Ei ( t )and Q Ri ( t ) are respectively the first i The performance degradation function is represented by a performance characterization index, which indicates the unperturbed stage, the disaster-damaged stage, the disaster-evolution stage, and the performance recovery stage. T For the evaluation period; T 1. T 2 and T 3 represents the duration of the disaster disturbance phase, the disaster evolution phase, and the performance recovery phase, respectively. T 1+ T 2+ T 3= T；

[0054] The occurrence of disasters is accidental. The toughness calculation of gravity retaining walls needs to comprehensively consider the performance degradation during the normal stage and the resistance, adaptation and recovery capacity during the disaster stage. The formula for calculating the comprehensive toughness index is as follows:

[0055] (11)

[0056] In the formula, R Ci For the first i A comprehensive resilience index represented by several performance characterization indicators. R Di For the first i A disaster resilience index represented by a performance characterization index; R Ni For the first i The normal resilience index is represented by a performance characterization index. P For a certain disaster during the assessment period T The probability of it occurring within a given timeframe.

[0057] S4: Based on the performance characterization indicators in S1 and the corresponding comprehensive resilience index in S3, construct the judgment matrix of the performance characterization indicators, establish the weight calculation model of each indicator, and obtain the resilience index ratio of each indicator.

[0058] The weight calculation model includes the calculation of subjective weight, objective weight, and comprehensive weight. The formula for calculating the subjective weight is as follows:

[0059] (12)

[0060] In the formula, W si For the first i Subjective weights of performance indicators; elements of judgment matrix A. A ij and A ik They represent the first i The performance characterization metric is relative to the first j The and the first k The importance of each performance metric;

[0061] The objective weight calculation formula is as follows:

[0062] (13)

[0063] In the formula, W oi For the first i Objective weights of each performance indicator; g i and g j The firsti the difference coefficient of the first j performance characterization index and the second performance characterization index;

[0064] The calculation formula of the comprehensive weight is as follows by considering the reliability of the subjective weight and the objective weight respectively:

[0065] (14)

[0066] In the formula, W i the comprehensive weight of the first i performance characterization index; W si and W sj the subjective weight of the first i performance characterization index and the subjective weight of the second j performance characterization index respectively; W oi and W oj the objective weight of the first i performance characterization index and the objective weight of the second j performance characterization index respectively; α i , α j and β i , β j the subjective weight reliability of the first i performance characterization index and the subjective weight reliability of the second j performance characterization index respectively.

[0067] S5: According to the toughness index of each performance characterization index in the evaluation period and the proportion thereof, the weighted comprehensive toughness index of the gravity retaining wall is calculated, the toughness grade is output, and the precise quantitative evaluation of the toughness of the gravity retaining wall is realized;

[0068] Specifically, as shown in the figure. The toughness grade is divided into high toughness, medium toughness and low toughness, and is determined in the following manner: Figure 4

[0069] High toughness: the toughness of the gravity retaining wall to be evaluated in the evaluation period is higher than the toughness of any gravity retaining wall of the “perfect” performance grade;

[0070] Medium toughness: the toughness of the gravity retaining wall to be evaluated in the evaluation period is higher than the toughness of any gravity retaining wall of the “slight attenuation” performance grade;

[0071] Low toughness: the toughness of the gravity retaining wall to be evaluated in the evaluation period is lower than the toughness of any gravity retaining wall of the “slight attenuation” performance grade.

Claims

1. A method for assessing the resilience of a gravity retaining wall based on performance degradation, characterized in that, The method comprises the following steps: S1, according to the stability analysis method of gravity retaining wall, the control indexes influencing the safety performance of the gravity retaining wall are selected from the five safety dimensions of the anti-overturning stability, the anti-sliding stability, the foundation bearing capacity, the shear capacity and the crack control of the gravity retaining wall, and the performance characterization indexes of the gravity retaining wall are constructed; In S1, the control index affecting the safety performance of the gravity retaining wall includes an overturning resistance stability coefficient K t , a sliding resistance stability coefficient K c , a foundation bearing capacity f a , a shear strength τ , a crack width w , wherein, The roll-over-resistance stability coefficient K t The calculation formula is as follows: （1） wherein K t is the overturning stability factor of the gravity retaining wall; G and x 0 is the weight of the retaining wall and its distance from the wall toe, respectively; E az and x f is the vertical component of the lateral pressure on the wall and its distance from the wall toe, respectively; E ax and z f is the horizontal component of the lateral pressure on the wall and its distance from the wall toe, respectively; The anti-skid stability coefficient K c The calculation formula is as follows: （2） wherein K c is the stability factor against sliding of the gravity retaining wall; μ is the friction coefficient of the retaining wall base; G is the self-weight of the retaining wall; E az and E ax are the vertical and horizontal components of the lateral pressure on the wall, respectively. The ground bearing capacity f a The calculation formula is as follows: （3） wherein, f a and f ak respectively are the bearing capacity of the foundation of the retaining wall bottom and its characteristic value; η b and η d is the correction coefficient; γ and γ m respectively are the specific weight of the retaining wall bottom soil and the weighted specific weight of the soil above it; b and d respectively are the width and the buried depth of the retaining wall; In S1, the performance characterization indexes of the gravity retaining wall include the anti-overturning stability, the anti-sliding stability, the bearing capacity attenuation degree, the strength attenuation degree and the crack evolution degree, wherein the anti-overturning stability calculation formula is as follows: （4） wherein Q 1( t ) is a performance degradation function of gravity retaining walls characterized by the anti-overturning stability; K t ( t ) is t the anti-overturning stability coefficient of the retaining wall at the instant; K t is the allowable anti-overturning stability coefficient; The anti-sliding stability calculation formula is as follows: （5） wherein Q 2( t ) is a performance degradation function of the gravity retaining wall characterized by the sliding stability; K c ( t ) is t the sliding stability coefficient of the retaining wall at the time; K c the allowable sliding stability coefficient; The bearing capacity attenuation degree calculation formula is as follows: （6） wherein Q 3( t ) is a performance degradation function of the gravity retaining wall characterized by a degree of bearing capacity degradation; K p ( t ) is t a stability coefficient of the bearing capacity of the retaining wall at the moment The bearing capacity stability coefficient calculation formula is as follows: （7） wherein K p is the stability factor of the retaining wall; f a is the bearing capacity of the foundation at the bottom of the retaining wall; p k is the pressure at the bottom of the retaining wall; The strength attenuation degree calculation formula is as follows: （8） wherein Q 4( t ) is a performance degradation function of the gravity retaining wall characterized by the degree of intensity degradation; V ( t ) is t the maximum shear force received by the retaining wall at the moment; V the allowable value of the shear force borne by the retaining wall. The crack evolution degree calculation formula is as follows: （9） wherein Q 5( t ) is a performance degradation function of the gravity retaining wall characterized by the degree of crack evolution; w ( t ) is t the maximum crack width of the retaining wall at the time; w the allowable crack width of the retaining wall; S2, based on the performance characterization indexes in S1, the resilience and performance attenuation correlation model of the gravity retaining wall under each index is established, the performance of the gravity retaining wall is divided into four levels of "intact", "slight attenuation", "serious attenuation" and "failure", the performance threshold corresponding to each level is determined and the performance attenuation function is fitted; Specifically, S2.1: taking the performance natural degradation amplitude caused by material aging and environmental action within the service period as the benchmark, if the performance of the gravity retaining wall is higher than the benchmark value, it is determined that the gravity retaining wall is in the "intact" state; If the structural performance is lower than the "slight attenuation" threshold, but has not completely lost the function, it is in the "serious attenuation" state; When the performance further decreases to zero or below, the structure is regarded as entering the "failure" state; S2.2: on the basis of the performance level division in S2.1, the time sequence information of the performance characterization indexes is obtained and calculated through sensor monitoring for the geometric parameters and wall side water and soil mechanics conditions of the gravity retaining wall to be evaluated, and the least square method is used to realize the fitting of the performance attenuation function of the gravity retaining wall in the evaluation period, so as to determine the specific performance level of the gravity retaining wall to be evaluated, and establish the resilience and performance attenuation correlation model thereof; S3, based on the performance attenuation function in S2, the resilience index of the normal stage and the disaster stage in the evaluation period under each performance characterization index is calculated; In S3, the resilience index is divided into normal resilience index and disaster resilience index, wherein the calculation formula of the normal resilience index is as follows: （10） wherein R Ni is a normal toughness index represented by the first i performance characterization index; Q i ( t ) is a performance degradation function represented by the first i performance characterization index; T is an evaluation period; The calculation formula of the disaster resilience index is as follows: （11） In the formula, R Di is the disaster damage resilience index represented by the first performance characterization index; i Q i t Q Di t Q Ei t Q Ri t i are performance decay functions of the undisturbed stage, the disaster damage disturbance stage, the disaster damage evolution stage, and the performance recovery stage respectively represented by the first performance characterization index; T is the evaluation period; T 1, T 2, and T 3 are the time lengths of the disaster damage disturbance stage, the disaster damage evolution stage, and the performance recovery stage respectively; T 1+ T 2+ T 3= T； ​​​​​​​​​ The occurrence of disasters is accidental, and the resilience calculation of the gravity retaining wall comprehensively considers the performance attenuation in the normal stage and the resistance, adaptation and recovery ability in the disaster stage, and the resilience index calculation formula is as follows: （12） wherein R Ci is a resilience index expressed as a performance characterization indicator; i R Di is a disaster resilience index expressed as a performance characterization indicator; i R Ni is a normal resilience index expressed as a performance characterization indicator; i P is a probability that a certain disaster occurs within an evaluation period T .​​​ S4, based on each performance characterization index in S1 and the corresponding resilience index in S3, a judgment matrix of the performance characterization index is constructed, a weight calculation model of each index is established, and the resilience index proportion of each index is obtained; S5, according to the resilience index of each performance characterization index in the evaluation period in S3 and the resilience index proportion of each index in S4, the weighted comprehensive resilience index of the gravity retaining wall is calculated, the resilience level thereof is output, and the precise quantitative evaluation of the resilience of the gravity retaining wall is realized.

2. The method for performance degradation-based gravity retaining wall toughness evaluation according to claim 1, wherein, In S2, the four grades are "intact", "slight attenuation", "severe attenuation" and "failure", and are determined as follows: "Intact" grade: the gravity retaining wall does not encounter catastrophe, and the performance only naturally decreases during the service period, and the main functions are not affected; "slight attenuation" grade: the gravity retaining wall still plays a basic role after performance attenuation caused by catastrophe disturbance, and its performance can slowly recover by relying on its own toughness; "severe attenuation" grade: the gravity retaining wall loses the main function after being disturbed by catastrophe, but it is still not completely failed, and it is difficult to recover only by relying on its own toughness, and needs to rely on external repair to continue to play a role; "failure" grade: the gravity retaining wall is completely failed and destroyed, loses all functions, and it is difficult to recover the basic function by repair.

3. The performance degradation-based gravity retaining wall toughness evaluation method of claim 1, wherein, In S4, the weight includes subjective weight and objective weight, wherein the subjective weight calculation formula is as follows: （13） In the formula, W si is the subjective weight of the first i performance characterization index; the elements of the judgment matrix A A ij and A ik respectively represent the importance of the first i performance characterization index relative to the first j and the second k performance characterization index. The objective weight calculation formula is as follows: （14） In the formula, W oi is the objective weight of the first i performance characterization index; g i and g j are the difference coefficients of the first i and the second j performance characterization index, respectively. Considering the reliability of subjective and objective weights respectively, the comprehensive weight calculation formula is as follows: （15） In the formula, W i is the comprehensive weight of the first i performance characterization index; W si and W sj are the subjective weights of the first i and the second j performance characterization index, respectively; W oi and W oj are the objective weights of the first i and the second j performance characterization index, respectively; α i , α j and β i , β j are the subjective weight reliability and the objective weight reliability of the first i and the second j performance characterization index, respectively.

4. The performance degradation-based gravity retaining wall toughness evaluation method of claim 1, wherein, In S5, the toughness grade is divided into high toughness, medium toughness and low toughness, and is determined as follows: High toughness: the toughness of the gravity retaining wall evaluated in the evaluation period is higher than that of any "intact" performance grade gravity retaining wall; Medium toughness: the toughness of the gravity retaining wall evaluated in the evaluation period is higher than that of any "slight attenuation" performance grade gravity retaining wall; Low toughness: the toughness of the gravity retaining wall evaluated in the evaluation period is lower than that of any "slight attenuation" performance grade gravity retaining wall.

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