Total probability risk assessment method for crossing earthquake fracture in railway line selection scheme

Abstract

The invention relates to the technical field of railway line selection, and relates to a total probability risk assessment method for crossing earthquake fracture in a railway line selection scheme. According to the evaluation method, Monte Carlo simulation is adopted, a cross-fault-zone total probability risk analysis model suitable for railway line selection design is established, on the basis of a performance-based seismic engineering theory, fault zone displacement probability risk analysis, railway structure probability vulnerability analysis and railway post-fracture probability economic loss analysis are integrated, and the fault zone displacement probability risk analysis, the railway structure probability vulnerability analysis and the railway post-fracture probability economic loss analysis are integrated. According to the method, the annual exceeding probability of a specific displacement value can be calculated in combination with fault zone characteristics (position, geometric morphology and earthquake intensity), the damage state of different railway structures (generally avoiding crossing the fault zone by adopting a bridge mode) under the influence of the fracture displacement is mainly considered, and meanwhile, the damage state of the different railway structures under the influence of the fracture displacement is evaluated. And the cross-fault-zone probability risk analysis model and the cost minimization model are combined to form a cost-risk net present value model, and the construction cost and the cross-fault-zone risk are evaluated synchronously.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of railway route selection, and particularly relates to a full-probability risk assessment method for railway route selection scheme crossing seismic faults. BACKGROUND

[0002] At present, some railways are planned and constructed in strong earthquake zones. For such key lifeline projects, various seismic activities (such as regional seismic motion, earthquake-induced landslides and active fault zones) will significantly threaten their service performance throughout their life cycle. Therefore, it is crucial to pay attention to seismic risk assessment at the initial stage of railway planning and design to reduce the impact of earthquakes on railway engineering infrastructure.

[0003] Route selection design is the core work of railway planning and design, and its main task is to determine the track geometric line position, infrastructure site selection and structure work point layout. However, due to the wide research area and complex topographic and geological conditions, the evaluation index is difficult to quantify, and there are multiple coupled constraint factors, so route selection design is also a very challenging work. The traditional manual design method is time-consuming and laborious, and may ignore a large number of potential high-quality schemes due to limited time and resources. To solve these problems, computer-aided railway line optimization has attracted widespread attention from global researchers.

[0004] However, the risk avoidance research of railway route selection in strong earthquake zones is still in the initial stage, and few studies consider the post-earthquake displacement risk when the railway crosses the active fault zone. Ideally, lifeline projects should avoid active fault zones, but in areas where faults are widely distributed, it is often difficult to achieve, and only reasonable line position and structure form can be used to cross the fault zone, at which time the railway line crossing the fault is threatened by the risk of earthquake displacement.

[0005] Therefore, the current railway route selection design research still has deficiencies in the risk assessment of crossing the fault, and it is necessary to establish a risk assessment system for railway lines crossing the fault. SUMMARY

[0006] The main purpose of the present application is to provide a full-probability risk assessment method for railway route selection scheme crossing seismic faults, which aims to solve the problem that the prior art cannot effectively evaluate the displacement risk when the railway crosses the active fault zone in the strong earthquake zone.

[0007] To achieve the above purpose, the present application provides a full-probability risk assessment method for railway route selection scheme crossing seismic faults, comprising the following steps: Step S1, obtaining a railway route selection scheme; obtaining the number M of fault zones contained in each railway route selection scheme; judging the type of each fault zone, the type of the fault zone including a main fault zone and a secondary fault zone; Step S2, numbering each fault-line intersection point in the railway route selection scheme , =1,2,3,…,M; Step S3, for the first Perform fault zone displacement probability hazard analysis at each fault-line intersection point and generate its displacement hazard curve; Step S4: Establish and simulate a full probability risk analysis model for crossing fault zones using Monte Carlo simulation, suitable for railway alignment design. This includes: Step S4.1: Initialize the Monte Carlo iteration count. =1 and the series of PGD =1; Step S4.2: Determine the displacement input of the main fault zone, specifically: sample the third-level permanent ground displacement PGD exceeding the set probability from the disaster curve obtained in step S3; and then... The fault zone displacement value of the PGD level is input into the probabilistic vulnerability analysis model of railway structures to calculate the probability of the structure being in different damage states. The displacement input for determining secondary fault zones specifically involves: searching for existing line-fault zone intersections; calculating and obtaining the average displacements of all secondary fault zones near the main fault zone under three types of earthquakes: frequent, occasional, and rare; and then... The average displacement value of the fracture zone of the PGD level is input into the probabilistic vulnerability analysis model of railway structures to calculate the probability of the structure being in different damage states. Step S4.3: Combine the probability of the structure being in different damage states to obtain the probabilistic economic loss analysis after the railway is interrupted. The probabilistic economic loss analysis after the railway is interrupted includes: randomly obtaining the damage ratio and recovery time of the structure according to the probability distribution form, determining the reconstruction length of the line after the interruption and calculating the direct repair loss. Step S4.4, take = +1, perform a judgment, if If it is less than or equal to K, then return to step S4.2; if If the count is greater than K, proceed to the next step; K is the maximum count value for the set iteration. Step S4.3, take = +1, perform a judgment, if If it is greater than 3, proceed to the next step; if If the value is less than or equal to 3, return to step S4.2; Step S5: Calculate the theoretical annual exceedance probability of the loss value based on the economic loss analysis of the railway failure probability obtained in S4. Step S6: Estimate the final annual direct loss based on the theoretical exceedance probability of the loss value; Step S7, Take = +1, perform a judgment, if If it is greater than M, proceed to the next step; if If M is less than or equal to the value of the step S3, go to step S3; Step S8, aggregate all line-fault zone intersection risks to obtain the total annual loss of all fault zone intersections along the railway line; calculate the cost-risk net present value based on the total annual loss of all fault zone intersections along the railway line.

[0008] Preferably, the main fault zone and the secondary fault zone each comprise a normal fault, a reverse fault and a strike-slip fault.

[0009] Preferably, in step S4.2: sampling a tertiary permanent ground displacement PGD with a 63% / 10% / 2% exceedance probability in 50 years from the disaster curve; The value of 1 represents a frequent event, The value of 2 represents an occasional event, The value of 3 represents a rare event; different damage states include no damage, moderate and severe.

[0010] Preferably, the railway structure probability vulnerability analysis model comprises the following steps: ①, divide the railway line into three types of structure groups, namely bridges, tunnels and roadbed sections; ②, define the damage state when the tunnel and roadbed section cross the active fault zone; take PGD as the earthquake intensity index, and derive the following lognormal distribution vulnerability curve for different structure types and damage states: Wherein: represents the conditional probability that the damage state is greater than when PGD takes ; DS is the damage state, is the index of DS, 0 represents no damage, 1 represents moderate damage, 2 represents severe damage; is the median of the th DS; is the deviation of the th DS; is a specific value taken by PGD; ③, calculate the probability of the structure being in different damage states, as follows: Wherein: represents the probability of no damage state; represents the probability of moderate damage state;​​​​​ representing the probability of a severe damage state.

[0011] Preferably, the cost-risk net present value is calculated using the following formula To complete the evaluation of the individual route option: ; ; ; where: is the construction cost; is the total annual loss of all fault crossings along the railway; is the series present value factor; is the interest rate; is the time period considered for the seismic risk assessment; is the construction duration of the railway; is the lump sum present value factor; is the time.

[0012] The technical scheme of the present application has the following effects: The railway route selection scheme full-probability risk assessment method disclosed by the present application adopts Monte Carlo simulation to establish a full-probability risk analysis model suitable for railway route selection design, integrates fault zone displacement probability risk analysis, railway structure probability vulnerability analysis and railway fault zone probability economic loss analysis based on performance-based seismic engineering theory, can calculate the annual exceedance probability of a specific displacement value in combination with fault zone characteristics (position, geometric shape, seismic intensity), and can evaluate the damage state of different railway structures (tunnels, roadbed sections and the intersection of fault zones are mainly considered in the present application, because bridges are usually not used to cross fault zones) under the influence of fault displacement. Meanwhile, the full-probability risk analysis model and the cost minimization model are combined to form a cost-risk net present value model to simultaneously evaluate the construction cost and the risk of crossing the fault zone. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from the structures shown in the drawings without creative labor.

[0014] Figure 1 is the principle diagram of the railway route selection scheme full-probability risk assessment method in the embodiments of the present application; Figure 2This is a schematic diagram of fault zone types in an embodiment of the present invention, wherein: (a) represents fault types classified according to distance from the epicenter; (b) represents fault types classified according to fault mechanism; Figure 3 This is a schematic diagram of the vulnerability curves of structures related to permanent ground displacement in an embodiment of the present invention; Figure 4 This is a schematic diagram of the line repair length in an embodiment of the present invention, wherein: (a) represents a schematic diagram of the repair length of a straight line; (b) represents a schematic diagram of the repair length of a curved line. Figure 5 This is a schematic diagram of annual earthquake loss calculation in an embodiment of the present invention, wherein: (a) represents the fitted P cost (C) <c |pgd p (a) Curve graph; (b) represents the direct loss exceedance probability P. cost (C≥c | pgd) p (c) represents the annual exceedance probability curve of the fault zone displacement; (d) represents the annual direct loss integral curve.

[0015] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] This embodiment discloses a method for full probability risk assessment of railway route selection schemes crossing seismic faults, as detailed below. Figure 1 Specifically, it includes: Step S1: Obtain railway alignment schemes; obtain the number M of fault zones contained in each railway alignment scheme; determine the type of each fault zone, which includes primary fault zones and secondary fault zones. Step S2: Number each fault-track intersection in the railway alignment scheme. , =1,2,3,…,M; Step S3, for the first Perform fault zone displacement probability hazard analysis at each fault-line intersection point and generate its displacement hazard curve; Step S4: Establish and simulate a full probability risk analysis model for crossing fault zones using Monte Carlo simulation, suitable for railway alignment design. This includes: Step S4.1, initialize the iteration count of Monte Carlo = 1 and the order of PGD = 1 Step S4.2, determine the displacement input of the main fault zone, specifically: sample the third permanent ground displacement PGD beyond the set probability from the hazard curve obtained in step S3; input the fault zone displacement value of the first PGD into the probability vulnerability analysis model of the railway structure, to calculate the probability of the structure being in different damage states; Determine the displacement input of the secondary fault zone, specifically: search for the existing line-fault zone intersection points; calculate the average displacement of all secondary fault zones near the main fault zone under the frequent, occasional and rare earthquakes; input the fault zone average displacement value of the first PGD into the probability vulnerability analysis model of the railway structure, to calculate the probability of the structure being in different damage states; Step S4.3, obtain the railway post-disaster probability economic loss analysis by combining the probability of the structure being in different damage states, which includes: randomly obtaining the damage ratio and recovery time of the structure according to the probability distribution form, determining the post-disaster reconstruction length of the line and calculating the direct repair loss; Step S4.4, take + 1, and determine whether is less than or equal to K, and if so, return to step S4.2; if is greater than K, proceed to the next step; K is the set maximum iteration count value; Step S4.3, take + 1, and determine whether is greater than 3, and if so, proceed to the next step; if is less than or equal to 3, return to step S4.2; Step S5, calculate the loss value theoretical annual exceedance probability based on the railway post-disaster probability economic loss analysis obtained in S4; Step S6, estimate the final annual direct loss based on the loss value theoretical annual exceedance probability; Step S7, take + 1, and determine whether is greater than M, and if so, proceed to the next step; if is less than or equal to M, return to step S3; Step S8, aggregate all line-fault zone intersection point risks to obtain the total annual loss of all fault zone intersection points along the railway; calculate the cost-risk net present value based on the total annual loss of all fault zone intersection points along the railway.

[0018] In this embodiment, as​​​Figure 2 As shown in Fig. 2(a), the active fault zone can be divided into two categories according to the distance from the epicenter: the main fault zone (i.e., the main fault with the largest displacement near the epicenter) and the secondary fault zone (i.e., the secondary fault far from the epicenter and affected by the main fault). In addition, according to the different mechanisms, the main fault zone and the secondary fault zone can be further divided into normal fault, reverse fault and strike-slip fault. The specific classification is shown in Fig. 2(b). Figure 2 In the subsequent Monte Carlo simulation process, different types of faults will adopt different probability models.

[0019] In this embodiment, each fault-line intersection is numbered, and the fault zone displacement probability risk analysis is performed to provide probability input for Monte Carlo simulation. Initialize the count = 1, and perform fault zone displacement probability risk analysis. First, determine the specific structure of the first line-fault intersection (counted from the beginning to the end of the line), and then assume that the fault zone is the main fault zone, and perform fault zone displacement probability risk analysis to generate its displacement disaster curve.

[0020] The specific method of fault zone probability risk analysis is referred to the simplified but practical fault zone displacement probability risk analysis method developed by Melissianos et al. in 2024 based on large-scale statistical analysis, which is used for main fault zone displacement disaster modeling in the life line design stage (Melissianos, et al. 2024. Simplified but practical fault zone displacement probability hazard analysis for life line design stage. Earthquake Spectra, 40(3), 1027-1048). Melissianos, V.E., Vamvatsikos, D., Danciu, L., Basili, R. (2024). Design displacement for lifelines at fault crossings: the code- based approach for Europe. Bull Earthquake Eng 22, 2677-2720 ), and generate fault zone displacement probability risk analysis curve to describe different fault zone dislocation disaster levels in railway route design.

[0021] For the secondary fault zone, this embodiment refers to the research results of Rodriguez Padilla and Oskin (Rodriguez Padilla, et al. 2018. Fault rupture characteristics of the 2012 Mw 7.6 Baja California Sur, Mexico, earthquake. Journal of Geophysical Research: Solid Earth, 123(10), 8872-8896). Rodriguez Padilla, A. M., Oskin M. E. (2023). Displacement hazard from distributed ruptures in strike-slip earth-quakes, Bull. Seismol. Soc. Am. 113, 2730-2745.

[0022] In this embodiment, the displacement input of the main fault zone is determined. The third permanent ground displacement (PGD) with a 63% / 10% / 2% exceedance probability in 50 years is sampled from the generated disaster curve, respectively corresponding to the frequent, rare and rare earthquakes defined in the “China Seismic Parameter Zoning Map” (GB 18306-2015). Initialize the count = 1. Input the fault zone displacement value of the first level (1 = frequent, 2 = rare, 3 = rare) PGD into the railway structure probability vulnerability analysis model to calculate the probability of the structure being in different damage states (defined as DS, divided into no damage, moderate damage and severe damage).

[0023] The specific implementation method of railway structure probability vulnerability analysis is as follows:​ ① The railway line is divided into three structural groups: bridges, tunnels, and roadbed sections (including cut and fill). Because bridges are highly sensitive to seismic activity, railway line design typically prohibits bridges from crossing fault zones; therefore, this study does not consider bridge-fault zone intersection scenarios. Tunnels and roadbed sections will be addressed in subsequent steps.

[0024] ② Define the damage state when tunnels and roadbed sections cross active fault zones. Refer to the HAZUS report ( Federal Emergency Management Agency (2024). HAZUS earthquake model technical manual 6.1, Washington DC. Using PGD as an earthquake intensity index, the following log-normal distribution is derived for different structure types and damage states. Vulnerability curve: ; in: Indicates taking in PGD Damage state greater than The conditional probability; DS represents the damage state. For the index of DS, A value of 0 represents no damage. Let 1 represent moderate damage. A value of 2 represents severe damage; For the first The median of each DS; For the first The deviation of each DS; These are specific values ​​chosen for PGD. Curve parameters are shown in Table 1. Table 1. Vulnerability Curve Parameters for Tunnels and Earthwork Sections

[0025] ③ Using the fault zone displacement probability hazard analysis model, a Level III PGD (Probability of Exceedance) of 63% / 10% / 2% within 50 years was determined at the intersection of the railway line and the fault zone. For a specific PGD value (i.e., a set threshold value), [the following is a definition of PGD]. ).

[0026] Calculate the probability of a structure being in different damage states.

[0027] This implementation uses the following formula to calculate the first probability of a structure being in different DS (e.g., ...). Figure 3 (as shown) ; ; ; in: Represents the probability of a damage-free state; represent the probability of moderate damage state; represent the probability of severe damage state.

[0028] In this embodiment, the displacement of secondary fault zone is determined and incorporated into the Monte Carlo simulation framework. For all secondary fault zones near the main fault zone and intersecting with the railway line, the displacement risk is triggered by the activity of the main fault zone. Within 3km range along the small and large mileage directions from the intersection point, search for other line-fault zone intersection points as secondary fault zones. Then, according to the research results of Rodriguez Padilla and Oskin, the average displacement of secondary fault zone is calculated by the following formula : ; wherein: is the distance from the main fault zone to the railway line-secondary fault zone intersection point; β is the average displacement of the main fault zone; is the normalization constant (set to 1m in this embodiment); g is the calibration slope (generally taken as 0.41). Finally, the average displacement of the secondary fault zone near the main fault zone under the three average displacements of the main fault zone under the frequent, occasional and rare earthquakes is calculated. Finally, the first level (1=frequent, 2=occasional, 3=rare) PGD fault zone average displacement value is input into the railway structure probability vulnerability analysis model to calculate the probability of the structure being in different damage states (defined as DS, divided into no damage, moderate and severe).

[0029] Initialize the Monte Carlo single iteration count =1. Then, perform a Monte Carlo simulation random sampling to generate a uniformly distributed random number ω in [0,1] and compare it with the structure damage state probability to determine the specific damage state (DS).

[0030] In this embodiment, the probability economic loss analysis of railway after-break is carried out, specifically: According to the probability distribution form, the damage ratio and recovery time of the structure are randomly obtained (as shown in Table 2), and the Figure 4 line after-break reconstruction length is determined and the direct repair loss (L) is calculated. Let = + 1. At this point, the iteration of the inner Monte Carlo simulation is completed.

[0031] The implementation method of the probability economic loss analysis of railway after-break is as follows: ​The probability risk analysis model of fault zone displacement can be further associated with the probability of structural damage ratio (the ratio of structural repair cost) and recovery time (the time required for the railway function to fully recover from the fault zone rupture), to build a railway fault probability economic loss analysis model. The damage ratio and recovery time are shown in Table 2. Assuming that the damage ratio is randomly and uniformly distributed, and the recovery time is normally distributed.

[0032] Table 2 Structural damage ratio and repair time information

[0033] If the DS, damage ratio (D) and recovery days (T) of the structure are known, the seismic fault zone risk can be converted into annual monetary loss (L) by the following formula, including direct loss (Ld, related to structural repair) and indirect loss (Li, related to railway recovery): wherein: is the unit structural repair loss; is the length of the line section affected by the fault zone deformation; is the empirical daily income related to the length of railway operation; is the total length of the line. As shown in Figure 4 , the line reconstruction process when the line intersects with the fault zone in two ways (straight line or curve) can be simulated from a geometric point of view, which can be divided into two cases: Case 1: If the straight line section passes through the rupture fault zone, an S-shaped curve is needed to reconnect the local line to ensure the smoothness of train operation, as shown in Figure 4 (a), at this time, the length of the reconstructed line (Lr) is: wherein: is the length of the reconstructed circular curve (which needs to be greater than the minimum threshold lcmin); is the length of the reconstructed transition curve; is the radius of the reconstructed curve; is the minimum straight line length between adjacent circular curves; is the deflection angle; is the fault zone displacement.

[0034] By simple iterative enumeration, the appropriate Lr and D can be found to determine L. ​​​​​​​​​​​​​​

[0035] Scenario 2: If the curve segment crosses a fracture zone, the local track can be reconstructed more directly in two ways, such as... Figure 4 As shown in (b). The first method keeps the straight lines unchanged and directly adjusts the radius of the deformed circular curve to reconnect them; the second method keeps the radius of the circular arc unchanged and reconstructs the common tangent connecting them.

[0036] In this embodiment, the inner Monte Carlo simulation cycle repeatedly performs random sampling to generate a statistical sample. The above steps are repeated until... k>K ( K (Define iteration limits for the user), resulting in two sets of data including direct loss and recovery time. K Data from a sample. For example... Figure 5 As shown in (a), two log-normal probability distribution curves are arranged in ascending order and fitted (taking direct loss as an example, denoted as...). Completed for a single level. p Model the probability distribution of the risk loss. Let p=p +1.

[0037] In this embodiment, the outer Monte Carlo simulation loop iterates through each level. p until p >3, thus obtaining the set of log-normal probability distribution curves for direct losses and recovery time under common, occasional, and rare earthquakes. For example... Figure 5 As shown in (b), the transcendence probability corresponding to the third-level PGD can be calculated. .

[0038] In this embodiment, based on the following formula, the theoretical annual exceedance probability of loss values ​​is calculated by integrating all PGD hazard levels, and the Monte Carlo simulation results are probabilistically fused with the seismic hazard analysis: .

[0039] Further optimization, for engineering problems, only Level 3 PGD disasters (corresponding to common, occasional, and rare earthquakes) are considered, thus simplifying it to: ; in: The probability difference between two levels of hazards on the fault zone displacement probability hazard curve is detailed in [link to relevant documentation]. Figure 5 As shown in (c). Therefore, the exceedance probability curve of annual direct loss is as follows. Figure 5 As shown in (d).

[0040] In this embodiment, the final annual direct loss is estimated according to the following formula: ; in: G for Figure 5The number of segments of the abscissa in (d) is defined by the route designer. Similarly, the annual recovery time of the same structure is obtained.

[0041] In this embodiment, the risk of all line-fault zone intersections is summarized. Until >M ( M After determining the fault zone displacement and the length of the line reconstruction caused by the fault zone displacement, the repair cost of the structure is estimated according to the given DS, damage ratio and recovery days. Further, the total annual loss of all fault zone intersections along the railway line (C) is: ; Wherein: N is the number of line-fault zone intersections. This formula sums up the direct loss of structure repair; but based on the assumption that rescue personnel and resources are sufficient after the earthquake, the indirect loss only takes the maximum repair time value in the line-fault zone intersection, that is, the railway closing time only depends on the maximum repair time of all fault zone sections.

[0042] In this embodiment, the cost-risk net present value is calculated to complete the evaluation of a single line scheme. That is, the direct basis for judging the pros and cons of the scheme, the smaller the cost-risk net present value, the better the railway route selection scheme. The cost-risk net present value (C) of the final fault zone full probability risk analysis model is the target function: ; ; ; Wherein: is the construction cost; is the construction period of the railway; is the time period considered in the earthquake risk assessment; is the interest rate; is the series present value coefficient; is the single payment present value coefficient; is the time.

[0043] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made under the inventive concept of the present application, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.​​

Claims

1. A method for full probability risk assessment of railway route selection schemes crossing seismic faults, characterized in that, Comprising the following steps: Step S1, obtaining railway route selection schemes; obtaining the number M of fault zones contained in each railway route selection scheme; judging the types of each fault zone, the types of fault zones including main fault zones and secondary fault zones; Step S2, numbering each fault-line intersection point in the railway route selection scheme , =1,2,3,…,M; Step S3, performing a fault zone displacement probability risk analysis on the first fault-line intersection point to generate a displacement disaster curve thereof; Step S4, establishing a full-probability risk analysis model suitable for railway route selection design across fault zones by Monte Carlo simulation and performing simulation, specifically comprising: Step S4.1, initialization of the iteration count of the Monte Carlo = 1 and the order of the PGD = 1; Step S4.2, determining the displacement input of the main fault zone, specifically: sampling the third level permanent ground displacement PGD that exceeds the set probability from the disaster curve obtained in step S3; inputting the fault zone displacement value of the third level PGD into the railway structure probabilistic vulnerability analysis model to calculate the probability of the structure being in different damage states. Step S4.2, determining the displacement input of the main fault zone, specifically: sampling the third level permanent ground displacement PGD that exceeds the set probability from the disaster curve obtained in step S3; inputting the fault zone displacement value of the third level PGD into the railway structure probabilistic vulnerability analysis model to calculate the probability of the structure being in different damage states. The displacement input of the secondary fault zone is determined, specifically: searching for the existing line-fault zone intersection points; calculating the average displacement of all secondary fault zones near the main fault zone under the three levels of average, occasional and rare earthquakes; inputting the average displacement value of the first level PGD fault zone into the railway structure probability vulnerability analysis model to calculate the probability of the structure being in different damage states. The displacement input of the secondary fault zone is determined, specifically: searching for the existing line-fault zone intersection points; calculating the average displacement of all secondary fault zones near the main fault zone under the three levels of average, occasional and rare earthquakes; inputting the average displacement value of the first level PGD fault zone into the railway structure probability vulnerability analysis model to calculate the probability of the structure being in different damage states. Step S4.3, obtaining railway post-fault probability economic loss analysis in combination with the probability of structures being in different damage states, the railway post-fault probability economic loss analysis comprising: randomly obtaining the damage ratio and recovery time of structures according to the probability distribution form, determining the post-fault reconstruction length of the line and calculating the direct repair loss; Step S4.4, take = +1, make a decision, if is less than or equal to K, return to step S4.2; if is greater than K, go to the next step; K is a set maximum iteration count value; Step S4.3, take = +1, make a decision, if is greater than 3, go to next step; if is less than or equal to 3, return to step S4.2; Step S5, calculating the loss value theoretical annual exceedance probability based on the railway post-fault probability economic loss analysis obtained in S4; Step S6, estimating the final annual direct loss based on the loss value theoretical annual exceedance probability; Step S7, take = +1, make a decision, if greater than M, go to the next step; if less than or equal to M, return to step S3; Step S8, summarizing the risks of all line-fault zone intersections to obtain the total annual loss of all fault zone intersections along the railway; calculating the cost-risk net present value based on the total annual loss of all fault zone intersections along the railway.

2. The all-probability risk assessment method for railway route selection schemes crossing a seismic fault of claim 1, wherein, Both the main fault zone and the secondary fault zone contain normal faults, reverse faults and strike-slip faults.

3. The all-probability risk assessment method for railway route selection plans to cross a seismic fault of claim 1, wherein, In step S4.2: sampling from the hazard curve the three levels of permanent ground displacement PGD with exceedance probabilities of 63% / 10% / 2% in 50 years; Value 1 represents a frequent event, Value 2 represents an occasional event, Value 3 represents a rare event; different damage states include no damage, moderate and severe.

4. The all-probability risk assessment method for railway route selection schemes crossing a seismic fault of claim 3, wherein, The railway structure probability vulnerability analysis model comprises the following steps: ①, dividing the railway line into three types of structure groups, namely bridges, tunnels and roadbed sections; ②, Define the damage state of tunnel and embankment section when crossing active fault zone; Take PGD as the seismic intensity index, and derive the following lognormal distribution vulnerability curves for different structure types and damage states: ​ ； in: Indicates taking in PGD Damage state greater than The conditional probability; DS represents the damage state. For the index of DS, A value of 0 represents no damage. Let 1 represent moderate damage. A value of 2 represents severe damage; For the first The median of each DS; For the first The deviation of each DS; A specific value taken by PGD; ③, calculating the probability of structures being in different damage states.

5. The all-probability risk assessment method for railway route selection schemes crossing a seismic fault of claim 4, wherein, The probability of structures being in different damage states is calculated as follows: ； ； ； wherein: represents the probability of the state of no injury; represents the probability of the state of moderate injury; represents the probability of the state of severe injury.

6. The all-probability risk assessment method for railway route selection plans to cross a seismic fault of claim 1, wherein, The cost-risk net present value is calculated by the following formula to complete the evaluation of a single line scheme: ； ； ； where: is the construction cost; is the total annual loss for all fault crossings along the railway; is the series present value factor; is the interest rate; is the time period considered for the seismic risk assessment; is the railway construction duration; is the single payment present value factor; is the time.

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