Establishment method of urban gas network seismic resilience curve based on monte carlo simulation

Abstract

The application discloses a method for establishing urban gas pipe network seismic resilience curve based on Monte Carlo simulation, comprising the following steps: establishing a ground motion prediction equation; obtaining urban gas pipe network basic data, and predicting the ground motion parameters of the urban gas pipe network; sampling the ground motion parameters of the urban gas pipe network based on Monte Carlo simulation, and calculating the failure probability of each station and the failure probability of each pipeline in the urban gas pipe network; determining whether each station fails; determining the number of damage points on each failed pipeline, randomly distributing damage types to each damage point, and generating a damaged network of the gas pipe network; simulating the repair process of the damaged network of the gas pipe network, and obtaining the resilience curve of different properties of the gas pipe network changing with time. The application is used for solving the problem that the recovery effect of the urban gas pipe network after an earthquake is difficult to be quantified and evaluated in the prior art, and can form a complete urban gas pipe network seismic resilience quantification and evaluation process, so that the urban gas pipe network seismic resilience can be more comprehensively evaluated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of urban gas pipeline network seismic performance research, and particularly relates to a method for establishing an urban gas pipeline network seismic toughness curve based on Monte Carlo simulation. BACKGROUND

[0002] The increase in natural gas production and the continuous construction of urban gas pipeline networks have led to an increase in gas usage, accompanied by safety problems in natural gas transportation. The urban gas pipeline network system is the main component of natural gas transmission and distribution, and therefore, the safe operation of the urban gas pipeline network is one of the important components of energy security. Earthquakes have a particularly prominent impact on urban gas pipeline networks, and earthquakes have the characteristics of suddenness, unpredictability, wide influence, great destructive power, and derivativeness. Earthquake factors were not fully considered in early urban planning, and therefore, the gas pipeline network is vulnerable to earthquakes, which threatens the safety and stability of the city. In the face of such random and destructive natural disasters as earthquakes, passive post-earthquake management alone cannot effectively reduce the damage caused by earthquakes, and the level of emergency response and post-earthquake rescue capabilities need to be improved. Therefore, the study of the seismic toughness of urban gas pipeline networks aims to strengthen the seismic design and emergency response capabilities of the pipeline network, improve its response and recovery capabilities in disasters such as earthquakes, and thus ensure a safe gas environment for urban residents.

[0003] The seismic toughness of the urban gas pipeline network can be defined as the ability of the gas pipeline network system to maintain or quickly restore user gas functions under seismic disturbance, and the adaptability in the face of uncertainty at each stage. In the prior art, the main method for studying the seismic toughness of the urban gas pipeline network is mainly focused on building a toughness evaluation system or a toughness theoretical research framework. However, these methods generally have a certain subjectivity, the stage characteristics are not prominent, the consideration of the interaction of multiple factors is weak, and the uncertainty of disasters cannot be effectively handled.

[0004] The toughness curve is a manifestation of the quantitative and visual development of system toughness measurement, and can show the whole process of the response-recovery of the pipeline network system from the occurrence to the end of the disturbance. The degree of decline, the degree of rise, and the process time of the curve respectively reflect the vulnerability, resilience, and robustness of the pipeline network system, and the impact of the disturbance can be evaluated by comparing with the system function baseline. However, there is no comprehensive and effective method for establishing the seismic toughness curve of the urban gas pipeline network in the prior art, and it is difficult to quantify and evaluate the recovery effect of the urban gas pipeline network after an earthquake. SUMMARY

[0005] The application provides a method for establishing an urban gas pipeline network seismic resilience curve based on Monte Carlo simulation, to solve the problem that there is no comprehensive and effective method for establishing an urban gas pipeline network seismic resilience curve in the prior art, and it is difficult to quantify and evaluate the recovery effect of the urban gas pipeline network after an earthquake, so as to realize a complete urban gas pipeline network seismic resilience quantitative evaluation process, and more comprehensively evaluate the urban gas pipeline network seismic resilience.

[0006] The application is realized by the following technical solutions:

[0007] The method for establishing an urban gas pipeline network seismic resilience curve based on Monte Carlo simulation comprises the following steps:

[0008] S1, establishing an earthquake motion prediction equation under different earthquake magnitudes and site conditions;

[0009] S2, obtaining urban gas pipeline network basic data, selecting a matching earthquake motion prediction equation, and predicting the earthquake motion parameters of the urban gas pipeline network;

[0010] S3, randomly sampling the earthquake motion parameters of the urban gas pipeline network based on Monte Carlo simulation, and calculating the failure probability of each station and the failure probability of each pipeline in the urban gas pipeline network;

[0011] S4, determining whether each station fails;

[0012] S5, determining the number of damage points on each failed pipeline, randomly assigning damage types to each damage point, and generating a damaged gas pipeline network;

[0013] S6, simulating the repair process of the damaged gas pipeline network, and obtaining the resilience curve of different properties of the gas pipeline network changing over time.

[0014] In view of the problem that there is no comprehensive and effective method for establishing an urban gas pipeline network seismic resilience curve in the prior art, and it is difficult to quantify and evaluate the recovery effect of the urban gas pipeline network after an earthquake, the application provides a method for establishing an urban gas pipeline network seismic resilience curve based on Monte Carlo simulation. This method first establishes an earthquake motion prediction equation under different earthquake magnitudes and site conditions for standby use. When it is necessary to establish the seismic resilience curve of a specified gas pipeline network, the basic data thereof is obtained, a matching earthquake motion prediction equation is selected, and the earthquake motion parameters of the urban gas pipeline network are predicted based on the earthquake motion prediction equation. Then, the earthquake motion parameters of the urban gas pipeline network are randomly sampled based on Monte Carlo simulation.

[0015] The town gas pipe network is not only composed of a network of pipes / pipelines, but also includes some door stations which play a role of pressure regulation in the pipe network, and the pipelines and the door stations are important nodes and edge units in the whole system, therefore, the door stations and the pipelines are divided into two parts as important components of the town gas pipe network for analysis. Specifically, according to the sampling results of the ground motion parameters, the failure probability of each door station in the town gas pipe network and the failure probability of the pipeline are calculated; for the door station, it is directly determined whether each door station fails; for the pipeline, the number of damage points on each failed pipeline is first determined, and then the damage types are randomly assigned to each damage point to generate a damaged network of the gas pipe network. Thus, the equivalent model of the seismic damage failure probability of the town gas pipe network can be obtained, and on this basis, the repair process of the damaged network of the gas pipe network is simulated to obtain the resilience curve of the gas pipe network with different properties changing over time.

[0016] The present application solves the problem that it is difficult to comprehensively and effectively establish the seismic resilience curve of the town gas pipe network, and it is difficult to quantify and evaluate the recovery effect of the town gas pipe network after an earthquake, and provides a complete process for quantifying the seismic resilience of the town gas pipe network, which is beneficial to more comprehensively evaluate the seismic resilience of the town gas pipe network and is beneficial to prepare targeted earthquake disaster measures and plans for the town gas pipe network.

[0017] Further, the ground motion prediction equation is:

[0018] lgY=C1+C2·M w +C3·M w 2 +C4lg[R+C5·exp(C6·M w )]+ε;

[0019] In the formula, Y is a target ground motion parameter; M w is a moment magnitude; R is an epicentral distance; C1, C2, C3, C4, C5 and C6 are all constants; and ε is an uncertainty random variable obeying a normal distribution with a mean of 0 and a standard deviation of σlg(Y), wherein σ is the mean square error of the overall sample.

[0020] In the ground motion prediction equation of the present application, the moment magnitude M w is used as an input, compared with the surface wave magnitude which is most commonly used, the relationship between the moment magnitude and the seismic physical process is more direct, which is beneficial to reduce the probability of occurrence of the magnitude saturation effect, and thus improve the prediction accuracy of the ground motion parameter.

[0021] Further, the ground motion parameter includes: a peak ground acceleration PGA, a peak ground velocity PGV and a permanent ground displacement PGD.

[0022] The peak ground acceleration (PGA) is a core parameter that determines the extent of damage to the gas pipeline network during an earthquake. It represents the maximum acceleration of the seismic wave as it travels to the ground and directly reflects the instantaneous force on the ground structure. A higher PGA means stronger seismic forces, so the gas pipeline network is more likely to rupture and lose stability. Therefore, the size of the PGA directly affects the vulnerability of the gas pipeline network during the epicenter phase, and is an important basis for assessing the extent of damage. Therefore, PGA is one of the necessary ground motion parameters in this scheme.

[0023] The peak ground velocity (PGV) reflects the propagation velocity of the seismic wave and is an important parameter for determining the extent of damage to the gas pipeline network during the epicenter phase. PGV not only affects physical damage, but also determines the size of the damaged area and the difficulty of repair, so it is crucial in the resilience assessment and is one of the necessary ground motion parameters in this scheme.

[0024] This scheme also introduces the permanent ground displacement (PGD) as one of the necessary ground motion parameters, which can be used as a key parameter to reflect the stability of gas supply and plays an important role in subsequent calculation of failure probability.

[0025] Further, the gate station failure probability is calculated by the following formula:

[0026] P 门站 =1-(1-P 储气罐 )×(1-P 计量调压间 );

[0027]

[0028] In the formula: P 门站 is the gate station failure probability; P 储气罐 is the facility failure probability of the gas storage tank; P 储气罐 is the facility failure probability of the metering and pressure regulating room; and PGA is the peak ground acceleration.

[0029] This scheme uses PGA as the ground motion parameter to control the failure of the gas gate station. As a parameter to describe the intensity of an earthquake, PGA directly reflects the maximum acceleration of the ground at the moment of seismic action, and has intuitive and easy-to-obtain properties. Therefore, using PGA as the control parameter for gate station failure helps to more accurately characterize the direct impact of ground motion on the structure of the gate station. This scheme divides the gate station failure into two working conditions: gas storage tank failure and metering and pressure regulating room failure, which can quickly quantify the failure probability of the gate station.

[0030] Further, the pipeline failure probability is calculated by the following formula:

[0031] P 管线 =1-(1-P f1 )·(1-P f2 );

[0032]

[0033] R f1 =0.002416×PGV×K1;

[0034] R f2 =2.5829×PGD 0.319 ×K2;

[0035] In the formula: P 管线 P represents the pipeline failure probability. f1 P represents the probability of connection failure due to uncertainty. f2 The gas supply uncertainty failure probability; L is the pipeline length; R f1 The average damage rate due to uncertainties in connectivity; R f2 1 represents the average seismic damage rate due to gas supply uncertainty; PGV represents peak seismic velocity; PGD represents permanent ground displacement; K1 is an adjustment factor related to PGV; and K2 is an adjustment factor related to PGD.

[0036] During their research, the inventors discovered that seismic waves propagate from the epicenter to the surface soil, causing ground deformation. This deformation, in turn, causes pipeline movement, which can lead to pipeline damage. Two scenarios emerge: first, pipeline damage due to ground motion deformation. In this case, PGV (Precipitation Gas Velocity) significantly impacts gas pipelines because it directly reflects changes in ground velocity caused by seismic wave propagation. Greater ground vibration amplitude results in stronger stress and strain on the gas pipeline, increasing the risk of damage. Second, pipeline damage can also occur due to permanent ground displacement caused by earthquakes, such as faults, soil liquefaction, and subsidence. In this case, PGD (Precipitation Gas Degradation) has a more significant impact, subjecting the gas pipeline to greater displacement and shear forces. Therefore, relying solely on PGV to describe the uncertainty of gas pipeline failure using traditional techniques has significant limitations in this application, failing to fully reflect the pipeline damage mechanism caused by earthquakes.

[0037] Based on the above research process, this scheme creatively introduces permanent ground displacement (PGD) as one of the key parameters affecting pipeline failure probability, and combines it with peak seismic velocity (PGV). Starting from both connectivity uncertainty and gas supply uncertainty, a brand-new method for calculating the pipeline failure probability of urban gas pipeline networks is constructed, which significantly improves the accuracy of pipeline failure probability calculation.

[0038] Considering that the gate station facility contains pressure regulating equipment, metering equipment, safety valves, filters and other key equipment, the bearing capacity, damage mode and recovery time of different equipment under earthquake action are quite different, which makes the overall failure of the gate station show strong uncertainty. If each device is modeled separately and its seismic performance, failure probability and recovery process are considered, the calculation process will be extremely complex, not only a large amount of equipment seismic damage data is needed as support, but also a multi-level, multi-variable probability model needs to be established, and the calculation amount increases significantly, thereby reducing the evaluation efficiency. In order to reduce the calculation complexity and reasonably represent the overall failure probability of the gate station under the condition of limited data, the failure judgment mode of the gate station is simplified, and it is assumed that the failure of the gate station obeys the uniform distribution of 0-1, thereby significantly reducing the difficulty of judging the failure of the gate station and improving the evaluation efficiency.

[0039] Further, the method for judging whether each gate station fails comprises:

[0040] A judgment value r is randomly generated in the interval of 0-1 for each gate station, and r is compared with the gate station failure probability of the gate station:

[0041] If r is less than the gate station failure probability, it is judged that the gate station fails;

[0042] If r is greater than or equal to the gate station failure probability, it is judged that the gate station operates normally.

[0043] The pipeline damage caused by the earthquake may have multiple damage points in a single pipeline, and the damage form of each damage point may be different. In analyzing the influence of the earthquake on the gas pipeline damage, the pipeline may appear bending deformation in some cases, but can still maintain gas supply. Although such cases may have some impact on the mechanical properties of the pipeline, they will not directly affect the gas supply function. Since this scheme mainly focuses on the influence of the connectivity of the pipeline on the user's gas use, only two failure types of leakage and rupture are considered. The damage of the pipeline in the earthquake is affected by many factors, and the complexity of the factors makes it difficult to accurately predict the specific damage form of the pipeline through a single deterministic method, so a random allocation method can reasonably reflect the random influence of the earthquake on the pipeline.

[0044] Further, the method for determining the number of damage points on each failed pipeline comprises:

[0045] S501, screening the pipelines whose failure probability is greater than a set threshold, defined as possible failure pipelines;

[0046] S502, calculating the average distance D of damage points of the possible failure pipelines i :

[0047]

[0048] In the formula, U is a random variable obeying the uniform distribution of 0-1; Rimax is the maximum value in R f1 , R f2 ; i represents the i-th possible failure pipeline;

[0049] S503, judging whether each possible failure pipeline is damaged or not:

[0050] If L i > D i , the i-th possible failure pipeline is intact;

[0051] If L i ≤ D i , the i-th possible failure pipeline is damaged;

[0052] wherein, L i is the length of the i-th possible failure pipeline;

[0053] S504, calculating the number H i of damaged points of the damaged possible failure pipeline: H i = L i / D i .

[0054] When the failure probability of the pipeline to be solved is greater than the set threshold value, i.e. the damage level of the pipeline reaches the serious damage and destruction, the possibility of pipeline failure is great, which needs to be focused on. The present scheme determines the number of damaged points of these pipelines which need to be focused on, so as to facilitate the random allocation of damage forms in the later period.

[0055] Further, the method for simulating the repair process of the damaged gas pipeline network comprises:

[0056] S601, fixing the repair time of the gate station as 3 days, and repairing the failure gate station;

[0057] S602, determining the respective repair time of each pipeline damage type as leakage and rupture;

[0058] S603, using a random function to generate the repair sequence of each damaged possible failure pipeline, sampling and assigning the repair time, and repairing each damaged possible failure pipeline;

[0059] S604, judging whether the repair of the damaged gas pipeline network is completed or not; if not, returning to step S5 to randomly allocate the damage type to each damaged point.

[0060] The uncertainty of the repair of the urban gas pipeline network makes it difficult to develop and implement the repair plan, and the repair time and effect are more difficult to predict, thereby affecting the overall recovery progress and efficiency of the gas supply system. According to the historical records of the gas station under the earthquake in China, it is set that the repair of the station needs 3 days. For the failed pipeline, the normal distribution model is adopted to randomly sample and simulate the post-earthquake pipeline repair time, which is more in line with the repair rules.

[0061] Further, the method for obtaining the resilience curve of the different attributes of the gas pipeline network changing over time comprises:

[0062] S605, determining the seismic resilience attribute parameters of the gas pipeline network; the seismic resilience attribute parameters comprise technical attributes, organizational attributes, social attributes and economic attributes;

[0063] S606, respectively establishing a technical attribute resilience curve, an organizational attribute resilience curve, a social attribute resilience curve and an economic attribute resilience curve.

[0064] The urban gas pipeline network is not only affected by the characteristics of the pipeline network itself and the earthquake, but also related to the way of human intervention. It is difficult to fully reflect the recovery capacity using a single attribute, and the evaluation results obtained by different attributes may be inconsistent or even contradictory. Therefore, this scheme comprehensively and efficiently quantitatively evaluates the multi-attribute resilience of the urban gas pipeline network in the disturbed, responsive and recovery stages from the aspects of organization, technology, society and economy. Among them, the technical attribute reflects the change process of the physical performance of the gas pipeline network unit, which is the core of the seismic resilience of the gas pipeline network; the organizational attribute reflects the emergency response capability and resource scheduling efficiency of the gas pipeline network in the earthquake disaster; the social attribute reflects the influence of the gas pipeline network as a social infrastructure on the population and social function; and the economic attribute reflects the economic loss of the gas pipeline network in the earthquake disaster and its ability to restore economic balance.

[0065] Further, it further comprises:

[0066] S7, calculating the seismic resilience index based on the resilience curve:

[0067] TRT=t k -t0;

[0068]

[0069] In the formula: TRT is the recovery time; t k is the time when the gas pipeline network is completely recovered; t0 is the time when the gas pipeline network starts to be repaired;

[0070] SRT is the recovery trajectory centroid; Q(t) represents the resilience curve; and Δt represents the time interval.

[0071] ​​​​​​​​​​​Re is the network redundancy degree; Q(T)2 represents the post-earthquake performance of the organizational attribute of the gas pipeline network; Q(T)1 represents the post-earthquake performance of the technical attribute of the gas pipeline network;

[0072] R is the recovery force; N(t) is the performance evaluation index of the corresponding seismic resilience attribute parameter at time t when the gas pipeline network is in normal operation; N is the number of simulations.

[0073] The seismic resilience curve of the urban gas pipeline network can visualize the resilience level of the pipeline network, but its quantitative degree still needs to be improved. In order to better quantify the seismic resilience of the urban gas pipeline network, the corresponding seismic resilience indicators are analyzed in this scheme.

[0074] Among them:

[0075] The recovery time TRT is used to quantify the length of time of the recovery performance of the urban gas pipeline network, which is related to the recovery time of the seismic resilience influencing factors, that is, the time span of the recovery process. The smaller the TRT value, the shorter the system recovery time, reflecting the rapid recovery ability of the gas pipeline network after the disaster; the larger the TRT value, the longer the recovery process of the system, indicating that the recovery ability is weak. Through the analysis of TRT, the recovery speed of the system under different seismic conditions and its influencing factors can be identified.

[0076] The recovery trajectory centroid SRT can be understood as the centroid position of the area below the corresponding resilience curve, aiming to reflect the recovery efficiency of the system. SRT is closely related to the process variables reflecting the recovery performance of the pipeline network, such as gas supply capacity, repair speed and quality, etc. When the recovery time (TRT) is consistent, the larger the SRT value, the lower the repair efficiency of the system in the recovery process; on the contrary, the smaller the SRT value, the higher the performance recovery efficiency of the system. SRT can provide quantitative analysis of the efficiency performance of the system during the post-earthquake recovery period, facilitating the comparison of the recovery effectiveness of different strategies.

[0077] The redundancy degree Re can be understood as the ratio of the post-earthquake performance indicators of the organizational attribute and the technical attribute, which is used to quantify the advantages and disadvantages of the network structure of the urban gas system under the given seismic conditions. This index is closely related to the density of the gas pipeline network and the rationality of the pipeline network layout. The higher the Re value, the more excellent the structural performance of the network, the stronger the stability and impact resistance of the system in the earthquake, thereby helping to enhance the overall resilience of the system.

[0078] The recovery force R is used to comprehensively measure the seismic capacity and recovery capacity of the gas pipeline network. The larger the R value, the stronger the seismic resilience of the gas system, which can better cope with the earthquake impact and recover to the pre-earthquake state. The recovery force R can provide key guidance for the optimization design and emergency management of the gas system.

[0079] The scheme takes the epicenter and the gas pipe network density after the earthquake stage, the pipe network arrangement rationality, the gas regulation and supply capacity, the repair speed and quality, the recovery time and other factors as the core influence indexes, quantifies the key characteristics of the system, establishes four anti-seismic toughness evaluation indexes of recovery time (TRT), shape center of recovery track (SRT), redundancy degree (Re) and recovery force (R) through analysis, and provides data support for the anti-seismic design and improvement of the urban gas pipe network.

[0080] Compared with the prior art, the present application has at least the following advantages and beneficial effects:

[0081] 1. The urban gas pipe network anti-seismic toughness curve establishment method based on Monte Carlo simulation solves the problems that it is difficult to comprehensively and effectively establish the urban gas pipe network anti-seismic toughness curve, and it is difficult to quantify and evaluate the recovery effect of the urban gas pipe network after the earthquake, provides a complete urban gas pipe network anti-seismic toughness quantification process, and is beneficial to more comprehensively evaluate the urban gas pipe network anti-seismic toughness and prepare targeted earthquake disaster measures and plans for the urban gas pipe network.

[0082] 2. The urban gas pipe network anti-seismic toughness curve establishment method based on Monte Carlo simulation introduces permanent ground displacement (PGD) as one of the key parameters affecting the pipeline failure probability, and combines it with peak ground velocity (PGV), constructs a new pipeline failure probability calculation method of the urban gas pipe network from the aspects of connectivity uncertainty and gas supply uncertainty, and significantly improves the calculation accuracy of the pipeline failure probability.

[0083] 3. The urban gas pipe network anti-seismic toughness curve establishment method based on Monte Carlo simulation comprehensively and efficiently quantitatively evaluates the multi-attribute toughness of the urban gas pipe network in the disturbed, response and recovery stages from the aspects of organization, technology, society and economy.

[0084] 4. The urban gas pipe network anti-seismic toughness curve establishment method based on Monte Carlo simulation establishes four anti-seismic toughness evaluation indexes of recovery time, track shape center, redundancy degree and recovery force, and provides data support for the anti-seismic design and improvement of the urban gas pipe network. DETAILED DESCRIPTION

[0085] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0086] Figure 1 It is a flowchart of the specific embodiment of the present application;

[0087] Figure 2 It is a simplified diagram of the urban gas pipe network in the specific embodiment of the present application;

[0088] Figure 3 This is a schematic diagram illustrating the post-earthquake performance of an urban gas pipeline network in a specific embodiment of the present invention.

[0089] Figure 4 The toughness curve is a technical attribute in a specific embodiment of the present invention.

[0090] Figure 5 This refers to the tissue toughness curve in a specific embodiment of the present invention;

[0091] Figure 6 This is a social attribute resilience curve in a specific embodiment of the present invention;

[0092] Figure 7 This is the economic attribute resilience curve in a specific embodiment of the present invention. Detailed Implementation

[0093] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explaining the invention only and are not intended to limit the invention. In the description of this application, it should be understood that terms such as "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "high," "low," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application.

[0094] Example 1:

[0095] like Figure 1 The method for establishing the seismic toughness curve of urban gas pipeline networks based on Monte Carlo simulation, as shown, includes the following steps:

[0096] S1. Establish seismic motion prediction equations under different magnitudes and site conditions:

[0097] lgY=C1+C2·M w +C3·M w 2 +C4lg[R+C5·exp(C6·M w )]+ε;

[0098] In the formula: Y represents the target ground motion parameter; M w R is the moment magnitude; C1, C2, C3, C4, C5, and C6 are all constants; ε is an uncertain random variable that follows a normal distribution with a mean of 0 and a standard deviation of σlg(Y), where σ is the root mean square of the population sample.

[0099] S2, acquire the basic data of the urban gas pipeline network, select a matching ground motion prediction equation, and predict the ground motion parameters of the urban gas pipeline network. The ground motion parameters include: peak ground acceleration PGA, peak ground velocity PGV and permanent ground displacement PGD.

[0100] S3, based on Monte Carlo simulation, randomly sample the ground motion parameters of the urban gas pipeline network, and calculate the failure probability of each gate station and the failure probability of the pipeline in the urban gas pipeline network.

[0101] Wherein, the failure probability of the gate station is calculated by the following formula:

[0102] P 门站 =1-(1-P 储气罐 )×(1-P 计量调压间 );

[0103]

[0104] In the formula: P 门站 is the failure probability of the gate station; P 储气罐 is the facility failure probability of the gas storage tank; P 储气罐 is the facility failure probability of the metering and pressure regulating room; PGA is the peak ground acceleration.

[0105] Wherein, the failure probability of the pipeline is calculated by the following formula:

[0106] P 管线 =1-(1-P f1 )·(1-P f2 );

[0107]

[0108] R f1 =0.002416×PGV×K1;

[0109] R f2 =2.5829×PGD 0.319 ×K2;

[0110] In the formula: P 管线 is the failure probability of the pipeline; P f1 is the failure probability of the connection uncertainty; P f2 is the failure probability of the gas supply uncertainty; L is the length of the pipeline; R f1 is the average seismic damage rate of the connection uncertainty; R f2 is the average seismic damage rate of the gas supply uncertainty; PGV is the peak ground velocity; PGD is the permanent ground displacement; K1 is the adjustment coefficient related to PGV; K2 is the adjustment coefficient related to PGD.

[0111] S4, determining whether each gate station is failure:

[0112] For each gate station, a random value r is generated in the interval of 0-1, and r is compared with the gate station failure probability of the gate station:

[0113] If r < gate station failure probability, it is determined that the gate station is failure;

[0114] If r ≥ gate station failure probability, it is determined that the gate station is normal operation.

[0115] S5, determine the number of damaged points on each failure pipeline:

[0116] Screen the pipelines with failure probability greater than the set threshold value, and define them as possible failure pipelines; the set threshold value in this embodiment is 0.75;

[0117] Calculate the average distance D of damaged points of the possible failure pipelines i :

[0118]

[0119] In the formula: U is a random variable subject to 0-1 uniform distribution; R imax is the maximum value in R f1 , R f2 i represents the i-th possible failure pipeline;

[0120] Determine whether each possible failure pipeline is damaged:

[0121] If L i > D i , the i-th possible failure pipeline is intact;

[0122] If L i ≤ D i , the i-th possible failure pipeline is damaged;

[0123] Wherein, L i is the length of the i-th possible failure pipeline;

[0124] Calculate the number of damaged points H i of the damaged possible failure pipeline: H i = L i / D i .

[0125] Then, randomly assign damage types to each damaged point to generate a gas pipeline network damage network.

[0126] S6, simulate the repair process of the gas pipeline network damage network:

[0127] The gate station repair time is fixed as 3 days, and the failure gate station is repaired;

[0128] determining the respective repair time when the pipeline damage type is leakage or rupture;

[0129] generating the repair sequence of the possible failure pipelines of each damage by using a random function, sampling and assigning the repair time, and repairing the possible failure pipelines of each damage;

[0130] judging whether the damaged gas pipeline network is repaired or not; if not, returning to step S5 to randomly allocate the damage type to each damage point.

[0131] Subsequently, the resilience curve of the gas pipeline network with different attributes changing over time is obtained by the following method:

[0132] determining the seismic resilience attribute parameters of the gas pipeline network; the seismic resilience attribute parameters include technical attributes, organizational attributes, social attributes and economic attributes;

[0133] technical attribute resilience curve, organizational attribute resilience curve, social attribute resilience curve and economic attribute resilience curve are respectively established.

[0134] In addition, the seismic resilience index is calculated based on the resilience curve in this embodiment:

[0135] TRT=t k -t0;

[0136]

[0137] In the formula: TRT is the recovery time; t k is the time when the gas pipeline network is completely recovered; t0 is the time when the gas pipeline network starts to be repaired;

[0138] SRT is the recovery trajectory centroid; Q(t) represents the resilience curve; Δt represents the time interval;

[0139] Re is the network redundancy; Q(T)2 represents the post-earthquake performance of the organizational attribute of the gas pipeline network; Q(T)1 represents the post-earthquake performance of the technical attribute of the gas pipeline network;

[0140] R is the recovery force; N(t) is the performance evaluation index of the seismic resilience attribute parameter corresponding to the time t when the gas pipeline network is in normal operation; N is the number of simulations.

[0141] Embodiment 2:

[0142] The method for establishing the seismic resilience curve of the urban gas pipeline network based on Monte Carlo simulation, on the basis of embodiment 1:

[0143] In this embodiment, the existing basic theoretical framework is combined, and the actual pipeline earthquake damage in China is referred to, and K1 and K2 are assigned according to the characteristics of different pipe materials and pipe diameters, as shown in Table 1.

[0144] Table 1 K1, K2 assignment table

[0145]

[0146] Example 3:

[0147] On the basis of the method for establishing the urban gas pipeline network seismic resilience curve based on Monte Carlo simulation, the technical attribute resilience curve, the organizational attribute resilience curve, the social attribute resilience curve, and the economic attribute resilience curve are respectively established by the technical attribute resilience function, the organizational attribute resilience function, the social attribute resilience function, and the economic attribute resilience function on the basis of Example 1 or 2.

[0148] In this example,

[0149] The technical attribute resilience function is:

[0150] Q(t)1=ω1·n s / N s +ω2·n p / N p ;

[0151] In the formula, Q(t)1 is the seismic resilience under the technical attribute; N s , n s are respectively the number of non-failed gate stations before and after the earthquake; N p , n p are respectively the number of non-failed pipelines before and after the earthquake; w1 and w2 are respectively the gate station importance factor and the pipeline importance factor, and satisfy w1+w2=1.

[0152] The organizational attribute resilience function is:

[0153]

[0154] In the formula, Q(t)2 is the seismic resilience under the organizational attribute; N pre is the number of users who can accept gas before the earthquake; n pos is the number of users who can accept gas after the earthquake.

[0155] The social attribute resilience function is:

[0156]

[0157] In the formula, Q(t)3 is the seismic resilience under the social attribute; w i is a coefficient representing the importance degree of user i, and users such as hospitals, schools, shopping malls, and important traffic hubs take a value of 1.5, and ordinary residential users take a value of 1; n i is the population density covered by user i.

[0158] The economic attribute resilience function is:

[0159]

[0160] In the formula, Q(t)4 is the anti-seismic resilience under the economic attribute; I s is the construction cost of a gate station of the urban gas pipeline network, in ten thousand yuan; I j1 is the construction cost of a pipeline of the urban gas pipeline network, in ten thousand yuan / km; L i is the construction cost of a pipeline of the urban gas pipeline network, in ten thousand yuan / km; L p is the length of each non-failed pipeline, in km; I j2 is the amount required to repair a gate station, in ten thousand yuan; I j3 is the amount required to repair a pipeline, in ten thousand yuan; I p is the construction cost of the entire urban gas pipeline network, in ten thousand yuan.

[0161] Example 4:

[0162] In this example, a city gas pipeline network in a city in the earthquake-prone southwest region of China is taken as an example to establish an anti-seismic resilience curve and calculate an anti-seismic resilience index.

[0163] The urban gas pipeline network of the city is shown in FIG. 1, the pipeline pressure is mainly high pressure 4.0 MPa, steel pipes and PE pipes are used, there are currently 2 gate stations, 131 node units, a total of 136 pipelines, and the pipeline construction is a total length of 83.437 km. The number of users of the current gas pipeline network is 287 households. Figure 2 The city is located near the Longmenshan earthquake fault zone, and the plate movement makes the area prone to earthquakes. The maximum magnitude of the earthquake is 7, and the established ground motion prediction equation is:

[0164]

[0165]

[0166] In the formula, ε1 is subject to a normal distribution with a mean of 0 and a standard deviation of 0.7918; ε2 is subject to a normal distribution with a mean of 0 and a standard deviation of 0.8643; and ε3 is subject to a normal distribution with a mean of 0 and a standard deviation of 0.9439.

[0167] In this example, Monte Carlo simulation is performed on each node in the target urban gas pipeline network, and the sampling number is 10,000. Since the uncertainty of ground motion is considered, the PGA, PGV, and PGD obtained each time are different, so the median value of the ground motion parameters of each node obtained at a certain time is taken to represent the state of the earthquake pipeline network at that time. The PGA corresponding to the two gate stations of the urban gas pipeline network is shown in Table 2:

[0168] Table 2 Gate station PGA value

[0169] ​ Door station node number Epicentral distance (km) PGA (g) 130 3.351559 0.455989508 131 10.86963 0.263199218

[0170] The PGV and PGD values of each pipe section of the town gas pipe network are obtained, and some results are shown in Table 3:

[0171] Table 3 PGV and PGD values of some pipes of the town gas pipe network

[0172] Pipe number Pipe length (m) PGV (cm / s) PGD (cm) 1-2 34.209 60.286 55.067 1-130 611.783 62.100 53.780 1-4 427.165 60.545 56.580 2-3 606.036 61.282 56.086 2-40 249.207 59.052 54.983 3-4 306.242 61.541 57.598 3-6 321.847 63.053 56.614 4-5 35.131 61.374 58.281 5-6 677.292 62.886 57.297 5-71 316.116 64.074 56.745 6-7 1006.072 62.258 57.417 7-8 195.118 60.259 57.555 7-9 490.440 58.518 57.793

[0173] Then, the failure probability of the gate station is calculated, and the results are shown in Table 4:

[0174] Table 4 Failure probability of the gate station

[0175] Door station node number PGA (g) Failure probability P 130 0.455989508 0.6655902 131 0.263199218 0.249103276

[0176] As can be seen from Table 4, the failure probability of the No. 130 gate station is higher than that of the No. 131 gate station, and the reason is that the No. 130 gate station is close to the epicenter, and the intensity of the ground motion and the related ground motion parameter characteristics are more significant, thereby causing the seismic resistance of the No. 130 gate station to be greatly affected.

[0177] In the case of steel pipes, K1=0.08 and K2=1.5×10 -4 are taken, and in the case of PE pipes, K1=0.05 and K2=8×10 -5 are taken. Accordingly, the failure probability of each pipeline is calculated, and some calculation results are shown in Table 5:

[0178] Table 5 Failure probability of some gas pipelines

[0179]

[0180] Then, according to the failure probability of each pipeline of the town gas pipe network calculated, the pipelines with P>0.75 are selected, and it is considered that the possibility of failure of these pipelines is extremely high when the earthquake occurs. The two damage point lengths and the number of damage points of these pipelines are calculated, and the pipeline damage point results are shown in Table 6:

[0181] Table 6 Pipeline damage point record

[0182]

[0183]

[0184] At this point, based on the above calculation, the failure conditions of each gate station and pipeline of the town gas pipe network under a certain 7-level earthquake are shown in Table 7: Figure 3 Figure 3 The red area in the middle represents the failed facilities, and it can be seen that the No. 130 gate station fails, and 18 pipelines such as 9-10 and 10-20 fail. ​

[0185] After that, the simulation repair process is as follows:

[0186] In this study pipeline network, 130 door station failure, 9-10, 10-20, a total of 18 pipe failure. First, the 130 door station repair, 3 days after the first repair is complete, the door station, gas supply function recovery, after the repair of each failure pipe, until all the pipe repair is complete, the city gas pipeline network to the initial performance of the perfect state.

[0187] Finally, the technical properties of the resilience curve, organizational properties of the resilience curve, social properties of the resilience curve and economic properties of the resilience curve are shown in Figure 4 、 Figure 5 、 Figure 6 and Figure 7 .

[0188] In addition, the resilience index of the urban gas pipeline network is calculated in this embodiment:

[0189] (1) The recovery time of the target urban gas pipeline network: TRT = 223-6 = 217h.

[0190] This result shows that the recovery process of the pipeline network after the earthquake is about 217 hours, which is about 9 days. The larger TRT value means that the recovery process of the system is relatively long, reflecting its relatively weak recovery ability. In view of this result, if the initial repair efficiency can be optimized or the seismic design of key facilities can be improved, the recovery time can be significantly shortened.

[0191] (2) The shape center of the recovery trajectory:

[0192] Based on the resilience curves of the four attributes, the shape center of the recovery trajectory under each attribute is calculated and compared to evaluate the influence of different attributes on the recovery efficiency of the system. The calculation results are shown in Table 7:

[0193] Table 7 SRT value under each attribute

[0194] Attribute SRT Technology 111.3501 Organization 111.4325 Society 111.4528 Economy 111.3043

[0195] From the above table, it can be seen that the SRT values of the four attributes are consistent. This may reflect that in the repair process of the urban gas pipeline network, the coordination between each attribute dimension is good, especially the effectiveness of resource scheduling and management.

[0196] (3) Redundancy:

[0197] In this embodiment, t = 6h, after the earthquake, the performance level of the organization attribute of the town gas pipe network Q2(t = 6) = 85.72%, the performance level of the technical attribute Q1(t = 6) = 68.75%. Then the redundancy degree result Re = 85.72% / 68.75% = 1.25.

[0198] The higher the redundancy degree Re value, the stronger the standby capacity and emergency fault tolerance mechanism of the town gas pipe network in the early stage after the earthquake.

[0199] (4) Recovery:

[0200] When the gas pipe network is in normal operation, the performance evaluation index value of each attribute is 100%, and the recovery force R value under four attributes is shown in Table 8:

[0201] Table 8 R value under each attribute

[0202] Attribute R Technology 0.8719 Organization 0.9148 Society 0.9344 Economy 0.7901

[0203] As can be seen from Table 8, the recovery force of social attribute and organizational attribute is strong, especially the social attribute (R = 0.9344), which shows that the pipe network can quickly restore the gas supply service to the social population and key users after the earthquake. In contrast, the recovery force of economic attribute (R = 0.7901) is weak, which reflects that the economic loss may be more significant and may face high cost pressure in the recovery process.

[0204] It can be seen that according to the above calculation process, the seismic performance and toughness level of the target town gas pipe network under four attributes can be clearly and accurately mastered, and scientific and reasonable basis can be provided for proposing phased measures to improve the seismic toughness of the gas pipe network, analyzing the applicability of the seismic toughness measures, and providing important reference for the seismic engineering design and maintenance of the gas pipe network.

[0205] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

[0206] It is to be noted that, as used in this text, the terms "comprises", "comprising", or other variations such as "comprises", "comprising", or "including" merely specify the presence of stated features, integers, steps, or components, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. Furthermore, as used in this text, the term "coupled" means either a direct connection between components that are directly in contact with each other, or an indirect connection through other components where the coupling of intervention of other components is not explicitly shown.

Claims

1. A method for establishing seismic toughness curves of urban gas pipeline networks based on Monte Carlo simulation, characterized in that, Includes the following steps: S1. Establish earthquake motion prediction equations under different magnitudes and site conditions; S2. Obtain basic data of urban gas pipeline network, select matching seismic motion prediction equation, and predict seismic motion parameters of urban gas pipeline network. S3. Based on Monte Carlo simulation, random sampling of seismic motion parameters of urban gas pipeline network is performed to calculate the failure probability of each gate station and pipeline in urban gas pipeline network. The pipeline failure probability is calculated using the following formula: P 管线 =1-(1-P f1 )·(1-P f2 ); R f1 =0.002416×PGV×K1; R f2 =2.5829×PGD 0.319 ×K2; In the formula: P 管线 P represents the pipeline failure probability. f1 P represents the probability of connection failure due to uncertainty. f2 The gas supply uncertainty failure probability; L is the pipeline length; R f1 The average damage rate due to uncertainties in connectivity; R f2 The average seismic damage rate is the gas supply uncertainty; PGV is the peak seismic velocity; PGD is the permanent ground displacement; K1 is the adjustment factor related to PGV; K2 is the adjustment factor related to PGD. S4. Determine if each gate station is inoperable; S5. Determine the number of damage points on each failed pipeline, randomly assign damage types to each damage point, and generate a gas pipeline network failure network. S6. Simulate the repair process of a damaged gas pipeline network and obtain the resilience curves of different properties of the gas pipeline network over time.

2. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 1, characterized in that, The earthquake motion prediction equation is as follows: lgY=C1+C2·M w +C3·M w 2 +C4lg[R+C5·exp(C6·M w )]+ε; In the formula: Y represents the target ground motion parameter; M w R is the moment magnitude; C1, C2, C3, C4, C5, and C6 are all constants; ε is an uncertain random variable that follows a normal distribution with a mean of 0 and a standard deviation of σlg(Y), where σ is the root mean square of the population sample.

3. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 1, characterized in that, The ground motion parameters include: peak ground acceleration, peak ground velocity, and permanent ground displacement.

4. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 3, characterized in that, The failure probability of the gate station is calculated using the following formula: P 门站 =1-(1-P 储气罐 )×(1-P 计量调压间 ); In the formula: P 门站 P represents the probability of gate station failure. 储气罐 P represents the facility failure probability of the gas storage tank. 储气罐 is the probability of facility failure in the metering and pressure regulating room; PGA is the peak ground acceleration.

5. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 1, characterized in that, The method for determining whether each gate station is in failure includes: For each gate station, a random decision value r is generated within the interval 0 to 1, and r is compared with the gate station failure probability of that gate station: If r < gate station failure probability, the gate station is determined to be failed; If r ≥ the gate station failure probability, the gate station is considered to be operating normally.

6. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 1, characterized in that, The method for determining the number of damage points on each failed pipeline includes: S501. Pipelines with a failure probability greater than a set threshold are defined as potentially failed pipelines. S502. Calculate the average distance D between potential failure points in the pipeline. i : In the formula: U is a random variable that follows a uniform distribution of 0-1; R imax For R f1 R f2 The maximum value in; i represents the i-th potentially failed pipe; S503. Determine if any potentially faulty pipes are damaged: If L i >D i If the i-th potentially failed pipe is intact, then the i-th pipe is intact. If L i ≤D i If the i-th pipe is damaged, then the i-th pipe may fail. Among them, L i Let be the length of the i-th potentially failing pipe; S504. Calculate the number H of potential failure points in the damaged pipeline. i H i =L i / D i .

7. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 1, characterized in that, The method for simulating the repair process of a damaged gas pipeline network includes: S601. Fix the gate station repair time to 3 days and repair the failed gate station; S602. Determine the repair time for pipeline damage types such as leakage and rupture. S603. Use a random function to generate the repair order of each damaged and potentially failed pipeline, sample and assign the repair time, and repair each damaged and potentially failed pipeline. S604. Determine whether the damaged gas pipeline network has been repaired; if not, return to step S5 and randomly reassign the damage type to each damaged point.

8. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 1, characterized in that, The method for obtaining the resilience curves of different properties of the gas pipeline network over time includes: S605. Determine the seismic toughness attribute parameters of the gas pipeline network; the seismic toughness attribute parameters include: technical attributes, organizational attributes, social attributes and economic attributes; S606. Establish technical attribute resilience curves, organizational attribute resilience curves, social attribute resilience curves, and economic attribute resilience curves respectively.

9. The method for establishing the seismic toughness curve of urban gas pipeline network based on Monte Carlo simulation according to claim 8, characterized in that, Also includes: S7. Based on the aforementioned toughness curve, calculate the seismic toughness index: TRT=t k -t0; In the formula: TRT is the recovery time; t k t0 is the time when the gas pipeline network is fully restored; t0 is the time when the gas pipeline network begins repair. SRT represents the centroid of the recovered trajectory; Q(t) represents the resilience curve; Δt represents the time interval. Re represents the network redundancy level; Q(T)2 represents the post-earthquake performance of the gas pipeline network organizational attributes; Q(T)1 represents the post-earthquake performance of the gas pipeline network technical attributes. R represents the restoring force; N(t) represents the performance evaluation index of the seismic toughness attribute parameter at time t when the gas pipeline network is operating normally; N represents the number of simulations.

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