Municipal drainage pipeline safety risk assessment method and device

Abstract

The invention discloses a municipal drainage pipeline safety risk assessment method and device, and belongs to the technical field of municipal drainage pipeline design. According to the method, a complete assessment process of determining assessment factors, calculating possibility scores, calculating consequence scores and judging risk levels is defined, the assessment factors cover the possibility and consequences, meanwhile, scores are calculated by adopting a specific formula, and four levels of risks are divided through a risk matrix. The method overcomes the defects that a conventional CJJ181 method has no static prediction, is incomplete in possibility factors and does not consider consequences, achieves the dynamic and comprehensive evaluation of the pipeline safety risk, provides a scientific basis for determining the pipeline safety risk level and formulating targeted management and control measures, is standard in evaluation process, is high in operability, and is suitable for popularization and application. And practical requirements of investigation and detection of municipal drainage pipelines are met.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the technical field of municipal drainage pipeline design, in particular to a municipal drainage pipeline safety risk assessment method and device. BACKGROUND

[0002] The municipal drainage pipeline is an important part of urban infrastructure, and its safe and stable operation is directly related to the urban drainage and flood control capacity, water environment quality and normal production and life of residents. The municipal drainage pipeline safety risk assessment, as a core means of systematically identifying pipeline defects and comprehensively analyzing safety risks, is a prerequisite for formulating targeted control measures and ensuring long-term reliable operation of the pipeline.

[0003] At present, the safety risk assessment of the municipal drainage pipeline in the industry is mainly based on the method given in the Technical Specification for Urban Drainage Pipeline Detection and Evaluation CJJ181. This method mainly evaluates two types of indexes, i.e. structural defects and functional defects of the pipeline, and reflects the current health status of the pipeline by giving corresponding scores and grades to the hazard degree of different defects. However, in the actual application process, this conventional evaluation method has obvious limitations: first, the evaluation result is only a static description of the current situation of the pipeline, which cannot reflect the actual degree of risk occurrence, and lacks the prediction ability of the future structural instability and functional degradation trend of the pipeline, making it difficult to meet the long-term operation and maintenance planning needs of the pipeline; second, the risk possibility factors covered by this method are not comprehensive, and the health status of the pipeline is only reflected by structural and functional defects, without considering key factors such as the physical properties of the pipeline, the laying environment, and the daily maintenance level, which cannot fully reflect the operation status and essential safety level of the pipeline, resulting in deviation of the risk assessment result; third, this method does not consider the consequences after the occurrence of pipeline safety risk, and the pollution of the surrounding soil, groundwater, and water body caused by pipeline risk events, as well as the social impact on residents' life and urban operation, are important factors for judging the risk size and formulating reasonable control measures, and the lack of conventional methods greatly reduces the practicality of risk assessment.

[0004] Therefore, there is an urgent need for a more scientific and comprehensive municipal drainage pipeline safety risk assessment method to solve the above problems. SUMMARY

[0005] The embodiment of the present application provides a municipal drainage pipeline safety risk assessment method and device. The technical solution is as follows: On the one hand, a municipal drainage pipeline safety risk assessment method is provided, and the method comprises: Step 101, determining evaluation factors, including possibility and consequence, wherein the influencing factors of the possibility include pipeline physical properties, pipeline structural detection, pipeline functional detection, and pipeline maintenance, and the possibility is affected by pipeline laying conditions, and the influencing factors of the consequence include environmental impact and social impact.

[0006] Step 102, calculating a possibility score and determining a possibility level. Step 103, calculating a consequence score and determining a consequence level. Step 104, synthesizing the possibility level and the consequence level, and dividing a risk level into four levels of I (low), II (general), III (relatively large), and IV (major) through a risk matrix.

[0007] Optionally, the calculating the possibility score and determining the possibility level comprises: calculating a pipeline laying score H, and the calculation formula is: wherein H is the pipeline laying score, is a pipeline laying index score, adopting a decimal system, i=1, 2, ……n, n is the number of pipeline laying evaluation indexes, is a pipeline laying index weight; determining a pipeline laying correction coefficient a according to the pipeline laying score H; calculating a possibility score P, and the calculation formula is: wherein, is a corrected possibility score, β1 is a pipe material coefficient, β2 is a pipe age coefficient, β3 is a pipeline interface coefficient, and β4 is a prediction coefficient, , is a possibility index score, adopting a decimal system, i=1, 2, ……n, n is the number of possibility evaluation indexes, is a possibility index weight, is a single possibility index score, adopting a decimal system, j=1, 2, ……n, n is the number of single possibility evaluation indexes, is a single possibility index weight; determining a possibility level according to the possibility score P.

[0008] Optionally, the calculating the consequence score and determining the consequence level comprises: calculating a consequence score C, and the calculation formula is: wherein, is a consequence score, , is a consequence index score, adopting a decimal system, i=1, 2, ……n, n is the number of consequence evaluation indexes, is a consequence index weight. Cj is a single consequence index score, using decimal, j = 1, 2, … n, n is the number of single consequence evaluation indexes, γ is a coupling additional term; A consequence level is determined according to the consequence score C.

[0009] Optionally, the pipeline physical property, the pipeline structural detection, the pipeline functionality detection, and the pipeline maintenance jointly constitute the core evaluation dimension of the possibility, and the pipeline laying condition is modified by a correction coefficient a on the possibility score P, for reflecting the influence of the pipeline laying environment on the possibility of risk occurrence.

[0010] Optionally, the evaluation indexes of the pipeline physical property include pipe age, pipe material, pipe diameter, and interface form. The evaluation indexes of the pipeline structural detection include rupture, deformation, corrosion, misalignment, undulation, disconnection, interface material shedding, branch pipe hidden connection, foreign matter penetration, and leakage. The evaluation indexes of the pipeline functionality detection include deposition, fouling, obstacle, residual wall dam root, tree root, and dregs. The evaluation indexes of the pipeline laying condition include ground activity condition, pipeline burial depth, safety spacing, pipeline crossing, illegal occupation, and soil condition. The evaluation indexes of the pipeline maintenance include maintenance frequency, repair times, emergency disposal level, and operation management system.

[0011] Optionally, the environmental impact and the social impact are two independent evaluation dimensions of the consequence, wherein the evaluation indexes of the environmental impact include soil pollution, underground water pollution, and water body pollution.

[0012] Optionally, the evaluation indexes of the social impact include service object, number of water interruption affected users, water interruption duration, resident complaint, and ground subsidence.

[0013] Optionally, , , are all obtained by the analytic hierarchy process. The analytic hierarchy process comprises: According to the selected evaluation index system, a judgment matrix is constructed, the maximum eigenvalue of the judgment matrix and the corresponding eigenvector are solved, and the importance weight of each evaluation index is determined based on the eigenvector.

[0014] In another aspect, a computer readable storage medium is provided, the computer readable storage medium stores a computer program, the computer program is loaded and executed by a processor to realize the municipal drainage pipeline safety risk evaluation method as described above.

[0015] In the embodiment of the present application, by explicitly determining the complete evaluation process of "determining evaluation factors, calculating possibility score, calculating consequence score, and determining risk level", and covering the possibility and consequence of the evaluation factors, and using a specific formula to calculate the score and dividing the four levels of risk through the risk matrix, the defects of the conventional CJJ181 method, such as static without prediction, incomplete possibility factors, and not considering consequences, are overcome, and dynamic and comprehensive evaluation of the safety risk of the pipeline is realized. The safety risk level of the pipeline is determined, and a scientific basis for formulating targeted control measures is provided. The evaluation process is standardized and has strong operability, and meets the practical needs of municipal drainage pipeline inspection and detection. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a flowchart of a municipal drainage pipeline safety risk evaluation method. Figure 2 It is a schematic diagram of the mutual relationship between the parent class, child class, and grandchild class of the evaluation factors. Figure 3 It is a risk matrix determination schematic diagram. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be described in further detail below with reference to the drawings.

[0018] In this paper, "multiple" refers to two or more. "And / or" describes the association between the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0019] Embodiment 1 As shown in the flowchart of a municipal drainage pipeline safety risk evaluation method. Figure 1

[0020] The embodiments of the present application include the core process of the municipal drainage pipeline safety risk evaluation method, which covers the following steps.

[0021] On the one hand, a municipal drainage pipeline safety risk evaluation method is provided, which includes: Step 101, determining evaluation factors, the evaluation factors including possibility and consequence, wherein the influencing factors of the possibility include pipeline physical properties, pipeline structural detection, pipeline functional detection, and pipeline maintenance, and the possibility is affected by pipeline laying conditions, and the influencing factors of the consequence include environmental impact and social impact.

[0022] ​The assessment factors are categorized into several sub-categories. Under the "Possibility" category, pipeline physical attributes include four sub-indicators: pipe age, pipe material, pipe diameter, and joint type. Pipeline structural inspection includes ten sub-indicators: cracking, deformation, corrosion, misalignment, undulation, disconnection, joint material detachment, concealed branch pipe connections, foreign object penetration, and leakage. Pipeline functional inspection includes six sub-indicators: sediment, scale, obstacles, residual walls / dam roots, tree roots, and scum. Pipeline maintenance includes four sub-indicators: maintenance frequency, number of repairs, emergency response level, and operation management system. Pipeline laying conditions include six sub-indicators: ground activity, pipeline burial depth, safety distance, pipeline crossings, illegal encroachment, and soil conditions. Under the "Consequences" category, environmental impact includes three sub-indicators: soil pollution, groundwater pollution, and water pollution. Social impact includes five sub-indicators: service recipients, number of users affected by water outages, duration of drainage interruption, resident complaints, and ground subsidence. These sub-indicators collectively constitute 38 sub-categories of assessment factors, ensuring no assessment factor is omitted.

[0023] like Figure 2 As shown, the relationships between the parent, child, and grandchild classes of the evaluation factors are as follows: Figure 2 As shown.

[0024] Step 102: Calculate the probability score and determine the probability level.

[0025] In step 102, the probability assessment decomposes and arranges the factors affecting the probability, calculates them according to the following formula in step 102, and determines the probability level based on the score, as shown in Table 1.

[0026] Table 1

[0027] In one possible implementation, step 102 includes the following.

[0028] S21, calculate the pipeline laying score H, the calculation formula is: Where H is the pipeline laying score, The scores for pipeline laying indicators can be calculated using the influencing factors of the probability indicators in Table 4, using a decimal system, where i = 1, 2, ..., n, where n is the number of pipeline laying evaluation indicators. Weighting of pipeline laying indicators; Table 4

[0029] It should be noted that, , , All data were obtained using the Analytic Hierarchy Process (AHP). A judgment matrix was constructed based on the selected evaluation index system. The maximum eigenvalue and corresponding eigenvector of the judgment matrix were then calculated. Based on the eigenvector, the importance weight of each evaluation index was determined.

[0030] In one example, the number of pipeline laying evaluation indicators is n=6 (corresponding to 6 laying sub-indicators). The score Hi of each indicator is assigned in decimal from 0 to 10 (e.g., when the ground activity is "dense traffic on the main road", H1=8 points; when the traffic on the branch road is "low traffic", H1=3 points; when the soil is "soft soil", H6=7 points; when the soil is "hard rock", H6=2 points). The weight Ji of each indicator is determined by the analytic hierarchy process (e.g., pipeline burial depth has the greatest impact on laying safety, J2=0.3; safety distance has a smaller impact, J3=0.1). Example calculation: H=8×0.2 (ground activity)+7×0.3 (burial depth)+6×0.1 (safety distance)+5×0.15 (crossing)+4×0.15 (illegal encroachment)+7×0.1 (soil quality)=6.5 points.

[0031] S22, determine the pipeline laying correction coefficient α according to the pipeline laying score H, as detailed in Table 3. Thus, those skilled in the art can divide the α interval according to the H score based on Table 3.

[0032] Table 3 - Correction Factors for Pipeline Laying

[0033] S23, calculate the probability score P, the calculation formula is: ,in, The corrected probability scores are: β1 is the pipe material coefficient, β2 is the pipe age coefficient, β3 is the pipe joint coefficient, and β4 is the prediction coefficient. , The probability index score is represented by a decimal number, where i = 1, 2, ..., n, and n is the number of probability assessment indicators. As the weight of the probability index, The score for each probability indicator is given in decimal, where j = 1, 2, ..., n, and n is the number of probability assessment indicators. Weights for individual probability indicators; The pipeline condition prediction uses a prediction coefficient β4, which predicts the health status of a specific pipe material at a certain age, increasing the probability of occurrence and reflecting the forward-looking nature of the assessment. It represents a targeted improvement to existing technologies. The prediction coefficient β4 values ​​are as follows: 1.1 for the first rupture of ductile iron pipes over 30 years old, and 1.5 for recurrences after repair; 1.2 for the first rupture of chemical building material pipes over 30 years old, and 2.0 for recurrences after repair; and 1.5 for the first rupture of all types of pipes with a diameter of DN1500 or larger, and 3.0 for recurrences after repair.

[0034] In one example, consider a DN1600 chemical building material pipe with a 30-year age. This pipe uses a precast ring asbestos cement joint and experiences its first rupture. According to the coefficient rules, the pipe material is chemical building material, so β1 = 1.15; the pipe age is 30 years, so β2 = 1.25; the joint is precast ring asbestos cement, so β3 = 1.2; and the rupture is the first time and the pipe diameter is greater than DN 1500 mm, so β4 = 1.5. Assuming the probability index weights are determined using the analytic hierarchy process, ∑PiIi = 5.2 (a weighted sum of scores from pipe physical properties, structural testing, functional testing, and maintenance), the pipe laying score H = 4.8, corresponding to a correction coefficient α = 1.15. The probability score P = 1.15(α) × 1.15(β1) × 1.25(β2) × 1.2(β3) × 1.5(β4) × 5.2(∑PiIi) ≈ 15.473 points.

[0035] The original score exceeded the 10-point scale due to the superposition of multiple factors. In practical application, "normalization" is adopted, with 10 points as the upper limit. The score of 15.473 is scaled down to the 10-point scale proportionally. The calculation method is 10 × (15.473 ÷ maximum theoretical score). Assuming that the maximum theoretical score is 17, then after normalization, P≈8.9 points. Therefore, referring to the probability assessment level table (8≤P≤10 corresponds to probability level 5), the probability level of this pipeline is determined to be level 5.

[0036] Table - Pipe Material Coefficient β1

[0037] Table - Pipe Age Coefficient β2

[0038] Table - Pipe Interface Coefficient β3

[0039] S24, determine the probability level based on the probability score P.

[0040] Table 2 lists the probability indicators.

[0041] Table 2

[0042] Step 103: Calculate the consequence score and determine the consequence level.

[0043] In this step, the consequences assessment breaks down and arranges the factors that affect the consequences, calculates them according to the following formula, and determines the consequences level based on the scores, as shown in Table 5.

[0044] In one possible implementation, step 103 includes the following.

[0045] S31, Calculate the consequence score C, the formula is: ,in, As a consequence-based score, , The scores for the consequence indicators can be calculated with reference to the consequence indicators in Table 6, using a decimal system, where i = 1, 2, ..., n, and n is the number of consequence assessment indicators. As for the weight of the consequence indicators, The scores for individual consequence indicators can be calculated with reference to the consequence indicators in Table 6, using a decimal system, where j = 1, 2, ..., n, and n is the number of individual consequence assessment indicators. γ represents the weight of a single consequence indicator, and γ is a coupling additional term. In one example, the number of consequence assessment indicators is n=2 (corresponding to two dimensions: environmental impact and social impact). The score Ci for each dimension is calculated as "sum of scores of sub-categories × weights" (e.g., Environmental Impact C1 = Soil pollution 5 points × 0.4 + Groundwater pollution 4 points × 0.3 + Water pollution 3 points × 0.3 = 4.1 points); Social Impact C2 = Service recipients 6 points × 0.2 + Number of users affected by water outage 5 points × 0.3 + Duration of drainage interruption 4 points × 0.2 + Resident complaints 3 points × 0.1 + Ground subsidence 2 points × 0.2 = 4.4 points. The weights Ii for each dimension are determined using the analytic hierarchy process (Social Impact I2 = 0.6; Environmental Impact I1 = 0.4), then ∑CiIi = 4.1 × 0.4 + 4.4 × 0.6 = 1.64 + 2.64 = 4.28. Assuming that the pipeline risk event involves both the number of users affected by water outage and groundwater pollution, according to the coupling additional term value table, γ = 3.6. The consequence score is C = ∑CiIi + γ = 4.28 + 3.6 = 7.88 points.

[0046] S32, determine the consequence level based on the consequence score C.

[0047] Table 5

[0048] Table 6

[0049] Coupling Additional Items

[0050] In one example, the C score is divided into 5 levels (e.g., 8≤C≤10 is level 5, 6≤C<8 is level 4, 4≤C<6 is level 3, 2≤C<4 is level 2, and 0≤C<2 is level 1). C=7.88 corresponds to the consequence level 4 (6≤7.88<8).

[0051] Step 104: Combining the probability level and the consequence level, the risk level is divided into four levels: Level I (low), Level II (moderate), Level III (relatively high), and Level IV (serious) using a risk matrix.

[0052] Projects assessed using this method can further refine secondary measures based on the aforementioned different levels of control measures, forming an "assessment-measure" closed loop and improving the feasibility of technology implementation. For example, for soil pollution caused by pipeline leakage, a secondary repair measure that can be adopted is the trenchless remediation process of ultraviolet curing in-situ remediation (UV-CIPP).

[0053] like Figure 3 The diagram shown illustrates the risk matrix determination.

[0054] In one possible implementation, the likelihood level (5 levels, Arabic numerals) and the consequence level (5 levels, Arabic numerals) are cross-matched (e.g., likelihood level 3 × consequence level 2 corresponds to risk level III (relatively high); likelihood level 4 × consequence level 4 corresponds to risk level IV (serious)). In this example, likelihood level 3 + consequence level 2, the final risk level is determined to be level III (relatively high).

[0055] The evaluation method of Example 1 will be further explained below using a specific implementation scenario as an example.

[0056] A safety risk assessment was conducted on a DN800 concrete drainage pipeline in the old urban area of ​​a certain city. The pipeline is 20 years old, with cement mortar joints, and is laid under a main road (with an average daily traffic flow of 8,000 vehicles). The burial depth is 2.5m, the safety distance meets the specifications, there are no crossings or illegal encroachments, and the soil is silty clay. The routine maintenance frequency is once every six months, and there have been 2 repairs in the past 3 years. The emergency response time is ≤2 hours, and there is a sound operation and management system. The pipeline serves 3 surrounding residential communities (approximately 1,500 households). There have been no major pollution incidents in the past, only occasional minor water accumulation complaints during the rainy season, and there have been water outages accompanied by mild soil contamination.

[0057] The specific implementation process is as follows.

[0058] The evaluation factors for the pipeline are determined according to 7 subcategories and 38 sub-categories of evaluation factors (such as physical attributes sub-items such as "pipe age 20 years, concrete pipe material, DN800 pipe diameter, cement mortar joint" and laying conditions sub-items such as "high traffic volume on main road, burial depth 2.5m, silty clay").

[0059] When calculating H in step S21, the following parameters are considered: ground activity H1 = 8 points (high traffic volume), burial depth H2 = 7 points (2.5m meets the standard but is not optimal), safety distance H3 = 5 points (meets the standard), crossing H4 = 3 points (none), illegal encroachment H5 = 3 points (none), and soil quality H6 = 7 points (silty clay is prone to settlement). The weights Ji are 0.2, 0.3, 0.1, 0.15, 0.15, and 0.1, respectively. Therefore, H = 8 × 0.2 + 7 × 0.3 + 5 × 0.1 + 3 × 0.15 + 3 × 0.15 + 7 × 0.1 = 6.2 points. Then, referring to the correction coefficient α value table in S22 (α = 1.2 when H ≥ 5), we take α = 1.2.

[0060] When calculating P in step S23, the physical property P1 = 7 (pipe age) × 0.4 + 6 (concrete) × 0.3 + 5 (DN800) × 0.2 + 4 (cement mortar joint) × 0.1 = 5.8 points; the structural inspection P2 = 6 points (local minor corrosion, no cracks); the functional inspection P3 = 5 points (small amount of deposition); and the maintenance P4 = 4 points (frequency meets standards but many repairs). The weights Ii are 0.3, 0.4, 0.2, and 0.1, respectively, resulting in ∑PiIi = 5.8 × 0.3 + 6 × 0.4 + 5 × 0.2 + 4 × 0.1 = 5.74. According to the coefficient value rules, for concrete pipes, β1 = 1.05 (pipe material coefficient); for pipes aged 20 years, β2 = 1.05 (pipe age coefficient); for cement mortar joints, β3 = 1.15 (joint coefficient); and for repairs in the past 3 years (not the first recurrence of cracks), β4 = 1.0 (prediction coefficient).

[0061] Then P = 1.2(α) × 1.05(β1) × 1.05(β2) × 1.15(β3) × 1.0(β4) × 5.74(∑PiIi) ≈ 8.73 points. Then, in step S24, refer to the probability assessment level table (8≤P≤10 corresponds to probability level 5) to determine the probability level as 5 (8≤8.73≤10).

[0062] When calculating C in step S31, the environmental impact C1 = 3 (slight soil pollution) × 0.4 + 2 (unpolluted groundwater) × 0.3 + 2 (unpolluted water body) × 0.3 = 2.4 points, and the social impact C2 = 4 (residential community) × 0.2 + 5 (water outage affecting 500 households) × 0.3 + 4 (interruption for 2 hours) × 0.2 + 3 (2 complaints) × 0.1 + 2 (no collapse) × 0.2 = 3.7 points. The weights Ii are 0.4 and 0.6 respectively, so ∑CiIi = 2.4 × 0.4 + 3.7 × 0.6 = 0.96 + 2.22 = 3.18. This pipeline previously experienced a water outage accompanied by slight soil pollution. According to the coupling additional term value table, the coupling element is "number of users affected by water outage + soil pollution", γ = 1.6.

[0063] Then C = ∑CiIi + γ = 3.18 + 1.6 = 4.78 points. Under step S32, refer to the consequence assessment level table (4 ≤ C < 6 corresponds to consequence level 3) to determine the consequence level as 3 (4 ≤ 4.78 < 6).

[0064] Based on the risk matrix, with a probability level of 5 and a consequence level of 3, the risk level was ultimately determined to be Level IV (Serious). As required, "immediate remediation measures + enhanced control" were to be taken. Therefore, the control measures were formulated as "using UV-cured in-situ remediation (UV-CIPP) technology for trenchless remediation + monthly inspections + increased inspections during the rainy season".

[0065] It should be noted that the evaluation factors given above are all-category factors. In practice, they can be selected based on the characteristics of the pipeline being evaluated. This application selects all or some indicators to participate in the evaluation, constructs a scenario-based indicator screening mechanism, selects some indicators to participate in the evaluation, and increases the scores of the corresponding evaluation indicators according to three scenarios: old urban areas (characteristics such as long pipeline age and poor soil quality), industrial parks (characteristics such as high pollution), and newly built urban areas (characteristics such as large pipeline diameter). Upper and lower limits are set to reflect the in-depth consideration of the actual use scenarios of the pipeline and enhance the adaptability and practicality of the evaluation method.

[0066] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0067] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware, or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk. The above descriptions are merely optional embodiments of this application and are not intended to limit the application. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for safety risk assessment of municipal drainage pipelines, characterized in that, The method includes: Step 101: Determine the assessment factors, which include two main categories: probability and consequences. The factors affecting probability include pipeline physical properties, pipeline structural inspection, pipeline functional inspection, and pipeline maintenance. The probability is affected by the pipeline laying conditions. The factors affecting consequences include environmental and social impacts. Step 102: Calculate the probability score and determine the probability level: Step 103: Calculate the consequence score and determine the consequence level; Step 104: Combining the probability level and the consequence level, the risk level is divided into four levels: Level I (low), Level II (moderate), Level III (relatively high), and Level IV (serious) using a risk matrix.

2. The method according to claim 1, characterized in that, The calculation of the probability score and determination of the probability level includes: The calculation formula for the pipeline laying score H is as follows: Where H is the pipeline laying score, The scores for pipeline laying indicators are given in decimal, where i = 1, 2, ..., n, and n represents the number of pipeline laying evaluation indicators. Weighting of pipeline laying indicators; The pipeline laying correction factor α is determined based on the pipeline laying score H. The probability score P is calculated using the following formula: ,in, The corrected probability scores are: β1 is the pipe material coefficient, β2 is the pipe age coefficient, β3 is the pipe joint coefficient, and β4 is the prediction coefficient. , The probability index score is represented by a decimal number, where i = 1, 2, ..., n, and n is the number of probability assessment indicators. As the weight of the probability index, The score for each probability indicator is given in decimal, where j = 1, 2, ..., n, and n is the number of probability assessment indicators. Weights for individual probability indicators; The probability level is determined based on the probability score P.

3. The method according to claim 1, characterized in that, The calculation of the consequence score and determination of the consequence level includes: The consequence score C is calculated using the following formula: ,in, As a consequence-based score, , The scores for the consequence indicators are in decimal, where i = 1, 2, ..., n, and n is the number of consequence assessment indicators. As for the weight of the consequence indicators, The score for each individual consequence indicator is given in decimal, where j = 1, 2, ..., n, and n is the number of individual consequence assessment indicators. γ represents the weight of a single consequence indicator, and γ is a coupling additional term. The severity level is determined based on the severity score C.

4. The method according to claim 1, characterized in that, The pipeline's physical properties, structural testing, functional testing, and maintenance together constitute the core assessment dimensions of the probability. The pipeline laying conditions are adjusted using a correction coefficient α to modify the probability score P, reflecting the impact of the pipeline laying environment on the probability of risk occurrence.

5. The method according to claim 4, characterized in that, The evaluation indicators for the physical properties of the pipeline include pipe age, pipe material, pipe diameter, and interface type; The evaluation indicators for the pipeline structural inspection include cracks, deformation, corrosion, misalignment, undulation, disconnection, joint material detachment, concealed branch pipe connections, foreign object penetration, and leakage. The evaluation indicators for pipeline functional testing include sediment, scale, obstructions, residual wall and dam roots, tree roots, and scum; The evaluation indicators for pipeline laying include ground activity, pipeline burial depth, safety distance, pipeline crossings, illegal encroachment, and soil conditions. The evaluation indicators for pipeline maintenance include maintenance frequency, number of repairs, emergency response level, and operation and management system.

6. The method according to claim 1, characterized in that, The environmental impact and social impact are two independent assessment dimensions of the consequences, wherein the assessment indicators of the environmental impact include soil pollution, groundwater pollution, and water pollution.

7. The method according to claim 6, characterized in that, The social impact assessment indicators include the service recipients, the number of users affected by the water outage, the duration of the drainage interruption, resident complaints, and ground subsidence.

8. The method according to claim 2 or 3, characterized in that, , , All were obtained through the Analytic Hierarchy Process (AHP). The analytic hierarchy process includes: Construct a judgment matrix based on the selected evaluation index system, solve for the maximum eigenvalue and corresponding eigenvector of the judgment matrix, and determine the importance weight of each evaluation index based on the eigenvector.

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