Secondary water supply facility safety risk assessment method

Abstract

The invention relates to a secondary water supply facility safety risk assessment method, which comprises the steps of constructing a hierarchical structure model comprising a target layer, a criterion layer and an index layer from top to bottom according to an AHP analysis method, and constructing a judgment matrix for indexes of the same layer; according to Delphi, assigning and adjusting the hierarchy discrimination matrix by multiple experts until the hierarchy discrimination matrix passes the consistency check; and obtaining a final index weight value based on each index weight vector in each expert level discrimination matrix, calculating a total score of the secondary water supply facility, and evaluating a safety risk level of the secondary water supply facility of the community. According to the method, each index is scored, an AHP-Delphi analysis method is adopted to determine an evaluation index weight during evaluation index processing and weight calculation, finally, a comprehensive score is obtained through calculation, and grade division is performed on the hidden danger risk of the whole secondary water supply facility of the community according to the score value. And a quantifiable evaluation method is provided for secondary water supply facility evaluation.

Description

Technical Field

[0001] This invention relates to the field of assessment of urban secondary water supply facilities, and in particular to a method for assessing the safety risks of secondary water supply facilities based on the AHP-Delphi analysis method. Background Technology

[0002] In recent years, higher demands have been placed on urban water supply management. It is necessary to comprehensively investigate potential safety hazards in secondary water supply facilities and equipment, accelerate the upgrading and renovation of these facilities, and focus on improving the ability of water supply facilities to cope with emergencies and natural disasters, thereby enhancing the resilience of the water supply system. As a crucial link in ensuring the safety of the "last mile" of urban water supply, secondary water supply is directly related to the drinking water safety and health of the people, and is an important component of the urban lifeline. Improving the safety assurance capabilities and management level of secondary water supply is an important manifestation of practicing the people-centered urban concept.

[0003] According to surveys, the total area of ​​existing urban residential communities nationwide is approximately 30 billion square meters. Many of these communities have secondary water supply facilities that are old and dilapidated, urgently requiring assessment and renovation. Faced with such a massive stock of secondary water supply facilities, how to make renovation investment decisions and ensure long-term operation and maintenance supervision, thereby improving the safety and emergency response capabilities of these facilities and enhancing the resilience of the entire urban water supply system, is a problem that urban water supply managers need to address and solve.

[0004] In existing technologies, research on secondary water supply facilities mainly focuses on the research of technical standards for new buildings or renovation standards, as well as the application of new products and technologies in secondary water supply. However, there is little research on the evaluation of existing secondary water supply facilities, especially the lack of methods for quantitative evaluation of secondary water supply facilities. Summary of the Invention

[0005] The purpose of this invention is to provide a safety risk assessment method for secondary water supply facilities, addressing the lack of research on assessment methods for existing secondary water supply facilities both domestically and internationally.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for safety risk assessment of secondary water supply facilities, comprising the following steps:

[0008] Based on the AHP analysis method, a hierarchical model including the target layer, criterion layer and indicator layer is constructed from top to bottom, and a judgment matrix is ​​constructed for indicators at the same level.

[0009] According to Delphi, multiple experts assigned and adjusted the hierarchical discriminant matrix until it passed the consistency test.

[0010] The average value of the weight vector of each indicator in the expert level discrimination matrix is ​​used as the final weight value of the indicator. The total score of the secondary water supply facilities is calculated and the safety risk level of the secondary water supply facilities in the community is assessed.

[0011] As a preferred technical solution, the hierarchical structure model takes the safety risk assessment index of secondary water supply facilities as the target and the water supply system, pump room, building water supply pipelines and ancillary facilities and rooftop water tanks and ancillary facilities as the criteria.

[0012] As a preferred technical solution, the primary indicators of the water supply system include water quality assurance, water pressure assurance, water quantity assurance, and automatic control.

[0013] The primary indicators of the pump room include pump units, water tanks / boxes, pipelines and valves, electrical facilities, and environmental sanitation.

[0014] The primary indicators for building water supply pipes and ancillary facilities include building water supply pipes, valve fittings, water meters, and antifreeze insulation;

[0015] The primary indicators for the rooftop water tank and its ancillary facilities include the rooftop water tank, local pressurization equipment, and antifreeze insulation.

[0016] As a preferred technical solution, the secondary indicators of the water pump unit include material and performance conditions, service life, and others;

[0017] The secondary indicators of the water tank / box include the material and performance conditions and the operating conditions of the auxiliary facilities;

[0018] The secondary indicators of the building water supply pipes include material and performance conditions, service life and laying location;

[0019] The secondary indicators of the rooftop water tank include the material and performance conditions and the operating conditions of the auxiliary facilities;

[0020] The secondary indicators of the local booster equipment include material and performance conditions, service life, and others.

[0021] As a preferred technical solution, the method constructs a judgment matrix for n indicators at the same level based on the AHP analysis method as follows:

[0022] A={α ij}n*n

[0023] In the formula, α ij α represents the importance of indicator i relative to indicator j. ji =1 / α ij .

[0024] As a preferred technical solution, the consistency check of the hierarchical discrimination matrix is ​​specifically performed as follows:

[0025] For each expert's hierarchical discrimination matrix, find its largest eigenvalue and its corresponding eigenvector. Normalize the eigenvectors to obtain the relative importance weight vector for the corresponding hierarchical single ranking, and calculate the consistency index (CI) and consistency ratio (CR).

[0026]

[0027] Where, λ max is the largest eigenvalue of the hierarchical discriminant matrix, n is the order of the hierarchical discriminant matrix; RI is the average random consistency index, which is related to the order of the hierarchical discriminant matrix;

[0028] When the consistency ratio is less than the set threshold, the consistency of the comparison judgment matrix is ​​considered acceptable; otherwise, the judgment matrix that fails the consistency test will be corrected by experts.

[0029] As a preferred technical solution, the method calculates the average, median, and mode of each element of the hierarchical discrimination matrix, and feeds back to experts to determine whether the hierarchical discrimination matrix needs to be adjusted. If adjustment is required, the method returns to repeat the consistency check of the hierarchical discrimination matrix; otherwise, it outputs the final expert hierarchical discrimination matrix.

[0030] As a preferred technical solution, the method calculates the weight values ​​of all indicators in all criteria layers and indicator layers by performing a weighted average on each indicator weight vector according to the finally determined hierarchical discrimination matrix.

[0031] As a preferred technical solution, the method classifies the safety risks of secondary water supply facilities into multiple levels based on the total score of the safety risk assessment of the secondary water supply facilities:

[0032] A total score of 4 or less is Level V, which is a dangerous level; a total score of 4 or more but less than or equal to 6 is Level IV, which is a high-risk level; a total score of 6 or more but less than or equal to 7.5 is Level III, which is a medium-risk level; a total score of 7.5 or more but less than or equal to 9 is Level II, which is a low-risk level; and a total score of 9 or more is Level I, which is a safe level.

[0033] As a preferred technical solution, when the method evaluates communities with only some secondary water supply facilities, the ratio of the actual score of a certain indicator in the evaluated community to the total score of the applicable indicators in the evaluated community reflects the relative score rate of the actual water supply facilities in the evaluated community to the theoretical total water supply facilities.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) The evaluation indicators selected in this invention are comprehensive and representative, that is, they fully consider all factors affecting the safety risks of secondary water supply facilities; the evaluation method adopts the AHP-Delphi analysis method that combines subjective and objective approaches to determine the weight of the evaluation indicators, which greatly avoids the influence of subjective thinking, and determines the risk level through scoring, which intuitively reflects the safety risk status of secondary water supply facilities.

[0036] 2) This invention addresses the current state of secondary water supply facilities by summarizing and extracting key indicators that influence water quality, pressure, quantity, and water supply safety. It constructs an evaluation index system for secondary water supply facilities and employs the AHP-Delphi analysis method to assign weights to these indicators. Each indicator is scored, and a comprehensive score is calculated. Furthermore, the invention proposes a risk level classification for the overall secondary water supply facilities in a residential community based on the score, providing a quantifiable evaluation method for secondary water supply facility assessment. The primary purpose of this invention is to quantify evaluation indicators to facilitate a clear understanding of the safety risks associated with secondary water supply facilities, providing a scientific and intuitive basis for government or water supply management decision-making departments to formulate renovation plans or schemes. Attached Figure Description

[0037] Figure 1 This is a flowchart of the steps of the present invention;

[0038] Figure 2 This is a diagram of the evaluation index system for secondary water supply facilities in this invention. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] This example focuses on the application scenario of assessing the secondary water supply facilities in an existing residential community. These facilities include pump rooms, building water supply risers, and rooftop water tanks. (See also...) Figure 1-2 An AHP-Delphi-based safety risk assessment method for secondary water supply facilities was used to evaluate the secondary water supply facilities in existing residential communities. The steps are as follows:

[0042] Step 1: Construct a hierarchical model based on AHP analysis.

[0043] Based on the AHP analysis method, a hierarchical model is constructed from top to bottom, including an objective layer, a criterion layer, and an indicator layer. The objective is the safety risk assessment index of secondary water supply facilities, and the criteria are the water supply system, pump station, building water supply pipelines and ancillary facilities, and rooftop water tanks and ancillary facilities. The water supply system includes four primary indicators: water quality assurance, water pressure assurance, water quantity assurance, and automatic control. The pump station includes five primary indicators: pump units, water tanks (reservoirs), pipelines and valves, electrical facilities, and environmental sanitation. The building water supply pipelines and ancillary facilities include building water supply pipelines, valve fittings, water meters, and antifreeze protection. The four primary indicators are: temperature, etc. The rooftop water tank and its ancillary facilities include three primary indicators: rooftop water tank, local booster equipment, and antifreeze insulation. The water pump unit includes three secondary indicators: material and performance conditions, service life, and other. The water tank (reservoir) includes two secondary indicators: material and performance conditions, and ancillary facility conditions. The building water supply pipes include three secondary indicators: material and performance conditions, service life, and laying location. The rooftop water tank includes two secondary indicators: material and performance conditions, and ancillary facility conditions. The local booster equipment includes three secondary indicators: material and performance conditions, service life, and other.

[0044] Step 2: Establish the hierarchical discrimination matrix

[0045] Based on the AHP analysis method, a judgment matrix is ​​constructed for n indicators at the same level:

[0046] A={α ij}n*n

[0047] In the formula, α ij This indicates the importance of indicator i relative to indicator j, and α ji =1 / α ij ;

[0048] Based on the target layer, criterion layer, and indicator layer of step 1, this embodiment constructs 10 hierarchical discrimination matrices. Taking the primary indicators of water supply system—water quality assurance, water pressure assurance, water quantity assurance, and automatic control—as examples, the hierarchical discrimination matrices are constructed as shown in Table 1. The hierarchical discrimination matrices for other primary and secondary indicators are similar.

[0049] Table 1. Criterion-level discrimination matrix

[0050] Water quality protection Water pressure guarantee Water supply guarantee Automatic control Water quality protection <![CDATA[a 11 ]]> <![CDATA[a 12 ]]> <![CDATA[a 13 ]]> <![CDATA[a 14 ]]> Water pressure guarantee <![CDATA[a 21 ]]> <![CDATA[a 22 ]]> <![CDATA[a 23 ]]> <![CDATA[a 24 ]]> Water supply guarantee <![CDATA[a 31 ]]> <![CDATA[a 32 ]]> <![CDATA[a 33 ]]> <![CDATA[a 34 ]]> Automatic control <![CDATA[a 41 ]]> <![CDATA[a 42 ]]> <![CDATA[a 43 ]]> <![CDATA[a 44 ]]>

[0051] Step 3: Assign values ​​to the hierarchical discrimination matrix using Delphi experts.

[0052] Six experts were invited to assign values ​​to the judgment matrix. Taking the judgment matrix of the first-level indicators of the water supply system as an example, the values ​​assigned by the six experts are shown in Table 2 below.

[0053] Table 2 Expert Assignments

[0054]

[0055]

[0056] Step 4: Consistency check of the hierarchical discriminant matrix

[0057] For each expert's hierarchical discrimination matrix, find its largest eigenvalue and its corresponding eigenvector. After normalizing the eigenvector, the relative importance weight vector for the corresponding hierarchical single ranking can be obtained. Then, calculate the consistency index CI and consistency ratio CR according to the following formula:

[0058]

[0059] Where, λ max is the largest eigenvalue of the matrix, and n is the order of the matrix; RI is the average random consistency index, which is related to the order and is taken from the values ​​in Table 3 below. When CR < 0.1, the consistency of the comparison judgment matrix can be considered acceptable; otherwise, it should return to step 3 for experts to make appropriate corrections to the judgment matrix that failed the consistency test. The weight vector, eigenvalue, consistency index, and consistency ratio of the aforementioned primary indicators of the water supply system are calculated as shown in Table 3 below.

[0060] Table 3. Calculation Table of Weight Vector, Eigenvalue, Consistency Index, and Consistency Ratio

[0061] matrix Weight vector of hierarchical single sorting <![CDATA[λ max ]]> CI RI CR Expert 1 <![CDATA[(0.167,0.333,0.333,0.167) T ]]> 4 0 0.94 0 Expert 2 <![CDATA[(0.364,0.182,0.364,0.091) T ]]> 4 0 0.94 0 Expert 3 <![CDATA[(0.362,0.163,0.326,0.148) T ]]> 4.021 0.007 0.94 0.007 Expert 4 <![CDATA[(0.048,0.643,0.101,0.208) T ]]> 4.174 0.058 0.94 0.062 Expert 5 <![CDATA[(0.618,0.136,0.200,0.045) T ]]> 4.265 0.088 0.94 0.094 Expert 6 <![CDATA[(0.638,0.151,0.151,0.060) T ]]> 4.050 0.017 0.94 0.018

[0062] All experts in the table have CR values ​​less than 0.1, which meets the consistency requirements.

[0063] Step 5: Calculate the mean, median, and mode of each element in the hierarchical discriminant matrix, and provide feedback to experts to determine whether adjustments to the hierarchical discriminant matrix are needed. The mean is the weighted average of the scores assigned by m experts, denoted as:

[0064]

[0065] The median value is the middle value among the m expert scores, denoted as . The mode is the value that is most frequently repeated among the scores assigned by m experts. If the experts receive the mean, median, and mode and need to adjust them, repeat step 4; otherwise, proceed to step 6.

[0066] The average, median, and mode of each element in the aforementioned primary indicator matrix of the water supply system are shown in Table 4 below.

[0067] Table 4. Matrix Mean, Median, and Mode

[0068]

[0069] In this embodiment, the expert example is not adjusted, so we proceed directly to step 6.

[0070] Step 6: Calculate the average value of the weight vector of each indicator in the expert level discrimination matrix, and use it as the final weight value w of the indicator;

[0071] Based on m experts, m*10 level discrimination matrices A were finally determined. m*10 For each level of the discrimination matrix, calculate the weight vector of each indicator according to step 4, denoted as w. j The final weight value is obtained by taking a weighted average of the weight vectors of each indicator:

[0072]

[0073] In this embodiment, the average weight is the average weight vector in Table 3. Therefore, the weights of the four primary indicators of the water supply system—water quality assurance, water pressure assurance, water quantity assurance, and automatic control—are 0.366, 0.268, 0.246, and 0.120, respectively.

[0074] Similarly, the weight values ​​of all indicators in all criteria and indicator layers can be calculated. The weight values ​​of all indicators obtained by following the above steps are shown in Table 5 below.

[0075] Table 5 Weighting Table of Evaluation Index System for Secondary Water Supply Facilities

[0076]

[0077]

[0078] Step 7: Calculate the total score for secondary water supply facilities

[0079] The total score for each indicator is set at 10 points. The score for each indicator is obtained by scoring according to the condition of the secondary water supply facilities. The total score for the safety risk assessment of the secondary water supply facilities in the community is obtained by multiplying the score of each indicator by the weight value w determined in step 6.

[0080] This example uses a 24-story high-rise residential community as an example. The water supply system is a combination of pump and water tank supply, with the top two floors using a localized pressurization system. The secondary water supply facilities include a pump room, building water supply risers and ancillary facilities, and a rooftop water tank and ancillary facilities. An example of scoring these facilities is as follows:

[0081] (1) Water supply system:

[0082] 1.1) Water quality assurance score: This community should have set up pollution return measures according to regulations but did not. Although the water quality test report indicators are qualified, there are water quality complaint work orders, etc., so the score is 0 points;

[0083] 1.2) Water Pressure Guarantee Score: The residential building is a 24-story high-rise with a rooftop water tank supply. However, the zoned water supply pressure exceeds 0.35 MPa, and no branch pipe pressure reducing system is installed. The water pressure at residents' taps is greater than 0.2 MPa. Therefore, the water pressure guarantee score is 0 points.

[0084] 1.3) Water supply guarantee score: The community's pipe network is equipped with a master meter and sub-meters, the pipe network leakage rate is calculated to be 2%, which meets the requirements, and there are no complaints about insufficient water supply. This item is worth 10 points.

[0085] 1.4) Automatic control score: The community water pump adopts an automatic water supply method, which mainly uses the water tank level to link the water pump to supply water, thus realizing the automatic water supply function. Therefore, the score is 10 points.

[0086] Overall score for water supply system:

[0087] A=0.366*0+0.268*0+0.246*10+0.120*10=3.66

[0088] (2) Pump room:

[0089] 2.1) Water Pump Unit: The cast iron pump exhibits rust, leakage, and poor performance, resulting in a material and performance score of 0. Its service life exceeds 15 years, earning a service life score of 0. There are no other non-compliance with national and local standards, therefore, the overall score is 10. Final comprehensive score for the water pump unit:

[0090] B1=0.546*0+0.237*0+0.217*10=2.17

[0091] 2.2) Pipe fittings: The pipes are made of galvanized steel pipes, and the valves are cast iron valves. The pipes and valves are rusted, which indicates poor working conditions and scores 0.

[0092] 2.3) Water Storage Tank: Concrete tank with detached internal tiles; the building structure itself is used as the tank walls and roof, indicating poor material quality and performance, resulting in 0 points. Manholes, overflow, and venting facilities meet specifications and are in good working condition; however, the overflow lacks an insect screen, earning 8 points. Overall score for the water storage tank:

[0093] B2 = 0.753 * 0 + 0.247 * 8 = 1.976

[0094] 2.4) Electrical facilities: The electrical facilities basically meet the requirements of national and local standards, but some facilities are in poor working condition, resulting in an overall score of 6 points;

[0095] 2.5) Environmental hygiene: There are no pollution sources around the pump room, the underground pump room is equipped with ventilation measures, the pump room lighting is good, the drainage facilities are good, and the noise meets the relevant requirements. The overall score is 8 points.

[0096] The final overall score for the pump station is:

[0097] B=0.328*0+0.117*0+0.191*1.976+0.219*6+0.145*8=2.85

[0098] (3) Building water supply pipes and ancillary facilities:

[0099] 3.1) Building water supply pipes: The material is steel-plastic composite pipe, and the performance is good, scoring 9 points for material and performance; the service life exceeds 25 years, scoring 0 points; the laying location is in a public pipe shaft, scoring 10 points; the overall score is:

[0100] C1=0.42*9+0.237*0+0.344*10=7.22

[0101] 3.2) Freeze protection and insulation: Since the pipeline is located inside the pipe well, no insulation is required, so it gets 10 points;

[0102] 3.3) Valve fittings: Localized corrosion on the valve, 8 points;

[0103] 3.4) Water meter: The water meter is located in the pipe well, which is convenient for meter reading and maintenance, and it is a smart water meter, so it gets 10 points.

[0104] Overall score for building water supply pipes and ancillary facilities:

[0105] C=0.335*7.22+0.176*10+0.251*8+0.238*10=8.57

[0106] (4) Rooftop water tank and ancillary facilities:

[0107] 4.1) Rooftop water tank: The tank is made of 304 stainless steel, and its material and performance are in good condition, scoring 8 points; the manhole, overflow, venting and other auxiliary facilities meet the specifications and are in good condition; the overflow is not equipped with an insect screen, scoring 8 points; Overall score for the rooftop water tank:

[0108] D1 = 0.699 * 8 + 0.301 * 8 = 8

[0109] 4.2) Local booster equipment: Made of stainless steel, with good performance and operating conditions, scoring 9 points for material and performance; service life of 5 years, scoring 10 points for service life; other aspects, including installation location, noise, and environment, all meet national and local standards, scoring 10 points. The overall score for the local booster equipment is:

[0110] D2=0.49*9+0.229*10+0.282*10=9.52

[0111] 4.3) Antifreeze and heat preservation: The roof water tank and local pressurization equipment are located in the roof water tank room, and the heat preservation is good, so it gets 10 points directly.

[0112] Overall score for rooftop water tanks and ancillary facilities:

[0113] D=0.514*8+0.238*9.52+0.248*10=8.86

[0114] Overall score of the community's secondary water supply facilities assessment:

[0115] Q=0.238*3.66+0.317*2.85+0.151*8.57+0.204*8.86=4.88

[0116] Step 8: Determine the safety risk level of the community's secondary water supply facilities

[0117] The safety risks of secondary water supply facilities are classified into levels I to V. Level V is defined as a total score of 4 or less, which is a dangerous level; Level IV is defined as a total score of 4 or less and 6 or less, which is a high-risk level; Level III is defined as a total score of 6 or less and 7.5 or less, which is a medium-risk level; Level II is defined as a total score of 7.5 or less and 9 or less, which is a low-risk level; and Level I is defined as a total score of 9 or more, which is a safe level.

[0118] The aforementioned example community is classified as Level IV, which is a high-risk area; its water supply system and pump room both have safety hazards, and the overall risk is relatively high. It is recommended that timely renovations be carried out.

[0119] Example 2

[0120] Based on Example 1, the secondary water supply facilities in the community were evaluated without rooftop water tanks.

[0121] In accordance with steps 1 to 6 of Example 1, remove the rooftop water tank and ancillary facilities in the criterion layer and the relevant indicators in each indicator layer, and determine the weight values ​​using the AHP-Delphi analysis method.

[0122] Similarly, for communities without pump rooms, the weight values ​​can be determined by removing the pump rooms from the criteria layer and the relevant indicators from each indicator layer, as described in Example 1.

[0123] However, if a region has already performed a full weighting calculation for all indicators according to Example 1, it can also be applied to the evaluation of communities with only some secondary water supply facilities. The score can be calculated as follows: the ratio of the actual score of a certain indicator in the evaluated community to the total score of the scoring items applicable to the evaluated community reflects the relative score rate of the actual "water supply facilities" in the evaluated community to the theoretical total "water supply facilities". For example, in a variable frequency water supply community, the evaluation indicators only include three indicators: water supply system, pump room, indoor and outdoor water supply pipes and ancillary facilities. After removing the score of rooftop water tanks and ancillary facilities, the total score of the three indicators according to Table 5 in Example 1 is 7.96 points. If these three indicators are actually scored as 6 points, then the final comprehensive score is 6 / 7.96*10 = 7.54 points.

[0124] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for safety risk assessment of secondary water supply facilities, characterized by the following steps: include: Based on the AHP analysis method, a hierarchical model including the target layer, criterion layer and indicator layer is constructed from top to bottom, and a judgment matrix is ​​constructed for indicators at the same level. According to Delphi, multiple experts assigned and adjusted the hierarchical discriminant matrix until it passed the consistency test. The average value of the weight vector of each indicator in the expert level discrimination matrix is ​​used as the final weight value of the indicator. The total score of the secondary water supply facilities is calculated and the safety risk level of the secondary water supply facilities in the community is assessed.

2. The method for safety risk assessment of secondary water supply facilities according to claim 1, characterized in that, The hierarchical model described above takes the safety risk assessment index of secondary water supply facilities as its objective and uses water supply systems, pump rooms, building water supply pipelines and ancillary facilities, and rooftop water tanks and ancillary facilities as its criteria.

3. The method for safety risk assessment of secondary water supply facilities according to claim 2, characterized in that, The primary indicators of the water supply system include water quality assurance, water pressure assurance, water quantity assurance, and automatic control. The primary indicators of the pump room include pump units, water tanks / boxes, pipelines and valves, electrical facilities, and environmental sanitation. The primary indicators for building water supply pipes and ancillary facilities include building water supply pipes, valve fittings, water meters, and antifreeze insulation; The primary indicators for the rooftop water tank and its ancillary facilities include the rooftop water tank, local pressurization equipment, and antifreeze insulation.

4. The method for safety risk assessment of secondary water supply facilities according to claim 3, characterized in that, The secondary indicators of the water pump unit include material and performance conditions, service life, and others; The secondary indicators of the water tank / box include the material and performance conditions and the operating conditions of the auxiliary facilities; The secondary indicators of the building water supply pipes include material and performance conditions, service life and laying location; The secondary indicators of the rooftop water tank include the material and performance conditions and the operating conditions of the auxiliary facilities; The secondary indicators of the local booster equipment include material and performance conditions, service life, and others.

5. The method for safety risk assessment of secondary water supply facilities according to claim 1, characterized in that, The method constructs a judgment matrix for n indicators at the same level based on AHP analysis, as follows: A={a ij }n*n In the formula, α ij α represents the importance of indicator i relative to indicator j. ji =1 / α ij .

6. The method for safety risk assessment of secondary water supply facilities according to claim 1, characterized in that, The consistency check of the hierarchical discrimination matrix is ​​specifically performed as follows: For each expert's hierarchical discrimination matrix, find its largest eigenvalue and its corresponding eigenvector. Normalize the eigenvectors to obtain the relative importance weight vector for the corresponding hierarchical single ranking, and calculate the consistency index (CI) and consistency ratio (CR). Where, λ max is the largest eigenvalue of the hierarchical discriminant matrix, n is the order of the hierarchical discriminant matrix; RI is the average random consistency index, which is related to the order of the hierarchical discriminant matrix; When the consistency ratio is less than the set threshold, the consistency of the comparison judgment matrix is ​​considered acceptable; otherwise, the judgment matrix that fails the consistency test will be corrected by experts.

7. The method for safety risk assessment of secondary water supply facilities according to claim 6, characterized in that, The method calculates the mean, median, and mode of each element in the hierarchical discriminant matrix and feeds back to experts to determine whether the hierarchical discriminant matrix needs to be adjusted. If adjustment is required, the method returns to repeat the consistency check of the hierarchical discriminant matrix; otherwise, it outputs the final expert hierarchical discriminant matrix.

8. The method for safety risk assessment of secondary water supply facilities according to claim 1, characterized in that, The method calculates the final weight value by weighting the weight vector of each indicator based on the final determined hierarchical discrimination matrix, and calculates the weight values ​​of all indicators in all criterion layers and indicator layers.

9. The method for safety risk assessment of secondary water supply facilities according to claim 1, characterized in that, The method classifies the safety risks of secondary water supply facilities into multiple levels based on the total score of the safety risk assessment. A total score of 4 or less is Level V, which is a dangerous level; a total score of 4 or more but less than or equal to 6 is Level IV, which is a high-risk level; and a total score of 6 or more but less than or equal to 7.5 is Level III, which is a medium-risk level. A total score of 7.5 points or less and 9 points or less is Level II, which is a low-risk danger level; A total score greater than 9 points is Level I, which is a safety level.

10. The method for safety risk assessment of secondary water supply facilities according to claim 1, characterized in that, When evaluating communities with only some secondary water supply facilities, the method uses the ratio of the actual score of a certain indicator item of the evaluated community to the total score of the applicable indicator items to reflect the relative score rate of the actual water supply facilities of the evaluated community relative to the theoretical total water supply facilities.

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