A method for calculating safety risk value of concrete gravity dam during operation

Abstract

The present invention discloses a method for calculating the safety risk value of a concrete gravity dam during operation, which belongs to the field of water conservancy and hydropower engineering. First, the safety risk factors and risk events during the operation of the concrete gravity dam are determined, and the risk factor weight, risk event weight, monitoring point weight and dam section weight, as well as the severity level of the risk event are determined by means of a questionnaire; then, based on historical monitoring data and safety management needs, a risk factor evaluation standard table and a risk level standard table are established; finally, through multiple weighted averages, the risk factor possibility index, risk event possibility index, risk event risk value, risk value of each dam section, and overall engineering safety risk value are obtained in turn. The present invention can conduct a comprehensive quantitative evaluation of the operational safety status of the dam, and play an effective supporting role in the intelligent management and precise decision-making of engineering safety.

Description

Technical Field

[0001] The invention belongs to the field of water conservancy and hydropower engineering, and specifically relates to a method for calculating the safety risk value of a concrete gravity dam during operation. Background Art

[0002] Water conservancy hubs are important national infrastructures, undertaking engineering tasks such as water supply and power generation, flood and ice prevention, water and sand regulation, and playing an important role in promoting social, economic, and ecological benefits. Dams are the most important buildings in water conservancy hubs, usually used for water retention, water discharge, and water diversion for power generation. Dam safety directly affects the normal operation and even overall safety of the hub. Therefore, conducting safety assessments on dams during operation, accurately grasping the safety status of dams, and timely discovering and eliminating safety risks in dam operation are of great significance for ensuring the long-term and stable benefits of water conservancy hubs.

[0003] Concrete gravity dam is one of the main dam types at present, and is widely used in high dam and extra-high dam projects. According to the requirements of the specifications, the monitoring items of concrete gravity dams usually include: environmental quantity monitoring, deformation monitoring, seepage monitoring, stress strain and temperature monitoring. Under the current monitoring accuracy and analysis theory conditions, the monitoring quantities such as dam body deformation and dam foundation uplift pressure are usually used as the main control indicators of dam safety. For a single monitoring quantity, after obtaining the monitoring data through the automatic monitoring system, the analysis model such as multivariate regression is used for data fitting and variable separation. The absolute value, change rate and trend of the physical quantity are analyzed to make qualitative safety judgments and early warnings, and the scope of judgment and early warning is often targeted at a certain dam section or a part of the dam section. At present, there is a lack of comprehensive overall evaluation and quantitative evaluation methods.

[0004] On the other hand, digital engineering management is an inevitable trend. The current water conservancy industry is comprehensively promoting the construction of smart water conservancy. Based on the concept of digital twins, an intelligent engineering safety management and control business application system is created. From data collection, model analysis to safety assessment, an automated analysis process is constructed throughout the process to improve the accuracy and timeliness of engineering safety forecasts and warnings. In the safety assessment process, a safety risk quantitative evaluation method with solid theory, clear logic, and easy programming is urgently needed. Summary of the invention

[0005] In view of the shortcomings of existing dam safety assessments that lack overall and quantitative analysis, the present invention proposes a method for calculating the safety risk value of a concrete gravity dam during operation. It comprehensively considers multiple risk factors such as dam body deformation, dam foundation uplift pressure, anti-sliding stability, multiple risk events such as overall instability and stress failure, and different dam sections such as water retaining, water discharge, and power generation, and derives a comprehensive overall safety risk value. It can conduct a specific quantitative evaluation of the operational safety status of the dam, and provide effective support for intelligent management of engineering safety and precise decision-making.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] S1. Dam body deformation, dam foundation uplift pressure and anti-sliding stability are regarded as risk factors affecting the safety of concrete gravity dams during operation, and overall instability and stress failure are regarded as risk events affecting dam safety. Risk factors are the causes that lead to the occurrence of risk events.

[0008] S2. A questionnaire survey group consisting of experts in the water conservancy industry, leaders of administrative departments, and power station operation and management personnel were formed to distribute questionnaires. Each person determined the risk factor weight, risk event weight, monitoring point weight, and dam section weight based on the accumulated engineering experience, water conservancy knowledge, and the actual engineering conditions such as the dam's operating boundary conditions, body structure characteristics, monitoring layout, operation and scheduling characteristics, and historical defect information. The details are as follows:

[0009] S2.1. Determine the weight coefficients of the two risk events of overall instability and stress failure in the safety evaluation of the concrete gravity dam during operation.

[0010] S2.2. Determine the weight coefficients of risk factors such as dam deformation, dam foundation uplift pressure, and anti-sliding stability in risk events such as overall instability and stress failure.

[0011] S2.3. Determine the weight coefficient of each section of the concrete gravity dam in the safety assessment.

[0012] S2.4. Determine the number and weight coefficient of deformation monitoring points arranged at the dam crest, dam body and dam foundation of each dam section one by one.

[0013] S2.5. Determine the number and weight coefficient of dam foundation uplift pressure monitoring points for each dam section one by one.

[0014] S3. Develop a consequence severity rating table based on the possible casualties, economic losses, water supply impact, ecological environment impact, social impact, etc. of the risk event. Using the same questionnaire survey method as step 2, the survey group determines the consequence severity level of the overall instability risk event and the consequence severity level of the stress failure risk event based on the specific installed capacity of the dam, reservoir capacity, downstream impact area, etc.

[0015] S4. Using the historical monitoring data of the dam, a multivariate regression equation was established, and the confidence interval method was adopted to formulate a standard table for judging the two risk factors of dam deformation and dam foundation uplift pressure.

[0016] S4.1. Based on the historical monitoring data of each monitoring point, a multiple regression equation is established one by one, as shown in formula (1). The measured water head in front of the dam at different times in history, the cumulative number of observation days and the measured deformation value of the monitoring point at the corresponding time are input into formula (2). The regression coefficient of the multiple regression equation can be determined by data fitting:

[0017]

[0018] Where: d is the measured deformation value of the deformation monitoring point, is the regression coefficient of the water head component, H is the water head; t is the cumulative number of days from the displacement observation day to the start monitoring day; b 1i , b 2i is the regression coefficient of temperature component; c 1 、c 2 、c 3 is the regression coefficient of the time-dependent deformation component;

[0019] S4.2. For each deformation monitoring point, according to the regression coefficient of the multivariate regression equation determined in S4.1, the measured dam head and the cumulative number of observation days at different historical times are input into the right side of formula (2) to obtain the fitting value of the deformation monitoring point at different historical times;

[0020]

[0021] Where: d′ is the fitting value of the dam deformation monitoring point, and the other variables are the same as formula (1);

[0022] S4.3. For each deformation monitoring point, subtract the measured deformation value d from the fitted value d′ at different historical moments to obtain a residual data series, calculate the standard deviation S of the data series, and on this basis formulate a standard table for judging the risk factor of dam body deformation;

[0023] S4.4. Use the same method as S4.1 to S4.3 to determine the risk factor evaluation standard table for the dam foundation uplift pressure monitoring points;

[0024] S5. According to the size of the anti-sliding stability coefficient of each dam section, a standard table for judging the anti-sliding stability risk factor is drawn up.

[0025] S6. Using the same questionnaire survey method as step 2, the survey group divides the risk value into four intervals: safety, first-level warning, second-level warning, and third-level warning according to the specific operational safety management needs of the dam, and obtains a risk level standard table.

[0026] S7. Calculate the safety risk value at a certain moment in the dam operation process based on the risk factors, risk events, risk weights, dam section weights, monitoring point weights, severity of risk event consequences, risk factor evaluation criteria table, risk level evaluation criteria table, etc. determined in S1 to S6. The specific steps are as follows:

[0027] S7.1. According to the dam deformation risk factor evaluation standard table determined in S4, determine the probability index of abnormality at each deformation monitoring point.

[0028] S7.2. Determine the probability index of abnormal deformation in each dam section based on the probability index of deformation monitoring points under the dam section.

[0029] S7.3. Determine the probability index of abnormal foundation uplift pressure in each dam section by referring to the methods in S7.1 to S7.2.

[0030] S7.4. According to the anti-sliding stability risk factor evaluation standard table determined in S5, determine the probability index of the existence of anti-sliding stability anomaly in each dam section.

[0031] S7.5. Based on S7.1 to S7.4, calculate the probability index of overall instability and the probability index of stress failure for each dam section.

[0032] S7.6. On the basis of S7.5, multiply it by the severity level of the consequences of the risk event determined in S3 to calculate the risk value of overall instability and stress failure of each dam section.

[0033] S7.7. The overall instability risk value and stress failure risk value of each dam section are calculated according to S7.6. The weight coefficient of the risk event determined in S2 is used to calculate the risk value of each dam section through weighted average.

[0034] S7.8. The risk value of each dam section is calculated according to S7.7. The weight coefficient of each dam section determined by S2 is used to calculate the overall risk value of the dam through weighted average. The safety status of the dam can be further determined according to the risk level standard table determined by S6.

[0035] The beneficial effects of the present invention are:

[0036] 1. Traditional dam safety assessment usually evaluates a single monitored physical quantity and a single dam section separately and isolates them from each other. The present invention provides an overall assessment method that comprehensively considers multiple monitored physical quantities and multiple dam sections.

[0037] 2. Traditional dam safety assessments often produce qualitative results that lack specific quantitative indicators. The present invention provides a method for calculating specific quantitative indicators that can more accurately reflect the safety status of the dam and facilitate decision-making by operation and management personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0039] Figure 1 The present invention provides a flow chart of a method for calculating the safety risk value of a concrete gravity dam during operation. DETAILED DESCRIPTION

[0040] The Wanjiazhai Water Conservancy Project is located on the main stream of the Yellow River in Pianguan County, Shanxi Province. The dam is a concrete gravity dam with a height of 90 meters and an axis length of 440 meters, which is divided into 22 dam sections. The following is a specific example of the Wanjiazhai concrete gravity dam (hereinafter referred to as the Wanjiazhai Dam) to further explain the present invention in detail:

[0041] Step 1: Take dam body deformation, dam foundation uplift pressure and anti-sliding stability as risk factors affecting the safe operation of Wanjiazhai Dam, and take overall instability and stress failure as risk events affecting the safety of Wanjiazhai Dam. Risk factors are the causes that lead to the occurrence of risk events.

[0042] Step 2: A total of 10 people, including experts in the water conservancy industry, leaders of administrative departments, and power station operation and management personnel, formed a questionnaire survey group and distributed questionnaires. Each person determined the risk factor weight, risk event weight, monitoring point weight, and dam section weight based on the accumulated engineering experience, water conservancy knowledge, and the actual engineering conditions such as the operation boundary conditions, body structure characteristics, monitoring layout, operation and scheduling characteristics, and historical defect information of the Wanjiazhai Dam. Based on the 10 questionnaires, the arithmetic average method was used to finally determine the weight coefficient as follows:

[0043] 1) Determine the weight coefficients of the two risk events of overall instability and stress failure in the safety of Wanjiazhai Dam, as shown in Table 1. The sum of the weight coefficients of the two risk events is 1.

[0044] Table 1 Weight coefficients of risk events

[0045]

[0046] 2) Determine the weight coefficients of risk factors such as dam deformation, dam foundation uplift pressure, and anti-sliding stability in risk events such as overall instability and stress failure, as shown in Table 2. In each risk event, the sum of the weight coefficients of the risk factors is 1.

[0047] Table 2 Weight coefficients of risk factors

[0048]

[0049]

[0050] 3) Determine the weight coefficients of the 22 dam sections of Wanjiazhai Dam, as shown in Table 3. The sum of the risk weight coefficients of the 22 dam sections is 1.

[0051] Table 3 Weight coefficients of each dam section

[0052] Dam section number Dam section 1 Dam section 2 Dam section 3 Dam section 4 Dam section 5 Dam section 6 Dam section 7 Dam section 8 Weight coefficient 0.045 0.045 0.045 0.045 0.045 0.045 0.045 0.045 Dam section number Dam section 9 Section 10 Dam section 11 Dam section 12 Dam section 13 Section 14 Section 15 Section 16 Weight coefficient 0.045 0.045 0.055 0.045 0.045 0.045 0.045 0.045 Dam section number Section 17 Section 18 Section 19 Section 20 Section 21 Dam section 22 Weight coefficient 0.045 0.045 0.045 0.045 0.045 0.045

[0053] 4) For the 22 dam sections of Wanjiazhai Dam, the number and weight coefficients of deformation monitoring points arranged at the dam crest, dam body and dam foundation of each dam section are shown in Table 4. The sum of the weight coefficients of the deformation monitoring points under each dam section is 1.

[0054] Table 4 Weight coefficients of deformation monitoring points under each dam section

[0055]

[0056]

[0057] 5) For the 22 dam sections of Wanjiazhai Dam, the number and weight coefficients of the dam foundation uplift pressure monitoring points for each dam section are shown in Table 5. The sum of the weight coefficients of the dam foundation uplift pressure monitoring points under each dam section is 1.

[0058] Table 5 Weight coefficients of deformation monitoring points under each dam section

[0059]

[0060]

[0061] Step 3: Based on the possible casualties, economic losses, water supply impact, ecological environment impact, social impact, etc. caused by the risk event, a consequence severity level table is developed, as shown in Table 6. Using the same questionnaire survey method as step 2, the survey group determined the consequence severity level of the overall instability risk event as 5 and the consequence severity level of the stress damage risk event as 3 based on the specific installed capacity, reservoir capacity, and downstream impact area of ​​the Wanjiazhai Dam.

[0062] Table 6 Severity level of risk event consequences

[0063]

[0064] Step 4: Using the historical monitoring data of Wanjiazhai Dam, a multivariate regression equation was established, and the confidence interval method was used to formulate a standard table for the two risk factors of dam deformation and dam foundation uplift pressure, as follows:

[0065] 1) For all 74 deformation monitoring points of Wanjiazhai Dam, a multivariate regression equation is established one by one according to the historical monitoring data of each monitoring point, as shown in formula (1). The measured dam head at different times in history, the cumulative number of observation days and the measured deformation value of the monitoring point at the corresponding time are input into formula (1). The regression coefficient of the multivariate regression equation can be determined by data fitting.

[0066]

[0067] Where: d is the measured deformation value of the deformation monitoring point, is the regression coefficient of the water head component, H is the water head. t is the cumulative number of days from the displacement observation day to the start monitoring day; b 1i , b 2i is the regression coefficient of the temperature component. 1 、c 2 、c 3 is the regression coefficient of the time-dependent deformation component.

[0068] 2) For each deformation monitoring point, according to the regression coefficient of the multivariate regression equation determined in 1), the measured dam head and the cumulative observation days at different historical times are input into the right side of formula (2), and the fitting value of the deformation monitoring point at different historical times can be obtained.

[0069]

[0070] Where: d′ is the fitting value of the dam deformation monitoring point, and the other variables are the same as formula (1).

[0071] 3) For each deformation monitoring point, the measured deformation value d at different historical moments is subtracted from the fitted value d′ to obtain a residual data series. The standard deviation S of the data series is calculated. On this basis, a standard table for judging the risk factor of the dam body deformation of Wanjiazhai Dam can be formulated, as shown in Table 7.

[0072] Table 7 Evaluation criteria for dam deformation risk factors

[0073]

[0074] 4) Using the same method as 1) to 3), the risk factor evaluation standard table for 56 dam foundation uplift pressure monitoring points of Wanjiazhai Dam can be determined, as shown in Table 8, where p is the measured dam foundation uplift pressure and p′ is the fitting value at the corresponding time.

[0075] Table 8 Evaluation criteria for dam foundation uplift pressure risk factors

[0076]

[0077]

[0078] Step 5: Prepare a standard table for judging the anti-sliding stability risk factor. According to the anti-sliding stability coefficient of each dam section, the possibility index of abnormal anti-sliding stability is divided into five levels, as shown in Table 9.

[0079] Table 9 Anti-sliding stability risk factor evaluation criteria

[0080] Qualitative assessment of risk occurrence Likelihood Index Judgment basis There is a high probability of an abnormality 5 Anti-slip stability safety factor is less than 1.0 There may be anomalies 4 Anti-slip stability safety factor greater than 1.0 and less than 2.0 There is basically no possibility of abnormality 3 Anti-slip stability safety factor greater than 2.0 and less than 3.0 No abnormality is possible 2 The anti-slip stability safety factor is greater than 3.0 and less than 4.0 Very unlikely to be abnormal 1 Anti-slip stability safety factor greater than 4.0

[0081] Step six, since the possibility index of risk factors and the severity level of consequences of risk events are both integers between 1 and 5, the risk value obtained by multiplying the possibility index by the severity level of consequences and then performing weighted average calculation step by step is a number between 1 and 25. The same questionnaire survey method as step two is used. The survey group divides the risk value into four intervals: safety, first-level warning, second-level warning, and third-level warning according to the needs of safe operation and control of Wanjiazhai Dam, and obtains a standard table of risk levels, as shown in Table 10.

[0082] Table 10 Risk level standard table

[0083] Risk Amount [1,15] (15,20] (20,23] (23,25] Risk Level Safety Level 1 warning Second level warning Level 3 warning

[0084] Step 7: Calculate the safety risk value of Wanjiazhai Dam at a certain moment in its operation process based on the risk factors, risk events, risk weights, dam section weights, monitoring point weights, severity of risk event consequences, risk factor evaluation criteria table, and risk level evaluation criteria table determined in steps 1 to 6. The specific steps are as follows:

[0085] 1) Using the method in step 4, determine the measured value and fitted value of each dam deformation monitoring point at that moment one by one, and determine the probability index of abnormality at each monitoring point according to the dam deformation risk factor evaluation standard table;

[0086] 2) For each dam section, the weight coefficient δ of the deformation monitoring point determined in step 2 is 测点 , and the probability index P of the abnormality of the monitoring point determined in step 7 1) 测点 According to formula (3), the weighted average of the deformation monitoring points under it can be calculated to obtain the probability index P of abnormal deformation in each dam section. 坝段 , as shown in Table 11.

[0087] P 坝段 =∑δ 测点 P 测点 (3)

[0088] Table 11 Probability index of abnormal deformation in each dam section

[0089] Dam section number Dam section 1 Dam section 2 Dam section 3 Dam section 4 Dam section 5 Dam section 6 Dam section 7 Dam section 8 Likelihood Index 5.00 3.00 2.50 4.20 3.00 2.67 3.33 2.34 Dam section number Dam section 9 Section 10 Dam section 11 Dam section 12 Section 13 Section 14 Section 15 Section 16 Likelihood Index 2.34 2.88 2.68 2.68 3.67 3.67 3.67 3.67 Dam section number Section 17 Section 18 Section 19 Section 20 Section 21 Dam section 22 Likelihood Index 3.67 2.68 3.00 3.00 2.50 3.00

[0090] 3) Referring to the methods in 1) to 2), determine the possibility index of abnormal dam foundation uplift pressure in each dam section, as shown in Table 12.

[0091] Table 12 The probability index of abnormal dam foundation uplift pressure in each dam section

[0092] Dam section number Dam section 1 Dam section 2 Dam section 3 Dam section 4 Dam section 5 Dam section 6 Dam section 7 Dam section 8 Likelihood Index 0.00 2.25 3.00 2.00 2.00 2.00 2.00 2.00 Dam section number Dam section 9 Section 10 Dam section 11 Dam section 12 Section 13 Section 14 Section 15 Section 16 Likelihood Index 2.00 2.00 2.12 2.00 2.00 2.50 2.00 2.00 Dam section number Section 17 Section 18 Section 19 Section 20 Section 21 Dam section 22 Likelihood Index 2.00 2.00 2.00 2.14 2.00 0.00

[0093] 4) According to the provisions of the concrete gravity dam design code, calculate the anti-sliding stability coefficient of each dam section, and determine the possibility index of anti-sliding stability anomaly in each dam section according to the anti-sliding stability risk factor evaluation standard table determined in step 5, as shown in Table 13.

[0094] Table 13 Probability index of abnormal anti-sliding stability in each dam section

[0095] Dam section number Dam section 1 Dam section 2 Dam section 3 Dam section 4 Dam section 5 Dam section 6 Dam section 7 Dam section 8 Likelihood Index 1.00 1.00 2.00 2.00 2.00 2.00 2.00 2.00 Dam section number Dam section 9 Section 10 Dam section 11 Dam section 12 Section 13 Section 14 Section 15 Section 16 Likelihood Index 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 Dam section number Section 17 Section 18 Section 19 Section 20 Section 21 Dam section 22 Likelihood Index 1.00 1.00 1.00 1.00 1.00 1.00

[0096] 5) For each dam section, the probability index of overall instability and the probability index of stress failure of each dam section are calculated by weighted average based on the probability index of each risk factor calculated in 1) to 4) and the risk factor weight coefficient determined in step 2;

[0097] 6) Multiply the probability index of overall instability and stress failure of each dam section by the severity level of the consequences of overall instability and stress failure determined in step 3 to calculate the risk value of overall instability and stress failure of each dam section, as shown in Table 14.

[0098] Table 14 Risk values ​​of overall instability and stress failure of each dam section

[0099]

[0100]

[0101] 7) Based on step 6), the overall instability risk value and stress failure risk value of each dam section are calculated. The weight coefficient of the risk event determined in step 2 is used to calculate the risk value of each dam section through weighted average, as shown in Table 15.

[0102] Table 15 Risk values ​​of each dam section

[0103] Dam section number Dam section 1 Dam section 2 Dam section 3 Dam section 4 Dam section 5 Dam section 6 Dam section 7 Dam section 8 Likelihood Index 8.58 8.49 8.68 11.73 10.13 9.69 10.57 9.25 Dam section number Dam section 9 Section 10 Dam section 11 Dam section 12 Dam section 13 Section 14 Section 15 Section 16 Likelihood Index 7.32 7.22 7.92 7.77 9.09 9.66 9.66 9.09 Dam section number Section 17 Dam section 18 Section 19 Section 20 Section 21 Dam section 22 Likelihood Index 9.09 7.77 8.20 8.36 7.53 5.92

[0104] 8) Based on the weight coefficient of each dam section determined in step 2 and the risk value of each dam section, the overall risk value of Wanjiazhai Dam is calculated to be 8.73 through weighted average. According to the risk level standard table determined in step 6, the current state of Wanjiazhai Dam can be determined to be safe.

[0105] The above are preferred embodiments of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, are within the scope of protection of the present invention.

Claims

1. A method for calculating the safety risk value of a concrete gravity dam during operation, characterized in that: The following steps are involved: S1. Dam body deformation, dam foundation uplift pressure and anti-sliding stability are considered as risk factors affecting the safety of concrete gravity dams during operation, and overall instability and stress failure are considered as risk events affecting dam safety. Risk factors are the causes that lead to risk events. S2. Form a questionnaire survey group, distribute questionnaires separately, and each person determines the risk factor weight, risk event weight, monitoring point weight and dam section weight based on the accumulated engineering experience, water conservancy knowledge and the actual engineering situation of the dam; S3. Develop a severity ranking table based on the possible consequences of risk events; S4. Using the historical monitoring data of the dam, a multivariate regression equation was established, and the confidence interval method was used to formulate a standard table for judging the two risk factors of dam deformation and dam foundation uplift pressure; S4.

1. Based on the historical monitoring data of each monitoring point, a multiple regression equation is established one by one, as shown in formula (1). The measured water head in front of the dam at different times in history, the cumulative number of observation days and the measured deformation value of the monitoring point at the corresponding time are input into formula (1). The regression coefficient of the multiple regression equation can be determined by data fitting: Where: d is the measured deformation value of the deformation monitoring point, is the regression coefficient of the water head component, H is the water head; t is the cumulative number of days from the displacement observation day to the start monitoring day; b 1i 、b 2i is the regression coefficient of temperature component; c1, c2, c3 are the regression coefficients of aging deformation component; S4.

2. For each deformation monitoring point, according to the regression coefficient of the multivariate regression equation determined in S4.1, the measured dam head and the cumulative number of observation days at different historical times are input into the right side of formula (2) to obtain the fitting value of the deformation monitoring point at different historical times; Where: d′ is the fitting value of the dam deformation monitoring point, and the other variables are the same as formula (1); S4.

3. For each deformation monitoring point, subtract the measured deformation value d from the fitted value d′ at different historical moments to obtain a residual data series, calculate the standard deviation S of the data series, and on this basis formulate a standard table for judging the risk factor of dam body deformation; S4.

4. Use the same method as S4.1 to S4.3 to determine the risk factor evaluation standard table for the dam foundation uplift pressure monitoring points; S5. According to the anti-sliding stability coefficient of each dam section, a standard table for judging the anti-sliding stability risk factor is drawn up; S6. The survey group divides the risk value into four intervals: safety, first-level warning, second-level warning and third-level warning according to the specific operation safety control needs of the dam, and obtains a risk level standard table; S7. Calculate the safety risk value at a certain moment in the dam operation process based on the risk factors, risk events, risk weights, dam section weights, monitoring point weights, severity of risk event consequences, risk factor evaluation criteria table and risk level evaluation criteria table determined in S1 to S6; The specific steps of S7 are as follows: S7.

1. According to the dam deformation risk factor evaluation standard table determined in S4, determine the probability index of abnormality at each deformation monitoring point; S7.

2. Determine the probability index of abnormal deformation in each dam section based on the probability index of deformation monitoring points under the dam section; S7.

3. Determine the probability index of abnormal dam foundation uplift pressure in each dam section by referring to the methods in S7.1 to S7.2; S7.

4. Determine the probability index of the existence of abnormal anti-sliding stability in each dam section according to the anti-sliding stability risk factor evaluation standard table determined in S5; S7.

5. Based on S7.1 to S7.4, calculate the probability index of overall instability and the probability index of stress failure for each dam section; S7.

6. Based on S7.5, multiply it by the severity level of the consequences of the risk event determined in S3 to calculate the risk value of overall instability and stress failure of each dam section; S7.

7. Calculate the overall instability risk value and stress failure risk value of each dam section according to S7.6, and use the weight coefficient of the risk event determined in S2 to calculate the risk value of each dam section through weighted average; S7.

8. Calculate the risk value of each dam section according to S7.7, use the weight coefficient of each dam section determined in S2, and calculate the overall risk value of the dam through weighted average. Further determine the safety status of the dam according to the risk level standard table determined in S6.

2. A method for calculating the safety risk value of a concrete gravity dam during operation according to claim 1, characterized in that: The specific steps of S2 include the following: S2.

1. Determine the weight coefficients of the two risk events of overall instability and stress failure in the safety evaluation of concrete gravity dam during operation; S2.

2. Determine the weight coefficients of dam deformation, dam foundation uplift pressure, and anti-sliding stability risk factors in the overall instability and stress failure risk events; S2.

3. Determine the weight coefficient of each section of the concrete gravity dam in the safety assessment; S2.

4. Determine the number and weight coefficient of deformation monitoring points arranged at the dam crest, dam body and dam foundation of each dam section one by one; S2.

5. Determine the number and weight coefficient of dam foundation uplift pressure monitoring points for each dam section one by one.

3. A method for calculating the safety risk value of a concrete gravity dam during operation according to claim 1, characterized in that: The specific steps of S3 are as follows: A consequence severity grade table is developed based on the possible casualties, economic losses, water supply impacts, ecological environmental impacts and social impacts caused by risk events; a questionnaire survey is conducted, and the survey group determines the consequence severity grade of the overall instability risk event and the consequence severity grade of the stress failure risk event based on the specific installed capacity of the dam, reservoir capacity and downstream impact area.

Images