Deflection risk rate detection method for construction initial-middle stage of ultra-high core-wall rock-fill dam

Abstract

The invention relates to the technical field of water conservancy and hydropower engineering construction, discloses a method for detecting the initial-middle stage diversion risk rate of construction of an ultra-high core-wall rockfill dam, and aims to accurately and reasonably quantify the initial-middle stage diversion risk rate of construction of the ultra-high core-wall rockfill dam. Important theoretical basis and technical support are provided for hydropower engineering construction flood safety risk assessment, risk decision, construction diversion engineering design scheme optimization and the like in the planning and design stage. The method comprises the following steps: firstly, constructing a flood-fighting water-retaining elevation calculation model and a diversion risk mathematical model in the initial-middle stage of construction of the ultra-high core wall rock-fill dam, and determining distribution parameters of random factors through systematic analysis of dam filling rising randomness and parameter analysis of random factors of a construction flood process and diversion tunnel discharge capacity, and then, constructing a flood-fighting water-retaining elevation calculation model of the ultra-high core wall rock-fill dam in the initial-middle stage of construction of the ultra-high core wall rock-fill dam. Carrying out flow guide risk rate stochastic simulation calculation, and then carrying out preliminary optimization and sorting on the construction flow guide engineering design scheme of the ultra-high core wall rock-fill dam; and finally, carrying out risk judgment and adjustment on the design scheme of the construction diversion engineering of the ultra-high core-wall rockfill dam.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy and hydropower engineering construction, and in particular to a method for detecting diversion risk rate in the early and middle stages of construction of an ultra-high core rockfill dam. Background Art

[0002] During the construction of water conservancy and hydropower projects, construction diversion is one of the key links throughout the entire process of water conservancy and hydropower project construction. However, as a risky system, once the construction diversion system overflows and collapses, it will seriously affect the safety, progress and benefits of the project itself, and cause personal injury and property losses to the people downstream.

[0003] A number of 300m-class ultra-high core rockfill dams such as Shuangjiangkou, Lianghekou, and Rumei are under construction and planning in southwest China. Most of these ultra-high rockfill dams are built in the high mountain canyon areas of southwest China. Their construction diversion generally adopts a tunnel diversion method with cofferdams breaking the flow once and foundation pits constructed throughout the year. According to relevant specifications, the stage of using the upstream cofferdam to block water is the initial diversion stage; when the dam is filled beyond the cofferdam, the period of using the dam body to temporarily block water until the last batch of diversion buildings are closed is the mid-term diversion stage. Due to the long construction period, great construction difficulty, harsh construction environment, and obvious changes in construction floods, the safety issues of flood control during the entire construction process are very prominent. Scientific and reasonable quantitative estimation of the diversion risk rate of hydropower project construction can provide an important theoretical basis and technical support for subsequent construction flood control risk assessment, risk decision-making, risk allocation, design optimization, etc. Therefore, systematic research on the diversion risk of the entire process of ultra-high core rockfill dam construction from the initial to the mid-term has important theoretical significance and engineering application value.

[0004] In recent years, the theory and methods of diversion risk in ultra-high dam construction have been continuously developed and improved. For example, Zhang Chao et al.

[2019] systematically studied the diversion risk model and solution in the early and middle stages of high arch dam construction, but the model is mainly for ultra-high arch dams and is difficult to adapt to other dam types; Liu Lan et al.

[2013] considered the different risk and benefit preferences of contractors and owners, and constructed an evolutionary model of high rockfill dam construction flood control negotiation decision-making under time-varying conditions, but the model did not consider the randomness of the dam fill rise; Chen Li et al.

[2020] proposed a comprehensive evaluation method for the risks and benefits of the high dam early sluice gate storage scheme in order to seek the ideal time for sluice gate closure.

[0005] These studies have continuously enriched and developed the theoretical methods for construction diversion risk rate detection. However, the actual project is affected by many random factors such as the quality of construction personnel, construction management level, weather, material field mining, transportation, etc., and the height of the dam filling rise is obviously uncertain. However, the above risk models have failed to consider the uncertainty of the dam filling rise, which has a certain deviation from the actual filling of the project, resulting in inaccurate calculation of the construction flood risk rate.

[0006] In addition, Zhang Chao et al.

[2014] took into account the uncertainty of the flood control elevation of high rockfill dams and studied a method for predicting the mid-term flood risk of high rockfill dams at a key time point before the mid-term flood season. However, this model is only applicable to the estimation of mid-term flood risk at a key time point during the construction period and cannot fully reflect the flood risk during the entire diversion period. It is difficult to meet the needs of risk rate detection of ultra-high core rockfill dams during the engineering planning and design stage. Summary of the invention

[0007] The technical problems to be solved by the present invention are:

[0008] A method for detecting the diversion risk rate in the initial and mid-term construction of an ultra-high core rockfill dam is provided, aiming to accurately and reasonably quantify the diversion risk rate in the initial and mid-term construction of an ultra-high core rockfill dam, and to provide important theoretical basis and technical support for the safety risk assessment, risk decision-making, and optimization of construction diversion engineering design schemes for hydropower project construction during the planning and design stage.

[0009] The technical solution adopted by the present invention to solve the above technical problems is:

[0010] The method for detecting the diversion risk rate in the early and middle stages of construction of an ultra-high core rockfill dam includes the following steps:

[0011] S1. Construct a calculation model for the flood retaining elevation of the super-high core rockfill dam during the initial and intermediate stages of construction;

[0012] S2. Construct a mathematical model for diversion risk in the early and mid-term construction of ultra-high core rockfill dams;

[0013] S3. Conduct a systematic analysis of the randomness of dam filling rise and determine the distribution parameters of each random factor;

[0014] S4. Analyze the parameters of the random factors of the construction flood process and the discharge capacity of the diversion tunnel to determine the distribution parameters of each random factor;

[0015] S5. Carry out random simulation calculation of diversion risk rate in the early and middle stages of construction of ultra-high core rockfill dam;

[0016] S6. Conduct preliminary optimization and ranking of the design schemes for diversion engineering of ultra-high core rockfill dam construction;

[0017] S7. Conduct risk assessment and adjustment on the design scheme of diversion engineering for super-high core rockfill dam construction.

[0018] Furthermore, in step S1, the construction of a calculation model for the flood-retaining elevation of an ultra-high core rockfill dam during the initial and intermediate stages of construction includes:

[0019] The diversion period from the initial to the middle stage of facility construction is t d Years, of which the initial diversion period is t cThe mid-term diversion period is 1 year, which is the tth year of the mid-term diversion. d If the dam filling elevation exceeds the cofferdam elevation before the main flood season of that year, then the diversion t in the early and middle stages of construction is d In the year, the water retaining elevation Z of the core rockfill dam during the initial and intermediate flood seasons before the main flood season in the jth year dj The calculation model is:

[0020]

[0021] Among them, Z W Z is the initial flood retaining elevation, i.e. the elevation of the top of the upstream cofferdam; sj It is the water retaining elevation for the mid-term flood season.

[0022] Furthermore, in step S2, the construction of a mathematical model for diversion risk in the early and mid-term construction of an ultra-high core rockfill dam includes:

[0023] The diversion risk in the initial and middle stages of construction of ultra-high core rockfill dam is defined as the probability of the highest flood level in the main flood season exceeding the flood retaining elevation during the initial and middle stages of construction. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the mathematical model of the dynamic risk R of the diversion in the initial and middle stages of construction of ultra-high core rockfill dam is established as follows:

[0024]

[0025] Among them, Z Hj (t) is the dynamic change process of the water level of the reservoir in front of the dam for flood control in the jth year; S T is the design parameter of the diversion tunnel, Z W is the design elevation of the upstream cofferdam; P() is the probability calculation; [S T ,Z W ] is S T and Z W The relationship matrix of

[0026] The initial diversion risk of construction is defined as the probability that the highest flood level in the main flood season exceeds the elevation of the upstream cofferdam top within the initial diversion period of construction, which represents the ability of the upstream cofferdam to resist the construction flood process during the main flood season within the initial diversion period. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the initial diversion risk R of ultra-high core rockfill dam construction is established. W The mathematical model is:

[0027] R W =P(max(Z Hj (t))>Z W |[S T ,Z W ]), where j = 1, 2, ..., t c

[0028] The mid-term diversion risk of construction is defined as the probability that the highest flood level during the main flood season exceeds the flood retaining elevation of the dam within the mid-term diversion period of construction. It represents the ability of the temporary dam with fill rising above the cofferdam elevation during the mid-term diversion period to resist the construction flood process during the main flood season. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the mid-term diversion risk R of ultra-high core rockfill dam construction is established. D The mathematical model is:

[0029]

[0030] in, For the tth d Dynamic changes in water level of the reservoir in front of the dam for flood control in 2017.

[0031] Furthermore, in step S3, the randomness of the dam filling rise is systematically analyzed to determine the distribution parameters of each random factor, including:

[0032] The calculation model of the dam core wall filling elevation in the kth month of the initial and intermediate construction period

[0033] where k = 1, 2, ..., t d ×12

[0034] The daily average rise speed H of the core wall of the core rockfill dam vi and the dam filling suspension days index T si The impact of the dam filling suspension days index T si It follows a normal distribution;

[0035] The average daily rise speed of the dam core wall is H vi It obeys the triangular distribution, and its probability density function is:

[0036]

[0037] Among them, h d is the lower limit, i.e. the slowest daily average rising speed; h m is the median value, i.e. the most likely daily average rising speed; h u is the upper limit, i.e. the fastest daily average rising speed.

[0038] Furthermore, in step S4, the parameter analysis of the random factors of the construction flood process and the discharge capacity of the diversion tunnel is performed to determine the distribution parameters of each random factor, including:

[0039] The random factors of the construction flood process and the discharge capacity of the diversion tunnel need to consider the randomness of the peak flow of the construction flood, the randomness of the water level-reservoir capacity relationship, and the randomness of the discharge capacity flow coefficient. The peak flow of the construction flood is set to satisfy the P-III distribution, and the reservoir capacity relationship coefficient and the discharge capacity coefficient are assumed to obey the triangular distribution.

[0040] Furthermore, in step S5, the random simulation calculation of the diversion risk rate in the early and middle stages of the construction of the ultra-high core rockfill dam includes:

[0041] S51, input model-related calculation parameters;

[0042] S52, determine the total number of simulation calculations N of the model that meets the accuracy requirements C ;

[0043] S53, conduct a series of random simulations of flood retaining elevations during the initial and mid-term construction period:

[0044] ① Generate random numbers of the average daily rising speed of the dam core wall in each month during the construction period to simulate the average daily rising speed of the dam core wall;

[0045] ② Generate a random number of days for dam filling suspension in each month during the construction period, simulate the number of days for dam filling suspension in each month, and calculate the effective construction days in each month;

[0046] ③According to the simulated calculation of the dam filling elevation series, the total diversion years t in the early and middle stages of construction are obtained. d , the number of years of diversion period at the beginning of construction t c According to the simulation model, the annual flood water retaining elevation matrix [Z d1 , Z d2 ,……,Z td ];

[0047] S54. Conduct random simulation of the highest flood level in front of the dam for flood control:

[0048] ①Generate diversion period t d Random numbers of construction flood peaks in each year to simulate the construction flood process;

[0049] ②Generate diversion period t d The random number of the reservoir capacity relationship coefficient in each year is used to simulate and fit the water level capacity relationship curve;

[0050] ③Generate diversion period t d The random number of the discharge capacity coefficient of each year in the year is used to simulate and fit the diversion and discharge capacity curve;

[0051] ④ Obtain the diversion period t through simulation of flood control calculation d Matrix of the highest flood levels in front of the dams in each year

[0052] S55. Estimation of diversion risk rate based on random simulation results:

[0053] ① After N C Sampling simulation calculations and statistical analysis of the diversion period t in the early and middle stages of construction d The highest flood level in front of the dam in each year (max(Z Hj (t)), where j = 1, 2, …, t d The elevation of the dam before the main flood season is not more than Z dj , where j = 1, 2, ..., t d The number of times is recorded as N D , then the dynamic risk rate estimation formula of the initial-mid-term diversion of the ultra-high core rockfill dam is:

[0054]

[0055] ②After N C Sampling simulation calculations were performed to statistically analyze the initial diversion period t c The highest flood level in front of the dam during the year max(Z Hj (t)), where j = 1, 2, …, t c Exceeding the flood retaining elevation Z of the dam construction before the main flood season W The number of times is recorded as N W , then the initial diversion risk rate estimation formula of the ultra-high core rockfill dam is:

[0056]

[0057] ③After N C The sampling simulation calculation is performed to statistically analyze the tth time of the mid-term diversion period. d The highest flood level before the dam Exceeding the flood-proof elevation during the mid-term construction of the dam The number of times is recorded as N G , then the mid-term diversion risk rate estimation formula is:

[0058]

[0059] Furthermore, in step S6, the preliminary optimization and sorting of the design schemes for the construction diversion project of the ultra-high core rockfill dam includes:

[0060] S61. Comprehensively consider the project scale, construction arrangement, interception difficulty and hydrological conditions, and combine engineering experience to make preliminary design of diversion project dimensions;

[0061] S62. Design cofferdam size: H max The maximum height of the upstream cofferdam that can be completed in a dry season or the maximum height under anti-seepage requirements; Bmin The minimum hole width required for construction and transportation vehicles to pass through;

[0062] S63. Analyze the trend of direct investment in diversion projects: The corresponding relationship matrix between the diversion hole size and the cofferdam size is determined by hydraulic method [S T ,Z W ], initially drafting several diversion engineering design schemes, and obtaining the variation law of direct investment of diversion engineering and cofferdam height and diversion tunnel size under the conditions of satisfying relevant design constraints;

[0063] S64. Based on the changing patterns of direct investment in diversion projects, cofferdam height and diversion tunnel size, and taking the lowest direct investment in diversion projects as the criterion, recommend the best diversion project design scheme and rank the diversion project design schemes.

[0064] Furthermore, in step S7, the risk identification and adjustment of the design scheme for the diversion project of the ultra-high core rockfill dam construction includes:

[0065] Conduct risk assessment on the initially selected optimal diversion engineering design scheme. If it meets the design requirements, the initially selected optimal diversion engineering design scheme is the optimal design scheme. If it does not meet the design requirements, adopt the design scheme ranked last until the risk assessment requirements are met. Otherwise, continue to adopt the design scheme ranked last for risk assessment.

[0066] The specific methods for risk identification are as follows:

[0067] The risk criterion for diversion in the early stage of construction of ultra-high core rockfill dam is R W ≤R IB ,in is the diversion risk rate in the initial construction period of the ultra-high core rockfill dam, T IB is the flood return period corresponding to the initial diversion standard;

[0068] The risk judgment standard for mid-term diversion of super-high core rockfill dam construction is R D ≤R MB ,in is the initial diversion risk rate during the construction of the ultra-high core rockfill dam, T MB is the flood return period corresponding to the medium-term diversion standard.

[0069] The beneficial effects of the present invention are:

[0070] (1) The present invention establishes a calculation model for the flood retaining elevation during the initial and intermediate stages of construction, which better considers the important indicators that affect the dam filling rise and objectively reflects the actual process of transition from the cofferdam retaining stage to the dam retaining stage.

[0071] (2) The present invention provides an analysis method for the randomness of dam filling. On the basis of systematic analysis of the randomness of dam filling, the influence of hydrology, hydraulics and the randomness of dam filling is comprehensively considered. The proposed diversion risk model for the early and middle stages of construction of ultra-high core wall rockfill dam can comprehensively and reasonably detect the diversion risk rate of the entire process from the early to the middle stages of construction, which provides an important theoretical basis for further carrying out construction flood risk assessment, risk decision-making, risk allocation, etc.

[0072] (3) The present invention combines the requirements of current regulations and specifications to respectively calculate the diversion risk in the initial construction stage and the diversion risk in the mid-term, and then provides a risk identification method for the diversion engineering design scheme. The design risk identification of the preliminarily selected diversion engineering design scheme can be performed, and the diversion design scheme can be optimized. This overcomes the shortcomings of traditional risk detection technology and provides new technical support for the design optimization of the diversion engineering of the ultra-high core wall rockfill dam and the decision-making of the flood control plan in the engineering planning and design stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 The present invention is a flow chart of the method for detecting the diversion risk rate in the early and middle stages of the construction of a super-high core rockfill dam. DETAILED DESCRIPTION

[0074] The present invention provides a method for detecting the diversion risk rate in the early and middle stages of the construction of an ultra-high core rockfill dam, aiming to accurately and reasonably quantify the diversion risk rate in the early and middle stages of the construction of an ultra-high core rockfill dam, and to provide an important theoretical basis and technical support for the safety risk assessment, risk decision-making, and optimization of construction diversion engineering design schemes for hydropower engineering construction during the planning and design stages.

[0075] In specific implementation, the detection method process of the present invention is as follows Figure 1 As shown, it includes the following implementation steps:

[0076] S1. Construct a calculation model for the water retaining elevation during the initial and intermediate stages of construction of an ultra-high core rockfill dam:

[0077] In the engineering design stage, since the ultra-high core rockfill dam has extremely stringent requirements on filling quality, in order to reduce the uneven settlement of the dam body and ensure the filling quality of the ultra-high dam and facilitate construction, the dam generally requires the whole section to be leveled and balanced, and its rising speed is mainly controlled by the rising speed of the core wall. At the same time, without necessary special protection measures, water is not allowed to flow through the dam. When the dam filling elevation exceeds the cofferdam, the dam water retention is mainly controlled by the core wall elevation.

[0078] Therefore, during the initial and middle diversion stages of the construction of the ultra-high core rockfill dam, two situations may occur during the construction and flood control in each year:

[0079] ① When the elevation of the core wall of the dam body before the main flood season of a certain year does not exceed the elevation of the top of the upstream cofferdam, the upstream cofferdam is relied upon to retain water during the flood season, and the elevation of the upstream cofferdam is the elevation of the upstream cofferdam.

[0080] ② When the elevation of the dam core wall exceeds the elevation of the upstream cofferdam crest before the main flood season of a certain year, the dam is relied upon to retain water during the flood season, and the water-retaining elevation during the flood season is the filling elevation of the dam core wall.

[0081] According to domestic and foreign engineering experience and relevant specifications, the filling rise of the core wall rockfill dam is mainly affected by the daily average rising speed of the core wall and the number of days of suspension of dam filling. Therefore, during the project planning and design stage, the monthly average daily rising speed of the dam core wall and the number of days of suspension of dam filling are important technical indicators for construction planning and design. The diversion period from the initial to the middle stage of the facility construction is t d The calculation model for the dam core wall filling elevation in the kth month of the initial and middle stages of construction is:

[0082]

[0083] Where, T i is the number of construction days in the ith month; T si is the number of days that work needs to be stopped in the i-th month; H vi is the average daily rising speed of the dam core wall in the i-th month.

[0084] Diversion during the early and mid-term construction d During the year, the dam core wall filling elevation Z before the main flood season of each year sn The calculation model of the series is:

[0085] Z sn =f D (W P ), where n=1,2,…,t (2)

[0086] In the formula, f D () Simplified functional expression of the core wall filling elevation series of the dam body before the main flood season.

[0087] According to the design experience of similar ultra-high dam projects, the mid-term diversion period is generally 1 to 2 years, and the dam body filling in the second year exceeds the design water level, which can basically meet the design requirements of flood control and flood prevention. Therefore, combined with the focus of this study, the mid-term diversion only considers the flood prevention situation in the first year. Assume that the initial diversion period is t c Years, the mid-term diversion period is 1 year, then the tth d (t d =t c +1) is the year when the dam filling elevation exceeds the cofferdam elevation before the main flood season of that year. The diversion time t in the early and middle stages of construction is d In the year, the water retaining elevation Z of the core rockfill dam during the initial and intermediate flood seasons before the main flood season in the jth year dj The calculation model is:

[0088]

[0089] In the formula, Z W It is the initial flood retaining elevation, and also the elevation of the top of the upstream cofferdam; Z sj It is the water retaining elevation for the mid-term flood season.

[0090] S2. Constructing a mathematical model for diversion risk in the early and mid-term construction of ultra-high core rockfill dams:

[0091] Because the extra-high core rockfill dams are high and have large reservoirs, they are mostly built in the high mountain canyon areas of the southwest. The construction period is long and the construction is difficult. The flood storage function of the construction process during the main flood season is obvious. The construction diversion is subject to the combined influence of random factors such as hydrology, hydraulics, and dam filling rise, which contains risks. Once the highest flood level during the main flood season during the construction diversion period exceeds the construction flood retaining elevation, it will cause huge economic and social losses to the cofferdam or dam itself and the downstream. In addition, the extra-high core rockfill dams in the southwest canyon area have large dams and reservoirs, and the operation of the diversion tunnel runs through the early and middle diversion stages of construction. The scale of different diversion tunnels and upstream cofferdams will affect the diversion risk rate. Assume S T is the design parameter of the diversion tunnel, and the design elevation of the upstream cofferdam is Z W , then the design parameters of the diversion project are mainly [S T ,Z W Therefore, assuming that the highest flood level matrix of each year during the construction diversion period is [Z d1 , Z d2 ,……,Z td ], the present invention first defines the diversion risk of the super-high core rockfill dam in the early and middle stages of construction as the probability of the highest flood level in the main flood season exceeding the flood retaining elevation during the construction period. Considering the randomness of the dam filling rise, the time when the dam exceeds the cofferdam before the main flood season has a certain randomness, so the diversion period t c and t d In summary, taking into account the randomness of hydrology, hydraulics, and dam filling rise, the mathematical model of the dynamic risk R of diversion in the early and middle stages of construction of ultra-high core rockfill dam is established as follows:

[0092]

[0093] In the formula, Z Hj (t) is the dynamic change process of the water level of the reservoir in front of the dam during flood control in the jth year.

[0094] The initial diversion risk of construction is defined as the probability that the highest flood level during the main flood season exceeds the elevation of the upstream cofferdam top within the initial diversion period of construction. It mainly represents the ability of the upstream cofferdam to resist the construction flood process during the main flood season within the initial diversion period. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the initial diversion risk R of ultra-high core rockfill dam construction is established. W The mathematical model is:

[0095] R W =P(max(Z Hj (t))>Z W |[S T ,Z W ]), where j = 1, 2, ..., t c (5)

[0096] The mid-term diversion risk of construction is defined as the probability that the highest flood level during the main flood season exceeds the flood retaining elevation of the dam during the mid-term diversion period. It mainly represents the ability of the temporary dam with fill rising above the cofferdam elevation during the mid-term diversion period to resist the construction flood process during the main flood season. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the mid-term diversion risk R of ultra-high core rockfill dam construction is established. D The mathematical model is:

[0097]

[0098] S3. Conduct a systematic analysis of the randomness of the dam filling rise and determine the distribution parameters of each random factor:

[0099] The construction of the super-high core rockfill dam is affected by many complex factors such as site conditions, soil characteristics, construction management, construction machinery, material field mining, transportation, rainfall, temperature, etc. The average daily rise speed of the core wall of the dam in each month and the number of days of suspension of dam filling are obviously random. According to relevant research, the number of days of suspension of dam filling in each month is T si A normal distribution can be assumed.

[0100] According to the experience of similar projects at home and abroad and the statistical data of dam filling, under the necessary constraints, the number of daily filling layers of the dam core wall in each month generally varies within a certain range. In the engineering design stage, considering the characteristics that the daily average filling rise speed of the dam core wall in each month varies within a certain range, there is a slowest daily average rise speed, a fastest daily average rise speed, and a most likely daily average rise speed, indicating that its random characteristics are relatively close to the characteristics of triangular distribution. The present invention assumes that the daily average rise speed of the dam core wall in the i-th month H vi It obeys the triangular distribution, and its probability density function is:

[0101]

[0102] In the formula, h d is the lower limit, i.e. the slowest daily average ascent speed, also used as the daily minimum control ascent speed; h m is the median value, i.e. the most likely daily average rising speed; h u is the upper limit, i.e. the fastest daily average rising speed.

[0103] S4. Analyze the parameters of the random factors of the construction flood process and the discharge capacity of the diversion tunnel to determine the distribution parameters of each random factor:

[0104] Hydrological and hydraulic random factors mainly consider the randomness of construction flood peak flow, the randomness of water level-reservoir relationship, and the randomness of discharge capacity flow coefficient. The flood process in the main flood season in the southwestern mountainous area is characterized by steep rise and fall. The construction flood process mainly considers the randomness of the construction flood peak. According to the characteristics of my country's floods, the P-III distribution can better describe its randomness.

[0105] Based on similar project experience and related research results, the reservoir capacity relationship coefficient and discharge capacity coefficient are assumed to obey a triangular distribution.

[0106] S5. Carry out random simulation calculation of diversion risk rate in the early and mid-term construction of ultra-high core rockfill dam:

[0107] The specific implementation steps of this step include:

[0108] S51, input model-related calculation parameters;

[0109] S52, determine the total number of model simulation calculations N that meet the accuracy requirements C ;

[0110] S53, conduct a series of random simulations of flood retaining elevations during the initial and mid-term construction period:

[0111] ① Generate random numbers of the average daily rise speed of the dam core wall in each month during the construction period to simulate the average daily rise speed of the dam core wall;

[0112] ② Generate a random number of days for dam filling suspension in each month during the construction period, simulate the number of days for dam filling suspension in each month, and calculate the effective construction days in each month;

[0113] ③According to the simulated calculation of the dam filling elevation series, the total diversion years t in the early and middle stages of construction are obtained. d , the number of years of diversion period at the beginning of construction t c According to the simulation model, the annual flood water retaining elevation matrix [Z d1 , Z d2 ,……,Z td ];

[0114] S54. Conduct random simulation of the highest flood level in front of the dam for flood control:

[0115] ①Generate diversion period t d Random numbers of construction flood peaks in each year to simulate the construction flood process;

[0116] ②Generate diversion period t dRandom numbers of the reservoir storage coefficient for each year within the year are used to simulate and fit the water level - storage relationship curve;

[0117] ③ Generate the diversion period t d Random numbers of the discharge capacity coefficient for each year within the year are used to simulate and fit the diversion discharge capacity curve;

[0118] ④ Obtain the diversion period t through simulation of flood regulation calculation d Series matrix of the highest flood levels in front of the dam for each year within the year

[0119] S55. Estimate the diversion risk rate based on the random simulation results:

[0120] ① After N C times of sampling simulation calculations, statistically analyze the diversion period t during the initial - middle stage of construction d The highest flood levels max(Z Hj (t)) in front of the dam for each year within the year, where j = 1, 2, …, t d all do not exceed the water - retaining elevation Z dj before the main flood season for dam construction during flood - season, where j = 1, 2, …, t d The number of times is denoted as N D Then the estimation formula for the dynamic risk rate of diversion during the initial - middle stage of the extra - high core - wall rock - fill dam is:

[0121]

[0122] ② After N C times of sampling simulation calculations, statistically analyze the highest flood levels max(Z c in front of the dam during the initial diversion period t Hj (t)) for each year within the year, where j = 1, 2, …, t c that exceed the water - retaining elevation Z W before the main flood season for dam construction during flood - season. The number of times is denoted as N W Then the estimation formula for the diversion risk rate during the initial stage of the extra - high core - wall rock - fill dam is:

[0123]

[0124] ③ After N C times of sampling simulation calculations, statistically analyze the highest flood level in front of the dam in the t d th year during the middle - stage diversion period that exceeds the water - retaining elevation during the middle - stage flood - season of dam construction The number of times is denoted as N G Then the estimation formula for the middle - stage diversion risk rate is:

[0125]

[0126] S6. Conduct preliminary optimization and ranking of the design schemes for diversion engineering of ultra-high core rockfill dam construction;

[0127] The specific implementation steps of this step include:

[0128] S61. Comprehensively consider the project scale, construction arrangement, interception difficulty and hydrological conditions, and combine engineering experience to make preliminary design of diversion project dimensions;

[0129] S62. Design cofferdam size: H max The maximum height of the upstream cofferdam that can be completed in a dry season or the maximum height under anti-seepage requirements; B min The minimum hole width required for construction and transportation vehicles to pass through;

[0130] S63. Analyze the trend of direct investment in diversion projects: The corresponding relationship matrix between the diversion hole size and the cofferdam size is determined by hydraulic method [S T ,Z W ], initially drafting several diversion engineering design schemes, and obtaining the variation law of direct investment of diversion engineering and cofferdam height and diversion tunnel size under the conditions of satisfying relevant design constraints;

[0131] S64. Based on the changing patterns of direct investment in diversion projects, cofferdam height and diversion tunnel size, and taking the lowest direct investment in diversion projects as the criterion, recommend the best diversion project design scheme and rank the diversion project design schemes.

[0132] S7. Conduct risk assessment and adjustment on the design scheme of diversion engineering for super-high core rockfill dam construction.

[0133] Carry out risk assessment on the initially selected best diversion engineering design scheme. If it meets the design requirements, the initially selected best diversion engineering design scheme is the optimal design scheme. If it does not meet the design requirements, the design scheme with the lowest ranking will be adopted until the risk assessment requirements are met. Otherwise, continue to use the design scheme with the lowest ranking for risk assessment.

[0134] When conducting risk identification, the current risk theory methods can be used, specifically:

[0135] Assume that the flood return period corresponding to the initial diversion standard is T IB , the flood return period corresponding to the medium-term flood control standard is T MB , and the initial diversion design risk rate R is converted to IB and mid-term diversion design risk rate R MB , the calculation expression is:

[0136]

[0137] According to the requirements of the current regulations and specifications in my country, when the dam is filled beyond the cofferdam, the medium-term diversion standard is suddenly and significantly higher than the initial diversion standard at a certain point in time, which brings difficulties to the construction diversion planning and design and risk decision-making. In the planning and design stage, the diversion engineering design needs to meet the requirements of both the initial diversion and the medium-term diversion for flood control. Therefore, the risk judgment criteria for the diversion design scheme of the ultra-high core wall rockfill dam to meet the requirements of the specification are:

[0138]

[0139] Example:

[0140] Taking the implementation of the SJK Hydropower Station, a controlling reservoir in the upper reaches of the Dadu River Basin, as an example, the weir is a core wall rockfill dam with a height of 315.00m, which is currently the highest dam in the world. The project is a first-class large (1) type project, and the hub project consists of a weir, flood discharge structures, and a water diversion and power generation system. The valley slope of this project is steep and the bedrock is exposed. The project adopts a tunnel diversion method in which the cofferdam is used to cut off the flow once and the foundation pit is constructed throughout the year. According to the construction diversion plan, the initial diversion tunnel will operate throughout the initial to mid-term diversion stages of construction, and the mid-term diversion period is considered to be 1 year for analysis. According to the relevant specifications, the initial diversion standard of this project adopts the 20-year flood standard, and the design flow is 4790m 3 / s; the medium-term diversion standard adopts the flood standard of once in 100 years, and the design flow is 5300m 3 / s.

[0141] In order to ensure the safety of flood control during the dam construction period, this paper adopts the risk analysis method to determine the scientific rationality of different diversion project designs. The specific implementation steps are as follows:

[0142] 1. Preliminary draft of diversion design:

[0143] According to the hub layout, topographic and geological conditions, based on the experience of domestic cofferdam filling projects, combined with the current construction level, considering that the upstream cofferdam needs to meet the requirements of completion within a dry season, the upper limit of the upstream cofferdam height is 70m, the lower limit is 50m, and the minimum hole width required for construction and transportation vehicles is 2.5m. Under the standard diversion conditions of once in 20 years, the hydraulic method is used to establish the relationship between the design scale of the diversion tunnel and the investment of the diversion project corresponding to different upstream cofferdam heights as shown in Table 1.

[0144] Table 1 Design parameters of diversion project

[0145] project Diversion tunnel section <![CDATA[Diversion tunnel area / m 2 > Cofferdam top elevation / m Cofferdam height / m Civil construction investment of diversion project / 10,000 yuan Solution 1 14×17.2 224.47 2322 70 41422 Solution 2 14×18.0 235.67 2317 65 42666 Solution 3 14×18.9 248.27 2312 60 44065 Solution 4 15×18.4 258.19 2307 55 44828 Solution 5 16×18.2 271.93 2302 50 46056

[0146] According to the changing rules, taking the lowest direct investment in diversion projects as the optimization criterion, the optimal diversion project design scheme 1 is preliminarily selected, and the diversion project design schemes are ranked as scheme 1, scheme 2, scheme 3, scheme 4, and scheme 5.

[0147] 2. Random parameter analysis:

[0148] (1) Random parameters of dam filling rise:

[0149] According to the SJK project dam construction plan, the foundation concrete will be poured from December of the fourth year to January of the fifth year, the foundation consolidation grouting construction will be carried out in February, and the dam filling construction will begin in March.

[0150] The SJK project dam is 315m high, and the dam filling quality requirements are extremely high. In order to ensure the quality of the dam filling, the design requires that the entire section of the dam be filled and raised flat. According to the research results of dam construction planning and combined with the experience of similar projects, under various relevant constraints, the number of daily filling layers of the dam core wall material is about 0.5 to 1.5 layers, and the daily average rising speed is about 0.1 to 0.3 m / d. The daily average rising speed given by the design is 0.21 m / d. Considering that the daily average rising speed of the dam core wall follows a triangular distribution, its distribution parameters are h d =0.1m / d (lower limit), h m =0.21m / d (median), h u =0.3m / d (upper limit).

[0151] According to the analysis of the effective construction days for the gravel-soil core wall filling of the dam, the influence of natural conditions such as rainfall and temperature is taken into account, and appropriate suspension standards are formulated in combination with the natural conditions of the construction area. Considering that the dam body filling adopts the method of daytime construction and night suspension in December to February in winter, there is no rainfall from November to March, and from June to September, the rainy season is appropriately reduced by 0.6 based on relevant engineering experience. The normal distribution parameters of the effective construction days and suspension days in each month (this project mainly considers the influence of rainfall) are shown in Table 2.

[0152] Table 2 Construction time parameters

[0153] project January February March April May June July August September October November December <![CDATA[T i ]]> 12 6 31 30 31 30 31 31 30 31 30 15 <![CDATA[T si ]]> 0 0 0 N(1.4,0.5) N(3.8,0.5) N(6.4,1.3) N(5.7,1.2) N(4.8,0.5) N(5.5,1.5) N(2,0.5) 0 0

[0154] (2) Hydrological random parameters:

[0155] Based on the measured annual maximum flow series of the hydrological station, the investigated annual historical floods are added to form a discontinuous series for frequency calculation. The empirical frequencies of historical floods and measured series are calculated according to the expectation formula, the moment method is used to calculate the initial estimated parameters, and the hydrological random parameter is determined as μ by the eye estimate fit line. Q =2540m 3 / s,C v =0.33,C s / C v =5.0.

[0156] (3) Hydraulic random parameters:

[0157] The discharge capacity coefficient of the initial diversion and discharge building follows a triangular distribution, generally ranging from 0.97 to 1.05. Based on the experience of similar projects, the distribution parameters are 0.97 (lower limit), 1.00 (median value), and 1.05 (upper limit). Considering that the water level-reservoir capacity relationship coefficient of this project follows a triangular distribution, the distribution parameters are 0.99 (lower limit), 1.00 (median value), and 1.01 (upper limit).

[0158] 3. Risk rate estimation and risk identification of the present invention:

[0159] (1) Estimation of flood risk rate in the early to mid-term:

[0160] Based on the design parameters of the diversion project of the better solution 1, the hydrological, hydraulic, and dam filling rise random factors were comprehensively considered, and the number of simulations was set at 100,000 times. The corresponding diversion risk R in the early and middle stages of construction was obtained as shown in Table 3.

[0161] Table 3 Risk rate of diversion in the early and middle stages of construction Risk rate results

[0162] project Section Cofferdam elevation / m R Solution 1 14×17.2 2322.0 4.80％

[0163] (2) Risk identification:

[0164] Taking into account the random factors of hydrology, hydraulics, and dam filling rise, combined with the random parameter values ​​of this project, the number of simulations was set at 100,000 times. According to different diversion project design schemes, the corresponding diversion risks in the early and middle stages of construction were obtained, and the risk identification results are shown in Table 4.

[0165] Table 4 Results of diversion risk identification under the condition of randomness of dam filling rise

[0166] project Section Cofferdam elevation / m <![CDATA[R W ]]> <![CDATA[R D ]]> Initial risk identification IMN risk assessment Option 1 (best in the initial selection) 14×17.2 2322.0 1.666％ 0.582％ satisfy satisfy Solution 2 14×18.0 2317.0 1.661％ 0.929％ satisfy satisfy Solution 3 14×18.9 2312.0 1.662％ 0.912％ satisfy satisfy Solution 4 15×18.4 2307.0 1.743％ 0.681％ satisfy satisfy Solution 5 16×18.2 2302.0 1.739％ 0.433％ satisfy satisfy

[0167] Based on the above analysis, the optimal solution 1 initially selected for this project meets the risk identification requirements and can be used as the recommended solution.

[0168] 4. Risk identification without considering the random impact of dam filling rise in traditional technology:

[0169] As the latest technology, it is compared with the existing technology. Traditional risk analysis technology ignores the impact of the randomness of dam filling rise. According to the dam construction planning analysis, the average daily rise rate of the dam core wall is taken as the most likely average daily rise rate of 0.21m / day, and the effective construction days and shutdown days in each month are taken as the average. The number of simulations is 10,000 times. According to different diversion design schemes, the initial diversion period t is obtained by comprehensively considering the hydrological and hydraulic random factors. c , initial diversion risk RW, mid-term diversion risk RD, and comprehensive diversion risk R are shown in Table 5.

[0170] Table 5 Results of diversion risk rate under the condition of dam filling rise determination in traditional technology

[0171] project Section Initial guide height / m Intermediate guide height / m <![CDATA[t c / year]]> <![CDATA[R W ]]> <![CDATA[R D ]]> Initial risk identification IMN risk assessment Solution 1 14×17.2 2322.00 2324.34 2 1.63％ 1.46％ Dissatisfied Dissatisfied Solution 2 14×18.0 2317.00 2324.34 2 1.60％ 1.05％ Dissatisfied Dissatisfied Solution 3 14×18.9 2312.00 2324.34 2 1.65％ 0.77％ satisfy satisfy Solution 4 15×18.4 2307.00 2324.34 2 1.71％ 0.48％ satisfy satisfy Solution 5 16×18.2 2302.00 2324.34 2 1.68％ 0.27％ satisfy satisfy

[0172] It can be seen that under the condition of a certain average daily rise rate of the dam core wall of 0.21m / day, the initial diversion risk rate R W They basically meet the requirements of the specification, indicating that the cofferdam height determined by hydraulic calculation is generally too large, indicating that the traditional design method has a certain safety margin; the medium-term diversion risk rate R D , the diversion risk R in the early and middle stages of construction decreases with the increase of the diversion tunnel section, indicating that the increase in discharge capacity is effective in reducing the risk of flood control and flood season, and the results are in line with the objective laws of the project; according to the requirements of the specifications, the diversion design schemes of Schemes 3, 4, and 5 meet the requirements of flood control and flood season in the early and middle stages of dam construction; Schemes 1 and 2 do not meet the requirements of flood control and flood season in the middle stage of construction. This is different from the results obtained in the present invention, but the present invention fully considers the randomness of the dam filling rise, which is obviously more in line with the actual project.

[0173] In summary, according to the method of the present invention, the randomness of the dam filling rise can be fully considered, and the calculation and analysis are more in line with the objective reality of the project. At the same time, the following important results are obtained: ① The risk rate of the initial-mid-term diversion process corresponding to different diversion design schemes is scientifically and reasonably detected, which can provide an important theoretical basis for further flood risk assessment, risk decision-making, and risk allocation; ② Risk discrimination is performed on the preliminary sorted diversion tunnel design schemes, and a better diversion tunnel design scheme is selected. This provides new technical means for the diversion optimization design and flood plan decision-making of the ultra-high core wall rockfill dam construction in the engineering planning and design stage.

[0174] Finally, it should be noted that the above embodiments are only preferred implementations and are not intended to limit the present invention. It should be pointed out that for those skilled in the art, several modifications, equivalent replacements, improvements, etc. can be made without departing from the scope of the present invention and the scope of protection of the claims, and all of these should be included in the protection scope of the present invention.

Claims

1. Detection method of diversion risk rate in the early and middle stages of construction of ultra-high core rockfill dam, It is characterized in that The following steps are involved: S1. Construct a calculation model for the flood retaining elevation of the super-high core rockfill dam during the initial and intermediate stages of construction; S2. Construct a mathematical model for diversion risk in the early and mid-term construction of ultra-high core rockfill dams; S3. Conduct a systematic analysis of the randomness of dam filling rise and determine the distribution parameters of each random factor; S4. Analyze the parameters of the random factors of the construction flood process and the discharge capacity of the diversion tunnel to determine the distribution parameters of each random factor; S5. Carry out random simulation calculation of diversion risk rate in the early and middle stages of construction of ultra-high core rockfill dam; S6. Conduct preliminary optimization and ranking of the design schemes for diversion engineering of ultra-high core rockfill dam construction; S7. Conduct risk assessment and adjustment on the design scheme of diversion engineering for super-high core rockfill dam construction.

2. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 1, It is characterized in that In step S1, the construction of a calculation model for the flood-retaining elevation of an ultra-high core rockfill dam during the initial and intermediate stages of construction includes: The diversion period from the initial to the middle stage of facility construction is t d Years, of which the initial diversion period is t c The mid-term diversion period is 1 year, which is the tth year of the mid-term diversion. d If the dam filling elevation exceeds the cofferdam elevation before the main flood season of that year, then the diversion t in the early and middle stages of construction is d In the year, the water retaining elevation Z of the core rockfill dam during the initial and intermediate flood seasons before the main flood season in the jth year dj The calculation model is: where j = 1, 2, ..., t d Among them, Z W Z is the initial flood retaining elevation, i.e. the elevation of the top of the upstream cofferdam; sj It is the water retaining elevation for the mid-term flood season.

3. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 2, It is characterized in that In step S2, the construction of a mathematical model for diversion risk in the early and mid-term construction of an ultra-high core rockfill dam includes: The diversion risk in the initial and middle stages of construction of ultra-high core rockfill dam is defined as the probability of the highest flood level in the main flood season exceeding the flood retaining elevation during the initial and middle stages of construction. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the mathematical model of the dynamic risk R of the diversion in the initial and middle stages of construction of ultra-high core rockfill dam is established as follows: where j = 1, 2, ..., t d Among them, Z Hj (t) is the dynamic change process of the water level of the reservoir in front of the dam for flood control in the jth year; S T is the design parameter of the diversion tunnel, Z W is the design elevation of the upstream cofferdam; P() is the probability calculation; [S T ,Z W ] is S T and Z W The relationship matrix of The initial diversion risk of construction is defined as the probability that the highest flood level in the main flood season exceeds the elevation of the upstream cofferdam top within the initial diversion period of construction, which represents the ability of the upstream cofferdam to resist the construction flood process during the main flood season within the initial diversion period. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the initial diversion risk R of ultra-high core rockfill dam construction is established. W The mathematical model is: R W = P(max(Z Hj (t)) > Z W |[S T , Z W ), where j = 1, 2, …, t c The mid-term diversion risk of construction is defined as the probability that the highest flood level during the main flood season exceeds the flood retaining elevation of the dam within the mid-term diversion period of construction. It represents the ability of the temporary dam with fill rising above the cofferdam elevation during the mid-term diversion period to resist the construction flood process during the main flood season. Taking into account the randomness of hydrology, hydraulics, and dam filling rise, the mid-term diversion risk R of ultra-high core rockfill dam construction is established. D The mathematical model is: in, For the tth d Dynamic changes in water level of the reservoir in front of the dam for flood control in 2017.

4. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 1, It is characterized in that In step S3, the randomness of the dam filling rise is systematically analyzed to determine the distribution parameters of each random factor, including: according to the calculation model of the dam core wall filling elevation in the kth month of the initial-mid-term construction where k = 1, 2, ..., t d ×12 The daily average rise speed H of the core wall of the core rockfill dam vi and the dam filling suspension days index T si The impact of the dam filling suspension days index T si It follows a normal distribution; The average daily rise speed of the dam core wall is H vi It obeys the triangular distribution, and its probability density function is: Among them, h d is the lower limit, i.e. the slowest daily average rising speed; h m is the median value, i.e. the most likely daily average rising speed; h u is the upper limit, i.e. the fastest daily average rising speed.

5. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 1, It is characterized in that In step S4, the parameter analysis of the random factors of the construction flood process and the discharge capacity of the diversion tunnel is performed to determine the distribution parameters of each random factor, including: The random factors of the construction flood process and the discharge capacity of the diversion tunnel need to consider the randomness of the peak flow of the construction flood, the randomness of the water level-reservoir capacity relationship, and the randomness of the discharge capacity flow coefficient. The peak flow of the construction flood is set to satisfy the P-III distribution, and the reservoir capacity relationship coefficient and the discharge capacity coefficient are assumed to obey the triangular distribution.

6. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 1, It is characterized in that In step S5, the random simulation calculation of the diversion risk rate in the early and middle stages of the construction of the ultra-high core rockfill dam includes: S51, input model-related calculation parameters; S52, determine the total number of simulation calculations N of the model that meets the accuracy requirements C ; S53, conduct a series of random simulations of flood retaining elevations during the initial and mid-term construction period: ① Generate random numbers of the average daily rise speed of the dam core wall in each month during the construction period to simulate the average daily rise speed of the dam core wall; ② Generate a random number of days for dam filling suspension in each month during the construction period, simulate the number of days for dam filling suspension in each month, and calculate the effective construction days in each month; ③According to the simulated calculation of the dam filling elevation series, the total diversion years t in the early and middle stages of construction are obtained. d , the number of years of diversion period at the beginning of construction t c According to the simulation model, the annual flood water retaining elevation matrix [Z d1 , Z d2 ,……,Z td ]; S54. Conduct random simulation of the highest flood level in front of the dam for flood control: ①Generate diversion period t d Random numbers of construction flood peaks in each year to simulate the construction flood process; ②Generate diversion period t d The random number of the reservoir capacity relationship coefficient in each year is used to simulate and fit the water level capacity relationship curve; ③Generate diversion period t d The random number of the discharge capacity coefficient of each year in the year is used to simulate and fit the diversion and discharge capacity curve; ④ Obtain the diversion period t through simulation of flood control calculation d Matrix of the highest flood levels in front of the dams in each year S55. Estimation of diversion risk rate based on random simulation results: ① After N C Sampling simulation calculations and statistical analysis of the diversion period t in the early and middle stages of construction d The highest flood level in front of the dam in each year (max(Z Hj (t)), where j = 1, 2, …, t d The elevation of the dam before the main flood season is not more than Z dj , where j = 1, 2, ..., t d The number of times is recorded as N D , then the dynamic risk rate estimation formula of the initial-mid-term diversion of the ultra-high core rockfill dam is: ②After N C Sampling simulation calculations were performed to statistically analyze the initial diversion period t c The highest flood level in front of the dam during the year max(Z Hj (t)), where j = 1, 2, …, t c Exceeding the flood retaining elevation Z of the dam construction before the main flood season W The number of times is recorded as N W , then the initial diversion risk rate estimation formula of the ultra-high core rockfill dam is: ③After N C The sampling simulation calculation is performed to statistically analyze the tth time of the mid-term diversion period. d The highest flood level before the dam Exceeding the flood-proof elevation during the mid-term construction of the dam The number of times is recorded as N G , then the mid-term diversion risk rate estimation formula is:

7. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 3, It is characterized in that In step S6, the preliminary optimization and sorting of the design schemes for the construction diversion project of the ultra-high core rockfill dam includes: S61. Comprehensively consider the project scale, construction arrangement, interception difficulty and hydrological conditions, and combine engineering experience to make preliminary design of diversion project dimensions; S62. Design cofferdam size: H max The maximum height of the upstream cofferdam that can be completed in a dry season or the maximum height under anti-seepage requirements; B min The minimum hole width required for construction and transportation vehicles to pass through; S63. Analyze the trend of direct investment in diversion projects: The corresponding relationship matrix between the diversion hole size and the cofferdam size is determined by hydraulic method [S T ,Z W ], initially drafting several diversion engineering design schemes, and obtaining the variation law of direct investment of diversion engineering and cofferdam height and diversion tunnel size under the conditions of satisfying relevant design constraints; S64. Based on the changing patterns of direct investment in diversion projects, cofferdam height and diversion tunnel size, and taking the lowest direct investment in diversion projects as the criterion, recommend the best diversion project design scheme and rank the diversion project design schemes.

8. The method for detecting diversion risk rate in the early and middle stages of construction of a super-high core rockfill dam according to claim 3, It is characterized in that In step S7, the risk identification and adjustment of the design scheme for the diversion project of the ultra-high core rockfill dam construction includes: Conduct risk assessment on the initially selected optimal diversion engineering design scheme. If it meets the design requirements, the initially selected optimal diversion engineering design scheme is the optimal design scheme. If it does not meet the design requirements, adopt the design scheme ranked last until the risk assessment requirements are met. Otherwise, continue to adopt the design scheme ranked last for risk assessment. The specific methods for risk identification are as follows: The risk criterion for diversion in the early stage of construction of ultra-high core rockfill dam is R W ≤R IB ,in is the diversion risk rate in the initial construction period of the ultra-high core rockfill dam, T IB is the flood return period corresponding to the initial diversion standard; The risk judgment standard for mid-term diversion of super-high core rockfill dam construction is R D ≤R MB ,in is the initial diversion risk rate during the construction of the ultra-high core rockfill dam, T MB is the flood return period corresponding to the medium-term diversion standard.

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