A Method for Determining Dual Control Indicators for Concrete Dam Deformation Considering Flood Control Risk

Abstract

This invention provides a method for determining dual control indicators for concrete dam deformation considering flood control risk, comprising the following steps: S1, Determination of deformation monitoring indicators based on the low-probability method: using measured data as a monitoring sequence, establishing a sample of typical effect sizes; assuming and testing the sample distribution to obtain the sample distribution function; using the design flood control risk as the failure probability, and employing the low-probability method to obtain the concrete dam deformation monitoring indicators; S2, Determination of deformation rate monitoring indicators considering flood control risk: determining the design flood control risk and performing flood regulation calculations in conjunction with the design flood standard; establishing a statistical model and performing regression analysis; calculating the rate of change of water pressure components, and taking the maximum value of the rate of change of water pressure components as the deformation rate monitoring indicator under the design flood standard. This method determines the concrete dam deformation monitoring indicators and deformation rate monitoring indicators, enabling timely monitoring of dam deformation when the reservoir water level rises rapidly, and preventing the monitored dam deformation from exceeding the determined deformation monitoring indicators.

Description

Technical Field

[0001] This invention relates to the field of concrete dam deformation monitoring, and specifically to a method for determining dual control indicators for concrete dam deformation that takes into account flood control risks. Background Technology

[0002] Deformation monitoring indicators are crucial for evaluating and monitoring dam safety. Since the low-probability method of typical monitoring effect quantities qualitatively relates the effect quantities generated by load combinations detrimental to strength and stability, and estimates monitoring indicators based on past monitoring data, when long-term monitoring data is available and unfavorable load combinations are actually encountered, the monitoring indicators formulated based on the low-probability method of typical monitoring effect quantities have a strong theoretical basis and are highly operable. Therefore, since Wu Zhongru proposed the low-probability method of typical monitoring effect quantities for formulating monitoring indicators, many scientific and technological workers have successively adopted the low-probability method to formulate corresponding monitoring indicators based on actual dam engineering monitoring data. Existing literature research indicates that the probability of failure or failure is generally determined based on engineering experience or project level, currently often taking 1% or 5%. However, this value lacks a basis. In fact, when designing dam projects, it is necessary to conduct specialized demonstrations to determine the corresponding characteristic water levels, combining data such as project level and different probability flood standards. Obviously, using the flood control risk determined through specialized demonstrations corresponding to the project level as the failure or failure probability value for the aforementioned low-probability method has a stronger engineering basis.

[0003] When upstream floods arrive, the reservoir rises rapidly above the flood control limit, causing the dam deformation to increase rapidly as well. Although the current dam deformation monitoring has not yet exceeded the planned deformation monitoring indicators, if the deformation rate increases too quickly, on the one hand, the dam deformation will not be able to keep up with the changes, and on the other hand, an excessively high deformation rate may easily cause the dam deformation monitoring to exceed the planned deformation monitoring indicators. Therefore, in order to monitor the safety status of the dam, it is essential to formulate dam deformation rate monitoring indicators in addition to formulating dam deformation monitoring indicators. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for determining dual control indicators for concrete dam deformation that takes into account flood control risks. This method determines the deformation monitoring indicators and deformation rate monitoring indicators for concrete dams, enabling timely monitoring of dam deformation when the reservoir water level rises rapidly, and preventing the monitored deformation of the dam from exceeding the determined deformation monitoring indicators.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for determining dual control indicators of concrete dam deformation considering flood control risks, comprising the following steps:

[0006] S1. Determination of deformation monitoring indicators based on the low probability method, including the following steps:

[0007] S101. Using measured data as a monitoring sequence, establish a sample of typical effect sizes;

[0008] S102. Assume a sample distribution and perform a test to obtain the sample distribution function;

[0009] S103. Using the design flood control risk as the failure probability, the deformation monitoring index of the concrete dam is obtained by the small probability method.

[0010] S2. Determining deformation rate monitoring indicators considering flood control risks, including the following steps:

[0011] S201. Determine the design flood control risks;

[0012] S202. Flood control calculations were performed in conjunction with the design flood standard to obtain the reservoir water level change curve;

[0013] S203. Establishment of statistical model and regression analysis to calculate the change curve of water pressure component during rapid rise in water level;

[0014] S204. Calculation of the rate of change of water pressure component: The maximum value of the rate of change of water pressure component is taken as the deformation rate monitoring index under the design flood standard.

[0015] In the preferred embodiment, in step S103, when using the small probability method of typical monitoring effect quantities to determine the concrete dam deformation monitoring index, the calculation is performed according to the following formula:

[0016]

[0017] In the formula: [δ I [] represents the deformation monitoring index, in mm; δ represents the monitored deformation amount, in mm; F ​​represents the sample distribution function of typical monitoring effect. and σ X α represents the mean and standard deviation of the monitoring effect sample space under unfavorable load combinations, respectively; α is the failure probability, taken as the design flood control risk.

[0018] In the preferred embodiment, in step S202, when using the flood hydrograph at the design flood frequency as the inflow and the flood control limit level as the starting level for flood regulation calculation, the following conditions should be met:

[0019]

[0020] In the formula: Q1 is the inflow rate at the beginning of the calculation period, m 3 / s; Q2 is the inbound flow rate at the end of the calculation period, m 3 / s; q1 is the discharge flow rate at the beginning of the calculation period, m 3 / s; q2 is the discharge flow rate at the end of the calculation period, m 3 / s; V1 is the initial reservoir storage volume during the calculation period, in m 3 V2 represents the reservoir's water storage at the end of the calculation period, in meters. 3 Δt is the calculation period, h; q is the discharge flow rate, m. 3 / s; n×b is the total weir width, m; ε is the lateral contraction coefficient; m is the flow coefficient; g is the gravitational acceleration; H0 is the head of the advancing water, m; V represents the reservoir capacity, m. 3 Z represents the upstream water level, in meters (m).

[0021] Using equation (2), flood control calculations are performed to calculate the downstream flow rate process line q(t) and the upstream water level process line Z(t).

[0022] In the preferred embodiment, in step S203, the statistical model of dam deformation consists of water pressure components, temperature components, and time-dependent components, namely:

[0023]

[0024] Where: δ H δ is the water pressure component; T δ is the temperature component; δ is the aging component; a0 is the constant term; a i Here are the regression coefficients for the water pressure component, i = 1 to 4; H i The value is the i-th power of the upstream water depth on the day of observation. The modeling data sequence is based on the i-th power of the upstream water depth on the first observation day; b i is the regression coefficient for the temperature component, i = 1–4; t is the cumulative number of days from the observation date to the initial measurement date; t0 is the cumulative number of days from the first observation date to the initial measurement date in the modeling data sequence; c i θ is the regression coefficient of the time-dependent component, i = 1 to 3; θ is the cumulative number of days from the observation date to the initial measurement date t divided by 100; θ0 is the cumulative number of days from the first observation date to the initial measurement date of the modeling data sequence t0 divided by 100;

[0025] Based on the deformation monitoring data, the regression coefficients were obtained by stepwise regression. The total duration of the entire flood control calculation was used as the modeling data sequence. The upstream water depth H1 at the first observation time was taken as the water depth corresponding to the starting water level. The change curve δ of the water pressure component during the rapid rise of the water level was calculated using equation (3). H (t).

[0026] In the preferred embodiment, in step S204, the rate of change of the water pressure component is obtained by taking the first derivative of the water pressure component in equation (3):

[0027]

[0028] The present invention provides a method for determining dual control indicators for concrete dam deformation considering flood control risks, which has the following beneficial effects:

[0029] 1. The proposed method takes the flood control risk at the corresponding engineering level as the probability of failure or failure of the typical monitoring effect quantity small probability method, thereby organically linking the operation and maintenance management and design of water conservancy projects.

[0030] 2. A proposed monitoring index for the deformation rate of concrete dams considering flood control risks was put forward. The maximum deformation rate of the concrete dam when the design flood arrives was calculated and used as the deformation rate monitoring index. This can monitor the dam deformation in a timely manner when the reservoir water level rises rapidly, and prevent the dam deformation from exceeding the proposed deformation monitoring index. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0032] Figure 1 This is a proposed flowchart of the present invention;

[0033] Figure 2 Diagram showing the monitoring layout for the upright and inverted plumb lines of the arch dam;

[0034] Figure 3 This is the upstream water level process line;

[0035] Figure 4 This is a process curve showing the change in water pressure components;

[0036] Figure 5 This is the process curve showing the rate of change of the water pressure component; Detailed Implementation

[0037] Combination Figures 1 to 5 The specific embodiments of the present invention will be described in further detail below.

[0038] A method for determining dual control indicators for concrete dam deformation considering flood control risks includes the following steps:

[0039] S1. Determination of deformation monitoring indicators based on the low probability method, including the following steps:

[0040] S101. Using measured data as the monitoring sequence, establish a sample of typical effect sizes.

[0041] S102. Assume a sample distribution and perform tests to obtain the sample distribution function. Generally, statistical test methods are used to determine the distribution, such as the AD method or the KS method.

[0042] S103. Using the design flood control risk as the failure probability, the deformation monitoring index of the concrete dam is obtained using the low-probability method. When formulating the concrete dam deformation monitoring index using the low-probability method of typical monitoring effect quantities, the following formula is used:

[0043]

[0044] In the formula: [δ I [] represents the deformation monitoring index, in mm; δ represents the monitored deformation amount, in mm; F ​​represents the sample distribution function of typical monitoring effect. and σ X α represents the mean and standard deviation of the monitoring effect sample space under unfavorable load combinations, respectively; α is the failure probability, taken as the design flood control risk.

[0045] S2. When upstream floods arrive, the reservoir water level rises rapidly from the flood control limit, causing a rapid increase in dam deformation. Therefore, flood control calculations are performed based on the design flood standard to obtain the reservoir water level change curve. Because the water level rises rapidly in a short period during floods, the temperature and time-dependent components of dam deformation show small fluctuations. Therefore, using the water pressure component from the dam deformation statistical model, the change curve of the water pressure component during the rapid water level rise is calculated, and the rate of change of the water pressure component is calculated. The maximum value of the rate of change of the water pressure component is taken as the deformation rate monitoring index under the design flood standard.

[0046] The formulation of deformation rate monitoring indicators considering flood control risks includes the following steps:

[0047] S201. Determine the design flood control risks.

[0048] The design flood risk of a dam is determined based on its flood control function and scale.

[0049] S202. Flood control calculations were performed in conjunction with the design flood standard to obtain the reservoir water level change curve.

[0050] When using the flood hydrograph at the design flood frequency as the inflow and the flood control limit level as the starting level for flood regulation calculations, the following conditions should be met:

[0051]

[0052] In the formula: Q1 is the inflow rate at the beginning of the calculation period, m 3 / s; Q2 is the inbound flow rate at the end of the calculation period, m 3 / s; q1 is the discharge flow rate at the beginning of the calculation period, m 3 / s; q2 is the discharge flow rate at the end of the calculation period, m 3 / s; V1 is the initial reservoir storage volume during the calculation period, in m 3 V2 represents the reservoir's water storage at the end of the calculation period, in meters. 3 Δt is the calculation period, h; q is the discharge flow rate, m. 3 / s; n×b is the total weir width, m; ε is the lateral contraction coefficient; m is the flow coefficient; g is the gravitational acceleration; H0 is the head of the advancing water, m; V represents the reservoir capacity, m.3 Z represents the upstream water level, in meters (m).

[0053] Using equation (2), flood control calculations are performed to calculate the downstream flow rate process line q(t) and the upstream water level process line Z(t).

[0054] The upstream water depth process line H(t) is obtained by subtracting the foundation elevation from the upstream water level Z at each time point.

[0055] S203. Establishment of statistical model and regression analysis to calculate the change curve of water pressure component during the rapid rise of water level.

[0056] The statistical model for dam deformation consists of water pressure components, temperature components, and time-dependent components, namely:

[0057]

[0058] Where: δ H δ is the water pressure component; T For temperature components; δ θ a is the time-dependent component; a0 is the constant term; a i Here are the regression coefficients for the water pressure component, i = 1 to 4; H i The value is the i-th power of the upstream water depth on the day of observation. The modeling data sequence is based on the i-th power of the upstream water depth on the first observation day; b i is the regression coefficient for the temperature component, i = 1–4; t is the cumulative number of days from the observation date to the initial measurement date; t0 is the cumulative number of days from the first observation date to the initial measurement date in the modeling data sequence; c i θ is the regression coefficient of the time-dependent component, i = 1 to 3; θ is the cumulative number of days from the observation date to the initial measurement date t divided by 100; θ0 is the cumulative number of days from the first observation date to the initial measurement date of the modeling data sequence t0 divided by 100.

[0059] Based on the deformation monitoring data, the regression coefficients were obtained by stepwise regression. The total duration of the entire flood control calculation was used as the modeling data sequence. The upstream water depth H1 at the first observation time was taken as the water depth corresponding to the starting water level. The change curve δ of the water pressure component during the rapid rise of the water level was calculated using equation (3). H (t).

[0060] S204. Determination of Deformation Rate Monitoring Index: The rate of change of water pressure component is calculated, and the maximum value of the rate of change of water pressure component is taken as the deformation rate monitoring index under the design flood standard.

[0061] Taking the first derivative of the water pressure component in equation (3), the rate of change of the water pressure component is:

[0062]

[0063] Taking a certain Class II large-scale water conservancy project as an example, it mainly consists of a concrete arch dam, an open spillway, and deep discharge holes. The design flood standard for the main structures such as the dam and spillway is once every 100 years, the check flood standard is once every 1000 years, and the flood limit water level is 643m.

[0064] Radial displacement of arch dams is a more effective indicator of dam safety. This radial displacement is primarily monitored using a plumb line system, arranged as follows: Figure 2 As shown.

[0065] Therefore, deformation dual monitoring indicators were proposed for typical radial displacement measuring points (PL1-3, PL2-3, PL3-3).

[0066] S1. Determination of deformation monitoring indicators based on the low probability method.

[0067] The radial horizontal displacement of three measuring points at the top of the dam from October 2, 2016 to October 29, 2020 was used as the monitoring sequence. Since there were few annual maximum values ​​in the monitoring sequence, the maximum values ​​of each quarter were used as the typical effect sample. The sample mean and standard deviation are shown in Appendix 1.

[0068] Appendix 1 Sample Mean and Standard Deviation

[0069]

[0070] Based on engineering experience, we assume that the samples follow a normal distribution. Using the KS method to test, we can see that the hypothesis is true and the samples from the three measurement points all follow a normal distribution.

[0071] Using the design flood control risk (1%) as the failure probability, the deformation monitoring index of the concrete dam was obtained by formula (1), and the calculation results are shown in Appendix Table 2.

[0072] Appendix 2: Proposed Results of Dam Deformation Monitoring Indicators

[0073]

[0074] S2. Determine the deformation rate monitoring index considering flood control risks.

[0075] S201. The design flood control risk of the dam is determined based on the dam's flood control tasks and dam size. In this embodiment, the design flood control risk is 1%.

[0076] S202. Flood control calculations were performed in conjunction with the design flood standard to obtain the reservoir water level change curve.

[0077] Using the flood hydrograph at the design flood frequency (1%) as the inflow rate Q(t), and given the reservoir capacity-water level relationship curve V=f(Z), and taking the flood control limit water level of 643m as the starting water level, flood control calculations are performed using equation (2) to calculate the downstream flow rate hydrograph q(t) and the upstream water level hydrograph Z(t). The upstream water level hydrograph Z(t) is shown in the attached figure. Figure 3 As shown.

[0078] The upstream water depth process line H(t) is obtained by subtracting the foundation elevation at the measuring point from the upstream water level Z at each time point obtained from the flood control calculation.

[0079] S203. Establishment of statistical model and regression analysis to calculate the change curve of water pressure component during the rapid rise of water level.

[0080] Combining the radial horizontal displacement monitoring values ​​of three measuring points PL1-3, PL2-3, and PL3-3 at the top of the dam from October 2, 2016 to October 29, 2020, we used this as the monitoring sequence and fitted Equation (4) with stepwise regression analysis to obtain the regression coefficients. The regression coefficients of the water pressure component are shown in Appendix Table 3.

[0081] Appendix 3 Regression coefficients of water pressure components

[0082]

[0083] Using the total duration of the flood control calculation as the modeling data sequence, the upstream water depth H1 at the first observation time is taken as the water depth corresponding to the starting water level (flood limit water level 643m). The change curve of water pressure component during the rapid rise of water level is calculated using equation (3). H (t), the results are attached. Figure 4 As shown.

[0084] S204. Deformation rate monitoring index formulation: Calculation of water pressure component change rate. Formula (4) is used to calculate the water pressure component change rate during the flood control calculation. The results are attached. Figure 5 As shown.

[0085] For the three measuring points PL1-3, PL2-3, and PL3-3 at the dam crest, the rate of change of water pressure components during the flood control calculation was calculated according to the above steps, and the maximum value was taken as the deformation rate monitoring index under the design flood standard. The results are shown in Appendix Table 4.

[0086] Appendix 4: Draft Results of Monitoring Indicators for Dam Deformation Change Rate

[0087]

[0088] The proposed method takes the flood control risk at the engineering level as the probability of failure or failure of the typical monitoring effect quantity small probability method, thereby organically linking the operation and maintenance management and design of water conservancy projects.

[0089] A proposed deformation rate monitoring index for concrete dams considering flood control risks was put forward. The maximum deformation rate of the concrete dam when the design flood arrives was calculated and used as the deformation rate monitoring index. This can monitor the dam deformation in a timely manner when the reservoir water level rises rapidly, and prevent the monitored deformation of the dam from exceeding the proposed deformation monitoring index.

Claims

1. A method for determining dual control indicators for concrete dam deformation considering flood control risks, characterized in that, The steps include: S1. Determination of deformation monitoring indicators based on the low probability method, including the following steps: S101. Using measured data as a monitoring sequence, establish a sample of typical effect sizes; S102. Assume a sample distribution and perform a test to obtain the sample distribution function; S103. Using the design flood control risk as the failure probability, the deformation monitoring index of the concrete dam is obtained by the small probability method. When formulating concrete dam deformation monitoring indicators using the small probability method of typical monitoring effect quantities, the following formula is used for calculation: (1)； In the formula: The deformation monitoring index is in mm; To monitor the amount of deformation, in mm; F This is the sample distribution function of a typical monitoring effect size; and These are the mean and standard deviation of the monitoring effect quantity sample space under unfavorable load combinations, respectively; The failure probability is taken as the design flood control risk; S2. Determining deformation rate monitoring indicators considering flood control risks, including the following steps: S201. Determine the design flood control risks; S202. Flood control calculations were performed in conjunction with the design flood standard to obtain the reservoir water level change curve; When using the flood hydrograph at the design flood frequency as the inflow and the flood control limit level as the starting level for flood regulation calculations, the following conditions should be met: (2)； In the formula: To calculate the inflow rate at the beginning of the time period, m 3 / s; To calculate the inbound flow at the end of the time period, m 3 / s; To calculate the discharge flow rate at the beginning of the time period, m 3 / s; To calculate the discharge flow at the end of the time period, m 3 / s; To calculate the initial reservoir water storage for a given period, m 3 ; To calculate the reservoir storage at the end of the time period, m 3 ; The calculation period is h; q To discharge the flow, m 3 / s; n × b The total width of the weir is in meters (m). The lateral contraction coefficient; m ρ is the flow coefficient; g is the acceleration due to gravity; The head of the water is m; V Indicates the reservoir capacity, m 3 ; Z Indicates the upstream water level, in meters (m). Using equation (2), flood control calculations are performed to calculate the downstream discharge process curve. q ( t ) and upstream water level process line ; S203. Establishment and regression analysis of dam deformation statistical model: The dam deformation statistical model consists of water pressure component, temperature component and time-dependent component. The change curve of water pressure component during the rapid rise of water level is calculated. S204. Calculation of the rate of change of water pressure components: The first derivative of the water pressure components in the statistical model of dam deformation is used to obtain the rate of change of water pressure components. The maximum value of the rate of change of water pressure components is taken as the deformation rate monitoring index under the design flood standard. .

2. The method for determining dual control indicators for concrete dam deformation considering flood control risk according to claim 1, characterized in that, In step S203, the statistical model of dam deformation consists of water pressure components, temperature components, and time-dependent components, namely: (3)； In the formula: This is the water pressure component; For temperature components; For time-sensitive quantities; For constant terms; The regression coefficients for the water pressure component are denoted as . i =1~4; To observe the upstream water depth on the day of the observation i Power; For modeling the upstream water depth on the first observation day of the data sequence i Power; The regression coefficient for the temperature component is denoted as . i =1~4; t The cumulative number of days from the observation date to the initial measurement date; This refers to the cumulative number of days from the first observation date to the initial measurement date in the data sequence used for modeling. The regression coefficients for the time-sensitivity component are denoted as . i =1~3; The cumulative number of days from the observation date to the start date of the measurement. t Divide by 100; To model the cumulative number of days from the first observation date to the initial measurement date of the data sequence. Divide by 100; Based on deformation monitoring data, stepwise regression was used to obtain the regression coefficients. The total duration of the entire flood control calculation was used as the modeling data sequence, with the upstream water depth at the first observation time being... Take the water depth corresponding to the initial water level, and use equation (3) to calculate the curve of the change in water pressure component during the rapid rise of water level. .

3. The method for determining dual control indicators for concrete dam deformation considering flood control risk according to claim 2, characterized in that, In step S204, the rate of change of the water pressure component is obtained by taking the first derivative of equation (3): (4)。

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