A safety monitoring method for concrete dams based on coupling simulation and monitoring

Abstract

The present invention provides a method for safety monitoring of concrete dams by coupling simulation and monitoring; first, a finite element mesh model of the dam is constructed according to the engineering structure design data, and the thermodynamic parameters of the dam concrete and bedrock are inverted using historical monitoring data. Secondly, the statistical error is determined based on the finite element calculation results and measured results of the historical deformation of the dam, and the first, second, and third level monitoring thresholds for dam safety monitoring are determined in combination with the deformation increment of the dam from normal operation to overload conditions. Thirdly, based on the calculated deformation value at a certain moment in the operation of the dam and the first, second, and third level monitoring thresholds, a hierarchical monitoring index at that moment is formulated. Finally, the safety monitoring status of the dam at that moment is determined based on the hierarchical monitoring index and the measured deformation value. The present invention can provide a theoretical and methodological basis for online monitoring of dams and the construction of digital twin projects.

Description

Technical Field

[0001] The invention belongs to the field of water conservancy and hydropower engineering, and in particular relates to a simulation and monitoring coupled concrete dam safety monitoring method. Background Art

[0002] Dam safety is related to national public security and the safety of people’s lives and property. While seeking comprehensive benefits such as water supply, power generation, and flood control, ensuring the safety of the dam itself is the most important constraint.

[0003] Dam safety monitoring models and monitoring indicators are the key to achieving online dam monitoring. However, the existing concrete dam monitoring models and monitoring indicator formulation methods have the following shortcomings:

[0004] In terms of safety monitoring models: it mainly relies on statistical analysis of monitoring data, that is, using mathematical models such as regression analysis, fuzzy mathematics, and neural network algorithms, based on historical data, to establish a functional relationship between effect quantities such as deformation, stress, seepage, and seepage pressure and cause quantities such as water level, temperature, and time, and to make local forecasts of the dam's behavior under different load combinations in the future. This monitoring model lacks overall behavior analysis of physical mechanisms, lacks sufficient understanding of the dam's true working behavior, and lacks the ability to predict risks in sudden and extreme situations. It is difficult to accurately analyze and effectively deal with accident symptoms after they appear. As time goes by, they accumulate and overlap, which may affect the normal operation of the project. In recent years, extreme climates have occurred frequently. Once sudden and extreme situations occur, they exceed the normal operating range, and there is a lack of effective risk prediction and assessment methods.

[0005] In terms of the formulation of monitoring indicators: the formulation of existing safety monitoring indicators also lacks physical mechanism analysis. For example, the safety monitoring indicators determined by the confidence interval method actually reflect the degree of deviation of the monitoring data from the statistical law; the safety monitoring indicators determined by the typical monitoring effect size small probability method are the extreme values ​​of a certain probability of failure under the current load conditions. The monitoring indicators formulated by the above method are not related to the causes and mechanisms of dam failures. The relationship between the monitoring indicators and the safety status of the dam itself is not clear. When encountering emergencies that exceed the existing load extremes, the monitoring indicators often lose their early warning function. Summary of the invention

[0006] In view of the above reasons, the purpose of the present invention is to provide a concrete dam safety monitoring method that couples simulation and monitoring. The method is based on the finite element mesh model and inversion parameters of the dam, uses the finite element method, monitors and predicts the dam deformation through thermodynamic coupling analysis, combines the traditional statistical method with the finite element overload method, and formulates a hierarchical monitoring index that can reflect both the abnormal monitoring data and the safety status of the dam. Using this method to monitor concrete dams can accurately identify potential safety hazards of the dam, and provide technical support for timely eliminating the dam operation risk and ensuring the long-term safe operation of the dam.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A simulation and monitoring coupled concrete dam safety monitoring method comprises the following steps:

[0009] S1. Based on the engineering structure design data and applying 3D modeling technology, a finite element mesh model of a concrete dam is constructed that can reflect the interaction between “dam-bedrock-reservoir water” and meet the needs of coupling analysis of different physical fields.

[0010] S2. Based on the environmental monitoring data and the dam temperature and deformation monitoring data, the real thermodynamic parameters of concrete and bedrock are obtained through parameter inversion.

[0011] S3. According to the measured data of reservoir water level, reservoir water temperature and air temperature at different times in history, based on the finite element mesh model and inversion parameters, the deformation values ​​of the dam at different times are calculated. The calculated values ​​of the deformation of the dam at different times are subtracted from the measured values ​​to obtain the deformation residuals at different times, and the standard deviation of the residual series is calculated as the first-level monitoring threshold for dam safety monitoring.

[0012] The first-level monitoring threshold δ1 is:

[0013]

[0014] In formula 1, N represents the number of data in the deformation residual series, x i represents the i-th deformation residual, μ represents the mean of the deformation residual series, and S represents the standard deviation of the deformation residual series.

[0015] S4. Set the reservoir water level to the normal water storage level, use the finite element method to calculate the deformation and stress of the dam, and gradually increase the head overload coefficient until the dam heel stress exceeds the tensile strength of the concrete. Subtract the deformation of the dam at this time from the deformation when the dam is not overloaded, and the difference is used as the third-level monitoring threshold for dam safety monitoring.

[0016] The three-level monitoring threshold δ3 is:

[0017] δ3=δ c -δ z (2)

[0018] In formula 2, δ z represents the dam deformation at normal water level without overloading, δ c It indicates the deformation of the dam when the dam heel stress exceeds the tensile strength of concrete under the normal water level. S5. Add the first-level monitoring threshold and the third-level monitoring threshold to get the average value, which is used as the second-level monitoring threshold for dam safety monitoring.

[0019] The secondary monitoring threshold δ2 is:

[0020]

[0021] In formula 3, δ1 represents the first-level monitoring threshold, and δ3 represents the third-level monitoring threshold.

[0022] S6. At a certain moment in the future operation of the concrete dam, obtain the real-time measured values ​​of the reservoir water level, reservoir water temperature and air temperature from the monitoring database. If the measured values ​​are abnormal, the estimated values ​​of the reservoir water level, reservoir water temperature and air temperature at that moment are obtained by interpolation based on the average reservoir water level, average reservoir water temperature and average air temperature of each month over many years.

[0023] S7. Taking into account the boundary conditions such as reservoir water level, reservoir water temperature, air temperature, and material properties such as concrete creep and bedrock rheology at that moment, the deformation of the dam is calculated through the "temperature-deformation-stress" coupling analysis.

[0024] S8. According to the primary, secondary and tertiary monitoring thresholds of the dam safety monitoring determined in steps S3 to S5, and the deformation value of the dam at a certain moment of operation calculated in step S7, determine the hierarchical monitoring index of the dam at that moment, as follows:

[0025] 1) The calculated value of dam deformation at that moment plus the first-level monitoring threshold is used as the upper limit of the first-level monitoring index; the calculated value of dam deformation at that moment minus the first-level monitoring threshold is used as the lower limit of the first-level monitoring index;

[0026] 2) The calculated value of the dam deformation at that moment plus the secondary monitoring threshold is used as the upper limit of the secondary monitoring index; the calculated value of the dam deformation at that moment minus the secondary monitoring threshold is used as the lower limit of the secondary monitoring index;

[0027] 3) The calculated value of the dam deformation at that moment is added to the third-level monitoring threshold as the upper limit of the third-level monitoring index; the calculated value of the dam deformation at that moment is subtracted from the third-level monitoring threshold as the lower limit of the third-level monitoring index.

[0028] The hierarchical monitoring indicators are:

[0029]

[0030] In formula 5, δ 1u Indicates the upper limit of the first-level monitoring index, δ 1d Indicates the lower limit of the first-level monitoring indicator, δ 2u Indicates the upper limit of the secondary monitoring index, δ 2d Indicates the lower limit of the secondary monitoring index, δ 3u Indicates the upper limit of the third-level monitoring index, δ 3d It represents the lower limit of the third-level monitoring index, and δ represents the calculated deformation value at a certain moment during the operation of the dam.

[0031] S9. Compare the measured value of the dam deformation at the same time with the graded monitoring index prepared in step S8 to determine the deformation monitoring status of the dam, as follows:

[0032] 1) If the measured value of the dam deformation is within the upper and lower limits of the first-level monitoring index, the deformation monitoring status of the dam is determined to be safe;

[0033] 2) If the measured value of dam deformation exceeds the upper and lower limits of the first-level monitoring index, but is within the upper and lower limits of the second-level monitoring index, the deformation monitoring status of the dam is judged to be slightly abnormal;

[0034] 3) If the measured value of the dam deformation exceeds the upper and lower limits of the second-level monitoring index, but is within the upper and lower limits of the third-level monitoring index, the deformation monitoring status of the dam is determined to be abnormal;

[0035] 4) If the measured value of the dam deformation exceeds the upper and lower limits of the third-level monitoring index, the deformation monitoring status of the dam is judged to be dangerous.

[0036] Beneficial effects of the present invention:

[0037] The present invention proposes a simulation and monitoring coupled concrete dam safety monitoring method, which has the following advantages:

[0038] 1) In terms of monitoring model, based on the finite element mesh model and inversion parameters of the dam, the calculation results of the dam deformation are obtained through thermodynamic coupling analysis. This result has a physical mechanism that can reflect the real working state of the dam;

[0039] 2) In terms of monitoring indicators, the proposed method for formulating hierarchical monitoring indicators can reflect both abnormal monitoring data and the safety status of the dam. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of the present invention;

[0041] Figure 2A It is the overall finite element mesh model including the concrete dam and bedrock;

[0042] Figure 2B It is the finite element mesh model of the concrete dam body;

[0043] Figure 3 This is a schematic diagram of the dam heel stress exceeding the concrete tensile strength;

[0044] Figure 4 It is a schematic diagram of the dam deformation monitoring curve.

[0045] Figure 4The meaning of the marks in the figure: 1-upper limit of the third-level monitoring index, 2-upper limit of the second-level monitoring index, 3-upper limit of the first-level monitoring index, 4-actual deformation measured value, 5-lower limit of the first-level monitoring index, 6-lower limit of the second-level monitoring index, 7-lower limit of the third-level monitoring index. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings, but it should be noted that these implementation modes are not limitations of the present invention, and equivalent changes or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these implementation modes are all within the protection scope of the present invention.

[0047] The present invention is described below by taking a concrete dam as an example. Figure 1 As shown:

[0048] Step 1: Based on the engineering structure design data, the 3D modeling technology is used to construct a finite element mesh model of the concrete dam. Figure 2A and Figure 2B As shown in the figure, the model takes into account the topographic and geological conditions of the dam area, as well as detailed dam structures such as orifices and joints, and boundary conditions such as temperature, water pressure, and silt pressure. It can reflect the interaction between "dam-bedrock-reservoir water" and meet the needs of coupling analysis of different physical fields.

[0049] Step 2: Based on the monitoring data of environmental variables such as reservoir water level, reservoir water temperature, air temperature, and the temperature and deformation monitoring data of the dam, the finite element method is used to obtain the true thermodynamic parameters of concrete and bedrock through parameter inversion, as shown in Table 1.

[0050] Table 1 Thermodynamic parameters of concrete and bedrock

[0051] Concrete grade <![CDATA[C 90 40]]> <![CDATA[C 90 30]]> <![CDATA[C 90 35]]> Elastic modulus E(GPa) 30 27 28 Thermal conductivity λ[kJ / (m·h·℃)] 8.2 8.2 8.2 <![CDATA[Temperature diffusivity a (m 2 / h)]]> 0.0036 0.0036 0.0036 <![CDATA[Unit weight γ (kg / m 3 )]]> 2450 2450 2450 Specific heat c[kJ / (kg·℃)] 0.95 0.95 0.95 <![CDATA[Coefficient of linear expansion α (×10 -6 / °C)]]> 9.5 9.5 9.5 Heat exchange coefficient β[kJ / (m2·h·℃] 83.72 83.72 83.72 Poisson's ratio of concrete 0.19 0.19 0.19 Bedrock elastic modulus E(GPa) 28 28 28

[0052] Step 3: According to the measured data of reservoir water level, reservoir water temperature and air temperature at different times in history, the deformation values ​​of the dam at different times are calculated based on the finite element mesh model and inversion parameters. The calculated deformation values ​​of the dam at different times are subtracted from the measured values ​​to obtain the deformation residuals at different times, as shown in Table 2. Formula 1 is used to calculate the standard deviation S of the deformation residual series, which is used as the first-level monitoring threshold δ1 for dam safety monitoring.

[0053] Table 2 Dam deformation residual series

[0054]

[0055]

[0056]

[0057] In formula 1, N represents the number of data in the deformation residual series, x i represents the i-th deformation residual, and μ represents the mean of the deformation residual series.

[0058] Step 4: Set the reservoir water level to the normal storage level and use the finite element method to calculate the deformation of the dam δ z , gradually increase the head overload coefficient until the dam heel stress exceeds the concrete tensile strength, such as Figure 3 As shown, the dam deformation is δ c , using δ c Subtract δ z The obtained difference is used as the third-level monitoring threshold δ3 for dam safety monitoring, as shown in Formula 2.

[0059] δ3=δ c -δ z (2)

[0060] Step 5: Add the first-level monitoring threshold δ1 and the third-level monitoring threshold δ3 to obtain the average value, which is used as the second-level monitoring threshold δ2 for dam safety monitoring, as shown in Formula 3.

[0061]

[0062] Step 6: At a certain moment in the future operation of the dam, obtain the real-time measured values ​​of the reservoir water level, reservoir water temperature and air temperature from the monitoring database. If the measured values ​​are abnormal, the estimated values ​​of the reservoir water level, reservoir water temperature and air temperature at that moment are obtained by interpolation based on the average reservoir water level, average reservoir water temperature and average air temperature of each month over many years.

[0063] Taking temperature as an example, the average monthly temperature over the years is shown in Table 3, and the interpolation method is shown in Formula 4.

[0064] Table 3. Average monthly temperature in the dam site area over the years

[0065]

[0066]

[0067] In formula 4, T t Indicates the estimated value of the temperature at a certain moment; d t Indicates the number of days from January 1st of the current year, d i-1 Indicates the number of days between the 15th of the previous month and January 1 of the current year; d i Indicates the number of days between the 15th of the next adjacent month and January 1 of the current year; T i-1 represents the average temperature of the previous adjacent month at that moment; T i It indicates the average temperature of the next adjacent month at that moment.

[0068] Step 7: Based on the real-time measured or estimated values ​​of the environmental quantities determined in step 6, taking into account boundary conditions such as reservoir water level, reservoir water temperature, air temperature, and material properties such as concrete creep and bedrock rheology, the finite element method is used to calculate the deformation value δ of the dam at that moment through "temperature-deformation-stress" coupling analysis.

[0069] Step 8: According to the first-level, second-level, and third-level monitoring thresholds δ1, δ2, and δ3 of the dam safety monitoring determined in steps 3 to 5, and the deformation value δ of the dam at a certain moment of operation calculated in step 7, determine the hierarchical monitoring index of the dam at that moment, as follows:

[0070] 1) Add the calculated value of dam deformation δ at this moment to the first-level monitoring threshold δ1 as the upper limit δ of the first-level monitoring index 1u ; Subtract the first-level monitoring threshold δ1 from the calculated dam deformation value δ at this moment as the lower limit δ of the first-level monitoring indicator 1d ;

[0071] 2) Add the calculated value of dam deformation δ at this moment to the secondary monitoring threshold δ2 as the upper limit δ of the secondary monitoring index 2u ; Subtract the secondary monitoring threshold δ2 from the calculated dam deformation value δ at this moment as the lower limit δ of the secondary monitoring index 2d ;

[0072] 3) Add the calculated value of dam deformation δ at this moment to the third-level monitoring threshold δ3 as the upper limit δ of the third-level monitoring index 3u ; Subtract the third-level monitoring threshold δ3 from the calculated dam deformation value δ at this moment as the lower limit δ of the third-level monitoring index 3d .

[0073]

[0074] By connecting the measured deformation values, calculated values ​​and graded monitoring indicators at several moments, we can get the safety monitoring curve of the dam, such as Figure 4 shown.

[0075] Step nine, compare the measured value δ′ of the dam deformation at the same time with the graded monitoring index proposed in step eight to determine the deformation monitoring status of the dam, as follows:

[0076] 1) If the measured value of dam deformation is within the upper and lower limits of the first-level monitoring index, that is, δ′∈[δ 1d ,δ 1u ], the deformation monitoring status of the dam is determined to be safe;

[0077] 2) If the measured value of dam deformation exceeds the upper and lower limits of the first-level monitoring index, but is within the upper and lower limits of the second-level monitoring index, that is, δ′∈[δ2d ,δ 1d ]∪[δ 1u ,δ 2u ], the deformation monitoring status of the dam is judged to be slightly abnormal;

[0078] 3) If the measured value of dam deformation exceeds the upper and lower limits of the second-level monitoring index, but is within the upper and lower limits of the third-level monitoring index, that is, δ′∈[δ 3d ,δ 2d ]∪[δ 2u ,δ 3u ], the deformation monitoring status of the dam is judged to be abnormal;

[0079] 4) If the measured value of dam deformation exceeds the upper and lower limits of the third-level monitoring index, that is, δ′∈[-∞,δ 3d ]∪[δ 3u ,+∞], the deformation monitoring status of the dam is judged to be dangerous.

[0080] The above are preferred embodiments of the present invention and the technical principles used therein. For those skilled in the art, any obvious changes such as equivalent transformations, simple replacements, etc. based on the technical solution of the present invention, without departing from the spirit and scope of the present invention, are within the scope of protection of the present invention.

Claims

1. A simulation and monitoring coupled concrete dam safety monitoring method, characterized in that: The following steps are involved: S1. Based on the engineering structure design data, the 3D modeling technology is applied to construct a concrete dam finite element mesh model that can reflect the interaction between "dam-bedrock-reservoir water" and meet the needs of coupling analysis of different physical fields; S2. Based on the environmental monitoring data and the dam temperature and deformation monitoring data, the real thermodynamic parameters of concrete and bedrock are obtained through parameter inversion; S3. According to the measured data of reservoir water level, reservoir water temperature and air temperature at different times in history, based on the finite element mesh model and inversion parameters, calculate the deformation value of the dam at different times; subtract the calculated value of the deformation of the dam at different times from the measured value to obtain the deformation residual at different times, and calculate the standard deviation of the residual series as the first-level monitoring threshold for dam safety monitoring; S4. Set the reservoir water level to the normal water level, use the finite element method to calculate the deformation and stress of the dam, gradually increase the head overload coefficient until the dam heel stress exceeds the concrete tensile strength, and subtract the deformation of the dam at this time from the deformation when the dam is not overloaded, and the difference is used as the third-level monitoring threshold for dam safety monitoring; S5. Add the first-level monitoring threshold and the third-level monitoring threshold to obtain an average value, which is used as the second-level monitoring threshold for dam safety monitoring; S6. At a certain moment in the future operation of the concrete dam, real-time measured values ​​of the reservoir water level, reservoir water temperature and air temperature are obtained from the monitoring database; If the measured value is abnormal, the estimated values ​​of the reservoir water level, reservoir water temperature and air temperature at that moment are obtained by interpolation based on the average reservoir water level, average reservoir water temperature and average air temperature of each month over many years; S7. Taking into account the reservoir water level, reservoir water temperature, air temperature boundary conditions, concrete creep, and bedrock rheological material properties at that moment, the deformation of the dam is calculated through "temperature-deformation-stress" coupling analysis; S8. According to the primary, secondary and tertiary monitoring thresholds of the dam safety monitoring determined in steps S3 to S5, and the deformation value of the dam at a certain moment of operation calculated in step S7, determine the hierarchical monitoring index of the dam at that moment, as follows: 1) The calculated value of dam deformation at that moment plus the first-level monitoring threshold is used as the upper limit of the first-level monitoring index; the calculated value of dam deformation at that moment minus the first-level monitoring threshold is used as the lower limit of the first-level monitoring index; 2) The calculated value of dam deformation at that moment is added to the secondary monitoring threshold as the upper limit of the secondary monitoring index; The calculated value of dam deformation at that moment minus the secondary monitoring threshold is used as the lower limit of the secondary monitoring index; 3) The calculated value of dam deformation at that moment is added to the third-level monitoring threshold as the upper limit of the third-level monitoring index; The calculated value of dam deformation at that moment minus the third-level monitoring threshold is used as the lower limit of the third-level monitoring index; S9. Compare the measured value of the dam deformation at the same time with the graded monitoring index prepared in step S8 to determine the deformation monitoring status of the dam, as follows: 1) If the measured value of the dam deformation is within the upper and lower limits of the first-level monitoring index, the deformation monitoring status of the dam is determined to be safe; 2) If the measured value of dam deformation exceeds the upper and lower limits of the first-level monitoring index, but is within the upper and lower limits of the second-level monitoring index, the deformation monitoring status of the dam is judged to be slightly abnormal; 3) If the measured value of the dam deformation exceeds the upper and lower limits of the second-level monitoring index, but is within the upper and lower limits of the third-level monitoring index, the deformation monitoring status of the dam is determined to be abnormal; 4) If the measured value of the dam deformation exceeds the upper and lower limits of the third-level monitoring index, the deformation monitoring status of the dam is judged to be dangerous.

2. The method for safety monitoring of concrete dams by coupling simulation and monitoring according to claim 1 is characterized in that: The first-level monitoring threshold δ1 described in step S3 is: In formula 1, N represents the number of data in the deformation residual series, x i represents the i-th deformation residual, μ represents the mean of the deformation residual series, and S represents the standard deviation of the deformation residual series.

3. The method for safety monitoring of concrete dams by coupling simulation and monitoring according to claim 2 is characterized in that: The three-level monitoring threshold δ3 described in step S4 is: δ3=δ c -d z (2) In formula 2, δ z represents the dam deformation at normal water level without overloading, δ c It refers to the deformation of the dam when the overload at normal water level reaches the point where the heel stress exceeds the tensile strength of the concrete.

4. The method for safety monitoring of concrete dams by coupling simulation and monitoring according to claim 3 is characterized in that: The secondary monitoring threshold δ2 described in step S5 is: In formula 3, δ1 represents the first-level monitoring threshold, and δ3 represents the third-level monitoring threshold.

5. The method for safety monitoring of concrete dams by coupling simulation and monitoring according to claim 4 is characterized in that: The hierarchical monitoring indicators described in step S8 are: In formula 5, δ 1u Indicates the upper limit of the first-level monitoring index, δ 1d Indicates the lower limit of the first-level monitoring indicator, δ 2u Indicates the upper limit of the secondary monitoring index, δ 2d Indicates the lower limit of the secondary monitoring index, δ 3u Indicates the upper limit of the third-level monitoring index, δ 3d It represents the lower limit of the third-level monitoring index, and δ represents the calculated deformation value at a certain moment during the operation of the dam.

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