Prediction method for river training engineering risk based on root stone state and river regime change

Abstract

The application discloses a river prevention engineering risk prediction method based on root stone state and river regime change, and relates to the technical field of water conservancy flood prevention. The method takes each dam of the river prevention engineering as an evaluation unit, collects root stone exploration, pre-flood river regime reconnaissance and model prediction data, extracts and quantifies root stone depth, root stone slope and stone deficiency, combines pre-flood river regime and flood period prediction state to perform standardized scoring, calculates comprehensive scores by using a weighted formula, and maps the comprehensive scores to corresponding defense levels and prevention measures. The application comprehensively considers engineering foundation state and river regime dynamic evolution, corrects logical defects of traditional slope evaluation, realizes risk quantitative evaluation and graded precise prevention and control, and provides a scientific basis for flood prevention resource optimized allocation and active prevention.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy engineering and flood control and emergency rescue technology. Specifically, it relates to a method for predicting the failure of river defense projects based on the state of the foundation stones and changes in the river morphology. Background Technology

[0002] River defense projects are the first line of defense against river floods, maintaining river channel stability, and ensuring the safety of the riverbanks. Under the influence of high flow rates during the flood season, they are prone to hazards such as rockfalls, loss of foundation stones, and instability of dam embankments due to factors like main channel shifts, erosion, and pre-construction scouring. Current project management often relies on qualitative judgments based on historical incidents or empirical models, lacking a method for predicting project hazards that quantifies the co-existence of foundation stone conditions with dynamic changes in river morphology.

[0003] Especially in rivers or river sections where the spatial and temporal distribution of water and sediment is uneven and the river course adjusts rapidly, the flow velocity, scour pit depth, and root slope of the river defense project change significantly. Relying on a single indicator is insufficient to reflect the true risk of the dam in a timely manner, resulting in insufficient targeting of preventive rock dumping, key defense deployment, and personnel and material allocation.

[0004] Therefore, there is an urgent need for a method to predict the risks of river defense projects that can comprehensively assess the basic conditions of the engineering structure and the dynamic changes in the river morphology, provide quantitative evaluation and accurate classification, and guide preventive measures. Summary of the Invention

[0005] The purpose of this invention is to provide a method for predicting the risk of river defense projects based on the condition of the foundation stones and changes in river morphology. This method unifies and quantifies the foundation stone condition before the project, the river morphology survey before the flood season, and the results of the river morphology prediction during the flood season using physical and / or mathematical models. This forms a comprehensive evaluation index system for the risk of river defense projects during the flood season, thereby improving the accuracy of risk assessment, the scientific nature of graded defense, and the pertinence of preventive measures.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for predicting the failure of river defense projects based on the condition of the foundation stones and changes in river morphology includes the following steps: S1: Establish the evaluation object. The smallest evaluation unit is each dam, revetment, and bank protection project in the research river section. The results of pre-flood river morphology survey, pre-construction foundation exploration, and flood season river morphology prediction results from physical and / or mathematical models are collected during the evaluation period.

[0007] Step S1 clarifies the spatiotemporal boundaries of the evaluation and the multi-source data foundation. By breaking down continuous river defense projects into the smallest evaluation units, a refined assessment of "one dam, one file" can be achieved.

[0008] S2: Extract quantitative indicators of root stone condition. Based on the results of the root stone exploration, calculate the root stone depth, root stone slope, and missing stone amount for each evaluation unit.

[0009] Step S2 transforms unstructured exploratory data from the engineering site into calculable quantitative indicators. The depth of the foundation stone determines the erosion resistance reserve, the slope of the foundation stone reflects the stability of the foundation, and the amount of missing stones quantifies the degree of loss in the engineering foundation.

[0010] S3: Determine the root stone condition score. Assign scores to the root stone depth, root stone slope, and missing stone amount to obtain root stone depth score A, root stone slope score B, and missing stone amount score C.

[0011] Step S3 standardizes and normalizes the basic status indicators. In particular, the root rock slope scoring adopts an absolute threshold based on a slope ratio of 1:m, which corrects the logical flaw of the inversion between slope and risk in traditional experience-based judgment.

[0012] S4: Determine the pre-flood river condition score. Based on the relative positional relationship between each evaluation unit and the river condition in the pre-flood river condition survey results, a score is assigned to obtain the pre-flood river condition score D.

[0013] Step S4 captures the current intensity of the mainstream effect on the project as the initial condition for dynamic evaluation.

[0014] S5: Determine the flood season river morphology prediction score. Based on the predicted pre-engineering flow velocity, scour pit depth, and main stream scour intensity from the physical and / or mathematical models, assign a score to obtain the flood season river morphology prediction score E.

[0015] Step S5: Introduce the prediction results of the hydrodynamic model and extend the evaluation time dimension to the "future flood season" to achieve risk warning within the "foreseeability period".

[0016] S6: Calculate the overall score and determine the defense level. Use the overall score formula F= x 1A+ x 2B+ x 3C+ x 4D+ x 5E calculates the comprehensive score F for each evaluation unit, divides the risk range according to the comprehensive score F, and maps the corresponding defense level and preventive measures.

[0017] Step S6 outputs a single comprehensive risk index F by weighted fusion of static and dynamic indicators, and directly maps it to five defense levels and corresponding preventive measures recommendations, thus connecting the entire process from technical assessment to flood control scheduling.

[0018] By adopting the above technical solution, the specific technical effects of the present invention are as follows: (1) Scientificity and accuracy: The logical error in the evaluation of root stone slope was corrected, and the trapezoidal integral method was used to accurately calculate the amount of missing stone, so that the quantitative results are more in line with engineering practice and soil mechanics principles.

[0019] (2) Comprehensiveness and foresight: Taking into account the project's own "physical condition", the current "environment" and future "challenges", we can realize the transformation from passive emergency response to proactive prevention.

[0020] (3) Practicality and operability: The evaluation results are directly linked to the flood control management system, with clear levels and specific measures, providing a scientific basis for flood control command departments to optimize resource allocation. Attached Figure Description

[0021] Figure 1 This is the overall flowchart of the engineering accident prediction method of the present invention; it shows the complete technical route and data flow process from data preparation (S1), indicator extraction and scoring (S2-S5) to comprehensive judgment and decision output (S6).

[0022] Figure 2 This diagram illustrates the indicator system, scoring rules, and weight relationships of the present invention; it visually demonstrates the hierarchical relationship and data flow of the five core evaluation indicators (A, B, C, D, E).

[0023] Figure 3 This diagram illustrates the mapping between the overall score, defense level, and preventative measures; it demonstrates the logical framework of how the numerical range of the overall score F corresponds to the five defense levels. Detailed Implementation

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1: Pre-flood risk assessment of a river control project 1. Evaluation object establishment and data collection (combined) Figure 1 Step S1) Fifteen dam embankments (numbered 1# to 15#) of a river control project were selected as the smallest evaluation unit. Before the flood season, a professional team conducted the following data collection work: Root rock exploration: Multibeam echo sounders are used to obtain topographic data of the root rock cross-sections of easily eroded parts such as the water-facing side and the top of the flow-facing side of each dam revetment; in areas where equipment is limited, manual exploration can be used to obtain the data.

[0026] River terrain survey: The relative position of each dam and the current main stream is recorded by combining drone aerial photography with on-site surveys.

[0027] Model prediction: Using a calibrated two-dimensional hydro-sediment mathematical model, the design flood hydrograph is input to simulate and predict the evolution of river morphology, pre-engineering velocity distribution, and scour pit depth under high flow rates during the flood season.

[0028] 2. Indicator Extraction and Quantification (Combined with...) Figure 1 Step S2) Taking dam #3 as an example: Root stone depth: Five detection sections (10m apart) were set up on the water-facing side. The elevation of the lowest point of the root stone in each section was read and the difference between it and the designed riverbed elevation was calculated. According to statistics, the average root stone depth of the dam is 8.5m.

[0029] Root stone slope: The average slope ratio is calculated based on the cross-sectional data. The measured average slope ratio of the No. 3 dam is 1:1.4 (i.e., slope ratio parameter M=1.4).

[0030] Rock loss calculation: A stable slope ratio of 1:1.5 is set. For the five detection sections set up in this evaluation unit, the measured topographic lines of the sections are compared with the envelope of the 1:1.5 stable slope to obtain the rock loss areas S1 to S5 of each section. The trapezoidal method is used to calculate the rock loss of adjacent section segments. The calculation formula is: V j =((S j +S j+1 ) / 2)×L j L j The length of the retaining wall between the two sections is 10m. The total amount of missing stones is obtained by summing up the missing stone amounts in each section. The total amount of missing stones for dam #3 is calculated to be 120 cubic meters.

[0031] 3. Indicator scoring and weight allocation (combined) Figure 1 Steps S3-S5 and Table 1) According to the evaluation index scoring criteria set by this invention (as shown in Table 1), the No. 3 dam revetment is quantitatively scored: Table 1. Evaluation Indicator Scoring Standards and Weight Allocation

[0032] Note: The specific division method for "first 1 / 3 interval", "middle 1 / 3 interval" and "last 1 / 3 interval" in the table is as follows: Sort the measured values ​​of the foundation stone depth of all evaluation units (15 dam piers in this example) in the same project from largest to smallest, and assign the intervals of the first 1 / 3 (i.e. the 5 with the largest depth), the middle 1 / 3 and the last 1 / 3 (i.e. the 5 with the shallowest depth) to deep, relatively deep and relatively shallow, respectively; Sort the measured values ​​of missing stone amount from smallest to largest, and assign the intervals of the first 1 / 3, the middle 1 / 3 and the last 1 / 3 to smaller, larger and larger, respectively.

[0033] Scoring of Dam #3 based on Table 1: The foundation stone depth score A: 8.5m is in the shallowest 1 / 3 section of the entire project (the last 1 / 3), so A=3.

[0034] Root stone slope score B: The measured m=1.4, which falls within the range of 1.3≤m<1.5, so B=2.

[0035] Stone deficiency score C: 120 cubic meters is in the largest 1 / 3 range of the entire project (the last 1 / 3), so C=3.

[0036] Pre-flood river condition score D: On-site inspection shows that the river is currently in a "flowing" state, so D=2.

[0037] River course prediction score during flood season E: The mathematical model predicts that the main current will "rush" against the dam during the flood season, so E=3.

[0038] Weighting: Based on expert experience and management priorities, this embodiment adopts preset preferred weight values: x 1 = 0.10 x 2 = 0.10 x 3 = 0.30 x 4 = 0.30 x 5 = 0.20.

[0039] 4. Comprehensive scoring and grade determination (combined) Figure 1 Step S6 Figure 3 (and Table 2) Using the comprehensive scoring formula F= x 1A+ x 2B+ x 3C+ x 4D+ x 5E Calculation of the Comprehensive Score of Dam #3: F=0.1×3+0.1×2+0.3×3+0.3×2+0.2×3=0.3+0.2+0.9+0.6+0.6=2.6 Based on the comprehensive score and defense level mapping relationship established according to this invention (as shown in Table 2), risk classification and measure matching are performed: Table 2 Mapping Table of Overall Score, Defense Level, and Preventive Measures

[0040] Output of the judgment result: The comprehensive score of dam #3 is F=2.6, falling within the range of (2.4, 3.0). The system automatically determines its risk level as "high risk" and its defense level as "defense".

[0041] The system outputs the following instructions: requiring the management department to immediately implement comprehensive pre-flood rock reinforcement (focusing on replenishing the 120 cubic meters of missing rock); and to arrange for dedicated personnel to be stationed on the dam during the flood season, and to deploy large-scale emergency rescue machinery and materials such as gabions on the dam top in advance.

[0042] Example 2: Comparative Analysis of Dam #8 in the Same Project The same method was used to evaluate dam #8: Indicator status and score (refer to Table 1): Deep root stone (A=1), gentle slope m=1.8 (B=1), small amount of missing stone (C=1), pre-flood survey shows "not near the river" (D=0), model predicts the main stream is far away during the flood season (E=0).

[0043] Overall score F: F = 0.1×1 + 0.1×1 + 0.3×1 + 0.3×0 + 0.2×0 = 0.5 Judgment result (refer to Table 2): F=0.5 falls within the range of [0,1.2], and is judged as "low risk", with a defense level of "routine patrol".

[0044] Implementation Results: Through this method and the standardized mapping in Tables 1 and 2, the management department accurately identified the high-risk units of Dam #3 and pre-positioned resources, while only routine management was carried out on low-risk units such as Dam #8, completely changing the previous blind defense model of "one-size-fits-all" or "relying on experience".

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the failure of river defense projects based on the condition of the foundation stones and changes in river morphology, characterized in that: Includes the following steps: S1. Establish evaluation objects: take each dam, revetment, and bank protection project in the research river section as the smallest evaluation unit, and collect the pre-flood river condition survey results, pre-project foundation stone exploration results, and flood season river condition prediction results of physical models and / or mathematical models during the evaluation period. S2. Extract quantitative indicators of root stone status: Based on the results of the root stone exploration, calculate the root stone depth, root stone slope and missing stone amount of each evaluation unit; S3. Determine the root stone status score: Assign scores to the root stone depth, root stone slope, and missing stone amount to obtain root stone depth score A, root stone slope score B, and missing stone amount score C. S4. Determine the pre-flood river condition score: Assign scores based on the relative positional relationship between each evaluation unit and the river condition in the pre-flood river condition survey results to obtain the pre-flood river condition score D; S5. Determine the flood season river morphology prediction score: Assign scores based on the pre-engineering flow velocity, scour pit depth, and main stream scour intensity predicted by the physical model and / or mathematical model to obtain the flood season river morphology prediction score E. S6. Calculate the overall score and determine the defense level: Use the overall score formula F= x 1A+ x 2B+ x 3C+ x 4D+ x 5E calculates the comprehensive score F for each evaluation unit, divides the risk range according to the comprehensive score F, and maps the corresponding defense level and preventive measures. in, x 1. x 2. x 3. x 4. x 5 represents the weighting coefficient for each scoring item, determined based on the importance of each indicator in the actual river section studied. x 1+ x 2+ x 3+ x 4+ x 5 = 1.

2. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: In step S1, the results of the root stone exploration are obtained by using a multibeam echo sounder or manual exploration to acquire the topographic data of the root stone cross-section on the water-facing side and the easily eroded parts of each evaluation unit; the results of the pre-flood river morphology survey are obtained by using drone aerial photography combined with on-site survey.

3. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: The method for calculating the amount of missing stones in step S2 is as follows: Set 1:1.5 as the stable slope ratio, set up multiple detection sections for each evaluation unit, compare the measured topographic lines of the sections with the envelope of the stable slope, and obtain the rock-deficient area of ​​each section. The trapezoidal method is used to calculate the amount of missing stones in adjacent cross-sectional sections. The calculation formula is: V j =((S j +S j+1 ) / 2)×L j ; Among them, S j and S j+1 The missing stone areas of two adjacent cross sections are L. j The length of the protective layer between the two sections is given; the total amount of missing stones in the evaluation unit is obtained by summing up the missing stone amounts in each section.

4. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: The scoring rules in step S3 are as follows: Root stone depth rating A: Based on the absolute depth threshold or the tertiles of the sample distribution within the same project, it is divided into three levels from deep to shallow: deep, relatively deep, and relatively shallow, corresponding to 1 point, 2 points, and 3 points respectively. Root stone slope rating B: expressed as a slope ratio of 1:m, where m is the ratio of horizontal width to vertical height; when m≥1.5, it is scored as 1 point, when 1.3≤m<1.5, it is scored as 2 points, and when m<1.3, it is scored as 3 points. Stone deficiency score C: Based on the absolute stone deficiency threshold or the ternary digits of the sample distribution within the same project, it is divided into three levels from small to large: small, large, and large, corresponding to 1 point, 2 points, and 3 points respectively. The higher the score for each rating item, the higher the risk of an incident.

5. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 4, characterized in that: When using the ternary digits of the sample distribution within the same project for division, the measured values ​​of the root stone depth of all evaluation units within the same project are sorted from largest to smallest, and the first 1 / 3, middle 1 / 3, and last 1 / 3 intervals are respectively assigned to the three levels of deep, relatively deep, and relatively shallow; the measured values ​​of missing stone are sorted from smallest to largest, and the first 1 / 3, middle 1 / 3, and last 1 / 3 intervals are respectively assigned to the three levels of smaller, larger, and larger.

6. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: The scoring rules for the pre-flood river condition score D in step S4 are as follows: Based on the relative relationship between the evaluation unit and the mainstream, not being near the river is scored as 0 points, being near the river is scored as 1 point, being near the stream is scored as 2 points, and being at the top of the stream is scored as 3 points.

7. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: In step S5, the mathematical model is a two-dimensional hydro-sediment mathematical model, which simulates and predicts the river morphology evolution under a large flow process during the flood season by inputting the design flood hydrograph; the scoring rules for the flood season river morphology prediction score E are as follows: The relative positions of the main stream and the engineering works during the flood process are determined comprehensively based on physical model tests and / or mathematical model calculations; when the main stream is predicted to be far away from the engineering works, 0 points are awarded; when the main stream is predicted to be close to the river, close to the current, or close to the surging force, 1 point, 2 points, and 3 points are awarded respectively.

8. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: In step S6, the weight coefficients are determined by the analytic hierarchy process (AHP) or by using preset preferred weight values. x 1 = 0.10 x 2 = 0.10 x 3 = 0.30 x 4 = 0.30 x 5 = 0.

20.

9. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 1, characterized in that: The risk range is divided in step S6 as follows: The comprehensive score F of all evaluation units within the study river section is divided into five intervals according to the probability of five equal parts or a preset threshold: low risk, low-medium risk, medium risk, medium-high risk, and high risk.

10. The method for predicting the failure of river defense projects based on the state of the foundation stones and changes in river morphology according to claim 9, characterized in that: The five zones correspond to five defense levels: routine patrol, attention, key attention, defense, and key defense. When the level is determined to be defensive or key defensive, the preventive measures include: pre-flood reinforcement with riprap to replenish missing stones, assigning dedicated personnel to guard the area and increasing the frequency of patrols during the flood season, and deploying emergency materials and large machinery in advance.

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