Sandy river bank collapse real-time monitoring and early warning method

Abstract

The invention provides a sandy river bank collapse real-time monitoring and early warning method. The method comprises the following steps: determining a bank collapse monitoring section; measuring a sediment underwater repose angle as a critical instability slope angle phi through an indoor test, and calculating a critical slope toe position; arranging a rigid long rod monitoring device with a photosensitive sensor, and transmitting light intensity data in real time; a real-time slope toe scouring position, an underwater bank slope angle theta and an erosion rate v are obtained based on light intensity signal analysis; comparing theta with phi, dividing early warning levels and triggering a signal; and adjusting the monitoring frequency according to the early warning level, estimating the bank collapse remaining time in combination with the erosion rate, and taking engineering measures or evacuating if necessary. Through automatic high-frequency monitoring, manpower is saved, early warning calculation is simplified, and efficiency is improved; the bank collapse time and the hidden danger level can be predicted through graded early warning, the prevention and treatment cost is reduced through accurate strategy, and technical reference is provided for sandy river bank collapse monitoring and early warning.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bank erosion and bank slope stability monitoring and early warning, and particularly relates to a sandy bank collapse real-time monitoring and early warning method. BACKGROUND

[0002] In the evolution process of natural alluvial plain rivers, bank collapse is very common. Under the influence of water flow and other factors, bank collapse often occurs. After bank collapse occurs, the planform of the river changes, which further triggers the continuous adjustment of the river regime upstream and downstream, and has a negative impact on the flood control capacity, navigation conditions, island and beach ecology, and the protection and utilization of the shoreline, and becomes one of the main geological disasters faced by alluvial plain rivers. Therefore, it is particularly important to carry out monitoring, early warning and evaluation research on bank collapse.

[0003] There are many influencing factors of bank collapse danger, and the bank collapse occurs in natural river sections that have not been artificially managed. Due to the lack of monitoring means and technology, it is difficult to warn of bank collapse. The existing bank collapse monitoring and early warning technology is not yet fully mature. The monitoring of underwater bank slope currently relies on a multi-beam sounding system. However, the multi-beam sounding system requires a large amount of manpower and material resources, and due to the long monitoring time interval, it cannot carry out continuous monitoring for years. The workload and cost are large, the timeliness is weak, the experience is strong, the monitoring frequency is low, and it cannot provide real-time continuous underwater bank slope topographic change data, and cannot achieve the purpose of real-time monitoring. On the other hand, there are two methods for bank collapse warning, one is for binary or multi-element bank slope, and the collapse mechanism is complex, which requires special bank slope stability model calculation; the other is for single soil bank slope, and the collapse is mostly downward landslide, and there is a critical stable slope for the clay bank slope, and many factors need to be determined by special test or model. SUMMARY

[0004] To solve the above technical problems, the present application provides a sandy bank collapse real-time monitoring and early warning method, which saves manpower through automatic high-frequency monitoring, simplifies early warning calculation and improves efficiency; graded early warning can predict the bank collapse time and hidden danger level, accurately implement measures to reduce prevention and control costs, and provides technical reference for sandy bank collapse monitoring and early warning.

[0005] A sandy bank collapse real-time monitoring and early warning method, comprising the following steps:

[0006] S1, monitoring section determination: according to the bank collapse occurrence area and frequency in previous years, combined with the actual underwater bank slope, the bank collapse monitoring section is determined, and the bank slope position is recorded on site;

[0007] S2, critical slope angle determination: collect the soil sample of the bank slope at the bank collapse monitoring section, determine the angle between the sediment slope surface and the horizontal plane after the natural accumulation and stabilization of the sediment as the underwater repose angle through indoor gradation analysis and underwater repose angle test, take the average value of multiple measurements of the underwater repose angle as the critical unstable slope angle φ, and calculate the critical unstable slope toe position in combination with the bank slope height;

[0008] S3, monitoring device layout: horizontally bury the transparent rigid long rod with photosensitive sensors at the bottom of the underwater slope toe, record the height from the buried position to the slope top as the slope height H and the distance from the slope toe to the intersection of the water surface and the slope surface as the slope length L 坡 ; the sensors are equally spaced in the long rod, the first sensor at the head aligns with the initial slope toe position, the tail is connected to the ground signal transmitter through the transmitting antenna, and the light intensity data is transmitted in real time;

[0009] S4, data transmission and analysis: determine the slope toe erosion position L 实时 in real time through the light intensity signal of the photosensitive sensor; 实时 calculate the underwater bank slope angle θ and the erosion and scour rate v according to the slope toe erosion position L

[0010] S5, hierarchical early warning trigger: compare the real-time underwater bank slope angle θ with the critical unstable slope angle φ, divide the warning levels according to the difference and send signals;

[0011] S6, warning correction and emergency: adjust the monitoring frequency according to the warning level; estimate the bank collapse remaining time in combination with the erosion rate v, and take engineering measures or issue evacuation instructions if necessary.

[0012] Further, the underwater repose angle test in S2 is specifically: slowly pour the sediment sample into the water container until it naturally accumulates and stabilizes, and use a protractor or professional instrument to measure the angle between the sediment slope surface and the horizontal plane, and take the average value of repeated measurements.

[0013] Further, the photosensitive sensor number of the transparent rigid long rod in S3 increases sequentially from the initial slope toe position to the interior of the bank slope, and the light intensity signal is output through the inverse relationship between the resistance value of the photosensitive resistor and the light intensity.

[0014] Further, the inverse relationship between the resistance value of the photosensitive resistor and the light intensity is R=K / I, R is the resistance value, I is the light intensity, and K is the proportionality constant.

[0015] Further, in S4, L 实时 =L 初始 -xd, L 初始 is the horizontal distance from the initial slope toe position P 初始 to the intersection P of the water surface and the slope surface, x is the sensor number corresponding to the real-time slope toe erosion position, the first sensor at the head aligns with the initial slope toe position and the number is 0, d is the sensor spacing; L 初始= H / tanθ0, where H is the slope height and θ0 is the initial bank slope angle.

[0016] Furthermore, in S4, based on the slope toe scour position L 实时 The formula for calculating the underwater slope angle θ is as follows: .

[0017] Furthermore, in S4, based on the slope toe scour position L 实时 The erosion rate ν at the toe of the slope is calculated using the following formula: , Δt represents the difference in scour position at the toe of the slope at different time points, and Δt represents the scour duration.

[0018] Furthermore, in S5, the real-time underwater slope angle θ is compared with the critical instability slope angle φ, and the warning level is divided according to the difference and a signal is issued. Specifically, a green signal is issued when θ≤φ-6°, a yellow signal is issued when φ-6°<θ≤φ-4°, an orange signal is issued when φ-4°<θ≤φ-2°, and a red signal is issued when φ-2°<θ≤φ.

[0019] Among them, the red warning point P corresponds to θ=φ, and the orange warning point P 橙 Corresponding to θ=φ-2°, yellow warning point P 黄 Corresponding to θ=φ-4°, green warning point P 绿 The corresponding θ = φ - 6°; the location of each warning point is determined by L = H / tanθ, the point on the water-facing side of the slope top is designated as point P, and the position where the vertical extension of point P intersects with the transparent rod is designated as P0, and L is the distance between P0 and the warning point; each warning point is determined by extending the line from the intersection point P of the water surface and the slope surface to the corresponding angle and intersecting with the extension line of the rod.

[0020] Furthermore, in S6, the monitoring frequency is adjusted according to the warning level. Specifically, for the orange warning segment, the real-time erosion rate is compared with the historical daily average rate. If the real-time rate is greater than 1.5 times the historical rate, it is upgraded to a red warning. The red warning segment requires monitoring once every 3 hours.

[0021] Furthermore, the engineering measures taken in S6 include scattering gabion sandbags.

[0022] Compared with existing bank collapse monitoring technologies, this invention has the following advantages and beneficial effects:

[0023] 1. The present application combines a monitoring device, a data transmission device and a remote analysis device to calculate the recent underwater slope toe erosion position, underwater bank slope angle and erosion rate in real time, and can timely detect abnormalities before bank collapse occurs. The present application can realize automatic normal high-frequency monitoring, save a lot of manpower, material and financial resources, and help water-related departments to quickly grasp the erosion information of the underwater bank slope of each bank section in real time, so as to timely take effective measures to avoid the occurrence of bank collapse or reduce the loss caused by bank collapse.

[0024] 2. The present application provides an online early warning system for sandy bank collapse by combining the bank slope critical angle judgment method of the underwater angle of repose, avoiding the complex model calculation of the background in the past, simplifying the early warning calculation workload, and improving the efficiency and timeliness of the early warning.

[0025] 3. The present application provides a different color bank collapse early warning point grading method, which can predict the approximate time of bank collapse and divide the severity level of bank collapse hazards, and gives subsequent measures under different circumstances, which not only achieves the purpose of preventing bank collapse and emergency monitoring, but also avoids unnecessary excessive protection, accurately implements measures, reduces the cost of bank collapse prevention, and provides an important technical reference for bank collapse monitoring and early warning. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a flow chart of a sandy bank collapse real-time monitoring and early warning method of the present application;

[0027] Figure 2 is a structural schematic diagram of a sandy bank collapse real-time monitoring and early warning device of the present application;

[0028] Figure 3 is a schematic diagram of each color early warning point of the present application;

[0029] Figure 4 is a bank slope terrain obtained by routine measurement of a certain river section in the present application;

[0030] Figure 5 is a schematic diagram of the slope toe erosion point reaching the corresponding color bank collapse early warning point in the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] The embodiment of the application takes the bank collapse early warning device embedded in the left sandy bank slope of a certain river section as an example to further illustrate the technical scheme of the application.

[0033] As shown in Figure 1 , a real-time monitoring and early warning method for sandy bank collapse includes the following steps:

[0034] S1, monitoring section determination: the section of a certain river section is located at a sharp bend of the river channel (as shown in Figure 3 ), the thalweg is close to the right bank, and a dam is built on the right bank for protection, the left bank has no revetment engineering and is a single structure sandy bank slope, which has collapsed several times between 2016 and 2021, the waterline has retreated about 78.12m, and the shoreline has retreated about 47.48m. The underwater repose angle of the bank slope is =34.6°, which is obtained by sampling the sand at the critical slope angle of the site during the post-flood recession period in 2025, the actual slope of the underwater bank slope is 30°, and the difference between the two is less than 6°, so the bank slope section is listed as a monitoring section, and the bank slope topography obtained by the hydrological department through annual routine measurement is shown in Figure 4 .

[0035] S2, critical slope angle determination: soil sampling is carried out on the section to be monitored, indoor gradation analysis and underwater repose angle test are carried out, sand samples and water containers are prepared, water is poured into the container to a certain slope height, sand is slowly poured to make it naturally accumulate, after the sand is completely settled and stable, the angle between the sand slope and the horizontal plane is measured using a protractor or professional instrument, which is the underwater repose angle, and the average value is recorded by repeating the measurement multiple times. The underwater repose angle obtained by the test is taken as the critical instability slope angle φ, and combined with the height of the bank slope, the position of the critical instability slope toe can be obtained.

[0036] S3, monitoring device layout: in the real-time monitoring device, a transparent rigid long rod with a photosensitive sensor is arranged horizontally inside the underwater slope toe, and the height from the buried position to the top of the slope is recorded as 3m, which is denoted as slope height H=3m, the initial slope toe degree θ0 is 30°, and the intersection of the water surface and the bank slope is measured downward vertically to the position intersected with the transparent long rod, which is denoted as P0. The slope length L 坡= =H / sinθ0=3m / sin30°=6m under the initial slope toe condition, the total length L 初始 =H / tanθ0=3m / tan30°=5.20m from point P0 to the head of the device under the initial slope angle condition. The sensors are equally spaced inside the transparent rigid long rod, with a spacing d of 5cm, and the first photosensitive sensor located at the head of the device is aligned at the scouring position of the underwater slope toe, numbered 0, and sequentially numbered inward (as shown in Figure 2(The photosensitive sensors 0-2 are deployed at equal intervals. At this time, the photosensitive sensors output light intensity parameters through the input light intensity changes. A real-time signal transmitter is installed at the end of the long pole and extended to the ground with an antenna to transmit the sensor light intensity parameters in real time.)

[0037] like Figure 2 As shown, the real-time monitoring device consists of a transparent, rigid rod with a photosensitive sensor section and a signal transmitter and transmitting antenna at the tail. ① is the photosensitive sensor, ② is the signal transmitter, and ③ is the signal antenna. In the diagram, 0, 1, and 2 are the photosensitive sensor numbers. A signal transmission device is positioned around the real-time monitoring device (such as a temporary field signal transmission station) to receive the light intensity parameters recorded by the photosensitive sensor from the real-time monitoring device and transmit them to a remote analysis device (such as a mobile phone or computer terminal).

[0038] S4. Data transmission and analysis: After installation, real-time monitoring is performed. Based on the slope morphology, remote analysis can be performed. The terminal can remotely analyze and calculate the underwater slope toe scour location, underwater slope angle and erosion rate through the light intensity parameters output by the photosensitive sensor.

[0039] Calculation of underwater slope toe scour location: During installation, the slope toe scour location is sensor number 0. If, after one day of water scour, the light intensity output of sensors 0 to 2 is not 0, and sensor number 3 is 0, then the slope toe scour location can be defined as the location of sensor number 2. The slope toe scour location difference = 2 × 0.05 m = 0.1 m, indicating that the bank slope has been scoured inward by 0.1 m compared to the initial working conditions.

[0040] Underwater bank slope angle calculation: Points P0 and P are obtained from the scour location at the toe of the slope. 实时 The length L between 实时 The tangent of this tangent to the slope height H is calculated, and the resulting angle represents the corresponding real-time underwater slope gradient. This is then combined with the slope height H and L recorded in S1. 实时 The underwater bank slope angle can be obtained using the following formula:

[0041]

[0042] In the formula: θ is the underwater bank slope angle; H is the slope height; L 实时 Let P0 and P 实时 The length between, L 实时 =L 初始 -xd,L 初始 Let P be the initial slope toe position. 初始 The horizontal distance to the intersection point P of the water surface and the slope surface; x is the sensor number corresponding to the real-time slope toe scour position; the first sensor at the head, aligned with the initial slope toe position, is numbered 0; d is the sensor spacing; L 初始 =H / tanθ0, where θ0 is the initial bank slope heel.

[0043] 1 day later, the total length L from P0 to the real-time scouring position of the slope toe can be obtained by the scouring position of the slope toe 实时 , and the sine value of H is calculated, and the angle size is the underwater slope gradient. The photosensitive sensor data shows that the 2nd sensor is the real-time scouring position of the slope toe at this time,

[0044] L 实时 = 2d = 4 x 0.05 = 0.2 m 初始 - 2d = 5.20 - 2 x 0.05 = 5.1 m.

[0045] The underwater slope angle is calculated by the following formula combined with the H recorded in S1:

[0046] 0.5882, θ ≈ 30.4°

[0047] In the formula: θ is the underwater slope angle; H is the slope height; L 实时 is the total length from P0 to the real-time scouring position of the slope toe. It shows that the underwater slope angle increases by 0.4° in 1 day, and the underwater angle of repose of 34.6°, which is the critical angle of bank collapse, still differs by 4.2°; similarly, the underwater slope angles of the 1st to 7th days are measured as 30.4°, 30.7°, 31.2°, 32°, 32.5°, 33.7°, and 34.6°, respectively.

[0048] Erosion and scouring rate calculation: the recent riverbank erosion rate of the bank section can be obtained by dividing the difference between the real-time scouring positions at two time points by the time length of scouring. For example, if the initial scouring position of the slope toe is the 0th sensor and the scouring position after 1 day is the 2nd sensor, then = 2d = 4 x 0.05 = 0.2 m, = 1d, and the scouring rate of the slope toe is calculated by the following formula:

[0049]

[0050] In the formula: is the scouring rate of the slope toe; is the difference between the scouring positions of the slope toe at different time points; is the time length of scouring. Similarly, the scouring rates of the 1st to 7th days are measured as 0.1, 0.05, 0.1, 0.15, 0.1, 0.2, and 0.2 meters per day, respectively.

[0051] S5, graded early warning triggering: according to the sizes of the corresponding measured underwater slope gradient and underwater angle of repose, the positions of the photosensitive sensors in the real-time monitoring devices at different warning threshold positions are determined. If the corresponding gradient warning threshold is exceeded, the corresponding bank collapse warning signal is sent out to achieve the purpose of long-distance real-time monitoring and warning of bank collapse.

[0052] The underwater angle of repose was measured through tests on the sandy bank slopes of the monitoring area. The angle is 34.6°. In this case, the total length from point P0 to the scour point at the toe of the slope is: L 临界 =H / tan =3m / tan34.6°=4.35m.

[0053] With an initial slope angle θ0 = 30°, the distance from point P0 to the slope toe scour position (i.e., the position of sensor 0):

[0054] L 初始 =H / tanθ0=3m / tan30°=5.20m. The difference between the two is... =L 初始 -L 临界 =5.20m - 4.35m = 0.85m, then the critical point P for bank collapse under the underwater angle of repose is... 临界 The sensor number is .

[0055] The above-described critical point of bank collapse, P 临界 As a red alert point P 红 At the location of sensor number 17, by increasing the underwater repose angle at the critical point of bank collapse by 2° and repeating this process three times, and then successively taking the intersection points according to the above method, orange warning point P was obtained. 橙 Yellow alert point P 黄 Green warning point P 绿 .

[0056] For example, the underwater slope angle corresponding to an orange alert point is... ° = 34.6° - 2° = 32.6°, the angle for an orange alert is... The total length L from point P0 to the scour point at the slope toe at a 32.6° angle. 橙 =H / tan =3m / tan32.6°=4.71m. L 初始 -L 橙 =5.20m - 4.71m = 0.49m, then the corresponding orange critical point P under the orange warning angle condition. 橙 The sensor number is .

[0057] The yellow warning point corresponds to the underwater slope angle. °=34.6°-4°=30.6°, and the yellow warning angle is 30.6°. The total length L from point P0 to the slope toe scour location is L. 黄 =H / tan =3m / tan30.6°=4.98m. L 初始 -L 黄= 5.20m - 4.98m = 0.22m, so the orange critical point P 橙 The sensor number where the point is located is .

[0058] The green warning point corresponds to an underwater shore slope angle of ° = 34.6° - 6° = 28.6°, which is less than the initial slope angle = 30°, indicating that the green warning point has been reached under the initial conditions and the erosion continues to the yellow warning point, and the initial state has reached the yellow warning state.

[0059] Compare the calculated warning points of each landslide with the real-time measured scour point of the slope toe. When the scour point of the slope toe reaches the corresponding color landslide warning point, issue the corresponding color landslide warning. Specifically, as shown in Figure 5 , when the scour point of the slope toe is between the initial scour point P 初始 (the location of the 0th sensor) and the yellow warning point P 黄 (the location of the 4th sensor), the stability of the shore slope decreases, the slope angle differs from the underwater rest angle by 4-6°, and it is defined as the yellow warning section. Similarly, when the scour point of the slope toe is between the yellow warning point P 黄 (the location of the 4th sensor) and the orange warning point P 橙 (the location of the 9th sensor), it is defined as the orange warning state, the slope toe differs from the underwater rest angle by 2-4°, and it is defined as the orange warning section. When the scour point of the slope toe is between the orange warning point P 橙 (the location of the 9th sensor) and the red warning point P 红 (the location of the 17th sensor), the slope toe differs from the underwater rest angle by 2° or less, and it is defined as the red warning section. When the scour point of the slope toe reaches the critical landslide point P 红 (the location of the 17th sensor), the landslide occurs.

[0060] In this example, through daily monitoring, it is measured that the scour position of the slope toe is initially located at the 0th sensor, after 1 day the scour position of the slope toe is located at the 2nd sensor, on the 2nd day it is located at the 3rd sensor, on the 3rd day it reaches the yellow warning point (4th sensor), on the 4th day it is located at the 7th sensor, on the 5th day it reaches the orange warning point (9th sensor), on the 6th day it reaches the 13th sensor, and on the 7th day it reaches the red warning point (17th sensor), i.e., it reaches the critical state of landslide. Therefore, it is indicated that the yellow warning should be issued on the 0th-2nd day, the orange warning on the 3rd-5th day, and the red warning on the 5th-7th day.

[0061] S6, warning correction and emergency: subsequent monitoring and data analysis are performed on abnormal warning sections, further correction is made on the landslide warning, and special emergency monitoring and engineering measures are carried out on necessary areas.

[0062] In this example, through daily monitoring, it is measured that the toe erosion position is initially located at No. 0 sensor, 1 day later the toe erosion position is located at No. 2 sensor, 2 days later at No. 3 sensor, 3 days later reaches the yellow warning point (No. 4 sensor), 4 days later at No. 7 sensor, 5 days later reaches the orange warning point (No. 9 sensor), 6 days later reaches No. 13 sensor, and 7 days later reaches the red warning point (No. 17 sensor), i.e. reaches the critical state of bank collapse. Through the calculation of S3 step, the toe erosion rates from the 1st day to the 7th day are 0.1, 0.05, 0.1, 0.15, 0.1, 0.2, 0.2 m / day, and the underwater bank slope angles are 30.4°, 30.7°, 31.2°, 32°, 32.5°, 33.7°, 34.6°, respectively.

[0063] a. For the yellow warning bank section of bank collapse, normal daily monitoring is carried out, the corresponding warning level is changed when reaching different color warning points, and the daily toe erosion rate is calculated.

[0064] In this example, the initial toe erosion point is located in the yellow warning bank section, so the yellow warning level is displayed, and the a plan is carried out from the 0th day to the 2nd day.

[0065] b. For the orange warning bank section of bank collapse, more detailed daily monitoring is carried out, the daily underwater toe erosion position, real-time bank slope angle and toe erosion rate are recorded. The remaining time to reach the critical state of bank collapse is estimated according to the latest erosion rate measured by the sensor parameters, and the historical daily erosion rate is combined. If the real-time erosion rate is greater than 1.5 times of the historical daily erosion rate, the warning level is upgraded to red, and the c procedure is executed, otherwise the orange warning level is maintained.

[0066] In this example, the toe erosion position is located at No. 4-9 sensor from the 3rd day to the 5th day, which is the orange warning level. For example, the toe erosion position is No. 7 sensor on the 4th day, the erosion rate is 0.15 m / day, the distance to the critical point of bank collapse (No. 17 sensor) is 10 x 0.05 = 0.5 m, and the estimated remaining bank collapse time is 0.5 / 0.15 = 3.3 days, indicating that there will be bank collapse in 3.3 days according to the monitoring data of the 4th day. The real-time erosion rates of 0.1, 0.15, 0.1 m / day from the 3rd day to the 5th day are not greater than 1.5 times of the erosion rates of 0.1, 0.05 m / day from the 0th day to the 2nd day, so the orange warning level is maintained and the b procedure is executed.

[0067] c. For the red warning bank section of bank collapse, multiple monitoring is required every day, such as once every 3 hours, the remaining time to reach the critical state of bank collapse is estimated according to the latest erosion rate measured by the sensor parameters, which provides technical support for bank collapse warning work, and necessary engineering measures are combined to prevent bank collapse or reduce economic losses after bank collapse.

[0068] In this example, the red alert level is from the 5th to the 7th day, so multiple monitoring needs to be performed within 1 day, such as the initial erosion rate of 0.2 m / d (0.83 cm / h) at 6 o'clock in the morning on the 6th day, and the angle of 33.7°, and the rate of 0.18, 0.23, 0.21, and 0.25 m / d (0.75 cm / h, 0.96 cm / h, 0.88 cm / h, and 0.75 cm / h) is obtained by multiple monitoring every 3 hours in the subsequent daytime period, and the angle is 33.8°, 33.9°, 34.0°, and 34.2°, and the distance from the red critical point of bank collapse (the 17th sensor) is 0.18 m, 0.15 m, 0.13 m, 0.11 m, and 0.08 m. Then, according to the latest erosion rate of 0.25 m / d (0.75 cm / h) at 18 o'clock in the evening on the 6th day, the remaining bank collapse time is calculated as 0.08 / 0.25 = 0.32 days = 7.7 hours, which indicates that bank collapse will occur in 7.7 hours, and relevant instructions need to be issued in time and combined with corresponding engineering measures such as manual throwing of stone cages and sandbags to prevent bank collapse or reduce economic losses after bank collapse.

[0069] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed by the present application can be easily thought of by any person skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for real-time monitoring and early warning of sandy riverbank collapse, characterized in that, Includes the following steps: S1. Determination of monitoring sections: Based on the areas and frequencies of bank collapses over the years, and in conjunction with the actual underwater bank slope, determine the monitoring sections for bank collapses and record the bank slope locations on-site. S2. Determination of critical slope angle: Collect soil samples from the bank slope at the bank collapse monitoring section. Through indoor gradation analysis and underwater angle of repose test, determine the angle between the silt slope surface and the horizontal plane after natural accumulation and stabilization of silt as the underwater angle of repose. Take the average value of multiple underwater angle of repose measurements as the critical instability slope angle φ, and calculate the critical instability slope toe position in combination with the bank slope height. S3. Monitoring Device Deployment: A transparent, rigid, long rod equipped with a photosensitive sensor is horizontally buried at the bottom of the underwater slope toe. The height from the burial position to the top of the slope is recorded as the slope height H, and the distance from the toe of the slope to the intersection of the water surface and the slope surface is recorded as the slope length L. 坡 The sensors are evenly spaced inside the long pole, with the first sensor at the head aligned with the initial foot of the slope, and the tail connected to the ground signal transmitter via a transmitting antenna to transmit light intensity data in real time. S4. Data Transmission and Analysis: The location of scour at the toe of the slope is determined in real time using the light intensity signal from the photosensitive sensor. 实时 According to the scour location L at the toe of the slope 实时 Calculate the underwater bank slope angle θ and the erosion rate ν; S5. Graded Early Warning Trigger: Compare the real-time underwater slope angle θ with the critical instability slope angle φ, classify the early warning level according to the difference and issue a signal; S6. Early Warning Correction and Emergency Response: Adjust the monitoring frequency according to the early warning level; estimate the remaining time of bank collapse based on the erosion rate ν, and take engineering measures or issue evacuation orders when necessary.

2. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 1, characterized in that: The underwater angle of repose test in S2 is specifically as follows: the sediment sample is slowly poured into a water-filled container until it settles naturally and stabilizes. The angle between the sediment slope and the horizontal plane is measured using a protractor or professional instrument. The measurement is repeated and the average value is taken.

3. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 1, characterized in that: The photosensitive sensors on the transparent rigid rod in S3 are numbered sequentially from the initial slope foot position towards the interior of the slope, and the light intensity signal is output through the inverse relationship between the resistance value of the photoresistor and the light intensity.

4. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 3, characterized in that: The inverse relationship between the resistance of the photoresistor and the light intensity is R=K / I, where R is the resistance, I is the light intensity, and K is a proportionality constant.

5. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 1, characterized in that: L in S4 实时 =L 初始 -xd,L 初始 Let P be the initial slope toe position. 初始 The horizontal distance to the intersection point P of the water surface and the slope surface; x is the sensor number corresponding to the real-time slope toe scour position; the first sensor at the head, aligned with the initial slope toe position, is numbered 0; d is the sensor spacing; L 初始 =H / tanθ0, where H is the slope height and θ0 is the initial bank slope angle.

6. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 5, characterized in that: In S4, based on the slope toe scour position L 实时 The formula for calculating the underwater slope angle θ is as follows: .

7. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 5, characterized in that: In S4, based on the slope toe scour position L 实时 The erosion rate ν at the toe of the slope is calculated using the following formula: , Δt represents the difference in scour position at the toe of the slope at different time points, and Δt represents the scour duration.

8. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 1, characterized in that: In S5, the real-time underwater slope angle θ is compared with the critical instability slope angle φ, and the warning level is divided according to the difference and a signal is issued. Specifically, a green signal is issued when θ≤φ-6°, a yellow signal is issued when φ-6°<θ≤φ-4°, an orange signal is issued when φ-4°<θ≤φ-2°, and a red signal is issued when φ-2°<θ≤φ. Among them, red alert point P 红 Corresponding to θ=φ, orange warning point P 橙 Corresponding to θ=φ-2°, yellow warning point P 黄 Corresponding to θ=φ-4°, green warning point P 绿 The corresponding θ = φ - 6°; the location of each warning point is determined by L = H / tanθ, the intersection of the water surface and the slope is defined as point P, and the position where the vertical extension of point P intersects with the transparent rod is defined as P0, and L is the distance between P0 and the warning point; each warning point is determined by extending the line from the intersection of the water surface and the slope P as the starting point and the corresponding angle to intersect the extension line of the rod.

9. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 8, characterized in that: The monitoring frequency in S6 is adjusted according to the warning level. Specifically, for the orange warning segment, the real-time erosion rate is compared with the historical daily average rate. If the real-time rate is greater than 1.5 times the historical rate, it is upgraded to a red warning. The red warning segment needs to be monitored once every 3 hours.

10. The method for real-time monitoring and early warning of sandy riverbank collapse according to claim 1, characterized in that: The engineering measures taken in S6 include scattering gabion sandbags.

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