Dredged soil dumping disposal evaluation method based on indoor test

Abstract

The invention relates to the technical field of dredging engineering tests, and provides a dredged soil dumping disposal evaluation method based on an indoor test, which comprises the following steps: constructing an indoor simulation test system comprising a test water tank, a dredged soil dumping device and a monitoring system, and monitoring the diffusion concentration of suspended sediment in the dumping test process in real time through the monitoring system; after the dredged soil is poured, dredged soil stacking height images at different positions are shot; performing visual angle correction and image splicing on the obtained dredged soil stacking height image, and analyzing the deposited sediment stacking height and the remaining amount of dredged soil dumping disposal and the diffusion concentration of suspended sediment in a surrounding water area under a specified construction working condition based on the obtained suspended sediment diffusion concentration and sediment stacking height distribution; by combining the ecological function and the use function of the construction water area, the potential influence of the deposited sediment remaining amount and the suspended sediment diffusion on the construction surrounding water area is analyzed. Scientific assessment is provided for the influence of dredged soil dumping disposal on the terrain change and water environment of the dumping area.

Description

Technical Field

[0001] The invention relates to the technical field of dredging engineering tests, and in particular to a dredged soil dumping disposal evaluation method based on indoor tests. Background Art

[0002] During dredging operations, the primary methods for disposing of dredged soil excavated by dredging vessels are landfill and dumping at a dumping site. During the dumping process, especially when dealing with fine-grained dredged soil, not all of the dredged soil settles at the dumping site. Tidal currents and waves often cause some of the dredged soil to become suspended and disperse into the surrounding waters, causing water turbidity and reducing sunlight, impacting the ecological environment surrounding the dumping site. Furthermore, the sedimentation characteristics of dredged soil after dumping are crucial for analyzing the utilization rate of the dumping site and its topographical changes.

[0003] Therefore, it is of great practical significance to conduct research on dredged soil dumping, analyze the sediment deposition and diffusion characteristics of dredged soil dumping under the influence of hydrodynamic environment such as water flow and waves, and evaluate the impact of dredged soil dumping on the topography changes of the dumping area and the ecological environment of the surrounding waters.

[0004] Existing research on dredged soil dumping primarily relies on field testing and numerical simulation. Due to the complexity of sediment movement mechanisms, numerical simulations offer limited accuracy in studying the deposition and diffusion characteristics of dredged soil dumping. While field testing approaches are closest to actual results, they are extremely expensive, fail to fully understand the sediment deposition and diffusion characteristics of dredged soil dumping under different hydrodynamic conditions, and lack practicality.

[0005] Therefore, there is an urgent need to use an experimental method to conduct research on dredged soil dumping and accurately evaluate and analyze the impact of dredged soil dumping on the surrounding water environment under different working conditions. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a dredged soil dumping disposal evaluation method based on indoor tests, the evaluation method comprising:

[0007] (1) Construct an indoor simulation test system including a test flume, a dredged soil dumping device, and a monitoring system;

[0008] (2) During the test, the suspended sediment diffusion concentration during the dumping test was monitored in real time by a monitoring system;

[0009] (3) After the dredged soil is dumped, images of the dredged soil accumulation height at different locations are taken;

[0010] (4) Performing perspective correction and image stitching on the acquired dredged soil accumulation height image to obtain the sediment accumulation height distribution after the dredged soil is dumped;

[0011] (5) Based on the obtained suspended sediment diffusion concentration and sediment accumulation height distribution, analyze the sediment accumulation height, retention volume, and the diffusion concentration of suspended sediment in the surrounding waters after dredged soil dumping under specified construction conditions; the specified construction conditions include specified water depth, water flow velocity, wave height, dredged soil dumping volume, and dumping rate;

[0012] (6) In combination with the ecological functions and use functions of the waters surrounding the construction site, analyze the potential impact of the amount of sediment retained and the diffusion of suspended sediment after the dredged soil dumping on the waters surrounding the construction site; the ecological functions include fish habitats and aquatic plant growth areas; the use functions include waterways and water intakes.

[0013] Furthermore, the indoor simulation test system in step (1) includes:

[0014] A test water tank, wherein the test water tank is provided with a flow and wave generating control system and a driving device. The flow and wave generating control system is integrated into the interior of the test water tank, and generates water flow with controllable flow rate and direction and waves of different waveforms through the driving device;

[0015] The dredged soil dumping device includes a storage bin, an electric valve, a mud outlet, and a control cabinet. The storage bin is used to place test soil samples. The electric valve is located between the storage bin and the mud outlet, and the mud outlet faces the interior of the test water tank. The control cabinet is installed next to the storage bin and is electrically connected to the electric valve via a control circuit. The electric valve controls the opening size of the mud outlet through the control cabinet to achieve precise adjustment of the dredged soil dumping rate.

[0016] The monitoring system includes a current meter, a wave height meter, a turbidity meter and a topographic surveying instrument. The current meter and the wave height meter are respectively installed in the test water flume for obtaining water flow parameters and wave height data during the dumping test. The turbidity meters are arranged in a multi-point array at different horizontal positions and vertical depths in the test water flume for real-time monitoring of the spatiotemporal variation of suspended sediment diffusion during the dredged soil dumping process. The topographic surveying instrument includes a measuring trolley and a depth camera. The measuring trolley is located above the test water flume and moves back and forth along the length of the water flume. The depth camera is fixed on the measuring trolley. By controlling the movement of the measuring trolley, the depth camera obtains images of the dredged soil accumulation height at different positions along the test water flume.

[0017] Furthermore, in step (1), the test scale is determined according to the on-site water environment and the test tank conditions, wherein the test tank conditions include the geometric dimensions and wave-making and flow-making capabilities of the test tank, and the test scale is determined according to the gravity similarity criterion of equal Froude number. Determine that the test scale includes the plane geometric scale λ L , vertical geometric scale λH , flow velocity u scale λ u 、Dumping volume V scale λ V , time t scale λ t and sediment settling velocity ratio λ w , and the relationship is as follows:

[0018] λ H =λ L / α;

[0019] Where g is the acceleration of gravity, α is the model rate of change, and h is the water depth of the on-site waters.

[0020] Furthermore, the specific steps of performing perspective correction on the dredged soil accumulation height images at different positions in step (4) are as follows:

[0021] The camera internal parameter matrix K is obtained in advance through camera calibration; during the shooting process, the rotation matrix R of the camera tilt angle when shooting the image is recorded, and the orthophoto rotation matrix R is set rect ;

[0022] Perform orthographic projection transformation on each pixel coordinate (u, v) in the original image taken by each depth camera at an angle to obtain the image coordinates (u′, v′) after orthographic projection transformation, thereby eliminating the geometric distortion caused by non-vertical shooting and generating the corrected image. Orthographic projection transformation is achieved by (Equation 1):

[0023]

[0024] Furthermore, the specific steps for stitching the dredged soil accumulation height images at different locations are as follows:

[0025] Use the feature extraction algorithm to extract features from any two rectified images, detect key points in the images, and generate feature descriptors for each key point;

[0026] The distance between the feature descriptors of two images is calculated using Euclidean distance or Hamming distance, and point pairs with a distance less than a set threshold are selected as potential matching points.

[0027] Normalize the coordinates of the potential matching points that have been screened out so that their coordinate values ​​are distributed within the preset range.

[0028] Select 4 pairs of matching points from the potential matching points, and construct a linear equation matrix by selecting 4 pairs of matching points. The linear equation matrix is:

[0029]

[0030] The constructed linear equations are solved using the singular value decomposition (SVD) method to obtain the homography matrix. Based on the obtained homography matrix, one of the rectified images is transformed and mapped to the coordinate system of the other image to complete the stitching of the two images.

[0031] All corrected images are stitched together in sequence to finally obtain a complete image of the sediment accumulation height distribution after the dredged soil is dumped;

[0032] Among them, (x′ i , y′ i ) and (x i ,y i ) are the pairs of points with the same name on the corrected image and the original image respectively, H is the homography matrix, and two equations can be constructed for each pair of matching points (because after the matrix multiplication is expanded, the first two rows correspond to the calculation of the x and y coordinates respectively). 8 equations can be constructed for 4 pairs of matching points, thus forming a set of linear equations about the elements of the homography matrix.

[0033] Furthermore, the steps for calculating the amount of sediment retained from the dredged soil dumping in step (5) are as follows:

[0034] (51) The maximum length L and width B of the sediment distribution in the test flume were measured, and the equivalent rectangular area of ​​the base was determined as S = L × B;

[0035] (52) Discretize the base plane into m×n equal-area units, with the area of ​​each unit being ΔS=S / (m×n); perform plane interpolation on the dredged soil sediment accumulation height image to extract the accumulation height matrix D=D i，j , where D i，j represents the sediment accumulation height value at the grid point (i, j); the discrete height data are integrated through numerical integration, and the calculation formula for the dredged soil dumping test retention Q is as follows:

[0036]

[0037] (53) Based on the sediment retention results of the dredged soil dumping test, the sediment retention of the dredged soil dumping disposal construction under the specified working conditions is obtained by scale conversion: P = Q × λ V .

[0038] Furthermore, in step (5), the calculation formula for the sediment diffusion concentration C at the designated location for dredged soil dumping is:

[0039] C=C i,j (1-Δx)(1-Δh)+C i+1,j Δx(1-Δh)+C i,j+1 (1-Δx)Δy+C i+1,j+1 ΔxΔy;

[0040] in, Indicates the relative offset of a specified position point between two adjacent concentration monitoring points along the flume direction;

[0041] Indicates the relative offset of a specified position point between two adjacent concentration monitoring points along the vertical direction of the water depth;

[0042] C i，j Indicates the monitoring point (x i ,y i ) is the sediment diffusion concentration at .

[0043] The present invention has the following beneficial effects:

[0044] (1) The turbidity meter of the present invention adopts a multi-point array arrangement (different positions and depths) to capture the spatiotemporal distribution of suspended sediment diffusion in real time; the topographic survey instrument is a combination of a measuring trolley and a depth camera, which obtains the full-sink sediment topography through perspective correction and image stitching, solving the one-sidedness problem of traditional single-point measurement or manual mapping, and realizing three-dimensional monitoring of the entire process of "suspension diffusion-sedimentation accumulation" after dredged soil dumping, providing high-density and high-precision basic data for the evaluation model, avoiding the omission of key parameters;

[0045] (2) The present invention constructs a test water tank including a flow and wave control system, which can simulate different hydrodynamic conditions (such as flow rate and waves), combined with the gravity similarity criterion of equal Froude number. Determine the test scale (plane / vertical geometric scale, flow velocity scale, etc.) to ensure the dynamic similarity between the indoor model test and the field environment. Through strict similarity criteria, the test results can be directly applied to actual projects through scale conversion, avoiding the subjectivity of traditional empirical methods and improving the universality and reliability of the evaluation model.

[0046] (3) The present invention eliminates geometric distortion by performing orthographic projection transformation on the images taken by the depth camera at an angle; completes multi-image stitching through homography transformation to construct a complete sedimentary topography distribution, overcomes the measurement error caused by camera viewing angle deviation, ensures the geometric accuracy of sediment accumulation height data, provides a reliable spatial coordinate reference for subsequent retention volume calculation (such as numerical integration), and avoids volume estimation deviation caused by image distortion;

[0047] (4) The present invention discretizes the base plane into m×n grid cells, extracts the stacking height matrix through plane interpolation, calculates the retention volume using numerical integration, and obtains the actual engineering retention volume through scale conversion; the continuous terrain is converted into discrete data, and the retention volume is quantitatively calculated by combining mathematical integration methods. Compared with traditional empirical formulas or simplified models, the accuracy of sedimentation assessment is significantly improved, and it is particularly suitable for refined analysis under complex terrain conditions;

[0048] (5) The present invention takes into account the suspended sediment diffusion concentration (real-time monitoring by a turbidity meter) and the amount of sediment retained (calculated by topographic measurement and integration), and can analyze the dual impact of dumping disposal on the construction water area (water pollution and sediment deposition) under specified hydrodynamic conditions. This breaks through the limitations of single-indicator evaluation and provides a two-dimensional evaluation of "pollution diffusion range-sediment retention efficiency" for engineering design, making it easier for decision makers to balance construction efficiency and environmental protection needs (such as optimizing dumping locations and controlling dumping volume);

[0049] (6) The present invention establishes a mapping relationship from "indoor test data" to "actual engineering parameters". By adjusting the test scale and inputting on-site environmental parameters (such as water depth h and flow velocity u), the dumping disposal effect under different working conditions (such as ports, rivers, and marine projects) can be quickly evaluated, avoiding repeated experiments and reducing evaluation costs.

[0050] (7) The present invention is based on indoor tests on dredged soil dumping, which can accurately reflect the sediment deposition and diffusion laws of dredged soil dumping under the action of waves and tidal currents. At the same time, the method of the present invention has a clear process and is easy to operate. It can efficiently carry out dredged soil dumping tests and provide a scientific assessment of the impact of dredged soil dumping on the topography changes and water environment of the dumping area. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a flow chart of the evaluation method in the present invention.

[0052] Figure 2 It is a schematic diagram of the arrangement of the dredged soil dumping test in the present invention.

[0053] Figure 3 This is a schematic diagram of the turbidity meter arranged in a multi-point array.

[0054] Figure 4 This is a schematic diagram of a topographic survey instrument.

[0055] Figure 5 Schematic diagram of the image before correction in the embodiment.

[0056] Figure 6 2 is a schematic diagram of an image before and after correction in the embodiment. DETAILED DESCRIPTION

[0057] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, but this embodiment is not intended to limit the present invention. All similar structures and similar variations of the present invention should be included in the scope of protection of the present invention. The semicolons in the present invention represent the relationship of and, and the English letters in the present invention are case-sensitive.

[0058] like Figure 1 As shown, the present invention provides a dredged soil dumping disposal evaluation method based on indoor tests, the evaluation method comprising:

[0059] S1, construct an indoor simulation test system including a test water tank 1, a dredged soil dumping device 2 and a monitoring system 3, use a flow and wave control system to simulate the target hydrodynamic environment, and dump the test soil sample into the test water tank through the dredged soil dumping device;

[0060] like Figure 2 As shown, the test water tank 1 is equipped with a flow and wave control system 11 and a drive device. The flow and wave control system 11 is integrated into the test water tank 1 and generates water flow with controllable flow rate and direction and waves of different waveforms through the drive device. The test scale is determined based on the on-site water environment and the conditions of the test water tank, where the test water tank conditions include the test water tank's geometric dimensions and wave and flow generation capabilities. The test scale is based on the gravity similarity criterion of equal Froude number. Determine that the test scale includes the plane geometric scale λ L , vertical geometric scale λ H , flow velocity u scale λ u 、Dumping volume V scale λ V , time t scale λ t and sediment settling velocity ratio λ w , and the relationship is as follows:

[0061] λ H =λ L / α;

[0062] Where g is the acceleration of gravity, α is the model rate of change, and h is the water depth of the on-site waters.

[0063] Test water tank 1 is supported by a steel structure with an open top and transparent tempered glass on the sides, ensuring both light transmittance and strength. A flow and wave control system is included within the test water tank, which utilizes computerized automation to adjust flow and wave parameters in real time.

[0064] The dredged soil dumping device 2 includes a storage bin, an electric valve, a mud outlet, and a control cabinet. The storage bin is used to place test soil samples. The electric valve is located between the storage bin and the mud outlet, and the mud outlet faces the interior of the test water tank. The control cabinet is installed next to the storage bin and is electrically connected to the electric valve via a control circuit. The electric valve controls the opening size of the mud outlet through the control cabinet to achieve precise adjustment of the dredged soil dumping rate.

[0065] The monitoring system 3 includes a current meter 31, a wave height meter 32, a turbidity meter 33 and a topographic surveying instrument 34. The current meter 31 and the wave height meter 32 are respectively installed in the test water tank 1 for obtaining water flow parameters and wave height data during the dumping test; the turbidity meter 33 is arranged in a multi-point array at different horizontal positions and vertical depths in the test water tank 1 for real-time monitoring of the spatiotemporal variation of suspended sediment diffusion during the dredged soil dumping process; the topographic surveying instrument 34 includes a measuring trolley 341 and a depth camera 342. The measuring trolley 341 is located above the test water tank 1 and moves back and forth along the length of the water tank. The depth camera 342 is fixed on the measuring trolley 341. By controlling the movement of the measuring trolley 341, the depth camera 342 obtains images of the dredged soil accumulation height at different positions of the test water tank 1 and the highest.

[0066] S2, during the test, the suspended sediment diffusion concentration during the dumping test is monitored in real time by a monitoring system, specifically by a turbidity meter;

[0067] S3, after the dredged soil is dumped, take images of the dredged soil accumulation height at different locations. Specifically, the measurement trolley is controlled to move along the length of the test flume, and the depth camera is used to take images of the dredged soil accumulation height at different locations, ensuring that the images cover the entire area of ​​the test flume.

[0068] S4, performing perspective correction and image stitching on the acquired dredged soil accumulation height image to obtain the sediment accumulation height distribution after the dredged soil is dumped; specifically, performing orthographic projection transformation on the image taken by the depth camera at an angle to eliminate geometric distortion, performing point matching on the corrected image, and performing image stitching using a homography matrix to obtain the sediment accumulation height distribution after the dredged soil is dumped;

[0069] The specific steps for perspective correction of dredged soil accumulation height images at different locations are as follows:

[0070] The camera intrinsic parameter matrix K is obtained in advance through camera calibration; during the shooting process, the rotation matrix R of the camera tilt angle when shooting the image is recorded, and the orthophoto rotation matrix Rrect is set;

[0071] Perform orthographic projection transformation on each pixel coordinate (u, v) in the original image taken by each depth camera at an angle to obtain the image coordinates (u′, v′) after orthographic projection transformation, thereby eliminating the geometric distortion caused by non-vertical shooting and generating the corrected image. Orthographic projection transformation is achieved by (Equation 1):

[0072]

[0073] The specific steps for image stitching of dredged soil accumulation height images at different locations are as follows:

[0074] Use the feature extraction algorithm to extract features from any two rectified images, detect key points in the images, and generate feature descriptors for each key point;

[0075] The distance between the feature descriptors of two images is calculated using Euclidean distance or Hamming distance, and point pairs with a distance less than a set threshold are selected as potential matching points.

[0076] Normalize the coordinates of the potential matching points that have been screened out so that their coordinate values ​​are distributed within the preset range.

[0077] Select 4 pairs of matching points from the potential matching points, and construct a linear equation matrix by selecting 4 pairs of matching points:

[0078]

[0079] The constructed linear equations are solved using the singular value decomposition (SVD) method to obtain the homography matrix. Based on the obtained homography matrix, one of the rectified images is transformed and mapped to the coordinate system of the other image to complete the stitching of the two images.

[0080] All corrected images are stitched together in sequence to finally obtain a complete image of the sediment accumulation height distribution after the dredged soil is dumped;

[0081] Among them, (x′ i , y′ i ) and (x i ,y i ) are the pairs of points with the same name on the corrected image and the original image respectively, H is the homography matrix, and two equations can be constructed for each pair of matching points (because after the matrix multiplication is expanded, the first two rows correspond to the calculation of the x and y coordinates respectively). 8 equations can be constructed for 4 pairs of matching points, thus forming a set of linear equations about the elements of the homography matrix.

[0082] S5, based on the obtained suspended sediment diffusion concentration and sediment accumulation height distribution, analyzing the sediment accumulation height and retention amount of the dredged soil dumping disposal and the diffusion concentration of the suspended sediment in the surrounding waters under specified construction conditions; the specified construction conditions include specified water depth, water flow velocity, wave height, dredged soil dumping amount, and dumping rate;

[0083] The steps for calculating the amount of sediment retained for dredged soil dumping are as follows:

[0084] S51, measure the maximum length L and width B of the sediment distribution in the test flume, and determine the equivalent rectangular area of ​​the base S = L × B;

[0085] S52, discretize the base plane into m×n equal-area units, each unit area is ΔS=S / (m×n); perform plane interpolation on the dredged soil sediment accumulation height image to extract the accumulation height matrix D=D i，j , where D i，j represents the sediment accumulation height value at the grid point (i, j); the discrete height data are integrated through numerical integration, and the calculation formula for the dredged soil dumping test retention Q is as follows:

[0086]

[0087] S53, based on the sediment retention results of the dredged soil dumping test, the sediment retention of the dredged soil dumping disposal construction under the specified working conditions is obtained by scale conversion P = Q × λ V .

[0088] The calculation formula for the sediment diffusion concentration C at the designated location of dredged soil dumping is:

[0089] C=C i,j (1-Δx)(1-Δh)+C i+1,j Δx(1-Δh)+C i,j+1 (1-Δx)Δy+C i+1,j+1 ΔxΔy;

[0090] in, Indicates the relative offset of a specified position point between two adjacent concentration monitoring points along the flume direction;

[0091] Indicates the relative offset of a specified position point between two adjacent concentration monitoring points along the vertical direction of the water depth;

[0092] C i，j Indicates the monitoring point (x i ,y i ) is the sediment diffusion concentration at .

[0093] S6. Analyze the potential impact of the amount of sediment retained and the diffusion of suspended sediment after dredged soil dumping on the surrounding waters of the construction site, taking into account the ecological functions and use functions of the construction waters. The ecological functions include fish habitats and aquatic plant growth areas, while the use functions include waterways and water intakes.

[0094] Example

[0095] This plan is used to evaluate the disposal of dredged soil in a certain dumping area.

[0096] S1, constructing an indoor simulation test system including a test water flume 1 with a flow and wave control system, a dredged soil dumping device 2, and a monitoring system 3. The flow and wave control system is used to simulate the hydrodynamic environment of the target area, and the test soil sample is dumped into the test water flume through the dredged soil dumping device;

[0097] like Figure 2 As shown; the indoor simulation test system includes:

[0098] Test water tank 1 utilizes a steel structure with an open top and transparent tempered glass sides, ensuring both light transmission and strength. It houses a flow and wave control system and a drive mechanism, which generate controlled flow rates and directions, as well as waves of varying waveforms. This computer-controlled flow and wave control system can generate flow rates of 0-1.0 m / s and wave heights of 0-0.6 m.

[0099] The corresponding on-site dumping construction water depth for this test is about 9.5m, the water flow velocity is about 0.8m / s, the wave height is about 0.5m, the surrounding water area for the dumping disposal impact assessment is about 1500m away from the dumping location, and the dumping volume is about 25000m 3 , the dumping duration is about 150s.

[0100] According to the on-site environmental parameters and water tank conditions, the plane geometric scale of this test is λ L =100, model variation α = 10, then λ H =10; In the test setting, the water depth is set to 0.95m, the water flow velocity is set to 0.08m / s, the wave height is set to 0.05m, and the amount of earth dumped in the test is 0.25m 3 , the dumping duration is controlled within 15s.

[0101] The dredged soil dumping device 2 includes a storage bin, an electric valve, a mud outlet, and a control cabinet. The storage bin is used to place test soil samples. The electric valve is located between the storage bin and the mud outlet, and the mud outlet faces the bottom of the test water tank. The control cabinet is installed next to the storage bin and is electrically connected to the electric valve through a control circuit. The electric valve controls the opening size of the mud outlet through the control cabinet to achieve precise adjustment of the dredged soil dumping rate.

[0102] The monitoring system 3 includes a flow meter 31, a wave height meter 32, a turbidity meter 33 and a topography meter 34, which are used to obtain the water flow velocity, wave height, suspended sediment diffusion concentration and sediment deposition height during the dumping test.

[0103] Turbidimeters are arranged in a multi-point array to monitor the temporal and spatial variations of suspended sediment diffusion during dredged soil dumping in real time; Figure 3 As shown, the turbidity meters 33 are arranged in a multi-point array downstream of the dredged soil dumping device 2, and are arranged at equal intervals of 5 meters along the center line of the mud outlet of the dredged soil dumping device 2. They are vertically arranged in water bodies with water depths of 0.1m, 0.5m and 0.9m, and the above water depths correspond to the surface layer, middle layer and bottom layer of the test water body respectively.

[0104] like Figure 4 As shown, the topographic surveying instrument 34 includes a measuring trolley 341 and a depth camera 342. The measuring trolley 341 is located above the water flume and can move back and forth along the length of the water flume. The depth camera 342 is fixed on the measuring trolley. By controlling the movement of the measuring trolley 341, the depth camera 342 obtains images of the dredged soil accumulation height at different positions of the test water flume.

[0105] S2, during the test, the suspended sediment diffusion concentration during the dumping test was monitored in real time by a turbidity meter; the sediment monitoring concentrations at different locations are shown in Table 1.

[0106] Table 1

[0107] Measuring point location surface layer Middle level bottom layer 5m 680mg / L 1366mg / L 1850mg / L 10m 569mg / L 1211mg / L 1632mg / L 15m 463mg / L 1002mg / L 1505mg / L 20m 401mg / L 933mg / L 1388mg / L

[0108] S3: After the dredged soil is dumped, use a depth camera to capture images of the dredged soil accumulation height at different locations, ensuring that the images cover the entire area of ​​the test flume. After the dredged soil is dumped in this test, the maximum accumulation height of the sediment obtained by the depth camera is 0.23m. According to the scale conversion, the corresponding maximum accumulation height during the dumping and disposal construction is 2.3m;

[0109] S4, performing perspective correction and image stitching on the acquired dredged soil accumulation height image to obtain the sediment accumulation height distribution after the dredged soil is dumped; specifically, performing orthographic projection transformation on the image taken by the depth camera at an angle to eliminate geometric distortion, performing point matching on the corrected image, and performing image stitching using a homography matrix to obtain the sediment accumulation height distribution after the dredged soil is dumped;

[0110] like Figure 5-Figure 6 As shown in the figure, there are two cameras, left and right, where Ol and Or are the optical centers of the left and right cameras respectively, and the line connecting them forms the baseline b. P is a point in space, Pl and Pr are the image points of P on the imaging planes of the left and right cameras respectively, gl and gr represent the specific positions of the image points on their respective planes, and the lines where Pl and Pr are located are the left and right epipolar lines respectively;

[0111] Perspective correction: Obtain the camera internal parameter matrix K in advance through camera calibration; during the shooting process, record the rotation matrix R of the camera tilt perspective when shooting the image, and set the orthophoto rotation matrix R rect ;

[0112] Perform orthographic projection transformation on each pixel coordinate (u, v) in the original image taken by each depth camera at an angle to obtain the image coordinates (u′, v′) after orthographic projection transformation, thereby eliminating the geometric distortion caused by non-vertical shooting and generating the corrected image. Orthographic projection transformation is achieved by (Equation 1):

[0113]

[0114] Image stitching: Use feature extraction algorithms to extract features from any two rectified images, detect key points in the images, and generate feature descriptors for each key point;

[0115] The distance between the feature descriptors of two images is calculated using Euclidean distance or Hamming distance, and point pairs with a distance less than a set threshold are selected as potential matching points.

[0116] Normalize the coordinates of the potential matching points that have been screened out so that their coordinate values ​​are distributed within the preset range.

[0117] Select 4 pairs of matching points from the potential matching points, and construct a linear equation matrix by selecting 4 pairs of matching points:

[0118]

[0119] The constructed linear equations are solved using the singular value decomposition (SVD) method to obtain the homography matrix. Based on the obtained homography matrix, one of the rectified images is transformed and mapped to the coordinate system of the other image to complete the stitching of the two images.

[0120] All corrected images are stitched together in sequence to finally obtain a complete image of the sediment accumulation height distribution after the dredged soil is dumped;

[0121] Among them, (x′ i , y′ i ) and (x i ,y i ) are the pairs of points with the same name on the corrected image and the original image respectively, and H is the homography matrix.

[0122] S5, based on the obtained suspended sediment diffusion concentration and sediment accumulation height distribution, analyzing the sediment accumulation height, retention volume, and the diffusion concentration of suspended sediment in the surrounding waters of the dredged soil dumping disposal under specified construction conditions; the specified construction conditions include specified water depth, water flow velocity, wave height, dredged soil dumping volume, and dumping rate;

[0123] The steps for calculating sediment retention are as follows:

[0124] S51, measured the maximum length of sediment distribution in the test flume was 7.5m and the width was 1.8m, and the equivalent rectangular area of ​​the base was determined to be S = 13.5㎡;

[0125] S52, discretize the base plane into 200×50 equal-area units, with the area of ​​each unit being ΔS=S / (m×n)=0.00135㎡; perform plane interpolation on the sediment accumulation height image to extract the accumulation height matrix D=D i，j , where D i，j represents the sediment accumulation height value at the grid point (i, j); the discrete height data are integrated through numerical integration, and the calculation formula for the dredged soil dumping test retention Q is as follows:

[0126]

[0127] Based on the above formula, the retained volume Q of the dredged soil dumping test is 0.18m 3 .

[0128] S53, based on the sediment retention results of the dredged soil dumping test, the sediment retention of the dredged soil dumping disposal construction under the specified working conditions is obtained by scale conversion P = Q × λ V The actual amount of sediment retained during the dumping and disposal construction is 18,000m 3 .

[0129] The calculation formula for the sediment diffusion concentration C at the designated location of dredged soil dumping is:

[0130] C=C i,j (1-Δx)(1-Δh)+C i+1,j Δx(1-Δh)+Ci,j+1 (1-Δx)Δy+C i+1,j+1 ΔxΔy;

[0131] Along the water flow direction, the sediment content in the water body at 1000m, 1500m and 2000m away from the dumping location increased by 569mg / L, 463mg / L and 401mg / L respectively.

[0132] S6. Based on the suspended sediment diffusion concentration and sediment retention of the above dumping disposal test, it can be seen that the dumping of dredged soil will cause the sediment content of the water body at 1000m, 1500m and 2000m away from the dumping location along the water flow direction to increase by 569mg / L, 463mg / L and 401mg / L respectively; 3 The amount of sediment retained after the dredged soil was dumped was approximately 18,000 m 3 The maximum accumulation height is about 2.3m, that is, after the dumping of the dredged soil, the local water depth in the dumping area is reduced from the original 9.5m to 7.2m. Based on the above information, the potential impact on the waters around the construction site is analyzed.

[0133] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

Claims

1. A dredged soil dumping disposal assessment method based on indoor tests, characterized in that: The evaluation method includes: (1) Construct an indoor simulation test system including a test flume, a dredged soil dumping device, and a monitoring system; (2) During the test, the suspended sediment diffusion concentration during the dumping test was monitored in real time by a monitoring system; (3) After the dredged soil is dumped, images of the dredged soil accumulation height at different locations are taken; (4) Performing perspective correction and image stitching on the acquired dredged soil accumulation height image to obtain the sediment accumulation height distribution after the dredged soil is dumped; (5) Based on the obtained suspended sediment diffusion concentration and sediment accumulation height distribution, analyze the sediment accumulation height, retention volume, and the diffusion concentration of suspended sediment in the surrounding waters after dredged soil dumping under specified construction conditions; the specified construction conditions include specified water depth, water flow velocity, wave height, dredged soil dumping volume, and dumping rate; (6) In combination with the ecological functions and usage functions of the waters surrounding the construction site, analyze the potential impact of the amount of sediment retained and the diffusion of suspended sediment after the dredged soil is dumped on the waters surrounding the construction site.

2. The dredged soil dumping and disposal evaluation method based on indoor experiments according to claim 1 is characterized in that: The indoor simulation test system in step (1) includes: A test water tank, wherein the test water tank is provided with a flow and wave generating control system and a driving device. The flow and wave generating control system is integrated into the interior of the test water tank, and generates water flow with controllable flow rate and direction and waves of different waveforms through the driving device; The dredged soil dumping device includes a storage bin, an electric valve, a mud outlet, and a control cabinet. The storage bin is used to place test soil samples. The electric valve is located between the storage bin and the mud outlet, and the mud outlet faces the bottom of the test water tank. The control cabinet is installed next to the storage bin and is electrically connected to the electric valve via a control circuit. The electric valve controls the opening size of the mud outlet through the control cabinet to achieve precise adjustment of the dredged soil dumping rate. The monitoring system includes a current meter, a wave height meter, a turbidity meter and a topographic surveying instrument. The current meter and the wave height meter are respectively installed in the test water flume for obtaining water flow parameters and wave height data during the dumping test. The turbidity meters are arranged in a multi-point array at different horizontal positions and vertical depths in the test water flume for real-time monitoring of the spatiotemporal variation of suspended sediment diffusion during the dredged soil dumping process. The topographic surveying instrument includes a measuring trolley and a depth camera. The measuring trolley is located above the test water flume and moves back and forth along the length of the water flume. The depth camera is fixed on the measuring trolley. By controlling the movement of the measuring trolley, the depth camera obtains images of the dredged soil accumulation height at different positions along the test water flume.

3. The dredged soil dumping and disposal evaluation method based on indoor tests according to claim 2 is characterized in that: The test scale is determined according to the on-site water environment and the test tank conditions. The test scale is determined according to the gravity similarity criterion of equal Froude numbers. The test scale includes the plane geometric scale λ L , vertical geometric scale λ H , flow velocity u scale λ u 、Dumping volume V scale λ V , time t scale λ t and sediment settling velocity ratio λ w , and the relationship is as follows: l H =λ L / a; Where α is the model variation rate.

4. The dredged soil dumping and disposal evaluation method based on indoor tests according to claim 2 is characterized in that: The specific steps for performing perspective correction on the dredged soil accumulation height images at different positions in step (4) are as follows: The camera internal parameter matrix K is obtained in advance through camera calibration; during the shooting process, the rotation matrix R of the camera tilt angle when shooting the image is recorded, and the orthophoto rotation matrix R is set rect ; Perform orthographic projection transformation on each pixel coordinate (u, v) in the original image taken by each depth camera at an angle to obtain the image coordinates (u′, v′) after orthographic projection transformation, thereby eliminating the geometric distortion caused by non-vertical shooting and generating the corrected image. Orthographic projection transformation is achieved by (Equation 1):

5. The dredged soil dumping and disposal evaluation method based on indoor tests according to claim 4 is characterized in that: The specific steps for image stitching of dredged soil accumulation height images at different locations are as follows: Use the feature extraction algorithm to extract features from any two rectified images, detect key points in the images, and generate feature descriptors for each key point; The distance between the feature descriptors of two images is calculated using Euclidean distance or Hamming distance, and point pairs with a distance less than a set threshold are selected as potential matching points. Normalize the coordinates of the potential matching points that have been screened out so that their coordinate values ​​are distributed within the preset range. Select 4 pairs of matching points from the potential matching points, and construct a linear equation matrix by selecting 4 pairs of matching points. The linear equation matrix is: The constructed linear equations are solved using the singular value decomposition method to obtain the homography matrix. Based on the obtained homography matrix, one of the rectified images is transformed and mapped to the coordinate system of the other image to complete the stitching of the two images. All corrected images are stitched together in sequence to finally obtain a complete image of the sediment accumulation height distribution after the dredged soil is dumped; Among them, (x′ i , y′ i ) and (x i ,y i ) are the pairs of points with the same name on the corrected image and the original image respectively, and H is the homography matrix.

6. The dredged soil dumping disposal assessment method based on indoor testing according to claim 1, characterized in that: The steps for calculating the amount of sediment retained for dredged soil dumping in step (5) are as follows: (51) The maximum length L and width B of the sediment distribution in the test flume were measured, and the equivalent rectangular area of ​​the base was determined as S = L × B; (52) Discretize the base plane into m×n equal-area units, with the area of ​​each unit being ΔS=S / (m×n); perform plane interpolation on the dredged soil accumulation height image to extract the accumulation height matrix D=D i，j , where D i，j represents the sediment accumulation height value at the grid point (i, j); the discrete height data are integrated through numerical integration, and the calculation formula for the dredged soil dumping test retention Q is as follows: (53) Based on the sediment retention results of the dredged soil dumping test, the sediment retention of the dredged soil dumping disposal construction under the specified working conditions is obtained by scale conversion: P = Q × λ V .

7. The dredged soil dumping disposal assessment method based on indoor testing according to claim 6, characterized in that: In step (5), the calculation formula for the sediment diffusion concentration C at the designated location for dredged soil dumping is: C=C i,j (1-Δx)(1-Δy)+C i+1,j Δx(1-Δy)+C i,j+1 (1-Δx)Δy+C i+1,j+1 ΔxΔy; in, Indicates the relative offset of a specified position point between two adjacent concentration monitoring points along the flume direction; Indicates the relative offset of a specified position point between two adjacent concentration monitoring points along the vertical direction of the water depth; C i，j Indicates the monitoring point (x i ,y i ) is the sediment diffusion concentration at .

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