Pit throwing site selection and mud throwing intensity planning method and system in sea reclamation project

Abstract

The invention discloses a pit throwing site selection and mud throwing strength planning method and system in sea reclamation engineering. The method comprises the steps that firstly, a hydrodynamic mathematical model and suspended load sediment transportation are constructed through a two-dimensional shallow water equation and a convection diffusion equation; secondly, on the basis of the established mathematical model, a model capable of being applied to an actual project is formed through a parameterization means by combining the actual situation of the project, and finally the loss rate calculation under different pit throwing positions and mud throwing strengths is carried out through the general model. According to the scheme, multi-dimensional information such as construction time, mud blowing ship construction parameters, hydraulic reclamation construction data and soil texture detection reports is comprehensively considered, and an advanced numerical simulation technology and a flow field analysis method are introduced, so that the silt loss rate under different working conditions is accurately predicted; meanwhile, according to the scheme, direct planning of pit throwing site selection and mud throwing strength is concerned, prediction and control of the wastage rate are indirectly optimized by introducing numerical simulation and flow field analysis, and therefore systematicness and comprehensiveness of sea reclamation project planning are enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, and in particular to a method and system for planning the site selection of dumping pits and the intensity of dumping mud in land reclamation engineering. Background Art

[0002] In coastal areas, with the continuous acceleration of urbanization and the continuous growth of land resource demand, land reclamation has become an important means to expand urban space. In reclamation projects, land reclamation by blowing is a key link, which usually involves blowing mud from coastal tidal flats or seabed to designated areas through pipelines to create new land resources. However, in the process of blowing, the site selection of dumping pits and the planning of mud dumping intensity directly affect the loss rate of mud dumping. Therefore, the site selection of dumping pits and the mud dumping intensity have become key factors affecting the efficiency of blowing and cost control.

[0003] At present, there are the following problems in the methods of pit site selection and mud dumping intensity planning in reclamation projects:

[0004] First of all, in the field of pit site selection and mud dumping intensity planning in reclamation projects, it still relies heavily on experience and judgment, and preliminary planning is mainly based on past experience of similar projects and actual on-site conditions.

[0005] Although this empirical judgment method can guide the planning of dumping pit site selection and mud dumping intensity to a certain extent, it ignores the unique geographical location, topography, hydrological conditions, soil characteristics and other complex factors of each reclamation project, resulting in large uncertainty and errors in the planning results. Due to the lack of scientific basis and theoretical support, the planning scheme is often difficult to achieve the optimal one, which affects the efficiency of filling and cost control.

[0006] Secondly, the planning process lacks systematicity and fails to comprehensively consider multi-dimensional information.

[0007] Traditional empirical judgment methods often focus on only a few key factors, while ignoring the impact of multi-dimensional information such as construction time, mud-blowing ship construction parameters, filling construction data, and soil quality test reports on pit site selection and mud-blowing intensity planning. This single-dimensional planning method is difficult to fully reflect the actual situation of reclamation projects, resulting in a lack of comprehensiveness and systematicness in planning results. At the same time, due to the lack of comprehensive consideration of this information, planning schemes are often difficult to optimize and improve, limiting the quality and benefits of reclamation projects.

[0008] In addition, there is a lack of support from advanced numerical simulation and flow field analysis methods.

[0009] Traditional empirical judgment methods often fail to accurately predict the sediment loss rate under different working conditions, resulting in a lack of scientific basis for planning schemes. In addition, due to the lack of support from advanced numerical simulation and flow field analysis methods, it is difficult to quantitatively analyze and compare different planning schemes, making it difficult to select the optimal planning scheme. This limits the ability of reclamation projects in construction design and cost control, and affects the overall benefits of the project.

[0010] It can be seen that a method for planning the site selection and mud dumping intensity in land reclamation projects is needed to solve the above technical problems, which is a problem that needs to be solved in this field. Summary of the invention

[0011] In view of the above-mentioned technical problems existing in existing reclamation projects, the purpose of the present invention is to provide a method for pit site selection and mud dumping intensity planning in reclamation projects. Compared with the traditional empirical judgment method, the method of the present invention is more scientific, accurate and reliable, and can provide more powerful support for the construction design and cost control of reclamation projects. On this basis, a pit site selection and mud dumping intensity planning system for reclamation projects that can implement this method is also provided.

[0012] In order to achieve the above object, the present invention provides a method for site selection and mud dumping intensity planning in a reclamation project, and the method for site selection and mud dumping intensity planning in a reclamation project comprises the following steps:

[0013] Step 1: Establish a mathematical model for mud dumping

[0014] This step constructs a hydrodynamic mathematical model and suspended sediment transport through two-dimensional shallow water equations and convection-diffusion equations;

[0015] Step 2: General model building

[0016] This step is based on the mathematical model established in step 1, combined with the actual situation of the specific project, and forms a model that can be applied to the actual project through parameterization;

[0017] Step 3: Calculate the loss rate at different dumping locations and dumping intensities

[0018] This step uses the general model verified in the above step 2 to calculate the loss rate under different dumping pit locations and mud dumping intensities by inputting key parameters.

[0019] Furthermore, the actual engineering conditions include the setting of network resolution, constraints, sediment characteristics and source and sink items.

[0020] Furthermore, the network resolution is determined by selecting an appropriate grid type for segmentation based on the size and complexity of the study area.

[0021] Furthermore, constraints are used to determine the boundary conditions of the model based on topographic, hydrological and meteorological data of the study area.

[0022] Furthermore, the properties of the dredged fill sand are determined to determine the type and parameters of the dredged fill sand in the model according to the source and properties of the dredged soil in the actual project.

[0023] Furthermore, source and sink items are set to set the source and sink items in the model according to the actual filling requirements and construction conditions of the project.

[0024] Furthermore, after the general model is established, the model is verified by collecting measured data. If there is a large deviation between the simulation results and the measured data, the model needs to be further optimized and adjusted.

[0025] Further, in step 3, calculating the loss rate under different dumping pit locations and dumping intensities includes the following steps:

[0026] (1): According to the specific dumping pit location and dumping intensity, the dumping area and source strength parameters in the simulation, as well as the simulation time, sand pile volume, and key simulation parameters are reasonably set;

[0027] (3) To evaluate the maximum loss rate that may occur during mud dumping under specific adverse conditions and explore how this loss rate is affected by the location of the dumping pit and the intensity of mud dumping;

[0028] (4) Calculate the transport and accumulation form of sediment using the model established in step 1 and step 2, and further simulate and calculate the loss of mud dumping based on the simulation of the accumulation form;

[0029] The total amount of thrown sediment and the amount of accumulated sediment are calculated through simulation, and the difference is the amount of lost sediment; the direction of sediment loss can be known from the expansion direction of sediment concentration; the sediment loss rate can be obtained by combining the changes in cross-section sediment;

[0030] (5) Compare the simulation results with the actual situation and, based on the simulation results, put forward suggestions for optimizing the dumping pit location and mud dumping intensity.

[0031] Furthermore, the simulation results calculated in step 3 are compared with the actual situation, and suggestions for optimizing the dumping pit location and mud dumping intensity are put forward based on the simulation results.

[0032] In order to achieve the above-mentioned object, the present invention provides a system for site selection and mud dumping intensity planning in land reclamation engineering, and the system for site selection and mud dumping intensity planning in land reclamation engineering comprises:

[0033] A mud dumping mathematical model establishment module, wherein the mud dumping mathematical model establishment module constructs a mud dumping mathematical model by establishing a hydrodynamic mathematical model and a sediment transport model;

[0034] A general model building module, which interacts with the mud dumping mathematical model building module in data, and forms a model applicable to actual projects through parameterization based on the mathematical model established by the mud dumping mathematical model building module and in combination with the actual conditions of the specific project;

[0035] The loss rate calculation module interacts with the general model building module to calculate the loss rate under different dumping positions and mud dumping intensities through the general model verified in the general model building module.

[0036] The method and system for site selection and mud dumping intensity planning in reclamation projects provided by the present invention address the problem that site selection and mud dumping intensity planning in reclamation projects are highly dependent on experience judgment and lack scientificity and accuracy. The present invention proposes a comprehensive consideration of multi-dimensional information such as construction time, mud blowing ship construction parameters, filling construction data and soil quality test reports, and introduces advanced numerical simulation technology and flow field analysis methods to achieve accurate prediction and scientific planning of sediment loss rate under different working conditions, making the planning process more quantitative, scientific and reliable.

[0037] In view of the problem that traditional planning methods lack systematicity and fail to fully consider the impact of multi-dimensional information on the site selection of dumping pits and the planning of mud dumping intensity, the present invention not only focuses on the direct planning of dumping pit site selection and mud dumping intensity, but also indirectly optimizes the prediction and control of loss rate by introducing numerical simulation and flow field analysis, thereby enhancing the systematicness and comprehensiveness of reclamation project planning. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a flow chart of the method for planning the dumping pit site selection and dumping intensity in this reclamation project;

[0040] Figure 2 This is an example diagram of the engineering area overview in this embodiment;

[0041] Figure 3 This is an example diagram of the calculation grid of Xiaoyangshan Sea Area in this embodiment.

[0042] Figure 4 This is an example diagram of the process of calculating the churn rate in this embodiment;

[0043] Figure 5 This is an example diagram of the terrain and grid near the engineering waters in this embodiment;

[0044] Figure 6 This is an example diagram of the changes in the topography of the engineering waters after mud dumping is completed in this embodiment. DETAILED DESCRIPTION

[0045] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0046] In view of the above-mentioned technical problems existing in existing reclamation projects, the purpose of the present invention is to provide a method for pit site selection and mud dumping intensity planning in reclamation projects. Compared with the traditional empirical judgment method, the method of the present invention is more scientific, accurate and reliable, and can provide stronger support for the construction design and cost control of reclamation projects.

[0047] Depend on Figure 1 It can be seen that this plan can be used to plan the site selection and mud dumping intensity in reclamation projects through the following steps:

[0048] S1: Establishing a mathematical model for mud dumping

[0049] This step constructs a hydrodynamic mathematical model and suspended sediment transport through two-dimensional shallow water equations and convection-diffusion equations, which are used to establish a general model in subsequent steps.

[0050] S11: Establishing a hydrodynamic mathematical model

[0051] In this step, a hydrodynamic mathematical model is established through two-dimensional shallow water equations to describe the movement state of water in shallow water areas.

[0052] Specifically, this step is based on the three-dimensional Navier-Stokes equations, which are simplified to obtain the following two-dimensional shallow water equations:

[0053]

[0054] where c f Calculated using the Manning coefficient:

[0055]

[0056] Where η is the water level (m); h is the water depth (m); u and v are the vertical average x and y flow velocities (m / s); g is the gravitational acceleration (m / s2); c f is the dimensionless friction coefficient; n is the Manning coefficient (s / m1 / 3); v H is the horizontal eddy viscosity coefficient (m2 / s); f is the Coriolis force coefficient (1 / s); M x 、M y are the external momentum sources and sinks in the x and y directions (m / s2), respectively. The ADI method (Alternating Direction Implicit method) is used to solve the momentum conservation equation and the continuity equation to obtain the hydrodynamic field at each time step.

[0057] This scheme can improve simulation efficiency by simplifying the three-dimensional equations into two-dimensional shallow water equations, and is widely used in simulation and prediction of shallow water areas. Through reasonable numerical methods and calculation conditions, the water movement state that conforms to the actual situation can be obtained, providing important support for engineering design and disaster prevention and mitigation.

[0058] S12: Developing a suspended sediment transport model

[0059] This step is based on the water velocity field and water depth distribution calculated by the above two-dimensional shallow water equation, and uses the following convection-diffusion equation to simulate the movement and diffusion of sediment particles with the water flow.

[0060]

[0061] In the formula, c i is the concentration of the ith sediment component (kg / m3); ε s,x and ε s,y are the horizontal diffusion coefficients in the x and y directions (m2 / s); E i and D i are the erosion flux and deposition flux of the ith sediment component (kg / m2 / s), representing the sediment exchange between the water body and the seabed.

[0062] This scheme can describe the movement and diffusion of sediment particles with water flow by using the convection-diffusion equation, which has the advantages of conforming to physical principles, simplifying calculations, and wide applicability. By applying the convection-diffusion equation, simulation accuracy can be improved, engineering design can be optimized, and the ecological environment can be protected.

[0063] At the same time, it should be noted that the sediment transport module can consider cohesive sand and non-cohesive sand components separately or simultaneously. The two are distinguished by particle size, and the critical particle size is 0.063mm. Sediment smaller than the critical particle size is cohesive sand, which is transported in the form of suspended load; sediment larger than the critical particle size is non-cohesive sand, which can be transported in the form of both bed load and suspended load.

[0064] S2: General model building

[0065] This step is based on the mathematical model established in step 1, combined with the actual situation of the specific project, and forms a model that can be applied to the actual project through parameterization.

[0066] The parameterized parameter settings here include but are not limited to flow velocity (u, v), sediment diffusion coefficient (εsx, εsy), sediment still water settling velocity (ω), initial or boundary value of sediment content (S), spatial step (Δx, Δy), time step (Δt), etc. The settings of these parameters depend on the specific form of the equation, the research purpose, and the conditions of the experiment or numerical simulation, and are used to accurately describe the movement and diffusion of sediment particles with the water flow, thereby optimizing engineering design and protecting the ecological environment.

[0067] It should be noted here that the accuracy and rationality of parameter settings directly affect the accuracy and reliability of subsequent simulation results.

[0068] At the same time, the actual engineering situation here includes network resolution, constraints, sediment characteristics and source and sink item settings.

[0069] S21: Network resolution settings:

[0070] This step is used to select the appropriate grid type for segmentation according to the size and complexity of the study area to improve the accuracy of the simulation results and the computational efficiency.

[0071] For example, for large sea areas or river basins, a single large-scale computational grid can be used; for local complex areas, such as engineering waters or estuaries, a double-layer nested grid can be used for encryption processing.

[0072] Meshing is the basis for discretization of the research area. The resolution of the mesh (i.e., the size and density of the mesh) directly affects the accuracy of the simulation results and the computational efficiency. Determining the computational mesh plays a vital role in the model. By selecting the appropriate mesh type and resolution, the simulation accuracy can be improved, the computational efficiency can be optimized, different research needs can be met, and the simulation of complex flow fields can be supported. At the same time, in the meshing process, attention should be paid to the setting of the mesh resolution, the control of the mesh quality, and the consideration of computing resources and time.

[0073] S22: Set constraints:

[0074] This step is used to determine the boundary conditions of the model based on the topographic, hydrological and meteorological data of the studied area. The boundary conditions describe the interaction between the simulation area and the external environment, as well as the physical and chemical processes within the simulation area.

[0075] The boundary conditions include but are not limited to upstream open boundaries, downstream outflow boundaries, open sea boundaries, and land boundaries. The upstream open boundary can be set according to measured hydrological data or climatological average data, and the downstream outflow boundary can be set according to the flow balance principle or water level control conditions. The open sea boundary usually needs to be set according to tidal harmonic constants or tidal forecast data to ensure that the simulation results are consistent with the actual tidal process. The land boundary needs to be interpolated according to the terrain data to simulate the impact of land on the hydrodynamic process.

[0076] In ocean and river simulations, boundary conditions usually include parameters such as water velocity, water level, temperature, salinity, and wind stress.

[0077] S23: Determine the properties of the dredger fill sediment:

[0078] This step is used to determine the type and parameters of the dredged soil in the model according to the source and properties of the dredged soil in the actual project.

[0079] Sediment properties are key input data for simulating and predicting the sedimentation and consolidation processes of hydraulic fill. The types and parameters of hydraulic fill sediment include but are not limited to key parameters such as particle size distribution, density, and settling velocity. Different mathematical models and calculation methods are required for simulation and prediction of different types of sediment.

[0080] By accurately determining the properties of the dredger fill sediment, key issues such as the dredger fill sedimentation process, consolidation process and foundation deformation can be simulated and predicted more accurately, providing an important basis for engineering design and construction.

[0081] S24: Set source and sink items:

[0082] This step is used to set the source and sink items in the model according to the actual filling requirements and construction conditions of the project.

[0083] The source-sink term represents the injection or outflow in the fluid system and is the key parameter for simulating the flow and deposition pattern of sediment during the filling process. The source-sink term includes but is not limited to key parameters such as the location, number, filling intensity and filling direction of the filling ports. These parameters directly determine the flow and deposition pattern of sediment during the filling process.

[0084] The setting of filling intensity requires comprehensive consideration of factors such as the mud concentration of the construction vessel, pipe diameter, filling flow rate, and construction time.

[0085] The filling direction needs to be reasonably adjusted according to the terrain and water flow conditions of the project area to ensure the efficiency and safety of the filling process.

[0086] S25: General Model Validation and Optimization:

[0087] This step is used to verify the model by collecting measured data after the above general model is established.

[0088] The measured data here include but are not limited to the verification of key hydrological parameters such as water level, flow velocity, flow direction, etc. The accuracy and reliability of the model are evaluated by comparing the simulation results with the measured data.

[0089] If there is a large deviation between the simulation results and the measured data, the model needs to be further optimized and adjusted. The optimization process includes but is not limited to adjusting the grid resolution, improving the boundary condition settings, optimizing the sediment parameter settings, and adjusting the source and sink parameters.

[0090] S3: Calculate the loss rate at different dumping locations and dumping intensities

[0091] This step uses the general model verified in step 2 above to calculate the loss rate under different dumping pit locations and mud dumping intensities.

[0092] S31: Determine simulation parameters and conditions:

[0093] According to the specific dumping pit location and mud dumping intensity, the mud dumping area and source strength parameters in the simulation, as well as key parameters such as simulation time, sand pile volume, simulation parameters, etc. are reasonably set.

[0094] Reasonable mud dumping area and source strength parameter settings can reflect the mud dumping process in actual conditions. For example, by considering the impact of environmental factors such as water flow velocity and tidal changes on the mud dumping process, the diffusion and deposition process of sediment can be simulated more accurately.

[0095] The mud dumping area and source strength parameters are set according to the specific dumping pit location and mud dumping intensity, and the mud dumping area and source strength parameters in the simulation are reasonably set. The mud dumping area and source strength parameters include but are not limited to the location, number, mud dumping rate and mud dumping direction of the mud dumping port.

[0096] Simulation duration: specify the duration of the simulated mud dumping and stockpiling stages, for example, 3 days for mud dumping and 5 days for stockpiling.

[0097] Sand pile volume: Determine the total volume of the sand pile in the simulation, such as 270,000 m in this example. 3 .

[0098] Simulation parameter table: lists in detail all key parameters used for simulation, including water velocity, tidal changes, sediment particle size distribution, etc.

[0099] S32: Select adverse conditions and analyze them:

[0100] Evaluate the maximum loss rate that may occur during mud dumping under specific adverse conditions, and explore how this loss rate is affected by the location of the dumping pit and the intensity of mud dumping. Through this analysis, a more comprehensive and in-depth scientific basis can be provided for engineering design and construction to ensure the smooth progress of the mud dumping process and the protection of the environment.

[0101] Determination of adverse conditions: According to the actual project and simulation requirements, select the unfavorable mud dumping period, such as selecting the high tide period as the mud dumping period.

[0102] Analyze the change of loss rate: Under the selected adverse conditions, simulation calculations are carried out to analyze the change of loss rate under different dumping pit locations and mud dumping intensities.

[0103] S33: Calculate the churn rate:

[0104] Deposition morphology simulation: Using the model established by S1 and S2, by inputting parameters such as water flow velocity, direction, water depth, and sediment particle size and density, the model can calculate the sediment transport and accumulation morphology. This process helps predict the impact of mud dumping operations on the surrounding environment and provides a scientific basis for subsequent loss rate calculations and optimization recommendations.

[0105] Simulation of loss: Based on the simulation of accumulation morphology, the loss of mud is further simulated and calculated, including the amount of lost sediment, loss direction and loss speed.

[0106] Specifically, the total amount of discharged sediment and the amount of accumulated sediment are calculated through simulation, and the difference is the amount of lost sediment; the direction of sediment loss can be known from the expansion direction of sediment concentration; and the sediment loss rate can be obtained by combining the changes in sediment in the cross section.

[0107] Calculation of loss rate: Based on the simulation results, calculate the loss rate under different dumping pit locations and mud dumping intensities. The loss rate can be calculated by dividing the amount of lost sediment by the total mud dumping amount.

[0108] S34: Result analysis and optimization:

[0109] Result comparison: Compare the simulation results with the actual situation and analyze the accuracy and reliability of the simulation results.

[0110] Optimization suggestions: Based on the simulation results, suggestions are put forward to optimize the dumping pit location and mud dumping intensity to reduce the loss rate and improve the mud dumping efficiency.

[0111] The method for site selection and mud dumping intensity planning in reclamation projects given in this example can be used as a corresponding software program to form a corresponding system for site selection and mud dumping intensity planning in reclamation projects. When the software program is running, it will execute the method for site selection and mud dumping intensity planning in reclamation projects, and store it in a corresponding storage medium for the processor to retrieve and execute.

[0112] The system for dumping pit site selection and mud dumping intensity planning in reclamation projects formed in this way mainly includes: mud dumping mathematical model building module, general model building module, and loss rate calculation module.

[0113] Among them, the mud dumping mathematical model establishment module in this system constructs a mud dumping mathematical model by establishing a hydrodynamic mathematical model and a sediment transport model, which is used for establishing a general model in subsequent steps.

[0114] The mud dumping mathematical model building module includes a hydrodynamic mathematical model building unit and a suspended sediment transport model building unit.

[0115] The hydrodynamic mathematical model building unit builds a hydrodynamic mathematical model through two-dimensional shallow water equations to describe the movement state of water in shallow water areas.

[0116] The suspended sediment transport model establishment unit uses the convection-diffusion equation to simulate the movement and diffusion of sediment particles with the water flow based on the water velocity field and water depth distribution calculated by the above two-dimensional shallow water equation.

[0117] The mud throwing mathematical model establishing module is configured to execute the above mud throwing mathematical model establishing steps to realize corresponding functions.

[0118] The general model building module in this system interacts with the mud dumping mathematical model building module in data. It is based on the mathematical model established by the mud dumping mathematical model building module and combines the actual situation of the specific project to form a model that can be applied to the actual project through parameterization.

[0119] The general model building module includes a parameter setting unit, a network resolution setting unit, a constraint condition setting unit, a sediment characteristic setting unit, a source and sink item setting unit, and a verification and optimization unit.

[0120] The parameters in the parameter setting unit include but are not limited to flow velocity (u, v), sediment diffusion coefficient (εsx, εsy), sediment still water settling velocity (ω), initial or boundary value of sediment content (S), spatial step (Δx, Δy), time step (Δt), etc.

[0121] The network resolution setting unit is used to select the appropriate grid type for subdivision according to the size and complexity of the study area to improve the accuracy of the simulation results and the calculation efficiency.

[0122] The constraint setting unit is used to determine the boundary conditions of the model based on the topographic, hydrological and meteorological data of the studied area.

[0123] It is used to determine the type and parameters of dredged soil in the model according to the source and properties of dredged soil in actual projects.

[0124] The source and sink item setting unit is used to set the source and sink items in the model according to the actual filling requirements and construction conditions of the project.

[0125] The verification and optimization unit is used to verify the general model by collecting measured data.

[0126] The measured data here include but are not limited to the verification of key hydrological parameters such as water level, flow velocity, flow direction, etc. By comparing the simulation results with the measured data, the accuracy and reliability of the general model are evaluated.

[0127] The general model building module is configured to execute the above general model building steps to realize corresponding functions.

[0128] The loss rate calculation module in this system interacts with the general model building module in data, and the loss rate calculation under different dumping pit locations and mud dumping intensities is carried out through the general model verified in the general model building module.

[0129] The churn rate calculation module includes a simulation parameter and condition determination unit, an adverse condition selection and analysis unit, a calculation unit, and an analysis and optimization unit.

[0130] The simulation parameter and condition determination unit is used to reasonably set the mud dumping area and source strength parameters in the simulation, as well as key parameters such as simulation time, sand pile volume, simulation parameters, etc. according to the specific dumping pit location and mud dumping intensity.

[0131] The adverse condition selection and analysis unit is used to evaluate the maximum loss rate that may occur during mud dumping under specific adverse conditions, and to explore how this loss rate is affected by the location of the dumping pit and the intensity of mud dumping.

[0132] The calculation unit calculates the sediment loss rate by dividing the amount of lost sediment by the total amount of thrown sediment.

[0133] The analysis and optimization unit is used to compare the simulation results with the actual situation. According to the simulation results, suggestions are put forward to optimize the dumping pit location and mud dumping intensity to reduce the loss rate and improve the mud dumping efficiency.

[0134] The churn rate calculation module is configured to execute the above churn rate calculation steps to realize corresponding functions.

[0135] Based on the above scheme, the method and system for site selection and mud dumping intensity planning in reclamation projects are described below with examples of their working process in specific applications. It should be noted that the working process is only an example and does not limit this scheme. For details, see Figure 4 .

[0136] This invention intends to take the pit site selection and mud dumping intensity issues in the Xiaoyangshan North Reclamation Area as an example. The Xiaoyangshan North land formation project is located on the north side of Xiaoyangshan in the rugged archipelago sea area at the junction of the Yangtze River Estuary and Hangzhou Bay on the eastern coast. The geographical coordinates are approximately 30°38′N, 122°05′E. It is about 70km away from the Yangtze River Estuary lightship in the north and about 90km away from Ningbo Beilun Port in the southwest. It directly connects to the open sea through Huangzeyang in the east and is about 104km away from the international ocean shipping route. It is connected to Shanghai Luchao Port by land through the East China Sea Bridge. The planned Xiaoyangshan North operation area is located on the north side of the Yangshan Deepwater Port Area, with the mountain of Bodaozui Island as the natural boundary in the east and Xiaoyangshan Island as the natural boundary in the west. It is planned to be a specialized container port area. The total reclamation area is 5.5km2, and the order of reclamation is West Area 1, West Area 2, West Area 3, East Area 2, East Area 1 ( Figure 2 ).

[0137] The specific implementation steps are as follows:

[0138] (1) Before the project is implemented, basic data on model construction and on-site construction data of the selected research and test area are collected;

[0139] In the nearshore land reclamation project, dredging and filling is an important engineering method. In the conventional dredging and filling process, the combined construction technology of raking and dredging is often adopted. The process flow is: dredging in the channel by a raking and suction hopper ship → the raking and suction hopper ship sails to the mud storage pit after the tank is full → the raking and suction hopper ship enters the mud storage pit to dump mud → the mud storage pit is full → the dredger enters the mud storage pit to dredge and blow mud → floating pipe → sunken pipe → onshore pipeline → filling area. The Xiaoyangshan North Land Project is also planned to adopt this method. The dredged soil for filling mainly comes from the deep-water channel of the North Channel of the Yangtze River Estuary, which is mainly silt. However, during the period of mud dumping by the raking and suction hopper ship and the storage period in the mud storage pit, the loss rate of sediment under the action of water flow will be considered. How to accurately estimate the loss rate and determine the reasonable amount of sand to be prepared is the key to ensuring the progress of filling and controlling construction costs.

[0140] In this case, the dredged soil comes from the Yangtze River Estuary Deepwater Channel. According to the measured soil quality data analysis, the dredged soil produced by the Yangtze River Estuary Deepwater Channel Maintenance Project is silt. For the main.

[0141] The soil supply of the trailing suction hopper is 2 million m 3 / month, West District 3 and East District 1 are equipped with 2 mud storage pits, each with a soil supply of 1 million m 3 / month, the mud storage capacity of each mud storage pit: 300m×300m×3m=270000m 3, the mud throwing and storage time is 8 days. In this paper, a mud storage pit location in each district is selected as a representative, the mud throwing period is set at 3 days, and the storage period is 5 days, and the mud loss rate of the mud storage pit under this condition is calculated.

[0142] (2) Based on the Navier-Stokes equations, the three-dimensional horizontal momentum equation and continuity equation are integrated along the water depth, ignoring the vertical difference of the water body, and the two-dimensional shallow water equation is obtained. The hydrodynamic and sediment mathematical model is constructed, and the filling process is numerically simulated by unstructured grid discretization. Figure 3 ); and according to the analysis of particle size data, the dredged fill soil is mainly silt. Therefore, the dredged sediment in this model is set as silt.

[0143] (3) The numerical simulation of the mud dumping process is divided into two stages: mud dumping and stockpiling. The accumulation morphology and loss of mud dumping are simulated and calculated. The mud dumping time is 3 days, the stockpiling time is 5 days, and the volume of sand pile is about 270,000 m3. The simulation parameters are shown in Table 1.

[0144] Table 1 Numerical simulation parameters of mud dumping

[0145] stage Duration Mud throwing strength Throwing mud 3 days 1770kg / s Sand pile 5 days /

[0146] For the construction period, in order to analyze the changes in the mud loss rate under adverse conditions, the high tide period from September 2 to September 4, 2020 was selected as the mud throwing period, and the subsequent 5 days (September 5 to September 9, 2020) were selected as the sand piling stage to ensure that the entire high tide period was included.

[0147] (4) Analyze and compare the mud dumping process under different working conditions, compare their loss rates, and analyze them in combination with the flow field. The loss rate mainly includes the loss rate during the mud dumping process and the loss rate during the storage period after mud dumping.

[0148] Condition 1: West Area 1 and West Area 2 are enclosed, and a mud pit is set up in West Area 3. The depth of the mud pit is 3m, and the location is not clear at this stage. Therefore, this paper selects the location of the mud pit near West Area 2 in West Area 3, and further digs it about 3m deeper according to the average water depth ( Figure 5 The water depth of the original mud pit was about -9m, and after deepening, the water depth of the mud pit was -12m (85 base surface).

[0149] Working condition 1: mud dumping stage. At the end of mud dumping stage, the elevation change in the mud storage pit is as follows: Figure 6 It can be seen that the average elevation inside the mud pit rises by about 2m, and the maximum elevation rises by more than 4m.

[0150] The change of sediment loss in working condition 1 is shown in Table 2. It can be seen from the table that after the 270,000 m3 of sediment was dumped, the amount of sediment in the mud pit was 168,493 m3, so the amount of sediment loss caused by the dumping was 101,507 m3, and the loss rate of the dumping was 37.6%; in the subsequent storage stage, the amount of sediment left in the pit after storage was 163,635 m3, the amount of sediment loss was 4,858 m3, and the storage loss rate was 2.9%. After calculation, in working condition 1, the overall sediment loss rate was 39.4%.

[0151] Table 2 Statistical results of sediment loss under condition 1

[0152] Total amount of mud dumped (m3) 270000 Amount of silt in the pit after dumping (m3) 168493 Amount of residue left in the pit after storage (m3) 163635 Mud loss (m3) 101507 Stockpile loss (m3) 4858 Loss rate in mud dumping stage (%) 37.6 Loss rate in storage stage (%) 2.9 Total churn rate (%) 39.4

[0153] In this way, the location of the mud dumping pit and the mud dumping intensity are repeatedly adjusted, the corresponding sediment loss rate is calculated, and the most economical engineering plan is selected by comparison.

[0154] In summary, the site selection and mud dumping intensity planning method of this reclamation project is highly scientific and accurate; secondly, comprehensive consideration of multi-dimensional information and the introduction of numerical simulation and flow field analysis make the planning method more systematic and can accurately predict the sediment loss rate.

[0155] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for site selection and mud dumping intensity planning in land reclamation projects, characterized in that: The method for selecting a pit site and planning mud dumping intensity in the land reclamation project comprises the following steps: Step 1: Establish a mathematical model for mud dumping This step constructs a hydrodynamic mathematical model and suspended sediment transport through two-dimensional shallow water equations and convection-diffusion equations; Step 2: General model building This step is based on the mathematical model established in step 1, combined with the actual situation of the specific project, and forms a model that can be applied to the actual project through parameterization; Step 3: Calculate the loss rate at different dumping locations and dumping intensities This step uses the general model in step 2 above to calculate the loss rate under different dumping locations and mud dumping intensities by inputting key parameters.

2. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1 is characterized in that: The actual engineering conditions include network resolution, constraints, sediment characteristics, and the setting of source and sink items.

3. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: The network resolution is determined by selecting an appropriate grid type for segmentation based on the size and complexity of the study area.

4. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: Constraints are used to determine the boundary conditions of the model based on topographic, hydrological and meteorological data of the study area.

5. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: Determining the properties of dredged fill sediment is used to determine the type and parameters of dredged fill sediment in the model based on the source and properties of dredged soil in actual projects.

6. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: Setting source and sink items is used to set the source and sink items in the model according to the actual filling requirements and construction conditions of the project.

7. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: After the general model is established, the model is verified by collecting measured data. If there is a large deviation between the simulation results and the measured data, the model needs to be further optimized and adjusted.

8. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: The calculation of the loss rate at different dumping pit locations and dumping intensities in step 3 includes the following steps: (1): According to the specific dumping pit location and dumping intensity, the dumping area and source strength parameters in the simulation, as well as the simulation time, sand pile volume, and key simulation parameters are reasonably set; (3) To evaluate the maximum loss rate that may occur during mud dumping under specific adverse conditions and explore how this loss rate is affected by the location of the dumping pit and the intensity of mud dumping; (4) Calculate the transport and accumulation form of sediment using the model established in step 1 and step 2, and further simulate and calculate the loss of mud dumping based on the simulation of the accumulation form; The total amount of thrown sediment and the amount of accumulated sediment are calculated through simulation, and the difference is the amount of lost sediment; the direction of sediment loss can be known from the expansion direction of sediment concentration; the sediment loss rate can be obtained by combining the changes in cross-section sediment; (5) Compare the simulation results with the actual situation and, based on the simulation results, put forward suggestions for optimizing the dumping pit location and mud dumping intensity.

9. The method for site selection and mud dumping intensity planning in a reclamation project according to claim 1, characterized in that: Compare the simulation results calculated in step 3 with the actual situation, and make suggestions for optimizing the dumping pit location and mud dumping intensity based on the simulation results.

10. A system for site selection and mud dumping intensity planning in land reclamation projects, characterized in that: The dumping pit site selection and mud dumping intensity planning system in the marine engineering includes: A mud dumping mathematical model establishment module, wherein the mud dumping mathematical model establishment module constructs a mud dumping mathematical model by establishing a hydrodynamic mathematical model and a sediment transport model; A general model building module, which interacts with the mud dumping mathematical model building module in data, and forms a model applicable to actual projects through parameterization based on the mathematical model established by the mud dumping mathematical model building module and in combination with the actual conditions of the specific project; The loss rate calculation module interacts with the general model building module to calculate the loss rate under different dumping positions and mud dumping intensities through the general model verified in the general model building module.

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