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CN-122016620-A - Multi-metal tuberculosis area deep sea bottom flow re-erosion rate experimental device and testing method

CN122016620ACN 122016620 ACN122016620 ACN 122016620ACN-122016620-A

Abstract

The invention relates to the field of deep sea mining environment influence simulation and deposition dynamics experiment test, and particularly provides a multi-metal tuberculosis region deep sea bottom flow re-erosion rate experiment device and a test method. The device comprises an annular water tank, a sedimentation tank, an acoustic ranging type depth gauge, an underwater camera, an acoustic Doppler flow velocity meter, a multi-parameter turbidity meter and other data collection modules which are arranged on the sedimentation tank. The testing method synchronously collects multi-source data such as the thickness of a sediment layer, the concentration of suspended particles, the flow speed, the bed surface image and the like through a plurality of sensors, establishes a mass conservation relation and image thickness inversion model, calculates the erosion rate of single points and areas, and introduces the volume fraction of tuberculosis and the correction critical shear stress of the buried depth. And the prediction of the erosion rate under the future working condition is further realized by combining a physical constraint neural network. The invention realizes quantitative, spatial and predictive analysis of the erosion process of the plume redeposition layer under indoor controllable conditions, and remarkably improves the accuracy and engineering applicability of the mining environment influence assessment of the deep sea tuberculosis area.

Inventors

  • JIA YONGGANG
  • ZHANG ZHICHENG
  • ZHU XIANMING
  • CHEN XIANG
  • FAN ZHIHAN
  • Quan Yongzheng

Assignees

  • 中国海洋大学

Dates

Publication Date
20260512
Application Date
20260226

Claims (6)

  1. 1. The experimental device for the multi-metal tuberculosis area deep sea bottom flow re-erosion rate comprises an annular water tank (8) and is characterized in that the annular water tank (8) is supported by a bearing frame (12) fixedly arranged at the bottom of the annular water tank and a bridge (15) in the middle of the annular water tank, a hoop (5) is arranged on the annular water tank (8), a metal bracket (6) is fixedly arranged at the top of the annular water tank (8), a data collecting module is fixedly arranged on the annular water tank (8) through the hoop (5) and the metal bracket (6), a data processor (16) is fixedly arranged at the upper part of the bridge (15), a settling tank (11) communicated with the bottom of the annular water tank (8) is arranged below the front part of the annular water tank (8), a wheel propeller current generator (7) is arranged at the rear part in the annular water tank (8), deep sea sediment (10) in the settling tank (11) is flush with the bottom of the annular water tank (8), multi-metal tuberculosis (9) are distributed in the deep sea sediment (10), and partition plates (13) capable of lifting through partition plate lifters (14) are respectively arranged on the left and right side walls and the settling tank (11); the data collection module comprises an acoustic ranging type depth gauge (1) and an underwater camera (4) which are positioned at the upper part of the sedimentation tank (11), an acoustic Doppler velocimeter (2) positioned at the left end of the sedimentation tank (11) and a multi-parameter turbidimeter (3) positioned at the right end of the sedimentation tank (11); the annular water tank (8) is provided with a flow rate controller (18).
  2. 2. The experimental device for the re-erosion rate of the deep sea bottom flow in the multi-metal tuberculosis area is characterized in that the acoustic ranging type depth gauge (1) is arranged at a position 20cm above a settling tank (11), an acoustic Doppler flow velocity meter (2) is fixed on a metal support (6) and is detected to be 10cm away from the bottom of an annular water tank (8), a multi-parameter turbidity meter (3) is fixed on the metal support (6) and is detected to be 10cm away from the bottom of the annular water tank (8), and an underwater camera (4) is fixed above the settling tank through a hoop (5).
  3. 3. A multi-metal nodule area deep sea underflow re-erosion rate experiment device according to claim 1, wherein the impeller blade flow generator (7) is equipped with blades (17).
  4. 4. The test method of the multi-metal tuberculosis area deep sea bottom flow re-erosion rate experimental device is characterized by comprising the following steps of: S1, checking and initializing a test system, namely performing reference calibration on an acoustic ranging type depth gauge (1) to obtain an initial distance H 0 from a probe to a bottom plate of a sedimentation tank, performing zero point and range calibration on a multi-parameter turbidity meter (3) and establishing a calibration relation between turbidity and suspended particle concentration, performing zero flow rate calibration on an acoustic Doppler flow velocity meter (2), and confirming that the position of the acoustic Doppler flow velocity meter at the near-bottom layer measured height is correct; S2, constructing a plume deposit bed, namely paving a pre-prepared deep sea deposit (10) sample and a polymetallic nodule (9) simulation sample in a sedimentation tank (11) of an annular water tank (8) to form a uniform simulated deep sea mining area bottom bed at the bottom of the sedimentation tank (11); s3, module defense arrangement and adjustment, namely arranging an acoustic ranging type depth gauge (1), an acoustic Doppler velocimeter (2), a multi-parameter turbidimeter (3) and an underwater camera (4) in an annular water tank (8) to enable an observation area to cover a plume deposition area in the center of a sedimentation tank (11), slowly injecting simulated seawater into the annular water tank (8), and raising a baffle plate (13) to enable the sedimentation tank (11) to be isolated from the simulated seawater when the water level reaches a set height so as to construct a stable local plume redeposition and re-erosion experimental environment; s4, after all the instruments are assembled, injecting a plume sediment sample into a sedimentation tank (11) from above an annular water tank (8) in a controlled manner, naturally settling the plume sediment sample under the condition of still water or different flow rates, forming a plume redeposition layer on the surface of a bottom bed, and confirming the spatial continuity and coverage state of the sedimentation layer in a visual field range by utilizing an underwater camera; S5, data acquisition and erosion rate calculation, namely, descending a baffle plate (13), starting a flow system of the annular water tank (8), enabling the flow rate near the bottom layer to change step by step according to set working conditions, and synchronously acquiring measurement and calculation data transmitted by each module.
  5. 5. The method for testing the multi-metal nodule area deep sea bottom flow re-erosion rate experiment device according to claim 4, wherein the step S5 specifically comprises the following steps: s5-1, calculating the underflow driving force: The flow velocity meter measures that the flow velocity near the bottom layer above the deposition layer is U (t), and the shear stress of the surface layer of the deposition is: Wherein the method comprises the steps of To act on the shear stress Pa of the plume deposit surface, Is the density of the water body, The sea bed resistance coefficient is U, and the bottom sea current flow rate is U; S5-2, correcting the influence of multi-metal tuberculosis: let the volume fraction of the polymetallic nodules in the deposition area be The average depth of burial of tuberculosis is D n , defining the tuberculosis enhancement coefficient: In the formula, For the enhancement factor of the tuberculosis, The volume fraction of the multi-metal nodules is D n , the average burial depth m of the multi-metal nodules is alpha and beta, and the morphology and the quality coefficient of the multi-metal nodules are obtained; s5-3, judging the erosion state: The effective critical shear stress is: In the middle of Equivalent critical shear stress for the deposit in the presence of multi-metal nodules, For the critical shear stress of the deposit, Is a conversion coefficient; Defining a flow driving factor: In the middle of Is an erosion degree factor; s5-4, resuspension inversion: Geometric thickness of deposited layer and re-suspension mass: In the middle of For the plume to redeposit the layer thickness, For the initial depth of water to be the same, For the value of the acoustic ranging measurements, Is the suspended particle concentration at height z; s5-5, erosion rate calculation: Single point erosion rate calculation considering tuberculosis and flow rate: In the middle of To account for the presence of multi-metal nodules and plume deposit erosion rate after ocean current influence, The density of the plume deposit particles, In order to deposit the layer of porosity, In order to deposit the layer thickness rate of change, For the rate of change of mass of suspended particles, when If the value is=0, judging that no erosion occurs; deposition rate under influence of tuberculosis: s5-6, extracting image information: Expanding the erosion rate of a single point in the whole view range, wherein the physical relationship between the image gray scale and the deposition thickness is that an original image obtained by an underwater camera is: wherein: The plane coordinates are expressed as plane coordinates of pixels in the image, t represents observation time, and I is the gray value of the image; After plume deposit coverage, the bottom bed reflectivity and light scattering change, so that under calibration conditions, gray scale and deposit thickness have a functional relationship, and the image is converted into a thickness field: In the middle of Representative of the pixel [ ] ) Plume deposit thickness at t, Then it is a mapping function between the gray value and the deposit; s5-7, redeposition inversion: the average deposition thickness in the viewing area is: In the middle of The average sediment thickness in the view range is given, and A is the view area acquired by the underwater camera. The single pixel area is deltaa, then the plume deposition volume is: Total deposition amount in view: wherein: in order to achieve a particle density of the particles, Is porosity; The image deposition thickness field is jointly constrained with the acoustic single point thickness: wherein: for the thickness of the effective deposited layer after the fusion, Is a weight coefficient; s5-8, calculating the area erosion rate: Image overlay weights: In the middle of Representative is the plume coverage area resulting from image recognition. Total erosion rate: S5-9, erosion rate and resuspension flux prediction: constructing a history sample based on the multi-source data: for each historical time t i , a feature vector is constructed: The erosion rate of the corresponding output is: the output result accords with physical constraint, and the following loss function is constructed in the training process: wherein: For the predicted total erosion rate in the field of view of the neural network, For practical erosion rates in the field of view of the multisensor system inversion, The actual erosion rate calculated from the model. Predicting the erosion rate under future working conditions, wherein the future working conditions are as follows: the predicted future erosion rates are: In unit time, the mass of sediment eroded by the bed surface enters the overlying water body to form re-suspended particles, so that the flux of re-suspended mass per unit area in the view range can be directly expressed by the erosion rate: In the middle of For the volumetric flux of sediment re-suspension, In order to suspend the particle density of the sediment, In order for the porosity of the deposit to be such that, Is the average deposition rate. In order to ensure the consistency of the resuspension flux calculation result and experimental observation, the resuspension flux needs to satisfy the conservation relation of suspended particle mass: In the middle of For suspended sediment concentration at height z, For the near-bottom effective water layer thickness, The output flux caused by water flow transportation. Calculated resuspension volume flux Further used for the prediction of redeposition thickness variation, the relationship is: In the middle of For an average deposition thickness in the field of view, Is the deposition rate per unit area.
  6. 6. The method for testing a multi-metal nodule area deep sea underflow re-erosion rate experiment apparatus according to claim 4, further comprising step S6 of mining area application prediction: Building a mining area state input vector aiming at a target mining area: In the middle of Is the near-bottom average flow rate of the deep sea mining area, Is the average shear stress of the bed surface of the mining area, A single mining operation affects the area of the mine, For the duration of a single mining operation, Is the nodule abundance of the polymetallic nodule mining area, Is the average burial depth of the tuberculosis, The source of sediment released for disturbances during mining operations is strong. Substituting mining area input parameters into an erosion rate prediction model obtained based on experimental data training to obtain the average erosion rate of mining area dimensions: In the middle of Is the erosion rate per unit area inside the deep sea mining area, Is a predictive model trained based on experimental data of the present invention.

Description

Multi-metal tuberculosis area deep sea bottom flow re-erosion rate experimental device and testing method Technical Field The invention relates to the technical field of deep sea mining environment influence simulation and deposition dynamics experiment test, in particular to an experimental device and a test method for the re-erosion rate of deep sea bottom flow in a multi-metal tuberculosis area, an indoor experimental device and a test method for the re-deposition and re-erosion process of the plume caused by the action of the deep sea bottom flow under the multi-metal tuberculosis mining condition, in particular to a comprehensive test and analysis method for quantitatively inverting and predicting sediment thickness variation, suspended particle mass flux and regional erosion rate based on multi-source data fusion of an acoustic ranging type depth gauge, a turbidity meter, a flow rate meter and an underwater camera by combining multi-metal nodule distribution characteristics and hydrodynamic parameters, which is suitable for indoor physical simulation and evaluation of a multi-metal nodule sediment re-erosion mechanism and environmental influence under a deep sea mining disturbance condition. Background Along with the continuous progress of deep-sea mineral resource development technology, commercial exploitation of deep-sea mineral such as polymetallic nodule has gradually entered engineering verification and trial exploitation stages. The polymetallic nodules are widely distributed on the surface layer of the deep sea plain, and the occurrence environment of the polymetallic nodules has the typical characteristics of low deposition rate, weak hydrodynamic force, thin coverage of fine sediment, high sensitivity to disturbance and the like. During the mining operation, the disturbance of the mining vehicle to the seabed surface layer and the tail water discharged by the lifting system generate a large amount of fine particle plumes which are diffused, settled and covered on the original tuberculosis area and the surrounding seabed again under the action of the near-bottom water power to form a mining induced sediment layer. Research has shown that mining plume redeposition layers generally have the characteristics of high porosity, loose structure, low shear strength and the like, and are extremely easy to re-erode and re-suspend under the action of deep sea underflow, so that the long-term circulating diffusion of plume particles is caused, and the long-term circulating diffusion has continuous influence on benthonic habitats, tuberculosis regeneration environments and regional deposition patterns. Therefore, quantitative measurement and prediction of erosion rates, re-suspension flux and spatial distribution characteristics of the mining induced sedimentary deposit under different flow rates and different tuberculosis distribution conditions are key scientific and technical problems of deep sea mining environment influence evaluation and engineering scheme optimization. The prior related researches mainly depend on means such as on-site turbidity monitoring, acoustic echo detection or discrete sampling analysis to estimate plume concentration or deposition change, but the prior methods have the defects that firstly, most of the methods only can acquire single-point or single-height layer data, the spatial non-uniformity of plume redeposition and erosion process is difficult to reflect, secondly, the lack of reliable physical conversion relation between turbidity and deposition thickness is difficult to directly obtain real deposition quality and erosion flux, thirdly, the prior methods usually neglect the spatial distribution of multi-metal tuberculosis and the modulation effect of the spatial distribution on the stability of a bed surface, so that great deviation exists in description of the real erosion process of a tuberculosis area, and fourthly, the prior testing methods mainly use post analysis, and the predictability evaluation of erosion processes under different flow speed working conditions and tuberculosis covering conditions is difficult. Therefore, a comprehensive testing device and method capable of simultaneously acquiring the thickness of a sediment layer, the quality of suspended particles, hydrodynamic conditions and tuberculosis distribution characteristics under indoor controllable conditions, expanding single-point measurement results to regional dimensions and further realizing quantitative inversion and prediction of erosion rates are needed, so as to provide scientific basis for environmental impact assessment and engineering design of deep-sea multi-metal tuberculosis mining activities. Disclosure of Invention In order to make up for the defects of the prior art, the invention provides a multi-metal tuberculosis area deep sea bottom flow re-erosion rate experimental device and a testing method. Aiming at the problems that in the existing deep sea multi-metal nodule mining env