43 results about "Bed load" patented technology

The invention discloses a bed load particle starting test method and device, and relates to the technical field of hydromechanics, the method comprises the following steps: laying sediment particles in a wave water tank, and adjusting the water flow rate through flow control until the bed surface shear stress is less than the critical shear stress; tracer particles are excited to emit fluorescence through a laser beam, and a camera array is used for synchronously collecting instantaneous flow velocity of a flow field and displacement data of sediment particles; analyzing spatial and temporal distribution characteristics of turbulence energy dissipation and pressure energy dissipation based on a turbulence burst process, and establishing a sediment particle starting mathematical model; experimental data and computational fluid mechanics numerical simulation are combined, and the mathematical model is verified and optimized. According to the technical scheme, the analysis precision and the experimental convergence speed of the sediment starting criterion under the complex hydrodynamic force condition can be remarkably improved, and full-chain efficient cooperation from micromechanical response to macroscopic engineering application is achieved.

The invention relates to the technical field of water conservancy and hydropower engineering, and discloses a sediment-carrying bed load riverway water taking structure which comprises a bed stabilizing structure, a flow guiding structure and a water taking structure, the bed stabilizing structure is arranged perpendicular to the water flow direction of a riverway, and one end of the bed stabilizing structure is connected with one side of the riverway; one side of the diversion structure is connected with the other end of the bed stabilizing structure, and the other side is connected with one end of the flood discharge gate; the water taking structure comprises a water taking weir, a pre-sedimentation tank and a sand blocking ridge, the pre-sedimentation tank is arranged on the other side of the river channel, the outer wall of the pre-sedimentation tank is connected with the flood discharge gate, the water taking weir is arranged on the side, close to the flood discharge gate, of the pre-sedimentation tank, and the sand blocking ridge is arranged on the downstream of the pre-sedimentation tank. The water taking structure carries out water taking and desilting, the water diversion and sand prevention problems of the river channel water taking opening are solved, and the operation efficiency of the water taking system is improved.

The invention discloses a riverbed sediment particle analysis method and a related device, and relates to the technical field of hydraulic engineering and sediment testing.The method comprises the steps that firstly, the light intensity penetrating through a preset plane at each moment in a plurality of moments in the riverbed sediment sample sedimentation process is obtained; the preset plane is any one of the horizontal planes except the highest horizontal plane and the lowest horizontal plane in a sample container filled with the riverbed sediment uniformly-mixed suspension, riverbed sediment with different particle sizes in the riverbed sediment sample settles to the preset plane at different settling speeds, and for each particle size, based on the light intensity penetrating through the preset plane at each moment, the light intensity of the riverbed sediment in the riverbed sediment sample is calculated. Calculating to obtain the percentage of the sand weight smaller than the particle size, based on each particle size and the percentage of the sand weight smaller than the particle size, obtaining the grain composition and the grain composition curve, and further calculating the vertical line average grain composition, the section average grain composition and the section average particle size. According to the method, the particle analysis of the riverbed sediment can be accurately completed.

Embodiments of the present application disclose a river bed load transport characteristic determination method and device, electronic equipment and a computer readable medium, relating to the field of engineering technology. The method performs fast Fourier transform on the sound pressure signals of the microphone array to obtain a sound pressure matrix in the frequency domain; based on the sound pressure matrix, cross-spectrum operation is performed to obtain a cross-spectrum matrix; based on each scanning grid point j on the surface of the monitoring sensor plate as an imaginary sound source point, a sound propagation model is selected according to the aerodynamics theory to determine the sound signal monitored by any microphone; each grid point is scanned, the auto-spectrum of the simulated sound signal is calculated, and the sound source holographic image of the bed load shock wave is determined; the sound source intensity is simulated, the bed load spatial position is obtained, and the bed load particle size component information is obtained through the calibration function relationship. That is, in the present application, the bed load spatial position and the bed load particle size component information are obtained, this method can accurately determine the transport characteristics of the bed load, and becomes an important support for quantifying the disaster prevention and reduction work of mountainous rivers.

The present application relates to the technical fields of water conservancy and hydropower engineering, and discloses a multi-sediment bed load river channel water intake structure, which comprises a stable bed structure, a flow guide structure and a water intake structure, the stable bed structure is arranged perpendicularly to the water flow direction of the river channel, and one end of the stable bed structure is connected with one side of the river channel; one side of the flow guide structure is connected with the other end of the stable bed structure, and the other side is connected with one end of a flood discharge gate; the water intake structure comprises a water intake weir, a pre-sedimentation tank and a sand blocking ridge, the pre-sedimentation tank is arranged on the other side of the river channel, the outer wall of the pre-sedimentation tank is connected with the flood discharge gate, the water intake weir is arranged on the side of the pre-sedimentation tank close to the flood discharge gate, and the sand blocking ridge is arranged downstream of the pre-sedimentation tank, the present application stabilizes the river regime through the stable bed structure, narrows the river bed below the flow guide structure to discharge the bed load, and the water intake structure is used for water intake and sand setting, so that the problem of water diversion and sand prevention of the river channel water intake is solved, and the operation efficiency of the water intake system is improved.

The invention relates to the technical field of measurement, and discloses a mountain river bed load motion attitude and sediment transport flux monitoring method and system, and the system comprises a data collection module which is used for obtaining the triaxial angular velocity data, the triaxial acceleration data and the triaxial magnetometer data of a bed load; the motion attitude extraction module is used for correcting the three-axis angular velocity data by using the three-axis acceleration data and the three-axis magnetometer data, extracting a real-time quaternion based on the corrected three-axis angular velocity data, calculating an attitude angle through the real-time quaternion, calculating accumulated displacement of a bed load based on the three-axis acceleration data, and calculating the motion attitude of the bed load according to the accumulated displacement. Using the accumulated displacement and the attitude angle to represent the motion attitude of the bed load; and the sediment transport flux calculation module is used for calculating the total sediment transport amount of the river channel. According to the method, the motion state of the bed load can be prevented from being interfered when the bed load is sampled, so that more accurate data can be acquired, and the acquisition efficiency of workers is improved.

The utility model discloses a bed load collecting device, which relates to the technical field of sediment testing and comprises a water tank, a gripping device mounting area is arranged on the side wall of the water tank, a gripping device and a visual identification mechanism are arranged on the gripping device mounting area, and the visual identification mechanism comprises a fixed light supplementing camera and a laser profile measuring head. The grabbing range of the grabbing device is located in the shooting range of the fixed light supplementing camera and the measuring range of the laser profile measuring head, and the volume, the approximate orientation and the approximate shape of the bed load can be calculated through a volumetric method according to images, shot by the fixed light supplementing camera, of the bed load. Then, the outline of the bed load is measured through the laser outline measuring head, so that the overall outline size and the accurate form of the bed load are obtained, accurate grabbing information is provided for the grabbing device, the grabbing precision is improved, and the defect that the size of the bed load is difficult to clearly know through a camera device in a sediment-carrying basin is overcome.

The invention discloses a pre-embedded bed load sediment transport rate measuring device based on sand wave motion, and the device comprises a measuring module which is used for measuring water pressure and sediment pressure; the pressure sensing module is used for measuring the sum of water pressure and sediment pressure above the inside of the riverbed; the water level measuring module is used for synchronously acquiring water level data; the central processing module is used for extracting sand wave elements including the sand wave height, the sand wave movement speed and the sand wave form coefficient and calculating the bed load sand transport rate; the data transmission module is used for transmitting the bed load sediment transport rate information to a remote terminal; the power supply module is used for supplying power to the pressure sensing module, the water level measuring module, the central processing module and the data transmission module. The method realizes real-time, interference-free and automatic monitoring of the bed load sediment transport rate, has the advantages of high precision, strong adaptability and the like, and is suitable for monitoring the shallow river bed load sediment transport rate.

The invention provides a sand blocking and guiding system and method for water power removal of a water inlet of a hydropower station, and relates to the technical field of water conservancy and hydropower engineering.The sand blocking and guiding system for water power removal of the water inlet of the hydropower station is applied to a power station, and the power station comprises a power station workshop and a drainage sand flushing gate which are arranged at intervals; the sand blocking and guiding system comprises a sand blocking ridge and a longitudinal guide wall, one end of the sand blocking ridge is used for being connected with a rock bank slope, the end, away from the rock bank slope, of the sand blocking ridge is connected with one end of the longitudinal guide wall, and the sand blocking ridge is configured to form an included angle with the main flow direction of a river channel; the end, away from the sand blocking ridge, of the longitudinal guide wall is used for being connected with the interval between the power station workshop and the drainage sand flushing gate, and the upstream face of the sand blocking ridge and the longitudinal guide wall form a flow guide channel used for guiding bed load silt. According to the invention, the bed load silt carried by the mainstream in the river channel at the upstream side of the water inlet of the power station workshop is automatically cleaned at low cost.

The invention discloses a method for determining the dredging opportunity of an upstream shoal of the Yangtze River, a terminal and a medium. The method comprises the following steps: acquiring historical dredging data of the upstream shoal of the Yangtze River; a three-dimensional water flow mathematical model control equation is established, a Van-Rijn sediment model is adopted to calculate the gravel bed load sediment transport rate, and a riverbed evolution model is obtained through visual solving; performing water flow motion characteristic verification on the obtained riverbed evolution model; carrying out dredging opportunity influence factor analysis, and carrying out water flow and siltation amount calculation by utilizing the verified riverbed evolution model; and constructing a dredging opportunity calculation model based on the time length required for dredging, the time length required from the current to dredging completion, and the time length required from the current to dredging starting, and calculating by using the dredging opportunity calculation model to obtain the optimal dredging opportunity of the dredging area. The dredging opportunity can be accurately calculated, the dredging construction efficiency is improved, and it is ensured that a channel is safe and unblocked.

The invention discloses a bed load section sediment transport rate modification method. The method comprises the following steps: calculating a plurality of measured bed load section sediment transport rates; calculating the bed load change section sediment transport rate of multiple times of measurement; based on the bed load actually-measured section sediment transport rate and the modified section sediment transport rate which are measured for multiple times, the correlation between the bed load actually-measured section sediment transport rate and the bed load modified section sediment transport rate is established and obtained; and based on the established relationship between the bed load actually measured section sediment transport rate and the modified section sediment transport rate, substituting the bed load actually measured section sediment transport rate of a certain measurement time to obtain the corresponding bed load calculated section sediment transport rate. According to the method, the bed load actually-measured section sediment transport rate is recalculated, the relation between the bed load actually-measured section sediment transport rate and the recalculated section sediment transport rate is established, the bed load recalculated section sediment transport rate is directly obtained, the actually-measured single-width sediment transport rates of all vertical lines of the bed load do not need to be recalculated one by one, the workload is greatly reduced, and the working time is greatly shortened.

The invention relates to an acoustic-seismic combined monitoring method and device for mountain river bed load, and the device comprises a sensing plate which bears the impact of river bed load particles, a seismic detector which collects a vibration signal, and a plurality of microphone elements which independently collect an acoustic signal. The method comprises the following steps of: extracting first-motion waves of a plurality of collected sound signals, passing through the amplitude of each node of a sensing plate, and generating a sound source intensity distribution image, thereby realizing the identification of the spatial position of a bed load on the sensing plate, and calculating a vibration signal wave packet through a system amplitude threshold value; constructing a correlation function to obtain the maximum positive amplitude of a vibration signal wave packet, calculating the particle size of bed load particles, correcting the eccentric error of the vibration signal, improving the recognition precision of the bed load particle size, and further calculating the sediment transport rate in real time. According to the method, the sound signal and the vibration signal are combined, the eccentricity error of the high-frequency geophone signal is recognized and corrected through the spatial position, the recognition precision of the grain size of the bed load is improved through the corrected geophone signal, and inversion calculation of the sediment transport rate is achieved.

The invention discloses a river basin sediment production estimation method based on a dynamic evolution process of a river-blocking barrier lake, and the method comprises the steps: carrying out the comparative analysis of key physicochemical characteristic parameters through an identification event layer in a residual barrier lake deposition sequence, and constructing a disaster chain extreme surface process river basin sediment production estimation method. Water level changes, hydrodynamic conditions and material source changes of the barrier lake are comprehensively analyzed, different sand production stages from the stable period, the decline period and the extinction period of the barrier lake are divided, the sediment change history from lacustrine facies suspended load to flood plain bed load is analyzed, and a complete barrier lake formation-evolution full life cycle evolution process mode is constructed. A layered triangular irregular network model is constructed to obtain layered accumulated sediment volume data, the layered volume and mass are calculated based on a dry density field of sedimentary stratification and spatial interpolation so as to calculate the total sediment yield, a physical information neural network model inverts a sedimentary thickness field, sediment yield estimation is achieved, and the non-stationary dynamic evolution characteristics of water and sediment of the barrier lake are quantified.

The invention relates to the technical field of hydraulics and river dynamics, and discloses a river channel scouring coarsening parameter determination method, device and equipment and a storage medium, in the calculation process, the target water flow condition is determined by adjusting the initial parameter, and the dynamic change of the water flow condition in the actual scouring process can be reflected. Furthermore, relevant parameters under different particle sizes can be accurately estimated through a dichotomy and a linear interpolation method, so that relatively accurate initial accumulative gradation is obtained. Furthermore, a bed sand gradation coarsening calculation method in the preset bed load scouring process is utilized to adjust the initial accumulative gradation, and the influence of the bed load on the bed sand gradation in the scouring process is considered, so that the calculation result is more in line with the bed sand change condition in the actual scouring process. Finally, the target river channel scouring coarsening parameter set is determined by comparing the target accumulative gradation with the preset threshold value, the accuracy of river channel scouring coarsening calculation is remarkably improved, and errors in actual engineering are reduced.

The invention discloses a double-layer back-silting observation device for collecting suspended load and bed load, which is placed in a river channel and comprises a first back-silting box for recycling suspended load and a second back-silting box for recycling bed load, the first back-silting box is arranged above the second back-silting box, and the second back-silting box is arranged above the first back-silting box. Collecting openings are formed in the top of the first back-silting box and the top of the second back-silting box, and the first back-silting box and the second back-silting box are connected through a connecting piece, so that a flowing gap allowing bed load and water to flow is formed between the first back-silting box and the second back-silting box. By the adoption of the technical scheme, suspended load is collected through the first back-silting box, flowing of bed load and water is facilitated through the flowing gap, so that the bed load is conveniently collected through the second back-silting box, the first back-silting box and the second back-silting box are matched, the bed load and the suspended load are collected at the same time, and the collecting efficiency is improved; meanwhile, the suspended load and the bed load are collected at the same position, so that the observation precision can be improved.

This invention discloses a sediment trap to prevent siltation at the tailrace outlet of a hydropower station. It is installed in the river channel at the confluence of the power station's tailrace outlet and the riverbed, and includes an arc-shaped transition section and a straight wall section. The upstream end of the arc-shaped transition section smoothly connects to the upstream bank wall of the river, and the downstream end smoothly connects to the straight wall section. The straight wall section extends along the river's flow direction and stands vertically in the river channel at the confluence of the power station's tailrace outlet and the riverbed. A tailrace flow passage is reserved between the downstream end of the straight wall section and the bank wall. The overall length of the sediment trap is determined based on the overall length L4 of the power station's tailrace outlet. The vertical distances between the starting end and the downstream end of the straight wall section and the power station's tailrace outlet are L1 and L2, respectively. The cross-sectional length of the tailrace flow passage reserved between the downstream end of the straight wall section and the bank wall is L3. By controlling the distances L1, L2, and L3, the impact of the sediment trap on the power station's tailrace elevation is minimized. This invention can prevent sediment from entering the power station's tailrace outlet and forming siltation, ensuring the normal operation of the power station.

The present invention discloses a real-time monitoring device and method for the pebble bedload sediment transport rate based on vibration signal processing. The device includes a vibration impact plate, an acceleration vibration sensor, a mounting base, a data collector, and a computer. The acceleration vibration sensor is fixedly mounted on the vibration impact plate, a groove is provided in the middle of the mounting base, the vibration impact plate covers and is fixed on the mounting base, and the side on which the acceleration vibration sensor is mounted faces downward so that the acceleration vibration sensor is placed in the groove space of the mounting base. The mounting base is fixed in the riverbed, and the installation elevation satisfies the requirement that the vibration impact plate is flush with the riverbed. The present invention installs the vibration sensor at the bottom center of the vibration impact plate flush with the riverbed surface, and infers the real-time bedload sediment transport rate by analyzing the vibration signal characteristics generated by the pebble bedload impacting the vibration impact plate. The present invention realizes accurate, effective, continuous, and real-time measurement of the pebble bedload sediment transport rate in a convenient and simple way.

The embodiment of the invention provides a method and device for determining riverbed coarsening level assignment, electronic equipment, a computer readable storage medium and a computer program product. The method for determining the layering of the riverbed coarsening layers comprises the following steps: acquiring an initial water and sediment condition of a target river reach; wherein the riverbed of the target river reach is a sand-doped pebble riverbed; based on the initial water and sediment conditions, by means of a preset riverbed coarsening layer gradation calculation rule, riverbed coarsening layer gradation when the target river reach reaches the limit scouring condition is determined; wherein the limit scouring condition is that the sediment scouring thickness and the sediment deposition thickness of the riverbed reach dynamic balance; and pushing the riverbed coarsening level to a user terminal. By means of the method, the response relation between riverbed scouring coarsening and conversion of bed sand, bed load and suspended load can be represented, and the calculation precision of the natural wide grading riverbed is improved.

This item is a bed load detector that is placed between the legs of a bed and the floor to detect the load applied to the bed.

The invention belongs to the field of hydraulics and river dynamics, and discloses a river bed load sediment transport rate prediction method under the effect of submerged vegetation, which comprises the following steps: firstly determining river near-bottom turbulent kinetic energy under the effect of submerged vegetation, carrying out dimensionless treatment on the river near-bottom turbulent kinetic energy, and then determining a river bed load sediment transport rate prediction model under the effect of submerged vegetation. The method can efficiently and accurately predict the sediment transport rate of the river bed load under the action of submerged vegetation, and provides a theoretical basis for further research on sediment movement characteristics and riverbed evolution rules involved in natural rivers and wetlands with submerged vegetation.

The debris flow river plugging coefficient calculation method provided by the invention comprises the following steps: collecting basic data, and calculating a primary debris flow rushing-out total volume; in the circulation area movement stage, the debris flow is divided into thin debris flow and viscous debris flow, the viscous debris flow is divided into a dragon head part and a dragon body part, the movement speed of the dragon head part and the movement speed of the dragon body part are calculated respectively, and the debris flow entering and converging main river volume is obtained; in the main river entering and converging stage, the debris flow accumulation body volume and the main river bed load sediment transport rate are expressed as a function of the maximum length of the accumulation body, and a sediment transport continuity equation is established according to the fact that the difference between the debris flow entering and converging main river total volume and the main river bed load sediment transport total volume is equal to the debris flow accumulation body volume; and obtaining a function relationship between the maximum length of the accumulation body and debris flow convergence time through iterative calculation, stopping iteration until the total volume of debris flow convergence into the main river is equal to the total volume of primary debris flow rushing out, and calculating a debris flow river plugging coefficient according to the maximum length of the accumulation body when the iteration is stopped. The method is high in physical generalization and high in calculation efficiency.

The invention provides a debris flow sediment transport ratio calculation method, which comprises the following steps: collecting basic data, and calculating a primary debris flow rushing-out total volume; in the circulation area movement stage, the debris flow is divided into thin debris flow and viscous debris flow, the viscous debris flow is divided into a dragon head part and a dragon body part, the movement speed of the dragon head part and the movement speed of the dragon body part are calculated respectively, and the debris flow entering and converging main river volume is obtained; in the main river entering and converging stage, a sediment transportation continuity equation is established according to the fact that the difference between the debris flow entering and converging main river volume and the main river bed load sediment transportation volume is equal to the debris flow accumulation body volume, and the relation between the maximum length of the accumulation body and debris flow entering and converging time is obtained through iterative calculation; in the scouring stage, the maximum length of the accumulation body when debris flow stops entering and converging and the shear stress of the main riverbed surface serve as initial values, and the shear stress of the main riverbed surface at different moments and the volume of the debris flow accumulation body when scouring stops are obtained through iterative calculation; and calculating the debris flow sediment transport ratio according to the volume and the primary debris flow rushing-out total volume. The method is high in physical generalization.

The application provides a method, device and equipment for the coordinated control of channel scouring and evolution, and a storage medium. The method comprises the following steps: first, calculating a correlation coefficient according to a sediment transport potential field and a water depth change, and entering the next step if the verification fails; then, calculating a grouped and ungrouped sediment transport rate according to a real-time particle size distribution, and determining that the gradation is abnormal if the deviation is large. At the same time, the spatial graph convolution topography weight is corrected based on the maximum particle size ratio, the modified eddy viscosity coefficient is determined, the weight coefficient of the bed load is updated, and finally, the multi-physical field coupling model is updated by using the coefficients, so that the prediction accuracy of the channel scouring is improved.

The application discloses a kind of water structure over-flow surface assembly type resistance large particle push sediment scour protection layer and construction method, belong to water construction technical field;A kind of water structure over-flow surface assembly type resistance large particle push sediment scour protection layer includes: the finishing pit formed in the position being destroyed, anchor rod fixed in finishing pit, the reinforced composite base layer formed in finishing pit, and the protection panel of covering integral surface, with anchor rod assembly connection.This application proposes assembly type composite connection system and corresponding structure design, construction method;By introducing rigid mechanical anchoring, constructing reinforced composite base layer, realizing modular assembly, the core problems such as connection unreliable, weak interface existing, maintenance difficult in prior art are systematically solved.

The invention relates to the technical field of bed load sediment transport tests, in particular to an intermittent sampling device suitable for bed load sediment transport tests, which comprises a plurality of temporary bed load storage cavities, a plurality of plug valves, two transmission gears, a driving rack, a driving gear, a self-locking motor and a control circuit, the plug valve is installed and arranged according to a specific mode, the transmission gear is connected with a plug body of the plug valve, the self-locking motor drives the driving gear, the driving rack is meshed with related gears, the control circuit controls the self-locking motor to rotate, and the specific composition of the control circuit, the connecting mode of all parts and the like are designed in detail. The technical effect that intermittent sampling in the bed load sediment transport test can be achieved is achieved, and effective equipment support is provided for sediment test sampling work.

The application discloses a kind of based on Doppler flow velocity profiler multilayer sediment sound signal attenuation correction's bed load sediment transport rate measurement method, comprising: in the floodplain area of the river reach to be measured, the bed surface of sediment is sampled, and the bed material gradation is measured, and the median size of bed sand is obtained;Obtain flow data, and extract ship speed data from flow data;According to ship speed data, calculate riverbed movement speed;Filter riverbed movement speed data, and calculate the eigenvalue of filtered riverbed movement speed data;According to the eigenvalue of filtered riverbed movement speed data, respectively calculate bed load vertical projection area ratio;According to bed sand median size, calculate dimensionless sediment particle size;According to dimensionless sediment particle size, calculate bed load layer thickness;According to bed load vertical projection area ratio and bed load layer thickness, calculate bed load volume concentration;According to bed load volume concentration, calculate multilayer sediment sound signal attenuation correction coefficient;According to multilayer sediment sound signal attenuation correction coefficient, calculate bed load sediment transport rate.The application accurately and effectively measures bed load sediment transport rate.

This invention proposes a method for simulating bed load stratification and zoning in a moving-bed physical model of a mountain river. The method includes: sampling the bottom sediment of the simulated river section, classifying the sediment types, and stratifying and zoning the bottom sediment distribution; calculating representative gradations for each type of sediment, classifying the sediment components, and calculating the proportions of each component; constructing a formula for calculating sediment similarity scales, calculating the particle size of model sand for each component, and preparing model sand for each type of sediment; constructing a physical model, laying pre-prepared model sand according to the sediment type in each layer, and conducting moving-bed tests for verification. This method achieves accurate simulation of bed load movement under complex bed conditions in mountain rivers, effectively solving the challenges of model sand selection, model sand laying, and accurate bed load simulation in moving-bed physical models, and enriching and developing moving-bed physical model design methods.

The invention relates to the field of river research, in particular to a bed load sediment transport rate measurer based on river channel desilting, which comprises a fixed cylinder, the inner cylinder is connected in the fixed cylinder; an inner cylinder is connected in the fixed cylinder; the inner cylinder is detachably connected with a plurality of spring telescopic rods; all the spring telescopic rods are jointly and fixedly connected with a collecting hopper, and the collecting hopper slides in the inner cylinder. When bed load falls into the collecting hopper, air in the air storage cavity is pressed into the annular cavity through the one-way valve of the vent hole along with downward movement of the collecting hopper, so that the pressure in the annular cavity is continuously increased, and when the pressure reaches a set threshold value of the pressure valve, the pressure valve is instantly opened, so that high-pressure air in the annular cavity enters the annular pipe from the pressure valve; and then the leaves are sprayed to the filter screen from the spray head, so that the leaves covering the filter screen are blown away and washed away along with water flow, and the filter screen is dredged regularly through pressurized air flow.

The utility model relates to a buoyancy anti-rotation switch mechanism of a riverbed material sampler, which comprises an anti-rotation structure fixed on a turntable and a clamping head in selective anti-rotation fit with the anti-rotation structure, the clamping head is assembled on the upper side of a shaft sleeve in a floating manner, a hinge seat and a switch piece are arranged on the shaft sleeve, and the switch piece comprises a buoy and a pressing rod connected with the buoy. The pressing rod is hinged to the hinge seat, the end, away from the buoy, of the pressing rod is arranged on the clamping head in a pressed mode, the buoy can swing upwards under the buoyancy effect of water and press the clamping head downwards, and the buoy swings downwards by means of gravity and releases the clamping head after the buoyancy disappears. After the whole riverbed material sampler enters water along with the lead fish, the tail of the buoy in the switch piece can be lifted, the pressing rod can be pressed downwards, the clamping head is clamped into the anti-rotation structure, at the moment, the rotating disc cannot rotate, and normal work of the sampler is guaranteed. After the fish lead flows out of water, the tail of the buoy falls down, the pressing rod is lifted up, the clamping head bounces upwards and is separated from the clamping groove of the anti-rotation structure, at the moment, the rotating disc can rotate, and the purpose of switching the samplers is achieved.

The invention provides a slope sediment starting flow velocity and bed load sediment transport rate prediction method and a model building method, and belongs to the technical field of hydraulics and river dynamics in natural science research. The method comprises the following steps: firstly, determining an acting force of sediment on a slope and an expression of the acting force, establishing a stress balance equation of sediment particles in a critical state, and introducing the force expression to obtain a slope sediment starting velocity initial expression; replacing the near-bottom flow velocity in the sediment starting critical flow velocity formula with the vertical line average flow velocity to obtain a slope sediment starting flow velocity prediction formula; parameters are determined according to an open channel sediment critical initial movement flow velocity measurement experiment, fixed parameters of a prediction formula are obtained, and meanwhile, a bed load sediment transport rate expression is established for prediction. According to the method, a sediment starting flow velocity formula which has simple and easily-obtained parameters and is suitable for a slope, a gentle slope and a flat bed is established, the model also comprises the prediction of the sediment transport rate, and the result also has relatively high reliability.