A solid-liquid separation and grading weighing device, a visual particle migration geotechnical hydraulic test device and a dynamic compensation method for weighing

Abstract

This invention discloses a solid-liquid separation and grading weighing device, a visualized particle transport geohydraulic test device, and a weighing dynamic compensation method. The device includes a rotating grading collection structure for rapid solid-liquid separation. Particles are graded and retained according to particle size on a multi-layer grading metal filter screen and weighed in real time. The weighing dynamic compensation method is based on the collaborative measurement of a single-point weighing sensor and an IMU. It decomposes the total dynamic force into material gravity, unbalanced centrifugal force, and structural vibration inertial force. Through frequency domain analysis and iterative calculation, interference components are deducted and attitude correction is performed. A dynamic compensation model related to rotational speed is introduced to establish a functional relationship between the integer average force and particle mass. Thus, particle grading mass-time curves and particle size evolution information are obtained under continuous flow, rotation, and vibration conditions. It is applicable to geohydraulic test scenarios such as seepage erosion tests, reverse filter layer scouring tests, sand-laden water flow erosion tests, filter backwashing tests, and pipeline scouring tests.

Description

Technical Field

[0001] This invention relates to the field of solid-liquid two-phase flow measurement and geohydraulic testing technology, specifically to a device for rapid solid-liquid separation and real-time graded weighing in geohydraulic testing, a geohydraulic testing device for visualized particle transport based on the device, and a dynamic weighing compensation method. Background Technology

[0002] In geotechnical structures such as dams, cofferdams, roadbeds, and foundations, internal erosion, piping, and seepage deformation are important modes leading to instability and failure. In filter layers, infiltration ditches, and drainage systems, the penetration and scouring of fine particles weaken the protective effect of the filter. Near bridge piers, revetments, and riverbeds, local scouring caused by sediment-laden water flow may expose the foundation and reduce safety reserves. In water supply, drainage, and water treatment engineering, filters require backwashing after long-term operation to remove particles clogging the filter layer and restore permeability. In urban drainage networks and manholes, the formation and scouring process of sediment directly affects the operational safety and maintenance costs of the drainage system. A common feature of these conditions is the presence of a solid-liquid two-phase flow containing particles downstream. In engineering practice, it is typically necessary to obtain the loss rate, cumulative loss, and particle size evolution over time for particles of various sizes to determine the critical conditions for internal erosion, scouring intensity, and the self-healing and instability processes of the structure.

[0003] In existing geohydraulic tests, downstream particle collection often employs methods such as flow-stopping and cup replacement or online weighing combined with offline sieving. Flow-stopping and cup replacement requires intermittently shutting off the water source or switching pipelines to change the collection container or filter, inevitably disturbing the upstream seepage field and scouring process. Furthermore, it only obtains cumulative mass data at a few discrete moments, making it difficult to reflect the continuous evolution of erosion and scouring. While online weighing combined with offline sieving can record the total mass change in real time, particle size information needs to be obtained through centralized sieving after the test. It lacks high-temporal-resolution real-time fractional mass-time curves, making it impossible to identify key moments such as "which particle size initiates the erosion, when it accelerates its loss, and when it stabilizes."

[0004] On the other hand, in tests such as seepage erosion, sand-laden water scouring, and filtration backwashing, the downstream discharge is often a solid-liquid two-phase mixture with large fluctuations in instantaneous flow rate and particle concentration. To avoid interference from the liquid mass on the weighing reading, solid-liquid separation is usually required first; however, the dewatering efficiency of traditional static filters or fixed sand collection hoppers is limited, and phenomena such as short-term submersion of the filter layer, water bridging, and liquid bridges are prone to occur, introducing additional weight errors. To improve dewatering efficiency, some devices introduce rotating or vibrating structures, but at this time the weighing unit is in a dynamic operating condition, and the reading is mixed with the unbalanced centrifugal force generated by the eccentric mass and the inertial force caused by mechanical vibration, resulting in violent fluctuations in the weighing signal, making it difficult to achieve stable and reliable online weighing under continuous flow conditions.

[0005] Few existing technologies can simultaneously meet the following requirements under continuous flow conditions: achieving rapid and effective solid-liquid separation of solid-liquid two-phase flow; real-time classification and collection of particles of different sizes and weighing them separately; and dynamic compensation and mass inversion of the eccentric centrifugal force and structural vibration inertial force contained in the weighing signal under rotation or vibration conditions, so as to obtain high-precision classification mass-time curves and particle size evolution information.

[0006] Therefore, there is a need to develop a device that is compact in structure, can be used as a downstream standard module for various types of geohydraulic tests, can achieve rapid solid-liquid separation and real-time graded weighing, and is equipped with a reliable dynamic weighing compensation method. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the prior art by providing a solid-liquid separation and grading weighing device, a visual particle transport geohydraulic test device, and a weighing dynamic compensation method.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A solid-liquid separation and grading weighing device is installed downstream of the sample in a geohydraulic test system. It is used to perform rapid solid-liquid separation, particle grading, and real-time weighing of the solid-liquid two-phase flow ejected from the sample. The device includes: a housing, a rotary drive assembly located below the housing, and a grading collection and weighing assembly located inside the housing. The grading collection and weighing assembly is connected to and supported on the rotary drive assembly. The graded collection and weighing assembly includes multiple graded filter cylinders nested from top to bottom along the axial direction. The bottom of each graded filter cylinder is provided with a graded metal filter screen and a rigid filter screen base plate. The mesh size of the multiple graded metal filter screens increases from top to bottom. The multiple graded metal filter screens are used to intercept solid particles according to particle size and achieve simultaneous dehydration. The graded filter cylinder is provided with an annular bypass and flow guiding assembly to guide solid particles to slowly rotate into the graded metal filter screen below and discharge liquid. The device housing is also provided with a water outlet. It also includes sensor and power interface components, including at least a single-point weighing sensor arranged on or below the grading collection and weighing component, and an inertial measurement unit installed on the grading collection and weighing component. The single-point weighing sensor is used to measure the total force signal including the material gravity, unbalanced centrifugal force and structural vibration inertial force. The inertial measurement unit is used to synchronously acquire the angular position information, angular velocity information and vertical acceleration of the grading filter cartridge under rotation conditions, providing a data basis for dynamic weighing compensation.

[0009] Furthermore, the rotary drive assembly includes a drive motor disposed at the bottom of the device housing, a connector and a rotating shaft connected to the output end of the drive motor, a turntable mounted on the rotating shaft, and a bearing seat and a seal for supporting and sealing the rotating shaft. The turntable connects to and carries the grading collection and weighing assembly.

[0010] Furthermore, the multi-layered grading funnels are multiple conical or frustum-shaped funnels arranged sequentially along the axial direction. The upper ends of the multi-layered grading funnels are connected together by connectors. The outermost or bottommost grading funnel is detachably mounted on the rotary drive assembly. The annular bypass and guide assembly also includes guide vanes and overflow grooves disposed on the peripheral wall of the grading funnels, as well as an overflow weir for suppressing liquid splashing and backflow, so that the liquid is preferentially thrown out under centrifugal force and collects along the inner wall of the device housing, and discharged through the outlet.

[0011] Furthermore, the inner wall of the grading filter cylinder, the grading metal filter screen, and the rigid filter screen base plate are respectively provided with superhydrophobic coatings to reduce the influence of water retention and liquid bridge effects on the weighing readings; the connection between the device housing and the external water supply and drainage pipes adopts a flexible connection structure with a hose and a vibration damping bracket to isolate the interference of pipe traction force and external mechanical vibration on the weighing measurement.

[0012] A visual particle transport geohydraulic testing device includes a soil sample testing unit, a water supply system, a pressure gauge, and a solid-liquid separation and grading weighing device as described above. The soil sample testing unit is one or more of a transparent soil column, a permeameter, a local scour model box, or a filter / reverse filtration model box. The downstream outlet of the soil sample testing unit is connected to the inlet of the solid-liquid separation and grading weighing device via a pipeline. The water supply system is connected to the upstream inlet of the soil sample testing unit. The pressure gauge is located upstream and downstream of the soil sample testing unit to measure the pressure difference during seepage or scour. During the test, the solid and liquid phases flushed out of the soil sample testing unit flow through the solid-liquid separation and grading weighing device to achieve clear liquid bypass discharge and particle grading and retention, which is then weighed in real time.

[0013] Furthermore, it also includes a visualization optical system and a computer. The visualization optical system includes a laser arranged on one side of the soil sample test unit and a high-speed camera on the other side. The high-speed camera is used to acquire images and quantitatively visualize the process of particle initiation, migration, channel formation and expansion. The high-speed camera, the pressure gauge, the single-point weighing sensor, the inertial measurement unit and the water supply system are electrically connected to the computer for unified control and acquisition of output signals.

[0014] A dynamic compensation method for weighing in a geohydraulic test device for visualizing particle transport, the dynamic compensation method comprising the following steps: The single-point weighing sensor measures the original total force signal. F total Establish the total force decomposition relationship: F total =F soil +F u +F iner , In the formula, F soil The initial value of the weight of the material to be determined is 0. F u This is the component of the unbalanced centrifugal force caused by the eccentric mass in the weighing direction; F iner It is the inertial force generated in the vertical direction by mechanical vibration; The unbalanced vibration is fitted using the least squares method to obtain... F u : , , , , In the formula, A and B both represent the fitting coefficients, and t represents time. i This indicates the angle between the vertical direction and the normal to the plane of rotation. Inertial force F iner The quest for: Instantaneous acceleration in the vertical direction detected by the inertial measurement unit a z (t) Let the total mass participating in the vibration at the moment be... m total Then the inertial force satisfies: F iner (t)=m total ⋅a z (t) ; Solving for the target gravitational component and material mass: Based on the results of the above steps, the effective gravity component of the target material is calculated: F soil =F total-F u -F iner , The mass of the particulate material is then determined based on the relationship between gravity and mass. m soil , , In the formula, m soil To determine the target material mass (target particle mass). gcosθ The effective component of gravitational acceleration along the weighing axis is obtained by attitude correction based on the attitude angle measured by the inertial measurement unit. During the experiment, the above calculation is iteratively updated according to the time step, i.e., updated... m total And repeat the calculation F u , F iner and F soil This allows the measured total dynamic force under rotation and vibration conditions to be restored to the static gravity of the material and the mass of the material to be obtained.

[0015] Furthermore, when the graded collection and weighing component includes multiple particle size levels or multiple radial regions, the gravity of each particle size level is transmitted to a single-point weighing sensor through a multi-point force transmission structure, and the dynamic compensation and mass inversion processing in the above steps are performed on the force signals corresponding to each size level to obtain the mass-time curve of each particle size level, which is used to characterize the graded erosion or scour rate and particle size evolution characteristics during the geohydraulic test.

[0016] Furthermore, it also includes the relationship with rotational speed. oh Related efficiency coefficients a(w) and no-load bias b(ω) After averaging the force signal over an entire revolution, the average force after eccentric force compensation, inertial force compensation, and attitude correction is denoted as... F Average force throughout the week F With particle mass m The following conditions must be met: F=α(ω)·R·m+ β(ω) , In the formula, R The equivalent radius of action, a(w) and b(ω) During the device calibration phase, experimental data under known mass and different rotation speed conditions are used to determine the particle mass inversion results for calibration correction during operation.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through the above-mentioned structural design, this solid-liquid separation and grading weighing device can rapidly separate the solid and liquid two-phase fluids added to the device, grade particles of different sizes, and weigh the separated solid particles for subsequent experimental analysis; 2. Through multiple rotatable grading funnels and grading metal filters at the bottom, this device achieves integrated "solid-liquid separation + particle size grading + dehydration" under the combined action of centrifugal force and gravity, continuously obtaining particles of coarse / medium / fine sizes. Combined with dynamic compensation methods, it can invert the real-time particle size distribution and identify "which particle size group starts / destabilizes first", making up for the shortcomings of traditional offline screening, which can only provide the final state gradation and lack time sequence information; 3. This device and method can continuously measure without interrupting the flow and without disturbing the upstream seepage field: the device can operate in a continuous flow state. It achieves rapid solid-liquid separation and weighing without stopping the pump to change cups or manually emptying the material; combined with whole-cycle synchronous averaging and frequency notch filtering, it obtains smooth and reliable weighing results within the constant speed window, ensuring continuous recording of the seepage-erosion process and particle loss process; 4. Adjustable parameters and strong adaptability: the size of the annular overflow channel, the number and angle of the guide vanes, the mesh size and number of layers of the filter screen, the weighing range and the working speed can all be quickly calibrated and modularly replaced according to the sample size, flow range and particle size distribution, and can be used in various geohydraulic test scenarios such as internal erosion of dams / foundations, reverse filtration scouring, local scouring of bridge piers, backwashing of filter beds and erosion by sand-laden water flow; 5. High dynamic compensation accuracy: based on the joint measurement of "weighing sensor + IMU", this invention proposes an algorithm flow that decomposes the dynamic total force into particle gravity, unbalanced centrifugal force and structural vibration inertial force, and introduces attitude correction and speed-related calibration models. F=α(ω)·R·m+ β(ω) Under continuous flow and rotation conditions, it can automatically deduct the effects of eccentricity and vibration, and reliably restore the measured dynamic total force to the equivalent static gravity and true mass, which is significantly better than the traditional weighing method that relies solely on low-pass filtering or static calibration; 6. Detailed and complete data: Under a unified time reference, downstream graded mass-time curves and upstream and downstream head difference data are collected synchronously. Based on the high-precision mass information after dynamic compensation, key nodes such as internal erosion criticality, formation and expansion of connecting channels, self-healing and re-blockage can be quantitatively determined, providing highly timely and reliable experimental basis for the study of solid-liquid two-phase flow measurement mechanism and the verification of numerical models and empirical formulas. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a solid-liquid separation and grading weighing device according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the annular overflow groove and guide vanes on the graded filter cartridge of the present invention; Figure 3 This is a schematic diagram of a geohydraulic test device for visualizing particle transport in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the dynamic compensation for vibration and eccentric swaying in this invention.

[0019] In the diagram: 1. Single-point weighing sensor; 2. Inertial measurement unit; 3. Pulley; 4. Shaft; 5. Connector; 6. Grading funnel; 7. Guide vanes and overflow trough; 8. Grading metal filter screen; 9. Rigid funnel base plate; 10. Rotating shaft; 11. Water outlet; 12. Device housing; 13. Pump; 14. Liquid tank; 15. Laser; 16. Soil sample testing unit; 17. Liquid collection container; 18. Computer; 19. High-speed camera; 20. Particle loss photograph recording module; 21. Pressure gauge. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] A device for rapid solid-liquid separation and real-time grading and weighing in geohydraulic testing includes a rotary drive assembly, an annular bypass and flow guiding assembly, a grading collection and weighing assembly, and a sensor and power interface assembly. The device is located downstream of the sample in the geohydraulic testing system and is used to perform rapid solid-liquid separation, particle grading, and real-time weighing of the solid-liquid two-phase flow ejected from the sample. The rotary drive assembly includes a drive motor for providing torque and achieving steady speed control, a rotating shaft and a connecting component connected to the output end of the drive motor, a turntable mounted on the rotating shaft, and a bearing seat and a seal for supporting and sealing the rotating shaft. The turntable is used to carry the grading collection and weighing assembly. The annular bypass and guide assembly is located upstream of the graded collection and weighing assembly. It includes an annular overflow trough arranged around the rotating shaft, a bypass drain port and pipe joint communicating with the annular overflow trough, guide vanes arranged inside or below the annular overflow trough to guide solid particles to slowly swirl into the well, and an overflow weir to suppress liquid splashing and backflow. This allows the liquid in the solid-liquid two-phase flow entering the device to be preferentially discharged through the annular overflow trough and bypass drain port, while the solid particles are guided along the guide vanes to the lower well or weighing cup (graded metal filter screen). The graded collection and weighing assembly includes multiple layers of graded metal filters arranged sequentially along the axial direction with increasing mesh size from top to bottom, a rigid strainer base plate located below the bottom graded metal filter, and a connecting structure for fixing the graded metal filters and strainer base plate as a whole onto the turntable. The multiple layers of graded metal filters are used to intercept solid particles according to particle size and achieve synchronous dehydration. The sensor and power interface assembly includes a single-point weighing sensor arranged below the turntable or on its support frame, an inertial measurement unit (IMU) installed on the graded collection and weighing assembly or its housing, a data acquisition and processing module electrically connected to the single-point weighing sensor and the IMU, a communication module, etc., as well as a battery and power filtering circuit for powering the above components. The single-point weighing sensor is used to measure the total force signal, including the weight of the material, the unbalanced centrifugal force, and the structural vibration inertial force. The IMU is used to synchronously acquire the angular position information, angular velocity information, and vertical acceleration of the device under rotational conditions, providing a data basis for dynamic weighing compensation.

[0023] Example 1: A solid-liquid separation and grading weighing device is provided, such as... Figure 1 As shown, it includes: a device housing 12, a rotary drive assembly located below the device housing 12, a grading collection and weighing assembly located inside the device housing 12, and the grading collection and weighing assembly being connected to and supported on the rotary drive assembly; The graded collection and weighing assembly includes multiple graded filter cylinders 6 nested from top to bottom along the axial direction. The bottom of each graded filter cylinder 6 is provided with a graded metal filter screen 8 and a rigid filter screen base plate 9. There is a receiving space between the graded metal filter screen 8 and the rigid filter screen base plate 9. The mesh size of the multiple graded metal filter screens 8 increases from top to bottom. The multiple graded metal filter screens 8 are used to intercept solid particles according to particle size and achieve synchronous dehydration. The graded filter cylinder 6 is provided with an annular bypass and flow guiding assembly to guide solid particles to slowly rotate into the graded metal filter screen below and discharge liquid. The device housing 12 is also provided with a water outlet 11. It also includes sensor and power interface components, including at least a single-point weighing sensor 1 arranged on or below the graded collection and weighing component, and an inertial measurement unit 2 (IMU) installed on the graded collection and weighing component.

[0024] This solid-liquid separation and grading weighing device, through the above-described structure, can rapidly separate solid and liquid two-phase fluids added to the device, grade particles of different sizes, and weigh the separated solid particles for subsequent experimental analysis.

[0025] This device integrates solid-liquid separation, particle size classification, and dehydration through a multi-layered rotatable classifying funnel 6 and a classifying metal filter 8 at its bottom, under the combined action of centrifugal force and gravity. It continuously obtains particles of coarse, medium, and fine particle sizes, and can retrieve the real-time particle size distribution in subsequent analysis.

[0026] This device can also perform continuous measurements without interrupting the flow and without disturbing the upstream seepage field: the device can complete rapid solid-liquid separation and weighing without interrupting the flow, without stopping the pump to change the cup or manually pouring the material. It is simple and convenient to operate and use, and it is also conducive to the conduct of geohydraulic tests on particle transport.

[0027] Furthermore, the rotary drive assembly includes a drive motor disposed at the bottom of the device housing 12, a connector and a rotating shaft 10 connected to the output end of the drive motor, a turntable mounted on the rotating shaft 10, and a bearing seat and a seal for supporting and sealing the rotating shaft 10. The turntable connects to and carries the grading collection and weighing assembly.

[0028] The drive motor can be installed inside the base of the device housing. The drive motor drives the rotating shaft 10 to rotate, and the rotating shaft 10 drives the grading collection and weighing assembly installed above it to rotate, that is, the grading funnel 6 to rotate.

[0029] In this embodiment, the drive motor is connected to the rotating shaft 10 through components such as pulley 3 and belt 4, and is used to provide torque and realize the steady rotation of the grading filter. The belt 4 transmits the power of pulley 3 to the turntable on the rotating shaft, thereby driving the upper grading structure to rotate as a whole.

[0030] Furthermore, the multi-layered grading cylinders 6 are multiple conical or frustum-shaped cylinders arranged sequentially along the axial direction. The upper ends of the multi-layered grading cylinders 6 are connected together by connectors 5. The outermost or lowermost grading cylinder 6 is detachably mounted on the turntable of the rotary drive assembly. The annular bypass and guide assembly also includes guide vanes and overflow grooves 7 disposed on the peripheral wall of the grading cylinders 6, as well as an overflow weir for suppressing liquid splashing and backflow, so that the liquid is preferentially thrown out under centrifugal force and collects along the inner wall of the device housing 12, and discharged through the outlet 11.

[0031] The multiple grading funnels 6 are arranged in ascending order of size, with the smaller ones nested inside the larger ones, and there is a certain gap between them to allow the liquid and particles separated from the upper stage to fall down. The upper surfaces of the multiple grading funnels 6 can be connected together by connectors 5 such as buckles or radial connecting rods with connecting holes to form an integral structure so that they can be installed together on the turntable.

[0032] In some implementations, such as Figure 2 As shown, the bottom of each layer of the grading filter cylinder 6 has sieve holes of different particle sizes, which are the grading metal filter screen 6 (or grading metal mesh bag). The outer edge of the side wall is processed into the shape of guide vanes to enhance the radial migration and grading effect of solid particles. Guide vanes and overflow grooves 7 are arranged above each grading filter cylinder 6. The overflow grooves form an annular bypass channel, so that the liquid is preferentially thrown out under centrifugal force and collects along the inner wall of the device shell, and is discharged through the outlet 11, thereby realizing rapid solid-liquid separation.

[0033] Below each grading funnel 6, there are grading metal filter screens 8 of different particle sizes and a rigid funnel base plate 9 (rigid metal mesh bag) at the bottom, which are matched with the particle size of each layer. This is used to trap particles according to particle size and achieve further dehydration. The grading metal filter screen 8 can form an axial floating support structure with the rigid funnel base plate 9 through rigid buckles, which takes into account both convenient disassembly and assembly and stable force transmission. The bottom of the grading funnel 6 and the grading metal filter screen 8 can form a structure similar to a sinkhole or weighing cup, which can carry particles and measure them. The bottom rigid funnel base plate can be used to bear the overall stiffness and uniformly transfer the gravity of each grading layer to the single-point weighing sensor below.

[0034] With the above structure, the solid-liquid two-phase flow entering the device is rapidly bypassed and discharged through the guide vanes and annular overflow groove under the combined action of centrifugation and gravity. The solid particles enter the stage-by-stage funnels 6 in sequence and are deposited in the corresponding metal mesh bags according to their particle size, thereby achieving rapid solid-liquid separation and real-time graded collection under continuous flow conditions.

[0035] In some implementations, each stage of the grading funnel and its bottom metal mesh bag can be made into a detachable unit module (containing features such as guide vanes and overflow grooves). The number of unit modules is determined by the number of stages required. They are assembled into the device housing and connected to the turntable below. The unit modules can be connected to each other or to the turntable using snap-fit ​​or connecting lugs with screw holes.

[0036] Furthermore, the grading filter cylinder 6, the grading metal filter screen 8, and the rigid filter screen base plate 9 are preferably made of stainless steel, with an aperture or mesh size ranging from 20 to 150 mesh, increasing from top to bottom. The overflow trough is preferably 6 mm wide, with a weir height of approximately 8 mm, and the guide vanes are a certain number of pieces, approximately 0.5 mm thick, with an inclination angle of 10° relative to the horizontal, to balance dewatering efficiency and stable particle introduction. The above dimensional parameters can be adjusted according to experimental needs.

[0037] Furthermore, the inner wall of the grading filter cylinder 6, the grading metal filter screen 8, and the rigid filter screen base plate 9 are respectively provided with superhydrophobic coatings to reduce the influence of water hanging and liquid bridge effects on the weighing readings; the connection between the device housing 12 and the external water supply pipe and drainage pipe adopts a flexible connection structure with a hose and a vibration damping bracket to isolate the interference of pipe traction force and external mechanical vibration on the weighing measurement.

[0038] Furthermore, the single-point weighing sensor 1 is installed on the turntable and / or in the accommodating space below the grading filter cylinder 6, and is used to measure the total force signal including the material gravity, unbalanced centrifugal force and structural vibration inertial force. The inertial measurement unit 2 is installed on the turntable, the grading filter cylinder 6 or in the accommodating space, and is used to synchronously acquire the angular position information, angular velocity information and vertical acceleration of the grading filter cylinder under rotation conditions, so as to provide a data basis for dynamic weighing compensation.

[0039] The single-point weighing sensor 1 can be set on the turntable or at the bottom of the entire grading filter cylinder to bear the weight of the entire grading structure and the particles therein, and output the total force signal; the single-point weighing sensor 1 can also be installed at the bottom of each grading filter cylinder, that is, in the space between the grading metal filter and the rigid filter bottom plate, to obtain the weight and force data of each level of particles, or to obtain the total force data.

[0040] Similarly, the IMU (Inertial Measurement Unit) 2 can also be installed on the turntable, the bottom of the classifying filter cylinder, or its side wall, capable of simultaneously acquiring the angular position, angular velocity, and vertical acceleration data of the classifying filter cylinder under rotational conditions. The single-point weighing sensor 1 and the inertial measurement unit 2 can each have a built-in battery and wireless communication unit to wirelessly transmit data to the data acquisition and processing module; alternatively, they can be electrically connected to the data acquisition and processing module via high-quality conductive slip ring channels.

[0041] Example 2: A visual particle transport geohydraulic test device is provided, including a soil sample test unit, a water supply system, a pressure gauge, and a solid-liquid separation and grading weighing device as described in Example 1; wherein, the soil sample test unit 16 is one or more of a transparent soil sample column, a permeameter, a local scour model box, or a filter / reverse filter model box, the downstream outlet of the soil sample test unit 16 is connected to the inlet of the solid-liquid separation and grading weighing device through a pipeline, the water supply system is connected to the upstream inlet of the soil sample test unit, the pressure gauge 21 is set at the upstream and downstream positions of the soil sample test unit, and is used to measure the pressure difference during the seepage or scour process, during the test, the solid and liquid two-phase flow flushed out of the soil sample test unit is discharged by bypass and the particles are graded and intercepted by the solid-liquid separation and grading weighing device and weighed in real time.

[0042] Furthermore, it also includes a visualization optical system and a computer 18. The visualization optical system includes a laser 15 arranged on one side of the soil sample test unit 16 and a high-speed camera 19 on the other side. The high-speed camera 19 is used to acquire images and quantitatively visualize the process of particle initiation, migration, channel formation and expansion. The high-speed camera 19, the pressure gauge 21, the single-point weighing sensor 1, the inertial measurement unit 2 and the water supply system are respectively electrically connected to the computer 18 for unified control and acquisition of output signals.

[0043] Specifically, such as Figure 3 As shown, it includes a water supply system containing a pump 13 and a liquid tank 14, a laser 15, a soil sample test unit 16 (the test specimen), a solid-liquid separation and grading weighing device (with graded metal filters of different pore sizes arranged sequentially inside) located at the downstream outlet of the soil sample test unit 16, a liquid collection container 17, a computer 18, a high-speed camera 19, a particle loss photograph recording module 20, and a pressure gauge 21 (such as a water pressure gauge).

[0044] The pump 13 is connected to the liquid tank 14 and can continuously deliver the test liquid in the liquid tank 14 to the soil sample test unit 16 at a set flow rate to provide stable and controllable seepage or scouring conditions for the sample. The liquid tank 14 is used to store the test liquid and fine particles or tracers can be added to it as needed.

[0045] The soil sample test unit 16 is preferably a soil sample column or model box made of transparent material, which is filled with the soil or particulate medium to be studied. The upstream inlet of the soil sample test unit 16 is connected to the outlet of the pump 13 through a pipeline, and the downstream outlet is connected to the inlet of the solid-liquid separation and grading weighing device through a hose, so that the particles that are eroded or washed down in the sample and the liquid enter the downstream grading funnel together.

[0046] Under the combined action of centrifugal force and gravity, the liquid in the solid-liquid two-phase flow entering the device is rapidly ejected and introduced into the liquid collection container 17, while the solid particles are sequentially classified and dehydrated by screens of different apertures and corresponding metal mesh bags according to particle size. The solid-liquid separation and classification weighing device is equipped with a single-point weighing sensor 1 and an IMU (Inertial Measurement Unit) to measure the total force signal, angular velocity, attitude angle, and vertical acceleration signal of the classification structure during rotation, thereby achieving real-time inversion and dynamic compensation of particle mass. The liquid collection container 17 is located below the device outlet 11 to collect the clarified liquid for subsequent volume measurement or water sample analysis.

[0047] To enable visual observation of particle migration processes within the sample, the laser 15 is positioned on one side of the soil sample test unit 16 and fixed by a bracket. Its output end is equipped with a broadening optical element to broaden the laser beam into a thinner laser sheet that illuminates a specific cross-section inside the soil sample test unit 16. The high-speed camera 19 is positioned on the other side of the sample, aimed at the plane of the laser sheet, with its lens centered on the central region of the soil sample test unit 16. Under laser illumination, the particle outlines within this cross-section of the soil sample test unit 16 are highlighted. The high-speed camera 19 continuously acquires images at a high frame rate, enabling quantitative and visual recording of processes such as particle initiation, migration, channel formation, and expansion.

[0048] The pressure gauge 21 is connected to the upstream and / or downstream water head measuring point of the soil sample test unit 16 through a pressure guide tube, and is used to measure the water head difference or local pressure change at both ends of the sample. The electrical signal output terminal of the pressure gauge 21 is connected to the computer 18.

[0049] Computer 18 has built-in data acquisition and image processing software, which can perform background removal, time averaging, and binarization processing on the laser sheet images inside the sample acquired by high-speed camera 19. It can also record and analyze the seepage pressure data obtained by pressure gauge 21, and call the weighing dynamic compensation algorithm to process the total force signal output by the grading collection device, and invert to obtain the mass-time curves of particles of different sizes. The particle loss photo recording module 20 can be a sequence of close-up images of the outlet area captured by high-speed camera 19, or it can be an independent image storage device, used to visually record the morphological characteristics of lost particles at different time periods.

[0050] The experimental apparatus described in this embodiment utilizes an optical visualization system comprised of a laser 15 and a high-speed camera 19. This system allows for real-time observation of particle transport and erosion morphology within the soil sample test unit 16 without damaging the sample structure. Pressure gauges 21 positioned upstream and downstream of the sample simultaneously monitor the evolution of seepage pressure differentials. Furthermore, the rotary solid-liquid separation and grading weighing device, with its grading metal meshes of varying apertures and grading weighing system, enables real-time acquisition of mass-time curves for each particle size loss without interrupting flow. The overall experimental apparatus is simple in structure and easy to operate. It can simultaneously acquire three types of information: internal morphology, hydraulic response, and downstream grading mass. The displayed results are intuitive and clear, and the test repeatability is excellent. It is particularly suitable for studying the mechanisms of geohydraulic problems such as internal erosion, localized scour, and filter clogging / restoration.

[0051] Furthermore, to facilitate subsequent dynamic compensation and mass inversion by the computer, the computer 18 synchronously acquires and resamples signals from the single-point weighing sensor and the IMU: using the rotation period of the graded collection device as the time window, the original total force time series output by the single-point weighing sensor is segmented and averaged in integer cycles to obtain the total force with respect to the rotation angle or time. F total(t) Simultaneously, the angular velocity, attitude angle, and vertical acceleration output by the IMU at the corresponding moment are recorded, providing basic data for subsequent calculation of eccentric centrifugal force and inertial force.

[0052] Example 3: A method for conducting experiments and performing data processing and dynamic weighing compensation using the visualization particle transport geohydraulic test device in Example 2 is provided, including the following steps.

[0053] After the experiment, the computer 9 processed the acquired weighing and IMU signals as follows to achieve dynamic compensation and mass inversion.

[0054] (1) Decomposition of the original total force The original total force time series measured by the single-point weighing sensor is denoted as: F total By segmenting the rotation into integer periods and resampling by time or angle, the force signal within each rotation cycle is unified into the angle domain, establishing the total force decomposition relationship: F total =F soil +F u +F iner , In the formula, F soil The initial value is 0, representing the weight (target quantity) of the material to be determined. F uThis is the component of the unbalanced centrifugal force caused by the eccentric mass in the weighing direction; F iner It is the inertial force generated in the vertical direction by mechanical vibration.

[0055] (2) Determine the vertical component of the eccentric / unbalanced centrifugal force F u like Figure 4 As shown, the drive motor is not perfectly balanced or has eccentric mass. m u It generates centrifugal force when it rotates around its axis, resulting in an eccentric mass. m u Unmeasurable. Measurement is performed by attaching an IMU sensor to the outer shell of the grading funnel. i Based on the Fourier transform principle, trigonometric functions are designed as the basic functions. By using the least squares method and FFT analysis, the dominant frequency and vibration amplitude of the eccentric sway can be obtained, and the equivalent [symmetric value] can be derived. F u : , , , , In the formula, t represents time. i The angle between the vertical direction and the normal to the plane of rotation (attitude angle) is represented by A and B, which are both fitting coefficients. For example, when using Fourier functions to describe a curve, the signal is decomposed into a series of linear combinations of sine and cosine functions to achieve fitting. A and B are the fitting coefficients. These fitting coefficients can be accurately calculated by integral formulas or estimated from discrete data points by numerical methods (such as the least squares method).

[0056] (3) Inertial force F iner The pursuit Instantaneous acceleration in the vertical direction detected by the inertial measurement unit a z (t) Let the total mass participating in the vibration at the moment be... m total (Including the weight of the tiered collection structure, the mass of the sensor, and the particle mass obtained from the previous time step iteration), the inertial force satisfies: F iner (t)=m total ⋅a z (t)。

[0057] (4) Solving for the target gravity component and material mass Based on the results of the above steps, the effective gravity component of the target material is calculated by successively subtracting the unbalanced centrifugal force and inertial force: F soil =F total -F u -F iner , Based on the attitude angle output by the IMU, calculate the effective component of gravity along the weighing axis over a certain period of time. g· cosθ(t) Thus, the particle mass is obtained: , In the formula, m soil To determine the target material mass (target particle mass). gcosθ The effective component of gravitational acceleration along the weighing axis is obtained by attitude correction based on the attitude angle measured by the inertial measurement unit. During the experiment, the above calculation is iteratively updated according to the time step, i.e., updated... m total And repeat the calculation F u , F iner and F soil This allows the measured total dynamic force under rotation and vibration conditions to be restored to the static gravity of the material and the mass of the material to be obtained.

[0058] Furthermore, the measured total force signal and IMU signal are averaged or smoothed over a time window of one or several revolutions to suppress random noise and transient impacts. Then, the decomposition and compensation calculations described above are performed to improve the stability and accuracy of the dynamic weighing results.

[0059] Furthermore, when the graded collection and weighing component includes multiple particle size levels or multiple radial regions, the gravity of each particle size level is transmitted to a single-point weighing sensor through a multi-point force transmission structure, and the dynamic compensation and mass inversion processing in the above steps are performed on the force signals corresponding to each size level to obtain the mass-time curve of each particle size level, which is used to characterize the graded erosion or scour rate and particle size evolution characteristics during the geohydraulic test.

[0060] Furthermore, it also includes the relationship with rotational speed. oh Related efficiency coefficients a(w) and no-load bias b(ω) After averaging the force signal over an entire revolution, the average force after eccentric force compensation, inertial force compensation, and attitude correction is denoted as...F Average force throughout the week F With particle mass m The following conditions must be met: F=α(ω)·R·m+ β(ω) , In the formula, R The equivalent radius of action, a(w) and b(ω) During the device calibration phase, experimental data under known mass and different rotation speed conditions are used to determine the particle mass inversion results for calibration correction during operation.

[0061] This step is a correction of the rotational speed-related calibration model. The purpose is to eliminate background loads that are unrelated to mass but vary with rotational speed, and to absorb the influence of wet fluid action and force transmission efficiency on the measurement, thereby improving the accuracy of mass inversion under different rotational speed conditions.

[0062] Specifically, it includes the following processes: Step 1: No-load bias calibration. With the apparatus in a "particle-free" state, using the same medium and liquid level as the actual test, run the calibration at multiple speed settings. oh Run and record the average force over the whole week. F ,get b(ω) ; Step 2: Efficiency coefficient calibration. Under the same operating conditions, add a known mass... m j At each speed oh collection F First deduct β (oh) The calculation was obtained by fitting a multi-mass × multi-speed matrix. a(w) .

[0063] , Step 3: Calculate the target value m. Real-time output of the mass m of each fractionated particle: , Through the above calculation steps, the true mass of particles at each time point can be reliably obtained from the dynamic total force measured by the weighing sensor under rotation and vibration conditions, thereby obtaining the mass-time curves and cumulative loss of particles of different grades.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A solid-liquid separation and classification weighing device, characterized in that, Located downstream of the sample in the geohydraulic testing system, this device is used for rapid solid-liquid separation, particle classification, and real-time weighing of the solid-liquid two-phase flow ejected from the sample. It includes: a device housing, a rotary drive assembly located below the device housing, and a classification collection and weighing assembly located inside the device housing. The classification collection and weighing assembly is connected to and supported on the rotary drive assembly. The graded collection and weighing assembly includes multiple graded filter cylinders nested from top to bottom along the axial direction. The bottom of each graded filter cylinder is provided with a graded metal filter screen and a rigid filter screen base plate. The mesh size of the multiple graded metal filter screens increases from top to bottom. The multiple graded metal filter screens are used to intercept solid particles according to particle size and achieve simultaneous dehydration. The graded filter cylinder is provided with an annular bypass and flow guiding assembly to guide solid particles to slowly rotate into the graded metal filter screen below and discharge liquid. The device housing is also provided with a water outlet. It also includes sensor and power interface components, including at least a single-point weighing sensor arranged on or below the grading collection and weighing component, and an inertial measurement unit installed on the grading collection and weighing component. The single-point weighing sensor is used to measure the total force signal including the material gravity, unbalanced centrifugal force and structural vibration inertial force. The inertial measurement unit is used to synchronously acquire the angular position information, angular velocity information and vertical acceleration of the grading filter cartridge under rotation conditions, providing a data basis for dynamic weighing compensation.

2. The solid-liquid separation and classification weighing device according to claim 1, characterized in that, The rotary drive assembly includes a drive motor disposed at the bottom of the device housing, a connector and a rotating shaft connected to the output end of the drive motor, a turntable mounted on the rotating shaft, and a bearing seat and a seal for supporting and sealing the rotating shaft. The turntable connects to and carries the grading collection and weighing assembly.

3. The solid-liquid separation and classification weighing device according to claim 1, characterized in that, The multi-layered grading funnel is a series of conical or frustum-shaped funnels arranged sequentially along the axial direction. The upper ends of the multi-layered grading funnels are connected together by connectors. The outermost or bottommost grading funnel is detachably mounted on the rotary drive assembly.

4. The solid-liquid separation and classification weighing device according to claim 1, characterized in that, The annular bypass and guide assembly also includes guide vanes and overflow grooves disposed on the peripheral wall of the staged funnel, as well as an overflow weir for suppressing liquid splashing and backflow, so that the liquid is preferentially thrown out under centrifugal force and collects along the inner wall of the device housing, and discharged through the outlet.

5. The solid-liquid separation and classification weighing device according to claim 1, characterized in that, The inner wall of the grading filter cylinder, the grading metal filter screen, and the rigid filter screen base plate are respectively provided with superhydrophobic coatings to reduce the influence of water hanging and liquid bridge effects on the weighing readings; the connection between the device housing and the external water supply and drainage pipes adopts a flexible connection structure with a hose and a vibration damping bracket to isolate the interference of pipe traction force and external mechanical vibration on the weighing measurement.

6. A geohydraulic test device for visualizing particle transport, characterized in that, The system includes a soil sample testing unit, a water supply system, a pressure gauge, and a solid-liquid separation and grading weighing device according to any one of claims 1-5; wherein, the soil sample testing unit is one or more of a transparent soil sample column, a permeameter, a local scour model box, or a filter / reverse filtration model box, the downstream outlet of the soil sample testing unit is connected to the inlet of the solid-liquid separation and grading weighing device through a pipeline, the water supply system is connected to the upstream inlet of the soil sample testing unit, the pressure gauge is set at the upstream and downstream positions of the soil sample testing unit to measure the pressure difference during seepage or scour, and during the test, the solid and liquid two-phase flow flushed out of the soil sample testing unit passes through the solid-liquid separation and grading weighing device to achieve clear liquid bypass discharge and particle grading and interception, and is weighed in real time.

7. The visualized particle transport geohydraulic testing device according to claim 6, characterized in that, It also includes a visualization optical system and a computer. The visualization optical system includes a laser arranged on one side of the soil sample test unit and a high-speed camera on the other side. The high-speed camera is used to acquire images and quantitatively visualize the process of particle initiation, migration, channel formation and expansion. The high-speed camera, the pressure gauge, the single-point weighing sensor, the inertial measurement unit and the water supply system are electrically connected to the computer for unified control and acquisition of output signals.

8. The weighing dynamic compensation method for the visual particle transport geohydraulic testing device according to claim 6 or 7, characterized in that, The dynamic compensation method for weighing includes the following steps: The single-point weighing sensor measures the original total force signal. F total Establish the total force decomposition relationship: F total =F soil +F u +F iner ， In the formula, F soil The initial value of the weight of the material to be determined is 0. F u This is the component of the unbalanced centrifugal force caused by the eccentric mass in the weighing direction; F iner It is the inertial force generated in the vertical direction by mechanical vibration; The unbalanced vibration is fitted using the least squares method to obtain... F u : ， ， ， ， In the formula, A and B both represent the fitting coefficients, and t represents time. θ This indicates the angle between the vertical direction and the normal to the plane of rotation. Inertial force F iner The quest for: Instantaneous acceleration in the vertical direction detected by the inertial measurement unit a z (t) Let the total mass participating in the vibration at the moment be... m total Then the inertial force satisfies: F iner (t)=m total ⋅a z (t) ; Solving for the target gravitational component and material mass: Based on the results of the above steps, the effective gravity component of the target material is calculated: F soil =F total -F u -F iner ， The mass of the particulate material is then determined based on the relationship between gravity and mass. m soil , ， In the formula, gcosθ The effective component of gravitational acceleration in the direction of the weighing axis is obtained by attitude correction based on the attitude angle measured by the inertial measurement unit. During the experiment, the above calculations are iteratively updated according to the time step, i.e., updated. m total And repeat the calculation F u , F iner and F soil This allows the measured total dynamic force under rotation and vibration conditions to be restored to the static gravity of the material and the mass of the material to be obtained.

9. The weighing dynamic compensation method for the visual particle transport geohydraulic test device according to claim 8, characterized in that, When the graded collection and weighing component includes multiple particle size levels or multiple radial regions, the gravity of each particle level is transmitted to a single-point weighing sensor through a multi-point force transmission structure. The dynamic compensation and mass inversion processing in the above steps are performed on the force signals corresponding to each level to obtain the mass-time curve of each particle size level, which is used to characterize the graded erosion or scour rate and particle size evolution characteristics during the geohydraulic test.

10. The dynamic weighing compensation method for the visualized particle transport geohydraulic testing device according to claim 8, characterized in that, Also includes rotational speed ω Related efficiency coefficients α(ω) and no-load bias β(ω) After averaging the force signal over an entire revolution, the average force after eccentric force compensation, inertial force compensation, and attitude correction is denoted as... F Average force throughout the week F With particle mass m The following conditions must be met: F = α(ω)·R·m + β(ω) ， In the formula, R The equivalent radius of action, α(ω) and β(ω) During the device calibration phase, experimental data under known mass and different rotation speed conditions are used to determine the particle mass inversion results for calibration correction during operation.

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