Sediment erodibility testing apparatus and method based on binocular vision measurement technology

Abstract

A sediment erodibility testing apparatus and method based on binocular vision measurement technology. The testing apparatus comprises: a pipeline system, comprising a water storage tank (1), a water inlet pipeline (5), a transparent horizontal pipeline (8) and a water outlet pipeline (16) which are connected in sequence and form a circulation loop; a flow velocity adjustment system, arranged on the pipeline system and used for adjusting water flow velocity and internal pipeline pressure intensity; a sample pushing system, comprising a sample cylinder (21) used for containing a sediment sample (22) to be tested, and a piston (20) baseplate mounted in the sample cylinder (21) and capable of moving up and down, wherein an upper opening of the sample cylinder (21) is connected to the lower surface of the transparent horizontal pipeline (8); and a binocular vision measurement system, comprising a binocular camera (13) located directly above the sample cylinder (21), and a laser emitter (12) located beside the binocular camera (13) and used for projecting speckles onto the surface of a soil sample to be tested.

Description

A sediment erodibility test device and method based on binocular vision measurement technology Technical Field

[0001] The invention belongs to the technical field of sediment scouring performance research, and relates to a sediment erodibility test device and method based on binocular vision measurement technology. Background Art

[0002] Sediment scour is closely related to soil erosion, riverbed and seabed evolution, and pollutant dispersion, posing a serious threat to the normal operation and structural safety of water conservancy and infrastructure projects. Sediment scour characteristics are influenced by both the dynamic conditions of the water flow and the physical and chemical properties of the sediment. Understanding the mechanisms and patterns of sediment scour is crucial for guiding engineering practice.

[0003] For a long time, the prediction of sediment scour has focused on the study of river hydrodynamics. In recent years, the study and understanding of sediment characteristics have gradually received attention. How to quantitatively measure the scour characteristics of sediment is a key issue that must be addressed. Existing sediment scour test devices include annular flumes, open channel flumes, rotary sediment scour devices, jet sediment scour devices, and tubular sediment scour flumes, each with its own advantages, disadvantages, and applicability. The common problem that all types of test devices need to solve is the measurement of scour sediment, and this invention is proposed based on this.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a sediment erodibility test device and method based on binocular vision measurement technology, which can effectively test the sediment erosion characteristics and observe its surface morphology evolution, with high test accuracy and good test effect.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] In one aspect, the present invention provides a sediment erodibility test device based on binocular vision measurement technology, comprising:

[0008] A piping system comprising a water storage tank, a water inlet pipe, a transparent horizontal pipe and a water outlet pipe which are sequentially connected to form a circulation;

[0009] A flow rate regulating system, which is provided on the piping system and is used to regulate the water flow rate and the pressure inside the pipe;

[0010] The sample pushing system includes a sample cylinder for containing the sediment sample to be tested, and a piston base installed in the sample cylinder and movable up and down. The upper opening of the sample cylinder is connected to the lower surface of the transparent horizontal pipe, so that the space inside the sample cylinder is connected to the inner cavity of the transparent horizontal pipe;

[0011] The binocular vision measurement system includes a binocular camera located directly above the sample tube, and a laser emitter located next to the binocular camera and used for projecting speckles on the surface of the soil sample to be measured.

[0012] Furthermore, the water inlet pipe and the transparent horizontal pipe are transitionally connected by a first variable-section joint, and the transparent horizontal pipe and the water outlet pipe are transitionally connected by a second variable-section joint;

[0013] Along the water flow direction, the inner diameter of the first variable-section joint gradually decreases, and the inner diameter of the second variable-section joint gradually increases.

[0014] Furthermore, the cross-section of the transparent horizontal pipe is rectangular and is made of organic glass.

[0015] Furthermore, a plurality of pressure gauges are arranged on the upper surface of the transparent horizontal pipe, wherein at least two pressure gauges are arranged in front of the measuring area where the sample cylinder is located, and at least one pressure gauge is arranged behind the measuring area where the sample cylinder is located.

[0016] Furthermore, the flow rate regulation system includes a water inlet pump, a water pump speed regulator and an electromagnetic flowmeter arranged on the water inlet pipe, and a control valve installed on the water outlet pipe.

[0017] Furthermore, the top surface of the sample tube is flush with the inner bottom surface of the transparent horizontal pipe.

[0018] Furthermore, the piston base plate is controllably connected to a servo motor via a screw lifting mechanism.

[0019] Furthermore, the binocular vision measurement system also includes a computer, which is also connected to the binocular camera and the laser emitter.

[0020] Furthermore, the axis of the binocular camera is at 90° to the surface of the sediment sample being measured.

[0021] On the other hand, the present invention also provides a sediment erodibility test method based on binocular vision measurement technology, which is based on any of the sediment erodibility test devices described above, and the sediment erodibility test method comprises the following steps:

[0022] (1) Prepare the sediment sample to be tested in the sample tube, and adjust the height of the piston base plate so that the surface of the sediment sample to be tested in the sample tube is pushed up to be flush with the bottom of the transparent horizontal tube;

[0023] (2) Start water inlet to the pipeline system and control the flow rate so that the water slowly fills the transparent horizontal tube. After the water is filled, turn on the laser transmitter and binocular camera to determine the test area;

[0024] (3) Adjust the water flow rate in the piping system from the low flow rate main supplement to the test set value and keep it constant. Read the flow rate value as the actual average flow rate through the transparent horizontal tube test area and calculate the bed shear stress.

[0025] (4) The piston base is controlled to push the sediment sample to 1 mm above the bottom of the transparent horizontal pipe, and images of the sediment sample surface are collected during the scouring process. After the scouring process stabilizes, the scouring rate test and scouring morphology observations are repeated at different flow rates.

[0026] (5) Obtain a three-dimensional morphological map of the sediment scouring process and calculate the scouring rate under different water flow rates.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The device of the present invention has an ingenious structure, dynamic water circulation during the test process, good integrity and high efficiency.

[0029] 2. The present invention has a high degree of automation. It can accurately control the displacement of the piston base plate, allowing the sample to be freely raised and lowered; and the flow rate in the pipeline can be adjusted by setting the frequency converter value.

[0030] 3. The pipe wall friction characteristics and the water pressure at the sediment sample can be obtained through the pressure gauge.

[0031] 4. Binocular vision technology can obtain real-time three-dimensional topography of the sediment surface in the test area to evaluate sediment movement patterns and calculate sediment scour rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic structural diagram of a device of the present invention;

[0033] Figure 2 is a schematic structural diagram of the sample pushing system;

[0034] Figure 3 is a schematic diagram of a variable cross-section joint;

[0035] FIG4 is a flow chart of a sediment erodibility study based on the present invention;

[0036] Figure 5 shows the laser speckle patterns on the surface of the sediment sample to be tested and before and after scouring, a) sample surface; b) laser speckle pattern before scouring; c) laser speckle pattern after scouring.

[0037] Figure 6 shows the three-dimensional morphology of the sample surface and the scouring amount calculated based on binocular vision technology, a) the three-dimensional morphology of the sample surface after scouring; b) the calculated scouring amount.

[0038] Explanation of the markings in the figure: 1-water storage tank; 2-flow guide pipe; 3-water pump speed regulator; 4-water inlet pump; 5-water inlet pipe; 6-electromagnetic flowmeter; 7-variable cross-section joint; 8-transparent horizontal pipe; 9-first pressure gauge; 10-second pressure gauge; 11-third pressure gauge; 12-laser transmitter; 13-binocular camera; 14-camera bracket; 15-control valve; 16-water outlet pipe; 17-servo motor; 18-motor speed regulator; 19-screw lifting mechanism; 20-piston; 21-soil sample cylinder; 22-sediment sample to be tested; 23-fixed bracket; 24-computer. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0040] In the following implementation manners or examples, unless otherwise specified, functional components or structures are conventional components or conventional structures used in the art to achieve corresponding functions.

[0041] In order to effectively test the scouring characteristics of sediment and observe its surface morphology evolution, the present invention provides a sediment erodibility test device based on binocular vision measurement technology. The structure of the device is shown in Figures 1 to 3, etc., and includes:

[0042] A piping system comprising a water storage tank, a water inlet pipe, a transparent horizontal pipe and a water outlet pipe which are sequentially connected to form a circulation;

[0043] A flow rate regulating system, which is provided on the piping system and is used to regulate the water flow rate and the pressure inside the pipe;

[0044] The sample pushing system includes a sample cylinder for containing the sediment sample to be tested, and a piston base installed in the sample cylinder and movable up and down. The upper opening of the sample cylinder is connected to the lower surface of the transparent horizontal pipe, so that the space inside the sample cylinder is connected to the inner cavity of the transparent horizontal pipe;

[0045] The binocular vision measurement system includes a binocular camera located directly above the sample tube (for collecting pictures and recording the test process), and a laser emitter located next to the binocular camera and used to project speckles on the surface of the soil sample being tested.

[0046] In some specific embodiments, please refer to FIG. 3 , etc., the water inlet pipe and the transparent horizontal pipe are connected by a first variable-section joint, and the transparent horizontal pipe and the water outlet pipe are connected by a second variable-section joint.

[0047] Along the water flow direction, the inner diameter of the first variable-section joint gradually decreases, while the inner diameter of the second variable-section joint gradually increases. The purpose of setting up variable-section joints in this way is to: reduce the inner diameter of the joint at the water inlet, and the smooth internal structure can calm the water flow, reduce the generation of bubbles, and prevent excessive bubbles from obscuring scattered spots on the surface of the measured object, thereby reducing errors; increase the inner diameter of the joint at the water outlet, and the smooth internal structure can accelerate the discharge of measured sediment and avoid backflow of washed sediment.

[0048] In some specific embodiments, the cross-section of the transparent horizontal pipe is rectangular and is made of organic glass.

[0049] In some specific embodiments, the upper surface of the transparent horizontal pipe is further provided with several pressure gauges. At least two pressure gauges are located in front of the measurement area where the sample cartridge is located, for measuring the pressure differential of the water flowing within the transparent pipe. At least one pressure gauge is located behind the measurement area where the sample cartridge is located, for measuring the pressure differential of the water flowing before and after passing through the sample. It is generally desired that the water flow at the pressure gauges in front of the measurement area is not affected by the sample range.

[0050] In some specific embodiments, the flow rate regulation system includes a water inlet pump, a water pump speed regulator and an electromagnetic flowmeter arranged on the water inlet pipe, and a control valve installed on the water outlet pipe.

[0051] In some specific embodiments, the top surface of the sample cylinder is flush with the inner bottom surface of the transparent horizontal channel.

[0052] In some specific embodiments, the piston base plate is controllably connected to a servo motor via a screw lifting mechanism.

[0053] In some specific embodiments, the binocular vision measurement system further includes a computer, which is further connected to the binocular camera and the laser emitter.

[0054] In some specific embodiments, the axis of the binocular camera is at 90 degrees to the surface of the sediment sample being measured. Generally, it is required that the spots projected by the laser emitter cover the surface of the object being measured and are clearly visible when photographed by the camera.

[0055] In addition, the present invention also provides a sediment erodibility test method based on binocular vision measurement technology, which is based on the sediment erodibility test device described above, and the sediment erodibility test method includes the following steps:

[0056] (1) Prepare the sediment sample to be tested in the sample tube, and adjust the height of the piston base plate so that the surface of the sediment sample to be tested in the sample tube is pushed up to be flush with the bottom of the transparent horizontal tube;

[0057] (2) Start water inlet to the pipeline system and control the flow rate so that the water slowly fills the transparent horizontal tube. After the water is filled, turn on the laser transmitter and binocular camera to determine the test area;

[0058] (3) Adjust the water flow rate in the piping system from the low flow rate main supplement to the test set value and keep it constant. Read the flow rate value as the actual average flow rate through the transparent horizontal tube test area and calculate the bed shear stress.

[0059] (4) The piston base is controlled to push the sediment sample to 1 mm above the bottom of the transparent horizontal pipe, and images of the sediment sample surface are collected during the scouring process. After the scouring process stabilizes, the scouring rate test and scouring morphology observations are repeated at different flow rates.

[0060] (5) Obtain a three-dimensional morphological map of the sediment scouring process and calculate the scouring rate under different water flow rates.

[0061] The above embodiments may be implemented individually or in any combination of two or more.

[0062] The above implementation is described in more detail below with reference to specific examples.

[0063] Example 1:

[0064] To effectively test sediment scouring characteristics and observe the evolution of its surface morphology, this embodiment provides a sediment erodibility test device based on binocular vision measurement technology. The structure of the device is shown in Figures 1 to 3, etc., and includes:

[0065] A piping system comprising a water storage tank, a water inlet pipe, a transparent horizontal pipe and a water outlet pipe which are sequentially connected to form a circulation;

[0066] A flow rate regulating system, which is provided on the piping system and is used to regulate the water flow rate and the pressure inside the pipe;

[0067] The sample pushing system includes a sample cylinder for containing the sediment sample to be tested, and a piston base installed in the sample cylinder and movable up and down. The upper opening of the sample cylinder is connected to the lower surface of the transparent horizontal pipe, so that the space inside the sample cylinder is connected to the inner cavity of the transparent horizontal pipe;

[0068] The binocular vision measurement system includes a binocular camera located directly above the sample tube (for collecting pictures and recording the test process), and a laser emitter located next to the binocular camera and used to project speckles on the surface of the soil sample being tested.

[0069] 3 , the water inlet pipe and the transparent horizontal pipe are connected by a first variable cross-section joint, and the transparent horizontal pipe and the water outlet pipe are connected by a second variable cross-section joint.

[0070] Along the water flow direction, the inner diameter of the first variable-section joint gradually decreases, while the inner diameter of the second variable-section joint gradually increases. The purpose of setting up variable-section joints in this way is to: reduce the inner diameter of the joint at the water inlet, and the smooth internal structure can calm the water flow, reduce the generation of bubbles, and prevent excessive bubbles from obscuring scattered spots on the surface of the measured object, thereby reducing errors; increase the inner diameter of the joint at the water outlet, and the smooth internal structure can accelerate the discharge of measured sediment and avoid backflow of washed sediment.

[0071] The cross section of the transparent horizontal pipe is rectangular and is made of organic glass.

[0072] The upper surface of the transparent horizontal pipe is also equipped with several pressure gauges. At least two are located in front of the measurement area where the sample tube is located, used to measure the pressure difference of the water flow within the transparent pipe. At least one is located behind the measurement area where the sample tube is located, used to measure the pressure difference before and after the water flows through the sample. The water pressure in the test area is generally required to be unaffected by the sample range at the pressure gauge in front of the measurement area.

[0073] Please refer to FIG. 1 again, the flow rate regulating system includes a water inlet pump, a water pump speed regulator and an electromagnetic flowmeter arranged on the water inlet pipe, and a control valve installed on the water outlet pipe.

[0074] The top surface of the sample cylinder is flush with the inner bottom surface of the transparent horizontal pipe.

[0075] Please refer to Figure 2 again. The piston base is controlled by a servo motor through a screw lifting mechanism. The screw lifting mechanism here is used to drive the piston base up and down through the servo motor to control the upper surface of the sample to be flush with the water tank floor or other preset positions.

[0076] The binocular vision measurement system also includes a computer, which is connected to the binocular camera and the laser emitter. The binocular camera's axis is at a 90-degree angle to the surface of the sediment sample being measured. It is generally required that the spots projected by the laser emitter cover the entire surface of the measured object and be clearly visible when captured by the camera.

[0077] Example 2:

[0078] Based on the sediment erodibility test device of Example 1, this example provides a test method for studying sediment scour characteristics based on binocular vision technology. Scour tests were conducted on sand and clay, respectively, as shown in Figure 4. The optical measurement method used was the three-dimensional digital speckle correlation method, and the sediment scour test was conducted using the laser speckle method. The sample surface image and the laser speckle pattern before and after scour are shown in Figure 5 (spray speckle was used for comparison during the period, and the results showed that the two speckle patterns had the same effect, so laser speckle was used in subsequent experiments).

[0079] The specific steps are as follows:

[0080] (1) Before the test begins, prepare the test soil sample according to the volume of the sampling container, turn on the power of the device, and confirm that the water pump speed regulator, electromagnetic flowmeter, motor speed regulator, laser transmitter and binocular camera are working properly.

[0081] (2) The binocular camera is fixed to the horizontal beam of the tripod, with the camera axis approximately 90° to the sediment surface. The laser emitter is adjusted so that the speckle pattern is clear and the test area is fully displayed. A black and white checkerboard pattern is used as a calibration template for the binocular camera. The Zhang calibration method is used to determine the intrinsic parameters of each camera and the extrinsic parameters between cameras. The camera is then recalibrated using the Camera Calibration Toolbox in Matlab to improve the accuracy of the 3D reconstruction. After successful calibration, the experiment begins.

[0082] During the test, the inlet pump was started. The pump speed regulator and control valve were combined to set a specific flow rate according to the test plan. Water was then pumped into a rectangular, transparent horizontal tube. After the flow stabilized, the electromagnetic flowmeter readings were taken three times. The average value was taken as the actual average flow rate in the flume, which was used to estimate the bed shear stress.

[0083] The water flow velocity through the transparent horizontal tube test area is recorded by an electromagnetic flowmeter, and the bed shear stress is calculated according to formula (1):

[0084] Where, τ b is the shear stress; ρ is the density of water; U is the average flow velocity, and f is the friction coefficient, which can be obtained from the Moody diagram based on the surface roughness of the soil sample and the Reynolds number of the water flow in the flume.

[0085] (3) Start the laser transmitter and binocular camera to start collecting images of the sediment surface during the scouring process to monitor the sediment movement pattern and calculate the sediment scouring rate.

[0086] Set the parameters of the motor speed regulator, control the servo motor, drive the screw lifting mechanism and push the piston base plate, push the sediment sample to be tested into the transparent horizontal tube at the set rate, push the sediment sample to 1mm above the bottom of the transparent horizontal tube, maintain a constant flow rate, and observe the scouring development process.

[0087] (4) Change the water flow rate, readjust the sediment surface to be approximately flush and 1 mm above the bottom of the transparent horizontal tube, and obtain new test data.

[0088] After the test, turn off the water pump speed regulator, electromagnetic flowmeter, motor speed regulator, laser transmitter and binocular camera, remove the remaining sediment in the soil sample tube, and clean the water tank.

[0089] After image matching and 3D reconstruction based on the 3D topography images before and after sediment scouring, the instantaneous elevation z at the initial time t of the pixel point is obtained. t (j) and the instantaneous elevation z at any time t+dt t+dt (j) After that, the elevation change of the pixel point is Δz (j) =z t+dt (j) -z t (j) (j=1, ..., n). Then according to the known metric length dimension Δx of the pixel (j) and Δy (j) , we can get the flushing volume difference ΔV of each pixel (j) =Δz (j) Δx (j) Δy (j) The flushing volume difference of each pixel point is summed to obtain the volume difference ΔV of the object before and after flushing.

[0090] The sediment scouring rate is calculated according to formula (2):

[0091] Where E is the scouring rate, unit is kg / (m 2 ·s); ΔV is the volume of sediment washed, unit is m 3 ; S is the cross-sectional area of ​​the sample, in m 2 ; Δt is the flushing time, in seconds; ρ d is the dry density of sediment, in kg / m 3 .

[0092] By processing the speckle information in the surface images of the soil sample before and after scouring, a three-dimensional reconstruction of the soil sample surface morphology is obtained, as shown in Figure 6(a). The surface morphology of the soil sample before and after scouring is compared, and the difference is calculated, as shown in Figure 6(b). The volume difference of the soil sample before and after scouring is further calculated, and the corresponding scouring rate can be calculated using Equation (2).

[0093] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A sediment erodibility test device based on binocular vision measurement technology, characterized in that: include: A piping system comprising a water storage tank, a water inlet pipe, a transparent horizontal pipe and a water outlet pipe which are sequentially connected to form a circulation; A flow rate regulating system, which is provided on the piping system and is used to regulate the water flow rate and the pressure inside the pipe; The sample pushing system includes a sample cylinder for containing the sediment sample to be tested, and a piston base installed in the sample cylinder and movable up and down. The upper opening of the sample cylinder is connected to the lower surface of the transparent horizontal pipe, so that the space inside the sample cylinder is connected to the inner cavity of the transparent horizontal pipe; The binocular vision measurement system includes a binocular camera located directly above the sample tube, and a laser emitter located next to the binocular camera and used for projecting speckles on the surface of the soil sample to be measured.

2. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The water inlet pipe and the transparent horizontal pipe are connected by a first variable cross-section joint, and the transparent horizontal pipe and the water outlet pipe are connected by a second variable cross-section joint; Along the water flow direction, the inner diameter of the first variable-section joint gradually decreases, and the inner diameter of the second variable-section joint gradually increases.

3. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The cross section of the transparent horizontal pipe is rectangular and is made of organic glass.

4. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: Several pressure gauges are also arranged on the upper surface of the transparent horizontal pipe, wherein at least two are located in front of the measuring area where the sample cylinder is located, and at least one is located behind the measuring area where the sample cylinder is located.

5. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The flow rate regulating system includes a water inlet pump, a water pump speed regulator and an electromagnetic flowmeter arranged on the water inlet pipe, and a control valve installed on the water outlet pipe.

6. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The top surface of the sample cylinder is flush with the inner bottom surface of the transparent horizontal pipe.

7. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The piston bottom plate is controllably connected to a servo motor via a screw rod lifting mechanism.

8. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The binocular vision measurement system also includes a computer, which is also connected to the binocular camera and the laser emitter.

9. The sediment erodibility test device based on binocular vision measurement technology according to claim 1 is characterized in that: The axis of the binocular camera is at 90° to the surface of the sediment sample being measured.

10. A sediment erodibility test method based on binocular vision measurement technology, which is based on the sediment erodibility test device according to any one of claims 1 to 9, characterized in that: The sediment erodibility test method comprises the following steps: (1) Prepare the sediment sample to be tested in the sample tube, and adjust the height of the piston base plate so that the surface of the sediment sample to be tested in the sample tube is pushed up to be flush with the bottom of the transparent horizontal tube; (2) Start water inlet to the pipeline system and control the flow rate so that the water slowly fills the transparent horizontal tube. After the water is filled, turn on the laser transmitter and binocular camera to determine the test area; (3) Adjust the water flow rate in the piping system from the low flow rate main supplement to the test set value and keep it constant. Read the flow rate value as the actual average flow rate through the transparent horizontal tube test area and calculate the bed shear stress. (4) The piston base is controlled to push the sediment sample to 1 mm above the bottom of the transparent horizontal pipe, and images of the sediment sample surface are collected during the scouring process. After the scouring process stabilizes, the scouring rate test and scouring morphology observations are repeated at different flow rates. (5) Obtain a three-dimensional morphological map of the sediment scouring process and calculate the scouring rate under different water flow rates.

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