A flume test system and method for exploring the mechanism of wave-induced sediment resuspension

Abstract

The present invention provides a flume test system and method for exploring the mechanism of wave-induced sediment resuspension, including a flume component simulating an ocean flow environment, a seepage system, a wave power system, and a sediment resuspension monitoring system. The device can control the intensity of the two mechanisms of shear and liquefaction. The technical solution of the present invention solves the problem that the intensity of the two mechanisms cannot be independently distinguished and controlled in a traditional wave flume. The patent of the present invention takes into account the representative characteristic parameters of the shear and liquefaction mechanisms, and proposes a research method based on a reference concentration calculation formula to distinguish the contribution rate of different mechanisms to the overall sediment resuspension amount, and quantifies the contribution of different mechanisms to the sediment resuspension amount.

Description

Technical Field

[0001] The present invention relates to the field of marine sediment technology, and in particular to a water tank test system and method for exploring the mechanism of wave-induced sediment resuspension. Background Art

[0002] Sediment resuspension is one of the key processes of material transport in the ocean, affecting the change process of suspended sediment concentration in the water body. The change process of suspended sediment concentration and the law of sediment migration indicate different hydrodynamic environments, which are of great significance to the material circulation of land and ocean and shoreline erosion and deposition. Under the action of continuous waves, sediment resuspension is significantly affected by two mechanisms: liquefaction and shear. The periodic load of waves is divided into horizontal shear load and vertical load according to the direction of action. The horizontal shear load of waves directly acts on the surface sediments of the seabed to produce shear stress. When this shear stress exceeds the critical shear stress of the sediment, the stability between the sediment particles is destroyed, and the sediment begins to be restarted and suspended in the water. The vertical load of waves generates excess pore water pressure inside the seabed through compression. The gradual accumulation of excess pore water pressure will cause the effective stress between sediment particles to gradually decrease. When the effective stress drops to zero, the stiffness and bearing capacity of the seabed soil drop sharply, and the sediment liquefies. The fluidity of the liquefied soil increases significantly, providing favorable conditions for the resuspension of sediments. The shear and liquefaction processes under the action of waves do not exist in isolation during the sediment resuspension process, and the influencing process of the internal mechanism of sediment resuspension is also more complicated. Due to the differences in their physical properties, different soil types (sand, clay) under the same wave conditions have significantly different characteristics of sediment resuspension caused by shear damage and liquefaction of different degrees. Due to the complexity of the seabed environment and the relatively difficult and costly field observations, indoor experiments have become a necessary and effective means. Although existing technical invention patents can simulate the process of sediment resuspension caused by waves, they do not directly distinguish between the two mechanisms of shear and liquefaction in terms of experimental equipment and methods.

[0003] Traditional rectangular flumes can simulate the action of waves to cause water oscillation and affect the response of bottom sediments, such as the patent "A wave flume test system" (CN202311744850.8), but it cannot distinguish the horizontal shear load generated by waves from the vertical pressure load; while annular flumes can simulate the phenomena of sediment initiation velocity, dynamic water sedimentation and scouring under different flow rates, salinity and other parameters. For example, the patent "An experimental device for wave-induced seepage-induced sediment erosion inside the seabed" (CN201710061388.X) realizes the combined effect of unidirectional flow scouring and seepage liquefaction, but does not solve the problem of distinguishing liquefaction resuspension; the patent "A circulating straight flume device for simulating sediment resuspension under reciprocating flow" (CN104075872 B) can simulate the process of sediment initiation and resuspension caused by reciprocating water flow acting on sediments, but only considers the effect of shear resuspension and ignores the contribution of liquefaction mechanism to the amount of sediment resuspension. The calculation method and model proposed in the patent "A method and system for calculating the sediment start-up flux in a wave-induced liquefaction state of silt" (CN117688788 A) take into account that the total sediment shear resuspension flux is composed of two parts: the wave-induced liquefaction resuspension flux and the seabed shear resuspension flux. However, it is mainly theoretical analysis and calculation, and lacks experimental equipment for verification. Moreover, whether it is field observation or indoor testing, the instruments and equipment directly measure the data on the change in suspended sediment concentration in the water body caused by the combined action of shear and liquefaction mechanisms. These data characterize the overall characteristics of the sediment resuspension phenomenon and cannot distinguish the specific mechanism that causes sediment resuspension. Therefore, there is an urgent need for a test device that can effectively distinguish between liquefaction and shear mechanisms while controlling the intensity of the action.

[0004] In view of this, the present invention provides a test device suitable for distinguishing and controlling the intensity of seabed shear and liquefaction under wave conditions, and proposes a calculation method for the sediment resuspension contribution rate based on the reference concentration formula, which solves the problem of difficulty in distinguishing and quantifying the contribution of liquefaction and shear mechanisms to sediment resuspension in indoor experiments. Summary of the invention

[0005] In order to make up for the shortcomings of the prior art, the present invention provides a flume test system and method for exploring the mechanism of wave-induced sediment resuspension. The device can control the intensity of the two mechanisms of shearing and liquefaction. This device solves the problem that the intensity of the two mechanisms cannot be independently distinguished and controlled in the traditional wave flume.

[0006] The patent of this invention takes into account the representative characteristic parameters of shear and liquefaction mechanisms, proposes a research method based on the reference concentration calculation formula to distinguish the contribution rate of different mechanisms to the overall sediment resuspension amount, and quantifies the contribution of different mechanisms to the sediment resuspension amount.

[0007] The present invention is realized by the following technical scheme: a water tank test system for exploring the mechanism of wave-induced sediment resuspension, comprising a water tank assembly simulating an ocean flow environment, a seepage system, a wave power system, and a sediment resuspension monitoring system, wherein the water tank assembly comprises a U-shaped water tank composed of a left-end open water tank, a right-end water tank, and an internally connected middle-section water tank, the bottom of the left-end open water tank has a drainage hole, and is equipped with a valve for discharging water, a honeycomb plate is provided at the left end of the connection between the left-end open water tank and the internally connected middle-section water tank, and a rectangular opening is provided above the middle-section water tank, and is equipped with a sealed top cover;

[0008] The seepage system includes a trough, a water storage tank, a water pump, a water pump controller, a voltage regulator, and a flow meter. The trough is installed at the bottom of the middle part of the internally connected middle water tank and is connected to the internally connected middle water tank. The bottom plate of the trough at the bottom of the trough is provided with five seepage holes to achieve relatively uniform seepage at the bottom. Four of the seepage holes are distributed in a rectangular shape on the bottom plate, and there is another seepage hole in the center. The five seepage holes are connected to the joints respectively, and then connected to the flow meter, voltage regulator, and water pump in turn through a hose, and finally connected to the water storage tank on the right. A water pump controller is provided on the water pump.

[0009] The wave power system includes a wave-pushing plate, a transmission rod, an electric cylinder, a servo motor, and a motor controller located in the right end water tank; the servo motor is installed on the electric cylinder to drive the electric cylinder, the motor controller is installed on the servo motor, the output end of the electric cylinder is connected to one end of the transmission rod, and the other end of the transmission rod is connected to the center position of the wave-pushing plate. The wave-pushing plate is located in the end water tank, and the motor controller controls the servo motor connected to the electric cylinder to drive the transmission rod to drive the wave-pushing plate to work and move up and down in the right end water tank;

[0010] The sediment resuspension monitoring system is located in the middle of the middle section of the water tank. The sediment resuspension monitoring system includes an acoustic Doppler velocimeter, a sample collection device, a turbidity meter, several pore water pressure sensors, and a camera. The acoustic Doppler velocimeter, the sample collection device, and the turbidity meter are installed above the sedimentation tank. During the process of laying sediment inside the sedimentation tank, pore water pressure sensors are placed at equal intervals at different depths and horizontal positions. The camera is installed directly in front of the sedimentation tank.

[0011] As a preferred solution, a rubber ring passes through the center of the sealing top cover, and an opening is opened on the rubber ring for fixing instruments and filling pores. The acoustic Doppler velocimeter, turbidity meter, and pore water pressure sensor are fixed by the rubber ring.

[0012] As a preferred solution, the left-end open water tank, the right-end water tank, the internally connected middle water tank, the sealed top cover, and the sediment sink are all made of transparent materials.

[0013] A working method of a flume test system for exploring the mechanism of wave-induced sediment resuspension, specifically comprising the following steps:

[0014] Step S1: Preliminary test preparation

[0015] Step S1.1: permeable stones are laid in the sedimentation tank to assist the uniform seepage process, sediments and some tracer particles are laid on top of the permeable stones, and pore water pressure sensors are arranged at equal intervals in the horizontal and vertical directions inside the sediments. The sediment surface is flush with the upper end of the sedimentation tank, and the valve is closed.

[0016] Step S1.2: Connect the seepage holes at the bottom of the sink bottom plate to the water pump, the pressure stabilizer, and the flow meter, and fill the water tank with water;

[0017] Step S1.3: Pour a small amount of water into the left open tank from the top until the water level is flush with the bottom of the middle tank, and remove bubbles on the side wall and sediment surface;

[0018] Step S1.4: Arrange the acoustic Doppler velocimeter, the sample collection device, and the turbidity meter at the reference height above the rectangular opening of the middle water tank, pass the instrument through the rubber ring in the middle of the sealing top cover and align it to the top of the sink, make sure that the rubber ring fits tightly against the instrument and the sealing top cover is aligned with the rectangular opening at the top of the middle water tank, and arrange the camera in front of the water tank assembly, with the lens aimed at the sediment surface of the sink;

[0019] Step S2: During the formal test, the working parameters of the wave power system and the seepage system are adjusted in sequence;

[0020] Step S2.1: Continue to fill the middle water tank with water until the water level in the right water tank is higher than the middle water tank;

[0021] Step S2.2: Setting the controller at the right end water tank of the wave power system to set the working parameters of the electric cylinder;

[0022] Step S2.3: setting the working parameters of the water pump controller in the seepage system, and at the same time, injecting water into the water storage tank to maintain the water volume;

[0023] Step S2.4: Start the wave power system controller so that the transmission rod in the right end water tank is connected to the wave pusher plate to generate a stable oscillating flow in the middle water tank; at the same time, start the water pump to extract the water from the water storage tank and pump it to the seepage hole to act on the soil of the sink;

[0024] Step S3: collecting image data of the sediment samples during the test and the sediment resuspension phenomenon and the upper surface of the sediment tank;

[0025] Step S3.1: Continuously collect pictures of the cross section of the sedimentation tank area using a camera, and record the movement state of the sediment particles and tracer particles on the surface of the sedimentation tank by analyzing the pictures;

[0026] Step S3.2: During the formal test, the sample collection device is opened at regular intervals to continuously siphon the sample into the label bottle at a relatively constant flow rate;

[0027] Step S4: Analyze and process the data collected by the sediment resuspension monitoring system to obtain sediment resuspension characteristics and sediment concentration data during the test; combined with the calculation method, the influence of shear and liquefaction on sediment resuspension characteristics at different action intensities and their contribution rates can be quantified;

[0028] As a preferred solution, step S4 specifically includes the following steps:

[0029] Step S4.1: Sediment particle size before testing ,density , Porosity Perform measurement analysis and calculate the dimensionless particle size using formula (1): :

[0030] (1)

[0031] In the formula, — acceleration due to gravity; —Specific gravity of sediment, , —Environmental water density; — kinematic viscosity;

[0032] Step S4.2: Measure the velocity data using the acoustic Doppler velocimeter and obtain the horizontal and vertical turbulent pulsation components through processing , , and then the Reynolds stress is calculated by formula (2): , characterizing the intensity of the shear mechanism on sediment resuspension:

[0033] (2)

[0034] Step S4.3: The pore water pressure sensor (504) is placed at different burial depths ( ) is the pressure difference in the seepage process measured at ), the vertical pore water pressure gradient can be calculated by formula (3): , characterizing the intensity of the liquefaction mechanism on sediment resuspension:

[0035] (3)

[0036] in, — Excess pore water pressure measured by a pore pressure sensor buried relatively deep; — Excess pore water pressure measured by pore pressure sensors at relatively shallow burial depths; —the relative height of the buried depth of the pore water pressure sensor (504); —the height of the location where the pore water pressure sensor (504) is buried at a relatively shallow depth;

[0037] Step S4.4: Reference concentration for sediment resuspension due to pure shear mechanism The expression of is formula (4):

[0038] (4)

[0039] In the formula, —Related to the reference height of the substrate, to which the substrate roughness is related.

[0040] Step S4.5: Considering the sediment resuspension caused by pure shear, the critical Shields number during the pure shear test , Shields number for pure shear mechanism Calculated by formula (5) and formula (6) respectively, we can get:

[0041] (5)

[0042] (6)

[0043] In the formula, — Shear stress when only the wave power system is working;

[0044] Step S4.5: Calibrate the turbidity meter measurement data with the sediment sample filtration results to establish the correlation between turbidity and suspended sediment concentration and obtain the pure shear sediment concentration measurement value ;

[0045] Step S4.6: Set the critical Shields number and the Shields number for the pure shear mechanism Substitute into the right side of the calculation formula (4); the pure shear sediment concentration measurement value Substituting into the left side of formula (4), the constant , ; Determine the suspended sediment value at different shear strengths ;

[0046] Step S4.7: The sediment concentration of the resuspended sediment is composed of two parts: the sediment concentration contributed by the shear mechanism and the sediment concentration contributed by the liquefaction mechanism. The total sediment concentration measurement value was determined experimentally. and pure shear concentration Therefore, the sediment resuspension concentration caused by liquefaction mechanism is It can be obtained by formula (7):

[0047] (7)

[0048] Step S4.8: Pure shear and pure liquefied suspended sediment value Substituting them into the calculation formula (8) and formula (9) respectively, we can get the contribution rate of shear and liquefaction mechanism to sediment resuspension. :

[0049] (8)

[0050] (9).

[0051] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0052] The top of the water tank test area of ​​the present invention adopts a detachable structure design, and there is enough space to adjust the posture of the instrument during the test. The design of the sealed top cover is convenient for driving away the bubbles in the water tank after a small amount of water is initially injected. The sealed top cover is closed to achieve the sealing of the middle section of the water tank, thereby reducing the influence of the top bubbles on the test observation and improving the accuracy of the simulation process of the resuspension of seabed sediments caused by wave action.

[0053] The invention has a simple structure, small footprint, easy operation and strong applicability. Compared with a large wave straight water tank, the U-shaped water tank of the invention can effectively generate the same reciprocating motion of water flow as waves through the design of a middle closed water tank in the middle, in conjunction with the wave power system and seepage system in the left and right water tanks, and has the same effect on sediments under wave conditions, thereby improving the operability of the experiment.

[0054] The experiment provided by the present invention can realize the study of the evolution process of sediment concentration on the sediment surface under different shear and liquefaction conditions at a laboratory scale, and can control the intensity of shear and liquefaction, so as to verify the influence characteristics of these two mechanisms on sediment resuspension under wave action.

[0055] The present invention proposes a method for distinguishing the extent of action of shear and liquefaction mechanisms and quantifying their contributions. The dimensionless quantity is taken into account in the calculation method to make the setting of experimental conditions or simulation parameters more flexible and convenient, reduce errors and uncertainties in experiments or simulations, and make the quantitative calculation results more widely applicable.

[0056] The present invention adopts a modular design, and the action intensity of the shearing and liquefaction mechanisms can be adjusted as needed to meet different research needs.

[0057] Additional aspects and advantages of the present invention will become apparent in the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0059] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0060] Figure 2 It is a front view structural schematic diagram of the present invention;

[0061] Figure 3 It is a left-side structural schematic diagram of the present invention;

[0062] Figure 4 It is a schematic diagram of the top view structure of the present invention;

[0063] Figure 5 It is a structural schematic diagram of the honeycomb board;

[0064] Figure 6 It is a schematic diagram of the structure of the sealing top cover;

[0065] Figure 7 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0066] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0067] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0068] Combine the following Figures 1 to 6 The water tank test system and method for exploring the wave-induced sediment resuspension mechanism according to the embodiment of the present invention are described in detail.

[0069] like Figure 1 , Figure 2As shown, the present invention proposes a water tank test system for exploring the mechanism of wave-induced sediment resuspension, including a water tank component simulating an ocean flow environment, a seepage system, a wave power system, and a sediment resuspension monitoring system, wherein the water tank component includes a left-end open water tank 101, a right-end water tank 401, and an internally connected middle-section water tank 201 to form a U-shaped water tank, the left-end open water tank 101 has a drainage hole at the bottom, and is equipped with a valve 1011 for discharging water, a honeycomb plate 2011 is provided at the left end of the connection between the left-end open water tank 101 and the internally connected middle-section water tank 201, a rectangular opening is provided above the middle-section water tank 201 for accommodating monitoring instruments, and is equipped with a sealing top cover 2012; a rubber ring 2013 is passed through a center of the sealing top cover 2012, and an opening 214 is provided on the rubber ring 2013 for fixing instruments and filling pores, and the acoustic Doppler velocimeter 501, the turbidity meter 503, and the pore water pressure sensor 504 are fixed by the rubber ring 2013.

[0070] The seepage system includes a trough 302, a water storage tank 303, a water pump 304, a water pump controller 3041, a voltage stabilizer 305, and a flow meter 306; the trough 302 is installed at the middle bottom end of the internally connected middle water tank 201, and is connected to the internally connected middle water tank 201. The trough bottom plate 3021 at the bottom of the trough 302 is provided with five seepage holes 3022 to achieve relatively uniform seepage at the bottom, four of which are distributed in a rectangular shape on the bottom plate, and there is another seepage hole 3022 in the center position. The five seepage holes 3022 are respectively connected to the joints, and then connected to the flow meter 306, the voltage stabilizer 305, and the water pump 304 in sequence through the hose, and finally connected to the water storage tank 303 on the right. The water pump 304 is provided with a water pump controller 3041, and the working intensity of the water pump 304 is controlled by changing the working parameters of the water pump controller 3041; the left end open water tank 101, the right end water tank 401, the internally connected middle water tank 301, the sealed top cover 2012, and the sediment settling tank 302 are all made of transparent materials.

[0071] The wave power system includes a wave pushing plate 402, a transmission rod 403, an electric cylinder 404, a servo motor 405, and a motor controller 406 located in the right end water tank 401; the servo motor 405 is installed on the electric cylinder 404 to drive the electric cylinder 404, and the motor controller 406 is installed on the servo motor 405. The output end of the electric cylinder 404 is connected to one end of the transmission rod 403, and the other end of the transmission rod 403 is connected to the center position of the wave pushing plate 402. The wave pushing plate 402 is located in the end water tank 401. The motor controller 406 controls the servo motor 405 connected to the electric cylinder 404 to drive the transmission rod 403 to drive the wave pushing plate 402 to work and move up and down in the right end water tank 401. The water body reaches the left honeycomb plate 2011 to dissipate the impact effect of the water flow;

[0072] The sediment resuspension monitoring system is located in the middle of the middle water tank 201. The sediment resuspension monitoring system includes monitoring instruments such as an acoustic Doppler velocimeter 501, a sample collection device 502, a turbidity meter 503, several pore water pressure sensors 504, and a camera 505. The acoustic Doppler velocimeter 501, the sample collection device 502, and the turbidity meter 503 are installed above the sedimentation tank 302, and the acoustic Doppler velocimeter 501 is used to measure the velocity and turbulent fluctuations. During the process of laying sediment inside the sedimentation tank 302, pore water pressure sensors 504 are placed at equal intervals at different depths and horizontal positions to monitor the changes in sediment pore water pressure during the test. The camera is installed in front of the sedimentation tank.

[0073] A working method of a flume test system for exploring the mechanism of wave-induced sediment resuspension, specifically comprising the following steps:

[0074] Step S1: Preliminary test preparation

[0075] Step S1.1: permeable stones are laid in the sedimentation tank 302 to assist the uniform seepage process, sediments and some tracer particles are laid on top of the permeable stones, and pore water pressure sensors 504 are arranged. The sediment surface is flush with the upper end of the sedimentation tank 302, and the valve 1011 is closed.

[0076] Step S1.2: Connect the seepage hole 3022 at the bottom of the sink bottom plate 3021 with the water pump 304, the voltage stabilizer 305, and the flow meter 306, and fill the water storage tank 303 with water;

[0077] Step S1.3: Pour a small amount of water from the top of the left open water tank 101 until the water level is flush with the bottom of the middle water tank 201, and remove bubbles on the side wall and the surface of the sediment;

[0078] Step S1.4: Arrange the acoustic Doppler velocimeter 501, the sample collection device 502, and the turbidity meter 503 at the reference height above the rectangular opening of the middle water tank 201, and align the instrument through the rubber ring 2013 in the middle of the sealing top cover 2012 to the top of the sink 302, confirm that the rubber ring 2013 is in close contact with the instrument and the sealing top cover 2012 is aligned with the rectangular opening at the top of the middle water tank 201, and arrange the camera 505 in front of the water tank assembly, with the lens aimed at the sediment surface of the sink 302;

[0079] Step S2: During the formal test, the operating parameters of the wave power system and the seepage system are adjusted in sequence, which may include various operating conditions where only the wave power system works, only the seepage system works, and intermediate transition conditions;

[0080] Step S2.1: Continue to fill the middle water tank 201 with water until the water level of the right water tank 101 is higher than the middle water tank 201;

[0081] Step S2.2: setting the controller 406 at the right end water tank 401 in the wave power system to set the working parameters of the electric cylinder 404;

[0082] Step S2.3: setting the working parameters of the water pump controller 3041 in the seepage system, and at the same time, injecting water into the water storage tank 305 to maintain the water volume;

[0083] Step S2.4: Start the wave power system controller 206 so that the transmission rod 203 in the right end water tank 201 is connected to the wave pusher 202 so that a stable oscillating flow is generated in the middle water tank 301; at the same time, start the water pump 303 to extract water from the water storage tank 305 and pump it to the seepage hole 3022 to act on the soil of the sedimentation tank 302;

[0084] Step S3: collecting image data of the test process, sediment resuspension phenomenon and sediment samples on the upper surface of the sedimentation tank 302;

[0085] Step S3.1: using the camera 505 to continuously collect pictures of the cross section of the sedimentation tank 302 at a suitable frequency, and by analyzing the pictures, recording the movement state of the sediment particles and the tracer particles on the surface of the sedimentation tank 302;

[0086] Step S3.2: during the formal test, the sample collection device 502 is opened at a fixed time, and a certain amount of sample is continuously siphoned into the label bottle at a relatively constant flow rate;

[0087] Step S4: Analyze and process the data collected by the sediment resuspension monitoring system to obtain sediment resuspension characteristics and sediment concentration data during the test; combined with the calculation method, the influence of shear and liquefaction on sediment resuspension characteristics at different action intensities and their contribution rates can be quantified;

[0088] The specific steps include:

[0089] Step S4.1: Sediment particle size before testing ,density , Porosity Perform measurement analysis and calculate the dimensionless particle size using formula (1): :

[0090] (1)

[0091] In the formula, — acceleration due to gravity; —Specific gravity of sediment, , —Environmental water density; — kinematic viscosity;

[0092] Step S4.2: Measure the velocity data using the acoustic Doppler velocimeter and obtain the horizontal and vertical turbulent pulsation components through processing , , and then the Reynolds stress is calculated by formula (2): , characterizing the intensity of the shear mechanism on sediment resuspension:

[0093] (2)

[0094] Step S4.3: The pore water pressure sensor 504 is located at different burial depths ( ) is the pressure difference in the seepage process measured at ), the vertical pore water pressure gradient can be calculated by formula (3): , characterizing the intensity of the liquefaction mechanism on sediment resuspension:

[0095] (3)

[0096] in, — Excess pore water pressure measured by a pore pressure sensor buried relatively deep; — Excess pore water pressure measured by pore pressure sensors at relatively shallow burial depths; - the relative depth of the pore water pressure sensor 504; - the height of the pore water pressure sensor 504 at a relatively shallow burial depth;

[0097] Step S4.4: Reference concentration for sediment resuspension due to pure shear mechanism The expression of is formula (4):

[0098] (4)

[0099] In the formula, —Related to the reference height of the substrate, to which the substrate roughness is related.

[0100] Step S4.5: Considering the sediment resuspension caused by pure shear, the critical Shields number during the pure shear test , Shields number for pure shear mechanism Calculated by formula (5) and formula (6) respectively, we can get:

[0101] (5)

[0102] (6)

[0103] In the formula, — Shear stress when only the wave power system is working;

[0104] Step S4.5: Calibrate the turbidity meter measurement data with the sediment sample filtration results to establish the correlation between turbidity and suspended sediment concentration and obtain the pure shear sediment concentration measurement value ;

[0105] Step S4.6: Set the critical Shields number and the Shields number for the pure shear mechanism Substitute into the right side of the calculation formula (4); the pure shear sediment concentration measurement value Substituting into the left side of formula (4), the constant , ; Determine the suspended sediment value at different shear strengths ;

[0106] Step S4.7: The sediment concentration of the resuspended sediment is composed of two parts: the sediment concentration contributed by the shear mechanism and the sediment concentration contributed by the liquefaction mechanism. The total sediment concentration measurement value was determined experimentally. and pure shear concentration Therefore, the sediment resuspension concentration caused by liquefaction mechanism is It can be obtained by formula (7):

[0107] (7)

[0108] Step S4.8: Pure shear and pure liquefied suspended sediment value Substituting them into the calculation formula (8) and formula (9) respectively, we can get the contribution rate of shear and liquefaction mechanism to sediment resuspension. :

[0109] (8)

[0110] (9).

[0111] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0112] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flume test system for exploring the mechanism of wave-induced sediment resuspension, comprising a flume component simulating an ocean flow environment, a seepage system, a wave power system, and a sediment resuspension monitoring system, characterized in that , The water tank assembly comprises a left-end open water tank (101), a right-end water tank (401), and an internally connected middle water tank (201) to form a U-shaped water tank, wherein the left-end open water tank (101) has a drainage hole at the bottom and is provided with a valve (1011) for draining water, a honeycomb plate (211) is provided at the left end of the connection between the left-end open water tank (101) and the internally connected middle water tank (201), and a rectangular opening is provided above the middle water tank (201) and is provided with a sealed top cover (2012); The seepage system comprises a trough (302), a water storage tank (303), a water pump (304), a water pump controller (3041), a voltage regulator (305), and a flow meter (306); the trough (302) is installed at the middle bottom end of the internally connected middle water tank (201) and is connected to the internally connected middle water tank (201); a trough bottom plate (3021) at the bottom of the trough (302) is provided with five seepage holes (3022), four of which are distributed on the bottom plate in a rectangular shape, and there is another seepage hole (3022) at the center; the five seepage holes (3022) are respectively connected to the joint, and then connected to the flow meter (306), the voltage regulator (305), and the water pump (304) in sequence through a hose, and finally connected to the water storage tank (303) located on the right side; a water pump controller (3041) is provided on the water pump (304); The wave power system comprises a wave pushing plate (402), a transmission rod (403), an electric cylinder (404), a servo motor (405), and a motor controller (406) located in a right end water tank (401); the servo motor (405) is mounted on the electric cylinder (404) for driving the electric cylinder (404); the motor controller (406) is mounted on the servo motor (405); the output end of the electric cylinder (404) is connected to one end of the transmission rod (403); the other end of the transmission rod (403) is connected to the center position of the wave pushing plate (402); the wave pushing plate (402) is located in the right end water tank (401); the motor controller (406) controls the servo motor (405) connected to the electric cylinder (404) to drive the transmission rod (403) to drive the wave pushing plate (402) to work and move up and down in the right end water tank (401); The sediment resuspension monitoring system is located in the middle of the middle water tank (201), and comprises an acoustic Doppler velocimeter (501), a sample collection device (502), a turbidity meter (503), a pore water pressure sensor (504), and a camera (505); the acoustic Doppler velocimeter (501), the sample collection device (502), and the turbidity meter (503) are installed above the sedimentation tank (302), and the pore water pressure sensors (504) are placed at equal intervals at different depths and horizontal positions during the process of laying sediment inside the sedimentation tank (302), and the camera (505) is installed in front of the sedimentation tank (302).

2. A flume test system for investigating the mechanism of wave-induced sediment resuspension according to claim 1, characterized in that A rubber ring (2013) passes through the center of the sealing top cover (2012), an opening (2014) is provided on the rubber ring (2013), and the acoustic Doppler velocimeter (501), the turbidity meter (503), and the pore water pressure sensor (504) are fixed by the rubber ring (2013).

3. A flume test system for investigating the mechanism of wave-induced sediment resuspension according to claim 1, characterized in that The left-end open water tank (101), the right-end water tank (401), the internally connected middle water tank (201), the sealed top cover (2012), and the sediment sink (302) are all made of transparent materials.

4. A method for operating a flume test system for investigating the mechanism of wave-induced sediment resuspension as claimed in any one of claims 1 to 3, characterized in that , specifically including the following steps: Step S1: Preliminary test preparation Step S1.1: permeable stones are laid in the sedimentation tank (302) to assist the uniform seepage process, sediments and some tracer particles are laid on top of the permeable stones, and a pore water pressure sensor (504) is arranged, the sediment surface is flush with the upper end of the sedimentation tank (302), and the valve (1011) is closed; Step S1.2: connecting the seepage hole (3022) at the bottom of the sink bottom plate (3021) with the water pump (304), the voltage stabilizer (305), and the flow meter (306), and filling the water storage tank (303) with water; Step S1.3: inject a small amount of water from the top of the left open water tank (101) until the water level is flush with the bottom of the middle water tank (201), and remove bubbles on the side wall and the surface of the sediment; Step S1.4: Arrange the acoustic Doppler velocimeter (501), the sample collection device (502), and the turbidity meter (503) at a reference height above the rectangular opening of the middle water tank (201), pass the instrument through the rubber ring (213) in the middle of the sealing top cover (2012) and align it to the top of the sediment tank (302), confirm that the rubber ring (2013) is in close contact with the instrument and that the sealing top cover (2012) is aligned with the rectangular opening at the top of the middle water tank (201), and arrange the camera (505) in front of the water tank assembly, with the lens aimed at the sediment surface of the sediment tank (302); Step S2: During the formal test, the working parameters of the wave power system and the seepage system are adjusted in sequence; Step S2.1: Continue to inject water so that the middle water tank (201) is completely filled with water until the water level of the right end water tank (401) is higher than that of the middle water tank (201); Step S2.2: setting the motor controller (406) at the right end water tank (401) in the wave power system to set the working parameters of the electric cylinder (404); Step S2.3: setting the working parameters of the water pump controller (3041) in the seepage system, and at the same time, injecting water into the water storage tank (303) to maintain the water volume; Step S2.4: Start the wave power system controller (206) so that the transmission rod (203) in the right end water tank (401) is connected to the wave pusher (402) so that a stable oscillating flow is generated in the middle water tank (201); at the same time, start the water pump (304) to extract water from the water storage tank (303) and pump it to the seepage hole (3022) to act on the soil of the sedimentation tank (302); Step S3: collecting image data of the sediment resuspension phenomenon and the sediment sample on the upper surface of the sedimentation tank (302) during the test; Step S3.1: using a camera (505) to continuously collect pictures of the cross section of the sedimentation tank (302), and by analyzing the pictures, recording the movement state of the sediment particles and the tracer particles on the surface of the sedimentation tank (302); Step S3.2: during the formal test, the sample collection device (502) is opened at a fixed time to continuously siphon the sample into the label bottle at a relatively constant flow rate; Step S4: Analyze and process the data collected by the sediment resuspension monitoring system to obtain sediment resuspension characteristics and sediment concentration data during the experiment; combine calculation methods to quantify the impact and contribution rate of shear and liquefaction on sediment resuspension characteristics under different action intensities.

5. The working method of a flume test system for investigating the mechanism of wave-induced sediment resuspension according to claim 4 is characterized in that , the step S4 specifically includes the following steps: Step S4.1: Sediment particle size before testing ,density , Porosity Perform measurement analysis and calculate the dimensionless particle size using formula (1): : （1） In the formula, — gravitational acceleration; s—specific gravity of sediment, , —Environmental water density; — kinematic viscosity; Step S4.2: Measure the velocity data using the acoustic Doppler velocimeter and obtain the horizontal and vertical turbulent pulsation components through processing , , and then the Reynolds stress is calculated by formula (2): , characterizing the intensity of the shear mechanism on sediment resuspension: （2） Step S4.3: The pore water pressure sensor (504) is located at different burial depths. The pressure difference in the seepage process measured at , the vertical pore water pressure gradient can be calculated by formula (3): , characterizing the intensity of the liquefaction mechanism on sediment resuspension: （3） in, — Excess pore water pressure measured by a pore pressure sensor buried at a relatively deep depth; — Excess pore water pressure measured by pore pressure sensors at relatively shallow burial depths; —the relative height of the buried depth of the pore water pressure sensor (504); —the height of the location where the pore water pressure sensor (504) is buried at a relatively shallow depth; Step S4.4: Reference concentration for sediment resuspension due to pure shear mechanism The expression of is formula (4): (4) In the formula, It is the reference height of suspended sediment relative to the bottom bed and is related to the bottom bed roughness; Step S4.5: Considering the sediment resuspension caused by pure shear, the critical Shields number during the pure shear test , Shields number for pure shear mechanism It can be calculated by formula (5) and formula (6) respectively: （5） （6） In the formula, — Shear stress when only the wave power system is working; Step S4.5: Calibrate the turbidity meter measurement data with the sediment sample filtration results to establish the correlation between turbidity and suspended sediment concentration and obtain the pure shear sediment concentration measurement value ; Step S4.6: Set the critical Shields number and the pure shear mechanism Shields number Substitute into the right side of the calculation formula (4); the pure shear sediment concentration measurement value Substitute into the left side of formula (4) to determine the constant , The value of pure shear suspended sediment under different shear strengths is obtained. ; Step S4.7: The sediment concentration of the resuspended sediment is composed of two parts: the sediment concentration contributed by the shear mechanism and the sediment concentration contributed by the liquefaction mechanism; the total sediment concentration measurement value is determined by experiment and pure shear suspended sediment value Therefore, the sediment resuspension concentration caused by liquefaction mechanism is It can be obtained by formula (7): （7） Step S4.8: Set the pure shear suspended sediment value Sediment resuspension and sediment concentration caused by liquefaction mechanism Substituting them into the calculation formula (8) and formula (9) respectively, we can get the contribution rate of shear and liquefaction mechanism to sediment resuspension. : （8） （9）。

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