A test device and test method for non-uniform sand motion probability

Abstract

The present invention discloses a test device and test method for the probability of non-uniform sand movement. The device includes a water tank, a sediment feeder, a bed simulation plate, a bed load collector, and a suspended load collector. The method specifically includes: firstly dyeing sediments of different particle sizes to obtain non-uniform dyed sand, sticking sediments of the same grade to the bottom of the water tank to form a rough plate, and arranging the sediment feeder, the bed load collector, and the suspended load collector from top to bottom; soaking the non-uniform dyed sand and spreading it on the sediment feeder, giving a water flow intensity so that the sediment is in partial transport or full transport, and opening the sediment feeder after the water flow is stable to start the test until the sediment stops moving. Collect the sediment in the bed load and suspended load collectors, dry and sieve them, and weigh the dyed sand of different particle sizes. The ratio of the weight of the graded dyed sand obtained by the two collectors to the initial weight is the starting probability and the suspension probability of the non-uniform sand. The present invention obtains two movement probabilities at the same time in one test, with low cost and high efficiency and accuracy.

Description

Technical Field

[0001] The invention belongs to the field of river sediment dynamics, and in particular relates to a test device and a test method for the probability of non-uniform sand movement. Background Art

[0002] Under certain water flow and boundary conditions, part of the sediment in rivers and coastal waters is in a static state, while the other part is in a moving state. The moving sediment is divided into bedload and suspended load. The transformation of sediment from static to bedload involves the initiation of sediment, while the transformation from bedload to suspended load is the suspension of sediment. The critical state of sediment transformation from bedload to suspended load is called sediment uplift. When the external force that promotes sediment movement is greater than the external force that keeps the sediment static, the sediment will be in a moving state, which is a deterministic mechanical phenomenon. However, the external force caused by water flow pulsation is random, and the position of sediment on the bed surface is also random. Therefore, sediment movement is a random mechanical phenomenon. There have been great developments in the experiment and theory on the initiation and uplift of uniform sand. Many formulas such as starting flow velocity, starting shear stress and uplift flow velocity have been established. Some experimental studies have also been conducted on the initiation of non-uniform sand. The above research focuses on the critical water flow state where sediment is in initiation or suspension, and considers the deterministic factors of sediment movement, while ignoring the randomness of sediment movement. Regarding the randomness of sediment movement, many scholars have established theoretical expressions for the probability of starting and the probability of lifting, but there is a lack of experimental data to support it. The main reason is that there is a lack of experimental methods that are purely for the probability of starting and the probability of lifting, and the experimental method that combines the probability of starting and the probability of lifting is still blank. For non-uniform sand, the interaction between particles of different particle sizes makes the movement of non-uniform sand much more complicated than that of uniform sand. The research on the movement of non-uniform sand is far less in-depth than that of uniform sand. There are fewer studies on the uncertainty of the probability of starting and the probability of lifting of non-uniform sand, which are mainly limited to theoretical deductions based on probability distribution. There is still a blank in the experimental verification of probability distribution. In short, the problem of the probability of starting and the probability of lifting of non-uniform sand is difficult to distinguish the movement state of particles of different particle sizes in the experiment, and the collection method of graded sediment under different movement states has not been solved for a long time, resulting in a relatively slow experimental study on the probability of non-uniform sand movement.

[0003] The probability of sediment movement reflects the possibility of sediment mass exchange between the bed and the water flow, and can quantitatively describe the mass of sediment exchange in different motion states. It is an important parameter of the sediment transport equation and boundary conditions of the mathematical model. At the same time, it can be used to calculate the sediment carrying capacity of the water flow and the balanced sediment transport rate of the bed load, and then predict the geomorphic evolution of water bodies such as rivers, estuaries, coasts, bays, reservoirs and lakes, and provide scientific basis and theoretical support for practical problems such as port channel management, tidal flat scouring and silting, downstream scouring of reservoirs and reservoir area siltation, and flood control and tide prevention. However, due to the lack of experimental equipment and experimental methods for movement probabilities such as sediment initiation probability and uplift probability, the theoretical research on the randomness of sediment movement lacks verification of measured data. These problems that should be calculated through the probability of sediment movement can only be solved by deterministic critical parameters such as starting velocity, starting shear stress and uplift velocity. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a test device and test method for the probability of non-uniform sand movement, which guides the calculation of the probability of non-uniform sand starting and suspension, and fills the gap in the non-uniform sand movement probability experiment in river sediment dynamics.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A test device for the probability of non-uniform sand movement, comprising a water tank, a sediment feeder, a bottom bed simulation plate, a bed load collector, and a suspended load collector;

[0007] The water tank comprises a water storage tank, a submersible pump, a flow stabilizing plate, a front door, a water tank body, a tail door and a return pipe; the water tank body is located above the water storage tank, and the tail of the water tank body is connected with the water storage tank through the return pipe; the submersible pump is located in the water storage tank, and the water outlet of the submersible pump is connected with the water inlet of the water tank body through a pipeline, so that the water in the water storage tank is pumped into the water tank body through the pipeline; the flow stabilizing plate is arranged near the water inlet of the water tank body, so as to make the water flow smoothly flow into the water tank body; the front door and the tail door are respectively located at the front end and the tail end of the water tank body, and the front door and the tail door are baffles that can be pulled up and down, and are used to block the water flow or adjust the water storage flow of the tank body;

[0008] The sediment feeder is located at the bottom of the water tank body and is used to contain sediment; the sediment feeder includes a cover plate that can be automatically popped open;

[0009] The bottom bed simulation plate, bed load collector and suspended load collector are arranged in sequence at the bottom of the water tank body along the length direction of the water tank; the bottom bed simulation plate is located between the sediment supplier and the bed load collector; there are two through holes at the beginning of the bottom of the water tank body, and the bed load collector and the suspended load collector both include a straight pipe section and a curved pipe section, which are fixedly connected to the through holes at the corresponding positions of the bottom of the water tank body through the straight pipe sections, and the bed load collector and the suspended load collector are used to collect bed load and suspended load, respectively.

[0010] Furthermore, the sediment supplier is a drawer-type cover box with a rectangular cross-section and a trapezoidal cross-section, which includes a drawer-type cover; both side surfaces of the drawer-type cover are connected to a bayonet control switch through a spring.

[0011] Furthermore, the width of the bed load collector is the same as that of the water tank body, and rotating blades are provided at the junction of the straight pipe section and the curved pipe section of the bed load collector to block the water flow from the water tank body; a detachable circular sealing plate is fixed at the tail of the curved pipe section to facilitate sediment collection.

[0012] Furthermore, the suspended matter collector and the pushed matter collector have the same structure, and the dimension of the suspended matter collector along the length direction of the water tank body is greater than the dimension of the pushed matter collector along the length direction of the water tank body.

[0013] Furthermore, there are two flow stabilizing plates, which are arranged in parallel and spaced apart near the water inlet of the water tank body.

[0014] Furthermore, the flow stabilizing plate is a plexiglass plate provided with uniform holes.

[0015] Furthermore, the dimension L of the bed load collector along the length direction of the water tank body is 推 Slightly larger than the maximum jump length L of the bed load b :

[0016]

[0017]

[0018] Among them, D max is the maximum starting particle size of the test sand; ρ s is the sediment density, ρ is the water flow density; is the dimensionless flow shear stress, D min is the minimum starting particle size of the test sand, R b is the hydraulic radius, J is the hydraulic energy slope; τ *c is the dimensionless starting shear stress, with a value of 0.032-0.047; D mis the average particle size; the coefficient α is determined based on the jump test data, α≥150;

[0019] The dimension L of the suspended matter collector along the length of the water tank 悬 for

[0020]

[0021] Among them, L s is the maximum movement distance of suspended sediment in suspended sediment trap 5, V0 is the water velocity, h0 is the water depth, h is the water depth in the suspended sediment trap, ω min The smallest test particle D min The corresponding sedimentation velocity.

[0022] A test method based on the probability of non-uniform sand movement is implemented based on a test device for the probability of non-uniform sand movement. The method comprises:

[0023] Step 1: Screen the natural sand to get particles of different sizes, and use red, yellow, green, blue, purple, black and white dyes to dye the particles of different sizes. k Dyeing and drying are performed to obtain dyed sand of different particle sizes, and the total weight G0 of the non-uniform sand and the weight G of the dyed sand of different particle sizes are obtained by weighing. 0k , calculate the initial grading Mix and wet the dyed sand and put it into the sand feeder as the test sand;

[0024] Step 2: Stick the non-uniform sand with the same grade as the test sand on the bottom bed simulation plate to form a rough plate;

[0025] Step 3: Determine the test water depth, set a variety of test flow rates at each test water depth to conduct tests, and execute steps 4 to 6. For each group of tests, obtain the probability of graded start-up and graded lift of non-uniform sand under the water flow conditions and their corresponding probability distribution;

[0026] The minimum test velocity should be greater than or equal to the calculated value of the starting velocity, and the maximum test velocity should be greater than or equal to the calculated value of the lifting velocity. The starting velocity V of the kth particle size sediment should be calculated using the following formula: kc and lifting velocity

[0027] V kc =8 / 7(h / D m ) 1 / 6 [(ρ s / ρ-1)gD k / ε k ] 0.5

[0028]

[0029]

[0030] Among them, D k is the particle size of the kth particle size, g is the gravitational acceleration, ρ s and ρ are the densities of sediment and water, respectively. is the hidden coefficient between different particles of non-uniform sand, D m is the average particle size of sediment, σ g is the geometric standard deviation, h is the water depth; D * is the dimensionless particle size, and ω is the sediment settling velocity.

[0031] Step 4: Turn on the submersible pump, and adjust the front door and the rear door of the water tank body to make the water level in the water tank body reach the preset test water depth, and set a suitable flow rate based on the formula calculation values ​​of the starting flow rate and the lifting flow rate to start the test;

[0032] Step 5: Keep the test flow rate and test water depth unchanged, open the sediment feeder, and start the transfer test of dyed sand in the water tank; continue the movement for a sufficient time so that the dyed sand in the sediment feeder no longer starts, and the dyed sand on the rough plate is washed away, close the tailgate and submersible pump, and stop the test;

[0033] Step 6: For some transport situations, the dyed sand in the sediment feeder, bed load collector and suspended load collector is collected, dried, sieved with a standard sieve of the same specification as before the test sand is dyed, and weighed to obtain the weight G of dyed sand of different particle sizes in bed load and suspended load. bk and G sk , respectively calculate the classification starting probability p of non-uniform sand bk =G bk / G0 and graded lift probability p sk =G sk / G0, and then obtain the cumulative frequency of the bed load, that is, the starting probability distribution The cumulative frequency of suspended matter, i.e. the probability distribution of suspended matter

[0034] For the full transport case, the dyed sand in the bed load collector and the suspended load collector were collected respectively, and the starting probability and suspension probability were calculated in the same way as in the partial transport case, and their respective probability distributions were obtained.

[0035] The beneficial effects of the present invention are as follows:

[0036] (1) The experimental device for the probability of non-uniform sand movement of the present invention fills the blank of the experiment on the probability of non-uniform sand movement in the field of river sediment dynamics.

[0037] (2) The experimental method for the probability of motion of non-uniform sand of the present invention simultaneously solves the experimental problems of the starting probability and the suspension probability of non-uniform sand. In the past, the research on the starting and suspension of non-uniform sand was only aimed at critical starting or critical suspension, which neither involved the probability test problem nor could achieve the simultaneous test of starting and suspension.

[0038] (3) By using the method of the present invention, the movement probabilities of sediment particles of different particle sizes are obtained under the same test conditions, which not only makes the movement of different particles comparable, but also makes the starting probability and the lifting probability comparable.

[0039] (4) Based on the experimental device and experimental method for the probability of non-uniform sand movement of the present invention, the starting probability and suspension probability of sediment particles of several particle sizes under a certain water flow condition can be obtained in one test, which greatly improves the test efficiency, significantly reduces the test cost, saves the researchers' time, and has high data collection accuracy and strong synchronization or comparability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the experimental setup for the probability of non-uniform sand motion.

[0041] Figure 2 Top view of the experimental device for the probability of non-uniform sand movement.

[0042] Figure 3 This is a cross-sectional view of the sediment feeder.

[0043] Figure 4 This is a top view of the sediment feeder.

[0044] Figure 5 Schematic diagram of the collector.

[0045] Figure 6 A top view of the rotating blades.

[0046] In the figure, water tank 1, water storage tank 1-1, submersible pump 1-2, electromagnetic flowmeter 1-3, water inlet 1-4, flow stabilizer 1-5, front door 1-6, water tank body 1-7, tailgate 1-8, return pipe 1-9, sediment supplier 2, hole 2-1, spring 2-2, cover plate 2-3, bayonet spring control switch 2-4, bottom bed simulation board 3, bed load collector 4, rotating blade 4-1, circular sealing plate 4-2, suspended load collector 5, rotating blade 5-1, circular sealing plate 5-2. DETAILED DESCRIPTION

[0047] The present invention will be described in detail below based on the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become more clear. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] like Figure 1 and 2 As shown, the experimental device for the probability of non-uniform sand movement of the present invention comprises a water tank 1, a sediment supplier 2, a bottom bed simulation plate 3, a bed load collector 4, and a suspended load collector 5.

[0049] Among them, the water tank 1 includes a water tank 1-1, a submersible pump 1-2, an electromagnetic flowmeter 1-3, a flow stabilizer 1-5, a front door 1-6, a water tank body 1-7, a tailgate 1-8, and a return pipe 1-9. The water tank body 1-7 is located on the upper part of the water tank 1-1, and the tail of the water tank body 1-7 is connected to the water tank 1-1 through the return pipe 1-9; the submersible pump 1-2 is located in the water tank 1-1, and the water outlet of the submersible pump 1-2 is connected to the water inlet 1-4 of the water tank body 1-7 through a pipeline, so that the water in the water tank 1-1 is pumped into the water tank body 1-7 through the pipeline. The flow stabilizer 1-5 is a plexiglass plate with uniform holes, which is arranged near the water inlet 1-4 of the water tank body 1-7 to allow the water to flow smoothly into the water tank body 1-7. Figure 1 As shown, there are two flow stabilizers 1-5, which are arranged in parallel and spaced apart. The front door 1-6 and the tail door 1-8 are located at the front end and the tail end of the water tank body 1-7, respectively. The front door 1-6 and the tail door 1-8 are organic glass baffles that can be pulled up and down, which can be used to block the water flow or adjust the water storage flow of the tank body. When the bottoms of the front door 1-6 and the tail door 1-8 are in contact with the bottom of the tank at the same time, the tank body is closed and can be used to inject water into the tank body section before the test starts. After the test starts, the front door 1-6 is fully opened, and the flow rate of the water flow in the tank body can be controlled by pulling the tail door 1-8 up and down, thereby controlling its depth and adjusting the water flow to the required water depth for the test.

[0050] like Figures 1 to 4 As shown, the sediment feeder 2 is a drawer-type cover box with a rectangular cross section and a trapezoidal cross section. The sediment feeder 2 is located at the bottom of the water tank body 1-7, and the top length L is greater than the bottom length L b , the width B is the same as the width of the water tank, and the height is δ. Among them, the sediment supplier 2 includes a box and a drawer-type cover 2-3; a set of springs 2-2 and a bayonet control switch 2-4 are respectively arranged on the front and rear sides of the drawer-type cover 2-3, one end of the spring 2-2 passes through the hole 2-1 of the drawer-type cover 2-3 and is connected to the box below, and the other end passes through the drawer-type cover 2-3 and is connected to the bayonet control switch 2-4 fixed on the water tank body 1-7. Before the test starts, the bayonet control switch 2-4 is closed, the drawer-type cover 2-3 is stuck, the spring 2-2 is in a stretched state, and the test sand is blocked by the drawer-type cover 2-3. When the water flow is adjusted to a predetermined uniform flow state, the bayonet control switch 2-4 is turned on, and the spring 2-2 drives the drawer-type cover 2-3 to open in the opposite direction of the water flow so that the test sand is exposed to the water flow and starts to move.

[0051] Furthermore, the slope of the water inlet of the sediment supplier 2 is set to be consistent with the initial angle of formation of the water flow vortex, so as to block the formation of the spiral vortex, ensure that the water flows into the sediment supplier 2 in a streamlined manner, prevent the formation of vortices from affecting the movement of sediment, and the end of the water outlet is tangent to the water flow and is streamlined, so that the water flows smoothly.

[0052] The bedload collector 4 and the suspended load collector 5 are arranged in sequence in the steady flow area at the middle and rear part of the bottom of the water tank body 1-7, and two through holes are formed at the middle and rear part of the bottom of the water tank body 1-7, which are used to install the bedload collector 4 and the suspended load collector 5 respectively. The bedload collector 4 and the suspended load collector 5 have the same structure, and their widths are the same as the width of the water tank body 1-7. They are cubic cylinders, including a straight pipe section and a curved pipe section. The straight pipe section is fixed to the bottom of the water tank, and a rotating blade 4-1 is set at the connection between the straight pipe section and the curved pipe section to block the water flow from the water tank body 1-7. The tail of the curved pipe section is fixed with a detachable circular sealing plate 4-2 by screws to facilitate sediment collection. The only difference between the bedload collector 4 and the suspended load collector 5 is that the dimensions of the straight pipe section along the length direction of the water tank body are different. The dimension L of the bed load collector 4 along the length direction of the water tank body is slightly larger than the maximum jump length L of the bed load. b :

[0053]

[0054]

[0055] Among them, D max is the maximum starting particle size of the test sand; ρ s is the sediment density, ρ is the water flow density; is the dimensionless flow shear stress, D min is the minimum starting particle size of the test sand, R b is the hydraulic radius, J is the hydraulic energy slope; is the dimensionless starting shear stress, with a value of 0.032-0.047; D m is the average particle size; the coefficient α is determined based on the jump test data, α≥150.

[0056] The dimension L of the suspended matter collector 5 along the length direction of the water tank body 悬 for

[0057]

[0058] Among them, L s is the maximum movement distance of suspended sediment in suspended sediment trap 5, V0 is the water velocity, h0 is the water depth, h is the water depth in the suspended sediment trap, ω min The smallest test particle D min The corresponding sedimentation velocity.

[0059] The bottom bed simulation plate 3 is located at the bottom of the water tank body 1-7 between the sediment supplier 2 and the bed collector 4. The bottom bed simulation plate 3 is the same width as the water tank body 1-7. During the test, sand particles of the same grade as the test sand are adhered to its upper surface to simulate the non-uniform rough bottom bed during sediment movement.

[0060] Before the test begins, tap water sufficient for the use is added to the water tank 1-1 in advance, and the submersible pump 1-2 is placed in the water tank 1-1. When the front door 1-6 and the tailgate 1-8 are all pulled out, after the switch is turned on, the water flows through the submersible pump 1-2 through the pipeline into the water tank body 1-7 at the water inlet 1-4, and then flows through the two flow stabilizers 1-5 to smoothly overflow to the upper part of the water tank body 1-7, and finally flows back to the water tank 1-1 through the return pipe 1-9. The water flows from the water tank 1-1 to the water tank body 1-7 by pumping water from the submersible pump 1-2, and the process of the water flowing from the water tank body 1-7 back to the lower water tank 1-1 is completed under the action of gravity, thereby realizing the circulation of the water.

[0061] The test device for the probability of non-uniform sand movement of the present invention also includes a current meter, a depth meter, and a slope adjustment device, etc. The current meter is used to measure the water flow velocity in the tank body, the depth meter is used to measure the water depth in the tank body, and the slope adjustment device is used to adjust the slope of the bottom of the tank body 1-7.

[0062] As shown in Figures 5 and 6, a rotary switch 4-1-1 is provided on the rotary blade 4-1 on the bed material collector 4. The rotary switch 4-1-1 extends out of the water tank body 1-7. When in use, the rotary switch 4-1-1 is turned to drive the rotary blade 4-1 to flip.

[0063] The test method of the test device for the probability of non-uniform sand movement according to the present invention comprises the following steps:

[0064] Step 1: Screen the natural sand to get particles of different sizes, and use red, yellow, green, blue, purple, black and white dyes to dye the particles of different sizes. k Dyeing and drying are performed to obtain dyed sand of different particle sizes, and the total weight G0 of the non-uniform sand and the weight G of the dyed sand of different particle sizes are obtained by weighing. 0k , calculate the initial grading The dyed sand is mixed and soaked and then put into the mud and sand feeder 2 as test sand.

[0065] Step 2: stick the non-uniform sand with the same gradation as the test sand onto the bottom bed simulation plate 3 to form a rough plate;

[0066] Step 3: Determine the test water depth, set a variety of test flow rates at each test water depth to conduct tests, and execute steps 4 to 6. For each group of tests, the probability of graded starting and graded lifting of non-uniform sand under the water flow conditions and their corresponding probability distribution can be obtained;

[0067] The minimum test velocity should be greater than or equal to the calculated starting velocity, and the maximum test velocity should be greater than or equal to the calculated lifting velocity. The following formulas are used to calculate the starting velocity V of the kth particle size sediment: kc and lifting velocity

[0068] V kc =8 / 7(h / D m ) 1 / 6 [(ρ s / ρ-1)gD k / ε k ] 0.5

[0069]

[0070]

[0071] Among them, D k is the particle size of the kth particle size, g is the gravitational acceleration, ρ s and ρ are the densities of sediment and water, respectively. is the hidden coefficient between different particles of non-uniform sand, D m is the average particle size of sediment, σ g is the geometric standard deviation, h is the water depth; D * is the dimensionless particle size, and ω is the sediment settling velocity.

[0072] Step 4: Close the front door 1-6 and the tail door 1-8 of the water tank body 1-7, fill water in front of the tail door 1-8 to a certain depth, start the submersible pump 1-2, and open the front door 1-6 and slowly open the tail door 1-8 after the inlet water level is roughly flush with the water level in the tank; increase the flow rate to the set value while increasing the tail door 1-8, so that the water level slowly drops until it reaches the preset water depth; adjust to a given flow rate to start the test;

[0073] Step 5: Keep the test flow rate and test water depth unchanged, open the sediment feeder 2, and start the transfer test of dyed sand in the water tank body 1-7; continue the movement for a sufficient time so that the dyed sand in the sediment feeder 2 no longer starts, and at the same time the dyed sand on the rough plate is washed away, close the tailgate 1-8 and the submersible pump 1-2, and stop the test.

[0074] Step 6: For some transport situations, the dyed sand in the sediment feeder 2, bed load collector 4 and suspended load collector 5 are collected respectively, dried in an oven at 105°, sieved with a standard sieve of the same specification as before dyeing the test sand, and weighed with an electronic balance with an accuracy of one thousandth of a gram to obtain the weight G of dyed sand of different particle sizes in the bed load and suspended load. bk and G sk , respectively calculate the classification starting probability p of non-uniform sand bk =G bk / G0 and graded lift probability p sk =G sk / G0, and then obtain the cumulative frequency of the bed load, that is, the starting probability distribution The cumulative frequency of suspended matter, i.e. the probability distribution of suspended matter

[0075] For the full transport situation, the dyed sand in the bed load collector 4 and the suspended load collector 5 are collected respectively, and the starting probability and the lifting probability are calculated in the same way as in the partial transport situation, and their respective probability distributions are obtained.

[0076] Those skilled in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention is described in detail with reference to the above examples, those skilled in the art can still modify the technical solutions recorded in the above examples or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, etc. made within the spirit and principle of the invention shall be included in the protection scope of the invention.

Claims

1. A test device for the probability of non-uniform sand movement, characterized in that: It includes a water tank, a sediment feeder, a bottom bed simulation plate, a bed load collector, and a suspended load collector; The water tank comprises a water storage tank, a submersible pump, a flow stabilizing plate, a front door, a water tank body, a tail door and a return pipe; the water tank body is located above the water storage tank, and the tail of the water tank body is connected with the water storage tank through the return pipe; the submersible pump is located in the water storage tank, and the water outlet of the submersible pump is connected with the water inlet of the water tank body through a pipeline, so that the water in the water storage tank is pumped into the water tank body through the pipeline; the flow stabilizing plate is arranged near the water inlet of the water tank body, so as to make the water flow smoothly flow into the water tank body; the front door and the tail door are respectively located at the front end and the tail end of the water tank body, and the front door and the tail door are baffles that can be pulled up and down, and are used to block the water flow or adjust the water storage flow of the tank body; The sediment feeder is located at the bottom of the water tank body and is used to contain sediment; the sediment feeder includes a cover plate that can be automatically popped open; The bottom bed simulation plate, bed load collector and suspended load collector are arranged in sequence at the bottom of the water tank body along the length direction of the water tank; the bottom bed simulation plate is located between the sediment supplier and the bed load collector; there are two through holes at the beginning of the bottom of the water tank body, and the bed load collector and the suspended load collector both include a straight pipe section and a curved pipe section, which are fixedly connected to the through holes at the corresponding positions of the bottom of the water tank body through the straight pipe sections, and the bed load collector and the suspended load collector are used to collect bed load and suspended load, respectively.

2. The test device for the probability of non-uniform sand movement according to claim 1, characterized in that: The sediment feeder is a drawer-type cover box with a rectangular cross section and a trapezoidal cross section, which comprises a drawer-type cover; both sides of the drawer-type cover are connected to a bayonet control switch through a spring.

3. The test device for the probability of non-uniform sand movement according to claim 1, characterized in that: The width of the bed load collector is the same as that of the water tank body. Rotating blades are arranged at the junction of the straight pipe section and the curved pipe section of the bed load collector to seal the water flow from the water tank body. A detachable circular sealing plate is fixed at the tail of the curved pipe section to facilitate sediment collection.

4. The test device for the probability of non-uniform sand movement according to claim 3, characterized in that: The suspended matter collector and the pushed matter collector have the same structure, and the dimension of the suspended matter collector along the length direction of the water tank body is greater than the dimension of the pushed matter collector along the length direction of the water tank body.

5. The test device for the probability of non-uniform sand movement according to claim 1, characterized in that: The flow stabilizing plates are two in number and are arranged in parallel and spaced apart near the water inlet of the water tank body.

6. The test device for the probability of non-uniform sand movement according to claim 1, characterized in that: The flow stabilizing plate is a plexiglass plate with uniform holes.

7. The test device for the probability of non-uniform sand movement according to claim 1, characterized in that: The dimension L of the bed load collector along the length direction of the water tank body 推 Slightly larger than the maximum jump length L of the bed load b : Among them, D max is the maximum starting particle size of the test sand; ρ s is the sediment density, ρ is the water flow density; is the dimensionless flow shear stress, D min is the minimum starting particle size of the test sand, R b is the hydraulic radius, J is the hydraulic energy slope; is the dimensionless starting shear stress, with a value of 0.032-0.047; D m is the average particle size; the coefficient α is determined based on the jump test data, α≥150; The dimension L of the suspended matter collector along the length of the water tank 悬 for Among them, L s is the maximum movement distance of suspended sediment in the suspended sediment trap, V0 is the water velocity, h0 is the water depth, h is the water depth in the suspended sediment trap, ω min The smallest test particle D min The corresponding sedimentation velocity.

8. An experimental method based on the probability of non-uniform sand movement, characterized in that: The method is implemented based on the test device for the probability of non-uniform sand movement according to any one of claims 1 to 7, and the method comprises: Step 1: Screen the natural sand to obtain particles of different sizes, and use red, yellow, green, blue, purple, black and white dyes to dye the particles of different sizes. k Dyeing and drying are performed to obtain dyed sand of different particle sizes, and the total weight G0 of the non-uniform sand and the weight G of the dyed sand of different particle sizes are obtained by weighing. 0k , calculate the initial grading Mix and wet the dyed sand and put it into the sand feeder as the test sand; Step 2: Stick the non-uniform sand with the same grade as the test sand on the bottom bed simulation plate to form a rough plate; Step 3: Determine the test water depth, set a variety of test flow rates at each test water depth to conduct tests, and execute steps 4 to 6. For each group of tests, obtain the probability of graded start-up and graded lift of non-uniform sand under the water flow conditions and their corresponding probability distribution; The minimum test velocity should be greater than or equal to the calculated value of the starting velocity, and the maximum test velocity should be greater than or equal to the calculated value of the lifting velocity. The starting velocity V of the kth particle size sediment should be calculated using the following formula: kc and lifting velocity V kc =8 / 7(h / D m ) 1 / 6 [(ρ s / ρ-1)gD k / ε k ] 0.5 Among them, D k is the particle size of the kth particle size, g is the gravitational acceleration, ρ s and ρ are the densities of sediment and water, respectively. is the hidden coefficient between different particles of non-uniform sand, D m is the average particle size of sediment, σ g is the geometric standard deviation, h is the water depth; D * is the dimensionless particle size, ω is the sediment settling velocity; Step 4: Turn on the submersible pump, and adjust the front door and the rear door of the water tank body to make the water level in the water tank body reach the preset test water depth, and set a suitable flow rate based on the formula calculation values ​​of the starting flow rate and the lifting flow rate to start the test; Step 5: Keep the test flow rate and test water depth unchanged, open the sediment feeder, and start the transfer test of dyed sand in the water tank; continue the movement for a sufficient time so that the dyed sand in the sediment feeder no longer starts, and the dyed sand on the rough plate is washed away, close the tailgate and submersible pump, and stop the test; Step 6: For some transport situations, the dyed sand in the sediment feeder, bed load collector and suspended load collector is collected, dried, sieved with a standard sieve of the same specification as before the test sand is dyed, and weighed to obtain the weight G of dyed sand of different particle sizes in bed load and suspended load. bk and G sk , respectively calculate the classification starting probability p of non-uniform sand bk =G bk / G0 and graded lift probability p sk =G sk / G0, and then obtain the cumulative frequency of the bed load, that is, the starting probability distribution The cumulative frequency of suspended matter, i.e. the probability distribution of suspended matter For the full transport case, the dyed sand in the bed load collector and the suspended load collector were collected respectively, and the starting probability and suspension probability were calculated in the same way as in the partial transport case, and their respective probability distributions were obtained.

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