River, lake and reservoir bottom consolidated sediment scouring experiment integrated system and experiment method

Abstract

The invention relates to a river, lake and reservoir bottom consolidated sediment scouring experiment integrated system and an experiment method. The system comprises a pressure-resistant pipe, a sedimentation device and a washing device. Collected consolidated sediment samples can be repeatedly used, time and labor are saved, the cost is saved, the sedimentation device and the washing device are located in the same laboratory, the transfer time can be shortened, the change of consolidated sediment is reduced, the accuracy and representativeness of experiments are guaranteed, the sedimentation environment which does not exist in reality can be simulated, and the sampling range of experimental samples is expanded; during a scouring experiment, the top of the consolidated sediment can be always flush with the wall surface of the bottom of the water flow pipeline in the experiment process, the device can adapt to consolidated sediment states at different river water flow speeds, experimental errors caused by inclination or accumulation are effectively eliminated, and the scouring speed can be deduced according to the pushing speed of the consolidated sediment at different water flow speeds; the experimental method can accurately simulate the natural deposition environment of silt under different water pressures and the actual erosion speed of river bottom silt in a laboratory environment.

Description

Technical Field

[0001] The invention relates to the technical field of consolidated sediment scouring experiments, and in particular to a complete set of consolidated sediment scouring experiments on the bottom of a river, a lake or a reservoir and an experimental method. Background Art

[0002] The consolidated sediment scouring experiment is an experiment to study the movement law and anti-scouring characteristics of consolidated sediment when it is scoured by water flow. The main research object of this experiment is the sedimentation and consolidation process of consolidated sediment at the bottom of rivers, lakes and reservoirs, as well as the starting and scouring phenomena under the action of water flow. Generally speaking, the experiment includes the following steps: 1. Collection of consolidated sediment; using the traditional mud column collection method to extract consolidated sediment from the bottom of the corresponding river, lake and reservoir using mechanical devices; 2. Startup and scouring experiment; the startup experiment is to place the collected consolidated sediment in a water tank, adjust the scouring water flow speed, observe the starting situation of the consolidated sediment, and record the critical starting flow rate and starting shear stress; on the basis of the startup experiment, the scouring laboratory increases the scouring water flow speed, measures the scouring height of consolidated sediment per unit time, and obtains the scouring rate; 3. Data recording and analysis; the scouring speed, shear stress and scouring height during the experiment are recorded, and the scouring law of consolidated sediment is analyzed based on the recorded data.

[0003] The existing consolidated sediment scouring experiments have the following disadvantages: 1. The traditional mud column collection method is time-consuming, labor-intensive, and costly, and is prone to deformation during transportation, which affects the accuracy and representativeness of the experiment; each consolidated sediment scouring experiment requires a collection; 2. Only consolidated sediment at the bottom of rivers, lakes, and reservoirs at the existing depth is collected, which greatly limits the sampling range of experimental samples and makes it difficult to study the characteristics of consolidated sediment at different depths; 3. In traditional start-up and scouring experiments, consolidated sediment is prone to tilt or pile up into a pyramid shape, causing experimental errors. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and to provide a complete system and method for the scouring experiment of consolidated sediment at the bottom of a river, lake or reservoir.

[0005] The technical scheme of the present invention is: a complete set of river, lake and reservoir bottom consolidated sediment scouring experiment system includes a pressure-resistant pipe, a sedimentation device and a scouring device; the sedimentation device is used to prepare consolidated sediment, which can simulate the natural sedimentation environment under different water pressures, so that the consolidated sediment can be used repeatedly, reducing the acquisition cost and difficulty of consolidated sediment, which is conducive to studying the characteristics of consolidated sediment at different depths; the scouring device can simulate the erosion speed of the actual flushing state;

[0006] The pressure-resistant pipe includes a pipe body, a top flange ring, a bottom flange ring, a hanging plate, and a height-adjusting plate; the top flange ring and the bottom flange ring are fixed to the top and bottom of the pipe body respectively; the height-adjusting plate is radially arranged in the middle of the pipe body, and is symmetrically provided with a plurality of height-adjusting threaded holes; the height-adjusting plate clamps the middle of the pipe body to improve the structural strength and pressure-bearing capacity of the pipe body; the hanging plate is symmetrically fixed to the middle of the pipe body;

[0007] The settling device includes a settling frame, a top flange, a bottom flange, a high-pressure pipeline, a control pipeline, and a switch valve; the settling frame is provided with a number of installation positions; U-shaped clips corresponding to and matching the hanging plates are symmetrically provided on the left and right sides of each installation position; the top flange matches the top flange ring, and is provided with a pilot check valve and a control valve; the control valve is connected to the high-pressure pipeline; the outlet of the pilot check valve is installed on the top flange, the inlet is connected to the outside, and the control port is connected to the control pipeline through the switch valve; the bottom flange matches the bottom flange ring;

[0008] The flushing device includes a water pipe, a pushing mechanism, a flushing frame, a height adjustment bolt, a settlement cup, and a quick-release clamp; flushing water flows into the water pipe; the water pipe is provided with a pushing position and a settlement position in sequence along the direction of the flushing water flow; the flushing frame and the pushing mechanism are both arranged below the pushing position; the water pipe at the pushing position is provided with a pushing through hole corresponding to the inner hole of the pressure-resistant pipe; the top of the flushing frame is connected to the bottom of the water pipe, and a fixing plate is provided in the middle; the threaded end of the height adjustment bolt is abutted against the top of the fixing plate; the threaded section of the height adjustment bolt is threadedly matched with the height adjustment threaded hole; the pushing mechanism includes a connecting sleeve, an electric push rod, and a piston; the upper end of the connecting sleeve is provided with a connecting flange corresponding to the bottom flange ring; the lower end of the connecting sleeve is connected to the fixed end of the electric push rod; the piston is coaxially fixed to the telescopic end of the electric push rod; the outer diameter of the piston corresponds to the inner diameter of the tube body; at the settlement position, the settlement cup is connected to the bottom of the water pipe through a quick-release clamp.

[0009] Preferably, the top flange is also equipped with a pressure gauge to detect the pressure inside the pressure-resistant pipe.

[0010] Preferably, the sedimentation device also includes an air compressor, an air tank with a boosting valve, and a pressure regulating valve; the switch valve uses a pneumatic hand-pull valve; the output end of the air compressor is connected to the control pipeline and the inlet of the air tank with a boosting valve at the same time; the outlet of the air tank with a boosting valve is connected to the high-pressure pipeline through the pressure regulating valve; the gas output by the air compressor directly participates in the work of the pilot check valve; the air tank pressurizes the gas output by the air compressor to meet the simulated underwater pressure.

[0011] Preferably, the sedimentation device also includes a water receiving trough; the water receiving trough is arranged below the installation position and is used to collect water leaking when the pressure-resistant pipe is disassembled, thereby ensuring the cleanliness of the experimental environment.

[0012] Preferably, the complete set of river, lake and reservoir bottom consolidation sediment scour experiment system also includes a sealing ring corresponding to the pressure-resistant pipe; the sealing ring is respectively installed on the top and bottom of the pressure-resistant pipe; the top flange ring and the bottom flange ring are both against the sealing ring; the sealing ring can ensure the sealing degree of the top and bottom of the pressure-resistant pipe, and reduce the processing requirements of the top flange plate, bottom flange plate, top flange ring, bottom flange ring, and connecting flange.

[0013] Preferably, observation windows are provided on both sides of the push position of the water flow pipeline, so that the water erosion situation can be directly observed.

[0014] Preferably, a tube plate is fixedly connected to the bottom of the push-up position of the water flow pipeline; a clamping groove corresponding to the outer circle of the top flange is provided at the center of the bottom of the tube plate; the clamping groove limits the pressure-resistant tube to ensure accurate positioning of the pressure-resistant tube; a through hole corresponding to the inner wall of the tube body is provided at the center of the tube plate; the through hole ensures the connection between the pressure-resistant tube and the water flow pipeline.

[0015] Preferably, the fixing plate is provided with a semi-long hole corresponding to the tube body, which is beneficial to the positioning of the pressure-resistant tube.

[0016] Preferably, the flushing device also includes a support frame; the support frame is arranged at one end of the water flow pipeline; the settlement position is located between the support frame and the flushing frame; the support frame and the flushing frame together set up the water flow pipeline to ensure the stability of the water flow pipeline.

[0017] Preferably, the side wall of the connecting sleeve is provided with air holes to avoid negative pressure under the piston and enable the piston to be pushed smoothly.

[0018] An experimental method of the above-mentioned river, lake, and reservoir bottom consolidation sediment scouring experimental complete set system comprises the following steps:

[0019] S1 Preparation of consolidated sediment

[0020] 1.1 Mix soil sample and water

[0021] After drying the soil sample collected on site, mix it with water in a certain proportion; repeatedly stir the soil sample and water until there is no moisture on the surface of the soil sample;

[0022] 1.2 Fill and install the pressure pipe on the sedimentation device

[0023] Use bolted joints to tightly connect the bottom flange plate and the bottom flange ring; fill the mixed soil sample and water into the pressure tube, and smooth the top of the soil sample after each filling until the top of the soil sample is at a specified distance h from the top of the pressure tube. 初 ; The total length of the pressure-resistant pipe is L; Fill the pressure-resistant pipe with water; Use bolted connectors to tightly connect the top flange plate and the top flange ring; Use hanging plate clips to install them on the U-shaped clips;

[0024] 1.3 Add pressure to the pressure pipe

[0025] Connect the control valve to the high-pressure pipeline; connect the switch valve to the control pipeline; open the control valve and close the switch valve; the high-pressure gas in the high-pressure pipeline enters the pressure-resistant pipe through the control valve, squeezes the water, and makes the water act on the soil sample; the pressure of the high-pressure gas is equivalent to the set underwater pressure of the consolidated sediment;

[0026] 1.4 Determine the density coefficient of consolidated sediment

[0027] At a specific time every day, close the control valve to prohibit high-pressure gas from entering the pressure-resistant pipe; open the control valve to allow the control port of the pilot check valve to enter the control gas flow, and the high-pressure gas in the pressure-resistant pipe is connected to the outside to relieve the pressure in the pressure-resistant pipe; after the pressure relief is completed, remove the top flange and measure the distance h from the top of the soil sample to the top of the pressure-resistant pipe 测 ; Calculate and record the density coefficient of the consolidated sediment on that day: After the measurement is completed, reinstall the top flange, close the switch valve, open the control valve, and continue to pressurize the pressure-resistant pipe;

[0028] 1.5 Formation of consolidated sediment

[0029] After a certain number of days, the control valve is closed and the switch valve is opened to release the pressure; after the pressure release is completed, the pressure pipe is removed; the top flange and the bottom flange are removed; the consolidated sediment is filled in the pressure pipe; the consolidated sediment in the pressure pipe is sampled using a ring knife, and the dry bulk density γ of the consolidated sediment in the pressure pipe is obtained after drying;

[0030] S2 flushing test

[0031] 2.1 Install the pressure tube and sedimentation cup on the flushing device

[0032] Weigh the sedimentation cup and record it as m0; use bolted connectors to tightly connect the connecting flange and the bottom flange ring; use height adjustment bolts to establish a threaded connection with the height adjustment threaded holes; lift the pressure tube so that the threaded end of the height adjustment bolts abuts against the fixed plate; adjust the horizontal position of the pressure tube so that the pressure tube and the top push through hole are aligned; rotate the height adjustment bolts to lift the pressure tube; the top flange ring abuts tightly against the bottom of the top push position; use quick-release clamps to install the sedimentation cup to the sedimentation position and connect it to the water flow pipeline;

[0033] 2.2 Start-up experiment

[0034] Start the electric push rod to make the top of the fixed sediment rise to the position flush with the bottom of the water flow pipe; slowly fill the water flow pipe with water; continue to start the electric push rod to make the top of the fixed sediment emerge in the water flow pipe; slowly increase the water flow velocity in the water flow pipe until you see through the observation window that the water flow in the water flow pipe just hits the top of the exposed fixed sediment; the sediment is peeled off from the top surface of the consolidated sediment in the form of small clumps by the water flow; record the water flow velocity at this time as the critical starting flow velocity v起动 ; Note the lifting speed v of the electric push rod H ;

[0035] 2.3 Scouring experiment

[0036] Increase the water flow rate until you can see through the observation window that the water flow in the water flow pipe has just washed away the top of the newly exposed solidified sand, so that the top of the solidified sand is always flush with the lower wall of the water flow pipe; the sand is lumped or smoke-like and peeled off from the top surface of the solidified sand; record the water flow rate at this time as the full starting flow rate v 冲刷 ;

[0037] 2.4 Sedimentation experiment

[0038] When the electric push rod is extended to the limit position, the consolidated sediment in the pressure-resistant tube is pushed into the water flow pipe and washed away by the water flow; stop supplying water to the water flow pipe and wait for the water in the water flow pipe to be drained out; number the sedimentation cups according to the distance from the observation window; remove each sedimentation cup by the quick-release clamp; put the sedimentation cup filled with sediment into a constant temperature oven and heat and dry it for 6-8 hours to remove the moisture in the sediment; after natural cooling, weigh the sedimentation cup and the sediment in the sedimentation cup;

[0039] The sampling and drying process of consolidated sediment includes the following steps:

[0040] 1) Sampling samples

[0041] Shovel the top of the consolidated mud and sand; press the ring knife vertically and steadily into the consolidated mud and sand; the volume of the ring knife is V; when pressing the ring knife in, it is strictly forbidden to shake the ring knife left and right; after the consolidated mud and sand emerge from the upper end of the ring knife, dig out the consolidated mud and sand around the ring knife, and then take out the ring knife and the consolidated mud and sand carried by the ring knife; use the soil scraper to scrape off the excess consolidated mud and sand at the upper and lower ends of the ring knife, so that the consolidated mud and sand are aligned with the ring knife from top to bottom; use the bottom cover to seal the lower end of the ring knife; cover the upper end of the ring knife with a cover; wipe off the consolidated mud and sand on the outer periphery of the ring knife;

[0042] 2) Drying and weighing the consolidated sand

[0043] The container of the constant temperature oven is weighed and recorded as m1; the consolidated sand in the ring knife is spread flat on the container of the constant temperature oven; the container containing the consolidated sand is placed in the constant temperature oven and heated and dried for 6 to 8 hours; after the sample consolidated sand and the container are cooled, the consolidated sand and the container are weighed and recorded as m2; the dry weight density of the consolidated sand is calculated to be

[0044] 2.5 Processing experimental data

[0045] The experimental data obtained during the experiment are counted and calculated. The experimental data include the flushing rate S r, critical starting shear stress τ 临界 and the difference flow rate Δυ;

[0046] The process of sediment being washed away from the consolidated state in the experiment can be regarded as the scouring and deposition process of sediment on the riverbed, so the formula of riverbed scouring rate is referred to: Among them, S r is the riverbed scouring rate, in kg / m 2 s; W s is the weight of the consolidated sediment reduced during the water flow scouring process, in kg; A is the area scoured by the water flow, in m 2 ; t is the water flow flushing time, in seconds; γ is the dry bulk density of the consolidated sediment in the pressure pipe, in kg / m 3 ; ν H is the lifting speed of the electric push rod, in m / s;

[0047] Based on the Prandtl-Karman study on turbulent flow, the turbulent smooth region satisfies the universal friction coefficient formula, and the friction velocity U * Relationship with wall shear stress τ0: Where ρ is the density of water; friction velocity U * Relationship with average flow velocity ν0: Where λ is the head loss coefficient along the way;

[0048] The two relations are combined and transformed accordingly, and can be transformed into: Where λ can be calculated by the Nicolaz formula; the Nicolaz formula is: Where R e is the Reynolds number, which is a unitless value used in fluid mechanics to describe the flow characteristics of a fluid; the average flow velocity ν0 is ν 起动 The calculated wall shear stress τ0 is the critical starting shear stress τ 临界 ;

[0049] The calculation formula of the differential flow rate Δυ is Δν=ν 冲刷 -ν 起动 ;

[0050] After each sedimentation cup is numbered according to the distance from the observation window, the dry bulk density of the sediment in each sedimentation cup can be measured by m i -m0 is used for calculation; because the inner diameter of each pressure-resistant pipe is uniform, the sedimentation of the washed sediment in each sedimentation cup can be reflected by the dry bulk density of the sediment in the sedimentation cup.

[0051] The beneficial effects of the present invention are as follows: the complete set of river, lake and reservoir bottom consolidation sediment scouring test system of the present invention has the following advantages:

[0052] (1) The present invention can accurately simulate the natural sedimentation environment of sediment under different water pressures and the actual erosion rate of riverbed silt in a laboratory environment, and can repeatedly use the collected consolidated sediment samples, saving time, labor and cost. The sedimentation device and the scouring device are in the same laboratory, which can reduce the transportation time, reduce the change of consolidated sediment, and ensure the accuracy and representativeness of the experiment. It can also simulate the sedimentation environment of consolidated sediment at the bottom of rivers, lakes and reservoirs that does not exist in reality, and expand the sampling range of experimental samples. During the scouring experiment, it can ensure that the top of the consolidated sediment is always flush with the bottom wall of the water flow pipe during the experiment, and can adapt to the consolidated sediment state at different river water flow rates, thereby effectively eliminating the experimental error caused by tilting or accumulation, and can deduce the erosion rate according to the top push speed of consolidated sediment at different water flow rates;

[0053] (2) The sealing ring of the present invention can ensure the sealing degree of the top and bottom of the pressure-resistant pipe, and reduce the processing requirements of the top flange, bottom flange, top flange ring, bottom flange ring, and connecting flange.

[0054] This experimental method can accurately simulate the natural sedimentation environment of sediment under different water pressures and the actual erosion rate of riverbed silt in a laboratory environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a three-dimensional diagram of a sedimentation device equipped with a pressure-resistant pipe;

[0056] Figure 2 yes Figure 1 A front partial sectional view of the

[0057] Figure 3 yes Figure 2 AA section view;

[0058] Figure 4 yes Figure 1 Control gas circuit diagram;

[0059] Figure 5 It is a front view of the flushing device with a pressure-resistant pipe installed;

[0060] Figure 6 yes Figure 5 BB cross-sectional view;

[0061] Figure 7 yes Figure 5 CC section view;

[0062] Figure 8 yes Figure 5 DD cross-sectional view;

[0063] Fig. 9 yes Figure 5 EE cross-sectional view;

[0064] Fig.10 yes Figure 6 FF cross-sectional view;

[0065] Fig.11 yes Figure 5 A three-dimensional diagram of a tube plate in FIG.

[0066] Fig.12 It is a partial experimental data statistics of sediment in each section during the experiment;

[0067] Fig.13 It is the relationship between the compaction coefficient of sediment in each section and the critical starting velocity;

[0068] Fig.14 This is the relationship between the compactness coefficient and critical starting velocity of the HY41 section;

[0069] Fig.15 It is the relationship diagram between the critical starting velocity and the critical starting stress after 14 days of sediment consolidation in each section;

[0070] Fig.16 This is the relationship between the critical starting velocity and the complete starting velocity during the HY41 section experiment;

[0071] Fig.17 This is a real object of a sedimentation device equipped with a pressure-resistant pipe. Figure 1 ;

[0072] Fig.18 This is a real object of a sedimentation device equipped with a pressure-resistant pipe. Figure 2 ;

[0073] Fig.19 This is a real object of a sedimentation device equipped with a pressure-resistant pipe. Figure 3 ;

[0074] Fig. 20 This is a real object of a sedimentation device equipped with a pressure-resistant pipe. Figure 4 ;

[0075] Fig.21 This is a real flushing device with a pressure-resistant pipe installed. Figure 1 ;

[0076] Fig. 22 This is a real flushing device with a pressure-resistant pipe installed. Figure 2 ;

[0077] In the figure: 1. Pressure-resistant pipe, 11. Pipe body, 12. Top flange ring, 13. Bottom flange ring, 14. Hanging plate, 15. Height-adjusting plate, 151. Height-adjusting threaded hole, 21. Settlement rack, 211. U-shaped card, 22. Top flange, 221. Pilot check valve, 222. Control valve, 223. Pressure gauge, 224. Manual pressure relief valve, 23. Bottom flange, 24. High-pressure pipeline, 25. Control pipeline, 26. Switch valve, 27. Water tank, 28. .Pressure regulating valve, 31. Water flow pipeline, 311. Push through hole, 312. Observation window, 313. Pipe clamp plate, 3131. Slot, 3132. Through hole, 321. Connecting sleeve, 3211. Connecting flange, 3212. Air vent, 322. Electric push rod, 323. Piston, 33. Flush rack, 331. Fixed plate, 3311. Half-long hole, 34. Height adjustment bolt, 35. Settling cup, 36. Quick-release clamp, 37. Support frame, 4. Sealing ring. DETAILED DESCRIPTION

[0078] Example 1: See Figure 1-11 A complete set of river, lake and reservoir bottom consolidated sediment scouring experiment system includes a pressure-resistant pipe 1, a sedimentation device and a scouring device; the sedimentation device is used to prepare consolidated sediment, which can simulate the natural sedimentation environment under different water pressures, so that the consolidated sediment can be used repeatedly, reducing the cost and difficulty of obtaining consolidated sediment, which is conducive to studying the characteristics of consolidated sediment at different depths; the scouring device can simulate the erosion speed of the actual flushing state;

[0079] The pressure-resistant pipe 1 includes a pipe body 11, a top flange ring 12, a bottom flange ring 13, a hanging plate 14, and a height-adjusting plate 15; the top flange ring 12 and the bottom flange ring 13 are fixedly connected to the top and the bottom of the pipe body 11 respectively; the height-adjusting plate 15 is radially arranged in the middle of the pipe body 11, and is symmetrically provided with a plurality of height-adjusting threaded holes 151; the height-adjusting plate 15 clamps the middle of the pipe body 11 to improve the structural strength and pressure-bearing capacity of the pipe body 11; the hanging plate 14 is symmetrically fixedly connected to the middle of the pipe body 11;

[0080] The settling device includes a settling frame 21, a top flange 22, a bottom flange 23, a high-pressure pipeline 24, a control pipeline 25, and a switch valve 26; the settling frame 21 is provided with a plurality of installation positions; U-shaped clips 211 corresponding to and matching the hanging plate 14 are symmetrically provided on the left and right sides of each installation position; the top flange 22 is matched with the top flange ring 12, and is provided with a pilot check valve 221 and a control valve 222; the control valve 222 is connected with the high-pressure pipeline 24; the outlet of the pilot check valve 221 is installed on the top flange 22, the inlet is connected with the outside, and the control port is connected with the control pipeline 25 through the switch valve 26; the bottom flange 23 is matched with the bottom flange ring 13;

[0081] The flushing device includes a water pipe 31, a pushing mechanism, a flushing frame 33, a height adjustment bolt 34, a settling cup 35, and a quick-release clamp 36; flushing water flows into the water pipe 31; the water pipe 31 is provided with a pushing position and a settling position in sequence along the direction of the flushing water flow; the flushing frame 33 and the pushing mechanism are both arranged below the pushing position; the water pipe 31 at the pushing position is provided with a pushing through hole 311 corresponding to the inner hole of the pressure-resistant pipe 1; the top of the flushing frame 33 is connected to the bottom of the water pipe 31, and a fixing plate 331 is provided in the middle; the threaded end of the height adjustment bolt 34 is connected to the fixing plate 3 31 is abutted against the top; the threaded section of the height adjustment bolt 34 is threadedly matched with the height adjustment threaded hole 151; the pushing mechanism includes a connecting sleeve 321, an electric push rod 322, and a piston 323; the upper end of the connecting sleeve 321 is provided with a connecting flange 3211 corresponding to the bottom flange ring 13; the lower end of the connecting sleeve 321 is connected to the fixed end of the electric push rod 322; the piston 323 is coaxially fixed to the telescopic end of the electric push rod 322; the outer diameter of the piston 323 corresponds to the inner diameter of the tube body 11; at the sedimentation position, the sedimentation cup 35 is connected to the bottom of the water flow pipe 31 through the quick-release clamp 36.

[0082] Compared with the prior art, the present invention provides a system for accurately simulating the natural sedimentation environment of silt under different water pressures and the actual erosion rate of riverbed silt in a laboratory environment. The collected consolidated silt samples can be repeatedly used, which saves time, labor and cost. The sedimentation device and the scouring device are in the same laboratory, which can reduce the transportation time, reduce the change of consolidated silt, ensure the accuracy and representativeness of the experiment, and simulate the sedimentation environment of consolidated silt at the bottom of rivers, lakes and reservoirs that does not exist in reality, so as to expand the sampling range of experimental samples. During the scouring experiment, it can ensure that the top of the consolidated silt is always flush with the bottom wall of the water flow pipe 31 during the experiment, and can adapt to the consolidated silt state at different river water flow rates, thereby effectively eliminating the experimental errors caused by tilting or accumulation, and can deduce the erosion rate according to the pushing speed of the consolidated silt at different water flow rates.

[0083] The top flange 22 is also equipped with a pressure gauge 223 which can detect the pressure inside the pressure-resistant pipe 1 .

[0084] The top flange 22 is also equipped with a manual pressure relief valve 224 as an alternative solution for relieving pressure of the pressure-resistant pipe 1 .

[0085] The sedimentation device also includes an air compressor, an air tank with a boosting valve, and a pressure regulating valve 28; the switch valve 26 uses a pneumatic hand-pull valve; the output end of the air compressor is connected to the control pipeline 25 and the inlet of the air tank with a boosting valve at the same time; the outlet of the air tank with a boosting valve is connected to the high-pressure pipeline 24 through the pressure regulating valve 28; the gas output by the air compressor directly participates in the operation of the pilot check valve 221; the air tank pressurizes the gas output by the air compressor to meet the simulated underwater pressure.

[0086] The sedimentation device also includes a water receiving tank 27; the water receiving tank 27 is arranged below the installation position and is used to receive water leaked when the pressure-resistant pipe 1 is disassembled to ensure the cleanliness of the experimental environment.

[0087] The complete set of river, lake and reservoir bottom consolidation sediment scour experiment system also includes a sealing ring 4 corresponding to the pressure-resistant pipe 1; the sealing ring 4 is respectively installed on the top and bottom of the pressure-resistant pipe 1; the top flange ring 12 and the bottom flange ring 13 are both against the sealing ring 4; the sealing ring 4 can ensure the sealing degree of the top and bottom of the pressure-resistant pipe 1, and reduce the processing requirements of the top flange plate 22, the bottom flange plate 23, the top flange ring 12, the bottom flange ring 13, and the connecting flange 3211.

[0088] Observation windows 312 are provided on both sides of the push position of the water flow pipe 31, so that the water flow erosion situation can be directly observed.

[0089] A clamping plate 313 is fixedly connected to the bottom of the push-up position of the water flow pipe 31; a clamping groove 3131 corresponding to the outer circle of the top flange 22 is provided at the center of the bottom of the clamping plate 313; the clamping groove 3131 limits the pressure-resistant pipe 1 to ensure that the pressure-resistant pipe 1 is accurately positioned; a through hole 3132 corresponding to the inner wall of the pipe body 11 is provided in the center of the clamping plate 313; the through hole 3132 ensures the connection between the pressure-resistant pipe 1 and the water flow pipe 31.

[0090] The fixing plate 331 is provided with a semi-long hole 3311 corresponding to and matching the tube body 11 , which is beneficial to the positioning of the pressure-resistant tube 1 .

[0091] The flushing device also includes a support frame 37; the support frame 37 is arranged at one end of the water flow pipe 31; the settlement position is located between the support frame 37 and the flushing frame 33; the support frame 37 and the flushing frame 33 together support the water flow pipe 31 to ensure the stability of the water flow pipe 31.

[0092] Embodiment 2: Embodiment 2 is basically the same as Embodiment 1, and the similarities are not repeated here. The difference is that a vent hole 3212 is provided on the side wall of the connecting sleeve 321 to prevent a negative pressure state from occurring under the piston 323, so that the piston 323 can be pushed smoothly.

[0093] Embodiment 3, an experimental method of a complete set of river, lake and reservoir bottom consolidation sediment scouring experimental system as described in Embodiment 1 comprises the following steps:

[0094] S1 Preparation of consolidated sediment

[0095] 1.1 Mix soil sample and water

[0096] After drying the soil sample collected on site, mix it with water in a certain proportion; repeatedly stir the soil sample and water until there is no moisture on the surface of the soil sample;

[0097] 1.2 Fill and install the pressure pipe 1 on the sedimentation device

[0098] Use bolted joints to tightly connect the bottom flange 23 and the bottom flange ring 13; fill the mixed soil sample and water into the pressure pipe 1, and smooth the top of the soil sample after each filling until the top of the soil sample is at a specified distance h from the top of the pressure pipe 1. 初 ; The total length of the pressure-resistant pipe 1 is L; fill the pressure-resistant pipe 1 with water; use bolted connectors to tightly connect the top flange 22 and the top flange ring 12; use the hanging plate 14 to be mounted on the U-shaped card 211;

[0099] 1.3 Pressurize the pressure tube 1

[0100] Connect the control valve 222 to the high-pressure pipeline 24; connect the switch valve 26 to the control pipeline 25; open the control valve 222 and close the switch valve 26; the high-pressure gas in the high-pressure pipeline 24 enters the pressure-resistant pipe 1 through the control valve 222, squeezes the water, and makes the water act on the soil sample; the pressure of the high-pressure gas is equivalent to the set underwater pressure of the consolidated sediment;

[0101] 1.4 Determine the density coefficient of consolidated sediment

[0102] At a specific time every day, close the control valve 222 to prohibit high-pressure gas from entering the pressure-resistant pipe 1; open the control valve 222 to allow the control port of the pilot check valve 221 to enter the control gas flow, and the high-pressure gas in the pressure-resistant pipe 1 is connected to the outside to relieve the pressure in the pressure-resistant pipe 1; after the pressure relief is completed, remove the top flange 22 and measure the distance h from the top of the soil sample to the top of the pressure-resistant pipe 1 测 ; Calculate and record the density coefficient of the consolidated sediment on that day: After the measurement is completed, the top flange 22 is reinstalled, the switch valve 26 is closed, the control valve 222 is opened, and the pressure-resistant pipe 1 is continuously pressurized;

[0103] 1.5 Formation of consolidated sediment

[0104] After a certain number of days, the control valve 222 is closed and the switch valve 26 is opened to release the pressure; after the pressure release is completed, the pressure pipe 1 is removed; the top flange 22 and the bottom flange 23 are removed; the consolidated sediment is filled in the pressure pipe 1; the consolidated sediment is sampled using a ring knife, and the dry bulk density γ of the consolidated sediment in the pressure pipe 1 is obtained after drying;

[0105] S2 flushing test

[0106] 2.1 Install the pressure tube 1 and the sedimentation cup 35 on the flushing device

[0107] Weigh the sedimentation cup 35, recorded as m0; use bolted connectors to seal the connection flange 3211 with the bottom flange ring 13; use the height adjustment bolt 34 to establish a threaded connection with the height adjustment threaded hole 151; lift the pressure tube 1 so that the threaded end of the height adjustment bolt 34 abuts against the fixing plate 331; adjust the horizontal position of the pressure tube 1 so that the pressure tube 1 is centered with the top push through hole 311; rotate the height adjustment bolt 34 to lift the pressure tube 1; the top flange ring 12 abuts tightly against the bottom of the top push position; use the quick-release clamp 36 to install the sedimentation cup 35 to the sedimentation position and connect it to the water flow pipe 31;

[0108] 2.2 Start-up experiment

[0109] Start the electric push rod 322 to make the top of the fixed mud rise to the position flush with the bottom of the water flow pipe 31; slowly fill the water flow pipe 31 with water; continue to start the electric push rod 322 to make the top of the fixed mud emerge in the water flow pipe 31; slowly increase the water flow velocity in the water flow pipe 31 until the water flow in the water flow pipe 31 just hits the top of the fixed mud that has emerged through the observation window 312; the mud is peeled off from the top surface of the fixed mud in the form of small clumps by the water flow; record the water flow velocity at this time as the critical starting flow velocity v 起动 ; Note the lifting speed v of the electric push rod 322 H ;

[0110] 2.3 Scouring experiment

[0111] Increase the flow rate of the water flow until you can see through the observation window 312 that the water flow in the water flow pipe 31 has just washed away the top of the newly exposed solidified sand, so that the top of the solidified sand is always flush with the lower wall of the water flow pipe 31; the sand is lumped or smoke-like and peeled off from the top surface of the solidified sand in large pieces; record the water flow rate at this time as the full starting flow rate v 冲刷 ;

[0112] 2.4 Sedimentation experiment

[0113] When the electric push rod 322 is extended to the limit position, the consolidated sediment in the pressure-resistant tube 1 is pushed into the water flow pipe 31 and washed away by the water flow; stop supplying water to the water flow pipe 31, and wait for the water in the water flow pipe 31 to be drained out; number the sedimentation cups 35 according to the distance from the observation window 312; remove each sedimentation cup 35 through the quick-release clamp 36; put the sedimentation cup 35 filled with sediment into a constant temperature oven, heat and dry it for 6-8 hours to remove the moisture in the sediment; after natural cooling, weigh the sedimentation cup 35 and the sediment in the sedimentation cup 35;

[0114] The sampling and drying process of consolidated sediment includes the following steps:

[0115] 1) Sampling samples

[0116] Shovel the top of the consolidated mud and sand; press the ring knife vertically and steadily into the consolidated mud and sand; the volume of the ring knife is V; when pressing the ring knife in, it is strictly forbidden to shake the ring knife left and right; after the consolidated mud and sand emerge from the upper end of the ring knife, dig out the consolidated mud and sand around the ring knife, and then take out the ring knife and the consolidated mud and sand carried by the ring knife; use the soil scraper to scrape off the excess consolidated mud and sand at the upper and lower ends of the ring knife, so that the consolidated mud and sand are aligned with the ring knife from top to bottom; use the bottom cover to seal the lower end of the ring knife; cover the upper end of the ring knife with a cover; wipe off the consolidated mud and sand on the outer periphery of the ring knife;

[0117] 2) Drying and weighing the consolidated sand

[0118] The container of the constant temperature oven is weighed and recorded as m1; the consolidated sand in the ring knife is spread flat on the container of the constant temperature oven; the container containing the consolidated sand is placed in the constant temperature oven and heated and dried for 6 to 8 hours; after the sample consolidated sand and the container are cooled, the consolidated sand and the container are weighed and recorded as m2; the dry weight density of the consolidated sand is calculated to be

[0119] 2.5 Processing experimental data

[0120] The experimental data obtained during the experiment are counted and calculated. The experimental data include the flushing rate S r , critical starting shear stress τ 临界 and the difference flow rate Δυ;

[0121] The process of sediment being washed away from the consolidated state in the experiment can be regarded as the scouring and deposition process of sediment on the riverbed, so the formula of riverbed scouring rate is referred to: Among them, S r is the riverbed scouring rate, in kg / m 2 s; W s is the weight of the consolidated sediment reduced during the water flow scouring process, in kg; A is the area scoured by the water flow, in m 2 ; t is the water flow flushing time, in seconds; γ is the dry bulk density of the consolidated sediment in the pressure pipe 1, in kg / m 3 ; ν H is the lifting speed of the electric push rod 322, in m / s;

[0122] Based on the Prandtl-Karman study on turbulent flow, the turbulent smooth region satisfies the universal friction coefficient formula, and the friction velocity U * Relationship with wall shear stress τ0: Where ρ is the density of water; friction velocity U * Relationship with average flow velocity ν0: Where λ is the head loss coefficient along the way;

[0123] The two relations are combined and transformed accordingly, and can be transformed into: Where λ can be calculated by the Nicolaz formula; the Nicolaz formula is: Where R e is the Reynolds number, which is a unitless value used in fluid mechanics to describe the flow characteristics of a fluid; the average flow velocity ν0 is ν 起动 The calculated wall shear stress τ0 is the critical starting shear stress τ 临界 ;

[0124] The calculation formula of the differential flow rate Δυ is Δν=ν 冲刷 -ν 起动 ;

[0125] After each sedimentation cup 35 is numbered according to the distance from the observation window 312, the dry bulk density of the sediment in each sedimentation cup 35 can be measured by m i -m0 is used for calculation; because the inner diameters of the pressure-resistant pipes 1 are uniform, the settling of the washed sediment in each sedimentation cup 35 can be reflected by the dry bulk density of the sediment in the sedimentation cup 35.

[0126] According to the above scheme, the inventors set up multiple sampling points in the extension section of the Yellow River from Tongguan to Sanmenxia, ​​collected different soil samples and brought them to the laboratory for experiments; different sampling points were numbered differently; the longitude and latitude coordinates of the HY12 sampling point were (111.184134, 34.796563), the longitude and latitude coordinates of the HY22 sampling point were (110.965580, 34.698570), the longitude and latitude coordinates of the HY30 sampling point were (110.751117, 34.644120), the longitude and latitude coordinates of the HY36 sampling point were (110.479943, 34.599409), and the longitude and latitude coordinates of the HY41 sampling point were (110.287307, 34.609599); the samples collected at each sampling point were also named with the sampling point number in the laboratory, and were dried before the experiment.

[0127] During the experiment, the inventors grouped the sedimentation barrels according to the water depths of 20m, 50m, 100m and 150m; after calculating the underwater pressure at 20m, 50m, 100m and 150m, high-pressure airflow of corresponding pressure was input to each group; each group was numbered according to the pressurization days of 1 day, 2 days, 3 days, 4 days, 5 days, 7 days, 10 days, 14 days, 18 days, 22 days, 26 days and 30 days, and experiments were carried out separately.

Claims

1. A complete set of river, lake and reservoir bottom consolidation sediment scour experiment system, characterized in that: It includes pressure-resistant pipe, settling device and flushing device; The pressure-resistant pipe includes a pipe body, a top flange ring, a bottom flange ring, a hanging plate, and a height-adjusting plate; the top flange ring and the bottom flange ring are fixedly connected to the top and bottom of the pipe body respectively; the height-adjusting plate is radially arranged in the middle of the pipe body, and is symmetrically provided with a plurality of height-adjusting threaded holes; the hanging plate is symmetrically fixedly connected to the middle of the pipe body; The settling device includes a settling frame, a top flange, a bottom flange, a high-pressure pipeline, a control pipeline, and a switch valve; the settling frame is provided with a number of installation positions; U-shaped clips corresponding to and matching the hanging plates are symmetrically provided on the left and right sides of each installation position; the top flange matches the top flange ring, and is provided with a pilot check valve and a control valve; the control valve is connected to the high-pressure pipeline; the outlet of the pilot check valve is installed on the top flange, the inlet is connected to the outside, and the control port is connected to the control pipeline through the switch valve; the bottom flange matches the bottom flange ring; The flushing device includes a water pipe, a pushing mechanism, a flushing frame, a height adjustment bolt, a settlement cup, and a quick-release clamp; flushing water flows into the water pipe; the water pipe is provided with a pushing position and a settlement position in sequence along the direction of the flushing water flow; the flushing frame and the pushing mechanism are both arranged below the pushing position; the water pipe at the pushing position is provided with a pushing through hole corresponding to the inner hole of the pressure-resistant pipe; the top of the flushing frame is connected to the bottom of the water pipe, and a fixing plate is provided in the middle; the threaded end of the height adjustment bolt is abutted against the top of the fixing plate; the threaded section of the height adjustment bolt is threadedly matched with the height adjustment threaded hole; the pushing mechanism includes a connecting sleeve, an electric push rod, and a piston; the upper end of the connecting sleeve is provided with a connecting flange corresponding to the bottom flange ring; the lower end of the connecting sleeve is connected to the fixed end of the electric push rod; the piston is coaxially fixed to the telescopic end of the electric push rod; the outer diameter of the piston corresponds to the inner diameter of the tube body; at the settlement position, the settlement cup is connected to the bottom of the water pipe through a quick-release clamp.

2. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: A pressure gauge is also installed on the top flange.

3. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: The sedimentation device also includes an air compressor, an air storage tank with a boosting valve, and a pressure regulating valve; the switch valve uses a pneumatic hand-pull valve; the output end of the air compressor is connected to the control pipeline and the inlet of the air storage tank with a boosting valve at the same time; the outlet of the air storage tank with a boosting valve is connected to the high-pressure pipeline through the pressure regulating valve.

4. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: It also includes a sealing ring that matches the pressure-resistant pipe; the sealing ring is respectively installed on the top and bottom of the pressure-resistant pipe; the top flange ring and the bottom flange ring are both against the sealing ring.

5. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: Observation windows are provided on both sides of the top push position of the water flow pipeline.

6. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: A clamping plate is fixedly connected to the bottom of the top push position of the water flow pipeline; a clamping groove corresponding to the outer circle of the top flange is arranged at the bottom center of the clamping plate; and a through hole corresponding to the inner wall of the pipe body is arranged at the center of the clamping plate.

7. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: The fixing plate is provided with a semi-long hole corresponding to the tube body.

8. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: The flushing device also includes a support frame; the support frame is arranged at one end of the water flow pipeline; and the settlement position is located between the support frame and the flushing frame.

9. The complete system for river, lake and reservoir bottom consolidation sediment scouring experiment according to claim 1 is characterized by: The side wall of the connecting sleeve is provided with ventilation holes.

10. An experimental method for the complete system for the river, lake and reservoir bottom consolidation sediment scour experiment according to claim 5, characterized in that: The following steps are involved: S1 Preparation of consolidated sediment 1.1 Mix soil sample and water After drying the soil sample collected on site, mix it with water in a certain proportion; repeatedly stir the soil sample and water until there is no moisture on the surface of the soil sample; 1.2 Fill and install the pressure pipe on the sedimentation device Use bolted joints to tightly connect the bottom flange plate and the bottom flange ring; fill the mixed soil sample and water into the pressure tube, and smooth the top of the soil sample after each filling until the top of the soil sample is at a specified distance h from the top of the pressure tube. 初 ; The total length of the pressure-resistant pipe is L; Fill the pressure-resistant pipe with water; Use bolted connectors to tightly connect the top flange plate and the top flange ring; Use hanging plate clips to install them on the U-shaped clips; 1.3 Add pressure to the pressure pipe Connect the control valve to the high-pressure pipeline; connect the switch valve to the control pipeline; open the control valve and close the switch valve; the high-pressure gas in the high-pressure pipeline enters the pressure-resistant pipe through the control valve, squeezes the water, and makes the water act on the soil sample; the pressure of the high-pressure gas is equivalent to the set underwater pressure of the consolidated sediment; 1.4 Determine the density coefficient of consolidated sediment At a specific time every day, close the control valve to prohibit high-pressure gas from entering the pressure-resistant pipe; open the control valve to allow the control port of the pilot check valve to enter the control gas flow, and the high-pressure gas in the pressure-resistant pipe is connected to the outside to relieve the pressure in the pressure-resistant pipe; after the pressure relief is completed, remove the top flange and measure the distance h from the top of the soil sample to the top of the pressure-resistant pipe 测 ; Calculate and record the density coefficient of the consolidated sediment for the day: After the measurement is completed, reinstall the top flange, close the switch valve, open the control valve, and continue to pressurize the pressure-resistant pipe; 1.5 Formation of consolidated sediment After a certain number of days, the control valve is closed and the switch valve is opened to release the pressure; after the pressure release is completed, the pressure pipe is removed; the top flange and the bottom flange are removed; the consolidated sediment is filled in the pressure pipe; the consolidated sediment in the pressure pipe is sampled using a ring knife, and the dry bulk density γ of the consolidated sediment in the pressure pipe is obtained after drying; S2 flushing test 2.1 Install the pressure tube and sedimentation cup on the flushing device Weigh the sedimentation cup and record it as m0; use bolted connectors to tightly connect the connecting flange and the bottom flange ring; use height adjustment bolts to establish a threaded connection with the height adjustment threaded holes; lift the pressure tube so that the threaded end of the height adjustment bolts abuts against the fixed plate; adjust the horizontal position of the pressure tube so that the pressure tube and the top push through hole are aligned; rotate the height adjustment bolts to lift the pressure tube; the top flange ring abuts tightly against the bottom of the top push position; use quick-release clamps to install the sedimentation cup to the sedimentation position and connect it to the water flow pipeline; 2.2 Start-up experiment Start the electric push rod to make the top of the fixed sediment rise to the position flush with the bottom of the water flow pipe; slowly fill the water flow pipe with water; continue to start the electric push rod to make the top of the fixed sediment emerge in the water flow pipe; slowly increase the water flow velocity in the water flow pipe until you see through the observation window that the water flow in the water flow pipe just hits the top of the exposed fixed sediment; the sediment is peeled off from the top surface of the consolidated sediment in the form of small clumps by the water flow; record the water flow velocity at this time as the critical starting flow velocity v 起动 ; Note the lifting speed v of the electric push rod H ; 2.3 Scouring experiment Increase the water flow rate until you can see through the observation window that the water flow in the water flow pipe has just washed away the top of the newly exposed solidified sand, so that the top of the solidified sand is always flush with the lower wall of the water flow pipe; the sand is lumped or smoke-like and peeled off from the top surface of the solidified sand; record the water flow rate at this time as the full starting flow rate v 冲刷 ; 2.4 Sedimentation experiment When the electric push rod is extended to the limit position, the consolidated sediment in the pressure-resistant tube is pushed into the water pipe and washed away by the water flow; stop supplying water to the water pipe and wait for the water in the water pipe to be drained out; number the sedimentation cups according to the distance from the observation window; remove each sedimentation cup by the quick-release clamp; put the sedimentation cup filled with sediment into a constant temperature oven and heat and dry it for 6-8 hours to remove the moisture in the sediment; after natural cooling, weigh the sedimentation cup and the sediment in the sedimentation cup, record it as m i ; 2.5 Processing experimental data Statistics and calculation of experimental data obtained during the experiment.

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