Test method for simulating surface desilting of gravel foundation bed

Abstract

The invention discloses a test method for simulating surface desilting of a gravel foundation bed, which comprises the following steps: paving graded broken stones and sludge with specific volume weight at the bottom of a test water tank, and mounting a desilting head, a dredge pump, an electromagnetic flowmeter and a sludge layer thickness measuring instrument; clear water is added into a test water tank, a dredge pump, a desilting head and an advancing mechanism are started in sequence, the pipeline flow collected by an electromagnetic flowmeter is collected in real time through a data collection system, clear water is continuously added into the test water tank in the desilting test process, and the height of the water level in the test water tank is kept unchanged; after the desilting test is finished, the dredge pump, the desilting head and the advancing mechanism are stopped in an inverted sequence, test water is discharged, and the desilting amount is determined according to the thickness of a mud layer of the silt laid in the test water tank and the thickness of a mud layer of the remaining silt; and the dredging effect of the dredging head is evaluated according to the relation between the pipeline flow and the preset dredge pump flow, the rotating speed of the dredging head and the advancing speed of the advancing mechanism and the dredging amount.

Description

Technical Field

[0001] The invention relates to the technical field of silt removal on the surface of a gravel bed of an immersed tube tunnel, and in particular to a test method for simulating silt removal on the surface of a gravel bed. Background Art

[0002] Underwater tunnels can effectively solve the problems of crossing waters and shipping in large waters, while reducing the impact on the surrounding environment. Therefore, large-scale underwater tunnel projects across the sea and inland rivers are increasing day by day. Due to the unique economic and technical advantages of immersed tube tunnels, and with the gradual resolution and improvement of key technical issues in the design and construction of immersed tube tunnels, immersed tube tunnels have attracted the attention of more and more countries and have gradually become the preferred construction method for large underwater tunnel projects. In the construction of immersed tube tunnels, in order to make the surface of the tunnel foundation trench flat, foundation treatment is usually required. Commonly used foundation treatment methods include pre-laying method and post-filling method. The pre-laying method refers to laying a gravel base bed before the immersed tube is sunk, which has the advantages of small settlement and high construction efficiency. However, when the pre-laying method is used for construction, due to the high sand content in the water area, the disturbance of the water flow will cause problems, affect normal construction, seriously restrict the construction progress, and cause economic losses. Therefore, it is necessary to remove the silt on the surface of the gravel base bed during the pre-laying method.

[0003] Traditional dredging often uses pump suction or water flushing to remove the silt from the base bed. However, the top surface of the leveled base bed is composed of crushed stone leveling materials with smaller particles. Due to the uneven action of the pump suction or water flushing force, the dredging is not thorough or the crushed stone is displaced, resulting in poor surface accuracy of the base bed, which makes it impossible to install the subsequent immersed tube. For example: The publication date is: 2021-01-29, the publication number is CN212427289U, and the name is: Utility model of mechanical and hydraulic double-acting precision scraping and dredging head and dredging device, which uses scraping blades to stir the silt, so that the silt and water are mixed to form a mud-water mixture with strong fluidity. At the same time, the scraping blades rotate to generate water flow force that drives the mud-water mixture to move toward the central axis of the spiral conveying mechanism, and cooperates with the positive rotation of the left and right spiral blades to transport the mud-water mixture to the docking section, and transport the mud-water mixture to the mud outlet corresponding to the docking section for discharge, thereby achieving base bed dredging. The existing dredging devices have not studied the dredging structural parameters and operating parameters, so it is impossible to obtain reasonable structural parameters and operating parameters, making it difficult to match the operating parameters. Summary of the invention

[0004] The purpose of this application is to provide a test method for simulating dredging of a gravel bed surface in order to address the technical defects in the prior art.

[0005] The technical solution adopted to achieve the purpose of this application is:

[0006] A test method for simulating dredging of a gravel bed surface comprises the following steps:

[0007] Step 1: Lay graded gravel on the bottom of the test water tank, and then perform manual leveling after paving;

[0008] Step 2, the dredging head is fixedly connected to the traveling mechanism on the guide rail of the test water tank through the beam, and the dredging head is adjusted to be horizontal, the dredging pump is fixedly installed on the outside of the test water tank, the mud outlet of the dredging head is connected to the water inlet of the dredging pump, the water outlet of the dredging pump is connected to one end of the electromagnetic flowmeter, and then the other end of the electromagnetic flowmeter is connected to the mud storage box, and the mud layer thickness measuring instrument is installed in the test water tank;

[0009] Step 3, putting soil, fine sand and clean water into the barrel of the sludge generating device in a certain proportion, fully mixing and soaking the soil and fine sand, stirring the fully mixed and soaked soil and fine sand in the barrel with a sludge agitator, and taking samples and measuring with a density meter, and generating sludge with a specific bulk density by continuously adjusting the proportion of soil, fine sand and water;

[0010] Step 4, evenly spread the sludge generated in step 3 into the test water tank, measure the thickness of the mud layer of the sludge laid in the test water tank using a mud layer thickness measuring instrument, and then lay a geotextile on the surface of the mud layer of the sludge to prevent the sludge from churning when adding clean water into the test water tank;

[0011] Step 5, add clean water to the test water tank through the water supply pipe to raise the water level to a preset height, take out the geotextile laid on the surface of the mud layer of the silt, and lower the dredging head to a preset height by turning the hand wheel forward, and then start the dredging pump, the dredging head and the traveling mechanism in sequence to start the dredging test. During the dredging test, the pipeline flow is collected by the electromagnetic flowmeter, and the pipeline flow collected by the electromagnetic flowmeter is collected in real time by the data acquisition system. According to the pipeline flow and the preset dredging pump flow, the rotation speed of the dredging head and the traveling speed of the traveling mechanism, the relationship between the pipeline flow and the dredging pump flow, the rotation speed of the dredging head and the traveling speed of the traveling mechanism is established;

[0012] Step 6: During the dredging test, clean water is continuously added to the test water tank through the water supply pipe to ensure that the water level in the test water tank remains unchanged. After the dredging test is completed, the dredging pump, the dredging head and the travel mechanism are stopped in reverse order, and the hand wheel is cranked in reverse to raise the dredging head to the initial height;

[0013] Step 7, slowly drain the test water in the test water tank through the drain port, measure the thickness of the mud layer of the remaining sludge in the test water tank again with the mud layer thickness measuring instrument, determine the dredging amount according to the mud layer thickness of the sludge laid in the test water tank and the mud layer thickness of the remaining sludge in the test water tank, and then evaluate the dredging effect of the dredging head according to the relationship between the pipeline flow rate and the dredging pump flow rate, the rotation speed of the dredging head and the travel speed of the travel mechanism, and the dredging amount;

[0014] Step 8, adjusting the flow rate of the dredging pump, the rotation speed of the dredging head and the travel speed of the traveling mechanism, repeating steps 3-7, and measuring the dredging effect of the dredging head under different power parameter conditions;

[0015] Step 9, replace the dredging head with different diameters and different pitches, repeat steps 3-8, and measure the dredging effect of the dredging head under different structural parameters and operating parameters.

[0016] In the above technical solution, an underwater video recording device is installed in the test water tank, and the process of the dredging test is recorded by the underwater video recording device during the dredging test.

[0017] In the above technical solution, in step 2, the mud outlet of the dredging head and the water inlet of the mud suction pump are connected through a steel wire hose; the water outlet of the mud suction pump is connected to one end of the electromagnetic flowmeter through a fixed iron pipe; the other end of the electromagnetic flowmeter is connected to the mud storage tank through a fixed iron pipe.

[0018] In the above technical solution, the laying thickness of the sludge in the test water tank in step 4 is 10 cm.

[0019] In the above technical solution, the bottom of the dredging head is 1 cm away from the top of the graded gravel.

[0020] In the above technical solution, the expression of the relationship between the pipeline flow rate and the dredge suction pump flow rate, the rotation speed of the dredging head and the travel speed of the travel mechanism is as follows:

[0021] Q1=f(q1、n1、v1)

[0022] In the formula, Q1 represents the pipeline flow collected by the electromagnetic flowmeter, q1 represents the preset dredge suction pump flow, n1 represents the preset rotation speed of the dredging head, and v1 represents the preset travel speed of the travel mechanism.

[0023] In the above technical scheme, during the dredging test, the gear at the bottom of the first motor cooperates with the rack formed on the side of the guide rail to drive the traveling mechanism to move along the direction of the guide rail; the transmission wheel of the second motor is connected to the first transmission rod, driving the first transmission rod and the first synchronous pulley on the first transmission rod to rotate, and the second synchronous pulley is driven to rotate through the first synchronous belt, thereby driving the rotating shafts on both sides of the dredging head to rotate, driving the dredging head to rotate, and using the dredging head to cut the sludge in the test water tank, so that the cut sludge is mixed with clean water to form a mud-water mixture with strong fluidity, and the mud-water mixture formed in the dredging head is pumped out by a mud suction pump and stored in a mud storage box.

[0024] In the above technical solution, the running speed of the traveling mechanism is adjustable, and the adjustable range is 0 to 2 m / min.

[0025] In the above technical solution, adjusting the flow rate of the dredge suction pump in step 8 includes: adjusting the flow rate of the dredge suction pump by a frequency converter equipped with the dredge suction pump.

[0026] In the above technical solution, the material of the side of the test water tank is glass, and the material of the bottom is stainless steel.

[0027] The beneficial effects of the present invention are as follows:

[0028] The test method of the present invention can realize the study of the dredging structural parameters and the operating parameters, so that reasonable structural parameters and operating parameters can be obtained, and the problem that the operating parameters of the existing dredging devices are difficult to match is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 It is a structural diagram of the test system for simulating dredging of the gravel bed surface of the present invention.

[0031] Figure 2 It is a structural diagram of the sludge generating device of the present invention.

[0032] Figure 3 The present invention is a flow chart of the test method for simulating gravel bed surface silt removal.

[0033] In the figure, 1-test water tank, 1-1-guide rail, 1-1-1-rack, 1-2-travel mechanism, 1-2-1-first motor, 1-2-2-support plate, 1-2-3-second motor, 1-2-4-first transmission rod, 1-2-5-slideway, 1-2-6-screw, 1-2-7-second transmission rod, 1-2-8-handwheel, 1-2-9-beam, 1-2-10-third transmission rod, 1 -2-11-second transmission wheel, 1-2-12-third transmission wheel, 1-2-13-second synchronous belt, 1-3-drainage outlet, 1-4-vertical driving mechanism, 3-dredging head, 3-1-mud outlet, 4-mud generating device, 4-1-barrel body, 4-2-mud agitator, 4-3-densitometer, 4-4-mobile bracket, 4-4-1-third motor, 4-4-2-universal wheel, 4-5-bracket. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments.

[0035] A test system for simulating the desilting of a gravel bed surface, see Figure 1 , including a test water tank 1, a sludge generating device 4, a sludge storage box, a dredging head 3, a sludge suction pump, an electromagnetic flowmeter, a mud layer thickness measuring instrument, a data acquisition system and an underwater video recording device. The test water tank 1 is provided with drain ports 1-3 for discharging the test water in the test water tank 1.

[0036] The test water tank 1 has a size of 5m×1.5m×1.1m, its side is made of glass, and its bottom is made of stainless steel. The running speed of the traveling mechanism 1-2 is adjustable within a range of 0 to 2m / min.

[0037] Guide rails 1-1 are installed on the cross beams on both sides of the test water tank 1, and racks 1-1-1 are formed on the sides of the guide rails 1-1; a traveling mechanism 1-2 is arranged on the guide rails 1-1, and a first motor 1-2-1 is fixedly installed on the side of the traveling mechanism 1-2, and a gear cooperating with the rack 1-1-1 is arranged at the bottom of the first motor 1-2-1, so as to drive the traveling mechanism 1-2 to move along the direction of the guide rails 1-1.

[0038] The traveling mechanism 1-2 is provided with a vertical driving mechanism 1-4, and the vertical driving mechanism 1-4 is fixedly connected to the dredging head 3 through the beam 1-2-9, and is used to drive the dredging head 3 to be lifted or lowered; the vertical driving mechanism 1-4 includes two symmetrically arranged vertical slideways 1-2-5, a lead screw 1-2-6 and a hand wheel 1-2-8, and a support plate 1-2-2 is slidably installed on the slideway 1-2-5, and the support plate 1-2-2 is fixedly connected to the dredging head 3 through the beam 1-2-9, and a second motor 1-2-3 is fixedly installed on one side of the support plate 1-2-2, and is used to drive the dredging head 3 to be lifted or lowered. The dredging head 3 rotates; a first transmission wheel is horizontally arranged at one end of the second motor 1-2-3, and a first transmission rod 1-2-4 is penetrated at the upper end of the beam 1-2-9, and the first transmission wheel is transmission-connected with the first transmission rod 1-2-4; two first synchronous pulleys are arranged on the first transmission rod 1-2-4, and second synchronous pulleys are coaxially arranged on the rotating shafts on both sides of the dredging head 3, and the first synchronous pulley and the second synchronous pulley are transmission-connected by the first synchronous belt (the beam 1-2-9 is a hollow structure, and the first synchronous pulley and the second synchronous pulley are both located inside the beam 1-2-9, so they cannot be Figure 1), so that the second motor 1-2-3 drives the dredging head 3 to rotate, and the dredging head 3 is used to cut the silt in the test water tank 1, and the cut silt is mixed with clean water to form a mud-water mixture with strong fluidity; the lead screw 1-2-6 is provided with a lead screw nut, and the lead screw nut is fixedly connected to the support plate 1-2-2; the handwheel 1-2-8 is fixedly installed on the outer side of the traveling mechanism 1-2, and the handwheel 1-2-8 is transmission-connected with the lead screw 1-2-6, and the lead screw 1-2-6 is driven to rotate by the hand-cranked handwheel 1-2-8, so that the lead screw nut drives the support plate 1-2-2 to move along the direction of the slideway 1-2-5, thereby realizing the lifting and lowering of the dredging head 3 (the forward hand-cranked handwheel 1-2-8 realizes the lowering of the dredging head 3, and the reverse hand-cranked handwheel 1-2-8 realizes the lifting of the dredging head 3). The sludge suction port of the dredging head 3 is always in the sludge layer; the dredging head 3 of this embodiment is the dredging head 3 disclosed in the public document with publication number CN212427289U, and the rotation speed of the dredging head 3 is adjustable within the adjustment range of 0 to 50 r / min.

[0039] The handwheel 1-2-8 is connected to the lead screw 1-2-6 through a driving device, and the driving device includes a second transmission rod 1-2-7 and a third transmission rod 1-2-10. One end of the second transmission rod 1-2-7 is fixedly connected to the handwheel 1-2-8, and the other end of the second transmission rod 1-2-7 is connected to the third transmission rod 1-2-10. The top of the third transmission rod 1-2-10 is provided with a second transmission wheel 1-2-11, and the top of the lead screw 1-2-6 is provided with a A third transmission wheel 1-2-12 is provided, and the second transmission wheel 1-2-11 and the third transmission wheel 1-2-12 are connected through the second synchronous belt 1-2-13. The second transmission rod 1-2-7 is driven to rotate by the hand-cranked handwheel 1-2-8, and the third transmission rod 1-2-10 is driven to rotate, and then the lead screw 1-2-6 is driven to rotate through the second synchronous belt 1-2-13, so that the lead screw nut drives the support plate 1-2-2 to move along the direction of the slideway 1-2-5, so as to realize the lifting and lowering of the dredging head 3.

[0040] See also Figure 2The sludge generating device 4 includes a plurality of barrels 4-1, a sludge agitator 4-2 and a plurality of densitometers 4-3. Each densitometer 4-3 is fixedly mounted on the side of the barrel 4-1 through a bracket 4-5. The sludge agitator 4-2 is suspended in the barrel 4-1 through a mobile bracket 4-4, and is used to agitate the soil and fine sand that are fully mixed and soaked in a certain proportion in the barrel, and to take samples and measure them using a densitometer. By continuously adjusting the proportion of soil, fine sand and water, sludge with a specific bulk density is generated. A second motor 4-4-1 is fixedly mounted on the mobile bracket 4-4, and is used to drive the sludge agitator 4-2 to rotate and agitate the soil and fine sand in the barrel. The bulk density of the sludge is set according to the test requirements. Universal wheels 4-4-2 are symmetrically arranged at the bottom of the mobile bracket 4-4, and are used to drive the sludge agitator 4-2 to move to the barrel 4-1 where sludge needs to be generated.

[0041] The dredge suction pump is fixedly installed outside the test water tank 1, and the mud outlet 3-1 of the dredging head 3 is connected to the dredge suction pump through a steel wire hose. The dredge suction pump is equipped with a frequency converter for adjusting the flow of the dredge suction pump.

[0042] The water outlet of the sludge suction pump is connected to one end of an electromagnetic flowmeter through a fixed iron pipe, and the electromagnetic flowmeter records the pipeline flow; the other end of the electromagnetic flowmeter is connected to a mud storage box through a fixed iron pipe, and the mud sucked out by the sludge suction pump is received through the mud storage box. The sludge suction pump is a centrifugal pump.

[0043] The mud layer thickness measuring instrument and the underwater video recording device are respectively installed in the test water tank 1. The mud layer thickness measuring instrument is used to measure the mud layer thickness of the silt laid in the test water tank 1 before the test and the mud layer thickness of the remaining silt in the test water tank 1 after the test; the underwater video recording device is used to record the dredging test process of the dredging head 3.

[0044] A test method for simulating the desilting of a gravel bed surface, see Figure 3 , including the following steps:

[0045] Step 1: Lay graded gravel on the bottom of the test water tank 1, and then perform manual leveling after laying.

[0046] The graded crushed stone is consistent with the one on site, and the laying thickness of the graded crushed stone is preferably 20 cm.

[0047] Step 2, fix the dredging head 3 (the diameter of the dredging head is d1 and the pitch is S1 at this time) to the traveling mechanism 1-2 on the guide rail 1-1 of the test water tank 1 through the beam 1-2-9, and adjust the dredging head 3 to make it horizontal, fix the dredging pump on the outside of the test water tank 1, connect the mud outlet 3-1 of the dredging head 3 with the water inlet of the dredging pump, connect the water outlet of the dredging pump with one end of the electromagnetic flowmeter, and then connect the other end of the electromagnetic flowmeter to the mud storage box, and install the mud layer thickness measuring instrument in the test water tank 1.

[0048] In step 2, the mud outlet 3-1 of the dredging head 3 is connected to the water inlet of the mud suction pump through a steel wire hose; the water outlet of the mud suction pump is connected to one end of the electromagnetic flowmeter through a fixed iron pipe; the other end of the electromagnetic flowmeter is connected to the mud storage tank through a fixed iron pipe.

[0049] Step 3, put the soil, fine sand and clean water into the barrel 4-1 of the sludge generating device 4 in a certain proportion, fully mix and soak the soil and fine sand, use the sludge agitator 4-2 to stir the fully mixed and soaked soil and fine sand in the barrel 4-1, and use a density meter to take samples and measure, and generate sludge with a specific bulk density by continuously adjusting the proportion of soil, fine sand and water.

[0050] Among them, there are multiple barrel bodies 4-1, which can provide sufficient silt for the test of simulating dredging of the gravel base bed surface. The silt agitator 4-2 can be moved to the barrel body 4-1 where the fully mixed and soaked soil and fine sand need to be stirred through the movable bracket 4-4; the barrel bodies 4-1 of this embodiment are preferably 3, and a density meter 4-3 is fixedly installed on the side of each barrel body 4-1.

[0051] Step 4, evenly spread the silt generated in step 3 into the test water tank 1, use a mud layer thickness measuring instrument to measure the thickness of the mud layer in the test water tank 1, and then lay a geotextile on the surface of the mud layer to prevent the silt from churning when adding clean water into the test water tank 1.

[0052] The laying thickness of the sludge in the test water tank 1 in step 4 is preferably 10 cm.

[0053] Step 5, add clean water to the test water tank 1 through the water supply pipe to raise the water level to a preset height, remove the geotextile laid on the surface of the mud layer of the silt, and lower the dredging head 3 to a preset height by turning the hand wheel 1-2-8 forward (at this time, the bottom of the dredging head 3 is 1 cm away from the top of the graded gravel, so that the sludge suction port of the dredging head 3 is always in the mud layer of the silt), and then start the dredging pump, the dredging head 3 and the traveling mechanism 1-2 in sequence to start the dredging test. During the dredging test, the pipeline flow is collected by an electromagnetic flowmeter, and the pipeline flow collected by the electromagnetic flowmeter is collected in real time by the data acquisition system, and according to the pipeline flow and the preset dredging pump flow, the rotation speed of the dredging head 3 and the traveling speed of the traveling mechanism 1-2, a relationship between the pipeline flow and the dredging pump flow, the rotation speed of the dredging head 3 and the traveling speed of the traveling mechanism 1-2 is established.

[0054] The expression of the relationship between the pipeline flow rate, the dredge suction pump flow rate, the rotation speed of the dredging head 3 and the travel speed of the travel mechanism 1-2 is as follows:

[0055] Q1=f(q1、n1、v1)

[0056] In the formula, Q1 represents the pipeline flow collected by the electromagnetic flowmeter, q1 represents the preset flow of the dredge suction pump, n1 represents the preset rotation speed of the dredging head 3, and v1 represents the preset travel speed of the travel mechanism 1-2.

[0057] Specifically, during the dredging test, the gear at the bottom of the first motor 1-2-1 cooperates with the rack 1-1-1 formed on the side of the guide rail 1-1, driving the traveling mechanism 1-2 to move along the direction of the guide rail 1-1; the transmission wheel of the second motor 1-2-3 is connected to the first transmission rod 1-2-4, driving the first transmission rod 1-2-4 and the first synchronous pulley on the first transmission rod 1-2-4 to rotate, and driving the second synchronous pulley to rotate through the first synchronous belt, thereby driving the rotating shafts on both sides of the dredging head 3 to rotate, driving the dredging head 3 to rotate, and using the dredging head 3 to cut the sludge in the test water tank 1, so that the cut sludge is mixed with clean water to form a mud-water mixture with strong fluidity, and the mud-water mixture formed in the dredging head 3 is pumped out by a mud suction pump and stored in a mud storage box.

[0058] Step 6, during the dredging test, clean water is continuously added to the test water tank 1 through the water supply pipe to ensure that the water level in the test water tank 1 remains unchanged. After the dredging test is completed, the dredging pump, the dredging head 3 and the traveling mechanism 1-2 are stopped in reverse order, and the hand wheel 1-2-8 is cranked in reverse to lift the dredging head 3 to the initial height.

[0059] Step 7, slowly discharge the test water in the test water tank 1 through the drain port 1-3, and use the mud layer thickness measuring instrument to measure the mud layer thickness of the remaining sludge in the test water tank 1 again, and determine the dredging amount according to the mud layer thickness of the sludge laid in the test water tank 1 and the mud layer thickness of the remaining sludge in the test water tank 1, and then evaluate the dredging effect of the dredging head 3 according to the relationship between the pipeline flow and the dredging pump flow, the rotation speed of the dredging head 3 and the traveling speed of the traveling mechanism 1-2, and the dredging amount.

[0060] Step 8, adjust the flow rate of the dredging pump, the rotation speed of the dredging head 3 and the travel speed of the traveling mechanism 1-2, repeat steps 3-7, and measure the dredging effect of the dredging head 3 under different power parameter conditions.

[0061] Wherein, adjusting the flow rate of the sludge suction pump in step 8 includes: adjusting the flow rate of the sludge suction pump by a frequency converter equipped with the sludge suction pump.

[0062] Step 9, change different diameters (d n ), different pitches (S n ) and repeat steps 3-8 to measure the dredging effect of the dredging head 3 under different structural parameters and operating parameters.

[0063] Furthermore, an underwater video recording device is installed in the test water tank 1, and the process of the dredging test is recorded by the underwater video recording device during the dredging test.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A test method for simulating dredging of a gravel bed surface, characterized in that: The following steps are involved: Step 1: Lay graded gravel on the bottom of the test water tank, and then perform manual leveling after paving; Step 2, the dredging head is fixedly connected to the traveling mechanism on the guide rail of the test water tank through the beam, and the dredging head is adjusted to be horizontal, the dredging pump is fixedly installed on the outside of the test water tank, the mud outlet of the dredging head is connected to the water inlet of the dredging pump, the water outlet of the dredging pump is connected to one end of the electromagnetic flowmeter, and then the other end of the electromagnetic flowmeter is connected to the mud storage box, and the mud layer thickness measuring instrument is installed in the test water tank; Step 3, putting soil, fine sand and clean water into the barrel of the sludge generating device in a certain proportion, fully mixing and soaking the soil and fine sand, stirring the fully mixed and soaked soil and fine sand in the barrel with a sludge agitator, and taking samples and measuring with a density meter, and generating sludge with a specific bulk density by continuously adjusting the proportion of soil, fine sand and water; Step 4, evenly spread the sludge generated in step 3 into the test water tank, measure the thickness of the mud layer of the sludge laid in the test water tank using a mud layer thickness measuring instrument, and then lay a geotextile on the surface of the mud layer of the sludge to prevent the sludge from churning when adding clean water into the test water tank; Step 5, add clean water to the test water tank through the water supply pipe to raise the water level to a preset height, take out the geotextile laid on the surface of the mud layer of the silt, and lower the dredging head to a preset height by turning the hand wheel forward, and then start the dredging pump, the dredging head and the traveling mechanism in sequence to start the dredging test. During the dredging test, the pipeline flow is collected by the electromagnetic flowmeter, and the pipeline flow collected by the electromagnetic flowmeter is collected in real time by the data acquisition system. According to the pipeline flow and the preset dredging pump flow, the rotation speed of the dredging head and the traveling speed of the traveling mechanism, the relationship between the pipeline flow and the dredging pump flow, the rotation speed of the dredging head and the traveling speed of the traveling mechanism is established; Step 6: During the dredging test, clean water is continuously added to the test water tank through the water supply pipe to ensure that the water level in the test water tank remains unchanged. After the dredging test is completed, the dredging pump, the dredging head and the travel mechanism are stopped in reverse order, and the hand wheel is cranked in reverse to raise the dredging head to the initial height; Step 7, slowly drain the test water in the test water tank through the drain port, measure the thickness of the mud layer of the remaining sludge in the test water tank again with the mud layer thickness measuring instrument, determine the dredging amount according to the mud layer thickness of the sludge laid in the test water tank and the mud layer thickness of the remaining sludge in the test water tank, and then evaluate the dredging effect of the dredging head according to the relationship between the pipeline flow rate and the dredging pump flow rate, the rotation speed of the dredging head and the travel speed of the travel mechanism, and the dredging amount; Step 8, adjusting the flow rate of the dredging pump, the rotation speed of the dredging head and the travel speed of the traveling mechanism, repeating steps 3-7, and measuring the dredging effect of the dredging head under different power parameter conditions; Step 9, replace the dredging head with different diameters and different pitches, repeat steps 3-8, and measure the dredging effect of the dredging head under different structural parameters and operating parameters.

2. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: The underwater video recording equipment is installed in the test water tank, and the process of the dredging test is recorded by the underwater video recording equipment during the dredging test.

3. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: In step 2, the mud outlet of the dredging head is connected to the water inlet of the mud suction pump through a steel wire hose; the water outlet of the mud suction pump is connected to one end of the electromagnetic flowmeter through a fixed iron pipe; the other end of the electromagnetic flowmeter is connected to the mud storage tank through a fixed iron pipe.

4. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: The laying thickness of the sludge in the test water tank in step 4 is 10 cm.

5. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: The bottom of the dredging head is 1 cm away from the top of the graded gravel.

6. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: The expression for the relationship between the pipeline flow rate, the dredge suction pump flow rate, the rotation speed of the dredging head and the travel speed of the travel mechanism is as follows: Q1=f(q1、n1、v1) In the formula, Q1 represents the pipeline flow collected by the electromagnetic flowmeter, q1 represents the preset dredge suction pump flow, n1 represents the preset rotation speed of the dredging head, and v1 represents the preset travel speed of the travel mechanism.

7. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: During the dredging test, the gear at the bottom of the first motor cooperates with the rack formed on the side of the guide rail to drive the travel mechanism to move along the direction of the guide rail; the transmission wheel of the second motor is connected to the first transmission rod, driving the first transmission rod and the first synchronous pulley on the first transmission rod to rotate, and the second synchronous pulley is driven to rotate through the first synchronous belt, thereby driving the rotating shafts on both sides of the dredging head to rotate, driving the dredging head to rotate, and using the dredging head to cut the silt in the test water tank, so that the cut silt is mixed with clean water to form a mud-water mixture with strong fluidity, and the mud-water mixture formed in the dredging head is pumped out by a mud suction pump and stored in a mud storage box.

8. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: The running speed of the traveling mechanism is adjustable within a range of 0 to 2 m / min.

9. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: Adjusting the flow rate of the sludge suction pump in step 8 includes: adjusting the flow rate of the sludge suction pump by a frequency converter equipped with the sludge suction pump.

10. The test method for simulating dredging of a gravel bed surface according to claim 1, characterized in that: The material of the side of the test water tank is glass, and the material of the bottom is stainless steel.

Images