Underwater gravel bed desilting test system and test method

Abstract

The invention relates to the technical field of underwater base bed construction, and in particular to an underwater gravel base bed dredging test system and test method. By simulating the underwater silting condition of a gravel base bed in a construction area, a mud thickness parameter and a dredging device operation parameter are used as variables, and by detecting the flow change of a dredging pump, the remaining thickness of a mud layer after dredging, and the sand content of sucked-out water, an optimal combination of the dredging device operation parameters is determined, so as to provide a reference for finally dredging in the construction area, eliminate the need for equipment debugging at a construction site, avoid damage to the gravel base bed, and improve construction efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of underwater base bed construction, and in particular to an underwater gravel base bed dredging test system and test method. Background Art

[0002] After the gravel base bed leveling construction of the immersed tube tunnel is completed, silt will often be deposited on the base bed before the immersed tube is installed. In order to eliminate its adverse effects and ensure the quality of the immersed tube installation, the silt on the gravel base bed needs to be removed.

[0003] Chinese patent CN2020111259392 discloses a gravel dredging test method, which uses a traditional hydraulic dredging device to conduct scouring experiments on a gravel layer without a silt layer and a gravel layer with a silt layer to determine the appropriate flow value, pressure value, height of the water gun head from the gravel surface, and scouring time at the water gun head during the dredging process. The data determined by the experiment is used to perform actual dredging operations, which can effectively clean the silt on the gravel and protect the gravel layer from being damaged by water with excessive flow and pressure.

[0004] For the new mechanical and hydraulic dual-action dredging device, the dredging of the base bed is achieved by cutting the sludge and mixing the sludge with water to form a mud-water mixture with strong fluidity, and at the same time transporting the mud-water mixture to the mud outlet corresponding to the docking section for discharge. For example, Chinese patent CN212427289U discloses a mechanical and hydraulic dual-action precision scraping and dredging head and dredging device, which uses the cutting action of the inner blades to cut the sludge, but because the inner blades are arranged at intervals, the cutting surface is easily uneven during the rotation cutting process.

[0005] When using the above-mentioned mechanical and hydraulic dual-action dredging device for dredging operations, the dredging device must first be debugged in a complex manner to ensure its normal operation and achieve the preset dredging effect. The on-site debugging process is time-consuming and labor-intensive, and also increases the uncontrollable factors of construction. During the debugging process, the gravel of the base bed leveling may shift under mechanical or hydraulic disturbance, which may easily cause the flatness of the base bed surface to deteriorate, causing adverse effects on the subsequent immersed tube installation; in severe cases, the gravel ridge of the immersed tube tunnel may be damaged, and the gravel ridge needs to be repaired, which increases the difficulty and cost of construction and leads to low construction efficiency. Summary of the invention

[0006] In view of the deficiencies in the above-mentioned prior art, the present invention provides an underwater gravel base bed dredging test system and test method. Before construction, the dredging device conducts a dredging test on the gravel base bed in a simulated construction area to obtain relevant operating parameters and provide a reference for the final dredging construction.

[0007] The present invention provides an underwater gravel bed dredging test system, comprising:

[0008] A water pool, wherein an isolation box is arranged in the middle of the water pool, one side of the isolation box is a test area, in which a test gravel bed and a silt layer simulating a gravel bed in a construction area are arranged, and the other side is an observation area, and the test area is connected to the observation area;

[0009] A walking assembly is arranged above the test area, comprising two tracks parallel to the length direction of the test gravel bed, and a walking trolley capable of moving along the tracks, wherein a rotating power mechanism is arranged on the walking trolley;

[0010] A lifting mechanism is arranged on the walking trolley, a dredging device is arranged below the lifting mechanism, and the lifting mechanism is used to adjust the distance between the bottom of the dredging device and the mud surface;

[0011] The detection system includes an electromagnetic flowmeter arranged on the dredging device for measuring the change of the flow rate of muddy water discharged therefrom, and an underwater camera arranged underwater for underwater observation of gravel and silt at various positions of the test area;

[0012] The rotation speed of the dredging device is adjusted by the rotating power mechanism, the different distances from the bottom of the dredging device to the mud surface are adjusted by the lifting mechanism, the translation speed of the dredging device is adjusted by the walking trolley, the different thicknesses of the sludge layer, and the flow rate of the mud and water mixture discharged by the dredging device are used as variables to detect and record the flow rate changes of the discharged mud and water mixture, the remaining thickness of the mud layer after dredging, and the sand content of the sucked out mud and water mixture.

[0013] In some embodiments of the present application, the dredging device comprises:

[0014] The dredging head comprises a shell and a spiral conveying mechanism arranged inside the shell, a mud suction port is provided at the bottom end of the shell, a mud discharge port is provided at the top of the shell, the spiral conveying mechanism is connected to a rotary power mechanism, the rotary power mechanism drives the spiral conveying mechanism to rotate, the spiral conveying mechanism cuts the mud and mixes the mud with water to form a mud-water mixture with strong fluidity, and the mud-water mixture is transported from the mud suction port to the mud discharge port;

[0015] A mud suction pump is arranged above the housing and connected to the mud outlet to suck the mud-water mixture out of the mud outlet;

[0016] A scraper is arranged on the outer side of the shell, and the scraper is an arc-shaped plate arranged coaxially with the shell. The length of the scraper is the same as the length of the shell, and the bottom edge of the scraper is a linear structure parallel to the axis of the shell. The bottom of the scraper is inserted into the sludge, and the dredging head moves to drive the scraper to scrape the sludge to form a flat scraping surface;

[0017] The scraper is connected to an adjusting device, which can be extended and retracted along its axial direction. One end of the adjusting device is fixed to the outer casing of the mud suction pump, and the other end is fixed to the scraper. The adjusting device is extended and retracted to drive the scraper to rotate and adjust the relative height between the bottom edge of the scraper and the mud surface.

[0018] In some embodiments of the present application, the dredging device also includes a high-pressure water flushing device, which includes a high-pressure water flushing pump, a water flushing pipe arranged on the dredging head, and high-pressure nozzles evenly arranged on the water flushing pipe. The high-pressure water flushing device sprays a certain range in front of the dredging head to break up or flush away large mud blocks in front of the running direction.

[0019] In some embodiments of the present application, the length of the isolation box is smaller than the length of the water pool, one end of the isolation box is connected to an inner wall of the water pool, and the other end forms a connecting channel with the water pool, and the connecting channel connects the test area and the observation area.

[0020] The observation area is provided with a retention box, and the mud outlet of the dredge pump is connected to a mud discharge pipe. The mud and water mixture passes through the dredging head, the dredge pump and the mud discharge pipe in sequence and is discharged onto the retention box for retaining the mud and water mixture discharged by the dredge pump. The filtered fine sand can be directly observed.

[0021] The present invention also provides a dredging test method for a dredging device. Based on the above-mentioned dredging test system, the underwater silting condition of the gravel bed in the simulated construction area is tested, and the mud thickness parameter and the dredging device operation parameter are used as variables. The flow change of the dredging pump in the dredging device, the remaining thickness of the mud layer after dredging, and the sand content of the mud-water mixture sucked out are detected by the detection system to obtain an optimized combination of the dredging device operation parameters. The test method specifically includes the following steps:

[0022] Construct the test area and install the dredging equipment:

[0023] An isolation box is placed in the middle of the pool to construct a test area and an observation area, tracks are installed on the ground on one side of the test area and above the isolation box on the other side, a traveling trolley is installed on the two tracks, and then a lifting mechanism is installed on the traveling trolley, and a dredging head, a dredging pump and a high-pressure flushing device of a dredging device are installed at the lower end of the lifting mechanism, so that the dredging head, the dredging pump and the high-pressure flushing device move synchronously with the traveling trolley;

[0024] Laying the test gravel base bed:

[0025] A gravel layer is laid in the test area, and mud and sand are laid on the gravel layer to form a silt layer. Then water is added to the test area to the designed water level to simulate the underwater siltation condition of the gravel base bed in the construction area.

[0026] Conducting dredging test:

[0027] Under different silt thicknesses, multiple dredging tests were carried out by adjusting the mud entry depth, translation speed, rotation speed, and mud suction pump flow of the dredging head. The flow changes of the dredging pump, the actual remaining thickness of the mud layer after dredging, and the sand content of the sucked water were detected and recorded to obtain the optimal combination of the operating parameters of the dredging device for subsequent dredging construction.

[0028] The test method of the dredging device of the present technical solution tests the dredging process of the dredging device in a test area to obtain an optimized combination of operating parameters of the dredging device, thereby providing a reference basis for dredging of the gravel base bed. There is no need to debug the equipment at the construction site, thus avoiding damage to the gravel base bed and improving construction efficiency.

[0029] In some embodiments of the present application, during the laying of the test bed, after the gravel layer is laid and leveled, mud and sand are laid, the thickness of the mud and sand is H, and the remaining thickness of the mud layer after dredging is preset to be H. 剩余 ;

[0030] During the dredging test, the distance between the bottom edge of the scraper of the dredging head and the surface of the gravel layer is H 剩余 .

[0031] In some embodiments of the present application, when conducting the dredging test, the high-pressure nozzle in the high-pressure water flushing device is also turned off to compare the dredging effect of the dredging device with and without the high-pressure nozzle.

[0032] In some embodiments of the present application, the remaining thickness of the mud layer can be measured manually, specifically: each certain distance is used as a measurement section, multiple measuring points are arranged in each measurement section, the thickness of the mud layer is measured with a ruler, the data is recorded, and the average remaining thickness of the mud layer in each section is analyzed;

[0033] The flow change of the dredge suction pump is measured using an electromagnetic flowmeter.

[0034] In some embodiments of the present application, when adding water to the gravel base bed, water is added from one side of the observation area, and the water enters the test area through the connecting channel along the outer wall of the isolation box until the water pool is gradually filled, thereby avoiding disturbance of the sand and gravel during the water adding process.

[0035] In some embodiments of the present application, during the test, the dredge suction pump is first turned on, and then the dredge cleaning head is started. When mud is discharged from the dredge suction pump outlet, the walking trolley is started. After the test is completed, each device is turned off in the reverse order.

[0036] After one set of tests is completed, the silt in the gravel is cleaned and prepared for the next set of tests.

[0037] Based on the above technical solution, the test method of the dredging device of the present invention tests the dredging process of the dredging device in the test area, obtains the optimal combination of the operating parameters of the dredging device, provides a reference basis for the dredging work of the gravel bed, does not need to debug the equipment at the construction site, avoids the damage to the gravel bed, and improves the construction efficiency;

[0038] During the dredging test, the operation procedures of the dredging process were sorted out to reduce operational errors in subsequent actual construction;

[0039] It can verify the effectiveness of the dredging head structure in the dredging device and the effectiveness of the high-pressure nozzle structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 A front view of a test system according to an embodiment of the present invention;

[0042] Figure 2 A top view of a test system according to an embodiment of the present invention;

[0043] Figure 3 This is a schematic structural diagram of a gravel bed according to an embodiment of the present invention;

[0044] Figure 4 A flow chart of a dredging test according to an embodiment of the present invention;

[0045] Figure 5 It is a structural schematic diagram of a dredging head according to an embodiment of the present invention;

[0046] Figure 6 A schematic structural diagram of a dredging head from another perspective of an embodiment of the present invention;

[0047] Figure 7 A schematic structural diagram of a spiral transport mechanism according to an embodiment of the present invention;

[0048] Figure 8 Schematic diagram of the cutting surface after silting using a scraper in an embodiment of the present invention;

[0049] in,

[0050] 10. Water pool; 11. Test area; 111. Test gravel bed; 112. Silt layer; 12. Observation area; 121. Retention box; 13. Connecting channel; 20. Isolation box; 30. Travel assembly; 31. Track; 32. Travel trolley; 40. Dredging device; 41. Dredging head; 411. Shell; 4111. Mud suction port; 4112. Mud discharge port; 412. Screw conveying mechanism; 4121. Conveying auger; 4122. Scraping blades; 413. Scraper; 414. Adjustment device; 42. Mud suction pump; 43. Lifting mechanism. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0053] The terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, a feature defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features.

[0054] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] The dredging test method of this embodiment simulates the underwater silting condition of the gravel base bed in the construction area, and takes the mud thickness parameter and the dredging device operation parameter as variables, and determines the optimal combination of the dredging device operation parameters by detecting the flow change of the dredging pump, the remaining thickness of the mud layer after dredging, and the sand content of the sucked water, so as to provide a reference for the final dredging in the construction area; the test method of this embodiment is carried out through a test system, such as Figure 1-Figure 2 As shown,

[0056] The test system includes:

[0057] The water pool 10, in this embodiment, is a fire emergency water pool, an isolation box 20 is arranged in the middle of the water pool 10, one side of the isolation box 20 is the test area 11, a test gravel base bed 111 simulating the gravel base bed of the construction area is arranged in the test area 11, and the other side is the observation area 12, the length of the isolation box 20 is less than the length of the water pool 10, one short side of the isolation box 20 is connected to an inner wall of the water pool 10, and the other short side opposite to the water pool 10 forms a connecting channel 13, and the connecting channel 13 connects the test area 11 and the observation area 12; in this embodiment, at the front end of the test area 11, the test area 11 and the observation area 12 are interconnected, when water is added to the test gravel base bed 111, water is added from one side of the observation area, water is added from the isolation box 20 located on the side of the observation area 12, and water passes through the isolation box 20 through the connecting channel 13 into the test area 11 until the water pool is gradually filled, so as to avoid disturbance of sand and gravel during the water adding process;

[0058] The walking assembly 30 is arranged above the test area 11, and includes two tracks 31 and a walking trolley 32 that can move along the tracks 31, wherein one track 31 is arranged at the edge of the pool, and the other track 31 is arranged on the top of the isolation box 20, and the walking trolley 32 moves in the length direction of the test area;

[0059] The dredging device 40 includes a dredging head 41, a dredging pump 42, and a high-pressure water flushing device;

[0060] The dredging head 41 is the main structure of the dredging device and is a key component for achieving accurate dredging of the stone ridge surface. Figure 5-Figure 6As shown, the dredging head 41 includes a shell 411 and a spiral conveying mechanism 412 arranged inside the shell 411, a mud suction port 4111 is opened at the bottom end of the shell 411, and a mud discharge port 4112 is opened on the top of the shell 411; the spiral conveying mechanism 412 includes a conveying auger 4121 and a scraping blade 4122, the conveying auger is composed of a left-section left-handed auger spiral blade and a right-section right-handed auger spiral blade, and the left-handed auger spiral blade and the right-handed auger spiral blade are coaxially connected; the scraping blade 4122 adopts an involute form, a hole is opened at the middle docking section of the scraping blade 4122, and the outer edge is set as a cutting portion. The spiral transport mechanism 412 is connected to the rotary power mechanism (not shown in the figure). In this embodiment, the diameter of the conveying auger is 400 mm, the pitch is 350 mm, and the number of spirals on one side is 4. The rotary power mechanism drives the spiral transport mechanism 412 to rotate, and the spiral blades cut the silt and mix the silt with water to form a mud-water mixture with strong fluidity. The mud-water mixture is transported from the mud suction port 4111 to the mud discharge port 4112.

[0061] A scraper 413 is arranged on the outside of the shell 411. The scraper 413 is an arc-shaped plate coaxially arranged with the shell 411. The length of the scraper 413 is the same as the length of the shell 411. The bottom edges on both sides of the scraper 413 are linear structures parallel to the axis of the shell 411. The bottom of the scraper is inserted into the silt, and the movement of the dredging head drives the scraper 413 to scrape the silt to form a flat scraping surface; the upper part of the scraper 413 is opened, leaving installation space for the dredge pump, so that the dredge pump can be fixed on the mud outlet.

[0062] The scraper 413 is connected to an adjusting device 414, which can be extended and retracted along its axial direction. In this embodiment, the adjusting device is a vertically installed telescopic cylinder, one end of which is fixed to the outer casing of the dredge pump, and the other end is fixed to the outer surface of the middle part of the scraper 413. When the telescopic cylinder is extended, the scraper 413 rotates clockwise, and the right bottom edge drops deep into the mud. In this embodiment, according to the direction of operation of the dredging device, the telescopic cylinder can be extended and retracted to adjust the different bottom edges of the scraper to penetrate into the mud, and the relative height between the bottom edge and the mud surface can be adjusted, that is, the depth of entry into the mud can be adjusted.

[0063] Working principle: The size of the mud suction port is adjusted by rotating the scraper 413, and the spiral conveying mechanism of the dredging head rotates forward under the action of the driving device. The scraping blade 4122 uses the scraping action of its blade to cut the sludge while mixing the sludge with water to form a mud-water mixture with strong fluidity. At the same time, the scraping blade 4122 rotates to generate a water flow force that drives the mud-water mixture to move toward the central axis of the spiral conveying structure. The left and right spiral blades rotate forward to transport the mud-water mixture to the middle docking section, and then transport the mud-water mixture to the mud outlet corresponding to the docking section for discharge, thereby achieving dredging.

[0064] The dredge suction pump 42 is arranged above the housing 411, and the dredge suction pump 42 has a sludge inlet connected to the sludge outlet of the dredging head, and the sludge-water mixture at the sludge outlet of the dredge cleaning head is sucked out and discharged on the retention box 121. The retention box 121 is a box structure with an upper opening, and its bottom plate is a filter screen, which retains the silt concentrated in the sludge-water mixture in the retention box, and the water flows into the pool through the filter screen; the dredge suction pump of this embodiment adopts a submersible slurry pump, model 100ZJQ120-35-22, flow rate 120m³ / h, power 22kW, head 35m;

[0065] The high-pressure water flushing device sprays a certain range in front of the dredging head to break up or flush away large mud blocks in front of the running direction; the high-pressure water flushing device of this embodiment adopts a pipeline dredging machine, model HY-D110A, with an ultimate pressure of 18MPa and a maximum flow rate of 40L / min. The water outlet is sent through a hose to multiple nozzles installed on the hard pipe in front of the dredging head to achieve a certain range of spraying.

[0066] Rotating power mechanism and lifting mechanism, the rotating power mechanism drives the dredging head to rotate, and is used to control the speed n of the dredging head; the rotating power mechanism of this embodiment is composed of a motor and a reducer, and transmits power to the outer end of the dredging head through a chain drive, driving the conveying auger of the dredging head to rotate. The maximum speed is 37r / min, and variable frequency speed regulation is possible;

[0067] The lifting mechanism controls the lifting and lowering of the dredging head, and is used to control the distance between the bottom of the dredging head and the mud surface. The adjustment accuracy reaches the centimeter level and the adjustment range is 1m. During the test, two electric hoists are used to realize the lifting and lowering functions; the rotating power mechanism and the lifting mechanism are both arranged on the walking trolley; the walking trolley integrates the lifting, rotating power, flushing pump and its own walking power of the dredging pump and the control of related actions together, and realizes walking by using two tracks 31. The effective stroke is 10m, the maximum walking speed is 10m / min, and the speed can be adjusted by variable frequency.

[0068] The detection system includes an electromagnetic flowmeter for measuring the flow change of the dredge pump and an underwater camera for underwater observation of the test area. The underwater camera of this embodiment is fixed on a long pole to observe various positions at any time.

[0069] The method for testing the dredging device using the above test system specifically comprises the following steps:

[0070] Construct the test area and install the dredging equipment:

[0071] This embodiment uses a fire emergency water pool, and an isolation box 20 is placed in the water pool 10. The water pool on one side of the isolation box 20 is the test area 11, and the other side is the observation area 12. After the test area 11 is constructed, tracks are installed on both sides of the test area 11, one side is located on the top of the isolation box 20, and the other side is located on one side edge of the water pool. A walking trolley 32 is set between the two tracks, and a dredging head, a dredging pump and a high-pressure fine water flushing device are installed on the walking trolley 32. The dredging head, the dredging pump and the high-pressure fine water flushing device move synchronously with the walking trolley;

[0072] Laying the test gravel base bed:

[0073] A gravel layer is laid in the test area. In this embodiment, Figure 3 As shown, two stone ridges are laid at the bottom of the test area, consisting of 10mm diameter gravel. The minimum diameter of the gravel in the actual construction site area is used here, which is more easily disturbed or sucked away, and can more effectively test the capacity of the equipment. The thickness of the test gravel base bed is 10cm; the gravel is loaded into the test trough and leveled manually. The middle ridge is determined by a V-shaped groove, and the ridges on both sides are manually sloped. After the gravel layer is laid, the characteristic positions are marked with paint to facilitate the inspection of the base bed disturbance after the test; after the gravel layer is laid, the elevation H of the gravel layer surface is measured with a ruler, and then different thicknesses of mud and sand are laid;

[0074] Fine sand and soil are fully mixed according to the set ratio, and laid on the stone ridge in different sections and thicknesses, and then water is injected. Water is added from the isolation box 20 on the side of the observation area 12. The water passes through the isolation box 20 and enters the test area 11 through the connecting channel 13. The water is slowly injected to the required water level. In this embodiment, the water is injected to 2.2m to simulate the underwater siltation condition of the gravel base bed in the construction area to avoid disturbing the sand and gravel. There are special personnel to watch and collect videos to ensure that the water does not overflow;

[0075] Determine the experimental variables and conduct the experiment:

[0076] The thickness h of the silt layer and the translation speed of the silt removal head in the silt removal device are respectively V s , the rotation speed n of the dredging head, and the flow rate Q of the dredging pump are used as variables, and multiple dredging tests are carried out to detect and record the flow rate change of the dredging pump, the remaining thickness of the mud layer after dredging, and the sand content of the sucked water, so as to obtain the optimal combination of the operating parameters of the dredging device and use it for subsequent dredging construction;

[0077] In this embodiment, the thickness h of the silt layer is 10 cm and 20 cm;

[0078] Translation speed of dredging head V sThe values ​​are 2.0m / min, 4.0m / min, 5.0m / min, 8.0m / min;

[0079] In this embodiment, according to the maximum mud layer thickness of 20cm at the construction site, the width of the gravel ridge is 1.2m, the width of the ridge ditch between the gravel ridges is 0.6m, there are 58 ridges in total, and the length is 47m. Considering that the actual extraction is a mixture of silt and water, the specific gravity of the mixture is between pure silt and water, combined with the dredging head, it can simultaneously process two ridges and one ditch, that is, the processing width of the dredging head is 3m. Considering the processing time, the dredging pump in this embodiment adopts a submersible slurry pump, model 100ZJQ120-35-22, flow rate 120m³ / h, power 22kW, and head 35m. The change of the flow rate Q of the dredging pump is measured and displayed using an electromagnetic flowmeter, and the frequency of the dredging pump during the test is adjusted according to the data displayed by the electromagnetic flowmeter.

[0080] When determining the test variables, the rotation speed n of the dredging head controlled by the rotating power mechanism is used as a parameter for the operation of the dredging device to obtain the flow change of the dredging pump, the remaining thickness of the mud layer after dredging, and the sand content of the sucked water at different rotation speeds n; in this embodiment, the rotation speed n of the dredging head is 10r / min, 20r / min, 30r / min, and 37r / min;

[0081] During the test, the mud entry depth of the dredging head is to adjust the bottom of the scraper to different distances below the mud surface. In this embodiment, the bottom of the scraper of the dredging head is adjusted to 4 cm and 16 cm below the mud surface to test the maximum dredging performance of the dredging head. After laying and leveling the gravel layer, sludge is laid. In this embodiment, the thickness H of the sludge is 10 cm and 20 cm respectively; the preset remaining thickness of the mud layer after dredging is H 剩余 ;

[0082] During the dredging test, the distance between the bottom edge of the scraper of the dredging head and the surface of the gravel layer is H. 剩余 .

[0083] After dredging, the remaining thickness of the mud layer can be measured manually, specifically: every 1.5m interval is used as a measurement section, 3 measuring points are arranged in each measurement section, and the thickness of the mud layer is measured using a steel ruler, the data is recorded, and the average remaining thickness of the mud layer in each section is analyzed. In the dredging test of this embodiment, the original mud layer thickness H is 10cm, the preset mud layer remaining thickness H is 10cm, and the remaining thickness H is 10cm. 泥If the height of the bottom edge of the scraper of the dredging head from the surface of the gravel layer is 6 cm, then the height of the bottom edge of the scraper of the dredging head from the surface of the gravel layer is 6 cm; after the silt is laid, a long rod with a height of 6 cm is inserted into the silt. When the bottom of the long rod touches the surface of the gravel layer, the insertion stops, and then the dredging head descends. When the bottom of the scraper of the dredging head touches the top of the long rod, the dredging head stops descending and the dredging operation begins; a total of 6 dredging processes are carried out; the actual remaining thickness of the mud layer is measured 48 hours after the dredging pump has pumped water, and the result is:

[0084]

[0085] The average remaining thickness of the mud layer is 4.67cm, and the average thickness of the mud scraped off by the dredging head is 5.33cm.

[0086] In another set of experiments, the original mud layer thickness H is 20 cm and the preset mud layer remaining thickness H is 泥 If the height of the bottom edge of the scraper of the dredging head from the surface of the gravel layer is 4 cm, then the height of the bottom edge of the scraper of the dredging head from the surface of the gravel layer is 4 cm; after the silt is laid, a long rod with a height of 4 cm is inserted into the silt. When the bottom of the long rod touches the surface of the gravel layer, the insertion stops, and then the dredging head descends. When the bottom of the scraper of the dredging head touches the top of the long rod, the dredging head stops descending and the dredging operation begins; a total of 4 dredging processes are carried out; the actual remaining thickness of the mud layer is measured 48 hours after the dredging pump has pumped water, and the result is:

[0087]

[0088] The average remaining thickness of the mud layer is 4.5 cm, and the average thickness of the mud scraped off by the dredging head is 15.5 cm.

[0089] Therefore, the setting of the scraper can make the dredging head meet the requirements of the preset dredging depth, such as Figure 8 As shown, the box in the figure shows the cutting surface of the dredging head of this embodiment after dredging, and its surface is flat and smooth.

[0090] Under the same silt thickness and the same depth of silt entry, the different translation speeds of the dredging head V s , and the desilting effect was compared at different speeds n. The results showed that at the same speed, the translation speed of the desilting head V s The smaller the size, the better the dredging effect, so the translation speed V s Select 2.0m / min; the dredging head moves at the same translation speed V s 1. Under the same mud penetration depth, the greater the rotation speed n, the better the silt removal effect;

[0091] This experiment also compared the dredging effects of the dredging head at different rotation speeds n at different mud entry depths, and found that the mud entry depth is proportional to the rotation speed n of the dredging head. The deeper the mud entry depth, the greater the rotation speed n and the better the dredging effect.

[0092] The test also verified the role of the high-pressure nozzle: the high-pressure nozzle in the high-pressure flushing device was closed and opened respectively, and the dredging effect of the dredging device was compared with and without the high-pressure nozzle. The results showed that when there was a high-pressure nozzle, large mud blocks were broken up and the dredging effect was better.

[0093] During the test, start the dredge pump first, then start the dredge head. When mud is discharged from the dredge pump outlet, start the traveling trolley. After the test, shut down each device in the reverse order.

[0094] After one set of tests is completed, the silt in the gravel is cleaned and prepared for the next set of tests.

[0095] Through the above dredging test, it can be obtained that in this embodiment, the translation speed of the dredging device is V s The speed of the dredging head is 2.0 m / min. The depth of entry into the mud is proportional to the speed n of the dredging head. The greater the depth of entry into the mud, the greater the speed required for the dredging head.

[0096] The test method of the dredging device of the present invention tests the dredging process of the dredging device in a test area to obtain an optimized combination of operating parameters of the dredging device, which provides a reference basis for the dredging work of the gravel bed, does not require equipment debugging at the construction site, avoids damage to the gravel bed, and improves the construction efficiency.

[0097] During the dredging test, the operation procedures of the dredging process were sorted out to reduce operational errors in subsequent actual construction;

[0098] It can verify the effectiveness of the dredging head structure in the dredging device and the effectiveness of the high-pressure nozzle structure.

[0099] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0100] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, a person skilled in the art should understand that the specific implementation mode of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. An underwater gravel bed dredging test system, characterized in that: include: A water pool, wherein an isolation box is arranged in the middle of the water pool, one side of the isolation box is a test area, in which a test gravel bed and a silt layer simulating a gravel bed in a construction area are arranged, and the other side is an observation area, and the test area is connected to the observation area; A walking assembly is arranged above the test area, comprising two tracks parallel to the length direction of the test gravel bed, and a walking trolley capable of moving along the tracks, wherein a rotating power mechanism is arranged on the walking trolley; A lifting mechanism is arranged on the traveling trolley, a dredging device is arranged below the lifting mechanism, and the lifting mechanism is used to adjust the distance between the bottom of the dredging device and the mud surface; The detection system includes an electromagnetic flowmeter arranged on the dredging device for measuring the flow change of the mud-water mixture sucked out by the dredging device, and an underwater camera arranged underwater for underwater observation of gravel and silt at various positions of the test area; The rotation speed of the dredging device is adjusted by the rotating power mechanism, the different distances from the bottom of the dredging device to the mud surface are adjusted by the lifting mechanism, the translation speed of the dredging device is adjusted by the walking trolley, the different thicknesses of the sludge layer, and the flow rate of the mud-water mixture discharged by the dredging device are used as variables to detect and record the flow change of the sucked-out mud-water mixture, the remaining thickness of the mud layer after dredging, and the sand content of the sucked-out mud-water mixture; The desilting device comprises: The dredging head comprises a semi-enclosed shell and a spiral conveying mechanism arranged inside the shell, a mud suction port is provided at the bottom end of the shell, a mud discharge port is provided at the upper middle part of the shell, the spiral conveying mechanism is connected to a rotary power mechanism, the rotary power mechanism drives the spiral conveying mechanism to rotate, the spiral conveying mechanism cuts the mud and mixes the mud with water to form a mud-water mixture with strong fluidity, and the mud-water mixture is transported from the mud suction port to the mud discharge port; A mud suction pump is arranged above the housing and connected to the mud outlet to suck the mud-water mixture out of the mud outlet; A scraper is arranged on the outer side of the shell, and the scraper is an arc-shaped plate arranged coaxially with the shell. The length of the scraper is the same as the length of the shell, and the bottom edge of the scraper is a linear structure parallel to the axis of the shell. The bottom of the scraper is inserted into the sludge, and the dredging head moves to drive the scraper to scrape the sludge to form a flat scraping surface; The scraper is connected to an adjusting device, which can be extended and retracted along its axial direction. One end of the adjusting device is fixed to the outer casing of the mud suction pump, and the other end is fixed to the scraper. The adjusting device is extended and retracted to drive the scraper to rotate and adjust the relative height between the bottom edge of the scraper and the mud surface.

2. According to the underwater gravel bed dredging test system of claim 1, the dredging device also includes a high-pressure water flushing device, which includes a high-pressure water flushing pump, a water flushing pipe arranged on the dredging head, and high-pressure nozzles evenly arranged on the water flushing pipe. The high-pressure water flushing device sprays a certain range in front of the dredging head to break up or flush away large mud blocks in front of the running direction.

3. The underwater gravel bed dredging test system according to claim 2, characterized in that: The length of the isolation box is shorter than the length of the pool, one end of the isolation box is connected to an inner wall of the pool, and the other end forms a communication channel with the pool, wherein the communication channel connects the test area and the observation area; The observation area is provided with a retention box, and the mud outlet of the dredge pump is connected to a mud discharge pipe. The mud and water mixture passes through the dredging head, the dredge pump and the mud discharge pipe in sequence and is discharged onto the retention box for retaining the mud and water mixture discharged by the dredge pump. The filtered fine sand can be directly observed.

4. A test method using the underwater gravel bed dredging test system according to any one of claims 1 to 3, characterized in that: The specific steps include: Construct the test area and install the dredging equipment: An isolation box is placed in the middle of the pool to construct a test area and an observation area, tracks are installed on the ground on one side of the test area and above the isolation box on the other side, a traveling trolley is installed on the two tracks, and then a lifting mechanism, a dredging head, a dredging pump and a high-pressure flushing device of a dredging device are installed on the traveling trolley, so that the dredging head, the dredging pump and the high-pressure flushing device move synchronously with the traveling trolley; Laying the test gravel base bed: A gravel layer is laid in the test area, and mud and sand are laid on the gravel layer to form a silt layer. Then water is added to the test area to the designed water level to simulate the underwater siltation condition of the gravel base bed in the construction area. Conducting dredging test: Under different silt thicknesses, multiple dredging tests were carried out by adjusting the mud entry depth, translation speed, rotation speed, and mud suction pump flow of the dredging head. The flow changes of the dredging pump, the actual remaining thickness of the mud layer after dredging, and the sand content of the sucked water were detected and recorded to obtain the optimal combination of the operating parameters of the dredging device for subsequent dredging construction.

5. The test method of the dredging device according to claim 4, characterized in that: During the laying of the test bed, after laying and leveling the gravel layer, silt is laid. The thickness of the silt is H. The remaining thickness of the silt layer after dredging is preset to be H. 剩余 ; During the dredging test, the distance between the bottom edge of the scraper of the dredging head and the surface of the gravel layer is H 剩余 .

6. The test method of the dredging device according to claim 4, characterized in that: When conducting the dredging test, the high-pressure nozzle in the high-pressure water flushing device is also turned off to compare the dredging effect of the dredging device with and without the high-pressure nozzle.

7. The test method of the dredging device according to claim 4, characterized in that: The remaining thickness of the mud layer is measured manually, specifically: each certain distance is taken as a measurement section, multiple measuring points are arranged in each measurement section, the thickness of the mud layer is measured with a ruler, the data is recorded, and the average remaining thickness of the mud layer in each section is analyzed; The flow change of the dredge suction pump is measured using an electromagnetic flowmeter.

8. The test method of the dredging device according to claim 4, characterized in that: When adding water to the gravel base bed, water is added from one side of the observation area, and the water enters the test area along the outer wall of the isolation box through the connecting channel until the water pool is gradually filled up, avoiding disturbance of the sand and gravel during the water adding process.

9. The test method of the dredging device according to claim 4, characterized in that: During the dredging test, the dredging pump is first turned on, and then the dredging head is started. When mud is discharged from the dredging pump outlet, the traveling trolley is started. After the test is completed, each device is closed in the reverse order. After one set of tests is completed, the silt in the gravel is cleaned and prepared for the next set of tests.

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