Propeller type flow generation test method in geotechnical centrifuge

Abstract

The invention discloses a geotechnical centrifuge internal propeller type flow generation test method, which comprises the following steps: preparing test slurry, pouring the test slurry into a model soil box, pressurizing and solidifying to form a soil sample, and burying soil pressure, pore pressure and displacement sensors in the soil sample; processing a structure model, and inserting the structure model into the soil sample; hoisting the manufactured model soil box into a preset position of a supergravity model box, and adding water into the supergravity model box; a flow generating water tank, an ultrasonic defoamer, a rectifying plate, a flow guide tank and a flow velocity meter are arranged on the supergravity model box and electrically connected with a control system and a sensor sampling system; the flow generating water tank is started, circulating water flow is formed through high-speed rotation of the flow generating propeller, the ultrasonic defoamer is started to eliminate bubbles in the water flow, the flow velocity of the water flow is adjusted according to parameter feedback measured by the flow velocity meter until stable water flow is formed, and scouring of the water flow to the soil sample and the structure model is observed through the observation window and the sensors.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering physical simulation, and in particular to a propeller-type flow generation test method in a geotechnical centrifuge. Background Art

[0002] In the construction of emerging sectors such as offshore wind power, deep-sea ranching, and deep-sea mining, the impact of ocean currents on engineering structures and foundations is a challenging engineering challenge that must be addressed. While ocean currents can damage structures by excessive stress, they can also weaken the foundation soil through erosion and erosion, altering stress distribution within the foundation and reducing its bearing capacity. This process involves complex interactions between ocean currents, structures, and foundations.

[0003] Currently, conventional wave flume tests are primarily used to study current-structure-foundation interactions. However, these tests have significant limitations in accurately simulating foundations and differ significantly from actual working conditions. Geotechnical centrifuge model tests, which can reproduce the initial stress transitions of a project, offer the highest similarity among all geotechnical simulations. However, studies of ocean scour in geotechnical centrifuges are rare.

[0004] Existing technologies often use water pumps to generate flow within geotechnical centrifuges. However, generating circulating water flow in a hypergravity field requires significant resistance, resulting in poor flow generation and extremely limited application scenarios. Therefore, it is urgent to develop a new propeller-type flow generation test device and test method for geotechnical centrifuges. Summary of the Invention

[0005] The purpose of this application is to provide a propeller-type flow generation test method in a geotechnical centrifuge to address the technical defects in the prior art.

[0006] The technical solutions adopted to achieve the purpose of this application are:

[0007] A propeller-type flow generation test method in a geotechnical centrifuge, wherein the propeller-type flow generation test device in the geotechnical centrifuge comprises a flow generation flume, a model soil box, a supergravity model box and a support;

[0008] The flow-generating water trough is fixedly mounted on the support, the supergravity model box is fixedly mounted on the support, and the flow-generating water trough is fixedly mounted around the supergravity model box; both ends of the flow-generating water trough are open and respectively connected to the two ends of the supergravity model box, one end of the flow-generating water trough is filled with water and the other end is sprayed with water to form a circulating water flow;

[0009] The flow-generating water trough is provided with a plurality of flow-generating propellers, which drive the water flow in the flow-generating water trough through high-speed rotation of the flow-generating propellers; the water outlet of the flow-generating water trough is connected to the supergravity model box through a rectifying and diffusing section; the rectifying and diffusing section is provided with an ultrasonic defoamer, which punctures bubbles in the water flow through ultrasonic vibrations;

[0010] The water inlet and water outlet of the flow flume are respectively provided with rectifying plates for rectifying the water flow entering and flowing out of the flow flume; the water outlet of the flow flume is provided with a guide groove for guiding the water flow; a flow meter is fixedly installed on the hypergravity model box for real-time monitoring of the water flow velocity and feedback adjustment of the water flow velocity;

[0011] The model soil box is placed inside the supergravity model box and in front of the diversion trough outlet, so that the model soil box can withstand the scouring of the stable water flow flowing out of the diversion trough outlet;

[0012] The test method comprises the following steps:

[0013] Step 1: Dry the test soil material, sieve it, remove impurities, add water and stir it into a test mud with a water content of about 2 times the liquid limit;

[0014] Step 2: Pour the test slurry obtained in step 1 into the model soil box and pressurize it to form a soil sample of a certain density to ensure that the soil sample is fully saturated. Then, earth pressure, pore pressure, and displacement sensors are buried at a certain depth inside the soil sample.

[0015] Step 3: Process the structural model and insert the structural model into the soil sample at a set depth to complete the production of the model soil box;

[0016] Step 4, hoisting the model soil box made in step 3 into a pre-set position of the hypergravity model box, and then adding water to the hypergravity model box to a certain height;

[0017] Step 5: Arrange the flow flume, ultrasonic defoamer, rectifier, guide trough and flow meter on the hypergravity model box and electrically connect them to the control system and sensor sampling system;

[0018] Step 6: Start the flow flume, and form a circulating water flow through the high-speed rotation of the flow-generating propeller in the flow flume. At the same time, turn on the ultrasonic defoamer to eliminate bubbles in the water flow, and adjust the water flow rate according to the feedback of the measurement parameters of the flow meter until a stable water flow is formed. Through the observation window and various sensors, observe the scouring of the water flow on the soil sample and the structural model, simulating the interaction between the ocean current, structure and foundation in the marine environment.

[0019] In the above technical solution, the flow flume is fixedly mounted on the support via a support frame, and the flow flume is fixedly mounted on the supergravity model box via bolts;

[0020] The flow-making water trough includes a first corner section, a power section and a second corner section. A water inlet is provided at one end of the first corner section, and the water inlet is connected to one end of the supergravity model box for water intake; the other end of the first corner section is connected to one end of the power section, and a plurality of flow-making propellers are arranged at equal intervals in the power section; the other end of the power section is connected to one end of the second corner section, and a water outlet is provided at the other end of the second corner section, and the water outlet is connected to the other end of the supergravity model box through a rectifying and diffusing section.

[0021] In the above technical solution, the power section is linear; the first corner section and the second corner section are both arc-shaped; and the rectifying and diffusing section is bell-mouth-shaped.

[0022] In the above technical solution, the ultrasonic defoamer is fixed on the rectifying and diffusing section of the flow-making flume through a base.

[0023] In the above technical solution, each flow-making propeller is an axial pump-jet propeller;

[0024] Each flow-making propeller includes blades and a motor, and the motor drives the blades to rotate at high speed to generate high-speed water flow.

[0025] In the above technical solution, the flow meter is fixedly mounted on the hypergravity model box via a connector, and the flow meter is a propeller-type flow meter.

[0026] In the above technical solution, the model soil box includes a soil box, a soil sample and a structural model. The soil sample is arranged inside the soil box. Strain gauges are pasted on the surface of the structural model to measure the internal force of the structural model. The structural model with strain gauges is arranged inside the soil sample.

[0027] In the above technical solution, the hypergravity model box includes multiple aluminum alloy wall panels, which form a rectangular box. One of the aluminum alloy wall panels is provided with an observation window, and organic glass is installed on the observation window for observing the scouring of the model soil box by the water flow in the hypergravity model box.

[0028] In the above technical solution, the ultrasonic defoamer includes an ultrasonic generator, a power amplifier and an ultrasonic sensor. The ultrasonic defoamer generates a high-frequency signal through the ultrasonic generator, amplifies it through the power amplifier, and then transmits the amplified high-frequency signal to the high-speed water flow in the rectification and diffusion section through the ultrasonic sensor, causing the bubbles in the water flow to resonate and burst, thereby eliminating the bubbles in the water flow.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. The propeller-type flow-making test device in the geotechnical centrifuge of the present invention adopts a shaftless pump-jet propeller to make flow. The flow-making water tank is placed horizontally, with high flow-making efficiency, low noise, few bubbles, and the ability to maintain high-speed circulating water flow for a long time.

[0031] 2. The propeller-type flow-generating test device in the geotechnical centrifuge of the present invention adopts an ultrasonic defoamer, which can further reduce the bubbles generated in the water flow, reduce the impact of bubble breakage on the model soil box, and improve the accuracy of water flow scouring simulation.

[0032] 3. The propeller-type flow-making test device in the geotechnical centrifuge of the present invention uses a diversion trough to divert water flow over a long distance, which can overcome the influence of the Coriolis force under the hypergravity field and easily form laminar flow conditions.

[0033] 4. The propeller-type flow-generating test device in the geotechnical centrifuge of the present invention can highly restore the water flow-structure-foundation interaction process in the marine environment. It is easy to operate, highly automated, and has a stable structure, providing a stable and reliable advanced research platform for the study of marine engineering related issues.

[0034] 5. The propeller-type flow-making test device in the geotechnical centrifuge of the present invention utilizes organic glass to monitor the water flow velocity in real time and perform feedback adjustment, thereby improving the accuracy of flow velocity control. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0036] Figure 1 This is a structural schematic diagram of the propeller-type flow-generating test device in a geotechnical centrifuge according to the present invention.

[0037] Figure 2 This is a schematic structural diagram of the flow-generating flume described in the present invention.

[0038] Figure 3 This is a schematic diagram of the structure of the shaftless pump-jet propeller described in the present invention.

[0039] Figure 4 This is a schematic structural diagram of the ultrasonic defoamer described in the present invention.

[0040] Figure 5 This is a schematic diagram of the model soil box structure of the present invention.

[0041] Figure 6 This is a structural schematic diagram of the hypergravity model box described in the present invention.

[0042] In the figure: 1-flow flume; 101-water inlet; 102-first corner section; 103-power section; 104-second corner section, 105-rectifier diffusion section; 106-water nozzle; 2-flow propeller; 201-blade; 202-motor; 3-ultrasonic defoamer; 301-ultrasonic generator; 302-power amplifier; 303-ultrasonic sensor; 304-base; 4-rectifier plate; 5-guide trough; 6-flow meter; 601-connector; 7-model soil box; 701-aluminum alloy soil box; 702-soil sample; 703-structural model; 8-hypergravity model box; 801-aluminum alloy wall panel; 802-observation window; 803-plexiglass, 9-support, 10-support frame. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention are further described below with reference to specific embodiments.

[0044] A propeller-type flow test device in a geotechnical centrifuge, see Figure 1 , including a flow flume 1, a model soil box 7, a supergravity model box 8 and a support 9, wherein:

[0045] See also Figure 2 The flow trough 1 is fixedly mounted on the support 9 via a support frame 10. The supergravity model box 8 is fixedly mounted on the support 9 via bolts. The flow trough 1 is fixedly mounted on the supergravity model box 8 via bolts. The flow trough 1 has openings at both ends, connected to the two ends of the supergravity model box 8 respectively. Water enters one end of the flow trough 1 and sprays water at the other end, forming a circulating water flow. The support 9 is made of high-strength alloy steel; the flow trough 1 is made of aluminum alloy, and its annular cross-section can withstand the supergravity field of the supergravity model box 8 without deformation.

[0046] The flow-generating water tank 1 is provided with a plurality of flow-generating propellers 2, so that the water flow in the flow-generating water tank is driven by the high-speed rotation of the flow-generating propellers 2. Figure 3The flow flume 1 includes a first corner section 102, a power section 103 and a second corner section 104. One end of the first corner section 102 is provided with a water inlet 101, which is connected to one end of the supergravity model box 8 for water intake; the other end of the first corner section 102 is connected to one end of the power section 103. A plurality of flow propellers 2 are arranged at equal intervals in the power section 103, so that the water flow in the flow flume 1 is driven by the high-speed rotation of the flow propellers 2, thereby A circulating water flow is formed; the other end of the power section 103 is connected to one end of the second corner section 104, and the other end of the second corner section 104 is provided with a water outlet 106, and the water outlet 106 is connected to the other end of the supergravity model box 8 through the rectifying and diffusing section 105; an ultrasonic defoamer 3 is provided on the rectifying and diffusing section 105 (the ultrasonic defoamer 3 is fixed on the rectifying and diffusing section 105 of the flow-making trough 1 through the base 304) to puncture bubbles in the water flow through ultrasonic vibration. Among them, the power section 103 is linear; the first corner section 102 and the second corner section 104 are both arc-shaped, which can guide the water flow to turn; the rectifying diffusion section 105 is a bell-mouth type; each flow-making propeller 2 is an axial pump-jet propeller, and each flow-making propeller 2 includes blades 201 and a motor 202. The motor 202 drives the blades 201 to rotate at high speed to generate high-speed water flow, with a compact structure, high propulsion efficiency, low noise, and few bubbles generated; the angle and rotation speed of the blades 201 of the flow-making propeller 2 are adjustable.

[0047] Furthermore, the water inlet 101 and the water outlet 106 of the flow trough 1 are each provided with a rectifying plate 4 for rectifying the water flow entering and exiting the flow trough 1; the water outlet of the flow trough 1 is provided with a guide groove 5 for guiding the water flow to overcome the influence of the Coriolis force generated by the movement of the liquid in the hypergravity field; a flow meter 6 is fixedly mounted on the hypergravity model box 8 for real-time monitoring of the water flow velocity and feedback adjustment of the water flow velocity. The flow meter 6 is located in front of the outlet of the guide groove 5 and is set according to the test requirements based on the distance from the outlet of the guide groove 5. The rectifying plate 4 is made of a porous aluminum alloy plate; the guide groove 5 is composed of multiple sets of equally spaced aluminum alloy plates; the flow meter 6 is fixedly mounted on the hypergravity model box 8 via a connector 601 and is a propeller-type flow meter.

[0048] See also Figure 5The model soil box 7 is placed inside the supergravity model box 8 and in front of the outlet of the diversion chute 5, so that the model soil box 7 can withstand the erosion of the steady water flow from the outlet of the diversion chute 5. The model soil box 7 includes a soil box 701, a soil sample 702, and a structural model 703. The soil sample 702 is placed inside the soil box 701. The surface of the structural model 703 is affixed with a strain gauge to measure the internal force of the structural model 703. The structural model 703 with the strain gauge is placed inside the soil sample 702. The soil sample 702 is embedded with a soil pressure sensor, a pore pressure sensor, and a displacement sensor to monitor the impact and disturbance of waves on the soil sample 702 and the structural model 703. The soil box 701 is made of aluminum alloy.

[0049] See also Figure 6 The hypergravity model box 8 includes multiple aluminum alloy wall panels 801, which form a rectangular box. One of the aluminum alloy wall panels is provided with an observation window 802. The observation window 802 is installed with organic glass with sufficient transparency to facilitate the operator to observe the scouring of the model soil box 7 by the water flow in the hypergravity model box 8.

[0050] See also Figure 4 The ultrasonic defoamer 3 includes an ultrasonic generator 301, a power amplifier 302 and an ultrasonic sensor 303. The ultrasonic defoamer 3 generates a high-frequency signal through the ultrasonic generator 301, amplifies it through the power amplifier 302, and then transmits the amplified high-frequency signal to the high-speed water flow in the rectifying and diffusing section 105 through the ultrasonic sensor 303, causing the bubbles in the water flow to resonate and burst, thereby eliminating the bubbles in the water flow.

[0051] A propeller-type flow generation test method in a geotechnical centrifuge comprises the following steps:

[0052] Step 1: Dry the test soil material, sieve it, remove impurities, add water and stir it into a test mud with a water content of about 2 times the liquid limit.

[0053] Step 2: Pour the test slurry obtained in step 1 into the model soil box 7 and pressurize it to form a soil sample 702 of a certain density to ensure that the soil sample 702 is fully saturated. Then, bury the soil pressure, pore pressure and displacement sensors at a certain depth inside the soil sample 702.

[0054] Step 3, processing the structural model 703, pasting strain gauges on the surface of the structural model 703 (using the strain gauges to measure the internal forces of the structural model 703), and waterproofing it, then inserting the structural model 703 into the soil sample 702 at a set depth to complete the production of the model soil box 7.

[0055] Step 4: hoist the model soil box 7 made in step 3 into the pre-set position of the supergravity model box 8, and then add water into the supergravity model box 8 to a certain height.

[0056] Step 5: Arrange the flow flume 1, ultrasonic defoamer 3, rectifier plate 4, guide trough 5 and flow meter 6 on the hypergravity model box 8, and electrically connect them to the control system and sensor sampling system.

[0057] Step 6, start the flow flume 1, and form a circulating water flow through the high-speed rotation of the flow propeller 2 in the flow flume 1 (through the high-speed rotation of the flow propeller 2, the water in the supergravity model box 8 flows into the flow flume 1 from the water inlet 101 of the flow flume 1, and then flows out from the water outlet 106 of the flow flume 1). At the same time, start the ultrasonic defoamer 3 to eliminate bubbles in the water flow, and adjust the water flow rate according to the feedback of the measurement parameters of the flow meter 6 until a stable water flow is formed. Through the observation window 802 and various sensors, observe the scouring of the soil sample 702 and the structural model 703 by the water flow, simulate the current-structure-foundation interaction in the marine environment, and promote in-depth research on hot issues such as marine interaction theory, deep-sea mining, and offshore wind power.

[0058] During the test, the water flow can be guided by the guide trough 5 , and the water flow entering and flowing out of the flow trough 1 can be rectified by the rectifier plate 4 .

[0059] For ease of explanation, spatial relative terms such as "upper", "lower", "left", and "right" are used in the embodiments to illustrate the relationship between one element or feature shown in the figures and another element or feature. It should be understood that, in addition to the orientation shown in the figures, spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, the element described as being "under" other elements or features will be positioned "above" other elements or features. Therefore, the exemplary term "under" can include both upper and lower orientations. The device can be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here can be interpreted accordingly.

[0060] Moreover, relational terms such as “first” and “second” are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any actual relationship or order between these components.

[0061] 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 principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A propeller flow test method in a geotechnical centrifuge, characterized in that: The propeller-type flow-making test device in the geotechnical centrifuge includes a flow-making flume, a model soil box, a supergravity model box and a support; The flow-generating water trough is fixedly mounted on the support, the supergravity model box is fixedly mounted on the support, and the flow-generating water trough is fixedly mounted around the supergravity model box; both ends of the flow-generating water trough are open and respectively connected to the two ends of the supergravity model box, one end of the flow-generating water trough is filled with water and the other end is sprayed with water to form a circulating water flow; The flow-generating water trough is provided with a plurality of flow-generating propellers, which drive the water flow in the flow-generating water trough through high-speed rotation of the flow-generating propellers; the water outlet of the flow-generating water trough is connected to the supergravity model box through a rectifying and diffusing section; the rectifying and diffusing section is provided with an ultrasonic defoamer, which punctures bubbles in the water flow through ultrasonic vibrations; The water inlet and water outlet of the flow flume are respectively provided with rectifying plates for rectifying the water flow entering and flowing out of the flow flume; the water outlet of the flow flume is provided with a guide groove for guiding the water flow; a flow meter is fixedly installed on the hypergravity model box for real-time monitoring of the water flow velocity and feedback adjustment of the water flow velocity; The model soil box is placed inside the supergravity model box and in front of the diversion trough outlet, so that the model soil box can withstand the scouring of the stable water flow flowing out of the diversion trough outlet; The propeller-type flow generation test method in a geotechnical centrifuge comprises the following steps: Step 1: Dry the test soil material, sieve it, remove impurities, add water and stir it into a test mud with a water content of about 2 times the liquid limit; Step 2: Pour the test slurry obtained in step 1 into the model soil box and pressurize it to form a soil sample of a certain density to ensure that the soil sample is fully saturated. Then, earth pressure, pore pressure, and displacement sensors are buried at a certain depth inside the soil sample. Step 3: Process the structural model and insert the structural model into the soil sample at a set depth to complete the production of the model soil box; Step 4, hoisting the model soil box made in step 3 into a pre-set position of the hypergravity model box, and then adding water to the hypergravity model box to a certain height; Step 5: Arrange the flow flume, ultrasonic defoamer, rectifier, guide trough and flow meter on the hypergravity model box and electrically connect them to the control system and sensor sampling system; Step 6: Start the flow flume, and form a circulating water flow through the high-speed rotation of the flow-generating propeller in the flow flume. At the same time, turn on the ultrasonic defoamer to eliminate bubbles in the water flow, and adjust the water flow rate according to the feedback of the measurement parameters of the flow meter until a stable water flow is formed. Through the observation window and various sensors, observe the scouring of the water flow on the soil sample and the structural model, simulating the interaction between the ocean current, structure and foundation in the marine environment.

2. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The flow-generating flume is fixedly mounted on the support via a support frame, and the flow-generating flume is fixedly mounted on the supergravity model box via bolts; The flow-making water trough includes a first corner section, a power section and a second corner section. A water inlet is provided at one end of the first corner section, and the water inlet is connected to one end of the supergravity model box for water intake; the other end of the first corner section is connected to one end of the power section, and a plurality of flow-making propellers are arranged at equal intervals in the power section; the other end of the power section is connected to one end of the second corner section, and a water outlet is provided at the other end of the second corner section, and the water outlet is connected to the other end of the supergravity model box through a rectifying and diffusing section.

3. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The power section is linear; the first corner section and the second corner section are both arc-shaped; and the rectifying and diffusing section is bell-mouth-shaped.

4. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The ultrasonic defoamer is fixed on the rectifying and diffusing section of the flow-making flume through a base.

5. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: Each flow-making propeller is an axial pump-jet propeller; Each flow-making propeller includes blades and a motor, and the motor drives the blades to rotate at high speed to generate high-speed water flow.

6. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The flow meter is fixedly mounted on the supergravity model box via a connecting piece, and the flow meter is a propeller-type flow meter.

7. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The model soil box includes a soil box, a soil sample and a structural model. The soil sample is arranged inside the soil box. A strain gauge is attached to the surface of the structural model to measure the internal force of the structural model. The structural model with the strain gauge is arranged inside the soil sample.

8. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The hypergravity model box includes multiple aluminum alloy wall panels, which form a rectangular box. One of the aluminum alloy wall panels is provided with an observation window, which is installed with organic glass for observing the scouring of the model soil box by the water flow in the hypergravity model box.

9. The propeller flow test method in a geotechnical centrifuge according to claim 1, characterized in that: The ultrasonic defoamer includes an ultrasonic generator, a power amplifier and an ultrasonic sensor. The ultrasonic defoamer generates a high-frequency signal through the ultrasonic generator, amplifies it through the power amplifier, and then transmits the amplified high-frequency signal to the high-speed water flow in the rectification and diffusion section through the ultrasonic sensor, causing the bubbles in the water flow to resonate and burst, thereby eliminating the bubbles in the water flow.

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