Seabed slope wave scouring resistance supergravity test method

Abstract

The invention discloses a seabed slope wave scouring resistance supergravity test method which comprises the following steps: inserting an ocean platform model into the slope surface of a seabed slope model through supporting piles at the bottom of the ocean platform model, and integrally placing the ocean platform model at a test end in a supergravity model box; the flushing box type wave generator is arranged at the wave making end of the supergravity flushing model box; the monitoring sensor system is arranged at set positions of the seabed slope model and the offshore platform model and is used for monitoring soil pressure, pore pressure and displacement changes in the whole damage process of the seabed slope model; a monitoring industrial camera is arranged and used for recording the form change of the seabed slope model in the whole process of being scoured and eroded. According to the test method, the catastrophe process of the seabed slope and the ocean structure under wave scouring can be truly simulated, the scouring, erosion, morphological evolution and parameter dynamic response process of the seabed slope can be truly recorded, the test precision is high, and the repeatability is high.

Description

Technical Field

[0001] This invention belongs to the field of marine engineering model testing technology, specifically relating to a method for testing the resistance of seabed slopes to wave erosion under ultragravity. Background Technology

[0002] During the development of marine resources, submarine landslides occur frequently, posing a serious threat to marine engineering structures and the lives of personnel involved. Especially in harsh open sea conditions, extreme winds, waves, and currents can cause large deformations in seabed slopes and structures, easily triggering large-scale submarine landslides and resulting in major marine engineering disasters. Therefore, in-depth research on the stability of seabed slopes against wave erosion is urgently needed.

[0003] Currently, research on the wave erosion stability of seabed slopes mainly employs methods from landslide analysis, such as the empirical slope ratio method, the limit equilibrium method, or numerical simulation. However, these methods struggle to realistically simulate the erosive effects of waves and the weakening effect of slope soil under long-term wave action. In terms of physical simulation techniques, model tests are primarily used to simulate the dynamic response of pore pressure in seabed soil under wave action or the liquefaction process of sandy seabeds, lacking methods for simulating the wave erosion process of seabed slopes. Model tests under hypergravity fields can reproduce the true stress state of the soil and have time-scaling and scale-down effects, making them an effective method for studying this problem.

[0004] Therefore, there is an urgent need to develop a supergravity test device for wave-induced erosion of seabed slopes to realistically simulate the erosion and damage process of waves on seabed slopes and marine structures, and to provide an effective test platform for studying the erosion, erosion, morphological changes of seabed slopes and the dynamic response of marine structures under wave action. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hypergravity test method for wave erosion resistance of seabed slopes. This method can realistically simulate the erosion and damage process of waves on seabed slopes and marine structures, overcome the problem that wave erosion under hypergravity fields cannot be continuously simulated, and can realistically record the erosion, morphological evolution and dynamic parameter response process of seabed slopes. The test has high accuracy and strong repeatability.

[0006] This invention is achieved through the following technical solution: A method for conducting a hypergravity test on the wave erosion resistance of a seabed slope includes: a hypergravity erosion model box, a wave generator, a seabed slope model, and a marine platform model; the hypergravity erosion model box is composed of an aluminum alloy box body and an plexiglass observation surface; the marine platform model is inserted into the slope surface of the seabed slope model via support piles at its bottom and is placed entirely within the test end of the hypergravity model box; the wave generator is located at the wave-generating end of the hypergravity erosion model box opposite to the test end; The method for conducting a wave erosion resistance test on a seabed slope under hypergravity conditions is as follows: Step 1: Sieve the test soil to remove impurities, then add water and stir to prepare the test soil sample; Step 2: Apply a layer of transparent grease to the inside of the super gravity flushing model box; Step 3: Divide the test soil sample into multiple portions of equal mass, and then take one portion of the test soil sample one by one and pour it evenly into the super gravity scour model box. Use a compaction hammer to compact it to ensure that the density of each soil layer is consistent. Also, roughen the interface between the soil layers to ensure that the soil layers are compacted. Prepare the foundation soil layers from bottom to top. Step 4: After the foundation soil layer is prepared to the design height, the pore pressure sensor and the soil pressure pore pressure sensor are buried in the set position; Step 5: After the foundation soil layer is compacted, the slope is cut according to the designed slope ratio to prepare the seabed slope model. Then, the marker points are pasted on the plexiglass observation surface corresponding to the seabed slope model to provide reference points for PIV image deformation analysis in the experiment. Step 6: Design the marine platform model according to the model similarity rate, attach strain gauge sensors and displacement sensors to the surface of the marine platform model and waterproof them, then cut appropriate grooves on the support piles, embed the pore pressure sensor and acceleration sensor in them and attach them firmly, and finally press the entire marine platform model into the seabed slope model at the set depth. Step 7: Inject seawater into the supergravity scouring model box to match the sea level of the model with that of the prototype and maintain a stable water level; Step 8: Hoist the entire hypergravity scour model box into the geotechnical centrifuge, connect the data acquisition channels, and securely tie the sensor data cables to ensure that each sensor channel can collect data normally. Then, fix the monitoring industrial camera on the plexiglass observation surface of the hypergravity scour model box and above the seabed slope model. Step 9: Start the geotechnical centrifuge to generate a stable hypergravity field. Once the hypergravity field reaches the set strength, start the wave generator to generate regular waves. Repeatedly scour the seabed slope model and the offshore platform model, observe the scouring, erosion, and morphological changes of the seabed slope model, and record the dynamic response of the soil in the seabed slope model and the offshore platform model.

[0007] In the above technical solution, the bottom of the supergravity scouring model box is provided with an energy-absorbing flexible pad to absorb the vibration generated during the wave generation process and reduce the reflection of vibration waves at the bottom of the model box.

[0008] In the above technical solution, the acrylic glass observation surface is made of a single piece of acrylic glass; the outer surface of the acrylic glass observation surface is coated to reduce the rainbow effect under light; a lighting system is arranged on the outer side of the acrylic glass observation surface to produce a shadowless lamp effect, so as to reduce the graphic distortion caused by light and shadow flicker and provide a stable background for PIV image analysis.

[0009] In the above technical solution, the box-type wave generator includes a triangular box block, a servo motor, and a vertical drive mechanism. The triangular box block is connected to the bottom of the vertical drive mechanism, and the servo motor is connected to the vertical drive mechanism as a power source, thereby driving the vertical drive mechanism to move the triangular box block up and down, impacting the water surface to generate regular waves.

[0010] In the above technical solution, the vertical drive mechanism adopts the following structure: it includes guide columns, a mounting frame, a first rocker arm, and a second rocker arm. Two guide columns are vertically slidably mounted on the mounting frame, located on either side of the servo motor. The bottom end of each guide column is connected to the triangular impact block, thus allowing the triangular impact block to move vertically up and down. The drive shaft of the servo motor is fixedly connected to one end of the first rocker arm, the other end of which is hinged to one end of the second rocker arm, and the other end of the second rocker arm is hinged to the triangular impact block. During operation, the servo motor drives the first and second rocker arms to move the triangular impact block up and down, striking the water surface to create waves.

[0011] The advantages and beneficial effects of this invention are as follows: This invention provides an effective test method for the stability of seabed slopes against wave erosion. It can realistically simulate the catastrophic process of seabed slopes and marine structures under wave erosion, overcoming the previous problem that wave erosion under hypergravity fields could not be continuously simulated. It can also realistically record the erosion, erosion, morphological evolution and dynamic parameter response process of seabed slopes. The test has high accuracy and strong repeatability.

[0012] The seabed slope model set up in this invention can not only study wave erosion, but also act as a wave-absorbing device to reduce wave reflection and improve the accuracy of wave simulation under hypergravity fields.

[0013] This invention employs non-contact PIV measurement technology to record and measure the morphological evolution and displacement field during the scouring and damage process of seabed slopes. It avoids the disturbance of experimental results by previous measurement factors, has high measurement accuracy, and strong image visualization, making it an effective means of studying the morphological evolution of seabed slopes. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a supergravity test device for wave erosion resistance of seabed slopes.

[0015] Figure 2This is a schematic diagram of the supergravity scouring model box.

[0016] Figure 3 This is a schematic diagram of a punching box wave generator.

[0017] Figure 4 This is a schematic diagram of the vertical drive mechanism of a punch-box wave generator.

[0018] Figure 5 It is a three-dimensional schematic diagram of a seabed slope model and an offshore platform model.

[0019] Figure 6 This is a frontal view of the seabed slope model and the offshore platform model.

[0020] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below with reference to specific embodiments.

[0022] This embodiment provides a method for testing the resistance of a submarine slope to wave erosion under ultragravity conditions. This method employs a testing apparatus, see attached diagram. Figure 1 - Appendix Figure 6 The experimental setup includes: a hypergravity scour model box 1, a wave generator 2, a seabed slope model 3, an offshore platform model 4, a monitoring sensor system 5, and a monitoring industrial camera 6. The hypergravity scour model box 1 is entirely placed inside a geotechnical centrifuge, where the high-speed rotation of the centrifuge generates a hypergravity field to restore the model's stress state. The offshore platform model 4 is inserted into the slope of the seabed slope model 3 via support piles 4-2 at its bottom and is placed entirely within the test end of the hypergravity model box 1. The wave generator 2 is located at the wave-generating end of the hypergravity scour model box 1 opposite to the test end, generating waves through regular impacts on the water surface to simulate the scour process of the seabed slope and marine structures. The monitoring sensor system 5 is positioned at designated locations on the seabed slope model 3 and the offshore platform model 4 to monitor soil pressure, pore pressure, and displacement changes during the failure process of the seabed slope model 3. The monitoring industrial camera 6 records the morphological changes of the seabed slope model 3 during scour and erosion.

[0023] For the preferred option, see Appendix Figure 2The hypergravity scour model box 1 consists of an aluminum alloy box body 1-1 and an acrylic glass observation surface 1-2, connected by bolts and waterproofed to ensure no plastic deformation or leakage in the hypergravity field. Furthermore, an energy-absorbing flexible pad 1-3 is installed at the bottom of the hypergravity scour model box 1 to absorb vibrations generated during wave generation and reduce vibration wave reflection from the bottom of the box. Furthermore, the acrylic glass observation surface 1-2 is made from a single piece of acrylic glass, ensuring sufficient strength and transparency, and coordinate points 1-4 are set around its perimeter to provide initial coordinates for PIV image analysis. Furthermore, the outer surface of the acrylic glass observation surface is coated 1-5 to reduce rainbow effects under light. Furthermore, a lighting system 1-6 is arranged on the outer side of the acrylic glass observation surface to produce a shadowless lighting effect, reducing graphic distortion caused by light flicker and providing a stable background for PIV image analysis.

[0024] For the preferred option, see Appendix Figure 3 The wave generator 2 includes a triangular impact block 2-1, a servo motor 2-2, and a vertical drive mechanism 2-3. The triangular impact block 2-1 is connected to the bottom of the vertical drive mechanism 2-3. The servo motor 2-2 serves as a power source connected to the vertical drive mechanism 2-3, thereby driving the vertical drive mechanism 2-3 to move the triangular impact block 2-1 up and down, impacting the water surface to generate regular waves. Furthermore, the included angle of the triangular impact block 2-1 is 35 degrees. This angle has been experimentally verified to generate waves of sufficient amplitude while preventing excessive impact energy from causing wave turbulence, making it the most efficient angle for wave generation. Further details are provided in the appendix. Figure 4 The vertical drive mechanism 2-3 can adopt the following structure: including a guide post 2-31, a mounting frame 2-32, a first rocker arm 2-33, and a second rocker arm 2-34, wherein the guide post 2-31 is vertically slidably mounted on the mounting frame 2-32. The guide posts 2-31 are preferably two in number, located on both sides of the servo motor 2-2. The bottom end of the guide posts 2-31 is connected to the triangular impact box block 2-1, thereby giving the triangular impact box block 2-1 the freedom to move vertically up and down. The servo motor 2-2 is horizontally mounted on the top of the super gravity scouring model box 1. The drive shaft of the servo motor 2-2 is fixedly connected to one end of the first rocker arm 2-33. The other end of the first rocker arm 2-33 is hinged to one end of the second rocker arm 2-34. The other end of the second rocker arm 2-34 is hinged to the triangular impact box block 2-1. During operation, the servo motor 2-2 drives the first rocker arm 2-33 and the second rocker arm 2-34 to move the triangular impact box block 2-1 up and down, striking the water surface and creating waves.

[0025] For the preferred option, see Appendix Figure 5 and attached Figure 6The seabed slope model 3 is made of marine silt or sand, and its slope ratio, height, and water depth are adjustable to meet the needs of simulating natural seabed slopes under different conditions. Furthermore, displacement markers 3-1 are set on one side of the plexiglass observation surface 1-2 of the seabed slope model 3 to observe the scouring and deformation process of the slope. Furthermore, pore pressure sensors 5-1 and earth pressure sensors 5-2 are arranged inside the seabed slope model 3 to monitor the dynamic response within the slope soil. Furthermore, at the test end of the hypergravity scouring model box 1, the seabed slope model 3 can absorb most of the waves to reduce wave reflection and keep the wave waveform stable for a long time. This ensures that the seabed slope model 3 obtains a continuous wave scouring effect and also acts as a wave-absorbing mechanism, further improving the efficiency of the experiment.

[0026] For the preferred option, see Appendix Figure 5 and attached Figure 6 The marine platform model 4 includes a platform body 4-1 and supporting piles 4-2 at its base, both made of metal. Its overall bending stiffness meets the requirements of the experimental similarity relationship. The supporting piles 4-2 are driven into the bearing layer of the seabed slope model 3, interacting with the seabed slope model 3 to jointly withstand wave erosion. Furthermore, pore pressure sensors 5-1 are arranged at equal intervals along the height direction on the wave-facing side of the supporting piles 4-2 to monitor the distribution of wave forces. Further, acceleration sensors 5-3 are arranged at equal intervals along the height direction on the wave-avoiding side of the supporting piles 4-2 to monitor the dynamic response at different locations on the supporting piles 4-2. Furthermore, displacement sensors 5-4 and strain gauge sensors 5-5 are arranged on the platform body 4-1 to monitor the deformation and internal force distribution of the platform body 4-1.

[0027] As a preferred embodiment, the monitoring sensor system 5 includes a pore pressure sensor 5-1, an earth pressure sensor 5-2, an acceleration sensor 5-3, a displacement sensor 5-4, and a strain gauge sensor 5-5, which are respectively arranged at key locations on the seabed slope model 3 and the offshore platform 4 to monitor the dynamic response and deformation values ​​of the model under wave scouring in real time, providing high-precision data for experimental analysis.

[0028] As a preferred embodiment, the monitoring industrial camera 6 is a high-speed, high-precision industrial camera, which is respectively arranged on the side and top of the seabed slope model 3. It can record the scouring and destruction process of the seabed slope model 3 in real time, and provide high-quality image materials for the analysis of the morphological changes and disaster mechanisms of the seabed slope.

[0029] The method for conducting a wave erosion resistance test on a seabed slope using the above-mentioned test apparatus is as follows: Step 1: Sieve the test soil to remove impurities, then add water and stir to make a loose soil sample with a certain moisture content. After the moisture content of the test soil sample stabilizes, it can be used for later use.

[0030] Step 2: Apply a layer of transparent grease to the inside of the super gravity flushing model box 1 to reduce friction on the side walls.

[0031] Step 3: Divide the test soil sample into multiple portions of equal mass, and then take one portion of the test soil sample one by one and pour it evenly into the gravity scour model box 1. Use a compaction hammer to compact it to ensure that the density of each soil layer is consistent. Also, roughen the interface between the soil layers to ensure that the soil layers are compacted. In this way, the foundation soil layers are prepared sequentially from bottom to top.

[0032] Step 4: After the foundation soil layer is prepared to the design height, pore pressure sensor 5-1 and earth pressure pore pressure sensor 5-2 are buried in the set position, and the sensor data lines are led out in parallel along the horizontal direction to prevent the sensors from interfering with each other.

[0033] Step 5: After the foundation soil layer is compacted, the slope is cut according to the designed slope ratio to prepare the seabed slope model 3. Then, the marker point 3-1 is pasted on the outer surface of the plexiglass observation surface corresponding to the seabed slope model to provide a reference point for the PIV image deformation analysis in the experiment.

[0034] Step 6: Design the marine platform model 4 according to the model similarity rate and use metal materials similar to the engineering prototype to ensure that its overall bending stiffness meets the similarity requirements. After processing and welding, attach strain gauge sensors 5-5 and displacement sensors 5-4 to the surface of the marine platform model 4 and waterproof them. Then, make appropriate grooves on the support piles 4-2 and embed the pore pressure sensor 5-1 and acceleration sensor 5-3 into them and attach them firmly. Finally, press the marine platform model 4 into the seabed slope model 3 at the set depth and lead the data lines of each sensor upward.

[0035] Step 7: Inject seawater into the supergravity scouring model box 1 to match the sea level of the model with that of the prototype and maintain a stable water level.

[0036] Step 8: Hoist the entire supergravity scour model box 1 into the geotechnical centrifuge, connect the data acquisition channels, and securely tie the sensor data cables to ensure that each sensor channel can collect data normally. Then, fix the monitoring industrial camera 6 above the plexiglass observation surface 1-2 of the supergravity scour model box 1 and the seabed slope model 3, lock the focal length of the industrial camera, so that the side and upper surface of the seabed slope model 3 can obtain clear images. Then turn on the lighting system 1-6, adjust the direction and intensity of the light, and ensure that there are no shadows in the field of view.

[0037] Step 9 involves starting the geotechnical centrifuge to generate a stable hypergravity field. Once the hypergravity field reaches the set intensity, the wave generator 2 will be started to generate regular waves that repeatedly scour the seabed slope model 3 and the offshore platform model 4. The scouring, erosion, and morphological changes of the seabed slope model 3 will be observed, and the dynamic responses of the soil in the seabed slope model 3 and the offshore platform model 4 will be recorded to further study the mechanism of wave scouring-induced seabed landslides.

[0038] For ease of explanation, spatial relative terms such as “up,” “down,” “left,” and “right” are used in the embodiments to describe the relationship of one element or feature shown in the figures relative to another element or feature. It should be understood that, in addition to the orientations 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 figures is inverted, an element described as being “down” of other elements or features would be positioned “up” of those other elements or features. Therefore, the exemplary term “down” can encompass both up and down orientations. The device may be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein can be interpreted accordingly. Moreover, relational terms such as “first” and “second” are used merely to distinguish one component from another that has the same name, and do not necessarily require or imply any such actual relationship or order between the components.

[0039] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for testing the resistance of a submarine slope to wave erosion under ultragravity conditions, characterized in that: include: The system comprises a hypergravity scour model box, a scour-type wave generator, a seabed slope model, and an offshore platform model. The hypergravity scour model box consists of an aluminum alloy box body and an acrylic glass observation surface. The offshore platform model is inserted into the slope surface of the seabed slope model via support piles at its bottom and is placed entirely within the test end of the hypergravity model box. The scour-type wave generator is located at the wave-generating end of the hypergravity scour model box, opposite to the test end. The method for conducting a wave erosion resistance test on a seabed slope under hypergravity conditions is as follows: Step 1: Sieve the test soil to remove impurities, then add water and stir to prepare the test soil sample; Step 2: Apply a layer of transparent grease to the inside of the super gravity flushing model box; Step 3: Divide the test soil sample into multiple portions of equal mass, and then take one portion of the test soil sample one by one and pour it evenly into the super gravity scour model box. Use a compaction hammer to compact it to ensure that the density of each soil layer is consistent. Also, roughen the interface between the soil layers to ensure that the soil layers are compacted. Prepare the foundation soil layers from bottom to top. Step 4: After the foundation soil layer is prepared to the design height, the pore pressure sensor and the soil pressure pore pressure sensor are buried in the set position; Step 5: After the foundation soil layer is compacted, the slope is cut according to the designed slope ratio to prepare the seabed slope model. Then, the marker points are pasted on the plexiglass observation surface corresponding to the seabed slope model to provide reference points for PIV image deformation analysis in the experiment. Step 6: Design the marine platform model according to the model similarity rate, attach strain gauge sensors and displacement sensors to the surface of the marine platform model and waterproof them, then cut appropriate grooves on the support piles, embed the pore pressure sensor and acceleration sensor in them and attach them firmly, and finally press the entire marine platform model into the seabed slope model at the set depth. Step 7: Inject seawater into the supergravity scouring model box to match the sea level of the model with that of the prototype and maintain a stable water level; Step 8: Hoist the entire hypergravity scour model box into the geotechnical centrifuge, connect the data acquisition channels, and securely tie the sensor data cables to ensure that each sensor channel can collect data normally. Then, fix the monitoring industrial camera on the plexiglass observation surface of the hypergravity scour model box and above the seabed slope model. Step 9: Start the geotechnical centrifuge to generate a stable hypergravity field. Once the hypergravity field reaches the set strength, start the wave generator to generate regular waves. Repeatedly scour the seabed slope model and the offshore platform model, observe the scouring, erosion, and morphological changes of the seabed slope model, and record the dynamic response of the soil in the seabed slope model and the offshore platform model.

2. The method for testing the resistance of seabed slopes to wave erosion under ultragravity according to claim 1, characterized in that: The bottom of the supergravity scouring model box is equipped with an energy-absorbing flexible pad to absorb the vibration generated during wave generation and reduce the reflection of vibration waves from the bottom of the model box.

3. The method for testing the resistance of submarine slopes to wave erosion under ultragravity according to claim 1, characterized in that: The punching box wave generator includes a triangular punching box block, a servo motor, and a vertical drive mechanism. The triangular punching box block is connected to the bottom of the vertical drive mechanism, and the servo motor is connected to the vertical drive mechanism as a power source.

4. The method for testing the resistance of submarine slopes to wave erosion under ultragravity according to claim 3, characterized in that: The vertical drive mechanism adopts the following structure: it includes guide columns, a mounting frame, a first rocker arm, and a second rocker arm. The guide columns are vertically slidably mounted on the mounting frame. There are two guide columns, located on both sides of the servo motor. The bottom end of the guide column is connected to the triangular punch block, thereby giving the triangular punch block the freedom to move vertically up and down through the guide columns. The drive shaft of the servo motor is fixedly connected to one end of the first rocker arm. The other end of the first rocker arm is hinged to one end of the second rocker arm, and the other end of the second rocker arm is hinged to the triangular punch block.

5. The method for testing the resistance of submarine slopes to wave erosion under ultragravity according to claim 1, characterized in that: The acrylic glass observation surface is made from a single piece of acrylic glass.

6. The method for testing the resistance of submarine slopes to wave erosion under ultragravity according to claim 1, characterized in that: The outer surface of the acrylic glass observation surface is coated to reduce the rainbow effect under light.

7. The method for testing the resistance of seabed slopes to wave erosion under ultragravity according to claim 1, characterized in that: A lighting system is installed on the outer side of the plexiglass observation surface.

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