Device and method for synchronously measuring wave force and pile foundation scouring in real time

Abstract

The invention discloses a device and a method for synchronously measuring wave force and pile foundation scouring in real time, the device is used for a single-pile physical model in an ocean structure, the device comprises a vertical cylinder, an upper cylinder, a lower cylinder, a fixed pulley, a slidable bolt, a fixed chassis, a high-elastic rubber pipe and a steel wire rope, and a gap is reserved between the upper cylinder and the lower cylinder; when the bottom round hole of the upper cylinder and the top round hole of the lower cylinder are aligned by utilizing the slidable bolt, the bolt is automatically located in the lower cylinder under the traction of the high-elastic rubber tube on the fixed chassis, and the wave force borne by the cylinders can be measured after the force sensor is fixed at the top end of the upper cylinder. After the lower cylinder is buried in a sand bed, pile foundation scouring can be achieved under the condition of incoming waves and incoming flows. The device can simultaneously complete measurement of wave force and pile foundation scouring, solves the problem that pure wave force cannot be measured due to bottom bed stress after the pile foundation is buried in a sand bed, can better reproduce actual conditions faced by the pile foundation of an ocean structure, and lays a foundation for wave force research under pile foundation scouring.

Description

Technical Field

[0001] This invention relates to the field of marine engineering physical model testing technology, and in particular to a device and method for synchronously and in real time measuring wave force and pile scour in a laboratory water tank. Background Technology

[0002] In the field of marine engineering, pile foundation structures (such as offshore wind turbine monopiles and offshore platform jackets) are widely used to support superstructures. These pile foundations are subjected to dynamic loads such as waves and currents over long periods of time, while the surrounding seabed experiences localized scouring, significantly reducing the bearing capacity and stability of the pile foundations. Therefore, studying the interaction mechanism between wave forces and pile foundation scouring through physical models in a laboratory tank is crucial for engineering safety design.

[0003] However, existing experimental techniques have significant limitations. Limited measurement functionality: Traditional experimental setups typically only measure wave force or observe scour patterns individually, making it difficult to perform both measurements simultaneously under the same model and experimental conditions. Step-by-step experiments introduce errors due to subtle differences in wave conditions and water flow, failing to accurately reflect the dynamic coupling effect between wave force and scour pit development. Inability to separate pure wave force: When the pile foundation model is embedded in the sand bed, the force acting on it is the coupling result of wave force and complex subsurface stress. Existing technologies struggle to separate the pure wave dynamic load from the pile-soil interaction, resulting in the inability to obtain accurate "pure wave force" data, thus hindering the precise quantification of the impact of scour pits on the magnitude and distribution of wave force. Poor model-to-actual fit: Most wave force measurement models do not consider the impact of the pile embedment section and scour, and models combined with scour experiments often cannot simultaneously measure forces, failing to fully reproduce the true physical environment of the marine pile foundation.

[0004] Therefore, there is an urgent need for an experimental device that can integrate two measurement functions and effectively separate different forces to deepen the understanding of the dynamic response of pile foundations under wave-flow-scour coupling. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, this invention proposes a device and method for synchronously and in real time measuring wave force and pile foundation scour, so as to achieve synchronous and accurate measurement of wave force acting on marine pile foundation and the development of local scour pits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a device for synchronously and in real-time measuring wave force and pile foundation scour, the device comprising: The upper cylinder has a three-dimensional force sensor fixed at its top and a first circular hole at its bottom. The lower cylinder is used to be embedded in the sand bed of the sand pit in the water inlet trough. The top is provided with a second round hole for matching with the first round hole. A sliding pin is used to pass through the first and second round holes to connect or separate the upper cylinder and the lower cylinder, thereby realizing a detachable connection between the upper cylinder and the lower cylinder. A fixed base is fixedly installed inside the lower cylinder; A high-elasticity rubber tube is used to connect the fixed chassis and the sliding pin, providing traction force for the sliding pin to automatically reset; A steel wire rope, one end of which is connected to the sliding pin for pulling and moving the sliding pin, and the other end of which passes through the steel wire rope positioning hole on the flange to achieve manual or mechanical control.

[0007] Furthermore, when the first and second circular holes are aligned, pulling the steel wire rope allows the sliding pin to overcome the traction force of the high-elasticity rubber tube, move to the middle of the first and second circular holes, and lock, connecting the upper and lower cylinders. After releasing the steel wire rope, under the traction of the high-elasticity rubber tube, the sliding pin automatically slides into the lower cylinder, separating the upper and lower cylinders. In this separated state, the steel wire rope is completely relaxed and cannot transmit force to the upper cylinder and its internal force sensor through a taut path. Simultaneously, its small diameter causes negligible interference to the flow field around the main structure and does not produce significant additional mass effects.

[0008] Furthermore, the upper cylinder and the lower cylinder have the same diameter, the height of the upper cylinder ensures that the force sensor will not be splashed with water after water is added to the water tank, and the height of the lower cylinder ensures that it is completely buried in the sand bed and slightly higher than the surface of the sand bed.

[0009] Furthermore, the sliding pin is cylindrical with a rounded, inwardly tapered top, facilitating its upward sliding through the first circular hole under tension. A counterweight is connected to the outside of the water tank by pulling a steel wire rope, and the weight of this counterweight keeps the sliding pin locked. The steel wire rope is attached to a hook-shaped screw. The upper end of the sliding pin has an upper thread, and the hook-shaped screw is screwed into the upper end of the sliding pin to ensure a tight connection between the steel wire rope and the pin. The high-elasticity rubber tube is attached to the hook-shaped screw and secured with a cable tie. The lower end of the sliding pin has a lower thread, and the hook-shaped screw is screwed into the lower end of the sliding pin to ensure a tight connection between the high-elasticity rubber tube and the pin.

[0010] Furthermore, the elastic modulus of the high-elasticity rubber tube is 2-5 MPa, and its tensile range is more than three times its own length.

[0011] Furthermore, the upper end of the high-elasticity rubber tube is connected to a hook-shaped screw, and the lower end is wrapped around a cross bracket in the center hole of the fixed chassis and secured with cable ties.

[0012] Furthermore, the fixed base is fixed to the bottom of the lower cylinder by radial adjustment bolts. The placement height of the fixed base needs to ensure that the pin of the high-elastic rubber tube connected to it does not protrude from the second round hole of the lower cylinder in the natural state, and that the pin is higher than the first round hole of the upper cylinder in the maximum tensile state.

[0013] Furthermore, the gap between the upper cylinder and the lower cylinder is adjustable, which is achieved by adjusting the number of gaskets provided on the upper flange of the upper cylinder.

[0014] Furthermore, the wire rope is made of stainless steel, has a diameter of 2-4 mm, and has a polytetrafluoroethylene coating on its surface.

[0015] Furthermore, the device also includes a fixed pulley and an upper bracket. The fixed pulley is used to guide the steel wire rope to change direction, making it easier to move the pin manually or mechanically. The upper bracket is used to connect to the three-dimensional force sensor above the experimental water tank, thereby fixing the upper cylinder.

[0016] On the other hand, the present invention also provides a method for synchronously and in real-time measuring wave force and pile foundation scour, the method comprising the following steps: 1) Embed the lower cylinder into the sand pit. After aligning the first hole of the upper cylinder with the second hole of the lower cylinder, fix the force sensor to the top of the upper cylinder in sequence, and fix the upper bracket to the top of the force sensor. 2) Place the fixed base in the appropriate position inside the lower cylinder, connect it to the high-elasticity rubber tube, and then adjust the sliding state of the pin to see if it meets the requirements. If it does, use high-viscosity glue to secure it firmly. 3) After the wire rope is connected to the pin, it passes through the second round hole of the lower cylinder, the first round hole of the upper cylinder, the third round hole on the upper cylinder flange (9), and the fixed pulley in sequence; 4) After installation, before the formal experiment, it is necessary to test the normal working status of each component, such as whether the round holes are aligned and whether the pins can be smoothly slid out and in. 5) Simple wave force measurement mode: The upper and lower cylinders are separated in the slack state of the wire rope, and the simple wave force data under different wave conditions are recorded; 6) Coupling effect measurement mode: By pulling and fixing the steel wire rope to connect the upper and lower cylinders, wave force data including the stress of the bed can be recorded, and the morphological development of the scour pit can be recorded through images.

[0017] The beneficial effects of this invention are: 1) This invention achieves simultaneous and accurate measurement of wave force and scour morphology, solving the problem of limited measurement functionality. By integrating the wave force measurement module and the scour module of erosive sand beds into the same experimental system, this invention can simultaneously collect dynamic development data of the wave force on the pile foundation and the morphology of the surrounding scour pits under identical wave, water flow, and bed conditions. This eliminates the errors introduced by the difficulty in completely reproducing wave and water flow conditions in step-by-step experiments, and can truly capture the dynamic coupling effect of wave force and scour pits during their development, providing a reliable and consistent data foundation for studying the interaction mechanism between the two.

[0018] 2) The invention innovatively separates and quantifies the "pure wave force," solving the problem of the difficulty in decomposing coupled forces. Addressing the difficulty in decoupling wave force from subsoil stress after pile foundations are embedded in sand beds, this invention designs a unique hollow segmented pile foundation model structure, which can effectively separate and calculate the "pure wave force" component acting on the pile foundation.

[0019] 3) This invention fully replicates the real physical environment of marine pile foundations from initial installation to local scour development by setting the pile foundation model in a suspended installation mode that can penetrate the sand bed and combining it with an adjustable and erosive sand bed. The model no longer measures forces or observes scour in isolation, but simulates the complex interaction between pile, soil, waves, and water flow as a whole system, greatly enhancing the realism of experimental results and the predictive ability for prototype working conditions. Attached Figure Description Figure 1 This is a schematic diagram of the working scenario of the present invention.

[0020] Figure 2 This is a schematic diagram of the pin structure in this invention.

[0021] Figure 3 This is a schematic diagram showing the connection between the pin, the high-elasticity rubber tube, and the fixed chassis in this invention.

[0022] Figure 4 This is a schematic diagram of the flange structure of the upper cylinder in this invention.

[0023] Figure 5 This is a diagram showing the connection state of the upper and lower cylinders in this invention.

[0024] Figure 6 This is a diagram showing the separation of the upper and lower cylinders in this invention.

[0025] The components include: 1. Sliding pin; 2. High-elasticity rubber tube; 3. Fixed base; 4. Fixed pulley; 5. Steel wire rope; 6. Upper cylinder; 7. Lower cylinder; 8. Three-dimensional force sensor; 9. Flange; 10. Sandpit; 11. Upper bracket; 101. Upper hook screw; 102. Lower hook screw; 103. Rounded surface; 104. Upper thread; 105. Lower thread; 201. First radial adjusting bolt; 202. Second radial adjusting bolt; 203. Bottom of lower cylinder; 204. Upper cable tie; 205. Lower cable tie; 206. Cross bracket; 301. Steel wire rope positioning hole; 302. Force sensor mounting slot; 303. Six circumferentially distributed fixing screws. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] like Figure 1 As shown, this invention provides a device for synchronously and in real-time measuring wave force and pile foundation scour, typically used in laboratory experiments with large, medium, and small water tanks. It includes an upper cylinder 6, a lower cylinder 7, a sliding pin 1, a fixed base 3, a high-elastic rubber tube 2, a steel wire rope 5, a fixed pulley 4, and an upper support 11. A three-dimensional force sensor 8 is fixed to the top of the upper cylinder 6, and the lower cylinder 7 is pre-embedded in the sand bed of the sand pit 10 within the water tank. The upper cylinder 6 and the lower cylinder 7 have the same diameter, with an adjustable gap between them.

[0028] The upper cylinder 6 has a first circular hole at its bottom, and the lower cylinder 7 has a second circular hole at its top. When the first and second circular holes are aligned, pulling the steel wire rope 5 allows the sliding pin 1 to overcome the traction force of the high-elasticity rubber tube 2, move to the middle of the two circular holes, and lock, connecting the upper and lower cylinders. After releasing the steel wire rope 5, under the traction of the high-elasticity rubber tube 2, the sliding pin 1 automatically slides into the lower cylinder, separating the upper and lower cylinders. In this separated state, although the steel wire rope 5 is still located inside the upper cylinder, it is in a completely relaxed state. This design ensures that the interaction force between the steel wire rope and the water flow cannot be transmitted to the upper cylinder and the force sensor inside through a taut path. At the same time, its small diameter has negligible interference with the flow field around the main structure and does not produce significant additional mass effects. Therefore, the relaxed steel wire rope will not interfere with the accurate measurement of wave force, effectively ensuring the accuracy of experimental data.

[0029] Figure 2The structure of the sliding pin 1 is shown. The pin is cylindrical, with its top tapering inward to form a rounded surface 103. This design effectively reduces friction and facilitates upward sliding through the round hole under tension. The upper end of the sliding pin is machined with an upper thread 104 for screwing and fixing the upper hook-shaped screw 101; the lower end is machined with a lower thread 105 for screwing and fixing the lower hook-shaped screw 102. A steel wire rope 5 is securely fastened to the upper hook-shaped screw 101 to provide tension; a high-elasticity rubber tube 2 is fastened to the lower hook-shaped screw 102 and further secured with an upper cable tie 204 to ensure the reliability of the elastic reset mechanism connection.

[0030] Figure 3 The diagram shows the connection structure between the pin, the high-elasticity rubber tube, and the fixed base. The fixed base 3 is fixed to the bottom 203 of the lower cylinder by the first radial adjusting bolt 201 and the second radial adjusting bolt 202. The upper end of the high-elasticity rubber tube 2 is connected to the lower hook-shaped screw 102, and the lower end is wrapped around the cross bracket 206 in the central circular hole of the fixed base 3 and secured with the lower cable tie 205. The elastic modulus of the high-elasticity rubber tube 2 is 2-5 MPa, and its tensile range is more than three times its own length. The placement height of the fixed base 3 must ensure that the pin 1 of the high-elasticity rubber tube 2 connected to it does not protrude from the second circular hole of the lower cylinder in its natural state, and that the pin 1 is higher than the first circular hole of the upper cylinder in its maximum tensile state.

[0031] Figure 4 The diagram shows the structure of the upper cylindrical flange 9, which has a wire rope positioning hole 301, a force sensor mounting slot 302, and six circumferentially distributed fixing screws 303. The gap between the upper cylinder 6 and the lower cylinder 7 can be adjusted by the number of gaskets provided on the flange 9.

[0032] Figure 5 The diagram shows the device of the present invention in the connected state of the upper and lower cylinders. In this state, the sliding pin 1 is rigidly connected by pulling and fixing the steel wire rope 5 so that it passes through the circular holes of the upper and lower cylinders simultaneously. At this time, the wave force is transmitted to the sand bed through the entire pile body, and the three-dimensional force sensor 8 measures the total force including the reaction force of the subsoil, while the development of scour pits around the lower cylinder can be observed.

[0033] Figure 6 The diagram shows the device of the present invention in the state of separation of the upper and lower cylinders. In this state, the steel wire rope 5 is in a slack state, and under the traction of the high-elastic rubber tube 2, the sliding pin 1 is located inside the lower cylinder 7, and the upper and lower cylinders are in a separated state. At this time, the waves only act on the upper cylinder 6, and the force on it is directly measured by the three-dimensional force sensor 8 at the top. The obtained data is the pure wave force unaffected by the sand bed.

[0034] Corresponding to the aforementioned embodiment of a device for synchronously and in real-time measuring wave force and pile foundation scour, the present invention also provides a method for synchronously and in real-time measuring wave force and pile foundation scour, the method comprising the following steps: 1) Embed the lower cylinder into the sand pit. After aligning the first hole of the upper cylinder with the second hole of the lower cylinder, fix the force sensor to the top of the upper cylinder in sequence, and fix the upper bracket to the top of the force sensor. 2) Place the fixed base in the appropriate position inside the lower cylinder, connect it to the high-elasticity rubber tube, and then adjust the sliding state of the pin to see if it meets the requirements. If it does, use high-viscosity glue to secure it firmly. 3) After the wire rope is connected to the pin, it passes through the second round hole of the lower cylinder, the first round hole of the upper cylinder, the third round hole on the upper cylinder flange (9), and the fixed pulley in sequence; 4) After installation, before the formal experiment, it is necessary to test the normal working status of each component, such as whether the round holes are aligned and whether the pins can be smoothly slid out and in. 5) Simple wave force measurement mode: The upper and lower cylinders are separated in the slack state of the wire rope, and the simple wave force data under different wave conditions are recorded; 6) Coupling effect measurement mode: By pulling and fixing the steel wire rope to connect the upper and lower cylinders, wave force data including the stress of the bed can be recorded, and the morphological development of the scour pit can be recorded through images.

[0035] This invention achieves rapid switching between connected and separated states of the upper and lower cylinders through the ingenious combination of a sliding pin and a high-elasticity rubber tube. This allows for the simultaneous measurement of wave force and pile scour, and the separation of pure wave force unaffected by substrate stress. The device has a reliable structural design and is remotely controlled via wire ropes and fixed pulleys. Its operation is simple and labor-saving, and it can realistically reproduce the actual working conditions of marine pile foundations under the coupled effects of waves and scour. This provides an effective experimental method for the dynamic response research and safety design of marine engineering pile foundations.

[0036] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A device for synchronously and in real-time measuring wave force and pile foundation scour, characterized in that, The device includes: The upper cylinder (6) has a three-dimensional force sensor (8) fixed at its top and a first circular hole at its bottom; The lower cylinder (7) is used to pre-embed the sand bed of the sand pit (10) in the water inlet trough. The top is provided with a second round hole for matching with the first round hole. A sliding pin (1) is used to pass through the first round hole and the second round hole to realize the detachable connection between the upper cylinder (6) and the lower cylinder (7); The fixed base (3) is fixedly installed inside the lower cylinder (7); A high-elasticity rubber tube (2) is used to connect the fixed chassis (3) and the sliding pin (1) to provide the sliding pin (1) with an automatic reset traction force; The wire rope (5) is connected at one end to the sliding pin (1) for pulling and moving the sliding pin (1), and at the other end passes through the wire rope positioning hole (301) on the flange (9) to achieve manual or mechanical control.

2. The apparatus according to claim 1, characterized in that, The upper cylinder (6) and the lower cylinder (7) have the same diameter. The height of the upper cylinder ensures that the force sensor will not be splashed after water is added to the water tank. The height of the lower cylinder ensures that it is completely buried in the sand bed and that the top protrudes from the surface of the sand bed.

3. The apparatus according to claim 1, characterized in that, The sliding pin (1) is cylindrical, with its bottom located in the second circular hole and its top end tapering inward, which facilitates its upward sliding through the first circular hole under the pull. By pulling the steel wire rope (5) and connecting it to a counterweight outside the water tank, the weight of the counterweight keeps the sliding pin (1) locked. The steel wire rope (5) is tied to the upper hook screw (101), which is screwed into the interior from the upper end of the sliding pin (1) to ensure a tight connection between the steel wire rope (5) and the pin (1). The high-elasticity rubber tube (2) is tied to the lower hook screw (102) and secured with a cable tie, which is screwed into the interior from the lower end of the sliding pin (1) to ensure a tight connection between the high-elasticity rubber tube (5) and the pin (1).

4. The apparatus according to claim 1, characterized in that, The elastic modulus of the high-elasticity rubber tube (2) is 2-5 MPa, and the tensile range is more than 3 times its own length.

5. The apparatus according to claim 4, characterized in that, The upper end of the high-elastic rubber tube (2) is tied to the lower hook screw (102) with an upper cable tie (204), and the lower end is wrapped around the cross bracket (206) in the center hole of the fixed base (3) and tied with a lower cable tie (205).

6. The apparatus according to claim 1, characterized in that, The fixed base (3) is fixed to the bottom of the lower cylinder (7) by the first radial adjusting bolt (201) and the second radial adjusting bolt (202). The placement height of the fixed base (3) needs to ensure that the sliding pin (1) of the high elastic rubber tube (2) connected to it does not protrude from the second round hole of the lower cylinder in the natural state, and that the sliding pin (1) is higher than the first round hole of the upper cylinder in the maximum tension state.

7. The apparatus according to claim 1, characterized in that, The gap between the upper cylinder (6) and the lower cylinder (7) is adjustable, which is achieved by the number of gaskets set on the upper flange (9) of the upper cylinder.

8. The apparatus according to claim 1, characterized in that, The steel wire rope (5) is made of stainless steel, with a diameter of 2-4 mm and a polytetrafluoroethylene coating on its surface.

9. The apparatus according to claim 1, characterized in that, The device also includes a fixed pulley (4) and an upper bracket (11). The fixed pulley (4) is used to guide the steel wire rope (5) to change direction, so that it is easier to move the pin manually or mechanically. The upper bracket (11) is used to connect to the three-dimensional force sensor (8) above the experimental water tank, thereby fixing the upper cylinder.

10. A method for synchronously and in real-time measuring wave force and pile foundation scour based on the device described in any one of claims 1-9, characterized in that, The method includes the following steps: 1) Embed the lower cylinder (7) into the sand pit (10), align the first round hole of the upper cylinder (6) with the second round hole of the lower cylinder (7), and then fix the force sensor (8) to the top of the upper cylinder (6) in sequence. 2) Place the fixed base (3) inside the lower cylinder and connect it to the high elastic rubber tube (2). Then, check whether the sliding state of the sliding pin (1) meets the requirements. If it does, use high viscosity glue to secure it. 3) After the wire rope (5) is connected to the sliding pin (1), it passes through the second round hole of the lower cylinder, the first round hole of the upper cylinder, and the wire rope positioning hole (301) on the upper cylinder flange (9) in sequence; 4) After installation, the normal working status of each component needs to be tested before the formal experiment; 5) Simple wave force measurement mode: The upper and lower cylinders are separated in the slack state of the wire rope (5), and the simple wave force data under different wave conditions are recorded; 6) Coupling effect measurement mode: Pull and fix the steel wire rope (5) to connect the upper and lower cylinders, which can record wave force data including bed stress and record the morphological development of the scour pit through images.

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