Bottom-supported ocean engineering pile foundation local scouring protection device

Abstract

The invention discloses a bottom-supported ocean engineering pile foundation local scouring protection device in the field of ocean engineering pile foundation protection devices, which comprises a sleeve, an annular base and at least one layer of closure retainer, the sleeve is sleeved on a pile foundation and is not physically connected with the pile foundation, the closure retainer comprises an arc arranged on the outer edge and used for deflecting flow, and the annular base is fixedly connected with the closure retainer. And the circular arc is opened towards the top direction of the pile foundation. According to the protection device, scouring of horseshoe vortex water flow to silt around the pile foundation is reduced by arranging the closure protection ring, the outer edge of the closure protection ring is further provided with an arc, and the water flow can be lifted upwards; the device is arranged on the pile foundation in a sleeving mode and adapts to scouring changes of the seabed surface, and the annular base can protect seabed sediments such as silt around the pile foundation from being scoured and transported. The size of each part of the device is calculated and determined according to the local scouring depth of the pile foundation, and CFD numerical simulation is adopted for inspection or optimization, so that a good protection effect on local scouring of the pile foundation is ensured.

Description

Technical Field

[0001] The invention relates to the field of pile foundation protection devices, and in particular to a bottom-seated marine engineering pile foundation local scour protection device. Background Art

[0002] The offshore wind turbine foundation has long been in an ocean environment with the combined effects of wind, waves and currents. The superposition of these factors has led to changes in the flow field around the foundation structure, increased the shear force on the seabed surface around the foundation, and caused scouring of the seabed soil around the foundation. Local scouring of the pile foundation leads to deterioration of the bearing capacity and changes in the natural frequency, posing a safety hazard to the operation of the wind turbine.

[0003] like Figure 7 As shown in Figure 1, the change of the flow field structure around the pile column has an important impact on the local scour of the pile foundation. When the water flows through the pile column, the existence of the structure causes profound changes in the flow field around it, mainly including the diving flow in front of the column, the horseshoe vortex system at the leading edge, the streamline contraction acceleration flow on the pile side, and the shedding of the rear tail vortex.

[0004] At present, offshore wind power pile foundation scour protection generally considers arranging protective measures around the piles, and commonly used ones include riprap, solidified soil, sand blanket, concrete row, etc. By arranging anti-scour materials on the seabed surface, the purpose of directly improving the foundation's anti-scour capacity can be achieved, but there are disadvantages such as difficulty in controlling construction quality and the need for regular maintenance. Therefore, such measures are essentially relatively passive protective measures. In recent years, some people have proposed the use of active protective devices such as pile column slits, column rows, hollow sleeves, and pile foundation wings based on modifying flow field characteristics, reducing vortex tube shedding, and reducing local flow velocity. According to the research of the proposers, this type of active protective device has a certain effect in reducing the depth of scour, but there are also situations such as pile foundation wings that produce more serious scour. There is mostly a lack of quantitative methods for determining the design scale of each component of the device, and it is more empirical or arbitrary.

[0005] In summary, the existing protective devices all have some defects. It is urgent to develop a protective device based on the formation mechanism of local scour of pile foundation, and accurately design the dimensions of each component of the protective device according to actual conditions to improve the protective effect against local scour of pile foundation. Summary of the invention

[0006] The purpose of the present invention is to provide a bottom-mounted marine engineering pile foundation local scour protection device, which uses a circular arc set on the outer periphery of the interception retaining ring to lift the water flow upward to prevent the horseshoe vortex water flow from scouring the seabed surface around the pile foundation downward. The annular base can protect the seabed sediments such as mud and sand around the pile foundation from being scoured and transported, thereby jointly improving the protection effect of the device against local scour of the pile foundation.

[0007] In order to solve the above technical problems, the following technical solutions are adopted:

[0008] The present invention provides a bottom-mounted marine engineering pile foundation local scour protection device, comprising: a sleeve, an annular base and at least one layer of interception retainer, wherein the sleeve is sleeved on the pile foundation and is not physically connected to the pile foundation, and the annular base and the interception retainer are both concentrically mounted on the sleeve;

[0009] The interception retaining ring includes a circular arc arranged on the outer edge for diverting the flow, and the circular arc opens toward the top of the pile foundation;

[0010] The annular base is in contact with the seabed; the interception retaining ring is located above the annular base;

[0011] The number of layers, height and radius of the interception retaining ring are determined according to the local scouring depth of the pile foundation.

[0012] Optionally, the radius of the arc is not less than 2 meters, and the central angle is not less than 45°.

[0013] Optionally, the annular base comprises an annular bottom plate and a lower baffle plate, the annular bottom plate and the lower baffle plate are both concentric ring-shaped and installed together, the annular bottom plate is located above the lower baffle plate, the lower baffle plate is embedded in the seabed, and the annular bottom plate is located on the surface of the seabed;

[0014] The radius of the annular bottom plate and the height of the lower baffle are determined according to the local scouring depth of the pile foundation.

[0015] Optionally, when the interception retaining ring is provided in multiple layers, its diameter decreases successively from the bottom to the top of the pile foundation, and the distance between the interception retaining ring located at the highest layer and the sea level is greater than the draft depth required for construction and maintenance vessels to approach for operation.

[0016] Optionally, a rubber pad is provided between the sleeve and the pile foundation, and the sleeve comprises two semicircular arcs, which are combined by a connector and sleeved on the pile foundation.

[0017] Optionally, the intercepting retainer further includes a supporting member for supporting.

[0018] Optionally, a submarine cable groove for installing a submarine cable is provided on the outer edge of the intercepting retaining ring.

[0019] Optionally, when the local scouring depth S of the pile foundation is less than 5 meters, the interception retaining ring is provided with one layer, and the height h1 between the interception retaining ring and the annular bottom plate satisfies: ;

[0020] When the local scouring depth S of the pile foundation is not less than 5 meters, the interception retaining ring is provided with two layers, and the height h1 between the two layers of the interception retaining ring satisfies: ;

[0021] In the formula, k h It indicates the interval height coefficient of the interception retaining ring;

[0022] The height w of the lower baffle satisfies: ;

[0023] In the formula, k w Indicates the height coefficient of the lower baffle;

[0024] The radius r0 of the annular bottom plate satisfies: ;

[0025] Where, k0 represents the annular bottom plate radius coefficient; R represents the scour pit radius;

[0026] The cut-off retainer i The radius satisfies: ;

[0027] In the formula, k r，i It represents the radius coefficient of the interception retaining ring. When the interception retaining ring is set as one layer, the value range of the radius coefficient of the interception retaining ring is 0.4~0.7; when the interception retaining ring is set as two layers, the value range of the radius coefficient of the interception retaining ring of the lower layer is 0.4~0.7, and the value range of the radius coefficient of the interception retaining ring of the upper layer is 0.3~0.5.

[0028] Optionally, the local scouring depth S of the pile foundation satisfies:

[0029] ;

[0030] Where D is the diameter of the pile foundation; K ξ It represents the foundation scour pier shape coefficient;

[0031] F ra The Froude number represents the pile diameter corresponding to the average velocity of the wave flow;

[0032] U cw It represents the ratio of the tidal velocity to the composite velocity of the wave and current near the bottom layer;

[0033] h represents water depth;

[0034] d 50 represents the median particle size of sediment particles;

[0035] in:

[0036] ;

[0037] ;

[0038] ;

[0039] ;

[0040] Where U a U represents the average velocity of water particles caused by the superposition of waves and currents; w Indicates the maximum velocity of the wave near the bottom water particle trajectory; U c It represents the maximum flow velocity near the bottom layer during the whole tide; H represents the wave height; L represents the average wavelength; T represents the wave period; and g represents the gravitational acceleration.

[0041] Optionally, the scour pit radius R satisfies:

[0042] ;

[0043] Where, β represents the slope angle of the scour pit; D represents the diameter of the pile foundation; It represents the underwater angle of repose of sediment;

[0044] When it is a silty seabed environment, ;

[0045] When it is a sandy seabed environment, ;

[0046] In the formula, represents the underwater angle of repose of sediment, satisfying: ;

[0047] Where, d 50 Represents the median particle size of sediment particles.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] 1. The protective device provided by the present invention reduces the scouring of the mud and sand around the pile foundation by the horseshoe vortex water flow by arranging an intercepting guard ring. A circular arc is also arranged on the outer edge of the intercepting guard ring, which can lift the water flow upward to prevent the horseshoe vortex water flow from scouring the seabed surface around the pile foundation downward. After the pile foundation is installed with the protective device, since the sleeve is not physically connected to the pile foundation, it is gradually embedded in the seabed under the action of effective gravity as the edge of the lower baffle plate of the annular base is scoured. Therefore, the protective device can adapt to the scouring changes of the seabed surface, protect the mud and sand around the pile foundation below the annular base from being scoured and transported, and improve the protective effect against local scouring of the pile foundation.

[0050] 2. The component sizes of the protective device provided by the present invention are calculated based on the hydrological and sediment conditions of the engineering sea area and the pile foundation parameters, which can further improve the protection efficiency.

[0051] 3. When calculating the components of the protective device, the present invention uses the anti-scour effect of the CFD numerical simulation device, which is installed after inspection or optimization. The protective device used in each pile foundation is accurately designed according to the environment in which the pile foundation itself is located, and has a higher protective effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of a protective device provided with a layer of interception retaining ring in an embodiment of the present invention;

[0053] Figure 2 Schematic diagram of a protective device with two layers of interception guard rings in an embodiment of the present invention;

[0054] Figure 3 1 is a schematic diagram of a top view of the structure of a protective device provided with a layer of interception retaining ring in an embodiment of the present invention;

[0055] Figure 4 It is a schematic side view of the structure of a protective device provided with a layer of interception retaining ring in an embodiment of the present invention;

[0056] Figure 5 1 is a schematic diagram of a top view of the structure of a protective device provided with two layers of interception retaining rings in an embodiment of the present invention;

[0057] Figure 6 is a schematic side view of the structure of a protective device provided with two layers of interception retaining rings in an embodiment of the present invention;

[0058] Figure 7 It is a schematic diagram of the flow field structure around the pile foundation of the present invention;

[0059] Figure 8 is the overall grid layout diagram of the CFD numerical water tank in the embodiment of the present invention;

[0060] Fig. 9 It is a streamline diagram of pile A in the embodiment of the present invention;

[0061] Fig.10 is a flow velocity vector diagram of pile A in the embodiment of the present invention;

[0062] Fig.11 is the scour contour map around the pile of Project A in the embodiment of the present invention;

[0063] Fig.12 It is a streamline diagram around the pile after the protective device is installed in item A in the embodiment of the present invention;

[0064] Fig.13 is a flow velocity vector diagram around the pile after the protective device is installed in Project A in the embodiment of the present invention;

[0065] Fig.14 is a depth contour map of the scour around the pile after the protective device is installed in Project A in the embodiment of the present invention;

[0066] Fig.15 : is a streamline diagram of piles around project B in an embodiment of the present invention;

[0067] Fig.16is a flow velocity vector diagram of pile circumference of project B in an embodiment of the present invention;

[0068] Fig.17 is the depth contour map of the scour around the pile of Project B in the embodiment of the present invention;

[0069] Fig.18 This is a streamline diagram around the pile after the protective device is installed in item B of the embodiment of the present invention;

[0070] Fig.19 is a vector diagram of flow velocity around the pile after the protective device is installed in item B in the embodiment of the present invention;

[0071] Fig. 20 This is a depth contour map of scour around piles after the protective device is installed in Project B in the embodiment of the present invention.

[0072] Description of reference numerals:

[0073] 1. Annular bottom plate; 2. Lower baffle plate; 3. Flow interception retaining ring; 3-1. Upper flow interception retaining ring; 3-2. Lower flow interception retaining ring; 4. Sleeve; 5. Support member; 6. Connector; 7. Cable trough; 8. Vertical branch line; 9. Rubber pad; 10. Pile foundation. DETAILED DESCRIPTION

[0074] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use.

[0075] Example 1

[0076] like Figure 1 As shown, this embodiment provides a bottom-mounted marine engineering pile foundation local scour protection device, including: a sleeve 4, an annular base and at least one layer of interception retainer 3, the sleeve 4 is sleeved on the pile foundation 10 and is not physically connected to the pile foundation 10, and the annular base and the interception retainer 3 are both concentrically mounted on the sleeve 4;

[0077] The annular base is in contact with the seabed; the interception retaining ring 3 is located above the annular base;

[0078] The number of layers, height and radius of the interception retaining ring 3 are determined according to the local scouring depth of the pile foundation 10;

[0079] The outer edge of the intercepting retaining ring 3 is provided with an arc for diverting the flow, and the arc opens toward the top of the pile foundation 10 .

[0080] The arc opening toward the top of the pile foundation 10 can guide the water flowing toward the pile foundation 10 upward, and prevent the horseshoe vortex water flow from scouring the seabed surface around the pile foundation 10 downward. The interception retainer 3 and the annular base are installed by providing the sleeve 4, and the interception retainer 3 and the annular base do not contact the pile foundation 10, thereby avoiding damage to the pile foundation 10.

[0081] The height of the sleeve 4 is adapted to the cut-off retainer 3 installed thereon.

[0082] The number of layers, height and radius of the interception retaining ring 3 are determined according to the local scour depth of the pile foundation 10. According to the pile foundation 10 installed in different positions, the pile foundation 10 is subjected to different scour environments. The public patent with patent number "2020108313620" discloses a method for determining the local scour depth of the seabed foundation based on the design flow velocity of the ocean current. The scour depth of the pile foundation 10 is determined according to this method.

[0083] The greater the scouring depth of the pile foundation 10 , the more layers of interception retaining rings 3 are provided.

[0084] The height of the interception retaining ring 3 is determined by the calculated scouring depth of the pile foundation 10 and the correlation coefficient in combination with the material used in the device and the processing precision design, and the height is calculated by multiplying the scouring depth and the correlation coefficient.

[0085] The radius of the interception retaining ring 3 is smaller than the radius of the annular base. The radius of the annular base is first calculated by combining the scouring depth of the pile foundation 10 with the hydrological and sediment conditions of the engineering sea area, and then the radius of the interception retaining ring 3 is calculated based on the radius of the annular base combined with the coefficient of the interception retaining ring 3.

[0086] Taking into account the influencing factors of the device itself and the environmental conditions in which it is located, the influencing factors are converted into correlation coefficients and combined with the scouring depth to accurately determine the relevant dimensions of the device, thereby improving the protection effect against local scouring of the pile foundation.

[0087] During installation, hanging points are arranged on the sleeve 4, the annular base and the interception retaining ring 3 to facilitate hanging and installation.

[0088] Example 2

[0089] This embodiment provides a bottom-mounted marine engineering pile foundation local scour protection device based on the first embodiment, the difference is that:

[0090] like Figure 1 As shown, the radius of the arc is not less than 2 meters, and the central angle is not less than 45°. When the radius of the interception retaining ring 3 is determined according to the local scouring depth of the pile foundation 10, the calculated radius includes the width of the arc. A U-shaped submarine cable trough 7 for installing a submarine cable is provided on the arc, and the submarine cable trough 7 extends inward for a certain distance.

[0091] The annular base includes an annular bottom plate 1 and a lower baffle plate 2. The annular bottom plate 1 and the lower baffle plate 2 are both concentric ring-shaped, and the two are installed together. The installation method can be bolt connection, welding or riveting, and the material is selected from materials with high corrosion resistance. The annular bottom plate 1 is located above the lower baffle plate 2, the lower baffle plate 2 is embedded in the seabed, and the annular bottom plate 1 is located on the surface of the seabed. The diameter of the annular bottom plate 1 is greater than the diameter of the lower baffle plate 2, and the thickness of the lower baffle plate 2 is greater than the thickness of the annular bottom plate 1. After the pile foundation is installed with the protective device, since the sleeve is not physically connected to the pile foundation 10, as the edge of the lower baffle plate 2 of the annular base is scoured, it is gradually embedded in the seabed under the action of effective gravity, so the protective device can adapt to the scouring changes of the seabed surface. And the diameter of the annular bottom plate 1 is greater than the diameter of the lower baffle plate 2, which can reduce the scouring of the edge of the lower baffle plate 2. The lower baffle plate 2 is embedded in the seabed, stabilizes the mud and sand around the pile foundation 10, and reduces the scope of the scouring pit around the pile foundation 10. Together, the pile foundation 10 is protected from being washed away and transported, thereby protecting the pile foundation 10 from being damaged.

[0092] The height of the lower baffle 2 is determined by the local scouring depth of the pile foundation 10 and the relative influencing factors, and the radius of the annular bottom plate 1 is determined according to the local scouring depth of the pile foundation 10 and the hydrological and sediment conditions of the engineering sea area. The height of the lower baffle 2 and the radius of the annular bottom plate 1 are determined according to the pile foundation 10 installed at different positions and the scouring depth of the pile foundation 10 at the position, and protective devices of different sizes are designed according to the local scouring depth of the pile foundation 10 to improve the protective effect against local scouring of the pile foundation.

[0093] The annular bottom plate 1 and the lower baffle plate 2 are both circular rings composed of two semicircular structures. The connection between the two semicircular structures can be bolted, welded or riveted to form a radial vertical dividing line 8 at the connection. The connecting piece 6 and the submarine cable groove 7 on the sleeve 4 are aligned with the vertical dividing line 8 to facilitate circumferential positioning during installation and disassembly.

[0094] A rubber pad 9 is provided between the sleeve 4 and the pile foundation 10, and the sleeve 4 does not directly contact the pile foundation 10, so as to prevent the sleeve 4 and the structure thereon from damaging the pile foundation 10. The sleeve 4 is composed of two semicircular arc structures, which are connected by a connector 6, and the connector 6 includes a connecting plate and a bolt assembly, and the connecting plates are respectively welded to the two side ends of the semicircular arc, and the connecting plates between the two semicircular arcs are installed by a bolt assembly, and the sleeve 4 is installed on the pile foundation 10, so as to facilitate the loading and unloading of the sleeve 4.

[0095] The interception retainer 3 also includes a support member 5 for support, the support member 5 is made of a material with high corrosion resistance, the support member 5 is cylindrical, the lower end of the support member 5 on the lower interception retainer 3 is installed on the upper surface of the annular bottom plate 1, the end surface of the upper end is located on the lower surface of the interception retainer 3, and the support member 5 is close to the arc of the outer edge of the interception retainer 3. The installation of the support member 5 can be selected by bolt connection, welding or riveting.

[0096] like Figure 1 , Figure 3 , Figure 4 As shown, a layer of interception retainer 3 is provided, and the support members 5 at the bottom of the interception retainer 3 are evenly arranged in the circumferential direction, and the other end of the support member 5 is connected to the annular bottom plate 1, and the connecting member 6, the cable trough 7, and the vertical dividing line 8 on the device are aligned. During installation, the annular bottom plate 1 and the lower baffle plate 2 are assembled together and hoisted for installation, the interception retainer 3 and the support member 5 thereon are assembled and installed, and the sleeve 4 and the rubber pad 9 are assembled and installed. When the support member 5 and the annular bottom plate 1 are installed, bolt connection or riveting can be selected.

[0097] like Figure 2 , Figure 5 , Figure 6 As shown, two layers of interception retaining rings 3 are provided, namely, an upper interception retaining ring 3-1 and a lower interception retaining ring 3-2. The diameter of the upper interception retaining ring 3-1 is smaller than the diameter of the lower interception retaining ring 3-2. The outer edges of the upper interception retaining ring 3-1 and the lower interception retaining ring 3-2 are both provided with arcs, through which the water flow is gradually guided upward, reducing the scouring around the pile foundation 10. The lower interception retaining ring 3-2 is provided with a circumferential support member 5 to meet the support of the interception retaining ring and the upper interception retaining ring 3-1.

[0098] The bottom-supported marine engineering pile foundation local scour protection device provided in this embodiment determines the size of each component in the protection device, specifically:

[0099] When the local scouring depth S of the pile foundation is less than 5 meters, the interception retaining ring is provided with one layer, and the height h1 between the interception retaining ring and the annular bottom plate satisfies: ;

[0100] When the local scouring depth S of the pile foundation is not less than 5 meters, the interception retaining ring is provided with two layers, and the height h1 between the two layers of the interception retaining ring satisfies: ;

[0101] In the formula, k h Indicates the interception retaining ring interval height coefficient; the value range is 0.4~0.6;

[0102] The height w of the lower baffle satisfies: ;

[0103] In the formula, k w Indicates the height coefficient of the lower baffle; the value range is 0.3~0.5.

[0104] The radius r0 of the annular bottom plate satisfies: ;

[0105] Where k0 represents the annular bottom plate radius coefficient; the value range is 0.8~1.0; R represents the scour pit radius.

[0106] The cut-off retainer i The radius satisfies: ;

[0107] In the formula, k r，i It represents the radius coefficient of the interception retaining ring. When the interception retaining ring is set as one layer, the value range of the radius coefficient of the interception retaining ring is 0.4~0.7; when the interception retaining ring is set as two layers, the value range of the radius coefficient of the interception retaining ring of the lower layer is 0.4~0.7, and the value range of the radius coefficient of the interception retaining ring of the upper layer is 0.3~0.5.

[0108] The local scouring depth S of the pile foundation satisfies:

[0109] ;

[0110] Where D is the diameter of the pile foundation; K ξ It represents the foundation scour pier shape coefficient, which is dimensionless;

[0111] F ra The Froude number represents the pile diameter corresponding to the average velocity of the wave flow, which is dimensionless;

[0112] U cw It represents the ratio of the tidal velocity to the composite velocity of the wave and current near the bottom layer, and is dimensionless;

[0113] h represents water depth, in m;

[0114] d 50 Indicates the median particle size of sediment particles, in mm;

[0115] in:

[0116] ;

[0117] ;

[0118] ;

[0119] ;

[0120] Where U a It represents the average velocity of water particles caused by the superposition of waves and currents, in m / s; U w Indicates the maximum velocity of the wave near the bottom water particle trajectory, unit is m / s; U cIt indicates the maximum flow velocity near the bottom layer during the whole tide, in m / s; H indicates the wave height, in m; L indicates the average wavelength, in m; T indicates the wave period, in s; g indicates the gravitational acceleration, in m / s 2 ;

[0121] When determining the radius of the annular bottom plate 1, the scour pit radius R (including the pile foundation radius) satisfies:

[0122] ;

[0123] Where, β represents the slope angle of the scour pit, unit: °;

[0124] When the calculated pile foundation is installed in a silty seabed environment, the scour pit slope angle β satisfies:

[0125] ;

[0126] When the calculated pile foundation is installed in a sandy seabed environment, the scour pit slope angle β satisfies:

[0127] ;

[0128] In the formula, represents the underwater angle of repose of sediment, satisfying: .

[0129] Example 3

[0130] In combination with Example 2, the dimensions of the protective device are determined. In this example, the protective device with dimensions determined by Example 2 is installed in offshore wind farm projects A and B for comparison with the protective device without the device installed. Specifically:

[0131] Offshore wind farm projects A and B are planned to install scour protection devices within 7 days after the completion of pile sinking of pile foundation 10. The design wave elements of 5-year return period (i.e., return period of 5 years) under the design high water level of the two projects, the possible maximum flow velocity near the bottom layer of full tide, the average particle size of seabed sediment, and the pile diameter are listed in Table 1.

[0132] Table 1 Design parameters related to Project A and Project B

[0133]

[0134] According to the relevant parameters in Table 1, the determination method disclosed in the specific implementation method of the patent named "Method and system for determining the local scour depth of seabed foundation based on the design flow velocity of ocean current" with patent number "202010831362.0" is used to calculate the composite flow velocity of the layered ocean current vectors in Project A and Project B to obtain the following Table 2.

[0135] Table 2 Composite velocity of stratified current vectors for Project A and Project B

[0136]

[0137] The calculation formula for calculating the local scour depth S of the pile foundation and the radius R of the scour pit is used to obtain the following Table 3.

[0138] Table 3 Calculation results of local scour depth and radius of pile foundation of Project A and Project B

[0139]

[0140] According to the local scour depth S of the pile foundation 10 and the scour pit radius R calculated in Table 3, the structural dimensions of each device are calculated.

[0141] As for the protective device required in Project A, it can be seen from Table 3 that the local scouring depth S of the pile foundation 10 in Project A is 4.4 meters, the local scouring depth of the pile foundation 10 is less than 5, and a layer of interception retaining ring 3 is set; the radius of the scouring pit is 18.0 meters. According to the formula in Example 2, it is calculated that:

[0142] The height of the interception retaining ring 3, that is, the distance between the interception retaining ring 3 and the annular bottom plate 1: rice;

[0143] Lower baffle 2 height: rice;

[0144] Radius of ring base 1: m, including pile foundation 10, radius 4.25 m;

[0145] Radius of cut-off retainer 3: m, including pile foundation 10, radius 4.25 m;

[0146] The outer edge of the interception guard ring 3 is provided with an arc opening upward, the arc having a radius of 2 meters and a central angle of 45°. The radius of the interception guard ring 3 calculated above includes the width of the arc.

[0147] The water depth in the sea area of ​​Project A is 15.0 meters. After deducting the 32.2-meter interception retaining ring and the height occupied by the thickness of other structures of the device, the remaining height is 12.4 meters, which meets the draft depth requirements for construction and operation and maintenance vessels to approach for operations.

[0148] As for the protective devices required in Project B, it can be seen from Table 3 that the local scouring depth S of the pile foundation 10 in Project B is 7.4 meters, the local scouring depth of the pile foundation 10 is greater than 5 meters, and two layers of interception retaining rings are set; the radius of the scouring pit is 21.3 meters. According to the formula in Example 2, it is calculated that:

[0149] The heights between the interception retaining ring 3 and the annular bottom plate and the two layers of interception retaining rings 3 are: rice;

[0150] Lower baffle 2 height: rice;

[0151] Radius of ring base 1: m; including pile foundation 10 radius 4.75 m;

[0152] Lower interception retaining ring 3-2 radius: m, including pile foundation 10, radius 4.75 m;

[0153] Upper interception retaining ring 3-1 radius: m, including pile foundation 10, radius 4.75 m

[0154] The outer edges of the upper interception retaining ring 3-1 and the lower interception retaining ring 3-2 are both provided with an arc opening upward, the radius of the arc is 2.0 meters, and the central angle is 45 degrees. The radius of each interception retaining ring calculated above includes the width of the arc.

[0155] The water depth in the sea area of ​​Project B is 26.8 meters. After deducting the total height of the two-layer interception retaining ring of 7.4 meters and the height occupied by the thickness of other structures of the device, the remaining height is 19.3 meters, which meets the draft depth requirements for construction and operation and maintenance vessels to approach operations.

[0156] For offshore wind farm projects A and B, numerical simulation calculations were performed using computational fluid dynamics (CFD) software before and after the installation of the scour protection device to verify the protective effect of the scour protection device. Specifically:

[0157] like Figure 8 As shown in the figure, a CFD (computational fluid dynamics) numerical flume is established, with the inlet as the velocity boundary and the water depth specified; the bottom as the wall boundary; the top as the pressure boundary, with the fluid volume fraction set to 0; the two sides as symmetric boundaries; the outlet as the outflow boundary, and a damping layer set at the rear to eliminate the problem of fluid volume reduction in the calculation domain. Baffles are set on both sides of the sediment layer to prevent the sediment from being taken away from the calculation domain.

[0158] The overall grid layout is as follows Fig. 9As shown in the figure, a cylinder is used to simulate the pile foundation, and the numerical simulation range is set to 10D1 upstream of the cylinder, 5D1 on both sides, and 15D1 downstream of the cylinder, where D1 is the diameter of the cylinder. When studying the scouring problem, interpolation problems will occur at the junction of grids of different sizes, resulting in the overall scouring of the sediment here, so a gradient grid is selected. A D1 / 16-sized grid is used within the range of 2.5D1 around the cylinder; due to the overall scouring problem at the soft and hard junction of the sediment and the baffle, a D1 / 20-sized grid is set within the range of D1 / 8 before and after the two junctions; the grid size in the gravity direction is uniformly set to D1 / 16; the grid number of the grids in the remaining positions is specified to achieve a gradient effect, with a total grid size of 1.45 million. In order to reduce the impact of the soft and hard junction on local scouring, and the problem that scouring mainly occurs on the front side of the pile, a 9.5D1 sediment layer is arranged in front of the pile, and a 5D1 sediment layer is arranged behind the pile.

[0159] like Fig. 9 , Fig.10 , Fig.11 As shown, Project A was simulated using the above computational fluid dynamics (CFD) software, and the scour protection device was not added in this state, and the pile streamline diagram, velocity vector distribution diagram and local scour contour diagram after scour balance were obtained.

[0160] like Fig.12 , Fig.13 , Fig.14 As shown, Fig.14 The Chinese and English annotations are the changes in the net height of seabed sediments. Project A is simulated using the above-mentioned computational fluid dynamics (CFD) software, and the state is that the scour protection device in the above-mentioned embodiment is installed to obtain the pile streamline map, flow velocity vector distribution map and local scour contour map after scour balance.

[0161] From the comparison of the streamline diagram around piles, velocity vector distribution diagram and local scour diagram before and after the installation of the scour protection device in Project A obtained above, it can be concluded that after the installation of the scour protection device, the scour depth reduction rate within the original scour range is 100%, and the scour depth reduction rate at the outer edge of the lower baffle away from the pile foundation is 68.2%.

[0162] like Fig.15 , Fig.16 , Fig.17 As shown, Project B was simulated using the above computational fluid dynamics (CFD) software, and the scour protection device was not added in this state, and the pile streamline diagram, velocity vector distribution diagram and local scour contour diagram after scour balance were obtained.

[0163] like Fig.18 , Fig.19 , Fig. 20 As shown, Fig. 20The Chinese and English annotations are the changes in the net height of seabed sediments. Project B is simulated using the above-mentioned computational fluid dynamics (CFD) software, and the state is that the scour protection device in the above-mentioned embodiment is installed to obtain the pile streamline diagram, velocity vector distribution diagram and local scour contour diagram after scour balance.

[0164] From the comparison of the streamline diagram around piles, velocity vector distribution diagram and local scour diagram before and after the installation of the scour protection device in Project B obtained above, it can be concluded that after the installation of the scour protection device, the scour depth reduction rate within the original scour range is 100%, and the scour depth reduction rate at the outer edge of the lower baffle away from the pile foundation is 73.0%.

[0165] For pile foundations of marine projects under construction, the scour protection device using this embodiment needs to be installed within 7 to 15 days after the pile is sunk. For pile foundations of existing marine projects, the scour pit needs to be filled to the same level as the surrounding seabed before installing this protection device.

[0166] The protective device is designed based on the actual conditions of the marine engineering sea area. It can calculate the local scour of the pile foundation based on the hydrological and sediment conditions of the engineering sea area and the pile foundation parameters, and generalize the design into one or more types of protective devices, which are adaptive to specific marine engineering. It can carry out precise protection based on the specific parameters of the actual situation and improve the protection effect of local scour of the pile foundation.

[0167] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which 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 cannot be understood as a limitation on the present invention. In the description of the present invention, unless otherwise specified, "multiple" means two or more. 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0168] 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 technical 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 local scour protection device for bottom-seated marine engineering pile foundation, characterized in that: include: A sleeve, an annular base and at least one layer of interception retainer, wherein the sleeve is sleeved on the pile foundation and is not physically connected to the pile foundation, and the annular base and the interception retainer are both concentrically mounted on the sleeve; The interception retaining ring includes a circular arc arranged on the outer edge for diverting the flow, and the circular arc opens toward the top of the pile foundation; The annular base is in contact with the seabed; the interception retaining ring is located above the annular base; The number of layers, height and radius of the interception retaining ring are determined according to the local scouring depth of the pile foundation.

2. The local scour protection device for bottom-supported marine engineering pile foundation according to claim 1 is characterized in that: The radius of the arc is not less than 2 meters, and the central angle is not less than 45°.

3. The local scour protection device for bottom-supported marine engineering pile foundation according to claim 1 is characterized in that: The annular base includes an annular bottom plate and a lower baffle plate, the annular bottom plate and the lower baffle plate are both concentric ring-shaped and installed together, the annular bottom plate is located above the lower baffle plate, the lower baffle plate is embedded in the seabed, and the annular bottom plate is located on the surface of the seabed; The radius of the annular bottom plate and the height of the lower baffle are determined according to the local scouring depth of the pile foundation.

4. The bottom-supported marine engineering pile foundation local scour protection device according to claim 1 is characterized in that: When the interception retaining ring is provided in multiple layers, its diameter decreases successively from the bottom to the top of the pile foundation, and the distance between the interception retaining ring located at the highest layer and the sea level is greater than the draft depth required for construction and operation vessels to approach for operation.

5. The bottom-supported marine engineering pile foundation local scour protection device according to claim 1 is characterized in that: A rubber pad is provided between the sleeve and the pile foundation. The sleeve comprises two semicircular arcs, which are combined by a connecting piece and sleeved on the pile foundation.

6. The bottom-supported marine engineering pile foundation local scour protection device according to claim 1 is characterized in that: The cut-off retainer further comprises a support member for supporting.

7. The local scour protection device for bottom-supported marine engineering pile foundation according to claim 1 is characterized in that: A submarine cable groove for installing a submarine cable is provided on the outer edge of the interception retaining ring.

8. The local scour protection device for bottom-supported marine engineering pile foundation according to claim 3 is characterized in that: When the local scouring depth S of the pile foundation is less than 5 meters, the interception retaining ring is provided with one layer, and the height h1 between the interception retaining ring and the annular bottom plate satisfies: ; When the local scouring depth S of the pile foundation is not less than 5 meters, the interception retaining ring is provided with two layers, and the height h1 between the two layers of the interception retaining ring satisfies: ; In the formula, k h It indicates the interval height coefficient of the interception retaining ring; The height w of the lower baffle satisfies: ; In the formula, k w Indicates the height coefficient of the lower baffle; The radius r0 of the annular bottom plate satisfies: ; Where, k0 represents the annular bottom plate radius coefficient; R represents the scour pit radius; The cut-off retainer i The radius satisfies: ; In the formula, k r，i It represents the radius coefficient of the interception retaining ring. When the interception retaining ring is set as one layer, the value range of the radius coefficient of the interception retaining ring is 0.4~0.7; when the interception retaining ring is set as two layers, the value range of the radius coefficient of the interception retaining ring of the lower layer is 0.4~0.7, and the value range of the radius coefficient of the interception retaining ring of the upper layer is 0.3~0.

5.

9. The local scour protection device for bottom-supported marine engineering pile foundation according to claim 8 is characterized in that: The local scouring depth S of the pile foundation satisfies: ； Where D is the diameter of the pile foundation; K ξ It represents the foundation scour pier shape coefficient; F ra The Froude number represents the pile diameter corresponding to the average velocity of the wave flow; U cw It represents the ratio of the tidal velocity to the composite velocity of the wave and current near the bottom layer; h represents water depth; d 50 represents the median particle size of sediment particles; in: ； ； ； ； Where U a U represents the average velocity of water particles caused by the superposition of waves and currents; w Indicates the maximum velocity of the wave near the bottom water particle trajectory; U c It represents the maximum flow velocity near the bottom layer during the whole tide; H represents the wave height; L represents the average wavelength; T represents the wave period; and g represents the gravitational acceleration.

10. The local scour protection device for bottom-supported marine engineering pile foundation according to claim 8 is characterized in that: The scour pit radius R satisfies: ； Where, β represents the slope angle of the scour pit; D represents the diameter of the pile foundation; When it is a silty seabed environment, ; When it is a sandy seabed environment, ; In the formula, represents the underwater angle of repose of sediment, satisfying: ; Where, d 50 Represents the median particle size of sediment particles.

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