A large diameter steel pipe pile for offshore wind power

Abstract

The present invention discloses a large-diameter steel pipe pile for offshore wind power generation, comprising a steel pipe pile body and a lifting lug; the steel pipe pile body is formed by butt-welding a plurality of steel pipe pile sections; the lifting lug is fixed on the outer wall surface of the upper part of the steel pipe pile body; a plurality of vent holes are evenly distributed along the pile peripheral wall surface in the middle of the second section of the steel pipe pile section below the pile top of the steel pipe pile body, and the plurality of vent holes are staggered with the auxiliary components on the steel pipe pile body. The large-diameter steel pipe pile for offshore wind power generation of the present invention can timely discharge the gas in the pile by opening the vent holes, can effectively reduce the top impact force of the compressed gas in the pile on the hydraulic hammer, eliminate the separation of the hydraulic hammer and the steel pipe pile when the pile is "slipping", and avoid damage to large construction ships and large hydraulic hammers.

Description

Technical Field

[0001] The invention relates to a large-diameter steel pipe pile for offshore wind power generation. Background Art

[0002] In recent years, offshore wind power has developed rapidly, and the single pile foundation is currently the most widely used foundation form. With the large-scale offshore wind turbines, the diameter of the single pile foundation is getting larger and larger, the weight is getting larger and larger, and the construction difficulty of the single pile foundation is also increasing. The underwater geological conditions of offshore wind power construction are complex. There are soft soil interlayers in some sea areas, the foundation soil is seriously liquefied, and the risk of "pile slippage" of large-diameter steel pipe piles is high. According to the statistics of pile sinking construction in offshore wind farms in recent years, the phenomenon of "pile slippage" of large-diameter steel pipe piles in the offshore waters of Jiangsu is relatively frequent, and there is a phenomenon of "pile slippage" for a long distance of up to 40m. Large-diameter single pile sinking in offshore wind farms usually adopts a large crane ship hanging large hydraulic hammer pile sinking construction technology. On the one hand, the "pile slippage" phenomenon may cause the single pile foundation to tilt, and the verticality of the pile body exceeds the design requirement of 3‰, causing quality problems; on the other hand, if preventive measures are not taken in advance during the "pile slippage" process, it is very likely to cause damage to the crane ship and hydraulic hammer, and even more serious casualties, which is extremely harmful. Through factor analysis, it was determined that during the "pile sliding" process, the gas in the pile was compressed rapidly in a short period of time, which lifted the hydraulic hammer, causing the pile and hammer to separate, which was the main factor that could cause the dangerous situation.

[0003] At present, large diameter steel pipe piles for offshore wind power generally adopt single pile foundation without transition section1 (see Figure 1 ), the steel pipe pile body 11 includes a plurality of steel pipe pile sections 110, each section 110 is rolled separately, butt-welded to form the pile body 11, and then the lugs 12 and other components are welded to the pile body 11. The pile body of the traditional steel pipe pile is complete without openings, and the main construction process is: single pile production and marine transportation; single pile sinking; water absorption and lime spreading in the pile; installation of integrated auxiliary components; anti-scouring construction.

[0004] Traditional large-diameter steel pipe piles for offshore wind power have the following disadvantages:

[0005] 1) In the case of "pile slipping" during steel pipe pile sinking, the gas in the pile will be compressed sharply in a short period of time, which will lift the hydraulic hammer and separate the steel pipe pile from the hydraulic hammer, which may cause damage to large ship machinery and equipment;

[0006] 2) After the steel pipe pile is sunk, a closed environment will be formed. The toxic and harmful gases produced by the decay of the marine organisms in the pile are not connected to the atmosphere, which may cause damage to the equipment in the fan and the operators entering the fan;

[0007] 3) After the steel pipe piles are sunk, the construction process of absorbing water and spreading lime is also required. Summary of the invention

[0008] The purpose of the present invention is to overcome the defects of the prior art and provide a large-diameter steel pipe pile for offshore wind power, which can discharge the gas in the pile in time, effectively reduce the impact force of the compressed gas in the pile on the hydraulic hammer, and solve the problem that the hydraulic hammer may detach from the steel pipe pile and cause damage to large ship machinery and equipment.

[0009] The object of the present invention is achieved as follows: an offshore wind power large-diameter steel pipe pile comprises a steel pipe pile body and a lifting lug; the steel pipe pile body is formed by butt welding of multiple sections of steel pipe pile pipe sections; the lifting lug is fixed on the outer wall surface of the upper half of the steel pipe pile body, wherein:

[0010] A plurality of ventilation holes are evenly arranged along the pile peripheral wall surface in the middle of the second steel pipe pile section below the pile top of the steel pipe pile body, and the plurality of ventilation holes are staggered with the auxiliary components on the steel pipe pile body.

[0011] In the above-mentioned offshore wind power large-diameter steel pipe pile, the ventilation hole is elliptical, and the long diameter a of the ventilation hole is parallel to the central axis of the steel pipe pile body, and the short diameter b of the ventilation hole is perpendicular to the central axis of the steel pipe pile body.

[0012] In the above-mentioned offshore wind power large-diameter steel pipe pile, the long diameter a and the short diameter b of the vent hole are calculated according to the following steps:

[0013] Step 1: Calculate the gas pressure P in the pile when the hydraulic hammer can just be lifted up when the steel pipe pile slips during pile sinking without opening the vent hole.

[0014] According to the pressure calculation formula:

[0015]

[0016] In formula (1), P is pressure, unit: Pa; F is pressure, unit: N; S is the force area, that is, the cross-sectional area S1 of the steel pipe pile, unit: m 2 ;

[0017] At this time, the pressure F is equal to the weight of the pile hammer, that is:

[0018] F=M×g (2)

[0019] In formula (2): M is the weight of the hydraulic hammer, unit: kg; g is the acceleration due to gravity, which is 9.8 N / kg;

[0020] Therefore, formula (1) becomes:

[0021]

[0022] Step 2: Calculate the pile height h2 of the steel pipe pile

[0023] According to Boyle's law, at a constant temperature and a constant quantity, the volume of an ideal gas is inversely proportional to the pressure of the gas. The calculation formula is:

[0024] P1×V1=P2×V2 (4)

[0025] In formula (4): P1 is the atmospheric pressure, usually 1 standard atmospheric pressure = 0.1 MPa = 1.01 × 105 N / m 2 ; V1 is the volume of the gas in the pile when it is not compressed, unit: m 3 ; P2 is the pressure of the gas in the pile after compression, P2 = P, unit: Pa; V2 is the volume of the gas in the pile after compression, unit: m 3 ;

[0026] Substituting into formula (4) we get:

[0027] P1×S1×(L-h1)=P2×S1(L-h1-h2) (5)

[0028] In formula (5), L is the total length of the steel pipe pile, unit: m; h1 is the water entry height of the steel pipe pile, unit: m; h2 is the sliding height of the steel pipe pile, unit: m;

[0029] Through formula (5), we can get:

[0030]

[0031] Step 3: Calculate the air velocity V under P2 state, unit: m / s

[0032] According to Bernoulli's principle, during the gas flow process, Bernoulli's equation can be simplified to:

[0033] P2=0.5ρV 2 (7)

[0034] In formula (7): ρ is the air density, which is 1.29 kg / m 3 ;

[0035] From formula (7), we can get:

[0036]

[0037] Step 4: Calculate the area S2 of each vent hole opened on the steel pipe pile

[0038] According to the principle that the volume of gas discharged from A vents is equal to the volume of gas compressed, we can get:

[0039] S1×h2=A×S2×V×t (9)

[0040] From formula (9), we can get:

[0041]

[0042] Substituting h2 calculated by formula (6) and V calculated by formula (8) into formula (10), we can obtain:

[0043]

[0044] In formula (11): t is the sliding time of the steel pipe pile, which is 30s;

[0045] Step 5: According to the calculated area S2 of the vent hole, set the long diameter a and short diameter b of the vent hole.

[0046] From the area calculation formula of the conventional elliptical vent: Set the major diameter a and minor diameter b in.

[0047] The offshore wind power large-diameter steel pipe pile of the present invention has the following characteristics:

[0048] 1) To solve the problem of "pile slippage" in large-diameter steel pipe piles for offshore wind power, which may cause damage to large ships and equipment. By timely discharging the gas in the pile, the impact force of the compressed gas in the pile on the hydraulic hammer can be effectively reduced;

[0049] 2) Solve the problem that after the construction of traditional steel pipe piles, a closed environment is formed, and the toxic and harmful gases produced by the decay of marine organisms in the piles are not connected to the atmosphere, avoiding the risk management of closed spaces;

[0050] 3) It reduces the construction process of absorbing water and spreading lime inside the pile after the pile is sunk, which can shorten the construction time of a single pile and reduce the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the structure of a traditional large-diameter steel pipe pile for offshore wind power;

[0052] Figure 2 It is a structural schematic diagram of the offshore wind power large-diameter steel pipe pile of the present invention;

[0053] Figure 3 It is a structural schematic diagram of the second section of the steel pipe pile pipe section in the offshore wind power large-diameter steel pipe pile of the present invention;

[0054] Figure 4 It is a schematic diagram of the relative positions of two vent holes provided on the second section of the steel pipe pile pipe section in the offshore wind power large diameter steel pipe pile of the present invention;

[0055] FIG5 is a schematic diagram of parameters on a steel pipe pile when calculating the size of a vent hole;

[0056] Figure 6It is a schematic diagram of exhausting air from the vent holes of the offshore wind power large-diameter steel pipe piles of the present invention when the piles are sunk. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with the accompanying drawings.

[0058] See also Figure 1 As shown in FIG5 , the offshore wind power large-diameter steel pipe pile of the present invention comprises a steel pipe pile body 11 and a lifting lug 12; wherein the steel pipe pile body 11 is formed by butt welding of several sections of steel pipe pile sections 110;

[0059] The lifting lug 12 is fixed on the outer wall surface of the upper part of the steel pipe pile body 11;

[0060] A plurality of ventilation holes 13 are evenly distributed along the pile wall in the middle of the second section of the steel pipe pile segment 110 below the pile top of the steel pipe pile body 11, and the plurality of ventilation holes 13 are staggered with the auxiliary components on the steel pipe pile body 11; the number of ventilation holes 13 can be set according to actual needs, and the number of ventilation holes 13 in this embodiment is two.

[0061] Each vent hole 13 is an elliptical hole, the long diameter a of each vent hole 13 is parallel to the central axis of the steel pipe pile body 11 , and the short diameter b of each vent hole 13 is perpendicular to the central axis of the steel pipe pile body 11 .

[0062] The long diameter a and short diameter b of the vent hole 13 are set according to relevant parameters such as the outer diameter R of the steel pipe pile, the load-bearing cross-sectional area S1 of the steel pipe pile, the length L of the steel pipe pile, the water entry height of the steel pipe pile, the weight M of the hydraulic hammer, the gravity F of the pile driving hammer, the assumed pile sliding height h2 when the steel pipe pile is sunk, and the pile sliding time t.

[0063] The major diameter a and the minor diameter b of each vent hole 13 are calculated according to the following steps:

[0064] Step 1: Calculate the gas pressure P in the pile when the hydraulic hammer 2 can just be lifted up without opening the vent hole and assuming that the steel pipe pile slips during pile sinking.

[0065] According to the pressure calculation formula:

[0066]

[0067] In formula (1), P is pressure, unit: Pa; F is pressure, unit: N; S is the force area, that is, the cross-sectional area S1 of the steel pipe pile, unit: m 2 ;

[0068] At this time, the pressure F is equal to the weight of the pile hammer, that is:

[0069] F=M×g (2)

[0070] In formula (2): M is the weight of the hydraulic hammer, unit: kg; g is the acceleration due to gravity, which is 9.8 N / kg;

[0071] Therefore, formula (1) becomes:

[0072]

[0073] Step 2: Calculate the pile height h2 of the steel pipe pile

[0074] According to Boyle's law, at a constant temperature and a constant quantity, the volume of an ideal gas is inversely proportional to the pressure of the gas. The calculation formula is:

[0075] P1×V1=P2×V2 (4)

[0076] In formula (4): P1 is the atmospheric pressure, usually 1 standard atmospheric pressure = 0.1 MPa = 1.01 × 105 N / m 2 ; V1 is the volume of the gas in the pile when it is not compressed, unit: m 3 ; P2 is the pressure of the gas in the pile after compression, P2 = P, unit: Pa; V2 is the volume of the gas in the pile after compression, unit: m 3 ;

[0077] Substituting into formula (4) we get:

[0078] P1×S1×(L-h1)=P2×S1(L-h1-h2) (5)

[0079] In formula (5), L is the total length of the steel pipe pile, unit: m; h1 is the height of the steel pipe pile entering the water (the height from the water surface to the pile bottom), unit: m; h2 is the sliding height of the steel pipe pile, unit: m;

[0080] Through formula (5), we can get:

[0081]

[0082] Step 3: Calculate the air velocity V under P2 state, unit: m / s

[0083] According to Bernoulli's principle, during the gas flow process, Bernoulli's equation can be simplified to:

[0084] P2=0.5ρV 2 (7)

[0085] In formula (7): ρ is the air density, which is 1.29 kg / m 3 ;

[0086] From formula (7), we can get:

[0087]

[0088] Step 4: Calculate the area S2 of each vent hole opened on the steel pipe pile

[0089] According to the principle that the volume of gas discharged from A vents is equal to the volume of gas compressed, we can get:

[0090] S1×h2=A×S2×V×t (9)

[0091] From formula (9), we can get:

[0092]

[0093] Substituting h2 calculated by formula (6) and V calculated by formula (8) into formula (10), we can obtain:

[0094]

[0095] In formula (11), t is the sliding time of the steel pipe pile, which is taken as 30s according to construction experience;

[0096] Step 5: Set the long diameter a and short diameter b of the vent hole according to the calculated area S2 of the vent hole.

[0097] From the area calculation formula of the conventional elliptical vent: The major diameter a and the minor diameter b are set in (a>b>0).

[0098] During the construction of the offshore wind power large-diameter steel pipe pile of the present invention, the main process is as follows:

[0099] Process 1: Steel pipe pile production and marine transportation

[0100] When large-diameter steel pipe piles for offshore wind power are manufactured in a steel structure processing plant, after the steel pipe pile sections 110 are butt-welded, two vent holes 13 are opened on the second section of the steel pipe pile section 110 below the pile top, and then the lifting lugs 12 and other components are welded to the steel pipe pile body 11; after the steel pipe piles are manufactured, they are transported to the corresponding installation location at sea by barge;

[0101] Process 2: Steel Pipe Pile Driving

[0102] When the steel pipe pile is sunk, the top of the pile is blocked by the hydraulic hammer 2, and the bottom of the pile sinks into the seabed mud surface C by its own weight. If the pile slips due to the soft soil interlayer, the gas 3 in the steel pipe pile of the present invention can be directly discharged out of the pile through the vent hole 13 (see FIG. Figure 6 );

[0103] Process 3: Installation of integrated auxiliary components and anti-scour construction

[0104] After the steel pipe pile of the present invention is sunk, the integrated auxiliary components are directly installed and the anti-scour construction is carried out, without the need to carry out the construction process of absorbing water in the pile and spreading lime.

[0105] The offshore wind power large-diameter steel pipe pile of the present invention has the following characteristics:

[0106] 1) To solve the problem of "pile slippage" in large-diameter steel pipe piles for offshore wind power, which may cause damage to large ships and equipment. By timely discharging the gas in the pile, the impact force of the compressed gas in the pile on the hydraulic hammer can be effectively reduced;

[0107] 2) Solve the problem that after the construction of traditional steel pipe piles, a closed environment is formed, and the toxic and harmful gases produced by the decay of marine organisms in the piles are not connected to the atmosphere, avoiding the risk management of closed spaces;

[0108] 3) It reduces the construction process of absorbing water and spreading lime inside the pile after the pile is sunk, which can shorten the construction time of a single pile and reduce the construction cost.

[0109] The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those skilled in the relevant technical field may make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by the claims.

Claims

1. An offshore wind power large-diameter steel pipe pile, comprising a steel pipe pile body and a lifting lug; the steel pipe pile body is formed by butt welding of multiple sections of steel pipe pile sections; the lifting lug is fixed on the outer wall surface of the upper half of the steel pipe pile body, characterized in that: A plurality of ventilation holes are evenly distributed along the peripheral wall of the pile in the middle of the second section of the steel pipe pile below the pile top of the steel pipe pile body, and the plurality of ventilation holes are staggered with the auxiliary components on the steel pipe pile body; The vent hole is elliptical, and the long diameter a of the vent hole is parallel to the central axis of the steel pipe pile body, and the short diameter b of the vent hole is perpendicular to the central axis of the steel pipe pile body; the long diameter a and the short diameter b of the vent hole are calculated according to the following steps: Step 1: Calculate the gas pressure P in the pile when the hydraulic hammer can just be lifted up when the steel pipe pile slips during pile sinking without opening the vent hole. According to the pressure calculation formula: In formula (1): P is pressure, unit: Pa; F is pressure, unit: N; S is the load area, which is the cross-sectional area S1 of the steel pipe pile, unit: m 2 ; At this time, the pressure F is equal to the weight of the pile hammer, that is: F=M×g (2) In formula (2): M is the weight of the hydraulic hammer, unit: kg; g is the acceleration due to gravity, which is 9.8 N / kg; Therefore, formula (1) becomes: Step 2: Calculate the pile height h2 of the steel pipe pile According to Boyle's law, at a constant temperature and a constant quantity, the volume of an ideal gas is inversely proportional to the pressure of the gas. The calculation formula is: P1×V1=P2×V2 (4) In formula (4): P1 is the atmospheric pressure, usually 1 standard atmospheric pressure = 0.1 MPa = 1.01 × 105 N / m 2 ; V1 is the volume of the gas in the pile when it is not compressed, unit: m 3 ; P2 is the pressure of the gas in the pile after compression, P2 = P, unit: Pa; V2 is the volume of the gas in the pile after compression, unit: m 3 ; Substituting into formula (4) we get: P1×S1×(L-h1)=P2×S1(L-h1-h2) (5) In formula (5), L is the total length of the steel pipe pile, unit: m; h1 is the water entry height of the steel pipe pile, unit: m; h2 is the sliding height of the steel pipe pile, unit: m; Through formula (5), we can get: Step 3: Calculate the air velocity V under P2 state, unit: m / s According to Bernoulli's principle, during the gas flow process, Bernoulli's equation can be simplified to: P2=0.5ρV 2 (7) In formula (7): ρ is the air density, which is 1.29 kg / m 3 ; From formula (7), we can get: Step 4: Calculate the area S2 of each vent hole opened on the steel pipe pile According to the principle that the volume of gas discharged from A vents is equal to the volume of gas compressed, we can get: S1×h2=A×S2×V×t (9) From formula (9), we can get: Substituting h2 calculated by formula (6) and V calculated by formula (8) into formula (10), we can obtain: In formula (11): t is the sliding time of the steel pipe pile, which is 30s; Step 5: According to the calculated area S2 of the vent hole, set the long diameter a and short diameter b of the vent hole. From the area calculation formula of the conventional elliptical vent: Set the major diameter a and minor diameter b in.

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