An underwater measuring method for steel pipe piles of a jacket foundation by a pre-pile method

Abstract

The application discloses a kind of underwater measurement methods of pile guide method jacket foundation steel pipe pile, comprising: step one, making four measurement tool holders;Step two, four measurement tool holders with long baseline beacon are hoisted to the top surface of four steel pipe piles;Step three, each long baseline beacon is tracked and measured to the remaining three long baseline beacon, and the distance between piles is obtained;Step four, fixed pressure sensor is installed on the measurement tool holder on No.1 pile, and diver holds mobile pressure sensor and places 1-2 minutes on each measurement tool holder;Step five, the difference between the data collected by mobile pressure sensor and the data collected by fixed pressure sensor is calculated, that is, the height difference of pile top is obtained;Step six, the inclination of steel pipe pile is measured using the built-in attitude sensor of long baseline beacon;Step seven, according to the height difference of pile top of four steel pipe piles, the inclination of the plane of pile top of four steel pipe piles is calculated.The application can measure the state of steel pipe pile after sinking pile with high precision.

Description

Technical Field

[0001] This invention relates to an underwater measurement method for steel pipe piles in a jacket foundation using the pre-pile method. Background Technology

[0002] With the rapid development of the offshore wind power industry in China, more and more wind turbine foundation types are being applied. Among them, jacket foundations, due to their high strength, high rigidity, good stability, low installation noise, light weight, and convenient transportation and installation, can serve as the support structure for large wind turbine units. Jacket foundations are less affected by wave loads and are suitable for sea areas with a water depth range of 5-50m. Compared with other foundation types, they have the advantages of fast installation speed and low cost. Currently, offshore wind power is developing towards deep-sea areas. For offshore wind turbine foundations located more than 25km offshore and in water depths of 25m-50m, the jacket foundation structure (pre-pile method) is adopted. This foundation structure consists of four steel pipe piles and an internally inserted jacket. The jacket foundation is constructed using the pre-pile method, that is, the underwater piles of the steel pipe piles are first driven, then the four pointed sections of the bottom of the jacket are inserted one by one into the four steel pipe piles, and finally the steel pipe piles are grouted to fix the jacket to the steel pipe piles. Because the internal jacket needs to be connected to the steel pipe piles underwater, the control accuracy requirements for the plane position, elevation, verticality, and relative position of each pile are very high.

[0003] When conducting underwater pile driving operations in deep-sea areas, factors such as strong winds, large waves, and persistent surges, as well as equipment malfunctions on the pile stabilization platform, the connection between the pile driver and the steel pipe pile, and the condition of the hydraulic hammer, can all affect the accuracy of the steel pipe pile driving. Failure to conduct timely post-driving re-measurement can easily hinder the subsequent installation of the jacket structure. Currently, the underwater measurement method involves acoustic scanning + diving measurement verification + elevation measurement. This method has a measurement error of up to 10cm, making it impossible to further reduce the measurement accuracy. This significant error directly impacts the installation of the jacket structure. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an underwater measurement method for the steel pipe piles of the jacket foundation using the pre-pile method, which can perform high-precision measurement of the state of the steel pipe piles of the jacket foundation after pile driving is completed.

[0005] The objective of this invention is achieved as follows: an underwater measurement method for steel pipe piles in a pre-pile method for jacket foundations, comprising the following steps:

[0006] Step 1: Fabricate four measuring fixtures. Each measuring fixture includes a cross-shaped top frame welded from two long channel steels, each 100cm longer than the outer diameter of the steel pipe pile; four corresponding limiting plates mounted on the bottom surfaces of the two long channel steels on the top frame; a beacon base mounted at the center of the top surface of the top frame; and a guide seat connected to the bottom of the top frame. The guide seat has an inverted square truncated pyramid frame structure and includes a cross-shaped bottom frame welded from two short channel steels, each shorter than the inner diameter of the steel pipe pile; four diagonal bracing rods corresponding to the top surfaces of the four outer ends of the two short channel steels and the inner surfaces of the four limiting plates; a circle with a diameter 40cm smaller than the inner diameter of the steel pipe pile is inscribed in the center of the outer surfaces of the four limiting plates; and a lifting lug is fixed to each of the two long channel steels on the top surface of the corresponding four limiting plates.

[0007] Step two: hoisting the surveying fixtures. First, install the four long baseline beacons one by one on the beacon bases of the four surveying fixtures. Then, use a total station to initially calibrate the tilt angle of the surveying fixtures. Next, use the crane on the engineering vessel to hoist the four surveying fixtures one by one onto the top of the four steel pipe piles. With the assistance of divers, install the guide seats of the surveying fixtures underwater into the corresponding steel pipe piles, so that the top frame of each surveying fixture sits on the top surface of the corresponding steel pipe pile. Check whether there is a 20mm gap between the center of the outer side of the four limiting plates of the surveying fixture and the inner wall of the corresponding steel pipe pile, to ensure that the long baseline beacons are on the axis of the corresponding steel pipe piles.

[0008] Step 3: Measure the pile spacing. Each long baseline beacon tracks and measures the other three long baseline beacons. A total of twelve measurements are performed. The distance between the four long baseline beacons is obtained through multiple distance measurements and adjustments. After removing the gap between the measuring fixture and the steel pipe piles, the distance between the centers of the top surfaces of the four steel pipe piles is obtained.

[0009] Step 4: Measure the pile top elevation difference. Install a fixed pressure sensor on the top frame of the first installed measuring fixture to collect the water level data at the top frame of the measuring fixture. Then, the diver holds a movable pressure sensor and places it on the top frame of each measuring fixture for 1-2 minutes to collect the water level data at the top frame of each measuring fixture. Finally, retrieve the four measuring fixtures.

[0010] Step 5: Extract the water level data collected by the fixed pressure sensor, and calculate the difference between the water level data collected by the moving pressure sensor on the other three measuring fixtures and the water level data collected by the fixed pressure sensor. This gives the difference in the top height of the four steel pipe piles.

[0011] Step 6: Measure the inclination of the steel pipe pile using the attitude sensor built into the long baseline beacon. That is, after the measurement fixture is installed, the pitch angle and roll angle of the steel pipe pile can be obtained, and the inclination of the steel pipe pile can be obtained by combining them.

[0012] Step 7: Calculate the inclination of the top plane of the four steel pipe piles based on the height difference between their tops.

[0013] The above-mentioned underwater measurement method for steel pipe piles of jacket foundation using the pre-piling method includes a guide seat for the measurement fixture, which further includes four vertical struts that are connected one-to-one between the bottom inner side of the four diagonal struts and the bottom surface of the top frame.

[0014] In the above-mentioned underwater measurement method for steel pipe piles of jacket foundation using the pre-pile method, when performing step four, closed-loop measurement is carried out in the order of pile 1 → pile 2 → pile 3 → pile 4 → pile 1. The difference between the two measurement data of pile 1 is processed, and the error is evenly distributed to piles 2, 3 and 4.

[0015] The underwater measurement method for the steel pipe piles of the jacket foundation using the pre-pile method of the present invention has the following characteristics: the state of the steel pipe piles of the jacket foundation after pile driving is measured with high precision by using a crane vessel in conjunction with a long baseline measurement system. The measurement content includes the underwater steel pipe pile spacing, pile top height difference and tilt angle, etc., and the measurement accuracy reaches 1-2cm. The accuracy meets the design requirements after measurement and verification. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the tooling frame used in the underwater measurement method of the steel pipe pile foundation of the jacket foundation of the present invention.

[0017] Figure 2 yes Figure 1 Top view;

[0018] Figure 3 This is a state diagram of step three in the underwater measurement method for the steel pipe pile foundation of the jacket foundation of the present invention. Detailed Implementation

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] The underwater measurement method for steel pipe piles in the pre-pile method of jacket foundation of the present invention is characterized in that the underwater measurement method includes the following steps:

[0021] Step 1: Fabricate four measuring fixtures. Each fixture includes a top frame 10, a beacon base 1A, four limiting plates 12, and a guide seat. The top frame 1A is formed by welding two long channel steels 11, each 100cm longer than the outer diameter of the steel pipe pile, into a cross shape. The beacon base 1A is installed at the center of the top surface of the top frame 10. The four limiting plates 12 are installed one-to-one on the bottom surfaces of the two long channel steels 11 at both ends of the top frame 10. A circle with a diameter 40cm smaller than the inner diameter of the steel pipe pile is inscribed in the center of the outer surface of each limiting plate 12. The guide seat is connected to the bottom of the top frame 10. The frame structure is an inverted square pyramidal frame, including a base frame 13, four diagonal braces 14, and four vertical braces 15. The base frame 13 is made of two short channel steels with a length smaller than the inner diameter of the steel pipe pile, welded together in a cross shape. The four diagonal braces 14 are connected one-to-one between the top surfaces of the four outer ends of the two short channel steels and the inner surfaces of the four limiting plates 12. The four vertical braces 15 are connected one-to-one between the bottom inner surfaces of the four diagonal braces 14 and the bottom surface of the top frame 10. The two long channel steels 11 of the top frame 10 each have a lifting lug 16 fixed on the top surface of the corresponding four limiting plates 12 (see...). Figure 1 and Figure 2 );

[0022] Step two: hoisting the surveying fixtures. First, install the four long baseline beacons 20 one by one on the beacon bases 1A of the four surveying fixtures. Then, use a total station to initially calibrate the tilt angle of the surveying fixtures. Next, use the crane on the engineering vessel to hoist the four surveying fixtures one by one onto the top of the four steel pipe piles through the four lifting lugs on the surveying fixtures. With the assistance of divers, install the guide seats of the surveying fixtures underwater into the corresponding steel pipe piles, so that the top frame of each surveying fixture sits on the top surface of the corresponding steel pipe pile. Check whether there is a 20mm gap between the outer center of the four limiting plates of the surveying fixture and the inner wall of the corresponding steel pipe pile to ensure that the long baseline beacons are on the axis of the corresponding steel pipe piles.

[0023] Step 3: Conduct pile spacing measurement, that is, each long baseline beacon 20 tracks and measures the other three long baseline beacons 20 using the principle of underwater acoustics (see...). Figure 3 A total of twelve measurements were conducted. The distance between the four long baseline beacons 20 was obtained through multiple distance measurements and adjustments. The gap between the measuring fixture and the steel pipe piles was removed, and the distance between the centers of the top surfaces of the four steel pipe piles 101 to 104 was obtained.

[0024] Step 4: Measure the height difference at the top of the piles. To improve measurement accuracy, it is best to do so during the low tide period. Install a fixed pressure sensor on the top frame of the first installed measuring fixture (on pile 1) to collect water level data at the top frame of the measuring fixture. Then, the diver holds a movable pressure sensor and places it on the top frame of each measuring fixture for 1-2 minutes to collect water level data at the top frame of each measuring fixture. Perform closed-loop measurements in the order of pile 101 → pile 202 → pile 303 → pile 404 → pile 101. Process the difference between the two measurements of pile 1 and distribute the error evenly to piles 2, 3, and 4. Then retrieve the four measuring fixtures.

[0025] Step 5: Extract the water level data collected by the fixed pressure sensor, and calculate the difference between the water level data collected by the moving pressure sensor on the other three measuring fixtures and the water level data collected by the fixed pressure sensor. This gives the difference in the top height of the four steel pipe piles.

[0026] Step 6: Measure the inclination of the steel pipe pile using the attitude sensor built into the long baseline beacon. That is, after the measurement fixture is installed, the pitch angle and roll angle of the steel pipe pile can be obtained. After combining them, the top surface inclination of the steel pipe pile can be obtained.

[0027] Step 7: Calculate the inclination of the top plane of the four steel pipe piles based on the height difference between their tops.

[0028] The measurement method of this invention is illustrated using the measurement results of four steel pipe piles at one turbine location of an offshore wind power plant:

[0029] The maximum pile spacing is: the distance between pile No. 2 and pile No. 3 is 30.034m;

[0030] The minimum pile spacing is: the distance between pile No. 3 and pile No. 4 is 29.954m;

[0031] Considering that a 20mm gap is set between the outer center of the four limiting plates on the measuring fixture and the inner wall of the steel pipe pile, the actual measurement error of the pile spacing is 0-40mm. The measurement results of the pile spacing of the four steel pipe piles are shown in Table 1 below:

[0032] Table 1

[0033] Pile spacing number Beacon distance (m) Distance between piles (m) Pile 1 - Pile 2 30.025 30.025±0.04 Pile 2 - Pile 3 30.034 30.034±0.04 Pile 3-Pile 4 29.954 29.954±0.04 Pile 4 - Pile 1 30.027 30.027±0.04

[0034] The verticality of a steel pipe pile refers to the verticality of the top surface of the steel pipe pile.

[0035] The elevation of the steel pipe piles is referenced to the top surface elevation of pile No. 1. The difference in pile top elevation is the difference between the top surface elevation of pile No. 2 and the top surface elevation of pile No. 1, the difference between the top surface elevation of pile No. 3 and the top surface elevation of pile No. 1, and the difference between the top surface elevation of pile No. 4 and the top surface elevation of pile No. 1.

[0036] The inclination of the top surface of the steel pipe pile is the inclination angle and orientation of the plane formed by fitting the top surfaces of the four steel pipe piles.

[0037] The measurement results are shown in Table 2 below:

[0038] Table 2

[0039]

[0040]

[0041] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. An underwater measurement method for steel pipe piles in a jacket foundation using the pre-pile method, characterized in that, The underwater measurement method includes the following steps: Step 1: Fabricate four measuring fixtures. Each measuring fixture includes a cross-shaped top frame welded from two long channel steels, each 100cm longer than the outer diameter of the steel pipe pile; four corresponding limiting plates mounted on the bottom surfaces of the two long channel steels on the top frame; a beacon base mounted at the center of the top surface of the top frame; and a guide seat connected to the bottom of the top frame. The guide seat has an inverted square truncated pyramid frame structure and includes a cross-shaped bottom frame welded from two short channel steels, each shorter than the inner diameter of the steel pipe pile; four diagonal bracing rods corresponding to the top surfaces of the four outer ends of the two short channel steels and the inner surfaces of the four limiting plates; a circle with a diameter 40cm smaller than the inner diameter of the steel pipe pile is inscribed in the center of the outer surfaces of the four limiting plates; and a lifting lug is fixed to each of the two long channel steels on the top surface of the corresponding four limiting plates. Step two: hoisting the surveying fixtures. First, install the four long baseline beacons one by one on the beacon bases of the four surveying fixtures. Then, use a total station to initially calibrate the tilt angle of the surveying fixtures. Next, use the crane on the engineering vessel to hoist the four surveying fixtures one by one onto the top of the four steel pipe piles. With the assistance of divers, install the guide seats of the surveying fixtures underwater into the corresponding steel pipe piles, so that the top frame of each surveying fixture sits on the top surface of the corresponding steel pipe pile. Check whether there is a 20mm gap between the center of the outer side of the four limiting plates of the surveying fixture and the inner wall of the corresponding steel pipe pile, to ensure that the long baseline beacons are on the axis of the corresponding steel pipe piles. Step 3: Measure the pile spacing. Each long baseline beacon tracks and measures the other three long baseline beacons. A total of twelve measurements are performed. The distance between the four long baseline beacons is obtained through multiple distance measurements and adjustments. After removing the gap between the measuring fixture and the steel pipe piles, the distance between the centers of the top surfaces of the four steel pipe piles is obtained. Step 4: Measure the pile top elevation difference. Install a fixed pressure sensor on the top frame of the first installed measuring fixture to collect the water level data at the top frame of the measuring fixture. Then, the diver holds a movable pressure sensor and places it on the top frame of each measuring fixture for 1-2 minutes to collect the water level data at the top frame of each measuring fixture. Finally, retrieve the four measuring fixtures. Step 5: Extract the water level data collected by the fixed pressure sensor, and calculate the difference between the water level data collected by the moving pressure sensor on the other three measuring fixtures and the water level data collected by the fixed pressure sensor. This gives the difference in the top height of the four steel pipe piles. Step 6: Measure the inclination of the steel pipe pile using the attitude sensor built into the long baseline beacon. That is, after the measurement fixture is installed, the pitch angle and roll angle of the steel pipe pile can be obtained, and the inclination of the steel pipe pile can be obtained by combining them. Step 7: Calculate the inclination of the top plane of the four steel pipe piles based on the height difference between their tops.

2. The underwater measurement method for steel pipe piles in the jacket foundation using the pre-pile method according to claim 1, characterized in that, The guide seat of the measuring fixture also includes four vertical struts that are connected one-to-one between the bottom inner side of the four diagonal struts and the bottom surface of the top frame.

3. The underwater measurement method for steel pipe piles in the jacket foundation using the pre-pile method according to claim 1, characterized in that, When performing step four, a closed-loop measurement is carried out in the order of pile 1 → pile 2 → pile 3 → pile 4 → pile 1. The difference between the two measurement data of pile 1 is processed, and the error is evenly distributed to piles 2, 3 and 4.

Images