WO2023010724A1

WO2023010724A1 - Offshore platform pile foundation construction method

Info

Publication number: WO2023010724A1
Application number: PCT/CN2021/133922
Authority: WO
Inventors: 何俊彪
Original assignee: 中国港湾工程有限责任公司
Priority date: 2021-08-03
Filing date: 2021-11-29
Publication date: 2023-02-09
Also published as: CN113404049A; ZA202203921B

Abstract

Disclosed is an offshore platform pile foundation construction method, which comprises the following steps: S1, fabricating a pile cap steel truss, wherein the pile cap steel truss has multiple pile holes distributed in rows and columns; S2, determining the length of a pile foundation according to the drilling positions and water depth of an offshore construction site; S3, towing the pile cap steel truss to the offshore construction site, making the pile holes correspond to the drilling positions one to one, hoisting and inserting the pile foundation into the pile holes and lowering the pile foundation to drilling holes, and pile driving same to a predetermined depth by using a vibration hammer; S4, fixing the pile cap steel truss and the pile foundation and reaching a designed height, and welding a panel above the pile cap steel truss to form an offshore platform. The present invention has a simple structure and high construction adaptability, and is suitable for engineering operations such as offshore drilling and well drilling, engineering surveying, and the like; and lateral and longitudinal expansions can be performed according to engineering requirements so as to increase an application range thereof.

Description

Construction method of offshore platform pile foundation

technical field

The present invention relates to offshore construction. More specifically, the present invention relates to a construction method for offshore platform pile foundations.

Background technique

Domestic shallow sea geological exploration and pile foundation piling construction are all carried out on offshore platforms to meet the needs of engineering construction operations. Existing offshore platforms include fixed, semi-fixed, floating, etc. The pile-based platform is a fixed platform, which is the most commonly used platform form in shallow sea engineering construction. When building a pile-based platform, the pile foundation is driven into the seabed, and the cap is installed on it as a construction platform. Due to the operation of pile foundation construction at sea, under the condition of complex underwater landform and seawater flow, the construction conditions are harsh, the positioning accuracy and stability of pile foundation are poor, and it does not have the ability to position and adjust all pile foundations at the same time.

Contents of the invention

It is an object of the present invention to solve at least the above-mentioned problems and to provide at least the advantages which will be described later.

Another object of the present invention is to provide a construction method for offshore platform pile foundations, which has a simple structure and strong construction adaptability, is suitable for offshore drilling, engineering survey and other engineering operations, and can be expanded horizontally and vertically according to engineering needs to increase its application range .

In order to realize these purposes and other advantages according to the present invention, a kind of offshore platform pile foundation construction method is provided, comprising the following steps:

S1, making a cap steel truss, the cap steel truss has a plurality of pile holes distributed in rows and columns;

S2. Determine the length of the pile foundation according to the drilling position and water depth of the offshore construction site;

S3. Tow the cap steel truss to the offshore construction site, and make the pile holes correspond to the drilling positions one by one, lift the pile foundation and insert it into the pile hole and lower it to the drilling hole, and use a vibrating hammer to drive the pile to a predetermined depth;

S4. Fix the cap steel truss and the pile foundation to the design height, and weld the panel above the cap steel truss to form an offshore platform.

Preferably, when making a pile foundation, a plurality of pile foundation segments are spliced to reach a certain length of the pile foundation, and when splicing a plurality of pile foundation segments, connectors are used to temporarily fix them, and the connectors include a pair of fastening parts, high-strength Bolts and nuts, a pair of fastening parts matching the outer circumference of the pile foundation segment, the fastening parts are reserved with welding holes, and the fastening parts are above and below the welding holes are provided with reinforcing plates.

Preferably, the drilling is carried out in stages, the first stage is large-stroke impact, the second stage is small-stroke impact, and the third stage is large-stroke impact.

Preferably, the stroke height of the first stage is ≤1m, the stroke height of the second stage is ≤0.6m, and the stroke height of the third stage is ≤1m.

Preferably, the mud is adjusted at any time while drilling, which specifically includes: separating and discharging the large particles after the immediate hole bottom mud is pumped, and re-injecting the small particles and the slurry into the bottom of the completed drilling hole after being collected.

Preferably, the slurry is adjusted in a cyclone separator. The cyclone separator has a large upper and lower conical structure. The upper side wall of the cyclone separator is a feed inlet, and the bottom shrinks to form a large particle discharge outlet. The cyclone separator The upper part of the device is provided with a guide tube along its axis, the upper end of the guide tube protrudes from the top of the cyclone separator to form a slurry outlet, and the lower end of the guide tube is lower than the feed inlet.

Preferably, after the S3 piling is completed, a reinforced keel and a diversion pipe are sequentially inserted into the pile foundation, and then concrete is poured through the diversion pipe to meet the design requirements.

The present invention at least includes the following beneficial effects:

First, the present invention has simple structure and strong construction adaptability, and can design and construct offshore platforms of different sizes according to engineering needs;

Second, the present invention is less affected by wind and waves, has good safety and reliability, and the bearing capacity of the pile foundation can meet the requirements of bearing load;

Third, the water area occupied by the present invention does not exceed the platform area, and there is no need to anchor around the offshore platform;

Fourth, the invention is easy to install and disassemble, and the components can be prefabricated on land and then transported to the offshore construction site without causing pollution or hidden dangers to the water area;

Fifth, the present invention is suitable for offshore drilling, engineering survey and other engineering operations, and can be expanded horizontally and vertically according to engineering needs to increase its application range.

Other advantages, objectives and features of the present invention will partly be embodied through the following descriptions, and partly will be understood by those skilled in the art through the study and practice of the present invention.

Detailed ways

The present invention will be further described in detail below in combination with details, so that those skilled in the art can implement it with reference to the description.

It should be understood that terms such as "having", "comprising" and "including" used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

It should be noted that the experimental methods described in the following embodiments, unless otherwise specified, are conventional methods, and the reagents and materials, if not otherwise specified, can be obtained from commercial sources; in the description of the present invention, It should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "arrangement" should be interpreted in a broad sense, for example, it can be fixedly connected, arranged, or detachably connected, arranged, or Connect and set in one piece. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations. The terms "landscape", "portrait", "top", "bottom", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", The orientation or positional relationship indicated by "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have Certain orientations, constructed and operative in certain orientations, therefore are not to be construed as limitations on the invention.

The invention provides a pile foundation construction method for an offshore platform, comprising the following steps:

S1. Manufacture the cap steel truss. The cap steel truss is used for supporting and opening guidance. The cap steel truss can be welded with I-shaped steel, channel steel, etc. to form a frame structure. Before construction, calculate the platform load and design the cap steel truss The structure and specifications of the pile cap steel truss have multiple pile holes distributed in rows and columns, the number of pile holes can be 2×3, 4×5, and the diameter of the pile holes can be 500mm, 600mm, etc.;

S2. According to the drilling position and water depth of the offshore construction site, the length of the pile foundation is determined. The pile foundation can be delivered to the site with prefabricated sections and spliced with flanges, etc., or it can be integrally formed. The length of the pile foundation is not necessarily equal. , which needs to be determined according to the drilling position and water depth of the seabed topography;

S3. Tow the cap steel truss to the offshore construction site, either by hoisting or pulling by a transport ship, and make the pile holes correspond to the drilling positions one by one, and limit the cap steel truss after positioning. Lift the pile foundation and insert it into the pile hole and lower it to the drill hole. After inserting the pile hole, it will correspond to the drill hole. Use a vibrating hammer to drive the pile to a predetermined depth, so that the cap steel truss and the pile foundation are in line with the drill hole. Achieve preliminary positioning and locking;

S4. Fix the cap steel truss and pile foundation to reach the design height, for example, 3-5m above sea level, and weld the panel above the cap steel truss to form an offshore platform. The panel can be prefabricated in blocks and welded on site. .

In the above technical scheme, it has the following advantages:

(1) The structure is simple and the construction adaptability is strong, and offshore platforms of different sizes can be designed and built according to the needs of the project;

(2) The present invention is less affected by wind and waves, has good safety and reliability, and the bearing capacity of the pile foundation can meet the requirements of bearing load;

(3) The water area occupied by the present invention does not exceed the platform area, and there is no need to anchor around the offshore platform;

(4) The present invention is easy to install and disassemble, and the components can be prefabricated on land and transported to the offshore construction site without causing pollution or hidden dangers to water areas;

(5) The present invention is suitable for engineering operations such as offshore drilling, engineering survey, etc., and can be expanded horizontally and vertically according to engineering needs to increase its application range.

In another technical solution, when making a pile foundation, a plurality of pile foundation segments are spliced to reach a certain length of the pile foundation, and a connector is used to temporarily fix the multiple pile foundation segments when splicing, and the connector includes a pair of buckles Fastening parts, high-strength bolts and nuts, a pair of fastening parts match the outer circumference of the pile foundation segment, the fastening parts are reserved with welding holes, and the fastening parts are provided with reinforcing plates above and below the welding holes. Compared with the segmented driving method, due to the harsh offshore construction conditions, the segmented driving is easy to be eccentric. Therefore, the method of temporarily fixing the connectors and then welding them into one piece ensures that the gravity of the pile foundation and the bending caused by the inclination of the pile foundation are formed perfectly. The stress distribution is uniform, less than the design tensile strength of the steel, which meets the construction requirements, and the reinforced version on the upper and lower sides of the welding hole relieves stress concentration and increases safety.

In another technical solution, the drilling is carried out in stages, the first stage is a large stroke impact, the second stage is a small stroke impact, and the third stage is a large stroke impact. During the drilling process, it is necessary to pay attention to the condition of the sediment. Punching at the first large, then small, and finally large stage is beneficial to distinguish the middle weathered layer.

In another technical solution, the stroke height of the first stage is ≤1m, the stroke height of the second stage is ≤0.6m, and the stroke height of the third stage is ≤1m. The data is empirical data, which can adapt to the bottom conditions of most shallow sea areas.

In another technical solution, the mud is adjusted at any time while drilling, which specifically includes: separating and discharging the large particles after the immediate hole bottom mud is pumped, and re-injecting the small particles and the slurry into the bottom of the completed drilling hole after being collected. This operation meets the construction requirements by observing, measuring and adjusting the mud density at any time, and increasing the mud concentration retaining wall in time. The submersible pump can be placed 60cm above the bottom of the hole, and the mud circulation can be realized through mud transportation and classification treatment.

In another technical solution, the slurry is adjusted in a cyclone separator, which has a large upper and lower conical structure, and the upper side wall of the cyclone separator is a feed inlet, and the bottom shrinks to form a large particle discharge. The upper part of the cyclone separator is provided with a guide tube along its axis, the upper end of the guide tube protrudes from the top of the cyclone separator to form a slurry discharge port, and the lower end of the guide tube is lower than the feed port. The cyclone separator can be used to quickly and effectively separate the slurry from the slurry. After the slurry drawn from the bottom of the hole enters the cyclone separator, due to gravity and centrifugal force, large particles (heavy) spiral downward along the inner cone surface and are discharged from the large particle discharge port. The small particles spiral upward along the inner cone surface with the backflow of the slurry, enter the diversion pipe and are discharged from the slurry discharge port to realize separation. The collected small particles and slurry have good performance indicators and meet the design and specification requirements. Drill the bottom of the hole.

In another technical solution, after the S3 piling is completed, a reinforced keel and a diversion pipe are sequentially inserted into the pile foundation, and then concrete is poured through the diversion pipe to meet the design requirements. After drilling, remove the sediment at the bottom of the hole, lower the steel keel and design an outward bulge structure on its top to limit its floating up, and pay attention to avoid scratching the steel keel when the diversion pipe is lowered, and lower it to the position to clean the hole. If the sediment is qualified, it will be carried out underwater Concrete pouring, pay attention to the depth of burial and the amount of pouring in the pouring operation to ensure the strength of the concrete.

The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations to the present invention will be apparent to those skilled in the art.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and those shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims

The offshore platform pile foundation construction method is characterized in that it comprises the following steps:

S1, making a cap steel truss, the cap steel truss has a plurality of pile holes distributed in rows and columns;

S2. Determine the length of the pile foundation according to the drilling position and water depth of the offshore construction site;

S3. Tow the cap steel truss to the offshore construction site, and make the pile holes correspond to the drilling positions one by one, lift the pile foundation and insert it into the pile hole and lower it to the drilling hole, and use a vibrating hammer to drive the pile to a predetermined depth;

S4. Fix the cap steel truss and the pile foundation to the design height, and weld the panel above the cap steel truss to form an offshore platform.
The method for constructing pile foundations on offshore platforms according to claim 1, wherein when making pile foundations, a plurality of pile foundation segments are spliced to reach a certain length of the pile foundation, and when splicing a plurality of pile foundation segments, a temporary connector is used. Fixing, the connecting piece includes a pair of fastening pieces, high-strength bolts and nuts, a pair of fastening pieces match the outer circumference of the pile foundation segment, the fastening pieces are reserved with welding holes, and the fastening pieces are located above the welding holes , The following are equipped with reinforcement boards.
The pile foundation construction method for an offshore platform according to claim 1, wherein the drilling is carried out in stages, the first stage is a large stroke impact, the second stage is a small stroke impact, and the third stage is a large stroke impact.
The pile foundation construction method for offshore platforms according to claim 3, wherein the stroke height of the first stage is ≤1m, the stroke height of the second stage is ≤0.6m, and the stroke height of the third stage is ≤1m.
The pile foundation construction method for offshore platforms according to claim 1, wherein the mud is adjusted at any time while drilling, which specifically includes: separating and discharging the large particles after the immediate hole bottom mud is pumped, and refilling the small particles after collecting the slurry. Inject into the bottom of completed boreholes.
The pile foundation construction method for offshore platforms according to claim 5, wherein the adjustment of mud is carried out in a cyclone separator, the cyclone separator has a large upper and lower conical structure, and the upper side wall of the cyclone separator is a The material port and the bottom shrink to form a large particle discharge port. The upper part of the cyclone separator is provided with a guide tube along its axis. The upper end of the guide tube protrudes from the top of the cyclone separator to form a slurry discharge port. The lower end is lower than the feed inlet.
The construction method for pile foundations on offshore platforms according to claim 1, characterized in that, after the piling in S3 is completed, a reinforced keel and a diversion pipe are sequentially inserted into the interior of the pile foundation, and then concrete is poured through the diversion pipe to meet the design requirements.