1. The offshore platform pile foundation construction method is characterized by comprising the following steps:

s1, manufacturing a bearing platform steel truss, wherein the bearing platform steel truss is provided with a plurality of pile holes distributed in a row and column mode;

s2, determining the length of a pile foundation according to the drilling position and the water depth of the offshore construction site;

s3, dragging the pile cap steel truss to an offshore construction site, enabling the pile holes to correspond to the drilling positions one by one, hoisting the pile foundation, inserting the pile foundation into the pile hole, lowering the pile foundation into the drilling hole, and driving the pile to a preset depth by adopting a vibration hammer;

and S4, fixing the pile cap steel truss and the pile foundation to reach the design height, and welding a panel above the pile cap steel truss to form the offshore platform.

2. The offshore platform pile foundation construction method of claim 1, wherein during pile foundation fabrication, the plurality of pile foundation segments are spliced to reach a determined pile foundation length, the plurality of pile foundation segments are temporarily fixed by using a connector during splicing, the connector comprises a pair of fasteners and a high-strength bolt nut, the pair of fasteners are matched with the periphery of the pile foundation segments, welding holes are reserved in the fasteners, and reinforcing plates are arranged above and below the welding holes.

3. The offshore platform pile foundation construction method of claim 1, wherein the drilling is performed in stages, a first stage of large stroke impact, a second stage of small stroke impact, and a third stage of large stroke impact.

4. The offshore platform pile foundation construction method of claim 3, wherein the first stage stroke height is less than or equal to 1m, the second stage stroke height is less than or equal to 0.6m, and the third stage stroke height is less than or equal to 1 m.

5. The offshore platform pile foundation construction method of claim 1, wherein the slurry is adjusted at any time while drilling the hole, specifically comprising: and (4) separating and discharging large particles after pumping and discharging the instant hole bottom slurry, and re-injecting the small particles and the slurry into the finished drilled hole bottom after collecting.

6. The offshore platform pile foundation construction method of claim 5, wherein the slurry is adjusted in a cyclone separator, the cyclone separator is of a conical structure with a large upper part and a small lower part, the upper side wall of the cyclone separator is a feed inlet, the bottom of the cyclone separator is contracted to form a large particle discharge outlet, the upper half part of the cyclone separator is provided with a flow guide pipe along the axis of the cyclone separator, the upper end of the flow guide pipe extends out of the top of the cyclone separator to form a slurry discharge outlet, and the lower end of the flow guide pipe is lower than the feed inlet.

7. The offshore platform pile foundation construction method of claim 1, wherein after S3 pile driving, the steel bar keel and the draft tube are inserted into the pile foundation in sequence, and then concrete is poured through the draft tube until the design requirements are met.

Background

The offshore platform is used for carrying out shallow sea geological exploration, pile foundation piling construction and the like at home so as to meet engineering construction operation. The existing offshore platform comprises a fixed type, a semi-fixed type, a floating type and the like, and the pile foundation type is a fixed type platform which is the most common platform form in the construction of shallow sea engineering at present. When the pile foundation type platform is built, the pile foundation is driven into the sea bottom, and a bearing platform is installed on the pile foundation as a construction platform. Due to the fact that the pile foundation is operated on the sea, under the conditions of ocean underwater complex landforms and seawater flowing, construction conditions are poor, positioning accuracy and stability of the pile foundation are poor, and the pile foundation is not capable of being positioned and adjusted simultaneously.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide a construction method of the offshore platform pile foundation, which has simple structure and strong construction adaptability, is suitable for engineering operations such as offshore drilling and engineering investigation, and can be transversely and longitudinally expanded according to engineering requirements to increase the application range of the offshore platform pile foundation.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided an offshore platform pile foundation construction method, comprising the steps of:

s1, manufacturing a bearing platform steel truss, wherein the bearing platform steel truss is provided with a plurality of pile holes distributed in a row and column mode;

s2, determining the length of a pile foundation according to the drilling position and the water depth of the offshore construction site;

s3, dragging the pile cap steel truss to an offshore construction site, enabling the pile holes to correspond to the drilling positions one by one, hoisting the pile foundation, inserting the pile foundation into the pile hole, lowering the pile foundation into the drilling hole, and driving the pile to a preset depth by adopting a vibration hammer;

and S4, fixing the pile cap steel truss and the pile foundation to reach the design height, and welding a panel above the pile cap steel truss to form the offshore platform.

Preferably, when the pile foundation is manufactured, the determined pile foundation length is achieved after the plurality of pile foundation sections are spliced, the plurality of pile foundation sections are temporarily fixed by adopting a connecting piece during splicing, the connecting piece comprises a pair of fasteners and high-strength bolts and nuts, the pair of fasteners are matched with the periphery of the pile foundation sections, welding holes are reserved in the fasteners, and reinforcing plates are arranged above and below the welding holes of the fasteners.

Preferably, the drilling is performed in stages, a first stage large stroke impact, a second stage small stroke impact, and a third stage large stroke impact.

Preferably, the stroke height of the first stage is less than or equal to 1m, the stroke height of the second stage is less than or equal to 0.6m, and the stroke height of the third stage is less than or equal to 1 m.

Preferably, the mud is adjusted at any time while drilling, and the method specifically comprises the following steps: and (4) separating and discharging large particles after pumping and discharging the instant hole bottom slurry, and re-injecting the small particles and the slurry into the finished drilled hole bottom after collecting.

Preferably, the slurry is adjusted in a cyclone separator, the cyclone separator is of a conical structure with a large upper part and a small lower part, the upper side wall of the cyclone separator is a feed inlet, the bottom of the cyclone separator is contracted to form a large-particle discharge outlet, a flow guide pipe is arranged at the upper half part of the cyclone separator along the axis of the cyclone separator, the upper end of the flow guide pipe extends out of the top of the cyclone separator to form a slurry discharge outlet, and the lower end of the flow guide pipe is lower than the feed inlet.

Preferably, after S3 pile driving is finished, steel bar keels and the guide pipe are sequentially inserted into the pile foundation, and then concrete is poured through the guide pipe until the design requirements are met.

The invention at least comprises the following beneficial effects:

firstly, the invention has simple structure and strong construction adaptability, and offshore platforms with different sizes can be designed and built according to the engineering requirements;

secondly, the invention is little affected by wind and waves, the safety and the reliability are good, and the bearing capacity of the pile foundation can meet the requirement of bearing load;

thirdly, the occupied water area of the invention does not exceed the area of the platform, and the invention does not need to be anchored around the offshore platform;

fourthly, the invention is convenient to install and disassemble, and the components can be prefabricated and molded on land and then transported to the offshore construction site without causing pollution and hidden danger to the water area;

fifthly, the invention is suitable for engineering operations such as offshore drilling, engineering investigation and the like, and can be transversely and longitudinally expanded according to engineering requirements to increase the application range of the device.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Detailed Description

The present invention is described in further detail below with reference to specific details so that those skilled in the art can practice the invention with reference to the description.

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

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "disposed" are to be construed broadly and can, for example, be fixedly connected, disposed, detachably connected, disposed, or integrally connected and disposed. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. The terms "transverse," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the indicated orientations and positional relationships to indicate orientations and positional relationships based on those shown, merely to facilitate description of the invention and to simplify description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be construed as limiting the present invention.

The invention provides a construction method of an offshore platform pile foundation, which comprises the following steps:

s1, manufacturing a bearing platform steel truss which has a supporting function and a hole opening guiding function, welding the bearing platform steel truss into a frame structure by adopting I-shaped steel, channel steel and the like, calculating platform load before building, and designing the structure and specification of the bearing platform steel truss, wherein the bearing platform steel truss is provided with a plurality of pile holes distributed in a row and column mode, the number of the pile holes can be 2 x 3 and 4 x 5, and the diameter of the pile holes can be 500mm and 600 mm;

s2, determining the length of a pile foundation according to the drilling position and the water depth of an offshore construction site, wherein the pile foundation can be formed by splicing a plurality of prefabricated sections after being transported to the site by flanges and the like or integrally formed, the lengths of the pile foundations are not necessarily equal, and the lengths of the pile foundations need to be determined according to the drilling position and the water depth of the submarine topography;

s3, pulling the pile cap steel truss to an offshore construction site, wherein the pile holes correspond to the positions of the drill holes one by adopting a hoisting mode or a transport ship pulling mode, limiting the pile cap steel truss after positioning to limit the large swing of the pile cap steel truss, hoisting the pile foundation, inserting the pile foundation into the pile holes, placing the pile foundation into the drill holes, enabling the pile foundation to correspond to the drill holes after inserting the pile holes, and driving the pile to a preset depth by adopting a vibration hammer to enable the pile cap steel truss, the pile foundation and the drill holes to be preliminarily positioned and locked;

and S4, fixing the bearing platform steel truss and the pile foundation to a designed height, for example, 3-5m higher than the sea level, welding a panel above the bearing platform steel truss to form an offshore platform, wherein the panel can be welded on site by adopting block prefabrication, and the panel is an anti-skid plate.

In the technical scheme, the method has the following advantages:

(1) the structure is simple, the construction adaptability is strong, and offshore platforms with different sizes can be designed and constructed according to the engineering requirements;

(2) the invention is little influenced by wind and waves, has good safety and reliability, and the bearing capacity of the pile foundation can meet the requirement of bearing load;

(3) the occupied water area of the invention does not exceed the area of the platform, and the invention does not need to be anchored around the offshore platform;

(4) the invention is convenient to install and disassemble, and the components can be prefabricated and molded on land and then transported to the offshore construction site, thus avoiding pollution and hidden danger to the water area;

(5) the invention is suitable for engineering operations such as offshore drilling, engineering investigation and the like, and can be transversely and longitudinally expanded according to engineering requirements to increase the application range of the device.

In another technical scheme, when the pile foundation is manufactured, the determined pile foundation length is achieved after the multiple pile foundation sections are spliced, the multiple pile foundation sections are temporarily fixed by adopting a connecting piece during splicing, the connecting piece comprises a pair of buckling pieces and high-strength bolts and nuts, the pair of buckling pieces are matched with the peripheries of the pile foundation sections, welding holes are reserved in the buckling pieces, and reinforcing plates are arranged above and below the welding holes of the buckling pieces. Compared with a sectional driving mode, the sectional driving mode is easy to be eccentric due to the fact that offshore construction conditions are poor, the mode that the connecting piece is fixed temporarily and then welded into an integral structure is adopted, the stress distribution formed by the gravity of the pile foundation and bending moment generated by inclination of the pile foundation is uniform, the stress distribution is smaller than the designed tensile strength of steel, construction requirements are met, stress concentration is relieved by the reinforcing plates above and below the welding hole, and safety is improved.

In another technical scheme, the drilling is carried out in stages, namely a first-stage large-stroke impact, a second-stage small-stroke impact and a third-stage large-stroke impact. In the drilling process, the condition of sediments needs to be concerned, and the punching in the stage of first big, then small and finally big is beneficial to distinguishing the apoplastic layer.

In another technical scheme, the stroke height of the first stage is less than or equal to 1m, the stroke height of the second stage is less than or equal to 0.6m, and the stroke height of the third stage is less than or equal to 1 m. The data is empirical data and can be adapted to the bottom conditions of most shallow sea areas.

In another technical scheme, the step of adjusting the mud at any time during drilling specifically comprises the following steps: and (4) separating and discharging large particles after pumping and discharging the instant hole bottom slurry, and re-injecting the small particles and the slurry into the finished drilled hole bottom after collecting. The operation can timely increase the slurry concentration of the retaining wall by observing, measuring and adjusting the slurry density at any time, thereby meeting the construction requirements. The submersible pump can be arranged 60cm above the bottom of the hole, and mud circulation is realized through mud conveying and classification treatment.

In another technical scheme, slurry is adjusted in a cyclone separator, the cyclone separator is of a conical structure with a large upper part and a small lower part, the upper side wall of the cyclone separator is a feed inlet, the bottom of the cyclone separator is contracted to form a large-particle discharge outlet, a flow guide pipe is arranged at the upper half part of the cyclone separator along the axis of the cyclone separator, the upper end of the flow guide pipe extends out of the top of the cyclone separator to form a slurry discharge outlet, and the lower end of the flow guide pipe is lower than the feed inlet. Adopt cyclone can be quick, effectively carry out the sediment thick liquid separation, behind the mud that the hole bottom was taken out gets into cyclone, because gravity and centrifugal force, large granule (heavy) is discharged by the large granule bin outlet downwards along the interior conical surface spiral, the tiny particle is upwards along with the thick liquid is adverse current along the interior conical surface spiral, get into the honeycomb duct and discharge by arranging the thick liquid mouth, realize the separation, the tiny particle and the thick liquid performance index of collecting after the separation are good, satisfy design and standard requirement, pour into the drilling hole bottom of the hole that has been accomplished again.

In another kind of technical scheme, after S3 pile driving finishes, steel reinforcement fossil fragments, honeycomb duct are inserted in proper order to pile foundation inside, pour the concrete through the honeycomb duct afterwards to satisfy the design requirement. And removing sediments at the bottom of the hole after drilling, lowering the steel bar keel, designing an outward bulge structure at the top of the steel bar keel to limit the steel bar keel to float upwards, lowering the flow guide pipe to avoid rubbing the steel bar keel by cutting, lowering the steel bar keel in place to clean the hole, pouring underwater concrete when the sediments are qualified, and pouring operation to pay attention to the burial depth and pouring amount and ensure the strength of the concrete.

The number of apparatuses and the scale of the process described herein are intended to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.

While embodiments of the invention have been disclosed above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.