RU2346110C2 - Method for erection of offshore structure - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention is related to hydrotechnical construction and is intended for erection of stationary offshore structures with continuous bearing block fixed by piles to sea bottom. Method for erection of offshore structure consists in the fact that bearing block is manufactured on shore out of two sections joined vertically: lower and upper tiers of bearing block. Lower tier of bearing block is installed on bottom and is fixed by "short" piles rammed through its main stands in bottom until they enter compact subsoil and providing stability of bearing block lower tier in initial period of sea erection works. Upper tier of bearing block is installed onto lower tier so that stands of bearing block upper tier are attached to "short" piles, afterwards intratubal soil plug is removed in "short" piles, and "long" piles that bear upper structure are rammed through them and stands of upper tier. In case of underwater joining of bearing block tiers, docking assembly is enveloped by caisson on the outside and sealed with packer or underwater welding. Afterwards water from stand of upper bearing block and caisson is pumped down to the level below attachment seam, which is prepared and welded on the inside of stand by automatic electric welding under normal atmospheric conditions. If stand diameter is considerable, electric welding is done by welder placed on floating pontoon, which is lowered and lifted in stand by supply or drain of outside water. After "long" piles have been rammed and attached to stands of upper tier of bearing block, intratubal space of piles, stands and caissons are filled with mortar.

EFFECT: higher reliability of offshore structures operation due to higher stability and reduction of structure metal intensity by reduction of bearing block upper tier stand diameter and reduction of stand and pile thickness at higher strength of piles, possibility to use crane ships of lower tonnage, and also to leave lower tier of bearing block fixed by piles with underwater end of stands and piles for the period of unfavorable ice conditions.

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Description

Technical field

The invention relates to hydraulic engineering and can be used mainly in the construction of offshore stationary platforms, with a through support block, fixed to the seabed with piles.

State of the art

Widely known are the methods of constructing offshore platforms, involving the manufacture of a support block on the shore, transportation and its installation at the bottom, fastening with piles and subsequent installation of the upper structure. [1] (“Exploration and exploitation of offshore oil and gas fields” V.I. Mishchevich, B. M. Loguntsov, N. P. Umanchik and others - M .: Nedra, 1978). The disadvantages of these methods include the need to use crane vessels of very high carrying capacity, the need to complete all construction and installation works in one navigation season.

There is a method of constructing offshore platforms, involving the manufacture on the shore of a support block of several sections (tiers), transportation and installation at the bottom of the lower tier, building it up with the upper tier, fastening with piles and subsequent installation of the upper structure. [2] (“Marine hydraulic structures on the continental shelf”: Textbook. G.V.Simakov, K.N. Shkhinek, V.A.Smelov and others - L .: Shipbuilding, 1989). The disadvantages of this method include the low stability of individual blocks of a multi-block structure until the completion of their building and fastening by piles.

There is a method of constructing an offshore platform in which the base and deck are transported with technological equipment in a surface position to the installation site, the base is installed at the bottom and fastened to the bottom using piles. In this case, the installation of cemented piles is carried out in pre-drilled stepped pile wells, and their length is chosen from the condition of overlapping unstable rocks [3]. (Invention No. 2198261, class E 02 B 17/00, 02/10/2003). The disadvantages of this method include the long duration of pile fastening.

SUMMARY OF THE INVENTION

The aim of the invention is to increase the reliability of operation of the platforms by increasing their stability and reducing the metal consumption of the structure by reducing the diameter of the racks of the upper tier of the support block and reducing the thickness of the racks and piles while increasing the strength of the piles, the use of 'crane vessels of lower carrying capacity, as well as the ability to leave the lower fixed by piles the tier of the support block with the underwater end of the uprights and piles during unfavorable ice conditions.

This goal is achieved by the fact that the support block is made ashore from two vertically composed sections: the lower and upper tiers of the support block. The lower tier of the support block is installed on the bottom and secured with “short” piles, driven through its main pillars into the bottom before entering the dense underlying soil layer and ensuring the stability of the lower tier of the support block during the initial period of installation work at sea. The upper tier of the support block is installed on the lower tier in such a way that the racks of the upper tier of the support block are joined with the "short" piles, after which the in-tube earth plug in the "short" piles is removed and the "long" piles carrying the upper structure are driven through them. In the case of underwater joining of the tiers of the support block, the docking unit is covered outside with a caisson and sealed with a packer or underwater welding, after which the water from the rack of the upper support block and the caisson is pumped to a level below the docking seam, which is prepared and welded from the inside of the rack by automatic electric welding in normal atmospheric conditions. With a large diameter of the rack, electric welding is performed by a welder placed on a floating pontoon, which is lowered and raised in the rack by removing or supplying outboard water to it. After driving and connecting “long” piles with uprights of the upper tier of the support block, the annular space of piles, uprights and caissons is filled with cement mortar.

The drawing shows a docking unit, a longitudinal section.

Information confirming the possibility of carrying out the invention.

The support block of the offshore platform is made ashore from two vertical sections: the lower and upper tiers of the support block. The lower tier of the support block 1 is installed on the bottom and fixed with “short” piles 2, driven into the bottom by means of its main posts 3 to the bottom until it enters the dense underlying soil layer and ensuring the stability of the lower tier of the support block 1 during the initial period of installation work at sea. The upper tier of the support block 4 is installed on the lower tier 1 in such a way that the racks 5 of the upper tier of the support block 4 are joined using centering strips 6 and an electric-welded seam 7 with “short” piles 2. After that, the inner tube plug in the “short” piles 2 is removed and through them and racks 5, “long” piles 8 are driven, bearing the upper structure. In the case of underwater docking of the tiers of the support block, the docking assembly is covered externally with a caisson 9 and sealed with packers 10 or an undersea weld seam. 11, after which the water from the rack 5 of the upper tier of the support block 4 and the caisson 9 is pumped to a level below the butt weld seam 7, which is prepared and welded from the inside of the rack 5 by automatic electric welding in normal atmospheric conditions. With a large diameter of the rack 5, the electric welding of the seam 7 is performed by a welder placed on a floating pontoon, which is lowered and raised in the rack 5 by removing or supplying sea water to it. After driving and connecting the "long" piles 8 with the uprights 5 of the upper tier of the support block 4, the annular space of the piles, uprights and caissons is filled with cement mortar 12.

The proposed technical solution improves the reliability of the platforms by increasing their stability and reduces the metal consumption of the structure by reducing the diameter of the racks of the upper tier of the support block and reducing the thickness of the racks and piles while increasing the strength of the piles. It allows the use of crane vessels of lower carrying capacity, as well as leaving the lower tier of the support block fixed with piles with the underwater end of the racks and piles for the period of adverse ice conditions.

Claims (1)

A method of constructing an offshore platform with a through support block fixed to the seafloor by piles, characterized in that the support block is made on the shore of two vertical sections: the lower and upper tiers of the support block, after transportation, the lower tier of the support block is installed on the bottom and fixed short ”piles, clogged through its main racks into the bottom before entering the dense underlying layer of soil and ensuring stability of the lower tier of the support block in the initial period of installation work at sea, and the upper The support block rus is installed on the lower tier in such a way that the uprights of the upper tier of the support block are joined with the “short” piles, after which the in-tube earth plug in the “short” piles is removed and the “long” piles carrying the upper structure are hammered through them and the upper tier racks in this case, in the case of underwater docking of the tiers of the support block, the docking assembly is covered on the outside with a caisson and sealed with a packer or underwater welding, after which the water from the rack of the upper support block and caisson is pumped to a level below the docking a seam that is prepared and welded from the inside of the rack by automatic electric welding in normal atmospheric conditions, with a large diameter of the rack, electric welding is performed by a welder placed on a floating pontoon, which is lowered and raised in the rack by removing or supplying outboard water to it; in this case, after driving and connecting “long” piles with uprights of the upper tier of the support block, the annulus of piles, racks and caissons is filled with cement mortar.