RU2739595C1 - Method of fixing support bases of offshore structures on pile field and pipe composite steel pile - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to methods of securing on pile field of support bases of marine stationary structures, such as offshore platforms, as well as to structures of piles used for this purpose. Method includes placing on sea bottom support base with guide holes made therein, intended for installation of piles, in which cylindrical grooves are made at certain height, installation of marine steel piles consisting of separate sections through guide holes of support structure of marine structure, which are successively connected to each other during pile driving into sea bed, at that, last section of each pile, in which a sealed cavity is made in advance, is installed opposite the cylindrical grooves made in the corresponding guide hole of the support base, after which working fluid is supplied into the sealed cavity under high pressure, for example, hydraulic oil, as a result of which when the yield point of metal wall of fixing section is deformed and pressed into annular grooves, made in support base guide hole, due to which support base is rigidly fixed on pile, eliminating possibility of vertical displacements along its axis. To implement the method, a special pipe composite steel pile structure is used, which consists of separate sections representing pipe sections, which are successively connected to each other, for example by welding, during pile driving, wherein the last fixing section differs from other sections in that a sealed cavity is formed inside it, formed by means of two partitions (steel plates) welded with a solid weld to its wall and located at some distance from each other, wherein thickness of these partitions exceeds the wall thickness of the pile section, due to which when supplying working fluid under pressure into the sealing cavity of the fixing section, its wall is deformed mainly in the radial direction, since its strength (due to difference in wall thickness and partitions) in radial direction is less than in axial. Besides, to supply working fluid under pressure to formed sealed cavity, as well as to bleed air from it in one of partitions there are unions. Also, to impart greater rigidity of connection of partition walls to wall section, connection points can be reinforced by additional reinforcing structural elements, such as books, struts, stiffeners and other, and using an additional reinforcing structural element, such as, for example, a rod or pipe connecting both partitions, even greater strength of fixing section design in its axial direction can be provided.

EFFECT: technical result consists in simplifying the technology and improving reliability of anchoring support bases of marine stationary structures on pipe steel piles, as well as in improving performance during installation works.

4 cl, 4 dwg

Description

SUBSTANCE: invention relates to methods of anchoring on a pile field of supporting foundations of stationary offshore structures, such as offshore platforms, as well as to structures of steel piles used.

A known method of fixing pipe steel piles in the support base of offshore stationary structures, used by Oil States Industries Inc. using the Hydra-Lok Swaged Connection Systems device (a video publication of the device's operation is posted on the Internet: https://www.youtube.com/watch?v=FMRe5-Wozz4), in which a support base of a stationary offshore structure is installed on the seabed , then pipe piles are driven into the bottom through guide sleeves having internal circular grooves-grooves, after which a special device is lowered into the piles, designed to unclamp the piles and equipped with hydraulic jacks installed so that the linings of the hydraulic jack rods are located in the middle of the inner circular grooves - recesses of the sleeves, then create pressure in the hydraulic system of the jacks, while the rods through the linings press on the inner surfaces of the piles until the pressure is reached, at which the pile material (steel) reaches the yield point and the pile wall is pressed into the groove-recess of the guide sleeve. After the completion of the deformation process of the pile wall, the pressure in the hydraulic system of the jacks is released, the rods, together with the linings, return to their original position and a special device is removed from the pile. Control over the process of unclamping the pile is carried out by changing the pressure in the hydraulic system, as well as using special sensors.

However, the known method has the disadvantages that the Hydra-Lok Swaged Connection Systems device is complex equipment, which requires high qualification of the service personnel, and the installation of piles also requires the use of high-power lifting and transport equipment.

There is also known a method of securing pipe steel piles in the guide sleeves of the support base by hydraulically expanding the section (s) of the pile into the inner circular grooves in the guide sleeve under the action of water pressure supplied to the inside of the isolated section of the pile (patent US4501514 dated 02.26.1985, IPC E02D5 / 54, B21D39 / 04). In this method, the sealing of the selected area, the provision of water supply and the creation of the required pressure is carried out using a device that is lowered into the pile, at the ends of which inflatable flexible sealing elements are installed.

The disadvantage of this method is that the device used for hydraulic expansion is difficult to manufacture and it can be configured only for one specific size of the pile and the guide sleeve, and, in addition, it requires the manufacture of special inflatable flexible sealing elements and for the installation of piles it is necessary to use lifting and transport equipment of high power.

Also known is a system of underwater connection between platform supports and foundation piles (patent US4695202 dated 09.22.1987, IPC E02B17 / 00), which includes anchor cylinders fixed to the platform supports, while the anchor cylinders consist of two coaxial cylinders, one of which is an outer cylinder , has a significant thickness and is made of high-strength steel, and the second is an inner cylinder, has a smaller thickness and is made of steel with a low yield strength, and the outer and inner cylinders are butt welded to each other in such a way as to form an annular chamber, and the piles are made of steels with high yield strength and have an outer surface with alternating grooves and teeth. During the supply of the working fluid under high pressure into the chamber, the wall of the inner cylinder is deformed and enters the grooves of the corresponding pile, due to which the platform supports are fixed on the foundation piles.

However, the known system has disadvantages, which are the complexity of the installation of the anchor cylinders, as well as the need to use heavy lifting equipment for the installation of piles.

Also known are the technical solutions disclosed in the patent for the invention of the Russian Federation No. 2689471, publ. 05/28/2019, IPC E02B17 / 00, E02D5 / 54 "Method of fastening steel pipe piles in the support foundation of offshore stationary hydraulic structures (platforms), as well as a device for its implementation", selected as a prototype. In accordance with the invention, the support base of the offshore structure is installed on the seabed, the pipe piles are driven through the guide sleeves of the support base into the seabed, a device equipped with hydraulic jacks is lowered into the pile so that the linings of the hydraulic jack rods are located in the middle of the inner circular groove made in the guide sleeve ; create pressure in the hydraulic system of jacks, the rods of which, through the linings, press on the inner surface of the pile until the pressure reaches a value at which the stress in the body of the pipe pile reaches the yield point of the pile material; in this way, the pile body is deformed into an inner circular groove of the guide sleeve; at the end of the deformation process, the pressure in the hydraulic system of the jacks is released, the jack rods, together with the linings, return to their original position and the device is lifted, while the process of unclamping the pile material is controlled by changing the pressure in the hydraulic system of the hydraulic jacks.

However, the known method has the following disadvantages:

1. To lower the inside of the piles of a special device equipped with hydraulic jacks, it is required to use sophisticated lifting and transport equipment of high power, which is complicated by the conditions of work in the open sea;

2. To ensure radial seals, a high purity of the pile surface is required in those places where it is expanded;

3. The work requires the involvement of highly qualified personnel;

4. There is no possibility of using equipment pre-configured on the shore for piles of a different diameter.

The technical problem solved by the present invention is the complexity and unreliability of the known methods of fixing the support foundations of stationary offshore structures on a pile field, consisting of steel pipe piles, which exclude the possibility of moving the support foundations along the axis of the piles after their fixation.

The technical result of the present invention is to simplify the technology and improve the reliability of the anchoring of the support bases of stationary offshore structures on steel pipe piles, as well as increase the productivity of installation work.

The specified technical result is achieved through the use of a method for securing the support foundations of offshore structures on a pile field, including the installation through the guide holes of the support base of the offshore structure of pipe composite steel piles, consisting of separate sections, which are sequentially connected to each other during piling into the seabed, the last, fixing section of each pile differs from other sections in that an airtight cavity is formed inside it, and cylindrical grooves are made in the guide holes of the support base at a certain height. Further, each fixing section is placed opposite the cylindrical grooves made in the corresponding guide hole of the support base and a working fluid, such as hydraulic oil, is supplied inside its sealed cavity under high pressure, after which, when the metal yield point is reached, the wall of the fixing section is deformed and pressed into the annular grooves , made in the guide hole of the support base, due to which the support base is rigidly fixed on the pile, excluding the possibility of vertical movements along its axis.

To implement the method, a special design of a pipe composite steel pile is used, which consists of separate sections, which are pipe sections that are sequentially connected to each other, for example, by welding, during pile driving, and the last fixing section differs from other sections in that that a sealed cavity is formed inside it, formed by two partitions (steel plates) welded with a continuous seam to its wall and located at a certain distance from each other, and the thickness of these partitions exceeds the wall thickness of the pile section, due to which, when supplying the working fluid under pressure into the sealed cavity of the fixing section, its wall is deformed mainly in the radial direction, since its strength (due to the difference in the thicknesses of the wall and partitions) in the radial direction is less than in the axial direction.

In addition, to supply the working fluid, for example, hydraulic oil under pressure, into the formed sealed cavity, as well as to bleed air from it, fittings are installed in one of the partitions.

Also, to make the connection of the partitions with the section wall more rigid, the connection points can be reinforced with additional reinforcing structural elements, such as knits, jibs, stiffeners and others.

Also, by using an additional reinforcing structural element, such as, for example, a rod or pipe, connecting both partitions, an even greater structural strength of the fixing section can be provided in its axial direction.

Thus, due to the use of a pipe composite steel pile, consisting of separate sections, sequentially connected to each other in the process of driving the pile into the ground, the need for the use of high-capacity lifting and transport equipment, which is usually used for lifting and installing solid piles, is eliminated.

In addition, this method of sectional driving of pipe composite steel piles significantly reduces the requirements for the technical support of the process and the capacity of the pile driving unit, which can be installed directly on the support base of an offshore stationary structure, for example, on the caisson of an offshore platform.

The inventive method of securing the support foundations of offshore structures on the pile field and the construction of a pipe composite steel pile are illustrated by images:

FIG. 1 shows the support base of an offshore stationary structure (caisson) with a pile-driving installation installed on it;

FIG. 2 shows the structure of the fixing section of a pipe composite steel pile;

FIG. 3 shows the pilot hole of the support base of the offshore stationary structure with the fixing section of the pipe composite steel pile installed in it;

FIG. 4 shows the stress-strain state that occurs in the fixing section of a pipe composite steel pile under the influence of the pressure of the working fluid.

To fix the support base 1 of the offshore stationary structure on the pile field (Fig. 1), which has guide holes 2 designed for guiding and driving piles, the support base is placed on the bottom, after which, through its guide holes 2, using the pile driver 3, the sections are alternately driven into pipe composite steel pile, and as the piles are immersed in the ground, they are successively attached (for example, welded) to each other, while the last fixing section of the pile (Fig. 2) differs from other sections in that an airtight cavity formed inside it is formed with the help of two partitions (steel plates) 4, welded with a continuous seam to its wall 5 at a certain distance from each other, and the thickness of the partitions 4 exceeds the thickness of the wall 5, due to which the structural strength of the fixing section in the axial direction is greater than in the radial direction, when this, in one of the two partitions 4, two fittings are installed: fitting 6, designed to supply work whose liquid into a sealed cavity under high pressure and a fitting 7, which serves to bleed air from it.

Additionally, to make the connection of partitions 4 with the wall of section 5 more rigid, the joints can also be reinforced using reinforcing structural elements, for example, using jibs 8, and by installing an additional reinforcing element such as a rod or pipe 9 connecting partition 4, an even greater strength of the fixing section of the pile in its axial direction can be provided.

The inventive method for securing the support foundations of offshore structures on a pile field is as follows.

Sections of piles, which are pipe sections, are pre-fabricated at the manufacturing plant and transported to the installation site of the support base 1 of the offshore stationary structure, where, using the pile driving unit 3, the sections of the composite pile are sequentially driven through the guide holes 2 made in the support base 1 and the connection (for example, welding) the sections together. At the same time, the last of the mounted sections is a fixing section and is structurally different from other sections in that an airtight cavity is formed inside it, formed by the wall of section 5 and two partitions 4.

In this case, in the guide holes 2 of the support base 1, cylindrical grooves 10 (Fig. 3) are made, intended for fixing the support base 1 on the pipe composite steel pile.

During the driving of the last fixing section of the composite steel pile, it is placed opposite the grooves 10 made in the guide hole 2 of the support base 1, after which the working fluid is supplied through the nozzle 6 using a high pressure pump to the inside of the sealed cavity formed in the fixing section of the pile. bleeding the air escaping through the nozzle 7. After that, the nozzle 7 is muffled and the working fluid continues to pump through the nozzle 6 into the sealed cavity. When the pressure of the working fluid exceeds the yield point of the material (steel) of the wall of the fixing section of the pile, it deforms (Fig. 4), since the strength of the fixing section of the pile in the radial direction is less than in the axial direction, due to the fact that the thickness of the partitions 5 exceeds the thickness walls. The pile wall material is pressed into the annular grooves 10 made in the corresponding guide hole 2 of the support base 1 and takes their shape, due to this, the support base 1 is fixed on the pipe composite steel pile, while eliminating the possibility of vertical displacements of the support base 1 along the axis of the pipe composite steel pile.

Thus, a technical result is achieved, which consists in simplifying the technology and increasing the reliability of fixing the support foundations of stationary offshore structures on steel pipe piles, as well as in increasing productivity during installation work, due to the lower cost of the equipment used and the relative simplicity of the pile installation technology, and also due to the low requirements for the technical support and capacity of the pile driving unit, which can be installed directly on the supporting base of the offshore stationary structure.

Claims (4)

1. A method of securing the support foundations of offshore structures on a pile field, including placing on the seabed of a support base with guide holes made in it, intended for the installation of piles, in which cylindrical grooves are made at a certain height, installation through the guide holes of the support base of pipe steel piles, characterized in that pipe steel piles, consisting of separate sections, are sequentially connected to each other during pile driving, while the last section of each pile, in which a sealed cavity is made in advance, is installed opposite the cylindrical grooves made in the corresponding guide hole of the support base, after that, a working fluid is supplied to the sealed cavity under pressure sufficient to overcome the yield point of the metal of the section wall, which, pressing into the circular cylindrical grooves, fixes the support base on the pile. 2. A pipe composite steel pile, consisting of interconnected sections, characterized in that a sealed cavity is made inside the last section, formed by two steel partitions welded to its wall at a certain distance from each other, and the thickness of the partitions exceeds the thickness of the section wall, and in one of the partitions there are fittings intended for supplying the working fluid under pressure into the sealed cavity and for bleeding air from it. 3. A pipe composite steel pile according to claim 2, characterized in that the joints of the partitions with the section wall are additionally connected by means of reinforcing structural elements. 4. A pipe composite steel pile according to claim 2, characterized in that the baffles are interconnected by means of a reinforcing structural element.

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