KR20170030985A

KR20170030985A - Subsea concrete caisson foundation structure and Method for installing the same

Info

Publication number: KR20170030985A
Application number: KR1020150128600A
Authority: KR
Inventors: 박종식; 원종화; 강효동; 류민철
Original assignee: 대우조선해양 주식회사
Priority date: 2015-09-10
Filing date: 2015-09-10
Publication date: 2017-03-20

Abstract

According to an aspect of the present invention, there is provided a concrete caisson foundation structure installed on a seabed ground, comprising: a caisson (20) formed of concrete; A drilling means (30) rotatably supporting a base (31) on a bottom surface of the caisson (20) and having a plurality of cutters (33) on a base (31); And a drive motor (40) attached and detached to apply a rotational force to the base (31) of the excavating means (30).
Accordingly, it is possible to facilitate stable excavation construction and stable support of the structure load in performing a large scale underwater foundation work for an offshore plant in a large water depth condition.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a subsea concrete caisson foundation structure,

The present invention relates to the support of a submarine plant structure, and more particularly, to a submarine concrete caisson foundation structure for performing a foundation work for supporting an offshore plant and a construction method thereof.

Generally, a suction pile is installed considering the ease of operation when the foundation structure is installed at the bottom of the water depth of thousands of meters. In consideration of the workability in the case where the strength of the subsoil layer is large at the low water depth condition, (driven pile). Suction files are advantageous in large water depth conditions, and type files are advantageous in large seafloor strength.

However, considering the water depth condition and the ground condition of the seabed, the suction structure and the type file as foundation structures may not always satisfy the structural stability and economical efficiency.

As related prior art documents, Korean Patent Publication No. 2010-0074479 (Prior Art 1) and Korean Patent Registration No. 1546231 (Prior Art 2) can be referred to.

In the prior art document 1, a concrete caisson-type concrete product is installed and assembled by using a plurality of sea caissons and corner caissons on the sea floor, and the inside thereof is dredged up to the top of weathered rock by using a crumbshell bucket. So that the assembled caisson and the iron jacket are integrated. Therefore, it is expected to prevent the scouring phenomenon and flooding caused by the currents, and to prevent the uneven settlement requirements in soft grounds in advance.

Prior Art 2 is a method for manufacturing a core tube, comprising the steps of: bonding a bit saw to a tip of a core tube; Connecting and drilling the core tube to a boring drilling rig; Removing the core tube and then drilling the steel pipe pile to a planned depth; And injecting the mortar into the interior of the steel pipe pile. Therefore, it is expected that the pumping speed is improved, there is no loosening of the surrounding ground, the excavation diameter is secured, and the stability of the work barge line can be secured.

However, according to the method of dredging using the bucket in the above-mentioned prior art 1 or the method of removing the core tube in the prior art 2, it is not suitable to be used as a purpose of performing large-scale underwater foundation work for an offshore plant in a large water depth condition.

1. Korean Laid-Open Patent Publication No. 2010-0074479 entitled " Field cast pile using an assembled caisson "(Open date: Feb. 10, 2012) 2. Korean Patent Registration No. 1546231 entitled " Method of constructing self-drilling marine eco-friendly pile "(Open date: Aug. 20, 2015).

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned problems of the prior art, and it is an object of the present invention to provide an excavation system for a large- scale offshore underwater foundation, And a method of constructing the same.

In order to achieve the above object, according to one aspect of the present invention, there is provided a concrete caisson foundation structure installed on a seabed ground, comprising: a caisson formed of concrete; Excavating means rotatably supporting the base on the bottom surface of the caisson and having a plurality of cutters on the base; And a driving motor attached to and detached from the base of the excavating means to apply a rotational force thereto.

As a detailed configuration of the present invention, the base of the excavation means is provided with a coupling on a rotary shaft for detachably engaging with the drive motor.

In a detailed configuration of the present invention, the cutter of the excavating means is formed of a concrete material and is radially disposed on the base.

As a detailed construction of the present invention, a bearing of a metal material is provided between the caisson and the excavating means.

According to another aspect of the present invention, there is provided a method for constructing a concrete caisson foundation structure according to claim 1, comprising the steps of: (a) lowering a caisson to a submarine ground in a state where the excavating means is engaged; (b) connecting a drive motor to the caisson and actuating the excavation means to pivot it to the seabed; And (c) separating the driving motor from the caisson and injecting a filler into the caisson.

In the detailed construction of the present invention, the step (a) further comprises adding Teflon resin to the surface of the caisson and the excavating means, which is in contact with the bearing.

As a detailed configuration of the present invention, the steps (b) and (c) are characterized in that the unmanned submersible is used in the process of attaching and detaching the drive motor.

As described above, according to the present invention, it is possible to facilitate stable excavation construction and stable support of the structural load in performing a large-scale underwater foundation work for an offshore plant in a large water depth condition.

In addition, there is an effect of solving the difficulty of installing a suction file on the ground having a large strength of the seabed strata and the difficulty of installing a type file on the seabed ground by using a large seam line under a large water depth condition.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing a caisson foundation structure according to the present invention;
2 is a schematic view showing a digging means of a foundation structure according to the present invention;
3 and 4 are schematic views showing a method of constructing using a foundation structure according to the present invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

According to one aspect of the present invention, a concrete caisson foundation structure installed on a seabed ground is proposed. Particularly, the present invention is not limited to large-scale undersea and underground conditions in relation to large-scale offshore underwater foundation work.

According to the present invention, the caisson 20 is formed of concrete. The caisson 20 is a cylinder structure having a circular cross section whose upper surface is opened, and is formed as a PC structure using concrete on land. The physical properties of the concrete forming the caisson 20 can be set differently depending on the depth of the seabed ground 10 and the topography.

According to the present invention, the excavating means 30 rotatably supports the base 31 on the bottom surface of the caisson 20, and has a plurality of cutters 33 on the base 31. The excavating means 30 acts as a boring tool of the boring machine so as to be brought into contact with the underside ground 10 and to be pivoted. The base 31 is formed of the same material as the caisson 20 as a circular plate having the same diameter as the caisson 20. The cutter 33 is installed on one side of the base 31 and performs excavation on the seabed ground 10. The base 31 is rotatably coupled to the bottom surface of the caisson 20 via a rotation shaft.

The base 31 of the excavating means 30 is provided with a coupling 35 on the rotary shaft for detachably engaging with the drive motor 40. [ A coupling 35 for shaft coupling is provided at the upper end of the rotating shaft provided at the center of the base 31. The coupling 35 is a part that is detachably coupled to the drive shaft 45 of the drive motor 40 to be described later. The coupling 35 is not limited to a specific known shaft coupling, but a method of easily attaching and detaching it in water is preferred.

As a detailed configuration of the present invention, the cutter 33 of the excavating means 30 is formed of a concrete material and is radially disposed on the base 31. [ If the strata are fragile, the cutter 33 can be a simple disk form, and the greater the strength of the stratum, the more the cutter 33 is shaped like a tool of the TBM. In either case, the cutter 33 uses concrete having strength and abrasion resistance equal to or higher than that of the base 31. The base 31 of the excavating means 30 and the cutter 33 are buried together with the caisson 20 and thus the structure is not required to be replaced. In addition, the cutter 33 may have a high strength tip (not shown) at its end.

As a detailed construction of the present invention, a bearing (22) of metallic material is provided between the caisson (20) and the excavating means (30). The bearing 22 reduces frictional forces by which the base 31 of the excavating means 30 is rotated, thereby shortening the working time and reducing power consumption. The bearing 22 can be formed of a spherical or disc-shaped unit using a non-metallic material which is not likely to be rubbed. It is preferable that a plurality of unit pieces of the bearing 22 are interlaced via separate rotation shafts (not shown). The unit can support the load between the caisson 20 and the excavating means 30 even if the rotary shaft is blown out after the installation.

According to the present invention, the drive motor 40 is attached to and detached from the base 31 of the excavating means 30 so as to apply a rotational force thereto. The drive motor 40 has a power supply and control wire 42 on the upper side and a drive shaft 45 for power transmission on the lower side. The electric wire 42 is connected to the barge on the upper side and the drive shaft 45 is connected to the coupling 35 on the lower side. Rotation control of the excavating means 30 via the drive motor 40 is performed in the barge.

According to another aspect of the present invention, a method for constructing the concrete caisson foundation structure of claim 1 is proposed. A caisson foundation structure is constructed on the seabed ground (10) by using a barge equipped with a crane.

The step (a) according to the present invention proceeds to a step of lowering the caisson 20 to the seabed ground 10 while the excavating means 30 is engaged. A base structure combining the caisson 20 and the excavating means 30 on the land is formed and mounted on a barge to move to the sea of installation object. Thereafter, the towing line 12 of the crane is fixed to the lug 24 of the caisson 20 and is launched into water and dropped to the seabed ground 10.

The step (a) of the present invention is characterized by further adding Teflon resin to the surface of the caisson 20 and the excavating means 30 which is in contact with the bearing 22. When the ground layer 10 of the seabed ground 10 is high in strength, a large frictional force acts, so it is preferable to adhere the Teflon resin. Teflon resin reduces the rolling resistance of the bearing (22), thereby shortening the working time and reducing power consumption.

The step (b) according to the present invention is carried out by connecting the drive motor 40 to the caisson 20 and actuating the excavating means 30 to pivot it to the seabed ground 10. The drive motor 40 is connected to the traction line 12 and gradually lowered to the upper surface of the caisson 20 reaching the seabed ground 10 to couple the drive shaft 45 to the coupling 35. 3 and 4, when the power is applied to the drive motor 40, the excavating means 30 rotates and is pivoted downward, and the caisson 20 connected to the excavating means 30 also moves down. Fig. 3 mainly illustrates the operation principle of the foundation structure, and Fig. 4 mainly illustrates the foundation structure construction state.

The step (c) according to the present invention proceeds to a process of separating the driving motor 40 from the caisson 20 and injecting the filler 26 into the caisson 20. When the foundation structure is pushed to the set depth, the drive motor 40 is stopped and the drive shaft 45 is separated from the coupling 35. The separated drive shaft 45 is loaded onto the barge using the traction line 12 and the tube 16 is lowered to the upper surface of the caisson 20 to inject the filler 26. The filling material 26 is a weight such as gravel and may be added in a mortar form.

In the detailed construction of the present invention, the steps (b) and (c) are characterized in that the unmanned submersible 14 is used in the process of attaching / detaching the drive motor 40. The unmanned submersible 14 transfers the process of coupling and separating the drive shaft 45 to the coupling 35 to the control room of the barge. In addition, it is also possible to acquire and transmit information of the whole process of construction. If the robot function is added to the unmanned submersible 14, connection / disconnection operations can be performed.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It is therefore intended that such variations and modifications fall within the scope of the appended claims.

10: Submarine ground 12: Traction line
14: unmanned submersible 16: tube
20: Caisson 22: Bearings
24: Lug 26: Filler
30: Excavation means 31: Base
33: Cutter 35: Coupling
40: drive motor 42:
45:

Claims

A concrete caisson foundation structure installed on a seabed ground, comprising:
A caisson formed of concrete;
Excavating means rotatably supporting the base on the bottom surface of the caisson and having a plurality of cutters on the base; And
And a driving motor attached to and detached from the base of the excavating means to apply a rotational force to the base of the excavating means.

The method according to claim 1,
Wherein the base of the excavating means is provided with a coupling on a rotating shaft for detachably engaging with a drive motor.

The method according to claim 1,
Wherein the cutter of the excavating means is formed of a concrete material and radially disposed on the base.

The method according to claim 1,
And a bearing of a metallic material is provided between the caisson and the excavating means.

A method of constructing a concrete caisson substructure of claim 1, the method comprising:
(a) lowering the caisson with the excavating means coupled to the seabed ground;
(b) connecting a drive motor to the caisson and actuating the excavation means to pivot it to the seabed; And
(c) separating the drive motor from the caisson and injecting a filler into the caisson.

The method of claim 5,
Wherein the step (a) further comprises adding Teflon resin to the surface of the caisson and the excavating means that is in contact with the bearing.

The method of claim 5,
Wherein the step (b) and the step (c) utilize an unmanned submersible in the process of attaching and detaching the drive motor.