JPH059922A - Off-shore foundation structure construction method - Google Patents

Abstract

PURPOSE:To construct an off-shore foundation structure with an easy method and reduce construction period. CONSTITUTION:Frames 3 and 3' constituting a bridge pier is made in a dry dock and are taken in tow on the sea to the final installation place. Ballast material is poured from the base part of the frames 3 and 3' laid on the sea to erect the frames perpendicularly on the sea, and the lower ends are made to reach the sea bottom ground. After that, the tops of the frames 3 and 3' are drawn to each other to be connected, and the lower parts of the frames 3 and 3' are fixed to the sea bottom ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a structure installed in the ocean, for example, a basic structure such as a bridge or a sea berth.

[0002]

2. Description of the Related Art In recent years, in Japan, the number of cases of constructing bridges and sea berths in relatively deep water is increasing. For example, the Honshu-Shikoku Connecting Bridge, Bisan Seto Ohashi, which opened in 1988, made a large steel caisson that is the foundation of a shipyard, and floats it on the sea to the installation site.
A construction method was adopted in which, after sunk on a supporting ground at a water depth of 50 m, the top of the shortage was replenished on site.

A steel jacket type structure is used as a basic structure of the seaverse. This structure is constructed by transporting the jacket body, which is a three-dimensional truss produced by the factory, and installing it on the seabed, penetrating the inside of the pillars of the jacket, driving a pile into the ground, and erection and fixing a superstructure on the pile head. It

[0004]

However, in the installation work of the large caisson which is the foundation part of the bridge, since the bottom surface of the foundation is large, it is necessary to excavate and level the sea floor over a large area. In addition, the installation work of the jacket in the sea berth is inevitably expensive due to the work of placing the piles and the like for the work boat and the equipment. Further, since the construction period of the offshore structure is generally long, the structure is exposed to external force for a long period of time in an unstable state, and there is a drawback that temporary facilities around the protective work become large. ..

The present invention is intended to solve the above-mentioned problems, and an object thereof is to provide a method for constructing a marine foundation structure by assembling a supporting member constituting the marine foundation structure into a simple structure. To provide.

[0006]

In order to achieve the above-mentioned object, a method of constructing an offshore foundation structure according to the present invention comprises manufacturing a plurality of support members constituting a foundation of an offshore structure at a place other than an assembly place, This is towed to the final installation location, the lower end of the supporting member is set on the seabed, the tops of two or more supporting members are connected, and the lower end of each supporting member is fixed to the seabed. The problem is solved by doing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a construction method of a bridge pier will be described below as an example of a marine foundation structure with reference to FIG. Manufacture of pier member The frame 3 that constitutes the pier is manufactured in advance by dry dock. The frame 3 is constituted by a pair of truss-shaped frames 3 and 3'in the shape of a ladder in which a girder 3b is arranged between two pedestals 3a as shown in FIG. 2 (A). The size of each frame 3, 3'is determined depending on the water depth of the installed sea area, but the height of the pier can be within the range of several tens m to several hundred m.

For example, for a pier installed at a water depth of 100 m, a concrete pipe having an outer diameter of 10 m and a height of 120 m
m, top width 50 m, open leg width 100 m between pedestals. Further, inside the pedestal 3a, partition walls made of steel plates are provided at intervals of several meters to partition the interior, and a vacant chamber into which a ballast material is injected, which will be described later, and a pump for supplying and draining the ballast material are installed. It is configured so that it can be used as a room.

[0009] At the beginning of excavation of the seabed, the seabed of the portion where the frames 3, 3'are bottomed is excavated in advance and the level is adjusted (step). In addition, at this time, after investigating the ground bearing capacity of the seabed ground, if necessary, a precast concrete plate or the like is installed in the excavation hole 1, or underwater concrete is placed to form the seabed foundation 2 To create (process).

The towing frame 3 is towed from the dry dock, floated on the sea, and levitated to the sea area to be installed. In addition, when manufacturing with a small dry dock, even if the frame 3 is divided into multiple parts, it is towed out from the dry dock and joined on a calm ocean, and then towed to the final installation location. Good.

[0011] bottom landing of the frame first, we will inject the ballast material such as seawater from the base of the frame 3 lying offshore, is vertically upright frame 3 at sea (step). After that, water is further poured into the ballast material, and the bottom of the foundation 2 is formed as it is (step). The same operation is performed for the other frame 3 '.

Assembling the bridge pier Ballast material is added to each frame 3, 3 ', and the tops of both are gradually pulled. The pulling work will be performed using equipment such as a crane ship, tugboat and winch. At this time, the inclinations of the frames 3 and 3'and the attitude of the pier can be controlled by adjusting the water injection amount and the water injection speed. After that, the tops of the two frames 3 and 3'are joined with an appropriate metal fitting (step).

The inside of the excavation hole 1 in which the pedestal 3a of the fixed frame 3 or 3'of the pier is bottomed is backfilled with earth, sand cement, concrete 4 or the like, and the lower end of the pedestal 3a becomes the seabed ground. Fix (process).

Finally, a top plate 5 of a predetermined size is placed on the tops of the two frames 3, 3'protruding on the sea, and the height and posture of the piers are finally adjusted (step).

[0015] in the same manner as in the superstructure normal bridge construction methods, upper structure of the main tower, etc. 6
Is installed on the top plate 5 (step).

In the above embodiment, the pair of frames 3,
Although the bridge pier is configured with 3 ', the present invention may also be used as a supporting member for configuring the bridge pier using a hollow concrete or steel strut 7 as shown in FIG. 2 (B). it can. That is, a combination of the support column 7 and the frame 3 or a combination of a plurality of support columns 7 and 7'is possible. Further, it is possible to combine the frame 3 or the columns 7 to form a tower-shaped substructure 8 as shown in FIG. 2 (C).

[0017]

The method of constructing a marine foundation structure of the present invention comprises:
Since the supporting member is composed of the columns having a simple structure, the structure can be constructed by an extremely simple method.
In addition, since all the supporting members can be manufactured in the dry dock, the construction period can be shortened and quality control can be performed well, as compared with the conventional method in which many offshore operations are performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the order of assembling and constructing a pier.

FIG. 2 is a diagram showing a modified example of a support member that constitutes a pier.

[Explanation of symbols]

 1 drill hole 2 seabed foundation 3, 3'frame 4 backfill 5 top plate 6 superstructure

Claims (1)

Claims: 1. A plurality of support members that form the foundation of an offshore structure are manufactured at a place other than the assembly site, and these are towed to the final installation site, and the lower end of the support members is at the bottom of the seabed. A method for constructing a marine foundation structure, comprising the steps of connecting the tops of two or more support members to each other and fixing the bottom ends of the support members to the seabed ground after the bottoms are attached to the bottom.