JP2536108B2 - Foundation construction method for offshore structures - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for constructing the foundation of a structure such as a skyscraper on the ocean.

[Conventional technology]

Conventionally, when constructing a structure such as a building on the ocean, first, after constructing a revetment, the inside of the revetment is filled up with earth and sand to construct a ground, and it is necessary to construct a foundation. For skyscrapers,
First, after constructing a retaining wall with sheet piles, column walls, or continuous underground walls, etc., excavating the inside to the supporting ground and constructing the foundation directly on this supporting ground, or supporting ground on the reclaimed ground. There is a method of placing piles that reach up to and constructing them while supporting them with these support piles.

[Problems to be Solved by the Invention]

However, land reclamation generally takes about 10 years, ground subsidence continues for a long time even after the land reclamation is constructed, and it causes damage to the joint between the constructed building and the ground or piping in the ground. Often. Further, when an earthquake occurs, so-called liquefaction phenomenon is likely to occur in the landfill ground, which adversely affects the bearing strength of the building constructed there. Moreover, landfilling has inevitably caused problems such as environmental pollution.

[Object of the Invention]

The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to construct a foundation such as a skyscraper on the ocean in a short construction period without resorting to landfill.

[Means for solving the problem]

A method for constructing a foundation of an offshore structure according to the present invention is shown in FIG.
As shown in FIG. 8, a process of constructing an open caisson 2 in a dock, attaching an upper lid 3 to the upper part of the caisson, adjusting the internal air pressure to levitate the caisson 2, and pulling it out at sea. The process of joining a plurality of caisson 2 into a predetermined shape and sunk in a predetermined position. While removing the upper lid 3 from the caisson assembly 5,
A step of excavating the inside while adding a skeleton concrete 6 to the upper part of the caisson aggregate 5 and submerging the caisson aggregate 5 up to a support ground 9 having a bearing capacity necessary for supporting the structure 8. Step of placing bottom concrete 10 on the bottom of caisson assembly 5. A process of constructing a structure 8 on the upper part of the caisson assembly 5 and parallelly constructing the structure 8 inside the caisson assembly 5. The above-mentioned steps (1) to (4) are included, and the above-mentioned object is achieved by such a configuration.

[Work]

A caisson assembly 5 having a predetermined shape and size is manufactured from the plurality of caissons 2.

Next, the caisson aggregate 5 is excavated inside while adding the skeleton concrete 6 to the upper part, and is safely laid down to the support ground 9 without damaging the skeleton, and the skeleton assembly 5 and the bottom ground constructed after the digging support the ground foundation 9 Is surely supported by.

A beam (partition wall 1) in the body of such a caisson assembly 5
The structure 8 is constructed on the upper part of the caisson assembly 5 while ensuring sufficient support strength corresponding to the degree of progress of the construction.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

First, as shown in FIG. 1, after constructing an open caisson (hereinafter simply referred to as “caisson”) 2 having a partition wall 1 whose body part is made of steel shell or concrete in a short shape in a dock not shown, As shown in Figure 2, caisson 2
The upper lid 3 is detachably attached to the top end of the caisson, and the air chamber A is provided above the caisson.
Levitate and pull out from inside the dog by towing.

When the caisson 2 is constructed, the joining means 4 capable of joining the caisson 2 to each other is attached.

Then, as shown in FIG. 3, the caisson 2 is floated over the sea and joined to a predetermined shape by using the joining means 4, and then the caisson assembly 5 is further fixed to a predetermined shape as shown in FIG. Move it to the position or sunk in the same position. Although not shown, it is needless to say that the caisson 2 may be successively sunk and joined, and then the caisson assembly 5 may be left at the same position or re-floated and further moved to a predetermined position before being sunk.

The caisson 2 or the caisson assembly 5 is gradually deposited while being stabilized by adjusting the internal air pressure of each air chamber A defined by the partition wall 1.

As shown in FIG. 5, after the caisson assembly 5 is sunk, the upper lid 3 is removed, and the inside of the caisson assembly 5 is excavated by an excavator 7 while adding a skeleton concrete 6 to the upper part of the caisson assembly 5,
The caisson assembly 5 is laid down to the support ground 9 having the bearing capacity required to support the structure 8. If the caisson assembly 5 is not sufficiently supported during excavation up to the support ground 9, the upper lid 3 should be removed while reaching the support ground 9 where a supporting force is obtained while excavating using the air jet or the like. The caisson assembly 5 is stabilized by gradually adjusting the internal air pressure of each air chamber A without removing it. If the upper cover 3 is lowered too much due to the digging due to the excavation, the upper cover 3 is pulled up and reinstalled for use. Then, when reaching the supporting ground 9, the upper lid 3 is removed, and the excavation and the digging are performed.

As shown in FIG. 6, when the caisson aggregate 5 is lowered to a predetermined depth of the support ground, a bottom concrete 10 is placed at the bottom of the caisson aggregate 5 to perform tip filling.

Next, as shown in FIG. 7, a structure 8 such as a skyscraper is constructed using the beam (partition wall 1) in the caisson body of the caisson assembly 5. In parallel with this, caisson assembly 5
Advance internal construction. At the initial stage of construction, the weight of the caisson assembly 5 may be smaller than the buoyancy. In this case, the water inside the caisson assembly 5 is not completely discharged, but a part of the water is left behind to allow the structure 8 to stand up. As it rises, it drains from the caisson assembly 5 and constructs each.

As shown in FIG. 8, at the same time as the upper structure 8 is completed, the lower caisson assembly 5 is completed.

With the above configuration, generally, in large-scale bridge foundations, etc., short caissons with a side of 50 to 60 m are used, but as a foundation for offshore urban structures, at least one side 20
It should be about 0 m. Since it is difficult to manufacture such a large caisson at a time, the caisson is manufactured by dividing it into 4 to 8 blocks, and these caissons are joined together. As a method of manufacturing the caisson assembly, in the present invention, as described above, after the caisson 2 is constructed in the dock, the internal air pressure of the air chamber A provided on the upper part of the caisson via the upper lid 3 is adjusted to adjust the caisson 2. After being levitated and pulled out to the sea, a plurality of caissons 2 are joined to a predetermined shape by using a joining means 4, so that a caisson assembly 5 having a predetermined shape and size is manufactured as a basis of an offshore urban structure. To be done.

After the caisson assembly 5 is manufactured, the inside of the caisson assembly 5 is excavated while adding the skeleton concrete 6 to the upper part of the caisson assembly 5, and the caisson assembly 5 is laid down to the support ground 9 having the bearing capacity required to support the structure 8. Also in this case, the caisson assembly 5 is stabilized and gradually submerged by adjusting the internal air pressure of the air chamber A, so that the caisson assembly 5 suddenly sinks or is submerged without stopping at a predetermined position. There is no such thing, and the above-mentioned depositing work is surely performed.

When the caisson aggregate 5 is lowered to the predetermined depth of the support ground 9, the bottom concrete is attached to the bottom of the caisson aggregate 5.
Since 10 is cast, the body and bottom of the caisson assembly 5 are securely supported by the support ground 9.

Next, a structure 8 such as a skyscraper is constructed using the beam (partition wall 1) in the body of the caisson assembly 5, and in parallel with this, the construction inside the caisson assembly 5 is advanced. The foundation of the structure 8 can be constructed reasonably and efficiently while ensuring sufficient support strength corresponding to the progress of the construction of the structure 8.

〔The invention's effect〕

As described above, according to the present invention, a plurality of open caisson can be predetermined on the sea by effectively utilizing the offshore levitating and submerging method performed by adjusting the internal air pressure of the air chamber provided on the upper part of the caisson via the upper lid. After connecting it to the shape and installing it on the support ground, place bottom concrete on the bottom of this caisson aggregate to ensure that it is supported on the ground through the skeleton and bottom, and then the structure above the caisson aggregate. It is possible to build a foundation while building a building, while ensuring sufficient support strength corresponding to the building progress. Therefore, the foundation of the structure can be efficiently constructed on the ocean, the construction period can be greatly shortened, and the problems such as marine pollution and ground subsidence as in the past do not occur. Further, since the constructed foundation is a caisson assembled structure, it can be used, for example, as a large-section shield tunnel start / arrival base for traffic access.

[Brief description of drawings]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 5, FIG. 6, FIG. 7, and FIG. 8 are process drawings showing an embodiment of the present invention. 1 ... Bulkhead, 2 ... Open caisson, 3 ... Top lid, 4
...... Joining means, 5 …… Caison aggregate, 6 …… Skeletal concrete, 7 …… Excavator, 8 …… Structure, 9 …… Foundation,
10 ... bottom concrete.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location E02D 27/18 E02D 27/18 (72) Inventor Satoru Shishihara Moto-Akasaka 1-2-chome, Minato-ku, Tokyo No. 7 Kashima Construction Co., Ltd. (72) Inventor Tsutomu Nakao 1-2-7 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (56) Reference JP-A-59-34331 (JP, A) JP 53-80696 (JP, A) JP-A-56-20235 (JP, A)

Claims (1)

(57) [Claims] 1. A step of constructing an open caisson in a dock, adjusting the internal air pressure of an air chamber provided on the upper part of the caisson through an upper lid to levitate the caisson, and draw it out at sea. The process of joining a plurality of caisson into a predetermined shape and sunk at a predetermined position. While removing the upper lid from this caisson assembly, excavating the inside of the caisson assembly by adding a skeleton concrete to the upper part of the caisson assembly, and laying the caisson assembly up to the supporting ground having the bearing capacity necessary for supporting the structure. Process to do. The process of placing bottom concrete on the bottom of the caisson assembly. The process of constructing a structure on the upper part of the caisson assembly and parallel with this to construct the inside of the caisson assembly. A method for constructing a foundation for an offshore structure, which comprises the steps described above.