JPH042131B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention is mainly applicable to large buildings built on offshore artificial islands, especially when underground structures under water are subject to enormous buoyancy due to ever-changing tide levels, and there is a danger that they may eventually float to the surface. This refers to construction methods that are implemented in such a location that the buoyancy of the building is not used, and more specifically, to the construction method that is used to avoid using the buoyancy of the building. Concerning construction methods for building buildings.

Conventional technology (1) Conventionally, soft submarine ground was improved using the so-called deep mixing method, in which cement slurry made from cement-based materials was injected into the soil, kneaded, and hardened, and large gravity-type structures were constructed on top of this improved ground. For example, the technology for constructing the
No. 146909, Japanese Unexamined Patent Application Publication No. 172909/1983, etc., and are publicly known.

(2) In the same way, the soft submarine ground will be improved, an offshore artificial island will be built on top of this improved ground by natural dumping of fill soil carried by an earth carrier, and structures will be built on top of this artificial island. Technology, for example,
It is described in Japanese Patent No. 60-230418 and belongs to the public domain.

Problems to be solved by the present invention () As stated in (1) above, when a large structure (building) is simply constructed on improved ground,
This structure is subject to enormous buoyancy due to the ever-changing tide level. In particular, if the underwater structure (or underground structure) is large, the buoyant force will be greater than the weight of the underground structure, and there is even a danger that the structure will float to the surface.

In this way, more or less buoyant forces work,
When a structure is placed in a soft rounding state where the installation pressure against the improved ground is small, the following problems occur especially during an earthquake.

That is, because the installation pressure of the structure is low, the structure causes horizontal sliding in the event of an earthquake, which in turn causes shear failure of the surrounding reclaimed soil (artificial island), and the disaster extends to the surrounding area. In addition, the sliding structure
If the degree of destruction of the artificial island's ground is severe, it is predicted that it will tilt, resulting in damage to equipment and danger to human life.

() As stated in (2) above, when an artificial island is constructed on improved ground and a structure is constructed on this artificial island, firstly, the structure is constructed by natural dumping of fill soil. Offshore artificial islands are made of loose soil and there is a risk of liquefaction, so it is not possible to be sure of the stability and safety of the structure as it is.

Therefore, large structures are naturally constructed on improved ground that has sufficient bearing capacity, but in doing so, the structures cannot escape being subjected to the enormous buoyant force mentioned in (1) above. .

Means for Solving the Problems As a means for solving the problems of the prior art described above, the building construction method that does not use buoyancy according to the present invention is a preferred embodiment shown in FIGS. 1 to 6 of the drawings. As shown, the steps include: constructing a predetermined area of the soft underwater ground 1 on improved ground 2 with good water-stop properties, and building an artificial island 4 on the improved ground 2 to a height that protrudes above the water surface. Regarding the artificial island 4, a step of constructing a second improved ground 5 having good water-stop properties that surrounds the outer periphery of the building 3 in a ring shape up to a portion (depth) where it reaches and integrates the improved ground 2 at the bottom of the water; 2nd improved ground 5
The present invention is characterized by comprising the steps of excavating a portion 10 surrounded by 10 to the improved ground 2 at the bottom of the water, and constructing a building 3 within the excavated portion 6.

Function: The improved ground 2 at the bottom of the water not only has good water-stopping properties, but also has considerable pressure resistance itself, and there is no risk of forming a lumpy solid and liquefying it. This improved ground 2 exhibits a sufficiently large supporting force against the vertical load of the building 3 built on it, and serves as a stable support. A second improved ground 5 constructed on the artificial island 4 constructed on the improved ground 2
serves as a reinforcing ring that integrates and reinforces the artificial island 4 formed of loosely deposited earth and sand with the improved ground 2 at the bottom of the water, and also provides a drilled hole 6 that is completely insulated from the water depth around the outer periphery of the artificial island 4. I will provide a. Therefore, the building 3 built inside this borehole 6 is also completely insulated from the water depth around the artificial island 4, and has exactly the same location conditions as a building built on land, so to speak. Buoyancy does not work on Building 3. Therefore, the installation pressure of the building 3 against the improved ground 2 is the weight of the building itself and is extremely large, so the building 3 will not cause horizontal sliding during an earthquake.

The ground surface of the artificial island 4 provides utility space for residents.

Example Next, the embodiment shown in the drawings will be explained.

Figures 1 to 4 show important process diagrams for first constructing an artificial island 4 on the improved ground 2 at the bottom of the water, and then constructing a building 3.

FIG. 1 shows that a predetermined area of soft underwater ground 1, that is, a fairly large area including the area where a building 3 will be constructed later, is injected with cement slurry made of cement-based material into the soil by a work boat 8 on the sea. This shows the stage where the improved ground 2 has been constructed using the so-called deep mixing method of kneading and hardening, and the improved ground 2 is formed as a blocky solid with good water-stopping properties. This improved ground 2 has an excellent water-stopping effect as shown in the graph of FIG. 5A. Moreover, it exhibits strength as shown in the graph of FIG. 5B.

FIG. 2 shows a stage in which an offshore artificial island 4 has been constructed to a height that projects above the sea surface W by naturally dropping fill soil carried by a sea-borne soil carrier onto the improved ground 2 on the water bottom. ing. Therefore,
This artificial island 4 is formed of loosely deposited earth and sand.

FIG. 3 shows a second improvement in which a working machine 9 is installed on the artificial island 4, and the size and shape of the building 3 to be constructed are encircled in a ring shape using the deep mixing method and have good water-stop properties. This shows the stage in which the ground 5 is constructed to the point (depth) where it reaches the improved ground 2 at the water bottom and is integrated with it. Therefore, the upper and lower improved grounds 2 and 5 with good water-stopping properties are ultimately formed integrally from the bottom of the water to above the water surface, and the artificial island 4 formed of loosely deposited earth and sand as described above is the second
It will be reinforced with improved ground 5.

Fig. 4 shows that a portion 10 (Fig. 3) surrounded by the second improved ground 5 was excavated to the improved ground 2 at the bottom of the water, and a building 3 was constructed on the improved ground 2 in the excavated hole 6. It shows the stages. The gap between the building 3 and the second improved ground 5 is filled with grout 11. Further, the water that had previously entered the drilled hole 6 is discharged to the outside by the pump 12.

Thus, the building 3 is constructed to stand directly on the improved ground 2 at the bottom of the water. Although the underground structure is deep and huge beneath the water surface, it is completely insulated from the surrounding seawater by the improved ground 2 and 5 with good waterproof properties, so it is not affected by any buoyancy.

Therefore, this building 3 can bend its own weight and transfer it to the improved ground 2, has a large installation pressure, and has no risk of sliding.

Other Embodiments FIG. 6 shows another method of constructing the improved ground 2 on the water bottom, in which sheet piles 10 are first driven to surround a predetermined area of the water bottom 1 to form an enclosing wall, and an earth transport vessel 12 on the sea The buried soil 11 carried by the above is put into the enclosure wall to form a seabed mound higher than the underwater ground 1, and this is constructed on the improved ground in the same manner as shown in Fig. 2. It is also possible to implement a construction method in which an artificial island protruding above the water surface is constructed on the submarine mound thus constructed, a ring-shaped second improved ground is constructed on this artificial island, and a building is constructed by excavating the inside.

As explained in the above embodiments, this invention can also be used not only when constructing artificial islands and buildings underwater (in the ocean or offshore), but also when constructing large buildings with deep underground parts on ground with a high groundwater level. can also be implemented effectively.

Effects of the present invention According to the method of constructing a building that does not exert buoyancy according to the present invention, the building 3 is built on the strong improved ground 2 and is extremely stable, and the building 3 has no buoyancy at all. Since the weight of the building is directly transferred to the improved ground 2, the installation pressure is extremely high, and an extremely safe building with no risk of horizontal sliding during an earthquake can be provided.

[Brief explanation of drawings]

Figures 1 to 4 are important process diagrams of the construction method according to the embodiment of this invention, Figures 5A and B are graphs showing an example of water-stopping properties and strength of improved soil, and Figure 6 is a diagram of different improved soils. It is a sectional view showing a construction method.

Claims (1)

[Claims] 1. A step of constructing a predetermined area of the soft underwater ground 1 on improved ground 2 with good water-stop properties, a step of constructing an artificial island 4 on the improved ground 2 to a height that projects above the water surface, and a step of constructing the artificial island 4 on the improved ground 2 to a height that protrudes above the water surface. Regarding the step of constructing a second improved ground 5 with good water-stop properties in a ring shape surrounding the outer periphery of the building 3 up to the part where it reaches and integrates the improved ground 2 at the bottom of the water, and the stage where the second improved ground 5 surrounded by the second improved ground 5 is A building construction method that does not use buoyancy, comprising the steps of excavating a portion 10 to the improved ground 2 at the bottom of the water, and constructing a building 3 on the improved ground 2 in the excavated part 6. .