JPS6256291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a prefabricated caisson construction method suitable for constructing a pier foundation for a bridge, for example.

Conventionally, a commonly used method for constructing pier foundations for bridges and the like is a caisson construction method using steel sheet piles or steel pipe piles.

In this type of construction method, the above-mentioned steel sheet piles or steel pipe piles are driven in a ring shape at the planned pier foundation site to construct a caisson of a specified diameter, and a specified amount of foundation construction material (chestnut stone, concrete, etc.) is placed inside the caisson. The purpose is to construct a pier foundation by pouring and compacting the concrete.

The conventional construction method described above has a structure in which the caisson itself is surrounded by steel sheet piles or steel pipe piles, so a large force (action) acts on the joints between each member, and there are few that can withstand this force, and corrosion is a problem. Problems persist.

This invention was made in view of the above circumstances, and its purpose is to mount caisson construction members such as concrete segments or hollow segments on a plurality of auxiliary floats, and to place each caisson construction member on the auxiliary float. The preceding caisson construction ring is tightened into a ring shape with prestress wires (hereinafter referred to as P and C wires) and then suspended into the sea, and the subsequent caisson construction ring to be constructed next is suspended into the sea. It is an object of the present invention to provide a prefabricated caisson construction method for obtaining a prefabricated caisson of a predetermined height by connecting and stacking the caisson on the top via a coupler.

An embodiment of the present invention will be described in detail below based on the drawings.

FIG. 1a is a perspective view showing the offshore work procedure of the construction method according to the present invention. In the figure, 1... is an auxiliary float (offshore work boat), and on top of this auxiliary float 1, a concrete segment 2... and a hollow segment 3... are mounted and connected in a ring shape (Fig. 1 b reference). Concrete segment 2...
The connection between the concrete segment 2 and the hollow segment 3 is shown in the figure.
This is done by tightening the P and C wires 4 (indicated by dotted lines in the figure) that are introduced through the... The caisson members 5 (one ring) connected in a ring shape are submerged into the sea while water is poured into each of the auxiliary floats 1 .

As described above, the caisson members 5 which are sequentially connected and integrated on the auxiliary float 1 are connected to the couplers 6...
The caissons 7 are connected vertically by ... and assembled as shown in Fig. 2, and are sunk into the seabed as a caisson 7.

By the way, in the above embodiment, the two hollow segments 3, 3 are incorporated on the right side of the caisson 7 to form an integrated caisson 7. However, this is because the foundation on the seabed is weak on the right side and the caisson 7 is to be sunk vertically. This shows the construction method that is used when it is impossible to maintain a sufficiently level surface even after sinking to a predetermined position using a hydraulic jet.

In general, when constructing bridge piers, etc., submarine foundations (topography,
Construction will begin only after a thorough geological investigation has been carried out through trial boring and other methods. Therefore, the degree of weakness at the submerged position of the caisson 7 can be clearly seen, and in order to cope with this, the above-mentioned hollow segments 3, 3 are installed. And the caisson 7 incorporating the hollow segments 3, 3 is the third
As shown in the figure, the caisson 7 is installed on the seabed foundation, and steel pipe piles 9 are driven from the sea into the hollow parts 8, 8 of each hollow segment 3, 3 to improve the bearing capacity of the soft seabed foundation. A horizontal installation is carried out. In addition, steel pipe piles 9 and other prescribed concrete 10 are also placed in the hollow parts 8, 8 of the hollow segments 3, 3, which improves the bearing capacity of the submarine foundation and at the same time strengthens the entire caisson 7 in the vertical direction. Integration is also being promoted.

Next, the construction procedure will be explained using the above configuration.

Multiple auxiliary floats 1 floating on the ocean...
The work of loading concrete segments 2 or hollow segments 3 onto the top is done sequentially starting from the carrier ship.
Ring-shaped tightening of each caisson member 5 by the P and C wires 4 is performed on the auxiliary floats 1 . The caisson members 5 of each stage tightened in a ring shape in this way are sequentially attached to the auxiliary floats 1...
The caisson member 5 is submerged while being poured with water, and even in this state, it is connected to the next caisson member 5 by the coupler 6,
This process is repeated until the lowermost caisson member 5 is seated at a predetermined position on the seabed. Through the above operations, the caisson 7 is constructed until the uppermost caisson member 5 is exposed at sea as shown in Fig. 3, and then steel pipe piles 9 are installed in the soft layer in order to keep the soil bearing capacity of the entire caisson 7 constant. Pouring work and pouring a predetermined amount of concrete 1 into the hollow parts 8 of the hollow segments 3, 3
A pour of 0 is made.

In the above embodiment, a cylindrical caisson 7 is constructed and two hollow segments 3 are installed on the right side of the caisson 7. However, the shape of the caisson 7 or the hollow segment The number of 3 and 3 is not particularly limited to the above embodiment.

As explained above, this invention has a caisson member for each ring mounted on a plurality of auxiliary floats,
This was tightened with P and C wires to form a ring shape, and then submerged in the sea one after another, connecting the upper and lower caisson members with couplers to construct a caisson with a predetermined height. Compared to the caisson construction method, which was constructed by driving sheet piles or steel pipe piles, the work is much faster, and there is no need to install large working machines such as driving machines offshore.
In addition, since the entire caisson is constructed using corrosion-resistant members such as concrete segments or hollow segments, it is cheaper than conventional caissons made of steel sheet piles or steel pipe piles.
Moreover, it becomes possible to obtain a caisson with excellent strength. In addition, hollow segments are incorporated in appropriate positions of the caisson members, so for example, when the caisson is being erected, it is difficult to hold the caisson horizontally due to large irregularities in the seabed foundation or soft ground in some areas. In such cases, by placing steel pipe piles and concrete in the hollow part of the hollow segment, it is possible to eliminate the influence of the unevenness and improve the bearing capacity of the soft ground, making the caisson extremely stable. It has various excellent industrial effects such as:

[Brief explanation of the drawing]

Figures 1a and 1b are perspective views and schematic side views for explaining the prefabricated caisson construction method according to the present invention, Figure 2 is a perspective view of the assembled caisson, and Figure 3 is a longitudinal cross-section of the caisson. It is a front view. 1... Auxiliary float, 2... Concrete segment, 3... Hollow segment, 4... P, C
Wire, 5...Caisson member, 6...Coupler, 7...Caisson, 11...Pontoon, 12
……crane.

Claims (1)

[Claims] 1 Concrete segments and hollow segments are mounted in a circular shape on a plurality of auxiliary floats, which are tightened into a ring shape by introducing prestress wire to form a caisson member, and then the caisson member is placed in the sea. At the same time, the following segments are mounted on each of the auxiliary floats, and a ring-shaped caisson member is constructed using prestressed wire as described above, and the latter caisson member and the former caisson member are connected via a coupler. The feature is that the caissons are stacked vertically and stacked at a predetermined height and are sunk to a predetermined depth, and in areas where the ground is weak, piles are driven into hollow segments and the gaps are filled with concrete to achieve integration. A prefabricated caisson construction method.