JPH0366454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a temporary cofferdam construction method using a continuous underground wall, and particularly relates to an improvement in a temporary cofferdam construction method applied when drying up the inside of a cofferdam.

<<Prior art>> As is well known, when constructing a structure such as a bridge pier footing in a river or the sea, a temporary cofferdam is formed in the water body, the water inside the cofferdam is drained to make it dry, and then it is placed on land. Construction work may be carried out under the same conditions.

As this type of temporary cofferdam, construction methods using steel sheet piles are widely adopted.

Temporary cofferdam construction methods using steel sheet piles are easy to construct and handle, but they do not provide sufficient resistance to external forces for sealing off large and deep bodies of water.

Therefore, a temporary cofferdam method has been proposed in which a water body is closed off with steel sheet piles, and filler soil is poured into the cofferdam, and a continuous wall made of concrete that reaches from the seabed ground to above the water surface is formed during the cofferdam construction. .

However, such a temporary cofferdam construction method using a continuous wall has the following problems, particularly when water in the cofferdam is drained and dried up.

≪Problems to be solved by the invention≫ In other words, when dry-up inside the temporary cofferdam,
Temporary cofferdams are affected by surrounding soil and water pressure, but
These external forces are quite large because temporary cofferdam work using continuous walls is applied to deep and large-scale construction work as described above. Therefore, in order to resist the external force applied to the temporary cofferdam during dry-up, it was necessary to increase the wall thickness of the continuous wall.

By the way, this type of temporary cofferdam is usually temporary equipment used to safely and quickly construct a construction object, and is scheduled to be removed after the construction is completed. It is desirable to have a temporary cofferdam that is safe, and how to construct a safe temporary cofferdam at low cost is an extremely important technical concern.

However, the above-mentioned construction method required increasing the wall thickness of the continuous wall, which caused a big problem from an economic point of view.

Here, it is also possible to reduce the wall thickness of the continuous wall and form a reverse wall on the inside of the continuous wall when dry-up the inside of the cofferdam, but this construction method is not suitable for constructing a temporary cofferdam. The problem is that it takes time.

This invention was made in view of these conventional problems, and its purpose is to:
The object of the present invention is to provide a temporary cofferdam construction method using continuous walls that can be constructed economically and in a short period of time.

≪Means for Solving the Problems≫ In order to achieve the above object, the present invention forms a cofferdam in a water body, forms a continuous wall within the cofferdam, and then surrounds the cofferdam with the continuous wall. The method of dry-up the inside is characterized in that a reinforcing beam is installed in advance in either the inner or outer gap formed between the continuous wall and the cofferdam.

≪Operation≫ According to the temporary cofferdam construction method with the above configuration, the inside of the continuous wall
There is a reinforcing beam on either side of the outside, so
When the inside of the cofferdam is dry-uped, the continuous walls and reinforcing beams work together to resist external forces applied to the cofferdam, so there is no need to increase the wall thickness of the continuous walls.

Furthermore, since the reinforcing beams are installed in advance when constructing the cofferdam, the construction period for the temporary cofferdam will not be prolonged.

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

FIG. 1 is a vertical sectional view showing an embodiment of the temporary cofferdam construction method using continuous walls according to the present invention in the order of steps.

In the construction method shown in FIG. 1, first, as shown in FIG.
Filling soil 12 is put in between 10 and 10.

When the filling soil 12 is deposited to a predetermined thickness on the seabed ground E, the first reinforcing beam 14a is installed, and then the filling soil 12 is put in again and the second and third reinforcing beams 14a are installed.
reinforcing beams 14b and 14c are installed.

Here, each of the reinforcing beams 14a, b, and c is located in an outer gap 17 between the continuous wall 16 and the cofferdam 10, which are provided at approximately the center position between the cofferdams 10-10, and on the outside of the continuous wall 16. The continuous wall 16 is located along the outer circumferential shape of the continuous wall 16.

Furthermore, if the object to be constructed within the cofferdam has a circular cross section, the most practical way for each of the reinforcing beams 14a, b, and c is to combine steel members having an appropriate width and thickness into a ring shape. , reinforcement beams 14a, b, c
The reinforcing beams 14a, b, and c may be formed by solidifying the filling soil 12 in a proportion corresponding to the installation position with a solidifying agent containing special additives to suppress separation in water.

When the reinforcing beams 14a, b, c are installed in steps,
As shown in FIG. 1b, a continuous wall 16 is constructed approximately centrally between the cofferdams 10-10.

The continuous wall 16 is made up of the filling earth and sand 12 and the seabed ground E.
It is formed by excavating a hole while filling it with muddy water, placing reinforcing bars in the hole, and then pouring concrete.

When the construction of the continuous wall 16 is completed, the temporary cofferdam is completed, so as shown in Fig. 1c, the reinforcing beam 14 is
Drain the water from the side where a, b, and c are not installed, that is, the inside partitioned by the temporary cofferdam, and dry it up, and construct the target object during the temporary cofferdam.

Now, if the temporary cofferdam is constructed using the method described above, the reinforcing beams 14a, b, and c will be able to withstand the external force that acts on the temporary cofferdam when it is dry-up, as shown in Figure 1c. Since the continuous walls 16 cooperate with each other to oppose each other, the wall thickness of the continuous walls 16 can be made thinner by the amount shared by the reinforcing beams 14a, b, and c.

Furthermore, when constructing inner-rolling concrete during temporary cofferdam construction, a sequential-rolling method in which concrete is poured from the bottom to the top can be adopted, making it possible to shorten the construction period.

FIG. 2 shows another embodiment of the temporary cofferdam construction method using a continuous wall according to the present invention, and only its characteristic points will be described below.

In this embodiment, reinforcing beams 14a to 14c are embedded in advance in an inner gap 18 formed between a continuous wall 16 and a cofferdam 10.

When drying up the inside of the cofferdam 10-10, the reinforcing beams 14a to 1 are sequentially removed from the upper stage side.
4c is exposed, a connecting material 20 such as concrete is filled between the reinforcing beams 14a to 14c and the continuous wall 16, and as shown in FIG. 2b, the reinforcing beam 14a is
~14c and the continuous wall 16 are integrated.

Even if the temporary cofferdam is created as described above, the same effects as those of the above embodiment can be obtained.

≪Effects of the Invention≫ As explained above, according to the temporary cofferdam construction method using continuous walls according to the present invention, construction can be carried out at great depths and on a large scale under economically advantageous conditions, which is the most important aspect of this type of construction method. A temporary cofferdam can be constructed.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the steps of the construction method of the present invention in order, and FIG. 2 is a longitudinal sectional view showing another embodiment of the same method in order of steps. 10... cofferdam, 12... filling earth and sand, 14a,
b, c...Reinforcement beam, 16...Continuous wall.

Claims (1)

[Scope of Claims] 1. A construction method in which a cofferdam is formed in a body of water, a continuous wall is formed within the cofferdam, and then the inside surrounded by the continuous wall is dry-upped, wherein the connection between the continuous wall and the cofferdam is A temporary cofferdam construction method using a continuous wall characterized by installing a reinforcing beam in advance on either the inner or outer gap formed between the inner and outer gaps. 2. A temporary cofferdam construction method using a continuous wall, characterized in that the reinforcing beams are buried in multiple stages at predetermined intervals in the depth direction along the continuous wall.