JPH073811A - Installation method of caisson - Google Patents

Abstract

PURPOSE:To bear the whole bottom of a steel shell caisson with equal force, and increase the degree of accuracy of installation by applying substitutional sand to a planned sea-bottom of installation in advance, and constructing a bearing mound thereon. CONSTITUTION:Substitutional sand 1 is applied to a planned sea-bottom of installation of a steel shell caisson 3, and a bearing mound 2 having the same shape as that of a work room 34 of the steel shell caisson 3 is constructed thereon. After that, the steel shell caisson 3 is towed upward of the bearing mound 2, slab concrete is placed to a ceiling section 33 of the work room 34, and the steel shell caisson 3 is settled by concrete load. Then, a cutting edge section 32 is settled to the sea-bottom and is penetrated thereinto, a ceiling slab of the work roan 34 is settled to the upper surface of the bearing mound 2, and the steel shell caisson 3 is installed. At that time, the whole bottom of the steel shell caisson 3 can be borne on equal force by the substitutional sand 1 and bearing mound 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of installing a steel shell casing.

[0002]

2. Description of the Related Art When a steel shell caisson is installed at a shallow water depth, conventionally, as shown in FIG. 4, the steel shell caisson a is towed to a planned installation location and then surrounded by a blade opening b. A slab concrete is placed on the ceiling portion d of the bottom working chamber c
It settled by the load of the concrete, and the blade opening part b was made to settle in the bottom of the water bottom ground, and was installed.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
There are the following problems. <a> In the water-bed ground in a natural state, because the supporting capacity of the caisson is not uniform, as shown in FIG. 4, the caisson body may incline and intrude. The concrete flows toward the lower slope to generate a larger slope. Therefore, the subsequent case
The direction in which the song is sunk is greatly deviated, and a great deal of construction time and cost is required to correct the direction in which the song is sunk.

<B> Further, as shown in FIG.
Is supported on the water bottom ground, but the ceiling part d is not supported. Therefore, when the slab concrete is placed, a large bending moment acts on the center of the ceiling part d due to its weight, and the case
There is a risk of deformation of the body. Therefore, it is necessary to increase the rigidity of the structure of the steel shell caisson, which causes an increase in manufacturing cost.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a steel shell capable of improving the installation accuracy of the caisson and simplifying the structure of the caisson. The purpose is to provide a method for installing a caisson.

[0006]

That is, the present invention relates to a method of installing a steel shell caisson having a working chamber surrounded by a blade opening at the bottom on a submarine ground, in which the caisson is to be installed beforehand. After constructing a replacement sand and constructing a support mound having substantially the same shape as the working chamber of the steel shell caisson on the replacement sand, the steel shell caisson is towed above the support mound, and the working room The slab concrete is placed on the ceiling part of the above and settled by the concrete load, and the blade part is set to the bottom of the submerged ground and penetrates, and the ceiling slab of the working room is set on the upper surface of the support mound and installed. It is a method for installing a caisson, which is characterized by that.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <a> Construction of replacement sand and support mound As shown in Fig. 1, replacement sand 1 is constructed in advance on the ground where the cason is to be installed. This replacement sand 1 is applied in a wider area than the outer shape of the caisson.

Next, a support mound 2 having a substantially same shape (for example, trapezoidal shape) as a working chamber 34 of a steel shell caisson 3 described later is built on the replacement sand 1. The materials that make up the support mound 2 should be selected according to the tidal current or wave conditions at the installation point. If the tidal current or wave conditions affect the material, use a material with a large particle size such as crushed stone, and then scour or drain. And so on.

Also, as slope protection of the support mound 2,
Further, use crushed stone or bagged mortar with a larger particle size. When constructing in a quiet area, use coarse sand as the mound material.

The building height of the support mound 2 is
The amount h of the blade opening 33 penetrating the bottom of the water due to the concrete load placed in the chamber is calculated (FIG. 3), and the height H−h is subtracted from the height H of the working chamber 34. (Fig. 1).

<B> Caisson towed steel shell caisson 3 has a steel outer shell, and as shown in FIG. 1, has an annular shape at the bottom of a side wall portion 31 having a cylindrical shape or a rectangular tube shape. In this structure, the blade opening portion 32 is vertically provided, and a working chamber 34 surrounded by the blade opening portion 32 and the horizontal ceiling portion 33 is provided.

The steel shell casing 3 thus constructed is towed to a position above the support mound 2 as shown in FIG.

<C> Placing the slab concrete and installing the caisson As shown in FIG. 2, after the towing of the steel shell caisson 3, the ceiling 3
A slab concrete 4 is placed in 3 and is gradually settled by concrete load, and the blade opening 32 is bottomed on the replacement sand 1.

Next, as shown in FIG. 3, the concrete load is further increased so that the blade opening portion 32 penetrates into the replacement sand 1. Then, when the penetration amount reaches h, the ceiling portion 33 bottoms on the upper surface of the support mound 2, and the installation of the steel shell caisson 3 is completed.

The displacement sand 1 and the support mound 2 can support the entire bottom portion of the steel shell caisson 3 installed on the upper portion with an equal force, unlike the water bottom soil in a natural state. After bottoming, pressure rock excavation for constructing a material lock and sinking the steel shell caisson 3 is performed.

[0016]

Since the present invention is as described above, the following effects can be obtained. <A> Since the bottom of the steel shell caisson is supported by an even supporting force of the displacement sand and the supporting mound, inclination and displacement of the caisson at the time of bottoming can be prevented. Therefore, unlike the conventional method, a great amount of work and cost are not required for the correction work in the sunk direction.

<B> Since the ceiling slab in the work chamber of the steel shell caisson is evenly supported by the entire area of the upper surface of the support mound, a large bending moment acts on the central portion of the ceiling slab as in the conventional case. However, it does not deform the casing body. Therefore, the steel shell structure can be simplified and the manufacturing cost can be reduced.

<C> Since the entire bottom of the caisson is supported by the replacement sand and the support mound at the time of initial digging where the frictional force on the peripheral surface cannot be expected, safe excavation and excavation can be performed by adjusting the support area. It becomes possible to perform the laying work.

[Brief description of drawings]

FIG. 1 Explanatory drawing of tow process of steel shell caisson

FIG. 2 is an explanatory view of a settling process of a steel shell caisson.

FIG. 3 is an explanatory view of a bottomed state of a steel shell caisson.

FIG. 4 is an explanatory diagram of a conventional technique.

FIG. 5 is an explanatory diagram of a conventional technique.

Claims (1)

[Claims] 1. A method of installing a steel shell caisson having a working chamber surrounded by a blade opening at the bottom on a subseabed ground, in which replacement sand is applied in advance to the ground to be installed in the caisson, and the replacement sand is placed on the replacement sand. After constructing a support mound having almost the same shape as the working chamber of the steel shell caisson, the steel shell caisson is towed above the supporting mound, and a slab concrete is struck on the ceiling of the working chamber. The casson is characterized in that it is installed and settled by a concrete load, the blade opening is set on the bottom of the water bottom and penetrates, and the ceiling slab of the working chamber is set on the upper surface of the support mound. Installation method.