JPS63201214A - Settling of caisson - Google Patents

Abstract

PURPOSE:To permit a caisson to be settled in shallow water depth with high accuracy by a method in which a shell having an air-tight bag on its downside is towed to a settling position, concrete is placed into the shell, and the bag is degassed and settled on the bottom under water. CONSTITUTION:A steel hollow cutting edge shell 12 having an air-tight bag 10 on its downside is towed to a settling position. Concrete is placed into the shell 12 while charging as into the bag 10 to form the bottom slab 16 of caisson in a floated state. After the concrete hardens, the bag 10 is deflated and the cutting edge 18 is landed on the bottom under water. The walls 22 of the caisson are formed on the slab 16, and the bottom 20 below the cutting edge 18 is excavated to settle the caisson down to a given depth. Since control on attitude of the caisson during settling period can be performed by controlling the amount of air in the bag 10, the resettling of the caisson is made possible by supplying of air into the bag 10 even when the settling position is shifted by tidal waves or current.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for installing a box.

(Prior Art) As is well known, a floating caisson installed on the bottom of a water body is towed to a place where it is to be submerged and then suspended by a large crane ship or the like.

In addition, when installing using a crane ship, etc., the crane ship may be unable to operate near the coast or in rivers where the water is shallow, as the stagnation of the crane ship may exceed the water depth.
In such cases, the methods of setting up a rocky island at the site of the caissons and dismantling the rocky island after sinking the caissons, or dredging the bottom of the water to deepen the water depth are also adopted.

However, in the method of installing a 70-ton caisson as described above, the caisson is generally assembled completely on land or at a dock and then towed to the sinking site, but this method shortens the construction period. The drawback was that it took a long time.

Therefore, a method has recently been proposed in which only the lower end of the caisson is made of steel, the caisson is fabricated on land, the caisson is towed to the location, and then concrete is poured inside the caisson for installation.

This method has the advantage of requiring only a small vessel to tow the caisson and shortening the construction period; however, if the concrete reaches the water bottom before it hardens, it may become deformed due to unevenness of the water bottom, etc. There was a problem that it would harden while it remained upright.

In addition, when it is submerged, the installation position is likely to shift due to waves or water currents, and if it does shift, it is difficult to reinstall it in a predetermined position, making it difficult to install with high precision.

This invention was made in view of the conventional problems as described above, and its purpose is to provide a method for installing a box that does not cause harmful deformation during installation and that allows for highly accurate installation. It is about providing.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for installing a box installed on the bottom surface of water, in which a cutter shell with an airtight bag disposed on the bottom surface is installed. It is towed to the site, and while injecting gas into the airtight bag, concrete is poured into the cutter shell to form the lower part of the box in a floating state, and after the concrete hardens, it is installed on the bottom of the water. It is characterized by

(Function) According to the installation method with the above configuration, the process of pouring concrete into the cutting edge shell of the box is carried out in a 70-ring state while injecting gas into the airtight bag and adjusting its buoyancy. Since the concrete is placed on the bottom of the water after it has hardened, no deformation occurs when it lands on the bottom of the water.

Furthermore, by adjusting the amount of gas injected into the airtight bag, it is possible to control the state of submersion and reinstallation, so installation can be performed with high precision.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the method for installing a box according to the present invention in the order of steps.

In the method shown in the figure, first, a hollow steel cutter shell 12 with a closed lower end, which is the lower side of a box with a plurality of airtight bags 10 and 10 arranged on the lower surface, is manufactured on land. A pipe 14.14 extending to the upper surface of the cutting edge shell 12 is connected to each airtight bag 10.10.

When the cutting edge shell 12 is completed, it is transported in a floating state by a small towing boat 11 to a burial site, as shown in FIG. 1(a).

When the blade shell 12 arrives at the place where it is deposited, as shown in Fig. 1(b)
As shown in the figure, concrete will be poured inside.

When pouring concrete, air is injected through the pipe 14 to inflate the airtight bag 10 and 10 to adjust the buoyancy and perform this in a floating state.

When the concrete for forming the bottom plate 16 of the box has been poured, the floating state is maintained until the concrete hardens.

When the bottom plate 16 is completed, the air inside the airtight bag 10.10 is removed through the pipe 14 while the blade 12 is gradually removed.
, and the blade 018 lands on the water bottom surface 20 (see FIG. 1(C)).

It should be noted that the amount of concrete that needs to be placed is sufficient to allow the cutting edge shell 12 to stably land on the bottom surface of the water.
It is not necessarily necessary to cast the amount to form the bottom plate 16.

In this case, the attitude control during sinking is performed by increasing or decreasing the amount of air inside the airtight bag 10, and if the landing position shifts, air is injected into the airtight bag 10 again and the installation is re-installed. Do this.

The cutting edge shell 12 with the bottom plate 16 formed as described above
When the is correctly positioned and installed, the image shown in Fig. 1(d)
As shown in FIG.
The water bottom surface 20 below the blade opening 18 is excavated, the box is lowered to a predetermined depth, and concrete is poured into the space formed under the blade opening 18 to complete the installation.

(Effects of the Invention) As explained above, according to the method for installing a box according to the present invention, concrete can be placed in a floating state at a sinking location in a cutter shell having an airtight bag provided on the lower surface. The lower part of the box is formed using concrete, and this is sunk after the concrete has hardened. This eliminates harmful deformation of the box, and also allows the airtight bag to maintain its posture by injecting and expelling gas when it is sunk. Since it can be controlled, even if the installation position is shifted due to waves or water currents, it can be easily reinstalled within m*.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram sequentially showing the construction order of the method of the present invention. 10... Airtight bag 12... Blade 14... Pipe 16...
・Bottom plate 18...Blade mouth 20...
... Water bottom surface 22 ... Wall Patent applicant Obayashi Corporation Representative Patent attorney - Kensuke Shiro
Patent attorney Masatoshi Matsumoto

Claims (1)

[Claims] In the installation method for a box installed on the bottom surface of water, a cutting shell with an airtight bag arranged on the bottom surface is towed to the installation site, and while gas is injected into the airtight bag, the cutting shell is injected into the cutting shell. A method for installing a box, comprising: pouring concrete to form a lower part of the box in a floating state, and installing the box on the bottom surface of water after the concrete has hardened.