JPH11229346A - Method for reducing uplift on caisson - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the constructibility and profitability of breakwater construction work by reducing uplift working on caissons, and miniaturizing the caissons while maintaining their simple shape such as a rectangle. SOLUTION: Impervious mats 10, 10... are laid to cover the entire front surface of a rubble mound 3 serving as the foundation of caissons 5, 5... which constitute a breakwater, The work of laying the impervious mats includes conveying the rolled impervious mat 10 into the sea, securing the end portion of the impervious mat 10 to the caisson 5, expanding the impervious mat 10 over the rubble mound 3, and connecting the side edges of the plurality of impervious mats 10, 10... together. A covering 7 is formed over the impervious mat 3. The impervious mats 10, 10... prevent seawater from flowing into the rubble mount 3 to reduce uplift working on the caissons 5, 5....

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caisson lifting pressure reducing method for reducing a lifting pressure acting on a caisson installed on a rubble mound.

[0002]

2. Description of the Related Art As shown in FIG. 3, a breakwater composed of a caisson is constructed by constructing a rubble mound 3 on the seabed 1 and mounting a caisson 5 on the rubble mound 3. When a wave hits such a breakwater, a vertical lift acts on the caisson 5 together with a horizontal wave force. In general, the lift is countered by the weight of the caisson 5. In some cases, the caisson is formed into a special shape, such as a slope structure or a rear parapet structure, to reduce the lifting pressure.

[0003]

As described above, when a caisson resists lifting pressure due to its own weight, the caisson becomes large and the amount of concrete, reinforcing steel, etc. constituting the caisson increases, and construction costs increase. There is a problem that
Further, when the caisson is formed in a special shape, there is a problem that the difficulty of construction is increased as compared with a caisson of a simple shape such as an upright wall caisson, a trapezoidal caisson, or the like.

The present invention has been made in view of such a conventional problem,
An object of the present invention is to provide a caisson lifting pressure reduction method capable of reducing the lifting pressure acting on the caisson irrespective of the shape of the caisson and reducing the cost of breakwater construction work by downsizing the caisson.

[0005]

SUMMARY OF THE INVENTION The features of the present invention for solving the conventional problems as described above and achieving the intended purpose are as follows.
A water-blocking mat having water-blocking properties is laid so as to cover the entire front surface of the rubble mound that forms the basis of the caisson that constitutes the breakwater, a coating is formed on the water-blocking mat, and the inside of the rubble mound is formed by the water-blocking mat. The purpose of the present invention is to prevent seawater from flowing into the caisson and reduce the lift pressure acting on the caisson.

The water-impervious mat is rolled and conveyed into the sea, the tip of the water-impervious mat is fixed to a caisson, and the water-impervious mat is deployed on a rubble mound. It is preferable to lay so that the side edge parts are mutually connected.

[0007]

FIG. 1 is a block diagram showing an embodiment of the present invention.
2 will be described.

A breakwater composed of caisson 5, 5,... Constructs a rubble mound 3 by putting a foundation stone on the seabed 1, and mounts the caisson 5, 5,.
The water-blocking mats 10, 10,... Having water-blocking are laid so as to cover the entire front surface (open sea side) of the rubble mound 3, and a covering stone is put on the water-blocking mats 10, 10,. It is configured by forming a coating 7.

Method of constructing rubble mound 3, caisson 5,
The installation method of 5 and the method of forming the coating 7 are substantially the same as those in the related art, but the divers lay the waterproof mats 10 as follows.

The water-blocking mat 10 is made of a flexible and water-permeable material such as a synthetic resin, and is formed in a long strip shape, compared with a water-blocking sheet used for preventing scouring and the like. Then it is thick and high strength.

First, the impermeable mat 1 rolled up
0 is transported underwater by the hoist ship, and the diver places the leading edge of the water-blocking mat 10 under the outer wall of the caisson 5,
Fixture 12 made of steel plate or the like, anchor bolts 14, 14
… Fixed through. In addition, inserts screwed with the anchor bolts 14, 14,... Are embedded in advance in lower portions of the outer wall surfaces of the caissons 5, 5,.

Next, the diver deploys the impermeable mat 10 on the rubble mound 3 to the opposite side of the caisson 5 and installs it so as to cover the rubble mound 3. At this time, in order to enhance the water-proofing ability, the side-edge part of the water-proofing mat 10 is made to sufficiently overlap with the side-edge part of the existing water-proofing mat 10, and the water-proofing mat 1
The connecting side edges of 0, 10,...
6, 16,...

In this manner, a large number of waterproof mats 10, 10...
Are fixed to the caisson 5, 5... While the side edges are connected to the existing water-impervious mat 10, and are spread and laid on the rubble mound 3 to form a large number of water-impervious mats 10, 10.
... covers the entire front surface of the rubble mound 3. Since the water-impervious mats 10, 10,... Are held down by the covering member 7 after laying, the connection between the water-impervious mats 10, 10,.

By covering the entire front surface of the rubble mound 3 with the impermeable mats 10, 10,..., The inflow of seawater into the rubble mound 3 is prevented, so that the caisson 5, 5, ... can be reduced. Also, since the water-blocking mats 10, 10,... Are laid between the rubble mound 3 and the cladding 7,
The breakage of the impermeable mats 10, 10,... Due to the waves, the separation from the rubble mound 3, and the like can be suitably prevented.

Therefore, it is not necessary to increase the weight of the caisson 5 or to make the caisson 5 a special shape in order to combat the lifting pressure, and the caisson 5 can be reduced in size with a simple shape such as a rectangle. In addition, the workability and economy of breakwater construction can be improved.

[0016]

As described above, in the caisson lifting pressure reduction method according to the present invention, a water-impervious mat having water-imperviousness is laid so as to cover the entire front surface of a rubble mound, which is the basis of a caisson constituting a breakwater, Forming a coating on the impermeable mat,
Water-blocking mats prevent seawater from flowing into the rubble mound and reduce the lifting pressure acting on the caisson. Performance and economy can be improved.

Further, the water-impervious mat is transported in the form of a roll into the sea, the tip of the water-impervious mat is fixed to a caisson, and the water-impervious mat is deployed on a rubble mound. Are laid so as to be connected to each other, so that the entire front surface of the rubble mound can be suitably covered.

[Brief description of the drawings]

FIG. 1 is an elevational view showing an embodiment of a caisson lifting pressure reduction method according to the present invention.

FIG. 2 is a perspective view showing a method of laying a waterproof mat in FIG. 1;

FIG. 3 is an elevational view showing a conventional caisson breakwater.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 sea floor 3 rubble mound 5 caisson 7 cladding 10 water-blocking mat 12 mounting fixture 14 anchor bolt 16 connection anchor

Claims (2)

[Claims] 1. A water-blocking mat having a water-blocking property is laid so as to cover the entire front surface of a rubble mound, which is the basis of a caisson constituting a breakwater, and a coating is formed on the water-blocking mat, A caisson lifting pressure reduction method for preventing the inflow of seawater into the rubble mound and thereby reducing the lifting pressure acting on the caisson. 2. A water-impervious mat is rolled and conveyed into the sea, and a front end portion of the water-impervious mat is fixed to a caisson to spread the water-impervious mat on a rubble mound. The caisson lifting pressure reduction method according to claim 1, wherein the side edge portions are laid so as to be connected to each other.