JPH06990B2 - Kason installation method - Google Patents

Description

The present invention relates to a caisson installation method used as a foundation for breakwaters, seawalls, bridges, and the like.

"Prior art" Conventionally, it is generally known that caisson is used as the foundation of breakwaters, seawalls, bridges, etc., but in this case, the caisson is usually constructed at a place different from the site and then transported to the site, Once installed in place, it will be installed in the usual procedure.

When installing the above caisson on the site, as shown in FIG. 5, a mound 1 is made by laying rubble stones 1a in advance, and the upper surface of the mound 1 is leveled with high accuracy, and the caisson is placed on the leveled mound 1. Install 2.

Next, a pre-packed concrete is cast on the lower inside of the caisson 2 to make a bottom slab 3, and a slab 4 is laid on the rubble mound 1 near the outer periphery of the caisson 2 to fix the caisson 1. It was being done.

"Problems to be solved by the invention" In the caisson installation method described above, there is a great deal of manual work by diving, which has been a major obstacle to shortening the construction period and reducing the construction cost. .

That is, in the above-mentioned construction method, the work of leveling the upper surface of the mound 1 with high accuracy, when the prepacked concrete is placed inside the caisson 2, the wall of the caisson 2 is preliminarily prevented from flowing out. Work to crush and fill the gap between the lower end of the part and the rubble mound 1 (R in the figure shows the stuffing), and work to spread the stone 4 on the rubble mound 1 near the outer periphery of the caisson 2. However, the actual situation is that these tasks rely on manual work by divers.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a caisson installation method in which manpower can be significantly reduced by diving, and the construction period and the construction cost can be reduced.

[Means for Solving the Problems] In order to achieve the above object, the present invention attaches the end of the outer net for the formwork to the outer periphery of the wall of the caisson, and the inner part of the formwork to the inner periphery of the wall of the caisson. Attach the end of the net,
Place the caisson on a submarine mound that is approximately level,
The upper surface of the mound near the outer periphery of the caisson is covered with the outer net for the mold, and the inner net for the mold is laid on the upper surface of the mound on the inside of the caisson, and the outer net is used as the upper mold to form a viscous agent on the lower side. While the concrete mixed with a predetermined amount is poured, the inner net is used as a lower formwork and the concrete with a predetermined amount of a thickener is poured on the upper side of the inner net to mount and fix the caisson.

"Action" For concrete containing a specified amount of thickener, cement is not washed with water, and almost all of it is fixed in a mold using a net.

Therefore, it is not necessary to perform crushing and filling work between the lower end of the caisson wall and the rubble mound, and it is also necessary to perform manual work for root consolidation near the outer periphery of the caisson, that is, work to spread paving stones. There is no. Further, since it is not necessary to perform the crushing and filling operations, the leveling accuracy of the upper surface of the mound can be relaxed, and the leveling work can be mechanized.

"Embodiment" FIGS. 1 to 4 are procedure explanatory views showing an embodiment of the present invention.

This method will be described with reference to these figures. When installing a caisson, first, a mound 1 is prepared by laying a rubble stone 1a in advance at a place where the caisson is installed (see FIG. 1). At this time, it is necessary to flatten the upper surface of the mound 1 substantially evenly, but in the present method, this flattening work can be performed by a machine such as an underwater bulldozer 10 having a rough finishing accuracy. This is one of the major features of this method.

Next, as shown in FIG. 2 and FIG. 3, the case 11 constructed beforehand at another location is transported, suspended by a crane ship or the like, and installed on the rubble mound 1.

As shown in FIG. 2, the end portion of the outer net 12 is fixed to the caisson 11 at a predetermined height position on the outer peripheral portion of the wall portion 11a, and the inner net is fixed at a predetermined height position on the inner peripheral portion of the wall portion 11a. Thirteen
The end of is fixed.

The outer net 12 and the inner net 13 are the caisson 11
It is used as a formwork when placing concrete inside and outside of the wire mesh, wire mesh, metal mesh,
Geotextiles are used. Also, as a result of the experiment,
It has been found that it is advantageous to use the nets 12 and 13 having a mesh diameter of 70% or less of the aggregate mixed in the concrete to be cast. If a mesh with a larger mesh is used, the amount of concrete flowing out from the mesh will be significantly increased.

Also, during the transportation or hanging, the nets 12, 1
If the end portion of the net 3 is suspended and supported by the rope 14 on the side opposite to the side fixed to the caisson 11, the net 1
It is possible to prevent 2 and 13 from swinging unnecessarily.

Next, after the caisson 11 is installed, the rope 14 is cut, the outer net 12 is put on the mound 1 near the outer peripheral portion of the caisson 11 as shown in FIG.
1 Mound 1 on the inside.

At this time, if the weight 15 is previously arranged at the end of the nets 12 and 13 opposite to the side fixed to the caisson 11,
The movement of the net due to the flow of water can be suppressed, which is advantageous in the work of expanding the net.

Next, a plurality of tremie pipes 16 arranged at appropriate intervals on the outer periphery of the caisson 11 are extended downward to penetrate the outer net 12, and the net 12 and the mound 1 covered with the net 12 are passed through the tremie pipe 16. Concrete is poured between the two to make root-consolidating concrete 17. At this time, if the weight 15 is attached to the end of the net as described above,
The end of the net can be held in contact with the mound 1, and concrete can be prevented from flowing out from the gap between the net end and the mound 1.

Further, a plurality of tremie pipes 18 are also arranged inside the caisson, and the inner net 13 is used as a lower formwork through the tremie pipes 18 and concrete is placed on the upper part thereof to form a bottom slab 19.

The concrete to be poured is polyvinyl alcohol,
Polyacrylamide, polyethylene oxide, sodium polyacrylate, carboxymethyl cellulose, methyl cellulose and cellulose ethers represented by these,
Use a mixture of a thickener such as sodium alginate and guamco in a weight ratio of 0.2 to 4.0% with cement. By using such concrete, it is possible to prevent the cement from being washed with water and flowing out from the nets of the nets 12 and 13, so that almost the entire amount of the placed concrete can be placed in the form using the net. Can be fixed.

The caisson 11 can be firmly fixed on the mound by the above method.

In this way, since concrete is directly cast on the outer peripheral portion of the caisson 11 to make the concrete 17 to be solidified, it is possible to eliminate the work of laying stones on the outer peripheral portion of the caisson 11, which is conventionally performed. You can

Also, when the bottom slab 19 inside the caisson 11 is placed, the top net of the mound 1 is laid out and placed as a formwork, so there is a slight gap between the lower end of the outer wall of the caisson 11 and the waste stone mound. Even if it occurs, it is not necessary to carry out the work for crushing or closing the mesh. Further, from this, the leveling accuracy of the waste stone mound can be significantly eased, and as described above, the leveling operation of the mound 1 can be performed by a machine having a rough finishing accuracy.

[Advantages of the Invention] According to the present invention, it is possible to eliminate the conventional work of crushing and filling between the lower end of the wall of the caisson and the rubble mound, and the work of laying stones near the outer periphery of the caisson. Further, since the mound leveling work can be mechanized, the manual work can be almost eliminated. As a result, the construction period and the construction cost can be shortened, and the caisson can be installed at the deep water (30 to 50 m).

Also, by using concrete mixed with a specified amount of thickening agent, it is possible to place concrete inside the caisson inside or outside without using prepacked concrete or paving stones, using a net as a formwork. For,
It is possible to achieve firm fixation with the mound and flattening of the top of the concrete, and it is possible to realize concrete pouring with high strength and uniform quality compared to the case of using conventional prepacked concrete.

[Brief description of drawings]

1 to 4 are views for explaining the procedure for carrying out the method of the present invention, FIG. 1 is a cross-sectional view of the work for leveling the top of the mound, and FIG. 2 is a side view for explaining suspension of a caisson. Figures and 3 are cross-sectional views illustrating the caisson installed on the mound, and Fig. 4 is a cross-sectional view of the bottom slab inside the caisson and the concrete-consolidating outside the caisson being placed.
FIG. 5 is a sectional view for explaining a conventional caisson installation method. 1 …… Scrap stone mound, 10 …… Underwater bulldozer, 11 …… Caisson, 12 …… Outer net, 13 …… Inner net, 15,16 …… Tremy pipe, 17 …… Consolidated concrete, 18 …… Bottom plate.

Claims (1)

[Claims] 1. A caisson is provided with an end of an outer net for a formwork on an outer periphery of a wall of the caisson and an inner end of an inner net for a formwork is attached to an inner circumference of a wall of the caisson so that the caisson is evenly leveled. It is installed on the seabed mound, the upper surface of the mound near the outer periphery of the caisson is covered with the outer net for the formwork, and the inner net for the formwork is laid on the upper surface of the mound inside the caisson, and the outer net is used as the upper formwork. While placing concrete with a certain amount of thickener on its lower side, place the caisson by placing concrete with a certain amount of thickener on the upper side using the inner net as a lower formwork. A caisson installation method characterized by: