JPS62248715A - Installation work for caisson - Google Patents

Abstract

PURPOSE:To shorten the period of construction as well as to reduce the cost of construction by a method in which an outer net and an inner net are each attached to the outer and inner surfaces of the wall of a caisson, the caisson is set on a seabed mound, and concrete is placed into both the inner and outer nets as formworks. CONSTITUTION:The end of an outer net 12 is fixed to the periphery of the wall 11a of a caisson 11, and the and of an inner net 13 is fixed to the inner surface of the wall 11a. The other ends of both the nets 12 and 13 are lifted up and supported by a rope 14. The caisson 11 is lifted up by a crane ship, etc. and set on a rubble mound 1, and the rope 14 is cut off to cover the net 12 on the mound 1 near the periphery of the caisson 11. The net 13 is laid on the mound 1 inside of the caisson 11. A concrete mixed with a thickening agent is placed into the space between the net 12 and the mound 1 covered with the net 12 through a tremie tube 16 to form a foot-protecting concrete 17. The same concrete is further placed onto the net 13 through a tremie tube 18 to form a bottom slab 19.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for installing caissons used as foundations for breakwaters, sea walls, bridges, etc.

``Prior Art'' Conventionally, it is known that caissons are generally used as the foundations of breakwaters, sea walls, bridges, etc. In this case, the caisson is usually constructed at a location different from the site, and then transported to the site. It is installed by installing it in a predetermined position.

When installing the above-mentioned caisson on site, as shown in Fig. 5, a mound L is created by laying rubble 1a on a flat surface, and the upper surface of this mound 1 is leveled with high precision. Install caisson 2 on top.

Next, pre-packed concrete is placed in the lower part of the inside of the caisson 2 to form the bottom slab 3, and paving stones 4 are spread over the rubble mound l near the outer periphery of the caisson 2, thereby providing means for fixing the caisson 1. It had been taken.

``J?l&nnJ, zek Ual to, !lJ-'' 1. In the above-mentioned caisson installation method, there is a great deal of manual labor involved in diving, which shortens the construction period and reduces construction costs. This was a major obstacle in achieving this goal.

In other words, in the above construction method, the top surface of mound l is leveled with high precision, and when prepacked concrete is poured inside caisson 2, the caisson 2 is leveled in advance to prevent this concrete from flowing outside. Work to fill in and close the gap that occurs between the lower end of the wall and the rubble mound L (R in the figure indicates closing), and also to place the masonry 4 on the rubble mound I near the outer periphery of the caisson 2. There is work involved in laying the floor, and the reality is that this work relies on manual labor 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 that can significantly reduce the manual labor required by diving, shorten the construction period, and reduce the construction cost.

"Means for Solving the Problems" In order to achieve the above object, the present invention attaches the ends of the outer net for formwork to the outer periphery of the wall of the caisson, and also attaches the end of the outer net for formwork to the inner periphery of the wall of the caisson. Attach the ends of the net,
The caisson is installed on a seabed mound leveled with the road surface,
The upper surface of the mound near the outer periphery of the caisson is covered with the outer net for formwork, and the inner net for formwork is spread over the upper surface of the mound inside the caisson, and the outer net is used as an upper formwork and a viscous layer is applied to the underside thereof. Concrete mixed with a predetermined amount of a thickening agent is poured, while concrete mixed with a predetermined amount of a thickening agent is poured on the upper side of the inner net as a lower formwork, and the caisson is installed and fixed.

``Operation'' Concrete mixed with a predetermined amount of a thickening agent solidifies almost entirely in a formwork using a net, without the cement being washed away by water.

Therefore, there is no need to carry out construction and filling work between the lower end of the caisson wall and the rubble mound, and there is also no need to perform manual work to harden the roots near the outer periphery of the caisson, and work to lay the stones tightly. There's no need to do it. Further, since it is not necessary to perform the above-mentioned slicing and filling work, the leveling accuracy of the upper surface of the mound can be relaxed, and this leveling work can be mechanized.

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

To explain this construction method according to these diagrams, when installing a caisson, first, a mound 1 is created by laying rubble 1a in advance at the location where the caisson will be installed (see Figure 1). At this time, it is necessary to level the top surface of Mound I so that it is almost flat, but in this construction method, this leveling work is performed using an underwater bulldozer, which has poor finishing accuracy. This can be done by a machine such as 0 or the like.

This is a major feature of this method.

Next, as shown in FIGS. 2 and 3, the caisson 11 previously constructed at another location is transported, suspended by a crane ship, etc., and installed on the rubble mound l.

An end of an outer net 12 is fixed at a predetermined height on the outer circumference of the wall 11a, and an end of an inner net 13 is fixed at a predetermined height on the inner circumference of the wall 11a.

The above outer net I2 and inner net 13 are connected to the caisson 11.
It is used as a formwork when pouring concrete inside and outside of the building.
Geotextile etc. are used. In addition, as a result of the experiment,
It has been found that it is advantageous to use nets I2 and I3 whose mesh diameter is 70% or less of the aggregate mixed in the concrete to be cast. If a mesh larger than this is used, the amount of concrete flowing out from the mesh will be significantly increased.

In addition, during the transportation or hanging, the net I2.1
3 caisson l! If the opposite end of the net 12 is lifted and supported by the lobes 14,
．． 13 can be prevented from swinging unnecessarily.

Next, caisson l! After installation, cut the rope 14: 1--1-rQIT711-2 J-L: I+AI-+
-11n#-z-+1 Mound 1 near the outer periphery of 11
Place the inner net 11 over the mound l inside the caisson 11.

At this time, if the weight +5 is placed in advance on the opposite end of the net 12, +3 from the side fixed to the caisson II,
It can suppress the movement of the net due to the flow of water, which is useful when expanding the net.

Next, caisson l! A plurality of tremie tubes 16 arranged at appropriate intervals around the outer circumference of the net I2 are extended downward to penetrate the outer net I2, and concrete is placed between the net 12 and the mound I covered by it through the tremie tubes 16. Pour the concrete and make foot hardening concrete +7. 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 l, and the concrete will flow out from the gap between the end of the net and the mound l. It is possible to prevent this from happening.

Further, a plurality of tremie pipes 18 are arranged inside the caisson, and the inner net 13 is used as a lower formwork through the tremie pipes 18, and concrete is poured into the second part of the inner net 13 to form a bottom slab 19.

The concrete to be poured is polyvinyl alcohol,
Polyacrylamide, polyethylene oxide, sodium polyacrylate, carboquine methylcellulose, methylcellulose and cellulose ethers represented by these,
A thickening agent such as sodium alginate or Guamco is used in a weight ratio of 0.2 to 4.0% with respect to cement. By using such concrete, it is possible to prevent cement from being washed away by water and flowing out through the mesh of the net 12.13, and almost all of the poured concrete can be contained within the formwork using the net. It can be solidified.

By the above method, the caisson 11 can be firmly fixed on the mount.

In this way, since the foot protection concrete 17 is created by pouring concrete directly on the outer periphery of the caisson 11, the work of laying stones around the outer periphery of the caisson It, which was conventionally done, can be eliminated. Can be done.

Also, the inside bottom plate of caisson 11! When pouring the caisson 11, a net is spread over the top of the mound l, and this is used as a formwork, so even if there is some gap between the lower end of the outer wall of the caisson 11 and the stone mound, it is necessary to fill it up or There is no need to perform eye filling work. Also, from this, it is possible to significantly reduce the leveling accuracy of the stone mound, making the mound look smooth! It became possible to perform the leveling work using a machine with coarse finishing accuracy.

"Effects of the Invention" According to the present invention, it is possible to eliminate the conventional work of closing and packing between the lower end of the wall of the caisson and the rubble mound, and the work of laying stones around the outer periphery of the caisson. Moreover, since the mound leveling work can be mechanized, manual work can be almost eliminated.

As a result, it has become possible to shorten the construction period and reduce construction costs.

In addition, by using concrete mixed with a predetermined amount of thickening agent, concrete can be placed using net formwork inside or outside the caisson without using pre-packed concrete or paving stones. For this reason,
This allows for strong fixation with the mound and flattening of the top of the poured concrete, making it possible to place concrete with higher strength and uniform quality than when using conventional pre-packed concrete. .

[Brief explanation of drawings]

Figures 1 to 4 are diagrams explaining the procedure for carrying out the construction method of the present invention. Figure 1 is a cross-sectional view of the work of leveling the top of the mound, and Figure 2 is a side view explaining the lifting of the caisson. Figure, 3rd
The figure is a cross-sectional view explaining the state in which the caisson is installed on a mound, Figure 4 is a cross-sectional view of the bottom slab inside the caisson and the concrete being poured outside the caisson, and Figure 5 is a conventional caisson installation. It is a sectional view explaining a construction method. ■・・・Rubble mound, lO・・・Underwater bulldozer-1! 1...caisson, 12...outer net, 13...inner net, l5, 16...toshimi
- Pipe, I7... Foot protection concrete, 18
...Bottom version.

Claims (1)

[Claims] Attach the ends of the outer net for formwork to the outer periphery of the wall of the caisson, and the end of the inner net for formwork to the inner periphery of the wall of the caisson, and install the caisson on a seabed mound leveled with the road surface. , the upper surface of the mound near the outer periphery of the caisson is covered with the outer net for formwork, and the inner net for formwork is spread over the upper surface of the mound inside the caisson, and the outer net is used as an upper formwork and adhesive is applied to the underside thereof. The method is characterized in that while concrete mixed with a predetermined amount of a thickening agent is poured, the inner net is used as a lower formwork, and concrete mixed with a predetermined amount of a thickening agent is poured on the upper side of the inner net, and the caisson is installed and fixed. Caisson installation method.