JPS60498B2 - Underwater concrete pouring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the construction of underwater structures, a construction method using tremie pipes is often used as a method for placing concrete.

However, when pouring concrete through a tremie pipe, after concrete pouring has been interrupted due to some kind of malfunction or accident, there is a problem with measures to be taken when concrete pouring is restarted and the first concrete is poured into the tremie pipe. has been done. This becomes a serious problem in the construction of underwater structures at great depths, and in the current situation where the number of constructions of underwater structures at great depths is increasing, a solution to this problem is desperately needed. The present invention solves these problems and provides an improved underwater concrete casting method that eliminates the drawbacks of the conventional tremie method and enables highly reliable underwater concrete placement. It is something to do.

Figures 1 to 3 show the tremie construction method for a secondary shaft, which is shown in Figure 1. In the conventional construction method shown in Figure 1, the lower end of the tremie pipe a is closed with a cover piece b. The tremie pipe is placed underwater and concrete is poured into the pipe, but as the water depth increases, the buoyancy increases, making it difficult to fix the tremie pipe a, and the impact force caused by the falling speed of the concrete causes the lid to break. Piece b can be easily removed, and furthermore, concrete pouring cannot be interrupted.

In the conventional construction method shown in Fig. 2, a plunger c is slidably inserted into a tremie pipe a and concrete d is poured into the pipe, but since the falling speed of the plunger c cannot be controlled, the concrete d is poured rapidly. Also, concrete pouring cannot be interrupted.

In the conventional method shown in FIG. 3, in order to improve the method shown in FIG. 2, the plunger c is suspended by a lifting element e to control its falling speed, but concrete placement cannot be interrupted.

The present invention aims to eliminate such defects by placing a tremie pipe equipped with an on-off valve near its lower end in water with the on-off valve open, and then closing the on-off valve to complete the tremie pipe. Water is injected into the pipe to raise the water level in the pipe, and then a plunger is conveniently installed in the pipe, concrete is poured into the pipe, and the opening degree of the opening/closing valve is adjusted to cause the concrete in the tremie pipe to flow into the plunger. This relates to an underwater concrete placing method characterized by dropping concrete into the water from the lower end of the pipe.

In the present invention, as described above, when installing the tremie tube underwater, the on-off valve installed near the lower end of the tube is opened, so the inside of the tremie tube is filled with water up to the water level in the outside world, so the buoyancy There are no problems such as difficulty in fixing the tremie tube.

After the tremie tube is placed underwater as described above, in the present invention, the on-off valve is closed and water is injected into the tube to raise the water level inside the tube above the water level in the outside world, and then the plunger is slidably inserted into the tube. Therefore, the concrete inside the pipe will not fall due to the water pressure inside the pipe.

In the present invention, after this, the water level in the tremie pipe is gradually lowered by adjusting the relationship of the on-off valve, so that the concrete in the pipe follows the plunger and falls inside the pipe according to the rate of decline of the water level. It falls into the water from the bottom end of the pipe. In this way, according to the present invention, concrete is placed using the water pressure inside the tremie pipe, which facilitates the initial concrete placement using the tremie pipe, and eliminates the separation of concrete aggregates. It is possible to reliably place high-quality concrete, and is particularly effective for placing concrete at great depths.

Further, by adjusting the on-off valve, the concrete placing speed can be freely adjusted, concrete is placed in response to the situation at the site, and highly reliable underwater concrete placing is possible. The present invention is also characterized in that, in the underwater concrete placing method, when concrete placing is interrupted, the on-off valve of the tremie pipe is closed. It is possible to deal with interruptions in concrete pouring caused by such reasons.

The present invention will be described below with reference to the illustrated embodiments.

1 is a tremie tube, and there is an on-off valve 2 approximately 1 above the lower end of the tube.
is established.

The on-off valve 2 is an automatic on-off valve such as a pinch valve that is opened and closed by air pressure. The tremie tube 1 is placed underwater with the on-off valve 2 open.
At this time, since the inside of the tremie tube 1 is filled with water up to the water level 3 in the outside world, no problem occurs due to buoyancy. (See Figure 4) Next, close the on-off valve 2, and pour concrete into the tremie pipe 1 to a height that does not interfere with the pouring of concrete.The water level in the pipe is 3.
After raising the water above the water level 3 in the outside world, a plunger 4 is slidably inserted into the pipe, and then concrete 5 is poured into the pipe.

At this time, the poured concrete 5 does not fall due to the water pressure inside the pipe. Note that 6 in the figure is a hopper. (See Figure 5)
Next, when the on-off valve 2 is gradually opened to lower the water level in the tremie pipe 1, the concrete 5 in the pipe falls according to the rate of decline of the water level in the pipe, and thereafter due to the balance between the concrete 5's own weight and the water pressure.

At this time, since the water pressure in the tremie pipe 1 can be freely adjusted by operating the on-off valve 2, the falling speed of the concrete 5 can also be freely adjusted. (See Figures 6 and 7) Thus, when the plunger 4 reaches the on-off valve 2, the on-off valve 2 is fully opened, the plunger 4 is pushed out from the lower end of the tremie pipe 1, and concrete is poured into the water from the same pipe 1. It is something to do.

(Refer to Fig. 8) When concrete 5 is continuously placed in water as shown in Fig. 8, when concrete placement is interrupted due to an accident, etc., the opening/closing valve 2
Just close it. Although the present invention has been described above with reference to embodiments, the present invention is, of course, not limited to such embodiments, and can be modified in various ways without departing from the spirit of the invention. be.

[Brief explanation of drawings]

Figures 1 to 3 are longitudinal cross-sectional views showing the implementation status of the subordinate tremie method, and Figures 4 to 8 are longitudinal cross-sectional views showing the steps of an embodiment of the underwater concrete casting method according to the present invention. It is a diagram. 1... Tremy tube, 2... Open/close valve, 4...
...Plungeer, 5...Concrete. Complete ↑Figure 2Figure 3Figure 4Figure 5Figure 6F Figure 8

Claims (1)

[Scope of Claims] 1. A tremie pipe equipped with an on-off valve near its lower end is placed in water with the on-off valve open, and then the on-off valve is closed and water is injected into the tremie pipe to cool the inside of the pipe. After raising the water level, a plunger is slidably fitted in the pipe, concrete is poured in, and the opening degree of the opening/closing valve is adjusted to cause the concrete in the tremie pipe to follow the plunger and descend to the lower end of the pipe. A method of placing underwater concrete that is characterized by allowing the concrete to fall deeper into the water. 2. An underwater concrete placing method as set forth in claim 1, characterized in that when concrete placement is interrupted, the on-off valve of the tremie pipe is closed.