JPH0433929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improvements in tremie pipes for underwater concrete placement.

BACKGROUND ART Conventionally, when constructing concrete structures such as piers and abutments constituting the substructure of a bridge in water, the sea, or muddy water, concrete has been placed in these liquids.

Among this type of construction method, the tremie method using a tremie tube having a hollow cylindrical body is relatively widely adopted. In the tremie method, concrete is usually poured with the tip of the tremie pipe slightly intruding into the concrete that has already been poured, so there is always enough concrete in the column shape inside the tremie pipe to balance the water pressure on the outside. The amount of concrete supplied from the upper end of the tremie pipe is discharged from the tip.

When pouring progresses and the specified amount of concrete has been placed, it is necessary to stop pouring concrete, pull out the tremie pipe, and move it to another location, but the following problems were pointed out at this time: It had been.

In other words, as mentioned above, there is concrete inside the tremie pipe that balances the water pressure on the outside.
Even when the implantation is advanced, it still exists, although the amount is slightly smaller.

Therefore, if you pull out the tremie tube in this state,
The balance between the concrete pressure inside the tremie pipe and the water pressure outside is disrupted, and the heavy concrete tends to fall, and lighter water tries to enter the tremie pipe in its place.

As a result of this replacement, the concrete in the tremie pipe is washed away and separated by the invading water, resulting in significant defects and deposits on the concrete that has already been placed.

As a means of solving this problem, since it is practically impossible to remove the defective part by diving,
A double-pipe structure has been proposed in which the tremie tube consists of an outer tube that is a rigid slit tube and a flexible inner tube, and a leaf spring that opens due to the weight of the poured concrete is attached to the tip of the inner tube.

However, although this double-tube structure tremie tube solves the above-mentioned problem at the time of transfer, it has the following drawbacks.

In other words, water pressure is constantly applied to the flexible inner pipe from the outside from the top to the bottom due to the slits in the outer pipe, which prevents the concrete from falling smoothly through the inside, and the tip receives the highest water pressure. It was difficult to counteract the elasticity of the leaf springs and smoothly discharge the concrete to the outside.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to provide a simple structure for separating concrete when transferring tremie pipes without using special power. To provide a tremie pipe for placing underwater concrete that can be smoothly placed while preventing the above problems.

In order to achieve the object, the present invention is a tremie pipe for underwater concrete pouring, and the tip of the tremie tube is a hollow rectangular shape that is suspended toward a concrete pouring position or pulled up from the concrete pouring position. It has a double-pipe structure consisting of an inner pipe and an outer pipe that can be raised and lowered relative to the inner pipe, and the outer pipe is
When the inner pipe is installed at the casting position, the bottom surface of the outer pipe touches the casting position and rises relative to the inner pipe to reach the highest position, while the inner pipe is placed at the casting position. Before and after it is installed in a certain position, it descends relative to the inner pipe due to its own weight, and the wall body facing the inner pipe has a wall of the outer pipe when the outer pipe is in a position other than the highest position. an inner opening that is closed by an inner wall; an opposing wall of the outer tube has an outer opening that aligns with the inner opening when the outer tube is in its highest position; At the upper edge of each of the inner openings formed, a valve body having a fan-shaped cross section that becomes thicker downward is pivotally supported so as to cover the inner opening. When the valve body is closed by the inner wall, the outer inclined surface of the valve body is regulated by the inner wall of the outer tube, and the inner lower ends of the valve body come into contact with each other, thereby closing the inner tube, and the inner opening and the center of gravity of the valve body is set or biasing means is added so that when the outer openings are aligned, the valve body projects outward through both openings and opens the inner tube, and the lower end of the outer tube The inner pipe is characterized in that an opening is formed in the inner pipe to discharge the underwater concrete filled in the inner pipe to the outside when the inner pipe is opened.

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

FIG. 1 shows an embodiment of a tremie pipe for underwater concrete placement according to the present invention.

This figure is an exploded perspective view of the distal end of the tremie tube, and the distal end of the tremie tube has a double structure of an inner tube 10 and an outer tube 12, both of which are formed into a hollow rectangular shape. The inner tube 10 is connected to the outer tube 12.
The cross section is slightly smaller than that of the inner tube 10, and its distal end enters the outer tube 12 and is locked so that it can move up and down, and a pair of openings are provided on opposing sides of the inner tube 10, A valve body 14 having a fan-shaped cross section is attached to each of the valve body 14 so as to be swingable by hinge-coupling the upper end to the side wall of the inner tube 10, and the arcuate surface of the valve body 14 A flat elastic piece 32 is fixed to each.

On the other hand, the outer tube 12 has stepped portions 16, 16 formed by narrowing opposing side surfaces at a substantially central portion in the axial direction at a predetermined interval in the vertical direction.
A pair of openings 1 are formed by cutting out the space between the stepped portions 16 and 16.
The vertical lengths of these openings 18, 18 are approximately the same as the circular arc diameter of the valve body 14, and the width thereof is approximately the same as the width of the valve body 14.

Further, a flange portion 20 that expands outward is formed at the upper end of the outer tube 12, and the inner tube 10
A stopper piece 22 protruding along the outer periphery of the outer tube 12 comes into contact with the stopper piece 22 , and a claw piece 2 that engages with the hinge part 24 of the valve body 14 is provided on the inner surface near the upper end of the outer tube 12 .
6 is provided protrudingly.

Further, a lower end portion of the outer pipe 12 is provided to prevent the outer pipe 12 from rising together with the inner pipe 10 when the inner pipe 10 installed at the concrete placement position is pulled up. In order to lower the outer pipe 12 relatively, an anchor material 28 is fixed to the outer pipe 12 to prevent upwelling, which protrudes horizontally from the outer pipe 12 and receives the weight or frictional force of the poured concrete.
The tip side walls of 2 are each cut into a substantially U-shape,
Through hole 3 for discharging underwater concrete to the outside
0 is set.

When the inner tube 10 is installed in the outer tube 12 with the above-described structure, the flange portion 20 of the outer tube 12 and the stopper piece 22 of the inner tube 10 are in contact with each other, and the hinge portion 24 of the inner tube 10 and the outer tube 12 are in contact with each other. The inner tube 10 can move up and down between the state in which it engages with the claw piece 26, and
The valve body 14 opens and closes the inner tube 10 as a result of this vertical movement, and its operation will be explained with reference to FIG. 2.

First, as shown in FIG.
6 and the hinge portion 24 of the valve body 14 of the inner tube 10 are engaged, and the outer surface of the valve body 14 is in contact with the inner surface of the outer tube 12. , each valve body 14 is pushed inward and the inner tube 10 is closed.

In this state, even if the inner pipe 10 is filled with concrete to be cast, it will not open. Then, the inner tube 10 gradually descends, and the inner tube 10
At the lowest position where the stopper piece 22 and the flange part of the outer tube 12 contact, the hinge part 2 of the valve body 14
4 comes into contact with a stepped portion 16 provided on the outer pipe 12, and this valve body 14 corresponds in position to an opening 18 that has approximately the same external shape as the outer pipe 12. With the gravity of the bait,
Alternatively, if a spring member (biasing means) for biasing the valve body 14 outward is interposed in the hinge portion 24, the inside of the opening 18 swings outward due to its elastic force.
The inner tube 10 is opened.

Next, a method of placing concrete underwater using the tremie tube having the above-described structure and operation will be described.

FIG. 3 is a schematic diagram showing the process order.

First, install the tremie tube underwater 34, and
0 is filled with concrete 36, and the tremie pipe is suspended by an appropriate means such as a crane (see FIG. 3a).

In this state, the inner pipe 10 is at the highest position in relation to the outer pipe 12 as shown in FIG. There is no possibility for surrounding water to enter.

Further, by filling the inner pipe 10 with concrete 36 and suspending it, the weight of the concrete 36 can be opposed to the buoyant force acting on the tremie pipe, which is extremely convenient.

Next, gradually lower the tremie tube and remove the outer tube 12.
However, when it reaches the submerged ground 38 and is lowered further, the inner pipe 10 becomes the state shown in FIG. 30 in a substantially horizontal direction (see FIG. 3b).

When a predetermined amount of concrete 34 is discharged, the inner pipe 10 is pulled up once and the valve body 14 is closed to stop the discharge, and the outer pipe 12 is raised slightly and the inner pipe 10 is lowered again to place the concrete 34. Continue (see Figure 3c).

In this case, an anchor material 28 for preventing upflow is fixed to the tip of the outer tube 12, and the cast concrete 40 covers the top surface of the anchor material 28, so that when the inner tube 10 is pulled up, the outer tube 12 will be upturned. This will be prevented.

When the pouring of concrete 34 progresses and a predetermined amount of concrete has been poured, it is necessary to transfer the tremie pipe, which is done by stopping the pouring of concrete 34, pulling up the inner pipe 10, and removing the outer surface of the valve body 14. When the inner tube 10 is closed by contacting with the inner surface of the outer tube 12 and the inner tube 10 is further pulled up, the state shown in FIG. The outer tube 12 can be separated from the existing concrete 40 while being filled with concrete 34 sufficient to balance the outside water pressure, and can be smoothly transferred to another pouring site (see FIG. 3 d).

Even during this transfer, since the tremie tube is filled with concrete 34, the buoyant force acting on the tremie tube can be counteracted and the movement can be made smooth.

In the above embodiment, only the distal end portion of the inner tube has been described, but the other portions may have various shapes such as a corner or a circle.

In addition to ordinary concrete, it is of course possible to use a highly viscous concrete to which a mixture for reducing separation is added as the concrete for pouring.

Furthermore, the anchor material 28 fixed to the tip of the outer tube 12 may be provided with a through hole 42 as shown by the imaginary line in FIG. 1 so that the poured concrete can be discharged in the vertical direction. .

As explained in detail in the examples above, the tremie pipe for underwater concrete placement according to the present invention has a simple structure without using any special power, and yet the pipe is filled with concrete when installed and moved. This makes these operations easy and smooth because the buoyant force acting on the tremie tube can be counteracted.

Additionally, when the tremie pipe is transferred, water can be prevented from coming into contact with the concrete remaining inside the pipe by blocking the inner pipe with a valve body, which prevents the concrete from being placed separately and resulting in significant defects. do not have.

Furthermore, since the tremie tube is a rigid hollow body,
Even when surrounding water pressure is applied, the poured concrete inside the pipe can be smoothly discharged, and since the tremie pipe can be opened and closed only by moving the inner pipe up and down, the concrete can be poured quickly.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the distal end of the tremie tube according to the present invention, FIG. 2 is an explanatory diagram of the opening/closing operation of the tremie tube, and FIG. 3 is an explanatory diagram of how to use the tremie tube. 10... Inner pipe, 12... Outer pipe, 14... Valve body,
16...Step part, 18...Opening, 20...Flange part, 22...Stopper piece, 24...Hinge part, 26...Claw piece, 28...Anchor material, 30...
...Through hole, 32...Elastic piece, 34...Underwater, 36...
...Concrete, 38...Ground, 40...Existing concrete.

Claims (1)

[Claims] 1. A tremie pipe for underwater concrete placement, with the tip of the tremie pipe being suspended toward the concrete placement position or lifted from the concrete placement position, and a hollow rectangular inner tube that is suspended from the concrete placement position; It has a double-pipe structure with an outer pipe that can be raised and lowered relative to the inner pipe, and when the inner pipe is installed at the casting position, the bottom surface of the outer pipe comes into contact with the casting position, so that the inner pipe can move up and down. On the other hand, before and after the inner pipe is installed at the casting position, it descends relative to the inner pipe due to its own weight, and the inner pipe's opposite an inner opening that is closed by the inner wall of the outer tube when the outer tube is in a position other than the highest position; forming an outer aperture that aligns with the inner aperture when in position;
At the upper edge of each inner opening formed in the inner tube, a valve body having a fan-shaped cross section that becomes thicker downward is pivotally supported so as to cover the inner opening. When the valve body is closed by the inner wall of the outer tube, the outer inclined surface of the valve body is regulated by the inner wall of the outer tube, and the inner lower ends of the valve body are in contact with each other, thereby closing the inner tube. , the center of gravity of the valve body is set or a biasing means is added so that when the inner opening and the outer opening are aligned, the valve body projects outward through both openings and opens the inner pipe; A tremie tube for placing underwater concrete, characterized in that an opening is formed at the lower end of the outer tube to discharge the underwater concrete filled in the inner tube to the outside when the inner tube is opened.