JPH0833011B2 - How to fill a closed caisson - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a method for filling a closed caisson by water-filling the filled caisson in a closed caisson sunk in the construction of a breakwater, a seawall, etc. Regarding

(Prior Art) Conventionally, as shown in FIGS. 7 and 8, the closed caisson is sunk in a state where the top surface of the caisson body 1 is closed with a top plate 2 and is opened in the top plate 2. Slurry of water and filling sand is sent from the inlet 3 through the injection pipe 4,
Sedimentary sand 5 is settled in caisson body 1 and spillage is added to top plate 2
It is sent back from the drainage port 6 through the return pipe 7 and used again for the slurry. In the figure, 8 is a compartment partitioned by a partition 9, and 10 is a communication hole between the compartments 8 opened in the partition 9.

In this conventional filling method, in the compartment 8a provided with the inlet 3, the slurry flows downward from the inlet 3 at a flow rate of 2 to 4 m / s.
Slurry is injected at a speed of about a degree, and the injected slurry flows through the flow port.
It passes through 10 to the adjacent compartment, and finally drains 6
The spilled water is discharged from the drainage chamber, and in the compartment 8b provided with the drainage port 6, since the drainage port 6 is provided vertically to the top plate 2, the spilled water flowing from the adjacent compartment 8 is drained. Is turned upward and discharged. Then, at the end of filling where the filling has progressed, as shown in FIG. 8, in the compartment 8a provided with the inlet 3, the slurry is injected downward at a considerable speed, so that particles with large mass are deposited. However, most of the particles cannot be deposited and are flowed to the downstream side, so that the state of voids corresponding to the slurry injection amount is maintained. On the other hand, a compartment with a discharge port 6
In 8b, the spilled water flowing from the uppermost circulation port 10 of the adjacent compartment 8 is discharged by changing the flowing direction upward, so that a large turbulence occurs in the flowing water port near the discharge port 6, The void in the limit state is to be maintained.

(Problems to be solved by the invention) In the conventional method as described above, the number of compartments having the inlet and the outlet is about 1/4 of all the compartments, which greatly affects the filling rate of the filling sand. Recently, there is a demand for increasing the filling rate of the compartments at the injection and discharge ports.

In view of such a state, in the present invention, it was noted that the number of outlets in the normal closed type caisson was twice that of the inlets, and the filling of the filling sand in the compartment with the outlets was increased to improve the overall filling rate. The purpose of the present invention is to provide a method of filling a closed type caisson that enhances the product.

(Means for Achieving the Object) The feature of the present invention that achieves the above-mentioned object is to inject the filling sand by water transfer from the inlet opened in the top plate of the closed type caisson, and after the sedimentation of the filling sand. In the filling method of the closed caisson in which the carrier water of the above is drained through the return pipe through the drain port opened in the top plate, and the inside diameter of the drain port is larger than the diameter of the pipe body of the return pipe. And, at the tip of the return pipe is provided with a widened portion having a diameter larger than the pipe diameter of the return pipe main body portion, and the widened side end portion of the widened portion is continuous with the drain port, It is intended that the flow velocity of the carrier water, which is injected together with the filling sand, at the drainage port is slower than the settling speed of the filling sand in still water to fill the filling.

(Operation) In this filling method, when the slurry with filling sand is fed from the inlet, the filling sand is settled and deposited in the caisson, and the residual water is spread from the drain port to the expansion part of the return pipe tip. Returned through the pipe. Then, as the filling progresses and the flow velocity through the drainage port and the expansion part is slower than the settling speed of the filling sand in still water even at the end of filling, there is no large void below the drainage outlet Accumulation is performed and filling with high filling rate is performed.

(Example) Next, the Example of this invention is described about FIGS. The same parts as those in the above-mentioned conventional example are designated by the same reference numerals, and the description thereof will be omitted.

In this method, the top plate 2 of the caisson body 1 is provided with a drain port 11 which is about 5 times as large as the inlet port 3 having an opening cross-sectional area, and a lower end is provided at the tip of the return pipe 7 as shown in FIG. A trumpet-shaped widening part 12 whose opening has the same diameter as the drainage port 11
Is provided, and the tip of the expanded portion 12 is connected to the drainage port 11. Further, the drainage ports 11 are provided at the same positions as the conventional drainage ports 6 in the same number, that is, one at each of the four corners of the top plate 2 of the caisson body 1. Two injection ports 3 having the same diameter as the conventional one are provided in the same arrangement, and the expansion chambers 8a, 8a, 8b are also arranged in the same manner as the conventional one.

When the slurry is injected from the inlet 3 at a flow rate of 2 to 4 m / s in this way, the opening cross-sectional area of each outlet 11 is 5 times that of the inlet 3, and the number of outlets is 2 times. Therefore, the flow velocity is reduced to 1/10, i.e., 0.2 to 0.4 m / s, and the sedimentation speed of the injected stillage sand in the still water is faster than this. Is deposited inside.

The result of filling with the same method as above was as shown in FIG. The numbers in the boxes in the figure indicate the filling ratio (%) of the filled sand in each compartment. From this result, the average filling rate (%) is as follows.

(1) Inlet installation chamber 98.1 (2) Drainage chamber 95.9 (3) Other than the previous period (1) (2) 99.0 (4) All chamber 98.1 In the above embodiment, the return pipe 7 Although the flared portion is shown as the flared portion, the flared portion 12 may be a straight tubular shaped portion having a straightened vertical portion as shown in FIG. 5, or as shown in FIG. As described above, it is also possible to form an expanded portion having a shape in which the entire upper portion of the compartment 8b is raised. The expanded portion may be provided integrally with the return pipe 7 or may be provided integrally with the top plate 2.

(Effect of the Invention) As described above, according to the method of filling the closed caisson of the present invention, the diameter of the drainage port is increased, and the expansion portion is provided at the tip of the return pipe connected to the drainage port. The filling rate of the compartment below the drainage port is remarkably improved even by filling at the same speed as the conventional one, and it is possible to install the caisson with higher stability.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional plan view of a caisson used in the present invention,
FIG. 2 is a longitudinal sectional view of the same, FIG. 3 is an enlarged sectional view of the drainage port portion, FIG. 4 is a caisson plane diagram showing the filling rate of the filling, and FIG.
FIGS. 6 and 6 are sectional views of drainage ports showing other different embodiments, FIG. 7 is a partial cross-sectional plan view of a caisson showing conventional filling, and FIG. 8 is a longitudinal sectional view thereof. . 1 ... Caisson body, 2 ... Top plate, 3 ... Injection port, 4 ...
… Injection pipe, 5 …… Medium sand, 6 …… Drainage port, 7 …… Return pipe, 8,8a, 8b …… Compartment, 9 …… Differential partition, 10 …… Flow hole,
11 …… Drainage port, 12 …… Expansion part.

Front page continuation (72) Inventor Shozo Ikeda 1-11-25 Higashiooi, Shinagawa-ku, Tokyo Goyo Construction Co., Ltd. Technical Research Institute (56) References Japanese Patent Publication No. 63-53333 (JP, B2) Japanese Patent Publication No. Sho 63-53334 (JP, B2) JP-B-63-53335 (JP, B2)

Claims (1)

[Claims] 1. A return pipe for injecting the filling sand by water transfer from an inlet opened in the top plate of the closed caisson, and carrying the carrier water after sedimentation of the filling sand through a drain port opened in the top plate. In a method for filling a closed caisson in which water is drained through, the diameter of the drainage port is made larger than the diameter of the pipe body of the return pipe, and the pipe of the return pipe body is attached to the tip of the return pipe. An expansion part having a diameter larger than the diameter is provided, the expansion side end part of the expansion part is connected to the drainage port, and the flow velocity at the drainage part of the carrier water injected together with the filling sand from the injection port, A method for filling a closed caisson, which is characterized by filling the sand while making it slower than the settling speed of the filled sand in still water.