JPS6338502B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for submerging an open caisson. This method relates to a construction method in which the internal pressure generated by the body's own weight is applied as a reaction force, thereby balancing the body's own weight and the reaction force to prevent excessive settlement of the body, while raising partitions and gradually sinking the body.

[Problems to be solved by conventional technology and invention]

Open caissons, which have a cylindrical body with a vertically penetrating interior, have the problem of excessive settling of the body when submerged in soft ground or on the seabed. In particular, when installing an open caisson on the seabed,
There is a risk that the crane ship will not be able to lower the structure to the specified depth due to its limited lifting capacity, and that the structure may sink too much due to the soft layer on the ocean floor.

The conventional open caisson construction method lacks effective measures to prevent excessive settlement of the structure.
Submerged construction was carried out because excessive subsidence was unavoidable. Therefore, in the conventional technology, it has been an unsolved problem to sink an open caisson while preventing excessive settling of the frame.

Therefore, an object of the present invention is to provide a construction method for safely sinking an open caisson whose scuttling length cannot be predicted, or an open caisson frame that is likely to sink excessively, to a predetermined depth. The object of the present invention is to provide a construction method that can achieve the above object with simple equipment and processes.

[Means to solve the problem]

In this invention, a partition consisting of a partition main body and a sealing material attached to the periphery of the main body is temporarily provided in the frame of an open caisson so as to be able to slide upwardly, and the inside of the frame is isolated from above and below, and the partition is By applying the internal pressure generated by the body weight of the building body as a reaction force to the lower surface, this partition can be relatively raised within the building body while balancing the body weight and the reaction force and preventing the building body from sinking excessively. This is an open caisson construction method that weakens the reaction force exerted on the lower surface of the partition and gradually sinks the frame.

[Effect]

The internal reaction force received at the bottom of the partition is gradually weakened by raising the partition relative to the structure, and the structure of the open caisson gradually sinks, so the structure can be over-settled even on the seabed or other soft ground. It is possible to sink to a predetermined depth without any problems.

〔Example〕

Next, the present invention will be explained with reference to illustrated embodiments. 1 to 4 are diagrams showing a first embodiment of the present invention.

1 in Figure 1 is the frame of the open caisson,
The state where this is submerged on the seabed 3 is shown. Inside the frame 1, there is a partition 2 that blocks the inside of the frame 1 from above and below.
is temporarily installed, and its lower surface receives the internal pressure generated by the weight of the frame 1 as a reaction force. The partition 2 consists of a partition main body 2a and a sealing material 2b attached to its periphery, and is slidable along the inner surface of the frame 1. A wire cable 4 whose lower end is fixed to the frame 1 is inserted through the partition 2. The tension of the cable 4 supports the reaction force that the partition 2 receives. 5 is a center hole jack installed on the top surface of the partition 2, and a wire cable 4
is held, and the partition 2 is raised and lowered by its operation. Reference numeral 6 denotes a center hole jack installed on a bracket 7 on the inner surface of the frame 1, and the partition 2 is lifted up by a steel rod 8 suspended between the center hole jack and the bracket 7. In addition, an air supply pipe 9 and an exhaust pipe 10 that communicate with the lower part of the partition 2 penetrate therethrough,
Both pipes 9 and 10 extend outside the frame 1. Both pipes 9,
At 10, on-off valves 9a and 10a are arranged.
1a is the sea surface outside the body 1, 11b is the sea surface inside the body 1, 12 is a sheath pipe, and 13 is a grout pipe.

FIG. 2 is an example of the sealing material 2b in FIG. 1,
Figure A shows an example in which a pressure chamber 2c is formed in the center of the sealing material 2b. 14 is stainless steel plate, 15
Numerals 16 are bolts and nuts for fastening the sealing material 2b to the partition main body 2a, and 16 is a seat plate, the inner surface of the frame 1 being coated with paraffin. Figure B is an example in which the pressure chamber 2c in Figure A does not exist in the seal 2b, and the others are A.
Same as figure.

FIG. 3 is an enlarged view of the part of the partition 2 through which the wire cable 4 passes, where 4a is a wire constituting the wire cable 4, 17 is an oblique pressure receiving plate for the wire 4a,
18 is a seal box, and 19 is urethane rubber for sealing.

In the state shown in Fig. 1, the lower end of the frame 1 has plunged into the seabed 3, and a cutting edge with an inwardly tapered surface and a sharp tip is formed at the lower end of the frame 1. Therefore, the main body 1
The earth and sand is guided by the tapered surface and enters the frame 1 by the volume of , and this entered earth and sand rises inside the frame 1. Air is trapped on the lower side of the partition 2, and the trapped air is compressed by the weight of the frame 1 and becomes high pressure, which acts on the lower surface of the partition 2 as a reaction force of the weight of the frame 1. In this way, the weight of the frame 1 and the reaction force applied to the lower surface of the partition 2 are balanced, so the frame 1 is at rest in the state shown in FIG. 1. Because of the earth and sand that has built up inside the frame 1, the sea level 11b is pushed up higher than the sea level 11a.

Therefore, when the body 1 is made to sink, if the reaction force applied to the lower surface of the partition 2 is reduced, the balance between the reaction force and the body weight of the body 1 is lost, and the body 1 sinks until the two balance again. In order to reduce the reaction force that the lower surface of the partition 2 receives, the partition 2 may be relatively raised to reduce the air pressure below the partition 2.

The partition 2 is raised by operating the center hole jack 5. Center hole jack 5
The upper and lower grippers are respectively provided with grippers, and the wire 4a of the wire cable 4 is alternately held by the upper and lower grippers, and when the lower gripper is held, the upper gripper is raised. That is, FIG. 4 shows the procedure. First, as shown in Figure A, the lower gripper B is fixed on the wire 4a, the upper gripper A is released, and in this state, the gripper A is raised. Then, gripper A is fixed on the wire 4a, and gripper B is released. This state is shown in Figure B, and when the gripper A is lowered here, the wire 4a is lowered together. There, Gritsupa B is fixed. By repeating this process an appropriate number of times, the wire 4a is lowered by a predetermined distance.

Looking at this in FIG. 1, since the portion of the wire cable 4 below the partition 2 becomes longer, the partition 2 relatively rises within the frame 1 due to the reaction force acting on its lower surface. Then, since the space below the partition 2 is expanded, the internal pressure is lowered, the reaction force applied to the lower surface of the partition 2 is reduced, the weight of the frame 1 overcomes the reaction force, and the frame 1 sinks due to its own weight. Due to this sinking, the partition 2 also sinks, compressing the air below it, and this pressure acts as a reaction force on the partition 2.
It acts on the lower surface and is balanced with the body weight of the body 1, so that the body 1 stops sinking.

At this time, the dead weight of the frame 1 is the sea level 11a, 11b
This means the self-weight under the influence of buoyancy in relation to the position of
Based on the fact that the part that acts on the removal of seawater in the entire volume of the body 1 is only a part and the buoyant force acting on the body 1 is small, the buoyant force acting on the body 1 is determined by the method described above. Does not adversely affect subsidence.

In this way, the above-mentioned procedure is repeated to sink the frame 1 to a predetermined depth, and then fix the frame 1 if necessary.

〔Effect of the invention〕

As is clear from the above, according to this invention,
A partition is temporarily installed inside the frame of an open caisson to isolate the upper and lower parts of the frame, and internal pressure generated by the body's own weight is applied as a reaction force to the bottom of this partition, making it possible to prevent the frame from over-sinking even on the seabed or other soft ground. It is possible to accurately lower the building frame to a predetermined depth one after another without having to do so. Since the subsidence work can be accomplished by a simple method of relatively raising the partition within the structure, there is an effect that the structure can be safely and easily sunk to a predetermined depth.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of the present invention, and FIG. 2 is an enlarged view of the sealing material portion of FIG. 1, where A shows one example, B shows another example,
FIG. 3 is an enlarged view showing the relationship between the partition and the wire cable in FIG. 1, and FIG. 4 is an explanatory diagram of the operation of the center hole jack. In addition, in the figure, 1 indicates a frame and 2 indicates a partition.

Claims (1)

[Claims] 1. A partition consisting of a partition main body and a sealing material attached to the periphery of the main body is temporarily installed inside the frame of an open caisson so as to be able to slide upwards to isolate the inside of the structure from above and below, and at the same time, on the bottom surface of the partition, By applying the internal pressure generated by the body's own weight as a reaction force, the body's own weight and the reaction force are balanced, preventing excessive settling of the body, and by raising this partition relatively within the body. A construction method for open caissons that is characterized by gradually sinking the structure by weakening the reaction force applied to the lower surface.