JPH0762625A - Cylindrical caisson group for construction of breakwater - Google Patents

Abstract

PURPOSE:To realize cost reduction, by effectively adopting precast materials in respect to the construction of a breakwater shielding waves from the offing in order to reduce processes in factory production on the ground and simplify works at site and curtail the construction period. CONSTITUTION:One block of box body 1 is constituted of a flat under floor slab 3, a plurality of cylindrical columns 4 vertically connected on the flat under floor slab 3 so as to mutually contact one another closely, a flat upper floor slab 5 connected with the upper ends of these cylindrical columns 4, and an upper structure 6 supported and fixed on the upper floor slab 5. The block is settled on a mound 2 constructed on the bottom of the sea of the construction site to receive waves on the group of cylindrical columns 4 and dissipate the waves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a group caisson for constructing a breakwater mainly composed of a large number of pillars. More specifically, it is a so-called wave impermeable type in which waves from outside the port are intercepted and shielded by a plurality of pillars. Regarding the group caisson of.

[0002]

2. Description of the Related Art Conventionally, in order to prevent waves coming from the outside of the port and keep the inside of the port quiet, breakwaters for jetties built in the port have been used as revetments built by conventional civil engineering methods, concrete tetrapots, etc. It is well known that the jetty is constructed by stacking the above in the sea, or the caisson is submerged in the sea.

In recent years, in the development of large-scale port facilities and development of offshore artificial islands for sea airports and the like, the construction area of breakwaters tends to expand even further offshore. Therefore, the establishment of efficient construction technology for large-scale breakwaters that can cope with deep water is an important issue. For example, for construction of breakwaters at a deep water depth of over 20 meters, caisson type breakwaters have become the mainstream at present.

[0004]

However, as the size of the facility increases, the size of the caisson also increases, and problems such as the cost of manufacturing caisson on land, the safety of land transportation to the construction site and the safety and cost of marine towing, It is desired to establish new technology that will achieve overall cost reduction, including shortening the construction period.

In view of such circumstances, the present invention relates to an impermeable breakwater for shielding waves, and by efficiently adopting a precast material for constructing a breakwater, the number of manufacturing steps on land is reduced, and on-site construction is simplified. The purpose of the present invention is to provide a group caisson for building a breakwater, which can realize cost reductions by reducing costs and shortening the construction period.

[0006]

In order to achieve this object, a group caisson for constructing a breakwater according to the present invention is a flat plate-shaped lower floor slab and stands on the lower floor slab in close contact with each other. A box made up of a plurality of cylindrical columns installed, a plate-shaped upper floor slab connected to the upper ends of the cylindrical columns, and a superstructure supported on the upper floor slab as one block, and the box is constructed at a construction site. It is constructed so that it is submerged and placed on a mound formed on the sea floor, and the waves are abutted against the cylinder column to shield it.

Further, in the present invention, a cylindrical columnar shape is adopted as the cross-sectional shape of the cylindrical column, which is easy to manufacture and is easy to handle, and the inside of such a cylindrical columnar column can be filled with a filling material.

Further, according to the present invention, the ring-shaped segments, which are subdivided in the height direction, are formed by stacking, and the reinforcing cores are embedded or inserted in the entire circumference of the segments to strengthen the joint with each other, and the reinforcing cores are It is possible to use a cylindrical column in which a plurality of stacked segments are axially tightened by using a PC steel rod having a tensile property as.

[0009]

[Function] A group break caisson is sunk in a predetermined sea area to construct a breakwater. Waves from outside the port collide with and are reflected by a large number of cylindrical columns, so the inside of the port is shielded from waves.

By filling the inside of the cylindrical column with a filling material, reinforcement and stability against external force such as waves can be easily obtained. In addition, by constructing the cylindrical column by stacking a large number of ring-shaped segments by precast molding, manufacturing equipment and the like can be simplified and the construction period can be shortened.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a breakwater building group cylinder caisson according to the present invention will be described below with reference to the drawings.

The group caisson referred to in the present invention is used for constructing a wave-shielding breakwater commonly called "impermeable type", as shown in the conceptual diagram of FIG. It receives and reflects.

FIG. 2 shows a group caisson 1 of an embodiment for constructing one block of a breakwater. The group caisson 1 is placed on a mound 2 formed by foundation work such as floor excavation and dredging on the uneven seabed at the construction site, and further throwing in and discarding foundation stone. That is, there is a lower floor slab 3 to be seated on the mound 2 formed by the seabed formation, and on the lower floor slab 3, a large number of cylindrical columns 4 are formed by a cylindrical cylinder having a length determined in accordance with the water depth of the sea area. Are installed vertically. An upper floor slab 5 is provided at the upper end of the cylindrical column 4, and if the structure from the mound 2 to the upper floor slab 5 is expressed as a substructure, then the substructure is used as a foundation for the upper floor slab 5 to be on the sea surface 7. A superstructure 6 that appears is placed, and a breakwater is constructed by continuously installing the group cylinder caisson 1 composed of these parts in the left-right direction of the drawing.

FIG. 3 is a plan view of the group caisson 1, FIG. 4 is a front view thereof, and FIG. 5 is a side view thereof. The group cylinder caisson 1 of the embodiment is assembled on the ground except for the mound 2 and the superstructure 6, and is manufactured under the assumption that the box caisson 1 is towed at sea and sunk in the field. The structure of each part is as follows.

The lower floor slab 3 is placed on the mound 2 described above. On the upper surface of the lower floor slab 3, a large number of cylindrical columns 4 are in contact with each other and densely arranged, and are vertically provided in a crowd form. in this way,
By providing a large number of cylindrical columns 4 in the form of a crowd, waves are received and reflected by their front portions.

Each of the cylindrical columns 4 is manufactured as a so-called precast member by casting concrete in a formwork at a land-side factory. When the cylindrical columns are formed into cylindrical columns as in the embodiment, the outer diameter dimension is, for example, about 5 m. In the case of submersion at a deep water depth of 20 m at the site both inside and outside, the height dimension H corresponding to this is considerably heavy in itself. At the installation site on the sea, the inside of the cylindrical column is filled with a filling material such as earth and sand as will be described later, and it is reinforced as a basic column member to strengthen and enhance stability against external force due to waves.

Further, a flat plate-shaped upper floor slab 5 is installed on the upper ends of a large number of cylindrical columns 4 and joined by PC steel rods. The structure up to the upper floor slab 5 is manufactured on the land side, and the superstructure 6 is mounted on the upper floor slab 5 at the installation site to assemble the group cylindrical caisson 1.

By the way, as described above, the weight including the internal filler is considerable even if the weight of the cylindrical column 4 alone is large. If this is expected to be 10 or more in one block, the total weight of the cylindrical columns 4 will be The total weight of the group cylindrical caisson 1 in which the lower floor slab 3 and the upper slab 5 are added to the top and bottom of the caisson 1 is considerably large.

Considering the transportability and the safety in long-distance transportation on land, the cylindrical column 4 has various difficulties in terms of weight and form manufacturing, in view of transportability and safety. FIG. 6 shows an embodiment of a small-part assembly structure in which a single cylindrical column 4 itself is taken into consideration in consideration of such a problem caused by single molding.

That is, a ring-shaped segment 10 obtained by subdividing the cylindrical column 4 in the direction of its height dimension H is precast and easily transported from a production plant to a production yard along the coast, where a plurality of segments are provided. It is possible to adopt a method of joining 10 to manufacture a single cylindrical column 4.

As an example, as described above, when the size of the single cylindrical column 4 is to be submerged in a large water depth such as an outside diameter of 5 m inside and outside and a site water depth of 20 m, the height of the segment 10 is increased. If the dimension h is about 1 m, 20 of them are stacked and joined. FIG. 7 shows a mode in which the segments 10 are stacked and the cylindrical column 4 is assembled. At the assembly site, the lower floor slab 3 that serves as a substrate is manufactured by concrete casting in advance, and a PC steel rod 11 as a reinforcing core material is erected by embedding in the lower floor slab 3 within a range along the circumference of the segment 10. ing. If, for example, 20 pieces of the segments 10 are piled up, some of the lower parts are inserted into the PC steel rods 11 and piled on the lower floor slab 3. The through hole 1 into which the PC steel rod 11 is previously inserted in the segment 10 at the stage of the form forming process.
0a is provided. After the PC steel rods 11 are passed through the several segments 10 in order from the bottom, a tension force is applied to the PC steel rods 11 by equipment such as a hydraulic jack, and several lower portions are tightened as a group. The PC steel rod 11 can be replenished with a joint at a predetermined position as needed.

With such joining, 20 segments 1
Stack 0 and join. On the lower floor slab 3, the joined cylindrical columns 4 are in contact with each other and stand upright, but they are assembled in the same manner. These cylindrical columns 4 are installed so that there is almost no gap between them. After assembling the required number of cylindrical columns 4, the upper floor slab 5 is fastened and coupled to the upper ends of the cylindrical columns 4 by utilizing the ends of the PC steel rods 11. The structure so far is the box shown in FIGS.

The box is towed by using a hoist ship (crane ship) or by itself on the sea to the installation site.
It is submerged in the sea at a predetermined position and placed on a mound 2 provided on the sea floor. After the placement, all the cylindrical columns 4 are filled with the filling sand up to the vicinity of the upper floor slab 5. A superstructure 6 is carried and mounted on an upper floor slab 5 exposed on the sea surface, and a one-block group caisson 1 is built. By installing a plurality of this group caisson 1 continuously without a gap, a breakwater of a predetermined length is constructed.

In the embodiment, the cylindrical column 4 has a circular cross section. Since a large number of cylindrical columns 4 are in close contact with each other in a group, when the front surface of each cylindrical column 4 directly receives a wave, the contact surface with the wave increases, which is advantageous in strength.

Other than the above, a segment having a polygonal cross section is possible in consideration of directionality, but from the viewpoint of cost reduction,
A non-directional cylindrical column is also preferable because it is easy to make the members uniform.

Further, considering the mechanical rigidity of the segment 10 forming the single cylindrical column 4 when waves or external pressure is applied during towing, a tensile force acts on the upper and lower ends of the segment 10 and an opposite action occurs on the central part. Since compressive force acts on the upper and lower segments 1,
In the case of 0, it is also necessary to increase the number of reinforcements by the PC steel rods 11 and strengthen the reinforcements, and take preventive measures for avoiding separation of the segments 10 from each other. From these points, segment 1
It is conceivable that 0 is not limited to a single type for assembling one cylindrical column 4, but several types corresponding to the strength of each part may be made into parts as a column.

[0027]

As described above, the group caisson for constructing a breakwater according to the present invention is effective in shielding and canceling waves from outside the port by installing a large number of cylindrical columns in a crowded form.

Further, in the present invention, the main cylindrical column is formed by stacking the ring-shaped segments formed by the precast member, so that it is expected that the caisson manufacturing process and the overall cost reduction due to the drastic shortening of the construction period can be expected.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the concept of a seawater impermeable breakwater according to the present invention.

FIG. 2 is a perspective view showing a form of a group caisson for constructing a breakwater of the embodiment after underwater construction.

FIG. 3 is a plan view of the group caisson of the embodiment.

FIG. 4 is a front view of the group caisson of the embodiment.

FIG. 5 is a side view of the group caisson of the embodiment.

FIG. 6 is a perspective view of an embodiment of a cylindrical segment that forms the main body of a group caisson.

FIG. 7 is a perspective view showing an assembly mode of the cylindrical segment shown in FIG.

[Explanation of symbols]

1 ... Group tube caisson, 2 ... mound, 3 ... lower floor,
4 ・ ・ Cylinder pillar, 5 ・ ・ Upper floor, 6 ・ ・ Superstructure, 7 ・ ・ Sea surface, 10 ・ ・ Segment, 11 ・ ・ PC steel rod.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideyuki Kitamura 2-10-10 Fujimi, Chiyoda-ku, Tokyo Maeda Construction Industry Co., Ltd. (72) Yasuhiro Ueda 2-26-10 Maeda, Fujimi, Chiyoda-ku, Tokyo Construction Industry Co., Ltd.

Claims (6)

[Claims] 1. A flat lower floor slab, a plurality of cylindrical pillars which are in contact with each other on the lower floor slab so as to be densely erected, a flat upper floor slab connected to an upper end of the cylindrical pillar, and an upper floor. A box consisting of a superstructure supported and bonded on the plate 1
A group caisson for building a breakwater, characterized by placing a box as a block on a mound formed on the sea floor of a construction site and placing it on it to abut a cylindrical column to block waves. 2. The cylindrical column is cylindrical with a circular cross section.
Group caisson for building breakwater as described. 3. The group caisson for constructing a breakwater according to claim 1, wherein a filling material is filled inside the cylindrical pillar. 4. A cylindrical column is formed by stacking ring-shaped segments that are subdivided in a height direction, and a reinforcing core material is embedded or inserted into the entire circumference of the segment to strengthen the joint with each other. A group caisson for building a breakwater according to any one of 1. 5. The group caisson for constructing a breakwater according to claim 4, wherein the reinforcing core material is a PC steel rod having a tensile property, and the stacked segments can be clamped in the axial direction. 6. A breakwater building cylinder column, which is formed by stacking ring-shaped segments that are subdivided in the height direction, and in which a reinforcing core material is embedded or inserted in the entire circumference of the segment to strengthen the joint with each other.