JPS6080626A - Multi-stage stacked caisson and its construction - Google Patents

Abstract

PURPOSE:To make easier operations on site by a method in which an upper stage caisson is stacked up on a lower stage caisson, and a continued prestressed steel material is vertically thrust through the upper slab of the lower stage caisson and the bottom slab of the upper stage caisson and clamped tightly. CONSTITUTION:A lower stage caisson 1 with a float 15 is floated on water and then sunk to a given depth from water surface by charging water into the caisson 1. An upper stage caisson 3 is sunk onto the caisson 1 while charging water into the caisson 3, and the coupling projection 4 of the caisson 1 is fitted into the coupling recession 5 of the caisson 3. The bouyancy of the caisson 1 is increased while discharging water inthe caisson 1, and the caisson 3 is stacked up on the caisson 1. After discharging water from the caisson 3, a prestressed steel material 7 supported on the upper slab of the caisson 3 is thrust through the hole 22 of the bottom slab 3A of the caisson 3 and clamped fightly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-tiered caisson embankment constructed by stacking caissons on the seabed, and a method for constructing the same.

Conventionally, when constructing a caisson embankment, the upper and lower caissons were connected by first lowering and fixing the lower caisson 1 on the seabed ground 2, and then pouring water into the upper caisson 3 while attaching the suspension wires, as shown in Figure 1. This was done by letting them settle while loosening, stacking them on the lower caisson 1, and fitting the joint projections 4 provided on the upper surface of the lower caisson 1 with the four joint parts 5 provided on the lower surface of the upper caisson 3.

However, such a joining method has the following drawbacks.

(b) To place the lower caisson 1 on the seabed ground 2,
It is necessary to remove the unevenness of the seabed ground 2, and the seabed ground m
2 has the disadvantage that support strength commensurate with the weight of the caisson is required.

(b) The work is mainly done on-site and has the drawback of being easily influenced by sea conditions such as waves and weather.

(c) In a multi-tiered caisson embankment, it is common to use the embankment's own weight to resist sliding and overturning.The cross section of the embankment body is determined by the magnitude of the design load, so if the design load is excessive, the upper stage Caisson 3 also requires a large cross-sectional area, which is uneconomical.

The object of the present invention is to be able to join the upper and lower caissons without being affected by the topography of the seabed, to select a location that is not affected by weather or sea conditions, and to connect the upper caissons. An object of the present invention is to provide a tiered caisson embankment capable of suppressing an increase in area and a method for constructing the same.

The gist of the present invention for achieving the above object is, firstly, an upper caisson is superimposed on a lower caisson, and a joint protrusion protruding from the upper plate of the lower caisson and a bottom plate of the upper caisson. A multi-tiered caisson embankment in which continuous prestressed steel is vertically penetrated through the upper plate of the lower caisson and the bottom plate of the upper caisson and fixed under tension. A caisson which is located on the embankment and which is joined by stacking the upper part on the lower part and fitting the joint protrusion protruding from the upper part of the lower caisson and the joining recess provided in the bottom part of the upper part caisson. In the joining method, prestressed steel members are suspended in advance at multiple locations on the upper plate of the lower caisson, and a bearing block, a bearing plate, and the like are preliminarily attached to the lower end of each prestressed steel member in the lower caisson. The lower caisson is floated on the water, and with the floating means attached to the lower caisson, water is poured into the lower caisson and the lower caisson is submerged to the required water depth. The upper caisson is held in a suspended state in the water by the floating means, and the upper caisson is lowered onto the lower caisson while water is poured into the upper caisson.
fl The lower caisson is drained by fully fitting the joint recesses 2 to increase buoyancy and the upper caisson is stacked on the lower caisson, and then the upper caisson is drained and the inside of the upper caisson is drained. With the water almost empty, each of the prestressed steel members, which had been previously suspended and supported on the upper plate of the lower caisson, was pulled up into the upper caisson through one hole previously drilled in the bottom plate of the upper caisson. A method of constructing a multi-tiered caisson embankment, which is characterized by performing tying work using

Next, embodiments of a multi-tiered caisson embankment and a method of constructing the same according to the present invention will be described in detail with reference to the drawings. First, in the present invention, as shown in FIG. 2, a plurality of through holes 6 are provided in advance in one upper plate of the lower caisson 1, and using these through holes 6, the upper plate IA is prestressed (hereinafter abbreviated as pc). )
Each is suspended and supported by the steel material 7. The PC steel material 7 of this embodiment has a structure in which a PC copper wire 7B is accommodated within a sheath pipe 7A. At the lower end of the PC steel material 7, there is a bearing block 8 crimped to the lower end of the PC steel wire IB, and a bearing block 8 that is crimped to the lower end of the PC steel wire IB.
A bearing grating 9 supported on a bearing block 8 fitted on the outer periphery of B, and a grout receiving mold frame 11 supported entirely below the bearing plate 9 through a support member 10 such as a round steel. Each is provided in advance. A temporary cover 12 is attached to the upper end of the PC steel material γ in advance, and when this temporary cover 12 is locked to one upper plate of the lower caisson 1, the PC steel material 7
- Clothes are suspended and supported by one person. A ring-shaped gasket 13 is previously attached to the upper surface of the upper plate 1A so as to surround the temporary lid 12 which is secured to the upper plate.

The lower caisson 1 is floated in the water, and a plurality of floating means 14 consisting of a cylinder 14A and a floating body 14B attached to the upper surface are attached to the upper surface of the lower caisson 1, as shown in FIG. The lower caisson 1 is submerged to a required water depth while water 15 is injected into the caisson 1, suspended in the water by the buoyancy of each floating means 14, and maintained in that state. floating body 1
4B is moored with anchor 1γ via mooring rope 16.

Next, the suspension 9 wire 2 of the crane 19 of the crane ship 18
0, suspend the upper caisson 3, pour water 21 into it and lower it onto the lower caisson 1, fit the joint 4 parts 5 of the upper caisson 3 onto the joint protrusions 4 of the lower caisson 1, and then The lower caisson 1 is drained to increase buoyancy and the upper caisson 3 is stacked on the lower caisson 1.

In this state, as shown in FIG. 4, the through hole 6 pre-drilled in the upper plate of the lower caisson 1 and the through hole 22 pre-drilled in the bottom plate 3A of the upper caisson 3 are aligned; The gasket 13 of the upper plate 1A of the lower caisson 1 is brought into contact with the bottom plate 3A of the upper caisson 3 to prevent seawater from entering the through hole 6.22. In this state, the upper caisson 3 is drained, and the water 21 inside the upper caisson 3 is drained.
■Empty state, and insert the dial into the upper caisson 3.
Open the temporary cover 23 blocking the through hole 22, and insert the PC steel material 7 suspended from the upper plate of the lower caisson 1 into the through hole 2.
2 and lift it into the upper caisson 3. The lifted PC@wire 7BKI4 is temporarily tensioned by applying tension, and is temporarily fixed with a fixing fitting 25 via a bearing plate 24 as shown in FIG. In this state, the bearing plate 9 at the lower end of the PC steel material γ is in contact with one upper plate of the lower caisson 1, and the upper end of the grout receiving form 11 is also in contact with one upper plate of the lower caisson 1. Ru. After the primary fixation of all PC steel materials T has been completed, main tension is applied to each PC steel wire γB to ensure complete fixation.
The upper end of each PC steel wire 7B is cut at a predetermined position. Thereafter, grout 26 is injected into the through hole 22 from a grout injection hole (not shown).

This grout 26 is filled into the through holes 22, 6 and also into the grout receiving mold frame 11 at the lower end. The fixing fitting 25 at the upper end is covered with mortar 2T.

After the joining work of the upper and lower caissons 1.3 is completed, these caissons 1.3 are towed to the site by a towboat, and the upper and lower caissons 1, 3 are filled with sand and the like and are sunk in the installation location.

In particular, when the lower caisson 1 and the upper caisson 3 are joined together using the PC steel material γ in this manner, the relaxation caused by the tension of the PC steel material γ can be effectively utilized. That is, PC
When tensioning the steel material 7, the tension is reduced due to loosening during fixation, creep of concrete, etc. Therefore, it is common to consider prestressing losses in advance, but
The value is multiplied by the design prestress, and PC@
The material 7 is required to have a strength greater than that of the cladding, which is uneconomical.

On the other hand, in the case of the present invention, when a horizontal force due to waves or the like acts on the upper caisson 3, a tensile force due to the horizontal force is applied to the PC steel material T in addition to the tensile force due to the tension. Therefore, it is necessary to use a PC steel material 7 that can withstand drawing tension. In this way, the PC steel material 7 used for multi-tiered caissons such as two-tiered caissons has the disadvantage that it is necessary to take into account the increase in tensile force due to horizontal force in the set proof strength, and that the prestress loss due to relaxation is large. be. In order to reasonably satisfy this in terms of design, prestress)
The required tensile strength tt'i due to tN incontinence and horizontal force may be approximately equal. In this way, it is possible to compensate for each other's weaknesses, and it can be effectively used in the entire relaxation design, and the uneconomical nature of the PC steel material 7 can be prevented.

In the above embodiment, the caissons are stacked in two stages, but the present invention can be similarly applied to multi-stage stacking of two or more stages.

As explained above, in the caisson joining method according to the present invention, the lower caisson is joined while suspended in the water by a floating means without touching the bottom of the water. There are benefits that go beyond these factors. Further, according to the Hiko joining method, the work can be performed in a yard such as a bay or an inlet, and the joining work can be performed without being affected by weather or sea conditions. Therefore, field work is greatly shortened, and when applied to a breakwater, it becomes possible to construct it far offshore. Furthermore, in the present invention, since the upper and lower caissons are joined by a PC steel material, the tensile strength of the PC steel material can be expected, and most of the resistance against overturning can be borne entirely by the PC steel material.

In addition, the tension of the PC steel material is added to the weight of the upper caisson, so an increase in the frictional resistance against sliding of the upper caisson can be expected, and an increase in the resistance moment against overturning. As a result, there is no need to increase the cross-sectional area of the upper caisson to resist sliding or overturning of the upper caisson, and there is an advantage that the upper caisson can be manufactured with an economical cross-sectional area. Furthermore, according to the present invention, by making the prestress loss of the PC steel material approximately equal to the required tensile strength due to the horizontal force acting on the upper caisson, it is possible to compensate for each other's weaknesses, and to effectively improve the relaxation of the PC steel material. It can be used to prevent the polyeconomics of PC steel materials. Moreover, in the present invention, the PC steel material is suspended and supported from the upper part of the lower caisson in advance, so there is no need for workers to enter the lower caisson during the joining work, and work safety is ensured. I can do it. °In addition to the bearing block and bearing plate, the grout receiving form is supported in advance under the PC steel material, so tensioning and fixing work can be done quickly.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view showing a conventional upper and lower caisson connection state, Fig. 2 is a cross-sectional view of a main part showing a state in which the PC steel material is suspended from the upper plate of the lower caisson used in the present invention, and Fig. 3 is a cross-sectional view of the main part showing the state in which the PC steel material is suspended from the upper plate of the lower caisson used in the present invention. FIGS. 4 and 5 are explanatory diagrams showing an example of the implementation state of the caisson joining method according to the present invention, and are sectional views of essential parts required for the joining process of upper and lower caissons according to the present invention. 1...Lower caisson, 1 person...Upper version, 3...Upper caisson, 4...Joint protrusion, 5...Joint recess, 6...
...Through hole, 7...PC steel material, 7A...Sheath pipe,
7B...pc copper wire, 8...bearing block, 9...
bearing pressure plate, 10... support material, 11... grau)
, TFL receiving mold, 12... Provisional payment, 13... Gaskent, 14A... Cylinder, 14B... Floating body, 14...
Floating means, 15...water, 16...mooring, 17...
・Anchor, 18... Crane ship, 19... Crane, 21... Water, 22... Shell hole, 23... Temporary cover, 2
4... Bearing pressure plate, 25... Fixing metal fitting, 26...
Grout, 2T ^ mortar. Patent applicant: Pentayo Construction Co., Ltd. Ear implantation Patent attorney: Isao Sasaki

Claims (2)

[Claims] (1) In a multi-tiered caisson embankment in which the upper caisson is stacked on the lower caisson and joined by fitting the joining protrusion protruding from the upper version of the lower caisson to the joining recess provided on the bottom version of the upper caisson. , a multi-tiered caisson embankment formed by penetrating and tension-fixing continuous prestressed steel members from the top and bottom of the upper plate of the lower caisson and the bottom plate of the upper caisson. (2) Stack the upper caisson on the lower caisson,
In the caisson joining method described in II, in which the joint protrusion protruding from the upper plate of the lower caisson and the four joint parts provided at the bottom plate of the upper caisson are fitted and joined, the upper plate of the lower caisson is Prestressed steel materials are suspended in advance at a plurality of locations, and grout receiving molds are supported in addition to the bearing plates and the bearing plates in the lower caisson, and the lower caisson is floated on the water. With the floating means attached to the lower caisson, the lower caisson is injected with water, the lower caisson is submerged to a required water depth, and suspended in the water by the floating means, while the upper caisson is injected with water. The upper caisson is lowered onto the lower caisson, and the lower caisson is drained by fitting the joint recess onto the joint protrusion to increase floating, and the upper caisson is placed on the lower caisson. Next, the upper caisson is drained to empty the water and metal in the upper caisson, and the prestressed steel members, which were previously suspended and supported by the upper plate of the lower caisson, are removed from the bottom plate of the upper caisson. A method for constructing a multi-tiered caisson structure, which comprises lifting each member into the upper caisson through pre-drilled holes in the upper caisson for tightening work.