JPH09302669A - Caisson installation construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide techniques in which placement of a foundation pile can be performed at high precision, installation for sinking a caisson can be performed at high precision, and the caisson can be kept in a stable condition by a template. SOLUTION: In driving plural foundation piles 3 on the seabottom ground on which a caisson 1 is to be installed, and installing the caisson 1 on the foundation piles 3 to be fixed, a template 4 as a steel structure having functions of a scale in driving the foundation piles 3, and a bearing plate in sinking the caisson is sunk before driving of the foundation piles 3. In sinking the template 4, a process of preliminarily driving plural support piles 10 for supporting the template 4 at a specified position where the template 4 is to be sunk, a process of driving plural foundation piles after sinking the template 4 using the template 4 as a scale, and a process of sinking the caisson on the template after driving the foundation piles to be installed are performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caisson installation method, and more particularly to a technique for installing and fixing a large steel shell caisson used for construction of artificial islands, etc., on a plurality of foundation piles driven into the seabed. It is a thing.

[0002]

2. Description of the Related Art For example, in the construction of a huge marine structure such as an artificial island, a giant steel shell caisson may be used in place of a general concrete caisson used for construction of a quay or a seawall. . This steel shell caisson itself,
It is usually formed in the shape of a hollow box with an open top.

As a conventional caisson installation method, a method of forming a waste stone mound on the sea floor and laying it on the mound is usually employed. However, in places where the water depth is deep, the tidal current is fast, and the bearing strength of the ground surface of the seabed is not sufficient, a foundation pile that reaches the support layer of the seabed is placed, and a caisson is installed and fixed on the foundation pile. It may be desirable to adopt a construction method.

[0004]

However, in order to carry out the method of supporting a caisson using a foundation pile as described above, there are some problems to be solved particularly in the following points. Firstly, the foundation piles must be laid with high precision in deep sea areas and fast tidal currents, and in large steel shell caissons, the foundation piles required to support them. Since the number of pilings is also considerable, the practicing work involves considerable difficulty.

Secondly, it is necessary to secure the accuracy when the caisson is sunk and installed on a large number of piled foundation piles. That is, it is necessary to mount the caisson so that the bottom of the caisson is exactly aligned with the head of each foundation pile. However, if the method of installing the caisson directly on the foundation pile is adopted, not only will it be difficult to align a large number of foundation piles with the caisson, but also a sufficient connection between the caisson bottom and the foundation pile head. It is difficult to create a structure that provides strength.

Thirdly, when the caisson is sunk, the caisson itself will not be unstable under the influence of tidal currents and waves for a certain period until the work of connecting the caisson bottom and the foundation pile head is completed. It is necessary to keep this stable on the foundation pile. From this point as well, it is difficult to stably support the caisson to the foundation pile by the method of installing the caisson directly on the foundation pile.

Fourth, in addition to securing the accuracy of placing a large number of foundation piles and the accuracy of installing caisson, etc., to the extent possible, the efficiency and workability of those operations are improved, and the construction cost and construction period are reduced. It is necessary to plan.

The present invention has been made in consideration of the above points, and a base pile is prepared after a template, which is a steel structure having a function as a ruler for placing a foundation pile and a saucer at the time of caisson digging, is laid down. By adopting the construction method of placing the caisson on the template and digging the caisson on the template, it is possible to place the foundation pile with high accuracy, and the installation accuracy accompanying caisson erection can be performed with high accuracy. , It is an object of the present invention to provide a technique capable of keeping a caisson in a stable state by a template when the caisson is submerged.

[0009]

In order to solve the above problems, in the present invention, when a plurality of foundation piles are driven on the seabed where the caisson is to be installed, and the caisson is installed and fixed on the foundation piles, Each of the steps A, B, C and D is performed. A A process of laying a template, which is a steel structure, that has the function of a ruler for laying foundation piles and a saucer when laying caisson before laying foundation piles. A step of preliminarily placing a plurality of support piles for supporting the template at a predetermined position where the template is to be laid when the template is laid. C A step of placing a plurality of foundation piles using the template as a ruler after the template is sunk. D The process of staking and installing caisson on the template after placing the foundation pile. Here, before the template is sunk, it is also possible to drive a guide pile used for ensuring accuracy when the template is sunk. It is also possible to attach a support member for receiving the template to the support pile and the guide pile. It is also possible to provide a guide device having a bevel around the template for guiding the bottom of the caisson to a fixed position on the template when the caisson is sunk. further,
After the caisson is set down, it is preferable to place an underwater concrete for connecting the caisson and the foundation pile.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the accompanying FIGS. 1 to 5 are process diagrams showing a caisson (steel shell caisson) installation method according to the present invention, FIG. 6 is a schematic plan view of a template, FIG. 7 is a side view of a guide device, and FIGS. Is a view showing a mounting structure of a support member, FIGS. 10 and 11 are a plan view and a side view showing a procedure for constructing a guide pile, and FIGS. 12 and 13 are a side view and a plan view showing a procedure for lifting a template.

Before describing the caisson installation method according to the present invention, first, the caisson structure and fabrication will be briefly described with reference to FIG. The caisson 1 is a so-called steel shell caisson in which a large number of large and small H steels are used for the framework and steel plates are used for the side plates, and is formed in a hollow inner box shape. The caisson 1 has an upper surface open, and the interior is divided into three chambers by two partition walls 2 parallel to each other. The lower part of the partition wall 2 is not provided in a portion where a slab concrete to be described later is poured. That is, the partition 2 has a structure rising from the bottom slab concrete. The size of the caisson 1 is several tens of meters or more in length, width, and height, respectively.

Caisson 1 having such a structure and size
Is manufactured, for example, using a dry dock of a shipyard. Thereafter, the caisson 1 is towed and moored to a quay or the like suitable for the concrete placement work, and the bottom concrete C is placed in the caisson 1. The structure and function of the slab concrete C will be described in more detail with reference to the cross-sectional view of FIG. 5. The caisson 1 will be towed to the intended setting location after the slab concrete C has been cast, and then the caisson 1 will be towed there. Will be sunk. At the time of this submersion, the template 4 is supported by the head part of the support pile 10 previously constructed, and the caisson 1 is set and fixed on the template 4. Template 4 is
The structure is integrated with a large number of foundation piles 3 including support piles 10 by pouring underwater concrete, and the head of each foundation pile 3 penetrates the template 4 and faces the caisson 1.

Therefore, a large number of voids 5 are formed in the bottom slab concrete C for drawing in the heads of the foundation piles 3, respectively. These cavities 5 are provided in advance when the caisson is manufactured, and are sealed with a watertight lid (not shown) until the caisson 1 is completely settled, so that the caisson 1 itself has a function as a hull. In FIG. 5, reference numeral 6 is a portion for placing pile head connection concrete, 7 is a gasket, 8a,
8b is a side wall, 9 is an upper floor beam.

Next, the method of installing the caisson 1 will be specifically described. First, as shown in FIG. 1, a support pile 10 for supporting the template 4 and a guide pile 20 for guiding the template 4 when the template 4 is sunk are driven on the seabed G. The number of the support piles 10 to be driven is determined according to the size and strength of the template 4. At least four or more support piles 10 are driven so that the template 4 can be stably supported near the seabed.
Although the structure and function of the template 4 will be described later, as shown in FIG. 6, the overall structure is a frame steel structure having a plane lattice shape.

On the other hand, as for the guide piles 20, at least two guide piles 20 are driven near both ends of the template 4 in the longitudinal direction. At this time, it is preferable that both guide piles 20 and 20 be considered so as to be located at the center position in the width direction of template 4. Since the guide piles 20 are used as guides when the template is sunk, the heads (upper ends) of the guide piles 20 are set to have a length protruding above the sea surface.

Further, the head of the support pile 10 and the guide pile 2
Bearing members (brackets) 11 and 21 for receiving the lower surface of the template 4 are attached to the outer peripheral portion of 0, respectively. These bearing members 11 and 21 should be at the same level as each other. The support member 21 of the guide pile 20 is fixed to the outer peripheral portion of the guide pile 20 by means such as underwater welding as shown in FIG. 8, but the support member 11 of the support pile 10 is shown in FIG. As shown in (b) and (c), it is preferable that the structure is fixed on the head of the support pile 10. This is advantageous in terms of structural strength and workability.

Each of the support members 11 and 21 is designed to be sufficiently larger in plan view than the outer diameters of the support pile 10 and the guide pile 20 located at the center. This is to ensure that a sufficiently large pressure receiving area can be obtained for stably supporting the template 4. Guide pile 2
In the case of the support member 21 attached to 0, here, the H-shaped steel 21a is assembled in a grid shape, and the diagonal member 21 as a reinforcing material is further used.
b, a support bracket 21c is added. Further, in the case of the support member 11 attached to the support pile 10, the H-shaped steel 11a is assembled in a grid shape, and the cross-shaped receiving member 11b mounted on the head of the support pile 10 is interposed between them.

However, in the case of this support member 11, the support pile 1
Since it is mounted on the head of 0, it exerts sufficient strength against a vertical load, but with respect to the force that moves in the horizontal direction, simply attaching both members by welding will increase the strength. Anxiety remains. Therefore, in this embodiment, FIG.
As shown in FIG. 9 (b) which is an enlarged view of the portion A of FIG. 9 (a) and FIG. 9 (c) which is a view taken in the direction of arrow C, on the lower flange side of the cross-shaped receiving member 11b made of H steel, , Support pile 10
The restraint plate 12 is welded at least at four places to the portion where the upper edge of the above hits. In each restraint plate 12,
A slit 12a into which the upper edge portion of the support pile 10 fits is provided, and this structure is configured to mechanically restrain the horizontal movement of the support member 11.

By the way, when the template 4 is used in this manner, the installation accuracy of the caisson 1 depends on the installation accuracy of the template 4. The template 4 has a structure in which it is received by the support members 11 and 21 welded to the support pile 10 and the guide pile 20, and it is possible to absorb the construction error in placing the support pile. However, the guide pile 20 needs to be driven with high precision in view of its construction purpose. In that sense, how to make a guide pile 20 on the sea where there is no fixed point
The important point in construction is how to improve the placement accuracy. In order to ensure the accuracy, as a "guide" for driving the guide pile 20, for example, a method of driving three guide piles per guide pile can be adopted.

FIGS. 10 and 11 show the procedure for driving the guide pile 20 after driving the three guide piles. That is, in the vicinity of the sea area where the guide pile 20 is to be installed, first, the guide piles 30, 30, 3 are placed at the positions of the apexes of the triangle.
0 are respectively driven, and the guide piles 30 are connected by the connecting members 31, 31, 31 made of H steel or the like. further,
Conductive materials 32, 32, which are also made of H steel and extend substantially horizontally and parallel to each other on the connecting material 31, and the conductive material 3
The conductors 33 orthogonal to 2 and 32 are fixed. As a result, the position at which the guide pile 20 is driven is determined.

The setting position of the guide pile 20 can be determined by adjusting the fixing positions of the conductors 32 and 33. Reference numeral 30a is a conductive material receiver fixed to the outer periphery of the conductive pile 30. In addition, when placing this guide pile 20,
Under bad conditions in which the tidal current is fast, the water depth is high, and the waves are high, the guide pile 30 may sway around under the influence thereof. At that time, it is desirable to select a time when the tidal current is slow and the construction is slow.

In this way, the support pile 10 and the guide pile 2
After finishing the construction of 0, support pile cutting and replacement sand work etc. are performed as needed, and thereafter, the supporting members 11 and 21 are attached, and then the guide pile 20 is guided as shown in FIG. Then, the template 4 is laid down.

As shown in FIG. 6, the template 4 is constructed as a framing steel structure having a plane lattice shape.
That is, a large H steel or I type steel is welded and assembled in a grid pattern, and among the many grids, the square grids (portions indicated by virtual circles) are the base piles 3. This is a portion designed so that the foundation pile 3 can be placed in a state of being positioned through the top during the placing. Around the template 4, there are provided a plurality of guide devices 40 that function as guides for the caulson 1 to be sunk when the caisson 1 is sunk. As shown in FIG. 7, the guide device 40 is configured to include an inclined surface 40a that guides the periphery of the bottom of the caisson 1. The template 4 is grounded on land and, for example, as shown in FIGS. 12 and 13, is suspended by a large crane ship K or the like and is transported by sea to the site of its submergence.
For lifting, a large number of lifting wires 50 are used in order to reduce the bending of the template 4.

When the template 4 is sunk, the crane 4 is positioned on the support pile 10 while being aligned with the guide pile 20 while being lifted by the crane ship K, and then gradually hung to sink to the support pile 10 by its own weight. It should be sunk. By doing so, the template 4 is firmly supported near the seabed by the support members 11 and 21 of the support pile 10 and the guide pile 20. Therefore, in this state, the template 4 is fixed to the support pile 10 and the guide pile 20.

After the fixing work of the template 4 is completed, the upper portion of the guide pile 20 is cut as shown in FIG. 3, and thereafter, a large number of foundation piles 3 are set using the template 4 as a ruler. When the foundation piles 3 are laid, the template 4 itself is a framework steel structure in the form of a flat lattice, so the foundation piles 3 should be laid in a form that vertically penetrates the squares of the lattice. By this, it is possible to place with a high accuracy with respect to a target position with a necessary interval therebetween.

After finishing the work of placing each foundation pile 3, next,
As needed, the work of filling the template outer periphery centering sand S is performed, and further, the template underwater concrete work C1 is performed. The filling sand S also serves as a leveling work before performing the underwater concrete work C1, and the underwater concrete work C1 is
It plays a role of integrating a large number of foundation piles 3 including the support piles 10 and the guide piles 20 with the template 4 by concrete. Regarding the thickness of the underwater concrete work C1, considering that the caisson 1 is installed on the template 4, consideration is given so as not to project beyond the upper surface of the template 4.

After the basic steps required to sunk the caisson 1 are completed as described above, the caisson body 1 is then towed to the sunk position as shown in FIG.
While being positioned directly above the template 4, they are successively submerged. When this caisson 1 is sunk, caisson 1
It is performed by injecting seawater as ballast water. In addition, in order to vertically sink the caisson 1 to a desired position, a sinking attitude control and measurement system using a computer-based analysis and image display, etc., is used in addition to the hoist ship, although not particularly shown here. Do it.

In this manner, the bottoms of the caisson 1 are sunk onto the template 4 by accurately substituting the caisson 1 in sequence. This state is shown in FIG.
Here, immediately before the bottom of the caisson 1 is placed on the template 4, if the relative position of the caisson 1 with respect to the template 4 is slightly deviated, the guide device 40 provided around the template 4 works. That is, the caisson 1 is guided to a predetermined position by the action of the inclined surface 40a.

When the bottom of the caisson 1 rests on the template 4, so-called bottomed, the guide device 4
The caisson 1 is firmly positioned with respect to the template 4 by the action of the whole zero. That is, the caisson 1 is restrained by the guide device 40 so as not to move in the horizontal direction. Therefore, the caisson 1 is supported on the template 4 in a stable state. As a result, even if the caisson 1 itself is affected by a tidal current or the like, it does not become unstable due to this. Of course, by fixing the template 4 and the caisson 1 with bolts or the like, they can be supported on the foundation pile in a more stable state.

When the caisson 1 is sunk, the pile head connecting concrete 6 is laid to make the caisson 1 and the support pile 1
0 and the foundation pile 3 including the guide pile 20 are integrated.
This pile head connection concrete 6 is also an underwater concrete casting operation. After that, while the drainage work in the caisson 1 is performed to the required extent, the concrete placing work on the partition wall 2, the side walls 8a and 8b is performed. The drainage work should be performed in accordance with the progress of the concrete placing work on the partition wall 2 and the side walls 8a and 8b, and at least the casson 1 should not be buoyant.

[0031]

As described above, according to the present invention, a plurality of foundation piles are driven on the seabed, and when the caisson is installed and fixed on the foundation piles, before the foundation piles are driven, The process of laying down a template, which is a steel structure that functions as a ruler for placing foundation piles and a saucer when caisson is laid down, and when laying down the template, a plurality of supports for supporting the template at a fixed position where it should be laid down. The steps of placing the support piles in advance, the steps of placing a plurality of foundation piles using the template as a ruler after the template is laid, and the step of placing caisons on the template after the foundation piles are placed and installed. As a result, the foundation piles can be driven with high precision, and the installation precision associated with caisson sinking can be performed with high precision. It is possible to hold the caisson in a stable state by the rate.

Further, before the template is sunk, a guide pile used for ensuring the accuracy when the template is sunk is struck so that the template can be easily sunk and the template can be easily sunk. In addition, it can be performed while offsetting the influence of waves, tidal currents, etc., thereby improving workability and safety.

Further, by mounting the support member for receiving the template on the support pile and the guide pile, it is possible to easily and surely support and fix the template.

Further, by providing a guide device around the template with a sloped surface for guiding the bottom of the caisson to a fixed position on the template when the caisson is sunk, the caisson just before the bottom of the caisson is slightly positioned. Even if it is deviated, it can be easily and accurately settled on the predetermined position. Also, after the caisson bottoms, the caisson can be firmly positioned and held on the template by the action of the guide device.

Furthermore, after the caisson is sunk, by placing underwater concrete for connecting the caisson and the foundation pile, the caisson can be fixed to the foundation pile more reliably and firmly.

[Brief description of drawings]

FIG. 1 is a process drawing showing a caisson installation method according to the present invention.

FIG. 2 is a process drawing showing a caisson installation method according to the present invention.

FIG. 3 is a process drawing showing a caisson installation method according to the present invention.

FIG. 4 is a process drawing showing a caisson installation method according to the present invention.

FIG. 5 is a process drawing showing a caisson installation method according to the present invention.

FIG. 6 is a schematic plan view of a template.

FIG. 7 is a side view of the guide device.

FIG. 8 is a plan view showing a mounting structure of a support member on a guide pile.

FIG. 9 is a view showing a mounting structure of a support member on a support pile.

FIG. 10 is a plan view showing a construction procedure of a guide pile.

FIG. 11 is a side view showing a construction procedure of a guide pile.

FIG. 12 is a side view showing a procedure for lifting the template.

FIG. 13 is a plan view showing how to hang up a template.

[Explanation of symbols]

 1 caisson main body 2 bulkhead 3 foundation pile 4 template 5 void space 6 pile head connection concrete 7 gasket 8a, 8b side wall 10 support pile 11 support member 11a H-shaped steel 11b cross-shaped support member 12 restraint plate 12a slit 20 guide pile 21 support Member 21a H-shaped steel 21b Inclined material 21c Support bracket 30 Guide pile 30a Conductive material receiver 31 Connecting material 32 Conductive material 40 Guide device 40a Slope K Crane ship C Bottom plate concrete S Filling sand C1 Underwater concrete

Claims (5)

[Claims] 1. When placing a plurality of foundation piles on the seabed where the caisson is to be installed and installing and fixing the caisson on the foundation piles, the following steps A, B, C and D are performed. A characteristic caisson installation method. A A step of laying down a template which is a steel structure having a function as a ruler for placing the foundation piles and a saucer when the caisson is laid, before placing the foundation piles. B When precipitating the template, a step of preliminarily driving a plurality of support piles for supporting the template at a predetermined position to be submerged. C A step of driving the plurality of foundation piles using the template as a ruler after the template is sunk. D A step of sinking and installing a caisson on the template after driving the foundation pile. 2. The caisson installation method according to claim 1, wherein before the template is sunk, a guide pile used for ensuring accuracy when the template is sunk is driven. 3. The caisson installation method according to claim 1, wherein a supporting member for receiving the template is attached to each of the support pile and the guide pile. 4. A guide device having a bevel around the template for guiding the bottom of the caisson to a fixed position on the template when the caisson is sunk. The caisson installation method according to any one of 3 to 3. 5. The caisson installation method according to claim 1, further comprising pouring underwater concrete for connecting the caisson and the foundation pile after the caisson is set down.